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Sample records for air pressure effects

  1. 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

  2. EFFECT OF LASER LIGHT ON LASER PLASMAS: Laser plasma at low air pressure

    NASA Astrophysics Data System (ADS)

    Vas'kovskiĭ, Yu M.; Moiseev, V. N.; Rovinskiĭ, R. E.; Tsenina, I. S.

    1993-01-01

    The dynamic and optical characteristics of the laser plasma produced during the application of a CO2 laser pulse to a target have been studied as a function of the ambient air pressure. The changes in the surface roughness of the sample after bombardment were studied as a function of the air pressure. It is concluded from the results that a transition from an air plasma to an erosion plasma occurs at a residual air pressure on the order of 1 torr. The experiment data support the existing picture of the process by which a plasma is produced near the surface of a target in air by laser pulses.

  3. 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

  4. 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

  5. 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

  6. Effects of the air pressure on the wave-packet dynamics of gaseous iodine molecules at room temperature

    NASA Astrophysics Data System (ADS)

    Fan, Rongwei; He, Ping; Chen, Deying; Xia, Yuanqin; Yu, Xin; Wang, Jialing; Jiang, Yugang

    2013-02-01

    Based on ultrafast laser pulses, time-resolved resonance enhancement coherent anti-Stokes Raman scattering (RE-CARS) is applied to investigate wave-packet dynamics in gaseous iodine. The effects of air pressure on the wave-packet dynamics of iodine molecules are studied at pressures ranging from 1.5 Torr to 750 Torr. The RE-CARS signals are recorded in a gas cell filled with a mixture of about 0.3 Torr iodine in air buffer gas at room temperature. The revivals and fractional revival structures in the wave-packet signal are found to gradually disappear with rising air pressure up to 750 Torr, and the decay behaviors of the excited B-state and ground X-state become faster with increasing air pressure, which is due to the collision effects of the molecules and the growing complexity of the spectra at high pressures.

  7. Effects of Photoionization on Similarity Properties of Streamers at Various Pressures in Air

    NASA Astrophysics Data System (ADS)

    Liu, N.; Pasko, V. P.

    2005-12-01

    pressures in air in a point-to-plane discharge geometry. We directly compare our results with recent experiments at atmospheric and near atmospheric pressures in air reported in [Pancheshnyi et al., 2005; Briels et al., 2005]. The modeling results emphasize that the quenching of singlet excited states of molecular nitrogen emitting photoionizing radiation is responsible for non-similar behavior of streamers at pressures higher than several Torr. Our modeling results agree with recent experimental work [Pancheshnyi et al., 2005; Briels et al., 2005] showing that streamers have more and thinner channels and branch more frequently at higher (i.e., near atmospheric) pressures than at lower pressures. The results also demonstrate importance of accounting for effects associated with electrode geometry for interpretation of experimental studies on similarity properties of streamers at various pressures. One of the major unsolved problems in current sprite research is the observed initiation of sprites by very weak lightning discharges [e.g., Hu et al., GRL, 29, 1279, 2002]. It has been proposed that meteoric dust particles in the mesosphere and stratosphere may be involved in the formation of sprites [Zabotin and Wright, GRL, 28, 2593, 2001]. In this talk we will also discuss the implications of the experimental results of Briels et al. [2005] and our related modeling studies for the meteoric dust theory of sprite initiation.

  8. The effectiveness of small changes for pressure redistribution; using the air mattress for small changes.

    PubMed

    Tsuchiya, Sayumi; Sato, Aya; Azuma, Eri; Urushidani, Hiroko; Osawa, Masako; Kadoya, Kanaho; Takamura, Mana; Nunomi, Makiko; Mitsuoka, Akimi; Nishizawa Yokono, Tomoe; Sugama, Junko

    2016-05-01

    Observing small changes (SCs) at specific sites is a new form of managing changes in position. We investigated SCs at specific sites considering interface pressure, contact area, body alignment and physical sensation in nine healthy female adults and evaluated SCs using the air mattress that was divided into six cells (A-F). Thirty-three SC combinations at one or several sites were evaluated. Pressure in the sacral region significantly decreased in 28 SC combinations compared with the supine position (p < 0.05), and the effect of pressure redistribution was greater when SCs were applied at several instead of a single site. The contact area at 17 of the 28 SC combinations significantly increased (p < 0.05). Among sites ranked based on interface pressure, body alignment and physical sensation, SCs at sites BCE, AE and BD were the most favorable. The common feature among these three combinations was that they involved tilting the buttock region and one other site. The findings suggested that SCs at the buttock region could reduce disruptions in alignment as well as the impact on physical sensation caused by the body sinking into the mattress and improve interface pressure redistribution via increased contact area with the mattress. PMID:26827265

  9. 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.

  10. 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

  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. Laser plasma at low air pressure

    NASA Astrophysics Data System (ADS)

    Vas'kovskii, Iu. M.; Moiseev, V. N.; Rovinskii, R. E.; Tsenina, I. S.

    1993-01-01

    The ambient-pressure dependences of the dynamic and optical characteristics of a laser plasma generated by CO2-laser irradiation of an obstacle are investigated experimentally. The change of the sample's surface roughness after irradiation is investigated as a function of air pressure. It is concluded that the transition from the air plasma to the erosion plasma takes place at an air pressure of about 1 mm Hg. The results confirm the existing theory of plasma formation near the surface of an obstacle under the CO2-laser pulse effect in air.

  13. 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.

  14. 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.

  15. 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.

  16. Water loss control using pressure management: life-cycle energy and air emission effects.

    PubMed

    Stokes, Jennifer R; Horvath, Arpad; Sturm, Reinhard

    2013-10-01

    Pressure management is one cost-effective and efficient strategy for controlling water distribution losses. This paper evaluates the life-cycle energy use and emissions for pressure management zones in Philadelphia, Pennsylvania, and Halifax, Nova Scotia. It compares water savings using fixed-outlet and flow-modulated pressure control to performance without pressure control, considering the embedded electricity and chemical consumption in the lost water, manufacture of pipe and fittings to repair breaks caused by excess pressure, and pressure management. The resulting energy and emissions savings are significant. The Philadelphia and Halifax utilities both avoid approximately 130 million liters in water losses annually using flow-modulated pressure management. The conserved energy was 780 GJ and 1900 GJ while avoided greenhouse gas emissions were 50 Mg and 170 Mg a year by Philadelphia and Halifax, respectively. The life-cycle financial and environmental performance of pressure management systems compares favorably to the traditional demand management strategy of installing low-flow toilets. The energy savings may also translate to cost-effective greenhouse gas emission reductions depending on the energy mix used, an important advantage in areas where water and energy are constrained and/or expensive and greenhouse gas emissions are regulated as in California, for example. PMID:23869434

  17. Thermal and hydrodynamic effects of nanosecond discharges in atmospheric pressure air

    NASA Astrophysics Data System (ADS)

    Xu, D. A.; Shneider, M. N.; Lacoste, D. A.; Laux, C. O.

    2014-06-01

    We present quantitative schlieren measurements and numerical analyses of the thermal and hydrodynamic effects of a nanosecond repetitively pulsed (NRP) discharge in atmospheric pressure air at 300 and 1000 K. The plasma is created by voltage pulses at an amplitude of 10 kV and a duration of 10 ns, applied at a frequency of 1-10 kHz between two pin electrodes separated by 2 or 4 mm. The electrical energy of each pulse is of the order of 1 mJ. We recorded single-shot schlieren images starting from 50 ns to 3 µs after the discharge. The time-resolved images show the shock-wave propagation and the expansion of the heated gas channel. Gas density profiles simulated in 1D cylindrical coordinates have been used to reconstruct numerical schlieren images for comparison with experimental ones. We propose an original method to determine the initial gas temperature and the fraction of energy transferred into ultrafast gas heating, using a comparison of the contrast profiles obtained from experimental and numerical schlieren images. This method is found to be much more sensitive to these parameters than the direct comparison of measured and predicted shock-wave and heated channel radii. The results show that a significant fraction of the electric energy is converted into gas heating within a few tens of ns. The values range from about 25% at a reduced electric field of 164 Td to about 75% at 270 Td, with a strong dependance on the initial gas temperature. These experiments support the fast heating processes via dissociative quenching of N2(B3 Πg, C3 Πu) by molecular oxygen.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. Radiation pressure and air drag effects on the orbit of the balloon satellite 1963 30D

    NASA Technical Reports Server (NTRS)

    Slowey, J. W.

    1974-01-01

    Computed orbits of the balloon satellite 1963 30D are given every 2 days over an interval of 456 days near the beginning of the satellite's lifetime and an interval of 824 days near the end of its lifetime. The effects of radiation pressure on the satellite are examined in some detail. It is found that the variations in all the elements can be represented by use of a single parameter to specify the effect of diffuse reflection from the satellite's surface, and that this parameter remains constant, or nearly so, during the entire 7-year lifetime. Success in obtaining a consistent representation of the radiation-pressure effects is ascribed to the inclusion of the effects of terrestrial radiation pressure, using a model for the earth's albedo that includes seasonal and latitudinal variations. Anomalous effects in the orbital acceleration, as well as in the other elements, are represented quite well by including a small force at right angle to the solar direction and by allowing this to rotate about the solar direction. This implies that the satellite is aspherical, that it is rotating, and that the axis of rotation precesses.

  3. Effect of pressure and fuel-air unmixedness on NO{sub x} emissions from industrial gas turbine burners

    SciTech Connect

    Biagioli, Fernando; Guethe, Felix

    2007-10-15

    The effect of fuel-air unmixedness on NO{sub x} emissions from industrial lean premixed gas turbine burners fueled with natural gas is analyzed in the pressure range from 1 to 30 bar. The analysis is based on a model where NO{sub x} production is split, according to a Damkoehler number criterion, into a ''prompt'' (fast) contribution generated within the very narrow instantaneous heat release region (flamelet) and a ''postflame'' (slow) one, generated in the combustion products. Using GRI3.0 chemical kinetics, it is found that (a) the prompt NO{sub x} contribution is approximately a factor of 3 less sensitive to adiabatic flame temperature variations than postflame NO{sub x} and (b) prompt and postflame NO{sub x} change with pressure respectively according to an exponent {alpha}{sub PR}{approx_equal}-0.45 and {alpha}{sub PF}{approx_equal}0.67. It is shown that total NO{sub x} emissions change from being mostly of prompt type at 1 bar to being mostly of postflame type at 30 bar, so that the effect of fuel-air unmixedness on NO{sub x} emissions significantly increases with increasing pressure. The combination of these findings yields a negative NO{sub x} pressure exponent under fully premixed conditions across a rather large range of equivalence ratios but a positive one for levels of fuel-air unmixedness typical of industrial burners. This result is confirmed by the application of the NO{sub x} model in the large eddy simulation of the ALSTOM EV double cone burner, which gives, in line with experimental data, an NO{sub x} pressure exponent growing, with equivalence ratio, from {approx_equal}0.1 to {approx_equal}0.67. (author)

  4. 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

  5. Effect of the initial pressure on the characteristics of the flame propagation in hydrogen-propane-air mixtures

    NASA Astrophysics Data System (ADS)

    Cheng, Guanbing; Bauer, Pascal; Zitoun, Ratiba

    2014-08-01

    This paper is aimed at an experimental investigation on effects of initial pressure on flame propagation characteristics of binary fuels hydrogen-propane-air mixtures at room temperature. The experiments are performed in a square channel equipped with perforated orifice obstacles. Four initial pressures are examined. Based on pressure transducers along the channel, the flame velocity, maximum pressure of the front peak and characteristic distances are measured. Successive stages are observed as flame propagates: (i) a velocity increase at the beginning, (ii) a velocity equal to the sound speed of combustion products and (iii) a decrease of the velocity. When the initial pressure is more important, the flame velocity and the maximal pressure of the front peak are higher, which yields a shorter characteristic distance of flame propagation. By means of a Schlieren photography technique, the physical mechanisms of flame propagation are identified in its initial stage. The physical mechanisms such as flame surface area increase and combustion product expansion as well as delayed combustion between two adjacent plates are responsible for flame acceleration upon its initial stage. The oscillations of the centerline flame velocity are due to the constrained-expanded structure of flow in reactants ahead of flame when it crosses the plates.

  6. Air Pressure Controlled Mass Measurement System

    NASA Astrophysics Data System (ADS)

    Zhong, Ruilin; Wang, Jian; Cai, Changqing; Yao, Hong; Ding, Jin'an; Zhang, Yue; Wang, Xiaolei

    Mass measurement is influenced by air pressure, temperature, humidity and other facts. In order to reduce the influence, mass laboratory of National Institute of Metrology, China has developed an air pressure controlled mass measurement system. In this system, an automatic mass comparator is installed in an airtight chamber. The Chamber is equipped with a pressure controller and associate valves, thus the air pressure can be changed and stabilized to the pre-set value, the preferred pressure range is from 200 hPa to 1100 hPa. In order to keep the environment inside the chamber stable, the display and control part of the mass comparator are moved outside the chamber, and connected to the mass comparator by feed-throughs. Also a lifting device is designed for this system which can easily lift up the upper part of the chamber, thus weights can be easily put inside the mass comparator. The whole system is put on a marble platform, and the temperature and humidity of the laboratory is very stable. The temperature, humidity, and carbon dioxide content inside the chamber are measured in real time and can be used to get air density. Mass measurement cycle from 1100 hPa to 200 hPa and back to 1100 hPa shows the effective of the system.

  7. 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.

  8. 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

  9. On the effect of pressure, oxygen concentration, air flow and gravity on simulated pool fires

    NASA Technical Reports Server (NTRS)

    Torero, J. L.; Most, J. M.; Joulain, P.

    1995-01-01

    The initial development of a fire is characterized by the establishment of a diffusion flame over the surface of a the condensed fuel and is particularly influenced by gravity, with most of the gaseous flow induced by natural convection. Low initial momentum of the fuel vapor, strong buoyant flows induced by the hot post-combustion gases and consequently low values of the Froude number (inertia-gravity forces ratio) are typical of this kind of scenario. An experimental study is conducted by using a porous burner to simulate the burning of a horizontal combustible surface. Ethane is used as fuel and different mixtures of oxygen and nitrogen as oxidizer. The magnitude of the fuel injection velocities is restricted to values that will keep the Froude number on the order of 10-5, when calculated at normal gravity and pressure, which are characteristic of condensed fuel burning. Two different burners are used, a circular burner (62 mm diameter) placed inside a cylindrical chamber (0.3 m diameter and 1.0 m height) and a rectangular burner (50 mm wide by 200 mm long) placed in a wind tunnel (350 mm long) of rectangular cross section (120 mm wide and 90 mm height). The first burner is used to study the effect of pressure and gravity in the absence of a forced flow parallel to the surface. The second burner is used to study the effect of a forced flow parallel to the burner surface as well as the effect of oxygen concentration in the oxidizer flow. In this case experiments are also conducted at different gravity levels (micro-gravity, 0.2 g(sub 0), g(sub 0) and 1.8 g(sub 0)) to quantify the relative importance of buoyancy.

  10. Using air pressure cells to evaluate the effect of soil environment on the transmission of soilborne viruses of wheat.

    PubMed

    Cadle-Davidson, L; Schindelbeck, R R; van Es, H M; Gray, S M; Bergstrom, G C

    2003-09-01

    ABSTRACT An air pressure cell, a laboratory tool that precisely controls soil matric potential, was utilized in a novel approach to investigate the epidemiology and management of soilborne disease. Matric potentials of -1, -5, -20, and -40 kPa were established in cores of field soil infested with Wheat soilborne mosaic virus (WSBMV) and its presumed vector Polymyxa graminis. Equilibrated soil cores were planted to wheat (Triticum aestivum), and after intervals of growth under controlled environment, virus transmission was assessed by serological detection of the virus in washed roots. Transmission occurred at all but the driest soil matric potential tested, -40 kPa, in which only pores with a diameter of 7.4 mum or less were water-filled, possibly obstructing movement of P. graminis zoospores. By starting plants at -40 kPa for 10.5 days and then watering them to conducive matric potential, we found that WSBMV transmission occurred between 12 to 24 h at 15 degrees C, and within 36 h at 20 degrees C. No significant transmission occurred within 96 h at 6.5 degrees C. In contrast, transmission of Wheat spindle streak mosaic virus (WSSMV) did not occur at 15 degrees C (the only transmission temperature tested), suggesting either that WSSMV is unable to establish infection at 15 degrees C or that a different vector is involved. The air pressure cell is a novel tool with many potential applications in research on the epidemiology and management of soilborne pathogens. Applications of the precise environmental control attained through the use of air pressure cells range from assessing the effects of cultural practices on soilborne inoculum to standardized virulence assays for soilborne pathogens to preliminary screens of host resistance and pesticide efficacy. PMID:18944097

  11. Analytical evaluation of effect of equivalence ratio inlet-air temperature and combustion pressure on performance of several possible ram-jet fuels

    NASA Technical Reports Server (NTRS)

    Tower, Leonard K; Gammon, Benson E

    1953-01-01

    The results of an analytical investigation of the theoretical air specific impulse performance and adiabatic combustion temperatures of several possible ram-jet fuels over a range of equivalence ratios, inlet-air temperatures, and combustion pressures, is presented herein. The fuels include octane-1, 50-percent-magnesium slurry, boron, pentaborane, diborane, hydrogen, carbon, and aluminum. Thermal effects from high combustion temperatures were found to effect considerably the combustion performance of all the fuels. An increase in combustion pressure was beneficial to air specific impulse at high combustion temperatures. The use of these theoretical data in engine operation and in the evaluation of experimental data is described.

  12. 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.

  13. Effects of air breathing engine plumes on SSV orbiter subsonic wing pressure distribution, volume 2

    NASA Technical Reports Server (NTRS)

    Soard, T.

    1974-01-01

    Data presented were obtained during wind tunnel tests of a 0.0405-scale model of the -89B ferry configuration of the space shuttle vehicle orbiter. These tests were conducted in the Rockwell International low speed wind tunnel (NAAL). The primary test objective was to investigate orbiter wing pressure distributions resulting from nacelle plumes above and below the wing. Three six-engine nacelle configurations were tested. One configuration has a twin-podded nacelle mounted above each wing and the others had one mounted below each wing. Both had a centerline twin-podded nacelle mounted below the wing. Wing pressure distribution was determined by locating static pressure bugs on the upper and lower surfaces of the left wing. Pressure bugs were also located on the upper and lower surfaces of the body flap and on the B12 afterbody fairing when it was installed. Base and balance cavity pressures were recorded and a strain gage instrumented beam in the right wing measured elevon hinge moments and normal forces.

  14. Effect of inlet-air humidity, temperature, pressure, and reference Mach number on the formation of oxides of nitrogen in a gas turbine combustor

    NASA Technical Reports Server (NTRS)

    Marchionna, N. R.; Diehl, L. A.; Trout, A. M.

    1973-01-01

    Tests were conducted to determine the effect of inlet air humidity on the formation of oxides of nitrogen (NOx) from a gas turbine combustor. Combustor inlet air temperature ranged from 506 K (450 F) to 838 K (1050 F). The tests were primarily run at a constant pressure of 6 atmospheres and reference Mach number of 0.065. The NOx emission index was found to decrease with increasing inlet air humidity at a constant exponential rate: NOx = NOx0e-19H (where H is the humidity and the subscript 0 denotes the value at zero humidity). the emission index increased exponentially with increasing normalized inlet air temperature to the 1.14 power. Additional tests made to determine the effect of pressure and reference Mach number on NOx showed that the NOx emission index varies directly with pressure to the 0.5 power and inversely with reference Mach number.

  15. Air-activated chemical warming devices: effects of oxygen and pressure.

    PubMed

    Raleigh, G; Rivard, R; Fabus, S

    2005-01-01

    Air-activated chemical warming devices use an exothermic chemical reaction of rapidly oxidizing iron to generate heat for therapeutic purposes. Placing these products in a hyperbaric oxygen environment greatly increases the supply of oxidant and thus increases the rate of reaction and maximum temperature. Testing for auto-ignition and maximum temperatures attained by ThermaCare Heat Wraps, Playtex Heat Therapy, and Heat Factory disposable warm packs under ambient conditions and under conditions similar to those encountered during hyperbaric oxygen treatments in monoplace and multiplace hyperbaric chambers (3 atm abs and > 95% oxygen) revealed a maximum temperature of 269 degrees F (132 degrees C) with no spontaneous ignition. The risk of thermal burn injury to adjacent skin may be increased significantly if these devices are used under conditions of hyperbaric oxygen. PMID:16509287

  16. 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.

  17. Calcium phosphate growth beneath a polycationic monolayer at the air-water interface: effects of oscillating surface pressure on mineralization.

    PubMed

    Junginger, Mathias; Bleek, Katrin; Kita-Tokarczyk, Katarzyna; Reiche, Jürgen; Shkilnyy, Andriy; Schacher, Felix; Müller, Axel H E; Taubert, Andreas

    2010-11-01

    The self-assembly of the amphiphilic block copolymer poly(butadiene)-block-poly[2-(dimethylamino)ethyl methacrylate] at the air-water interface and the mineralization of the monolayers with calcium phosphate was investigated at different pH values. As expected for polyelectrolytes, the subphase pH strongly affects the monolayer properties. The focus of the current study, however, is on the effect of an oscillating (instead of a static) polymer monolayer on calcium phosphate mineralization. Monitoring of the surface pressure vs. mineralization time shows that the monolayer is quite stable if the mineralization is performed at pH 8. In contrast, the monolayer at pH 5 shows a measurable decrease of the surface pressure already after ca. 2 h of mineralization. Transmission electron microscopy reveals that mineralization at low pH under constant oscillation leads to small particles, which are arranged in circular features and larger entities with holes of ca. 200 nm. The larger features with the holes disappear as the mineralization is continued in favor of the smaller particles. These grow with time and form necklace-like architectures of spherical particles with a uniform diameter. In contrast, mineralization at pH 8 leads to very uniform particle morphologies already after 2 h. The mineralization products consist of a circular feature with a dark dot in the center. The increasing contrast of the precipitates in the electron micrographs with mineralization time indicates an increasing degree of mineralization vs. reaction time. The study therefore shows that mechanical effects on mineralization at interfaces are quite complex. PMID:20835481

  18. Calcium phosphate growth beneath a polycationic monolayer at the air-water interface: effects of oscillating surface pressure on mineralization

    NASA Astrophysics Data System (ADS)

    Junginger, Mathias; Bleek, Katrin; Kita-Tokarczyk, Katarzyna; Reiche, Jürgen; Shkilnyy, Andriy; Schacher, Felix; Müller, Axel H. E.; Taubert, Andreas

    2010-11-01

    The self-assembly of the amphiphilic block copolymer poly(butadiene)-block-poly[2-(dimethylamino)ethyl methacrylate] at the air-water interface and the mineralization of the monolayers with calcium phosphate was investigated at different pH values. As expected for polyelectrolytes, the subphase pH strongly affects the monolayer properties. The focus of the current study, however, is on the effect of an oscillating (instead of a static) polymer monolayer on calcium phosphate mineralization. Monitoring of the surface pressure vs. mineralization time shows that the monolayer is quite stable if the mineralization is performed at pH 8. In contrast, the monolayer at pH 5 shows a measurable decrease of the surface pressure already after ca. 2 h of mineralization. Transmission electron microscopy reveals that mineralization at low pH under constant oscillation leads to small particles, which are arranged in circular features and larger entities with holes of ca. 200 nm. The larger features with the holes disappear as the mineralization is continued in favor of the smaller particles. These grow with time and form necklace-like architectures of spherical particles with a uniform diameter. In contrast, mineralization at pH 8 leads to very uniform particle morphologies already after 2 h. The mineralization products consist of a circular feature with a dark dot in the center. The increasing contrast of the precipitates in the electron micrographs with mineralization time indicates an increasing degree of mineralization vs. reaction time. The study therefore shows that mechanical effects on mineralization at interfaces are quite complex.

  19. Effect of airstream velocity on mean drop diameters of water sprays produced by pressure and air atomizing nozzles. [for combustion studies

    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.

  20. The effect of the partial pressure of water vapor on the surface tension of the liquid water-air interface.

    PubMed

    Pérez-Díaz, José L; Álvarez-Valenzuela, Marco A; García-Prada, Juan C

    2012-09-01

    Precise measurements of the surface tension of water in air vs. humidity at 5, 10, 15, and 20 °C are shown. For constant temperature, surface tension decreases linearly for increasing humidity in air. These experimental data are in good agreement with a simple model based on Newton's laws here proposed. It is assumed that evaporating molecules of water are ejected from liquid to gas with a mean normal component of the speed of "ejection" greater than zero. A high humidity in the air reduces the net flow of evaporating water molecules lowering the effective surface tension on the drop. Therefore, just steam in air acts as an effective surfactant for the water-air interface. It can partially substitute chemical surfactants helping to reduce their environmental impact. PMID:22717083

  1. Evaluation of effect of continuous positive airway pressure during cardiopulmonary bypass on cardiac de-airing after open heart surgery in randomized clinical trial

    PubMed Central

    Mansour, Mojtaba; Massodnia, Nasim; Mirdehghan, Abolghasem; Bigdelian, Hamid; Massoumi, Gholamreza; Alavi, Zeinab Rafieipour

    2014-01-01

    Background: Cardiac and pulmonary veins de-airing are of the most important steps during open heart surgery. This study evaluates the effect of continuous positive airway pressure (CPAP) on air trapping in pulmonary veins and on quality of de-airing procedure. Materials and Methods: This randomized prospective double blind clinical trial conducted on 40 patients. In the control group: During cardiopulmonary bypass (CPB), the ventilator was turned off and adjustable pressure limit (APL) valve was placed in SPONT position. In CPAP group: During CPB, after turning the ventilator off, the flow of oxygen flow was maintained at the rate of 0.5 L/min and the APL valve was placed in MAN position on 20 mbar. During cardiopulmonary bypass (CPB) weaning, the patients were observed for air bubbles in left atrium by using transesophageal echocardiography. Results: The mean de-airing time after the start of mechanical ventilation in CPAP group (n = 20) was significantly lower than the control group (n = 20) (P = 0.0001). The mean time of the left atrium air bubbles occupation as mild (P = 0.004), moderate (P = 0.0001) and severe (P = 0.015) grading was significantly lower in CPAP group. Conclusions: By CPAP at 20 mbar during CPB in open heart surgery, de-airing process can be down in better quality and in significantly shorter time. PMID:24949307

  2. Effect of aviation fuel type and fuel injection conditions on the spray characteristics of pressure swirl and hybrid air blast fuel injectors

    NASA Astrophysics Data System (ADS)

    Feddema, Rick

    Feddema, Rick T. M.S.M.E., Purdue University, December 2013. Effect of Aviation Fuel Type and Fuel Injection Conditions on the Spray Characteristics of Pressure Swirl and Hybrid Air Blast Fuel Injectors. Major Professor: Dr. Paul E. Sojka, School of Mechanical Engineering Spray performance of pressure swirl and hybrid air blast fuel injectors are central to combustion stability, combustor heat management, and pollutant formation in aviation gas turbine engines. Next generation aviation gas turbine engines will optimize spray atomization characteristics of the fuel injector in order to achieve engine efficiency and emissions requirements. Fuel injector spray atomization performance is affected by the type of fuel injector, fuel liquid properties, fuel injection pressure, fuel injection temperature, and ambient pressure. Performance of pressure swirl atomizer and hybrid air blast nozzle type fuel injectors are compared in this study. Aviation jet fuels, JP-8, Jet A, JP-5, and JP-10 and their effect on fuel injector performance is investigated. Fuel injector set conditions involving fuel injector pressure, fuel temperature and ambient pressure are varied in order to compare each fuel type. One objective of this thesis is to contribute spray patternation measurements to the body of existing drop size data in the literature. Fuel droplet size tends to increase with decreasing fuel injection pressure, decreasing fuel injection temperature and increasing ambient injection pressure. The differences between fuel types at particular set conditions occur due to differences in liquid properties between fuels. Liquid viscosity and surface tension are identified to be fuel-specific properties that affect the drop size of the fuel. An open aspect of current research that this paper addresses is how much the type of aviation jet fuel affects spray atomization characteristics. Conventional aviation fuel specifications are becoming more important with new interest in alternative

  3. Effect of dielectric material on bipolar nanosecond pulse diffuse dielectric barrier discharge in air at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Tang, Kai; Wang, Wenchun; Yang, Dezheng; Zhang, Shuai; Yang, Yang; Liu, Zhijie

    2013-08-01

    In this paper, dielectric plates made by ceramic, quartz and polytetrafluoroethylene (PTFE) respectively are employed to generate low gas temperature, diffuse dielectric barrier discharge plasma by using a needle-plate electrode configuration in air at atmospheric pressure. Both discharge images and the optical emission spectra are obtained while ceramic, quartz and PTFE are used as dielectric material. Plasma gas temperature is also calculated by comparing the experimental emission spectra with the best fitted spectra of N2 (C3Πu → B3Πg 1-3) and N2 (C3Πu → B3Πg 0-2). The effects of different pulse peak voltages and gas gap distances on the emission intensity of N2 (C3Πu → B3Πg, 0-0, 337.1 nm) and the plasma area on dielectric surface are investigated while ceramic, quartz and PTFE are used as dielectric material. It is found that the permittivity of dielectric material plays an important role in the discharge homogeneity, plasma gas temperature, emission spectra intensity of the discharge, etc. Dielectric with higher permittivity i.e., ceramic means brighter discharge luminosity and stronger emission spectra intensity of N2 (C3Πu → B3Πg, 0-0, 337.1 nm) among the three dielectric materials. However, more homogeneous, larger plasma area on dielectric surface and lower plasma gas temperature can be obtained under dielectric with lower permittivity i.e., PTFE. The emission spectra intensity and plasma gas temperature of the discharge while the dielectric plate is made by quartz are smaller than that while ceramic is used as dielectric material and bigger than that when PTFE is used as dielectric material.

  4. Effect of dielectric material on bipolar nanosecond pulse diffuse dielectric barrier discharge in air at atmospheric pressure.

    PubMed

    Tang, Kai; Wang, Wenchun; Yang, Dezheng; Zhang, Shuai; Yang, Yang; Liu, Zhijie

    2013-08-01

    In this paper, dielectric plates made by ceramic, quartz and polytetrafluoroethylene (PTFE) respectively are employed to generate low gas temperature, diffuse dielectric barrier discharge plasma by using a needle-plate electrode configuration in air at atmospheric pressure. Both discharge images and the optical emission spectra are obtained while ceramic, quartz and PTFE are used as dielectric material. Plasma gas temperature is also calculated by comparing the experimental emission spectra with the best fitted spectra of N2 (C(3)Πu→B(3)Πg 1-3) and N2 (C(3)Πu→B(3)Πg 0-2). The effects of different pulse peak voltages and gas gap distances on the emission intensity of N2 (C(3)Πu→B(3)Πg, 0-0, 337.1 nm) and the plasma area on dielectric surface are investigated while ceramic, quartz and PTFE are used as dielectric material. It is found that the permittivity of dielectric material plays an important role in the discharge homogeneity, plasma gas temperature, emission spectra intensity of the discharge, etc. Dielectric with higher permittivity i.e., ceramic means brighter discharge luminosity and stronger emission spectra intensity of N2 (C(3)Πu→B(3)Πg, 0-0, 337.1 nm) among the three dielectric materials. However, more homogeneous, larger plasma area on dielectric surface and lower plasma gas temperature can be obtained under dielectric with lower permittivity i.e., PTFE. The emission spectra intensity and plasma gas temperature of the discharge while the dielectric plate is made by quartz are smaller than that while ceramic is used as dielectric material and bigger than that when PTFE is used as dielectric material. PMID:23673240

  5. Effects of sudden air pressure changes on hospital admissions for cardiovascular diseases in Prague, 1994-2009

    NASA Astrophysics Data System (ADS)

    Plavcová, Eva; Kyselý, Jan

    2014-08-01

    Sudden weather changes have long been thought to be associated with negative impacts on human health, but relatively few studies have attempted to quantify these relationships. We use large 6-h changes in atmospheric pressure as a proxy for sudden weather changes and evaluate their association with hospital admissions for cardiovascular diseases (CVD). Winter and summer seasons and positive and negative pressure changes are analysed separately, using data for the city of Prague (population 1.2 million) over a 16-year period (1994-2009). We found that sudden pressure drops in winter are associated with significant rise in hospital admissions. Increased CVD morbidity was observed neither for pressure drops in summer nor pressure increases in any season. Analysis of synoptic weather maps shows that large pressure drops in winter are associated with strong zonal flow and rapidly moving low-pressure systems with centres over northern Europe and atmospheric fronts affecting western and central Europe. Analysis of links between passages of strong atmospheric fronts and hospital admissions, however, shows that the links disappear if weather changes are characterised by frontal passages. Sudden pressure drops in winter are associated also with significant excess CVD mortality. As climate models project strengthening of zonal circulation in winter and increased frequency of windstorms, the negative effects of such weather phenomena and their possible changes in a warmer climate of the twenty-first century need to be better understood, particularly as their importance in inducing excess morbidity and mortality in winter may increase compared to cold spells.

  6. Modelling of heat and mass transfer in a granular medium during high-temperature air drying. Effect of the internal gas pressure

    NASA Astrophysics Data System (ADS)

    Othmani, Hammouda; Hassini, Lamine; Lamloumi, Raja; El Cafsi, Mohamed Afif

    2016-02-01

    A comprehensive internal heat and water transfer model including the gas pressure effect has been proposed in order to improve the industrial high-temperature air drying of inserts made of agglomerated sand. In this model, the internal gas phase pressure effect was made perfectly explicit, by considering the liquid and vapour transfer by filtration and the liquid expulsion at the surface. Wet sand enclosed in a tight cylindrical glass bottle dried convectively at a high temperature was chosen as an application case. The model was validated on the basis of the experimental average water content and core temperature curves for drying trials at different operating conditions. The simulations of the spatio-temporal distribution of internal gas pressure were performed and interpreted in terms of product potential damage. Based on a compromise between the drying time and the pressure increase, a simple drying cycle was implemented in order to optimize the drying process.

  7. [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

  8. Effect of initial moisture content on the in-vessel composting under air pressure of organic fraction of municipal solid waste in Morocco

    PubMed Central

    2013-01-01

    This study aimed to evaluate the effect of initial moisture content on the in-vessel composting under air pressure of organic fraction of municipal solid waste in Morocco in terms of internal temperature, produced gases quantity, organic matter conversion rate, and the quality of the final composts. For this purpose, in-vessel bioreactor was designed and used to evaluate both appropriate initial air pressure and appropriate initial moisture content for the composting process. Moreover, 5 experiments were carried out within initial moisture content of 55%, 65%, 70%, 75% and 85%. The initial air pressure and the initial moisture content of the mixture showed a significant effect on the aerobic composting. The experimental results demonstrated that for composting organic waste, relatively high moisture contents are better at achieving higher temperatures and retaining them for longer times. This study suggested that an initial moisture content of around 75%, under 0.6 bar, can be considered as being suitable for efficient composting of organic fraction of municipal solid waste. These last conditions, allowed maximum value of temperature and final composting product with good physicochemical properties as well as higher organic matter degradation and higher gas production. Moreover, final compost obtained showed good maturity levels and can be used for agricultural applications. PMID:23369502

  9. Effects of Atmospheric-Pressure N2, He, Air, and O2 Microplasmas on Mung Bean Seed Germination and Seedling Growth.

    PubMed

    Zhou, Renwu; Zhou, Rusen; Zhang, Xianhui; Zhuang, Jinxing; Yang, Size; Bazaka, Kateryna; Ken Ostrikov, Kostya

    2016-01-01

    Atmospheric-pressure N2, He, air, and O2 microplasma arrays have been used to investigate the effects of plasma treatment on seed germination and seedling growth of mung bean in aqueous solution. Seed germination and growth of mung bean were found to strongly depend on the feed gases used to generate plasma and plasma treatment time. Compared to the treatment with atmospheric-pressure O2, N2 and He microplasma arrays, treatment with air microplasma arrays was shown to be more efficient in improving both the seed germination rate and seedling growth, the effect attributed to solution acidification and interactions with plasma-generated reactive oxygen and nitrogen species. Acidic environment caused by air discharge in water may promote leathering of seed chaps, thus enhancing the germination rate of mung bean, and stimulating the growth of hypocotyl and radicle. The interactions between plasma-generated reactive species, such as hydrogen peroxide (H2O2) and nitrogen compounds, and seeds led to a significant acceleration of seed germination and an increase in seedling length of mung bean. Electrolyte leakage rate of mung bean seeds soaked in solution activated using air microplasma was the lowest, while the catalase activity of thus-treated mung bean seeds was the highest compared to other types of microplasma. PMID:27584560

  10. Effects of Atmospheric-Pressure N2, He, Air, and O2 Microplasmas on Mung Bean Seed Germination and Seedling Growth

    PubMed Central

    Zhou, Renwu; Zhou, Rusen; Zhang, Xianhui; Zhuang, Jinxing; Yang, Size; Bazaka, Kateryna; (Ken) Ostrikov, Kostya

    2016-01-01

    Atmospheric-pressure N2, He, air, and O2 microplasma arrays have been used to investigate the effects of plasma treatment on seed germination and seedling growth of mung bean in aqueous solution. Seed germination and growth of mung bean were found to strongly depend on the feed gases used to generate plasma and plasma treatment time. Compared to the treatment with atmospheric-pressure O2, N2 and He microplasma arrays, treatment with air microplasma arrays was shown to be more efficient in improving both the seed germination rate and seedling growth, the effect attributed to solution acidification and interactions with plasma-generated reactive oxygen and nitrogen species. Acidic environment caused by air discharge in water may promote leathering of seed chaps, thus enhancing the germination rate of mung bean, and stimulating the growth of hypocotyl and radicle. The interactions between plasma-generated reactive species, such as hydrogen peroxide (H2O2) and nitrogen compounds, and seeds led to a significant acceleration of seed germination and an increase in seedling length of mung bean. Electrolyte leakage rate of mung bean seeds soaked in solution activated using air microplasma was the lowest, while the catalase activity of thus-treated mung bean seeds was the highest compared to other types of microplasma. PMID:27584560

  11. Effects of Atmospheric Pressure Air Plasma Pretreatment on the Seed Germination and Early Growth of Andrographis paniculata

    NASA Astrophysics Data System (ADS)

    Tong, Jiayun; He, Rui; Zhang, Xiaoli; Zhan, Ruoting; Chen, Weiwen; Yang, Size

    2014-03-01

    The objective of this paper is to demonstrate whether air plasma can change the seed germination characteristics, seedling emergence, as well as biochemical reactivity, in Andrographis paniculata (A. paniculata) seedlings by modifying the seed coat and finding a beneficial treatment dose. Eight treatment doses and one control were used to conduct electrical conductivity determination, a germination test, a seedling emergence test and a biochemical assay. The results showed that after being treated with air plasma excited at 5950 V for 10 s, the permeability of the seeds was improved significantly, resulting in the acceleration of seed germination and seedling emergence. In the meantime, the catalase activity and catalase isoenzyme expression were also improved, while the malondialdehyde content in the seedlings was decreased (which means greater counteraction with environmental stress). After being treated with 4250 V for 10 s and 5950 V for 20 s, the seed germination was enhanced, but without an obvious change in seedling emergence. However, after treatment with 3400 V for 20 s and 5100 V for 10 s, the permeability of the seeds was decreased, resulting in a delay in seedling emergence. These results indicate that air plasma can change the physiological and biochemical characteristics of Andrographis paniculata seeds by modifying the seed coat, combined with the effects of the active plasma species, and that different treating doses have different effects.

  12. Effects of Environmental Humidity and Temperature on Sterilization Efficiency of Dielectric Barrier Discharge Plasmas in Atmospheric Pressure Air

    NASA Astrophysics Data System (ADS)

    Kikuchi, Yusuke; Miyamae, Masanori; Nagata, Masayoshi; Fukumoto, Naoyuki

    2011-01-01

    The inactivation of Bacillus atrophaeus spores by a dielectric barrier discharge (DBD) plasma in atmospheric humid air was investigated in order to develop a low-temperature, low-cost, and high-speed plasma sterilization technique. The biological indicators covered with a Tyvek sheet were set just outside the DBD plasma region, where air temperature and humidity as a discharge gas were precisely controlled by an environmental test chamber. The results show that the inactivation of B. atrophaeus spores was found to be dependent strongly on humidity, and was completed within 15 min at a relative humidity of 90% and a temperature of 30 °C. The treatment time for sterilization is shorter than those of conventional sterilization methods using ethylene oxide gas and dry heat treatment. The inactivation rates depend on not only relative humidity but also temperature, so that water content in air could determine the generation of reactive species such as hydroxyl radicals that are effective for the inactivation of B. atrophaeus spores.

  13. Three Modes of Air Atmospheric Pressure Plasma

    NASA Astrophysics Data System (ADS)

    Mohamed, Abdel-Aleam H.

    2015-09-01

    Atmospheric pressure plasma jet operating in air have gained a high interest due to its various applications in industry and biomedical. The presented air plasma jet system is consisted of stainless steel hollow needle electrode of 1 mm inner diameter which is covered with a quartz tube with a 1 mm diameter side hole. The hole is above the tube nozzle by 5 mm and it is covered by a copper ring which is connected to the ground. The needle is connected to sinusoidal 27 kHz high voltage power supply (25 kV) though a current limiting resistor of 50 k Ω. The tested distance between the needle tip and the side hole was 1 mm or 2.1 mm gape. The electric and plasma jet formation characteristics show three modes of operations. Through these modes the plasma length changes with air flow rate to increase in the first mode and to confine inside the quartz tube in the second mode, then it start to eject from the nozzle again and increase with flow rate to reach a maximum length of 7 mm at 4.5 SLM air flow rate in the third mode. The measured gas temperature of the plasma jet can approach room temperature (300 K). Moreover, the plasma jet emission spectra shows the presence of reactive O and OH radical in the plasma jet. These results indicate that the generated air plasma jet can be used a plasma sterilization.

  14. Effects of low-pressure air on oxygen contamination and lithium corrosion of a tantalum alloy, T-111, at 980 and 1260 C

    NASA Technical Reports Server (NTRS)

    Gahn, R. F.

    1974-01-01

    The effects were studied of low-pressure air on contamination and corrosion in the tantalum alloy T-111/lithium system at 980 and 1260 C. Capsules of T-111 containing lithium were exposed to six vacuum levels between 1 x 10 to the 8th power and 0.0003 torr by controlled air leakage into a vacuum system. Capsules exposed at 980 C and 0.0002 torr failed from intragranular oxidation. The remainder of the capsules completed the 96-hour tests. The depth of oxygen contamination was greater at 980 C than at 1260 C. Tests made at 0.0001 and 0.00001 torr levels caused large increases in the oxygen content of the T-111. Tests at 0.000001 torr or less produced no significant contamination. No lithium corrosion of the T-111 was observed under any of the conditions.

  15. Numerical study of the effect of water content on OH production in a pulsed-dc atmospheric pressure helium-air plasma jet

    NASA Astrophysics Data System (ADS)

    Mu-Yang, Qian; Cong-Ying, Yang; Zhen-dong, Wang; Xiao-Chang, Chen; San-Qiu, Liu; De-Zhen, Wang

    2016-01-01

    A numerical study of the effect of water content on OH production in a pulsed-dc atmospheric pressure helium-air plasma jet is presented. The generation and loss mechanisms of the OH radicals in a positive half-cycle of the applied voltage are studied and discussed. It is found that the peak OH density increases with water content in air (varying from 0% to 1%) and reaches 6.3×1018 m-3 when the water content is 1%. Besides, as the water content increases from 0.01% to 1%, the space-averaged reaction rate of three-body recombination increases dramatically and is comparable to those of main OH generation reactions. Project supported by the National Natural Science Foundation of China (Grant No. 11465013), the Natural Science Foundation of Jiangxi Province, China (Grant No. 20151BAB212012), and the International Science and Technology Cooperation Program of China (Grant No. 2015DFA61800).

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. 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...

  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. Health Effects of Air Pollution

    MedlinePlus

    ... Health effects of air pollution Health effects of air pollution Breathing air that is not clean can hurt ... important to know about the health effects that air pollution can have on you and others. Once you ...

  3. Effects of the air breathing engine plumes on SSV orbiter subsonic wing pressure distributions (OA57A)

    NASA Technical Reports Server (NTRS)

    Cameron, B. W., Jr.

    1974-01-01

    Experimental aerodynamic pressure investigations were conducted on a 0.0405 scale representation of the -89 space shuttle orbiter ferry configuration in the Rockwell International 7.75 x 11.00 foot Low Speed Wind Tunnel. The primary test objective was to investigate the orbiter wing pressure distribution resulting from five under-wing engine nacelle plumes. Two five engine nacelle configurations were tested at 3 ground plane heights with pressure bug measurements being made on the left upper and lower wing panel. In addition, base and balance cavity pressure measurements were made, with elevon normal and hinge moment measurements on the right panel.

  4. Investigation of nonlinear inviscid and viscous flow effects in the analysis of dynamic stall. [air flow and chordwise pressure distribution on airfoil below stall condition

    NASA Technical Reports Server (NTRS)

    Crimi, P.

    1974-01-01

    A method for analyzing unsteady airfoil stall was refined by including nonlinear effects in the representation of the inviscid flow. Certain other aspects of the potential-flow model were reexamined and the effects of varying Reynolds number on stall characteristics were investigated. Refinement of the formulation improved the representation of the flow and chordwise pressure distribution below stall, but substantial quantitative differences between computed and measured results are still evident for sinusoidal pitching through stall. Agreement is substantially improved by assuming the growth rate of the dead-air region at the onset of leading-edge stall is of the order of the component of the free stream normal to the airfoil chordline. The method predicts the expected increase in the resistance to stalling with increasing Reynolds number. Results indicate that a given airfoil can undergo both trailing-edge and leading-edge stall under unsteady conditions.

  5. Effects of air breathing engine plumes on SSV orbiter subsonic wing pressure distribution (OA57B), volume 1

    NASA Technical Reports Server (NTRS)

    Soard, T.

    1974-01-01

    Data were obtained during wind tunnel tests of a 0.0405-scale model of the ferry configuration of the space shuttle vehicle orbiter conducted in a low speed wind tunnel during the time period of September 18 to September 23, 1973. The primary test objective was to investigate orbiter wing pressure distributions resulting from nacelle plumes above and below the wing. Three six-engine nacelle configurations were tested. One configuration had a twin-podded nacelle mounted above each wing and the others had one mounted below each wing. Both had a centerline twin-podded nacelle mounted below the wing. Wing pressure distribution was determined by locating static pressure bugs on the upper and lower surfaces of the left wing. Pressure bugs were also located on the upper and lower surfaces of the body flap and on the B12 afterbody fairing when it was installed. Base and balance cavity pressures were recorded and a strain gage instrumented beam in the right wing measured elevon hinge moments and normal forces.

  6. 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.

  7. 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

  8. Effect of substrate roughness and working pressure on photocatalyst of N-doped TiOx films prepared by reactive sputtering with air

    NASA Astrophysics Data System (ADS)

    Lee, Seon-Hong; Yamasue, Eiji; Okumura, Hideyuki; Ishihara, Keiichi N.

    2015-01-01

    N-doped TiOx films on the glass substrate were prepared by radio-frequency (RF) magnetron reactive sputtering of Ti target in a mixed gas of argon and dry air. The effect of substrate roughness and working pressure on the physical properties and the photocatalytic properties of the N-doped TiOx films was investigated. The surface roughness of glass substrate has little influence on the film properties such as produced phases, lattice parameters, introduced nitrogen contents, and atomic bonding configurations, but significant influence on the surface roughness of film resulting in the variation of the photocatalytic ability. The working pressure has little influence on the produced phases and the atomic bonding configurations, but significant influence on the atomic concentration of the N-doped TiOx film, resulting in the large variation of optical, structural, and photocatalytic properties. It is suggested that the high photocatalysis of N-doped TiOx film requires a certain range of the N doping concentration which shows the interstitial complex N doping states in TiO2.

  9. 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. PMID:26398125

  10. Interpretation of prematurely terminated air-pressurized slug tests

    USGS Publications Warehouse

    Shapiro, Allen M.; Greene, Earl A.

    1995-01-01

    An air-pressurized slug test consists of applying a constant pressure to the column of air in a well, monitoring the declining water level, and then releasing the air pressure and monitoring the recovering water level. Such tests offer a means of estimating formation transmissivity and storativity without extensive downhole equipment and the associated safety risks. This paper analyzes data from prematurely terminated tests. A solution to the boundary-value problem for the declining and recovering water level during an air-pressurized slug test is developed for an arbitrary time-dependent air pressure applied to the well. Type curves are generated to estimate formation transmissivity and storativity from the recovering water level associated with prematurely, terminated tests. The application of the type curves is illustrated in a series of actual tests.

  11. 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.

  12. 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.

  13. The back-diffusion effect of air on the discharge characteristics of atmospheric-pressure radio-frequency glow discharges using bare metal electrodes

    NASA Astrophysics Data System (ADS)

    Sun, Wen-Ting; Liang, Tian-Ran; Wang, Hua-Bo; Li, He-Ping; Bao, Cheng-Yu

    2007-05-01

    Radio-frequency (RF), atmospheric-pressure glow discharge (APGD) plasmas using bare metal electrodes have promising prospects in the fields of plasma-aided etching, deposition, surface treatment, disinfection, sterilization, etc. In this paper, the discharge characteristics, including the breakdown voltage and the discharge voltage for sustaining a stable and uniform α mode discharge of the RF APGD plasmas are presented. The experiments are conducted by placing the home-made planar-type plasma generator in ambient and in a vacuum chamber, respectively, with helium as the primary plasma-forming gas. When the discharge processes occur in ambient, particularly for the lower plasma-working gas flow rates, the experimental measurements show that it is the back-diffusion effect of air in atmosphere, instead of the flow rate of the gas, that results in the obvious decrease in the breakdown voltage with increasing plasma-working gas flow rate. Further studies on the discharge characteristics, e.g. the luminous structures, the concentrations and distributions of chemically active species in plasmas, with different plasma-working gases or gas mixtures need to be conducted in future work.

  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. Underground storage systems for high-pressure air and gases

    NASA Technical Reports Server (NTRS)

    Beam, B. H.; Giovannetti, A.

    1975-01-01

    This paper is a discussion of the safety and cost of underground high-pressure air and gas storage systems based on recent experience with a high-pressure air system installed at Moffett Field, California. The system described used threaded and coupled oil well casings installed vertically to a depth of 1200 ft. Maximum pressure was 3000 psi and capacity was 500,000 lb of air. A failure mode analysis is presented, and it is shown that underground storage offers advantages in avoiding catastrophic consequences from pressure vessel failure. Certain problems such as corrosion, fatigue, and electrolysis are discussed in terms of the economic life of such vessels. A cost analysis shows that where favorable drilling conditions exist, the cost of underground high-pressure storage is approximately one-quarter that of equivalent aboveground storage.

  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. 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.

  18. Air pressure waves from Mount St. Helens eruptions

    SciTech Connect

    Reed, J.W.

    1987-10-20

    Weather station barograph records as well as infrasonic recordings of the pressure wave from the Mount St. Helens eruption of May 18, 1980, have been used to estimate an equivalent explosion airblast yield for this event. Pressure amplitude versus distance patterns in various directions compared with patterns from other large explosions, such as atmospheric nuclear tests, the Krakatoa eruption, and the Tunguska comet impact, indicate that the wave came from an explosion equivalent of a few megatons of TNT. The extent of tree blowdown is considerably greater than could be expected from such an explosion, and the observed forest damage is attributed to outflow of volcanic material. The pressure-time signature obtained at Toledo, Washington, showed a long, 13-min duration negative phase as well as a second, hour-long compression phase, both probably caused by ejacta dynamics rather than standard explosion wave phenomenology. The peculiar audibility pattern, with the blast being heard only at ranges beyond about 100 km, is explicable by finite amplitude propagation effects. Near the source, compression was slow, taking more than a second but probably less than 5 s, so that it went unnoticed by human ears and susceptible buildings were not damaged. There was no damage as Toledo (54 km), where the recorded amplitude would have broken windows with a fast compression. An explanation is that wave emissions at high elevation angles traveled to the upper stratosphere, where low ambient air pressures caused this energetic pressure oscillation to form a shock wave with rapid, nearly instantaneous compression. Atmospheric refraction then returned part of this wave to ground level at long ranges, where the fast compressions were clearly audible. copyright American Geophysical Union 1987

  19. 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

  20. The Research of Membrane-sorption System with Increased Pressure Stream for Enriching Air with Oxygen

    NASA Astrophysics Data System (ADS)

    Korolev, M. V.; Laguntsov, N. I.; Kurchatov, I. M.

    Numerical study of single-hybrid membrane-sorption air separation system for enriching the air with oxygen were conducted. The effectiveness of such a system was analyzed, depending on selective sorbents and membranes under specified pressure ratio. A comparison of various modes membrane sorption system was done. The conclusion regarding the choice of the membrane and a sorbent for the system with a pressurized product stream was drawn.

  1. SMALL OIL BURNER CONCEPTS BASED ON LOW PRESSURE AIR ATOMIZATION

    SciTech Connect

    BUTCHER,T.; CELEBI,Y.; WEI,G.; KAMATH,B.

    2000-03-16

    The development of several novel oil burner applications based on low pressure air atomization is described. The atomizer used is a prefilming, airblast nozzle of the type commonly used in gas turbine combustion. The air pressure used can be as low as 1,300 Pa and such pressure can be easily achieved with a fan. Advantages over conventional, pressure-atomized nozzles include ability to operate at low input rates without very small passages and much lower fuel pressure requirements. The development of three specific applications is presented. The first two are domestic heating burners covering a capacity range 10 to 26 kW. The third application presented involves the use of this burner in an oil-fired thermophotovoltaic power generator system. Here the design firing rate is 2.9 kW and the system produces 500 watts of electric power.

  2. Pressure evolution of ethylene-air explosions in enclosures

    NASA Astrophysics Data System (ADS)

    Movileanu, C.; Razus, D.; Giurcan, V.; Gosa, V.

    2014-08-01

    The peak explosion pressure and the maximum rate of pressure rise are important safety parameters for assessing the hazard of a process and for design of vessels able to withstand an explosion or of their vents used as relief devices. Using ethylene-air with various fuel concentrations (4-10 vol% C2H4) as test mixture, the propagation of explosion in four closed vessels (a spherical vessel with central ignition and three cylindrical vessels with various L/D ratios, centrally or side ignited) has been studied at various initial pressures between 0.3-2.0 bar. In all cases, the peak pressures and the maximum rates of pressure rise were found to be linear functions on the total initial pressure, at constant fuel concentration. Examining several enclosures, the maximum values of explosion pressures and rates of pressure rise have been found for the spherical vessel. For the same initial conditions, the peak explosion pressure and maximum rates of pressure rise determined in cylindrical vessels decrease with the increase of L/D ratio. Asymmetric ignition, at vessel's bottom, induces important heat losses during flame propagation. This process is characterized by the lowest rates of pressure rise, as compared to propagation of flame ignited in the centre of the same vessel.

  3. The Effect of Air Preheat at Atmospheric Pressure on the Formation of NO(x) in the Quick-Mix Sections of an Axially Staged Combustor

    NASA Technical Reports Server (NTRS)

    Vardakas, M. A.; Leong, M. Y.; Brouwer, J.; Samuelsen, G. S.; Holdeman, J. D.

    1999-01-01

    The Rich-burn/Quick-mix/Lean-burn (RQL) combustor concept has been proposed to minimize the formation of nitrogen oxides (NO(x)) in gas turbine systems. The success of this combustor strategy is dependent upon the efficiency of the mixing section bridging the fuel-rich and fuel-lean stages. Note that although these results were obtained from an experiment designed to study an RQL mixer, the link between mixing and NOx signatures is considerably broader than this application, in that the need to understand this link exists in most advanced combustors. The experiment reported herein was designed to study the effects of inlet air temperature on NO(x) formation in a mixing section. The results indicate that NO(x) emission is increased for all preheated cases compared to non-preheated cases. When comparing the various mixing modules, the affect of jet penetration is important, as this determines where NO(x) concentrations peak, and affects overall NO(x) production. Although jet air comprises 70 percent of the total airflow, the impact that jet air preheat has on overall NO(x) emissions is small compared to preheating both main and jet air flow.

  4. Acute Air Pollution Exposure and Blood Pressure at Delivery Among Women With and Without Hypertension

    PubMed Central

    Männistö, Tuija; Liu, Danping; Leishear, Kira; Sherman, Seth; Laughon, S. Katherine

    2015-01-01

    BACKGROUND Chronic air pollution exposure increases risk for hypertensive disorders of pregnancy, but the effect of acute air pollution exposure on blood pressure during pregnancy is less well known. METHODS We studied 151,276 singleton term deliveries from the Consortium on Safe Labor (2002–2008) with clinical blood pressure measured at admission to labor/delivery and diagnoses of hypertensive disorders collected from electronic medical records and hospital discharge summaries. Air pollution exposures were estimated for the admission hour and the 4 hours preceding admission using a modified version of the Community Multiscale Air Quality models and observed air monitoring data. Blood pressure was categorized as normal; high normal; and mild, moderate, or severe hypertension based on pregnancy cut points. Adjusted ordinal logistic regression estimated the odds of women having a higher admission blood pressure category as a function of air pollutant, hypertensive disorders, and their interaction effect. RESULTS Odds of high blood pressure at admission to labor/delivery were increased in normotensive women after exposure to nitrogen oxides (by 0.2%/5 units), sulfur dioxide (by 0.3%/1 unit), carbon monoxide and several air toxics (by 3%–4%/high exposure). The effects were often similar or stronger among women with gestational hypertension and preeclampsia. Exposure to particulate matter <10 μm increased odds of high blood pressure in women with preeclampsia by 3%/5 units. CONCLUSIONS Air pollution can influence admission blood pressure in term deliveries and may increase likelihood of preeclampsia screening at delivery admission. PMID:24795401

  5. 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.…

  6. 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.

  7. 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

  8. Modulated corona nanosecond discharge in air under ambient pressure

    NASA Astrophysics Data System (ADS)

    Lepekhin, N. M.; Priseko, Yu. S.; Filippov, V. G.; Bulatov, M. U.; Sukharevskii, D. I.; Syssoev, V. S.

    2015-04-01

    A unique type of corona discharge-modulated corona nanosecond discharge-has been obtained, the parameters of which have been determined in a geometric system of electrodes with a sharply heterogeneous electric field in air under ambient pressure and natural humidity.

  9. 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,…

  10. 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…

  11. Air Circulation and Heat Exchange under Reduced Pressures

    NASA Astrophysics Data System (ADS)

    Rygalov, Vadim; Wheeler, Raymond; Dixon, Mike; Hillhouse, Len; Fowler, Philip

    Low pressure atmospheres were suggested for Space Greenhouses (SG) design to minimize sys-tem construction and re-supply materials, as well as system manufacturing and deployment costs. But rarified atmospheres modify heat exchange mechanisms what finally leads to alter-ations in thermal control for low pressure closed environments. Under low atmospheric pressures (e.g., lower than 25 kPa compare to 101.3 kPa for normal Earth atmosphere), convection is becoming replaced by diffusion and rate of heat exchange reduces significantly. During a period from 2001 to 2009, a series of hypobaric experiments were conducted at Space Life Sciences Lab (SLSLab) NASA's Kennedy Space Center and the Department of Space Studies, University of North Dakota. Findings from these experiments showed: -air circulation rate decreases non-linearly with lowering of total atmospheric pressure; -heat exchange slows down with pressure decrease creating risk of thermal stress (elevated leaf tem-peratures) for plants in closed environments; -low pressure-induced thermal stress could be reduced by either lowering system temperature set point or increasing forced convection rates (circulation fan power) within certain limits; Air circulation is an important constituent of controlled environments and plays crucial role in material and heat exchange. Theoretical schematics and mathematical models are developed from a series of observations. These models can be used to establish optimal control algorithms for low pressure environments, such as a space greenhouse, as well as assist in fundamental design concept developments for these or similar habitable structures.

  12. 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).

  13. 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.

  14. Flame structures in the pressurized methane-air combustor

    SciTech Connect

    Yamamoto, Tsuyoshi; Miyazaki, Tomonaga, Furuhata, Tomohiko; Arai, Norio

    1998-07-01

    This study has been carried out in order to investigate the applicability of a pressurized and fuel-rich burner at a first stage combustor for a newly proposed chemical gas turbine system. The flammability limits, exhaust gas composition and the NO{sub x} emission characteristics under the pressurized conditions of 1.1--4.1 MPa have been investigated in a model combustor. This paper focuses on the influence of pressure and F/A equivalence ratio on flame structures of pressurized combustion with methane and air to obtain detailed data for designing of fuel-rich combustor for gas turbine application. The flame under fuel-rich condition and pressure of 1 MPa showed underventilated structure like other atmospheric fuel-rich flames while the flame under pressure over 1.5 MPa had shapes as fuel-lean flame. The flame becomes longer as the pressure was increased under the fuel-lean conditions, which under fuel-rich condition the influence of pressure on flame length was smaller in comparison with the flame under fuel-lean conditions. These results give an opportunity for developing smaller combustor under fuel-rich and pressurized condition compared to fuel-lean one. Numerical simulation has been done for defining the temperature profile in the model combustor using the k-{var{underscore}epsilon} turbulence model and three-step reaction model. The comparison between theoretical results and experimental data showed fair agreements.

  15. 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.

  16. 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.

  17. 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.

  18. 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…

  19. Adding a custom made pressure release valve during air enema for intussusception: A new technique

    PubMed Central

    Ahmed, Hosni Morsi; Ahmed, Osama; Ahmed, Refaat Khodary

    2015-01-01

    Background: Non-surgical reduction remains the first line treatment of choice for intussusception. The major complication of air enema reduction is bowel perforation. The authors developed a custom made pressure release valve to be added to portable insufflation devices, delivering air at pressures accepted as safe for effective reduction of intussusception in children under fluoroscopic guidance. The aim of this study was to develop a custom made pressure release valve that is suitable for the insufflation devices used for air enema reduction of intussusception and to put this valve into regular clinical practice. Materials and Methods: An adjustable, custom made pressure release valve was assembled by the authors using readily available components. The valve was coupled to a simple air enema insufflation device. The device was used for the trial of reduction of intussusception in a prospective study that included 132 patients. Results: The success rate for air enema reduction with the new device was 88.2%. The mean pressure required to achieve complete reduction was 100 mmHg. The insufflation pressure never exceeded the preset value (120 mmHg). Of the successful cases, 58.3% were reduced from the first attempt while 36.1% required a second insufflation. Only 5.55% required a third insufflation to complete the reduction. In cases with unsuccessful pneumatic reduction attempt (18.1%), surgical treatment was required. Surgery ranged from simple reduction to resection with a primary end to end anastomosis. No complications from air enema were recorded. Conclusions: The authors recommend adding pressure release valves to ensure safety by avoiding pressure overshoot during the procedure. PMID:26712286

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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

  5. 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)

  6. 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)

  7. 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.

  8. 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.

  9. 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)

  10. [Effect of osmotic pressure on nitrification].

    PubMed

    Zheng, Ping; Wu, Ming-Sheng

    2006-01-01

    The effect of osmotic pressure on nitrification was investigated in the internal-loop air-lift nitrifying reactor. When influent ammonia concentration is kept at 420mg x L(-1) and influent osmotic pressure is increased from 4.3 to 18.8 x 10(5) Pa, the ammonia conversion of the nitrifying bioreactor is maintained between 93% and 100%. After influent osmotic pressure is further increased to 19.2 x 10(5)Pa, the ammonia conversion goes down to 69.2%. The influence of osmotic pressure on nitrification takes place without any alarm and the critical osmotic pressure is between 18.8 x 10(5) and 19.2 x 10(5) Pa. During osmotic stress, the nitrifying bacterial populations in the activated sludge become simplified, the cell size becomes smaller, the inner membrane becomes less and some unknown inclusion particles are formed. The cell structure is restored as soon as the osmotic pressure is removed. Addition of potassium is able to relieve the effect of osmotic pressure on nitrification. The nitrifying activity of the activated sludge is stimulated by the osmotic stress, and the specific ammonia conversion is increased from 0.083 kg x kg(-1) x d(-1) to 0.509 kg x kg(-1) x d(-1) and 2.569 kg x kg(-1) x d(-1), respectively. PMID:16572857

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    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.

  12. 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.

  13. 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. PMID:26282384

  14. Effects of pressure waves

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Two parameters, side on overpressure and side on impulse loads, and their application to the determination of structural damage to buildings and vehicles in the vicinity of an explosion are investigated. Special consideration was given to what constitutes damage and what level of damage is acceptable. Solutions were sorted through the examination of glass breakage, curve fit to bomb damage, overturning of marginal structures (buses, trucks, mobile homes) subject to toppling, and initiation of yielding in either beam or plate structural components. Three different empirical pressure versus impulse diagrams were presented - the first is for minor structural damage involving wrenched joints and partitions, the second is for major damage structural damage with load bearing members at least partially destroyed, and the third is for 50% to 75% of the building demolished. General guidelines were obtained from the results when the accurate structural details are unknown.

  15. 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.

  16. Evaluation of Air Capture Ratio of Scramjet Inlet by Multi-Point Pressure Measurement

    NASA Astrophysics Data System (ADS)

    Kitamura, Eijiro; Mitani, Tohru; Sakuranaka, Noboru; Izumikawa, Muneo; Watanabe, Syuichi; Masuya, Goro

    A method to evaluate aerodynamic performances of scramjet engines by using multi-probe rakes was proposed. The aerodynamic tests were carried out under Mach 4 flight conditions. The Pitot and static pressures were measured at 250 points in the cross sectional area of the engine exit by the rakes. Local mass flux and thrust function were evaluated from the pressure measurement at each point and integrations of these values enabled to obtain the mass flow rate and the stream thrust at the engine exit. The air capture ratios were independently measured by the rakes and a conventional choked flowmeter. The air capture ratios measured by these two methods agreed within 2%. It was found that the rakes enabled to measure the air capture ratio more simply than the flowmeter. Additionally, the effect of boundary layer ingestion to an internal drag was investigated by the rakes. The decrease of air capture ratio measured by the rakes showed that the ingested boundary layers were separated in the inlet. The pressure drag of inlet increased by the separation and the pressure thrust decreased by the decrease of air capture ratio. As a result, the internal drag increased when the forebody boundary layer was ingested.

  17. 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.

  18. Blasting and blast effects in cold regions. Part 1. Air blast. Special report

    SciTech Connect

    Not Available

    1985-12-01

    Contents include: ideal blast waves in free air; the shock equations for air blast; scaling procedures for comparison of explosions; reflection and refraction of airblast; effect of charge height, or height of burst; attenuation of air blast and variation of shock-front properties; air blast from nuclear explosions; air blast from underground explosions; air blast from underwater explosions; air blast damage criteria; effects of ambient pressure and temperature; explosions in vacuum or in space; air blast attenuation over snow surfaces; shock reflection from snow surfaces; shock velocity over snow; variation of shock pressure with charge height over snow; release of avalanches by air blast.

  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.

    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

  1. 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.

  2. 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.

  3. Picosecond ballistic imaging of diesel injection in high-temperature and high-pressure air

    NASA Astrophysics Data System (ADS)

    Duran, Sean P.; Porter, Jason M.; Parker, Terence E.

    2015-04-01

    The first successful demonstration of picosecond ballistic imaging using a 15-ps-pulse-duration laser in diesel sprays at temperature and pressure is reported. This technique uses an optical Kerr effect shutter constructed from a CS2 liquid cell and a 15-ps pulse at 532 nm. The optical shutter can be adjusted to produce effective imaging pulses between 7 and 16 ps. This technique is used to image the near-orifice region (first 3 mm) of diesel sprays from a high-pressure single-hole fuel injector. Ballistic imaging of dodecane and methyl oleate sprays injected into ambient air and diesel injection at preignition engine-like conditions are reported. Dodecane was injected into air heated to 600 °C and pressurized to 20 atm. The resulting images of the near-orifice region at these conditions reveal dramatic shedding of the liquid near the nozzle, an effect that has been predicted, but to our knowledge never before imaged. These shedding structures have an approximate spatial frequency of 10 mm-1 with lengths from 50 to 200 μm. Several parameters are explored including injection pressure, liquid fuel temperature, air temperature and pressure, and fuel type. Resulting trends are summarized with accompanying images.

  4. Effects of particulate air pollution on blood pressure in a highly exposed population in Beijing, China: a repeated-measure study

    PubMed Central

    2011-01-01

    Background Particulate Matter (PM) exposure is critical in Beijing due to high population density and rapid increase in vehicular traffic. PM effects on blood pressure (BP) have been investigated as a mechanism mediating cardiovascular risks, but results are still inconsistent. The purpose of our study is to determine the effects of ambient and personal PM exposure on BP. Methods Before the 2008 Olympic Games (June 15-July 27), we examined 60 truck drivers and 60 office workers on two days, 1-2 weeks apart (n = 240). We obtained standardized measures of post-work BP. Exposure assessment included personal PM2.5 and Elemental Carbon (EC, a tracer of traffic particles) measured using portable monitors during work hours; and ambient PM10 averaged over 1-8 days pre-examination. We examined associations of exposures (exposure group, personal PM2.5/EC, ambient PM10) with BP controlling for multiple covariates. Results Mean personal PM2.5 was 94.6 μg/m3 (SD = 64.9) in office workers and 126.8 (SD = 68.8) in truck drivers (p-value < 0.001). In all participants combined, a 10 μg/m3 increase in 8-day ambient PM10 was associated with BP increments of 0.98 (95%CI 0.34; 1.61; p-value = 0.003), 0.71 (95%CI 0.18; 1.24; p-value = 0.01), and 0.81 (95%CI 0.31; 1.30; p-value = 0.002) mmHg for systolic, diastolic, and mean BP, respectively. BP was not significantly different between the two groups (p-value > 0.14). Personal PM2.5 and EC during work hours were not associated with increased BP. Conclusions Our results indicate delayed effects of ambient PM10 on BP. Lack of associations with exposure groups and personal PM2.5/EC indicates that PM effects are related to background levels of pollution in Beijing, and not specifically to work-related exposure. PMID:22188661

  5. Interactive effects of soil water deficit and air vapour pressure deficit on mesophyll conductance to CO2 in Vitis vinifera and Olea europaea.

    PubMed

    Perez-Martin, A; Flexas, J; Ribas-Carbó, M; Bota, J; Tomás, M; Infante, J M; Diaz-Espejo, A

    2009-01-01

    The present work aims to study the interactive effect of drought stress and high vapour pressure deficit (VPD) on leaf gas exchange, and especially on mesophyll conductance to CO(2) (g(m)), in two woody species of great agronomical importance in the Mediterranean basin: Vitis vinifera L. cv. Tempranillo and Olea europaea L. cv. Manzanilla. Plants were grown in specially designed outdoor chambers with ambient and below ambient VPD, under both well-irrigated and drought conditions. g(m) was estimated by the variable J method from simultaneous measurements of gas exchange and fluorescence. In both species, the response to soil water deficit was larger in g(s) than in g(m), and more important than the response to VPD. Olea europaea was apparently more sensitive to VPD, so that plants growing in more humid chambers showed higher g(s) and g(m). In V. vinifera, in contrast, soil water deficit dominated the response of g(s) and g(m). Consequently, changes in g(m)/g(s) were more related to VPD in O. europaea and to soil water deficit in V. vinifera. Most of the limitations of photosynthesis were diffusional and especially due to stomatal closure. No biochemical limitation was detected. The results showed that structural parameters played an important role in determining g(m) during the acclimation process. Although the relationship between leaf mass per unit area (M(A)) with g(m) was scattered, it imposed a limitation to the maximum g(m) achievable, with higher values of M(A) in O. europaea at lower g(m) values. M(A) decreased under water stress in O. europaea but it increased in V. vinifera. This resulted in a negative relationship between M(A) and the CO(2) draw-down between substomatal cavities and chloroplasts in O. europaea, while being positive in V. vinifera. PMID:19457982

  6. A noncontact intraocular pressure measurement device using a micro reflected air pressure sensor for the prediagnosis of glaucoma

    NASA Astrophysics Data System (ADS)

    Kim, Kyoung Hwan; Kim, Byeong Hee; Seo, Young Ho

    2012-03-01

    This study investigates a novel, portable tonometer using a micro reflected air pressure sensor for the prediagnosis of glaucoma. Because glaucoma progresses slowly and is not painful, glaucoma patients require a portable prediagnosis system to periodically measure intraocular pressure at home. Conventionally, intraocular pressure is measured by an air-puff tonometer whereby the cornea is deformed by a short pulse of air pressure and the magnitude of the corneal deformation is measured by optic systems such as a combination of laser- and photodiodes. In this study, a micro reflected air pressure sensor was designed, fabricated, and tested in order to measure the magnitude of corneal deformation without optic systems. In an experimental study, artificial eyes with different internal pressures were fabricated and these pressures were measured by the aforementioned system.

  7. 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.

  8. 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.

  9. Health Effects of Air Pollution.

    ERIC Educational Resources Information Center

    Environmental Education Report and Newsletter, 1985

    1985-01-01

    Summarizes health hazards associated with air pollution, highlighting the difficulty in establishing acceptable thresholds of exposure. Respiratory disease, asthma, cancer, cardiovascular disease, and other problems are addressed. Indicates that a wide range of effects from any one chemical exists and that there are differences in sensitivity to…

  10. Emission measurements for a lean premixed propane/air system at pressures up to 30 atmospheres

    NASA Technical Reports Server (NTRS)

    Roffe, G.; Venkataramani, K. S.

    1978-01-01

    The emissions of a lean premixed system of propane/air were measured in a flametube apparatus. Tests were conducted at inlet temperatures of 600K and 800K and pressures of 10 atm and 30 atm over a range of equivalence ratios. The data obtained were combined with previous data taken in the same apparatus to correlate nitrogen oxide emissions with operating conditions. Sampling probe design was found to have a pronounced effect on measured CO levels but did not influence measurements. The most effective probe tested was one which combined thermal and pressure quenching of the gas sample.

  11. Effect of Pulse Nanosecond Volume Discharge in Air at Atmospheric Pressure on Electrical Properties of Mis Structures Based on p-HgCdTe Grown by Molecular Beam Epitaxy

    NASA Astrophysics Data System (ADS)

    Voitsekhovskii, A. V.; Nesmelov, S. N.; Dzyadukh, S. M.; Grigor'ev, D. V.; Tarasenko, V. F.; Shulepov, M. A.

    2015-11-01

    The effect of the pulse nanosecond volume discharge in air at atmospheric pressure on the admittance of MIS structures based on MBE graded-gap p-Hg0.78Cd0.22Te is studied in a wide range of frequencies and temperatures. It is shown that the impact of the discharge leads to significant changes in electrical characteristics of MIS structures (the density of positive fixed charge increases), to the changes in the nature of the hysteresis of capacitance-voltage characteristics, and to an increase in the density of surface states. A possible reason for the changes in the characteristics of MIS structures after exposure to the discharge is substantial restructuring of the defect-impurity system of the semiconductor near the interface.

  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. 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.

  15. Ground cloud air quality effects

    NASA Technical Reports Server (NTRS)

    Brubaker, K. L.

    1980-01-01

    The effects of the ground cloud associated with launching of a large rocket on air quality are discussed. The ground cloud consists of the exhaust emitted by the rocket during the first 15 to 25 seconds following ignition and liftoff, together with a large quantity of entrained air, cooling water, dust and other debris. Immediately after formation, the ground cloud rises in the air due to the buoyant effect of its high thermal energy content. Eventually, at an altitude typically between 0.7 and 3 km, the cloud stabilizes and is carried along by the prevailing wind at that altitude. For the use of heavy lift launch vehicles small quantities of nitrogen oxides, primarily nitric oxide and nitrogen dioxide, are expected to be produced from a molecular nitrogen impurity in the fuel or liquid oxygen, or from entrainment and heating of ambient air in the hot rocket exhaust. In addition, possible impurities such as sulfur in the fuel would give rise to a corresponding amount of oxidation products such as sulfur dioxide.

  16. 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.

  17. Atmospheric Pressure Non-Thermal Air Plasma Jet

    NASA Astrophysics Data System (ADS)

    Mohamed, Abdel-Aleam; Al-Mashraqi, Ahmed; Benghanem, Mohamed; Al Shariff, Samir

    2013-09-01

    Atmospheric pressure air cold plasma jet is introduced in this work. It is AC (60 Hz to 20 kHz) cold plasma jet in air. The system is consisted of a cylindrical alumina insulator tube with outer diameter of 1.59 mm and 26 mm length and 0.80 mm inner diameter. AC sinusoidal high voltage was applied to the powered electrode which is a hollow needle inserted in the Alumina tube. The inner electrode is a hollow needle with 0.80 mm and 0.46 mm outer and inner diameters respectively. The outer electrode is grounded which is a copper ring surrounded the alumina tube locates at the nozzle end. Air is blowing through the inner electrode to form a plasma jet. The jet length increases with flow rate and applied voltage to reach 1.5 cm. The gas temperature decreases with distance from the end of the nozzle and with increasing the flow rate. The spectroscopic measurement between 200 nm and 900 nm indicates that the jet contains reactive species such as OH, O in addition to the UV emission. The peak to peak current values increased from 6 mA to 12 mA. The current voltage waveform indicates that the generated jet is homogenous plasma. The jet gas temperature measurements indicate that the jet has a room temperature. This work was supported by the National Science, Technology and Innovation Plan(NSTIP) through the Science and Technology Unit (STU) at Taibah University, Al Madinah Al Munawwarah, KSA, with the grant number 08-BIO24-5.

  18. Effects of particulate air pollution on asthmatics

    SciTech Connect

    Perry, G.B.; Chai, H.; Dickey, D.W.; Jones, R.H.; Kinsman, R.A.; Morrill, C.G.; Spector, S.L.; Weiser, P.C.

    1983-01-01

    Twenty-four asthmatic subjects in Denver were followed from January through March 1979, a three-month period in which Denver air pollution levels are generally high and variable. Dichotomous, virtual impactor samplers provided daily measurements (micrograms/m3) of inhaled particulate matter (total mass, sulfates, and nitrates) for coarse (2.5--15 micrograms in aerodynamic diameter) and fine fractions (less than 2.5 micrometers). Carbon monoxide, sulfur dioxide, ozone, temperature, and barometric pressure were also measured. Twice daily measurements of each subject's peak expiratory flow rates, use of as-needed aerosolized bronchodilators, and report of airways obstruction symptoms characteristic of asthma were tested for relationships to air pollutants using a random effects model across subjects. During the time actually observed, there were very few days in which high levels of suspended particulates were recorded. Of the environmental variables studied, only fine nitrates were associated with increased symptom reports and increased aerosolized bronchodilator usage.

  19. In-air and pressurized water reactor environment fatigue experiments of 316 stainless steel to study the effect of environment on cyclic hardening

    NASA Astrophysics Data System (ADS)

    Mohanty, Subhasish; Soppet, William K.; Majumdar, Saurindranath; Natesan, Krishnamurti

    2016-05-01

    Argonne National Laboratory (ANL), under the sponsorship of Department of Energy's Light Water Reactor Sustainability (LWRS) program, is trying to develop a mechanistic approach for more accurate life estimation of LWR components. In this context, ANL has conducted many fatigue experiments under different test and environment conditions on type 316 stainless steel (316 SS) material which is widely used in the US reactors. Contrary to the conventional S ∼ N curve based empirical fatigue life estimation approach, the aim of the present DOE sponsored work is to develop an understanding of the material ageing issues more mechanistically (e.g. time dependent hardening and softening) under different test and environmental conditions. Better mechanistic understanding will help develop computer-based advanced modeling tools to better extrapolate stress-strain evolution of reactor components under multi-axial stress states and hence help predict their fatigue life more accurately. Mechanics-based modeling of fatigue such as by using finite element (FE) tools requires the time/cycle dependent material hardening properties. Presently such time-dependent material hardening properties are hardly available in fatigue modeling literature even under in-air conditions. Getting those material properties under PWR environment, are even harder. Through this work we made preliminary attempt to generate time/cycle dependent stress-strain data both under in-air and PWR water conditions for further study such as for possible development of material models and constitutive relations for FE model implementation. Although, there are open-ended possibility to further improve the discussed test methods and related material estimation techniques we anticipate that the data presented in this paper will help the metal fatigue research community particularly, the researchers who are dealing with mechanistic modeling of metal fatigue such as using FE tools. In this paper the fatigue experiments

  20. The effect of undissolved air on isochoric freezing.

    PubMed

    Perez, Pedro A; Preciado, Jessica; Carlson, Gary; DeLonzor, Russ; Rubinsky, Boris

    2016-06-01

    This study evaluates the effect of undissolved air on isochoric freezing of aqueous solutions. Isochoric freezing is concerned with freezing in a constant volume thermodynamic system. A possible advantage of the process is that it substantially reduces the percentage of ice in the system at every subzero temperature, relative to atmospheric freezing. At the pressures generated by isochoric freezing, or high pressure isobaric freezing, air cannot be considered an incompressible substance and the presence of undissolved air substantially increases the amount of ice that forms at any subfreezing temperature. This effect is measurable at air volumes as low as 1%. Therefore eliminating the undissolved air, or any separate gaseous phase, from the system is essential for retaining the properties of isochoric freezing. PMID:27074589

  1. 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.

  2. On the impact of entrapped air in infiltration under ponding conditions. Part a: Preferential air flow path effects on infiltration

    NASA Astrophysics Data System (ADS)

    Mizrahi, Guy; Weisbrod, Noam; Furman, Alex

    2015-04-01

    Entrapped air effects on infiltration under ponding conditions could be important for massive infiltration of managed aquifer recharge (MAR) or soil aquifer treatment (SAT) of treated wastewater. Earlier studies found that under ponding conditions, air is being entrapped and compressed until it reaches a pressure which will enable the air to escape (unstable air flow). They also found that entrapped air could reduce infiltration by 70-90%. Most studies have dealt with entrapped air effects when soil surface topography is flat. The objective of this study is to investigate, under ponding conditions, the effects of: (1) irregular surface topography on preferential air flow path development (stable air flow); (2) preferential air flow path on infiltration; and (3) hydraulic head on infiltration when air is trapped. Column experiments were used to investigate these particular effects. A 140 cm deep and 30 cm wide column packed with silica sand was used under two boundary conditions: in the first, air can only escape vertically upward through the soil surface; in the second, air is free to escape through 20 ports installed along the column perimeter. The surface was flooded with 13 liters of water, with ponding depth decreasing with time. Two soil surface conditions were tested: flat surface and irregular surface (high and low surface zones). Additionally, Helle-show experiments were conducted in order to obtain a visual observation of preferential air flow path development. The measurements were carried out using a tension meter, air pressure transducers, TDR and video cameras. It was found that in irregular surfaces, stable air flow through preferential paths was developed in the high altitude zones. Flat surface topography caused unstable air flow through random paths. Comparison between irregular and flat surface topography showed that the entrapped air pressure was lower and the infiltration rate was about 40% higher in the irregular surface topography than in the

  3. Seed disinfection effect of atmospheric pressure plasma and low pressure plasma on Rhizoctonia solani.

    PubMed

    Nishioka, Terumi; Takai, Yuichiro; Kawaradani, Mitsuo; Okada, Kiyotsugu; Tanimoto, Hideo; Misawa, Tatsuya; Kusakari, Shinichi

    2014-01-01

    Gas plasma generated and applied under two different systems, atmospheric pressure plasma and low pressure plasma, was used to investigate the inactivation efficacy on the seedborne pathogenic fungus, Rhizoctonia solani, which had been artificially introduced to brassicaceous seeds. Treatment with atmospheric plasma for 10 min markedly reduced the R. solani survival rate from 100% to 3% but delayed seed germination. The low pressure plasma treatment reduced the fungal survival rate from 83% to 1.7% after 10 min and the inactivation effect was dependent on the treatment time. The seed germination rate after treatment with the low pressure plasma was not significantly different from that of untreated seeds. The air temperature around the seeds in the low pressure system was lower than that of the atmospheric system. These results suggested that gas plasma treatment under low pressure could be effective in disinfecting the seeds without damaging them. PMID:24975415

  4. Pressure Sensitive Insulated Gate Field Effect Transistor

    NASA Astrophysics Data System (ADS)

    Suminto, James Tjan-Meng

    A pressure sensitive insulated gate field effect transistor has been developed. The device is an elevated gate field-effect-transistor. It consists of a p-type silicon substrate in which two n^+ region, the source and drain, are formed. The gate electrode is a metal film sandwiched in an insulated micro-diaphragm resembling a pill-box which covers the gate oxide, drain, and source. The space between the gate electrode and the oxide is vacuum or an air-gap. When pressure is applied on the diaphragm it deflects and causes a change in the gate capacitance, and thus modulates the conductance of the channel between source and drain. A general theory dealing with the characteristic of this pressure sensitive insulated gate field effect transistor has been derived, and the device fabricated. The fabrication process utilizes the standard integrated circuit fabrication method. It features a batch fabrication of field effect devices followed by the batch fabrication of the deposited diaphragm on top of each field effect device. The keys steps of the diaphragm fabrication are the formation of spacer layer, formation of the diaphragm layer, and the subsequent removal of the spacer layer. The chip size of the device is 600 μm x 1050 mum. The diaphragm size is 200 μm x 200 mum. Characterization of the device has been performed. The current-voltage characteristics with pressure as parameters have been demonstrated and the current-pressure transfer curves obtained. They show non-linear characteristics as those of conventional capacitive pressure sensors. The linearity of threshold voltage versus pressure transfer curves has been demonstrated. The temperature effect on the device performances has been tested. The temperature coefficient of threshold voltage, rather than the electron mobility, has dominated the temperature coefficient of the device. Two temperature compensation schemes have been tested: one method is by connecting two identical PSIGFET in a differential amplifier

  5. The effect of atmospheric pressure on ventricular assist device output.

    PubMed

    Goto, Takeshi; Sato, Masaharu; Yamazaki, Akio; Fukuda, Wakako; Watanabe, Ken-Ichi; Daitoku, Kazuyuki; Minakawa, Masahito; Fukui, Kozo; Suzuki, Yasuyuki; Fukuda, Ikuo

    2012-03-01

    The effect of cabin pressure change on the respiratory system during flight is well documented in the literature, but how the change in atmospheric pressure affects ventricular assist device (VAD) output flow has not been studied yet. The purpose of our study was to evaluate the change in VAD output using a mock circulatory system in a low-pressure chamber mimicking high altitude. Changes in output and driving pressure were measured during decompression from 1.0 to 0.7 atm and pressurization from 0.7 to 1.0 atm. Two driving systems were evaluated: the VCT system and the Mobart system. In the VCT system, output and driving pressure remained the same during decompression and pressurization. In the Mobart system, the output decreased as the atmospheric pressure dropped and recovered during pressurization. The lowest output was observed at 0.7 atm, which was 80% of the baseline driven by the Mobart system. Under a practical cabin pressure of 0.8 atm, the output driven by the Mobart system was 90% of the baseline. In the Mobart system, the output decreased as the atmospheric pressure dropped, and recovered during pressurization. However, the decrease in output was slight. In an environment where the atmospheric pressure changes, it is necessary to monitor the diaphragmatic motion of the blood pump and the driving air pressure, and to adjust the systolic:diastolic ratio as well as the positive and negative pressures in a VAD system. PMID:21915797

  6. Influence of venting areas on the air blast pressure inside tubular structures like railway carriages.

    PubMed

    Larcher, Martin; Casadei, Folco; Solomos, George

    2010-11-15

    In case of a terrorist bomb attack the influence and efficiency of venting areas in tubular structures like train carriages is of interest. The pressure-time function of an air blast wave resulting from a solid charge is first compared to that of a gas or dust explosion and the capability of a venting structure to fly away is assessed. Several calculations using fluid-structure interaction are performed, which show that after a certain distance from the explosion, the air blast wave inside a tubular structure becomes one-dimensional, and that the influence of venting areas parallel to the wave propagation direction is small. The pressure peak and the impulse at certain points in a tubular structure are compared for several opening sizes. The overall influence of realistic size venting devices remains moderate and their usefulness in mitigating internal explosion effects in trains is discussed. PMID:20728991

  7. 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

  8. 30 CFR 56.13015 - Inspection of compressed-air receivers and other unfired pressure vessels.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... other unfired pressure vessels. 56.13015 Section 56.13015 Mineral Resources MINE SAFETY AND HEALTH... and other unfired pressure vessels. (a) Compressed-air receivers and other unfired pressure vessels... applicable chapters of the National Board Inspection Code, a Manual for Boiler and Pressure Vessel...

  9. 29 CFR 1915.172 - Portable air receivers and other unfired pressure vessels.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Engineers Boiler and Pressure Vessel Code, Section VIII, Rules for Construction of Unfired Pressure Vessels... 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...

  10. 29 CFR 1915.172 - Portable air receivers and other unfired pressure vessels.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Engineers Boiler and Pressure Vessel Code, Section VIII, Rules for Construction of Unfired Pressure Vessels... 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...

  11. 30 CFR 56.13015 - Inspection of compressed-air receivers and other unfired pressure vessels.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... other unfired pressure vessels. 56.13015 Section 56.13015 Mineral Resources MINE SAFETY AND HEALTH... and other unfired pressure vessels. (a) Compressed-air receivers and other unfired pressure vessels... applicable chapters of the National Board Inspection Code, a Manual for Boiler and Pressure Vessel...

  12. Combination Of Thermography And Pressure Tests To Combat Air Leakage Problems In Building Enclosures

    NASA Astrophysics Data System (ADS)

    Spruin, W. G.

    1987-05-01

    Uncontrolled air leakage in a building enclosure is the main component of space heating and cooling costs. In Atlantic Canada, Public Works Canada has combined thermography and pressure testing to identify design and construction problems in new construction and to identify specific areas of air leakage in existing housing stock. A study case shows how thermography and pressure testing has been utilized to locate and compare specific areas of air leakage in a residence before and after air sealing. The study provides both quantitative and qualitative evidence of how air sealing increases the air tightness in building enclosures.

  13. 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

  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. Air pollution, blood pressure, and the risk of hypertensive complications during pregnancy: the generation R study.

    PubMed

    van den Hooven, Edith H; de Kluizenaar, Yvonne; Pierik, Frank H; Hofman, Albert; van Ratingen, Sjoerd W; Zandveld, Peter Y J; Mackenbach, Johan P; Steegers, Eric A P; Miedema, Henk M E; Jaddoe, Vincent W V

    2011-03-01

    Exposure to air pollution is associated with elevated blood pressure and cardiovascular disease. We assessed the associations of exposure to particulate matter (PM(10)) and nitrogen dioxide (NO(2)) levels with blood pressure measured in each trimester of pregnancy and the risks of pregnancy-induced hypertension and preeclampsia in 7006 women participating in a prospective cohort study in the Netherlands. Information on gestational hypertensive disorders was obtained from medical records. PM(10) exposure was not associated with first trimester systolic and diastolic blood pressure, but a 10-μg/m(3) increase in PM(10) levels was associated with a 1.11-mm Hg (95% confidence interval [CI] 0.43 to 1.79) and 2.11-mm Hg (95% CI 1.34 to 2.89) increase in systolic blood pressure in the second and third trimester, respectively. Longitudinal analyses showed that elevated PM(10) exposure levels were associated with a steeper increase in systolic blood pressure throughout pregnancy (P<0.01), but not with diastolic blood pressure patterns. Elevated NO(2) exposure was associated with higher systolic blood pressure levels in the first, second, and third trimester (P<0.05), and with a more gradual increase when analyzed longitudinally (P<0.01). PM(10) exposure, but not NO(2) exposure, was associated with an increased risk of pregnancy-induced hypertension (odds ratio 1.72 [95% CI 1.12 to 2.63] per 10-μg/m(3) increase). In conclusion, our results suggest that air pollution may affect maternal cardiovascular health during pregnancy. The effects might be small but relevant on a population level. PMID:21220700

  16. 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....

  17. 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…

  18. 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…

  19. 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.

  20. 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.

  1. 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. PMID:26133864

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Effects of boundary layer and liquid viscosity and compressible air on sloshing characteristics

    NASA Astrophysics Data System (ADS)

    Zou, Chang-Fang; Wang, De-Yu; Cai, Zhong-Hua

    2015-07-01

    In this paper, numerical investigations for tank sloshing, based on commercial CFD package FLUENT, are performed to study effects of boundary layer grid, liquid viscosity and compressible air on sloshing pressure, wave height and rising time of impact pressure. Also, sloshing experiments for liquids of different viscosity are carried out to validate the numerical results. Through comparison of numerical and experimental results, a computational model including boundary layer grid can predict the sloshing pressure more accurately. Energy dissipation due to viscous friction leads to reduction of sloshing pressure and wave elevation. Sloshing pressure is also reduced because of cushion effect of compressible air. Due to high viscosity damping effect and compressible air effect, the rising time of impact pressure becomes longer. It is also found that liquid viscosity and compressible air influence distribution of dynamic pressure along the vertical tank wall.

  8. The effectiveness of a heated air curtain

    NASA Astrophysics Data System (ADS)

    Frank, Daria

    2014-11-01

    Air curtains are high-velocity plane turbulent jets which are installed in the doorway in order to reduce the heat and the mass exchange between two environments. The air curtain effectiveness E is defined as the fraction of the exchange flow prevented by the air curtain compared to the open-door situation. In the present study, we investigate the effects of an opposing buoyancy force on the air curtain effectiveness. Such an opposing buoyancy force arises for example if a downwards blowing air curtain is heated. We conducted small-scale experiments using water as the working fluid with density differences created by salt and sugar. The effectiveness of a downwards blowing air curtain was measured for situations in which the initial density of the air curtain was less than both the indoor and the outdoor fluid density, which corresponds to the case of a heated air curtain. We compare the effectiveness of the heated air curtain to the case of the neutrally buoyant air curtain. It is found that the effectiveness starts to decrease if the air curtain is heated beyond a critical temperature. Furthermore, we propose a theoretical model to describe the dynamics of the buoyant air curtain. Numerical results obtained from solving this model corroborate our experimental findings.

  9. Mixture distributions for the statistical time delay in synthetic air at low pressure

    NASA Astrophysics Data System (ADS)

    Jovanović, Aleksandar P.; Popović, Biljana Č.; Marković, Vidosav Lj.; Stamenković, Suzana N.; Stankov, Marjan N.

    2014-08-01

    The mixture distributions for statistical time delay of electrical breakdown are proposed along with the generalized relation for the effective electron yield. The validity of the proposed model is tested by applying this distribution to experimental data measured in synthetic air at low pressure. Two samples without and with oxide surface are compared in order to determine physical processes leading to appearance of mixture distributions in the case of oxidized cathode. The obtained distributions are tested by Kolmogorov-Smirnov statistical hypothesis test in order to justify the use of mixture distributions. The physical interpretation of mixture distribution measured in the synthetic air is proposed, accompanied by the calculated values of the effective electron yield of initiating electrons in the gas gap.

  10. Pressure effects in multiphase binary diffusion couples

    NASA Astrophysics Data System (ADS)

    Subramanyam, Dilip; Notis, Michael R.; Goldstein, Joseph I.

    1985-04-01

    A systematic study has been carried out of the effect of pressure upon growth kinetics of intermediate phases formed in diffusion couples in the binary systems Ni-Al, U-A1, and U-Cu. Even though applied pressures greater than 100 MPa and long times were investigated little or no pressure effect was observed, in disagreement with previous literature reports. The magnitude of observed pressure effects falls within that expected by closure of Kirkendall porosity.

  11. 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.

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

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... other unfired pressure vessels. 57.13015 Section 57.13015 Mineral Resources MINE SAFETY AND HEALTH... receivers and other unfired pressure vessels. (a) Compressed-air receivers and other unfired pressure vessels shall be inspected by inspectors holding a valid National Board Commission and in accordance...

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

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... other unfired pressure vessels. 57.13015 Section 57.13015 Mineral Resources MINE SAFETY AND HEALTH... receivers and other unfired pressure vessels. (a) Compressed-air receivers and other unfired pressure vessels shall be inspected by inspectors holding a valid National Board Commission and in accordance...

  14. The physics of pulsed streamer discharge in high pressure air and applications to engine techonologies

    NASA Astrophysics Data System (ADS)

    Lin, Yung-Hsu

    The goal of this dissertation is to study high pressure streamers in air and apply it to diesel engine technologies. Nanosecond scale pulsed high voltage discharges in air/fuel mixtures can generate radicals which in turn have been shown to improve combustion efficiency in gasoline fueled internal combustion engines. We are exploring the possibility to extend such transient plasma generation and expected radical species generation to the range of pressures encountered in compression-ignition (diesel) engines having compression ratios of ˜20:1, thereby improving lean burning efficiency and extending the range of lean combustion. At the beginning of this dissertation, research into streamer discharges is reviewed. Then, we conducted experiments of streamer propagation at high pressures, calculated the streamer velocity based on both optical and electrical measurements, and the similarity law was checked by analyzing the streamer velocity as a function of the reduced electric field, E/P. Our results showed that the similarity law is invalid, and an empirical scaling factor, E/√P, is obtained and verified by dimensional analysis. The equation derived from the dimensional analysis will be beneficial to proper electrode and pulse generator design for transient plasma assisted internal engine experiments. Along with the high pressure study, we applied such technique on diesel engine to improve the fuel efficiency and exhaust treatment. We observed a small effect of transient plasma on peak pressure, which implied that transient plasma has the capability to improve the fuel consumption. In addition, the NO can be reduced effectively by the same technique and the energy cost is 30 eV per NO molecule.

  15. 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.

  16. Impacts of air pressure on the evolution of nanosecond pulse discharge products

    NASA Astrophysics Data System (ADS)

    Yu, Jin-Lu; He, Li-Ming; Ding, Wei; Wang, Yu-Qian; Du, Chun

    2013-05-01

    Based on the nonequilibrium plasma dynamics of air discharge, a dynamic model of zero-dimensional plasma is established by combining the component density equation, the Boltzmann equation, and the energy transfer equation. The evolution properties of nanosecond pulse discharge (NPD) plasma under different air pressures are calculated. The results show that the air pressure has significant impacts on the NPD products and the peak values of particle number density for particles such as O atoms, O3 molecules, N2(A3) molecules in excited states, and NO molecules. It increases at first and then decreases with the increase of air pressure. On the other hand, the peak values of particle number density for N2(B3) and N2(C3) molecules in excited states are only slightly affected by the air pressure.

  17. 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

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Pressure sensing by flexible, organic, field effect transistors

    NASA Astrophysics Data System (ADS)

    Manunza, I.; Sulis, A.; Bonfiglio, A.

    2006-10-01

    A mechanical sensor based on a pentacene field effect transistor has been fabricated. The pressure dependence of the output current has been investigated by applying a mechanical stimulus by means of a pressurized air flow. Experimental results show a reversible current dependence on pressure. Data analysis suggests that variations of threshold voltage, mobility and contact resistance are responsible for current variations. Thanks to the flexibility of the substrate and the low cost of the technology, this device opens the way for flexible mechanical sensors that can be used in a variety of innovative applications such as e-textiles and robotic interfaces.

  5. 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

  6. 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.

  7. Vertical laryngeal position and oral pressure variations during resonance tube phonation in water and in air. A pilot study.

    PubMed

    Wistbacka, Greta; Sundberg, Johan; Simberg, Susanna

    2016-10-01

    Resonance tube phonation in water (RTPW) is commonly used in voice therapy, particularly in Finland and Sweden. The method is believed to induce a lowering of the vertical laryngeal position (VLP) in phonation as well as variations of the oral pressure, possibly inducing a massage effect. This pilot study presents an attempt to measure VLP and oral pressure in two subjects during RTPW and during phonation with the free tube end in air. VLP is recorded by means of a dual-channel electroglottograph. RTPW was found to lower VLP in the subjects, while it increased during phonation with the tube end in air. RTPW caused an oral pressure modulation with a bubble frequency of 14-22 Hz, depending mainly on the depth of the tube end under the water surface. The results indicate that RTPW lowers the VLP instantly and creates oral pressure variations. PMID:26033381

  8. Pressure Regulators as Valves for Saving Compressed Air and their Influence on System Dynamics

    NASA Astrophysics Data System (ADS)

    Dvořák, Lukáš; Fojtášek, Kamil

    2015-05-01

    Pressure regulators in the field of pneumatic mechanisms can be used as valves for saving compressed air. For example it can be used to reduce the pressure when the piston rod is retracting unloaded and thus it is possible to save some energy. However the problem is that saving valve can significantly affect the dynamics of the pneumatic system. The lower pressure in the piston rod chamber causes extension of time for retraction of the piston rod. This article compare the air consumption experimentally determined and calculated, measured curves of pressure in cylinder chambers and piston speed when saving valve is set up differently.

  9. Air-leakage effects on stone cladding panels

    NASA Astrophysics Data System (ADS)

    Colantonio, Antonio

    1995-03-01

    This paper looks at the effects of air leakage on insulated stone clad precast panels used in present day construction of large commercial buildings. The building investigated was a newly built twenty story office building in a high density urban setting. Air leakage was suspected as a possible cause for thermal comfort complaints at isolated locations within the perimeter zones of the building. During the warrantee period the building owner asked for a quality control inspection of the air barrier assembly of the building envelope. Infrared thermography was used to locate areas of suspected air leakage within the building envelope. In order to differentiate thermal patterns produced by air leakage, conduction and convection as well as radiation from external sources, the building was inspected from the exterior; (1) after being pressurized for three hours, (2) one hour after the building was depressurized and (3) two and a half hours after total building depressurization was maintained by the building mechanical systems. Thermal images from similar locations were correlated for each time and pressure setting to verify air leakage locations within the building envelope. Areas exhibiting air leakage were identified and contractors were requested to carry out the necessary repairs. The pressure differential across the building envelope needs to be known in order to properly carry out an inspection to identify all locations of air leakage within a building envelope. As well the direction of the air movement and the density of the cladding material need to be accounted for in the proper inspection of these types of wall assemblies.

  10. [Effect of dopamine on the portal pressure].

    PubMed

    Benko, H; Peschl, L; Schüller, J; Neumayr, A

    1975-01-01

    1. An infusion of 3 gamma/kg/min dopamine causes a significant increase in the renal plasma flow and the glomerulum filtration rate. This dosage does not cause a change of the mean systolic and arterial pressure. This effect may also be observed in patients with hepatic cirrhosis. 2. The wedged hepatic vein pressure, an indicator for the portal pressure, only shows a slight increase (9,46 +/- 9,41%) as compared to the initial pressure produced by the mentioned dose. Measurements of the spleen pulpa pressure, which likewise indicates the portal pressure, showed an increase of pressure up to 100% due to pressing or coughing. 3. If in the case of bleeding oesophageal varices acute renal failure might develop, the advantage of the effect of dopamine in stimulating the blood flow through the kidneys may be considered more important than the minute danger of a slight increase of the portal pressure, which might provoke haemorrhage. PMID:1220517

  11. Detailed Comparison of Blast Effects in Air and Vacuum

    SciTech Connect

    Tringe, J W; Molitoris, J D; Garza, R G; Andreski, H G; Batteux, J D; Lauderbach, L M; Vincent, E R; Wong, B M

    2007-07-26

    Although blast mitigation is most often achieved with solid shielding, ambient gas pressure can also affect the coupling of shock waves to solid targets. In this work the role of air as an energy transfer medium was examined experimentally by subjecting identical large-area rectangular witness plates to short-range blast effects in air and vacuum ({approx}50 mtorr) at 25 C. The expanding reactant front of 3 kg C4 charges was observed by fast camera to be cylindrically symmetric in both air and vacuum. The horizontal component of the reactant cloud velocity (perpendicular to the witness plates) was constant in both cases, with values of 3.0 and 5.9 km/s for air and vacuum, respectively. As a result of the blast, witness plates were plastically deformed into a shallow dish geometry, with local maxima 30 and 20 mm deep for air and vacuum, respectively. The average plate deflection from the air blast was 11 mm, {approx}10% deeper than the average vacuum plate deflection. Shock pressure estimates were made with a simple impedance-matching model, and indicate peak values in the 30-50 MPa range are consistent with the reactant cloud density and velocity. However, more detailed analysis is necessary to definitely establish the mechanisms by which air couples shock energy to the plates.

  12. A new DBD-driven atmospheric pressure plasma jet source on air or nitrogen

    NASA Astrophysics Data System (ADS)

    Sosnin, Eduard A.; Panarin, Victir A.; Skakun, Victor S.; Tarasenko, Victor F.; Pechenitsin, Dmitrii S.; Kuznetsov, Vladimir S.

    2015-12-01

    The paper proposes a new atmospheric pressure plasma jet (APPJ) source for operation in air and nitrogen. The conditions for the formation of stable plasma jets 4 cm long are determined. Energy and spectral measurement data are presented.

  13. The upper explosion limit of lower alkanes and alkenes in air at elevated pressures and temperatures.

    PubMed

    Van den Schoor, F; Verplaetsen, F

    2006-01-16

    The upper explosion limit (UEL) of ethane-air, propane-air, n-butane-air, ethylene-air and propylene-air mixtures is determined experimentally at initial pressures up to 30 bar and temperatures up to 250 degrees C. The experiments are performed in a closed spherical vessel with an internal diameter of 200 mm. The mixtures are ignited by fusing a coiled tungsten wire, placed at the centre of the vessel, by electric current. Flame propagation is said to have taken place if there is a pressure rise of at least 1% of the initial pressure after ignition of the mixture. In the pressure-temperature range investigated, a linear dependence of UEL on temperature and a bilinear dependence on pressure are found except in the vicinity of the auto-ignition range. A comparison of the UEL data of the lower alkanes shows that the UEL expressed as equivalence ratio (the actual fuel/air ratio divided by the stoichiometric fuel/air ratio) increases with increasing carbon number in the homologous series of alkanes. PMID:16154265

  14. 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.

  15. 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. 393.51 Section 393.51 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL... REGULATIONS PARTS AND ACCESSORIES NECESSARY FOR SAFE OPERATION Brakes § 393.51 Warning signals, air...

  16. Pressure effects on the femtosecond laser filamentation

    NASA Astrophysics Data System (ADS)

    Qi, Xiexing; Ma, Cunliang; Lin, Wenbin

    2016-01-01

    We investigate the pressure effects on the propagation of the laser pulse with wavelength of 800 nm by numerical simulations. We consider the effects on the on-axis intensity, the beam radius and the energy of the filament, as well as the on-axis density of plasma. Numerical results show that when the pressures increase, the length, radius and energy of the light filament become shorter, narrower and lower, respectively. Moreover, we find that the length and the radius of filament are approximately inversely proportional to the pressure and the square root of pressure, respectively, and the pulse with shorter duration is easier to be affected by the pressure. We also obtain the conclusion that the plasma is not necessary to generate the filament in gases in various pressures, as stated by Béjot et al. [1] for the case of standard atmosphere pressure.

  17. On the impact of entrapped air in infiltration under ponding conditions: Part a: Preferential air flow path effects on infiltration

    NASA Astrophysics Data System (ADS)

    Weisbord, N.; Mizrahi, G.; Furman, A.

    2015-12-01

    Entrapped air effects on infiltration under ponding conditions could be important for massive infiltration of managed aquifer recharge or soil aquifer treatment. Earlier studies found that under ponding conditions air could reduce infiltration by 70-90%. Most studies have dealt with entrapped air effects when soil surface topography is flat. The objective of this study is to investigate the effects of: (1) irregular surface topography on preferential air flow path development; (2) preferential air flow path on infiltration; and (3) hydraulic head on infiltration when air is trapped. Column experiments were used to investigate these particular effects. A 140 cm deep and 30 cm wide column packed with silica sand was used under two boundary conditions: in the first, air can only escape vertically upward through the soil surface; in the second, air is free to escape. The surface was flooded with 13 liters of water, with ponding depth decreasing with time. Two soil surface conditions were tested: flat surface and irregular. It was found that in irregular surfaces, stable air flow through preferential paths was developed in the high altitude zones. Flat surface topography caused unstable air flow through random paths. Comparison between irregular and flat surface topography showed that the entrapped air pressure was lower and the infiltration rate was about 40% higher in the irregular surface topography than in the flat surface topography. No difference of infiltration rate between flat and irregular surface topography was observed when air was free to escape along the infiltration path. It was also found that at the first stage of infiltration, higher hydraulic heads caused higher entrapped air pressures and lower infiltration rates. In contrast, higher hydraulic head results in higher infiltration rate, when air was free to escape. Our results suggest that during ponding conditions: (1) preferential air flow paths develop at high surface zones of irregular topography

  18. 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. PMID:26580727

  19. Self-pulsing discharges in pre-heated air at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Janda, Mário; Machala, Zdenko; Dvonč, Lukáš; Lacoste, Deanna; Laux, Christophe O.

    2015-01-01

    The paper presents investigations of self-pulsing discharges in atmospheric pressure air pre-heated to 300-1000 K. Despite using a direct-current power supply, two self-pulsing discharge regimes, a repetitive transient spark (TS) and a repetitive streamer (RS) were generated. The pulse repetition frequency, on the order of a few kHz, can be controlled by adjusting the generator voltage. The TS is a discharge initiated by a streamer, followed by a short (tens of ns) spark current pulse (˜ 1 A), associated with the total discharging of the internal capacity of the electric circuit. The TS is suitable for the study of ‘memory’ effects (pre-heating, pre-ionization) on the mechanisms of streamer-to-spark transition and electrical breakdown in atmospheric pressure air. The TS regime was stable below ˜600 K. Above ˜600 K, a stable repetitive streamer (RS) regime was observed. In this regime, the breakdown and spark did not occur. After the initial streamer, the internal capacity of the electrical circuit discharged partially. With further pre-heating of the gas, the stable TS appeared again at ˜1000 K.

  20. 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

  1. 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)

  2. 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.

  3. Preliminary investigation of cooling-air ejector performance at pressure ratios from 1 to 10

    NASA Technical Reports Server (NTRS)

    Ellis, C W; Hollister, D P; Sargent, A F , Jr

    1951-01-01

    Preliminary investigation was made of conical cooling air ejector at primary pressure ratios from 1 to 10. The cooling-air flow was maintained at zero and the resulting pressure variation in the shroud indicated pumping ability. The cooling-air flow was maintained at zero and the resulting pressure variation in the shroud indicated pumping ability. The gross thrust of the ejector and nozzle were compared. Several ratios of the spacing between the nozzle and shroud exit to the nozzle exit diameter were investigated for several shroud to nozzle exit diameter ratios. Maximum gross thrust loss occurred under conditions of zero cooling-air flow and was as much as 35 percent below nozzle jet thrust. For minimum thrust loss, ejector should be designed with as low diameter and spacing ratio as possible.

  4. Radio-Frequency Sustainment of Laser Initiated, High-Pressure Air Constituent Plasmas*

    NASA Astrophysics Data System (ADS)

    Akhtar, Kamran; Scharer, John; Tysk, Shane; Denning, Mark

    2003-10-01

    We investigate the feasibility of creating a high-density sim 10^12 -10^14 /cc, large volume plasma in air constituents by laser (300 mJ, 20(+/-2) ns) preionization of an organic gas. Tetrakis (dimethyl-amino) ethylene (TMAE) is seeded in high-pressure air constituent gases and then sustained by the efficient absorption of the radio-frequency (RF) power (1-25 kW pulsed) through inductive coupling of the wave fields, thereby reducing the rf initiation power budget.1 A multi-turn helical antenna is used to couple rf power through a capacitive matching network to sustain the plasma. Plasma density and decay recombination mechanisms with and without the background gas are examined using a 105 GHz interferometr.2 The effect of gas heating on plasma life-time enhancement through reduced formation of negative oxygen ions will also be presented. Optical emission spectroscopy is employed to study the process of delayed ionization of the seed gas and RF creation of air constituent plasma and calculate the plasma temperature. RF wave penetration and projection of plasma away from the source region are also examined for different gas flow rates. 1. Kelly K, Scharer J, Paller E, and Ding G, J. App. Phys., 92,698(2002). 2. Akhtar K, Scharer J, Tysk S., and Kho E., Rev. Sci. Instrum., 74, 996 (2003).

  5. Cell immobilization on polymer by air atmospheric pressure plasma jet treatment

    NASA Astrophysics Data System (ADS)

    Lee, Jung-Hwan; Kwon, Jae-Sung; Om, Ji-yeon; Kim, Yong-Hee; Choi, Eun-Ha; Kim, Kwang-Mahn; Kim, Kyoung-Nam

    2014-08-01

    The study of cell immobilization on delicate polymer by an air atmospheric pressure plasma jet (AAPPJ) is required for its medical application. The aim of this study was to evaluate whether AAPPJ treatment induce cell immobilization effect on delicate polymers without significant change of surface roughness by AAPPJ treatment. After surface roughness, dynamic contact angle, and chemical characteristics were investigated, the immobilization effect was evaluated with the mouse fibroblast L929 cell line. Surface roughness change was not observed (P > 0.05) in either delicate dental wax or polystyrene plate (PSP) as advancing and receding contact angles significantly decreased (P < 0.05), thanks to decreased hydrocarbon and formation of oxygen-related functional groups in treated PSP. Adherent L929 cells with elongated morphology were found in treated PSP along with the formation of immobilization markers vinculin and actin cytoskeleton. Increased PTK2 gene expression upregulated these markers on treated PSP.

  6. 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.

  7. Electron reactions in nonpolar liquids: Pressure effects

    SciTech Connect

    Holroyd, R.A.

    1993-09-01

    Theory predicts that electron energy levels in nonpolar molecular hydrocarbons should increase in energy with density/pressure increase, and therefore electron attachment rates in solution should change with pressure. Studies of pressure effect on electron mobility show that some contraction occurs around trapped electrons, but more contraction occurs around ions in hydrocarbons. After a brief discussion of pressure effects on electron energy levels and mobility, this paper reports studies of electron attachment reactions of N{sub 2}O, CO{sub 2}, and n-C{sub 5}F{sub 12} in tetramethylsilane, and of toluene, benzene, CO{sub 2}, and 1,3-butadiene in several solvents.

  8. 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.

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

    SciTech Connect

    Fox, R.L.

    1983-06-28

    An apparatus is claimed 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.

  10. 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

  11. Pressure effect on dissimilatory sulfate reduction

    NASA Astrophysics Data System (ADS)

    Williamson, A. J.; Carlson, H. K.; Coates, J. D.

    2015-12-01

    Biosouring is the production of H2S by sulfate reducing microorganisms (SRM) in-situ or in the produced fluids of oil reservoirs. Sulfide is explosive, toxic and corrosive which can trigger equipment and transportation failure, leading to environmental catastrophe. As oil exploration and reservoir development continue, subsequent enhanced recovery is occurring in progressively deeper formations and typical oil reservoir pressures range from 10-50 MPa. Therefore, an understanding of souring control effects will require an accurate understanding of the influence of pressure on SRM metabolism and the efficacy of souring control treatments at high pressure. Considerable work to date has focussed on souring control at ambient pressure; however, the influence of pressure on biogeochemical processes and souring treatments in oil reservoirs is poorly understood. To explore the impact of pressure on SRM, wild type Desulfovibrio alaskensis G20 (isolated from a producing oil well in Ventura County, California) was grown under a range of pressures (0.1-14 MPa) at 30 °C. Complete sulfate reduction occurred in all pressures tested within 3 days, but microbial growth was inhibited with increasing pressure. Bar-seq identified several genes associated with flagella biosynthesis (including FlhB) and assembly as important for survival at elevated pressure and fitness was confirmed using individual transposon mutants. Flagellar genes have previously been implicated with biofilm formation and confocal microscopy on glass slides incubated with wild type D. alaskensis G20 showed more biomass associated with surfaces under pressure, highlighting the link between pressure, flagellar and biofilm formation. To determine the effect of pressure on the efficacy of SRM inhibitors, IC50 experiments were conducted and D. alaskensis G20 showed a greater resistance to nitrate and the antibiotic chloramphenicol, but a lower resistance to perchlorate. These results will be discussed in the context of

  12. Ventilation System Effectiveness and Tested Indoor Air Quality Impacts

    SciTech Connect

    Rudd, A.; Bergey, D.

    2014-02-01

    Ventilation system effectiveness testing was conducted at two unoccupied, single-family, detached lab homes at the University of Texas - Tyler. Five ventilation system tests were conducted with various whole-building ventilation systems. Multizone fan pressurization testing characterized building and zone enclosure leakage. PFT testing showed multizone air change rates and interzonal airflow. Cumulative particle counts for six particle sizes, and formaldehyde and other Top 20 VOC concentrations were measured in multiple zones. The testing showed that single-point exhaust ventilation was inferior as a whole-house ventilation strategy. It was inferior because the source of outside air was not direct from outside, the ventilation air was not distributed, and no provision existed for air filtration. Indoor air recirculation by a central air distribution system can help improve the exhaust ventilation system by way of air mixing and filtration. In contrast, the supply and balanced ventilation systems showed that there is a significant benefit to drawing outside air from a known outside location, and filtering and distributing that air. Compared to the Exhaust systems, the CFIS and ERV systems showed better ventilation air distribution and lower concentrations of particulates, formaldehyde and other VOCs. System improvement percentages were estimated based on four System Factor Categories: Balance, Distribution, Outside Air Source, and Recirculation Filtration. Recommended System Factors could be applied to reduce ventilation fan airflow rates relative to ASHRAE Standard 62.2 to save energy and reduce moisture control risk in humid climates. HVAC energy savings were predicted to be 8-10%, or $50-$75/year.

  13. Ventilation System Effectiveness and Tested Indoor Air Quality Impacts

    SciTech Connect

    Rudd, Armin; Bergey, Daniel

    2014-02-01

    In this project, Building America research team Building Science Corporation tested the effectiveness of ventilation systems at two unoccupied, single-family, detached lab homes at the University of Texas - Tyler. Five ventilation system tests were conducted with various whole-building ventilation systems. Multizone fan pressurization testing characterized building and zone enclosure leakage. PFT testing showed multizone air change rates and interzonal airflow. Cumulative particle counts for six particle sizes, and formaldehyde and other Top 20 VOC concentrations were measured in multiple zones. The testing showed that single-point exhaust ventilation was inferior as a whole-house ventilation strategy. This was because the source of outside air was not direct from outside, the ventilation air was not distributed, and no provision existed for air filtration. Indoor air recirculation by a central air distribution system can help improve the exhaust ventilation system by way of air mixing and filtration. In contrast, the supply and balanced ventilation systems showed that there is a significant benefit to drawing outside air from a known outside location, and filtering and distributing that air. Compared to the exhaust systems, the CFIS and ERV systems showed better ventilation air distribution and lower concentrations of particulates, formaldehyde and other VOCs. System improvement percentages were estimated based on four system factor categories: balance, distribution, outside air source, and recirculation filtration. Recommended system factors could be applied to reduce ventilation fan airflow rates relative to ASHRAE Standard 62.2 to save energy and reduce moisture control risk in humid climates. HVAC energy savings were predicted to be 8-10%, or $50-$75/year.

  14. Pressure versus drag effects on crater size

    NASA Technical Reports Server (NTRS)

    Schmidt, R. M.

    1993-01-01

    The topic of atmospheric effects on crater formation is very complex because it includes not only pressure effects on excavation, but also drag effects on ejecta placement. Experiments have to be designed very carefully to allow isolation of the two phenomena. Historically, numerous investigators have shown an influence of atmospheric pressure. However, none have identified the scaling that correctly isolates pressure from drag effects. On-going work in explosive cratering has produced scaling paradigms for deeply buried explosive charges where drag effects are negligible. Here it was found that increased pressure caused significant induced strength effects that impeded crater excavation. The effect is more pronounced with increasing burial depth and less pronounced with increased yield.

  15. High gas pressure effects on yeast.

    PubMed

    Espinasse, V; Perrier-Cornet, J-M; Marecat, A; Gervais, P

    2008-11-01

    Dried microorganisms are particularly resistant to high hydrostatic pressure effects. However, exposure to high pressures of nitrogen proved to be effective in inactivating dried yeasts. In this study, we tried to elucidate this mechanism on Saccharomyces cerevisiae. High-pressure treatments were performed using different inert gases at 150 MPa and 25 degrees C with holding time values up to 12 months. The influence of cell hydration was also investigated. For fully hydrated cells, pressurized gases had little specific effect: cell inactivation was mainly due to compression effects. However, dried cells were sensitive to high pressure of gases. In this latter case, two inactivation kinetics were observed. For holding time up to 1 h, the inactivation rate increased to 4 log and was linked to a loss of membrane integrity and the presence of damage on the cell wall. In such case cell inactivation would be due to gas sorption and desorption phenomena which would rupture dried cells during a fast pressure release. Gas sorption would occur in cell lipid phases. For longer holding times, the inactivation rate increased more slightly due to compression effects and/or to a slower gas sorption. Water therefore played a key role in cell sensitivity to fast gas pressure release. Two hypotheses were proposed to explain this phenomenon: the rigidity of vitrified dried cells and the presence of glassy solid phases which would favor intracellular gas expansion. Our results showed that dried microorganisms can be ruptured and inactivated by a fast pressure release with gases. PMID:18814287

  16. Water cycles in closed ecological systems: effects of atmospheric pressure

    NASA Technical Reports Server (NTRS)

    Rygalov, Vadim Y.; Fowler, Philip A.; Metz, Joannah M.; Wheeler, Raymond M.; Bucklin, Ray A.; Sager, J. C. (Principal Investigator)

    2002-01-01

    In bioregenerative life support systems that use plants to generate food and oxygen, the largest mass flux between the plants and their surrounding environment will be water. This water cycle is a consequence of the continuous change of state (evaporation-condensation) from liquid to gas through the process of transpiration and the need to transfer heat (cool) and dehumidify the plant growth chamber. Evapotranspiration rates for full plant canopies can range from 1 to 10 L m-2 d-1 (1 to 10 mm m-2 d-1), with the rates depending primarily on the vapor pressure deficit (VPD) between the leaves and the air inside the plant growth chamber. VPD in turn is dependent on the air temperature, leaf temperature, and current value of relative humidity (RH). Concepts for developing closed plant growth systems, such as greenhouses for Mars, have been discussed for many years and the feasibility of such systems will depend on the overall system costs and reliability. One approach for reducing system costs would be to reduce the operating pressure within the greenhouse to reduce structural mass and gas leakage. But managing plant growth environments at low pressures (e.g., controlling humidity and heat exchange) may be difficult, and the effects of low-pressure environments on plant growth and system water cycling need further study. We present experimental evidence to show that water saturation pressures in air under isothermal conditions are only slightly affected by total pressure, but the overall water flux from evaporating surfaces can increase as pressure decreases. Mathematical models describing these observations are presented, along with discussion of the importance for considering "water cycles" in closed bioregenerative life support systems.

  17. Water cycles in closed ecological systems: effects of atmospheric pressure.

    PubMed

    Rygalov, Vadim Y; Fowler, Philip A; Metz, Joannah M; Wheeler, Raymond M; Bucklin, Ray A

    2002-01-01

    In bioregenerative life support systems that use plants to generate food and oxygen, the largest mass flux between the plants and their surrounding environment will be water. This water cycle is a consequence of the continuous change of state (evaporation-condensation) from liquid to gas through the process of transpiration and the need to transfer heat (cool) and dehumidify the plant growth chamber. Evapotranspiration rates for full plant canopies can range from ~1 to 10 L m-2 d-1 (~1 to 10 mm m-2 d-1), with the rates depending primarily on the vapor pressure deficit (VPD) between the leaves and the air inside the plant growth chamber. VPD in turn is dependent on the air temperature, leaf temperature, and current value of relative humidity (RH). Concepts for developing closed plant growth systems, such as greenhouses for Mars, have been discussed for many years and the feasibility of such systems will depend on the overall system costs and reliability. One approach for reducing system costs would be to reduce the operating pressure within the greenhouse to reduce structural mass and gas leakage. But managing plant growth environments at low pressures (e.g., controlling humidity and heat exchange) may be difficult, and the effects of low-pressure environments on plant growth and system water cycling need further study. We present experimental evidence to show that water saturation pressures in air under isothermal conditions are only slightly affected by total pressure, but the overall water flux from evaporating surfaces can increase as pressure decreases. Mathematical models describing these observations are presented, along with discussion of the importance for considering "water cycles" in closed bioregenerative life support systems. PMID:12481804

  18. Effects of Sand-Filled Hydraulic Fractures during Air Sparging

    NASA Astrophysics Data System (ADS)

    Hall, R. J.; Murdoch, L. C.; Falta, R. W.

    2003-12-01

    The effectiveness of air sparging is limited in fine-grained formations, such as clay-rich saprolite, where low permeability restricts flow rates. The purpose of this work is to investigate the effectiveness of using hydraulic fractures to increase the performance of air sparging in relatively low permeability materials. The approach has been to conduct step-rate, air-injection tests into conventional wells and wells intersecting fractures, and then to evaluate the results of these tests using analytical and numerical models. Fieldwork is being conducted in an area underlain by saprolite weathered from granitoid gneiss. Permeability of the saprolite ranges from 1x10-12 to 5x10 -12 m2 according to slug test data. Five wells have been used for testing: three non-fractured and two fractured wells. Well tests involved injecting air at constant pressure and monitoring transient flow rates until the flow approximately equilibrated over 10 to 60 minutes, then incrementally increasing pressure and repeating the flow monitoring. Field results were expressed in terms of the initial specific sparge capacity (Q/(P-H-E)) where Q is mass flow rate, P is injection pressure, H is hydrostatic pressure, and E is air entry pressure. The specific sparge capacity of conventional wells ranges from 0.3 to 0.6 m3/(Mpa min), whereas it is several times greater for fractured wells (0.8 to 3.5 m3/(Mpa min)) at the field site. Field data have been analyzed using analytical and numerical models. We use the step-rate data and invert an analytical solution adapted from Philip (J. Contam. Hydro., 1998) to estimate the in situ relative permeability function during sparging. This approach indicates that permeability ranges from 0.4x10-12 to 2x10-12 m2, which is remarkably similar to the slug test data. It also indicates that the in situ air entry pressure is approximately 31 kPa, and the exponent constant in the Gardner relative permeability function ranges from 0.12 to 0.25 m-1. Numerical analyses

  19. Electrode Evaporation Effects on Air Arc Behavior

    NASA Astrophysics Data System (ADS)

    Li, Xingwen; Chen, Degui; Li, Rui; Wu, Yi; Niu, Chunping

    2008-06-01

    A numerical study of the effects of copper and silver vapours on the air arc behavior is performed. The commercial software FLUENT is adapted and modified to develop a two-dimensional magneto-hydrodynamic (MHD) models of arc with the thermodynamic properties and transport coefficients, net emission coefficient for the radiation model of 99% ai-1% Cu, 99% air-1% Ag, and pure air, respectively. The simulation result demonstrates that vaporization of the electrode material may cool the arc center region and reduce the arc velocity. The effects of Ag vapour are stronger compared to those of Cu vapour.

  20. 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

  1. 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

  2. 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

  3. 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.

  4. 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.

  5. Development of open air silicon deposition technology by silane-free atmospheric pressure plasma enhanced chemical transport under local ambient gas control

    NASA Astrophysics Data System (ADS)

    Naito, Teruki; Konno, Nobuaki; Yoshida, Yukihisa

    2016-07-01

    Open air silicon deposition was performed by combining silane-free atmospheric pressure plasma-enhanced chemical transport and a newly developed local ambient gas control technology. The effect of air contamination on silicon deposition was investigated using a vacuum chamber, and the allowable air contamination level was confirmed to be 3 ppm. The capability of the local ambient gas control head was investigated numerically and experimentally. A safe and clean process environment with air contamination less than 1 ppm was achieved. Combining these technologies, a microcrystalline silicon film was deposited in open air, the properties of which were comparable to those of silicon films deposited in a vacuum chamber.

  6. 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.

  7. Air pressure waves from Mount St. Helens eruptions

    SciTech Connect

    Reed, J.W.

    1980-01-01

    Barograms from a number of National Weather Service stations were assembled for the May 18, 1980, eruption and compared to airblast wave propagations from large explosions. Wave amplitudes at 50 to 300 km distances were about what might be expected from a nuclear explosion of between 1 megaton and 10 megaton yield. Pressure-time signatures could not be resolved for the first compression phase, because of the slow paper recording speed. The 900 s negative phase duration was much too long for comparison with the negative phase of an explosion. Nevertheless, positive and negative amplitudes were about equal, as often observed at long distances from explosions. Calculations have been made for a simple finite amplitude propagation model. These show rough bounds on the source compression rate, to give the observed inaudible waves at least to 54 km distance, yet cause audibly rapid compression at Seattle, near 150 km, and beyond.

  8. Constant-Pressure Combustion Charts Including Effects of Diluent Addition

    NASA Technical Reports Server (NTRS)

    Turner, L Richard; Bogart, Donald

    1949-01-01

    Charts are presented for the calculation of (a) the final temperatures and the temperature changes involved in constant-pressure combustion processes of air and in products of combustion of air and hydrocarbon fuels, and (b) the quantity of hydrocarbon fuels required in order to attain a specified combustion temperature when water, alcohol, water-alcohol mixtures, liquid ammonia, liquid carbon dioxide, liquid nitrogen, liquid oxygen, or their mixtures are added to air as diluents or refrigerants. The ideal combustion process and combustion with incomplete heat release from the primary fuel and from combustible diluents are considered. The effect of preheating the mixture of air and diluents and the effect of an initial water-vapor content in the combustion air on the required fuel quantity are also included. The charts are applicable only to processes in which the final mixture is leaner than stoichiometric and at temperatures where dissociation is unimportant. A chart is also included to permit the calculation of the stoichiometric ratio of hydrocarbon fuel to air with diluent addition. The use of the charts is illustrated by numerical examples.

  9. Altitude Cooling Investigation of the R-2800-21 Engine in the P-47G Airplane. IV - Engine Cooling-Air Pressure Distribution

    NASA Technical Reports Server (NTRS)

    Kaufman, Samuel J.; Staudt, Robert C.; Valerino, Michael F.

    1947-01-01

    A study of the data obtained in a flight investigation of an R-2800-21 engine in a P-47G airplane was made to determine the effect of the flight variables on the engine cooling-air pressure distribution. The investigation consisted of level flights at altitudes from 5000 to 35,000 feet for the normal range of engine and airplane operation. The data showed that the average engine front pressures ranged from 0.73 to 0.82 of the impact pressure (velocity head). The average engine rear pressures ranged from 0.50 to 0.55 of the impact pressure for closed cowl flaps and from 0.10 to 0.20 for full-open cowl flaps. In general, the highest front pressures were obtained at the bottom of the engine. The rear pressures for the rear-row cylinders were .lower and the pressure drops correspondingly higher than for the front-row cylinders. The rear-pressure distribution was materially affected by cowl-flap position in that the differences between the rear pressures of the front-row and rear-row cylinders markedly increased as the cowl flaps were opened. For full-open cowl flaps, the pressure drops across the rear-row cylinders were in the order of 0.2 of the impact pressure greater than across the front-row cylinders. Propeller speed and altitude had little effect on the -coolingair pressure distribution, Increase in angle of inclination of the thrust axis decreased the front ?pressures for the cylinders at the top of the engine and increased them for the cylinders at the bottom of the engine. As more auxiliary air was taken from the engine cowling, the front pressures and, to a lesser extent, the rear pressures for the cylinders at the bottom of the engine decreased. No correlation existed between the cooling-air pressure-drop distribution and the cylinder-temperature distribution.

  10. Research on the water hammer protection of the long distance water supply project with the combined action of the air vessel and over-pressure relief valve

    NASA Astrophysics Data System (ADS)

    Li, D. D.; Jiang, J.; Zhao, Z.; Yi, W. S.; Lan, G.

    2013-12-01

    We take a concrete pumping station as an example in this paper. Through the calculation of water hammer protection with a specific pumping station water supply project, and the analysis of the principle, mathematical models and boundary conditions of air vessel and over-pressure relief valve we show that the air vessel can protect the water conveyance system and reduce the transient pressure damage due to various causes. Over-pressure relief valve can effectively reduce the water hammer because the water column re-bridge suddenly stops the pump and prevents pipeline burst. The paper indicates that the combination set of air vessel and over-pressure relief valve can greatly reduce the quantity of the air valve and can eliminate the water hammer phenomenon in the pipeline system due to the vaporization and water column separation and re-bridge. The conclusion could provide a reference for the water hammer protection of long-distance water supply system.

  11. Health effects of outdoor air pollution

    PubMed Central

    Abelsohn, Alan; Stieb, Dave M.

    2011-01-01

    Abstract Objective To inform family physicians about the health effects of air pollution and to provide an approach to counseling vulnerable patients in order to reduce exposure. Sources of information MEDLINE was searched using terms relevant to air pollution and its adverse effects. We reviewed English-language articles published from January 2008 to December 2009. Most studies provided level II evidence. Main message Outdoor air pollution causes substantial morbidity and mortality in Canada. It can affect both the respiratory system (exacerbating asthma and chronic obstructive pulmonary disease) and the cardiovascular system (triggering arrhythmias, cardiac failure, and stroke). The Air Quality Health Index (AQHI) is a new communication tool developed by Health Canada and Environment Canada that indicates the level of health risk from air pollution on a scale of 1 to 10. The AQHI is widely reported in the media, and the tool might be of use to family physicians in counseling high-risk patients (such as those with asthma, chronic obstructive pulmonary disease, or cardiac failure) to reduce exposure to outdoor air pollution. Conclusion Family physicians can use the AQHI and its health messages to teach patients with asthma and other high-risk patients how to reduce health risks from air pollution. PMID:21841106

  12. High-pressure phases of SiO2 made in air by Fedoseev-Derjaguin laser process

    NASA Astrophysics Data System (ADS)

    Alam, M.; DebRoy, T.; Roy, R.; Breval, E.

    1988-10-01

    Exposure of a falling stream of 1 μm average size α-quartz particles to a continuous wave or pulsed CO2 laser beam in air resulted in the formation of a complete series of high-pressure phases of silica: coesite, stishovite, and apparently even denser forms with α-PbO2 and Fe2N structures. Since the laser exposure technique works with the carbon black to diamond transition, the technique is confirmed as a simple and generally applicable means to achieve the same effects as exposure to several hundred kilobars pressure.

  13. Human health effects of air pollution.

    PubMed Central

    Folinsbee, L J

    1993-01-01

    Over the past three or four decades, there have been important advances in the understanding of the actions, exposure-response characteristics, and mechanisms of action of many common air pollutants. A multidisciplinary approach using epidemiology, animal toxicology, and controlled human exposure studies has contributed to the database. This review will emphasize studies of humans but will also draw on findings from the other disciplines. Air pollutants have been shown to cause responses ranging from reversible changes in respiratory symptoms and lung function, changes in airway reactivity and inflammation, structural remodeling of pulmonary airways, and impairment of pulmonary host defenses, to increased respiratory morbidity and mortality. Quantitative and qualitative understanding of the effects of a small group of air pollutants has advanced considerably, but the understanding is by no means complete, and the breadth of effects of all air pollutants is only partially understood. PMID:8354181

  14. Auto-ignition and upper explosion limit of rich propane-air mixtures at elevated pressures.

    PubMed

    Norman, F; Van den Schoor, F; Verplaetsen, F

    2006-09-21

    The auto-ignition limits of propane-air mixtures at elevated pressures up to 15 bar and for concentrations from 10 mol% up to 70 mol% are investigated. The experiments are performed in a closed spherical vessel with a volume of 8 dm3. The auto-ignition temperatures decrease from 300 degrees C to 250 degrees C when increasing the pressure from 1 bar to 14.5 bar. It is shown that the fuel concentration most sensitive to auto-ignition depends on initial pressure. A second series of experiments investigates the upper flammability limit of propane-air mixtures at initial temperatures up to 250 degrees C and pressures up to 30 bar near the auto-ignition area. Finally the propane auto-oxidation is modelled using several detailed kinetic reaction mechanisms and these numerical calculations are compared with the experimental results. PMID:16716499

  15. 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

    ... OF RESPIRATORY PROTECTIVE DEVICES Supplied-Air Respirators § 84.149 Type C supplied-air respirator... air-supply system, and the range of hose length for the respirator. For example, he might specify that... pressure at the point of attachment of the hose to the air-supply system shall not exceed 863 kN/m.2...

  16. 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

    ... OF RESPIRATORY PROTECTIVE DEVICES Supplied-Air Respirators § 84.149 Type C supplied-air respirator... air-supply system, and the range of hose length for the respirator. For example, he might specify that... pressure at the point of attachment of the hose to the air-supply system shall not exceed 863 kN/m.2...

  17. 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

    ... OF RESPIRATORY PROTECTIVE DEVICES Supplied-Air Respirators § 84.149 Type C supplied-air respirator... air-supply system, and the range of hose length for the respirator. For example, he might specify that... pressure at the point of attachment of the hose to the air-supply system shall not exceed 863 kN/m.2...

  18. 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

    ... OF RESPIRATORY PROTECTIVE DEVICES Supplied-Air Respirators § 84.149 Type C supplied-air respirator... air-supply system, and the range of hose length for the respirator. For example, he might specify that... pressure at the point of attachment of the hose to the air-supply system shall not exceed 863 kN/m.2...

  19. The Effects of Very Light Jet Air Taxi Operations on Commercial Air Traffic

    NASA Technical Reports Server (NTRS)

    Smith, Jeremy C.; Dollyhigh, Samuel M.

    2006-01-01

    This study investigates the potential effects of Very Light Jet (VLJ) air taxi operations adding to delays experienced by commercial passenger air transportation in the year 2025. The affordable cost relative to existing business jets and ability to use many of the existing small, minimally equipped, but conveniently located airports is projected to stimulate a large demand for the aircraft. The resulting increase in air traffic operations will mainly be at smaller airports, but this study indicates that VLJs have the potential to increase further the pressure of demand at some medium and large airports, some of which are already operating at or near capacity at peak times. The additional delays to commercial passenger air transportation due to VLJ air taxi operations are obtained from simulation results using the Airspace Concepts Evaluation System (ACES) simulator. The direct increase in operating cost due to additional delays is estimated. VLJs will also cause an increase in traffic density, and this study shows increased potential for conflicts due to VLJ operations.

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

    SciTech Connect

    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

  1. Air pollution holiday effect in metropolitan Kaohsiung

    NASA Astrophysics Data System (ADS)

    Tan, P.; Chen, P. Y.

    2014-12-01

    Different from Taipei, the metropolitan Kaohsiung which is a coastal and industrial city has the major pollution sources from stationary sources such as coal-fired power plants, petrochemical facilities and steel plants, rather than mobile sources. This study was an attempt to conduct a comprehensive and systematical examination of the holiday effect, defined as the difference in air pollutant concentrations between holiday and non-holiday periods, over the Kaohsiung metropolitan area. We documented evidence of a "holiday effect", where concentrations of NOx, CO, NMHC, SO2 and PM10 were significantly different between holidays and non-holidays, in the Kaohsiung metropolitan area from daily surface measurements of seven air quality monitoring stations of the Taiwan Environmental Protection Administration during the Chinese New Year (CNY) and non-Chinese New Year (NCNY) periods of 1994-2010. Concentrations of the five pollutants were lower in the CNY than in the NCNY period, however, that of O3 was higher in the CNY than in the NCNY period and had no holiday effect. The exclusion of the bad air quality day (PSI > 100) and the Lantern Festival Day showed no significant effects on the holiday effects of air pollutants. Ship transportation data of Kaohsiung Harbor Bureau showed a statistically significant difference in the CNY and NCNY period. This difference was consistent with those found in air pollutant concentrations of some industrial and general stations in coastal areas, implying the possible impact of traffic activity on the air quality of coastal areas. Holiday effects of air pollutants over the Taipei metropolitan area by Tan et al. (2009) are also compared.

  2. Compressibility and Heating Effects on Pressure Loss and Cooling of a Baffled Cylinder Barrel

    NASA Technical Reports Server (NTRS)

    Goldstein, Arthur W; Ellerbrock, Herman H , Jr

    1944-01-01

    Theoretical investigations have shown that, because air is compressible, the pressure-drop requirements for cooling an air-cooled engine will be much greater at high altitudes and high speeds than at sea level and low speeds. Tests were conducted by the NACA to obtain some experimental confirmation of the effect of air compressibility on cooling and pressure loss of a baffled cylinder barrel and to evaluate various methods of analysis. The results reported in the present paper are regarded as preliminary to tests on single-cylinder and multicylinder engines. Tests were conducted over a wide range of air flows and density altitudes.

  3. Surface treatment of aramid fiber by air dielectric barrier discharge plasma at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Jia, Caixia; Chen, Ping; Liu, Wei; Li, Bin; Wang, Qian

    2011-02-01

    Aramid fiber samples are treated by air dielectric barrier discharge (DBD) plasma at atmospheric pressure; the plasma treatment time is investigated as the major parameter. The effects of this treatment on the fiber surface physical and chemical properties are studied by using surface characterization techniques. Scanning electron microscopy (SEM) is performed to determine the surface morphology changes, X-ray photoelectron spectroscopy (XPS) is analyzed to reveal the surface chemical composition variations and dynamic contact angle analysis (DCAA) is used to examine the changes of the fiber surface wettability. In addition, the wetting behavior of a kind of thermoplastic resin, poly(phthalazinone ether sulfone ketone) (PPESK), on aramid fiber surface is also observed by SEM photos. The study shows that there seems to be an optimum treatment condition for surface modification of aramid fiber by the air DBD plasma. In this paper, after the 12 s, 27.6 W/cm3 plasma treatment the aramid fiber surface roughness is significantly improved, some new oxygen-containing groups such as C-O, Cdbnd O and Odbnd C-O are generated on the fiber surface and the fiber surface wettability is greatly enhanced, which results in the better wetting behavior of PPESK resin on the plasma-treated aramid fiber.

  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. Air-driven Brazil nut effect

    NASA Astrophysics Data System (ADS)

    Naylor, M.; Swift, Michael; King, P.

    2003-07-01

    A large heavy object may rise to the top of a bed of smaller particles under the influence of vertical vibration, the “Brazil nut effect.” Recently it has been noted that interstitial air can influence the Brazil nut rise time. Here we report that the air movement induced by vertical vibration produces a very strong Brazil nut effect for fine granular beds. We use a porous-bottomed box to investigate the mechanism responsible for this effect and to demonstrate that it is related to the piling of fine beds, first reported by Chladni and studied by Faraday. Both effects are due to the strong interaction of the fine particles with the air, as it is forced through the bed by the vibration.

  6. 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

  7. Diffuse plasma treatment of polyamide 66 fabric in atmospheric pressure air

    NASA Astrophysics Data System (ADS)

    Li, Lee; Peng, Ming-yang; Teng, Yun; Gao, Guozhen

    2016-01-01

    The polyamide 66 (PA66) fabrics are hard to be colored or glued in industrial production due to the poor hydrophily. Diffuse plasma is a kind of non-thermal plasma generated at atmospheric pressure in air. This paper proposes that large-scale diffuse plasma generated between wire electrodes can be employed for improving the hydrophily of PA66 fabrics. A repetitive nanosecond-pulse diffuse-discharge reactor using a cylindrical wire electrode configuration is presented, which can generate large-scale non-thermal plasmas steadily at atmospheric pressure without any barrier dielectric. Then the reactor is used to treat PA66 fabrics in different discharge conditions. The hydrophilicity property of modified PA66 is measured by wicking test method. The modified PA66 is also analyzed by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) to prove the surface changes in physical microstructure and chemical functional groups, respectively. What's more, the effects of treatment time and treatment frequency on surface modification are investigated and discussed.

  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. 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.

  10. 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.

  11. Air-pollution effects on biodiversity

    SciTech Connect

    Barker, J.R.; Tingey, D.T.

    1992-04-01

    To address the issues of air pollution impacts on biodiversity, the U.S. Environmental Protection Agency, Environmental Research Laboratory in Corvallis, OR, the U.S. Fish and Wildlife Service National Fisheries Research Center in Leetown, and the Electric Power Research Institute convened a workshop to evaluate current knowledge, identify information gaps, provide direction to research and assess policy issues. In order to obtain the most current and authoritative information possible, air pollution and biodiversity experts were invited to participate in a workshop and author the papers that make up this report. Each paper was presented and discussed, then collected in this document. The material has been organized into four parts: an introduction, an overview of air pollution exposure and effects, the consequences of air pollution on biodiversity, and policy issues and research needs.

  12. Air pollutants effects on forest ecosystems

    SciTech Connect

    Not Available

    1985-01-01

    This book presents the papers given at a conference on the effects of acid rain on forests. The conference was sponsored by the National Acid Precipitation Assessment Program (NAPAP). Topics considered at the conference included the status of US research on acid deposition and its effects contributing factors to the decline of forests, evidence for effects on ecosystems, the effects of air pollutants on forest ecosystems in North America and Europe, forest management, and future scientific research programs and management approaches.

  13. 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)

  14. 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…

  15. 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

  16. 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 ...

  17. 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)...

  18. 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)...

  19. 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)...

  20. 40 CFR 53.56 - Test for effect of variations in ambient pressure.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 6 2013-07-01 2013-07-01 false Test for effect of variations in ambient pressure. 53.56 Section 53.56 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) AMBIENT AIR MONITORING REFERENCE AND EQUIVALENT METHODS Procedures for Testing Physical (Design) and...

  1. Measurement of the First Townsend's Ionization Coefficients in Helium, Air, and Nitrogen at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Ran, Junxia; Luo, Haiyun; Yue, Yang; Wang, Xinxin

    2014-07-01

    In the past the first Townsend’s ionization coefficient α could only be measured with Townsend discharge in gases at low pressure. After realizing Townsend discharge in some gases at atmospheric pressure by using dielectric barrier electrodes, we had developed a new method for measuring α coefficient at atmospheric pressure, a new optical method based on the discharge images taken with ICCD camera. With this newly developed method α coefficient in helium, nitrogen and air at atmospheric pressure were measured. The results were found to be in good agreement with the data obtained at lower pressure but same reduced field E/p by other groups. It seems that the value of α coefficient is sensitive to the purity of the working gas.

  2. Non-LTE Steady-State Kinetics of He-Air Atmospheric Pressure Plasmas

    NASA Astrophysics Data System (ADS)

    Petrova, Tzvetelina; Petrov, George; Gillman, Eric; Boris, David; Hernández, Sandra; Walton, Scott

    2015-11-01

    A non-LTE, steady-state collisional-radiative kinetics model is developed to study discharges produced in mixtures of He, N2 and O2 (He-Air) at atmospheric pressures. The model is based on a self-consistent solution of coupled Boltzmann equation for the electron energy distribution function, electron energy balance equation, gas thermal balance equation, and a system of non-linear equations for species that govern plasma chemistry (electrons, ions, radicals, atoms and molecules in ground and excited states). The model and results can be applied to study a variety of atmospheric pressure plasmas generated in He-Air mixtures, such as plasma jets, dielectric barrier discharges, laser-induced plasmas, microwave plasmas, etc. In this talk, collisional rates and species densities are obtained as a function of He-to-air ratio and the results are benchmarked against available experimental data. Work supported by the NRL Base Program.

  3. Nonlinear effective pressure law for permeability

    NASA Astrophysics Data System (ADS)

    Li, M.; Xiao, W.-L.; Bernabé, Y.; Zhao, J.-Z.

    2014-01-01

    The permeability k of porous rocks is known to vary with confining pressure pc and pore fluid pressure pf. But it is, in principle, possible to replace the two-variable function k(pf, pc) by a function k(peff) of a single variable, peff(pf, pc), called the effective pressure. Our goal in this paper is to establish an experimental method for determining a possibly nonlinear, effective pressure law (EPL) for permeability, i.e., find the function κs(pf, pc) such that the effective pressure is given by peff = pc - κs(pf, pc) pf. We applied this method to a set of 26 sandstone cores from various hydrocarbon reservoirs in China. We found that κs greatly varied, from sample to sample, in magnitude and range, sometimes even reaching theoretically prohibited values (i.e., greater than 1 or lower than porosity). One interesting feature of κs(pf, pc) is that it could be approximately described in all rocks but one as a decreasing function κs(pc - pf) of Terzaghi's differential pressure. We also investigated the dependence of permeability on peff for each of our samples. Three models from the literature, i.e., exponential (E), power law (P), and the Walsh model (W), were tested. The (W) model was more likely to fit the experimental data of cores with a high pressure dependence of permeability whereas (E) occurred more frequently in low-pressure-sensitive rocks. Finally, we made various types of two- and three-dimensional microstructural observations that generally supported the trend mentioned above.

  4. Effects of Commercial Air Travel on Patients With Pulmonary Hypertension

    PubMed Central

    Elliott, C. Gregory; Barnett, Christopher F.; Blanc, Paul D.; Chen, Joan; De Marco, Teresa; Chen, Hubert

    2012-01-01

    Background: Limited data are available on the effects of air travel in patients with pulmonary hypertension (PH), despite their risk of physiologic compromise. We sought to quantify the incidence and severity of hypoxemia experienced by people with PH during commercial air travel. Methods: We recruited 34 participants for a prospective observational study during which cabin pressure, oxygen saturation (Spo2), heart rate, and symptoms were documented serially at multiple predefined time points throughout commercial flights. Oxygen desaturation was defined as Spo2 < 85%. Results: Median flight duration was 3.6 h (range, 1.0-7.3 h). Mean ± SD cabin pressure at cruising altitude was equivalent to the pressure 1,968 ± 371 m (6,456 ± 1,218 ft) above sea level (ASL) (maximum altitude = 2,621 m [8,600 ft] ASL). Median change in Spo2 from sea level to cruising altitude was −4.9% (range, 2.0% to −15.8%). Nine subjects (26% [95% CI, 12%-38%]) experienced oxygen desaturation during flight (minimum Spo2 = 74%). Thirteen subjects (38%) reported symptoms during flight, of whom five also experienced desaturations. Oxygen desaturation was associated with cabin pressures equivalent to > 1,829 m (6,000 ft) ASL, ambulation, and flight duration (all P values < .05). Conclusions: Hypoxemia is common among people with PH traveling by air, occurring in one in four people studied. Hypoxemia was associated with lower cabin pressures, ambulation during flight, and longer flight duration. Patients with PH who will be traveling on flights of longer duration or who have a history of oxygen use, including nocturnal use only, should be evaluated for supplemental in-flight oxygen. PMID:22490871

  5. 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.

  6. The impact of upstream blocking, drainage flow and the geostrophic pressure gradient on the persistence of cold-air pools

    NASA Astrophysics Data System (ADS)

    Zängl, G.

    2003-01-01

    Idealized numerical simulations are performed to investigate dynamical mechanisms affecting the persistence of cold-air pools in basins and valleys. The first orography type considered is a shallow elongated basin located upstream of a mountain ridge. For sensitivity tests, the mountain ridge is removed. The second type is a basin embedded in a plateau-like mountain ridge. In part of the simulations, this basin has an outflow towards the lee-side plain so as to assess the impact of the drainage flow.The large-scale flow is taken to be in geostrophic balance. In the standard setting, it is perpendicular to the basin and the ridge. The main effect of a large-scale pressure gradient is to induce a circulation within a cold-air pool until the upper boundary of the cold pool is inclined such as to compensate for the ambient pressure gradient. The cold air accumulates where the ambient pressure is lowest. For a shallow basin, this means that part of the cold air may be lost due to advection out of the basin. The upstream influence of a mountain ridge in the lee of a shallow basin is found to be twofold. It tends to deflect the low-level flow towards the lower pressure, leading to an additional ridge-parallel force on the cold-air pool. On the other hand, the absolute wind speed is reduced, diminishing the turbulent mixing near the top of the cold pool. The simulations show that the first effect prevails for ridge-normal flow while second effect may dominate for other flow directions. Drainage flow out of a valley is found to be very important as it promotes the penetration of warm air into valleys very effectively. It may cause a cold pool in a deep valley to disappear more quickly than a cold pool in a shallow basin. Sensitivity tests show that the persistence of a cold pool depends on its depth, on its vertically integrated heat deficit, and on the maximum heat deficit at the bottom of the cold pool.

  7. Effect of air on energy and rise-time spectra measured by proportional gas counter

    SciTech Connect

    Kawano, T.; Tanaka, M.; Isozumi, S.; Isozumi, Y.; Tosaki, M.; Sugiyama, T.

    2015-03-15

    Air exerts a negative effect on radiation detection using a gas counter because oxygen contained in air has a high electron attachment coefficient and can trap electrons from electron-ion pairs created by ionization from incident radiation in counting gas. This reduces radiation counts. The present study examined the influence of air on energy and rise-time spectra measurements using a proportional gas counter. In addition, a decompression procedure method was proposed to reduce the influence of air and its effectiveness was investigated. For the decompression procedure, the counting gas inside the gas counter was decompressed below atmospheric pressure before radiation detection. For the spectrum measurement, methane as well as various methane and air mixtures were used as the counting gas to determine the effect of air on energy and rise-time spectra. Results showed that the decompression procedure was effective for reducing or eliminating the influence of air on spectra measurement using a proportional gas counter. (authors)

  8. Effects of shock pressures on calcic plagioclase

    NASA Technical Reports Server (NTRS)

    Gibbons, R. V.; Ahrens, T. J.

    1977-01-01

    Calcic plagioclase single crystals were subjected to shock loading up to a pressure of 496 kbar; optical and electron microscope studies were conducted to investigate the shock-induced effects on the mineral, which is found in terrestrial and lunar rocks and in meteorites. It was observed that up to 287 kbar pressure, the recovered samples are essentially crystalline, while samples subjected to pressures between 300 and 400 kbar are almost 100% diaplectic glasses, suggesting shock transformation in the solid state. Samples shock-loaded to pressures greater than 400 kbar yielded glasses with refractive indices similar to those of thermally fused glass. It is concluded that planar features, absent in all the specimens, may not be definitive shock indicators, but may be linked to local heterogeneous dynamic stresses experienced by plagioclase grains within shocked rocks.

  9. 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.

  10. CVD mullite coatings in high-temperature, high-pressure air-H{sub 2}O[Chemical Vapor Deposition

    SciTech Connect

    Haynes, J.A.; Lance, M.J.; Cooley, K.M.; Ferber, M.K.; Lowden, R.A.; Stinton, D.P.

    2000-03-01

    Crystalline mullite was deposited by chemical vapor deposition (CVD) onto SiC/SiC composites overlaid with CVD SiC. Specimens were exposed to isothermal oxidation tests in high-pressure air +H{sub 2}O at 1,200 C. Unprotected CVD SiC formed silica scales with a dense amorphous inner layer and a thick, porous, outer layer of cristobalite. Thin coatings ({approximately}2{mu}m) of dense CVD mullite effectively suppressed the rapid oxidation of CVD SiC. No microstructural evidence of mullite volatility was observed under these temperature, pressure, and low-flow-rate conditions. Results of this preliminary study indicate that dense, crystalline, high-purity CVD mullite is stable and protective in low-velocity, high-pressure, moisture-containing environments.

  11. 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…

  12. 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

    ... 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 HEALTH... test; Type C supplied-air respirator, pressure-demand class; minimum requirements. (a) The...

  13. 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

    ... 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 HEALTH... test; Type C supplied-air respirator, pressure-demand class; minimum requirements. (a) The...

  14. 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

    ... 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 HEALTH... test; Type C supplied-air respirator, pressure-demand class; minimum requirements. (a) The...

  15. 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

    ... 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 HEALTH... test; Type C supplied-air respirator, pressure-demand class; minimum requirements. (a) The...

  16. 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

  17. The effect of ambient pressure on well chamber response: experimental results with empirical correction factors.

    PubMed

    Griffin, S L; DeWerd, L A; Micka, J A; Bohm, T D

    2005-03-01

    For some air-communicating well-type chambers used for low-energy brachytherapy source assay, deviations from expected values of measured air kerma strength were observed at low pressures associated with high altitudes. This effect is consistent with an overcompensation by the air density correction to standard atmospheric temperature and pressure (P(TP)). This work demonstrates that the P(TP) correction does not fully compensate for the high altitude pressure effects that are seen with air-communicating chambers at low photon energies in the range of 20-100 keV. Deviations of up to 18% at a pressure corresponding to an approximate elevation of 8500 ft for photon energies of 20 keV are possible. For high-energy photons and for high-energy beta emitters in air-communicating chambers the P(TP) factor is applicable. As expected, the ambient pressure does not significantly affect the response of pressurized well chambers (within 1%) to either low- or high-energy photons. However, when used with beta emitters, pressurized chambers appear to exhibit a slight dependence on the ambient pressure. Using measured data, the response and correction factors were determined for three models of air-communicating well chambers for low-energy photon sources at various pressures corresponding to elevations above sea level. Monte Carlo calculations were also performed which were correlated with the experimental findings. A more complete study of the Monte Carlo calculations is presented in the accompanying paper, "The effect of ambient pressure on well chamber response: Monte Carlo calculated results for the HDR1000 Plus." PMID:15839341

  18. Calculating osmotic pressure of xylitol solutions from molality according to UNIFAC model and measuring it with air humidity osmometry.

    PubMed

    Yu, Lan; Zhan, Tingting; Zhan, Xiancheng; Wei, Guocui; Tan, Xiaoying; Wang, Xiaolan; Li, Chengrong

    2014-11-01

    The osmotic pressure of xylitol solution at a wide concentration range was calculated according to the UNIFAC model and experimentally determined by our newly reported air humidity osmometry. The measurements from air humidity osmometry were compared with UNIFAC model calculations from dilute to saturated solution. Results indicate that air humidity osmometry measurements are comparable to UNIFAC model calculations at a wide concentration range by two one-sided test and multiple testing corrections. The air humidity osmometry is applicable to measure the osmotic pressure and the osmotic pressure can be calculated from the concentration. PMID:24032449

  19. Influence of atmospheric pressure supplied on permittivity of air-film of aerostatic bearing

    NASA Astrophysics Data System (ADS)

    Li, Min; Zhang, Yubing; Li, Dong-sheng

    2013-01-01

    Influence of atmospheric pressure supplied on permittivity of the air-film is researched based on the capacitive testing method of the air film thickness of aerostatic bearing. An experiment platform is designed. The experimental results illustrate that permittivity has significant negative correlation with atmospheric pressure which varies from 0.1MPa to 0.48MPa when other environmental conditions remain unchanged. The curves conform to the fourth-order polynomial approximately. All of the values of R2 are beyond 0.944 which means that trend lines fit the data curves well. Relative permittivity of the air film is between 0.996 and 1.324. This interval shows that weak current exists between restrictor and flat of the experiment which are not absolutely insulating and atmosphere of the air film is not pure. This result provides a basis both for establishing accurate mathematical model of air film thickness and capacitance value of the aerostatic bearing and for other exploratory experiments later.

  20. 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.

  1. 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

  2. The effect of air leakage and heat exchange on the decay of entrapped air pocket slamming oscillations

    NASA Astrophysics Data System (ADS)

    Abrahamsen, Bjørn C.; Faltinsen, Odd M.

    2011-10-01

    The phenomenon studied in this work is that of an air pocket entrapped by a free surface water wave inside a rectangular tank at a high filling level. The wave, which is a gravity wave, is caused by forced horizontal motion which is constructed in a particular way, in order to entrap an air pocket as it approaches the upper left corner of the tank. As the wave touches the roof, the air is compressed and starts to oscillate. The oscillations resemble, to some extent, the free oscillations of an underdamped mass-spring system, where the mass is related to the generalized added mass effect of the water pressure associated with the air pocket oscillations. The stiffness is due to the compressibility of the air. The reason for the damping or, more generally, the decay of the air pocket oscillations is less understood. Air leakage has been proposed as one possible reason for this decay. In this work, the role of air leakage is found not to be the reason for the decay of the air pocket oscillations, because it is not present during major parts of the impact. However, by drilling holes in the roof of the tank, the effect of leakage during the oscillations is proven to cause decay. To explain the physical source of the decay of the oscillations, damping due to heat transfer to and from the air pocket is investigated through an analytical one-dimensional steady-state model. The damping due to heat transfer is observed to play an important role. The obtained understanding of the mechanisms causing the decay of the air-pocket impact at the upper corner is believed to be relevant to other types of impacts, particularly the entrapment of air pockets on walls by breaking waves.

  3. 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.

  4. 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.

  5. 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.

  6. Plasma formation in atmospheric pressure helium discharges under different background air pressures

    SciTech Connect

    Liu Yaoge; Hao Yanpeng; Zheng Bin

    2012-09-15

    Atmospheric pressure glow discharges generated between parallel-plate electrodes in helium have been characterized using temporally resolved emission spectra. The variation of typical spectral lines over time has been analyzed. In helium with a low concentration of N{sub 2}, the emission of He at 706.5 nm is dominant and appears 500 ns earlier than N{sub 2}{sup +} first negative bands, indicating low reaction rates of Penning ionization and charge transfer in the initial stage. During the decay, it is the Penning ionization caused by He metastables with a long lifetime rather than the charge transfer reaction that leads to the long decay of N{sub 2}{sup +} emissions. When helium contains a higher concentration of N{sub 2} molecules, the N{sub 2}{sup +} first negative bands become the most intense, and emissions from He, N{sub 2}{sup +}, and O exhibit similar behavior as they increase. The emissions last for a shorter time under such conditions because of rapid consumption of He metastables and He{sub 2}{sup +}.

  7. 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.

  8. 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.

  9. 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.

  10. Femtosecond filamentation in air at low pressures. Part II: Laboratory experiments

    NASA Astrophysics Data System (ADS)

    Méchain, G.; Olivier, T.; Franco, M.; Couairon, A.; Prade, B.; Mysyrowicz, A.

    2006-05-01

    We present experimental studies of filamentation of a femtosecond laser pulse in air at low pressures. The evolution of the filament has been studied by measuring along the propagation axis the conductivity and the sub-THz emission from the plasma channel. We show experimentally that the filamentation process occurs at pressures as low as 0.2 atm in agreement with numerical simulations. Experimental and numerical results [A. Couairon, M. Franco, G. Méchain, T. Olivier, B. Prade, A. Mysyrowicz, Opt. Commun., submitted for publication] are compared and the possible sources of discrepancy are discussed.

  11. The Effect of Charge Reactive Metal Cases on Air Blast

    NASA Astrophysics Data System (ADS)

    Zhang, Fan; Wilson, William H.

    2009-12-01

    Experiments were conducted in a 23 m3 closed chamber using a charge encased in a cylindrical reactive metal case to study the effect on air blast from the case fragments. Parameters varied included case/charge mass ratio, charge diameter and charge type (i.e., detonation energy and pressure). The pressure histories measured on the chamber wall showed a double-shock front structure with an accelerating precursor shock followed by the primary shock, suggesting the early-time reaction of small case fragments. During the early reflections on the chamber wall, significant pressure rises versus the steel-cased and bare charges indicated combustion of a large amount of small case particles generated by secondary fragmentation. The analysis of explosion pressures and recovered fragments and solid products gave an expression for burnt casing mass as a function of Gurney velocity and charge diameter. The equivalent bare charge mass that yields the same explosion pressure as the cased charge increased with case/charge mass ratio and reached 2.5 times charge mass at the ratio of 1.75.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. The Effect of Anthocyanins on Blood Pressure

    PubMed Central

    Zhu, Yongjian; Bo, Yacong; Wang, Xi; Lu, Wenjie; Wang, Xule; Han, Zhanying; Qiu, Chunguang

    2016-01-01

    Abstract The findings of clinical studies concerning the association between anthocyanins supplementation and blood pressure (BP) are inconsistent. In order to provide a more precise estimate of the overall effect of anthocyanins on systolic blood pressure (SBP) and diastolic blood pressure (DBP), we conducted a meta-analysis of clinical trials about anthocyanins supplementation and BP. PubMed, Web of Science, Wanfang Database, and China National Knowledge Infrastructure (CNKI) (until October 2015) were searched to identify potential studies with information on anthocyanins extract supplementation and arterial BP. The weighted mean difference (WMD) and 95% confidence interval (CI) were used as a summary statistic. Net changes in SBP and DBP between anthocyanins supplementation and placebo groups were calculated by subtracting the values at end of follow-up from those at baseline. Meta regression was used to explore the potential moderators of effect size. The publication bias was assessed using Begger's Funnel plots and Egger's tests; P < 0.05 was considered to be statistically significant. Finally, 6 clinical studies with 472 participants for the effect of anthocyanins consumption on BP were included in the present meta-analysis. There is no significant effect on either SBP (WMD: 1.15 mm Hg, 95% CI: −3.17 to 5.47, I2 = 56%) or DBP (WMD: 1.06 mm Hg, 95% CI: −0.71 to 2.83, I2 = 0%) following supplementation with anthocyanins. In summary, results from this meta-analysis do not favor any clinical efficacy of supplementation with anthocyanins in improving blood pressure. Further well-designed large randomized controlled trials (RCTs) with long follow-up period are needed to verify the association of anthocyanins supplementation and blood pressure. PMID:27082604

  17. 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.

  18. 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.

  19. Laser-rf creation and diagnostics of seeded atmospheric pressure air and nitrogen plasmas

    SciTech Connect

    Luo Siqi; Denning, C. Mark; Scharer, John E.

    2008-07-01

    A laser initiation and radio frequency (rf) sustainment technique has been developed and improved from our previous work to create and sustain large-volume, high-pressure air and nitrogen plasmas. This technique utilizes a laser-initiated, 15 mTorr partial pressure tetrakis (dimethylamino) ethylene seed plasma with a 75 Torr background gas pressure to achieve high-pressure air/nitrogen plasma breakdown and reduce the rf power requirement needed to sustain the plasma. Upon the laser plasma initiation, the chamber pressure is raised to 760 Torr in 0.5 s through a pulsed gas valve, and the end of the chamber is subsequently opened to the ambient air. The atmospheric-pressure plasma is then maintained with the 13.56 MHz rf power. Using this technique, large-volume (1000 cm{sup 3}), high electron density (on the order of 10{sup 11-12} cm{sup -3}), 760 Torr air and nitrogen plasmas have been created while rf power reflection is minimized during the entire plasma pulse utilizing a dynamic matching method. This plasma can project far away from the antenna region (30 cm), and the rf power budget is 5 W/cm{sup 3}. Temporal evolution of the plasma electron density and total electron-neutral collision frequency during the pulsed plasma is diagnosed using millimeter wave interferometry. Optical emission spectroscopy (OES) aided by SPECAIR, a special OES simulation program for air-constituent plasmas, is used to analyze the radiating species and thermodynamic characteristics of the plasma. Rotational and vibrational temperatures of 4400-4600{+-}100 K are obtained from the emission spectra from the N{sub 2}(2+) and N{sub 2}{sup +}(1-) transitions by matching the experimental spectrum results with the SPECAIR simulation results. Based on the relation between the electron collision frequency and the neutral density, utilizing millimeter wave interferometry, the electron temperature of the 760 Torr nitrogen plasma is found to be 8700{+-}100 K (0.75{+-}0.1 eV). Therefore, the plasma

  20. 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

  1. 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.

  2. The Air Toxics Health Effects Database (ATHED)

    SciTech Connect

    Woodall, George M. Smith, Roy L.

    2008-11-15

    The Air Toxics Health Effects Database (ATHED) is currently used by the EPA's Office of Air Quality Planning and Standards (OAQPS) to support risk assessments for the Residual Risk Program. An assessment of the residual risk is required to be performed at a specified time (typically 8years) following the promulgation of a technology-based Maximum Achievable Control Technologies (MACT) standard. The goal of the Residual Risk Program is to assure that the risk that remains after MACT standards are implemented (i.e., the 'residual risk') is acceptable, and if not, to propose additional regulations to mitigate those risks. ATHED maintains all available reference values for each chemical as separate data records, and includes values for all exposure durations (acute, short-term, subchronic and chronic). These values are used as benchmarks to determine acceptable exposure levels to the hazardous air pollutants (HAPs) listed in Section 112 of the Clean Air Act. ATHED also provides useful background information on the uncertainty and/or modifying factors that were applied in the derivation of each reference value, as well as the point of departure and the critical study/studies. To facilitate comparisons across durations for a specific chemical, ATHED data can be graphically presented.

  3. Laminar burning velocities of lean hydrogen-air mixtures at pressures up to 1.0 MPa

    SciTech Connect

    Bradley, D.; Lawes, M.; Liu, Kexin; Woolley, R.; Verhelst, S.

    2007-04-15

    Values of laminar burning velocity, u{sub l}, and the associated strain rate Markstein number, Ma{sub sr}, of H{sub 2}-air mixtures have been obtained from measurements of flame speeds in a spherical explosion bomb with central ignition. Pressures ranged from 0.1 to 1.0 MPa, with values of equivalence ratio between 0.3 and 1.0. Many of the flames soon became unstable, with an accelerating flame speed, due to Darrieus-Landau and thermodiffusive instabilities. This effect increased with pressure. The flame wrinkling arising from the instabilities enhanced the flame speed. A method is described for allowing for this effect, based on measurements of the flame radii at which the instabilities increased the flame speed. This enabled u{sub l} and Ma{sub sr} to be obtained, devoid of the effects of instabilities. With increasing pressure, the time interval between the end of the ignition spark and the onset of flame instability, during which stable stretched flame propagation occurred, became increasingly small and very high camera speeds were necessary for accurate measurement. Eventually this time interval became so short that first Ma{sub sr} and then u{sub l} could not be measured. Such flame instabilities throw into question the utility of u{sub l} for high pressure, very unstable, flames. The measured values of u{sub l} are compared with those predicted by detailed chemical kinetic models of one-dimensional flames. (author)

  4. Effects of tamsulosin on resting urethral pressure and arterial blood pressure in anaesthetized female dogs.

    PubMed

    Ohtake, Akiyoshi; Sato, Shuichi; Sasamata, Masao; Miyata, Keiji

    2006-03-01

    The purposes of the present study were to investigate the effects of the alpha1-adrenoceptor antagonists tamsulosin, prazosin and urapidil on resting urethral pressure in anaesthetized female dogs, and to compare the results with their effects on arterial blood pressure. Tamsulosin decreased resting maximal urethral pressure in the urethral pressure profile in a dose-dependent fashion, whereas it had almost no effect on mean arterial blood pressure. Prazosin and urapidil also dose-dependently decreased resting maximal urethral pressure, but these effects were accompanied by decreases in mean arterial blood pressure. Thus, of these three compounds, tamsulosin dose-dependently decreased resting maximal urethral pressure with negligible effect on mean arterial blood pressure in female dogs. These results suggest that tamsulosin will be useful in the treatment of voiding dysfunction associated with bladder outlet obstruction in women, with little hypotensive effect. PMID:16536901

  5. 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

  6. 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

  7. New data for aerosols generated by releases of pressurized powders and solutions in static air

    SciTech Connect

    Ballinger, M.Y.; Sutter, S.L.; Hodgson, W.H.

    1987-05-01

    Safety assessments and environmental impact statements for nuclear fuel cycle facilities require an estimate of potential airborne releases. Aerosols generated by accidents are being investigated by Pacific Northwest Laboratory to develop radioactive source-term estimation methods. Experiments measuring the mass airborne and particle size distribution of aerosols produced by pressurized releases were run. Carbon dioxide was used to pressurize uranine solutions to 50, 250, and 500 psig before release. The mass airborne from these experiments was higher than for comparable air-pressurized systems, but not as great as expected based on the amount of gas dissolved in the liquid and the volume of liquid ejected from the release equipment. Flashing sprays of uranine at 60, 125, and 240 psig produced a much larger source term than all other pressurized releases performed under this program. Low-pressure releases of depleted uranium dioxide at 9, 17.5, and 24.5 psig provided data in the energy region between 3-m spills and 50-psig pressurized releases.

  8. Emissions measurements for a lean premixed propane/air system at pressures up to 30 atmospheres

    NASA Technical Reports Server (NTRS)

    Roffe, G.

    1979-01-01

    A series of experiments was conducted in which the emissions of a lean premixed system of propane and air were measured at pressures of 5, 10, 20 and 30 atm in a flametube apparatus. Measurements were made for inlet temperatures between 600K and 1000K and combustor residence times from 1.0 to 3.0 msec. A schematic of the test rig is presented along with graphs showing emissions measurements for nitric oxide, carbon monoxide, and UHC as functions of bustor residence time for various equivalence ratios, entrance temperatures and pressures; typical behavior of emissions as a function of equivalence ratio for a fixed residence time. Correlations of nitric oxide emission index with adiabatic flame temperature for a fixed residence time of 2 msec and pressures from 5 to 30 atm; and adiabatic flame temperature corresponding to CO breakpoint conditions for 2 msec residence time as a function of inlet temperature.

  9. 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.

  10. Inactivation of Staphylococcus aureus and Enterococcus faecalis by a direct-current, cold atmospheric-pressure air plasma microjet☆

    PubMed Central

    Tian, Ye; Sun, Peng; Wu, Haiyan; Bai, Na; Wang, Ruixue; Zhu, Weidong; Zhang, Jue; Liu, Fuxiang

    2010-01-01

    Objective A direct-current, cold atmospheric-pressure air plasma microjet (PMJ) was performed to inactivate Staphylococcus aureus (S. aureus) and Enterococcus faecalis (E. faecalis) in air. The process of sterilization and morphology of bacteria was observed. We wish to know the possible inactivation mechanisms of PMJ and explore a potential application in dental and other temperature sensitive treatment. Methods In this study, we employed a direct current, atmospheric pressure, cold air PMJ to inactivate bacterias. Scanning electron microscopy was employed to evaluate the morphology of S. aureus and showed rupture of cell walls after the plasma treatment and Optical emission spectrum (OES) were used to understand the possible inactivation mechanisms of PMJ. Results The inactivation rates could reach 100% in 5 min. When the distance between the exit nozzle of the PMJ device and Petri dish was extended from 1 cm to 3 cm, effective inactivation was also observed with a similar inactivation curve. Conclusion The inactivation of bacteria is attributed to the abundant reactive oxygen and nitrogen species, as well as ultroviolet radiation in the plasma. Different life spans and defensibilities of these killing agents may hold the key to understanding the different inactivation curves at different treatment distances. PMID:23554639

  11. Effects of pressure on arterial failure.

    PubMed

    Khamdaengyodtai, Pannathai; Vafai, Kambiz; Sakulchangsatjatai, Phrut; Terdtoon, Pradit

    2012-10-11

    A three-dimensional multilayer model of mechanical response for analyzing the effect of pressure on arterial failure is presented in this work. The multilayer arterial wall is considered to be composed of five different layers. The three-dimensional effects are incorporated within the five-concentric axisymmetric layers while incorporating the nonlinear elastic characteristics under combined extension and inflation. Constitutive equations for fiber-reinforced material are employed for three of the major layers, i.e., intima, media and adventitia and an isotropic material model is employed for the other two layers, i.e., endothelium and internal elastic lamina. Our own developed three-dimensional five-layer model has been utilized to model propagated rupture area of the arterial wall. Required parameters for each layer are obtained by using a nonlinear least square method fitted to in vivo non-invasive experimental data of human artery and the effects of pressure on arterial failure are examined. The solutions from our computational model are compared with previous studies and good agreements are observed. Local stresses and strain distributions across the deformed arterial wall are illustrated and consequently the rupture area is predicted by varying luminal pressure in the physiological range and beyond. The effects of pressure on the arterial failure have been interpreted based on this comprehensive three-dimensional five-layer arterial wall model. This is the first study which employs two constitutive equations and incorporates a five-layer arterial wall model in three-dimensions based on in vivo non-invasive experimental data for a human artery. PMID:22980577

  12. Air quality effects of residential wood combustion

    SciTech Connect

    Cannon, J.A.

    1984-09-01

    In the mid 1970s the air quality in Missoula, Montana began to deteriorate due to pollution from wood-burning stoves. By 1980, 12,000 households were heating their homes with wood to some degree. Consequently, particulate concentrations rose sharply, with concentrations of over 500 ..mu..g/m/sup 3/ on many days. Because of health concerns, the Montana Department of Health and Environmental Sciences carried out an air pollution study. According to the data studied, airborne particulates appeared to be impairing the pulmonary function of children and older individuals with obstructive pulmonary disease. The correlation between human health effects and wood stove emissions was even more serious because of the size of the particulates; i.e., less than ten microns in diameter. A number of communities across the country have instituted voluntary and/or mandatory restrictions on local wood-burning. EPA has been involved in a number of activities that support the efforts of any community that thinks it has a potential air quality problem caused by residential wood combustion. The agency has also funded research on mutagenic and carcinogenic effects of wood smoke emission on mamallian cells and rodents.

  13. Effects of pressure anisotropy on plasma transport

    SciTech Connect

    Zawaideh, E.; Najmabadi, F.; Conn, R.W.

    1986-03-01

    In a recent paper a new set of generalized two-field equations is derived which describes plasma transport along the field lines of a space and time dependent magnetic field. These equations are valid for collisional to weakly collisional plasmas; they reduce to the conventional fluid equations of Braginskii for highly collisional plasmas. An important feature of these equations is that the anisotropy in the ion pressure is explicitly included. In this paper, these generalized transport equations are applied to a model problem of plasma flow through a magnetic mirror field. The profiles of the plasma parameters (density, flow speed, and pressures) are numerically calculated for plasma in different collisionality regimes. These profiles are explained by examining the competing terms in the transport equation. The pressure anisotropy is found to profoundly impact the plasma flow behavior. As a result, the new generalized equations predict flow behavior more accurately than the conventional transport equations. A large density and pressure drop is predicted as the flow passes through a magnetic mirror. Further, the new equations uniquely predict oscillations in the density profile, an effect missing in results from the conventional equations.

  14. Development of a diffuse air-argon plasma source using a dielectric-barrier discharge at atmospheric pressure

    SciTech Connect

    Tang Jie; Jiang Weiman; Zhao Wei; Wang Yishan; Li Shibo; Wang Haojing; Duan Yixiang

    2013-01-21

    A stable diffuse large-volume air plasma source was developed by using argon-induced dielectric-barrier discharges at atmospheric pressure. This plasma source can be operated in a filamentary discharge with the average areal power density of 0.27 W/cm{sup 2} and the gas temperature of 315{+-}3 K. Spatial measurement of emission spectrum and temperature indicates that this plasma is uniform in the central region along the transverse direction. It is also found that the formation of diffuse air plasma mainly lies in the creation of sufficient seed electrons by the Penning effect through collisions between two argon or nitrogen metastables at low electric fields.

  15. 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.

  16. 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

  17. 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.

  18. 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

  19. Technology Solutions Case Study: Ventilation System Effectiveness and Tested Indoor Air Quality Impacts

    SciTech Connect

    A. Rudd and D. Bergey

    2015-08-01

    Ventilation system effectiveness testing was conducted at two unoccupied, single-family, detached lab homes at the University of Texas - Tyler. Five ventilation system tests were conducted with various whole-building ventilation systems. Multizone fan pressurization testing characterized building and zone enclosure leakage. PFT testing showed multizone air change rates and interzonal airflow filtration. Indoor air recirculation by a central air distribution system can help improve the exhaust ventilation system by way of air mixing and filtration. In contrast, the supply and balanced ventilation systems showed that there is a significant benefit to drawing outside air from a known outside location, and filtering and distributing that air. Compared to the Exhaust systems, the CFIS and ERV systems showed better ventilation air distribution and lower concentrations of particulates, formaldehyde and other VOCs.

  20. Effect of Exhaust Pressure on the Cooling Characteristics of a Liquid-Cooled Engine

    NASA Technical Reports Server (NTRS)

    Doyle, Ronald B.; Desmon, Leland G.

    1947-01-01

    Data for a liquid-cooled engine with a displacement volume of 1710 cubic inches were analyzed to determine the effect of exhaust pressure on the engine cooling characteristics. The data covered a range of exhaust pressures from 7 to 62 inches of mercury absolute, inlet-manifold pressures from 30 to 50 inches of mercury absolute, engine speeds from 1600 to 3000 rpm, and fuel-air ratios from 0.063 to 0.100. The effect of exhaust pressure on engine cooling was satisfactorily incorporated in the NACA cooling-correlation method as a variation in effective gas temperature with exhaust pressure. Large variations of cylinder-head temperature with exhaust pressure were obtained for operation at constant charge flow. At a constant charge flow of 2 pounds per second (approximately 1000 bhp) and a fuel-air ratio of 0.085, an increase in exhaust pressure from 10 to 60 inches of mercury absolute resulted in an increase of 40 F in average cylinder-head temperature. For operation at constant engine speed and inlet-manifold pressure and variable exhaust pressure (variable charge flow), however, the effect of exhaust pressure on cylinder-head temperature is small. For example, at an inlet-manifold pressure of 40 inches of mercury absolute, an engine speed of 2400 rpm.- and a fuel-air ratio of 0.085, the average cylinder-head temperature was about the same at exhaust pressures of 10 and 60 inches of,mercury absolute; a rise and a subsequent decrease of about 70 occurred between these extremes.

  1. Extended effects of air pollution on cardiopulmonary mortality in Vienna

    NASA Astrophysics Data System (ADS)

    Neuberger, Manfred; Rabczenko, Daniel; Moshammer, Hanns

    BackgroundCurrent standards for fine particulates and nitrogen dioxide are under revision. Patients with cardiovascular disease have been identified as the largest group which need to be protected from effects of urban air pollution. MethodsWe sought to estimate associations between indicators of urban air pollution and daily mortality using time series of daily TSP, PM 10, PM 2.5, NO 2, SO 2, O 3 and nontrauma deaths in Vienna (Austria) 2000-2004. We used polynomial distributed lag analysis adjusted for seasonality, daily temperature, relative humidity, atmospheric pressure and incidence of influenza as registered by sentinels. ResultsAll three particulate measures and NO 2 were associated with mortality from all causes and from ischemic heart disease and COPD at all ages and in the elderly. The magnitude of the effect was largest for PM 2.5 and NO 2. Best predictor of mortality increase lagged 0-7 days was PM 2.5 (for ischemic heart disease and COPD) and NO 2 (for other heart disease and all causes). Total mortality increase, lagged 0-14 days, per 10 μg m -3 was 2.6% for PM 2.5 and 2.9% for NO 2, mainly due to cardiopulmonary and cerebrovascular causes. ConclusionAcute and subacute lethal effects of urban air pollution are predicted by PM 2.5 and NO 2 increase even at relatively low levels of these pollutants. This is consistent with results on hospital admissions and the lack of a threshold. While harvesting (reduction of mortality after short increase due to premature deaths of most sensitive persons) seems to be of minor importance, deaths accumulate during 14 days after an increase of air pollutants. The limit values for PM 2.5 and NO 2 proposed for 2010 in the European Union are unable to prevent serious health effects.

  2. 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 ...

  3. Indicated mean-effective pressure instrument

    NASA Technical Reports Server (NTRS)

    Rice, W. J. (Inventor)

    1978-01-01

    An apparatus for measuring indicated mean effective pressure (IMEP) of an internal combustion piston or rotary engine or of an external combustion engine such as a stirling engine is disclosed. An optical shaft encoder measures crankshaft angle of the engine. Changes in volume with respect to changes in crank angle of one or more cylinders (dV/d theta) is determined either empirically or algebraically from engine geometry and stored in a memory. As the crank angle changes, dV/d theta) is read from the memory and multiplied by chamber or cylinder pressure. The product (P dv/d theta) is then added to the total previously accumulated in the cycle. Each time theta changes by an amount equal to delta theta, the process is repeated. At the end of each engine cycle, the total is equal to the IMEP value for that cycle.

  4. Filament wound pressure vessels - Effects of using liner tooling of low pressure vessels for high pressure vessels development

    NASA Astrophysics Data System (ADS)

    Lal, Krishna M.

    High performance pressure vessels have been recently demanded for aerospace and defense applications. Filament wound pressure vessels consist of a metallic thin liner, which also acts as a mandrel, and composite/epoxy overwrap. Graphite/epoxy overwrapped vessels have been developed to obtain the performance ratio, PV/W, as high as one million inches. Under very high pressure the isotropic metallic liner deforms elasto-plastically, and orthotropic composite fibers deform elastically. Sometimes, for the development of ultra high pressure vessels, composite pressure vessels industry uses the existing liner tooling developed for low burst pressure capacity composite vessels. This work presents the effects of various design variables including the low pressure liner tooling for the development of the high burst pressure capacity Brilliant Pebbles helium tanks. Advance stress analysis and development of an ultra high pressure helium tank.

  5. Development and Performance Evaluation of an Ozone-Contained Ice Making Machine Employing Pressurized Air Tight Containers

    NASA Astrophysics Data System (ADS)

    Yoshimura, Kenji; Akiyama, Tomoaki; Hirofuji, Yushi; Koyama, Shigeru

    Ozone has the capability of sterilization and deodorization due to high oxidation power. It is also effective for the conservation of perishable foods and purification of water. However, ozone has a disadvantage, that is, conservation of ozone is difficult because it reacts to oxygen. Recently, ozone-contained ice is taken attention for the purpose of its conservation. The use of ozone-contained ice seems to keep food fresher when we conserve and transport perishable foods due to the effects of cooling and sterilization of ozone-contained ice. In the present study, we have developed an ozone-contained ice making machine employing pressurized air tight containers with commercially available size. And the performance evaluation of the system is also carried out. Furthermore, we investigated the sterilization effect of ozone-contained ice on conservation of fish. It was seen that ozone-contained ice is effective for sterilization of surface of fish.

  6. Design of a two dimensional planer pressurized air labyrinth seal test rig

    NASA Astrophysics Data System (ADS)

    Konicki, Joseph S.

    1993-12-01

    A two-dimensional planer labyrinth seal test rig was designed to operate with air supplied at 45 psig and temperatures up to 150 F. The rig operates with a manually specified test section pressure up to 30 psig yielding Mach numbers to 0.9 and gap Reynolds numbers to 100,000. The air flow rate through the seal will be controlled by setting inlet pressure and adjusting an outlet control valve. The test section measurements are 18 inches wide by 1.5 inches depth by 6 inches in length and provides for 10:1 large scale geometry seals to be used to facilitate measurements. Design maximum seal gap size is 0.15 inches. The test section has a glass viewing port to allow flow field measurement by non-intrusive means such as Laser Doppler Velocimeter (LDV) with seals containing up to 5 sealing knives. Measurements of pressure, temperature and flow fields can also be simultaneously measured by probes inserted in the seal itself, or mounted on the removable/replaceable top plate. Inlet flow is conditioned through the use of a dump diffuser incorporating screens, honeycombs, expansion and contraction portions. The inlet flow to the test section can be modified from uniform to various non-uniform conditions by employing profile generators such as screens and winglets. A detailed mechanical design has been conducted including stress analysis and seal flow rate predictions.

  7. Effect of back pressure on emulsification of lipid nanodispersions in a high-pressure homogenizer.

    PubMed

    Saheki, Akira; Seki, Junzo; Nakanishi, Takeo; Tamai, Ikumi

    2012-01-17

    We examined the effect of 0-20% back pressure, which functions as a resistance to emulsification in a high-pressure homogenizer, on emulsification of lipid nanodispersions (emulsion and liposomes) less than 100 nm in diameter. Back pressure in the range of 0.9-3.8% of the emulsification pressure enhanced the emulsification, and the particle diameter of lipid nanodispersion was the smallest at 2% back pressure. The back pressure effect was independent of the actual pressure, which was regarded as the difference between the emulsification and the back pressures. The mechanism of the back pressure effect was considered to be enhancement of emulsification by suppression of collapse cavitation in the high-pressure emulsification module. This back pressure effect appeared in emulsification of emulsion and liposomes, and was seen predominantly in the early emulsification phase (within 10 passages). The particles of lipid nanodispersions prepared at 2% back pressure with adequate re-circulation achieved physicochemically optimal diameter with a narrow size distribution, and were more stable at 60°C for 7 days than particles prepared with 20% back pressure. Our results indicate that emulsification with a low level of back pressure is effective for production of stable lipid nanodispersions with narrow size distribution. PMID:22108638

  8. Vapor pressure deficit effects on leaf area expansion and transportation of soybean subjected to soil drying

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Effects of leaf-to-air vapor pressure difference (VPD) and soil water deficit on transpiration rate (TR) of plants are well understood but their effects on plant leaf area expansion (PLAE) are less defined. Both PLAE and TR are unaffected by soil drying until the fraction transpirable soil water (FT...

  9. 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.

  10. 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.

  11. A comparison between the dimensions of positive transtibial residual limb molds prepared by air pressure casting and weight-bearing casting methods

    PubMed Central

    Hajiaghaei, Behnam; Ebrahimi, Ismail; Kamyab, Mojtaba; Saeedi, Hassan; Jalali, Maryam

    2016-01-01

    Background: Creating a socket with proper fit is an important factor to ensure the comfort and control of prosthetic devices. Several techniques are commonly used to cast transtibial stumps but their effect on stump shape deformation is not well understood. This study compares the dimensions, circumferences and volumes of the positive casts and also the socket comfort between two casting methods. Our hypothesis was that the casts prepared by air pressure method have less volume and are more comfortable than those prepared by weight bearing method. Methods: Fifteen transtibial unilateral amputees participated in the study. Two weight bearing and air pressure casting methods were utilized for their residual limbs. The diameters and circumferences of various areas of the residual limbs and positive casts were compared. The volumes of two types of casts were measured by a volumeter and compared. Visual Analogue Scale (VAS) was used to measure the sockets fit comfort. Results: Circumferences at 10 and 15 cm below the patella on the casts were significantly smaller in air pressure casting method compared to the weight bearing method (p=0.00 and 0.01 respectively). The volume of the cast in air pressure method was lower than that of the weight bearing method (p=0.006). The amputees found the fit of the sockets prepared by air pressure method more comfortable than the weight bearing sockets (p=0.015). Conclusion: The air pressure casting reduced the circumferences of the distal portion of residual limbs which has more soft tissue and because of its snug fit it provided more comfort for amputees, according to the VAS measurements. PMID:27390711

  12. 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.

  13. Reviewing the Literature on the Effectiveness of Pressure Relieving Movements

    PubMed Central

    Stinson, May

    2013-01-01

    Sitting for prolonged periods of time increases seating interface pressures, which is known to increase the risk of developing pressure ulcers. Those at risk of developing pressure ulcers are advised to perform pressure relieving movements such as “pushups” or “forward leans” in order to reduce the duration and magnitude of pressure acting on the vulnerable ischial tuberosity region. The aim of this review was to synthesize and critique the existing literature investigating the effectiveness of pressure relieving movements on seating interface pressures. The twenty-seven articles included in this paper highlight the need for further research investigating the effect of recommended pressure relieving movements on the pressures around the ischial tuberosities. Furthermore, this review found that the majority of individuals at risk of developing pressure ulcers do not adhere with the pressure relieving frequency or magnitude of movements currently recommended, indicating a need for pressure ulcer prevention to be explored further. PMID:23365733

  14. Evaluative pressure overcomes perceptual load effects.

    PubMed

    Normand, Alice; Autin, Frédérique; Croizet, Jean-Claude

    2015-06-01

    Perceptual load has been found to be a powerful bottom-up determinant of distractibility, with high perceptual load preventing distraction by any irrelevant information. However, when under evaluative pressure, individuals exert top-down attentional control by giving greater weight to task-relevant features, making them more distractible from task-relevant distractors. One study tested whether the top-down modulation of attention under evaluative pressure overcomes the beneficial bottom-up effect of high perceptual load on distraction. Using a response-competition task, we replicated previous findings that high levels of perceptual load suppress task-relevant distractor response interference, but only for participants in a control condition. Participants under evaluative pressure (i.e., who believed their intelligence was assessed) showed interference from task-relevant distractor at all levels of perceptual load. This research challenges the assumptions of the perceptual load theory and sheds light on a neglected determinant of distractibility: the self-relevance of the performance situation in which attentional control is solicited. PMID:25233881

  15. Comparison of surface modification of polypropylene film by filamentary DBD at atmospheric pressure and homogeneous DBD at medium pressure in air

    NASA Astrophysics Data System (ADS)

    Fang, Z.; Xie, X.; Li, J.; Yang, H.; Qiu, Y.; Kuffel, E.

    2009-04-01

    Non-equilibrium plasmas generated by a dielectric barrier discharge (DBD) are of great interest in material surface processing because of their convenience, effectiveness and low cost. In this paper, polypropylene (PP) films are modified using a non-equilibrium plasma generated by a DBD in air in homogeneous mode and in filamentary mode. The filamentary DBD is generated in ambient air, and the homogeneous DBD is generated at medium pressure with an operating pressure value of 3 kPa. The characteristics of homogeneous DBD are studied and compared with those of filamentary DBD by measuring their electrical discharge parameters and observing their light emission phenomena, and the surface properties of the PP films before and after the treatments are studied using contact angle and surface energy measurement, x-ray photoelectron spectroscopy and scanning electron microscopy. It is found that the homogeneous DBD is even and stable in the whole gas gap, which differs from the commonly filamentary DBD. The plasma treatments modify the PP surface in both morphology and composition. The PP films modified in both treatments show a remarkable decrease in the water contact angle and a remarkable increase in surface energy due to the introduction of oxygen-containing groups on the surface and the etching of the surface. The homogeneous DBD is more effective in PP surface modification than the filamentary DBD as it can make the contact angle decrease to a lower level by introducing more oxygen-containing groups. This effect could be explained by the evenly distributed plasma at a homogeneous DBD than at a filamentary DBD, and by the more efficient introduction of atomic oxygen to the PP surface in the case of homogeneous DBD.

  16. 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.

  17. 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.

  18. Antimicrobial nanoparticle-coated electrostatic air filter with high filtration efficiency and low pressure drop.

    PubMed

    Sim, Kyoung Mi; Park, Hyun-Seol; Bae, Gwi-Nam; Jung, Jae Hee

    2015-11-15

    In this study, we demonstrated an antimicrobial nanoparticle-coated electrostatic (ES) air filter. Antimicrobial natural-product Sophora flavescens nanoparticles were produced using an aerosol process, and were continuously deposited onto the surface of air filter media. For the electrostatic activation of the filter medium, a corona discharge electrification system was used before and after antimicrobial treatment of the filter. In the antimicrobial treatment process, the deposition efficiency of S. flavescens nanoparticles on the ES filter was ~12% higher than that on the pristine (Non-ES) filter. In the evaluation of filtration performance using test particles (a nanosized KCl aerosol and submicron-sized Staphylococcus epidermidis bioaerosol), the ES filter showed better filtration efficiency than the Non-ES filter. However, antimicrobial treatment with S. flavescens nanoparticles affected the filtration efficiency of the filter differently depending on the size of the test particles. While the filtration efficiency of the KCl nanoparticles was reduced on the ES filter after the antimicrobial treatment, the filtration efficiency was improved after the recharging process. In summary, we prepared an antimicrobial ES air filter with >99% antimicrobial activity, ~92.5% filtration efficiency (for a 300-nm KCl aerosol), and a ~0.8 mmAq pressure drop (at 13 cm/s). This study provides valuable information for the development of a hybrid air purification system that can serve various functions and be used in an indoor environment. PMID:26172593

  19. Heat transfer and pressure distributions on hemisphere-cylinders in methane-air combustion products at Mach 7

    NASA Technical Reports Server (NTRS)

    Weinstein, I.

    1973-01-01

    Heat-transfer and pressure distributions were measured over the surfaces of three hemisphere-cylinder models tested at a nominal Mach number of 7 in the Langley 8-foot high-temperature structures tunnel which uses methane-air products of combustion as a test medium. The results showed that the heat-transfer and pressure distributions over the surface of the models were in good agreement with experimental data obtained in air and also with theoretical predictions.

  20. 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.

  1. 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).

  2. 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.

  3. Experimental characterization of the effects of pneumatic tubing on unsteady pressure measurements

    NASA Technical Reports Server (NTRS)

    Whitmore, Stephen A.; Lindsey, William T.; Curry, Robert E.; Gilyard, Glenn B.

    1990-01-01

    Advances in aircraft control system designs have, with increasing frequency, required that air data be used as flight control feedback. This condition requires that these data be measured with accuracy and high fidelity. Most air data information is provided by pneumatic pressure measuring sensors. Typically unsteady pressure data provided by pneumatic sensing systems are distorted at high frequencies. The distortion is a result of the pressure being transmitted to the pressure sensor through a length of connective tubing. The pressure is distorted by frictional damping and wave reflection. As a result, air data provided all-flush, pneumatically sensed air data systems may not meet the frequency response requirements necessary for flight control augmentation. Both lab and flight test were performed at NASA-Ames to investigate the effects of this high frequency distortion in remotely located pressure measurement systems. Good qualitative agreement between lab and flight data are demonstrated. Results from these tests are used to describe the effects of pneumatic distortion in terms of a simple parametric model.

  4. Simulation of pressure effects on glasses

    SciTech Connect

    Kogure, Y.; Doyama, M.

    1997-12-31

    Glass transition and effects of pressure and shear stress on atomic configuration are investigated by means of molecular dynamics simulation. An embedded atom method potential is used for the atomic interaction. A model crystal for Cu is melted and quenched to realize the glass state. Atomic configuration in the glass is examined through the radial distribution function. External stress is applied and displacement of atoms is monitored to investigate the mechanism of mechanical relaxation. Larger displacement of atoms is observed under a shear stress.

  5. [Temporal behavior of light emission of dielectric barrier discharges in air at atmospheric pressure].

    PubMed

    Yin, Zeng-qian; Dong, Li-fang; Han, Li; Li, Xue-chen; Chai, Zhi-fang

    2002-12-01

    The experimental setup of dielectric barrier discharge was designed which is propitious to optical measurement. Temporal behavior of light emission of dielectric barrier discharges (filamentary model) in air at atmospheric pressure was measured by using optical method. Temporal behavior of dielectric barrier discharges was obtained. The experimental results show that the discharge burst in each half cycle of applied voltage consists of a series of discharge pulses, the duration of each discharge pulse is about 30-50 ns, and the interval of the neighboring discharge pulses is about a few hundred ns. The result is of great importance to the application of dielectric barrier discharges. PMID:12914154

  6. 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.

  7. 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.

  8. Modification of the surface layers of copper by a diffuse discharge in atmospheric pressure air

    NASA Astrophysics Data System (ADS)

    Shulepov, Mikhail A.; Erofeev, Mikhail V.; Oskomov, Konstantin V.; Tarasenko, Victor F.

    2015-12-01

    The paper presents the results of examination of copper samples exposed to a diffuse discharge initiated by a runaway electron beam in air under normal pressure. The changes in the chemical composition of the surface layers of copper caused by the action of the discharge were investigated. It has been found that the oxygen and carbon concentrations in the surface layers depend on the number of discharge pulses. The study was aimed at finding possible ways of using this type of discharge in research and industry.

  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. Design and fabrication of dielectric diaphragm pressure sensors for applications to shock wave measurement in air

    NASA Astrophysics Data System (ADS)

    Parkes, W.; Djakov, V.; Barton, J. S.; Watson, S.; MacPherson, W. N.; Stevenson, J. T. M.; Dunare, C. C.

    2007-07-01

    Optical fibre pressure sensors have potential performance advantages over electrical sensors in measuring rapid transients such as shock waves from explosive blasts. We report the development of micromachined optical fibre Fabry-Pérot pressure sensors using a silicon dioxide or nitride diaphragm and detail the fabrication stages of the sensor body and diaphragm. The planar technology used is based on silicon deep etching and direct fusion bonding of silicon wafers. Test results for both types of diaphragm are presented. Sensors with rise times better than 3 µs, range 0.1 to 1 MPa and resolution ~500 Pa have been demonstrated in explosives trials. Despite the difference in the sign of stress for the two diaphragm types, both demonstrated excellent high-speed response to explosively generated air shocks.

  11. Pressurized air injection in an axial hydro-turbine model for the mitigation of tip leakage cavitation

    NASA Astrophysics Data System (ADS)

    Rivetti, A.; Angulo, M.; Lucino, C.; Liscia, S.

    2015-12-01

    Tip leakage vortex cavitation in axial hydro-turbines may cause erosion, noise and vibration. Damage due to cavitation can be found at the tip of the runner blades on the low pressure side and the discharge ring. In some cases, the erosion follows an oscillatory pattern that is related to the number of guide vanes. That might suggest that a relationship exists between the flow through the guide vanes and the tip vortex cavitating core that induces this kind of erosion. On the other hand, it is known that air injection has a beneficial effect on reducing the damage by cavitation. In this paper, a methodology to identify the interaction between guide vanes and tip vortex cavitation is presented and the effect of air injection in reducing this particular kind of erosion was studied over a range of operating conditions on a Kaplan scale model. It was found that air injection, at the expense of slightly reducing the efficiency of the turbine, mitigates the erosive potential of tip leakage cavitation, attenuates the interaction between the flow through the guide vanes and the tip vortex and decreases the level of vibration of the structural components.

  12. Isotope effect of mercury diffusion in air

    PubMed Central

    Koster van Groos, Paul G.; Esser, Bradley K.; Williams, Ross W.; Hunt, James R.

    2014-01-01

    Identifying and reducing impacts from mercury sources in the environment remains a considerable challenge and requires process based models to quantify mercury stocks and flows. The stable isotope composition of mercury in environmental samples can help address this challenge by serving as a tracer of specific sources and processes. Mercury isotope variations are small and result only from isotope fractionation during transport, equilibrium, and transformation processes. Because these processes occur in both industrial and environmental settings, knowledge of their associated isotope effects is required to interpret mercury isotope data. To improve the mechanistic modeling of mercury isotope effects during gas phase diffusion, an experimental program tested the applicability of kinetic gas theory. Gas-phase elemental mercury diffusion through small bore needles from finite sources demonstrated mass dependent diffusivities leading to isotope fractionation described by a Rayleigh distillation model. The measured relative atomic diffusivities among mercury isotopes in air are large and in agreement with kinetic gas theory. Mercury diffusion in air offers a reasonable explanation of recent field results reported in the literature. PMID:24364380

  13. Measurement and Simulation of Spontaneous Raman Scattering Spectra in High-Pressure, Fuel-Rich H2-Air Flames

    NASA Technical Reports Server (NTRS)

    Kojima, Jun; Nguyen, Quang-Viet

    2003-01-01

    Rotational vibrational spontaneous Raman spectra (SRS) of H2, N2, and H2O have been measured in H2-air flames at pressures up to 30 atm as a first stem towards establishing a comprehensive Raman spectral database for temperatures and species in high-pressure combustion. A newly developed high-pressure burner facility provides steady, reproducible flames with a high degree of flow precision. We have obtained an initial set of measurements that indicate the spectra are of sufficient quality in terms of spectral resolution, wavelength coverage, and signal-to-noise ratio for use in future reference standards. The fully resolved Stokes and anti-Stokes shifted SRS spectra were collected in the visible wavelength range (400-700 nm) using pulse-stretched 532 nm excitation and a non-intensified CCD spectrograph with a high-speed shutter. Reasonable temperatures were determined via the intensity distribution of rotational H2 lines at stoichiometry and fuel-rich conditions. Theoretical Raman spectra of H2 were computed using a semi-classical harmonic-oscillator model with recent pressure broadening data and were compared with experimental results. The data and simulation indicated that high-J rotational lines of H2 might interfere with the N2 vibrational Q-branch lines, and this could lead to errors in N2-Raman thermometry based on the line-fitting method. From a comparison of N2 Q-branch spectra in lean H2 low-pressure (1.2 atm) and high-pressure (30 atm) flames, we found no significant line-narrowing or -broadening effects at the current spectrometer resolution of 0.04 nm.

  14. 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.

  15. 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.

  16. Effects of confining pressure, pore pressure and temperature on absolute permeability. SUPRI TR-27

    SciTech Connect

    Gobran, B.D.; Ramey, H.J. Jr.; Brigham, W.E.

    1981-10-01

    This study investigates absolute permeability of consolidated sandstone and unconsolidated sand cores to distilled water as a function of the confining pressure on the core, the pore pressure of the flowing fluid and the temperature of the system. Since permeability measurements are usually made in the laboratory under conditions very different from those in the reservoir, it is important to know the effect of various parameters on the measured value of permeability. All studies on the effect of confining pressure on absolute permeability have found that when the confining pressure is increased, the permeability is reduced. The studies on the effect of temperature have shown much less consistency. This work contradicts the past Stanford studies by finding no effect of temperature on the absolute permeability of unconsolidated sand or sandstones to distilled water. The probable causes of the past errors are discussed. It has been found that inaccurate measurement of temperature at ambient conditions and non-equilibrium of temperature in the core can lead to a fictitious permeability reduction with temperature increase. The results of this study on the effect of confining pressure and pore pressure support the theory that as confining pressure is increased or pore pressure decreased, the permeability is reduced. The effects of confining pressure and pore pressure changes on absolute permeability are given explicitly so that measurements made under one set of confining pressure/pore pressure conditions in the laboratory can be extrapolated to conditions more representative of the reservoir.

  17. Chemical Pressure Effects in Layered Manganites

    NASA Astrophysics Data System (ADS)

    Moritomo, Yutaka; Maruyama, Yousuke; Nakamura, Arao

    1998-03-01

    Lattice effects on the magnetic and transport properties have been investigated for layered-type doped mangaites. The insulator-to-metal transition temperature for La_1.2Sr_1.8Mn_2O7 (T_C=130 K) is significantly suppressed with chemical substitution of the trivalent La^3+ ions to smaller Nd^3+ (or Sm^3+) ions(Y. Moritomo et al), Phys. Rev. B56(1997)R7057. Similarly, the charge-ordering temperature for La_0.5Sr_1.5MnO4 (T_CO=230 K) is suppresses with chemical substitution(Y. Moritomo et al), Phys. Rev. B56, in press. Systematic x-ray as well as neutron diffraction measurements have revealed that above chemical pressure enhances the static Jahn-Teller distortion of the MnO6 octahedra in both the system. We will explain the suppressions of TC and T_CO in terms of the increasing d_3z^2-r^2 character in the occupied eg state. Our observation indicates that the chemical pressure effects are qualitatively different between the cubic and layered manganites systems. The authors are grateful to K. Ohoyama and M. Ohashi for their help in neutron diffraction measurements, and to S. Mori for his help in electron diffraction measurements. This work was supported by a Grant-In-Aid for Scientific Research from the Ministry of Education, Science, Sport and Culture and from PRESTO, Japan Scienece and Technology Corporation (JST), Japan.

  18. Field test of two high-pressure, direct-contact downhole steam generators. Volume I. Air/diesel system

    SciTech Connect

    Marshall, B.W.

    1983-05-01

    As a part of the Project DEEP STEAM to develop technology to more efficiently utilize steam for the recovery of heavy oil from deep reservoirs, a field test of a downhole steam generator (DSG) was performed. The DSG burned No. 2 diesel fuel in air and was a direct-contact, high pressure device which mixed the steam with the combustion products and injected the resulting mixture directly into the oil reservoir. The objectives of the test program included demonstration of long-term operation of a DSG, development of operational methods, assessment of the effects of the steam/combustion gases on the reservoir and comparison of this air/diesel DSG with an adjacent oxygen/diesel direct contact generator. Downhole operation of the air/diesel DSG was started in June 1981 and was terminated in late February 1982. During this period two units were placed downhole with the first operating for about 20 days. It was removed, the support systems were slightly modified, and the second one was operated for 106 days. During this latter interval the generator operated for 70% of the time with surface air compressor problems the primary source of the down time. Thermal contact, as evidenced by a temperature increase in the production well casing gases, and an oil production increase were measured in one of the four wells in the air/diesel pattern. Reservoir scrubbing of carbon monoxide was observed, but no conclusive data on scrubbing of SO/sub x/ and NO/sub x/ were obtained. Corrosion of the DSG combustor walls and some other parts of the downhole package were noted. Metallurgical studies have been completed and recommendations made for other materials that are expected to better withstand the downhole combustion environment. 39 figures, 8 tables.

  19. Effect of alveolar pressure on pulmonary artery pressure in chronically hypoxic rats.

    PubMed

    Wach, R; Emery, C J; Bee, D; Barer, G R

    1987-02-01

    The effect on pulmonary artery pressure of a rise in alveolar pressure differed in chronically hypoxic rats (10% O2 for 3-5 weeks) compared with control rats. Chronically hypoxic rats have newly muscularised walls in arterioles in the alveolar region. Isolated lungs of chronically hypoxic and control rats were perfused with blood under conditions in which alveolar pressure was greater than left atrial pressure during both normoxia and hypoxia. Alveolar pressure was the effective downstream pressure. Pressure-flow lines were measured at low and high alveolar pressure (5 and 15 mmHg). During normoxia pressure-flow lines of chronically hypoxic rats had a steeper slope (higher resistance) and greater extrapolated intercept on the pressure axis (effective downstream pressure) than control rats. In both groups of rats the change from low to high alveolar pressure during normoxia caused an approximately parallel shift in the pressure-flow line similar to the change in alveolar pressure. During hypoxia, which led to an increase in slope and intercept in both groups of rats, the effect of a rise in alveolar pressure differed in chronically hypoxic from control rats. In control rats there was a small parallel shift in the pressure-flow line that was much less than the increase in alveolar pressure; in chronically hypoxic rats there was a large parallel shift in the pressure-flow line that was greater than the increase in alveolar pressure. Thus in chronically hypoxic rats hypoxic vasoconstriction probably occurred mainly in muscular alveolar vessels, whereas in control rats it probably occurred upstream in extra-alveolar vessels. At constant blood flow the relation between pulmonary artery pressure and alveolar pressure was measured while alveolar pressure was reduced from approximately 15 mmHg to zero during both normoxia and hypoxia. In control and chronically hypoxic rats the slope of this line was less than 1. At an alveolar pressure of 2-3 mmHg there was an inflection

  20. Coke-oven back pressure and its effect on door leaks

    SciTech Connect

    Sundholm, J.L. )

    1993-07-01

    In anticipation of more stringent door leaks standards mandated by the 1990 Clean Air Act Amendments, LTV has conducted three studies at the Pittsburgh coke plant: door evaluations; back pressure system study and reduced back pressure operation. This paper will discuss the investigations and results of the pressure related studies. Raw coke-oven gas from the five batteries in operation is evacuated via three suction mains to a common set of primary coolers and exhausters. At any pint in time it is possible to have up to three ovens being charged which significantly increases the load on the suction system. The back pressure system study was conducted to determine the effect of charging practice on the collecting main pressure, system suction pressure and exhausted response, and the effect on collecting main pressure on a battery when charging other batteries for the purpose of defining operational and facility changes necessary to reduce collecting main pressure variation. Observations at normal collecting main pressure and at reduced pressure indicate that door leaks can be appreciably lowered at the reduced pressure. However, conventional operation at the lower back pressure will invariably cause a suction condition within the oven resulting in undesirable air infiltration. To avoid this suction condition, a partial dampening procedure has been tested successfully on several ovens operating at reduced back pressure. Based upon this result, a decision has been made to implement the technique on all ovens on one battery. During this test, the effect of the modified operations on wall condition, end temperature, stack appearance, and topside leaks, as well as door leaks will be assessed.

  1. Shuttle Entry Air Data System concepts applied to Space Shuttle Orbiter flight pressure data to determine air data - STS 1-4

    NASA Technical Reports Server (NTRS)

    Siemers, P. M., III; Wolf, H.; Flanagan, P. F.

    1983-01-01

    The Shuttle Entry Air Data System (SEADS) is the implementation of a new concept in air data systems, with application to entry vehicles. This concept incorporates an array of flush orifices in the nose and forward fuselage of the vehicle and a new flowfield modeling concept for the analysis of flight data and the determination of the required air data parameters. Although the SEADS has not been fully demonstrated, a developmental analysis capability has been assembled and demonstrated. This analytical capability has been used to analyze selected Development Flight Instrumentation (DFI) pressure data from STS-1 through STS-4 and determine angle of attack and freestream dynamic pressure. The results of this study verify the potential of the SEADS as a highly fault tolerant operational air data system. In addition, the transition of SEADS from its present status as an experimental system to an operational system is shown to be readily achievable.

  2. Formation of reactive oxygen and nitrogen species by repetitive negatively pulsed helium atmospheric pressure plasma jets propagating into humid air

    NASA Astrophysics Data System (ADS)

    Norberg, Seth A.; Johnsen, Eric; Kushner, Mark J.

    2015-06-01

    Atmospheric pressure plasma jets have many beneficial effects in their use in surface treatment and, in particular, plasma medicine. One of these benefits is the controlled production of reactive oxygen and nitrogen species (RONS) in the active discharge through the molecular gases added to the primary noble gas in the input mixture, and through the interaction of reactive species in the plasma effluent with the ambient air. In this computational investigation, a parametric study was performed on the production of RONS in a multiply pulsed atmospheric pressure plasma jet sustained in a He/O2 mixture and flowing into ambient humid air. The consequences of flow rate, O2 fraction, voltage, and repetition rate on reactant densities after a single discharge pulse, after 30 pulses, and after the same total elapsed time were investigated. At the end of the first discharge pulse, voltage has the greatest influence on RONS production. However, the systematic trends for production of RONS depend on repetition rate and flow rate in large part due to the residence time of RONS in the plasma zone. Short residence times result in reactive species produced by the previous pulse still being in the discharge tube or in the path of the ionization wave at the next pulse. The RONS therefore accumulate in the tube and in the near effluent on a pulse-to-pulse basis. This accumulation enables species requiring multiple reactions among the primary RONS species to be produced in greater numbers.

  3. Effects of Lingual Effort on Swallow Pressures Following Radiation Treatment

    ERIC Educational Resources Information Center

    Lenius, Kerry; Stierwalt, Julie; LaPointe, Leonard L.; Bourgeois, Michelle; Carnaby, Giselle; Crary, Michael

    2015-01-01

    Purpose: This article investigated the effects of increased oral lingual pressure on pharyngeal pressures during swallowing in patients who have undergone radiotherapy for head and neck cancer. It was hypothesized that increased oral lingual pressure would result in increased pharyngeal pressures. Method: A within-subject experimental design was…

  4. Nanoparticle formation by laser ablation in air and by spark discharges at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Itina, T. E.; Voloshko, A.

    2013-12-01

    Recent promising methods of nanoparticle fabrication include laser ablation and spark discharge. Despite different experimental conditions, a striking similarity is often observed in the sizes of the obtained particles. To explain this result, we elucidate physical mechanisms involved in the formation of metallic nanoparticles. In particular, we compare supersaturation degree and sizes of critical nucleus obtained under laser ablation conditions with that obtained for spark discharge in air. For this, the dynamics of the expansion of either ablated or eroded products is described by using a three-dimensional blast wave model. Firstly, we consider nanosecond laser ablation in air. In the presence of a background gas, the plume expansion is limited by the gas pressure. Nanoparticles are mostly formed by nucleation and condensation taking place in the supersaturated vapor. Secondly, we investigate nanoparticles formation by spark discharge at atmospheric pressure. After efficient photoionization and streamer expansion, the cathode material suffers erosion and NPs appear. The calculation results allow us to examine the sizes of critical nuclei as function of the experimental parameters and to reveal the conditions favorable for the size reduction and for the increase in the nanoparticle yield.

  5. 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.

  6. 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.

  7. Features of the electron density dynamics in the filamentation of femtosecond laser radiation in air at elevated pressure

    NASA Astrophysics Data System (ADS)

    Chizhov, P. A.; Bukin, V. V.; Ushakov, A. A.; Garnov, S. V.

    2016-04-01

    The electron density in the plasma channel of a femtosecond filament in air at pressures from 1 to 7 atm is measured at different instants, starting from the ionisation onset and up to several hundreds of picoseconds after it. The initial electron density is found to increase sharply in the pressure range of 3 – 4 atm. The plasma channel diameter is found to decrease with an increase in pressure from 3 to 7 atm.

  8. Particle-in-cell simulations of multi-MeV pulsed X-ray induced air plasmas at low pressures

    NASA Astrophysics Data System (ADS)

    Ribière, M.; Cessenat, O.; d'Almeida, T.; de Gaufridy de Dortan, F.; Maulois, M.; Delbos, C.; Garrigues, A.; Azaïs, B.

    2016-03-01

    A full kinetic modelling of the charge particles dynamics generated upon the irradiation of an air-filled cavity by a multi-MeV pulsed x-ray is performed. From the calculated radiative source generated by the ASTERIX generator, we calculated the electromagnetic fields generated by x-ray induced air plasmas in a metallic cavity at different pressures. Simulations are carried out based on a Particle-In-Cell interpolation method which uses 3D Maxwell-Vlasov calculations of the constitutive charged species densities of air plasmas at different pressures at equilibrium. The resulting electromagnetic fields within the cavity are calculated for different electron densities up to 4 × 1010 cm-3. For each air pressure, we show electronic plasma waves formation followed by Landau damping. As electron density increases, the calculations exhibit space-charged neutralization and return current formation.

  9. Compact High-Velocity Atmospheric Pressure Dielectric Barrier Plasma Jet in Ambient Air

    NASA Astrophysics Data System (ADS)

    Annette, Meiners; Michael, Leck; Bernd, Abel

    2015-01-01

    In this paper, a non-thermal atmospheric pressure plasma jet at high streaming velocity operating with ambient air is highlighted. In the present technological approach, the employment of air poses a significant challenge. The high oxygen concentration in air results in a reduced concentration of reactive species in combination with a short species lifetime. The plasma jet assembly presented here contains a special dielectric barrier with a high secondary emission coefficient. In this way, the electron density and in turn the density of reactive species is increased. In addition, the plasma jet assembly is equipped with a short electrode. This leads to a higher voltage across the discharge gap and in turn to an increased density of reactive plasma species. The plasma jet is formed within and emitted by a small conical nozzle. A high-speed gas flow with gas velocity of 340 m/s was achieved at the end of the nozzle. In the jet the concentration of toxic and unwanted neutral plasma species like O3 or NOx is significantly reduced because of the shorter residence time within the plasma. The range of short-lived active plasma species is in turn considerably enhanced. The jet efficiency and action range measured through the oxidation of a test surface were determined by measuring the increase of surface tension of a polypropylene substrate via contact angle measurements after plasma treatment. Numerical modeling of the plasma plume indicates that oxygen atoms are in fact the main active species in the plasma plume.

  10. Focused excimer laser initiated and radio frequency sustained plasma formation in high pressure air

    NASA Astrophysics Data System (ADS)

    Giar, Ryan

    A doctoral thesis project was performed to experimentally investigate the feasibility of focused excimer laser initiation of air plasmas for radio frequency sustainment. A 193 nm, 15 MW, 300 mJ laser was focused with a 18 cm focal length lens to form a small, high density (ne ~ 10 14 cm--3) seed plasma. These laser plasmas were produced inside a borosilicate glass tube around which was wrapped a 5 turn helical antenna. This antenna was powered with 5 kW of 13.56 MHz of radiation for 1.5 s. This was accomplished at a pressure of 22 Torr, resulting in a large volume (300 cm3) air plasma. Diagnostic measurements of this air plasma determined an electron density of 5E10 cm-3 and an electron temperature 1.3 eV with a neutral temperature of 3500 K. The collision frequency was measured to be 9E10 Hz which resulted in a plasma-loaded antenna resistance of 6 O with a voltage reflection coefficient of 0.7.

  11. 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.

  12. Effect of elevated temperature and pressure on sprays from simplex swirl atomizers

    NASA Technical Reports Server (NTRS)

    Dodge, L. G.; Biaglow, J. A.

    1986-01-01

    An examination is made of the effects of air temperature and pressure on the spray quality of a moderately high capacity pressure swirl atomizer spraying jet-A and No. 2 diesel fuel. Drop size distributions, in terms of both Sauter mean diameter (SMD) and the width of the distribution given by the Rosin-Rammler N parameter, are determined over a variety of air conditions. Close to the nozzle, limited data suggest that the SMDs were a strong function of air density, but independent of air temperature. Trends of SMD and N are shown as a function of distance from the nozzle at all conditions, indicating some of the evaporation characteristics of fuel sprays.

  13. Treatment of poly(ethylene terephthalate) foils by atmospheric pressure air dielectric barrier discharge and its influence on cell growth

    NASA Astrophysics Data System (ADS)

    Kuzminova, Anna; Vandrovcová, Marta; Shelemin, Artem; Kylián, Ondřej; Choukourov, Andrei; Hanuš, Jan; Bačáková, Lucie; Slavínská, Danka; Biederman, Hynek

    2015-12-01

    In this contribution an effect of dielectric barrier discharge (DBD) sustained in air at atmospheric pressure on surface properties of poly(ethylene terephthalate) (PET) foils is studied. It is found that exposure of PET to DBD plasma leads to rapid changes of surface chemical composition, wettability, surface morphology as well as mechanical properties of PET surface. In addition, based on biological tests that were performed using two cell types (Saos-2 human osteoblast-like cells and HUVEC human umbilical vein endothelial cells), it may be concluded that DBD plasma treatment positively influences cell growth on PET. This effect was found to be connected predominantly with increased surface energy and oxygen content of the surface of treated PET foils.

  14. 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

  15. 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

  16. Effect of pressure on electrospray characteristics

    PubMed Central

    Marginean, Ioan; Page, Jason S.; Kelly, Ryan T.; Tang, Keqi; Smith, Richard D.

    2009-01-01

    An experimental study of pulsating electrosprays operated at subambient pressure is reported. The pressure domain that affords stable electrospray operation appears to be limited by the vapor pressure of the liquid. The voltage driving the electrospray is shown to have a logarithmic dependence on pressure. The observed scaling amends the relationship currently used to calculate the electric field at the tip of the meniscus of an electrified liquid. PMID:19997584

  17. Effect of pressure on electrospray characteristics

    SciTech Connect

    Marginean, Ioan; Page, Jason S.; Kelly, Ryan T.; Tang, Keqi; Smith, Richard D.

    2009-11-02

    An experimental study of sub-ambient pressure electrosprays is reported. The pressure domain that affords stable electrospray operation appears to be limited by the vapor pressure of the liquid. The voltage driving the electrospray is shown to have a logarithmic dependence on the pressure. This scaling amends the relationship currently in use to calculate the electric field at the tip of the meniscus of an electrified liquid

  18. Effects of a continuous lateral turning device on pressure relief.

    PubMed

    Do, Nam Ho; Kim, Deog Young; Kim, Jung-Hoon; Choi, Jong Hyun; Joo, So Young; Kang, Na Kyung; Baek, Yoon Su

    2016-01-01

    [Purpose] The purpose of this study was to examine the pressure-relieving effects of a continuous lateral turning device on common pressure ulcer sites. [Subjects] Twenty-four healthy adults participated. [Methods] The design of our continuous lateral turning device was motivated by the need for an adequate pressure-relieving device for immobile and/or elderly people. The procedure of manual repositioning is embodied in our continuous lateral turning device. The interface pressure and time were measured, and comfort grade was evaluated during sessions of continuous lateral turning at 0°, 15°, 30°, and 45°. We quantified the pressure-relieving effect using peak pressure, mean pressure, and pressure time integration. [Results] Participants demonstrated pressure time integration values below the pressure-time threshold at 15°, 30°, and 45° at all the common pressure ulcer sites. Moreover, the most effective angles for pressure relief at the common pressure ulcer sites were 30° at the occiput, 15° at the left scapula, 45° at the right scapula, 45° at the sacrum, 15° at the right heel, and 30° at the left heel. However, angles greater than 30° induced discomfort. [Conclusion] Continuous lateral turning with our specially designed device effectively relieved the pressure of targeted sites. Moreover, the suggested angles of continuous lateral turning can be used to relieve pressure at targeted sites. PMID:27065531

  19. Effects of a continuous lateral turning device on pressure relief

    PubMed Central

    Do, Nam Ho; Kim, Deog Young; Kim, Jung-Hoon; Choi, Jong Hyun; Joo, So Young; Kang, Na Kyung; Baek, Yoon Su

    2016-01-01

    [Purpose] The purpose of this study was to examine the pressure-relieving effects of a continuous lateral turning device on common pressure ulcer sites. [Subjects] Twenty-four healthy adults participated. [Methods] The design of our continuous lateral turning device was motivated by the need for an adequate pressure-relieving device for immobile and/or elderly people. The procedure of manual repositioning is embodied in our continuous lateral turning device. The interface pressure and time were measured, and comfort grade was evaluated during sessions of continuous lateral turning at 0°, 15°, 30°, and 45°. We quantified the pressure-relieving effect using peak pressure, mean pressure, and pressure time integration. [Results] Participants demonstrated pressure time integration values below the pressure-time threshold at 15°, 30°, and 45° at all the common pressure ulcer sites. Moreover, the most effective angles for pressure relief at the common pressure ulcer sites were 30° at the occiput, 15° at the left scapula, 45° at the right scapula, 45° at the sacrum, 15° at the right heel, and 30° at the left heel. However, angles greater than 30° induced discomfort. [Conclusion] Continuous lateral turning with our specially designed device effectively relieved the pressure of targeted sites. Moreover, the suggested angles of continuous lateral turning can be used to relieve pressure at targeted sites. PMID:27065531

  20. Comparison of predicted and experimental real-gas pressure distributions on space shuttle orbiter nose for shuttle entry air data system

    NASA Technical Reports Server (NTRS)

    Shinn, J. L.

    1980-01-01

    An experimental investigation of inviscid real-gas effects on the pressure distribution along the Space Shuttle Orbiter nose center line up to an angle of attack of 32 deg was performed in support of the Shuttle Entry Air Data System (SEADS). Free-stream velocities from 4.8 to 6.6 kn/s were generated at hypersonic conditions with helium, air, and CO2, resulting in normal-shock density ratios from 3.7 to 18.4. The experimental results for pressure distribution agreed closely with numerical results. Modified Newtonian theory deviates from both experiment and the numerical results as angle of attack increases or shock density ratio decreases. An evaluation of the use of modified Newtonian theory for predicting SEADS pressure distributions in actual flight conditions was made through comparison with numerical predictions.

  1. Combustor exhaust-emissions and blowout-limits with diesel number 2 and jet A fuels utilizing air-atomizing and pressure atomizing nozzles

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

    Experimental tests with diesel number 2 and Jet A fuels were conducted in a combustor segment to obtain comparative data on exhaust emissions and blowout limits. An air-atomizing nozzle was used to inject the fuels. Tests were also made with diesel number 2 fuel using a pressure-atomizing nozzle to determine the effectiveness of the air-atomizing nozzle in reducing exhaust emissions. Test conditions included fuel-air ratios of 0.008 to 0.018, inlet-air total pressures and temperatures of 41 to 203 newtons per square centimeter and 477 to 811 K, respectively, and a reference velocity of 21.3 meters per second. Smoke number and unburned hydrocarbons were twice as high with diesel number 2 as with Jet A fuel. This was attributed to diesel number 2 having a higher concentration of aromatics and lower volatility than Jet A fuel. Oxides of nitrogen, carbon monoxide, and blowout limits were approximately the same for the two fuels. The air-atomizing nozzle, as compared with the pressure-atomizing nozzle, reduced oxides-of-nitrogen by 20 percent, smoke number by 30 percent, carbon monoxide by 70 percent, and unburned hydrocarbons by 50 percent when used with diesel number 2 fuel.

  2. Blood Pressure Changes and Chemical Constituents of Particulate Air Pollution: Results from the Healthy Volunteer Natural Relocation (HVNR) Study

    PubMed Central

    Wu, Shaowei; Deng, Furong; Huang, Jing; Wang, Hongyi; Shima, Masayuki; Wang, Xin; Qin, Yu; Zheng, Chanjuan; Wei, Hongying; Hao, Yu; Lv, Haibo; Lu, Xiuling

    2012-01-01

    Background: Elevated blood pressure (BP) has been associated with particulate matter (PM) air pollution, but associations with PM chemical constituents are still uncertain. Objectives: We investigated associations of BP with various chemical constituents of fine PM (PM2.5) during 460 repeated visits among a panel of 39 university students. Methods: Resting BP was measured using standardized methods before and after the university students relocated from a suburban campus to an urban campus with different air pollution contents in Beijing, China. Air pollution data were obtained from central monitors close to student residences. We used mixed-effects models to estimate associations of various PM2.5 constituents with systolic BP (SBP), diastolic BP (DBP), and pulse pressure. Results: An interquartile range increase of 51.2 μg/m3 in PM2.5 was associated with a 1.08-mmHg (95% CI: 0.17, 1.99) increase in SBP and a 0.96-mmHg (95% CI: 0.31, 1.61) increase in DBP on the following day. A subset of PM2.5 constituents, including carbonaceous fractions (organic carbon and elemental carbon), ions (chloride and fluoride), and metals/metalloid elements (nickel, zinc, magnesium, lead, and arsenic), were found to have robust positive associations with different BP variables, though robust negative associations of manganese, chromium, and molybdenum with SBP or DBP also were observed. Conclusions: Our results support relationships between specific PM2.5 constituents and BP. These findings have potential implications for the development of pollution abatement strategies that maximize public health benefits. PMID:23086577

  3. 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}% ).

  4. Effects of hydrostatic pressure, agitation and CO2 stress on Phytophthora nicotianae zoospore survival

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phytophthora nicotianae Breda de Haan was used as a model pathogen to investigate the effects of hydrostatic pressure, agitation, and aeration with CO2 or breathable air on the survival of Phytophthora zoospores in water. Injecting CO2 into 2 liters of zoospore-infested water for 5 min at 110.4 ml ...

  5. Effect of body repositioning after venous air embolism. An echocardiographic study

    NASA Technical Reports Server (NTRS)

    Geissler, H. J.; Allen, S. J.; Mehlhorn, U.; Davis, K. L.; Morris, W. P.; Butler, B. D.

    1997-01-01

    BACKGROUND: Current therapy for massive venous air embolism (VAE) may include the use of the left lateral recumbent (LLR) position, although its effectiveness has been questioned. This study used transesophageal echocardiography to evaluate the effect of body repositioning on intracardiac air and acute cardiac dimension changes. METHODS: Eighteen anesthetized dogs in the supine position received a venous air injection of 2.5 ml/kg at a rate of 5 ml/ s. After 1 min the dogs were repositioned into either the LLR, LLR 10 degrees head down (LLR-10 degrees), right lateral recumbence, or remained in the supine position. RESULTS: Repositioning after VAE resulted in relocation of intracardiac air to nondependent areas of the right heart. Peak right ventricular (RV) diameter increase and mean arterial pressure decrease were greater in the repositioned animals compared with those in the supine position (P < 0.05). Right ventricular diameter and mean arterial pressure showed an inverse correlation (r = 0.81). Peak left atrial diameter decrease was greater in the LLR and LLR-10 degrees positions compared with the supine position (P < 0.05). Repositioning did not influence peak pulmonary artery pressure increase, and no correlation was found between RV diameter and pulmonary artery pressure. All animals showed electrocardiogram and echocardiographic changes reconcilable with myocardial ischemia. CONCLUSIONS: In dogs, body repositioning after VAE provided no benefit in hemodynamic performance or cardiac dimension changes, although relocation of intracardiac air was demonstrated. Right ventricular air did not appear to result in significant RV outflow obstruction, as pulmonary artery pressure increased uniformly in all groups and was not influenced by the relocation of intracardiac air. The combination of increased RV afterload and arterial hypotension, possibly with subsequent RV ischemia rather than RV outflow obstruction by an airlock appeared to be the primary mechanism for

  6. 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.

  7. Interactive response of photosynthetic characteristics in Haloxylon ammodendron and Hedysarum scoparium exposed to soil water and air vapor pressure deficits.

    PubMed

    Gong, Chunmei; Wang, Jiajia; Hu, Congxia; Wang, Junhui; Ning, Pengbo; Bai, Juan

    2015-08-01

    C4 plants possess better drought tolerance than C3 plants. However, Hedysarum scoparium, a C3 species, is dominant and widely distributed in the desert areas of northwestern China due to its strong drought tolerance. This study compared it with Haloxylon ammodendron, a C4 species, regarding the interactive effects of drought stress and different leaf-air vapor pressure deficits. Variables of interest included gas exchange, the activity levels of key C4 photosynthetic enzymes, and cellular anatomy. In both species, gas exchange parameters were more sensitive to high vapor pressure deficit than to strong water stress, and the net CO2 assimilation rate (An) was enhanced as vapor pressure deficits increased. A close relationship between An and stomatal conductance (gs) suggested that the species shared a similar response mechanism. In H. ammodendron, the activity levels of key C4 enzymes were higher, including those of phosphoenolpyruvate carboxylase (PEPC) and nicotinamide adenine dinucleotide phosphate-malate enzyme (NADP-ME), whereas in H. scoparium, the activity level of nicotinamide adenine dinucleotide-malate enzyme (NAD-ME) was higher. Meanwhile, H. scoparium utilized adaptive structural features, including a larger relative vessel area and a shorter distance from vein to stomata, which facilitated the movement of water. These findings implied that some C4 biochemical pathways were present in H. scoparium to respond to environmental challenges. PMID:26257361

  8. Direct measurement of the effective pressure law: Deformation of joints subject to pore and confining pressures

    SciTech Connect

    Boitnott, G.N.; Scholz, C.H. )

    1990-11-10

    When describing the deformation of poro-elastic materials subject to pore pressure (P{sub p}) and confining pressure (P{sub c}), the concept of effective pressure is commonly used. In such a description the deformation is described in terms of a single stress parameter, the effective stress (P{sub e}). Experimental studies which attempt to describe the effective pressure law are troubled by the fact that deformation of geologic materials invariably exhibits loading path dependence (hysteresis). Here the authors develop an experimental technique for measuring the effective pressure law which is useful for many properties of interest, including those that are highly nonlinear and exhibit common types of hysteresis. They experimentally derive an effective pressure law which describes the values of pore and confining pressure consistent with a given joint closure for a law which describes the values of pore and confining pressure consistent with a given joint closure for a loading path of constant closure. The study can be viewed as an attempt to include both pore and confining pressure in a single constitutive law for joint closure. The constant closure loading path is such that the measurement is not affected by hysteresis caused by joint closure. The results provide insight into the microgeometrical and micromechanical properties of joints. The data are not consistent with a simple extension of commonly used linear elastic constitutive models for joint deformation which have compared favorably with experiments in the absence of pore pressure. For smooth lapped glass joints, the effective pressure relation is found to be dependent on the local joint stiffness, with the relationship between the effective pressure law and the local joint stiffness being insensitive to the measured surface topography. Similar measurements on lapped and fractured rock provide some constraints on the effective pressure behavior of jointed rock.

  9. Effect of Fuel Injection and Mixing Characteristics on Pulse-Combustor Performance at High-Pressure

    NASA Technical Reports Server (NTRS)

    Yungster, Shaye; Paxson, Daniel E.; Perkins, Hugh D.

    2014-01-01

    Recent calculations of pulse-combustors operating at high-pressure conditions produced pressure gains significantly lower than those observed experimentally and computationally at atmospheric conditions. The factors limiting the pressure-gain at high-pressure conditions are identified, and the effects of fuel injection and air mixing characteristics on performance are investigated. New pulse-combustor configurations were developed, and the results show that by suitable changes to the combustor geometry, fuel injection scheme and valve dynamics the performance of the pulse-combustor operating at high-pressure conditions can be increased to levels comparable to those observed at atmospheric conditions. In addition, the new configurations can significantly reduce the levels of NOx emissions. One particular configuration resulted in extremely low levels of NO, producing an emission index much less than one, although at a lower pressure-gain. Calculations at representative cruise conditions demonstrated that pulse-combustors can achieve a high level of performance at such conditions.

  10. What is an effective portable air cleaning device? A review.

    PubMed

    Shaughnessy, R J; Sextro, R G

    2006-04-01

    The use of portable air cleaning devices in residential settings has been steadily growing over the last 10 years. Three out of every 10 households now contain a portable air cleaning device. This increased use of air cleaners is accompanied by, if not influenced by, a fundamental belief by consumers that the air cleaners are providing an improved indoor air environment. However, there is a wide variation in the performance of air cleaners that is dependent on the specific air cleaner design and various indoor factors. The most widely used method in the United States to assess the performance of new air cleaners is the procedure described in the American National Standards Institute (ANSI)/Association of Home Appliance Manufacturers (AHAM) AC-1-2002. This method describes both the test conditions and the testing protocol. The protocol yields a performance metric that is based on the measured decay rate of contaminant concentrations with the air cleaner operating compared with the measured decay rate with the air cleaner turned off. The resulting metric, the clean air delivery rate (CADR), permits both an intercomparison of performance among various air cleaners and a comparison of air cleaner operation to other contaminant removal processes. In this article, we comment on the testing process, discuss its applicability to various contaminants, and evaluate the resulting performance metrics for effective air cleaning. PMID:16531290

  11. A new air quality perception scale for global assessment of air pollution health effects.

    PubMed

    Deguen, Séverine; Ségala, Claire; Pédrono, Gaëlle; Mesbah, Mounir

    2012-12-01

    Despite improvements in air quality in developed countries, air pollution remains a major public health issue. To fully assess the health impact, we must consider that air pollution exposure has both physical and psychological effects; this latter dimension, less documented, is more difficult to measure and subjective indicators constitute an appropriate alternative. In this context, this work presents the methodological development of a new scale to measure the perception of air quality, useful as an exposure or risk appraisal metric in public health contexts. On the basis of the responses from 2,522 subjects in eight French cities, psychometric methods are used to construct the scale from 22 items that assess risk perception (anxiety about health and quality of life) and the extent to which air pollution is a nuisance (sensorial perception and symptoms). The scale is robust, reproducible, and discriminates between subpopulations more susceptible to poor air pollution perception. The individual risk factors of poor air pollution perception are coherent with those findings in the risk perception literature. Perception of air pollution by the general public is a key issue in the development of comprehensive risk assessment studies as well as in air pollution risk management and policy. This study offers a useful new tool to measure such efforts and to help set priorities for air quality improvements in combination with air quality measurements. PMID:22852801

  12. 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.

  13. Air plasma effect on dental disinfection

    NASA Astrophysics Data System (ADS)

    Duarte, S.; Kuo, S. P.; Murata, R. M.; Chen, C. Y.; Saxena, D.; Huang, K. J.; Popovic, S.

    2011-07-01

    A nonthermal low temperature air plasma jet is characterized and applied to study the plasma effects on oral pathogens and biofilms. Experiments were performed on samples of six defined microorganisms' cultures, including those of gram-positive bacteria and fungi, and on a cultivating biofilm sample of Streptococcus mutans UA159. The results show that the plasma jet creates a zone of microbial growth inhibition in each treated sample; the zone increases with the plasma treatment time and expands beyond the entire region directly exposed to the plasma jet. With 30s plasma treatment twice daily during 5 days of biofilm cultivation, its formation was inhibited. The viability of S. mutans cells in the treated biofilms dropped to below the measurable level and the killed bacterial cells concentrated to local regions as manifested by the fluorescence microscopy via the environmental scanning electron microscope. The emission spectroscopy of the jet indicates that its plasma effluent carries an abundance of reactive atomic oxygen, providing catalyst for the observed plasma effect.

  14. Air plasma effect on dental disinfection

    SciTech Connect

    Duarte, S.; Murata, R. M.; Saxena, D.; Kuo, S. P.; Chen, C. Y.; Huang, K. J.; Popovic, S.

    2011-07-15

    A nonthermal low temperature air plasma jet is characterized and applied to study the plasma effects on oral pathogens and biofilms. Experiments were performed on samples of six defined microorganisms' cultures, including those of gram-positive bacteria and fungi, and on a cultivating biofilm sample of Streptococcus mutans UA159. The results show that the plasma jet creates a zone of microbial growth inhibition in each treated sample; the zone increases with the plasma treatment time and expands beyond the entire region directly exposed to the plasma jet. With 30s plasma treatment twice daily during 5 days of biofilm cultivation, its formation was inhibited. The viability of S. mutans cells in the treated biofilms dropped to below the measurable level and the killed bacterial cells concentrated to local regions as manifested by the fluorescence microscopy via the environmental scanning electron microscope. The emission spectroscopy of the jet indicates that its plasma effluent carries an abundance of reactive atomic oxygen, providing catalyst for the observed plasma effect.

  15. 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.

  16. Air damping effect on the air-based CMUT operation

    NASA Astrophysics Data System (ADS)

    Cha, Bu-Sang; Kanashima, Takeshi; Lee, Seung-Mok; Okuyama, Masanori

    2015-08-01

    The vibration amplitude, damping ratio and viscous damping force in capacitive micromachinedultrasonic transducers (CMUTs) with a perforated membrane have been calculated theoretically and compared with the experimental data on its vibration behavior. The electrical bias of the DC and the AC voltages and the operation frequency conditions influence the damping effect because leads to variations in the gap height and the vibration velocity of the membrane. We propose a new estimation method to determine the damping ratio by the decay rate of the vibration amplitudes of the perforated membrane plate are measured using a laser vibrometer at each frequency, and the damping ratios were calculated from those results. The influences of the vibration frequency and the electrostatic force on the damping effect under the various operation conditions have been studied.

  17. 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. PMID:18529171

  18. Effect of air, heliox, and oxygen breathing on air bubbles in aqueous tissues in the rat.

    PubMed

    Hyldegaard, O; Madsen, J

    1994-12-01

    Our purpose was to examine the behavior of air bubbles in three non-lipid tissues (skeletal muscle, tendon, and the anterior chamber of the eye) during breathing of air, helium-oxygen (heliox, 80:20), or oxygen. Air bubbles were injected into skeletal muscle or tendon in rats after decompression from a 1-h air exposure at 3.5 atm abs (355 kPa) or into the anterior chamber of the rat eye without any previous pressure exposure. The bubbles were studied by photomicroscopy at 1 atm abs (101 kPa) during either air breathing or during air breathing followed by heliox or O2 breathing. Muscle: during air breathing, all bubbles initially increased in size for a period of 55-100 min after decompression and then started to shrink. Both heliox and O2 breathing increased the shrinking rate as compared to air. Bubble size decreased more rapidly during O2 than heliox breathing. Tendon: during air breathing, bubble size decreased at a constant rate; in one bubble the decrease was preceded by a small increase. During heliox breathing most bubbles decreased faster than during breathing of air. O2 breathing caused a short-term increase in bubble size in 4 out of 10 bubbles. Otherwise, the shrinkage rate was increased in six bubbles and uninfluenced in four bubbles during breathing of O2. Rat eye: during air breathing all bubbles shrank in the observation period. When heliox breathing was started, all bubbles transiently grew for 10-35 min, after which they began shrinking faster than during air breathing. When O2 breathing was started, five out of seven bubbles initially grew or stopped shrinking for 5-15 min, after which they decreased in size faster than during both air and heliox breathing. We conclude that breathing of either heliox or O2 will cause air bubbles in aqueous tissues to disappear faster than during breathing of air. Since heliox breathing promoted bubble shrinking in both muscle and tendon, gas exchange was probably not primarily limited by extravascular diffusion in

  19. 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.

  20. Solvent Selection for Pressurized Liquid Extraction of Polymeric Sorbents Used in Air Sampling

    PubMed Central

    Primbs, Toby; Genualdi, Susan; Simonich, Staci

    2014-01-01

    Pressurized liquid extraction (PLE) was evaluated as a method for extracting semivolatile organic compounds (SOCs) from air sampling media; including quartz fiber filter (QFF), polyurethane foam (PUF), and a polystyrene divinyl benzene copolymer (XAD-2). Hansen solubility parameter plots were used to aid in the PLE solvent selection in order to reduce both co-extraction of polyurethane and save time in evaluating solvent compatibility during the initial steps of method development. A PLE solvent composition of 75:25% hexane:acetone was chosen for PUF. The XAD-2 copolymer was not solubilized under the PLE conditions used. The average percent PLE recoveries (and percent relative standard deviations) of 63 SOCs, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organochlorine, amide, triazine, thiocarbamate, and phosphorothioate pesticides, were 76.7 (6.2), 79.3 (8.1), and 93.4 (2.9) % for the QFF, PUF, and XAD-2, respectively. PMID:18220448

  1. 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.

  2. Laser-induced cooling of a Yb:YAG crystal in air at atmospheric pressure.

    PubMed

    Soares de Lima Filho, Elton; Nemova, Galina; Loranger, Sébastien; Kashyap, Raman

    2013-10-21

    We report for the first time the experimental demonstration of optical cooling of a bulk crystal at atmospheric pressure. The use of a fiber Bragg grating (FBG) sensor to measure laser-induced cooling in real time is also demonstrated for the first time. A temperature drop of 8.8 K from the chamber temperature was observed in a Yb:YAG crystal in air when pumped with 4.2 W at 1029 nm. A background absorption of 2.9 × 10⁻⁴ cm⁻¹ was estimated with a pump wavelength at 1550 nm. Simulations predict further cooling if the pump power is optimized for the sample's dimensions. PMID:24150315

  3. Generation of Atmospheric Pressure Plasma by Repetitive Nanosecond Pulses in Air Using Water Electrodes

    NASA Astrophysics Data System (ADS)

    Shao, Tao; Yu, Yang; Zhang, Cheng; Jiang, Hui; Yan, Ping; Zhou, Yuanxiang

    2011-12-01

    Dielectric barrier discharge (DBD) excitated by pulsed power is a promising method for producing nonthermal plasma at atmospheric pressure. Discharge characteristic in a DBD with salt water as electrodes by a home-made unipolar nanosecond-pulse power source is presented in this paper. The generator is capable of providing repetitive pulses with the voltage up to 30 kV and duration of 70 ns at a 300 Ω resistive load. Applied voltage and discharge current are measured under various experimental conditions. The DBD created between two liquid electrodes shows that the discharge is homogeneous and diffuse in the whole discharge regime. Spectra diagnosis is conducted by an optical emission spectroscopy. The air plasma has strong emission from nitrogen species below 400 nm, notably the nitrogen second positive system.

  4. Synthesis of ammonia directly from air and water at ambient temperature and pressure

    PubMed Central

    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. PMID:23362454

  5. Analysis of Cylinder-pressure-indicator Diagrams Showing Effects of Mixture Strength and Spark Timing

    NASA Technical Reports Server (NTRS)

    Gerrish, Harold C; Voss, Fred

    1940-01-01

    An investigation was made to determine the effect of mixture strength and of normal as well as optimum spark timing on the combustion, on the cylinder temperature, and on the performance characteristics of an engine. A single-cylinder test unit utilizing an air-cooled cylinder and a carburetor and operating with gasoline having an octane rating of 92 was used. The investigation covered a range of fuel-air ratios from 0.053 to 0.118. Indicator diagrams and engine-performance data were taken for each change in engine conditions. Examination of the indicator shows that for fuel-air ratios less than and greater than 0.082 the rate and the amount of effective fuel burned decreased. For a fuel-air ratio of 0.118 the combustion efficiency was only 58 percent. Advancing the spark timing increased the rate of pressure rise. This effect was more pronounced with leaner mixtures.

  6. Health effects of particulate air pollution: time for reassessment?

    PubMed Central

    Pope, C A; Bates, D V; Raizenne, M E

    1995-01-01

    Numerous studies have observed health effects of particulate air pollution. Compared to early studies that focused on severe air pollution episodes, recent studies are more relevant to understanding health effects of pollution at levels common to contemporary cities in the developed world. We review recent epidemiologic studies that evaluated health effects of particulate air pollution and conclude that respirable particulate air pollution is likely an important contributing factor to respiratory disease. Observed health effects include increased respiratory symptoms, decreased lung function, increased hospitalizations and other health care visits for respiratory and cardiovascular disease, increased respiratory morbidity as measured by absenteeism from work or school or other restrictions in activity, and increased cardiopulmonary disease mortality. These health effects are observed at levels common to many U.S. cities including levels below current U.S. National Ambient Air Quality Standards for particulate air pollution. Images Figure 1. PMID:7656877

  7. Novel atmospheric pressure plasma device releasing atomic hydrogen: reduction of microbial-contaminants and OH radicals in the air

    NASA Astrophysics Data System (ADS)

    Nojima, Hideo; Park, Rae-Eun; Kwon, Jun-Hyoun; Suh, Inseon; Jeon, Junsang; Ha, Eunju; On, Hyeon-Ki; Kim, Hye-Ryung; Choi, Kyoung Hui; Lee, Kwang-Hee; Seong, Baik-Lin; Jung, Hoon; Kang, Shin Jung; Namba, Shinichi; Takiyama, Ken

    2007-01-01

    A novel atmospheric pressure plasma device releasing atomic hydrogen has been developed. This device has specific properties such as (1) deactivation of airborne microbial-contaminants, (2) neutralization of indoor OH radicals and (3) being harmless to the human body. It consists of a ceramic plate as a positive ion generation electrode and a needle-shaped electrode as an electron emission electrode. Release of atomic hydrogen from the device has been investigated by the spectroscopic method. Optical emission of atomic hydrogen probably due to recombination of positive ions, H+(H2O)n, generated from the ceramic plate electrode and electrons emitted from the needle-shaped electrode have been clearly observed in the He gas (including water vapour) environment. The efficacy of the device to reduce airborne concentrations of influenza virus, bacteria, mould fungi and allergens has been evaluated. 99.6% of airborne influenza virus has been deactivated with the operation of the device compared with the control test in a 1 m3 chamber after 60 min. The neutralization of the OH radical has been investigated by spectroscopic and biological methods. A remarkable reduction of the OH radical in the air by operation of the device has been observed by laser-induced fluorescence spectroscopy. The cell protection effects of the device against OH radicals in the air have been observed. Furthermore, the side effects have been checked by animal experiments. The harmlessness of the device has been confirmed.

  8. 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.

  9. 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.

  10. Effect of inlet-air humidity on the formation of oxides of nitrogen in a gas-turbine combustor

    NASA Technical Reports Server (NTRS)

    Marchionna, N. R.

    1973-01-01

    Tests were conducted to determine the effect of inlet-air humidity on the formation of oxides of nitrogen from a gas-turbine combustor. Combustor inlet-air temperature ranged from 450 F to 1050 F. The tests were run at a constant pressure of 6 atmospheres and reference Mach number of 0.065. The NO sub x emission index was found to decrease with increasing inlet-air humidity at a constant exponential rate of 19 percent per mass percent water vapor in the air. This decrease of NO sub x emission index with increasing humidity was found to be independent of inlet-air temperature.

  11. 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.

  12. Effects of Conversational Pressures on Speech Planning

    ERIC Educational Resources Information Center

    Swets, Benjamin; Jacovina, Matthew E.; Gerrig, Richard J.

    2013-01-01

    In ordinary conversation, speakers experience pressures both to produce utterances suited to particular addressees and to do so with minimal delay. To document the impact of these conversational pressures, our experiment asked participants to produce brief utterances to describe visual displays. We complicated utterance planning by including…

  13. Atmospheric Effects on Cosmic Ray Air Showers Observed with HAWC

    NASA Astrophysics Data System (ADS)

    Young, Steven

    2014-01-01

    The High Altitude Water Cherenkov Gamma Ray detector (HAWC), currently under construction on the Sierra Negra volcano near Puebla, Mexico, can be used to study solar physics with its scaler data acquisition system. Increases in the scaler rates are used to observe GeV cosmic rays from solar flares while decreases in the rates show the heliospheric disturbances associated with coronal mass ejections. However, weather conditions and height-dependent state variables such as pressure and temperature affect the production of extensive particle air showers that can be detected by the scaler system. To see if these atmospheric effects can be removed, we obtained local weather data from the Global Data Assimilation System (GDAS) and the local weather station at HAWC. The scaler pulse rates were then correlated to the pressure and temperature. We present data from a Forbush decrease observed by HAWC following a significant coronal mass ejection in April 2013, and describe our efforts to remove atmospheric variations from the scaler counts. This work was partially supported by the National Science Foundation’s REU program through NSF Award AST-1004881 to the University of Wisconsin-Madison.

  14. 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.

  15. Repetitively pulsed atmospheric pressure discharge treatment of rough polymer surfaces: I. Humid air discharges

    NASA Astrophysics Data System (ADS)

    Bhoj, Ananth N.; Kushner, Mark J.

    2008-08-01

    Plasmas generated at atmospheric pressure are used to functionalize the surfaces of polymers by creating new surface-resident chemical groups. The polymers used in textiles and biomedical applications often have non-planar surfaces whose functionalization requires penetration of plasma generated species into sometimes complex surface features. In this regard, the atmospheric pressure plasma treatment of a rough polypropylene surface was computationally investigated using a two-dimensional plasma hydrodynamics model integrated with a surface kinetics model. Repetitively pulsed discharges produced in a dielectric barrier-corona configuration in humid air were considered to affix O. Macroscopic non-uniformities in treatment result from the spatial variations in radical densities which depend on the polarity of the discharge. Microscopic non-uniformities arise due to the higher reactivity of plasma produced species, such as OH radicals, which are consumed before they can diffuse deeper into surface features. The consequences of applied voltage magnitude and polarity, and the relative humidity on discharge dynamics and radical generation leading to surface functionalization, are discussed.

  16. Influence of low air pressure on flashover voltages of polluted insulators

    SciTech Connect

    Rudakova, V.M.; Tikhodeev, N.N.

    1989-01-01

    Numerous mountain 110 to 500 kV power transmission lines are in operation in the USSR; since 1967 a 110 kV lien has been in service at an altitude (H/sub o/) up to 3.58 km above the sea level; a recent 100 kV overhead line has H/sub o/ = 4 km, its entire 224 km length running above 1,8 km and at least 65% of its right-of-way lying in mountains with H/sub o/ less than or equal to 3 km. A number of 220 to 500 kV lines cross passes whose latitude exceeds 3.2 km. Construction of overhead lines in the mountains of the Caucasus, Central Asia and in the Eastern USSR made it necessary to conduct unique studies of outdoor insulation behaviour at air pressures p below the normal pressure values p/sub o/. Some of the studies were made in altitude chambers, and some, at special high-altitude outdoor test facilities. Here an attempt is made to generalize basic results of these studies made in the USSR.

  17. Numerical and experimental study of an axisymmetric coflow laminar methane-air diffusion flame at pressures between 5 and 40 atmospheres

    SciTech Connect

    Liu, Fengshan; Thomson, Kevin A.; Guo, Hongsheng; Smallwood, Gregory J.

    2006-08-15

    A numerical and experimental study of an axisymmetric coflow laminar methane-air diffusion flame at pressures between 5 and 40 atm was conducted to investigate the effect of pressure on the flame structure and soot formation characteristics. Experimental work was carried out in a new high-pressure combustion chamber described in a recent study [K.A. Thomson, O.L. Gulder, E.J. Weckman, R.A. Fraser, G.J. Smallwood, D.R. Snelling, Combust. Flame 140 (2005) 222-232]. Radially resolved soot volume fraction was experimentally measured using both spectral soot emission and line-of-sight attenuation techniques. Numerically, the elliptic governing equations were solved in axisymmetric cylindrical coordinates using the finite volume method. Detailed gas-phase chemistry and complex thermal and transport properties were employed in the numerical calculations. The soot model employed in this study accounts for soot nucleation and surface growth using a semiempirical acetylene-based global soot model with oxidation of soot by O{sub 2}, OH, and O taken into account. Radiative heat transfer was calculated using the discrete-ordinates method and a nine-band nongray radiative property model. Two soot surface growth submodels were investigated and the predicted pressure dependence of soot yield was compared with available experimental data. The experiment, the numerical model, and a simplified theoretical analysis found that the visible flame diameter decreases with pressure as P{sub a}{sup -0.5}. The flame-diameter-integrated soot volume fraction increases with pressure as P{sub a}{sup 1.3} between 5 and 20 atm. The assumption of a square root dependence of the soot surface growth rate on the soot particle surface area predicts the pressure dependence of soot yield in good agreement with the experimental observation. On the other hand, the assumption of linear dependence of the soot surface growth rate on the soot surface area predicts a much faster increase in the soot yield with

  18. Air Pollution and Heart Disease, Stroke

    MedlinePlus

    ... Pressure High Blood Pressure Tools & Resources Stroke More Air Pollution and Heart Disease, Stroke Updated:Aug 30,2016 ... or Longer-Term Acute short-term effects of air pollution tend to strike people who are elderly or ...

  19. Generation of aerosols by the electrical explosion of wires at reduced air pressure

    SciTech Connect

    Sedoi, V.S.; Valevich, V.V.; Katz, J.D.

    1998-12-31

    The exploding wire method of particle production allows the authors to model the high speed formation of aerosols because of the fast heating and evaporation rates inherent to this technique. The method is also of interest from the viewpoint of controlling the production of aerosols of a particular material with a specific particle size distribution at a specific efficiency. The electrical explosion of iron, aluminum, titanium, and copper wires have been investigated in various gases at pressures from 0.01 to 1 atm. In these experiments the energy density introduced into the material, w, is normalized to the sublimation energy of the material, w{sub s}. The energy density also controls the heating rate. Particle and agglomerate sizes were determined using transmission electron microscopy and laser scattering methods. The specific surface area of the powder was measured by low-temperature adsorption. The phase composition was determined by X-ray diffraction. Increasing the energy density increases the internal energy of the material, the expansion velocity and the number of condensation centers, while the final particle size decreases. With an exothermic oxidation reaction, the optimum energy density can be less than the sublimation energy of the material. As a result, metal oxides are formed. Electrical explosion of wires, at reduced air pressures, allows for the production of ultra-fine powders of oxides of various metals with particle sizes of less than 50 nm. The method is environmentally safe and does not require excess energy expenditures. The electrical explosion of wire at reduced pressure allows for new possibilities in the production of ultra-fine powders (UFP).

  20. Pressure responses of portlandite and H-D isotope effects on pressure-induced phase transitions

    NASA Astrophysics Data System (ADS)

    Iizuka, Riko; Kagi, Hiroyuki; Komatsu, Kazuki; Ushijima, Daichi; Nakano, Satoshi; Sano-Furukawa, Asami; Nagai, Takaya; Yagi, Takehiko

    2011-12-01

    The pressure responses of portlandite and the isotope effect on the phase transition were investigated at room temperature from single-crystal Raman and IR spectra and from powder X-ray diffraction using diamond anvil cells under quasi-hydrostatic conditions in a helium pressure-transmitting medium. Phase transformation and subsequent peak broadening (partial amorphization) observed from the Raman and IR spectra of Ca(OH)2 occurred at lower pressures than those of Ca(OD)2. In contrast, no isotope effect was found on the volume and axial compressions observed from powder X-ray diffraction patterns. X-ray diffraction lines attributable to the high-pressure phase remained up to 28.5 GPa, suggesting no total amorphization in a helium pressure medium within the examined pressure region. These results suggest that the H-D isotope effect is engendered in the local environment surrounding H(D) atoms. Moreover, the ratio of sample-to-methanol-ethanol pressure medium (i.e., packing density) in the sample chamber had a significant effect on the increase in the half widths of the diffraction lines, even at pressures below the hydrostatic limit of the pressure medium.

  1. Experimental study on the flow regimes and pressure gradients of air-oil-water three-phase flow in horizontal pipes.

    PubMed

    Al-Hadhrami, Luai M; Shaahid, S M; Tunde, Lukman O; Al-Sarkhi, A

    2014-01-01

    An experimental investigation has been carried out to study the flow regimes and pressure gradients of air-oil-water three-phase flows in 2.25 ID horizontal pipe at different flow conditions. The effects of water cuts, liquid and gas velocities on flow patterns and pressure gradients have been studied. The experiments have been conducted at 20 °C using low viscosity Safrasol D80 oil, tap water and air. Superficial water and oil velocities were varied from 0.3 m/s to 3 m/s and air velocity varied from 0.29 m/s to 52.5 m/s to cover wide range of flow patterns. The experiments were performed for 10% to 90% water cuts. The flow patterns were observed and recorded using high speed video camera while the pressure drops were measured using pressure transducers and U-tube manometers. The flow patterns show strong dependence on water fraction, gas velocities, and liquid velocities. The observed flow patterns are stratified (smooth and wavy), elongated bubble, slug, dispersed bubble, and annular flow patterns. The pressure gradients have been found to increase with the increase in gas flow rates. Also, for a given superficial gas velocity, the pressure gradients increased with the increase in the superficial liquid velocity. The pressure gradient first increases and then decreases with increasing water cut. In general, phase inversion was observed with increase in the water cut. The experimental results have been compared with the existing unified Model and a good agreement has been noticed. PMID:24523645

  2. Experimental Study on the Flow Regimes and Pressure Gradients of Air-Oil-Water Three-Phase Flow in Horizontal Pipes

    PubMed Central

    Al-Hadhrami, Luai M.; Shaahid, S. M.; Tunde, Lukman O.; Al-Sarkhi, A.

    2014-01-01

    An experimental investigation has been carried out to study the flow regimes and pressure gradients of air-oil-water three-phase flows in 2.25 ID horizontal pipe at different flow conditions. The effects of water cuts, liquid and gas velocities on flow patterns and pressure gradients have been studied. The experiments have been conducted at 20°C using low viscosity Safrasol D80 oil, tap water and air. Superficial water and oil velocities were varied from 0.3 m/s to 3 m/s and air velocity varied from 0.29 m/s to 52.5 m/s to cover wide range of flow patterns. The experiments were performed for 10% to 90% water cuts. The flow patterns were observed and recorded using high speed video camera while the pressure drops were measured using pressure transducers and U-tube manometers. The flow patterns show strong dependence on water fraction, gas velocities, and liquid velocities. The observed flow patterns are stratified (smooth and wavy), elongated bubble, slug, dispersed bubble, and annular flow patterns. The pressure gradients have been found to increase with the increase in gas flow rates. Also, for a given superficial gas velocity, the pressure gradients increased with the increase in the superficial liquid velocity. The pressure gradient first increases and then decreases with increasing water cut. In general, phase inversion was observed with increase in the water cut. The experimental results have been compared with the existing unified Model and a good agreement has been noticed. PMID:24523645

  3. 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.

  4. 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.

  5. Characterization of air freshener emission: the potential health effects.

    PubMed

    Kim, Sanghwa; Hong, Seong-Ho; Bong, Choon-Keun; Cho, Myung-Haing

    2015-01-01

    Air freshener could be one of the multiple sources that release volatile organic compounds (VOCs) into the indoor environment. The use of these products may be associated with an increase in the measured level of terpene, such as xylene and other volatile air freshener components, including aldehydes, and esters. Air freshener is usually used indoors, and thus some compounds emitted from air freshener may have potentially harmful health impacts, including sensory irritation, respiratory symptoms, and dysfunction of the lungs. The constituents of air fresheners can react with ozone to produce secondary pollutants such as formaldehyde, secondary organic aerosol (SOA), oxidative product, and ultrafine particles. These pollutants then adversely affect human health, in many ways such as damage to the central nervous system, alteration of hormone levels, etc. In particular, the ultrafine particles may induce severe adverse effects on diverse organs, including the pulmonary and cardiovascular systems. Although the indoor use of air freshener is increasing, deleterious effects do not manifest for many years, making it difficult to identify air freshener-associated symptoms. In addition, risk assessment recognizes the association between air fresheners and adverse health effects, but the distinct causal relationship remains unclear. In this review, the emitted components of air freshener, including benzene, phthalate, and limonene, were described. Moreover, we focused on the health effects of these chemicals and secondary pollutants formed by the reaction with ozone. In conclusion, scientific guidelines on emission and exposure as well as risk characterization of air freshener need to be established. PMID:26354370

  6. 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.

  7. 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.

  8. Flight Investigation of the Effects of Pressure-Belt Tubing Size on Measured Pressure Distributions

    NASA Technical Reports Server (NTRS)

    Rivers, Natale A.; vanDam, Cornielious P.; Brown, Phillip W.; Rivers, Robert A.

    2001-01-01

    The pressure-belt technique is commonly used to measure pressure distributions on lifting and nonlifting surfaces where flush, through-the-surface measurements are not possible. The belts, made from strips of small-bore, flexible plastic tubing, are surface-mounted by a simple, nondestructive method. Additionally, the belts require minimal installation time, thus making them much less costly to install than flush-mounted pressure ports. Although pressure belts have been used in flight research since the early 1950s, only recently have manufacturers begun to produce thinner, more flexible tubing, and thin, strong adhesive tapes that minimize the installation-induced errors on the measurement of surface pressures. The objective of this investigation was to determine the effects of pressure-belt tubing size on the measurement of pressure distributions. For that purpose, two pressure belts were mounted on the right wing of a single-engine, propeller-driven research airplane. The outboard pressure belt served as a baseline for the measurement and the comparison of effects. Each tube had an outer diameter (OD) of 0.0625 in. The inboard belt was used to evaluate three different tube sizes: 0.0625-, 0.1250-, and 0.1875-in. OD. A computational investigation of tube size on pressure distribution also was conducted using the two-dimensional Multielement Streamtube Euler Solver (MSES) code.

  9. Air exchange effectiveness of conventional and task ventilation for offices

    SciTech Connect

    Fisk, W.J.; Faulkner, D.; Prill, R.J.

    1991-12-01

    Air quality and comfort complaints within large buildings are often attributed to air distribution problems. We define three air exchange effectiveness parameters related to air distribution. The first two indicate the indoor air flow pattern (i.e., the extent of short circuiting, mixing, or displacement flow) for an entire building or region. The third parameter is most useful for assessments of the spatial variability of ventilation. We also define the air diffusion effectiveness which indicates the air flow pattern within specific rooms or sections of buildings. The results of measurements of these parameters in US office buildings by the authors and other researchers are reviewed. Almost all measurements indicate very limited short circuiting or displacement flow between locations of air supply and removal. However, a moderate degree of short circuiting is evident from a few measurements in rooms with heated supply air. The results of laboratory-based measurements by the authors are consistent with the field data. Our measurements in office buildings do indicate that ventilation rates can vary substantially between indoor locations, probably due to variation in air supply rates between locations rather than variation in the indoor air flow patterns. One possible method of improving air distribution is to employ task ventilation with air supplied closer to the occupant`s breathing zone. We have evaluated two task ventilation systems in a laboratory setting. During most operating conditions, these systems did not provide a region of substantially increased ventilation where occupants breath. However, both systems are capable of providing substantially enhanced ventilation at the breathing zone under some operating conditions. Therefore, task ventilation is a potential option for using ventilation air more effectively.

  10. Air exchange effectiveness of conventional and task ventilation for offices

    SciTech Connect

    Fisk, W.J.; Faulkner, D.; Prill, R.J.

    1991-12-01

    Air quality and comfort complaints within large buildings are often attributed to air distribution problems. We define three air exchange effectiveness parameters related to air distribution. The first two indicate the indoor air flow pattern (i.e., the extent of short circuiting, mixing, or displacement flow) for an entire building or region. The third parameter is most useful for assessments of the spatial variability of ventilation. We also define the air diffusion effectiveness which indicates the air flow pattern within specific rooms or sections of buildings. The results of measurements of these parameters in US office buildings by the authors and other researchers are reviewed. Almost all measurements indicate very limited short circuiting or displacement flow between locations of air supply and removal. However, a moderate degree of short circuiting is evident from a few measurements in rooms with heated supply air. The results of laboratory-based measurements by the authors are consistent with the field data. Our measurements in office buildings do indicate that ventilation rates can vary substantially between indoor locations, probably due to variation in air supply rates between locations rather than variation in the indoor air flow patterns. One possible method of improving air distribution is to employ task ventilation with air supplied closer to the occupant's breathing zone. We have evaluated two task ventilation systems in a laboratory setting. During most operating conditions, these systems did not provide a region of substantially increased ventilation where occupants breath. However, both systems are capable of providing substantially enhanced ventilation at the breathing zone under some operating conditions. Therefore, task ventilation is a potential option for using ventilation air more effectively.

  11. Moderate pressure is essential for massage therapy effects.

    PubMed

    Field, Tiffany; Diego, Miguel; Hernandez-Reif, Maria

    2010-05-01

    Moderate pressure appears to be necessary for massage therapy effects. Studies comparing moderate and light pressure massage are reviewed and they suggest that growth and development are enhanced in infants and stress is reduced in adults, but only by moderate pressure massage. The stimulation of pressure receptors leads to increased vagal activity which, in turn, seems to mediate the diverse benefits noted for massage therapy. PMID:20402578

  12. Measured pressure distributions, aerodynamic coefficients and shock shapes on blunt bodies at incidence in hypersonic air and CF4

    NASA Technical Reports Server (NTRS)

    Miller, C. G., III

    1982-01-01

    Pressure distributions, aerodynamic coefficients, and shock shapes were measured on blunt bodies of revolution in Mach 6 CF4 and in Mach 6 and Mach 10 air. The angle of attack was varied from 0 deg to 20 deg in 4 deg increments. Configurations tested were a hyperboloid with an asymptotic angle of 45 deg, a sonic-corner paraboloid, a paraboloid with an angle of 27.6 deg at the base, a Viking aeroshell generated in a generalized orthogonal coordinate system, and a family of cones having a 45 deg half-angle with spherical, flattened, concave, and cusp nose shapes. Real-gas effects were simulated for the hperboloid and paraboloid models at Mach 6 by testing at a normal-shock density ratio of 5.3 in air and 12 CF4. Predictions from simple theories and numerical flow field programs are compared with measurement. It is anticipated that the data presented in this report will be useful for verification of analytical methods for predicting hypersonic flow fields about blunt bodies at incidence.

  13. Quantitative Analysis of Spectral Interference of Spontaneous Raman Scattering in High-Pressure Fuel-Rich H2-Air Combustion

    NASA Technical Reports Server (NTRS)

    Kojima, Jun; Nguyen, Quang-Viet

    2004-01-01

    We present a theoretical study of the spectral interferences in the spontaneous Raman scattering spectra of major combustion products in 30-atm fuel-rich hydrogen-air flames. An effective methodology is introduced to choose an appropriate line-shape model for simulating Raman spectra in high-pressure combustion environments. The Voigt profile with the additive approximation assumption was found to provide a reasonable model of the spectral line shape for the present analysis. The rotational/vibrational Raman spectra of H2, N2, and H2O were calculated using an anharmonic-oscillator model using the latest collisional broadening coefficients. The calculated spectra were validated with data obtained in a 10-atm fuel-rich H2-air flame and showed excellent agreement. Our quantitative spectral analysis for equivalence ratios ranging from 1.5 to 5.0 revealed substantial amounts of spectral cross-talk between the rotational H2 lines and the N2 O-/Q-branch; and between the vibrational H2O(0,3) line and the vibrational H2O spectrum. We also address the temperature dependence of the spectral cross-talk and extend our analysis to include a cross-talk compensation technique that removes the nterference arising from the H2 Raman spectra onto the N2, or H2O spectra.

  14. Effects of high pressure hydrogen on metals

    NASA Technical Reports Server (NTRS)

    Chandler, W. T.; Walter, R. J.

    1970-01-01

    Hydrogen environment embrittlement causes failure of hydrogen storage vessels at and below design pressures of 5000 to 6000 psi. Investigation of thirty-five alloys determines their susceptibility to such embrittlement.

  15. Effects of inner materials on the sensitivity and phase depth of wireless inductive pressure sensors for monitoring intraocular pressure

    NASA Astrophysics Data System (ADS)

    Jang, Cheol-In; Shin, Kyeong-Sik; Kim, Mi Jeung; Yun, Kwang-Seok; Park, Ki Ho; Kang, Ji Yoon; Lee, Soo Hyun

    2016-03-01

    In this research, we developed wireless, inductive, pressure sensors with high sensitivity and investigated the effects of the inner materials (copper or ferrite) on the performance of the sensors. The proposed sensor is comprised of two parts, i.e., the top and the bottom parts. The top part includes a micro coil and a capacitor for the wireless transfer of data, and the bottom part includes the inner materials and a thick or thin flexible membrane to induce changes in the inductance. An anchor is used to assemble the top and bottom parts. The behavior of the sensor with copper was based on the eddy current effect, and, as the pressure increased, its resonance frequency increased, while its phase depth decreased exponentially. The principle of the sensor with ferrite was related to the effective permeability between a ferrite and a coil, and its response was the opposite of that with copper, i.e., as the pressure increased, the resonance frequency decreased linearly, and the phase depth increased linearly. These different operational mechanisms can be explained by the changes in the equations of inductance presented in this paper. After characterizing four different types of inductive pressure sensors in ambient air, one type of inductive pressure sensor was used to monitor the intraocular pressure (IOP) of a rabbit's eye as a biomedical application. The results showed that, in the animal tests, the measured responsivity and sensitivity were 16.7 kHz/mmHg and 1340 ppm/mmHg, respectively. These data indicate that the proposed sensor is a good candidate for monitoring IOP.

  16. UNDERSTANDING THE EFFECTS OF AIR POLLUTION ON HUMAN HEALTH

    EPA Science Inventory

    Modern air pollution regulation is first and foremost motivated by concerns about the effects of air pollutants on human health and secondarily by concerns about its effects on ecosystems, cultural artifacts, and quality of life values such as visibility. This order of priority ...

  17. LONG-TERM EFFECTS OF AIR POLLUTANTS: IN CANINE SPECIES

    EPA Science Inventory

    The Clean Air Act of 1970 as amended in 1977 requires that a comprehensive data base be established to assess human health effects caused by air pollution from mobile sources. The spectrum of potential toxic effects can be viewed from two perspectives: The first is the identifica...

  18. Some Factors Influencing Air Force Simulator Training Effectiveness. Technical Report.

    ERIC Educational Resources Information Center

    Caro, Paul W.

    A study of U.S. Air Force simulator training was conducted to identify factors that influence the effectiveness of such training and to learn how its effectiveness is being determined. The research consisted of a survey of ten representative Air Force simulator training programs and a review of the simulator training research literature. A number…

  19. Effect of high pressure on cod (Gadus morhua) desalting

    NASA Astrophysics Data System (ADS)

    Salvador, Ângelo C.; Saraiva, Jorge A.; Fidalgo, Liliana G.; Delgadillo, Ivonne

    2013-06-01

    The effect of high pressure on salt and water diffusion in the desalting process of cod was studied. Under pressure, up to 300 MPa, the osmotic equilibrium is reached much faster, compared to desalting at atmospheric pressure. Water (D ew) and salt (D es) effective diffusion coefficients reached a maximum at 200 MPa, increasing 500- and 160-fold, respectively, compared with desalting at atmospheric pressure. Increasing pressure up to 300 MPa causes a reduction in both effective diffusion coefficients, although they were still about 70-fold higher than at atmospheric pressure. Up to 200 MPa, a linear correlation was found between D ew and D es and pressure. However, the total diffused amounts of water and salt, when the osmotic equilibrium was reached, were lower under pressure. At atmospheric pressure cod water content increased 1.65-fold, but under pressure the increment was on average 1.25-fold, while salt content decreased to 0.51-fold the initial value at atmospheric pressure and to around 0.75-fold under pressure.

  20. Tooth Whitening Effects by Atmospheric Pressure Cold Plasmas with Different Gases

    NASA Astrophysics Data System (ADS)

    Choi, Hye-sook; Kim, Kyoung-Nam; You, Eun-Mi; Choi, Eun-Ha; Kim, Yong-Hee; Kim, Kwang-Mahn

    2013-11-01

    The aim of the present study was to investigate the effects of atmospheric pressure cold plasma with different gases on external tooth bleaching. After 10 min treatment, the air (50%) + oxygen (50%) group shows a remarkable color change (ΔE*), and nitrogen and air groups indicate some color change, although not as much as that shown by the air + oxygen group. Also, the argon group shows the least amount of color change among the various gases in this experiment. Atomic oxygen species exists during this tooth bleaching as determined by optical emission spectroscopy. Hence, atmospheric pressure cold plasma treatment could significantly accelerate the tooth bleaching process owing to this atomic oxygen species, and the intensity of tooth bleaching depends on the type of gas in the cold plasma.

  1. Register Closing Effects on Forced Air Heating System Performance

    SciTech Connect

    Walker, Iain S.

    2003-11-01

    Closing registers in forced air heating systems and leaving some rooms in a house unconditioned has been suggested as a method of quickly saving energy for California consumers. This study combined laboratory measurements of the changes in duct leakage as registers are closed together with modeling techniques to estimate the changes in energy use attributed to closing registers. The results of this study showed that register closing led to increased energy use for a typical California house over a wide combination of climate, duct leakage and number of closed registers. The reduction in building thermal loads due to conditioning only a part of the house was offset by increased duct system losses; mostly due to increased duct leakage. Therefore, the register closing technique is not recommended as a viable energy saving strategy for California houses with ducts located outside conditioned space. The energy penalty associated with the register closing technique was found to be minimized if registers furthest from the air handler are closed first because this tends to only affect the pressures and air leakage for the closed off branch. Closing registers nearer the air handler tends to increase the pressures and air leakage for the whole system. Closing too many registers (more than 60%) is not recommended because the added flow resistance severely restricts the air flow though the system leading to safety concerns. For example, furnaces may operate on the high-limit switch and cooling systems may suffer from frozen coils.

  2. Air- and N2-Broadening Coefficients and Pressure-Shift Coefficients in the C-12(O2-16) Laser Bands

    NASA Technical Reports Server (NTRS)

    Devi, V. Malathy; Benner, D. Chris; Smith, Mary Ann H.; Rinsland, Curtis P.

    1998-01-01

    In this paper we report the pressure broadening and the pressure-induced line shift coefficients for 46 individual rovibrational lines in both the (12)C(16)O2, 00(sup 0)1-(10(sup 0)0-02(sup 0)0)I, and 00(sup 0)1-(10(sup 0)0-02(sup 0)0)II, laser bands (laser band I centered at 960.959/cm and laser band II centered at 1063.735/cm) determined from spectra recorded with the McMath-Pierce Fourier transform spectrometer. The results were obtained from analysis of 10 long-path laboratory absorption spectra recorded at room temperature using a multispectrum nonlinear least-squares technique. Pressure effects caused by both air and nitrogen have been investigated. The air-broadening coefficients determined in this study agree well with the values in the 1996 HITRAN database; ratios and standard deviations of the ratios of the present air-broadening measurements to the 1996 HITRAN values for the two laser bands are: 1.005(15) for laser band I and 1.005(14) for laser band II. Broadening by nitrogen is 3 to 4% larger than that of air. The pressure-induced line shift coefficients are found to be transition dependent and different for the P- and R-branch lines with same J" value. No noticeable differences in the shift coefficients caused by air and nitrogen were found. The results obtained are compared with available values previously reported in the literature.

  3. The development of effects-based air quality management regimes

    NASA Astrophysics Data System (ADS)

    Longhurst, J. W. S.; Irwin, J. G.; Chatterton, T. J.; Hayes, E. T.; Leksmono, N. S.; Symons, J. K.

    This paper considers the evolution of attempts to control and manage air pollution, principally but not exclusively focussing upon the challenge of managing air pollution in urban environments. The development and implementation of a range of air pollution control measures are considered. Initially the measures implemented primarily addressed point sources, a small number of fuel types and a limited number of pollutants. The adequacy of such a source-control approach is assessed within the context of a changing and challenging air pollution climate. An assessment of air quality management in the United Kingdom over a 50-year timeframe exemplifies the range of issues and challenges in contemporary air quality management. The need for new approaches is explored and the development and implementation of an effects-based, risk management system for air quality regulation is evaluated.

  4. 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

  5. The effect of pressure drop on respirator faceseal leakage.

    PubMed

    Janssen, Larry; Weber, Robert

    2005-07-01

    Users of particulate air-purifying respirators are typically told to change their filters when breathing resistance becomes uncomfortable. It has been proposed that a noticeable increase in breathing resistance (pressure drop) may increase airflow through respirator faceseal leaks. This logic has been extended to suggest that respirator user exposure to contaminants may increase because of this theoretical increase in air leakage. Procedures similar to those of previous investigators were used to study this issue. Repeated faceseal leak rate measurements were made at -5.6 through -20.1 mm water pressure drops across the faceseal. Subjects were divided into two groups, representing acceptable fit or unacceptable fit, based on leak rate criteria prescribed by the Occupational Safety and Health Administration (OSHA). Subjects with acceptable fit did not experience an increase in faceseal leak rate with increased pressure drop. Leak rates for subjects with unacceptable fit were highly variable and did not show an association with pressure drop. Results of this study do not support the concept of increased faceseal leakage with increased pressure drop. The evidence does not suggest increased risk of contaminant exposure through the face seal as pressure drop increases. PMID:16020096

  6. Effects of atmospheric pressures on gas transport in the vadose zone

    SciTech Connect

    Massmann, J. ); Farrier, D.F. )

    1992-03-01

    Temporal variations in barometric pressure due to weather patterns may induce air intrusion into the subsurface. This air intrusion can affect monitoring activities aimed at characterizing the composition and movement of gases in the vadose zone. Expressions are presented to estimate gas fluxes due to the combined effects of Knudsen diffusion, multicomponent molecular diffusion, and viscous flow. These expressions are used to evaluate the validity of the single-component advection-dispersion equation for simulating gas transport in the presence of atmospheric pressure variations. The single-component equation provides reasonable results when used to simulate transport in media with relatively high gas permeability. Computer simulations of vertical transport at sites with homogeneous soils indicate that fresh' air can migrate several meters into the subsurface during a typical barometric pressure cycle. Horizontal pressure gradients can develop at sites with near-surface heterogeneities. These gradients may cause fresh air to intrude meters or tens of meters into the vadose zone during a storm event.

  7. Respiratory effects of air pollution on children.

    PubMed

    Goldizen, Fiona C; Sly, Peter D; Knibbs, Luke D

    2016-01-01

    A substantial proportion of the global burden of disease is directly or indirectly attributable to exposure to air pollution. Exposures occurring during the periods of organogenesis and rapid lung growth during fetal development and early post-natal life are especially damaging. In this State of the Art review, we discuss air toxicants impacting on children's respiratory health, routes of exposure with an emphasis on unique pathways relevant to young children, methods of exposure assessment and their limitations and the adverse health consequences of exposures. Finally, we point out gaps in knowledge and research needs in this area. A greater understanding of the adverse health consequences of exposure to air pollution in early life is required to encourage policy makers to reduce such exposures and improve human health. PMID:26207724

  8. Effect of fuel/air nonuniformity on nitric oxide emissions

    NASA Technical Reports Server (NTRS)

    Lyons, V. J.

    1979-01-01

    A flame tube combustor holding jet A fuel was used in experiments performed at a pressure of .3 Mpa and a reference velocity of 25 meters/second for three inlet air temperatures of 600, 700, and 800 K. The gas sample measurements were taken at locations 18 cm and 48 cm downstream of the perforated plate flameholder. Nonuniform fuel/air profiles were produced using a fuel injector by separately fueling the inner five fuel tubes and the outer ring of twelve fuel tubes. Six fuel/air profiles were produced for nominal overall equivalence ratios of .5 and .6. An example of three of three of these profiles and their resultant nitric oxide NOx emissions are presented. The uniform fuel/air profile cases produced uniform and relatively low profile levels. When the profiles were either center-peaked or edge-peaked, the overall mass-weighted nitric oxide levels increased.

  9. Effects of different cold-air exposure intensities on the risk of cardiovascular disease in healthy and hypertensive rats

    NASA Astrophysics Data System (ADS)

    Luo, Bin; Zhang, Shuyu; Ma, Shoucun; Zhou, Ji; Wang, Baojian

    2014-03-01

    Ten-week-old male Wistar rats (systolic blood pressure, 106-116 mmHg; body weight, 300-320 g) and spontaneously hypertensive rats (systolic blood pressure, 160-176 mmHg; body weight, 210.9-244.9 g) were used as healthy and hypertensive subjects to determine the effects of varying degrees of cold-air exposure in a climate chamber box. The three cold-air ranks were cold air I [minimum temperature (TMIN) 6.4 °C, ↓∆T48 8.6 °C], cold air II (TMIN 3.8 °C, ↓∆T48 11.2 °C), and cold air III (TMIN -0.3 °C, ↓∆T48 15.3 °C), as established from the cold-air data of Zhangye City, China. Each cold-air rank consisted of a temperature drop and a temperature increase with the same initial and terminal temperatures (15 °C). After cold-air exposure, the risk factors for cardiovascular disease (CVD) such as systolic blood pressure, whole blood viscosity (10/s and 150/s), plasma fibrinogen, and blood lipids of the rats were determined. The results indicated that the CVD risk factors of the healthy and hypertensive rats increased significantly with cold-air exposure intensities. The increase in systolic blood pressure was greater during temperature drops, whereas the increases in whole blood viscosity and plasma fibrinogen were greater after cold-air exposure. The effects of cold-air exposure on the CVD risk factors of healthy rats, particularly the systolic blood pressure, whole blood viscosity (150/s), and LDL/HDL, were greater than those in hypertensive rats. In conclusion, CVD risk may increase with cold-air ranks. Blood pressure-induced CVD risk may be greater during cold-air temperature drop, whereas atherosclerosis-induced CVD risk may be greater after cold-air exposure. The effect of cold air on the CVD risk factors in healthy subjects may be more significant than those in hypertensive subjects.

  10. The Effect of Compressibility on the Pressure Reading of a Prandtl Pitot Tube at Subsonic Flow Velocity

    NASA Technical Reports Server (NTRS)

    Walchner, O

    1939-01-01

    Errors arising from yawed flow were also determined up to 20 degrees angle of attack. In axial flow, the Prandtl pitot tube begins at w/a approx. = 0.8 to give an incorrect static pressure reading, while it records the tank pressure correctly, as anticipated, up to sonic velocity. Owing to the compressibility of the air, the Prandtl pitot tube manifests compression shocks when the air speed approaches velocity of sound. This affects the pressure reading of the instrument. Because of the increasing importance of high speed in aviation, this compressibility effect is investigated in detail.

  11. The health effects of exercising in air pollution.

    PubMed

    Giles, Luisa V; Koehle, Michael S

    2014-02-01

    The health benefits of exercise are well known. Many of the most accessible forms of exercise, such as walking, cycling, and running often occur outdoors. This means that exercising outdoors may increase exposure to urban air pollution. Regular exercise plays a key role in improving some of the physiologic mechanisms and health outcomes that air pollution exposure may exacerbate. This problem presents an interesting challenge of balancing the beneficial effects of exercise along with the detrimental effects of air pollution upon health. This article summarizes the pulmonary, cardiovascular, cognitive, and systemic health effects of exposure to particulate matter, ozone, and carbon monoxide during exercise. It also summarizes how air pollution exposure affects maximal oxygen consumption and exercise performance. This article highlights ways in which exercisers could mitigate the adverse health effects of air pollution exposure during exercise and draws attention to the potential importance of land use planning in selecting exercise facilities. PMID:24174304

  12. Pressure-Sensitive Paint: Effect of Substrate

    PubMed Central

    Quinn, Mark Kenneth; Yang, Leichao; Kontis, Konstantinos

    2011-01-01

    There are numerous ways in which pressure-sensitive paint can be applied to a surface. The choice of substrate and application method can greatly affect the results obtained. The current study examines the different methods of applying pressure-sensitive paint to a surface. One polymer-based and two porous substrates (anodized aluminum and thin-layer chromatography plates) are investigated and compared for luminescent output, pressure sensitivity, temperature sensitivity and photodegradation. Two luminophores [tris-Bathophenanthroline Ruthenium(II) Perchlorate and Platinum-tetrakis (pentafluorophenyl) Porphyrin] will also be compared in all three of the substrates. The results show the applicability of the different substrates and luminophores to different testing environments. PMID:22247685

  13. 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

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum requirements. 84.157 Section 84.157 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY...

  14. 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.

  15. 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 demand class; minimum requirements. 84.149 Section 84.149 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES...

  16. Development of gas-pressure bonding process for air-cooled turbine blades

    NASA Technical Reports Server (NTRS)

    Meiners, K. E.

    1972-01-01

    An investigation was conducted on the application of gas-pressure bonding to the joining of components for convectively cooled turbine blades and vanes. A processing procedure was established for joining the fins of Udimet 700 and TD NiCr sheet metal airfoil shells to cast B1900 struts without the use of internal support tooling. Alternative methods employing support tooling were investigated. Testing procedures were developed and employed to determine shear strengths and internal burst pressures of flat and cylindrical bonded finned shell configurations at room temperature and 1750 F. Strength values were determined parallel and transverse to the cooling fin direction. The effect of thermal cycles from 1750 F to room temperature on strength was also investigated.

  17. 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.

  18. Development of a gas-promoted oil agglomeration process: Air-promoted oil agglomeration of moderately hydrophobic coals. 2: Effect of air dosage in a model mixing system

    SciTech Connect

    Drzymala, J.; Wheelock, T.D.

    1996-07-01

    In a selective oil agglomeration process for cleaning coal, fine-size particles are suspended in water and treated with a water-immiscible hydrocarbon which can range from pentane to heavy fuel oil. Vigorous agitation is applied to disperse the oil and to produce frequent contacts between oil-coated particles. In Part 1 of this series of papers, it was shown that a definite amount of air had to be present in a laboratory mixing unit which produced a moderate shear rate in order to form compact, spherical agglomerates in an aqueous suspension of moderately hydrophobic coal using heptane or hexadecane as an agglomerate. In this paper, the effects of different amounts of air including dissolved air are discussed. The results indicate that a small amount of air will trigger the process of agglomeration, and even the air dissolved in water under equilibrium conditions at room temperature and pressure is sufficient to promote agglomeration provided it is released from solution.

  19. Gas Phase Pressure Effects on the Apparent Thermal Conductivity of JSC-1A Lunar Regolith Simulant

    NASA Technical Reports Server (NTRS)

    Yuan, Zeng-Guang; Kleinhenz, Julie E.

    2011-01-01

    Gas phase pressure effects on the apparent thermal conductivity of a JSC-1A/air mixture have been experimentally investigated under steady state thermal conditions from 10 kPa to 100 kPa. The result showed that apparent thermal conductivity of the JSC-1A/air mixture decreased when pressure was lowered to 80 kPa. At 10 kPa, the conductivity decreased to 0.145 W/m/degree C, which is significantly lower than 0.196 W/m/degree C at 100 kPa. This finding is consistent with the results of previous researchers. The reduction of the apparent thermal conductivity at low pressures is ascribed to the Knudsen effect. Since the characteristic length of the void space in bulk JSC-1A varies over a wide range, both the Knudsen regime and continuum regime can coexist in the pore space. The volume ratio of the two regimes varies with pressure. Thus, as gas pressure decreases, the gas volume controlled by Knudsen regime increases. Under Knudsen regime the resistance to the heat flow is higher than that in the continuum regime, resulting in the observed pressure dependency of the apparent thermal conductivity.

  20. Carbon dioxide partial pressure and carbon fluxes of air-water interface in Taihu Lake, China

    NASA Astrophysics Data System (ADS)

    Fan, Chengxin; Hu, Weiping; Ford, Phillip W.; Chen, Yuwei; Qu, Wenchuan; Zhang, Lu

    2005-03-01

    To obtain carbon dioxide (CO2) flux between water-air interface of Taihu lake, monthly water samplers at 14 sites and the local meteorological data of the lake were collected and analyzed in 1998. Carbon dioxide partial pressures (pCO2) at air-water interface in the lake were calculated using alkalinity, pH, ionic strength, active coefficient, and water temperature. The carbon fluxes at different sublakes and areas were estimated by concentration gradient between water and air in consideration of Schmidt numbers of 600 and daily mean windspeed at 10 m above water surface. The results indicated that the mean values of pCO2 in Wuli Lake, Meiliang Bay, hydrophyte area, west littoral zone, riverine mouths, and the open lake areas were 1 807.8±1 071.4 (mean±standard deviation) μatm (1atm=1.013 25×105Pa), 416.3±217.0 μatm, 576.5±758.8 μatm, 304.2±243.5 μatm, 1 933.6±1 144.7 μatm, and 448.5±202.6 μatm, respectively. Maximum and minimum pCO2 values were found in the hypertrophic (4 053.7 μatm) and the eutrophic (3.2 μatm) areas. The riverine mouth areas have the maximum fluxes (82.0±62.8 mmol/m2a). But there was no significant difference between eutrophic and mesotrophic areas in pCO2 and the flux of CO2. The hydrophyte area, however, has the minimum (-0.58±12.9 mmol/m2a). In respect to CO2 equilibrium, input of the rivers will obviously influence inorganic carbon distribution in the riverine estuary. For example, the annual mean CO2 flux in Zhihugang River estuary was 19 times of that in Meiliang Bay, although the former is only a part of the latter. The sites in the body of the lake show a clear seasonal cycle with pCO2 higher than atmospheric equilibrium in winter, and much lower than atmospheric in summer due to CO2 consumption by photosynthesis. The CO2 amount of the net annual evasion that enters the atmosphere is 28.42×104 t/a, of which those from the west littoral zone and the open lake account for 53.8% and 36.7%, respectively.

  1. Vertical two-phase flow regimes and pressure gradients: Effect of viscosity

    SciTech Connect

    Da Hlaing, Nan; Sirivat, Anuvat; Siemanond, Kitipat; Wilkes, James O.

    2007-05-15

    The effect of liquid viscosity on the flow regimes and the corresponding pressure gradients along the vertical two-phase flow was investigated. Experiment was carried out in a vertical transparent tube of 0.019 m in diameter and 3 m in length and the pressure gradients were measured by a U-tube manometer. Water and a 50 vol.% glycerol solution were used as the working fluids whose kinematic viscosities were 0.85 x 10{sup -6} and 4.0 x 10{sup -6} m{sup 2}/s, respectively. In our air-liquid annular two-phase flow, the liquid film of various thicknesses flowed adjacent to the wall and the gas phase flowed at the center of the tube. The superficial air velocity, j{sub air}, was varied between 0.0021 and 58.7 m/s and the superficial liquid velocity, j{sub liquid}, was varied between 0 and 0.1053 m/s. In the bubble, the slug and the slug-churn flow regimes, the pressure gradients decreased with increasing Reynolds number. But in the annular and the mist flow regimes, pressure gradients increased with increasing Reynolds number. Finally, the experimentally measured pressure gradient values were compared and are in good agreement with the theoretical values. (author)

  2. AIR POLLUTION EFFECTS ON SEMEN QUALITY

    EPA Science Inventory

    The potential impact of exposure to periods of high air pollution on male reproductive health was examined within the framework of an international project conducted in the Czech Republic. Semen quality was evaluated in young men (age 18) living in the Teplice District who are ex...

  3. Pressure Effects in Droplet Combustion of Miscible Binary Fuels

    NASA Technical Reports Server (NTRS)

    Mikami, Masato; Habara, Osamu; Kono, Michikata; Sato, Jun-Ichi; Dietrich, Daniel L.; Williams, Forman A.

    1997-01-01

    The objective of this research is to improve understanding of the combustion of binary fuel mixtures in the vicinity of the critical point. Fiber-supported droplets of mixtures of n-heptane and n-hexadecane, initially 1 mm in diameter, were burned in room-temperature air at pressures from 1 MPa to 6 MPa under free-fall microgravity conditions. For most mixtures the total burning time was observed to achieve a minimum value at pressures well above the critical pressure of either of the pure fuels. This behavior is explained in terms of critical mixing conditions of a ternary system consisting of the two fuels and nitrogen. The importance of inert-gas dissolution in the liquid fuel near the critical point is thereby re-emphasized, and nonmonotonic dependence of dissolution on initial fuel composition is demonstrated. The results provide information that can be used to estimate high-pressure burning rates of fuel mixtures.

  4. Method transfer from high-pressure liquid chromatography to ultra-high-pressure liquid chromatography. II. Temperature and pressure effects.

    PubMed

    Åsberg, Dennis; Samuelsson, Jörgen; Leśko, Marek; Cavazzini, Alberto; Kaczmarski, Krzysztof; Fornstedt, Torgny

    2015-07-01

    The importance of the generated temperature and pressure gradients in ultra-high-pressure liquid chromatography (UHPLC) are investigated and compared to high-pressure liquid chromatography (HPLC). The drug Omeprazole, together with three other model compounds (with different chemical characteristics, namely uncharged, positively and negatively charged) were used. Calculations of the complete temperature profile in the column at UHPLC conditions showed, in our experiments, a temperature difference between the inlet and outlet of 16 °C and a difference of 2 °C between the column center and the wall. Through van't Hoff plots, this information was used to single out the decrease in retention factor (k) solely due to the temperature gradient. The uncharged solute was least affected by temperature with a decrease in k of about 5% while for charged solutes the effect was more pronounced, with k decreases up to 14%. A pressure increase of 500 bar gave roughly 5% increase in k for the uncharged solute, while omeprazole and the other two charged solutes gave about 25, 20 and 15% increases in k, respectively. The stochastic model of chromatography was applied to estimate the dependence of the average number of adsorption/desorption events (n) and the average time spent by a molecule in the stationary phase (τs) on temperature and pressure on peak shape for the tailing, basic solute. Increasing the temperature yielded an increase in n and decrease in τs which resulted in less skew at high temperatures. With increasing pressure, the stochastic modeling gave interesting results for the basic solute showing that the skew of the peak increased with pressure. The conclusion is that pressure effects are more pronounced for both retention and peak shape than the temperature effects for the polar or charged compounds in our study. PMID:26003622

  5. Students' Pressure, Time Management and Effective Learning

    ERIC Educational Resources Information Center

    Sun, Hechuan; Yang, Xiaolin

    2009-01-01

    Purpose: This paper aims to survey the status quo of the student pressure and the relationship between their daily time management and their learning outcomes in three different types of higher secondary schools at Shenyang, the capital city of Liaoning Province in mainland China. Design/methodology/approach: An investigation was carried out in 14…

  6. Building America Case Study: Ventilation System Effectiveness and Tested Indoor Air Quality Impacts, Tyler, Texas

    SciTech Connect

    2015-08-01

    ?Ventilation system effectiveness testing was conducted at two unoccupied, single-family, detached lab homes at the University of Texas - Tyler. Five ventilation system tests were conducted with various whole-building ventilation systems. Multizone fan pressurization testing characterized building and zone enclosure leakage. PFT testing showed multizone air change rates and interzonal airflow filtration. Indoor air recirculation by a central air distribution system can help improve the exhaust ventilation system by way of air mixing and filtration. In contrast, the supply and balanced ventilation systems showed that there is a significant benefit to drawing outside air from a known outside location, and filtering and distributing that air. Compared to the Exhaust systems, the CFIS and ERV systems showed better ventilation air distribution and lower concentrations of particulates, formaldehyde and other VOCs. System improvement percentages were estimated based on four System Factor Categories: Balance, Distribution, Outside Air Source, and Recirculation Filtration. Recommended System Factors could be applied to reduce ventilation fan airflow rates relative to ASHRAE Standard 62.2 to save energy and reduce moisture control risk in humid climates. HVAC energy savings were predicted to be 8-10%, or $50-$75/year. Cumulative particle counts for six particle sizes, and formaldehyde and other Top 20 VOC concentrations were measured in multiple zones. The testing showed that single-point exhaust ventilation was inferior as a whole-house ventilation strategy.

  7. X-ray radiation from the volume discharge in atmospheric-pressure air

    NASA Astrophysics Data System (ADS)

    Bratchikov, V. B.; Gagarinov, K. A.; Kostyrya, I. D.; Tarasenko, V. F.; Tkachev, A. N.; Yakovlenko, S. I.

    2007-07-01

    X-ray radiation from the volume discharge in atmospheric-pressure air is studied under the conditions when the voltage pulse rise time varies from 0.5 to 100 ns and the open-circuit voltage amplitude of the generator varies from 20 to 750 kV. It is shown that a volume discharge from a needle-like cathode forms at a relatively wide voltage pulse (to ≈60 ns in this work). The volume character of the discharge is due to preionization by fast electrons, which arise when the electric field concentrates at the cathode and in the discharge gap. As the voltage pulse rise time grows, X-ray radiation comes largely from the discharge gap in accordance with previous experiments. Propagation of fast avalanche electrons in nitrogen subjected to a nonuniform unsteady electric field is simulated. It is demonstrated that the amount of hard X-ray photons grows not only with increasing voltage amplitude but also with shortening pulse rise time.

  8. 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.

  9. 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.

  10. Electrode Erosion in Pulsed Arc for Generating Air Meso-Plasma Jet under Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Shiki, Hajime; Motoki, Junpei; Takikawa, Hirofumi; Sakakibara, Tateki; Nishimura, Yoshimi; Hishida, Shigeji; Okawa, Takashi; Ootsuka, Takeshi

    Various materials of the rod electrode were examined in pulsed arc of PEN-Jet (Plasma ENergized-Jet) with working gas of air, which can be used for the surface treatment under atmospheric pressure. The erosion of the rod electrode was measured and it surface was observed. The amount of erosion and surface appearance were found to be different for the materials, input power and energizing time. Tungsten (W) rod electrode was oxidized immediately after starting the discharge and tungsten oxide (WO3) powder was generated over the side surface of electrode tip. This powder contaminated the treating surface. Copper (Cu) rod electrode was also oxidized immediately and CuO/Cu2O multi-layer was formed on the electrode surface. However, the erosion of Cu electrode was quite small. Platinum (Pt) and iridium (20 wt%)-contained-platinum (Pt-Ir) rod electrode were not oxidized and their erosions were significantly small. This indicated that they could be employed for keeping the constant electrode-gap and processing the surface treatment without contamination due to electrode erosion.

  11. 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.

  12. 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.

  13. Pressure Relief, Visco-Elastic Foam with Inflated Air? A Pilot Study in a Dutch Nursing Home

    PubMed Central

    Van Leen, Martin; Schols, Jos

    2015-01-01

    Objective: There is still little evidence regarding the type of mattress that is the best for preventing pressure ulcers (PUs). In a Dutch nursing home, a new type of overlay mattress (air inflated visco-elastic foam) was tested to analyze the opportunity for replacement of the normally used static air overlay mattress in its three-step PU prevention protocol In this small pilot the outcome measures were: healing of a category one pressure ulcer, new development or deterioration of a category one PU and need for repositioning. Methods: We included 20 nursing home residents with a new category one pressure ulcer, existing for no longer than 48 h following a consecutive sampling technic. All residents were staying for more than 30 days in the nursing home and were lying on a visco-elastic foam mattress without repositioning (step one of the 3-step protocol) at the start of the pilot study. They had not suffered from a PU in the month before. The intervention involved use of an air inflated foam overlay instead of a static air overlay (normally step 2 of the 3-step protocol). At the start; the following data were registered: age; gender; main diagnosis and presence of incontinence. Thereafter; all participating residents were checked weekly for PU healing tendency; deterioration of PUs; new PUs and need of repositioning. Only when residents showed still a category one PU after 48 h or deterioration of an existing pressure ulcer or if there was development of a new pressure ulcer, repositioning was put into practice (step 3 of the PU protocol). All residents participated during 8 weeks. Results: Seven residents developed a new pressure ulcer category one and still had a category one pressure ulcer at the end of the study period. One resident developed a pressure ulcer category 2. Fifteen residents needed repositioning from one week after start of the study until the end of the study. Conclusions: Overall 40% of the residents developed a pressure ulcer. Seventy five

  14. Blood Pressure and Same-Day Exposure to Air Pollution at School: Associations with Nano-Sized to Coarse PM in Children

    PubMed Central

    Pieters, Nicky; Koppen, Gudrun; Van Poppel, Martine; De Prins, Sofie; Cox, Bianca; Dons, Evi; Nelen, Vera; Panis, Luc Int; Plusquin, Michelle; Schoeters, Greet

    2015-01-01

    Background Ultrafine particles (UFP) may contribute to the cardiovascular effects of particulate air pollution, partly because of their relatively efficient alveolar deposition. Objective In this study, we assessed associations between blood pressure and short-term exposure to air pollution in a population of schoolchildren. Methods In 130 children (6–12 years of age), blood pressure was determined during two periods (spring and fall 2011). We used mixed models to study the association between blood pressure and ambient concentrations of particulate matter and ultrafine particles measured in the schools’ playground. Results Independent of sex, age, height, and weight of the child, parental education, neighborhood socioeconomic status, fish consumption, heart rate, school, day of the week, season, wind speed, relative humidity, and temperature on the morning of examination, an interquartile range (860 particles/cm3) increase in nano-sized UFP fraction (20–30 nm) was associated with a 6.35 mmHg (95% CI: 1.56, 11.14; p = 0.01) increase in systolic blood pressure. For the total UFP fraction, systolic blood pressure was 0.79 mmHg (95% CI: 0.07, 1.51; p = 0.03) higher, but no effects on systolic blood pressure were found for the nano-sized fractions with a diameter > 100 nm, nor PM2.5, PMcoarse, and PM10. Diastolic blood pressure was not associated with any of the studied particulate mass fractions. Conclusion Children attending school on days with higher UFP concentrations (diameter < 100 nm) had higher systolic blood pressure. The association was dependent on UFP size, and there was no association with the PM2.5 mass concentration. Citation Pieters N, Koppen G, Van Poppel M, De Prins S, Cox B, Dons E, Nelen V, Int Panis L, Plusquin M, Schoeters G, Nawrot TS. 2015. Blood pressure and same-day exposure to air pollution at school: associations with nano-sized to coarse PM in children. Environ Health Perspect 123:737–742; http://dx.doi.org/10.1289/ehp.1408121

  15. Atmospheric effects on extensive air showers observed with the surface detector of the Pierre Auger observatory

    NASA Astrophysics Data System (ADS)

    Pierre Auger Collaboration; Abraham, J.; Abreu, P.; Aglietta, M.; Aguirre, C.; Ahn, E. J.; Allard, D.; Allekotte, I.; Allen, J.; Allison, P.; Alvarez-Muñiz, J.; Ambrosio, M.; Anchordoqui, L.; Andringa, S.; Anzalone, A.; Aramo, C.; Arganda, E.; Argirò, S.; Arisaka, K.; Arneodo, F.; Arqueros, F.; Asch, T.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avila, G.; Bäcker, T.; Badagnani, D.; Barber, K. B.; Barbosa, A. F.; Barroso, S. L. C.; Baughman, B.; Bauleo, P.; Beatty, J. J.; Beau, T.; Becker, B. R.; Becker, K. H.; Bellétoile, A.; Bellido, J. A.; Benzvi, S.; Berat, C.; Bernardini, P.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanch-Bigas, O.; Blanco, F.; Bleve, C.; Blümer, H.; Boháčová, M.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brogueira, P.; Brown, W. C.; Bruijn, R.; Buchholz, P.; Bueno, A.; Burton, R. E.; Busca, N. G.; Caballero-Mora, K. S.; Caramete, L.; Caruso, R.; Carvalho, W.; Castellina, A.; Catalano, O.; Cazon, L.; Cester, R.; Chauvin, J.; Chiavassa, A.; Chinellato, J. A.; Chou, A.; Chudoba, J.; Chye, J.; Clay, R. W.; Colombo, E.; Conceição, R.; Connolly, B.; Contreras, F.; Coppens, J.; Cordier, A.; Cotti, U.; Coutu, S.; Covault, C. E.; Creusot, A.; Criss, A.; Cronin, J.; Curutiu, A.; Dagoret-Campagne, S.; Dallier, R.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; de Domenico, M.; de Donato, C.; de Jong, S. J.; de La Vega, G.; de Mello, W. J. M.; de Mello Neto, J. R. T.; de Mitri, I.; de Souza, V.; de Vries, K. D.; Decerprit, G.; Del Peral, L.; Deligny, O.; Della Selva, A.; Delle Fratte, C.; Dembinski, H.; di Giulio, C.; Diaz, J. C.; Diep, P. N.; Dobrigkeit, C.; D'Olivo, J. C.; Dong, P. N.; Dornic, D.; Dorofeev, A.; Dos Anjos, J. C.; Dova, M. T.; D'Urso, D.; Dutan, I.; Duvernois, M. A.; Engel, R.; Erdmann, M.; Escobar, C. O.; Etchegoyen, A.; Facal San Luis, P.; Falcke, H.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferrer, F.; Ferrero, A.; Fick, B.; Filevich, A.; Filipčič, A.; Fleck, I.; Fliescher, S.; Fracchiolla, C. E.; Fraenkel, E. D.; Fulgione, W.; Gamarra, R. F.; Gambetta, S.; García, B.; García Gámez, D.; Garcia-Pinto, D.; Garrido, X.; Gelmini, G.; Gemmeke, H.; Ghia, P. L.; Giaccari, U.; Giller, M.; Glass, H.; Goggin, L. M.; Gold, M. S.; Golup, G.; Gomez Albarracin, F.; Gómez Berisso, M.; Gonçalves, P.; Gonçalves Do Amaral, M.; Gonzalez, D.; Gonzalez, J. G.; Góra, D.; Gorgi, A.; Gouffon, P.; Grashorn, E.; Grebe, S.; Grigat, M.; Grillo, A. F.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Gutiérrez, J.; Hague, J. D.; Halenka, V.; Hansen, P.; Harari, D.; Harmsma, S.; Harton, J. L.; Haungs, A.; Healy, M. D.; Hebbeker, T.; Hebrero, G.; Heck, D.; Hojvat, C.; Holmes, V. C.; Homola, P.; Hörandel, J. R.; Horneffer, A.; Hrabovský, M.; Huege, T.; Hussain, M.; Iarlori, M.; Insolia, A.; Ionita, F.; Italiano, A.; Jiraskova, S.; Kaducak, M.; Kampert, K. H.; Karova, T.; Kasper, P.; Kégl, B.; Keilhauer, B.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapik, R.; Knapp, J.; Koang, D.-H.; Krieger, A.; Krömer, O.; Kruppke-Hansen, D.; Kuempel, D.; Kunka, N.; Kusenko, A.; La Rosa, G.; Lachaud, C.; Lago, B. L.; Lautridou, P.; Leão, M. S. A. B.; Lebrun, D.; Lebrun, P.; Lee, J.; Leigui de Oliveira, M. A.; Lemiere, A.; Letessier-Selvon, A.; Leuthold, M.; Lhenry-Yvon, I.; López, R.; Lopez Agüera, A.; Louedec, K.; Lozano Bahilo, J.; Lucero, A.; Luna García, R.; Lyberis, H.; Maccarone, M. C.; Macolino, C.; Maldera, S.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Maris, I. C.; Marquez Falcon, H. R.; Martello, D.; Martínez, J.; Martínez Bravo, O.; Mathes, H. J.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurizio, D.; Mazur, P. O.; McEwen, M.; McNeil, R. R.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Meyhandan, R.; Micheletti, M. I.; Miele, G.; Miller, W.; Miramonti, L.; Mollerach, S.; Monasor, M.; Monnier Ragaigne, D.; Montanet, F.; Morales, B.; Morello, C.; Moreno, J. C.; Morris, C.; Mostafá, M.; Moura, C. A.; Mueller, S.; Muller, M. A.; Mussa, R.; Navarra, G.; Navarro, J. L.; Navas, S.; Necesal, P.; Nellen, L.; Newman-Holmes, C.; Newton, D.; Nhung, P. T.; Nierstenhoefer, N.; Nitz, D.; Nosek, D.; Nožka, L.; Nyklicek, M.; Oehlschläger, J.; Olinto, A.; Oliva, P.; Olmos-Gilbaja, V. M.; Ortiz, M.; Ortolani, F.; Pacheco, N.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Parente, G.; Parizot, E.; Parlati, S.; Pastor, S.; Patel, M.; Paul, T.; Pavlidou, V.; Payet, K.; Pech, M.; PeĶala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Pesce, R.; Petermann, E.; Petrera, S.; Petrinca, P.; Petrolini, A.; Petrov, Y.; Petrovic, J.; Pfendner, C.; Piegaia, R.; Pierog, T.; Pimenta, M.; Pinto, T.; Pirronello, V.; Pisanti, O.; Platino, M.; Pochon, J.; Ponce, V. H.; Pontz, M.; Privitera, P.; Prouza, M.; Quel, E. J.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Redondo, A.; Reucroft, S.; Revenu, B.; Rezende, F. A. S.; Ridky, J.; Riggi, S.; Risse, M.; Rivière, C.; Rizi, V.; Robledo, C.; Rodriguez, G.; Rodriguez Martino, J.; Rodriguez Rojo, J.; Rodriguez-Cabo, I.; Rodríguez-Frías, M. D.; Ros, G.; Rosado, J.; Rossler, T.; Roth, M.; Rouillé-D'Orfeuil, A.; Roulet, E.; Rovero, A. C.; Salamida, F.; Salazar, H.; Salina, G.; Sánchez, F.; Santander, M.; Santo, C. E.; Santos, E. M.; Sarazin, F.; Sarkar, S.; Sato, R.; Scharf, N.; Scherini, V.; Schieler, H.; Schiffer, P.; Schmidt, A.; Schmidt, F.; Schmidt, T.; Scholten, O.; Schoorlemmer, H.; Schovancova, J.; Schovánek, P.; Schroeder, F.; Schulte, S.; Schüssler, F.; Schuster, D.; Sciutto, S. J.; Scuderi, M.; Segreto, A.; Semikoz, D.; Settimo, M.; Shellard, R. C.; Sidelnik, I.; Siffert, B. B.; Smiałkowski, A.; Šmída, R.; Smith, B. E.; Snow, G. R.; Sommers, P.; Sorokin, J.; Spinka, H.; Squartini, R.; Strazzeri, E.; Stutz, A.; Suarez, F.; Suomijärvi, T.; Supanitsky, A. D.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Tamashiro, A.; Tamburro, A.; Tarutina, T.; Taşcău, O.; Tcaciuc, R.; Tcherniakhovski, D.; Thao, N. T.; Thomas, D.; Ticona, R.; Tiffenberg, J.; Timmermans, C.; Tkaczyk, W.; Todero Peixoto, C. J.; Tomé, B.; Tonachini, A.; Torres, I.; Travnicek, P.; Tridapalli, D. B.; Tristram, G.; Trovato, E.; Tuci, V.; Tueros, M.; Ulrich, R.; Unger, M.; Urban, M.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van den Berg, A. M.; Vázquez, J. R.; Vázquez, R. A.; Veberič, D.; Velarde, A.; Venters, T.; Verzi, V.; Videla, M.; Villaseñor, L.; Vorobiov, S.; Voyvodic, L.; Wahlberg, H.; Wahrlich, P.; Wainberg, O.; Warner, D.; Watson, A. A.; Westerhoff, S.; Whelan, B. J.; Wieczorek, G.; Wiencke, L.; Wilczyńska, B.; Wilczyński, H.; Wileman, C.; Winnick, M. G.; Wu, H.; Wundheiler, B.; Yamamoto, T.; Younk, P.; Yuan, G.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zaw, I.; Zepeda, A.; Ziolkowski, M.

    2009-09-01

    Atmospheric parameters, such as pressure (P), temperature (T) and density (ρ∝P/T), affect the development of extensive air showers initiated by energetic cosmic rays. We have studied the impact of atmospheric variations on extensive air showers by means of the surface detector of the Pierre Auger Observatory. The rate of events shows a ˜10% seasonal modulation and ˜2% diurnal one. We find that the observed behaviour is explained by a model including the effects associated with the variations of P and ρ. The former affects the longitudinal development of air showers while the latter influences the Molière radius and hence the lateral distribution of the shower particles. The model is validated with full simulations of extensive air showers using atmospheric profiles measured at the site of the Pierre Auger Observatory.

  16. Blood pressure monitor with a position sensor for wrist placement to eliminate hydrostatic pressure effect on blood pressure measurement.

    PubMed

    Sato, Hironori; Koshimizu, Hiroshi; Yamashita, Shingo; Ogura, Toshihiko

    2013-01-01

    Accurate measurement of blood pressure at wrist requires the heart and wrist to be kept at the same level to avoid the effects of hydrostatic pressure. Although a blood pressure monitor with a position sensor that guides appropriate forearm angle without use of a chair and desk has already been proposed, a similar functioning device for measuring upper arm blood pressure with a chair and desk is needed. In this study, a calculation model was first used to explore design of such a system. The findings were then implemented into design of a new blood pressure monitor. Results of various methods were compared. The calculation model of the wrist level from arthrosis angles and interarticulars lengths was developed and considered using published anthropometric dimensions. It is compared with 33 volunteer persons' experimental results. The calculated difference of level was -4.1 to 7.9 (cm) with a fixed chair and desk. The experimental result was -3.0 to 5.5 (cm) at left wrist and -2.1 to 6.3(cm) at right wrist. The absolute difference level equals ±4.8 (mmHg) of blood pressure readings according to the calculated result. This meets the AAMI requirements for a blood pressure monitor. In the conclusion, the calculation model is able to effectively evaluate the difference between the heart and wrist level. Improving the method for maintaining wrist to heart level will improve wrist blood pressure measurement accuracy when also sitting in the chair at a desk. The leading angle of user's forearm using a position sensor is shown to work for this purpose. PMID:24110067

  17. Membrane air-stripping: Effects of pretreatment

    SciTech Connect

    Castro, K. ); Zander, A.K. . Dept. of Civil and Environmental Engineering)

    1995-03-01

    As a result of the Safe Drinking Water Act and its 1986 amendments, the number of regulated volatile organic chemicals (VOCs) has increased substantially. The discovery of drinking water supply sources contaminated by VOCs is also increasing. These factors have led to the development of alternative treatment methods for control of VOCs. Microporous polypropylene hollow-fiber membranes offer significant advantages over packed-tower aeration for removing volatile organic chemicals. A laboratory study assessed the performance of membrane air-stripping in continuous operation, while exposed to various pretreatments. Results indicate that membrane air-stripping is compatible with low-pH or low-chlorine waters but not with waters of high pH or high-chlorine concentration or those that are ozonated.

  18. Effects of air cavity on fly-ear inspired directional microphones: a numerical study

    NASA Astrophysics Data System (ADS)

    Liu, Haijun; Yu, Miao

    2011-04-01

    The superacute ear of the parasitoid fly Ormia ochracea has inspired the development of a variety of novel miniature directional microphones for sound source localization, in which the effects of air cavity backing the eardrums are often neglected without validation. In the original testing on the fly ear, the integrity of the air space is shown not to be the key to the intertympnal coupling. However, it does not necessarily mean that the tympanum can be treated as in vacuo, and the effects of the air cavity backing the eardrums have yet to be fully understood. In this article, a normalized version of our previous model of air-backed circular membranes is derived to study the conditions under which the air cavity can be indeed neglected. This model is then used to study a fly-ear inspired directional microphone design with two clamped circular membranes mechanically coupled by a bridge. The performance of the directional microphone with air cavity is evaluated in comparison to its counterpart in vacuo. This article not only provides more insights into the fly ear phenomena, but builds a theoretical foundation on whether and how to take the air cavity into account in the design of pressure sensors and directional microphones in general.

  19. Effect of pressurization on antibacterial properties of Lactobacillus strains

    NASA Astrophysics Data System (ADS)

    Jankowska, Agnieszka; Grześkiewicz, Aleksandra; Wiśniewska, Krystyna; Reps, Arnold

    2010-03-01

    The objective of the study was to determine the effect of high pressures on antibacterial properties of selected strains of the Lactobacillus species. Cultures of 22 strains were subjected to high-pressure treatment at 30, 60, 90, and 300 MPa/1 min/18 °C. The susceptibility of the bacteria pressurized at 30-90 MPa was diversified and depended on the strain and not on its species affiliation. When compared with pressures of 30-90 MPa, the pressure treatment at 300 MPa caused the inhibition of the acidifying activity of the strains analyzed. In turn, the pressures applied had no impact on the quantity of hydrogen peroxide synthesized. An increase in pressure was accompanied by a diminishing antibacterial activity of the investigated Lactobacillus strains.

  20. 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

  1. The effect of nutrition on blood pressure.

    PubMed

    Savica, Vincenzo; Bellinghieri, Guido; Kopple, Joel D

    2010-08-21

    The incidence and severity of hypertension are affected by nutritional status and intake of many nutrients. Excessive energy intake and obesity are major causes of hypertension. Obesity is associated with increased activity of the renin-angiotensin-aldosterone and sympathetic nervous systems, possibly other mineralcorticoid activity, insulin resistance, salt-sensitive hypertension and excess salt intake, and reduced kidney function. High sodium chloride intake strongly predisposes to hypertension. Increased alcohol consumption may acutely elevate blood pressure. High intakes of potassium, polyunsaturated fatty acids, and protein, along with exercise and possibly vitamin D, may reduce blood pressure. Less-conclusive studies suggest that amino acids, tea, green coffee bean extract, dark chocolate, and foods high in nitrates may reduce blood pressure. Short-term studies indicate that specialized diets may prevent or ameliorate mild hypertension; most notable are the Dietary Approaches to Stop Hypertension (DASH) diet, which is high in fruits, vegetables, and low-fat dairy products, and the DASH low-sodium diet. Long-term compliance to these diets remains a major concern. PMID:20645853

  2. Peripheral vascular effects on auscultatory blood pressure measurement.

    PubMed

    Rabbany, S Y; Drzewiecki, G M; Noordergraaf, A

    1993-01-01

    Experiments were conducted to examine the accuracy of the conventional auscultatory method of blood pressure measurement. The influence of the physiologic state of the vascular system in the forearm distal to the site of Korotkoff sound recording and its impact on the precision of the measured blood pressure is discussed. The peripheral resistance in the arm distal to the cuff was changed noninvasively by heating and cooling effects and by induction of reactive hyperemia. All interventions were preceded by an investigation of their effect on central blood pressure to distinguish local effects from changes in central blood pressure. These interventions were sufficiently moderate to make their effect on central blood pressure, recorded in the other arm, statistically insignificant (i.e., changes in systolic [p < 0.3] and diastolic [p < 0.02]). Nevertheless, such alterations were found to modify the amplitude of the Korotkoff sound, which can manifest itself as an apparent change in arterial blood pressure that is readily discerned by the human ear. The increase in diastolic pressure for the cooling experiments was statistically significant (p < 0.001). Moreover, both measured systolic (p < 0.004) and diastolic (p < 0.001) pressure decreases during the reactive hyperemia experiments were statistically significant. The findings demonstrate that alteration in vascular state generates perplexing changes in blood pressure, hence confirming experimental observations by earlier investigators as well as predictions by our model studies. PMID:8463815

  3. Which ornamental plant species effectively remove benzene from indoor air?

    NASA Astrophysics Data System (ADS)

    Liu, Yan-Ju; Mu, Yu-Jing; Zhu, Yong-Guan; Ding, Hui; Crystal Arens, Nan

    Phytoremediation—using plants to remove toxins—is an attractive and cost effective way to improve indoor air quality. This study screened ornamental plants for their ability to remove volatile organic compounds from air by fumigating 73 plant species with 150 ppb benzene, an important indoor air pollutant that poses a risk to human health. The 10 species found to be most effective at removing benzene from air were fumigated for two more days (8 h per day) to quantify their benzene removal capacity. Crassula portulacea, Hydrangea macrophylla, Cymbidium Golden Elf., Ficus microcarpa var. fuyuensis, Dendranthema morifolium, Citrus medica var. sarcodactylis, Dieffenbachia amoena cv. Tropic Snow; Spathiphyllum Supreme; Nephrolepis exaltata cv. Bostoniensis; Dracaena deremensis cv. Variegata emerged as the species with the greatest capacity to remove benzene from indoor air.

  4. 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.

  5. Isolating Gas Sensor From Pressure And Temperature Effects

    NASA Technical Reports Server (NTRS)

    Sprinkle, Danny R.; Chen, Tony T. D.; Chaturvedi, Sushi K.

    1994-01-01

    Two-stage flow system enables oxygen sensor in system to measure oxygen content of low-pressure, possibly-high-temperature atmosphere in test environment while protecting sensor against possibly high temperature and fluctuations in pressure of atmosphere. Sensor for which flow system designed is zirconium oxide oxygen sensor sampling atmospheres in high-temperature wind tunnels. Also adapted to other gas-analysis instruments that must be isolated from pressure and temperature effects of test environments.

  6. Effective anisotropy gradient in pressure graded [Co/Pd] multilayers

    SciTech Connect

    Kirby, B. J. Maranville, B. B.; Greene, P. K.; Liu, Kai; Davies, J. E.

    2015-02-14

    We have used polarized neutron reflectometry to show that controlled variation of growth pressure during deposition of Co/Pd multilayers can be used to achieve a significant vertical gradient in the effective anisotropy. This gradient is strongly dependent on deposition order (low to high pressure or vice versa), and is accompanied by a corresponding gradient in saturation magnetization. These results demonstrate pressure-grading as an attractively simple technique for tailoring the anisotropy profile of magnetic media.

  7. Effect of flameholder pressure drop on emissions and performance of premixed-prevaporized combustors

    NASA Technical Reports Server (NTRS)

    Duerr, R. A.; Lyons, V. J.

    1983-01-01

    Parametric tests were conducted to determine the effects of flameholder pressure drop on the emissions and performance of lean premixed-prevaporized combustors. A conical flameholder mounted in a diverging duct was tested with two values of flameholder blockage. Emissions of nitrogen oxides, carbon monoxide, carbon dioxide, and unburned hydrocarbons were measured for combustor entrance conditions of 600 to 800 K air temperature, 0.3 MPa to 0.5 MPa pressure, and 20 m/sec to 35 m/sec reference velocity. Jet A fuel was injected at flow rates corresponding to an equivalence ratio range from 0.8 down to the lean stability limit. Emission results for the high-blockage flameholder were a substantial improvement over the low-blockage emission results. A correlation of combustion efficiency with flameholder pressure drop was developed for pressure drops less than 9 percent.

  8. Experimental Study on Effects of Frequency and Mean Pressure on Heat Pumping by Acoustic Oscillation

    NASA Astrophysics Data System (ADS)

    Kawamoto, Akira; Ozawa, Mamoru; Kataoka, Masaki; Takifuji, Tomonari

    Experimental studies were conducted for the fundamental understanding of the thermoacoustic behavior in the simulated resonance-tube refrigerator with special reference to the effect of imposed frequency and mean pressure. The resonance frequency in the case of helium was lower by about 20% than the theoretical prediction, while the experimental value in the case of air was almost the same as the theoretical one. The temperature difference observed along the stack increased with the increase in the amplitude of acoustic pressure, and decreased with the increase in the mean pressure, Based on the simplified model of heat pumping process, the relationship between the temperature variation and the acoustic pressure field was formulated, and thus the characteristic parameter which represents overall heat transfer between gas and stack plates or heat exchangers was obtained.

  9. Effect of Initial Mixture Temperature on Flame Speed of Methane-Air, Propane-Air, and Ethylene-Air Mixtures

    NASA Technical Reports Server (NTRS)

    Dugger, Gordon L

    1952-01-01

    Flame speeds based on the outer edge of the shadow cast by the laminar Bunsen cone were determined as functions of composition for methane-air mixtures at initial mixture temperatures ranging from -132 degrees to 342 degrees c and for propane-air and ethylene-air mixtures at initial mixture temperatures ranging from -73 degrees to 344 degrees c. The data showed that maximum flame speed increased with temperature at an increasing rate. The percentage change in flame speed with change in initial temperature for the three fuels followed the decreasing order, methane, propane, and ethylene. Empirical equations were determined for maximum flame speed as a function of initial temperature over the temperature range covered for each fuel. The observed effect of temperature on flame speed for each of the fuels was reasonably well predicted by either the thermal theory as presented by Semenov or the square-root law of Tanford and Pease.

  10. Effect of osmolytes on pressure-induced unfolding of proteins: a high-pressure SAXS study.

    PubMed

    Krywka, Christina; Sternemann, Christian; Paulus, Michael; Tolan, Metin; Royer, Catherine; Winter, Roland

    2008-12-22

    Herein, we explore the effect of different types of osmolytes on the high-pressure stability and tertiary structure of a well-characterized monomeric protein, staphylococcal nuclease (SNase). Changes in the denaturation pressure and the radius of gyration are obtained in the presence of different concentrations of trimethylamine N-oxide (TMAO), glycerol and urea. To reveal structural changes in the protein upon compression at various osmolyte conditions, small-angle X-ray scattering (SAXS) experiments were carried out. To this end, a new high-pressure cell suitable for high-precision SAXS studies at synchrotron sources was built, which allows one to carry out scattering experiments up to maximum pressures of about 7 kbar. Our data clearly indicate that the osmolytes that stabilize proteins against temperature-induced unfolding drastically increase their pressure stability and that the elliptically shaped curve of the pressure-temperature-stability diagram of proteins is shifted to higher temperatures and pressures with increasing osmolyte concentration. A drastic stabilization is observed for the osmolyte TMAO, which exhibits not only a significant stabilization against temperature-induced unfolding, but also a particularly strong stabilization of the protein against pressure. In fact, such findings are in accordance with in vivo studies (for example P. J. Yancey, J. Exp. Biol. 2005, 208, 2819-2830), where unusually high TMAO concentrations in some deep-sea animals were found. Conversely, chaotropic agents such as urea have a strong destabilizing effect on both the temperature and pressure stability of the protein. Our data also indicate that sufficiently high TMAO concentrations might be able to largely offset the destabilizing effect of urea. The different scenarios observed are discussed in the context of recent experimental and theoretical studies. PMID:18924198

  11. 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. PMID:25907963

  12. Personal Black Carbon Exposure Influences Ambulatory Blood Pressure: Air Pollution and Cardio-metabolic Disease (AIRCMD-China) Study

    PubMed Central

    Zhao, Xiaoyi; Sun, Zhichao; Ruan, Yanping; Yan, Jianhua; Mukherjee, Bhramar; Yang, Fumo; Duan, Fengkui; Sun, Lixian; Liang, Ruijuan; Lian, Hui; Zhang, Shuyang; Fang, Quan; Gu, Dongfeng; Brook, Jeffrey R.; Sun, Qinghua; Brook, Robert D.; Rajagopalan, Sanjay; Fan, Zhongjie

    2015-01-01

    Few prospective studies have assessed the blood pressure impact of extremely high air pollution encountered in Asia’s megacities. The objective of this study was to evaluate the association between combustion-related air pollution with ambulatory blood pressure and autonomic function. During February to July 2012, personal black carbon was determined for 5 consecutive days using microaethelometers in patients with metabolic syndrome in Beijing, China. Simultaneous ambient fine particulate matter concentration was obtained from the Beijing Municipal Environmental Monitoring Center and the U.S. Embassy. 24-hour ambulatory blood pressure and heart rate variability were measured from Day 4. Arterial stiffness and endothelial function were obtained at the end of Day 5. For statistical analysis, we used generalized additive mixed models for repeated outcomes and generalized linear models for single/summary outcomes. Mean (standard deviation) of personal black carbon and fine particulate matter over 24-hour was 4.66 (2.89) and 64.2 (36.9) μg/m3. Exposure to high levels of black carbon in the preceding hours was significantly associated with adverse cardiovascular responses. A unit increase in personal black carbon over the previous 10 hours was associated with an increase in systolic blood pressure of 0.53 mmHg and diastolic blood pressure of 0.37 mmHg (95% confidence interval, 0.17-0.89 and 0.10-0.65 mmHg, respectively), a percent change in low frequency to high frequency ratio of 5.11 and mean inter-beat interval of −0.06 (95% confidence interval, 0.62 to 9.60 and −0.11 to −0.01, respectively). These findings highlight the public health impact of air pollution and the importance of reducing air pollution. PMID:24420543

  13. Investigating the Effects of Traffic on Air Pollution.

    ERIC Educational Resources Information Center

    Taylor, Sharon

    2001-01-01

    Discusses the benefits of bringing scientists into the classroom to collaborate with children on environmental research projects. Describes one collaborative project that focused on the effects of traffic on air pollution. (DDR)

  14. Soft electrostatic repulsion in particle monolayers at liquid interfaces: surface pressure and effect of aggregation.

    PubMed

    Kralchevsky, Peter A; Danov, Krassimir D; Petkov, Plamen V

    2016-07-28

    Non-densely packed interfacial monolayers from charged micrometre-sized colloid particles find applications for producing micropatterned surfaces. The soft electrostatic repulsion between the particles in a monolayer on an air/water (or oil/water) interface is mediated by the non-polar fluid, where Debye screening is absent and the distances between the particles are considerably greater than their diameters. Surface pressure versus area isotherms were measured at the air/water interface. The experiments show that asymptotically the surface pressure is inversely proportional to the third power of the interparticle distance. A theoretical model is developed that predicts not only the aforementioned asymptotic law but also the whole surface pressure versus area dependence. An increase in the surface pressure upon aggregation of charged particles in the interfacial monolayers is experimentally established. This effect is explained by the developed theoretical model, which predicts that the surface pressure should linearly increase with the square root of the particle mean aggregation number. The effect of added electrolyte on the aggregation is also investigated. The data lead to the conclusion that 'limited aggregation' exists in the monolayers of charged particles. In brief, the stronger electrostatic repulsion between the bigger aggregates leads to a higher barrier to their coalescence that, in turn, prevents any further aggregation, i.e. negative feedback is present.This article is part of the themed issue 'Soft interfacial materials: from fundamentals to formulation'. PMID:27298437

  15. The effect of pressure on annular flow pressure drop in a small pipe

    SciTech Connect

    de Bertodano, M.A.L.; Beus, S.G.; Shi, Jian-Feng

    1996-09-01

    New experimental data was obtained for pressure drop and entrainment for annular up-flow in a vertical pipe. The 9.5 mm. pipe has an L/D ratio of 440 to insure fully developed annular flow. The pressure ranged from 140 kPa to 660 kPa. Therefore the density ratio was varied by a factor of four approximately. This allows the investigation of the effect of pressure on the interfacial shear models. Gas superficial velocities between 25 and 126 m/s were tested. This extends the range of previous data to higher gas velocities. The data were compared with well known models for interfacial shear that represent the state of the art. Good results were obtained when the model by Asali, Hanratty and Andreussi was modified for the effect of pressure. Furthermore an equivalent model was obtained based on the mixing length theory for rough pipes. It correlates the equivalent roughness to the film thickness.

  16. Transition effect of air shower particles in plastic scintillators

    NASA Technical Reports Server (NTRS)

    Asakimori, K.; Maeda, T.; Kameda, T.; Mizushima, K.; Misaki, Y.

    1985-01-01

    The transition effect of air shower particles in the plastic scintillators near the core was measured by scintillators of various thickness. The air showers selected for the measurement were of 10,000. Results obtained are as follows: (1) the multiplication of shower particles in the scintillators is less than 20% for that of 50 mm thickness; (2) dependence of the transition effect on age parameter is not recognized within the experimental errors.

  17. Quantitative assessment of radiation force effect at the dielectric air-liquid interface

    PubMed Central

    Capeloto, Otávio Augusto; Zanuto, Vitor Santaella; Malacarne, Luis Carlos; Baesso, Mauro Luciano; Lukasievicz, Gustavo Vinicius Bassi; Bialkowski, Stephen Edward; Astrath, Nelson Guilherme Castelli

    2016-01-01

    We induce nanometer-scale surface deformation by exploiting momentum conservation of the interaction between laser light and dielectric liquids. The effect of radiation force at the air-liquid interface is quantitatively assessed for fluids with different density, viscosity and surface tension. The imparted pressure on the liquids by continuous or pulsed laser light excitation is fully described by the Helmholtz electromagnetic force density. PMID:26856622

  18. 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.

  19. 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.

  20. 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.