WorldWideScience

Sample records for air pressure effect

  1. Air Entrainment in Dynamic Wetting: Knudsen Effects and the Influence of Ambient Air Pressure

    CERN Document Server

    Sprittles, James E

    2015-01-01

    Recent experiments on coating flows and liquid drop impact both demonstrate that wetting failures caused by air entrainment can be suppressed by reducing the ambient gas pressure. Here, it is shown that non-equilibrium effects in the gas can account for this behaviour, with ambient pressure reductions increasing the gas' mean free path and hence the Knudsen number $Kn$. These effects first manifest themselves through Maxwell slip at the gas' boundaries so that for sufficiently small $Kn$ they can be incorporated into a continuum model for dynamic wetting flows. The resulting mathematical model contains flow structures on the nano-, micro- and milli-metre scales and is implemented into a computational platform developed specifically for such multiscale phenomena. The coating flow geometry is used to show that for a fixed gas-liquid-solid system (a) the increased Maxwell slip at reduced pressures can substantially delay air entrainment, i.e. increase the `maximum speed of wetting', (b) unbounded maximum speeds ...

  2. Effect of ambient air pressure on debris redeposition during laser ablation of glass

    International Nuclear Information System (INIS)

    The effect of ambient air pressure on the redeposition of debris, ablated from the zinc borosilicate glass target using 6 ns, 266 nm laser pulses, has been studied for incident fluences of 3-18 J/cm2. Measurements were carried out in air at pressures ranging from 10-750 Torr. Scanning electron microscopy and optical microscope observations of the target surface were made to analyze the morphology of the redeposited debris. It was found that for higher values of the laser fluence and ambient pressure, the target surface is extremely rough, with large pieces of molten glass and debris fragments deposited near and around the ablation site. The profile of the redeposited debris also shows signs of a strong shock-wave-cleaning effect and possibly a Rayleigh-Taylor instability at higher pressures. Contrary to this, under low-pressure environment the surface of the redeposited debris is cleaner and smoother, with minimal damage around the ablated crater. The measured radius of the debris field was found to be proportional to the inverse cube root of the ambient pressure, consistent with the stagnation distance of the expansion plume when energy balance with the displaced air is considered. In addition to this, the mass of the redeposited debris was estimated from the measured optical thickness of the film and compared to the ablated mass. In the range below 100 Torr, both the mass of the redeposited debris and the percentage of the ablated mass which was redeposited were found to increase with the increasing fluence and the ambient air pressure

  3. Effect analysis of air introduced by pressurization on fuel rod performances

    International Nuclear Information System (INIS)

    In the process of pressurization and seal welding, it is common practice to vacuumize before gas filling for the sake of preventing introducing air and other impurities, which would affect the gas composition inside of the fuel rod. However, vacuumization during pressurization is likely not being required sometimes in order to simplify the fabrication procedure. In the present work, based on the AFA3G fuel rod design with 2 MPa of filling gas, analyses on fuel rod performances were carried out under the condition of pressurization with and without vacuumization, respectively. Furthermore, the effect on hydrogen content in fuel rod was preliminarily discussed. Results indicate that the impacts of air composition introduced by pressurization on fuel rod thermal-mechanical performances, such as internal pressure and fuel center temperature, were extremely slight. The gap conductance varies to some extent as a result of the change of gas composition due to air introduced in fuel rod. The impact of humidity on water content in fuel rod is negligible at a low temperature of around 25℃. However, at higher temperature, it is essential to pay attention on the control of fabrication process, and prevent much moisture entering into the fuel rod and increasing the probability of hydriding failure. (authors)

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

    Science.gov (United States)

    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. The effect of air trap to the precision of measurement level using differential pressure transmitter

    International Nuclear Information System (INIS)

    The Differential Pressure Transmitter is an instruments for measuring water-level on Pressurizer and Steam Generator of Reactor Thermalhydraulic Loop. This instrument works base on difference pressure of two sides The difference pressure of two sides e.g : Reference pressure sides and processing pressure sides. The difference pressure of two side of transmitter equivalent to water level which to be measured, according to equation P ρ g h. The output of transmitter is electrical current that equivalent to the difference pressure appeared. Air trap on water level measurement system caused a difference output current, comparing to the out put current without air trap, on the same water level. Increasing the height of air trap causes increasing the measurement error, where the indicated level will be low that the real level

  6. Effect of microwave frequency on plasma formation in air breakdown at atmospheric pressure

    Institute of Scientific and Technical Information of China (English)

    赵朋程; 郭立新; 李慧敏

    2015-01-01

    Microwave breakdown at atmospheric pressure causes the formation of a discrete plasma structure. The one-dimensional fluid model coupling Maxwell equations with plasma fluid equations is used to study the effect of the mi-crowave frequency on the formation of air plasma. Simulation results show that, the filamentary plasma array propagating toward the microwave source is formed at different microwave frequencies. As the microwave frequency decreases, the ratio of the distance between two adjacent plasma filaments to the corresponding wavelength remains almost unchanged (on the order of 1/4), while the plasma front propagates more slowly due to the increase in the formation time of the new plasma filament.

  7. Pressurized air supply device

    International Nuclear Information System (INIS)

    Ventilation air-conditioning facilities in a nuclear reactor building are adapted to suck clean external air not containing radioactivity through air supply filters disposed at an air intake port of the nuclear reactor building by means of an air supply blower and then supply the sucked air through an air supply duct and an air supply port to the inside of the power plant. Futher, pipeways for supplying sucked air to a compressor is branched from the air supply duct, through which air is supplied to an air compressor for instrumentation and an air compressor used in the power plant. The air sucked and compressed in the air compressor for instrumentation is further supplied by way of pipeways for supplying air for instrumentation to air-actuated valves, instruments, etc. Further, air sucked and compressed in the air compressor used in the power plant is further supplied by way of air supply pipeways for the power plant to a reservoir, air mask, etc. By supplying clean compressed air in this way, operators exposure dose can be reduced. (T.M.)

  8. Air humidity and water pressure effects on the performance of air-cathode microbial fuel cell cathodes

    KAUST Repository

    Ahn, Yongtae

    2014-02-01

    To better understand how air cathode performance is affected by air humidification, microbial fuel cells were operated under different humidity conditions or water pressure conditions. Maximum power density decreased from 1130 ± 30 mW m-2 with dry air to 980 ± 80 mW m -2 with water-saturated air. When the cathode was exposed to higher water pressures by placing the cathode in a horizontal position, with the cathode oriented so it was on the reactor bottom, power was reduced for both with dry (1030 ± 130 mW m-2) and water-saturated (390 ± 190 mW m-2) air. Decreased performance was partly due to water flooding of the catalyst, which would hinder oxygen diffusion to the catalyst. However, drying used cathodes did not improve performance in electrochemical tests. Soaking the cathode in a weak acid solution, but not deionized water, mostly restored performance (960 ± 60 mW m-2), suggesting that there was salt precipitation in the cathode that was enhanced by higher relative humidity or water pressure. These results showed that cathode performance could be adversely affected by both flooding and the subsequent salt precipitation, and therefore control of air humidity and water pressure may need to be considered for long-term MFC operation. © 2013 Elsevier B.V. All rights reserved.

  9. The effect of form pressure on the air void structure of SCC

    DEFF Research Database (Denmark)

    Jensen, Mikkel Vibæk; Hasholt, Marianne Tange; Geiker, Mette Rica

    2005-01-01

    The high workability of self-compacting concrete (SCC) invites to high casting rates. However, casting walls at high rate may result in large pressure at the bottom of the form and subsequently compression of the air voids. This paper deals with the influence of hydrostatic pressure during settin...... air void structure may be estimated by using Boyle-Mariottes law. However, other conditions such as the form filling method might influence.......The high workability of self-compacting concrete (SCC) invites to high casting rates. However, casting walls at high rate may result in large pressure at the bottom of the form and subsequently compression of the air voids. This paper deals with the influence of hydrostatic pressure during setting...... on the air void structure of hardened, air entrained SCC. The subject was examined through laboratory investigations of SCC with two different amounts of air entrainment. The condition in the form was simulated by using containers making it possible to cure concrete under various pressures...

  10. Surfactant effects on air pressure transients in building drainage, waste and ventilation (DWV) systems

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, D.P. [Drainage Research Group, The School of the Built Environment, Heriot-Watt University, Edinburgh, EH14 4AS (United Kingdom)

    2007-05-15

    Building drainage, waste and ventilation (DWV) systems isolate the habitable space from the waste material with water trap seals at various points in the network. Current design guides aim to produce systems which protect these trap seals from unwanted air pressures, but are based on steady state experiments utilising cold clean water as a test media, and include a large 'safety factor' with no formal basis. However, most 'gray' and 'black' water sources are dosed with detergent, and are often warm, which significantly alters the behaviour when compared to clean water. This paper describes the current status of the investigation of parameters affected in systems operating with detergent-dosed waste water over typical temperature ranges, then uses an existing EPSRC-funded mathematical model (AIRNET) based on these findings to assess the impact of the effect of detergents on existing building codes. The results quantify the effects of detergency with temperature and indicate a general shortfall in current code-based predictions, and suggest that building codes may need revision. (author)

  11. Investigation of Gas Turbine Intake Air Cooling Via Evaporative Media and Its Effects on Cartridge Filters Pressures Drop

    Directory of Open Access Journals (Sweden)

    Ehsan Farvaresh

    2015-10-01

    Full Text Available  The Aim of this study was to evaluate the effect of Evaporative Media as gas turbine intake air cooling method on pressure drop of cartridge air filters. This study performed under the laboratory condition, using stainless steel test rig with specified dimensions to investigate the role of evaporative media in air cooling as well as its effects on new and used cartridge filters (as representative of clean and loaded filters. Tests were carried out at three five hours consecutive stages including, warm -dry stage (Ta=35-40°C and relative humidity ([RH] =10-15%, cold - humid stage (Ta=22-27°C and RH=80 to 85%, and, warm-dry stage (Ta=35-40 °C and RH=10-15% for 3 consecutive days. Findings showed that using evaporative media caused air intake temperature reduction was equal to 12.5 °C. Total pressure drop of cartridge filters was 5.13±0.84 and 3.86±0.14 mbar for used and new filters, respectively. Results of repeated measure test showed that the differences between new and used filters pressure drop was significant (P=0.001. Combined effects of humidity and dust loading on filters pressure drop demonstrated that cartridge filters were not affected by humidity (P=0.75 and the main reason of pressure drop was due to collected dust on filters. It is concluded that using evaporative media systems is suitable method for cooling gas turbine intake and increase turbine efficiency without any significant increase of filter pressure drop in hot-dry climate.  

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

    International Nuclear Information System (INIS)

    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. (paper)

  13. Effect of Fuel-Air Ratio, Inlet Temperature, and Exhaust Pressure on Detonation

    Science.gov (United States)

    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.

  14. Effect of non-thermal air atmospheric pressure plasma jet treatment on gingival wound healing

    Science.gov (United States)

    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

  15. Effect of non-thermal air atmospheric pressure plasma jet treatment on gingival wound healing

    International Nuclear Information System (INIS)

    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

  16. Experimental Investigation of Nozzle Effects on Thrust and Inlet Pressure of an Air-breathing Pulse Detonation Engine

    Institute of Scientific and Technical Information of China (English)

    CHEN Wenjuan; FAN Wei; ZHANG Quan; PENG Changxin; YUAN Cheng; YAN Chuanjun

    2012-01-01

    Nozzle effects on thrust and inlet pressure of a multi-cycle air-breathing pulse detonation engine (APDE) are investigated experimentally.An APDE with 68 mm in diameter and 2 050 mm in length is operated using gasoline/air mixture.Straight nozzle,converging nozzle,converging-diverging nozzle and diverging nozzle are tested.The results show that thrust augmentation of converging-diverging nozzle,diverging nozzle or straight nozzle is better than that of converging nozzle on the whole.Thrust augmentation of straight nozzle is worse than those of converging-diverging nozzle and diverging nozzle.Thrust augmentations of diverging nozzle with larger expansion ratio and converging-diverging nozzle with larger throat area range from 20% to 40%on tested frequencies and are bener than those of congeneric other nozzles respectively.Nozzle effects on inlet pressure are also researched.At each frequency it is indicated that filling pressures and average peak pressures of inlet with diverging nozzle and converging-diverging nozzle with large throat cross section area are higher than those with straight nozzle and converging nozzle.Pressures near thrust wall increase in an increase order from without nozzle,with diverging nozzle,straight nozzle and converging-diverging nozzle to converging nozzle.

  17. Incidence of Cold Injury and Effects of Reduced Air Pressure in High Altitude Areas of the Himalayas

    OpenAIRE

    B. D. Varma

    1984-01-01

    Data covering the three-year period, 1981-1984, from the forward area hospitals, receiving patients from units operating in high altitude areas of the Himalaya reveal an average admission of 247 and 171 cases of cold injury and effects of reduced air pressure respectively. Chillblain was the commonest (85.8%) form of cold injury and high altitude pulmonary oedema the commonest (76.2%) clinical syndrome in the hopoxia group. In both groups, the disease was mild in 61 per cent cases and severe ...

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

    Science.gov (United States)

    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

  19. Effect of Aviation Fuel Type and Fuel Injection Conditions on the Spray Characteristics of Pressure Swirl and Hybrid Air Blast Fuel Injectors

    OpenAIRE

    Feddema, Rick Thomas

    2013-01-01

    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...

  20. Effect of pressure and stoichiometric air ratio on NOx emissions in gas turbine dump combustor with double cone burner

    International Nuclear Information System (INIS)

    This work presents an experimental investigation of NOx emissions according to inlet air temperature (550-660K), stoichiometric air ratio (λ, 1.4-2.1), and elevated pressure (2-5bar) in a High Press Combustor (HPC) equipped with a double cone burner, which was designed by Pusan Clean Coal Center (PC3). The exhaust gas temperature and NOx emissions were measured at the end of the combustion chamber. The NOx emissions generally decreased as a function of increasing λ. On the other hand, NOx emissions were influenced by λ, inlet air temperature and pressure of the combustion chamber. In particular, when the inlet air temperature increased, the flammability limit was extended to leaner conditions. As a result, a higher adiabatic temperature and lower NOx emissions could be achieved under these operation conditions. The NOx emissions that were governed by thermal NOx were greatly increased under elevated pressures, and slightly increased at sufficiently low fuel concentrations (λ>1.8)

  1. On small climatic effects of air invasion in polar regions: The influence on atmospheric pressure and heat flux

    International Nuclear Information System (INIS)

    The possibility of decreasing atmospheric pressure by air invasion in the down-welling zone of the ocean is discussed. The boundary condition for the solution of the baric tendency equation on the atmosphere-ocean interface is derived. It is shown that atmospheric pressure may decrease about 0.1-10 Pa day-1 for gas invasion and downwelling rates of 0.001-0.1 cm c-1, due to active gas-water exchange without regard for heat and water vapor transfer. This calculation was based on a model of the diffusion boundary layer. It was used for the total solution of the baric tendency equation. These estimates were made for the region of formation of Antarctic Bottom Water. This factor, with regard to the quasi-stationary condition of the process, provides a significant contribution to the formation of atmospheric depressions, sub-antarctic depressions and some depressions in high latitudes of both hemispheres. The heat effect of N2, O2 and CO2 solutions in polar sea regions is considered. It is shown that, for example, the heat flux with CO2 solution (∼20 mol m-2 yr-1) corresponds to 12 Cal cm-2 year. This flux and the flux from the earth's interior (∼47 Cal cm-2 yr-1) are the same order of magnitude. In winter, this factor is one positive member of the heat balance for the polar surface layers

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

  4. Air separation with medium pressure enrichment

    International Nuclear Information System (INIS)

    A cryogenic air separation process is disclosed wherein the low pressure column section of a doubler is caused to operate closer to equilibrium and, hence, more efficiently by incorporating a medium pressure column which further enriches HP column enriched oxygen liquid before introduction into the LP column. The MP column is reboiled by indirect heat exchange with condensing HP column nitrogen, and is refluxed by direct injection of condensed nitrogen. A second improvement to cryogenic air separation is disclosed which can be advantageously combined with the above improvement, in which pressurized oxygen up to 10 ATA is efficiently produced from pumped LOX by using the pumped LOX to reflux an auxiliary higher pressure column in which a fraction of the supply air compressed to higher pressure is separated into liquid N2 which is subsequently used as reflux and into oxygen enriched liquid which is further separated

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  8. Diagnostics of atmospheric pressure air plasmas

    International Nuclear Information System (INIS)

    Atmospheric pressure air plasmas are often thought to be in Local Thermodynamics Equilibrium (LTE) owing to fast interspecies collisional exchanges at high pressure. As will be seen here, this assumption cannot be relied upon, particularly with respect to optical diagnostics. Large velocity gradients in flowing plasmas and/or elevated electron temperatures created by electrical discharges can result in large departures from chemical and thermal equilibrium. Diagnostic techniques based on optical emission spectroscopy (OES) and Cavity Ring-Down Spectroscopy (CRDS) have been developed and applied at Stanford University to the investigation of atmospheric pressure plasmas under conditions ranging from thermal and chemical equilibrium to thermochemical nonequilibrium. This article presents a review of selected temperature and species concentration measurement techniques useful for the study of air and nitrogen plasmas

  9. Effect of Initial Moisture Content on the in-Vessel Composting Under Air Pressure of Organic Fraction of MunicipalSolid Waste in Morocco

    Directory of Open Access Journals (Sweden)

    Abdelhadi Makan

    2013-01-01

    Full Text Available 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.

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

    Science.gov (United States)

    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 N2, He, Air, and O2 Microplasmas on Mung Bean Seed Germination and Seedling Growth.

    Science.gov (United States)

    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

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

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

    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.

  14. Candida utilis metabolism and morphology under increased air pressure up to 12 bar

    OpenAIRE

    Pinheiro, Rita; Lopes, Marlene; Belo, Isabel; Mota, M.

    2014-01-01

    Batch cultures of C. utilis CBS 621 were carried out in a pressurized reactor under increased air pressure up to 6 bar. The effect of total air pressure was also investigated in a high cell density fed-batch culture, raising the total air pressure from 1 bar to 12 bar. The results showed that the rise of air pressure, for both operation modes, led to a substantial enhancement of biomass production. Moreover, ethanol formation was significantly reduced at 6 bar and 12 bar air pressure, respect...

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

    Science.gov (United States)

    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.

  16. IceBridge Paroscientific L0 Pressure Altimeter Raw Air Pressure

    Data.gov (United States)

    National Aeronautics and Space Administration — The NASA IceBridge Paroscientific L0 Pressure Altimeter Raw Air Pressure (IAPRS0) data set contains air pressure readings taken over Antarctica using the...

  17. Predicted thermal superluminescence in low-pressure air

    CERN Document Server

    Aramyan, A R; Galechyan, G A; Mangasaryan, N R; Nersisyan, H B

    2009-01-01

    It is shown that due to the dissociation of the molecular oxygen it is possible to obtain inverted population in low pressure air by heating. As a result of the quenching of the corresponding levels of the atomic oxygen the thermal superluminescent radiation is generated. It has been found that the threshold of the overpopulation is exceeded at the air temperature 2300-3000 K. Using this effect a possible mechanism for the generation of the flashes of the radiation in air observed on the airframe of the space shuttle during its descent and reentry in the atmosphere is suggested.

  18. Predicted thermal superluminescence in low-pressure air

    OpenAIRE

    Aramyan, A. R.; Haroyan, K. P.; Galechyan, G. A.; Mangasaryan, N. R.; Nersisyan, H. B.

    2009-01-01

    It is shown that due to the dissociation of the molecular oxygen it is possible to obtain inverted population in low pressure air by heating. As a result of the quenching of the corresponding levels of the atomic oxygen the thermal superluminescent radiation is generated. It has been found that the threshold of the overpopulation is exceeded at the air temperature 2300-3000 K. Using this effect a possible mechanism for the generation of the flashes of the radiation in air observed on the airf...

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

    OpenAIRE

    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 b...

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

    Science.gov (United States)

    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).

  1. 21 CFR 880.5550 - Alternating pressure air flotation mattress.

    Science.gov (United States)

    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...

  2. Effect of substrate roughness and working pressure on photocatalyst of N-doped TiO{sub x} films prepared by reactive sputtering with air

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seon-Hong, E-mail: pookter@naver.com [Corporate R and D Center, Samsung SDI Co. Ltd., Yongin 446-577, Gyunggido (Korea, Republic of); Yamasue, Eiji; Okumura, Hideyuki; Ishihara, Keiichi N. [Graduate School of Energy Science, Kyoto University, Yoshida Honmachi, Sakyo, Kyoto 606-8501 (Japan)

    2015-01-01

    Highlights: • Effect of substrate roughness and working pressure on the physical properties and the photocatalytic properties of the N-doped TiO{sub x} films are investigated. • Surface roughness of glass substrate has little influence on the film properties, but significant influence on the photocatalytic ability. • 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 TiO{sub x} film. • High photocatalysis of N-doped TiO{sub x} film requires the permissible range of the N doping concentration which shows the interstitial complex N doping states in TiO{sub 2}. - Abstract: N-doped TiO{sub x} 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 TiO{sub x} 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 TiO{sub x} film, resulting in the large variation of optical, structural, and photocatalytic properties. It is suggested that the high photocatalysis of N-doped TiO{sub x} film requires a certain range of the N doping concentration which shows the interstitial complex N doping states in TiO{sub 2}.

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

    Science.gov (United States)

    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.

  4. Health Effects of Air Pollution

    Science.gov (United States)

    ... air pollution How to protect yourself from air pollution Chemicals Noise Quizzes Links to more information girlshealth glossary girlshealth.gov home http://www.girlshealth.gov/ Home The environment and your health Air Health effects of air pollution ... Health effects of air pollution Breathing air that ...

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

    Czech Academy of Sciences Publication Activity Database

    Plavcová, Eva; Kyselý, Jan

    2014-01-01

    Roč. 58, č. 6 (2014), s. 1327-1337. ISSN 0020-7128 R&D Projects: GA ČR(CZ) GAP209/11/1985 Institutional support: RVO:68378289 Keywords : weather * pressure change * cardiovascular disease * morbidity * mortality * Central Europe Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 3.246, year: 2014 http://link.springer.com/article/10.1007/s00484-013-0735-y

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

    Science.gov (United States)

    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

  7. Prenatal air pollution exposure and newborn blood pressure

    NARCIS (Netherlands)

    van Rossem, Lenie; 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, are

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    Sun Wenting; Liang Tianran; Wang Huabo; Li Heping; Bao Chengyu [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)

    2007-05-15

    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 {alpha} 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.

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

    Science.gov (United States)

    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.

  11. Measuring air pressure with a polymeric gas sensor

    Directory of Open Access Journals (Sweden)

    Juliana R. Cordeiro

    2010-01-01

    Full Text Available In this communication we describe the application of a conductive polymer gas sensor as an air pressure sensor. The device consists of a thin doped poly(4'-hexyloxy-2,5-biphenylene ethylene (PHBPE film deposited on an interdigitated metallic electrode. The sensor is cheap, easy to fabricate, lasts for several months, and is suitable for measuring air pressures in the range between 100 and 700 mmHg.

  12. Research on delayed effect of landslides caused by air pressure under heavy rainfall%强降雨条件下气压对滑坡延时效应研究

    Institute of Scientific and Technical Information of China (English)

    韩同春; 马世国; 徐日庆

    2013-01-01

    Under the intense rainfall infiltration, the air in the shallow slope is likely to be confined, and the pore air pressure in air-confining condition increases constantly as the infiltration of rainfall. The physical meaning of the air-closing pressure is illustrated through the force analysis of the wetting front. Compared with the classical Green-Ampt infiltration model, the simplified infiltration model considering the air pressure is used to study the effects of air pressure on the infiltration rate and the moving wetting front. Then the infiltration process and stability analysis of a large area of shallow slope with bedrock beneath is studied through the simplified infiltration model. The results show that the air pressure in the air-confining condition reduces the infiltration rate and the safety factor remarkably, which could also reveal the reason that why some areas had frequent landslides after the rainfall. So considering air pressure for landslide forecasting is greatly significant.%  在强降雨入渗条件下,浅层边坡土体中的气体可能被封闭,孔隙气压力在封闭条件下随着雨水的入渗不断增加。结合湿润峰面受力分析对封闭气体压力的物理意义进行了说明,通过考虑简化的气阻入渗模型,对比经典的Green-Ampt入渗模型,研究了气压对入渗率和下移的湿润峰的影响。应用该入渗模型,对下部为基岩的大面积浅层边坡雨水入渗过程以及边坡稳定性进行分析。研究表明,封闭气压显著降低了边坡体内雨水的入渗率,对安全系数的降低具有明显的延时性,这进一步揭示了部分地区雨后滑坡频繁发生的重要原因。因此,考虑封闭气压对大面积边坡降雨安全预报具有重要意义。

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

    Science.gov (United States)

    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.

  14. Environmental pressure group strength and air pollution. An empirical analysis

    International Nuclear Information System (INIS)

    There is an established theoretical and empirical case-study literature arguing that environmental pressure groups have a real impact on pollution levels. Our original contribution to this literature is to provide the first systematic quantitative test of the strength of environmental non-governmental organizations (ENGOs) on air pollution levels. We find that ENGO strength exerts a statistically significant impact on sulfur dioxide, smoke and heavy particulates concentration levels in a cross-country time-series regression analysis. This result holds true both for ordinary least squares and random-effects estimation. It is robust to controlling for the potential endogeneity of ENGO strength with the help of instrumental variables. The effect is also substantively important. Strengthening ENGOs represents an important strategy by which aid donors, foundations, international organizations and other stakeholders can try to achieve lower pollution levels around the world

  15. Dirty Air, High Blood Pressure Linked

    Institute of Scientific and Technical Information of China (English)

    应树道

    2001-01-01

    贵刊去年第6期曾刊登一短文,题目是:盐,迫升血压之元凶。读了该文,我开始严格控制每日的食盐摄入量,再附以药物治疗,血压果然趋于平稳。近日上网,遇一奇文,意思是人的血压与空气污染状况有涉!根据对2600个成年人的调查,得出了这样的结论:Pollution may cause changes in the part of the nervous system that controls blood pressure.文章又同时说明:Exactly how pollution might cause blood pressure to climb remains unclear.人体之奥妙由此可见一斑。

  16. Pressure Effect on Extensional Viscosity

    DEFF Research Database (Denmark)

    Christensen, Jens Horslund; Kjær, Erik Michael

    1999-01-01

    The primary object of these experiments was to investigate the influence of hydrostatic pressure on entrance flow. The effect of pressure on shear and extensional viscosity was evaluated using an axis symmetric capillary and a slit die where the hydrostatic pressure was raised with valves. The...... experiments show a significant increase in extensional viscosity with increasing pressure....

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

    OpenAIRE

    Baccarelli Andrea; Barretta Francesco; Dou Chang; Zhang Xiao; McCracken John P; Díaz Anaité; Bertazzi Pier; Schwartz Joel; Wang Sheng; Hou Lifang

    2011-01-01

    Abstract 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 tw...

  18. Characterizing the effects of elevated temperature on the air void pore structure of advanced gas-cooled reactor pressure vessel concrete using x-ray computed tomography

    International Nuclear Information System (INIS)

    X-ray computed tomography (X-ray CT) has been applied to nondestructively characterise changes in the microstructure of a concrete used in the pressure vessel structure of Advanced Gas-cooled Reactors (AGR) in the UK. Concrete specimens were conditioned at temperatures of 105 C and 250 C, to simulate the maximum thermal load expected to occur during a loss of coolant accident (LOCA). Following thermal treatment, these specimens along with an unconditioned control sample were characterised using micro-focus X-ray CT with a spatial resolution of 14.6 microns. The results indicate that the air void pore structure of the specimens experienced significant volume changes as a result of the increasing temperature. The increase in the porous volume was more prevalent at 250 C. Alterations in air void size distributions were characterized with respect to the unconditioned control specimen. These findings appear to correlate with changes in the uni-axial compressive strength of the conditioned concrete. (authors)

  19. EFFECTS OF ENTRAINED AIR MANNER ON CAVITATION DAMAGE*

    Institute of Scientific and Technical Information of China (English)

    WU Jian-hua; LUO Chao

    2011-01-01

    Early in 1953 the experiments by Peterka proved that air entrainment has effects on decreasing cavitation damage. This technology has been widely used in the release works of high dams since the inception of air entrainment in the Grand Goulee Dam in 1960. Behavior, mechanism and application of air entrainment for cavitation damage control have been investigated for over half century. However, severe cavitation damage happened due to complex mechanism of air entrainment. The effects of air entrainment are related to many factors, including geometric parameters, hydraulic parameters and entrained air manners. In the present work an experimental set-up for air entrainment was specially designed, the behavior of reducing cavitation damage was experimentally investigated in the three aspects of entrained air pressure, air tube aera and air tube number. The results show that magnitude of reduction of cavitation damage is closely related to the entrained air tube number as well as entrained air pressure, air tube aera, and that the effect through three air tubes is larger than that through single air tube although the entrained air tubes have the same sum of tube aera, that is, 1 + 1 + 1 > 3. Therefore, it is important to design an effective manner of air entrainment.

  20. Pneumomediastinum following high pressure air injection to the hand.

    LENUS (Irish Health Repository)

    Kennedy, J

    2010-04-01

    We present the case of a patient who developed pneumomediastinum after high pressure air injection to the hand. To our knowledge this is the first reported case of pneumomediastinum where the gas injection site was the thenar eminence. Fortunately the patient recovered with conservative management.

  1. Pneumomediastinum following high pressure air injection to the hand.

    LENUS (Irish Health Repository)

    Kennedy, J

    2012-02-01

    We present the case of a patient who developed pneumomediastinum after high pressure air injection to the hand. To our knowledge this is the first reported case of pneumomediastinum where the gas injection site was the thenar eminence. Fortunately the patient recovered with conservative management.

  2. Experimental Air Pressure Tank Systems for Process Control Education

    Science.gov (United States)

    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…

  3. A coupled surface/subsurface flow model accounting for air entrapment and air pressure counterflow

    DEFF Research Database (Denmark)

    Delfs, Jens Olaf; Wang, Wenqing; Kalbacher, Thomas; Singh, Ashok; Kolditz, Olaf

    2013-01-01

    This work introduces the soil air system into integrated hydrology by simulating the flow processes and interactions of surface runoff, soil moisture and air in the shallow subsurface. The numerical model is formulated as a coupled system of partial differential equations for hydrostatic (diffusive...... the mass exchange between compartments. A benchmark test, which is based on a classic experimental data set on infiltration excess (Horton) overland flow, identified a feedback mechanism between surface runoff and soil air pressures. Our study suggests that air compression in soils amplifies surface...

  4. Effect of low atmospheric pressure of plateau environment on air content and bubble stability of air-entrained concrete%高原低气压环境对引气混凝土含气量及气泡稳定性的影响

    Institute of Scientific and Technical Information of China (English)

    李雪峰; 付智

    2015-01-01

    该文利用低气压试验箱模拟高原气压环境,试验研究了不同配合比及初始含气量水平下环境气压的降低对引气混凝土含气量及其气泡稳定性的影响。结果表明:与常压相比,环境气压的降低能够显著削弱引气剂的引气能力,当混凝土配合比及引气剂掺量一定时,混凝土含气量随环境气压降低呈线性减少,当环境气压降低至50 kPa时,混凝土含气量降低约20%~49%。另外,低气压条件下混凝土气泡稳定性变差,具体表现为混凝土含气量经时损失变大,延长振捣时间导致低压混凝土损失更多气泡,二者均使低压下硬化混凝土的气泡间距系数增大,影响混凝土抗冻性。因此,在高原地区应通过采取优选引气剂类型、增大引气剂掺量以及避免过振等技术措施,以确保高原地区引气混凝土含气量能够达到抗冻设计要求。%The effect of atmospheric pressure reduction of environment on air content and bubble stability of air-entrained concrete were experimentally studied using low-pressure test chamber to stimulate the plateau environment. Three different mixing proportions and three different levels of the initial air content of concretes were prepared for study, and four different common types of air-entraining admixture, saponin, alkyl sulfonate, abietic soap and polyether, were used in the experiments. The results indicated that the change of atmospheric pressure of environment had a significant impact on the performance of air-entraining admixtures. When the mix proportions of concrete and the amount of air-entraining admixtures took a certain value respectively, the air content of fresh concrete decreased linearly with the drop of atmospheric pressure. When the atmospheric pressure was 50 kPa, the air content of fresh concrete fell by roughly 20% to 49%. The higher the air content of fresh concrete mixed in normal atmospheric pressure, the faster the air

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

    Science.gov (United States)

    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.

  6. High Pressure Effects on Superconductivity

    OpenAIRE

    Lorenz, B.; Chu, C. W.

    2004-01-01

    The review is devoted to a discussion of the effects of high pressure imposed on superconducting materials. Low-temperature superconductors, high-temperature superconducting cuprates, and some unconventional superconducting compounds are investigated. Experimental as well as theoretical results regarding the pressure effects on Tc and other interesting properties are summarized.

  7. Drainage vent systems: investigation and analysis of air pressure regime

    Energy Technology Data Exchange (ETDEWEB)

    Swaffield, J.A.; Jack, L.B. [Heriot-Watt University, Edinburgh (United Kingdom). Dept. of Building Engineering and Surveying

    1998-12-31

    Knowledge of the performance of building drainage vent systems and associated appliance trap seal loss and retention has developed in recent years due to extensive research into the generation and propagation of air pressure transients within drainage networks. This paper demonstrates how data gathered from experimental testing of several single stack systems, considering the influence of a wide range of parameters including stack diameter, roughness, height and applied water flow rate, can be used to provide generally applicable mathematical expressions which assist in determining the pressure regime present at critical points within such systems. (author)

  8. Insulation Technology in Dry Air and Vacuum for a 72kV Low Pressured Dry Air Insulated Switchgear

    Science.gov (United States)

    Yoshida, Tadahiro; Koga, Hiromi; Harada, Takakazu; Miki, Shinichi; Arioka, Masahiro; Sato, Shinji; Yoshida, Satoru; Inoue, Naoaki; Maruyama, Akihiko; Takeuchi, Toshie

    A new 72kV rated low pressured dry air insulated switchgear applying electromagnetic actuation and function that supports CBM has been developed. First, dielectric characteristics in dry air under lightning impulse application has been investigated at bare and insulator covered electrodes. Dependence of the breakdown electric field strength on the effective area has been clarified to apply the configuration design of the insulation mold for the vacuum interrupter. In addition, moisture volume dependence on surface resistance has been clarified to decide moisture volume in gas pressure tank. Next, a new vacuum circuit breaker (VCB) has been designed. To keep dimensions from former 72kV SF6 gas insulated switchgear, distance between contacts in vacuum interrupter is needed to be shorter than that of former switchgear. Voltage withstand capability between electrodes practically designed for vacuum interrupter has been investigated under dc voltage application simulated the small capacitive current breaking test. Gap configuration including contacts and slits has been optimized and distance has been shortened 11% from former switchgear. As a result, the new low pressured dry air insulated switchgear has been designed comparably in outer size to former SF6 gas insulated switchgear. Using dry air as an insulation medium with low pressure has been able to reduce the environmental burden.

  9. Guidelines for the pressure and efficient sizing of pressure vessels for compressed air energy storage

    International Nuclear Information System (INIS)

    Highlights: ► In small-scale CAES there are no robust guidelines in choosing an operational pressure for the vessels. ► Through the stress analysis of the vessel, an optimum pressure at minimum cost can be determined. ► One contribution is in determining the optimum pressure is small-scale CAES. ► Another contribution is in determining the shape size, and number of vessels in small-scale CAES designs. - Abstract: The paper reports guidelines for the efficient design and sizing of Small-Scale Compressed Air Energy Storage (SS-CAES) pressure vessels, including guidelines for pressures that should be used in the SS-CAES system to minimize the cost of the pressure vessel. Under a specified energy storage capacity and specified maximum and minimum operating pressures in CAES, the volume of the vessel(s) can be evaluated. The present study provides guidelines for choosing appropriate shape and size for the vessels that minimize material and manufacturing cost for cylindrical vessels. The two main contributions of the paper are that it provides a methodology to determine: (a) an optimum pressure; (b) the shape, size, and number of vessel to be used in a particular application. Results suggest that pressure vessels with a length to diameter ratio of roughly three are the most economical, and that a system should be designed for a pressure of roughly three times the minimum pressure of the expansion device.

  10. Microcontrolled air-mattress for ulcer by pressure prevention

    International Nuclear Information System (INIS)

    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

  11. Microcontrolled air-mattress for ulcer by pressure prevention

    Science.gov (United States)

    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.

  12. Microcontrolled air-mattress for ulcer by pressure prevention

    Energy Technology Data Exchange (ETDEWEB)

    Pasluosta, Cristian F; Fontana, Juan M; Beltramone, Diego A; Taborda, Ricardo A M [Universidad Nacional de Cordoba. Cordoba (Argentina)

    2007-11-15

    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.

  13. Cascade exchange pressure supercharging system of the transport engine with deep cooling of intake air

    OpenAIRE

    Alekseev, S; Krajniuk, A.

    2010-01-01

    The new principle of the organisation of working process of the combined supercharging system of Internal Comdustion Engine (ICE) with the Cascade Pressure Exchanger(CPE) has been described. It allows considerably to raise level of forcing of the engine by supercharging at the expense of expansion of effective air supply area and coolings of supercharging air to temperature below an ambient without attraction of additional mechanical energy on refrigeration cycle realization. Substantiv...

  14. AIR SEPARATION BY PRESSURE SWING ADSORPTION USING SUPERIOR ADSORBENTS

    Energy Technology Data Exchange (ETDEWEB)

    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.

  15. How micropatterns and air pressure affect splashing on surfaces

    CERN Document Server

    Tsai, Peichun; van de Raa, Matthias; Lohse, Detlef

    2010-01-01

    We experimentally investigate the splashing mechanism of a millimeter-sized ethanol drop impinging on a structured solid surface, comprised of micro-pillars, through side-view and top-view high speed imaging. By increasing the impact velocity we can tune the impact outcome from a gentle deposition to a violent splash, at which tiny droplets are emitted as the liquid sheet spreads laterally. We measure the splashing threshold for different micropatterns and find that the arrangement of the pillars significantly affects the splashing outcome. In particular, directional splashing in direction in which air flow through pattern is possible. Our top-view observations of impact dynamics reveal that an trapped air is responsible for the splashing. Indeed by lowering the pressure of the surrounding air we show that we can suppress the splashing in the explored parameter regime.

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

    Science.gov (United States)

    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)

  17. [Effect of osmotic pressure on nitrification].

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xianhui; Yang, Si-ze [Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); Liu, Dongping [Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600 (China); Song, Ying [School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600 (China); School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116023 (China); Sun, Yue [School of Physics, Changchun University of Science and Technology, Changchun 130022 (China)

    2013-05-15

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

  20. Effects of pressure waves

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

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

  2. Electrical characterization of atmospheric pressure DBD in air

    International Nuclear Information System (INIS)

    Atmospheric pressure dielectric barrier discharge (DBD) in air was generated between two rectangular copper electrodes covering the lower electrode with a dielectric (glass or polycarbonate -PC) using low frequency (line frequency-50Hz) high voltage power supply. The discharge was studied for inter-electrode gap spacing in the range of 2 mm – 5 mm and their influence on breakdown voltage. Voltage-current characteristics and the analysis of the distribution of current pulses per half cycle of the current waveform indicated that the discharge is more uniform in 3 mm inter-electrode gap spacing with PC as a dielectric rather than glass. (author)

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

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

    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. (paper)

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

    Science.gov (United States)

    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. Bronchomotor response to cold air or helium-oxygen at normal and high ambient pressures.

    Science.gov (United States)

    Jammes, Y; Burnet, H; Cosson, P; Lucciano, M

    1988-05-01

    Effects of inhalation of cold air or helium-oxygen mixture on lung resistance (RL) were studied in anesthetized and tracheotomized rabbits under normal ambient pressure and in human volunteers under normo- and hyperbaric conditions. In artificially ventilated rabbits, an increase in RL occurred when the tracheal temperature fell to 10 degrees C. This effect was more than double with helium breathing compared to air, despite a lower respiratory heat loss by convection (Hc) with helium. In 3 normal humans, inhalation of cold air (mouth temperature = 8 degrees C) at sea level had no effect on RL value. However, with a helium-nitrogen-oxygen mixture, a weak but significant increase in RL due to cold gas breathing was measured in 1 subject at 2 ATA and in 2 individuals at 3.5 ATA. The density of inhaled gas mixture (air or He-N2-O2) was near the same in the three circumstances (1, 2, and 3.5 ATA) but Hc value increased with helium. At 8 ATA a 30-55% increase in RL occurred in the 3 divers during inhalation of cold gas (Hc was multiplied by 6 compared to air at sea level) and at 25 ATA the cold-induced bronchospasm ranged between 38 and 95% (Hc multiplied by 27). Thus, in rabbits and humans helium breathing enhanced the cold-induced increase in RL at normal or elevated ambient pressure, and this effect was interpreted as resulting from different mechanisms in the two circumstances. PMID:3388628

  9. Numerical and Experimental Investigation of Electron Beam Air Plasma Properties at Moderate Pressure

    International Nuclear Information System (INIS)

    Large size of air plasma at near atmospheric pressure has specific effects in aerospace applications. In this paper, a two dimensional multi-fluid model coupled with Monte Carlo (MC) model is established, and some experiments were carried out to investigate the characteristics of electron beam air plasma at pressure of 100-170 Torr. Based on the model, the properties of electron beam air plasma are acquired. The electron density is of the order of 1016 m−3 and the longitudinal size can exceed 1.2 m. The profiles of charged particles demonstrate that the oxygen molecule is very important for air plasma and its elementary processes play a key role in plasma equilibrium processes. The potential is almost negative and a very low potential belt is observed at the edge of plasma acting as a protection shell. A series of experiments were carried out in a low pressure vacuum facility and the beam plasma densities were diagnosed. The experimental results demonstrate that electron density increased with the electron beam energy, and the relatively low pressure was favorable for gaining high density plasma. Hence in order to achieve high density and large size plasma, it requires the researchers to choose proper discharge parameters. (basic plasma phenomena)

  10. 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

    Science.gov (United States)

    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.

  11. Comparison of Effectiveness of Static Air Mattress and Dynamic Air Mattress Support in Preventing Pressure Ulcers in Patients of Department of Neurology%动态与静态空气床垫预防神经内科卧床患者压疮效果的比较

    Institute of Scientific and Technical Information of China (English)

    瞿小龙; 蒋琪霞

    2014-01-01

    目的:比较静态空气床垫与动态空气床垫对预防神经内科卧床患者压疮发生的效果.方法便利选取2012年5-8月南京军区南京总医院的神经内科患者90例,根据随机数字表法分为静态空气床垫组和动态空气床垫组各45例,两组均每2 h翻身1次,预期观察14 d,比较两组患者的压疮发生率、压疮严重度、Braden压疮危险评估结果及成本效益.结果两组患者观察期内压疮发生率均为0;Braden压疮危险评估结果分别为(14.45±2.07)分和(14.25±2.49)分,差异无统计学意义(P>0.05);静态空气床垫价格比动态空气床垫价格低350元,且无医疗耗电;静态空气床垫和动态空气床垫的平均护理时间分别为(8.87±3.03)、(9.00±3.10)d,平均每人翻身次数分别为(108±37.16)、(106±36.33)次,差异均无统计学意义(P>0.05).结论静态空气床垫与动态空气床垫比较,其预防压疮的效果相当,但成本投入少于动态空气床垫.%Objective To explore the effect of static air mattress and dynamic air mattress support in pre-venting pressure ulcers in patients of neurology department.Methods By convenience sampling,90 patients of neurology department were selected and equally divided into static air mattress group and dynamic air mattress group,Two groups of patients were all had every 2 h repositing and the expected observation period of 14 days.The incidence of pressure ulcer and the severity of pressure ulcer,Braden risk assessment result and the cost-benefit were compared.Results The incidence of pressure ulcers were 0 in both groups.The Braden scoring results were the (14.45±2.07)and (14.25±2.49)respectively(P>0.05).The result of cost-benefit analysis showed that price of static air mattress was less 350RMB than dynamic air mattress support without medical power assumption.The average nursing time of two groups patients was (8.87±3.03)days and (9±3.10) days respectively,and the

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

    International Nuclear Information System (INIS)

    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 PM2.5 (particulate matter with an aerodynamic diameter 10 (particulate matter with an aerodynamic diameter 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 PM2.5 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Jacobs, Lotte [Occupational and Environmental Medicine, Unit of Lung Toxicology, K.U.Leuven, Leuven (Belgium); Buczynska, Anna [Departement of Chemistry, UA, Wilrijk (Belgium); Walgraeve, Christophe [Research group EnVOC, Department of Sustainable Organic Chemistry and Technology, UGent, Gent (Belgium); Delcloo, Andy [Royal Meteorological Institute, Brussels (Belgium); Potgieter-Vermaak, Sanja [Departement of Chemistry, UA, Wilrijk (Belgium); Molecular Science Institute, School of Chemistry, University of Witwatersrand, Johannesburg (South Africa); Division of Chemistry and Environmental Science, Manchester Metropolitan University, Manchester (United Kingdom); Van Grieken, Rene [Departement of Chemistry, UA, Wilrijk (Belgium); Demeestere, Kristof; Dewulf, Jo; Van Langenhove, Herman [Research group EnVOC, Department of Sustainable Organic Chemistry and Technology, UGent, Gent (Belgium); De Backer, Hugo [Royal Meteorological Institute, Brussels (Belgium); Nemery, Benoit, E-mail: ben.nemery@med.kuleuven.be [Occupational and Environmental Medicine, Unit of Lung Toxicology, K.U.Leuven, Leuven (Belgium); Nawrot, Tim S. [Occupational and Environmental Medicine, Unit of Lung Toxicology, K.U.Leuven, Leuven (Belgium); Centre for Environmental Sciences, Hasselt University, Diepenbeek (Belgium)

    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.

  14. Effect of aeration on fast gas pressure tests

    Institute of Scientific and Technical Information of China (English)

    CHEN Yu-jia; JIANG Cheng-lin; LI Xiao-wei; TANG Jun; WANG Chen; YANG Fei-long; WANG Fa-kai; ZHANG Chao-jie; DENG Shu-hua

    2009-01-01

    Given the problem of the long time required for testing gas pressure, we propose a fast-test method in which we used a technique of fast borehole sealing and air replenishing. Based on the characteristics of gas emission from boreholes to be tested, we built a theoretical model for calculating parameters during the process of increasing natural pressure and aeration. Using this model, we investigated the effect of different aeration conditions on velocity of pressure tests. The result shows that: 1) aerating air into boreholes can speed up gas pressure tests and 2) the more similar the pressure of the aerated air to the original gas pressure, the smaller the gas volume absorbed by coal and the shorter the time needed in pressure test. A case study in the Lu'an mining area shows that the time needed for gas pressure test is only 4 h using our method of aeration and 29 h under conditions of increasing natural pressure, saving time by 86.2%. This case study also indicates that, by using the aeration method, only one hour is needed for gas pressure to reach a stable state, which breaks the record of the shortest time needed for gas pressure tests in China.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Gorji-Bandpy Mofid

    2012-04-01

    Full Text Available 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. 供氧模式对载人航天器气压控制的影响分析%The effect of oxygen supply mode on air pressure control of manned spacecraft

    Institute of Scientific and Technical Information of China (English)

    靳健; 侯永青

    2015-01-01

    The air control system in a manned spacecraft is used to control theoxygen partial pressure and the air pressure of the pressurized cabin within the index range. In the manned spacecraft for a long-term crew staying, the water electrolysis system is usually used to control the oxygen partial pressure of the pressurized cabin. A simulation model of the air pressure control system of the pressurized cabin in the manned spacecraft is proposed. Using this model, the varying trends of the oxygen partial pressure and the air pressure related to the two oxygen supply modes of the water electrolysis system and the oxygen cylinder are compared and analyzed. According to the results, when the staying period is 24 h, the oxygen partial pressure related to the oxygen supply by the oxygen cylinder keeps declining, which is different from that related to the oxygen supply by the water electrolysis system. The varying trend of the oxygen partial pressure related to the oxygen supply by the water electrolysis system is determined by the oxygen supply flux and the crew metabolic oxygen consumption; meanwhile, the varying range of the oxygen partial pressure related to the oxygen supply by the water electrolysis system is dramatically smaller than that related to the oxygen supply by the oxygen cylinder. When the staying period is 60 d, the varying cycle of the oxygen partial pressure and the air pressure related to the oxygen supply by the water electrolysis system is dramatically longer than that related to the oxygen supply by the oxygen cylinder. In order to avoid the influence of the air temperature, the control range of the oxygen partial pressure and the air pressure should be narrower than the allowable range.%载人航天器气压控制系统主要负责控制密封舱内氧分压和总压满足指标要求,承担长期载人任务的载人航天器通常配备电解制氧系统用于维持密封舱内氧分压水平.文章建立了一种载人航天器密封舱气压控

  18. The effect of oxygen supply mode on air pressure control of manned spacecraft%供氧模式对载人航天器气压控制的影响分析

    Institute of Scientific and Technical Information of China (English)

    靳健; 侯永青

    2015-01-01

    载人航天器气压控制系统主要负责控制密封舱内氧分压和总压满足指标要求,承担长期载人任务的载人航天器通常配备电解制氧系统用于维持密封舱内氧分压水平.文章建立了一种载人航天器密封舱气压控制系统仿真分析模型,利用该模型分析对比了氧气瓶供氧和电解制氧供氧 2 种模式对应的密封舱氧分压和总压变化规律.结果表明,驻留24 h内,氧气瓶供氧模式对应的氧分压单调下降;电解制氧供氧模式对应的氧分压并非单调下降,而是取决于供氧速率与乘员代谢耗氧间的关系,且氧分压变化范围要远小于氧气瓶供氧模式.驻留60 d内,电解制氧供氧模式对应的氧分压在上下限间的变化周期以及总压的变化周期要明显长于氧气瓶供氧模式.为避免空气温度的影响,氧分压和总压的控制范围应比允许范围窄.%The air control system in a manned spacecraft is used to control theoxygen partial pressure and the air pressure of the pressurized cabin within the index range. In the manned spacecraft for a long-term crew staying, the water electrolysis system is usually used to control the oxygen partial pressure of the pressurized cabin. A simulation model of the air pressure control system of the pressurized cabin in the manned spacecraft is proposed. Using this model, the varying trends of the oxygen partial pressure and the air pressure related to the two oxygen supply modes of the water electrolysis system and the oxygen cylinder are compared and analyzed. According to the results, when the staying period is 24 h, the oxygen partial pressure related to the oxygen supply by the oxygen cylinder keeps declining, which is different from that related to the oxygen supply by the water electrolysis system. The varying trend of the oxygen partial pressure related to the oxygen supply by the water electrolysis system is determined by the oxygen supply flux and the crew metabolic

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

    Science.gov (United States)

    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. Firing with compressed air at very high pressure; Disparo con aire comprimido a muy alta presion

    Energy Technology Data Exchange (ETDEWEB)

    Saez Garcia, E.; Margareto Garcia, J.L.; Millan Echevarria, J.L.; Embil Martinez, E. [Escuela Tecnia Superior de Ingenieros Mineros, Oviedo (Spain)

    1994-05-01

    This article recounts the experiments executed in Hunosa`s Montsacro pit on the application of the DAMAP (Disparo can aire comprimido a muy alta presion - Firing with compressed air at very high pressure) process to the horizontal, sloping and caving seams or horizontal sublevels mining method usually used by Hunosa for thick and vertical seams. The project met the approval of Ocicarbon who participated with finance. Mescek Coal Mines also participated with their knowledge of DAMAP from mining in Hungary and provided the necessary equipment, technical assistance and training for Hunosa personnel. The project lasted for 14 months, comprising three phases: receipt, assembling of the equipment, and two months of system testing; 10 months of experiments to discern the possibilities offered by DAMAP technology in horizontal sublevels; and compilation of a report recounting the experience and results of the project. 3 figs., 1 tab.

  1. Repetitive nanosecond glow discharge in atmospheric pressure air

    Science.gov (United States)

    Packan, Denis

    Nonequilibrium, weakly ionized plasmas are widely used in the industry, but they are restricted to the domain of continuous discharges at low gas pressure or with specialty gases because of stability and power budget constraints. In this study, repetitively pulsed discharges were investigated as a way to decrease the power budget of atmospheric air plasmas by several orders of magnitude compared to continuous discharges, for an electron density of 1012 cm-3. The principle of the pulsed scheme is to use nanosecond electrical pulses to ionize air diffusely and with high efficiency, and to match the pulse interval with the recombination time of the plasma in order to maintain an elevated average electron density. Maxwellian and non-Maxwellian models of the physical processes in the discharge were examined, and the discharge parameters were chosen to minimize the power. Using a 10 ns, 12 kV, 100 kHz repetitive pulse generator, it was found that a repetitive nanosecond glow discharge could be operated in stable manner in atmospheric pressure air at 2000 K at an electron density of about 10 12 cm-3. Two pulsed discharges, with repetition frequencies of 100 kHz and 30 kHz, are described in this work. The electrode gap is 1 cm and the pulsed voltage is about 5 kV/cm. Electrical and optical methods were developed to measure the electron density in the discharge. The electron density was measured from the electrical conductivity during both the pulse and recombination phases, from the absolute intensity of the N2 Second Positive system during the pulse phase, and from the NO-gamma system during the recombination phase. The average electron density was found to be 1.4 x 1012 cm -3 for the 100 kHz discharge, and 1.8 x 102 cm-3 for the 30 kHz discharge, with peak values of 2 x 1012 cm-3 and 1013 cm-3, respectively. The power budget for the 30 kHz discharge was measured, from the voltage and current during the pulse phase, to be about 10 W/cm3, which represents an improvement of

  2. Determination of air and hydrofoil pressure coefficient by laser doppler anemometry

    Directory of Open Access Journals (Sweden)

    Ristić Slavica S.

    2010-01-01

    Full Text Available Some results of experiments performed in water cavitation tunnel are presented. Pressure coefficient (Cp was experimentally determined by Laser Doppler Anemometry (LDA measurements. Two models were tested: model of airplane G4 (Super Galeb and hydrofoil of high speed axial pump. These models are not prepared for conventional pressure measurements, so that LDA is applied for Cp determination. Numerical results were obtained using a code for average Navier-Stokes equations solutions. Comparisons between computational and experimental results prove the effectiveness of the LDA. The advantages and disadvantages of LDA application are discussed. Flow visualization was made by air bubbles.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  5. High pressure effects on fruits and vegetables

    OpenAIRE

    Timmermans, R.A.H.; Matser, A.M.

    2016-01-01

    The chapter provides an overview on different high pressure based treatments (high pressure pasteurization, blanching, pressure-assisted thermal processing, pressure-shift freezing and thawing) available for the preservation of fruits and vegetable products and extending their shelf life. Pressure treatment can be used for product modification through pressure gelatinization of starch and pressure denaturation of proteins. Key pressure–thermal treatment effects on vitamin, enzymes, flavor, co...

  6. A proposed compressed air drying method using pressurized liquid desiccant and experimental verification

    International Nuclear Information System (INIS)

    Highlights: • A novel compressed air drying method using pressurized liquid desiccant was proposed. • Experiments verified the method and get compressed air with the humidity of 0.9 g/kg. • Energy efficiency was analyzed to show the energy saving potential of the new method. - Abstract: A novel compressed air drying method using pressurized liquid desiccant is proposed in this paper. The compressed air drying system is consisted of a compressed air module, a pressurized liquid desiccant dehumidifier, a liquid desiccant regenerator working in an atmospheric pressure, and other auxiliary components. An experimental apparatus of the pressurized liquid desiccant dehumidifier associated with a compressed air module is established to verify the proposed air drying method experimentally. The results show that, under the pressure of 0.5 MPa, the moisture content in the outlet air can reach 0.9 g/kg. The moisture content of the outlet air reaches 1.4 g/kg under the pressure of 0.3 MPa, and the power consumption of the drying system is 6.17 kJ/g, which is 0.69 kJ/g and 10.1% lower than the conventional compressed air cooling drying system. The dehumidification efficiency is around 0.90, indicating the sufficiently mass transfer between compressed air and solution in pressurized dehumidifier. Besides, the proposed compressed air drying system can use the low-grade heat from the air compressor to regenerate the diluted desiccant solution. The novel air drying method is verified to offer very dry air for industrial application, and shows significant energy saving potential compared with the conventional compressed air cooling drying system

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

    Science.gov (United States)

    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. Pressure distributions in a centrifugal impeller handling air-water mixtures

    International Nuclear Information System (INIS)

    At the time of vapor and liquid two-phase flow, when the volume proportion of vapor to liquid increases, the performance of pumps lowers conspicuously. The lowering of performance in the state of bubble flow arises mainly at the entrance of impellers, and the changes of the flow in impellers and pump performance at this time show the features similar to the case of cavitation in liquid single-phase flow, accordingly, the similar treatment of both cases can be made. In this study, a centrifugal pump of semi-open radial flow type with low specific speed was used, and by measuring the varying pressure inside the casing through the small holes drilled on the casing, the pressure distribution in the impeller at the time of air and water two-phase flow (bubble flow) was obtained, thus the effect of the ratio of flow rate of air and water was examined. The experimental setup and experimental method, the dynamic characteristics of the measuring instrument system, the gap at the end of vanes and the pressure distribution on vane surfaces, and the pressure distribution in the impeller are reported. The pressure distribution in two-phase flow was remarkably different from that in liquid single-phase flow. (Kako, I.)

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

    Science.gov (United States)

    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 (Ppregnancy-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

  10. Influence of humidity on atmospheric pressure air plasma treatment of aluminium surfaces

    International Nuclear Information System (INIS)

    Atmospheric pressure air plasma treatment of aluminium surfaces and its aging behaviour in different environments were studied. Two types of aluminium samples with different purity and surface morphology were treated using the diffuse coplanar surface barrier discharge (DCSBD). Surface free energy (SFE) and X-ray photoelectron spectroscopy (XPS) have been utilised to characterise changes induced by the plasma. A significant decrease of hydrocarbon contaminants after the plasma treatment was observed. It is concluded that besides the re-contamination by exposure to ambient air, the aging effect, i.e. decrease of the surface free energy of plasma treated surfaces, can be due by dehydration of aluminium oxide layer. Also, it was observed that the humid air plasma treatment resulted in generation of -NOx surface groups.

  11. Measurement of laminar flame speeds and flame stability analysis of tert-butanol-air mixtures at elevated pressures

    International Nuclear Information System (INIS)

    Highlights: → New measured laminar flame speeds and Markstein lengths for the tert-butanol-air were provided. → Flame stability is analyzed from the diffusive stability and hydrodynamic stability. → New understanding to the fundamental combustion characteristics of premixed tert-butanol-air mixture is provided. → These data are useful for development and validation of tert-butanol chemical kinetics. - Abstract: Laminar flame speeds and Markstein lengths of tert-butanol-air premixed mixtures were measured over a wide range of equivalence ratios at different initial temperatures and pressures by using the spherically propagating flame in a constant volume combustion chamber. Effects of Markstein number, flame thickness and density ratio at two sides of flame front on flame instability were analyzed combined with the schlieren photos. Results show that the unstretched flame propagation speeds and laminar flame speeds of the tert-butanol-air mixtures increase with the increase of initial temperature and decrease with the increase of initial pressure. Peak values of laminar flame speeds present at equivalence ratio of 1.1 regardless of initial pressure and temperature. Markstein length decreases with the increase of initial pressure. Flame front instability increases as equivalence ratio and initial pressure increase. Cellular structure appears at elevated pressure. The combined effect of diffusional-thermal instability and hydrodynamic instability leads to the increase of flame instability as initial pressure increases.

  12. Design and clinical application of safe air-pressure reduction system for intussusception

    International Nuclear Information System (INIS)

    This study was performed to design a safe air-pressure reduction system which can absorb rapidly rising intraluminal pressure during intussusception, and comparison with other reduction systems to test its clinical availability. The air-pressure reduction system consisted of a pressure gauge, air insufflators, a pressure controller, buffers, and rapid exhaustion devices, and to determine its absorbability, it was connected with a bowel model. By using it in 20 infants with intussusception, we compared the absorbability of our air-pressure reduction system with preexisting systems. While extraluminal pressure was applied to the bowel model in which baseline intraluminal pressure was set to 120mmHg, this rose to 176mmHg (56mmHg high to standard, 100%) in the direct infusion system, but to only 130mmHg (10mmHg high to standard, 17.9%) in a system connected to a large buffer of 10,500mL capacity. Immediately after the application of extraluminal pressure for less than 1 sec, this air-pressure reduction system showed better asorbability than the hydrostatic reduction system. Applying this system to 20 infants with intussusception, this was successfully reduced in 19 cases(95%), without complications. In this experiment, it was proved that the system absorbed rapid intraluminal pressure elevation. Its use would help prevent bowel perforation during air reduction occurring during intussusception.=20

  13. Effect of Air Outlet Angle on Air Distribution Performance Index

    Directory of Open Access Journals (Sweden)

    Isbeyeh W. Maid

    2013-05-01

    Full Text Available       In this paper a numerical study of velocity and temperature distribution in air conditioned space have been made. The computational model consists of the non-isothermal 3-D turbulent with (k-ε model. The numerical study is made to conduct air distribution in a room air-conditioned space with real interior dimensions (6×4×3m and to analyze the effect of changing angle of grille vanes on the flow pattern, velocity, and temperature distribution in the room under a set of different condition, and under a supply air temperature of 16˚C to examine the final result on air distribution performance index (ADPI.The results show a significant effect within the change of supply air angle, the maximum air distribution performance index (ADPI is 52% when air change per hour (ACH is equal to 10 at 16˚C inlet temperature with angle ( 15˚ down, and the minimum value of (ADPI is 20% when ACH is equal to 15 at 16˚C inlet temperature and angle ( degree. 

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

    Science.gov (United States)

    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.

  15. Effect of pressure on nanomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Uma D. [Department of Physics, G.B. Pant University of Agriculture and Technology, Pantnagar-263145 (India); Kumar, M., E-mail: munish_dixit@yahoo.co [Department of Physics, G.B. Pant University of Agriculture and Technology, Pantnagar-263145 (India)

    2010-07-01

    A simple theory is proposed to predict the effect of pressure on nanomaterials, which gets support from the Mie-Gruneisen theory of thermal expansivity as formulated by Born and Huang. We considered LiAlSi{sub 2}O{sub 6} to study the effect of pressure in the light of other formulations, viz. Murnaghan, Birch-Murnaghan, Vinet and Kumar. The results obtained are found to present a good agreement with the experimental data as well as other formulations. To confirm the validity of the formulation, we applied the method to study the compression behaviour of a number of nanomaterials, viz. CdSe, Rb{sub 3}C{sub 60}, Ni(20 nm), carbon nanotube, {gamma}-Fe{sub 2}O{sub 3}, {epsilon}-Fe (Hexagonal iron), MgO, CuO, {gamma}-Al{sub 2}O{sub 3} (67 nm), {alpha}-Fe{sub 2}O{sub 3}, {alpha}-Fe (filled nanotube), TiO{sub 2} (anatase), 3C-SiC (30 nm), TiO{sub 2} (rutile phase), Zr{sub 0.1}Ti{sub 0.9}O{sub 2}, AlN (hexagonal), {gamma}-Si{sub 3}N{sub 4}, Ni-filled MWCNT and Fe-filled MWCNT. The results obtained are compared with the experimental data. A good agreement between theory and experiment demonstrates the validity of the present approach.

  16. Air-water two-phase flow pressure drop across various components of AHWR fuel bundle

    International Nuclear Information System (INIS)

    Single-phase (water) and two-phase (air-water) experiments were carried out for the measurement of pressure drops across various components of a prototype full scale 54-rod fuel bundle of proposed AHWR (Advanced Heavy Water Reactor). From the measured values of pressure drops, the friction factor for fuel bundle and the loss coefficients for the tie plates and spacers were estimated. The single-phase experimental data were compared with different existing correlations. Correlations have been proposed based on the data generated with the air-water mixture which can be used for prediction of pressure drop across fuel channel (with 54 rod fuel bundle) of AHWR under normal operating conditions with appropriate correction factor for steam-water flow. Also a heuristic approach to predict the Lockhart-Martinelli parameter has been presented. Further, a new correlation for two-phase friction multiplier applicable to 54-rod cluster geometry has been developed based on two-phase experimental pressure drop data. The effect of mixture mass flux on the two-phase friction multiplier has been probed and the assessment of existing friction multiplier correlations has also been carried out with the test data. (author)

  17. An Alternative Approach to the Monitoring of Respiration by Dynamic Air-Pressure Sensor

    OpenAIRE

    Takarada, Tohru; Kawahara, Michio; Irifune, Masahiro; Endo, Chie; Shimizu, Yoshitaka; Kobayashi, Keiko; Sakata, Keiko; Kikuchi, Nobuhito; Saida, Takuya; Onizuka, Chiori

    2007-01-01

    Monitoring and assessing of patient respiratory function during conscious sedation are important because many drugs used for conscious sedation produce respiratory depression and subsequent hypoventilation. The purpose of this study is to assess the value of a dynamic air-pressure sensor for respiratory monitoring of clothed patients. Eight clothed adult volunteers were reclined on a dental chair positioned horizontally. The air bag for measuring air-pressure signals corresponding to respirat...

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

    Directory of Open Access Journals (Sweden)

    Zou Chang-Fang

    2015-07-01

    Full Text Available 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.

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

    Science.gov (United States)

    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.

  20. Pressure effects in multiphase binary diffusion couples

    Science.gov (United States)

    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.

  1. Pressure measurements in a hydrogen combustion environment: hydrogen-air combustion test series 1 and 2 in the FITS tank. Volume 1

    International Nuclear Information System (INIS)

    Test series 1 and 2 examined the effects of a number of parameters on hydrogen-air combustion: the initial temperature and pressure of the gases, the effect of added steam or carbon dioxide as diluents, and the percent hydrogen in air. For tests in the range of 20% to 40% hydrogen in air, recorded peak pressures were equal to adiabatic, isochoric, complete combustion (AICC) values within an experimental error of 15%. This was contrary to the results of tests at a number of other facilities. The pre-ignition temperature had a strong effect on the peak pressure, while pre-ignition pressure in the range examined had no effect on combustion pressure ratios. Calculations showed that, although the effect of dynamic head on the peak pressure was a few percent or less, interactions of the wave preceding the flame front with the flame and with the vessel walls may be apparent in the experimental records

  2. Air Circulation and Heat Exchange Under Reduced Pressures

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

    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. (physics of gases, plasmas, and electric discharges)

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

    Institute of Scientific and Technical Information of China (English)

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

    2013-01-01

    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.

  6. Energy distribution of runaway electrons generated by a nanosecond discharge in atmospheric-pressure air

    Science.gov (United States)

    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.

  7. Incentive Effects of Peer Pressure in Organizations

    OpenAIRE

    Kohei Daido

    2006-01-01

    This paper studies the effects of peer pressure on incentives. We assume that, in addition to the material payoff, each agent's utility includes the psychological payoff from peer pressure generated by a comparison of effort costs. We show that the optimal incentive schemes depend mainly on the degree of peer pressure and of the heterogeneity of agents. Furthermore, we examine the optimal organizational forms in terms of the principal''s intention to make use of the effects of peer pressure.

  8. Burning Behaviour of High-Pressure CH4-H2-Air Mixtures

    Directory of Open Access Journals (Sweden)

    Jacopo D'Alessio

    2013-01-01

    Full Text Available Experimental characterization of the burning behavior of gaseous mixtures has been carried out, analyzing spherical expanding flames. Tests were performed in the Device for Hydrogen-Air Reaction Mode Analysis (DHARMA laboratory of Istituto Motori—CNR. Based on a high-pressure, constant-volume bomb, the activity is aimed at populating a systematic database on the burning properties of CH4, H2 and other species of interest, in conditions typical of internal combustion (i.c. engines and gas turbines. High-speed shadowgraph is used to record the flame growth, allowing to infer the laminar burning parameters and the flame stability properties. Mixtures of CH4, H2 and air have been analyzed at initial temperature 293÷305 K, initial pressure 3÷18 bar and equivalence ratio  = 1.0. The amount of H2 in the mixture was 0%, 20% and 30% (vol.. The effect of the initial pressure and of the Hydrogen content on the laminar burning velocity and the Markstein length has been evaluated: the relative weight and mutual interaction has been assessed of the two controlling parameters. Analysis has been carried out of the flame instability, expressed in terms of the critical radius for the onset of cellularity, as a function of the operating conditions.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  11. The effect of a photocatalytic air purifier on indoor air quality quantified using different measuring methods

    Energy Technology Data Exchange (ETDEWEB)

    Kolarik, Barbara [Technical University of Denmark, International Centre for Indoor Environment and Energy, Faculty of Civil Engineering, Lyngby (Denmark); Silesian University of Technology, 44-100 Gliwice (Poland); Danish Building Research Institute (SBi), Department of Construction and Health, Dr Neergaards Vej 15, 2970 Hoersholm (Denmark); Wargocki, Pawel [Technical University of Denmark, International Centre for Indoor Environment and Energy, Faculty of Civil Engineering, Lyngby (Denmark); Skorek-Osikowska, Anna [Silesian University of Technology, 44-100 Gliwice (Poland); Wisthaler, Armin [Institute of Ion Physics and Applied Physics, University of Innsbruck, 6020 Innsbruck (Austria)

    2010-06-15

    The effect on indoor air quality of an air purifier based on photocatalytic oxidation (PCO) was determined by different measuring techniques: sensory assessments of air quality made by human subjects, Proton-Transfer-Reaction Mass Spectrometry (PTR-MS) and chromatographic methods (Gas Chromatography/Mass Spectrometry and High-Pressure Liquid Chromatography with UV detection). The experiment was conducted in a simulated office, ventilated with 0.6 h{sup -1}, 2.5 h{sup -1} and 6 h{sup -1}, in the presence of additional pollution sources (carpet, chipboard and linoleum). At the lowest air change rate, additional measurements were made with no pollution sources present in the office. All conditions were tested with the photocatalytic air purifier turned on and off. The results show that operation of the air purifier in the presence of pollutants emitted by building materials and furniture improves indoor air quality, as documented by sensory assessments made by human subjects. It also reduces concentrations of many chemical compounds present in the air as documented by the PTR-MS technique. For the lowest ventilation, results from measurements using the chromatographic methods have similar tendency, however many of the 50 compounds that were targeted for analysis were not detected at all, independent of whether the purifier was on or off. For the two conditions with higher ventilation the results were inconclusive. (author)

  12. An Explosive Range Model Based on the Gas Composition, Temperature, and Pressure during Air Drilling

    Directory of Open Access Journals (Sweden)

    Xiangyu Fan

    2016-01-01

    Full Text Available Air drilling is low cost and effectively improves the penetration rate and causes minimal damage to liquid-sensitive pay zones. However, there is a potential downhole explosion when combustible gas mixed with drilling fluid reaches the combustible condition. In this paper, based on the underground combustion mechanism, an explosive range calculation model is established. This model couples the state equation and the empirical formula method, which considers the inert gas content, pressure, mixed gas component, and temperature. The result shows that increase of the inert gas content narrows the explosive range, while increase of the gas temperature and pressure improves the explosive range. A case in Chongqing, China, is used to validate the explosive range calculation model.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    Dvořák Lukáš

    2015-01-01

    Full Text Available 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.

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

    Science.gov (United States)

    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.

  17. Impact of air pressure on volatile organic compound emissions from a carpet

    Institute of Scientific and Technical Information of China (English)

    高鹏; 邓琴琴; LIN; Chao-hsin; 杨旭东

    2009-01-01

    The measurement of volatile organic compound (VOC) emissions from materials is normally conducted under standard environmental conditions, i.e., (23±1) ℃ temperature, (50±5)% relative humidity, and 0.1 MPa pressure. In order to define VOC emissions in non-standard environmental conditions, it is necessary to study the impact of key environmental parameters on emissions. This paper evaluates the impact of air pressure on VOC emissions from an aircraft carpet. The correlation between air pressure and VOC diffusion coefficient is derived, and the emission model is applied to studying the VOC emissions under pressure conditions of less than 0.1 MPa.

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

    Science.gov (United States)

    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

  19. Detailed Comparison of Blast Effects in Air and Vacuum

    Energy Technology Data Exchange (ETDEWEB)

    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.

  20. Review of Methods for Calculating Pressure Profiles of Explosive Air Blast and its Sample Application

    OpenAIRE

    Chock, Jeffrey Mun Kong

    1999-01-01

    Blast profiles and two primary methods of determining them were reviewed for use in the creation of a computer program for calculating blast pressures which serves as a design tool to aid engineers or analysts in the study of structures subjected to explosive air blast. These methods were integrated into a computer program, BLAST.F, to generate air blast pressure profiles by one of these two differing methods. These two methods were compared after the creation of the program and can conserv...

  1. Numerical analysis of steam-air behavior in a pressurizer during reflux cooling

    International Nuclear Information System (INIS)

    During reflux cooling, proper estimation of an accumulated non-condensable gas in the SG U-tubes is important to estimate the performance of the reflux cooling. Non-condensable gas exists in the pressurizer and the possibility of migration of air in the pressurizer to the SG U-tubes is well not known. Steam and air behavior in the pressurizer during reflux cooling is, therefore, calculated numerically using FLUENT 6.3.26 and the possibility of migration of air to the hot leg is investigated. As a calculation domain, the pressurizer of ROSA-IV/LSTF was employed, which has experimental data of the loss of RHR event during the mid-loop operation. Two phases were assumed; (1) Phase 1: latent heat accumulates in the wall of the pressurizer and releases to the outside, (2) Phase 2: the wall heats up to the steam saturation temperature and only heat loss to the outside is present. In Phase 1 air did not migrate to the surge line in both results of laminar and turbulent calculations, while in Phase 2 migration of air to the hot leg occurred only in the laminar calculation. Comparison of the fluid temperatures near the wall of pressurizer indicates that the turbulent calculation was closer to the ROSA-IV/LSTF experiment and the possibility of migration of air to the hot leg is low. (author)

  2. Space Charge Transient Kinetic Characteristics in DC Air Corona Discharge at Atmospheric Pressure

    Science.gov (United States)

    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.

  3. Space Charge Transient Kinetic Characteristics in DC Air Corona Discharge at Atmospheric Pressure

    International Nuclear Information System (INIS)

    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

  4. On the hydrogen-air adiabatic isochoric complete combustion pressure

    International Nuclear Information System (INIS)

    A simple and fast method for calculating the AICC state (adiabatic Isochoric Complete Combustion) for the hydrogen-air reaction is presented. By comparison with more detailed algorithms it is shown that the proposed method produces satisfactory results, and is thus a viable alternative in situations where the use of detailed algorithms or of tables is too time-consuming. (orig.)

  5. Pressure effects on the femtosecond laser filamentation

    Science.gov (United States)

    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.

  6. Discussion of mechanical design for pressured cavity-air-receiver in solar power tower system

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Zhilin; Zhang, Yaoming; Liu, Deyou; Wang, Jun; Liu, Wei [Hohai Univ., Nanjing (China). New Materials and Energy Sources Research and Exploitation Inst.

    2008-07-01

    In 2005, Hohai university and Nanjing Chunhui science and technology Ltd. of China, cooperating with Weizmann Institute of Science and EDIG Ltd. of Israel, built up a 70kWe solar power tower test plant in Nanjing, Jiangsu province, China, which was regarded as the first demonstration project to demonstrate the feasibility of solar power tower system in China. The system consists of heliostats field providing concentrated sunlight, a solar tower with a height of 33 meter, a pressured cavity-air-receiver transforming solar energy to thermal energy, a modified gas turbine adapting to solar power system, natural gas subsystem for solar-hybrid generation, cooling water subsystem for receiver and CPC, controlling subsystem for whole plant, et al. In this system, air acts as actuating medium and the system works in Brayton cycle. Testing results show that solar power tower system is feasible in China. To promote the development of solar powered gas turbine system and the pressured cavity-air-receiver technology in China, it is necessary to study the mechanical design for pressured Cavity-air-receiver. Mechanical design of pressured cavity-air-receiver is underway and some tentative principles for pressured cavity-air-receiver design, involving in power matching, thermal efficiency, material choosing, and equipment security and machining ability, are presented. At the same time, simplified method and process adapted to engineering application for the mechanical design of pressured cavity-air-receiver are discussed too. Furthermore, some design parameters and appearance of a test sample of pressured cavity-air-receiver designed in this way is shown. It is appealed that, in China, the research in this field should be intensified and independent knowledge patents for pivotal technological equipments such as receiver in solar power tower system should be formed. (orig.)

  7. Effective Coulomb interactions in solids under pressure

    OpenAIRE

    Tomczak, Jan M.; Miyake, T; Sakuma, R.; Aryasetiawan, F.

    2009-01-01

    Correlated materials are extremely sensitive to external stimuli, such as temperature or pressure. Describing the electronic properties of such systems often requires applying many-body techniques to effective low energy problems in the spirit of the Hubbard model, or extensions thereof. While the effect of pressure on structures and bands has been investigated extensively within density-functional based methods, the pressure dependence of electron-electron interactions has so far received li...

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

    Science.gov (United States)

    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

  9. Effects of air vessel on water hammer in high-head pumping station

    International Nuclear Information System (INIS)

    Effects of air vessel on water hammer process in a pumping station with high-head were analyzed by using the characteristics method. The results show that the air vessel volume is the key parameter that determines the protective effect on water hammer pressure. The maximum pressure in the system declines with increasing air vessel volume. For a fixed volume of air vessel, the shape of air vessel and mounting style, such as horizontal or vertical mounting, have little effect on the water hammer. In order to obtain good protection effects, the position of air vessel should be close to the outlet of the pump. Generally, once the volume of air vessel is guaranteed, the water hammer of a entire pipeline is effectively controlled

  10. Finding the optimal setting of inflated air pressure for a multi-cell air cushion for wheelchair patients with spinal cord injury.

    Directory of Open Access Journals (Sweden)

    Hamanami K

    2004-02-01

    Full Text Available Pressure distribution patterns of the seating interface on the multi-cell air cushion (ROHO High Profile of 36 adults with spinal cord injury (SCI (Neurological level Th3 -L1 were measured at different air pressure levels by a pressure mat measurement system. Stress distribution relative to the inflated air pressure in the air cushion on the patients' wheelchairs was analyzed to determine the appropriate inflated air pressure of the cushion for patients. The maximum pressure points in all subjects were at the areas of the ischial tuberosities (82 to 347 mmHg. The optimal reduction in interface pressure at the ischial tuberosities was obtained just before bottoming out. The cushion air pressure at that point was between 17 and 42 mmHg, and correlated well to body weight (r = 0.495, P = 0.0021. In contrast, the maximum pressure levels did not correlate to body weight or the Body Mass Index (BMI. Pressure at the ischial area could be reduced, but not eliminated, by adjusting the air pressure. The maximum pressure levels seemed to be related to the shape of the buttocks, especially the amount of soft tissue, and exceeded the defined threshold for pressure ulcers (> 80 g/cm2.

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

    OpenAIRE

    Dvořák Lukáš; Fojtášek Kamil

    2015-01-01

    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 expe...

  12. Creation of prompt and thin-sheet splashing by varying surface roughness or increasing air pressure

    CERN Document Server

    Latka, Andrzej; Driscoll, Michelle M; Stevens, Cacey S; Nagel, Sidney R

    2012-01-01

    A liquid drop impacting a solid surface may splash by emitting a thin liquid sheet that subsequently breaks apart or by promptly ejecting droplets from the advancing liquid-solid contact line. Using high-speed imaging, we show that air pressure and surface roughness influence both splash mechanisms. Roughness increases prompt splashing at the advancing contact line but inhibits the formation of the thin sheet. If the air pressure is lowered, droplet ejection is suppressed not only during thin-sheet formation but for prompt splashing as well. The threshold pressure depends on impact velocity, liquid viscosity and surface roughness.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-01-15

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

  14. 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

    Science.gov (United States)

    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.

  15. Response of NPP structures to simultaneously acting air pressure loads and ground waves caused by a gas cloud explosion

    International Nuclear Information System (INIS)

    Gas cloud explosions cause air pressure waves which propagate over the ground surface. The ground motion induced by these loads and their effect on structures are studied. The soil is modelled as a linear viscoelastic medium. A semianalytical method is used to compute the ground motion produced by a deflagration and by a detonation in a stiff and a soft layered soil. For a PWR reactor building subjected to the direct impact of an air pressure wave the additional effects of the ground waves on the motion of the building are studied. Whereas the vertical structural response is increased, the horizontal response decreases, when the effect of the ground waves is included. For the case studied the additional effect of the ground waves is small. (orig.)

  16. Border Effects in Passenger Air Traffic

    OpenAIRE

    Klodt, Henning

    2003-01-01

    National borders substantially matter in passenger air traffic. Empirical estimates based upon a new data set on domestic and international departures from German airports indicate that the German border reduces air traffic activity by a factor of four to five. This result adds a further piece of evidence to the significance of border effects in various kinds of economic activity.

  17. Numerical simulation and experimental validation of a direct current air corona discharge under atmospheric pressure

    Institute of Scientific and Technical Information of China (English)

    Liu Xing-Hua; He Wei; Yang Fan; Wang Hong-Yu; Liao Rui-Jin; Xiao Han-Guang

    2012-01-01

    Air corona discharge is one of the critical problems associated with high-voltage equipment.Investigating the corona mechanism plays a key role in enhancing the electrical insulation performance.An improved self-consistent multi-component two-dimensional plasma hybrid model is presented for the simulation of a direct current atmospheric pressure corona discharge in air.The model is based on plasma hydrodynamic and chemical models,and includes 12 species and 26 reactions.In addition,the photoionization effect is introduced into the model.The simulation on a bar-plate electrode configuration with an inter-electrode gap of 5.0 mm is carried out.The discharge voltage-current characteristics and the current density distribution predicted by the hybrid model agree with the experimental measurements.In addition,the dynamics of volume charged species generation,discharge current waveform,current density distribution at an electrode,charge density,electron temperature,and electric field variations are investigated in detail based on the model.The results indicate that the model can contribute valuable insights into the physics of an air plasma discharge.

  18. Numerical simulation and experimental validation of a direct current air corona discharge under atmospheric pressure

    International Nuclear Information System (INIS)

    Air corona discharge is one of the critical problems associated with high-voltage equipment. Investigating the corona mechanism plays a key role in enhancing the electrical insulation performance. An improved self-consistent multi-component two-dimensional plasma hybrid model is presented for the simulation of a direct current atmospheric pressure corona discharge in air. The model is based on plasma hydrodynamic and chemical models, and includes 12 species and 26 reactions. In addition, the photoionization effect is introduced into the model. The simulation on a bar-plate electrode configuration with an inter-electrode gap of 5.0 mm is carried out. The discharge voltage—current characteristics and the current density distribution predicted by the hybrid model agree with the experimental measurements. In addition, the dynamics of volume charged species generation, discharge current waveform, current density distribution at an electrode, charge density, electron temperature, and electric field variations are investigated in detail based on the model. The results indicate that the model can contribute valuable insights into the physics of an air plasma discharge. (physics of gases, plasmas, and electric discharges)

  19. Plasma propagation of a 13.56 MHz asymmetric surface barrier discharge in atmospheric pressure air

    Energy Technology Data Exchange (ETDEWEB)

    Dedrick, J; Boswell, R W; Charles, C [Space Plasma, Power and Propulsion Group, Research School of Physics and Engineering, The Australian National University, ACT 0200 (Australia); Audier, P; Rabat, H; Hong, D, E-mail: james.dedrick@anu.edu.au [GREMI - UMR6606 CNRS/Universite d' Orleans, Polytech' Orleans, 14, rue d' Issoudun - BP6744, 45067 ORLEANS Cedex 2 (France)

    2011-05-25

    The propagation of an rf asymmetric surface barrier discharge in atmospheric pressure air has been investigated. Measurements of the pulse-modulated 13.56 MHz voltage and current together with ICCD images of the plasma were recorded to study the visible plasma structure with respect to the rf pulses, time within the pulses and the rf waveforms. When exposing images over full rf pulses, which comprise over 150 oscillations of the applied voltage, clearly defined filamentary structures are observed indicating a strong memory effect. The discharge intensity decreases exponentially with distance from the electrode edge, and the average propagation length increases linearly with the applied voltage. Similar to some lower frequency asymmetric surface dielectric barrier discharges, two distinct breakdown events occur during one period of the voltage waveform. The number of filaments is found to be the same for both breakdown events, and collective effects are observed in both discharges.

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

    Science.gov (United States)

    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.

  1. Effect of pressure on biogas production

    Directory of Open Access Journals (Sweden)

    Ahmet ERYAŞAR

    2009-02-01

    Full Text Available In facilities in which biogas systems are installed biogas is not produced and consumed simultaneously. Therefore, biogas produced when there is no consumption should be stored. Low pressure gasometers with 1- 1,5 kPa value are preferred in the rural area and when needed pressurizer is added to the system. When the pressure which gas production and usage require is provided by natural ways without usage of an added pressurizer, a respectively high pressure atmosphere can be seen. In this study, the effects of different low pressures on anaerobic fermentation of cattle manure were experimentally analyzed. Fermentation experiment which was carried out with 9 reactors with fed-batch type, 3 parallels in pressures of 19.6 kPa, 9.5 kPa and 1.5 kPa continued 60 days at 35 ºC. The acquired experimental data was subjected to LSD test in P

  2. Ventilation System Effectiveness and Tested Indoor Air Quality Impacts

    Energy Technology Data Exchange (ETDEWEB)

    Rudd, Armin [Building Science Corporation, Somerville, MA (United States); Bergey, Daniel [Building Science Corporation, Somerville, MA (United States)

    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.

  3. Ventilation System Effectiveness and Tested Indoor Air Quality Impacts

    Energy Technology Data Exchange (ETDEWEB)

    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.

  4. Monitoring of urban air pollution from MODIS aerosol data: effect of meteorological parameters

    OpenAIRE

    Zha, Yong; Gao, Jay; Jiang, Jianjun; Lu, Heng; Huang, Jiazhu

    2011-01-01

    Remote sensors designed specifically for studying the atmosphere have been widely used to derive timely information on air pollution at various scales. Whether the satellite-generated aerosol optical thickness (AOT) data can be used to monitor air pollution, however, is subject to the effect of a number of meteorological parameters. This study analyses the influence of four meteorological parameters (air pressure, air temperature, relative humidity, and wind velocity) on estimating particulat...

  5. High gas pressure effects on yeast.

    Science.gov (United States)

    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

  6. Conversion of Dynamic High Pressures from Air to Water for a Spherical TNT Charge

    Directory of Open Access Journals (Sweden)

    A. K. Sharma

    1996-01-01

    Full Text Available A numerical method has been applied to convert the dynamic high pressures from air-to-water for a spherical TNT charge. Standard equation of scaling law in air for TNT has been utilised to make the necessary conversions. The investigations have been made by taking into consideration the ambient pressure values for the two media. The calculations have been performed under the scaled distances to get better results. Experimental measurements using indigenous blast pressure gauge have been undertaken by detonating spherical charges of TNT under the same scaled distances in water to check the correctness of results and direct application of this method. A fairly close agreement between the theoretically computed and the experimental values of the dynamic high pressures shows the practical utility of this approach in that it enables an estimate of the experimental shock wave pressures, without conducting underwater experiments.

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

    Science.gov (United States)

    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.

  8. Influence of ambient air pressure on impact pressure caused by breaking waves

    NARCIS (Netherlands)

    Moutzouris, C.

    1979-01-01

    Engineers are interested in the dynamics of the interface waterstructure. In case of breaking of water waves on a structure high positive and sometimes negative pressures of very short duration occur. Not only the maxima and minima of the pressures on the structure are important to a designing engin

  9. Characterization of the pressure field induced by the explosions in air of a hydrocarbon-air mixture with slow deflagration of fast deflagration

    International Nuclear Information System (INIS)

    The present research contract, carried out in the framework of a French working group CEA-EDF-ENSMA, was divided into four phases: 1) Phase 1: Scaling effects on a pressure field generated by spontaneous accelerations of deflagrations in a homogeneous medium: these ''CHARLES'' tests performed on completely unconfined charges of ethylene-air and acetylene-air mixture (V approximately= 12 m3) have demonstrated the high sensitivity of the pressure field to the flame acceleration, particularly at the end of the propagation. 2) Phase 2: Effect of a sudden discontinuity in the concentration of the combustible gas on the deflagration speed in a heterogeneous medium: this discontinuity was obtained using two concentric latex balloons, filled with different hydrocarbon concentrations and also destroyed before firing. 3) Phase 3: Study of pseudo-detonation modes for the explosion of spherical ethylene-air mixtures: these modes were sought by increasing an explosive plastic mass associated to the igniter. 4) Phase 4: Study of the influence of cloud shape, ignition point location and simple obstacles in the flame path on the pressure field generated by the explosion. A retractable enclosure was designed, built and unfortunately destroyed by the second test

  10. Electrode Evaporation Effects on Air Arc Behavior

    Institute of Scientific and Technical Information of China (English)

    LI Xingwen; CHEN Degui; LI Rui; WU Yi; NIU Chunping

    2008-01-01

    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.

  11. Effects of cryogenic cold air jet cutting on chip break in metal machining

    Institute of Scientific and Technical Information of China (English)

    YANG Ying; TONG Mingwei; WU Zhijuan

    2004-01-01

    The half-dry cutting employs cryogenic compressed air cooled down to (-10 to -40) ℃ and a micro-dosage of lubricating oil, called cryogenic cold air jet cutting was studied. On the basis of a comparative experiment on dry and cryogenic cold air jet cuttings carried out for grade 45 steel, the effects of cryogenic cold air jet on the breaking of chips were discussed.The experimental results reveal that in the valid ranges of pressure and temperature, the cryogenic cold air jet widens the chip breaking areas effectively. When the cutting depth is not greater than 1 mm, the influence of chip breaking is much more significant. But different injecting angle of cold air has different influence on the chip-break. From the experiment, the optimized jet injecting angle, temperature effecting range and pressure working range of cold air are obtained. These results can offer a foundation for industrial manufacturing.

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Shuang; Wang, Kaile; Zuo, Shasha; Liu, Jiahui [Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Zhang, Jue, E-mail: zhangjue@pku.edu.cn; Fang, Jing [Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); College of Engineering, Peking University, Beijing 100871 (China)

    2015-10-15

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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  16. Electric wind produced by a surface dielectric barrier discharge operating in air at different pressures: aeronautical control insights

    Energy Technology Data Exchange (ETDEWEB)

    Benard, N; Balcon, N; Moreau, E [Laboratoire d' Etudes Aerodynamiques (LEA), Universite de Poitiers, ENSMA, CNRS Bld Marie et Pierre Curie, Teleport 2, 86962 Futuroscope Cedex (France)

    2008-02-21

    The effects of the ambient air pressure level on the electric wind produced by a single dielectric barrier discharge (DBD) have been investigated by Pitot velocity measurements. Pressures from 1 down to 0.2 atm were tested with a 32 kV{sub p-p} 1 kHz excitation. This preliminary study confirms the effectiveness of surface DBD at low pressure. Indeed, the induced velocity is strongly dependent on the ambient air pressure level. Quite surprisingly the produced airflow presents a local maximum at 0.6 atm. The measured velocities at 1 atm and 0.2 atm are 2.5 m s{sup -1} and 3 m s{sup -1}, respectively while 3.5 m s{sup -1} is reached at 0.6 atm. The position of the maximal velocity always coincides with the plasma extension. Mass flow rate calculations indicate that the DBD is effective in real flight pressure conditions. (fast track communication)

  17. Electrical characterization of atmospheric pressure dielectric barrier discharge in air

    International Nuclear Information System (INIS)

    This paper reports the electrical characterization of dielectric barrier discharge produced at atmospheric pressure using a high voltage power supply operating at 50Hz. The characteristics of the discharge have been studied under different values as such applied voltage and the electrode gap width. The results presented in this work can be helpful in understanding the influence of dielectric material on the nature of the discharge. An attempt has also been made to investigate the influence of ballast resistor on the magnitude of discharge current and also the density of micro-discharges. Our results indicated that with this power supply and electrode geometry, a relatively more homogenous discharge is observed for 3 mm spacing. (author)

  18. 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

    International Nuclear Information System (INIS)

    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

  19. 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

    Science.gov (United States)

    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.

  20. Numerical simulation of air flow field in high-pressure fan with splitter blades

    Institute of Scientific and Technical Information of China (English)

    Jianfeng LI; Junfu LU; Hai ZHANG; Qing LIU; Guangxi YUE

    2008-01-01

    For a deeper understanding of the flow char-acteristics in the high-pressure centrifugal blower of a fan of Model 9-26 with splitter blades, a three dimensional (3-D) numerical simulation of air flows in the fan was con-ducted with FLUENT software. The standard k-ε tur-bulent model and unstructured grids were used. The computational fluid dynamics (CFD) results showed that the performance of a fan could be improved by adding the splitter blades in the channel among the leaf blades. Under operational conditions, with the presence of splitter blades, the air flow rate of the fan increased about 5% and the total pressure at the outlet of the fan increased about 10% on average. It was also found that the length of the splitter blades affected the air flow and pressure drop. There is an optimal value for the length. The simulation results provide helpful information for improving the fan performance.

  1. Construction and testing of a blower-door assembly for regulation of air pressure within structures

    International Nuclear Information System (INIS)

    The Technical Measurements Center is evaluating several methods to decrease the time required to determine an annual average radon-daughter concentration in structures. One method involves stabilizing the air pressure within the structure at a constant pressure with reference to external atmospheric or soil-gas pressure. This report describes the construction and preliminary testing of a blower-door system to maintain a constant differential air pressure within a structure. The blower-door assembly includes a collapsible frame and a large fan to occlude a doorway, a damper with an actuator to control air flow, a controller to drive the damper actuator, and a pressure transducer to measure the differential pressure. Preliminary testing of the system indicates that pressure within the structure in the range of 1 to 20 Pascals can be held to within approximately +-1 Pa of the set point. Further testing of the blower-door system is planned to provide data on the applicability of this method to short-duration tests for annual average radon-daughter concentration estimates. 13 figs., 1 tab

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

    OpenAIRE

    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.

    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 pres...

  3. Influence of pressure on Leidenfrost effect

    OpenAIRE

    Buchmüller, Ilja

    2014-01-01

    The Leidenfrost effect influences substantially the contact of a liquid droplet with a hot surface. Contact between the liquid and solid is crucial for cooling applications such as fire-fighting, hot-mill steel rolling, thermal power plants and microprocessor cooling. In automotive or aerospace internal combustion engines, the combustion chamber is pressurized prior to ignition. Despite various effects of elevated pressure, the combustion process needs to be controlled. The rea...

  4. Aircraft vibration and other factors related to high systolic blood pressure in Indonesian Air Force pilots

    Directory of Open Access Journals (Sweden)

    Minarma Siagian

    2013-05-01

    Full Text Available AbstrakLatar belakang: Penerbangan dapat berdampak pada sistem kardiovaskular manusia. Penerbang terpajan antara lain pada bising dan vibrasi pesawat. Penelitian bertujuan untuk mengetahui pengaruh beberapa faktor penerbangan pada tekanan darah sistolik.Metode: Penelitian nested case-control dilakukan pada penerbang Angkatan Udara Republik Indonesia yang melakukan pemeriksaan fisik tahunan di Lembaga Kesehatan Penerbangan dan Ruang Angkasa (LAKESPRA Saryanto tahun 2003–2008. Data yang diperoleh dari rekam medik berupa umur, jumlah jam terbang, jenis pesawat, kadar glukosa puasa dan kadar kholesterol darah, lingkaran pinggang, tinggi dan berat badan, tinggi badan, serta tekanan darah.Hasil: Dari 336 penerbang, terdapat 16 penerbanga dengan tekanan sistolik ³ 140 mmHg. Penerbang dengan rata-rata jam penerbangan 300-622 jam per tahun dibandingkan dengan 29-299 jam per tahun mempunyai risiko peningkatan tekanan darah sistolik tinggi sebesarf 5 kali [rasio odds suaian (ORa = 5,05, 95% interval kepercayaan (CI = 0,88 -23,30, P = 0,070]. Menurut jam terbang total, mereka yang memiliki 1.401-1,1125 jam dibandingkan 147-1.400 jam berisiko 3,6 kali mengalami tekanan darah sistolik tinggi (ORa = 3,58, 95% CI = 1,24-10,38. Selain itu, mereka dengan denyut nadi istirahat tinggi dibandingkan dengan denyut nadi normal istirahat memiliki 2,4 kali mengalami tekanan darah sistolik tinggi (ORa = 2,37, CI = 0,74-7,50 95, P = 0,147].Kesimpulan: Vibrasi pesawat terbang tinggi, rata-rata jam terbang per tahun tinggi, dan frekuensi nadi istirahat yang tinggi meningkatkan risiko tekanan sistolik tinggi.Kata kunci:tekanan darah sistolik, vibrasi pesawat terbang, frekuensi nadi istirahat, pilotAbstractBackground:Flight may affect the human cardiovascular system. Pilots are exposed among others to aircraft noise and vibration. This study aimed to investigate the effects of aircraft flight on systolic blood pressure.Methods:A nested case-control study was conducted on

  5. Effect of Climate Change on Air Quality

    OpenAIRE

    Jacob, Daniel J.; Winner, Darrel A.

    2009-01-01

    Air quality is strongly dependent on weather and is therefore sensitive to climate change. Recent studies have provided estimates of this climate effect through correlations of air quality with meteorological variables, perturbation analyses in chemical transport models (CTMs), and CTM simulations driven by general circulation model (GCM) simulations of 21st-century climate change. We review these different approaches and their results. The future climate is expected to be more stagnant, due ...

  6. Rayleigh-Brillouin scattering profiles of air at different temperatures and pressures

    CERN Document Server

    Gu, Ziyu; van de Water, Willem; Ubachs, Wim

    2013-01-01

    Rayleigh Brillouin (RB) scattering profiles for air have been recorded for the temperature range from 255 to 340 K and the pressure range from 640 to 3300 mbar, covering the conditions relevant for the Earth's atmosphere and for planned atmospheric light detection and ranging (LIDAR) missions. The measurements performed at a wavelength of 366.8 nm detect spontaneous RB scattering at a 90 degree scattering angle from a sensitive intracavity setup, delivering scattering profiles at a 1 percent rms noise level or better. The elusive transport coefficient, the bulk viscosity, is effectively derived by a comparing the measurements to the model, yielding an increased trend. The calculated (Tenti S6) line shapes are consistent with experimental data at the level of 2 percent, meeting the requirements for the future RB scattering LIDAR missions in the Earth's atmosphere. However, the systematic 2 percent deviation may imply that the model has a limit to describe the finest details of RB scattering in air. Finally, it...

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

    Science.gov (United States)

    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:

  8. Theoretical computation for non-equilibrium air plasma electrical conductivity at atmospheric pressure

    International Nuclear Information System (INIS)

    Based on the Chapman-Enskog theory, we calculate the electrical conductivity of non-equilibrium air plasma in the two-temperature model. We consider different degrees of non-equilibrium, which is defined by the ratio of electronic temperature to heavy particles temperature. The method of computing the composition of air plasma is demonstrated. After calculating the electrical conductivity from electron temperature 1000 K to 15000 K, the present result is compared with Murphy's study for equilibrium case. All the calculation is completed at atmospheric pressure. The present results may have potential applications in numerical calculation of non-equilibrium air plasma. (authors)

  9. Effects of Ambient Pressure on Bubble Characteristics

    Institute of Scientific and Technical Information of China (English)

    卢新培; 刘明海; 江中和; 潘垣

    2002-01-01

    The effects of the ambient pressure Pambient on the bubble characteristics of pulsed discharge in water are investigated. The simulation results show that, when Pambient increases from 1 atm to 100 atm, the bubble radius R decreases from 4cma to 7mm, and its pulsation period decreases frown 8ms to 0.2ms. The results also show that the peak pressure of the first shock wave is independent of Pambient, but the peak pressure of the second shock wave caused by the bubble re-expansion decreases when Pambient increases. On the other hand, the larger the ambient pressure, the larger the peak pressure of the plasma in the bubble, while the plasma temperature is independent of Pambient.

  10. Effect of operating conditions and particle properties on performance of vertical air-lift

    OpenAIRE

    Chladek, Jana; Enstad, Gisle; Melaaen, Morten Christian

    2011-01-01

    The effect of the fluidization air flow rate and the transport air velocity on the solids mass flow rate and the pressure drop along the transport pipe was investigated in a vertical air-lift. The use of two different materials, glass (150 μm) and zirconium oxide (260 μm) particles (Geldart’s B class), enabled to estimate the effect of particle properties on the air-lift performance. Different levels of the solids mass flow rate were obtained by varying the fluidization air flow rate while ke...

  11. Unique erosion features of hafnium cathode in atmospheric pressure arcs of air, nitrogen and oxygen

    Science.gov (United States)

    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.

  12. Interaction of Atmospheric-Pressure Air Microplasmas with Amino Acids as Fundamental Processes in Aqueous Solution.

    Directory of Open Access Journals (Sweden)

    Renwu Zhou

    Full Text Available Plasma medicine is a relatively new field that investigates potential applications of cold atmospheric-pressure plasmas in bioengineering, such as for bacterial inactivation and degradation of organic molecules in water. In order to enunciate mechanisms of bacterial inactivation at molecular or atomic levels, we investigated the interaction of atmospheric-pressure air microplasmas with amino acids in aqueous solution by using high-resolution mass spectrometry (HRMS. Results show that the oxidation effect of plasma-induced species on the side chains of the amino acids can be categorized into four types, namely hydroxylation, nitration, dehydrogenation and dimerization. In addition, relative activities of amino acids resulting from plasma treatment come in descending order as follows: sulfur-containing carbon-chain amino acids > aromatic amino acids > five-membered ring amino acids > basic carbon-chain amino acids. Since amino acids are building blocks of proteins vital to the growth and reproduction of bacteria, these results provide an insight into the mechanism of bacterial inactivation by plasma.

  13. Interaction of Atmospheric-Pressure Air Microplasmas with Amino Acids as Fundamental Processes in Aqueous Solution

    Science.gov (United States)

    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

  14. Surface Treatment of Polyethylene Terephthalate Film Using Atmospheric Pressure Glow Discharge in Air

    Institute of Scientific and Technical Information of China (English)

    方志; 邱毓昌; 王辉

    2004-01-01

    Non-thermal plasmas under atmospheric pressure are of great interest in polymer surface processing because of their convenience, effectiveness and low cost. In this paper, the treatment of Polyethylene terephthalate (PET) film surface for improving hydrophilicity using the non-thermal plasma generated by atmospheric pressure glow discharge (APGD) in air is conducted.The discharge characteristics of APGD are shown by measurement of their electrical discharge parameters and observation of light-emission phenomena, and the surface properties of PET before and after the APGD treatment are studied using contact angle measurement, x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). It is found that the APGD is homogeneous and stable in the whole gas gap, which differs from the commonly filamentary dielectric barrier discharge (DBD). A short time (several seconds) APGD treatment can modify the surface characteristics of PET film markedly and uniformly. After 10 s APGD treatment, the surface oxygen content of PET surface increases to 39%, and the water contact angle decreases to 19°, respectively.

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

    Science.gov (United States)

    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.

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

    OpenAIRE

    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 vari...

  17. Afterglow chemistry of atmospheric-pressure helium–oxygen plasmas with humid air impurity

    International Nuclear Information System (INIS)

    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. (paper)

  18. Effects of pressure on doped Kondo insulators

    International Nuclear Information System (INIS)

    The effects of pressure on the doped Kondo insulators (KI) are studied in the framework of the slave-boson mean-field theory under the coherent potential approximation (CPA). A unified picture for both electron-type KI and hole-type KI is presented. The density of states of the f-electrons under the applied pressures and its variation with the concentration of the Kondo holes are calculated self-consistently. The specific heat coefficient, the zero-temperature magnetic susceptibility as well as the low temperature electric resistivity of the doped KI under various pressures are obtained. The two contrasting pressure-dependent effects observed in the doped KI systems can be naturally explained within a microscopic model. (author)

  19. Nonlinear propagation of a high-power focused femtosecond laser pulse in air under atmospheric and reduced pressure

    International Nuclear Information System (INIS)

    This paper examines the propagation of focused femtosecond gigawatt laser pulses in air under normal and reduced pressure in the case of Kerr self-focusing and photoionisation of the medium. The influence of gas density on the beam dimensions and power and the electron density in the plasma column in the nonlinear focus zone of the laser beam has been studied experimentally and by numerical simulation. It has been shown that, in rarefied air, the radiation-induced reduction in the rate of plasma formation diminishes the blocking effect of the plasma on the growth of the beam intensity in the case of tight focusing. This allows higher power densities of ultrashort laser pulses to be reached in the focal waist region in comparison with beam self-focusing under atmospheric pressure.

  20. Air distribution and ventilation effectiveness in an occupied room heated by warm air

    DEFF Research Database (Denmark)

    Krajcik, Michal; Simone, Angela; Olesen, Bjarne W.

    2012-01-01

    environment. Contaminant removal effectiveness and air change efficiency were used to evaluate ventilation effectiveness. No significant risk of thermal discomfort due to vertical air temperature differences or draught was found. When the room was heated by warm air, buoyancy forces were important for......Air distribution, ventilation effectiveness and thermal environment were experimentally studied in a simulated room in a low-energy building heated and ventilated by warm air supplied by a mixing ventilation system. Measurements were performed for various positions of the air terminal devices and...... ventilation effectiveness at low air change rates. The effect of increasing air change on the ventilation effectiveness depended on the position of air terminal devices. Depending on the position of air terminal devices, the ventilation effectiveness varied between 0.4 and 1.2, where 1 is complete mixing...

  1. The effect of air quality on sleep

    DEFF Research Database (Denmark)

    Strøm-Tejsen, Peter; Wargocki, Pawel; Wyon, David Peter;

    2014-01-01

    The effect of air quality on sleep was examined for occupants of 14 identical single-occupancy dormitory rooms. The subjects, half women, were exposed to two conditions (open/closed window), each for one week, resulting in night-time average CO2 levels of 660 and 2585 ppm, and air temperatures of...... 24.7 and 23.9°C, respectively. Sleep was assessed from movement data recorded on wristwatch-type actigraphs and from online morning questionnaires, including the Groningen Sleep Quality scale, questions about the sleep environment, next-day well-being, SBS symptoms, and two tests of mental...... performance. Although no significant effects on the sleep quality scale or on next-day performance could be shown, there were significant and positive effects of a higher ventilation rate (open window) on the actigraph measured sleep latency and on the subjects’ assessment of the freshness of the air, their...

  2. Effects of political institutions on air quality

    International Nuclear Information System (INIS)

    We empirically test existing theories on the provision of public goods, in particular air quality, using data on sulfur dioxide (SO2) concentrations from the Global Environment Monitoring Projects for 107 cities in 42 countries from 1971 to 1996. The results are as follows: First, we provide additional support for the claim that the degree of democracy has an independent positive effect on air quality. Second, we find that among democracies, presidential systems are more conducive to air quality than parliamentary ones. Third, in testing competing claims about the effect of interest groups on public goods provision in democracies we establish that labor union strength contributes to lower environmental quality, whereas the strength of green parties has the opposite effect. (author)

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

    Science.gov (United States)

    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

  4. The clinical research of the relation between air-pressure enema and the bowel swelling in infantile intussusception

    International Nuclear Information System (INIS)

    Objective: To explore the relation of air enema with bowel swelling in' infantile intussusception. Methods: In 61 cases of infantile intussusception, the thickness of the swollen bowel wall was measured and recorded by color Doppler. Then different air pressure was used for enema according to the thickness of the swollen bowel wall. Results: There were 52 (85%) cases succeeded in the operations, with 9 cases (15%) failed.. Thus the standard of feasibility of air-pressure enema in infantile intussusception was as following: (1) When the thickness of the dropsical bowel wall l.5cm, air pressure less than 8 kPa could be used only for diagnosis, not for therapy to prevent gastrointestinal perforation. Conclusion: There is obvious relation between the succession of air-pressure enema with the dropsical degree of bowel wall in infantile intussusception. This standard has very high leading value for the selection of air-pressure enema in infantile intussusception. (authors)

  5. Experimental study on the thermal performance and pressure drop of a solar air collector based on flat micro-heat pipe arrays

    International Nuclear Information System (INIS)

    Highlights: • A new type of solar air collector by using flat micro-heat pipe arrays is proposed. • Thermal efficiency rates in summer and winter are approximately 73% and 56%. • The pressure loss is below 25 Pa when the volume flow rate is less than 201.6 m3/h. - Abstract: A new solar air collector that combines the use of flat micro-heat pipe arrays (FMHPA) and evacuated tube is developed and investigated. Using FMHPA as the central transporting component in a solar air collector is an effective approach to improve the collector’s thermal properties and reduce its pressure drop. The thermal properties and pressure drop of the FMHPA solar air collector are analyzed in detail. The main objective of this paper is to report test results of the FMHPA solar air collectors which includes the effects of different seasons and airflow rates on the thermal efficiency and the pressure drop of the air collector. In summer, the thermal efficiency of the collector reaches 73% under stable operation. In the testing airflow range condition, the pressure drop is less than 25 Pa when the flow rate is below 201.6 m3/h. The relative uncertainty of thermal efficiency is approximately 7.73%

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

    Science.gov (United States)

    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.

  7. Nonlinear effective pressure law for permeability

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kawano, T.; Tanaka, M. [National Institute for Fusion Science, Toki, Gifu (Japan); Isozumi, S. [IsoShieldJP, Co. Ltd., Kohata, Ufi-shi, Kyoto (Japan); Isozumi, Y.; Tosaki, M. [Radioisotope Research Centre, Kyoto University, Kyoto (Japan); Sugiyama, T. [School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya (Japan)

    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)

  9. Systematic errors in global air-sea CO2 flux caused by temporal averaging of sea-level pressure

    Directory of Open Access Journals (Sweden)

    H. Kettle

    2005-01-01

    Full Text Available Long-term temporal averaging of meteorological data, such as wind speed and air pressure, can cause large errors in air-sea carbon flux estimates. Other researchers have already shown that time averaging of wind speed data creates large errors in flux due to the non-linear dependence of the gas transfer velocity on wind speed (Bates and Merlivat, 2001. However, in general, wind speed is negatively correlated with air pressure, and a given fractional change in the pressure of dry air produces an equivalent fractional change in the atmospheric partial pressure of carbon dioxide (pCO2air. Thus low pressure systems cause a drop in pCO2air, which together with the associated high winds, promotes outgassing/reduces uptake of CO2 from the ocean. Here we quantify the errors in global carbon flux estimates caused by using monthly or climatological pressure data to calculate pCO2air (and thus ignoring the covariance of wind and pressure over the period 1990-1999, using two common parameterisations for gas transfer velocity. Results show that on average, compared with estimates made using 6 hourly pressure data, the global oceanic sink is systematically overestimated by 7% (W92 and 10% (WM99 when monthly mean pressure is used, and 9% (W92 and 12% (WM99 when climatological pressure is used.

  10. Systematic errors in global air-sea CO2 flux caused by temporal averaging of sea-level pressure

    Directory of Open Access Journals (Sweden)

    C. J. Merchant

    2005-01-01

    Full Text Available Long-term temporal averaging of meteorological data, such as wind speed and air pressure, can cause large errors in air-sea carbon flux estimates. Other researchers have already shown that time averaging of wind speed data creates large errors in flux due to the non-linear dependence of the gas transfer velocity on wind speed (Bates and Merlivat, 2001. However, in general, wind speed is negatively correlated with air pressure, and a given fractional change in the pressure of dry air produces an equivalent fractional change in the atmospheric partial pressure of carbon dioxide (pCO2air. Thus low pressure systems cause a drop in pCO2air, which together with the associated high winds, promotes outgassing/reduces uptake of CO2 from the ocean. Here we quantify the errors in global carbon flux estimates caused by using monthly or climatological pressure data to calculate pCO2air (and thus ignoring the covariance of wind and pressure over the period 1990–1999, using two common parameterisations for gas transfer velocity (Wanninkhof, 1992 (W92 and Wanninkhof and McGillis, 1999 (WM99. Results show that on average, compared with estimates made using 6 hourly pressure data, the global oceanic sink is systematically overestimated by 7% (W92 and 10% (WM99 when monthly mean pressure is used, and 9% (W92 and 12% (WM99 when climatological pressure is used.

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

    Directory of Open Access Journals (Sweden)

    W. A. Cooper

    2014-09-01

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

  12. Human health effects of air pollution

    Energy Technology Data Exchange (ETDEWEB)

    Kampa, Marilena [Laboratory of Experimental Endocrinology, University of Crete, School of Medicine, P.O. Box 2208, Heraklion, 71003 (Greece)], E-mail: kampa@med.uoc.gr; Castanas, Elias [Laboratory of Experimental Endocrinology, University of Crete, School of Medicine, P.O. Box 2208, Heraklion, 71003 (Greece)], E-mail: castanas@med.uoc.gr

    2008-01-15

    Hazardous chemicals escape to the environment by a number of natural and/or anthropogenic activities and may cause adverse effects on human health and the environment. Increased combustion of fossil fuels in the last century is responsible for the progressive change in the atmospheric composition. Air pollutants, such as carbon monoxide (CO), sulfur dioxide (SO{sub 2}), nitrogen oxides (NOx), volatile organic compounds (VOCs), ozone (O{sub 3}), heavy metals, and respirable particulate matter (PM2.5 and PM10), differ in their chemical composition, reaction properties, emission, time of disintegration and ability to diffuse in long or short distances. Air pollution has both acute and chronic effects on human health, affecting a number of different systems and organs. It ranges from minor upper respiratory irritation to chronic respiratory and heart disease, lung cancer, acute respiratory infections in children and chronic bronchitis in adults, aggravating pre-existing heart and lung disease, or asthmatic attacks. In addition, short- and long-term exposures have also been linked with premature mortality and reduced life expectancy. These effects of air pollutants on human health and their mechanism of action are briefly discussed. - The effect of air pollutants on human health and underlying mechanisms of cellular action are discussed.

  13. Human health effects of air pollution

    International Nuclear Information System (INIS)

    Hazardous chemicals escape to the environment by a number of natural and/or anthropogenic activities and may cause adverse effects on human health and the environment. Increased combustion of fossil fuels in the last century is responsible for the progressive change in the atmospheric composition. Air pollutants, such as carbon monoxide (CO), sulfur dioxide (SO2), nitrogen oxides (NOx), volatile organic compounds (VOCs), ozone (O3), heavy metals, and respirable particulate matter (PM2.5 and PM10), differ in their chemical composition, reaction properties, emission, time of disintegration and ability to diffuse in long or short distances. Air pollution has both acute and chronic effects on human health, affecting a number of different systems and organs. It ranges from minor upper respiratory irritation to chronic respiratory and heart disease, lung cancer, acute respiratory infections in children and chronic bronchitis in adults, aggravating pre-existing heart and lung disease, or asthmatic attacks. In addition, short- and long-term exposures have also been linked with premature mortality and reduced life expectancy. These effects of air pollutants on human health and their mechanism of action are briefly discussed. - The effect of air pollutants on human health and underlying mechanisms of cellular action are discussed

  14. 42 CFR 84.149 - Type C supplied-air respirator, demand and pressure demand class; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... OF RESPIRATORY PROTECTIVE DEVICES Supplied-Air Respirators § 84.149 Type C supplied-air respirator... pounds per square inch gage), the respirator shall be equipped with a pressure-release mechanism that... exceeding 863 kN/m.2 (125 pounds per square inch gage). (2) The pressure-release mechanism shall be set...

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

    Science.gov (United States)

    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…

  16. Air Drag Effects on the Missile Trajectories

    Directory of Open Access Journals (Sweden)

    F. A. Abd El-Salam

    2011-01-01

    Full Text Available The equations of motion of a missile under the air drag effects are constructed. The modified TD88 is surveyed. Using Lagrange's planetary equations in Gauss form, the perturbations, due to the air drag in the orbital elements, are computed between the eccentric anomalies of the burn out and the reentry points [Ebo,2π−Ebo], respectively. The range equation is expressed as an infinite series in terms of the eccentricity e and the eccentric anomaly E. The different errors in the missile-free range due to the drag perturbations in the missile trajectory are obtained.

  17. Pressure drop measurement of column weight in disc and doughnut pulsed extraction column by external air purge method

    International Nuclear Information System (INIS)

    The pressure drop of column weight was measured in a disc and doughnut pulsed extraction column with the inertial diameter of 0.3 m and height of 5.6 m by internal and external air purge methods, respectively. The experimental results show that the pressure drops of column weight measured by external air purge method are in good agreement with those by internal air purge method, therefore, the external air purge method is recommended to measure the pressure drop of column weight in the pulsed extraction column in plutonium purification cycle. (authors)

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

    Science.gov (United States)

    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. Wall pressure measurements of flooding in vertical countercurrent annular air-water flow

    International Nuclear Information System (INIS)

    An experimental study of flooding in countercurrent air-water annular flow in a large diameter vertical tube using wall pressure measurements is described in this paper. Axial pressure profiles along the length of the test section were measured up to and after flooding using fast response pressure transducers for three representative liquid flow rates representing a wide range of liquid Reynolds numbers (ReL = 4Γ/μ; Γ is the liquid mass flow rate per unit perimeter; μ is the dynamic viscosity) from 3341 to 19,048. The results show that flooding in large diameter tubes cannot be initiated near the air outlet and is only initiated near the air inlet. Fourier analysis of the wall pressure measurements shows that up to the point of flooding, there is no dominant wave frequency but rather a band of frequencies encompassing both the low frequency and the broad band that are responsible for flooding. The data indicates that flooding in large diameter vertical tubes may be caused by the constructive superposition of a plurality of waves rather than the action of a single large-amplitude wave.

  20. Ambient air quality and the effects of air pollutants on otolaryngology in Beijing

    OpenAIRE

    Zhang, Fengying; Xu, Jin; Zhang, Ziying; Meng, Haiying; Wang, Li; Lu, Jinmei; Wang, Wuyi; Kraft, Thomas

    2015-01-01

    Abstract To investigate temporal patterns, pollution concentrations and the health effects of air pollutants in Beijing we carried out time-series analyses on daily concentrations of ambient air pollutants and daily numbers of outpatient visits for otolaryngology over 2 years (2011– 2012) to identify possible health effects of air pollutants. The results showed that PM10 was the major air pollutant in Beijing and that air quality was slightly better in 2012 than in 201...

  1. Mathematical models for changes in HEPA filter pressure drop caused by high air humidity

    International Nuclear Information System (INIS)

    Possible high air humidities resulting from an accident in a nuclear installation threaten the integrity of high-efficiency particulate air (HEPA) filter units in the facility air cleaning systems. Field surveys indicate that filter units continue to be exposed to adverse humidities in routine service despite the development of moisture countermeasures. One of the detrimental consequences of exposure to high air humidity is an increase in filter pressure drop (Δp). Reported failures due to a tearing of the filter medium partly result from elevated structural loadings imposed by Δp increases. The extent to which filter Δp varies with airstream conditions can be used to help calculate safety margins for filter units during normal and upset operations as well as during postulated accidents involving high air humidity. Studies of humidity-related changes in pressure drop were carried out to help explain structural failures in routine service and to obtain the empirical data needed to numerically model flow dynamics in air cleaning systems under accident conditions. Tests were performed on full-scale filter units under fog conditions and on samples of filter media at humidities up to 99% RH. Test results show that typical changes in Δp can be mathematically modeled by a number of time functions having coefficients that can only be determined empirically. Regression analysis is used to establish the coefficients for specific filter units and dust loadings tested under the operating conditions of interest. Comparison of measured and calculated increases in pressure drop for clean filter units under fog conditions show that good agreement can be obtained with coefficients determined as relatively simple functions of the airstream velocity and liquid water content

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

    Science.gov (United States)

    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

    Science.gov (United States)

    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. Modeling of Pressure Effects in HVDC Cables

    DEFF Research Database (Denmark)

    Szabo, Peter; Hassager, Ole; Strøbech, Esben

    1999-01-01

    A model is developed for the prediction of pressure effects in HVDC mass impregnatedcables as a result of temperature changes.To test the model assumptions, experiments were performed in cable like geometries.It is concluded that the model may predict the formation of gas cavities....

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

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

    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.

  7. Translational, rotational and vibrational temperatures of a gliding arc discharge at atmospheric pressure air

    DEFF Research Database (Denmark)

    Zhu, Jiajian; Gao, Jinlong; Ehn, Andreas; Li, Zhongshan; Aldén, Marcus; Salewski, Mirko; Leipold, Frank; Kusano, Yukihiro

    2014-01-01

    Gliding arc discharges have generally been used to generate non-equilibrium plasma at atmospheric pressure. Temperature distributions of a gliding arc are of great interest both for fundamental plasma research and for practical applications. In the presented studies, translational, rotational and...... vibrational temperatures of a gliding arc generated at atmospheric pressure air are investigated. Translational temperatures (about 1100 K) were measured by laser-induced Rayleigh scattering, and two-dimensional temperature imaging was performed. Rotational and vibrational temperatures (about 3600 K and 6700...

  8. Numerical Investigation of Air-Side Heat Transfer and Pressure Drop in Circular Finned-Tube Heat Exchangers

    OpenAIRE

    Mon, Mi Sandar

    2009-01-01

    A three-dimensional numerical study is performed to investigate the heat transfer and pressure drop performance on the air-side of circular finned tube bundles in cross flow. New heat transfer and pressure drop correlations for the air-cooled heat exchangers have been developed with the Reynolds number ranging from 5000 to 70000. The heat transfer and pressure drop results agree well with several existing experimental correlations. In addition, the influence of the geometric parameters on the...

  9. Interacting kinetics of neutral and ionic species in an atmospheric-pressure helium–oxygen plasma with humid air impurities

    International Nuclear Information System (INIS)

    We unravel the complex chemistry in both the neutral and ionic systems of a radio-frequency-driven atmospheric-pressure plasma in a helium–oxygen mixture (He–0.5% O2) with air impurity levels from 0 to 500 ppm of relative humidity from 0% to 100% using a zero-dimensional, time-dependent global model. Effects of humid air impurity on absolute densities and the dominant production and destruction pathways of biologically relevant reactive neutral species are clarified. A few hundred ppm of air impurity crucially changes the plasma from a simple oxygen-dependent plasma to a complex oxygen–nitrogen–hydrogen plasma. The density of reactive oxygen species decreases from 1016 to 1015 cm−3, which in turn results in a decrease in the overall chemical reactivity. Reactive nitrogen species (1013 cm−3), atomic hydrogen and hydroxyl radicals (1011–1014 cm−3) are generated in the plasma. With 500 ppm of humid air impurity, the densities of positively charged ions and negatively charged ions slightly increase and the electron density slightly decreases (to the order of 1011 cm−3). The electronegativity increases up to 2.3 compared with 1.5 without air admixture. Atomic hydrogen, hydroxyl radicals and oxygen ions significantly contribute to the production and destruction of reactive oxygen and reactive nitrogen species. (paper)

  10. Influence of ambient air on the flowing afterglow of an atmospheric pressure Ar/O2 radiofrequency plasma

    CERN Document Server

    Duluard, C Y; Hubert, J; Reniers, F

    2016-01-01

    The influence of ambient air on the flowing afterglow of an atmospheric pressure Ar/O2 radiofrequency plasma has been investigated experimentally. Spatially resolved mass spectrometry and laser induced fluorescence on OH radicals were used to estimate the intrusion of air in between the plasma torch and the substrate as a function of the torch-to-substrate separation distance. No air is detected, within the limits of measurement uncertainties, for separation distances smaller than 5 mm. For larger distances, the effect of ambient air can no longer be neglected, and radial gradients in the concentrations of species appear. The Ar 4p population, determined through absolute optical emission spectroscopy, is seen to decrease with separation distance, whereas a rise in emission from the N2(C--B) system is measured. The observed decay in Ar 4p and N2(C) populations for separation distances greater than 9mm is partly assigned to the increasing collisional quenching rate by N2 and O2 molecules from the entrained air....

  11. Asymptotic analysis of simple ionization kinetics of air flows at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Degond, Pierre [Mathematiques pour l' Industrie et la Physique, UFR MIG, Universite Paul Sabatier Toulouse 3, 118, route de Narbonne, 31 062 Toulouse cedex 4 (France); Quinio, Geraldine [Mathematiques pour l' Industrie et la Physique, UFR MIG, Universite Paul Sabatier Toulouse 3, 118, route de Narbonne, 31 062 Toulouse cedex 4 (France); Rogier, Francois [Onera centre de Toulouse, Departement Traitement de l' Information et Modelisation, 2, avenue Edouard Belin, 31055 Toulouse cedex (France)

    2005-05-07

    The purpose of this paper is to propose and analyse a simplified model for plasma generation in air flows at atmospheric pressure. The starting point is a model previously proposed by Lowke (1992 J. Phys. D: Appl. Phys. 25 202-10), enriched with a loss term which schematically takes into account the drag of the metastable and ionized species by the flow. An asymptotic analysis of this model confirmed by numerical simulations is proposed and shows that plasma generation is a two or three time scale process (depending on the electric field value). Eventually, the existence of the plasma over long time scales depends on the value of the flow velocity relative to a threshold value, which can be approximately computed analytically. A procedure for generating a plasma at atmospheric pressure in air at low energetic cost is also suggested.

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

    International Nuclear Information System (INIS)

    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 > eUm, where Um is the maximum gap voltage, is relatively small.

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

    Science.gov (United States)

    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. Spatiotemporal relationships between sea level pressure and air temperature in the tropics

    CERN Document Server

    Makarieva, Anastassia M; Nefiodov, Andrei V; Sheil, Douglas; Nobre, Antonio Donato; Li, Bai-Lian Larry

    2014-01-01

    While surface temperature gradients have been highlighted as drivers of low-level atmospheric circulation, the underlying physical mechanisms remain unclear. Lindzen and Nigam (1987) noted that sea level pressure (SLP) gradients are proportional to surface temperature gradients if isobaric height (the height where pressure does not vary in the horizontal plane) is constant; their own model of low-level circulation assumed that isobaric height in the tropics is around 3 km. Recently Bayr and Dommenget (2013) proposed a simple model of temperature-driven air redistribution from which they derived that the isobaric height in the tropics again varies little but occurs higher (at the height of the troposphere). Here investigations show that neither the empirical assumption of Lindzen and Nigam (1987) nor the theoretical derivations of Bayr and Dommenget (2013) are plausible. Observations show that isobaric height is too variable to determine a universal spatial or temporal relationship between local values of air ...

  15. Surface Decontamination of Chemical Agent Surrogates Using an Atmospheric Pressure Air Flow Plasma Jet

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

    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

  17. High Pressure Air Jet in the Endoscopic Preparation Room: Risk of Noise Exposure on Occupational Health

    OpenAIRE

    2015-01-01

    After high-level disinfection of gastrointestinal endoscopes, they are hung to dry in order to prevent residual water droplets impact on patient health. To allow for quick drying and clinical reuse, some endoscopic units use a high pressure air jet (HPAJ) to remove the water droplets on the endoscopes. The purpose of this study was to evaluate the excessive noise exposure with the use of HPAJ in endoscopic preparation room and to investigate the risk to occupational health. Noise assessment w...

  18. Self-Organized Filaments in Dielectric Barrier Discharge in Air at Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    DONG Li-Fang; LI Xue-Chen; YINZeng-Qian; QIAN Sheng-Fa; OUYANG Ji-Ting; WANG Long

    2001-01-01

    The self-organized filament pattern created by dielectric barrier discharges in air at atmospheric pressure is investigated experimentally. The density and dimension of filament are analysed quantitatively. The experimental results show that the distance between neighbouring filaments decreases with the increased applied voltage or with the decreased width of the gas gap. Also, the diameter of the filament decreases with the increased applied voltages or with the decreased width of the gas gap.

  19. Ion composition of a propane-butane-air flame at low pressure

    Energy Technology Data Exchange (ETDEWEB)

    Fialkov, A.B.; Fialkov, B.S.

    1985-06-01

    Ion types and distributions are determined experimentally for propane-butane-air flames with excess oxidizer coefficients of 0.7-1.2 in the pressure range 4-65 KPa. It is shown that nonthermal ionization occurs not only in the known chemiionization zone (which practically coincides with the chemiluminescence zone) but also in the mixture preparation zone. A general mechanism for ion formation in the flame is proposed. 42 references.

  20. Ionic wind generation by a wire-cylinder-plate corona discharge in air at atmospheric pressure

    OpenAIRE

    Colas, Dorian,; Ferret, Antoine; Pai, David,; Lacoste, Deanna,; Laux, C.

    2010-01-01

    A wire-cylinder-plate electrode configuration is presented to generate ionic wind with a dc corona discharge in air at atmospheric pressure. The objective of the work is to maximize the power supplied to the flow in order to increase acceleration while avoiding breakdown. Thus, the proposed experimental setup addresses the problem of decoupling the mechanism of ion generation from that of ion acceleration. Using a wire-plate configuration as a reference, we have focused on improving the topog...

  1. Numerical Modelling of Soot Formation in Laminar Axisymmetric Ethylene-Air Coflow Flames at Atmospheric and Elevated Pressures

    KAUST Repository

    Abdelgadir, Ahmed

    2015-03-30

    A set of coflow diffusion flames are simulated to study the formation, growth, and oxidation of soot in flames of diluted hydrocarbon fuels, with focus on the effects of pressure. Firstly, we assess the ability of a high performance CFD solver, coupled with detailed transport and kinetic models, to reproduce experimental measurements of a series of ethylene-air coflow flames. Detailed finite rate chemistry describing the formation of Polycyclic Aromatic Hydro-carbons is used. Soot is modeled with a moment method and the resulting moment transport equations are solved with a Lagrangian numerical scheme. Numerical and experimental results are compared for various pressures. Finally, a sensitivity study is performed assessing the effect of the boundary conditions and kinetic mechanisms on the flame structure and stabilization properties.

  2. The Air Toxics Health Effects Database (ATHED)

    International Nuclear Information System (INIS)

    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. Air Pressurized Cabin Compressed Air Automatic Control System%空气加压氧舱压缩空气自动控制系统

    Institute of Scientific and Technical Information of China (English)

    郑志满; 张冕; 胡昕; 伍锡勇

    2011-01-01

    This paper describes a air pressurized cabin compressed air automatic control system, the designis simple, practical, safe and reliable.%本文介绍一种空气加压氧舱压缩空气自动控制系统,该设计简单、实用、安全、可靠.

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

    International Nuclear Information System (INIS)

    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

  5. Effect of lemon juice on blood pressure

    OpenAIRE

    SARI, Aysel; SELİM, Nevzat; Melda DİLEK; AYDOĞDU, Turkan; ADIBELLİ, Zelal; BÜYÜKKAYA, Piltan; Akpolat, Tekin

    2012-01-01

    Lemon juice has commonly been used by hypertensive patients in order to lower blood pressure (BP) acutely when BP is raised or as an alternative/complementary therapy for expectation of chronic improvement. Grapefruit, a citrus fruit like lemon, causes clinically significant interactions with a variety of drugs including calcium antagonists. The aims of this study were to investigate acute and chronic effects of lemon juice on BP among hypertensive patients. Ninty-eight patients were included...

  6. Effects of pressure on arterial failure.

    Science.gov (United States)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    Tang Jie; Jiang Weiman; Zhao Wei; Wang Yishan; Li Shibo; Wang Haojing [State Key Laboratory of Transient Optics and Photonics, Xi' an Institute of Optics and Precision Mechanics of CAS, Xi' an 710119 (China); Duan Yixiang [State Key Laboratory of Transient Optics and Photonics, Xi' an Institute of Optics and Precision Mechanics of CAS, Xi' an 710119 (China); Research Center of Analytical Instrumentation, Sichuan University, Chengdu 610064 (China)

    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.

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

    Science.gov (United States)

    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

  9. Analysis of copper surface features obtained using TEA CO2 laser at reduced air pressure

    International Nuclear Information System (INIS)

    Interaction of a transversely excited atmospheric (TEA) CO2 laser with rough copper surface, at reduced air pressure, was studied. Optical pulse duration of the laser employed was ∼2 μs, with the initial spike FWHM of ∼100 ns. Laser energy density of ∼32 J/cm2 (intensity ∼108 W/cm2) was above the plasma ignition threshold. Morphological features of the copper can be summarized as follows: (i) superficial damages, which take crater-shaped form at a higher number of accumulated laser pulses, (ii) development of melt pools with visible bubbles inside the damage region, (iii) formation of solid droplets at near periphery, and (iv) presence of “halo” effect at the irradiated surface. The laser induced surface changes were influenced by the target plasma formation. The formation of plasma influenced the laser–target interaction in two opposite ways: trough absorption of laser energy by the plasma, i.e. trough the effect of plasma shielding, and trough energy transfer from the plasma to the sample. Optical emission spectra were compared for laser induced plasma originated by a single and by cumulative laser pulses. It was found that plasma dimensions and emission intensities have a strong correlation with the number of accumulated laser pulses. Enhancement of both atomic and ionic copper lines was registered when laser induced plasma originated from a single pulse. Chemical analysis of the surface showed a tendency of copper content increase and oxygen content reduction when going from non-irradiated region to the central irradiated region. In the central damage zone, nearly pure copper was present which can be advantageous for some applications due to considerably lower contamination.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. Air-side Particulate Fouling of Microchannel Heat Exchangers: Experimental Comparison of Air-Side Pressure Drop and Heat Transfer with Plate-Fin Heat Exchanger

    OpenAIRE

    Bell, Ian; Groll, Eckhard

    2011-01-01

    In this study, the air-side pressure drop and heat transfer performance of plate-fin and microchannel coils were tested under clean and fouled conditions. The heat exchangers were tested with two different types of dust, ASHRAE Standard Dust and Arizona Road Test Dust. The ASHRAE Standard Dust was found to have a very significant impact on the pressure drop of the microchannel heat exchanger, increasing the air-side pressure drop of the microchannel heat exchanger over 200% for a dust injec...

  12. The Effects of Air Preheating and Fuel/Air Inlet Diameter on the Characteristics of Vortex Flame

    Directory of Open Access Journals (Sweden)

    Mostafa Khaleghi

    2015-01-01

    Full Text Available The effects of fuel/air inlet diameter as well as air preheating on the flame stability, temperature distribution, pollutant formation, and combustion characteristics of a lab-scaled asymmetric vortex flame have been investigated. A three-dimensional steady-state finite volume solver has been used to solve the governing and energy equations. The solver uses a first-order upwind scheme to discretize the governing equations in the space. The semi-implicit method for pressure linked equations has been applied to couple the pressure to the velocity terms. Several turbulence models were applied to predict the flame temperature and it was found that k-ε RNG has given the best results in accordance with the experimental results. The results reveal that the inlet air diameter can enhance the thermal properties and reduce the NOx emission while the inlet fuel diameter has less significant impact. Increasing diameters are accompanied with a pressure drop. It was found that preheating the air and fuel would significantly affect the flame temperature and NOx emission with constant mass flow rate.

  13. Optical and electrical characteristics of air dielectric barrier discharges in mode transition at atmospheric pressure

    International Nuclear Information System (INIS)

    Atmospheric pressure dielectric barrier discharges (DBDs) have a wide range of industrial applications, generally exhibiting either filamentary or diffuse (i.e. glow) discharges. The focus of this investigation is on the formation mechanisms of the discharge current pulse width, on the order of tens of microseconds, accompanied by a light source formation, which is called a light source (LS) mode in air DBDs at atmospheric pressure. From a macroscopic point of view, the characteristics of the discharge current in the LS mode are similar with those of the glow mode. The optical and electrical characteristics of air DBDs at atmospheric pressure are investigated in the transition from the filamentary mode to the LS mode by measuring the optical emission spectroscopy and electrical signals. It is shown that in the manual increasing voltage stage, the vibrational temperature almost never changes and the gas temperature, electron temperature, dielectric capacitance, gas voltage (Vg) and discharge power (P) increase with an increase in the applied voltage. In the automatic decreasing voltage stage, all of these parameters, except Vg and P, increase with a decrease in the voltage. But, when the voltage decreases to a minimum value corresponding to the LS mode, P reaches a maximum value. In this paper, the variations of these parameters are analyzed and discussed in detail. The formation of the LS mode originates from the secondary electrons. The formation mechanisms of the secondary electrons are also discussed. (paper)

  14. Air passenger transport and the greenhouse effect

    International Nuclear Information System (INIS)

    The commercial aviation sector accounts for 2.5 % of total worldwide anthropogenic carbon dioxide (CO2) emissions. Water vapour (H2O) and NOx emissions, the formation of condensation trails and increased formation of cirrus clouds due to altitude (indirect effects) also accentuate the greenhouse effect. The Intergovernmental Panel on Climate Change (IPCC) estimates that the effects apart from CO2 emissions are relatively higher for aviation than for other human activities. For one tonne of CO2 emissions, the radiative forcing of aviation is twice as important as other activities. On this basis, a Paris-New York return trip for one passenger on a charter flight corresponds to a quarter of the total climate impact caused by the annual consumption of a French person. Increased mobility and a rise in international tourism suggest that past trends in the growth of air passenger transport will continue. The improvements in energy efficiency achieved are seemingly not sufficient to prevent a significant increase in the impact of air transport on climate change. (author)

  15. Effect of actual vapor pressure on estimating evapotranspiration at Serbia

    OpenAIRE

    Trajković Slaviša; Živković Svetlana

    2009-01-01

    Actual vapor pressure (VP) is an important parameter that is used in many evapotranspiration equations. However, vapor pressure is difficult to measure accurately. In the humid climate, the actual vapor pressure can be derived from minimum air temperature. The objectives of this study were: first, to estimate errors that can arise if VP data are not available and have to be estimated; second, to compare the Priestley-Taylor ET0 values computed under various levels of VP data availability; and...

  16. Effective air thickness in a glass capillary for the in-air material analysis

    International Nuclear Information System (INIS)

    In order to establish in-air material analysis techniques with a glass capillary, we have measured energy distributions of extracted alpha particles in air using the glass capillary. We have estimated the effective air thickness in the glass capillary and found it to be compatible with a simple calculation. (paper)

  17. Deactivating bacteria with RF Driven Hollow Slot Microplasmas in Open Air at Atmospheric Pressure

    Science.gov (United States)

    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.

  18. Mitigation effects of radon decay products by air cleaner

    International Nuclear Information System (INIS)

    One of the most effective methods for reducing exposure is the use of air cleaners. In this study, a dose mitigation of a commonly-used Japanese air cleaner under conditions in which aerosols are continuously supplied was investigated. Although the values of the EERC during an operation of air cleaner decreased, values of the fp increased with the use of air cleaner. An effective dose was calculated on the basis of our experimental results, resulting in the dose mitigation of about 40 % by the air cleaner. Air cleaners can be regarded as an effective tool for the dose mitigation under with conditions in which aerosols are continuously supplied. (author)

  19. Characterization of atmospheric pressure plasma treated pure cashmere and wool/cashmere textiles: Treatment in air/water vapor mixture

    Energy Technology Data Exchange (ETDEWEB)

    Zanini, Stefano, E-mail: stefano.zanini@mib.infn.it [Università degli Studi di Milano-Bicocca, Dipartimento di Fisica “G. Occhialini”, p.za della Scienza, 3, I-20126 Milano (Italy); Grimoldi, Elisa [Università degli Studi di Milano-Bicocca, Dipartimento di Fisica “G. Occhialini”, p.za della Scienza, 3, I-20126 Milano (Italy); Citterio, Attilio [Politecnico di Milano, Dipartimento di Chimica, Materiali ed Ingegneria Chimica “G. Natta”, Via Mancinelli 7, I-20131 Milano (Italy); Riccardi, Claudia, E-mail: riccardi@mib.infn.it [Università degli Studi di Milano-Bicocca, Dipartimento di Fisica “G. Occhialini”, p.za della Scienza, 3, I-20126 Milano (Italy)

    2015-09-15

    Highlights: • We treated cashmere and wool/cashmere textiles with atmospheric pressure plasma. • Wettability of the fabrics was increased. • The increment in wettability derived from a surface oxidation of the fibers. • Only minor etching effects were observed with scanning electron microscopy. - Abstract: We performed atmospheric pressure plasma treatments of pure cashmere and wool/cashmere textiles with a dielectric barrier discharge (DBD) in humid air (air/water vapor mixtures). Treatment parameters have been optimized in order to enhance the wettability of the fabrics without changing their bulk properties as well as their touch. A deep characterization has been performed to study the wettability, the surface morphologies, the chemical composition and the mechanical properties of the plasma treated textiles. The chemical properties of the plasma treated samples were investigated with attenuated total reflectance Fourier transform infrared (FTIR/ATR) spectroscopy and X-ray photoelectron microscopy (XPS). The analyses reveal a surface oxidation of the treated fabrics, which enhances their surface wettability. Morphological characterization of the treated fibers with scanning electron microscopy (SEM) reveals minor etching effects, an essential feature for the maintenance of the textile softness.

  20. Characterization of atmospheric pressure plasma treated pure cashmere and wool/cashmere textiles: Treatment in air/water vapor mixture

    International Nuclear Information System (INIS)

    Highlights: • We treated cashmere and wool/cashmere textiles with atmospheric pressure plasma. • Wettability of the fabrics was increased. • The increment in wettability derived from a surface oxidation of the fibers. • Only minor etching effects were observed with scanning electron microscopy. - Abstract: We performed atmospheric pressure plasma treatments of pure cashmere and wool/cashmere textiles with a dielectric barrier discharge (DBD) in humid air (air/water vapor mixtures). Treatment parameters have been optimized in order to enhance the wettability of the fabrics without changing their bulk properties as well as their touch. A deep characterization has been performed to study the wettability, the surface morphologies, the chemical composition and the mechanical properties of the plasma treated textiles. The chemical properties of the plasma treated samples were investigated with attenuated total reflectance Fourier transform infrared (FTIR/ATR) spectroscopy and X-ray photoelectron microscopy (XPS). The analyses reveal a surface oxidation of the treated fabrics, which enhances their surface wettability. Morphological characterization of the treated fibers with scanning electron microscopy (SEM) reveals minor etching effects, an essential feature for the maintenance of the textile softness

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

    Directory of Open Access Journals (Sweden)

    Rachel Schofield

    2013-01-01

    Full Text Available 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.

  2. Evaluative pressure overcomes perceptual load effects.

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

    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

  7. Research Update: Direct conversion of amorphous carbon into diamond at ambient pressures and temperatures in air

    International Nuclear Information System (INIS)

    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

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

    DEFF Research Database (Denmark)

    Zhu, Jiajian; Gao, Jinlong; Li, Zhongshan;

    2014-01-01

    Rapid transition from glow discharge to thermal arc has been a common problem in generating stable high-power non-thermal plasmas especially at ambient conditions. A sustained diffusive gliding arc discharge was generated in a large volume in atmospheric pressure air, driven by an alternating......, synchronized with simultaneously recorded current and voltage waveforms. Dynamic details of the novel non-equilibrium discharge are revealed, which is characterized by a sinusoidal current waveform with amplitude stabilized at around 200 mA intermediate between thermal arc and glow discharge, shedding light to...

  9. Energy transfer from a laser pulse to a blast wave in reduced-pressure air atmospheres

    International Nuclear Information System (INIS)

    Focusing a transversely excited atmospheric CO2 laser beam in air atmospheres induced a blast wave. The kinetic energy of a laser-induced blast wave was determined from shadowgraph images of shock wave expansion. Results showed that the fraction of input laser energy that is converted into the blast wave energy decreased from 0.45 to 0.2 concomitant with the decrease in ambient pressure from 100 to 10 kPa. Also, it was insensitive to input laser energy from 4 to 13 J

  10. Air pollution epidemiology. Assessment of health effects and risks

    Energy Technology Data Exchange (ETDEWEB)

    Katsouyanni, K. [Athens Univ. (Greece). Dept. of Hygiene and Epidemiology

    1995-12-31

    Air pollution epidemiology is the study of the occurrence and distribution of health outcomes in association with community air pollution exposure. It is therefore specific in the exposure variable. Air pollution health effects became evident during high air pollution episodes which occurred in the first decades of our century. Since then, legal and other control measures have led to lower air pollution levels. However, recent results from several studies indicate that lower levels of air pollution than the previously considered safe have serious adverse health effects. Although, there is increasingly agreement that air pollution, at levels measured today, affects health, there is still a lot to be understood concerning specific causal pollutants, biologic mechanisms involved and sensitive groups of individuals. The extent of potential confounding, time-considerations in air pollution effects, individual variation in air pollution exposure and exposure misclassification are some factors which complicate the study of these issues. (author)

  11. Bifurcation and Nonlinear Dynamic Analysis of Externally Pressurized Double Air Films Bearing System

    Directory of Open Access Journals (Sweden)

    Cheng-Chi Wang

    2014-01-01

    Full Text Available This paper studies the chaotic and nonlinear dynamic behaviors of a rigid rotor supported by externally pressurized double air films (EPDAF bearing system. A hybrid numerical method combining the differential transformation method and the finite difference method is used to calculate pressure distribution of EPDAF bearing system and bifurcation phenomenon of rotor center orbits. The results obtained for the orbits of the rotor center are in good agreement with those obtained using the traditional finite difference approach. The results presented summarize the changes which take place in the dynamic behavior of the EPDAF bearing system as the rotor mass and bearing number are increased and therefore provide a useful guideline for the bearing system.

  12. High power laser interaction effects with metallic pressure vessel

    Science.gov (United States)

    Das, Nilratan; Mukherji, D.; Kumar, R.; Husain, M.; Zaidi, Z. H.; Kumar, Anil

    2006-05-01

    The paper describes the theoretical and experimental investigation of high power Gas Dynamic Laser(GDL, λ~10.6μm) interaction studies with a pressurized hollow metal(MS) target. The design and development of such type of target which has been shown bursting as well as burning effect at the time of interaction have been carried out. It has been filled by gas mixture of H II and Air in the range of flammability limit. Various parameters like power density, target thickness, filling pressure, mixture ratio etc have been optimized. High mass flow GDL of power level about several KW in unstable mode provides power density about 3.2 KW/Cm2 by a beam delivery system at distance 25m. Since target material is thin and heat diffuses through it rapidly, by maintaining the required power density, rupturing is accomplished by heating an area of the pressure vessel to a temperature at which it will fail under the pressure load. Rupture initiates a propagating crack which spreads the damage over a large fraction of the pressure vessel. The gas mixture ignites due to its contact with atmosphere and explodes with a massive sound level of the order of 130dB. The sound level was measured by a Decibel meter. Temperature distribution along radial and depth have been studied theoretically. Surface temperature during interaction has been measured. Experimental data has been validated with theory. These study shows a very attractive demonstration showing potentiality of scientific applications of High Power CO II Laser.

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

    Science.gov (United States)

    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. Pressurization rate effect on ligament rupture and burst pressures of cracked steam generator tubes

    International Nuclear Information System (INIS)

    The question of whether ligament rupture pressure or unstable burst pressure may vary significantly with pressurization rate at room temperature arose from the results of pressure tests by industry on tubes with machined part-throughwall notches. Slow (quasi-static) and fast 14 MPa/s (2000 psi/s) pressurization rate tests on specimens with nominally the same notch geometry appeared to show a significant effect of the rate of pressurization on the unstable burst pressure. Unfortunately, the slow and fast loading rate tests were conducted following two different test procedures, which could confound the results. The current series of tests were conducted on a variety of specimen geometries using a consistent test procedure to better establish the effect of pressurization rate on ligament rupture and burst pressures. (author)

  15. Aerosols generated by releases of pressurized powders and solutions in static air

    International Nuclear Information System (INIS)

    Safety assessments and environmental impact statements for nuclear fuel cycle facilities require an estimate of potential airborne releases caused by accidents. Aerosols generated by accidents are being investigated by Pacific Northwest Laboratory to develop the source terms for these releases. An upper boundary accidental release event would be a pressurized release of powder or liquid in static air. Experiments were run using various source sizes and pressures and measuring the mass airborne and the particle size distribution of aerosols produced by these pressurized releases. Two powder and two liquid sources were used: TiO2 and depleted uranium dioxide (DUO); and aqueous uranine (sodium fluorescein) and uranyl nitrate solutions. Results of the experiments showed that pressurization level and source size were significant variables for the airborne powder releases. For this experimental configuration, the liquid releases were a function of pressure, but volume did not appear to be a significant variable. During the experiments 100 g and 350 g of DUO (1 μm dia) and TiO2 (1.7 μm dia) powders and 100 cm3 and 350 cm3 of uranine and uranyl nitrate solutions were released at pressures ranging from 50 to 500 psig. The average of the largest fractions of powder airborne was about 24%. The maximum amount of liquid source airborne was significantly less, about 0.15%. The median aerodynamic equivalent diameters (AED) for collected airborne powders ranged from 5 to 19 μm; liquids ranged from 2 to 29 μm. All of the releases produced a significant fraction of respirable particles of 10 μm and less. 12 references, 10 figures, 23 tables

  16. Laser-based measurements of OH in high pressure CH4/air flames

    Science.gov (United States)

    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.

  17. Effect of overbalance pressure on formation damage

    Energy Technology Data Exchange (ETDEWEB)

    Jilani, S.Z.; Menouar, H.; Al-Majed, A.A. [Center for Petroleum and Minerals, The Research Institute, King Fahd University of Petroleum and Minerals, Mail Box 2002, 31261 Dhahran (Saudi Arabia); Khan, M.A. [Center for Applied Physical Sciences, The Research Institute, King Fahd University of Petroleum and Minerals, 31261 Dhahran (Saudi Arabia)

    2002-10-01

    Experiments were conducted to investigate the influence of overbalance pressure on formation damage during drilling operations. An innovative ultrasonic method was employed to measure mud invasion depth. It was observed that mud invasion depth decreases with increasing overbalance pressure until it reaches a critical pressure. Beyond that, invasion depth increases with overbalance pressure. The above phenomenon reflects a strong physical relationship between overbalance pressure and mud fines and filtrate invasion depth.

  18. Effects of diameter and air inlet on flooding

    International Nuclear Information System (INIS)

    The effects of diameter and air inlet on flooding and flow reverse have been studied by experiment. Experimental results indicated that when resistance reduced at the air inlet, air flow rate at the onset of flooding will rise in some conditions. On right angle, the inlet conditions do not effect flooding points. When air inlet is well-rounded, the tube diameters have effects on the points. Air inlet has effects on complete carry up, but tube diameter no effects on that, the smaller of diameter, the larger of Jg* in complete carry up. Diameter and air inlet have no effects on flow reverse. Air inlet does not effect flooding but the tube diameter does

  19. The effect of a photocatalytic air purifier on indoor air quality quantified using different measuring methods

    DEFF Research Database (Denmark)

    Kolarik, Barbara; Wargocki, Pawel; Skorek-Osikowska, A.;

    2010-01-01

    Chromatography/Mass Spectrometry and High-Pressure Liquid Chromatography with UV detection). The experiment was conducted in a simulated office, ventilated with 0.6 h(-1), 2.5 h(-1) and 6 h(-1), in the presence of additional pollution sources (carpet, chipboard and linoleum). At the lowest air change rate...... air quality, as documented by sensory assessments made by human subjects. It also reduces concentrations of many chemical compounds present in the air as documented by the PTR-MS technique. For the lowest ventilation, results from measurements using the chromatographic methods have similar tendency...

  20. Effect of high pressure on mesophilic lactic fermentation streptococci

    Energy Technology Data Exchange (ETDEWEB)

    Reps, A; Kuzmicka, M; Wisniewska, K [Chair of Food Biotechnology, University of Warmia and Mazury, ul. Heweliusza 1, 10-724 Olsztyn (Poland)], E-mail: arnold.reps@uwm.edu.pl

    2008-07-15

    The research concerned the effect of high pressure on mesophilic lactic fermentation streptococci, present in two cheese-making commercial inocula produced by Christian-Hansen. Water solutions of inocula were pressurized at 50-800 MPa, at room temperature, for 30-120 min. Pressurization at 50-100 MPa slightly increased or reduced the number of lactic streptococci, depending on the inoculum and pressurization time. Pressurization at 200 MPa caused a reduction in the number of streptococci by over 99.9%, whereas the pressure of 400 MPa and above almost completely inactivated streptococci. Pressurization also reduced the dynamics of microorganism growth and acidification, to the degree depending on the pressure.

  1. On the use of pulsed Dielectric Barrier Discharges to control the gas-phase composition of atmospheric pressure air plasmas

    International Nuclear Information System (INIS)

    We presents results obtained from the numerical simulation of the gas-phase chemical kinetics in atmospheric pressure air non-equilibrium plasmas. In particular we have addressed the effect of pulsed operation mode of a plane dielectric barrier discharge. It was conjectured that the large difference in the time scales involved in the fast dissociation of oxygen molecules in plasma and their subsequent reactions to produce ozone and nitrogen oxides, makes the presence of a continuously repeated plasma production unnecessary and a waste of electrical power and thus efficiency. In order to test such suggestion we have performed a numerical study of the composition and the temporal evolution of the gas-phase of atmospheric pressure air non-equilibrium plasmas. Comparison with experimental findings in a dielectric barrier discharge with an electrode configuration symmetrical and almost ideally plane is briefly addressed too, using plasma diagnostics to extract the properties of the single micro-discharges and a sensor to measure the concentration of ozone produced by the plasma

  2. Effect of free-air nuclei on fully developed individual bubble cavitation

    International Nuclear Information System (INIS)

    Fully developed individual-bubble cavitation was studied. Nuclei population and pressure distribution at the boundary of a cavitating converging-diverging test section were measured. It was shown that some cavitation tests can only yield valid results if the free air content of the water is known. During the initial stages of bubble growth the wall pressure in the cavitation region is lower than the vapor pressure. Wall pressure rises later. For a given cavitation number and flow velocity, the pressure distribution depends on the number of expanding bubbles on the hydrofoil. Minimum pressure coefficient depends only on the cavitation number, the flow velocity and the number of expanding bubbles present. Bubbles generate pressure pulses at the wall; combined effect of all such pulses is to shift the wall pressure away from the value that would be obtained at the same cavitation number if no cavitation was present. The greater the number of expanding bubbles, the more the wall pressure tends to approach the vapor pressure. An important result of the work is to pin-point free air contents of water tunnel which lead to correct scaling of cavitation flows

  3. Analysis of Environmental Effects on Leaf Temperature under Sunlight, High Pressure Sodium and Light Emitting Diodes

    OpenAIRE

    Nelson, Jacob A.; Bugbee, Bruce

    2015-01-01

    The use of LED technology is commonly assumed to result in significantly cooler leaf temperatures than high pressure sodium technology. To evaluate the magnitude of this effect, we measured radiation incident to and absorbed by a leaf under four radiation sources: clear sky sunlight in the field, sunlight in a glass greenhouse, and indoor plants under either high pressure sodium or light emitting diodes. We then applied a common mechanistic energy-balance model to compare leaf to air temperat...

  4. A Novel Constant-Pressure Pumped Hydro Combined with Compressed Air Energy Storage System

    Directory of Open Access Journals (Sweden)

    Erren Yao

    2014-12-01

    Full Text Available As intermittent renewable energy is receiving increasing attention, the combination of intermittent renewable energy with large-scale energy storage technology is considered as an important technological approach for the wider application of wind power and solar energy. Pumped hydro combined with compressed air energy storage system (PHCA is one of the energy storage systems that not only integrates the advantages but also overcomes the disadvantages of compressed air energy storage (CAES systems and pumped hydro energy storage systems to solve the problem of energy storage in China’s arid regions. Aiming at the variable working conditions of PHCA system technology, this study proposes a new constant-pressure PHCA. The most significant characteristics of this system were that the water pump and hydroturbine work under stable conditions and this improves the working efficiency of the equipment without incurring an energy loss. In addition, the constant-pressure PHCA system was subjected to energy and exergy analysis, in expectation of exploring an attractive solution for the large-scale storage of existing intermittent renewable energy.

  5. Emission spectroscopy of an atmospheric pressure plasma jet operated with air at low frequency

    Science.gov (United States)

    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.

  6. Surface treatment of high density polyethylene (HDPE) film by 50 Hz dielectric barrier discharge produced in air and argon/air mixture at atmospheric pressure

    OpenAIRE

    Joshi Ujjwal Man; Subedi Deepak Prasad

    2015-01-01

    Thin films of high density polyethylene (HDPE) are treated for improving hydrophilicity using non-thermal plasma generated by 50 Hz line frequency dielectric barrier discharge produced in air and argon/air mixture at atmospheric pressure. HDPE samples before and after the treatment are studied using contact angle measurements, surface free energy calculations and atomic force microscopy (AFM). Distilled water (H2O), glycerol (C3H8O3) and diiodomethane (CH2I2) are used as test liqu...

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

    Science.gov (United States)

    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.

  8. Letter to the Editor: Applications Air Q Model on Estimate Health Effects Exposure to Air Pollutants

    OpenAIRE

    , Gholamreza Goudarzi; Sahar Geravandi; Elaheh Jame Porazmey; Mohammad Javad Mohammadi

    2016-01-01

    Epidemiologic studies in worldwide have measured increases in mortality and morbidity associated with air pollution (1-3). Quantifying the effects of air pollution on the human health in urban area causes an increasingly critical component in policy discussion (4-6). Air Q model was proved to be a valid and reliable tool to predicts health effects related to criteria  pollutants (particulate matter (PM), ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2), and carbon monoxide (CO)),...

  9. Effects of vegetarian diets on blood pressure

    Directory of Open Access Journals (Sweden)

    Yokoyama Y

    2016-04-01

    Full Text Available Yoko Yokoyama,1,2 Kazuo Tsubota,2,3 Mitsuhiro Watanabe1,2,4,5 1Graduate School of Media and Governance, Keio University, Fujisawa, Kanagawa, 2Health Science Laboratory, 3Department of Ophthalmology, 4Department of Internal Medicine, Keio University School of Medicine, Tokyo, 5Faculty of Environment and Information Studies, Keio University, Fujisawa, Kanagawa, Japan Abstract: Hypertension is a major independent risk factor for coronary artery diseases, and the prevalence of hypertension is continuously increasing. Diet is an important factor that can be modified to prevent hypertension. According to the US Department of Health and Human Services, dietary patterns are defined as the quantities, proportions, and variety or combinations of different foods and beverages in diets and the frequency with which they are habitually consumed. In this review, the vegetarian dietary pattern is introduced with a focus on the effect on blood pressure (BP. Although the available evidence is limited, according to a previous meta-analysis of controlled trials, vegetarian dietary patterns significantly reduced systolic and diastolic BPs. One of the common features of a vegetarian diet is weight loss, which might, at least partially, explain the effect on BP. Other possible factors such as sodium, potassium, protein, amino acids, vitamin B-12, antioxidants, fiber, and the microbiome are introduced as possible mechanisms. Further studies are needed with non-Western populations to determine the most effective vegetarian dietary pattern and to explore the exact mechanisms by which these dietary patterns affect BP. Keywords: vegetarian diet, plant-based diet, blood pressure, hypertension, meta-analysis

  10. The Impact of Air Exchange Effectiveness on Thermal Comfort in an Air-Conditioned Office

    Directory of Open Access Journals (Sweden)

    Roonak Daghigh

    2009-01-01

    Full Text Available Problem statement: Impact of air exchange effectiveness on thermal comfort has not been investigated and, therefore, not well understood .Therefore, the influence of air exchange effectiveness on thermal comfort is investigated in this study. Approach: The main objective of this research is to investigate the thermal comfort level of an air-conditioned office room under 14 windows-door opening arrangements as a function of maximum, minimum and mean Air Exchange Effectiveness (AEE, as has not been inquired into already. The tracer gas decay method has been applied during the experimental procedures to estimate air exchange effectiveness, on the basis of room average and local mean age of air. Simultaneously, thermal comfort variables were measured and through these data, the thermal comforts Fanger's indices (PMV and PPD were calculated. Staff answered a survey on their sensation of the indoor climate. Results: Results of 60 survey responses to thermal comfort questions in office and indoor air quality are presented. This study has shown that there are relationship between AEE and thermal comfort and three linear regression equations of PMV versus AEE can be derived for this air-conditioned office. Conclusion: Studies on the effect of air exchange effectiveness on thermal comfort in an office have shown that Thermal comfort is influenced by AEE, which go beyond the six factors which have been taken into account in PMV modeling.

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

    Science.gov (United States)

    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.

  12. Atmospheric effects on extensive air showers observed with the Surface Detector of the Pierre Auger Observatory

    CERN Document Server

    2009-01-01

    Atmospheric parameters, such as pressure (P), temperature (T) and density, 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 pressure and density. The former affects the longitudinal development of air showers while the latter influences the Moliere 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.

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

    Science.gov (United States)

    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 ...

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

    Science.gov (United States)

    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

  15. Air

    International Nuclear Information System (INIS)

    In recent years several regulations and standards for air quality and limits for air pollution were issued or are in preparation by the European Union, which have severe influence on the environmental monitoring and legislation in Austria. This chapter of the environmental control report of Austria gives an overview about the legal situation of air pollution control in the European Union and in specific the legal situation in Austria. It gives a comprehensive inventory of air pollution measurements for the whole area of Austria of total suspended particulates, ozone, volatile organic compounds, nitrogen oxides, sulfur dioxide, carbon monoxide, heavy metals, benzene, dioxin, polycyclic aromatic hydrocarbons and eutrophication. For each of these pollutants the measured emission values throughout Austria are given in tables and geographical charts, the environmental impact is discussed, statistical data and time series of the emission sources are given and legal regulations and measures for an effective environmental pollution control are discussed. In particular the impact of fossil-fuel power plants on the air pollution is analyzed. (a.n.)

  16. Pressure effect on subtilisin crystallization and solubility

    Science.gov (United States)

    Webb, J. N.; Waghmare, R. Y.; Carpenter, J. F.; Glatz, C. E.; Randolph, T. W.

    1999-09-01

    High pressures (135 and 200 MPa) arrested the crystallization process in unseeded batch crystallizations of subtilisin conducted at 25°C over a period of seven days. Crystallization resumed at the normal atmospheric pressure rate once batches were depressurized and the active soluble enzyme concentration decayed to the same value as seen in atmospheric crystallizations. Solubility experiments conducted at 25°C showed an exponential increase in apparent solubility with pressure. The solubility increased approximately five-fold at 200 MPa. The partial molar volume change of crystallization for this increase in solubility with pressure is +21±1 ml/mol. Solubility changes with pressure are largely responsible for the arrest in crystallization rate at high pressure. Experiments on pH-pressure and ionic strength-pressure interactions showed that the change in apparent solubility is not due to pressure-induced changes in pH and ionic strength. For comparative purposes, solubility data as a function of pressure were collected on lysozyme. A linear dependence of lysozyme solubility with pressure was observed, with a 40% increase in apparent solubility after incubation for seven days at 210 MPa and 25°C.

  17. Numerical Modelling of Soot Formation in Laminar Axisymmetric Ethylene-Air Coflow Flames at Atmospheric and Elevated Pressures

    KAUST Repository

    Rakha, Ihsan Allah

    2015-05-01

    The steady coflow diffusion flame is a widely used configuration for studying combustion kinetics, flame dynamics, and pollutant formation. In the current work, a set of diluted ethylene-air coflow flames are simulated to study the formation, growth, and oxidation of soot, with a focus on the effects of pressure on soot yield. Firstly, we assess the ability of a high performance CFD solver, coupled with detailed transport and kinetic models, to reproduce experimental measurements, like the temperature field, the species’ concentrations and the soot volume fraction. Fully coupled conservation equations for mass, momentum, energy, and species mass fractions are solved using a low Mach number formulation. Detailed finite rate chemistry describing the formation of Polycyclic Aromatic Hydrocarbons up to cyclopenta[cd]pyrene is used. Soot is modeled using a moment method and the resulting moment transport equations are solved with a Lagrangian numerical scheme. Numerical and experimental results are compared for various pressures. Reasonable agreement is observed for the flame height, temperature, and the concentrations of various species. In each case, the peak soot volume fraction is predicted along the centerline as observed in the experiments. The predicted integrated soot mass at pressures ranging from 4-8 atm, scales as P2.1, in satisfactory agreement with the measured integrated soot pressure scaling (P2.27). Significant differences in the mole fractions of benzene and PAHs, and the predicted soot volume fractions are found, using two well-validated chemical kinetic mechanisms. At 4 atm, one mechanism over-predicts the peak soot volume fraction by a factor of 5, while the other under-predicts it by a factor of 5. A detailed analysis shows that the fuel tube wall temperature has an effect on flame stabilization.

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

    Science.gov (United States)

    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

  19. A global ground truth view of the lunar air pressure tide L2

    Science.gov (United States)

    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.

  20. Systematic Review: Is Prescription of Pressure-relieving Air Cushions Justified in Acute and Subacute Settings?

    Directory of Open Access Journals (Sweden)

    Alyce Folan

    2015-12-01

    Conclusion: Whilst there is currently preliminary evidence to support the effectiveness of pneumatic pressure-relieving cushions as compared to standard foam, specific recommendations as to a preferred make/model of cushion for use within general hospital settings are not supported at this time.

  1. Air plasma effect on dental disinfection

    Energy Technology Data Exchange (ETDEWEB)

    Duarte, S.; Murata, R. M.; Saxena, D. [Department of Basic Sciences and Craniofacial Biology, College of Dentistry, New York University, New York, New York 10010 (United States); Kuo, S. P.; Chen, C. Y.; Huang, K. J. [Department of Electrical and Computer Engineering, Polytechnic Institute of New York University, Brooklyn, New York 11202 (United States); Popovic, S. [Department of Physics, Old Dominion University, Norfolk, Virginia 23529 (United States)

    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.

  2. Assessment of Effects of Air Pollution on Daily Outpatient Visits using the Air Quality Index

    OpenAIRE

    Mu, Haosheng; Otani, Shinji; Okamoto,Mikizo; Yokoyama, Yae; Tokushima, Yasuko; Onishi, Kazunari; Hosoda, Takenobu; KUROZAWA, Youichi

    2014-01-01

    Background The air quality index (AQI) is widely used to characterize the quality of ambient air. Chinese cities officially report the AQI on a daily basis. To assess the possible effects of air pollution on daily outpatient visits, we examined the association between AQI and the daily outpatient count. Methods Daily data on outpatient visits to each clinical department were collected from the Z county hospital of Datong City, China. The collection period was between 5 April and 30 June, 2012...

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

    Science.gov (United States)

    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.

  4. Simulations of nanosecond-pulsed dielectric barrier discharges in atmospheric pressure air

    Energy Technology Data Exchange (ETDEWEB)

    Soo Bak, Moon; Cappelli, Mark A. [Mechanical Engineering Department, Stanford University, Stanford, California 94305 (United States)

    2013-03-21

    This paper describes simulations of nanosecond pulse plasma formation between planer electrodes covered by dielectric barriers in air at atmospheric pressure and 340 K. The plasma formation process starts as electrons detach from negative ions of molecular oxygen that are produced from the previous discharge pulse. An ionization front is found to form close to the positively biased electrode and then strengthens and propagates towards the grounded electrode with increasing gap voltage. Charge accumulation and secondary emission from the grounded electrode eventually lead to sheath collapse. One interesting feature is a predicted reversal in gap potential due to the accumulated charge, even when there is no reversal in applied potential. The simulation results are compared to recent measurement of mid-gap electric field under the same discharge conditions [Ito et al., Phys. Rev. Lett. 107, 065002 (2011)].

  5. Supershort electron beam and voluminous heavy-current air discharge at atmospheric pressure

    International Nuclear Information System (INIS)

    The conditions of the electron beam and voluminous discharge formation in the air at the atmospheric pressure and subnanosecond pulse tension front are studied. It is shown that the electron beam in the gaseous diode originates at the pulse tension front over time of ∼ 0.5 ns and has duration at the semiheight of ≤0.4 ns. The electron beam with the electrons average energy of 60-80 keV and current amplitude of ≥70 A is obtained. It is assumed that the electron beam is formed from the electron avalanches, originating in the gap on the account of the gas ionization by fast electrons at achieving the critical field between the expanding plasma cloud front and anode

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

    International Nuclear Information System (INIS)

    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. (15th asian conference on electrical discharge)

  7. Integrated LTCC Pressure/Flow/Temperature Multisensor for Compressed Air Diagnostics†

    Directory of Open Access Journals (Sweden)

    Nicolas Craquelin

    2010-12-01

    Full Text Available 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.

  8. Instabilities and soot formation in spherically expanding, high pressure, rich, iso-octane-air flames

    Energy Technology Data Exchange (ETDEWEB)

    Lockett, R D [School of Engineering and Mathematical Sciences, City University, Northampton Square, London EC1V OHB (United Kingdom)

    2006-07-15

    Flame instabilities, cellular structures and soot formed in high pressure, rich, spherically expanding iso-octane-air flames have been studied experimentally using high speed Schlieren cinematography, OH fluorescence, Mie scattering and laser induced incandescence. Cellular structures with two wavelength ranges developed on the flame surface. The larger wavelength cellular structure was produced by the Landau-Darrieus hydrodynamic instability, while the short wavelength cellular structure was produced by the thermal-diffusive instability. Large negative curvature in the short wavelength cusps caused local flame quenching and fracture of the flame surface. In rich flames with equivalence ratio {phi} > 1.8, soot was formed in a honeycomb-like structure behind flame cracks associated with the large wavelength cellular structure induced by the hydrodynamic instability. The formation of soot precursors through low temperature pyrolysis was suggested as a suitable mechanism for the initiation of soot formation behind the large wavelength flame cracks.

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

    Science.gov (United States)

    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

  10. Ultrasound enhanced plasma treatment of glass-fibre-reinforced polyester in atmospheric pressure air for adhesion improvement

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Singh, Shailendra Vikram; Norrman, Kion;

    2011-01-01

    A glass-fibre-reinforced polyester (GFRP) plate was treated with dielectric barrier discharge (DBD) at atmospheric pressure in air for adhesion improvement. The effects of ultrasonic irradiation using a high-power gas-jet generator during the treatment were investigated. The optical emission...... spectrum of the discharge remained almost unchanged by the ultrasonic irradiation, indicating that the bulk property of the discharge was not significantly influenced by the ultrasound. However, the ultrasonic irradiation during the plasma treatment suppressed occasional arcing in the DBD, preventing...... damage of the GFRP plates. The polar component of the surface energy of the polyester plate was 21 mJ/m2 before the treatment, increased markedly to 52 mJ/m2 after 2-s plasma treatment without ultrasonic irradiation, and further increased slightly after longer treatments. In addition, the polar component...

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

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

    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.

  13. An air-pressure-free elastomeric valve for integrated nucleic acid analysis by capillary electrophoresis

    Science.gov (United States)

    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.

  14. An air-pressure-free elastomeric valve for integrated nucleic acid analysis by capillary electrophoresis

    International Nuclear Information System (INIS)

    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. (paper)

  15. THE EFFECTS OF AREA CONTRACTION ON SHOCK WAVE STRENGTH AND PEAK PRESSURE IN SHOCK TUBE

    Directory of Open Access Journals (Sweden)

    A. M. Mohsen

    2012-06-01

    Full Text Available This paper presents an experimental investigation into the effects of area contraction on shock wave strength and peak pressure in a shock tube. The shock tube is an important component of the short duration, high speed fluid flow test facility, available at the Universiti Tenaga Nasional (UNITEN, Malaysia. The area contraction was facilitated by positioning a bush adjacent to the primary diaphragm section, which separates the driver and driven sections. Experimental measurements were performed with and without the presence of the bush, at various diaphragm pressure ratios, which is the ratio of air pressure between the driver (high pressure and driven (low pressure sections. The instantaneous static pressure variations were measured at two locations close to the driven tube end wall, using high sensitivity pressure sensors, which allow the shock wave strength, shock wave speed and peak pressure to be analysed. The results reveal that the area contraction significantly reduces the shock wave strength, shock wave speed and peak pressure. At a diaphragm pressure ratio of 10, the shock wave strength decreases by 18%, the peak pressure decreases by 30% and the shock wave speed decreases by 8%.

  16. Localized etching of polymer films using an atmospheric pressure air microplasma jet

    International Nuclear Information System (INIS)

    A direct-write process device based on the atmospheric pressure air microplasma jet (AμPJ) has been developed for the localized etching of polymer films. The plasma was generated by the air discharge ejected out through a tip-nozzle (inner diameter of 100 μm), forming the microplasma jet. The AμPJ was capable of reacting with the polymer surface since it contains a high concentration of oxygen reactive species and thus resulted in the selective removal of polymer films. The experimental results demonstrated that the AμPJ could fabricate different microstructures on a parylene-C film without using any masks or causing any heat damage. The etch rate of parylene-C reached 5.1 μm min−1 and microstructures of different depth and width could also be realized by controlling two process parameters, namely, the etching time and the distance between the nozzle and the substrate. In addition, combining XPS analysis and oxygen-induced chemical etching principles, the potential etching mechanism of parylene-C by the AμPJ was investigated. Aside from the etching of parylene-C, micro-holes on the photoresist and polyimide film were successfully created by the AμPJ. In summary, maskless pattern etching of polymer films could be achieved using this AμPJ. (paper)

  17. Heat transfer and pressure drop for air-water mixtures in an isoflux vertical annulus

    Energy Technology Data Exchange (ETDEWEB)

    Khattab, M. [Nuclear Research Center, Cairo (Egypt); El-Sallak, M. [Cairo Univ. (Egypt); Morcos, S.M. [Cairo Univ. (Egypt); Salama, A. [Nuclear Research Center, Cairo (Egypt)

    1996-05-01

    Heat transfer and pressure drop in flows of air-water mixtures have been investigated experimentally in an isoflux vertical annulus. The superficial liquid Reynolds number, as a reference parameter, varied from 4500 to 30 000, at different values of gas-to-liquid superficial velocity ratios up to 20 and surface heat fluxes from 50 to 240 kW/m{sup 2}. Enhancement of the two-phase heat transfer coefficient is pronounced particularly at low liquid superficial velocities. The results are correlated and compared with some models of two-phase, two-component flows for air-water mixtures within their range of validity. Satisfactory agreement is obtained from the trend of the experimental data. (orig.) [Deutsch] Waermeuebertragung und Druckabfall in Stroemungen von Luft-Wasser-Gemischen wurden experimentell in einem vertikalen Ringraum untersucht. Der Referenzparameter, die Reynolds`sche Zahl an der Fluessigkeitsoberflaeche, variierte zwischen 4500 und 30 000, das Verhaeltnis der Oberflaechengeschwindigkeiten von Luft und Wasser erreichte Werte bis zu 20, und die Waermestromdichte an der Oberflaeche lag zwischen 50 und 240 kW/m{sup 2}. Der Zweiphasen-Waermeuebertragungskoeffizient nimmt bei kleinen Oberflaechengeschwindigkeiten besonders ausgepraegt zu. Die experimentellen Ergebnisse werden durch bestehende mathematische Modelle von Zweiphasen-Zweikomponenten-Stroemungen befriedigend vorhergesagt. (orig.)

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

    International Nuclear Information System (INIS)

    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. (low temperature plasma)

  19. Effects of air humidity on ionization chamber response

    International Nuclear Information System (INIS)

    A study of the effect of air humidity on four different ionization chamber cap materials verified earlier studies (Kristensen and Sundbom, 1981; Mijnheer et al., 1983) and extended our understanding of the problem. We found nylon and A-150 plastic caps swell as they absorb water from the air. This accounts for as much as 2.5% increase in ionization response. Graphite chambers readily absorb and desorb water from the air. This creates a problem in maintaining dry air in a wet graphite chamber. Humid air has a different density and W value than dry air (Niatel, 1969, 1975). This decreases the charge collected in a wet graphite chamber. We observe a decrease in response of approximately 2%, a value greater than can be accounted for by these effects alone. Polyethylene chambers are unaffected by humid air. 4 refs., 9 figs

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

    International Nuclear Information System (INIS)

    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.

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

    Science.gov (United States)

    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.

  2. Microwave air plasmas in capillaries at low pressure I. Self-consistent modeling

    Science.gov (United States)

    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 (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}% ).

  3. Influence of water–air ratio on the heat transfer and creep life of a high pressure gas turbine blade

    International Nuclear Information System (INIS)

    An analytical model to investigate the influence of Water–Air Ratio (WAR) on turbine blade heat transfer and cooling processes (and thus the blade creep life) of industrial gas turbines is presented. The effects of WAR are emphasised for the modelling of the gas properties and the subsequent heat transfer process. The approach considers convective/film cooling and includes the influence of a thermal barrier coating. In addition, the approach is based on the thermodynamic outputs of a gas turbine performance simulation, heat transfer model, as well as a method that accounts for the changes in the properties of moist air as a function of WAR. For a given off-design point, the variation of WAR (0.0–0.10) was investigated using the heat transfer model. Results showed that with increasing WAR the blade inlet coolant temperature reduced along the blade span. The blade metal temperature at each section was reduced as WAR increased, which in turn increased the blade creep life. The increase in WAR increased the specific heat of the coolant and increased the heat transfer capacity of the coolant air flow. The model can be implemented by using the thermodynamic cycle of the engine, without knowing the turbine cooling details in the conceptual design stage. Also, this generic method assists the end user to understand the effect of operating conditions and design parameter on the creep life of a high pressure turbine blade. -- Highlights: • The influence of WAR on gas turbine blade heat transfer and creep life is examined. • Coolant specific heat capacity is the key property affected by changes in WAR. • Increase in WAR reduces the coolant and metal temperature along the blade span. • Creep life increases with increase in WAR even if ambient temperature is increased

  4. Effect mechanism of air deflectors on the cooling performance of dry cooling tower with vertical delta radiators under crosswind

    International Nuclear Information System (INIS)

    Highlights: • A 3D numerical model was set for NDDCTV to study the effect of air deflectors. • The air deflectors improve the tower performance by 1.375 °C at uc = 6 m/s for a case. • The air deflectors reduce the air inflow deviation angle θd at most delta entries. • The reduced θd can improve the cooling performance of former deteriorated columns. • Both the radial inflow air velocity and θd impact the cooling performance of delta. - Abstract: To study the effect mechanism of air deflectors on dry cooling tower, a three dimensional numerical model was established, with full consideration of the delta structure. The accuracy and credibility of dry cooling tower numerical model were validated. By numerical model, the average air static pressure and the average radial inflow air velocity were computed and analyzed at delta air entry, sector air entry and exit faces. By the air inflow deviation angle θd, the effect of air deflectors on the aerodynamic field around tower was analyzed. The water exit temperatures of θ−1 columns, θ+2 columns and cooling sectors were also presented to clarify the effect of air deflectors. It was found that the air deflectors improved the aerodynamic field around cooling columns. The reduced air inflow deviation degree at delta entry improved the cooling performance of deteriorated columns. Referring to the radial inflow air velocity ura and the air inflow deviation degree at delta entry, the effect mechanism of air deflectors are clarified under crosswind

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

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    Luai M. Al-Hadhrami

    2014-01-01

    Full Text Available 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.

  7. Dual-pump CARS of Air in a Heated Pressure Vessel up to 55 Bar and 1300 K

    Science.gov (United States)

    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.

  8. The effect of grass transpiration on the air temperature

    Czech Academy of Sciences Publication Activity Database

    Šír, M.; Tesař, Miroslav; Lichner, Ľ.; Czachor, H.

    2014-01-01

    Roč. 69, č. 11 (2014), s. 1570-1576. ISSN 0006-3088 Institutional support: RVO:67985874 Keywords : air temperature oscillations * embolism * plant transpiration * soil water * tensiometric pressure * xylem tension Subject RIV: DA - Hydrology ; Limnology Impact factor: 0.827, year: 2014

  9. Effect of Classical Music on Reducing Blood Pressure in Children

    OpenAIRE

    Saing, Saloma Klementina; Rina, Oke; Ramayati, Rafita; Rusdidjas

    2009-01-01

    Background High blood pre ssure remains a public health problem. High blood pressure in children and adolescent is a major risk for cardiovascular disease in adulthood which can cause high morbidity and mortality. Listening to the classical music can be used as an alternative in reducing high blood pressure. Objective To investigate the effect of classical music in reducing blood pressure in children with high normal blood pressure and or hypertension. Methods Eighty eight students of S...

  10. Memory effect under pressure in low density amorphous silicon

    OpenAIRE

    Garg, Nandini; Pandey, K. K.; K. V. Shanavas; Betty, C. A.; Sharma, Surinder M

    2010-01-01

    Our investigations on porous Si show that on increase of pressure it undergoes crystalline phase transitions instead of pressure induced amorphization - claimed earlier, and the amorphous phase appears only on release of pressure. This amorphous phase, when subjected to higher pressures, transforms reversibly to a higher coordinated primitive hexagonal phase showing a kind of memory effect which may be the only example of its kind in the elemental solids. First principles calculations and the...

  11. Electrical and spectroscopic analysis of mono- and multi-tip pulsed corona discharges in air at atmospheric pressure

    International Nuclear Information System (INIS)

    This work is devoted to the analysis of experimental results obtained in dry air at atmospheric pressure in a positive point-to-plane corona discharge under a pulsed applied voltage in the cases of anodic mono- and multi-tips. In the mono-tip case, the peak corona current is analysed as a function of several experimental parameters such as magnitude, frequency and duration of pulsed voltage and gap distance. The variation of the corona discharge current is correlated with the ozone production. Then in the multi-tip case, the electrical behaviour is analysed as a function of the distance between two contiguous tips and the tip number in order to highlight the region of creation active species for the lowest dissipated power. Intensified charge-coupled device pictures and electric field calculations as a function of inter-tip distance are performed to analyse the mutual effect between two contiguous tips. The optical emission spectra are measured in the UV–visible–NIR wavelength range between 200 nm and 800 nm, in order to identify the main excited species formed in an air corona discharge such as the usual first and second positive systems with first negative systems of molecular nitrogen. The identification of atomic species (O triplet and N) and the quenching of NOγ emission bands are also emphasized.

  12. Numerical model for the calculation of spherical pressure wave propagation in elastoplastic and viscoelastic materials, and calculation of the air-blast induced ground movements in the subseismic case

    International Nuclear Information System (INIS)

    The results of two works on the topic 'propagation and effect of nuclear pressure waves in the ground and in rocks' are given in this report. The first part deals with fundamentals and preliminary results of a numerical computer programme to calculate the spherically symmetrical pressure wave propagation in viscoelastic and elastoplastic media. The second part deals with the application of existing programmes to calculate the building stress in the subseismic region of air-blast induced ground pressure waves. (orig./LH)

  13. Wave effects on a pressure sensor

    Digital Repository Service at National Institute of Oceanography (India)

    Joseph, A.; DeSa, E.J.; Desa, E.; McKeown, J.; Peshwe, V.B.

    Wave flume experiments indicated that for waves propagating on quiescent waters the sensor's performance improved (i.e. the difference Delta P between the average hydrostatic and measured pressures was small and positive) when the inlet...

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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...

  16. Chiral selective effects of doxazosin enantiomers on blood pressure and urinary bladder pressure in anesthetized rats

    Institute of Scientific and Technical Information of China (English)

    Shi-ping MA; Lei-ming REN; Ding ZHAO; Zhong-ning ZHU; Miao WANG; Hai-gang LU; Li-hua DUAN

    2006-01-01

    Aim: To study chiral selective effects of doxazosin enantiomers on blood pressure and urinary bladder pressure in anesthetized rats. Methods: In anesthetized rats, the carotid blood pressure, left ventricular pressure of the heart and the urinary bladder pressure were recorded. Results: Administration of S-doxazosin at 0.25, 2.5, 25, and 250 nmol/kg iv produced a dose-dependent decrease in blood pressure, but its depressor effect was significantly weaker than that induced by R-doxazosin and racemic-doxazosin (rac-doxazosin), and the ED30 values (producing a 30% decrease in mean arterial pressure) of R-doxazosin, rac-doxazosin and S-doxazosin were 15.64,45.93, and 128.81, respectively. Rac-doxazosin and its enantiomers administered cumulatively in anesthetized rats induced a dose-dependent decrease in the left ventricular systolic pressure and ±dp/dtmax, and the potency order of the 3 agents was R-doxazosin >rac-doxazosin >S-doxazosin. Rac-doxazosin and its enantiomers decreased the vesical micturition pressure dose-dependently at 2.5,25, and 250 nmol/kg, and the inhibitory potency among the 3 agents was not significantly different. Conclusion: S-doxazosin decreases the carotid blood pressure and left ventricular pressure of the heart less than R-doxazosin and rac-doxazosin, but its effect on the vesical micturition pressure is similar to R-doxazosin and rac-doxazosin, indicating that S-doxazosin has chiral selectivity between cardiovascular system and urinary system in anesthetized rats.

  17. Ambient air particle transport into the effluent of a cold atmospheric-pressure argon plasma jet investigated by molecular beam mass spectrometry

    International Nuclear Information System (INIS)

    Ambient air species, which are transported into the active effluent of an atmospheric-pressure plasma jet result in highly reactive oxygen and nitrogen species (RONS). Especially for the envisaged application field of plasma medicine, these RONS are responsible for strong biological responses. In this work, the effect of ambient air transport into the effluent of an atmospheric-pressure plasma argon jet on the on-axis densities of nitrogen, oxygen and argon was investigated by means of absolutely calibrated molecular beam mass spectrometry (MBMS). According to biomedical experiments a (bottomless) Petri dish was installed in front of the MBMS. In the following, the near flow field is referring to the region close to the nozzle exit and the far flow field is referring to the region beyond that. The absolute on-axis densities were obtained by three different methods, for the near flow field with VUV-absorption technique, for the far flow field with the MBMS and the total flow field was calculated with a computational fluid dynamics (CFD) simulation. The results of the ambient air particle densities of all independent methods were compared and showed an excellent agreement. Therefore the transport processes of ambient air species can be measured for the whole effluent of an atmospheric-pressure plasma jet. Additionally, with the validation of the simulation it is possible in future to calculate the ambient species transport for various gas fluxes in the same turbulent flow regime. Comparing the on-axis densities obtained with an ignited and with a non-ignited plasma jet shows that for the investigated parameters, the main influence on the ambient air species transport is due to the increased temperature in the case when the jet is switched on. Moreover, the presence of positive ions (e.g. ArN2+) formed due to the interaction of plasma-produced particles and ambient air species, which are transported into the effluent, is shown. (paper)

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

    Directory of Open Access Journals (Sweden)

    Hye Yeon Seo

    Full Text Available 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

  19. Research of air-cushion isolation effects on high arch dam reservoir

    Institute of Scientific and Technical Information of China (English)

    Shao-Jie Zhang; Jiang Chen; Yuan-Ze Zhang; Hao-Wu Liu

    2011-01-01

    A three-dimensional (3D) finite element model of air-cushion isolated arch dam is presented with the nonlinear gas-liquid-solid multi-field dynamic coupling effect taken into account.In this model,the displacement formulation in Lagrange method,pressure formulation in Euler method,nonlinear contact model based on Coulomb friction law are applied to the air-cushion,reservoir and contraction joint domain,respectively.The dynamic response of Jinping I arch dam with a height of 305m is analyzed using the seismic records of the Wenchuan Earthquake in 2008.Numerical resuits show that the air-cushion isolation reduces significantly the hydrodynamic pressure as well as the opening width for the contraction joints of high arch dam.

  20. Sildenafil has no effect on portal pressure but lowers arterial pressure in patients with compensated cirrhosis

    OpenAIRE

    Tandon, Puneeta; Inayat, Irteza; Tal, Michael; Spector, Marcelo; Shea, Martha; Groszmann, Roberto; Garcia-Tsao, Guadalupe

    2010-01-01

    The reduction of portal pressure in patients with early compensated cirrhosis may be more responsive to drugs increasing intrahepatic vasodilatation than those reducing portal venous inflow. The PDE-V inhibitor sildenafil can potentially reduce portal pressure by decreasing intrahepatic resistance, but its systemic vasodilatory effects may be deleterious.

  1. Letter to the Editor: Applications Air Q Model on Estimate Health Effects Exposure to Air Pollutants

    Directory of Open Access Journals (Sweden)

    Gholamreza Goudarzi

    2016-02-01

    Full Text Available Epidemiologic studies in worldwide have measured increases in mortality and morbidity associated with air pollution (1-3. Quantifying the effects of air pollution on the human health in urban area causes an increasingly critical component in policy discussion (4-6. Air Q model was proved to be a valid and reliable tool to predicts health effects related to criteria  pollutants (particulate matter (PM, ozone (O3, nitrogen dioxide (NO2, sulfur dioxide (SO2, and carbon monoxide (CO, determinate  the  potential short term effects of air pollution  and allows the examination of various scenarios in which emission rates of pollutants are varied (7,8. Air Q software provided by the WHO European Centre for Environment and Health (ECEH (9. Air Q model is based on cohort studies and used to estimates of both attributable average reductions in life-span and numbers of mortality and morbidity associated with exposure to air pollution (10,11. Applications

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

    Science.gov (United States)

    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.

  3. The health effects of exercising in air pollution.

    Science.gov (United States)

    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

  4. Collective effects in the radiation pressure force

    CERN Document Server

    Bachelard, R; Guerin, W; Kaiser, R

    2016-01-01

    We discuss the role of diffuse, Mie and cooperative scattering on the radiation pressure force acting on the center of mass of a cloud of cold atoms. Even though a mean-field Ansatz (the `timed Dicke state'), previously derived from a cooperative scattering approach, has been shown to agree satisfactorily with experiments, diffuse scattering also describes very well most features of the radiation pressure force on large atomic clouds. We compare in detail an incoherent, random walk model for photons and a diffraction approach to the more complete description based on coherently coupled dipoles. We show that a cooperative scattering approach, although it provides a quite complete description of the scattering process, is not necessary to explain the previous experiments on the radiation pressure force.

  5. Manufacturers of Copper Tube for Central Air Conditioner Use Face Mounting Pressure in the Final Quarter of the Year

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    <正>This year,the investment growth rate of real estate industry continued to slow down,sold area of commercial housing also dropped significantly,which brought huge pressure to the domestic air conditioning manufactures.In the first half of the year,by relying on high growth in national financial expenditure,along with investment in public infrastructure

  6. AGRICULTURAL PRICE, QUANTITY, AND WELFARE EFFECTS OF AIR QUALITY IMPROVEMENTS

    OpenAIRE

    Ribaudo, Marc; Shortle, James S.

    1986-01-01

    The failure to allow for significant crop quality effects in a partial-equilibrium model can lead to misleading inferences about the price, output and welfare implications of air quality improvements. It has been observed that air pollutants such as ozone, sulphur dioxide, and nitrogen dioxide affect the yield and quality of many crops. The economic benefit from improving air quality in crop producing regions has been measured using a partial-equilibrium approach which accounts only for suppl...

  7. Pressure Effects on the Thermal De-NOx Process

    DEFF Research Database (Denmark)

    Kjærgaard, Karsten; Glarborg, Peter; Dam-Johansen, Kim;

    1996-01-01

    The effect of pressure on the thermal de-NOx process has been investigated in flow reactor experiments. The experiments were performed at pressures from 1 to 10 bar and temperatures ranging from 925 to 1375 K. The inlet O-2 level was varied from 1000 ppm to 10%, while NH3 and NO were maintained at...... effect of the pressure but also cause a slight decrease in the NO reduction potential. The results are consistent with recent atmospheric pressure experiments of thermal de-NOx covering a wide range of reactant partial pressures. Comparisons of the experimental data with the recent chemical kinetic model...... of Miller and Glarborg show satisfactory agreement. The implications of the results for application of thermal de-NOx in high-pressure systems, such as pressurized fluidized bed combustion and gas turbines, are discussed....

  8. Concrete blocks' adverse effects on indoor air and recommended solutions

    International Nuclear Information System (INIS)

    Air infiltration through highly permeable concrete blocks can allow entry of various serious indoor air pollutants including radon. An easy approach to avoiding these pollutants is to select a less-air-permeable concrete block. Tests show that air permeability of concrete blocks can vary by a factor greater than 50 (0.63--35 standard L/min/m2 at 3 Pa). The surface texture of the blocks correlates well with air permeability; test results of smoother, closed-surface-texture blocks were usually less air-permeable. During construction, air infiltration can be minimized by capping walls and carefully sealing around openings for utilities or other penetrations. Structures with indoor air-quality problems due to soil-gas entry can be mitigated more effectively with less coating material if the blocks have a closed surface texture. All coatings evaluated--cementaceous block filler (which has the lowest applied cost and is more than 99.5% effective), surface bonding cement, water-based epoxy, polysulfide vinyl acrylic, and latex (three coats)--were highly effective (more than 98%) in reducing air permeability when adequately applied. Coating selection should be influenced by expected service life, considering surface condition and cost

  9. High-pressure effects on intramolecular electron transfer compounds

    CERN Document Server

    He Li Ming; Li Hong; Zhang Bao Wen; Li Yi; Yang Guo Qiang

    2002-01-01

    We explore the effect of pressure on the fluorescence spectra of the intramolecular electron transfer compound N-(1-pyrenylmethyl), N-methyl-4-methoxyaniline (Py-Am) and its model version, with poly(methyl methacrylate) blended in, at high pressure up to 7 GPa. The emission properties of Py-Am and pyrene show distinct difference with the increase of pressure. This difference indicates the strength of the charge transfer interaction resulting from the adjusting of the conformation of Py-Am with increase of pressure. The relationship between the electronic state of the molecule and pressure is discussed.

  10. Diffusion air effects on the soot axial distribution concentration in a premixed acetylene/air flame

    Energy Technology Data Exchange (ETDEWEB)

    Fassani, Fabio Luis; Santos, Alex Alisson Bandeira; Goldstein Junior, Leonardo [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Mecanica. Dept. de Engenharia Termica e de Fluidos]. E-mails: fassani@fem.unicamp.br; absantos@fem.unicamp.br; leonardo@fem.unicamp.br; Ferrari, Carlos Alberto [Universidade Estadual de Campinas, SP (Brazil). Inst. de Fisica. Dept. de Eletronica Quantica]. E-mail: ferrari@ifi.unicamp.br

    2000-07-01

    Soot particles are produced during the high temperature pyrolysis or combustion of hydrocarbons. The emission of soot from a combustor, or from a flame, is determined by the competition between soot formation and its oxidation. Several factors affect these processes, including the type of fuel, the air-to-fuel ratio, flame temperature, pressure, and flow pattern. In this paper, the influence of the induced air diffusion on the soot axial distribution concentration in a premixed acetylene/air flame was studied. The flame was generated in a vertical axis burner in which the fuel - oxidant mixture flow was surrounded by a nitrogen discharge coming from the annular region between the burner tube and an external concentric tube. The nitrogen flow provided a shield that protected the flame from the diffusion of external air, enabling its control. The burner was mounted on a step-motor driven, vertical translation table. The use of several air-to-fuel ratios made possible to establish the sooting characteristics of this flame, by measuring soot concentration along the flame height with a non-intrusive laser light absorption technique. (author)

  11. Students' Pressure, Time Management and Effective Learning

    Science.gov (United States)

    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…

  12. Bibliography on vapor pressure isotope effects

    International Nuclear Information System (INIS)

    The first Bibliography on Vapour Pressure Isotope and covered the literature of the period from 1919 through December 1975. The present Supplement reviews the literature from January 1976 through December 1979. The bibliography is arranged in chronological order; within each year the references are listed alphabetically according to the name of the first author of each work. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  16. High pressure air jet in the endoscopic preparation room: risk of noise exposure on occupational health.

    Science.gov (United States)

    Chiu, King-Wah; Lu, Lung-Sheng; Wu, Cheng-Kun

    2015-01-01

    After high-level disinfection of gastrointestinal endoscopes, they are hung to dry in order to prevent residual water droplets impact on patient health. To allow for quick drying and clinical reuse, some endoscopic units use a high pressure air jet (HPAJ) to remove the water droplets on the endoscopes. The purpose of this study was to evaluate the excessive noise exposure with the use of HPAJ in endoscopic preparation room and to investigate the risk to occupational health. Noise assessment was taken during 7 automatic endoscopic reprocessors (AERs) and combined with/without HPAJ use over an 8-hour time-weighted average (TWA). Analytical procedures of the NIOSH and the ISO for noise-induced hearing loss were estimated to develop analytic models. The peak of the noise spectrum of combined HPAJ and 7 AERs was significantly higher than that of the 7 AERs alone (108.3 ± 1.36 versus 69.3 ± 3.93 dBA, P  2.5 dB) was 2.15% at 90 dBA, 11.6% at 95 dBA, and 51.3% at 100 dBA. The odds ratio was 49.1 (95% CI: 11.9 to 203.6). The noise generated by the HPAJ to work over TWA seriously affected the occupational health and safety of those working in an endoscopic preparation room. PMID:25710009

  17. Functionalization of graphene by atmospheric pressure plasma jet in air or H2O2 environments

    Science.gov (United States)

    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.

  18. Nanosecond Repetitively Pulsed Discharges in Air at Atmospheric Pressure -- Experiment and Theory of Regime Transitions

    Science.gov (United States)

    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.

  19. Low temperature, atmospheric pressure, direct current microplasma jet operated in air, nitrogen and oxygen

    Science.gov (United States)

    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.

  20. Runaway electrons and x-rays from a corona discharge in atmospheric pressure air

    International Nuclear Information System (INIS)

    The characteristics of a corona discharge in atmospheric pressure air are studied using pulsed power generators that produce voltage pulses of different durations, polarities and shapes. The characteristics are measured in the single pulse, batch, and repetitively pulsed modes. It is shown that no matter what the voltage pulse polarity is, a corona discharge starts developing as a conical diffuse discharge near the electrode tip with a voltage rate of increase of ∼1015 V s-1 across an electrode of small curvature radius. With lower voltage rate of increase (∼1013 V s-1 or lower), one or several diffuse jets develop from this electrode. The diameter of the jets at their front is less than 1 mm and depends on many factors (voltage pulse amplitude and increase, inter-electrode gap width, pulse repetition rate, etc). It is found that at long voltage pulse durations, the radiation spectrum of the corona discharge changes, and the bands and lines of the material of the electrode appear in the UV region at 200-300 nm. It is demonstrated that a runaway electron beam in a corona discharge is generated and detected at a distance several times greater than the brightly glowing plasma region of the corona discharge. It is shown that x-rays are generated from a corona discharge at high pulse repetition rates of up to 1 kHz. (paper)

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

    Directory of Open Access Journals (Sweden)

    Martin Van Leen

    2015-02-01

    Full Text Available 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

  2. Personal computers pollute indoor air: effects on perceived air quality, SBS symptoms and productivity in offices

    DEFF Research Database (Denmark)

    Bako-Biro, Zsolt; Wargocki, Pawel; Weschler, Charles J.;

    2002-01-01

    female subjects were exposed for 4.8 h to each of the two conditions in the office and performed simulated office work. They remained thermally neutral by adjusting their clothing and were blind to the interventions. In the absence of PCs in the office the perceived air quality improved, odour intensity......Perceived air quality and Sick Building Syndrome (SBS) symptoms were studied in a low-polluting office space ventilated at an air change rate of 2 h-1 (10 L/s per person with 6 people present) with and without personal computers (PCs). Other environmental parameters were kept constant. Thirty...... effects of PCs on human comfort and performance....

  3. Beneficial cardiovascular effects of reducing exposure to particulate air pollution with a simple facemask

    Directory of Open Access Journals (Sweden)

    Li Jing

    2009-03-01

    Full Text Available Abstract Background Exposure to air pollution is an important risk factor for cardiovascular morbidity and mortality, and is associated with increased blood pressure, reduced heart rate variability, endothelial dysfunction and myocardial ischaemia. Our objectives were to assess the cardiovascular effects of reducing air pollution exposure by wearing a facemask. Methods In an open-label cross-over randomised controlled trial, 15 healthy volunteers (median age 28 years walked on a predefined city centre route in Beijing in the presence and absence of a highly efficient facemask. Personal exposure to ambient air pollution and exercise was assessed continuously using portable real-time monitors and global positional system tracking respectively. Cardiovascular effects were assessed by continuous 12-lead electrocardiographic and ambulatory blood pressure monitoring. Results Ambient exposure (PM2.5 86 ± 61 vs 140 ± 113 μg/m3; particle number 2.4 ± 0.4 vs 2.3 ± 0.4 × 104 particles/cm3, temperature (29 ± 1 vs 28 ± 3°C and relative humidity (63 ± 10 vs 64 ± 19% were similar (P > 0.05 for all on both study days. During the 2-hour city walk, systolic blood pressure was lower (114 ± 10 vs 121 ± 11 mmHg, P vs 88 ± 11/min; P > 0.05. Over the 24-hour period heart rate variability increased (SDNN 65.6 ± 11.5 vs 61.2 ± 11.4 ms, P vs 816 ± 340 ms2, P Conclusion Wearing a facemask appears to abrogate the adverse effects of air pollution on blood pressure and heart rate variability. This simple intervention has the potential to protect susceptible individuals and prevent cardiovascular events in cities with high concentrations of ambient air pollution.

  4. Health Effects of Climate and Air Pollution in Buenos Aires: A First Time Series Analysis

    OpenAIRE

    Patricia Romero Lankao; Laura Dawidowski; Patricia Matus; Rosana Abrutzky

    2012-01-01

    Background: The impact of urban air pollution and temperature changes over health is a growing concern for epidemiologists all over the world and particularly for developing countries where fewer studies have been performed. Aim: The main goal of this paper is to analyze the short term effects of changes in temperature and atmospheric carbon monoxide on daily mortality in Buenos Aires, Argentina. Methods: We conducted a time series study focused on three age groups, gender, and cardiovascular...

  5. Calculation of pressure rise in electrical installations due to internal arcs considering SF{sub 6}-air mixtures and arc energy absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Anantavanich, Kittipong

    2010-07-01

    Internal arcs cause sudden temperature and thus pressure increase in electrical installations, which may endanger personnel, installation rooms or buildings as well as the security of power supply. Overpressure can be controlled by e.g. relief openings. The proof of internal arc withstand is usually performed by tests in high power laboratories or by pressure calculations especially in cases, where tests are impractical. Nowadays, there exist reliable pressure calculation methods, which are able to determine pressure rise due to internal arcing. For practical applications, two methods are of importance, the CFD calculation method, which provides spatially resolved results, and the standard calculation method providing spatially averaged results. However, the application range of these methods is limited. This is especially true if SF{sub 6}-air mixtures have to be considered (SF{sub 6}-insulated switchgear) or if arc energy absorbers are installed. In this thesis, both effects, which are important for pressure rise in the case of internal arcing, are treated. The key point of modelling SF{sub 6}-air mixture flows of changing composition is the generation and treatment of reliable gas data. A further main focus is the modelling of arc energy absorbers. For this purpose, heat absorption and flow resistance are considered first of all separately. In order to describe both effects simultaneously, existing and improved model approaches are evaluated and appropriate model combinations are proposed. SF{sub 6}-air mixtures and the effect of arc absorbers are implemented in both calculation methods for the first time with reliable gas data. Special care is taken on data handling and modification of the equation systems. The inclusion of the effect of absorbers is achieved by considering heat sinks and friction forces. Based on the standard calculation method, a versatile improved software tool (Improved Standard Calculation Method) for the determination of pressure

  6. Acute effects of consumption of energy drinks on intraocular pressure and blood pressure

    Directory of Open Access Journals (Sweden)

    Ilechie AA

    2011-04-01

    Full Text Available A Alex Ilechie, Sandra TettehDepartment of Optometry, University of Cape Coast, GhanaBackground: Energy drinks contain a wide variety of ingredients including caffeine, for which there have been conflicting reports regarding its effects on intraocular pressure (IOP and blood pressure. The aim of this study was to investigate the acute effects of an energy drink (Red Bull® on the IOP and blood pressure of healthy young adults.Methods: Thirty healthy university students of either gender, aged 18–30 (mean 23.20 ± 2.81 years were randomly selected to participate in this study. The subjects were randomly divided into two groups (experimental and control and were asked to abstain from caffeine for 48 hours prior to and during the study. Baseline IOP and blood pressure were measured. The experimental group (n = 15 consumed one can of the energy drink (containing 85 mg of caffeine in 250 mL and measurements were repeated at 30, 60, and 90 minutes, while the control group drank 250 mL of water and were tested over the same time period.Results: When compared with baseline, a significant decrease (P < 0.05 in mean IOP at 60 and 90 minutes was observed in the experimental group. There was no corresponding change in systolic or diastolic blood pressure.Conclusion: Our results suggest that energy drinks (ie, Red Bull produce a significant reduction in IOP but have no effect on blood pressure. These findings may be interpreted as reflecting the effect of the combination of caffeine and taurine in the Red Bull energy drink. This effect may result from the known hypotensive effect of taurine, and warrants further study.Keywords: acute effect, intraocular pressure, blood pressure, glaucoma, caffeine, taurine

  7. Anomalous Effects in Air While Cooling Water

    CERN Document Server

    Sardo, Rachel

    2008-01-01

    Water is a unique compound with many anomalies and properties not fully understood. Designing an experiment in the laboratory to study such anomalies, we set up a series of experiments where a tube was placed inside a sealed container with thermocouples attached to the outer surface of the tube and in the air adjacent to the tube. Alternately, deionized water and other compounds were added to the tube and cooled to freezing. Several of the thermocouples suspended in the air and adjacent to the tube showed thermal oscillations as the overall temperature of the container was decreasing. The temperature of the thermocouples increased and decreased in a sinusoidal way during part of the cool down to freezing. Thermal oscillations as large as 3 degrees Celsius were recorded with typical frequencies of about 5 oscillations per minute.

  8. Effect of tube length on measurement of instantaneous pressure drop of column weight in pulsed extraction column

    International Nuclear Information System (INIS)

    The theoretical and experimental study on the purge tube length effect in the air purge method was carried out. Two problems including the effect of the purge tube length on the pressure amplitude and on the pressure phase delay were mainly investigated. The results show that the tube length has little effect on the pressure amplitude when it is no bigger than 17 m. Obvious attenuation is found out when the tube length is bigger than 17 m and the attenuation coefficient calculated by the theoretical model shall be used to calculate the real pressure amplitude. The tube length has obvious delay effect on the pressure wave. The delay time increases with the tube length. The pressure wave delay has big effect in a pressure difference measurement when the lengths of the two purge tubes are not equal. The gas velocity in the purge tube calculated by the theoretical model provides a good method for the evaluation of the purge cup volume. A purge cup with volume of 50 mL could satisfy the requirement of the air purge method. The theoretical and experimental results in this article provide fundamental for the application of the air purge method. (authors)

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

    Science.gov (United States)

    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.

  10. Effect of structured packing density on performance of air dehumidifier

    International Nuclear Information System (INIS)

    An experimental study has been conducted to investigate the performance of a liquid desiccant air dehumidifier equipped with a structured packing made of wood for three different densities using triethylene glycol (TEG) as the liquid desiccant. The structured packing densities used were 77, 100 and 200 m2/m3. The performance of the dehumidifier was expressed in terms of the moisture removal rate and the dehumidifier effectiveness under different air and desiccant parameters, i.e. the air and TEG flow rates, air and TEG inlet temperatures, inlet air humidity and inlet TEG concentration. In general, the trend in the dehumidifier performance was similar to that reported by other investigators using random packing. The effect of packing density on moisture removal rate and dehumidifier effectiveness is assessed. The differences in the effectiveness of different packing densities are attributed to the wetting condition. Lower effectiveness of the column is shown with the packing density of 200 m2/m3 compared to the other two packing densities when the air flow rate, inlet concentration and desiccant flow rate are increased. However, higher effectiveness is shown when either the inlet temperature of the air or desiccant is increased

  11. Effect of structured packing density on performance of air dehumidifier

    Energy Technology Data Exchange (ETDEWEB)

    Abdul-Wahab, S.A. E-mail: sabah1@squ.edu.om; Abu-Arabi, M.K.; Zurigat, Y.H

    2004-09-01

    An experimental study has been conducted to investigate the performance of a liquid desiccant air dehumidifier equipped with a structured packing made of wood for three different densities using triethylene glycol (TEG) as the liquid desiccant. The structured packing densities used were 77, 100 and 200 m{sup 2}/m{sup 3}. The performance of the dehumidifier was expressed in terms of the moisture removal rate and the dehumidifier effectiveness under different air and desiccant parameters, i.e. the air and TEG flow rates, air and TEG inlet temperatures, inlet air humidity and inlet TEG concentration. In general, the trend in the dehumidifier performance was similar to that reported by other investigators using random packing. The effect of packing density on moisture removal rate and dehumidifier effectiveness is assessed. The differences in the effectiveness of different packing densities are attributed to the wetting condition. Lower effectiveness of the column is shown with the packing density of 200 m{sup 2}/m{sup 3} compared to the other two packing densities when the air flow rate, inlet concentration and desiccant flow rate are increased. However, higher effectiveness is shown when either the inlet temperature of the air or desiccant is increased.

  12. Atmospheric pressure diffuse plasma in ambient air for ITO surface cleaning

    International Nuclear Information System (INIS)

    Effects of atmospheric filament-free diffuse plasma in ambient air and oxygen by Diffuse Coplanar Surface Barrier Discharge (DCSBD) on surface of indium tin oxide (ITO) were studied. The DCSBD plasma treatment resulted in significant reduction of water contact angles (even for 1 s long treatment). The decrease can be explained by the chemical changes on surface. These were studied by XPS which shows considerable decrease in the carbon surface concentration. The detailed analysis of C1s peak indicates the increase of the highest binding energy component of the C1s peak that corresponds to polar bonds with oxygen, which may be also related to decrease of water contact angle. AFM measurement showed no significant effect of plasma on ITO surface morphology.

  13. Weather induced effects on extensive air showers observed with the surface detector of the Pierre Auger Observatory

    CERN Document Server

    Bleve, Carla

    2007-01-01

    The rate of events measured with the surface detector of the Pierre Auger Observatory is found to be modulated by the weather conditions. This effect is due to the increasing amount of matter traversed by the shower as the ground pressure increases and to the inverse proportionality of the Moliere radius to the air density near ground. Air-shower simulations with different realistic profiles of the atmosphere support this interpretation of the observed effects.

  14. Auto-ignition of lubricating oil working at high pressures in a compressor for an air conditioner.

    Science.gov (United States)

    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

  15. Pressure effect on the melting temperature

    CERN Document Server

    Garai, Jozsef

    2009-01-01

    Pressure-melting temperature relationship is proposed and tested against the experiments of metals (Pt and Al), salt (NaCl), and ceramic (MgO) with positive results. The equation contains one open parameter which remains constant for the investigated substances. The constant value of the parameter indicates that the presented equation for the melting curve might be the first one which does not contain any arbitrary constant which is left open to fit to the experiments.

  16. Effects of Cyclic Hydraulic Pressure on Osteocytes

    OpenAIRE

    Liu, Chao; Zhao, Yan; Cheung, Wing-Yee; Gandhi, Ronak; Wang, Liyun; You, Lidan

    2010-01-01

    Bone is able to adapt its composition and structure in order to suit its mechanical environment. Osteocytes, bone cells embedded in the calcified matrix, are believed to be the mechanosensors and responsible for orchestrating the bone remodeling process. Recent in vitro studies have shown that osteocytes are able to sense and respond to substrate strain and fluid shear. However the capacity of osteocytes to sense cyclic hydraulic pressure (CHP) associated with physiological mechanical loading...

  17. Effects of intake air temperature on homogenous charge compression ignition combustion and emissions with gasoline and n-heptane

    Directory of Open Access Journals (Sweden)

    Zhang Jianyong

    2015-01-01

    Full Text Available In a port fuel injection engine, Optimized kinetic process (OKP technology is implemented to realize HCCI combustion with dual-fuel injection. The effects of intake air temperature on HCCI combustion and emissions are investigated. The results show that dual-fuel control prolongs HCCI combustion duration and improves combustion stability. Dual-fuel HCCI combustion needs lower intake air temperature than gasoline HCCI combustion, which reduces the requirements on heat management system. As intake air temperature decreases, air charge increases and maximum pressure rising rate decreases. When intake air temperature is about 55ºC, HCCI combustion becomes worse and misfire happens. In fixed dual fuel content condition, HC and CO emission decreases as intake air temperature increases. The combination of dual-fuel injection and intake air temperature control can expand operation range of HCCI combustion.

  18. The effect of nutrition on blood pressure.

    Science.gov (United States)

    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

  19. Full scale measurements of pressure equalization on air permeable facade elements

    NARCIS (Netherlands)

    Bentum, C.A. van; Geurts, C.P.W.

    2015-01-01

    Wind-induced pressure differences over rain screens are determined by the external pressures and the pressures inside the cavity. Minimizing this pressure difference decreases the risk of water leakage and also helps to minimize the local loads on the façade elements. Current rules to determine the

  20. Cocurrent flow in an atmospheric pressure air-water model of a PWR hot leg at 0.114 scale

    International Nuclear Information System (INIS)

    Experimental work has been carried out with air and water in a 0.114 times scale model of the proposed Sizewell 'B' PWR hot leg. The model was accurate from the entry from the reactor vessel to the tube plate in the steam generator. Visual observations are summarized in a flow map in the coordinates of an air Froude number versus a water Froude number. The map shows a predominantly stratified system with spray occurring at higher air flowrates and surges appearing at higher water flowrates. Also, at very low air flowrates, long bubbles of air passed along the top of the hot leg through water filling the pipe. A previous theory predicts the water level in the reactor vessel in terms of the air and water flowrates. This theory also agrees with data from other sources on the level in the hot leg in terms of the discharge of two phases through a horizontal hot leg break. The data includes results for steam and water at pressures up to 62 bar. Correlations for the interface level in the hot leg are developed. Data for lower air flowrates agrees substantially with a theory for the onset of slugging. (author)

  1. Isolating Gas Sensor From Pressure And Temperature Effects

    Science.gov (United States)

    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.

  2. Effect of a tight necktie on intraocular pressure

    OpenAIRE

    Božić Marija; Hentova-Senćanin Paraskeva; Branković Aleksandra; Marjanović Ivan; Jocić Đorđević Jasmina; Senćanin Ivan

    2012-01-01

    Introduction. Any factor causing constriction of the neck may lead to an increase in intraocular pressure. A tight necktie may result in increasing intraocular pressure, which could lead to an erroneous diagnosis and treatment of ocular hypertension or even glaucoma. This study was aimed at evaluating the effect of a tight necktie on intraocular pressure measurement using Goldmann applanation tonometry. Material and Methods. This study included forty eyes of 20 patients with primary ope...

  3. BWR Mark I pressure suppression study: effect of downcomer fill level on the vertical load function

    International Nuclear Information System (INIS)

    The investigation reported forms a part of the BWR Mark I Pressure Suppression Experiment Program and is one of a series of small scale studies designed to evaluate limited aspects of the pool dynamics phenomena prior to conduct of the 1/5 scale air test series. Presented is an experimental study of the effect of downcomer fill level (DFL) on the vertical load function

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

    Science.gov (United States)

    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

  5. Burning rates of hydrogen-air mixtures in containment buildings and the consequent pressure transients

    International Nuclear Information System (INIS)

    One-dimensional flame models are often used to predict the pressure transients caused by hydrogen combustion in containments during postulated severe accidents. In the absence of data, these models account for prevailing flame acceleration mechanisms, such as initial turbulence, venting and obstacle-induced turbulence, by using arbitrarily large burning velocities that are much higher than laminar burning velocities. Using an intermediate-scale test facility at the Whiteshell Nuclear Research Establishment we have obtained necessary data on the effects of flame acceleration mechanisms, to estimate the safety margin in the buring velocities used in the models. So far, data have been analyzed, with a one-dimensional model, to determine effective burning velocities and burning-rate enhancement factors. The results of the analyses indicate that the effect of initial turbulence on the burning rate can be bounded only if the effect of flame-generated turbulence is included. The effect of venting can be accounted for by using two burning velocities, one for the pre-vent duration and a second increased value during the vented-combustion stage. The enhancement factors due to these two mechanisms, for the different conditions analyzed, varied up to 5.4, and the effective burning velocities varied up to 8.4 m/s

  6. Experimental and Numerical Studies of Vitiated Air Effects on Hydrogen-fueled Supersonic Combustor Performance

    Institute of Scientific and Technical Information of China (English)

    LUO Feiteng; SONG Wenyan; ZHANG Zhiqiang; LI Weiqiang; LI Jianping

    2012-01-01

    This paper deals with the vitiation effects of test air on the scramjet performance in the ground combustion heated facilities.The primary goal is to evaluate the effects of H2O and CO2,the two major vitiated species generated by combustion heater,on hydrogen-fueled supersonic combustor performance with experimental and numerical approaches.The comparative experiments in the clean air and vitiated air are conducted by using the resistance heated direct-connected facility,with the typical Mach 4 flight conditions simulated.The H2O and CO2 species with accurately controlled contents are added to the high enthalpy clean air from resistance heater,to synthesize the vitiated air of a combustion-type heater.Typically,the contents of H2O species can be varied within the range of 3.5%-30o% by mole,and 3.0%-10% for CO2 species.The total temperature,total pressure,Mach number and O2 mole fraction at the combustor entrance are well-matched between the clean air and vitiated air.The combustion experiments are completed at the fuel equivalence ratios of 0.53 and 0.42 respectively.Furthermore,three-dimensional (3D) reacting flow simulations of combustor towpath are performed to provide insight into flow field structures and combustion chemistry details that cannot resolved by experimental instruments available.Finally,the experimental data,combined with computational results,are employed to analyze the effects of H2O and CO2 vitiated air on supersonic combustion characteristics and performance.It is concluded that H2O and CO2 contaminants can significantly inhibit the combustion induced pressure rise measured from combustor wall,and the pressure profile decreases with the increasing H2O and CO2 contents in nonlinear trend;simulation results agree well with experimental data and the overall vitiation effects are captured; direct extrapolation of the results from vitiated air to predict the performance of actual flight conditions could result in over-fueling the combustor

  7. Transition effect of air shower particles in plastic scintillators

    Science.gov (United States)

    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.

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

    OpenAIRE

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

    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.

  9. Liquid Steel at Low Pressure: Experimental Investigation of a Downward Water Air Flow

    Science.gov (United States)

    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.

  10. Atmospheric pressure He-air plasma jet: Breakdown process and propagation phenomenon

    Energy Technology Data Exchange (ETDEWEB)

    Begum, Asma [Independent University, Bangladesh, School of Engineering and Computer Science, Bashundhara, Dhaka (Bangladesh); Laroussi, Mounir [Old Dominion University, Department of Electrical and Computer Engineering, Norfolk, Virginia (United States); Pervez, Mohammad Rasel [Master Mind College, Department of Physics, Dhanmondi, Dhaka (Bangladesh)

    2013-06-15

    In this paper He-discharge (plasma jet/bullet) in atmospheric pressure air and its progression phenomenon has been studied experimentally using ICCD camera, optical emission spectroscopy (OES) and calibrated dielectric probe measurements. The repetitive nanosecond pulse has applied to a plasma pencil to generate discharge in the helium gas channel. The discharge propagation speed was measured from the ICCD images. The axial electric field distribution in the plasma jet is inferred from the optical emission spectroscopic data and from the probe measurement. The correlation between the jet velocities, jet length with the pulse duration is established. It shows that the plasma jet is not isolated from the input voltage along its propagation path. The discharge propagation speed, the electron density and the local and average electric field distribution along the plasma jet axis predicted from the experimental results are in good agreement with the data predicted by numerical simulation of the streamer propagation presented in different literatures. The ionization phenomenon of the discharge predicts the key ionization parameters, such as speed, peak electric field in the front, and electron density. The maximum local electric field measured by OES is 95 kV/cm at 1.3 cm of the jet axis, and average EF measured by probe is 24 kV/cm at the same place of the jet. The average and local electron density estimated are in the order of 10{sup 11} cm{sup -3} and it reaches to the maximum of 10{sup 12} cm{sup -3}.

  11. Nanosecond repetitively pulsed discharges in air at atmospheric pressure-the spark regime

    International Nuclear Information System (INIS)

    Nanosecond repetitively pulsed (NRP) spark discharges have been studied in atmospheric pressure air preheated to 1000 K. Measurements of spark initiation and stability, plasma dynamics, gas temperature and current-voltage characteristics of the spark regime are presented. Using 10 ns pulses applied repetitively at 30 kHz, we find that 2-400 pulses are required to initiate the spark, depending on the applied voltage. Furthermore, about 30-50 pulses are required for the spark discharge to reach steady state, following initiation. Based on space- and time-resolved optical emission spectroscopy, the spark discharge in steady state is found to ignite homogeneously in the discharge gap, without evidence of an initial streamer. Using measured emission from the N2 (C-B) 0-0 band, it is found that the gas temperature rises by several thousand Kelvin in the span of about 30 ns following the application of the high-voltage pulse. Current-voltage measurements show that up to 20-40 A of conduction current is generated, which corresponds to an electron number density of up to 1015 cm-3 towards the end of the high-voltage pulse. The discharge dynamics, gas temperature and electron number density are consistent with a streamer-less spark that develops homogeneously through avalanche ionization in volume. This occurs because the pre-ionization electron number density of about 1011 cm-3 produced by the high frequency train of pulses is above the critical density for streamer-less discharge development, which is shown to be about 108 cm-3.

  12. Nanosecond repetitively pulsed discharges in air at atmospheric pressure-the spark regime

    Energy Technology Data Exchange (ETDEWEB)

    Pai, David Z; Lacoste, Deanna A; Laux, Christophe O [Laboratoire EM2C, CNRS UPR288, Ecole Centrale Paris, 92295 Chatenay-Malabry (France)

    2010-12-15

    Nanosecond repetitively pulsed (NRP) spark discharges have been studied in atmospheric pressure air preheated to 1000 K. Measurements of spark initiation and stability, plasma dynamics, gas temperature and current-voltage characteristics of the spark regime are presented. Using 10 ns pulses applied repetitively at 30 kHz, we find that 2-400 pulses are required to initiate the spark, depending on the applied voltage. Furthermore, about 30-50 pulses are required for the spark discharge to reach steady state, following initiation. Based on space- and time-resolved optical emission spectroscopy, the spark discharge in steady state is found to ignite homogeneously in the discharge gap, without evidence of an initial streamer. Using measured emission from the N{sub 2} (C-B) 0-0 band, it is found that the gas temperature rises by several thousand Kelvin in the span of about 30 ns following the application of the high-voltage pulse. Current-voltage measurements show that up to 20-40 A of conduction current is generated, which corresponds to an electron number density of up to 10{sup 15} cm{sup -3} towards the end of the high-voltage pulse. The discharge dynamics, gas temperature and electron number density are consistent with a streamer-less spark that develops homogeneously through avalanche ionization in volume. This occurs because the pre-ionization electron number density of about 10{sup 11} cm{sup -3} produced by the high frequency train of pulses is above the critical density for streamer-less discharge development, which is shown to be about 10{sup 8} cm{sup -3}.

  13. Radiation effects on reactor pressure vessel supports

    International Nuclear Information System (INIS)

    The purpose of this report is to present the findings from the work done in accordance with the Task Action Plan developed to resolve the Nuclear Regulatory Commission (NRC) Generic Safety Issue No. 15, (GSI-15). GSI-15 was established to evaluate the potential for low-temperature, low-flux-level neutron irradiation to embrittle reactor pressure vessel (RPV) supports to the point of compromising plant safety. An evaluation of surveillance samples from the High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory (ORNL) had suggested that some materials used for RPV supports in pressurized-water reactors could exhibit higher than expected embrittlement rates. However, further tests designed to evaluate the applicability of the HFIR data to reactor RPV supports under operating conditions led to the conclusion that RPV supports could be evaluated using traditional method. It was found that the unique HFIR radiation environment allowed the gamma radiation to contribute significantly to the embrittlement. The shielding provided by the thick steel RPV shell ensures that degradation of RPV supports from gamma irradiation is improbable or minimal. The findings reported herein were used, in part, as the basis for technical resolution of the issue

  14. Temperature effects for high pressure processing of Picornaviruses

    Science.gov (United States)

    Investigation of the effects of pre-pressurization temperature on the high pressure inactivation for single strains of aichivirus (AiV), coxsackievirus A9 (CAV9) and B5 (CBV5) viruses, as well as human parechovirus -1 (HPeV), was performed. For CAV9, an average 1.99 log10 greater inactivation was ...

  15. Effects of hyperbaric air exposure on the functions of mouse peritoneal macrophages

    Institute of Scientific and Technical Information of China (English)

    WU Hai-sheng; TAO Heng-yi; XU Wei-gang; JIANG Chun-lei; TAO Kai-zhong; GUO Ming-zhu

    2004-01-01

    Objective: To study the effects of hyperbaric air exposure on the functions of peritoneal macrophages of mice. Methods: Forty-eight mice were equally randomized to 6 groups: (1) normal air group (NA); (2) hyperbaric air group 1 (HA1); (3) hyperbaric air group 2 (HA2); (4) hyperbaric air group 3 (HA3); (5) hyperbaric oxygen group (HO); (6) hyperbaric nitrogen group (HN). Every group was exposed to corresponding pressure for 60 min, twice a day for 3 d. Peritoneal macrophages were obtained at the corresponding time to observe the changes of phagocytosis, acid phosphatase, antigen presentation function and the produce of NO and TNF-α. Results: Compared with those in NA group, the activity of phagocytosis, acid phosphatase, antigen presentation function and the produce of NO and TNF-α were markedly inhibited in hyperbaric oxygen group and hyperbaric air group l ( P < 0.05, P < 0.01) and they changed little in HN group. These changes could disappear in 3 - 5 d. Conclusion: The functions of mice peritoneal macrophages were obviously inhibited in simulated air diving environment and hyperoxia may play an important role in it.

  16. Barocaloric effect and the pressure induced solid state refrigerator

    International Nuclear Information System (INIS)

    The current refrigerators are based on the heating and cooling of fluids under external pressure variation. The great inconvenience of this refrigeration technology is the damage caused to the environment by the refrigerant fluids. In this paper, we discuss the magnetic barocaloric effect, i.e., the heating or cooling of magnetic materials under pressure variation and its application in the construction of refrigerators using solid magnetic compounds as refrigerant materials and pressure as the external agent. The discussion presented in this paper points out that such a pressure induced solid state refrigerator can be very interesting because it is not harmful to the environment and can exhibit a good performance.

  17. The effect of high pressure on nitrogen compounds of milk

    International Nuclear Information System (INIS)

    The effect of pressurization at different pressures (from 200 to 1000 MPa, at 200 MPa intervals, tconst. = 15 min) and periods of time (from 15 to 35 min, at 10 min intervals, pconst. = 800 MPa) on the changes of proteins and nitrogen compounds of skimmed milk was studied. The pressurization caused an increase in the amount of soluble casein and denaturation of whey proteins. The level of nonprotein nitrogen compounds and proteoso-peptone nitrogen compounds increased as a result of the high-pressure treatment. These changes increased with an increase in pressure and exposure time. High-pressure treatment considerably affected the changes in the conformation of milk proteins, which was reflected in the changes in the content of proteins sedimenting and an increase in their degree of hydration

  18. The effect of high pressure on nitrogen compounds of milk

    Science.gov (United States)

    Kielczewska, Katarzyna; Czerniewicz, Maria; Michalak, Joanna; Brandt, Waldemar

    2004-04-01

    The effect of pressurization at different pressures (from 200 to 1000 MPa, at 200 MPa intervals, tconst. = 15 min) and periods of time (from 15 to 35 min, at 10 min intervals, pconst. = 800 MPa) on the changes of proteins and nitrogen compounds of skimmed milk was studied. The pressurization caused an increase in the amount of soluble casein and denaturation of whey proteins. The level of nonprotein nitrogen compounds and proteoso-peptone nitrogen compounds increased as a result of the high-pressure treatment. These changes increased with an increase in pressure and exposure time. High-pressure treatment considerably affected the changes in the conformation of milk proteins, which was reflected in the changes in the content of proteins sedimenting and an increase in their degree of hydration.

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

    Science.gov (United States)

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

    2009-07-01

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

  20. Comparison of optical emission spectrums of cold flowing discharge and the post-discharge plasmas of air at low pressure

    OpenAIRE

    İlik, Erkan; AKAN, Tamer; Durmuş, Çağrı; Tanışlı, Murat; Şahin, Neslihan; Mertadam, Sercan

    2015-01-01

    The main differences between cold flowing discharge and the post-discharge plasmas of any gas are intended with the help of new designed plasma generation reactor which Works at low pressure. The up and the middle flanges which made of stainless steel are served as ring electrodes on the plasma generation reactor at low pressure and low temperature. The discharge and the post-discharge plasmas of air are created by means of a d.c. power supply. The reactor both generating post – discharge pla...

  1. High intensity interior aircraft noise increases the risk of high diastolic blood pressure in Indonesian Air Force pilots

    Directory of Open Access Journals (Sweden)

    Minarma Siagian

    2009-12-01

    Full Text Available Aim: To analyze the effects of aircraft noise, resting pulse rate, and other factors on the risk of high diastolic blood pressure (DBP in Indonesian Air Force pilots.Methods: A nested case-control study was conducted using data extracted from annual medical check-ups indoctrination aerophysiologic training records at the Saryanto Aviation and Aerospace Health Institute (LAKESPRA in Jakarta from January 2003 – September 2008. For analysis of DBP: the case group with DBP ≥ 90 mmHg were compared with contral group with DBP < 79 mmHG. One case matched to 12 controls.Results: Out of 567 pilots, 544 (95.9% had complete medical records. For this analysis there were 40 cases of high DBP and 480 controls for DBP. Pilots exposed to aircraft noise 90-95 dB rather than 70-80 dB had a 2.7-fold increase for high DBP [adjusted odds ratio (ORa = 2.70; 95% confi dence interval (CI = 1.05-6.97]. Pilots with resting pulse rates of ≥ 81/minute rather than ≤ 80/minute had a 2.7-fold increase for high DBP (ORa = 2.66; 95% CI = 1.26-5.61. In terms of total fl ight hours, pilots who had 1401-11125 hours rather than 147-1400 hours had a 3.2-fold increase for high DBP (ORa = 3.18; 95% CI = 1.01-10.03.Conclusion: High interior aircraft noise, high total flight hours,  and high resting pulse rate, increased risk for high DBP. Self assessment of resting pulse rate can be used to control the risk of high DBP. (Med J Indones 2009; 276: 276-82Keywords: diastolic blood pressure, aircraft noise, resting pulse rate, military pilots

  2. Effects of pressure and temperature on gate valve unwedging

    International Nuclear Information System (INIS)

    The stem thrust required to unwedge a gate valve is influenced by the pressure and temperature when the valve is closed and by the changes in these conditions between closure and opening. open-quotes Pressure lockingclose quotes and open-quotes thermal bindingclose quotes refer to situations where pressure and temperature effects cause the unwedging load to be much higher than normal. A model of these phenomena has been developed. Wedging (closure) is modeled as developing an open-quotes interferenceclose quotes between the disk and its seat rings in the valve. The effects of pressure and temperature are analyzed to determine the change in this disk-to-seat open-quotes interferenceclose quotes. Flexibilities, of the disk, body, stem and yoke strongly influence the unwedging thrust. Calculations and limited comparisons to data have been performed for a range of valve designs and scenarios. Pressure changes can increase the unwedging load when there is either a uniform pressure decrease, or a situation where the bonnet pressure exceeds the pressures in the adjacent piping. Temperature changes can increase the unwedging load when: (1) valve closure at elevated system temperature produces a delayed stem expansion, (2) a temperature increase after closure produces a bonnet pressure increase, or (3) a temperature change after closure produces an increase in the disk-to-seat open-quotes interferenceclose quotes or disk-to-seat friction

  3. Effects of pressure and temperature on gate valve unwedging

    Energy Technology Data Exchange (ETDEWEB)

    Damerell, P.S.; Harrison, D.H.; Hayes, P.W.; Simons, J.W.; Walker, T.A.

    1996-12-01

    The stem thrust required to unwedge a gate valve is influenced by the pressure and temperature when the valve is closed and by the changes in these conditions between closure and opening. {open_quotes}Pressure locking{close_quotes} and {open_quotes}thermal binding{close_quotes} refer to situations where pressure and temperature effects cause the unwedging load to be much higher than normal. A model of these phenomena has been developed. Wedging (closure) is modeled as developing an {open_quotes}interference{close_quotes} between the disk and its seat rings in the valve. The effects of pressure and temperature are analyzed to determine the change in this disk-to-seat {open_quotes}interference{close_quotes}. Flexibilities, of the disk, body, stem and yoke strongly influence the unwedging thrust. Calculations and limited comparisons to data have been performed for a range of valve designs and scenarios. Pressure changes can increase the unwedging load when there is either a uniform pressure decrease, or a situation where the bonnet pressure exceeds the pressures in the adjacent piping. Temperature changes can increase the unwedging load when: (1) valve closure at elevated system temperature produces a delayed stem expansion, (2) a temperature increase after closure produces a bonnet pressure increase, or (3) a temperature change after closure produces an increase in the disk-to-seat {open_quotes}interference{close_quotes} or disk-to-seat friction.

  4. Quantifying wind and pressure effects on trace gas fluxes across the soil-atmosphere interface

    Science.gov (United States)

    Redeker, K. R.; Baird, A. J.; Teh, Y. A.

    2015-12-01

    Large uncertainties persist in estimates of soil-atmosphere exchange of important trace gases. One significant source of uncertainty is the combined effect of wind and pressure on these fluxes. Wind and pressure effects are mediated by surface topography: few surfaces are uniform and over scales of tenths of a metre to tens of metres, air pressure and wind speed at the ground surface may be very variable. In this paper we consider how such spatial variability in air pressure and wind speed affects fluxes of trace gases. We used a novel nested wind tunnel design comprising a toroidial wind tunnel, in which wind speed and pressure may be controlled, set within a larger, linear wind tunnel. The effects of both wind speed and pressure differentials on fluxes of CO2 and CH4 within three different ecosystems (forest, grassland, peat bog) were quantified. We find that trace gas fluxes are positively correlated with both wind speed and pressure differential near the surface boundary. We argue that wind speed is the better proxy for trace gas fluxes because of its stronger correlation and because wind speed is more easily measured and wind speed measurement methodology more easily standardized. Trace gas fluxes, whether into or out of the soil, increase with wind speed within the toroidal tunnel (+55 % flux per m s-1), while faster, localized surface winds that are external to the toroidal wind tunnel reduce trace gas fluxes (-13 % flux per m s-1). These results are consistent for both trace gases over all ecosystem soil types studied. Our findings support the need for a revised conceptualization of soil-atmosphere gas exchange. We propose a conceptual model of the soil profile that has a "mixed layer", with fluxes controlled by wind speed, wind duration, porosity, water table, and gas production and consumption.

  5. 29 CFR 1915.172 - Portable air receivers and other unfired pressure vessels.

    Science.gov (United States)

    2010-07-01

    ..., 1963. They shall be subjected to a hydrostatic pressure test of one and one-half times the working... quarterly by a competent person. They shall be subjected yearly to a hydrostatic pressure test of one...

  6. An asperity-deformation model for effective pressure

    Science.gov (United States)

    Gangi, Anthony F.; Carlson, Richard L.

    1996-05-01

    Variations of the mechanical and transport properties of cracked and/or porous rocks under isotropic stress depend on both the confining pressure ( Pc) and the pore-fluid pressure ( Pp). To a first approximation, these rock properties are functions of the differential pressure, Pd = Pc - Pp; at least for low differential pressures. However, at higher differential pressures, the properties depend in a more complicated way upon the two pressures. The concept of effective pressure, Pe, is used to denote this variation and it is defined as Pe( Pc, Pp) = Pc - n( Pc, Pp) Pp. If n = 1 (and therefore, is independent of Pc and Pp), the effective pressure is just the differential pressure. We have used an asperity-deformation model and a force-balance equation to derive expressions for the effective pressure. We equate the total external force (in one direction), Fc, to the total force on the asperities, Fa, and the force of the fluid, Fp, acting in that same direction. The fluid force, Fp, acts only on the parts of the crack (or pore-volume) faces which are not in contact. Then, the asperity pressure, Pa, is the average force per unit area acting on the crack (or grain) contacts P a = {F a}/{A} = {F c}/{A} - {F p}/{A} = P c - (1 - {A c}/{A})P p, where A is the total area over which Fc acts and Ac is the area of contact of the crack asperities or the grains. Thus, the asperity pressure, Pa, is greater than the differential pressure, Pd, because Pp acts on a smaller area, A- Ac, than the total area, A. For elastic asperities, the area of contact Ac and the strain (e.g., crack and pore openings) remain the same, to a high degree of approximation, at constant asperity pressure. Therefore, transport properties such as permeability, resistivity, thermal conductivity, etc. are constant, to the same degree of approximation, at constant asperity pressure. For these properties, the asperity pressure is, very accurately, the effective pressure, Pc. Using this model, we find that the

  7. Air pollution effects on the structure of Citrus aurantium leaves

    Energy Technology Data Exchange (ETDEWEB)

    Psaras, G.K.; Christodoulakis, N.S.

    1987-09-01

    Individual air pollutants cause acute and chronic plant injury, act on stomata and affect carbon dioxide exchange as well as plant growth and development. Inhibition of photosynthesis by several air pollutants has been reported repeatedly. Besides, structural modifications of cell organelles have been reported after fumigation by SO/sub 2/. Although chlorosis and subsequent necrosis are common phenomena caused by artificial treatment with pollutants, fine structural leaf characteristics of plants exposed to long-term air pollution in natural conditions are little explored. Light microscope examination of air pollution affected leaves of plants common in natural ecosystems of Athens' metropolitan area revealed chlorosis phenomena. Electron microscope examination of the leaves of a common subshrub of greek phryganic formations grown in a heavily air polluted natural ecosystem of Athens metropolitan area revealed pronounced ultrastructural anomalies of chloroplasts, mitochondria and microbodies of the mesophyll cells. This organelle destruction of the photosynthesizing tissue as well as the minimization of the ecosystem primary productivity are attributed to the compound action of several toxic air pollutants of the photochemical smog of Athens. This work describes the long-term air pollution effects on the structural features of the leaves of Citrus aurantium, a decorative species planted throughout the heavily air polluted city of Athens.

  8. Development of hydrophilic dental wax without surfactant using a non-thermal air atmospheric pressure plasma jet

    Science.gov (United States)

    Lee, Jung-Hwan; Kim, Yong-Hee; Choi, Eun-Ha; Kim, Kwang-Mahn; Kim, Kyoung-Nam

    2014-06-01

    Dental wax (DW), a low-melting and high-molecular-weight organic mixture, is widely used in dentistry for forming moulds of teeth. Hydrophilicity is an important property for DW, as a wet dental investment is used to surround the wax before wax burnout is performed. However, recent attempts to improve the hydrophilicity of DW using a surfactant have resulted in the reduced mechanical properties of the dental investment, leading to the failure of the dental restoration. This study applied a non-thermal air atmospheric pressure plasma jet (AAPPJ) for DW surface treatment and investigated its effect on both DW hydrophilicity and the dental investment's mechanical properties. The results showed that the application of the AAPPJ significantly improved the hydrophilicity of the DW, and that the results were similar to that of cleaner-treated DW using commercially available products with surfactant. A surface chemical analysis indicated that the improvement of hydrophilicity was related to an increase in the number of oxygen-related bonds on the DW surface following the removal of carbon hydrate in both AAPPJ and cleaner-treated DW. However, cleaner treatment compromised the mechanical property of the dental investment when the dental investment was in contact with the treated DW, while the AAPPJ treatment did not. Therefore, the use of AAPPJ to treat DW is a promising method for accurate dental restoration, as it induces an improvement in hydrophilicity without harming the dental investment.

  9. Development of hydrophilic dental wax without surfactant using a non-thermal air atmospheric pressure plasma jet

    International Nuclear Information System (INIS)

    Dental wax (DW), a low-melting and high-molecular-weight organic mixture, is widely used in dentistry for forming moulds of teeth. Hydrophilicity is an important property for DW, as a wet dental investment is used to surround the wax before wax burnout is performed. However, recent attempts to improve the hydrophilicity of DW using a surfactant have resulted in the reduced mechanical properties of the dental investment, leading to the failure of the dental restoration. This study applied a non-thermal air atmospheric pressure plasma jet (AAPPJ) for DW surface treatment and investigated its effect on both DW hydrophilicity and the dental investment's mechanical properties. The results showed that the application of the AAPPJ significantly improved the hydrophilicity of the DW, and that the results were similar to that of cleaner-treated DW using commercially available products with surfactant. A surface chemical analysis indicated that the improvement of hydrophilicity was related to an increase in the number of oxygen-related bonds on the DW surface following the removal of carbon hydrate in both AAPPJ and cleaner-treated DW. However, cleaner treatment compromised the mechanical property of the dental investment when the dental investment was in contact with the treated DW, while the AAPPJ treatment did not. Therefore, the use of AAPPJ to treat DW is a promising method for accurate dental restoration, as it induces an improvement in hydrophilicity without harming the dental investment. (paper)

  10. Influence of pulsed nanosecond volume discharge in atmospheric-pressure air on the electrical characteristics of MCT epitaxial films

    Science.gov (United States)

    Grigoryev, Denis V.; Voitsekhovskii, Alexandr V.; Lozovoy, Kirill A.; Nesmelov, Sergey N.; Dzyadukh, Stanislav M.; Tarasenko, Viktor F.; Shulepov, Michail A.; Dvoretskii, Sergei A.

    2015-12-01

    The purpose of this paper was investigating the effect of volume nanosecond discharge in air at atmospheric pressure on the electro-physical properties of the HgCdTe (MCT) epitaxial films grown by molecular beam epitaxy. Hall measurements of electro-physical parameters of MCT samples after irradiation have shown that there is a layer of epitaxial films exhibiting n-type conductivity that is formed in the near-surface area. After more than 600 pulses of influence parameters and thickness of the resulting n-layer is such that the measured field dependence of Hall coefficient corresponds to the material of n-type conductivity. Also it is shown that the impact of the discharge leads to significant changes in electro-physical characteristics of MIS structures. This fact is demonstrated by increase in density of positive fixed charge, change in the hysteresis type of the capacitance-voltage characteristic, an increase in density of surface states. The preliminary results show that it is possible to use such actions in the development of technologies of the controlled change in the properties of MCT.

  11. Magnetic Ignition of Pulsed Gas Discharges in Air of Low Pressure in a Coaxial Plasma Gun

    Science.gov (United States)

    Thom, Karlheinz; Norwood, Joseph, Jr.

    1961-01-01

    The effect of an axial magnetic field on the breakdown voltage of a coaxial system of electrodes has been investigated by earlier workers. For low values of gas pressure times electrode spacing, the breakdown voltage is decreased by the application of the magnetic field. The electron cyclotron radius now assumes the role held by the mean free path in nonmagnetic discharges and the breakdown voltage becomes a function of the magnetic flux density. In this paper the dependence of the formative time lag as a function of the magnetic flux density is established and the feasibility of using a magnetic field for igniting high-voltage, high-current discharges is shown through theory and experiment. With a 36 microfarad capacitor bank charged to 48,000 volts, a peak current of 1.3 x 10( exp 6) amperes in a coaxial type of plasma gun was achieved with a current rise time of only 2 microseconds.

  12. Strength behaviour of a gas pressure sintered siliconnitride (GPSSN) under static and cyclostatic loading at 1250 C in air

    Energy Technology Data Exchange (ETDEWEB)

    Lauf, S.; Maier, H.P. [Staatliche Materialpruefungsanstalt (MPA), Universitaet Stuttgart (Germany); Rixecker, G. [Max-Planck-Institut fuer Metallforschung, Pulvermetallurgisches Laboratorium, Stuttgart (Germany); Lohrmann, A. [Welz Industrieprodukte GmbH, Fellbach (Germany)

    2000-07-01

    The strength of ceramic materials shows commonly a great scatter. If the material exhibits distinct subcritical crack growth additionally a great scatter in lifetime occurs at least under tensile loading. Gas pressure sintered siliconnitride is expected to show a less distinct fatigue behaviour as sintered siliconnitride. Therefore, experimental investigations under dynamic, static and cyclostatic loading with 4-point bending specimens at 1250 C in air were performed. (orig.)

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

    OpenAIRE

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

    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 wi...

  14. Influence of surface charges on the structure of a dielectric barrier discharge in air at atmospheric pressure: experiment and modeling

    OpenAIRE

    Celestin, S.; Bonaventura, Z.; Guaitella, O; Rousseau, A.; A. Bourdon

    2009-01-01

    Abstract Dielectric barrier discharges (DBD) in air at atmospheric pressure and at low frequency are mainly constituted of thin transient plasma filaments (or microdischarges) with radii of a few hundreds of micrometers. In this work, we consider a point-to-plane geometry with the dielectric covering the plane electrode. Plasma filaments are initiated by streamers, starting from the high-field region close to the point electrode. The plasma filaments deposit charges on the ...

  15. Transitions between corona, glow, and spark regimes of nanosecond repetitively pulsed discharges in air at atmospheric pressure

    OpenAIRE

    Pai, David,; Lacoste, Deanna,; Laux, C.

    2010-01-01

    International audience 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 interelectrode gap distance) of each discharge regime. In particular, the experimental conditions necessary for the glow regime of NRP discharges have been determi...

  16. Field Evaluation for Air-source Transcritical CO2 Heat Pump Water Heater with Optimal Pressure Control

    OpenAIRE

    Hu, Bin; He, Yongning; Wang, Shouguo; Cao, Feng; Xing, Ziwen

    2014-01-01

    Air-source transcritical CO2 heat pump water heater (ATHW) can supply hot water from 60 ? to 90 ? at high efficiency with environment-friendly refrigerant CO2 for commercial, residential and industrial applications. Several optimal discharge pressure correlations for transcritical CO2 heat pump have been proposed in the past few years, most of which are related to the ambient temperature, the evaporation temperature and the gas cooler outlet temperature. In an earlier study, the authors’ rese...

  17. Surface treatment of polypropylene (PP) film by 50 Hz dielectric barrier discharge produced in air and argon/air mixture at atmospheric pressure

    International Nuclear Information System (INIS)

    Thin films of polypropylene (PP) are treated for improving hydrophilicity using non-thermal plasma generated by 50 Hz line frequency dielectric barrier discharge produced in air and argon/air mixture at atmospheric pressure. PP samples before and after the treatments are studied using contact angle measurements, surface free energy calculations and scanning electron microscopy (SEM). Distilled water (H2O), glycerol (C3H8O3) and diiodomethane (CH2I2) are used as test liquids. The contact angle measurements between test liquids and PP samples are used to determine total surface free energy using sessile drop technique. PP films show a remarkable increase in surface free energy after plasma treatment. SEM analysis of the plasma-treated PP films shows that plasma treatment introduces greater roughness on the surface leading to the increased surface free energy. Furthermore, it is found that introducing a small quantity of argon can enhance the surface treatment remarkably

  18. Surface treatment of high density polyethylene (HDPE film by 50 Hz dielectric barrier discharge produced in air and argon/air mixture at atmospheric pressure

    Directory of Open Access Journals (Sweden)

    Joshi Ujjwal Man

    2015-03-01

    Full Text Available Thin films of high density polyethylene (HDPE are treated for improving hydrophilicity using non-thermal plasma generated by 50 Hz line frequency dielectric barrier discharge produced in air and argon/air mixture at atmospheric pressure. HDPE samples before and after the treatment are studied using contact angle measurements, surface free energy calculations and atomic force microscopy (AFM. Distilled water (H2O, glycerol (C3H8O3 and diiodomethane (CH2I2 are used as test liquids. The contact angle measurements between test liquids and HDPE samples are used to determine total surface free energy using sessile drop technique. HDPE films show a remarkable increase in surface free energy after plasma treatment. AFM analysis of the plasma-treated HDPE films shows that plasma treatment introduces greater roughness on the surface leading to the increased surface free energy. Furthermore, it is found that introducing a small quantity of argon can enhance the surface treatment remarkably.

  19. Surface treatment of polypropylene (PP) film by 50 Hz dielectric barrier discharge produced in air and argon/air mixture at atmospheric pressure

    Science.gov (United States)

    Joshi, Ujjwal Man; Subedi, Deepak Prasad

    2015-07-01

    Thin films of polypropylene (PP) are treated for improving hydrophilicity using non-thermal plasma generated by 50 Hz line frequency dielectric barrier discharge produced in air and argon/air mixture at atmospheric pressure. PP samples before and after the treatments are studied using contact angle measurements, surface free energy calculations and scanning electron microscopy (SEM). Distilled water (H2O), glycerol (C3H8O3) and diiodomethane (CH2I2) are used as test liquids. The contact angle measurements between test liquids and PP samples are used to determine total surface free energy using sessile drop technique. PP films show a remarkable increase in surface free energy after plasma treatment. SEM analysis of the plasma-treated PP films shows that plasma treatment introduces greater roughness on the surface leading to the increased surface free energy. Furthermore, it is found that introducing a small quantity of argon can enhance the surface treatment remarkably.

  20. Effect of blank holder pressure on viscous pressure forming aluminum alloy ladder parts

    Institute of Scientific and Technical Information of China (English)

    王忠金; 王新云; 王仲仁

    2002-01-01

    Viscous pressure forming (VPF), is suitable for forming difficult-to-form sheet metal parts. An investigation in the effect of blank holder pressure (BHP) on VPF aluminum alloy ladder parts was conducted. Based on experimental and numerical simulation results of the effect of BHP on dimensional accuracy, wall-thickness reduction, forming pressure, material flow and defects (such as wrinkling and fracture) of specimens, the effect patterns of BHP load path on VPF ladder parts were explained. The limits of BHP corresponding to specimens with no defect and with wrinkling or fracture defect were determined. In the limits of formable BHP, the variable load path of BHP was beneficial to drawing blank into the die and decreasing wall-thickness reduction of specimens. The experimental results show that the ladder parts of good surface fineness and high dimensional accuracy can be obtained by variable load paths of BHP.

  1. Human activity under high pressure: A case study on fluctuation scaling of air traffic controller's communication behaviors

    Science.gov (United States)

    Wang, Yanjun; Zhang, Qiqian; Zhu, Chenping; Hu, Minghua; Duong, Vu

    2016-01-01

    Recent human dynamics research has unmasked astonishing statistical characteristics such as scaling behaviors in human daily activities. However, less is known about the general mechanism that governs the task-specific activities. In particular, whether scaling law exists in human activities under high pressure remains an open question. In air traffic management system, safety is the most important factor to be concerned by air traffic controllers who always work under high pressure, which provides a unique platform to study human activity. Here we extend fluctuation scaling method to study air traffic controller's communication activity by investigating two empirical communication datasets. Taken the number of controlled flights as the size-like parameter, we show that the relationships between the average communication activity and its standard deviation in both datasets can be well described by Taylor's power law, with scaling exponent α ≈ 0.77 ± 0.01 for the real operational data and α ≈ 0.54 ± 0.01 for the real-time training data. The difference between the exponents suggests that human dynamics under pressure is more likely dominated by the exogenous force. Our findings may lead to further understanding of human behavior.

  2. AMBIENT AIR TEMPERATURE EFFECT ON POWER PLANT PERFORMANCE

    OpenAIRE

    Rajesh. Kumar; Sarabpreet Singh

    2012-01-01

    The performance of the power plant strongly depends on ambient air temperature (AAT).Mass flow rate (kg/s)of air decreases in summer with increasing AAT for the same volumetric flow rate (m3/s), which results in reduced power output of turbine and increased heat rate.This paper analyzes the effects of the AAT on various parameters of power plant viz., mass flow rate of air, fuel consumption, steam, power output of turbine, efficiency and heat rate of gas turbine, steam turbine and combined cy...

  3. SCALE EFFECT OF IMPINGING PRESSURE CAUSED BY SUBMERGED JET

    Institute of Scientific and Technical Information of China (English)

    TIAN Zhong; XU Wei-lin; WANG Wei; LIU Shan-jun; DONG Jian-wei

    2005-01-01

    The characteristics of the impinging pressure at the jet equipment where the maximum jet velocity can reach 50m/s were studied. By comparing the impinging pressure with the one measured at the low velocity conditions, two conclusions of the scale effect are drawn: firstly, the velocity attenuation degree is smaller than that of low-velocity jet, and secondly, the relative impinging width is narrower than that of low-velocity jet. The reasons of the scale effect of the impinging pressure were elucidated through numerical simulation.

  4. Effect of pressure pulse on geomagnetic field oscillations

    Science.gov (United States)

    Sinha, A. K.; Rajaram, R.

    The effect of solar wind pressure pulse on geomagnetic field oscillations has been computed by using Green's function technique. The dominance of toroidal oscillations during dawn/dusk sectors appears to be natural consequences of solar wind pressure pulse and may not be attributed to K-H instability at the magnetopause boundary caused by velocity shear. Pressure pulse generates surface waves at the magnetopause boundary and couples to the field oscillations to give rise such effects. The paper adopts the 3-dimensional approach to explain the phenomena.

  5. Aging Characteristics on Epoxy Resin Surface Under Repetitive Microsecond Pulses in Air at Atmospheric Pressure

    Science.gov (United States)

    Xie, Qing; Liu, Xiong; Zhang, Cheng; Wang, Ruixue; Rao, Zhangquan; Shao, Tao

    2016-03-01

    Research on aging characteristics of epoxy resin (EP) under repetitive microsecond pulses is important for the design of insulating materials in high power apparatus. It is because that very fast transient overvoltage always occurs in a power system, which causes flashover and is one of the main factors causing aging effects of EP materials. Therefore, it is essential to obtain a better understanding of the aging effect on an EP surface resulting from flashover. In this work, aging effects on an EP surface were investigated by surface flashover discharge under repetitive microsecond pulses in atmospheric pressure. The investigations of parameters such as the surface micro-morphology and chemical composition of the insulation material under different degrees of aging were conducted with the aid of measurement methods such as atomic force microscopy (AFM), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Results showed that with the accumulation of aging energy on the material surface, the particles formed on the material surface increased both in number and size, leading to the growth of surface roughness and a reduction in the water contact angle; the surface also became more absorbent. Furthermore, in the aging process, the molecular chains of EP on the surface were broken, resulting in oxidation and carbonisation. supported by the Natural Science Foundation of Hebei Province (No. E2015502081), National Natural Science Foundation of China (Nos. 51222701, 51307060), and the National Basic Research Program of China (No. 2014CB239505-3)

  6. Effects of radon in indoor air studied

    International Nuclear Information System (INIS)

    Radon is an odorless, tasteless and colourless radioactive noble gas that enters indoor air from the ground. Radon causes lung cancer. A committee set up to evaluate the health risks of chemical substances has been drafting a report on radon, which will compile the major research findings on the lung cancer risk posed by radon. Animal tests have shown that even small doses of radon can cause lung cancer. Smokers seem to contract radon-induced lung cancer more readily than non-smokers. Because research findings have been conflicting, however, it is not known exactly how high the risk of lung cancer caused by indoor radon exposure really is. Several major research projects are under way to obtain increasingly accurate risk assessments. An on-going European joint project brings together several studies - some already finished, some still being worked on. In this way it will be possible to get more accurate risk assessments than from individual studies. In order to prevent lung cancer, it is important to continue the work of determining and reducing radon connects and to combat smoking. (orig.)

  7. Effects of Indoor Air Pollution on Human Health

    DEFF Research Database (Denmark)

    Berglund, B.; Brunekreef, B.; Knöppel, H.;

    1992-01-01

    This article contains a summary discussion of human health effects linked to indoor air pollution (UP) in homes and other non-industrial environments. Rather than discussing the health effects of the many different pollutants which can be found in indoor air, the approach has been to group broad...... reproduction: effects on the skin and mucous membranes in the eyes, nose and throat; sensory effects and other effects on the nervous system; effects on the cardiovascular system; systemic effects on the liver, kidney and gastro-intestinal system. For each of these groups, effects associated with IAP the...... much lower than the number of people contracting resparatory disease or alhgies, or experiencing irritative effects due to exposure to indoor pollution. The effects of IAP on reproduction, cardiovascular disease and on other systems and organs have not been well documented to date. To a certain extent...

  8. Productivity Effects of Air Pollution: Evidence from Professional Soccer

    OpenAIRE

    Lichter, Andreas; Pestel, Nico; Sommer, Eric

    2015-01-01

    In this paper, we estimate the causal effect of ambient air pollution on individuals' productivity by using panel data on the universe of professional soccer players in Germany over the period 1999-2011. Combining this data with hourly information on the concentration of particulate matter in spatial proximity to each stadium at the time of kickoff, we exploit exogenous variation in the players' exposure to air pollution due to match scheduling rules that are beyond the control of teams and p...

  9. Effect of actual vapor pressure on estimating evapotranspiration at Serbia

    Directory of Open Access Journals (Sweden)

    Trajković Slaviša

    2009-01-01

    Full Text Available Actual vapor pressure (VP is an important parameter that is used in many evapotranspiration equations. However, vapor pressure is difficult to measure accurately. In the humid climate, the actual vapor pressure can be derived from minimum air temperature. The objectives of this study were: first, to estimate errors that can arise if VP data are not available and have to be estimated; second, to compare the Priestley-Taylor ET0 values computed under various levels of VP data availability; and third, to evaluate the reliability of Priestley-Taylor equation as compared to the FAO-56 Penman-Monteith method. The following main conclusions can be drawn: Estimated VP values generally were in closest agreement with measured VP values. The measurements of air humidity at humid locations are not indispensable for estimating reference evapotranspiration. The Priestley-Taylor method (with measured or estimated VP provides the very good agreement with the evapotranspiration obtained by the FAO-56 Penman-Monteith method except windless locations.

  10. The Effects of Temperature, Pressure, and Humidity Variations on 100 Meter Sprint Performances

    CERN Document Server

    Mureika, J R

    2005-01-01

    It is well known that ``equivalent'' sprint race times run with different accompanying wind speeds or at different altitudes are anything but equivalent races. The drag force acting on a sprinter is a function of air density and the relative wind speed, where the former has traditionally been calculated using the race venue's elevation above sea level. However, air density variation is dependent on more than just altitude. This work will quantify how changes in air temperature, barometric pressure, and humidity levels influence 100 m sprint performances. When these effects are considered in combination, the corrections to performances can be very large. The results suggest that a non-negligible difference in race times can be expected for ``equivalent'' performances run with the same wind speed at the same venue or physical altitude, but under different atmospheric conditions.

  11. Optimal heat rejection pressure in transcritical carbon dioxide air conditioning and heat pump systems

    DEFF Research Database (Denmark)

    Liao, Shengming; Jakobsen, Arne

    1998-01-01

    Due to the urgent need for environmentally benign refrigerants, the use of the natural substance carbon dioxide in refrigeration systems has gained more and more attention. In systems such as automobile air-conditioners and heat pumps, owing to the relatively high heat rejection temperatures, the...... dioxide air conditioning or heat pump systems and for intelligent controlling such systems....

  12. Bench experiments comparing simulated inspiratory effort when breathing helium-oxygen mixtures to that during positive pressure support with air

    Directory of Open Access Journals (Sweden)

    Martin Andrew R

    2012-10-01

    Full Text Available Abstract Background Inhalation of helium-oxygen (He/O2 mixtures has been explored as a means to lower the work of breathing of patients with obstructive lung disease. Non-invasive ventilation (NIV with positive pressure support is also used for this purpose. The bench experiments presented herein were conducted in order to compare simulated patient inspiratory effort breathing He/O2 with that breathing medical air, with or without pressure support, across a range of adult, obstructive disease patterns. Methods Patient breathing was simulated using a dual-chamber mechanical test lung, with the breathing compartment connected to an ICU ventilator operated in NIV mode with medical air or He/O2 (78/22 or 65/35%. Parabolic or linear resistances were inserted at the inlet to the breathing chamber. Breathing chamber compliance was also varied. The inspiratory effort was assessed for the different gas mixtures, for three breathing patterns, with zero pressure support (simulating unassisted spontaneous breathing, and with varying levels of pressure support. Results Inspiratory effort increased with increasing resistance and decreasing compliance. At a fixed resistance and compliance, inspiratory effort increased with increasing minute ventilation, and decreased with increasing pressure support. For parabolic resistors, inspiratory effort was lower for He/O2 mixtures than for air, whereas little difference was measured for nominally linear resistance. Relatively small differences in inspiratory effort were measured between the two He/O2 mixtures. Used in combination, reductions in inspiratory effort provided by He/O2 and pressure support were additive. Conclusions The reduction in inspiratory effort afforded by breathing He/O2 is strongly dependent on the severity and type of airway obstruction. Varying helium concentration between 78% and 65% has small impact on inspiratory effort, while combining He/O2 with pressure support provides an additive

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

    Science.gov (United States)

    Adimurthy, M.; Katti, Vadiraj V.

    2016-06-01

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

  14. Analysis of Environmental Effects on Leaf Temperature under Sunlight, High Pressure Sodium and Light Emitting Diodes.

    Directory of Open Access Journals (Sweden)

    Jacob A Nelson

    Full Text Available The use of LED technology is commonly assumed to result in significantly cooler leaf temperatures than high pressure sodium technology. To evaluate the magnitude of this effect, we measured radiation incident to and absorbed by a leaf under four radiation sources: clear sky sunlight in the field, sunlight in a glass greenhouse, and indoor plants under either high pressure sodium or light emitting diodes. We then applied a common mechanistic energy-balance model to compare leaf to air temperature difference among the radiation sources and environments. At equal photosynthetic photon flux, our results indicate that the effect of plant water status and leaf evaporative cooling is much larger than the effect of radiation source. If plants are not water stressed, leaves in all four radiation sources were typically within 2°C of air temperature. Under clear sky conditions, cool sky temperatures mean that leaves in the field are always cooler than greenhouse or indoor plants-when photosynthetic photon flux, stomatal conductance, wind speed, vapor pressure deficit, and leaf size are equivalent. As water stress increases and cooling via transpiration decreases, leaf temperatures can increase well above air temperature. In a near-worst case scenario of water stress and low wind, our model indicates that leaves would increase 6°, 8°, 10°, and 12°C above air temperature under field, LED, greenhouse, and HPS scenarios, respectively. Because LED fixtures emit much of their heat through convection rather than radiative cooling, they result in slightly cooler leaf temperatures than leaves in greenhouses and under HPS fixtures, but the effect of LED technology on leaf temperature is smaller than is often assumed. Quantifying the thermodynamic outputs of these lamps, and their physiological consequences, will allow both researchers and the horticulture industry to make informed decisions when employing these technologies.

  15. Analysis of Environmental Effects on Leaf Temperature under Sunlight, High Pressure Sodium and Light Emitting Diodes.

    Science.gov (United States)

    Nelson, Jacob A; Bugbee, Bruce

    2015-01-01

    The use of LED technology is commonly assumed to result in significantly cooler leaf temperatures than high pressure sodium technology. To evaluate the magnitude of this effect, we measured radiation incident to and absorbed by a leaf under four radiation sources: clear sky sunlight in the field, sunlight in a glass greenhouse, and indoor plants under either high pressure sodium or light emitting diodes. We then applied a common mechanistic energy-balance model to compare leaf to air temperature difference among the radiation sources and environments. At equal photosynthetic photon flux, our results indicate that the effect of plant water status and leaf evaporative cooling is much larger than the effect of radiation source. If plants are not water stressed, leaves in all four radiation sources were typically within 2°C of air temperature. Under clear sky conditions, cool sky temperatures mean that leaves in the field are always cooler than greenhouse or indoor plants-when photosynthetic photon flux, stomatal conductance, wind speed, vapor pressure deficit, and leaf size are equivalent. As water stress increases and cooling via transpiration decreases, leaf temperatures can increase well above air temperature. In a near-worst case scenario of water stress and low wind, our model indicates that leaves would increase 6°, 8°, 10°, and 12°C above air temperature under field, LED, greenhouse, and HPS scenarios, respectively. Because LED fixtures emit much of their heat through convection rather than radiative cooling, they result in slightly cooler leaf temperatures than leaves in greenhouses and under HPS fixtures, but the effect of LED technology on leaf temperature is smaller than is often assumed. Quantifying the thermodynamic outputs of these lamps, and their physiological consequences, will allow both researchers and the horticulture industry to make informed decisions when employing these technologies. PMID:26448613

  16. An Analytical Explanation for the X-43A Flush Air Data Sensing System Pressure Mismatch Between Flight and Theory

    Science.gov (United States)

    Ellsworth, Joel C.

    2010-01-01

    Following the successful Mach 7 flight test of the X-43A, unexpectedly low pressures were measured by the aft set of the onboard Flush Air Data Sensing System s pressure ports. These in-flight aft port readings were significantly lower below Mach 3.5 than was predicted by theory. The same lower readings were also seen in the Mach 10 flight of the X-43A and in wind-tunnel data. The pre-flight predictions were developed based on 2-dimensional wedge flow, which fails to predict some of the significant 3-dimensional flow features in this geometry at lower Mach numbers. Using Volterra s solution to the wave equation as a starting point, a three-dimensional finite wedge approximation to flow over the X-43A forebody is presented. The surface pressures from this approximation compare favorably with the measured wind tunnel and flight data at speeds of Mach 2.5 and 3.

  17. Research Update: Direct conversion of h-BN into pure c-BN at ambient temperatures and pressures in air

    International Nuclear Information System (INIS)

    We report a direct conversion of hexagonal boron nitride (h-BN) into pure cubic boron nitride (c-BN) by nanosecond laser melting at ambient temperatures and atmospheric pressure in air. According to the phase diagram, the transformation from h-BN into c-BN can occur only at high temperatures and pressures, as the hBN-cBN-Liquid triple point is at 3500 K/9.5 GPa. Using nanosecond laser melting, we have created super undercooled state and shifted this triple point to as low as 2800 K and atmospheric pressure. The rapid quenching from super undercooled state leads to formation of super undercooled BN (Q-BN). The c-BN phase is nucleated from Q-BN depending upon the time allowed for nucleation and growth

  18. Research Update: Direct conversion of h-BN into pure c-BN at ambient temperatures and pressures in air

    Energy Technology Data Exchange (ETDEWEB)

    Narayan, Jagdish, E-mail: narayan@ncsu.edu; Bhaumik, Anagh [Department of Materials Science and Engineering, Centennial Campus, North Carolina State University, Raleigh, North Carolina 27695-7907 (United States)

    2016-02-01

    We report a direct conversion of hexagonal boron nitride (h-BN) into pure cubic boron nitride (c-BN) by nanosecond laser melting at ambient temperatures and atmospheric pressure in air. According to the phase diagram, the transformation from h-BN into c-BN can occur only at high temperatures and pressures, as the hBN-cBN-Liquid triple point is at 3500 K/9.5 GPa. Using nanosecond laser melting, we have created super undercooled state and shifted this triple point to as low as 2800 K and atmospheric pressure. The rapid quenching from super undercooled state leads to formation of super undercooled BN (Q-BN). The c-BN phase is nucleated from Q-BN depending upon the time allowed for nucleation and growth.

  19. The pressure effects on two-phase anaerobic digestion

    International Nuclear Information System (INIS)

    Highlights: • The pressure effect on anaerobic digestion up to 9 bar was examined. • Increasing pressure decreased pH value in the anaerobic filter. • Increasing pressure increased methane content. • Increasing pressure decreased specific methane yield slightly. • The pressurized methane reactor was very stable and performed well. - Abstract: Two-phase pressurized anaerobic digestion is a novel process aimed at facilitating injection of the produced biogas into the natural gas grid by integrating the fermentative biogas production and upgrading it to substitute natural gas. In order to understand the mechanisms, knowledge of pressure effects on anaerobic digestion is required. To examine the effects of pressure on the anaerobic digestion process, a two-phase anaerobic digestion system was built up in laboratory scale, including three acidogenesis-leach-bed-reactors and one pressure-resistant anaerobic filter. Four different pressure levels (the absolute pressure of 1 bar, 3 bar, 6 bar and 9 bar) were applied to the methane reactor in sequence, with the organic loading rate maintained at approximately 5.1 kgCOD m−3 d−1. Gas production, gas quality, pH value, volatile fatty acids, alcohol, ammonium-nitrogen, chemical oxygen demand (COD) and alkaline buffer capacity were analyzed. No additional caustic chemicals were added for pH adjustment throughout the experiment. With the pressure increasing from 1.07 bar to 8.91 bar, the pH value decreased from 7.2 to 6.5, the methane content increased from 66% to 75%, and the specific methane yield was slightly reduced from 0.33 lN g−1COD to 0.31 lN g−1COD. There was almost no acid-accumulation during the entire experiment. The average COD-degradation grade was always more than 93%, and the average alkaline buffering capacity (VFA/TIC ratio) did not exceed 0.2 at any pressure level. The anaerobic filter showed a very stable performance, regardless of the pressure variation

  20. Assessment of Effects of Air Pollution on Daily Outpatient Visits using the Air Quality Index

    Science.gov (United States)

    Mu, Haosheng; Otani, Shinji; Okamoto, Mikizo; Yokoyama, Yae; Tokushima, Yasuko; Onishi, Kazunari; Hosoda, Takenobu; Kurozawa, Youichi

    2014-01-01

    Background The air quality index (AQI) is widely used to characterize the quality of ambient air. Chinese cities officially report the AQI on a daily basis. To assess the possible effects of air pollution on daily outpatient visits, we examined the association between AQI and the daily outpatient count. Methods Daily data on outpatient visits to each clinical department were collected from the Z county hospital of Datong City, China. The collection period was between 5 April and 30 June, 2012. Daily AQI data and meteorological information were simultaneously recorded. We compared outpatient counts between the index days and comparison days, and calculated Pearson’s product moment correlation coefficient between outpatient counts and AQI levels. Results The average AQI level for index days was significantly higher than that for comparison days. No significant difference was observed in temperature or relative humidity between index days and comparison days. The outpatient counts for pediatrics were significantly higher on index days than on comparison days, and no significant difference was noted in other clinical departments. The outpatient counts for pediatrics positively correlated with the AQI level, and no correlation was noted in other clinical departments. Conclusion The present study assessed the association between daily outpatient visits and air pollution using AQI. The results obtained suggest that air pollution could increase the outpatient count for pediatrics. PMID:25901100

  1. Effect of citicoline on blood pressure variability

    Directory of Open Access Journals (Sweden)

    O. D. Ostroumova

    2014-01-01

    Full Text Available The authors give the results of their investigation dealing with citicoline therapy in patients with hypertension and cognitive impairments.Objective: to determine the efficiency of citicoline therapy on the level and variability of both systolic and diastolic blood pressures (BP (SBP and DBP.Patients and methods. The investigation covered 60 patients with Stage II hypertension and a goal BP of < 140/90 mm Hg within ≥3 months before their inclusion. The patients were randomized into 2 groups: 30 patients in the study group were assigned to receive a cycle of 10 injections of citicoline in a daily dose of 1000 mg dropwise intravenously, then 1000 mg/day orally for as long as 3 months. 30 patients comprised the control group.Results and discussion. 24-hour BP monitoring indicated that during 4-week citicoline therapy there were significant (p<0.05 reductions in average nocturnal SBP (by 4.1±2.24 mm Hg, average daytime (-1.5±0.39 mm Hg and average nighttime (-1.5±0.37 mm Hg BP variabilities; such changes were not found in the control group. In the study group, normal daytime SBP variability at baseline (≤15 mm Hg was seen in 15 (50% patients; that after citicoline treatment was in 21 (70%; in the control group, this was in 15 (50% and 14 (46.7% patients before and after 4-week therapy, respectively. In the study group, normal nocturnal SBP variability at baseline (≤ 15 mm Hg was seen in 15 (50% patients; that after citicoline treatment was in 23 (76.7%; in the control group, this was in 15 (50% and 16 (53.3% patients, respectively.Twenty-one (70% patients in each group had baseline normal daytime DBP variability (<14 mm Hg; following 4 weeks of treatment, the number of patients with normal daytime DBP variability remained unchanged in the control group and that increased by one patient (n = 22 (73.3% in the citicoline group. Normal nocturnal DBP variability at baseline (<12 mm Hg was observed in 19 (63.3% patients in each group

  2. Application technology in coffee (Coffea arabica L.: effect of air assistance with manually driven equipment

    Directory of Open Access Journals (Sweden)

    João Miguel Francisco Ruas

    2013-12-01

    Full Text Available Small farmers in various parts of Brazil, based the application of pesticides exclusively by a coastal manual sprayers. How it is simple equipment, there are few resources available to improve the quality of the application. The aim of this paper was to study the effect of air assistance, with manual override, in the deposition and percentage of coverage applied on the leaves of coffee plants, situated internally and externally. The equipment consisted of a sprayer coastal pressurized by CO2 attached to an air assistance equipment. At the exit of air assistance equipment a hose was adapted for driving the air flow emitted to the nozzle of the sprayer coastal (XR 110-02, expanded jet plane. It was used a solution of water + potassium chloride + fluorescent dye to the application. The levels of deposits were measured by electrical conductivity of the solution from the washing leaves and the percentage of coverage by ultraviolet light. The deposition was higher in leaves positioned externally to the plant, as well as the coverage percentage. The percentage of coverage was greater for the adaxial side of the coffee leaves. There was no difference for the use or not of the air assistance. Improvements in the generation and distribution of air in manually equipments may be necessary, in order to improve its use in the application of spray liquids.

  3. Water chamber geometry and stabilizer construction effect on water pressure distribution of high pressure descaling nozzles

    Directory of Open Access Journals (Sweden)

    Hrabovský Jozef

    2012-04-01

    Full Text Available High pressure descaling nozzles are used mainly for removing oxides from hot steel products. The homogeneity and intensity of water pressure distribution on the oxidised surface are very important characteristics for a description of nozzle characteristics. The higher the water impact is the more scales are removed and the surface is cleaner. The results of water impact depend not only on the used nozzle but also on the used water stabilizer and geometry of water chamber in which the nozzle with the stabilizer is mounted. To analyse the real water pressure distribution a special measuring device was used that enables us to scan pressure distribution of the spraying nozzle. Two different nozzles were used, each with a different construction of a stabilizer. The nozzles with the stabilizers were mounted in the water chambers with different geometries. It was confirmed that water chamber geometry has a slight effect on water pressure distribution. It was also found that for some geometry of the stabilizer the water chamber geometry has a bigger effect and for some smaller. The measured values are also compared with numerical simulations in the water chamber and the stabilizer.

  4. FAST TRACK COMMUNICATION: Contrasting characteristics of sub-microsecond pulsed atmospheric air and atmospheric pressure helium-oxygen glow discharges

    Science.gov (United States)

    Walsh, J. L.; Liu, D. X.; Iza, F.; Rong, M. Z.; Kong, M. G.

    2010-01-01

    Glow discharges in air are often considered to be the ultimate low-temperature atmospheric pressure plasmas for numerous chamber-free applications. This is due to the ubiquitous presence of air and the perceived abundance of reactive oxygen and nitrogen species in air plasmas. In this paper, sub-microsecond pulsed atmospheric air plasmas are shown to produce a low concentration of excited oxygen atoms but an abundance of excited nitrogen species, UV photons and ozone molecules. This contrasts sharply with the efficient production of excited oxygen atoms in comparable helium-oxygen discharges. Relevant reaction chemistry analysed with a global model suggests that collisional excitation of O2 by helium metastables is significantly more efficient than electron dissociative excitation of O2, electron excitation of O and ion-ion recombination. These results suggest different practical uses of the two oxygen-containing atmospheric discharges, with air plasmas being well suited for nitrogen and UV based chemistry and He-O2 plasmas for excited atomic oxygen based chemistry.

  5. Schlieren imaging investigation of successive laser-induced breakdowns in atmospheric-pressure air

    Science.gov (United States)

    Bak, Moon Soo; Wermer, Lydia; Im, Seong-kyun

    2015-12-01

    Fast Schlieren imaging was performed to visualize the interactions between previously produced laser breakdown and a subsequent laser pulse. A pair of laser pulses was used to generate successive breakdowns in the quiescent standard air, and the interval between the pulses was varied from 50 ns to 100 μs to experimentally simulate various laser repetition rates. The incident laser energies ranged from 5 mJ to 31 mJ, and the energy absorbed by the breakdown of the second laser pulse was quantified by measuring the energies before and after the breakdown. The results indicate that the second laser pulse coupled to the background gas and produced a second laser breakdown only when the pulse interval was shorter than 250 ns or longer than 15 μs. For the shorter pulse intervals, the second breakdown occurred at the edge of the first breakdown region along the laser beam path, and its effect on the perturbation of the density field was found to be small. On the other hand, for the longer pulse intervals, the second breakdown occurred at the lens focal point, and the density field perturbations caused by the first and second breakdowns seemed to interact with each other inducing the Richtmyer-Mechkov instability. As a result, more significant turbulence in the density field was observed after successive laser pulse breakdowns than was observed following a single breakdown.

  6. Pressure drop and heat transfer of a mercury single-phase flow and an air-mercury two-phase flow in a helical tube under a strong magnetic field

    International Nuclear Information System (INIS)

    For the reduction of a large magneto-hydrodynamic (MHD) pressure drop of a liquid metal single-phase flow, a liquid metal two-phase flow cooling system has been proposed. As a fundamental study, MHD pressure drops and heat transfer characteristics of a mercury single-phase flow and an air-mercury two-phase flow were experimentally investigated. A strong transverse magnetic field relevant to the fusion reactor conditions was applied to the mercury single-phase flow and the air-mercury two-phase flow in a helically coiled tube that was inserted in the vertical bore of a solenoidal superconducting magnet. It was found that MHD pressure drops of a mercury single-phase flow in the helically coiled tube were nearly equal to those in a straight tube. The Nusselt number at an outside wall was higher than that at an inside wall both in the mercury single-phase flow in the absence and presence of a magnetic field. The Nusselt number of the mercury single-phase flow decreased, increased and again decreased with an increase in the magnetic flux density. MHD pressure drops did not decrease appreciably by injecting air into a mercury flow and changing the mercury flow into the air-mercury two-phase flow. Remarkable heat transfer enhancement did not appear by the air injection. The injection of air into the mercury flow enhanced heat transfer in the ranges of high mercury flow rate and low magnetic flux density, possibly due to the agitation effect of air bubbles. The air injection deteriorated heat transfer in the range of low mercury flow rates possibly because of the occupation of air near heating wall

  7. Effects of shifting time on pressure impact in hydraulic systems

    Institute of Scientific and Technical Information of China (English)

    ZHU Zhen-cai; CHEN Guo-an

    2005-01-01

    The limitations in existing measures for absorbing pressure impact in hydraulic systems were summarized in this paper. Based on the forming principle of the oil in a hydrostatic closed pressure chamber, the underlying reasons of the pressure impact were analyzed theoretically, the intrinsic laws that the extent of the pressure impact in hydraulic oil lines are affected by some factors, such as oil elastic modulus, oil line's geometrical volume, and changing rate of oil volume versus time etc, were discussed. Experimental investigations into pressure impact in all pressure chambers because of shifting were conducted under different working conditions by employing a special experimental system. The effects of shifting time on pressure impact were studied. A new concept with universal meaning, i.e. optimal shifting time, and its characterizing parameter and the methods of shifting at optimal shifting time were also proposed. The results show that shifting time lag △t is of rationality and maneuverablility. The higher the working pressure, the shorter the shifting time.

  8. DIRECT AIR BLAST EXPOSURE EFFECTS IN ANIMALS, OPERATION UPSHOT-KNOTHOLE, PROJECT 4.2

    Energy Technology Data Exchange (ETDEWEB)

    DRAEGER, R.H. (UNITED STATES NAVY - DEPARTMENT OF); LEE, R.H. (UNITED STATES NAVY - DEPARTMENT OF)

    1953-12-31

    Project 4.2 was designed to study direct (primary) air blast injury, in animals, from an atomic weapon in the range of 20 to 50 psi under circumstances affording protection against missiles, thermal and ionizing radiation and to estimate the probable direct air blast hazard in man. The pressure levels at which atomic weapons direct air blast injuries occur will determine, to a large extent, the number of blast casualties likely to be encountered. It is probable that fatal overpressures are not reached until well within the range at which indirect (secondary) blast, thermal and ionizing radiation are practically certain to prove fatal. Only in special situations affording partial protection from other injuries are blast injuries likely to be of practical importance. Two animal species of widely different body weights (700 rats and 56 dogs) were exposed, together with air pressure recorders, in aluminum cylinders, covered by sandbags and dirt but open at both ends, at seven stations distributed within the intended overpressure range of 20 to 50 psi of Shot 10« About 200 rats were likewise exposed in Shot 9. Unfortunately, the destructive effect of the air blast of Shot 10 was much greater than anticipated. Many of the exposure cylinders were displaced and their contents destroyed. Only a partial recovery of the animals was possible due to the excessive radioactive contamination which greatly limited the time in the area. Most of the animals were dead upon recovery. Those living were in a state of severe shock. Autopsy findings showed remarkably few traumatic lesions and lung hemorrhages in spite of the rough treatment and high overpressure to which they were subjected. The rats recovered from Shot 9 were exposed to a recorded pressure of 18 to 2k psi. The autopsy findings showed moderate lung hemorrhage in most of the animals undoubtedly due to direct air blast injury. The findings were typical of those seen following exposure to air blast from HE or in the shock

  9. Influence of surface emission processes on a fast-pulsed dielectric barrier discharge in air at atmospheric pressure

    Science.gov (United States)

    Pechereau, François; Bonaventura, Zdeněk; Bourdon, Anne

    2016-08-01

    This paper presents simulations of an atmospheric pressure air discharge in a point-to-plane geometry with a dielectric layer parallel to the cathode plane. Experimentally, a discharge reignition in the air gap below the dielectrics has been observed. With a 2D fluid model, it is shown that due to the fast rise of the high voltage applied and the sharp point used, a first positive spherical discharge forms around the point. Then this discharge propagates axially and impacts the dielectrics. As the first discharge starts spreading on the upper dielectric surface, in the second air gap with a low preionization density of {{10}4}~\\text{c}{{\\text{m}}-3} , the 2D fluid model predicts a rapid reignition of a positive discharge. As in experiments, the discharge reignition is much slower, a discussion on physical processes to be considered in the model to increase the reignition delay is presented. The limit case with no initial seed charges in the second air gap has been studied. First, we have calculated the time to release an electron from the cathode surface by thermionic and field emission processes for a work function φ \\in ≤ft[3,4\\right] eV and an amplification factor β \\in ≤ft[100,220\\right] . Then a 3D Monte Carlo model has been used to follow the dynamics of formation of an avalanche starting from a single electron emitted at the cathode. Due to the high electric field in the second air gap, we have shown that in a few nanoseconds, a Gaussian cloud of seed charges is formed at a small distance from the cathode plane. This Gaussian cloud has been used as the initial condition of the 2D fluid model in the second air gap. In this case, the propagation of a double headed discharge in the second air gap has been observed and the reignition delay is in rather good agreement with experiments.

  10. Effect of fresh air ventilation on indoor radon concentration

    International Nuclear Information System (INIS)

    The radon concentration of laboratory for radon simulation (LRS) was measured by the RAD7 radon monitor, and the effect of the different fresh air ventilations on indoor radon concentration was studied and analyzed. The indoor radon concentration of LRS can be accumulated up to 2000 Bq/m3 and the average radon exhalation rate of the LRS is 14.5 Bq · m-2 . h-1. Furthermore, when the fresh air enters into the LRS continuously, the indoor radon concentration decreases exponentially with the increase of time. The equilibrium radon concentration and equilibrium time of LRS decrease exponentially with the increase of the rate of fresh air ventilation. In addition, the indoor radon concentration increases by accumulation with the decrease of the rate of fresh air ventilation. (authors)

  11. Optimization of Sensing and Feedback Control for Vibration/Flutter of Rotating Disk by PZT Actuators via Air Coupled Pressure

    Directory of Open Access Journals (Sweden)

    Bingfeng Ju

    2011-03-01

    Full Text Available In this paper, a feedback control mechanism and its optimization for rotating disk vibration/flutter via changes of air-coupled pressure generated using piezoelectric patch actuators are studied. A thin disk rotates in an enclosure, which is equipped with a feedback control loop consisting of a micro-sensor, a signal processor, a power amplifier, and several piezoelectric (PZT actuator patches distributed on the cover of the enclosure. The actuator patches are mounted on the inner or the outer surfaces of the enclosure to produce necessary control force required through the airflow around the disk. The control mechanism for rotating disk flutter using enclosure surfaces bonded with sensors and piezoelectric actuators is thoroughly studied through analytical simulations. The sensor output is used to determine the amount of input to the actuator for controlling the response of the disk in a closed loop configuration. The dynamic stability of the disk-enclosure system, together with the feedback control loop, is analyzed as a complex eigenvalue problem, which is solved using Galerkin’s discretization procedure. The results show that the disk flutter can be reduced effectively with proper configurations of the control gain and the phase shift through the actuations of PZT patches. The effectiveness of different feedback control methods in altering system characteristics and system response has been investigated. The control capability, in terms of control gain, phase shift, and especially the physical configuration of actuator patches, are also evaluated by calculating the complex eigenvalues and the maximum displacement produced by the actuators. To achieve a optimal control performance, sizes, positions and shapes of PZT patches used need to be optimized and such optimization has been achieved through numerical simulations.

  12. The Effect of Air Density on Atmospheric Electric Fields Required for Lightning Initiation from a Long Airborne Object

    Science.gov (United States)

    Bazelyan, E. M.; Aleksandrov, N. L.; Raizer, Yu. Pl.; Konchankov, A. M.

    2006-01-01

    The purpose of the work was to determine minimum atmospheric electric fields required for lightning initiation from an airborne vehicle at various altitudes up to 10 km. The problem was reduced to the determination of a condition for initiation of a viable positive leader from a conductive object in an ambient electric field. It was shown that, depending on air density and shape and dimensions of the object, critical atmospheric fields are governed by the condition for leader viability or that for corona onset. To establish quantitative criteria for reduced air densities, available observations of spark discharges in long laboratory gaps were analyzed, the effect of air density on leader velocity was discussed and evolution in time of the properties of plasma in the leader channel was numerically simulated. The results obtained were used to evaluate the effect of pressure on the quantitative relationships between the potential difference near the leader tip, leader current and its velocity; based on these relationships, criteria for steady development of a leader were determined for various air pressures. Atmospheric electric fields required for lightning initiation from rods and ellipsoidal objects of various dimensions were calculated at different air densities. It was shown that there is no simple way to extend critical ambient fields obtained for some given objects and pressures to other objects and pressures.

  13. Effect of humidity on the filter pressure drop

    Energy Technology Data Exchange (ETDEWEB)

    Vendel, J.; Letourneau, P. [Institut de Protection et de Surete Nucleaire, Gif-sur-Yvette (France)

    1995-02-01

    The effects of humidity on the filter pressure drop have been reported in some previous studies in which it is difficult to draw definite conclusions. These studies show contradictory effects of humidity on the pressure drop probably due to differences in the hygroscopicity of the test aerosols. The objective of this paper is to present experimental results on the evolution of the filter pressure drop versus mass loading, for different test aerosols and relative humidities. Present results are compared to those found in various publication. An experimental device has been designed to measure filter pressure drop as the function of the areal density for relative humidity varying in the range of 9 % to 85 %. Experiments have been conducted with hygroscopic: (CsOH) and nonhygroscopic aerosols (TiO{sub 2}). Cesium hydroxyde (CsOH) of size of 2 {mu} M AMMD has been generated by an ultrasonic generator and the 0.7 {mu}m AMMD titanium oxyde has been dispersed by a {open_quotes}turn-table{close_quotes} generator. As it is noted in the BISWAS`publication [3], present results show, in the case of nonhygroscopic aerosols, a linear relationship of pressure drop to mass loading. For hygroscopic aerosols two cases must be considered: for relative humidity below the deliquescent point of the aerosol, the relationship of pressure drop to mass loading remains linear; above the deliquescent point, the results show a sudden increase in the pressure drop and the mass capacity of the filter is drastically reduced.

  14. EFFECT OF POWER SUPPLY AND DUTY CONTROL IN CRANKCASE FLOW (CRANKCASE PRESSURE PORT OF ECV

    Directory of Open Access Journals (Sweden)

    MD. IQBAL MAHMUD

    2016-06-01

    Full Text Available The electromagnetic control valve (ECV operated by solenoid in the external variable compressor with the swash plate type is the rising phenomenon. ECV controls the air conditioning compressor for automobile on the basis of the input signal of the pulse width modulation (PWM that supplied from the external controller. PWM technique is used to encode the information for transmission; its main use is to allow the control of the power to be supplied to electrical devices, especially to inertial loads. The mechanism changes the swash plate angle inside the compressor by increasing or reducing the pressure of swash plate chamber by use of the functions of different pressure port within the ECV. Increasing and reducing the swash plate angle finally depends on the solenoid force acting on the rate of supply of current. This research paper investigates the effect of power supply and duty control during the crankcase flowing at Pc pressure port of ECV.

  15. Mechanical effects on the reactor pressure vessel

    International Nuclear Information System (INIS)

    The mechanical RPV effects of a steam explosion are to be studied in an experimental program focusing on the BERDA tests. The BERDA facility has been completed. The analytical avaluation is difficult. Therefore the similarity attainable between the fluid/structure bouncing phenomena on different scales is investigated by the FLIPPER experiments. For an analytical description of the problem a model was used which had beeen developed by the CEA for the PLEXUS code. It is based on a discretization of the fluid plug by an assembly of spheres. The computational results, however, do not compare well with the FLIPPER tests and are also in disagreement with the continuum theoretical SLUGDY model. (orig.)

  16. Pressure effects on lipids and bio-membrane assemblies

    Directory of Open Access Journals (Sweden)

    Nicholas J. Brooks

    2014-11-01

    Full Text Available Membranes are amongst the most important biological structures; they maintain the fundamental integrity of cells, compartmentalize regions within them and play an active role in a wide range of cellular processes. Pressure can play a key role in probing the structure and dynamics of membrane assemblies, and is also critical to the biology and adaptation of deep-sea organisms. This article presents an overview of the effect of pressure on the mesostructure of lipid membranes, bilayer organization and lipid–protein assemblies. It also summarizes recent developments in high-pressure structural instrumentation suitable for experiments on membranes.

  17. The Effects of Popping Popcorn Under Reduced Pressure

    Science.gov (United States)

    Quinn, Paul; Cooper, Amanda

    2008-03-01

    In our experiments, we model the popping of popcorn as an adiabatic process and develop a process for improving the efficiency of popcorn production. By lowering the pressure of the popcorn during the popping process, we induce an increase in popcorn size, while decreasing the number of remaining unpopped kernels. In this project we run numerous experiments using three of the most common popping devices, a movie popcorn maker, a stove pot, and a microwave. We specifically examine the effects of varying the pressure on total sample size, flake size and waste. An empirical relationship is found between these variables and the pressure.

  18. Counterion adsorption effects on the swelling pressure in clays

    Energy Technology Data Exchange (ETDEWEB)

    Greathouse, J.A.; McQuarrie, D.A. [Univ. of California, Davis, CA (United States)

    1995-10-01

    The effects arising due to counterion adsorption in interacting planar electrical double layers is studied using modified Gouy-Chapman theory. The conditions used here model clay swelling experiments that have shown a strong dependence on the choice of counterion. The results show that the swelling pressure between charged plates depends on counterion adsorption, but they do not explain the experimental data. If the adsorption is strong enough, the swelling pressure becomes so small that it is unaffected by the plate separation. The swelling pressure is also affected by the bulk electrolyte concentration, although for a given adsorption parameter the adsorbed charge density is independent of ion concentration.

  19. High pressure effect on the superconductivity in VN

    International Nuclear Information System (INIS)

    We revisited the superconductivity in a vanadium-based superconductor VNx with a special focus on its high-pressure effect. We found that the electronic specific heat at low temperature follows a single gap BCS-type function, indicating the s-wave symmetry of superconducting gap. We also revealed that the superconducting transition temperature (Tc) enhances as the pressure increases up to 8 GPa, giving a positive differential pressure coefficient of 0.09 K/GPa. The enhancement of Tc was discussed in terms of the suppressed spin fluctuations, and the phonon softening. (author)

  20. Effect of overtime work on 24-hour ambulatory blood pressure.

    Science.gov (United States)

    Hayashi, T; Kobayashi, Y; Yamaoka, K; Yano, E

    1996-10-01

    Recently, the adverse effects of long working hours on the cardiovascular systems of workers in Japan, including "Karoshi" (death from overwork), have been the focus of social concern. However, conventional methods of health checkups are often unable to detect the early signs of such adverse effects. To evaluate the influence of overtime work on the cardiovascular system, we compared 24-hour blood pressure measurements among several groups of male white-collar workers. As a result, for those with normal blood pressure and those with mild hypertension, the 24-hour average blood pressure of the overtime groups was higher than that of the control groups; for those who periodically did overtime work, the 24-hour average blood pressure and heart rate during the busy period increased. These results indicate that the burden on the cardiovascular system of white-collar workers increases with overtime work. PMID:8899576

  1. Pressure effects on magnetism in the uranium and neptunium monopnictides

    International Nuclear Information System (INIS)

    The magnetic properties of the cubic NaCl uranium and neptunium monopnictides (UX, NpX; X=N, P, As, Sb, Bi) have been widely studied at ambient pressure. Properties ranging from itinerant to localized magnetism, and a variety of ordered magnetic structures have been observed. In particular the profusion of non-collinear double-k or triple-k structures is a consequence of strongly anisotropic exchange interactions. The application of pressure is a clean way of continuously varying the lattice parameter, and the exchange interactions, from one compound to another. A number of studies have been performed using different high pressure techniques. Some of the effects of pressure can be understood in a simple picture of a continuous variation of the lattice parameter, but some highly anomalous effects are also found which are discussed in relation to the possible nature of the magnetic interactions. (orig.)

  2. The effects of coloured quark entropy on the bag pressure

    International Nuclear Information System (INIS)

    We study the effects of the ground state entropy of coloured quarks upon the bag pressure at low temperatures. The vacuum expectation values of the quark and gluon fields are used to express the interactions in the QCD ground state in the limit of low temperatures and chemical potentials. Apparently, the inclusion of this entropy in the equation of state provides the hadron constituents with an additional heat which causes a decrease in the effective latent heat inside the hadronic bag and consequently decreases the non-perturbative bag pressure. We have considered two types of baryonic bags, Δ and Ω-. In both cases we have found that the bag pressure decreases with the temperature. On the other hand, when the coloured quark ground state entropy is not considered, the bag pressure as conventionally believed remains constant for finite temperature

  3. Characterization and biological effect of Buenos Aires urban air particles on mice lungs

    International Nuclear Information System (INIS)

    Exposure to increased levels of ambient air particulate matter (PM) is associated with increased cardiopulmonary morbidity and mortality. Its association with adverse health effects and the still unclear mechanisms of action are of concern worldwide. Our objective was to analyze air PM from downtown Buenos Aires (UAP-BA), and evaluate its biological impact on normal airways. We studied the inflammatory response to intranasal instillation of UAP-BA in a short-term-exposure mouse model. We analyzed UAP-BA morphology by scanning electron microscopy and characterized particle chemical composition by energy dispersive X-ray analysis and capillary gas chromatography. We evaluated lung changes by histomorphometry and histochemical methods. Regarding size, surface area and distribution, UAP-BA proved to be small spherical ultrafine particles: free, in clusters and associated to a matrix. The particles contained polycyclic aromatic hydrocarbons, polychlorinated biphenyls and almost no metal traces. Histologically, UAP-BA induced the recruitment of phagocytes, a reduction in air spaces, an increase in mucous PAS positive cells and weak incomplete elastic fiber network. Our results demonstrate that UAP-BA causes adverse biological effects on the respiratory tract generating inflammation that, in turn, may cause tissue injury or organ dysfunction and may contribute to the pathogenesis of lung diseases

  4. Boost Pressure Control Strategy to Account for Transient Behavior and Pumping Losses in a Two-Stage Turbocharged Air Path Concept

    Directory of Open Access Journals (Sweden)

    Thivaharan Albin

    2016-07-01

    Full Text Available Increasingly complex air path concepts are investigated to achieve a substantial reduction in fuel consumption while improving the vehicle dynamics. One promising technology is the two-stage turbocharging for gasoline engines, where a high pressure and a low pressure turbocharger are placed in series. For exploiting the high potential, a control concept has to be developed that allows for coordinated management of the two turbocharger stages. In this paper, the control strategy is investigated. Therefore, the effect of the actuated values on transient response and pumping losses is analyzed. Based on these findings, an optimization-based control algorithm is developed that allows taking both requirements into account. The developed new controller allows achieving a fast transient response, while at the same time reducing pumping losses in stationary operation.

  5. NRC Information Notice No. 92-67: Deficiency in design modifications to address failures of Hiller actuators upon a gradual loss of air pressure

    International Nuclear Information System (INIS)

    On January 7, 1992, Carolina Power and Light Company (Shearon Harris Plant) components associated with the air supply to the actuators of the three main feedwater preheater bypass isolation valves were not qualified for a Q class application. Specifically, the failure of the air pump in the non-Q Class, non-seismic instrument air supply to the valve actuator accumulator could prevent pressure switches upstream of the air pump from detecting slow leakage in the Q Class, seismic portion of the actuator air lines. The pressure switches were installed to ensure valve closure by sending an automatic close signal if the instrument air system pressure (upstream of the actuator air pump) dropped to 66 psig as discussed in IN 82-25. The main feedwater preheater bypass isolation valves function as containment isolation valves upon receipt of a feedwater isolation signal. The function of the air pump is to raise the normal instrument air supply pressure from 70 to 100 psig to approximately 150 psig. If accumulator pressure drops from 150 psig to 122 psig, the main feedwater preheater bypass isolation valve may not close within 10 seconds. If pressure drops to a value as low as 20 psig, it may not be sufficient to close the main feedwater preheater bypass isolation valve and keep it closed against the maximum differential pressure across the valve seat. Upon discovery of this condition, Shearon Harris established a surveillance interval for verifying that the actuators' components were functioning properly and that the accumulators were fully pressurized. On January 12, 1992, non-Q components were replaced with suitable components and testing was completed satisfactorily

  6. Peer Pressure in Work Teams : The effects of Inequity Aversion

    OpenAIRE

    Masclet, David

    2002-01-01

    Working Paper du GATE 2002-15 Many empirical studies have shed light on the efficiency of peer pressure. I propose here to model peer pressure by incorporating in the utility function self centered inequity aversion. I find that opportunity for sufficiently inequity averse players to punish their peers, is effective in inducing others to cooperate. At the equilibrium, all players cooperate and punish any shirker since punishing is a way to reduce inequity. Contrary, nobody cooperates witho...

  7. Radiation pressure on a moving body: beyond the Doppler effect

    OpenAIRE

    Horsley, S. A. R.; Artoni, M.; La Rocca, G. C.

    2011-01-01

    The dependence of macroscopic radiation pressure on the velocity of the object being pushed is commonly attributed to the Doppler effect. This need not be the case, and here we highlight velocity-dependent radiation pressure terms that have their origins in the mixing of s and p polarizations brought about by the Lorentz transformation between the lab and the material rest frame, rather than in the corresponding transformation of frequency and wavevector. The theory we develop may be relevant...

  8. THE EFFECT OF WATER/RESIDUAL OIL EMULSIONS ON AIR POLLUTANT EMISSIONS AND EFFICIENCY OF COMMERCIAL BOILERS

    Science.gov (United States)

    The paper gives results of tests of two commercially available water-in-oil emulsifiers to determine the effect of water/residual oil emulsions on air pollutant emissions and thermal efficiency of a packaged boiler. Of the two emulsifiers, one (Cottell reactor) used low pressure ...

  9. Air

    Science.gov (United States)

    ... house) Industrial emissions (like smoke and chemicals from factories) Household cleaners (spray cleaners, air fresheners) Car emissions (like carbon monoxide) *All of these things make up “particle pollution.” They mostly come from cars, trucks, buses, and ...

  10. Influence of ambient air pressure on the energy conversion of laser-breakdown induced blast waves

    International Nuclear Information System (INIS)

    Influence of ambient pressure on energy conversion efficiency from a Nd : glass laser pulse (λ = 1.053 µm) to a laser-induced blast wave was investigated at reduced pressure. Temporal incident and transmission power histories were measured using sets of energy meters and photodetectors. A half-shadowgraph half-self-emission method was applied to visualize laser absorption waves. Results show that the blast energy conversion efficiency ηbw decreased monotonically with the decrease in ambient pressure. The decrease was small, from 40% to 38%, for the pressure change from 101 kPa to 50 kPa, but the decrease was considerable, to 24%, when the pressure was reduced to 30 kPa. Compared with a TEA-CO2-laser-induced blast wave (λ = 10.6 µm), higher fraction absorption in the laser supported detonation regime ηLSD of 90% was observed, which is influenced slightly by the reduction of ambient pressure. The conversion fraction ηbw/ηLSD≈90% was achieved at pressure >50 kPa, which is significantly higher than that in a CO2 laser case. (paper)

  11. Arterial pressure transfer characteristics: effects of travel time.

    Science.gov (United States)

    Westerhof, Berend E; Guelen, Ilja; Stok, Wim J; Wesseling, Karel H; Spaan, Jos A E; Westerhof, Nico; Bos, Willem Jan; Stergiopulos, Nikos

    2007-02-01

    We investigated the quantitative contribution of all local conduit arterial, blood, and distal load properties to the pressure transfer function from brachial artery to aorta. The model was based on anatomical data, Young's modulus, wall viscosity, blood viscosity, and blood density. A three-element windkessel represented the distal arterial tree. Sensitivity analysis was performed in terms of frequency and magnitude of the peak of the transfer function and in terms of systolic, diastolic, and pulse pressure in the aorta. The root mean square error (RMSE) described the accuracy in wave-shape prediction. The percent change of these variables for a 25% alteration of each of the model parameters was calculated. Vessel length and diameter are found to be the most important parameters determining pressure transfer. Systolic and diastolic pressure changed <3% and RMSE <1.8 mmHg for a 25% change in vessel length and diameter. To investigate how arterial tapering influences the pressure transfer, a single uniform lossless tube was modeled. This simplification introduced only small errors in systolic and diastolic pressures (1% and 0%, respectively), and wave shape was less well described (RMSE, approximately 2.1 mmHg). Local (arm) vasodilation affects the transfer function little, because it has limited effect on the reflection coefficient. Since vessel length and diameter translate into travel time, this parameter can describe the transfer accurately. We suggest that with a, preferably, noninvasively measured travel time, an accurate individualized description of pressure transfer can be obtained. PMID:16963619

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

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Murray E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-02-23

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

  13. Effect of glow discharge air plasma on grain crops seed

    Energy Technology Data Exchange (ETDEWEB)

    Dubinov, A.E.; Lazarenko, E.M.; Selemir, V.D.

    2000-02-01

    Oat and barley seeds have been exposed to both continuous and pulsed glow discharge plasmas in air to investigate the effects on germination and sprout growth. Statistical analysis was used to evaluate the effect of plasma exposure on the percentage germination and length of sprout growth. A stimulating effect of plasma exposure was found together with a strong dependence on whether continuous or pulsed discharges were used.

  14. Heating effects of a non-equilibrium RF corona discharge in atmospheric air

    Energy Technology Data Exchange (ETDEWEB)

    Auzas, F; Makarov, M; Agneray, A [Technocentre Renault, 1 Avenue du Golf, 78288 Guyancourt (France); Tardiveau, P; Puech, V, E-mail: pierre.tardiveau@u-psud.f [Laboratoire de Physique des Gaz et des Plasmas, Bat 210, Universite Paris-Sud, 91405 Orsay Cedex (France)

    2010-12-15

    Electrical and thermal properties of a single electrode configuration corona discharge generated under radiofrequency high voltage inside an open air gap at pressures above 1 bar is investigated. Time-resolved imaging of the discharge shows a four-step development of the discharge at atmospheric pressure starting by streamers' inception and propagation, evolving in heating waves and stabilizing in a stationary regime until the power supply is switched off. The mean gas temperature reaches about 1700 K in tens of microseconds with electrical energy release around tens of millijoules. Heating has been attributed to ion collisions and excited species relaxation, promoted by the successive time periods of the power supply. At higher pressures, beyond 3 bar, this behaviour changes and heating occurs at the same time as the discharge propagates. It leads to hot channels which constrict near the electrode as long as the voltage pulse is applied. Temperature gets higher and saturates at 2600 K whatever the voltage and the pressure. Considering the change in the electrical energy density released within the plasma channels with pressure and voltage, temperature saturation seems to be an effect of heat confining within the channels due to pressure. The large and non-thermal plasma generated by the RF corona discharge is a very good candidate for car engine lean mixtures ignition issues.

  15. Heating effects of a non-equilibrium RF corona discharge in atmospheric air

    International Nuclear Information System (INIS)

    Electrical and thermal properties of a single electrode configuration corona discharge generated under radiofrequency high voltage inside an open air gap at pressures above 1 bar is investigated. Time-resolved imaging of the discharge shows a four-step development of the discharge at atmospheric pressure starting by streamers' inception and propagation, evolving in heating waves and stabilizing in a stationary regime until the power supply is switched off. The mean gas temperature reaches about 1700 K in tens of microseconds with electrical energy release around tens of millijoules. Heating has been attributed to ion collisions and excited species relaxation, promoted by the successive time periods of the power supply. At higher pressures, beyond 3 bar, this behaviour changes and heating occurs at the same time as the discharge propagates. It leads to hot channels which constrict near the electrode as long as the voltage pulse is applied. Temperature gets higher and saturates at 2600 K whatever the voltage and the pressure. Considering the change in the electrical energy density released within the plasma channels with pressure and voltage, temperature saturation seems to be an effect of heat confining within the channels due to pressure. The large and non-thermal plasma generated by the RF corona discharge is a very good candidate for car engine lean mixtures ignition issues.

  16. Pressure increase in two-phase media behind air shock waves and by shock wave accelerated pistons

    Science.gov (United States)

    Patz, G.; Smeets, G.

    Results are summarized from experimental and theoretical studies of the effects of a shock wave on a two-phase medium (TPM) and the compression of a TPM by a piston accelerated by the pressure behind a reflected shock. Attention is also given to the use of foam as the TPM and actions of the changing pressure as the shock moves to the end of the shock tube and returns. The situation is extended to the situation where the returning wave drives a piston into the foam. Analysis of the pressure variations in the foam shows that the peak pressure will depend only on the piston pressure. No shocks formed in the TMP, either in the model predictions or in an experimental validation, because the piston speed was always well below the sonic velocity in the lather.

  17. Effect of pressure on the phonon properties of europium chalcogenides

    Indian Academy of Sciences (India)

    U K Sakalle; P K Jha; S P Sanyal

    2000-06-01

    Lattice vibrational properties of europium chalcogenides have been investigated at high pressure by using a simple lattice dynamical model theory viz. the three-body force rigid ion model (TRIM) which includes long range three-body interaction arising due to charge transfer effects. The dispersion curves for the four Eu-chalcogenides agree reasonably well with the available experimental data. Variation of LO, TO, LA and TA phonons with pressure have also been studied at the symmetry points of the brillouin zone (BZ) for Euchalcogenides for the first time by using a lattice dynamical model theory. We have also calculated the one phonon density of states and compared them with the first order Raman scattering results. The calculation of one phonon density of states for Eu-chalcogenides has also been extended up to the phase transition pressure. We observed a pronounced shift in phonon spectrum as pressure is increased.

  18. Effect of pressurized steam on AA1050 aluminium

    DEFF Research Database (Denmark)

    Jariyaboon, Manthana; Møller, Per; Ambat, Rajan

    2012-01-01

    measurements were used to study corrosion behavior. Findings - A 590?nm boehmite oxide layer was generated on AA1050 associated with partially dissolved and/or fallen off Fe-containing intermetallic particles after exposure to pressurized steam. A significant reduction (25 times) in anodic and cathodic......Purpose - The purpose of this paper is to understand the effect of pressurized steam on surface changes, structures of intermetallic particles and corrosion behavior of AA1050 aluminium. Design/methodology/approach - Industrially pure aluminium (AA1050, 99.5 per cent) surfaces were exposed to...... pressurized steam produced from a commercial pressure cooker at the maximum temperature of 116oC for 10?min. Surface morphology was observed using SEM-EDX and FIB-SEM. Phase identification and compositional depth profiling were investigated using XRD and GDOES, respectively. Potentiodynamic polarization...

  19. Pressure and inductance effects on vertical stability of shaped tokamaks

    International Nuclear Information System (INIS)

    Numerical calculations are presented to show the influence of finite pressure on the vertical stability of shaped tokamaks. High εβp improves the vertical stability of dee-shaped tokamaks but is destabilizing for an inverse dee. For highly elongated cross sections, the pressure effect is well described by a linear dependence of the maximum value of stable internal inductance on εβp, with a coefficient that depends on the geometry and increases with triangularity. Stability diagrams are shown in terms of li,crit versus εβp for TCV- and DIII-D-like cross sections. The effects of pressure are significant even in the absence of a surrounding wall. Current profile effects depend critically on the wall configuration: low values of li increase the driving force of the instability, but are stabilizing if the wall is sufficiently close. (author) 8 figs., 24 refs

  20. Pressure Drop in Cyclone Separator at High Pressure

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    For the design of pressurized circulating fluidized beds, experiments were conducted in a small cyclone with 120 mm in diameter and 300 mm in height at high pressures and at atmospheric temperatures. Influence of air leakage from the stand pipe into the cyclone was specially focused. A semi-empirical model was developed for the predic tion of the pressure drop of the cyclone separator at different operate pressures with the effect of air leakage and inlet solid loading. The operate pressure, air leakage and inlet solid loading act as significant roles in cyclone pressure drop. The pressure drop increases with the increasing of pressure and decreases with the increasing of the flow rate of air leakage from the standpipe and with the increasing of the inlet solid loading.

  1. Effect of a tight necktie on intraocular pressure

    Directory of Open Access Journals (Sweden)

    Božić Marija

    2012-01-01

    Full Text Available Introduction. Any factor causing constriction of the neck may lead to an increase in intraocular pressure. A tight necktie may result in increasing intraocular pressure, which could lead to an erroneous diagnosis and treatment of ocular hypertension or even glaucoma. This study was aimed at evaluating the effect of a tight necktie on intraocular pressure measurement using Goldmann applanation tonometry. Material and Methods. This study included forty eyes of 20 patients with primary open angle glaucoma and 20 healthy controls (all male. Intraocular pressure was measured without a necktie, 3 minutes after placing a tight necktie and 3 minutes after loosening it. Student’s t-test was used to analyze the data between two groups. The intraocular pressure measurements were subjected to paired t - test. The value p < 0.05 was considered statistically significant. A possible correlation between the age of subjects and intraocular pressure values was analyzed using linear regression (Pearson′. Results. A statistically significant difference was found in intraocular pressure readings in all three measurements between two tested groups (p<0.05. When analyzed within groups, statistical significance in intraocular pressure readings was found after loosening the necktie (<0.05. No correlation between the age of subjects and increased intraocular pressure was found in either tested group of subjects after the necktie had been tightened (r2=0.006, p=0.70 for primary open angle patients, r2=0.07, p=0.22 for healthy controls. Conclusion. Wearing a tight necktie for a limited period of time during the day could be considered as a possible risk factor for glaucoma development.

  2. Measurement of OH density and air-helium mixture ratio in an atmospheric-pressure helium plasma jet

    Science.gov (United States)

    Yonemori, Seiya; Nakagawa, Yusuke; Ono, Ryo; Oda, Tetsuji

    2012-06-01

    The absolute density of OH radicals in an atmospheric-pressure helium plasma jet is measured using laser-induced fluorescence (LIF). The plasma jet is generated in room air by applying a pulsed high voltage onto a quartz tube with helium gas flow. The time-averaged OH density is 0.10 ppm near the quartz tube nozzle, decreasing away from the nozzle. OH radicals are produced from water vapour in the helium flow, which is humidified by water adsorbed on the inner surface of the helium line and the quartz tube. When helium is artificially humidified using a water bubbler, the OH density increases with humidity and reaches 2.5 ppm when the water vapour content is 200 ppm. Two-dimensional distribution of air-helium mixture ratio in the plasma jet is also measured using the decay rate of the LIF signal waveform which is determined by the quenching rate of laser-excited OH radicals.

  3. The Effects of Air Pollution and Temperature on COPD.

    Science.gov (United States)

    Hansel, Nadia N; McCormack, Meredith C; Kim, Victor

    2016-06-01

    Chronic Obstructive Pulmonary Disease (COPD) affects 12-16 million people in the United States and is the third-leading cause of death. In developed countries, smoking is the greatest risk factor for the development of COPD, but other exposures also contribute to the development and progression of the disease. Several studies suggest, though are not definitive, that outdoor air pollution exposure is linked to the prevalence and incidence of COPD. Among individuals with COPD, outdoor air pollutants are associated with loss of lung function and increased respiratory symptoms. In addition, outdoor air pollutants are also associated with COPD exacerbations and mortality. There is much less evidence for the impact of indoor air on COPD, especially in developed countries in residences without biomass exposure. The limited existing data suggests that indoor particulate matter and nitrogen dioxide concentrations are linked to increased respiratory symptoms among patients with COPD. In addition, with the projected increases in temperature and extreme weather events in the context of climate change there has been increased attention to the effects of heat exposure. Extremes of temperature-both heat and cold-have been associated with increased respiratory morbidity in COPD. Some studies also suggest that temperature may modify the effect of pollution exposure and though results are not conclusive, understanding factors that may modify susceptibility to air pollution in patients with COPD is of utmost importance. PMID:26683097

  4. Effects of Cold Air on Cardiovascular Disease Risk Factors in Rat

    OpenAIRE

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

    2012-01-01

    The purpose of this study is to explore possible potential implications of cold air in cardiovascular disease (CVD) risk in rats. Healthy Wistar rats were exposed to artificial cold air under laboratory conditions, and their systolic blood pressure, heart rate, vasoconstriction, CVD risk factors, and myocardial damage indicators after cold air exposure were determined and evaluated. Systolic blood pressure, whole blood viscosity, and plasma level of norepinephrine, angiot...

  5. Electron properties and air mixing in radio frequency driven argon plasma jets at atmospheric pressure

    International Nuclear Information System (INIS)

    A time modulated radio frequency (RF) plasma jet operated with an Ar mixture is investigated by measuring the electron density and electron temperature using Thomson scattering. The measurements have been performed spatially resolved for two different electrode configurations and as a function of the plasma dissipated power and air concentration admixed to the Ar. Time resolved measurements of electron densities and temperatures during the RF cycle and after plasma power switch-off are presented. Furthermore, the influence of the plasma on the air entrainment into the effluent is studied using Raman scattering

  6. Counter-current flow limitation experiments in a model of the hot leg of a pressurised water reactor. Comparison between low pressure air/water experiments and high pressure steam/water experiments

    International Nuclear Information System (INIS)

    In order to investigate the two-phase flow behaviour in a complex reactor-typical geometry and to supply suitable data for CFD code validation, a model of the hot leg of a pressurized water reactor was built at Forschungszentrum Dresden-Rossendorf (FZD). The hot leg model is devoted to optical measurement techniques, therefore, a flat test section design was chosen and equipped with large windows. In order to enable the operation at high pressures, the test section is installed in the pressure chamber of the TOPFLOW test facility of FZD, which is used to perform the experiments under pressure equilibrium with the inside atmosphere. Counter-current flow limitation (CCFL) experiments were performed, simulating the reflux-condenser cooling mode appearing in small break LOCA scenarios. The fluids used were air and water at room temperature and pressures of up to 3.0 bar, as well as steam and water at pressures of up to 50 bar and the corresponding saturation temperature of 264degC. One selected 50 bar experiment is presented in detail: the observed behaviour is analysed and illustrated by typical high-speed camera images of the flow. Furthermore, the flooding characteristic obtained from the different experimental runs are presented in terms of the Wallis parameter and Kutateladze number, which are commonly used in the literature. However, both parameters fail to properly correlate the data: a discrepancy is observed between the air/water and steam/water series. Therefore, a modified Wallis parameter is proposed, which takes into account the effect of the fluid viscosities on the CCFL. The new parameter is validated against comparable data found in the literature, even though no data was found with such a large range of viscosities. This analysis points out that the effect of the dynamic viscosity on flooding has already been observed, but not identified. Furthermore, it is shown that the proposed modification of the Wallis parameter allows a significant improvement

  7. Constant pressure problems of air source heat pump%空气源热泵的定压问题

    Institute of Scientific and Technical Information of China (English)

    焦宏照

    2012-01-01

    Two kinds of common methods on constant pressure of air source heat pump are analyzed, the disadvantages are pointed out, and according to the detailed calculation, the reasons are dissected and the solutions are given.%对空气源热泵定压常用的2种方式进行分析,指出其存在的弊端,经过详细计算,剖析原因,并给出解决问题的方法.

  8. Electrical Characteristics of Dielectric-Barrier Discharges in Atmospheric Pressure Air Using a Power-Frequency Voltage Source

    International Nuclear Information System (INIS)

    Dielectric-barrier discharges (DBDs) in atmospheric pressure air have been studied by using a power-frequency voltage source. In this paper the electrical characteristics of DBDs using glass and alumina dielectrics have been investigated experimentally. According to the Lissajous figures of voltage-charges, it is discovered that the discharge power for an alumina dielectric is much higher than that for a glass dielectric at the same applied voltage. Also, the voltage-current curves of the glass and alumina dielectrics confirm the fact that the dielectric barriers behave like semiconducting materials at certain applied voltages. (low temperature plasma)

  9. Investigations on the aging of activated carbons in the exhaust air of a pressurized water reactor (PWR 4)

    International Nuclear Information System (INIS)

    Investigations were performed on the aging of five activated carbons in the containment exhaust air of a German pressurized water reactor to find out whether longer stay times can be obtained with activated carbons other than that usually employed (207B (KI)) in the Federal Republic of Germany. The aging with respect to the retention of methyl iodide (CH3131I) was smaller with activated carbons impregnated with KIsub(x) only than with those impregnated additionally or exclusively with a tertiary amine (e.g. TEDA). However, because of the better performance without aging, the best retention was found with the TEDA (only) impregnant. (orig.)

  10. Acute effects of winter air pollution on respiratory health

    NARCIS (Netherlands)

    Zee, van der S.

    1999-01-01

    In this thesis, acute respiratory health effects of exposure to winter air pollution are investigated in panels of children (7-11 yr) and adults (50-70 yr) with and without chronic respiratory symptoms, living in urban and non-urban areas in the Netherlands. The study was performed during three cons

  11. A passive measurement of dissociated atom densities in atmospheric pressure air discharge plasmas using vacuum ultraviolet self-absorption spectroscopy

    International Nuclear Information System (INIS)

    We demonstrate a method for determining the dissociation degree of atmospheric pressure air discharges by measuring the self-absorption characteristics of vacuum ultraviolet radiation from O and N atoms in the plasma. The atom densities are determined by modeling the amount of radiation trapping present in the discharge, without the use of typical optical absorption diagnostic techniques which require external sources of probing radiation into the experiment. For an 8.0 mm spark discharge between needle electrodes at atmospheric pressure, typical peak O atom densities of 8.5 × 1017 cm−3 and peak N atom densities of 9.9 × 1017 cm−3 are observed within the first ∼1.0 mm of plasma near the anode tip by analyzing the OI and NI transitions in the 130.0–132.0 nm band of the vacuum ultraviolet spectrum

  12. Impact of Spatial Resolution on Wind Field Derived Estimates of Air Pressure Depression in the Hurricane Eye

    Directory of Open Access Journals (Sweden)

    Linwood Jones

    2010-03-01

    Full Text Available Measurements of the near surface horizontal wind field in a hurricane with spatial resolution of order 1–10 km are possible using airborne microwave radiometer imagers. An assessment is made of the information content of the measured winds as a function of the spatial resolution of the imager. An existing algorithm is used which estimates the maximum surface air pressure depression in the hurricane eye from the maximum wind speed. High resolution numerical model wind fields from Hurricane Frances 2004 are convolved with various HIRAD antenna spatial filters to observe the impact of the antenna design on the central pressure depression in the eye that can be deduced from it.

  13. Pulsed IR laser ablation of organic polymers in air: shielding effects and plasma pipe formation

    Energy Technology Data Exchange (ETDEWEB)

    Panchenko, A N; Shulepov, M A; Tel' minov, A E [Institute of High-Current Electronics SB RAS, 2/3 Akademichesky Ave., 634055 Tomsk (Russian Federation); Zakharov, L A; Bulgakova, N M [Institute of Thermophysics SB RAS, 1 prosp. Lavrentyev, 630090 Novosibirsk (Russian Federation); Paletsky, A A, E-mail: nbul@itp.nsc.ru [Institute of Chemical Kinetics and Combustion SB RAS, 3 Institutskaya St., 630090 Novosibirsk (Russian Federation)

    2011-09-28

    We report the effect of 'plasma pipe' formation on pulsed laser ablation of organic polymers in air under normal conditions. Ablation of polymers (PMMA, polyimide) is carried out in a wide range of CO{sub 2} laser fluences with special attention to plasma formation in the ablation products. Evolution of laser ablation plumes in air under different pressures is investigated with simultaneous registration of radiation spectra of the ablation products. An analysis based on thermo-chemical modelling is performed to elucidate the effects of laser light attenuation upon ablation, including plasma and chemical processes in a near-target space. The analysis has shown that the experimental observations of plume development in air can be explained by a combination of processes including formation of a pre-ionized channel along the laser beam propagation, laser-supported detonation wave and effective combustion of the polymer ablation products. A scenario of a streamer-like polymer plasma flow within an air plasma pipe created via laser-induced breakdown is proposed.

  14. Basement Kind Effects on Air Temperature of a Solar Chimney in Baghdad - Iraq Weather

    Directory of Open Access Journals (Sweden)

    Miqdam Tariq Chaichan

    2011-01-01

    Full Text Available A solar updraft tower power plant (solar tower is a solar thermal power plant that utilizes a combination of solar air collector and central updraft tube to generate an induced convective flow which drives pressure staged turbines to generate electricity. This paper presents practical results of a prototype of a solar chimney with thermal mass, where the glass surface is replaced by transparence plastic cover. The study focused on chimney's basements kind effect on collected air temperatures. Three basements were used: concrete, black concrete and black pebbles basements. The study was conducted in Baghdad from August to November 2009. The results show that the best chimney efficiency attained was 49.7% for pebbles base. The highest collected air temperature reached was 49ºC when using the black pebbles basement also.also, the maximum basement temperature measured was 59ºC for black pebbles. High increaments in collected air temperatures were achieved in comparison with the ambient air temperatures for the three basement kinds. The highest temperature difference reached was 22ºC with the pebble ground.

  15. Temperature effect compensation for fast differential pressure decay testing

    International Nuclear Information System (INIS)

    To avoid the long temperature recovery period with differential pressure decay for leak detection, a novel method with temperature effect compensation is proposed to improve the testing efficiency without full stabilization of temperature. The mathematical model of conventional differential pressure decay testing is established to analyze the changes of temperature and pressure during the measuring period. Then the differential pressure is divided into two parts: the exponential part caused by temperature recovery and the linear part caused by leak. With prior information obtained from samples, parameters of the exponential part can be identified precisely, and the temperature effect will be compensated before it fully recovers. To verify the effect of the temperature compensated method, chambers with different volumes are tested under various pressures and the experiments show that the improved method is faster with satisfactory precision, and an accuracy less than 0.25 cc min−1 can be achieved when the compensation time is proportional to four times the theoretical thermal-time constant. (paper)

  16. Weather induced effects on extensive air showers observed with the surface detector of the Pierre Auger Observatory

    Science.gov (United States)

    Bleve, Carla

    The rate of events measured with the surface detector (SD) of the Pierre Auger Observatory is found to be modulated by the weather conditions. This effect, observed in different ranges of S(1000), the signal measured at 1000 m from the shower core, is due to the increasing amount of matter traversed by a shower as the ground pressure increases and to the inverse proportionality of the Moliere radius to the air density near ground. The latter effect results in a modulation of the lateral spread of the shower with T and P. Air- shower simulations with different realistic profiles of the atmosphere support this interpretation of the observed effects.

  17. High-Pressure Air Injection on a Low-Head Francis Turbine

    Science.gov (United States)

    von Fellenberg, S.; Häussler, W.; Michler, W.

    2014-03-01

    Birecik is a Turkish hydroelectric power plant located at the Euphrat River in the southeast of Turkey. During commissioning of the units, a vibration phenomenon was discovered, restricted to a small power band. The cone which supports the thrust bearing and which is braced against the turbine head cover started to vibrate at its natural frequency. Investigations showed the vibrations to be innocuous to the lifetime of the machine. Exhaustive vibration measurements on site pointed to hydraulic source for the vibration. Detailed flow simulations by means of computational fluid dynamics (CFD) were carried out. They permitted the detailed analysis of a variety of transient flow phenomena happening inside the machine. They revealed the presence of interblade vortices in the power and head range where the vibrations occurred. As a consequence, it was suggested to inject air downstream of the wicket gates through the head cover. In 2012, one unit of the Birecik power plant was equipped with such an air injection system. As soon as the air injection was turned on, the machine operated calmly in the small power band where vibrations had been observed before. The necessary air volume was considerably smaller than expected to be necessary for a calm operation.

  18. High-Pressure Air Injection on a Low-Head Francis Turbine

    International Nuclear Information System (INIS)

    Birecik is a Turkish hydroelectric power plant located at the Euphrat River in the southeast of Turkey. During commissioning of the units, a vibration phenomenon was discovered, restricted to a small power band. The cone which supports the thrust bearing and which is braced against the turbine head cover started to vibrate at its natural frequency. Investigations showed the vibrations to be innocuous to the lifetime of the machine. Exhaustive vibration measurements on site pointed to hydraulic source for the vibration. Detailed flow simulations by means of computational fluid dynamics (CFD) were carried out. They permitted the detailed analysis of a variety of transient flow phenomena happening inside the machine. They revealed the presence of interblade vortices in the power and head range where the vibrations occurred. As a consequence, it was suggested to inject air downstream of the wicket gates through the head cover. In 2012, one unit of the Birecik power plant was equipped with such an air injection system. As soon as the air injection was turned on, the machine operated calmly in the small power band where vibrations had been observed before. The necessary air volume was considerably smaller than expected to be necessary for a calm operation

  19. Air cleaning efficiency of deodorant materials under dynamic conditions: effect of air flow rate

    DEFF Research Database (Denmark)

    Mizutani, Chiyomi; Bivolarova, Mariya Petrova; Melikov, Arsen Krikor;

    2014-01-01

    evaluated as deodorant materials neutralising ammonia in air. The deodorant material efficiency was tested in a special experimental set-up consisting of a straight pipe section, an ammonia gas generator, a fan and a textile frame. The deodorant materials, placed in the pipe, were exposed to a flow of air......Unpleasant odor is a serious problem in hospitals and elderly facilities. One of the unpleasant odors is ammonia originating from human urine and sweat. The air cleaning efficiency of porous activated carbon fiber fabric which has been treated with acid, and porous activated carbon fiber fabric was...... mixed with ammonia gas at a concentration of 20 ppm and velocities of 0.05, 0.15, 0.3 and 1.2 m/s. The activated carbon fibers treated with acid had a high deodorizing effect for ammonia (0.8) at a velocity of 0.05 m/s. The deodorizing effect of this material decreased with the increase in the velocity...

  20. Effect of positive pleural pressure on left ventricular performance

    International Nuclear Information System (INIS)

    A sudden increase in pleural pressure such as coughing or a valsalva maneuver causes a transient increase in left ventricular stroke volume but the mechanism is not known. To help understand this phenomenon we studied 7 normal volunteers during spontaneous breathing and when breathing under positive pleural pressure. The positive pressure was developed by expiring against a 24cm H/sub 2/O threshold load. Radionuclide ventriculopgraphy using a double gating technique as performed. Image data were acquired during the cardiac cycles occurring during positive pleural pressure by means of a pressure transducer coupled to an EKG gate. They were compared to data acquired by EKG gating alone under quiet respiration as control. Results are shown for end diastolic (EDC), end systolic (ESC) and stroke counts (SC) and are expressed as % change from control for each parameter. The authors conclude that a transient increase in positive pleural pressure comparable to that reached during forceful coughing increases stroke volume and cardiac output through a combination of increased end diastolic volume with a lesser increase in end systolic volume. This effect was seen in the absence of any change in cardiac rhythm or rate