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Sample records for air vents discharge

  1. Energy saving avoiding the centrifugal motor-compressors air vents discharge to the surrounding atmosphere; Ahorro de energia evitando venteo de aire a la atmosfera en motocompresores centrifugos

    Energy Technology Data Exchange (ETDEWEB)

    Serrano, Alex [Compressor Controls Corporation, Houston, TX (United States)

    1996-12-31

    The motor-compressors are a key part of the industrial processes. The reliability and efficient operation of a compressor is critical. The surge phenomenon is a threat in the reliability of a compressor and therefore for the process. Surge, in a centrifugal compressor is defined as a dramatic flow and pressure drop, including back-flow. This is always a significant process disturbance. Continuous surge results into costly process shutdowns and mechanical damages. To prevent surge, and control the discharge pressure with simple or obsolete controls it is needed to vent air to the surrounding atmosphere. This form of control is very inefficient and costly. An advanced control with leading technology, besides providing an economical value preventing surge damages, offers substantial energy saving reducing or eliminating the venting of air to the atmosphere. [Espanol] Los motocompresores son un aparte clave de los procesos industriales. La confiable y eficiente operacion de un compresor es critica. El fenomeno de surge es una amenaza a la confiabilidad de un compresor y por lo tanto del proceso. El surge en un compresor centrifugo es definido como una dramatica caida de flujo y presion, incluyendo flujo inverso. Esto es siempre un significante disturbio del proceso. El surge continuo resulta en costosos paros de proceso y danos mecanicos. Para prevenir el surge y controlar la presion de descarga con controles simples u obsoletos, es necesario ventear aire a la atmosfera. Esta forma de control es muy ineficiente y costosa. Un control avanzado con tecnologia de punta ademas de proveer valor economico previniendo danos por surge, provee sustanciales ahorros de energia reduciendo o eliminando el venteo de aire a la atmosfera.

  2. Visualization of the air flow behind the automotive benchmark vent

    Directory of Open Access Journals (Sweden)

    Pech Ondrej

    2015-01-01

    Full Text Available Passenger comfort in cars depends on appropriate function of the cabin HVAC system. A great attention is therefore paid to the effective function of automotive vents and proper formation of the flow behind the ventilation outlet. The article deals with the visualization of air flow from the automotive benchmark vent. The visualization was made for two different shapes of the inlet channel connected to the benchmark vent. The smoke visualization with the laser knife was used. The influence of the shape of the inlet channel to the airflow direction, its enlargement and position of air flow axis were investigated.

  3. Visualization of the air flow behind the automotive benchmark vent

    Science.gov (United States)

    Pech, Ondrej; Jedelsky, Jan; Caletka, Petr; Jicha, Miroslav

    2015-05-01

    Passenger comfort in cars depends on appropriate function of the cabin HVAC system. A great attention is therefore paid to the effective function of automotive vents and proper formation of the flow behind the ventilation outlet. The article deals with the visualization of air flow from the automotive benchmark vent. The visualization was made for two different shapes of the inlet channel connected to the benchmark vent. The smoke visualization with the laser knife was used. The influence of the shape of the inlet channel to the airflow direction, its enlargement and position of air flow axis were investigated.

  4. How many vent fields? New estimates of vent field populations on ocean ridges from precise mapping of hydrothermal discharge locations

    Science.gov (United States)

    Baker, Edward T.; Resing, Joseph A.; Haymon, Rachel M.; Tunnicliffe, Verena; Lavelle, J. William; Martinez, Fernando; Ferrini, Vicki; Walker, Sharon L.; Nakamura, Koichi

    2016-09-01

    Decades of exploration for venting sites along spreading ridge crests have produced global datasets that yield estimated mean site spacings of ∼ 12- 220 km. This conclusion demands that sites where hydrothermal fluid leaks from the seafloor are improbably rare along the 66 000 km global ridge system, despite the high bulk permeability of ridge crest axes. However, to date, exploration methods have neither reliably detected plumes from isolated low-temperature, particle-poor, diffuse sources, nor differentiated individual, closely spaced (clustered within a few kilometers) sites of any kind. Here we describe a much lower mean discharge spacing of 3-20 km, revealed by towing real-time oxidation-reduction-potential and optical sensors continuously along four fast- and intermediate-rate (>55 mm/yr) spreading ridge sections totaling 1470 km length. This closer spacing reflects both discovery of isolated sites discharging particle-poor plumes (25% of all sites) and improved discrimination (at a spatial resolution of ∼1 km) among clustered discrete and diffuse sources. Consequently, the number of active vent sites on fast- and intermediate-rate spreading ridges may be at least a factor of 3-6 higher than now presumed. This increase provides new quantitative constraints for models of seafloor processes such as dispersal of fauna among seafloor and crustal chemosynthetic habitats, biogeochemical impacts of diffuse venting, and spatial patterns of hydrothermal discharge.

  5. Helium corona-assisted air discharge

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Nan; Gao Lei; Ji Ailing; Cao Zexian [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2011-10-15

    Operation of atmospheric discharge of electronegative gases including air at low voltages yet without consuming any inert gas will enormously promote the application of non-thermal plasmas. By taking advantage of the low onset voltage for helium corona, air discharge was successfully launched at much reduced voltages with a needle-plate system partly contained in a helium-filled glass bulb--for a needle-plate distance of 12 mm, 1.0 kV suffices. Ultraviolet emission from helium corona facilitates the discharging of air, and the discharge current manifests distinct features such as relatively broad Trichel pulses in both half periods. This design allows safe and economic implementation of atmospheric discharge of electronegative gases, which will find a broad palette of applications in surface modification, plasma medicine and gas treatment, etc.

  6. Behaviour of air discharged from a sparger

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Yoon Yeong [Korea Atomic Energy Research Institute, Taejeon (Korea)

    2000-03-01

    This research has been performed as a part of the project, Development of Design Verification Technology for Korea Next Generation Reactor. At first, current state of the art of the bubble dynamics and the result will be used to develop an optimum tool including computer code for analysis of air or air-steam mixture bubble, which is discharged from a sparger. Introduced are linear perturbation; spherical bubble cloud theory; bubble interaction; and Volume of Fluid, a method of tracking free surface, which is to be used in computational fluid dynamics. An analysis was performed for the oscillation of an air bubble of perfect spherical shape. The heat transfer through the bubble surface is considered, although the effect was not so significant. The effect of initial and boundary conditions were investigated and the correlation equation was developed. 42 refs., 22 figs., 2 tabs. (Author)

  7. MICRO ELECTRICAL DISCHARGE MACHINING DEPOSITION IN AIR

    Institute of Scientific and Technical Information of China (English)

    JIN Baidong; ZHAO Wansheng; WANG Zhenlong; CAO Guohui

    2006-01-01

    A new deposition method is described using micro electrical discharge machining (EDM)to deposit tool electrode material on workpiece in air. The basic principles of micro electrical discharge deposition (EDD) are analyzed and the realized conditions are predicted. With an ordinary EDM shaping machine, brass as the electrode, high-speed steel as the workpiece, a lot of experiments are carried out on micro EDD systematically and thoroughly. The effects of major processing parameters, such as the discharge current, discharge duration, pulse interval and working medium, are obtained. As a result, a micro cylinder with 0.19 mm in diameter and 7.35 mm in height is deposited.By exchanging the polarities of the electrode and workpiece the micro cylinder can be removed selectively. So the reversible machining of deposition and removal is achieved, which breaks through the constraint of traditional EDM. Measurements show that the deposited material is compact and close to workpiece base, whose components depend on the tool electrode material.

  8. Impacts of Ventilation Ratio and Vent Balance on Cooling Load and Air Flow of Naturally Ventilated Attics

    Directory of Open Access Journals (Sweden)

    Zhigang Shen

    2012-08-01

    Full Text Available The impacts of ventilation ratio and vent balance on cooling load and air flow of naturally ventilated attics are studied in this paper using an unsteady computational fluid dynamics (CFD model. Buoyancy-driven turbulent ventilations in attics of gable-roof residential buildings are simulated for typical summer conditions. Ventilation ratios from 1/400 to 1/25 combined with both balanced and unbalanced vent configurations are investigated. The modeling results show that the air flows in the attics are steady and exhibit a general streamline pattern that is qualitatively insensitive to the variations in ventilation ratio and vent configuration. The predicted temperature fields are characterized by thermal stratification, except for the soffit regions. It is demonstrated that an increase in ventilation ratio will reduce attic cooling load. Compared with unbalanced vent configurations, balanced attic ventilation is shown to be the optimal solution in both maximizing ventilating flow rate and minimizing cooling load for attics with ventilation ratio lower than 1/100. For attics with ventilation ratios greater than 1/67, a configuration of large ridge vent with small soffit vent favors ventilating air flow enhancement, while a configuration of small ridge vent with large soffit vent results in the lowest cooling energy consumption.

  9. Energy savings in one-pipe steam heating systems fitted with high-capacity air vents. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1994-09-01

    Multifamily buildings heated by one-pipe steam systems experience significant temperature gradients from apartment to apartment, often reaching 15{degrees}F. As a result, many tenants are to cold, or if the heating system output is increased so as to heat the coldest apartment adequately, too hot. While both are undesirable, the second is particularly so because it wastes energy. It was thought that insufficient air venting of the steam pipes contributed to the gradient. Theoretically, if steam mains and risers are quickly vented, steam will reach each radiator at approximately the same time and balance apartment temperatures. The project`s objective was to determine if the installation of large-capacity air vents at the ends of steam mains and risers would economically reduce the temperature gradient between apartments and reduce the amount of space heating energy required. The test was conducted by enabling and disabling air vents biweekly in 10 multifamily buildings in New York City between December 1992 to May 1993. The temperatures of selected apartments and total space heating energy were compared during each venting regime. There was no difference in energy consumption between ``vents on`` and ``vents off`` periods (see Tables 2 and 5); however, there was a reduction in the maximum spread of apartment temperatures.

  10. The effect of ignition location on explosion venting of hydrogen-air mixtures

    Science.gov (United States)

    Cao, Y.; Guo, J.; Hu, K.; Xie, L.; Li, B.

    2017-02-01

    The effect of ignition location and vent burst pressure on the internal pressure-time history and external flame propagation was investigated for vented explosions of hydrogen-air mixtures in a small cylindrical vessel. A high-speed camera was used to record videos of the external flame while pressure transducers were used to record pressure-time histories. It was found that central ignition always leads to the maximum internal peak overpressure, and front ignition resulted in the lowest value of internal peak overpressure. The internal peak overpressures are increased corresponding to the increase in the vent burst pressure in the cases of central and rear ignition. Because of the effect of acoustic oscillations, the phenomenon of oscillations is observed in the internal pressure profile for the case of front ignition. The pressure oscillations for the cases of rear and central ignition are triggered by external explosions. The behavior of flames outside the chamber is significantly associated with the internal pressure of the chamber so that the velocity of the jet flame is closely related to the internal overpressure peak.

  11. 40 CFR 52.1988 - Air contaminant discharge permits.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Air contaminant discharge permits. 52.1988 Section 52.1988 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Oregon § 52.1988 Air...

  12. Pulsed positive streamer discharges in air at high temperatures

    Science.gov (United States)

    Ono, Ryo; Kamakura, Taku

    2016-08-01

    Atmospheric-pressure air pulsed positive streamer discharges are generated in a 13 mm point-plane gap in the temperature range of 293 K-1136 K, and the effect of temperature on the streamer discharges is studied. When the temperature is increased, the product of applied voltage and temperature VT proportional to the reduced electric field can be used as a primary parameter that determines some discharge parameters regardless of temperature. For a given VT, the transferred charge per pulse, streamer diameter, product of discharge energy and temperature, and length of secondary streamer are almost constant regardless of T, whereas the streamer velocity decreases with increasing T and the decay rate of the discharge current is proportional to 1/T. The N2(C) emission intensity is approximately determined by the discharge energy independent of T. These results are useful to predict the streamer discharge and its reactive species production when the ambient temperature is increased.

  13. Modification of various metals by volume discharge in air atmosphere

    Science.gov (United States)

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

    2015-12-01

    The results of the modification of stainless steel, niobium and titanium by volume discharge induced by a beam of runaway electrons in air under normal pressure are presented. Changes in the chemical composition of the surface layers of metal by the action of the discharge, structural changes and changes of hardness were studied. It has been found that the concentration of oxygen and carbon in the surface layers of the samples depend on the number of discharge pulses. The aim of this work is to find possible application of this type of discharge in science and industrial production.

  14. Monte Carlo simulation of electrical corona discharge in air

    Energy Technology Data Exchange (ETDEWEB)

    Settaouti, A.; Settaouti, L. [Electrotechnic Department, University of Sciences and Technology, P.O. Box 1505, El-M' naouar, Oran (Algeria)

    2011-01-15

    Electrical discharges play a key role in technologies; there are many industrial applications where the corona discharge is used. Air as insulator is probably the best compromise solution for many applications. All of this reflects on the great importance of the evaluation of the corona performance characteristics. Numerical simulation of the corona discharge helps to better understand the involved phenomena and optimize the corona devices. This paper is aimed at calculating the corona discharge in negative point-plane air gaps. To describe the non-equilibrium behavior of the electronic avalanches and to simulate the development of corona discharge the method of Monte Carlo has been used. This model provides the spatial-temporal local field and particles charged densities variations as well as the ionization front velocity. (author)

  15. Air/oil separator with minimal space requirements in the crankcase venting system; Oelnebelabscheidung in der Kurbelgehaeuseentlueftung auf engstem Raum

    Energy Technology Data Exchange (ETDEWEB)

    Bastias, P. [Dana Sealing and Plastics Products Design Center, Paris, TN (United States); Brueckle, T.; Grafl, D.; Sattler-Laegel, T.; Spaeth, B. [Reinz-Dichtungs-GmbH, Neu-Ulm (Germany); Caloghero, D. [Victor Reinz Mercosur (VRM), Gravatai (Brazil)

    2005-12-01

    An important function for crankcase venting is the separation of oil mist from the blow-by gas. In this area, engine builders place widely varying demands on their development suppliers. Not only must air/oil separator systems be highly efficient, robust, functionally reliable, flexible and compact, they must also be cost-effective. Reinz-Dichtungs-GmbH, a Dana Corporation company, set up a global development team to take on the challenge. The result is one of today's smallest and at the same time most efficient air/oil separator systems - the Multitwister. (orig.)

  16. Spatiotemporally resolved characteristics of a gliding arc discharge in a turbulent air flow at atmospheric pressure

    DEFF Research Database (Denmark)

    Zhu, Jiajian; Gao, Jinlong; Ehn, Andreas

    2017-01-01

    A gliding arc discharge was generated in a turbulent air flow at atmospheric pressure driven by a 35 kHz alternating current (AC) electric power. The spatiotemporally resolved characteristics of the gliding arc discharge, including glow-type discharges, spark-type discharges, short-cutting events...

  17. Numerical Investigation of Air-cooled Cylindrical Lithium-ion Battery Thermal Management System with Vent%增设通风孔的风冷式锂离子电池热管理系统数值研究

    Institute of Scientific and Technical Information of China (English)

    张新强; 洪思慧; 汪双凤

    2015-01-01

    电池热管理系统的优化设计可以维持动力电池的高效性能,进而促进电动汽车产业的发展.本文采用CFD方法研究有通风孔的情况下,风冷式锂离子电池组在放电过程中的散热性能.研究结果发现,在电池组外壳增设通风孔可以明显提高整个电池组的冷却效果.风孔开设在主出风口的相反方向时,电池组的温升和温差最小.当风孔的面积与出口面积相等时,电池组的冷却效果最佳;继续增大风孔对电池组的冷却效果影响较小.最后探讨了空气进口温度和电池间冷却通道的变化对电池组散热效果的影响.采用在电池组外壳上开设多个通风孔的办法有助于电池热管理系统的冷却优化设计.%The optimum design of battery thermal management system helps maintaining the high efficient performance of power battery, which will contribute to the development of the electric vehicle industry. In this research, a CFD model for an air-cooled battery pack with vent is developed to investigate the thermal performance of battery during discharging. It's found that the additional vent can significantly improve the cooling performance of the entire battery pack. Temperature rise and temperature difference of the battery pack reach the lowest when the vent is opened at the opposite of the outlet. Moreover, the best cooling performance is achieved as the area of the vent equals to that of the outlet. However, continuously increasing the area of the vent makes little difference on improving the cooling performance. The effects of the inlet air temperature and the volume of the cooling channel on the thermal performance of lithium-ion battery pack are also investigated. Opening multiple vents in the battery pack enable to the optimum design on the cooling capability of the battery thermal management system.

  18. Optical Emission Spectroscopic Measurement of Hydroxyl Radicals in Air Discharge with Atomized Water%Optical Emission Spectroscopic Measurement of Hydroxyl Radicals in Air Discharge with Atomized Water

    Institute of Scientific and Technical Information of China (English)

    孙明; 陈维刚; 张颖

    2011-01-01

    Effects of discharge mode, voltage applied, size of the nozzle discharge electrode and flow rate of water on the generation of hydroxyl radical were investigated in air discharge with atomized water, by using optical emission spectroscopy (OES). Water was injected into the discharge region through the discharge nozzle electrode, and a large amount of fine water drops, formed and distributed in the discharge region, corona discharge was more effective to generate were observed. It was found that negative DC the hydroxyl radicals in comparison to positive DC corona discharge or negative pulsed discharge. A larger outer diameter of the nozzle electrode or a stronger electric field is beneficial for hydroxyl-radical generation. Moreover, there is a critical value in the flow rate of atomized water against the discharge voltage. Below this critical value, hydroxyl-radical generation increases with the increase in flow rate of the water, while above this value, it decreases. In addition, it is observed that OES from the discharge is mainly in the ultraviolet domain. The results are helpful in the study of the mechanism and application of plasma in pollution-control in either air or water.

  19. Investigation of Nanosecond Pulsed Discharge and Its Audio Characteristics in Atmospheric-pressure Air

    Institute of Scientific and Technical Information of China (English)

    REN Chengyan; RAN Huijuan; WANG Jue; WANG Tao; YAN Ping

    2013-01-01

    There was no well-resolved mechanism of audible noise caused by corona discharge on UHV transmission lines.Hence we measured the sound pressure of pulsed discharges between needle-plane electrodes under different discharge conditions in air,for revealing the intrinsic relationship between discharge and its audible noise(AN).The relationship between discharge parameters and audio characteristics was drawn from the analysis of the electric and sound signals obtained in experiments.Experiment results showed that nanosecond pulsed discharges produce the sound pressure with a microsecond pulse lagging behind the discharge pulse in their waveforms.The peak value of the sound pulse decreases and its high frequency component gradually attenuates,when the measuring distance from discharges increases.The sound pulses correlate with the discharge current and voltage significantly,especially the current.The audible noise produced by repetitive pulsed discharge increases with the strength,duration,and pulse repetition rate of discharge.

  20. Cryogenic Cooling System for Zero-Venting Storage of Supercritical Air Packs Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Supercritical air at cryogenic temperature is an attractive source of breathing air because of its very high density and low pressure. However, heat leak into the...

  1. CFD simulation of air discharge tests in the PPOOLEX facility

    Energy Technology Data Exchange (ETDEWEB)

    Tanskanen, V.; Puustinen, M. (Lappeenranta Univ. of Technology, Nuclear Safety Research Unit (Finland))

    2008-07-15

    This report summarizes the CFD simulation results of two air discharge tests of the characterizing test program in 2007 with the scaled down PPOOLEX facility. Air was blown to the dry well compartment and from there through a DN200 blowdown pipe into the condensation pool (wet well). The selected tests were modeled with Fluent CFD code. Test CHAR-09-1 was simulated to 28.92 seconds of real time and test CHAR-09-3 to 17.01 seconds. The VOF model was used as a multiphase model and the standard k epsilon-model as a turbulence model. Occasional convergence problems, usually at the beginning of bubble formation, required the use of relatively short time stepping. The simulation time costs threatened to become unbearable since weeks or months of wall-clock time with 1-2 processors were needed. Therefore, the simulated time periods were limited from the real duration of the experiments. The results obtained from the CFD simulations are in a relatively good agreement with the experimental results. Simulated pressures correspond well to the measured ones and, in addition, fluctuations due to bubble formations and breakups are also captured. Most of the differences in temperature values and in their behavior seem to depend on the locations of the measurements. In the vicinity of regions occupied by water in the experiments, thermocouples getting wet and drying slowly may have had an effect on the measured temperature values. Generally speaking, most temperatures were simulated satisfyingly and the largest discrepancies could be explained by wetted thermocouples. However, differences in the dry well and blowdown pipe top measurements could not be explained by thermocouples getting wet. Heat losses and dry well / wet well heat transfer due to conduction have neither been estimated in the experiments nor modeled in the simulations. Estimation of heat conduction and heat losses should be carried out in future experiments and they should be modeled in future simulations, too. (au)

  2. Quantification of topographic venting of boundary layer air to the free troposphere

    Directory of Open Access Journals (Sweden)

    S. Henne

    2004-01-01

    Full Text Available Net vertical air mass export by thermally driven flows from the atmospheric boundary layer (ABL to the free troposphere (FT above deep Alpine valleys was investigated. The vertical export of pollutants above mountainous terrain is presently poorly represented in global chemistry transport models (GCTMs and needs to be quantified. Air mass budgets were calculated using aircraft observations obtained in deep Alpine valleys. The results show that on average 3 times the valley air mass is exported vertically per day under fair weather conditions. During daytime the type of valleys investigated in this study can act as an efficient 'air pump' that transports pollutants upward. The slope wind system within the valley plays an important role in redistributing pollutants. Nitrogen oxide emissions in mountainous regions are efficiently injected into the FT. This could enhance their ozone (O3 production efficiency and thus influences tropospheric pollution budgets. Once lifted to the FT above the Alps pollutants are transported horizontally by the synoptic flow and are subject to European pollution export. Forward trajectory studies show that under fair weather conditions two major pathways for air masses above the Alps dominate. Air masses moving north are mixed throughout the whole tropospheric column and further transported eastward towards Asia. Air masses moving south descend within the subtropical high pressure system above the Mediterranean.

  3. Quantification of topographic venting of boundary layer air to the free troposphere

    Directory of Open Access Journals (Sweden)

    S. Henne

    2003-10-01

    Full Text Available Net vertical air mass export by thermally driven f/lows from the atmospheric boundary layer (ABL to the free troposphere (FT above deep Alpine valleys was investigated. The vertical export of pollutants above mountainous terrain is presently poorly represented in global chemistry transport models (GCTMs and needs to be quantified. Air mass budgets were calculated using aircraft observations obtained in deep Alpine valleys. The results show that on average 3 times the valley air mass is exported vertically per day under fair weather conditions. During daytime the type of valleys investigated in this study can act as an efficient "air pump" that transports pollutants upward. The slope wind system within the valley plays an important role in redistributing pollutants. Nitrogen oxide emissions in mountainous regions are efficiently injected into the FT. This enhances their ozone production efficiency and thus influences tropospheric pollution budgets. Once lifted to the FT above the Alps pollutants are transported horizontally by the synoptic flow and are subject to European pollution export. Forward trajectory studies show that under fair weather conditions two major pathways for air masses above the Alps dominate. Air masses moving north are mixed throughout the whole tropospheric column and further transported eastward towards Asia. Air masses moving south descend within the subtropical high pressure system above the Mediterranean.

  4. Flammability limits of lithium-ion battery thermal runaway vent gas in air and the inerting effects of halon 1301

    Science.gov (United States)

    Karp, Matthew Eugene

    Lithium-ion (rechargeable) and lithium-metal (non-rechargeable) battery cells put aircraft at risk of igniting and fueling fires. Lithium batteries can be packed in bulk and shipped in the cargo holds of freighter aircraft; currently lithium batteries are banned from bulk shipment on passenger aircraft [1]. The federally regulated Class C cargo compartment extinguishing system's utilization of a 5 %vol Halon 1301 knockdown concentration and a sustained 3 %vol Halon 1301 may not be sufficient at inerting lithium-ion battery vent gas and air mixtures [2]. At 5 %vol Halon 1301 the flammability limits of lithium-ion premixed battery vent gas (Li-Ion pBVG) in air range from 13.80 %vol to 26.07 %vol Li-Ion pBVG. Testing suggests that 8.59 %vol Halon 1301 is required to render all ratios of the Li-Ion pBVG in air inert. The lower flammability limit (LFL) and upper flammability limit (UFL) of hydrogen and air mixtures are 4.95 %vol and 76.52 %vol hydrogen, respectively. With the addition of 10 %vol and 20 %vol Halon 1301 the LFL is 9.02 %vol and 11.55 %vol hydrogen, respectively, and the UFL is 45.70 %vol and 28.39 %vol hydrogen, respectively. The minimum inerting concentration (MIC) of Halon 1301 in hydrogen and air mixtures is 26.72 %vol Halon 1301 at 16.2 %vol hydrogen. The LFL and UFL of Li-Ion pBVG and air mixtures are 7.88 %vol and 37.14 %vol Li-Ion pBVG, respectively. With the addition of 5 %vol, 7 %vol, and 8 %vol Halon 1301 the LFL is 13.80 %vol, 16.15 %vol, and 17.62 % vol Li-Ion pBVG, respectively, and the UFL is 26.07 %vol, 23.31 %vol, and 21.84 %vol Li- Ion pBVG, respectively. The MIC of Halon 1301 in Li-Ion pBVG and air mixtures is 8.59 %vol Halon 1301 at 19.52 %vol Li-Ion pBVG. Le Chatelier's mixing rule has been shown to be an effective measure for estimating the flammability limits of Li-Ion pBVGes. The LFL has a 1.79 % difference while the UFL has a 4.53 % difference. The state of charge (SOC) affects the flammability limits in an apparent parabolic

  5. Charging of moving surfaces by corona discharges sustained in air

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jun-Chieh, E-mail: junchwan@umich.edu; Kushner, Mark J., E-mail: mjkush@umich.edu [Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Ave., Ann Arbor, Michigan 48109-2122 (United States); Zhang, Daihua, E-mail: dhzhang@tju.edu.cn [Tianjin University, Tianjin (China); Leoni, Napoleon, E-mail: napoleon.j.leoni@hp.com; Birecki, Henryk, E-mail: henryk.birecki@hp.com; Gila, Omer, E-mail: omer-gila@hp.com [Hewlett-Packard Research Labs, Palo Alto, California 94304 (United States)

    2014-07-28

    Atmospheric pressure corona discharges are used in electrophotographic (EP) printing technologies for charging imaging surfaces such as photoconductors. A typical corona discharge consists of a wire (or wire array) biased with a few hundred volts of dc plus a few kV of ac voltage. An electric discharge is produced around the corona wire from which electrons drift towards and charge the underlying dielectric surface. The surface charging reduces the voltage drop across the gap between the corona wire and the dielectric surface, which then terminates the discharge, as in a dielectric barrier discharge. In printing applications, this underlying surface is continuously moving throughout the charging process. For example, previously charged surfaces, which had reduced the local electric field and terminated the local discharge, are translated out of the field of view and are replaced with uncharged surface. The uncharged surface produces a rebound in the electric field in the vicinity of the corona wire which in turn results in re-ignition of the discharge. The discharge, so reignited, is then asymmetric. We found that in the idealized corona charging system we investigated, a negatively dc biased corona blade with a dielectric covered ground electrode, the discharge is initially sustained by electron impact ionization from the bulk plasma and then dominated by ionization from sheath accelerated secondary electrons. Depending on the speed of the underlying surface, the periodic re-ignition of the discharge can produce an oscillatory charging pattern on the moving surface.

  6. Charging of moving surfaces by corona discharges sustained in air

    Science.gov (United States)

    Wang, Jun-Chieh; Zhang, Daihua; Leoni, Napoleon; Birecki, Henryk; Gila, Omer; Kushner, Mark J.

    2014-07-01

    Atmospheric pressure corona discharges are used in electrophotographic (EP) printing technologies for charging imaging surfaces such as photoconductors. A typical corona discharge consists of a wire (or wire array) biased with a few hundred volts of dc plus a few kV of ac voltage. An electric discharge is produced around the corona wire from which electrons drift towards and charge the underlying dielectric surface. The surface charging reduces the voltage drop across the gap between the corona wire and the dielectric surface, which then terminates the discharge, as in a dielectric barrier discharge. In printing applications, this underlying surface is continuously moving throughout the charging process. For example, previously charged surfaces, which had reduced the local electric field and terminated the local discharge, are translated out of the field of view and are replaced with uncharged surface. The uncharged surface produces a rebound in the electric field in the vicinity of the corona wire which in turn results in re-ignition of the discharge. The discharge, so reignited, is then asymmetric. We found that in the idealized corona charging system we investigated, a negatively dc biased corona blade with a dielectric covered ground electrode, the discharge is initially sustained by electron impact ionization from the bulk plasma and then dominated by ionization from sheath accelerated secondary electrons. Depending on the speed of the underlying surface, the periodic re-ignition of the discharge can produce an oscillatory charging pattern on the moving surface.

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

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Wenzheng, E-mail: wzhliu@bjtu.edu.cn; Sun, Guangliang, E-mail: 11121659@bjtu.edu.cn; Li, Chuanhui; Zhang, Rongrong [School of Electrical Engineering, Beijing Jiaotong University, Beijing 100044 (China)

    2014-04-15

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

  8. The Experimental Investigations of Dielectric Barrier Discharge and Pulse Corona Discharge in Air Cleaning

    Institute of Scientific and Technical Information of China (English)

    左莉; 侯立安; 杨林松

    2003-01-01

    The dielectric barrier discharge (DBD) and pulse corona discharge(PCD) plasmagenerator was used to remove NH3, H2S, C7Hs etc. from atmosphere. The principle and charac-teristic of the two ways was discussed in the article. The test shows the result of PCD is betterthan that of DBD.

  9. Nonradioactive Air Emissions Notice of Construction (NOC) Application for the Central Waste Complex (CSC) for Storage of Vented Waste Containers

    Energy Technology Data Exchange (ETDEWEB)

    KAMBERG, L.D.

    2000-04-01

    This Notice of Construction (NOC) application is submitted for the storage and management of waste containers at the Central Waste Complex (CWC) stationary source. The CWC stationary source consists of multiple sources of diffuse and fugitive emissions, as described herein. This NOC is submitted in accordance with the requirements of Washington Administrative Code (WAC) 173-400-110 (criteria pollutants) and 173-460-040 (toxic air pollutants), and pursuant to guidance provided by the Washington State Department of Ecology (Ecology). Transuranic (TRU) mixed waste containers at CWC are vented to preclude the build up of hydrogen produced as a result of radionuclide decay, not as safety pressure releases. The following activities are conducted within the CWC stationary source: Storage and inspection; Transfer and staging; Packaging; Treatment; and Sampling. This NOC application is intended to cover all existing storage structures within the current CWC treatment, storage, and/or disposal (TSD) boundary, as well as any storage structures, including waste storage pads and staging areas, that might be constructed in the future within the existing CWC boundary.

  10. Piezoelectric transformers for low-voltage generation of gas discharges and ionic winds in atmospheric air

    Science.gov (United States)

    Johnson, Michael J.; Go, David B.

    2015-12-01

    To generate a gas discharge (plasma) in atmospheric air requires an electric field that exceeds the breakdown threshold of ˜30 kV/cm. Because of safety, size, or cost constraints, the large applied voltages required to generate such fields are often prohibitive for portable applications. In this work, piezoelectric transformers are used to amplify a low input applied voltage (corona-like discharges on its corners or on adjacent electrodes. In the proper configuration, these discharges can be used to generate a bulk air flow called an ionic wind. In this work, PT-driven discharges are characterized by measuring the discharge current and the velocity of the induced ionic wind with ionic winds generated using input voltages as low as 7 V. The characteristics of the discharge change as the input voltage increases; this modifies the resonance of the system and subsequent required operating parameters.

  11. Comparison of atmospheric air plasmas excited by high-voltage nanosecond pulsed discharge and sinusoidal alternating current discharge

    Science.gov (United States)

    Zhang, Shuai; Wang, Wen-chun; Jiang, Peng-chao; Yang, De-zheng; Jia, Li; Wang, Sen

    2013-10-01

    In this paper, atmospheric pressure air discharge plasma in quartz tube is excited by 15 ns high-voltage nanosecond pulsed discharge (HVNPD) and sinusoidal alternating current discharge (SACD), respectively, and a comparison study of these two kinds of discharges is made through visual imaging, electrical characterization, optical detection of active species, and plasma gas temperature. The peak voltage of the power supplies is kept at 16 kV while the pulse repetition rate of nanosecond pulse power supply is 100 Hz, and the frequency of sinusoidal power supply is 10 kHz. Results show that the HVNPD is uniform while the SACD presents filamentary mode. For exciting the same cycles of discharge, the average energy consumption in HVNPD is about 1/13 of the SACD. However, the chemical active species generated by the HVNPD is about 2-9 times than that excited by the SACD. Meanwhile, the rotational and vibrational temperatures have been obtained via fitting the simulated spectrum of N2 (C3Πu → B3Πg, 0-2) with the measured one, and the results show that the plasma gas temperature in the HVNPD remains close to room temperature whereas the plasma gas temperature in the SACD is about 200 K higher than that in HVNPD in the initial phase and continually increases as discharge exposure time goes on.

  12. Measure Guideline: Passive Vents

    Energy Technology Data Exchange (ETDEWEB)

    Berger, David [Consortium for Advanced Residential Buildings, Norwalk, CT (United States); Neri, Robin [Consortium for Advanced Residential Buildings, Norwalk, CT (United States)

    2016-02-05

    This document addresses the use of passive vents as a source of outdoor air in multifamily buildings. The challenges associated with implementing passive vents and the factors affecting performance are outlined. A comprehensive design methodology and quantified performance metrics are provided. Two hypothetical design examples are provided to illustrate the process. This document is intended to be useful to designers, decision-makers, and contractors implementing passive ventilation strategies. It is also intended to be a resource for those responsible for setting high-performance building program requirements, especially pertaining to ventilation and outdoor air. To ensure good indoor air quality, a dedicated source of outdoor air is an integral part of high-performance buildings. Presently, there is a lack of guidance pertaining to the design and installation of passive vents, resulting in poor system performance. This report details the criteria necessary for designing, constructing, and testing passive vent systems to enable them to provide consistent and reliable levels of ventilation air from outdoors.

  13. 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...

  14. Electro-Hydrodynamics and Kinetic Modeling of Dry and Humid Air Flows Activated by Corona Discharges

    Science.gov (United States)

    P. Sarrette, J.; Eichwald, O.; Marchal, F.; Ducasse, O.; Yousfi, M.

    2016-05-01

    The present work is devoted to the 2D simulation of a point-to-plane Atmospheric Corona Discharge Reactor (ACDR) powered by a DC high voltage supply. The corona reactor is periodically crossed by thin mono filamentary streamers with a natural repetition frequency of some tens of kHz. The study compares the results obtained in dry air and in air mixed with a small amount of water vapour (humid air). The simulation involves the electro-dynamics, chemical kinetics and neutral gas hydrodynamics phenomena that influence the kinetics of the chemical species transformation. Each discharge lasts about one hundred of a nanosecond while the post-discharge occurring between two successive discharges lasts one hundred of a microsecond. The ACDR is crossed by a lateral dry or humid air flow initially polluted with 400 ppm of NO. After 5 ms, the time corresponding to the occurrence of 50 successive discharge/post-discharge phases, a higher NO removal rate and a lower ozone production rate are found in humid air. This change is due to the presence of the HO2 species formed from the H primary radical in the discharge zone.

  15. Electro-Hydrodynamics and Kinetic Modeling of Dry and Humid Air Flows Activated by Corona Discharges

    Institute of Scientific and Technical Information of China (English)

    J.P.SARRETTE; O.EICHWALD; F.MARCHAL; O.DUCASSE; M.YOUSFI

    2016-01-01

    The present work is devoted to the 2D simulation of a point-to-plane Atmospheric Corona Discharge Reactor (ACDR) powered by a DC high voltage supply.The corona reactor is periodically crossed by thin mono filamentary streamers with a natural repetition frequency of some tens of kHz.The study compares the results obtained in dry air and in air mixed with a small amount of water vapour (humid air).The simulation involves the electro-dynamics,chemical kinetics and neutral gas hydrodynamics phenomena that influence the kinetics of the chemical species transformation.Each discharge lasts about one hundred of a nanosecond while the post-discharge occurring between two successive discharges lasts one hundred of a microsecond.The ACDR is crossed by a lateral dry or humid air flow initially polluted with 400 ppm of NO.After 5 ms,the time corresponding to the occurrence of 50 successive discharge/post-discharge phases,a higher NO removal rate and a lower ozone production rate are found in humid air.This change is due to the presence of the HO2 species formed from the H primary radical in the discharge zone.

  16. Optical emission spectroscopy of point-plane corona and back-corona discharges in air

    Science.gov (United States)

    Czech, T.; Sobczyk, A. T.; Jaworek, A.

    2011-12-01

    Results of spectroscopic investigations and current-voltage characteristics of corona discharge and back discharge on fly-ash layer, generated in point-plane electrode geometry in air at atmospheric pressure are presented in the paper. The characteristics of both discharges are similar but differ in the current and voltage ranges of all the discharge forms distinguished during the experiments. Three forms of back discharge, for positive and negative polarity, were investigated: glow, streamer and low-current back-arc. In order to characterize ionisation and excitation processes in back discharge, the emission spectra were measured and compared with those obtained for normal corona discharge generated in the same electrode configuration but with fly ash layer removed. The emission spectra were measured in two discharge zones: near the tip of needle electrode and near the plate. Visual forms of the discharge were recorded with digital camera and referred to current-voltage characteristics and emission spectra. The measurements have shown that spectral lines emitted by back discharge depend on the form of discharge and the discharge current. From the comparison of the spectral lines of back and normal discharges an effect of fly ash layer on the discharge morphology can be determined. The recorded emission spectra formed by ionised gas and plasma near the needle electrode and fly ash layer are different. It should be noted that in back arc emission, spectral lines of fly ash layer components can be distinguished. On the other hand, in needle zone, the emission of high intensity N2 second positive system and NO γ lines can be noticed. Regardless of these gaseous lines, also atomic lines of dust layer were present in the spectrum. The differences in spectra of back discharge for positive and negative polarities of the needle electrode have been explained by considering the kind of ions generated in the crater in fly ash layer. The aim of these studies is to better

  17. Force measurements in positive unipolar wire-to-plane corona discharges in air

    CERN Document Server

    de Haan, V O

    2004-01-01

    Measurements of force generated by a positive unipolar wire-to-plane corona discharge in air are compared with numerical simulations. The generated force does not depend on the ion or electron mobilities, preventing the influence of uncertainty and variation of these parameters. A method is described to simulate the voltage and charge distribution for a wire-to-plane set-up. This method enables the determination of the transition between unipolar and bipolar discharges. In the experimental set-up breakdown electric field of air reduces with increasing discharge current.

  18. Quasi-perpetual discharge behaviour in p-type Ge-air batteries.

    Science.gov (United States)

    Ocon, Joey D; Kim, Jin Won; Abrenica, Graniel Harne A; Lee, Jae Kwang; Lee, Jaeyoung

    2014-11-07

    Metal-air batteries continue to become attractive energy storage and conversion systems due to their high energy and power densities, safer chemistries, and economic viability. Semiconductor-air batteries - a term we first define here as metal-air batteries that use semiconductor anodes such as silicon (Si) and germanium (Ge) - have been introduced in recent years as new high-energy battery chemistries. In this paper, we describe the excellent doping-dependent discharge kinetics of p-type Ge anodes in a semiconductor-air cell employing a gelled KOH electrolyte. Owing to its Fermi level, n-type Ge is expected to have lower redox potential and better electronic conductivity, which could potentially lead to a higher operating voltage and better discharge kinetics. Nonetheless, discharge measurements demonstrated that this prediction is only valid at the low current regime and breaks down at the high current density region. The p-type Ge behaves extremely better at elevated currents, evident from the higher voltage, more power available, and larger practical energy density from a very long discharge time, possibly arising from the high overpotential for surface passivation. A primary semiconductor-air battery, powered by a flat p-type Ge as a multi-electron anode, exhibited an unprecedented full discharge capacity of 1302.5 mA h gGe(-1) (88% anode utilization efficiency), the highest among semiconductor-air cells, notably better than new metal-air cells with three-dimensional and nanostructured anodes, and at least two folds higher than commercial Zn-air and Al-air cells. We therefore suggest that this study be extended to doped-Si anodes, in order to pave the way for a deeper understanding on the discharge phenomena in alkaline metal-air conversion cells with semiconductor anodes for specific niche applications in the future.

  19. Formation of white-eye pattern with microdischarge in an air dielectric barrier discharge system

    CERN Document Server

    He, Yafeng; Liu, Weili; Wang, Hongfang; Zhao, Zengchao; Fan, Weili

    2011-01-01

    We report on the first observation of white-eye pattern in an air dielectric barrier discharge. The patterned discharges undergo a development as following: random spots - quasihexagonal pattern - hexagonal pattern (type I) - hexagonal pattern (type II) - white-eye pattern - chaos as the voltage is increased. The spatiotemporal characteristics of patterned discharges are investigated by using an optical method. Results show that the two discharge modes, uniform mode and filamentary mode, are actually two different spatial presentations of the same origin: the microdischarge. From the viewpoint of pattern dynamics, the white-eye pattern results from a 3-wave resonance interaction.

  20. Preliminary Investigation of a Dielectric Barrier Discharge Lamp in Open Air at Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    LIU Feng; WANG Wei-Wei; CHANG Xi-Jiang; LIANG Rong-Qing

    2011-01-01

    @@ A dielectric barrier discharge (DBD) lamp is investigated by using sinusoidal power with a 10 kHz frequency in open air at atmospheric pressure.With increasing applied voltages, the different discharge phenomena appear.At relatively low voltages, the discharge states are general stochastic filamentary discharges with weak light.However, at relatively high voltages, the walls of quartz tubes are heated sharply by plasma, and then the dazzling light is emitted very quickly to form the DBD Lamp, corresponding to the low maintaining voltage that is lower than the ignited voltage.The discharge state or mode of the DBD lamp that corresponds to the glow discharge is deduced according to the wave form of the circuit current, which is evidently different from the filamentary discharges.Under these conditions, the spectrum of the DBD lamp is continuous in the range 400-932nm, which is scanned in the range 300-932nm.It is also shown that there is another discharge state or mode that is different from the traditional filamentary discharges.Therefore, it is concluded that the discharge state or mode of the DBD lamp is a glow discharge.

  1. Investigation of a single barrier discharge in submillimeter air gaps. Nonuniform field

    Science.gov (United States)

    Bondarenko, P. N.; Emel'yanov, O. A.; Shemet, M. V.

    2014-08-01

    Pulse characteristics of single barrier discharges as well as parameters of charges accumulated on the surface of a dielectric under the atmospheric pressure in the "needle-(0.1-2.0)-mm air gap-polymer barrier-plane" system are investigated. It is found experimentally that for the positive polarity of the needle, the voltage for the discharge initiation is higher than in the case of the negative polarity by ˜25-35%. The reversal of the needle polarity from negative to positive increases the amplitude of the discharge current and the accumulated surface charge by ˜1.5-3 times. For the positive polarity of the needle, the discharge is governed by a streamer mechanism, while for the negative polarity, the discharge is initiated by the formation of a single Trichel pulse. The single pulse regime is observed for the discharge current up to a certain electrode gap d CR. For the positive needle and for air gap width d air > d CR ≈ 1.5 mm, a multipulse burst corona is formed, while for the negative needle and d air > d CR ≈ 0.9 mm, a damped sequence of Trichel pulses evolves in the system.

  2. Ozone production by a dc corona discharge in air contaminated by n-heptane

    Science.gov (United States)

    Pekárek, S.

    2008-01-01

    Beneficial purposes of ozone such as elimination of odours, harmful bacteria and mildew can be used for transportation of food, fruits and vegetables with the aim to extend their storage life. To date the main technique used for this purpose in the transportation of these commodities, e.g. by trucks, was cooling. Here a combination of cooling together with the supply of ozone into containers with these commodities is considered. For these purposes we studied the effect of air contamination by n-heptane (part of automotive fuels) and humidity on ozone production by a dc hollow needle to mesh corona discharge. We found that, for both polarities of the needle electrode, addition of n-heptane to air (a) decreases ozone production; (b) causes discharge poisoning to occur at lower current than for air; (c) does not substantially influence the current for which the ozone production reaches the maximum. Finally the maximum ozone production for the discharge in air occurs for the same current as the maximum ozone production for the discharge contaminated by n-heptane. We also found that humidity decreases ozone production from air contaminated by n-heptane irrespective of the polarity of the coronating needle electrode. This dependence is stronger for the discharge with the needle biased positively.

  3. Study on the Microsecond Pulse Homogeneous Dielectric Barrier Discharges in Atmospheric Air and Its Influencing Factors%Study on the Microsecond Pulse Homogeneous Dielectric Barrier Discharges in Atmospheric Air and Its Influencing Factors

    Institute of Scientific and Technical Information of China (English)

    方志; 雷枭; 蔡玲玲; 邱毓昌; Edmund KUFFEL

    2011-01-01

    The homogeneous dielectric barrier discharge (DBD) in atmospheric air between two symmetric-columnar copper electrodes with epoxy plates as the dielectric barriers is generated using a us pulse high voltage power supply. The discharge characteristics are studied by measurement of its electrical discharge parameters and observation of its light emission phenom- ena, and the main discharge parameters of the homogenous DBD, such as discharge current and average discharge power, are calculated. Results show that the discharge generated is a homogeneous one with one larger single current pulse of about 2 #s duration appearing in each voltage pulse, and its light emission is radially homogeneous and covers the entire surface of the two elec- trodes. The influences of applied voltage amplitude, air gap distance and barrier thickness on the transition of discharge modes are studied. With the increase of air gap distance, the discharge will transit from homogeneous mode to filamentary mode. The higher the thickness of dielectric barriers, the larger the air gap distance for generating the homogeneous discharge mode. The average discharge power increases non-linearly with increasing applied voltage amplitude, and decreases non-linearly with the increase of air gap distance and barrier thickness. In order to generate stable and homogeneous DBD with high discharge power, thin barriers distance should be used, and higher applied voltage amplitude should be applied to small air gap.

  4. 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.

  5. Pulsed and streamer discharges in air above breakdown electric field

    NARCIS (Netherlands)

    Sun, A.B.; Teunissen, H.J.; Ebert, U.

    2013-01-01

    A 3D particle model is developed to investigate the streamer formation in electric fields above the breakdown threshold, in atmospheric air (1bar, 300 Kelvin). Adaptive particle management, adaptive mesh refinement and parallel computing techniques are used in the code. Photoionization and electron

  6. Corona Discharges in Atmospheric Air Between a Wire and Two Plates

    OpenAIRE

    Bérard, Philippe; Lacoste, Deanna,; Laux, C.

    2011-01-01

    International audience; The corona discharge obtained in atmospheric air between a wire and two plates is presented. For the configuration studied and the voltage applied, the current is steady for the positive corona and exhibits Trichel pulses in the negative corona. The positive corona produces a homogeneous blue halo around the wire, whereas the negative discharge produces evenly spaced spots on the wire surface. We verified the analytic prediction that the ionic wind varies as the square...

  7. Investigation of Ozone Yield of Air Fed Ozonizer by High Pressure Homogeneous Dielectric Barrier Discharge

    Science.gov (United States)

    2013-07-01

    homogeneous dielectric barrier discharge ( DBD ) in dry air by using a simple DBD device. So far, we have tried to apply the homogeneous DBD to an...specific input energy region. In this work, we investigated the effect of gas pressure (from 0.1 MPa to 0.2 MPa) on the ozone yield by homogeneous DBD . The...homogeneous DBD decreased with increasing the gas pressure. 1. Introduction The dielectric barrier discharge ( DBD ) is composed of many filamentary micro

  8. Characteristics of a Normal Glow Discharge Excited by DC Voltage in Atmospheric Pressure Air

    Science.gov (United States)

    Li, Xuechen; Zhao, Huanhuan; Jia, Pengying

    2013-11-01

    Atmospheric pressure glow discharges were generated in an air gap between a needle cathode and a water anode. Through changing the ballast resistor and gas gap width between the electrodes, it has been found that the discharges are in normal glow regime judged from the current-voltage characteristics and visualization of the discharges. Results indicate that the diameter of the positive column increases with increasing discharge current or increasing gap width. Optical emission spectroscopy is used to calculate the electron temperature and vibrational temperature. Both the electron temperature and the vibrational temperature increases with increasing discharge current or increasing gap width. Spatially resolved measurements show that the maxima of electron temperature and vibrational temperature appeared in the vicinity of the needle cathode.

  9. Piezoelectric transformers for low-voltage generation of gas discharges and ionic winds in atmospheric air

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Michael J. [Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, Indianapolis 46556 (United States); Go, David B., E-mail: dgo@nd.edu [Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, Indianapolis 46556 (United States); Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indianapolis 46556 (United States)

    2015-12-28

    To generate a gas discharge (plasma) in atmospheric air requires an electric field that exceeds the breakdown threshold of ∼30 kV/cm. Because of safety, size, or cost constraints, the large applied voltages required to generate such fields are often prohibitive for portable applications. In this work, piezoelectric transformers are used to amplify a low input applied voltage (<30 V) to generate breakdown in air without the need for conventional high-voltage electrical equipment. Piezoelectric transformers (PTs) use their inherent electromechanical resonance to produce a voltage amplification, such that the surface of the piezoelectric exhibits a large surface voltage that can generate corona-like discharges on its corners or on adjacent electrodes. In the proper configuration, these discharges can be used to generate a bulk air flow called an ionic wind. In this work, PT-driven discharges are characterized by measuring the discharge current and the velocity of the induced ionic wind with ionic winds generated using input voltages as low as 7 V. The characteristics of the discharge change as the input voltage increases; this modifies the resonance of the system and subsequent required operating parameters.

  10. Role of water and discharge mode on modulating properties in an atmospheric air MHCD jet

    Science.gov (United States)

    Liu, Kun; Wang, Chenying; Lei, Juzhang; Hu, Huimin; Zheng, Peichao; He, Wei

    2016-04-01

    A portable micro hollow cathode discharge (MHCD) device was designed in this paper to generate water-air plasma jet. The results showed that MHCD jet pattern was changed from self-pulsing discharge mode to DC mode with the increasing of voltage, and the critical voltage value of discharge mode increased with the rise of gas flow. In order to study the influences of discharge mode and water content on MHCD jet, the electrical characteristics and radicals were all measured in different conditions. We found that the length of jet decreased and temperature increased with raising water-air ratio, and during self-pulsing discharge mode, •OH content was extremely low because of the low energy of electron, but level of NO was raised with gradually increasing applied voltage. In DC mode, the results showed there was least NO content, on the other hand •OH content increased with rise of voltage and water-air ratio. O existed in both discharge modes and the effect of water content on the O production was complex. Contribution to the Topical Issue "Recent Breakthroughs in Microplasma Science and Technology", edited by Kurt Becker, Jose Lopez, David Staack, Klaus-Dieter Weltmann and Wei Dong Zhu.

  11. Spatiotemporally resolved characteristics of a gliding arc discharge in a turbulent air flow at atmospheric pressure

    Science.gov (United States)

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

    2017-01-01

    A gliding arc discharge was generated in a turbulent air flow at atmospheric pressure driven by a 35 kHz alternating current (AC) electric power. The spatiotemporally resolved characteristics of the gliding arc discharge, including glow-type discharges, spark-type discharges, short-cutting events and transitions among the different types of discharges, were investigated using simultaneously optical and electrical diagnostics. The glow-type discharge shows sinusoidal-like voltage and current waveforms with a peak current of hundreds of milliamperes. The frequency of the emission intensity variation of the glow-type discharge is the same as that of the electronic power dissipated in the plasma column. The glow-type discharge can transfer into a spark discharge characterized by a sharp peak current of several amperes and a sudden increase of the brightness in the plasma column. Transitions can also be found to take place from spark-type discharges to glow-type discharges. Short-cutting events were often observed as the intermediate states formed during the spark-glow transition. Three different types of short-cutting events have been observed to generate new current paths between two plasma channel segments, and between two electrodes, as well as between the channel segment and the electrodes, respectively. The short-cut upper part of the plasma column that was found to have no current passing through can be detected several hundreds of microseconds after the short-cutting event. The voltage recovery rate, the period of AC voltage-driving signal, the flow rates and the rated input powers were found to play an important role in affecting the transitions among the different types of discharges.

  12. Experimental Study on Indoor Air Cleaning Technique of Nano-Titania Catalysis Under Plasma Discharge

    Institute of Scientific and Technical Information of China (English)

    GAO Deli; YANG Xuechang; ZHOU Fei; WU Yuhuang

    2008-01-01

    In this study, a new technique of air cleaning by plasma combined with catalyst was proposed, which consisted of electrostatic precipitation, volatile organic compounds (VOCs) decomposition and sterilization. A novel indoor air purifier based on this technique was adopted. The experimental results showed that formaldehyde decomposition by the plasma-catalyst hybrid system was more efficient than that by plasma only. Positive discharge was better than negative discharge in formaldehyde removal. Meanwhile, the outlet concentration of ozone byproduct was effectively reduced by the nano-titania catalyst.

  13. Semi-analytical modelling of positive corona discharge in air

    Science.gov (United States)

    Pontiga, Francisco; Yanallah, Khelifa; Chen, Junhong

    2013-09-01

    Semianalytical approximate solutions of the spatial distribution of electric field and electron and ion densities have been obtained by solving Poisson's equations and the continuity equations for the charged species along the Laplacian field lines. The need to iterate for the correct value of space charge on the corona electrode has been eliminated by using the corona current distribution over the grounded plane derived by Deutsch, which predicts a cos m θ law similar to Warburg's law. Based on the results of the approximated model, a parametric study of the influence of gas pressure, the corona wire radius, and the inter-electrode wire-plate separation has been carried out. Also, the approximate solutions of the electron number density has been combined with a simplified plasma chemistry model in order to compute the ozone density generated by the corona discharge in the presence of a gas flow. This work was supported by the Consejeria de Innovacion, Ciencia y Empresa (Junta de Andalucia) and by the Ministerio de Ciencia e Innovacion, Spain, within the European Regional Development Fund contracts FQM-4983 and FIS2011-25161.

  14. Post-discharge treatment of air effluents polluted by butyl-mercaptan: role of nitrate radical

    Science.gov (United States)

    Braci, L.; Ognier, S.; Liu, Y. N.; Cavadias, S.

    2011-01-01

    Dry air polluted by butyl-mercaptan was treated in a Dielectric Barrier Discharge (DBD) reactor at atmospheric pressure using air as plasmagene gas in discharge and post-discharge modes. The energy density was varied between 200 to 1300 J/L. To assess the treatment efficiency, the concentrations of buty-mercaptan, total Volatile Organic Compounds (VOCs) and SO2 were determined in the exhaust gas. Whatever the energy density was, the treatment efficiency was better in post-discharge mode. The butyl-mercaptan could be completely eliminated from 400 J/L and SO2 selectivity was always low, below 10%. Measurements of CO, CO2 and total VOCs indicated that 50 to 70% of the reaction products were condensed on the reactor wall in the form of micro-droplets, depending on the energy density. FTIR and XPS techniques were used to characterize the reaction products which were soluble in water. These analyses indicated that the reaction products contain oxygen, nitrogen and sulphur in an oxidized form. A reaction mechanism involving hydrogen abstraction from the -SH bond by the nitrate radical was proposed, pointing out the important role of nitrate radicals NO3 in the reactivity of air flowing post-discharge.

  15. 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.

  16. 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.

  17. Laser-guided energetic discharges over large air gaps by electric-field enhanced plasma filaments

    Science.gov (United States)

    Théberge, Francis; Daigle, Jean-François; Kieffer, Jean-Claude; Vidal, François; Châteauneuf , Marc

    2017-01-01

    Recent works on plasma channels produced during the propagation of ultrashort and intense laser pulses in air demonstrated the guiding of electric discharges along the laser path. However, the short plasma lifetime limits the length of the laser-guided discharge. In this paper, the conductivity and lifetime of long plasma channels produced by ultrashort laser pulses is enhanced efficiently over many orders of magnitude by the electric field of a hybrid AC-DC high-voltage source. The AC electric pulse from a Tesla coil allowed to stimulate and maintain the highly conductive channel during few milliseconds in order to guide a subsequent 500 times more energetic discharge from a 30-kV DC source. This DC discharge was laser-guided over an air gap length of two metres, which is more than two orders of magnitude longer than the expected natural discharge length. Long plasma channel induced by laser pulses and stimulated by an external high-voltage source opens the way for wireless and efficient transportation of energetic current pulses over long air gaps and potentially for guiding lightning. PMID:28053312

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

    Science.gov (United States)

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

    2012-04-01

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

  19. The inception of pulsed discharges in air: simulations in background fields above and below breakdown

    CERN Document Server

    Sun, Anbang; Ebert, Ute

    2014-01-01

    We investigate discharge inception in air, in uniform background electric fields above and below the breakdown threshold. We perform 3D particle simulations that include a natural level of background ionization in the form of positive and O$_{2}^-$ ions. When the electric field rises above the breakdown and the detachment threshold, which are similar in air, electrons can detach from O$_{2}^-$ and start ionization avalanches. These avalanches together create one large discharge, in contrast to the `double-headed' streamers found in many fluid simulations. On the other hand, in background fields below breakdown, something must enhance the field sufficiently for a streamer to form. We use a strongly ionized seed of electrons and positive ions for this, with which we observe the growth of positive streamers. Negative streamers were not observed. Below breakdown, the inclusion of electron detachment does not change the results much, and we observe similar discharge development as in fluid simulations.

  20. Non-self-sustained microwave discharge and the concept of a microwave air jet engine

    Energy Technology Data Exchange (ETDEWEB)

    Batanov, G M; Gritsinin, S I; Kossyi, I A [General Physics Institute of Russian Academy of Sciences, 119991, Vavilov Street 38, Moscow (Russian Federation)

    2002-10-21

    A new type of microwave discharge - near-surface non-self-sustained discharge (NSND) - has been realized and investigated. A physical model of this discharge is presented. For the first time NSND application for microwave air jet engines has been proposed. Measurements under laboratory conditions modelling the microwave air jet engine operation shows the qualitative agreement between the model of NSND and actual processes near the target irradiated by a powerful microwave beam. Characteristic dependences of recoil momentum of target on the background pressure and microwave pulse duration obtained in experiments are presented. Measured cost of thrust produced by the NSND is no more than 3.0 kW N{sup -1}, which is close to the predicted values.

  1. Selective poisoning of Li-air batteries for increased discharge capacity

    DEFF Research Database (Denmark)

    Mýrdal, Jón Steinar Garðarsson; Vegge, Tejs

    2014-01-01

    The main discharge product at the cathode of non-aqueous Li-air batteries is insulating Li2O2 and its poor electronic conduction is a main limiting factor in the battery performance. Here, we apply density functional theory calculations (DFT) to investigate the potential of circumventing...... accessible battery capacity at the expense of a limited increase in the overpotentials....

  2. Vortex flow formation during dielectric barrier discharge initiation in quiescent air

    NARCIS (Netherlands)

    Golub, V. V.; Saveliev, A. S.

    2010-01-01

    The structure of vortex flows generated by dielectric barrier discharge initiated in quiescent air at atmospheric pressure has been studied by the methods of particle image velocimetry and schlieren photography. The flow parameters have been measured as functions of the time past the electric discha

  3. Effect of duty-cycles on the air plasma gas-phase of dielectric barrier discharges

    Science.gov (United States)

    Barni, R.; Biganzoli, I.; Dell'Orto, E. C.; Riccardi, C.

    2015-10-01

    An experimental investigation concerning the effects of a duty-cycle in the supply of a dielectric barrier discharge in atmospheric pressure air has been performed. Electrical characteristics of the discharge have been measured, focusing mainly on the statistical properties of the current filaments and on dielectric surface charging, both affected by the frequent repetition of breakdown imposed by the duty-cycle. Information on the gas-phase composition was gathered too. In particular, a strong enhancement in the ozone formation rate is observed when suitable long pauses separate the active discharge phases. A simulation of the chemical kinetics in the gas-phase, based on a simplified discharge modeling, is briefly described in order to shed light on the observed increase in ozone production. The effect of a duty-cycle on surface modification of polymeric films in order to increase their wettability has been investigated too.

  4. An investigation of an underwater steam plasma discharge as alternative to air plasmas for water purification

    Science.gov (United States)

    Gucker, Sarah N.; Foster, John E.; Garcia, Maria C.

    2015-10-01

    An underwater steam plasma discharge, in which water itself is the ionizing media, is investigated as a means to introduce advanced oxidation species into contaminated water for the purpose of water purification. The steam discharge avoids the acidification observed with air discharges and also avoids the need for a feed gas, simplifying the system. Steam discharge operation did not result in a pH changes in the processing of water or simulated wastewater, with the actual pH remaining roughly constant during processing. Simulated wastewater has been shown to continue to decompose significantly after steam treatment, suggesting the presence of long-lived plasma produced radicals. During steam discharge operation, nitrate production is limited, and nitrite production was found to be below the detection threshold of (roughly 0.2 mg L-1). The discharge was operated over a broad range of deposited power levels, ranging from approximately 30 W to 300 W. Hydrogen peroxide production was found to scale with increasing power. Additionally, the hydrogen peroxide production efficiency of the discharge was found to be higher than many of the rates reported in the literature to date.

  5. Measurement of the impulse produced by a pulsed surface discharge actuator in air

    Science.gov (United States)

    Elias, P. Q.; Castera, P.

    2013-09-01

    The pulsed surface discharge in atmospheric pressure air generates a shock wave, thereby transferring an impulse to the surrounding gas. The aim of this work is to measure this impulse, using implementation of a plasma actuator based on linear surface discharges of length up to 10 cm, and of linear energy in a range 0.1-0.5 J cm-1. The shock wave generated by the discharge is visualized using a pulsed schlieren system and the impulse is measured with a dedicated balance. These measurements are correlated with 1D numerical simulations of pulsed energy depositions in a perfect gas. Experiments show that the discharge generates a cylindrical shock wave that travels at sonic speed after a few tens of microseconds, and produces an impulse that varies from 1 to 4 mN s m-1 and scales linearly with the linear energy density. This linearity agrees with the numerical simulations when 9.5% of the energy dissipated in the discharge is assumed to heat the gas. Overall, to produce a time-averaged force similar to the one achieved by dielectric barrier discharge (DBD) actuators, 2 to 3 times more power is required. However, surface discharge actuators do not saturate, and thus can induce time-averaged forces one or two orders of magnitude above DBD when pulsed at several hundreds of hertz.

  6. Study on the characteristic decomposition components of air-insulated switchgear cabinet under partial discharge

    Science.gov (United States)

    Gui, Yingang; Zhang, Xiaoxing; Zhang, Ying; Qiu, Yinjun; Chen, Lincong

    2016-07-01

    Air-insulated switchgear cabinet plays a critical role in entire power transmission and distribution system. Its stability directly affects the operational reliability of the power system. And the on-line gas detection method, which evaluates the insulation status of insulation equipment by detecting the decomposition components of filled air in cabinet, becomes an innovative way to ensure the running stability of air-insulated switchgear cabinet. In order to study the characteristic gas types and production regularity of decomposition components under partial discharge, three insulation defects: needle-plate, air-gap and impurity defect are proposed to simulate the insulation defects under partial discharge in air-insulated switchgear cabinet. Firstly, the generation pathways and mechanism of composition components are discussed. Then CO and NO2 are selected as the characteristic decomposition components to characterize the partial discharge due to their high concentration and chemical stability. Based on the different change regularity of CO and NO2 concentration under different insulation defect, it provides an effective way to evaluate and predict the insulation defect type and severity in the field.

  7. Remarkable impact of water on the discharge performance of a silicon-air battery.

    Science.gov (United States)

    Cohn, Gil; Macdonald, Digby D; Ein-Eli, Yair

    2011-08-22

    Here, we report on a Si-air/ionic liquid electrolyte battery whose performance improves with small amounts of water in the electrolyte. The shift of the generation zone of the SiO(2) discharge product from the air cathode surface into the bulk region of the liquid electrolyte, caused by water addition, is demonstrated through various means. Addition of 15 vol% water leads to an increase of 40% in the discharge capacity as compared to the capacity obtained using a pure ionic liquid electrolyte. If the water content increases above 20 vol%, the Si-air cell capacity dramatically decreases. The water-ionic liquid electrolyte mixture shows a maximum in the ionic conductivity with a water content of 10 vol%. In-depth studies indicate a reduced amount of discharge product at the air electrode using 15 vol% H(2)O electrolyte. The morphology of the anode surface, as well as the developed surface film in the presence of water-containing ionic liquid, is reported. This study shows that exposing a Si-air battery to a humid environment does not result in capacity losses, but rather improves cell performance.

  8. 14 CFR 34.11 - Standard for fuel venting emissions.

    Science.gov (United States)

    2010-01-01

    ... FUEL VENTING AND EXHAUST EMISSION REQUIREMENTS FOR TURBINE ENGINE POWERED AIRPLANES Engine Fuel Venting Emissions (New and In-Use Aircraft Gas Turbine Engines) § 34.11 Standard for fuel venting emissions. (a) No... discharge to the atmosphere of fuel drained from fuel nozzle manifolds after engines are shut down and...

  9. Absolute OH Number Density Measurements in Lean Fuel-Air Mixtures Excited by a Repetitively Pulsed Nanosecond Discharge

    Science.gov (United States)

    2013-01-01

    discharge filaments and near the electrode edges [9]. Instead of using absorption measurement, an atmospheric pressure flame generated by a Hencken...DuPont) is placed between each electrode and the channel wall, to reduce air gaps and prevent corona discharge outside the cell. In the present work...1 Absolute OH Number Density Measurements in Lean Fuel-Air Mixtures Excited by a Repetitively Pulsed Nanosecond Discharge Zhiyao Yin, Campbell D

  10. Effects of air transient spark discharge and helium plasma jet on water, bacteria, cells, and biomolecules.

    Science.gov (United States)

    Hensel, Karol; Kučerová, Katarína; Tarabová, Barbora; Janda, Mário; Machala, Zdenko; Sano, Kaori; Mihai, Cosmin Teodor; Ciorpac, Mitică; Gorgan, Lucian Dragos; Jijie, Roxana; Pohoata, Valentin; Topala, Ionut

    2015-06-06

    Atmospheric pressure DC-driven self-pulsing transient spark (TS) discharge operated in air and pulse-driven dielectric barrier discharge plasma jet (PJ) operated in helium in contact with water solutions were used for inducing chemical effects in water solutions, and the treatment of bacteria (Escherichia coli), mammalian cells (Vero line normal cells, HeLa line cancerous cells), deoxyribonucleic acid (dsDNA), and protein (bovine serum albumin). Two different methods of water solution supply were used in the TS: water electrode system and water spray system. The effects of both TS systems and the PJ were compared, as well as a direct exposure of the solution to the discharge with an indirect exposure to the discharge activated gas flow. The chemical analysis of water solutions was performed by using colorimetric methods of UV-VIS absorption spectrophotometry. The bactericidal effects of the discharges on bacteria were evaluated by standard microbiological plate count method. Viability, apoptosis and cell cycle were assessed in normal and cancerous cells. Viability of cells was evaluated by trypan blue exclusion test, apoptosis by Annexin V-FITC/propidium iodide assay, and cell cycle progression by propidium iodide/RNase test. The effect of the discharges on deoxyribonucleic acid and protein were evaluated by fluorescence and UV absorption spectroscopy. The results of bacterial and mammalian cell viability, apoptosis, and cell cycle clearly show that cold plasma can inactivate bacteria and selectively target cancerous cells, which is very important for possible future development of new plasma therapeutic strategies in biomedicine. The authors found that all investigated bio-effects were stronger with the air TS discharge than with the He PJ, even in indirect exposure.

  11. Review of the Lightning Shielding Against Direct Lightning Strokes Based on Laboratory Long Air Gap Discharges

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    It is one of the most effective ways to use laboratory long air gap discharges tbr investigating the fundamental process involved in the lightning strike. During the 1960s and the 1970s, the electro-geometrical method (EGM) and the rolling sphere method were developed base on the breakdown characteristics of negative long spark discharges, which have been widely used to design the lightning shielding system of transmission lines and structures. In recent years, the scale of the power facilities is increased dramatically with the rising of power grid's voltage level.

  12. 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.

  13. Study on law of negative corona discharge in microparticle-air two-phase flow media

    Directory of Open Access Journals (Sweden)

    Bo He

    2016-03-01

    Full Text Available To study the basic law of negative corona discharge in solid particle-air two-phase flow, corona discharge experiments in a needle-plate electrode system at different voltage levels and different wind speed were carried out in the wind tunnel. In this paper, the change law of average current and current waveform were analyzed, and the observed phenomena were systematically explained from the perspectives of airflow, particle charging, and particle motion with the help of PIV (particle image velocity measurements and ultraviolet observations.

  14. Atmospheric pressure air direct current glow discharge ionization source for ion mobility spectrometry.

    Science.gov (United States)

    Dong, Can; Wang, Weiguo; Li, Haiyang

    2008-05-15

    A new atmospheric pressure air direct current glow discharge (DCGD) ionization source has been developed for ion mobility spectrometry (IMS) to overcome the regularity problems associated with the conventional (63)Ni source and the instability of the negative corona discharge. Its general electrical characteristics were experimentally investigated. By equipping it to IMS, a higher sensitivity was obtained compared to that of a (63)Ni source and corona discharge, and a linear dynamic range from 20 ppb to 20 ppm was obtained for m-xylene. Primary investigations showed that alkanes, such as pentane, which are nondetectable or insensitively detectable with (63)Ni-IMS, can be efficiently detected by DCGD-IMS and the detection limit of 10 ppb can be reached. The preliminary results have shown that the new DCGD ionization source has great potential applications in IMS, such as online monitoring of environment pollutants and halogenated compounds.

  15. Analyzing x-ray emissions from meter-scale negative discharges in ambient air

    DEFF Research Database (Denmark)

    Kochkin, Pavlo; Köhn, Christoph; Ebert, Ute

    2016-01-01

    When voltage pulses of 1 MV drive meter long air discharges, short and intense bursts of x-rays are measured. Here we develop a model for electron acceleration and subsequent photon generation within this discharge to understand these bursts. We start from the observation that the encounter of two...... streamers of opposite polarity launches the electrons, that they are further accelerated in the discharge field and then lose their energy, e.g., by photon emission through Bremsstrahlung. We model electron and photon dynamics in space and energy with a Monte Carlo model. Also the detector response...... to incoming photons is modelled in detail. The model justifies the approximation that the x-ray bursts are isotropic in space; this assumption is used to conclude that x-ray bursts near the high-voltage electrode with 6x 104 photons and characteristic energies of 160 keV closely reproduce the measured spectra...

  16. The impacts of magnetic field on repetitive nanosecond pulsed dielectric barrier discharge in air

    Science.gov (United States)

    Liu, Yidi; Qi, Haicheng; Fan, Zhihui; Yan, Huijie; Ren, ChunSheng

    2016-11-01

    In this paper, the impacts of the parallel magnetic field on the repetitive nanosecond pulsed dielectric barrier discharge (DBD) are experimentally investigated by optical and electrical measurements. The DBD is generated between two parallel-plate electrodes in the ambient air with the stationary magnetic field on the order of 1 T. The experimental results show that additional microdischarge channels are generated and the photocurrent intensity of the plasma is increased by the magnetic field. The microdischarge channels develop along the magnetic field lines and the diffuse background emission of the discharge is stronger in the DBD with the magnetic field. As the pulse repetition frequency decreases from 1200 Hz to 100 Hz, only the photocurrent intensity of the third discharge that occurred at about 500 ns is noticeably increased by the additional magnetic field. It is believed that the enhancement of the memory effect and the confinement of the magnetic field on electrons are the main reasons.

  17. Nitric oxide density measurements in air and air/fuel nanosecond pulse discharges by laser induced fluorescence

    Science.gov (United States)

    Uddi, M.; Jiang, N.; Adamovich, I. V.; Lempert, W. R.

    2009-04-01

    Laser induced fluorescence is used to measure absolute nitric oxide concentrations in air, methane-air and ethylene-air non-equilibrium plasmas, as a function of time after initiation of a single pulse, 20 kV peak voltage, 25 ns pulse duration discharge. A mixture of NO and nitrogen with known composition (4.18 ppm NO) is used for calibration. Peak NO density in air at 60 Torr, after a single pulse, is ~8 × 1012 cm-3 (~4.14 ppm) occurring at ~250 µs after the pulse, with decay time of ~16.5 ms. Peak NO atom mole fraction in a methane-air mixture with equivalence ratio of phiv = 0.5 is found to be approximately equal to that in air, with approximately the same rise and decay rate. In an ethylene-air mixture (also with equivalence ratio of phiv = 0.5), the rise and decay times are comparable to air and methane-air, but the peak NO concentration is reduced by a factor of approximately 2.5. Spontaneous emission measurements show that excited electronic states N2(C 3Π) and NO(A 2Σ) in air at P = 60 Torr decay within ~20 ns and ~1 µs, respectively. Kinetic modelling calculations incorporating air plasma kinetics complemented with the GRI Mech 3.0 hydrocarbon oxidation mechanism are compared with the experimental data using three different NO production mechanisms. It is found that NO concentration rise after the discharge pulse is much faster than predicted by Zel'dovich mechanism reactions, by two orders of magnitude, but much slower compared with reactions of electronically excited nitrogen atoms and molecules, also by two orders of magnitude. It is concluded that processes involving long lifetime (~100 µs) metastable states, such as N2(X 1Σ,v) and O2(b 1Σ), formed by quenching of the metastable N2(A 3Σ) state by ground electronic state O2, may play a dominant role in NO formation. NO decay, in all cases, is found to be dominated by the reverse Zel'dovich reaction, NO + O → N + O2, as well as by conversion into NO2 in a reaction of NO with ozone.

  18. Streamer-to-spark transition initiated by a nanosecond overvoltage pulsed discharge in air

    Science.gov (United States)

    Lo, A.; Cessou, A.; Lacour, C.; Lecordier, B.; Boubert, P.; Xu, D. A.; Laux, C. O.; Vervisch, P.

    2017-04-01

    This study is focused on the streamer-to-spark transition generated by an overvoltage nanosecond pulsed discharge under atmospheric pressure air in order to provide a quantitative insight into plasma-assisted ignition. The discharge is generated in atmospheric pressure air by the application of a positive high voltage pulse of 35 kV to pin-to-pin electrodes and a rise time of 5 ns. The generated discharge consists of a streamer phase with high voltage and high current followed by a spark phase characterized by a low voltage and a decreasing current in several hundreds of nanosecond. During the streamer phase, the gas temperature measured by optical emission spectroscopy related to the second positive system of nitrogen shows an ultra-fast gas heating up to 1200 K at 15 ns after the current rise. This ultra-fast gas heating, due to the quenching of electronically excited species by oxygen molecules, is followed by a quick dissociation of molecules and then the discharge transition to a spark. At this transition, the discharge contracts toward the channel axis and evolves into a highly conducting thin column. The spark phase is characterized by a high degree of ionization of nitrogen and oxygen atoms shown by the electron number density and temperature measured from optical emission spectroscopy measurements of N+ lines. Schlieren imaging and optical emission spectroscopy techniques provide the time evolution of the spark radius, from which the initial pressure in the spark is estimated. The expansion of the plasma is adiabatic in the early phase. The electronic temperature and density during this phase allows the determination of the isentropic coefficient. The value around 1.2–1.3 is coherent with the high ionization rate of the plasma in the early phase. The results obtained in this study provide a database and the initial conditions for the validation of numerical simulations of the ignition by plasma discharge.

  19. 14 CFR 29.975 - Fuel tank vents and carburetor vapor vents.

    Science.gov (United States)

    2010-01-01

    ... end at any point— (i) Where the discharge of fuel from the vent outlet would constitute a fire hazard... with vapor elimination connections must have a vent line to lead vapors back to one of the fuel tanks... line must lead back to the fuel tank used for takeoff and landing....

  20. 14 CFR 25.975 - Fuel tank vents and carburetor vapor vents.

    Science.gov (United States)

    2010-01-01

    ... may end at any point— (i) Where the discharge of fuel from the vent outlet would constitute a fire... carburetor with vapor elimination connections must have a vent line to lead vapors back to one of the fuel... return line must lead back to the fuel tank used for takeoff and landing....

  1. Electron density fluctuations accelerate the branching of streamer discharges in air

    CERN Document Server

    Luque, A

    2011-01-01

    Branching is an essential element of streamer discharge dynamics but today it is understood only qualitatively. The variability and irregularity observed in branched streamer trees suggest that stochastic terms are relevant for the description of streamer branching. We here consider electron density fluctuations due to the discrete particle number as a source of stochasticity in positive streamers in air at standard temperature and pressure. We derive a quantitative estimate for the branching distance that agrees within a factor of 2 with experimental values. As branching without noise would occur later, if at all, we conclude that stochastic particle noise is relevant for streamer branching in air at atmospheric pressure.

  2. 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

    International audience; 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 focuse...

  3. 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.

  4. Modeling plasma glow discharges in Air near a Mach 3 bow shock with KRONOS

    Science.gov (United States)

    Rassou, Sebastien; Labaune, Julien; Packan, Denis; Elias, Paul-Quentin

    2016-09-01

    In this work, plasma glow discharge in Air is modeled near a Mach 3 bow shock. Numerical simulations are performed using the coupling KRONOS which have been developed at ONERA. The flow field is modeled using the code CFD: CEDRE from ONERA and the electrical and plasma part by the EDF open-source code CODE_SATURNE. The plasma kinetic modeling consists on a two-term Boltzmann equation solver and a chemical reaction solver depending of the electric field. The coupling KRONOS is fully parallelized and run on ONERA supercomputers. The shock wave is formed by the propagation of a supersonic flow (M = 3) through a truncated conical model mounted with a central spike. Depending on the spike's voltage value, corona, glow or arc regime could be obtained in a steady flow. The parameters for the supersonic flow and the spike configurations are chosen to be in glow discharge regime and to reproduce the experimental setup. In our simulations, 12 species and 80 reactions (ionization, electronic or vibrational excitation, attachment etc ...) are considered to properly model the glow discharge and the afterglow. In a stationary flow, glow discharge is observed only at the upstream of the shock wave near the high voltage spike. Behind the bow shock, in the afterglow, negative ions are provided by electrons attachment with O2. The negative ions flow convection ensures the electrical conduction and the establishment of the glow discharge.

  5. Numerical modeling of a glow discharge through a supersonic bow shock in air

    Science.gov (United States)

    Rassou, S.; Packan, D.; Elias, P.-Q.; Tholin, F.; Chemartin, L.; Labaune, J.

    2017-03-01

    The interaction between a glow discharge and the bow shock of a Mach 3 air flow around a truncated conical model with a central spike is modeled, and comparison is made with prior experimental results. The KRONOS workflow for plasma modeling in flow fields, which has recently been developed at ONERA, was used for the modeling. Based on the quasi-neutral approximation, it couples hypersonic and reactive flow fields with electron chemistry, including the effect of non-Maxwellian electron energy distribution function. The model used for the discharge involves 12 species and 82 reactions, including ionization, electronic and vibrational excitation, and attachment. The simulations reproduce the main features of the discharge observed experimentally well, in particular, the very recognizable topology of the discharge. It was found from the simulations that behind the bow shock, in the afterglow, the negative ion flow ensures the electrical conduction and the establishment of the glow discharge. The influence of kinetic rates on the voltage-current characteristics is discussed.

  6. Numerical modelling of the effect of dry air traces in a helium parallel plate dielectric barrier discharge

    Science.gov (United States)

    Lazarou, C.; Belmonte, T.; Chiper, A. S.; Georghiou, G. E.

    2016-10-01

    A validated numerical model developed for the study of helium barrier discharges in the presence of dry air impurities is presented in this paper. The model was used to numerically investigate the influence of air traces on the evolution of the helium dielectric barrier discharge (DBD). The level of dry air used as impurity was in the range from 0 to 1500 ppm, which corresponds to the most commonly encountered range in atmospheric pressure discharge experiments. The results presented in this study clearly show that the plasma chemistry and consequently the discharge evolution is highly affected by the concentration level of impurities in the mixture. In particular, it was observed that air traces assist the discharge ignition at low concentration levels (~55 ppm), while on the other hand, they increase the burning voltage at higher concentration levels (~1000 ppm). Furthermore, it was found that the discharge symmetry during the voltage cycle highly depends on the concentration of air. For the interpretation of the results, a detailed analysis of the processes that occur in the discharge gap is performed and the main reaction pathways of ion production are described. Thanks to this approach, useful insight into the physics behind the evolution of the discharge is obtained.

  7. Kinetics of NO formation and decay in nanosecond pulse discharges in Air, H2-Air, and C2H4-Air mixtures

    Science.gov (United States)

    Burnette, David; Shkurenkov, Ivan; Adamovich, Igor V.; Lempert, Walter R.

    2016-04-01

    Time-resolved, absolute NO and N atom number densities are measured by NO Laser Induced Fluorescence (LIF) and N Two-Photon Absorption LIF in a diffuse plasma filament, nanosecond pulse discharge in dry air, hydrogen-air, and ethylene-air mixtures at 40 Torr, over a wide range of equivalence ratios. The results are compared with kinetic modeling calculations incorporating pulsed discharge dynamics, kinetics of vibrationally and electronically excited states of nitrogen, plasma chemical reactions, and radial transport. The results show that in air afterglow, NO decay occurs primarily by the reaction with N atoms, NO  +  N  →  N2  +  O. In the presence of hydrogen, this reaction is mitigated by reaction of N atoms with OH, N  +  OH  →  NO  +  H, resulting in significant reduction of N atom number density in the afterglow, additional NO production, and considerably higher NO number densities. In fuel-lean ethylene-air mixtures, a similar trend (i.e. N atom concentration reduction and NO number density increase) is observed, although [NO] increase on ms time scale is not as pronounced as in H2-air mixtures. In near-stoichiometric and fuel-lean ethylene-air mixtures, when N atom number density was below detection limit, NO concentration was measured to be lower than in air plasma. These results suggest that NO kinetics in hydrocarbon-air plasmas is more complex compared to air and hydrogen-air plasmas, additional NO reaction pathways may well be possible, and their analysis requires further kinetic modeling calculations.

  8. Pulsed positive discharges in air at moderate pressures near a dielectric rod

    Science.gov (United States)

    Dubinova, A.; Trienekens, D.; Ebert, U.; Nijdam, S.; Christen, T.

    2016-10-01

    We study pulsed positive discharges in air in a cylindrically symmetric setup with an electrode needle close (about 1 mm) above the top of a dielectric cylindrical rod of 4 mm in diameter mounted at its bottom on a grounded plate electrode. We present ICCD (intensified charge-coupled device) pictures and evaluations of experiments as well as simulations with a fluid discharge model; the simulations use cylindrical symmetry. In the experiments, there is an initial inception cloud phase, where the cylindrical symmetry is maintained, and later a streamer phase, where it is broken spontaneously. At 75-150 mbar, discharges with cylindrical symmetry are not attracted to the dielectric rod, but move away from it. The dielectric rod plays the sole role of an obstacle that shades (in the context of photoionization) a cone-shaped part of the inception cloud; the cone size is determined by the geometry of the setup. The material properties of the dielectric rod, such as its dielectric permittivity and the efficiency of the photon induced secondary electron emission do not have a noticeable effect. This is due to the abundance of photoionization in air, which supplies a positive discharge with free electrons and allows it to propagate along the electric field lines. Using some simple field calculations, we show that field enhancement due to dielectric polarization does not play a significant role in our geometry as long as the discharge maintains its cylindrical symmetry. The field component towards the rod is insufficiently enhanced to cause the discharge to move towards the rod. Any additional electrons produced by the dielectric surface do not influence this discharge morphology. This interpretation is supported by both experiments and simulations. At higher pressures (400-600 mbar) or for larger gaps between the needle and the dielectric rod, the inception cloud reaches its maximal radius within the gap between needle and rod and destabilizes there. In those cases

  9. Study of nanosecond discharges in different H2 air mixtures at atmospheric pressure for plasma-assisted applications

    Science.gov (United States)

    Bourdon, Anne; Kobayashi, Sumire; Bonaventura, Zdenek; Tholin, Fabien; Popov, Nikolay

    2016-09-01

    This paper presents 2D simulations of nanosecond pulsed discharges between two point electrodes in different H2/air mixtures and in air at atmospheric pressure. A fluid model is coupled with detailed kinetic schemes for air and different H2/air mixtures to simulate the discharge dynamics. First, as the positive and negative ionization waves propagate in the interelectrode gap, it has been observed that in H2/air mixtures with equivalence ratios between 0.3 and 2, major positive ions produced by the nanosecond discharge are N2+,O2+and HN2+.The discharge dynamics is shown to vary only slightly for equivalence ratios of the H2/air mixture between 0.3 and 2. Then, as the discharge transits to a nanosecond spark discharge, we have studied the different chemical reactions that lead to fast gas heating and to the production of radicals, as O,H and OH. Both thermal and chemical effects of the nanosecond spark discharge are of interest for plasma assisted combustion applications. This work has been supported by the project DRACO (Grant No. ANR-13-IS09-0004) and the french russian LIA Kappa.

  10. Effect of air flow on the micro-discharge dynamics in an array of integrated coaxial microhollow dielectric barrier discharges

    Science.gov (United States)

    Nayak, Gaurav; Du, Yanjun; Brandenburg, Ronny; Bruggeman, Peter J.

    2017-03-01

    The micro-discharge properties and evolution in a 2D array of integrated coaxial microhollow dielectric barrier discharges are studied by using highly time-resolved electrical and optical diagnostics. The study is focused on the effect of the gas flow rate and gas residence time on discharge properties. The investigated integrated coaxial microhollow discharge geometry allows operating the discharge at exceptionally small residence times, which can be equal to or even smaller than the discharge period, at reasonable gas flow rates. The gas flow has an impact on gas heating, residual humidity, pre-ionization density and the densities of excited and reactive species produced by previous discharges. A unique voltage–charge plot is obtained with elongated periods without discharge activity. A very significant effect of flow on NO emission is observed that relates to the impact of flow on the NO production in these micro-discharges. Using the emission intensities of molecular bands of the second positive system of nitrogen and the first negative system of the nitrogen ion, effective reduced electric field strengths are obtained with a maximum equal to 870 Td. The reduced electric field decreases with increasing gas flow rate. This behavior is consistent with the reduction of the overall discharge intensity due to a reduced amount of charges present in the discharge gap. Both the flow rate and a reduction in water impurity changing the ion mobility can be responsible for the different effective electric field distributions at the highest and no flow conditions.

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

    Science.gov (United States)

    Pai, David Z.; Lacoste, Deanna A.; Laux, Christophe O.

    2010-12-01

    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. 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 determine...

  13. 致电伸缩材料驱动智能气囊排气装置特征%Characteristic of Intelligent Air Bag Venting Structure Actuating by Electrostrictive Stack Actuator

    Institute of Scientific and Technical Information of China (English)

    戈嗣诚

    2002-01-01

    本文利用层叠电致伸缩驱动器设计了智能气囊排气装置,分析了其动态响应特性与缓冲驱动特性,并结合应用的需要进行了控制特性仿真.研究结果表明,该排气装置具有良好的驱动性能,可以满足智能气囊的排气控制要求.%In this paper the conception of smart materials and structures is firstly combined with research of air bag,and the main theory of self-adapting cushioning of intelligent air bag is expatiated.The intelligent venting structure is the main part affecting the cushioning result.Electrostrictive material was found having big force,high response speed and wide linearity,and it is fit to utilize in intelligent venting structure. The characteristic of the dynamic response and cushioning actuating of an electrostrictive stack actuator is analyzed,and the result of the computer simulation of the fuzzy control to intelligent venting structure is given.It is concluded that intelligent venting structure has good actuating characteristic and can satisfy the need of intelligent air bag.

  14. Size reduction of ammonia scrubbers for pig and poultry houses: Use of conditional bypass vent at high air loading rates

    NARCIS (Netherlands)

    Melse, R.W.; Wagenberg, van A.V.; Mosquera, J.

    2006-01-01

    In The Netherlands, both acid and biological air scrubbers are used for removal of ammonia from exhaust air at pig and poultry houses. Current regulations require that scrubbers are dimensioned for treating the maximum airflow rate that may occur, so on average these systems are overdimensioned and

  15. Flow Alteration and Chemical Reduction: Air Stripping to Lessen Subsurface Discharges of Mercury to Surface Water

    Science.gov (United States)

    Brooks, S. C.; Bogle, M.; Liang, L.; Miller, C. L.; Peterson, M.; Southworth, G. R.; Spalding, B. P.

    2009-12-01

    process water. Greater than 90% of the mercury in that discharge was converted to the highly volatile dissolved Hg(0) by dechlorinating the streamflow with ascorbic acid and then treating it with a near stoichiometric concentration of the chemical reductant stannous chloride. Preliminary engineering evaluations indicate that once converted to Hg(0), mercury in the stream discharge could be removed by in-situ air stripping at the discharge point or perhaps within the enclosed stormdrain network upstream. If chemical reduction:air stripping was eventualy able to remove 80% or more of Hg from water, input to the stream from that source could be lowered from 6 - 8 g/d to 1 - 2 g/d. Together, these two strategies have the potential to eliminate much of the remaining dissolved Hg input to the creek.

  16. Two-Dimensional Electron Density Measurement of Positive Streamer Discharge in Atmospheric-Pressure Air

    Science.gov (United States)

    Inada, Yuki; Ono, Ryo; Kumada, Akiko; Hidaka, Kunihiko; Maeyama, Mitsuaki

    2016-09-01

    The electron density of streamer discharges propagating in atmospheric-pressure air is crucially important for systematic understanding of the production mechanisms of reactive species utilized in wide ranging applications such as medical treatment, plasma-assisted ignition and combustion, ozone production and environmental pollutant processing. However, electron density measurement during the propagation of the atmospheric-pressure streamers is extremely difficult by using the conventional localized type measurement systems due to the streamer initiation jitters and the irreproducibility in the discharge paths. In order to overcome the difficulties, single-shot two-dimensional electron density measurement was conducted by using a Shack-Hartmann type laser wavefront sensor. The Shack-Hartmann sensor with a temporal resolution of 2 ns was applied to pulsed positive streamer discharges generated in an air gap between pin-to-plate electrodes. The electron density a few ns after the streamer initiation was 7*1021m-3 and uniformly distributed along the streamer channel. The electron density and its distribution profile were compared with a previous study simulating similar streamers, demonstrating good agreement. This work was supported in part by JKA and its promotion funds from KEIRIN RACE. The authors like to thank Mr. Kazuaki Ogura and Mr. Kaiho Aono of The University of Tokyo for their support during this work.

  17. Experimental study of the spatio-temporal development of meter-scale negative discharge in air

    CERN Document Server

    Kochkin, P O; Ebert, U

    2013-01-01

    We study the development of a negative discharge driven by a Marx generator of about 1 MV in an air gap of 1 up to 1.5 meter, at standard temperature and pressure. We show the evolution of the discharge with nanosecond-fast photography together with the electrical characteristics. The negative discharge develops through four well-distinguished streamer bursts. The streamers have different velocities and life times in different bursts. The last burst triggers a positive inception cloud on the positive grounded electrode and a burst of positive counter-streamers emerges. The pre-discharge then bridges the gap and leaders grow from both electrodes. Finally a spark is formed. Looking closer into the pre-ionized zone near the cathode, we find isolated dots which are potential branching points. These dots act as starting points for positive streamers that move towards the high-voltage electrode. We also find such phenomena as space leaders and leader stepping in our laboratory sparks.

  18. 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.

  19. 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.

  20. Modelling of the negative discharge in long air gaps under impulse voltages

    Energy Technology Data Exchange (ETDEWEB)

    Rakotonandrasana, J H; Beroual, A [Ecole Centrale de Lyon, Laboratoire AMPERE UMR CNRS 5005, 69134 Ecully Cedex (France); Fofana, I [Universite of Quebec at Chicoutimi, 555, Boulevard de l' Universite, G7H 2B1, Chicoutimi, QC (Canada)

    2008-05-21

    This paper presents a self-consistent model enabling the description of the whole negative discharge sequence, initiated in long air gaps under impulse voltage waves. This sequence includes the different phases of the propagation such as the initiation of the first corona, the pilot leader, the electrode and space leaders, and their junction. The model consists of using a RLC equivalent electrical network, the parameters of which vary with time according to the discharge characteristics and geometry (R, L and C being, respectively, the resistance, the inductance and the capacitance). This model provides the spatial and temporal evolution of the entire discharge, the current and the corresponding electrical charge, the power and energy injected into the gap and the velocity. It also allows us to simulate an image converter working in streak or frame mode and the leader propagation velocities as well as the trajectory of the discharge obtained from a probabilistic distribution. The computed results are compared with experimental data. Good agreement between computed and experimental results was obtained for various test configurations.

  1. Streptococci biofilm decontamination on teeth by low-temperature air plasma of dc corona discharges

    Science.gov (United States)

    Kovalóvá, Z.; Zahoran, M.; Zahoranová, A.; Machala, Z.

    2014-06-01

    Non-thermal plasmas of atmospheric pressure air direct current corona discharges were investigated for potential applications in dental medicine. The objective of this ex vivo study was to apply cold plasmas for the decontamination of Streptococci biofilm grown on extracted human teeth, and to estimate their antimicrobial efficiency and the plasma's impact on the enamel and dentine of the treated tooth surfaces. The results show that both positive streamer and negative Trichel pulse coronas can reduce bacterial population in the biofilm by up to 3 logs in a 10 min exposure time. This bactericidal effect can be reached faster (within 5 min) by electrostatic spraying of water through the discharge onto the treated tooth surface. Examination of the tooth surface after plasma exposure by infrared spectroscopy and scanning electron microscopy did not show any significant alteration in the tooth material composition or the tooth surface structures.

  2. The inception of pulsed discharges in air: simulations in background fields above and below breakdown

    Science.gov (United States)

    Sun, Anbang; Teunissen, Jannis; Ebert, Ute

    2014-11-01

    We investigate discharge inception in air, in uniform background electric fields above and below the breakdown threshold. We perform 3D particle simulations that include a natural level of background ionization in the form of positive and \\text{O}2- ions. In background fields below breakdown, we use a strongly ionized seed of electrons and positive ions to enhance the field locally. In the region of enhanced field, we observe the growth of positive streamers, as in previous simulations with 2D plasma fluid models. The inclusion of background ionization has little effect in this case. When the background field is above the breakdown threshold, the situation is very different. Electrons can then detach from \\text{O}2- and start ionization avalanches in the whole volume. These avalanches together create one extended discharge, in contrast to the ‘double-headed’ streamers found in many fluid simulations.

  3. Dimensional analysis of detrimental ozone generation by positive wire-to-plate corona discharge in air

    Science.gov (United States)

    Bo, Z.; Chen, J. H.

    2010-02-01

    The dimensional analysis technique is used to formulate a correlation between ozone generation rate and various parameters that are important in the design and operation of positive wire-to-plate corona discharges in indoor air. The dimensionless relation is determined by linear regression analysis based on the results from 36 laboratory-scale experiments. The derived equation is validated by experimental data and a numerical model published in the literature. Applications of such derived equation are illustrated through an example selection of the appropriate set of operating conditions in the design/operation of a photocopier to follow the federal regulations of ozone emission. Finally, a new current-voltage characteristic equation is proposed for positive wire-to-plate corona discharges based on the derived dimensionless equation.

  4. Laser-induced fluorescence from N2(+) ions generated by a corona discharge in ambient air.

    Science.gov (United States)

    Konthasinghe, Kumarasiri; Fitzmorris, Kristin; Peiris, Manoj; Hopkins, Adam J; Petrak, Benjamin; Killinger, Dennis K; Muller, Andreas

    2015-09-01

    In this work, we present the measurement of laser-induced fluorescence from N2(+) ions via the B(2)Σu(+)-X(2)Σg(+) band system in the near-ultraviolet. The ions were generated continuously by a plasma glow discharge in low pressure N2 and by a corona discharge in ambient air. The fluorescence decay time was found to rapidly decrease with increasing pressure leading to an extrapolated decay rate of ≍10(10) s(-1) at atmospheric pressure. In spite of this quenching, we were able to observe laser induced fluorescence in ambient air by means of a time-gated spectral measurement. In the process of comparing the emission signal with that of N2 spontaneous Raman scattering, ion concentrations in ambient air of order 10(8-)10(10) cm(-3) were determined. With moderate increases in laser power and collection efficiency, ion concentrations of less than 10(6) cm(-3) may be measurable, potentially enabling applications in atmospheric standoff detection of ionizing radiation from hazardous radioactive sources.

  5. 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.

  6. Genetic effects of an air discharge plasma on Staphylococcus aureus at the gene transcription level

    Science.gov (United States)

    Xu, Zimu; Wei, Jun; Shen, Jie; Liu, Yuan; Ma, Ronghua; Zhang, Zelong; Qian, Shulou; Ma, Jie; Lan, Yan; Zhang, Hao; Zhao, Ying; Xia, Weidong; Sun, Qiang; Cheng, Cheng; Chu, Paul K.

    2015-05-01

    The dynamics of gene expression regulation (at transcription level) in Staphylococcus aureus after different doses of atmospheric-pressure room-temperature air plasma treatments are investigated by monitoring the quantitative real-time polymerase chain reaction. The plasma treatment influences the transcription of genes which are associated with several important bio-molecular processes related to the environmental stress resistance of the bacteria, including oxidative stress response, biofilm formation, antibiotics resistance, and DNA damage protection/repair. The reactive species generated by the plasma discharge in the gas phase and/or induced in the liquid phase may account for these gene expression changes.

  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

    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. Determination of Xenon in Air by a Pulse-discharge Helium Ionization Detector

    Institute of Scientific and Technical Information of China (English)

    CHEN Zhan-ying; CHANG Yin-zhong; LIU Shu-jiang; ZHANG Hai-tao; WANG Shi-lian; LI Qi

    2012-01-01

    A pulse-discharge helium ionization detector(Valco,PD-D3-I) was used to measure xenon concentration in air.The dependences of the detector relative response on various gas chromatograph parameters were investigated.Based on the well prepared gas connections for the detector system and optimized gas ehromatography(GC) working conditions,the atmospheric xenon concentration could be measured by the cheap GC method with a detection level of 0.7×10-9(parts by volume).Moreover,the xenon concentration in the ground level air around our laboratory was measured with the result of 0.085 × 10-6(parts by volume) and RSD of 0.91%.

  9. Stress response of Escherichia coli induced by surface streamer discharge in humid air

    Science.gov (United States)

    Doležalová, Eva; Prukner, Václav; Lukeš, Petr; Šimek, Milan

    2016-02-01

    Inactivation of Escherichia coli by means of surface streamer discharge has been investigated to obtain new insights into the key mechanisms involved, with a particular emphasis placed on the microbial response to plasma-induced stress. The surface streamer discharge was produced in coplanar dielectric barrier discharge electrode geometry, and was driven by an amplitude-modulated ac high voltage in humid synthetic air at atmospheric pressure. The response to plasma-induced stress was evaluated by using conventional cultivation, sublethal injury and resazurin assay and the LIVE/DEAD® BacLight™ Bacterial Viability kit. Compared to conventional cultivation, the LIVE/DEAD® test labels bacteria with damaged membranes, while resazurin assay tracks their metabolic activity. Our results clearly demonstrate that the treated bacteria partly lost their ability to grow properly, i.e. they became injured and culturable, or even viable but nonculturable (VBNC). The ability to develop colonies could have been lost due to damage of the bacterial membrane. Damage of the membranes was mainly caused by the lipid peroxidation, evidencing the key role of oxygen reactive species, in particular ozone. We conclude that the conventional cultivation method overestimates the decontamination efficiency of various plasma sources, and must therefore be complemented by alternative techniques capable of resolving viable but nonculturable bacteria.

  10. Plasma decay in the afterglow of a high-voltage nanosecond discharge in air

    Science.gov (United States)

    Aleksandrov, N. L.; Anokhin, E. M.; Kindysheva, S. V.; Kirpichnikov, A. A.; Kosarev, I. N.; Nudnova, M. M.; Starikovskaya, S. M.; Starikovskii, A. Yu.

    2012-02-01

    The decay of air plasma produced by a high-voltage nanosecond discharge at room temperature and gas pressures in the range of 1-10 Torr was studied experimentally and theoretically. The time dependence of the electron density was measured with a microwave interferometer. The initial electron density was about 1012 cm-3. The discharge homogeneity was monitored using optical methods. The dynamics of the charged particle densities in the discharge afterglow was simulated by numerically solving the balance equations for electron and ions and the equation for the electron temperature. It was shown that, under these experimental conditions, plasma electrons are mainly lost due to dissociative and three-body recombination with ions. Agreement between the measured and calculated electron densities was achieved only when the rate constant of the three-body electron-ion recombination was increased by one order of magnitude and the temperature dependence of this rate constant was modified. This indicates that the mechanism for three-body recombination of molecular ions differs from that of the well-studied mechanism of atomic ion recombination.

  11. Plasma decay in air and O2 after a high-voltage nanosecond discharge

    Science.gov (United States)

    Aleksandrov, N. L.; Anokhin, E. M.; Kindysheva, S. V.; Kirpichnikov, A. A.; Kosarev, I. N.; Nudnova, M. M.; Starikovskaia, S. M.; Starikovskii, A. Yu

    2012-06-01

    This paper presents the results of experimental and theoretical studies of an afterglow in room temperature air and O2 excited by a high-voltage nanosecond discharge for pressures between 1 and 10 Torr. We measured time-resolved electron density by a microwave interferometer for initial electron densities in the range (2-3) × 1012 cm-3. Discharge uniformity was investigated by optical methods. The balance equations for charged particles and electron temperature were numerically solved to describe the temporal evolution of the densities of electrons and ions in the discharge afterglow. It was shown that the loss of electrons is governed by dissociative and three-body electron recombination with O_2^+ ions under the conditions considered. Good agreement between the calculated and measured electron density histories could be obtained only when the rate of three-body recombination was increased by an order of magnitude and when the dependence of the recombination rate on electron temperature was changed. This could testify that the well-understood mechanism of three-body electron recombination with atomic ions could be noticeably modified in the case of molecular ions.

  12. Plasma decay in the afterglow of a high-voltage nanosecond discharge in air

    Energy Technology Data Exchange (ETDEWEB)

    Aleksandrov, N. L.; Anokhin, E. M.; Kindysheva, S. V.; Kirpichnikov, A. A.; Kosarev, I. N.; Nudnova, M. M. [Moscow Institute of Physics and Technology (Russian Federation); Starikovskaya, S. M. [Ecole Polytechnique, route de Saclay (France); Starikovskii, A. Yu. [Princeton University (United States)

    2012-02-15

    The decay of air plasma produced by a high-voltage nanosecond discharge at room temperature and gas pressures in the range of 1-10 Torr was studied experimentally and theoretically. The time dependence of the electron density was measured with a microwave interferometer. The initial electron density was about 10{sup 12} cm{sup -3}. The discharge homogeneity was monitored using optical methods. The dynamics of the charged particle densities in the discharge afterglow was simulated by numerically solving the balance equations for electron and ions and the equation for the electron temperature. It was shown that, under these experimental conditions, plasma electrons are mainly lost due to dissociative and three-body recombination with ions. Agreement between the measured and calculated electron densities was achieved only when the rate constant of the three-body electron-ion recombination was increased by one order of magnitude and the temperature dependence of this rate constant was modified. This indicates that the mechanism for three-body recombination of molecular ions differs from that of the well-studied mechanism of atomic ion recombination.

  13. Plasma decay in air excited by high-voltage nanosecond discharge

    Science.gov (United States)

    Aleksandrov, Nikolay; Anokhin, Eugeny; Kindusheva, Svetlana; Kirpichnikov, Artem; Kosarev, Ilya; Nudnova, Maryia; Starikovskaia, Svetlana; Starikovskiy, Andrey; mipt Team

    2011-10-01

    Plasma decay in air after a high-voltage nanosecond discharge has been studied experimentally and numerically at room temperature for pressures between 1 and 10 Torr. Time-resolved electron density was measured by a microwave interferometer for initial electron densities in the range (2-3) × 1012 cm-3. Discharge non-uniformity was investigated by optical methods. The balance equations for charged particles and electron temperature were numerically solved to describe the temporal evolution of the densities of electrons and ions in the discharge afterglow. It was shown that the loss of electrons is governed by dissociative and three-body recombination with O2+ions under the conditions considered. Good agreement between the calculated and measured electron density histories could be obtained only when increasing the rate of three-body recombination by an order of magnitude and when changing the dependence of the recombination rate on electron temperature. This could testify that the well-known mechanism of three-body recombination of atomic ions changes in the case of molecular ions.

  14. Potential Industrial Applications of the One Atmosphere Uniform Glow Discharge Plasma (OAUGDP) Operating in Ambient Air

    Science.gov (United States)

    Reece Roth, J.

    2004-11-01

    The majority of industrial plasma processing with glow discharges has been conducted at pressures below 10 torr. This tends to limit applications to high value workpieces as a result of the high capital cost of vacuum systems and the production constraints of batch processing. It has long been recognized that glow discharge plasmas would play a much larger industrial role if they could be generated at one atmosphere. The One Atmosphere Uniform Glow Discharge Plasma (OAUGDP), developed at the University of Tennessee's Plasma Sciences Laboratory, is a non-thermal RF plasma operating on displacement currents with the time-resolved characteristics of a classical low pressure DC normal glow discharge. As a glow discharge, the OAUGDP operates with maximum electrical efficiency at the Stoletow point, where the energy input per ion-electron pair is a minimum [1, 2]. Several interdisciplinary teams have investigated potential applications of the OAUGDP. These teams included collaborators from the UTK Textiles and Nonwovens Development Center (TANDEC), and the Departments of Electrical and Computer Engineering, Microbiology, and Food Science and Technology, as well as the NASA Langley Research Center. The potential applications of the OAUGDP have all been at one atmosphere and room temperature, using air as the working gas. These applications include sterilizing medical and dental equipment; sterilizable air filters to deal with the "sick building syndrome"; removal of soot from Diesel engine exhaust; subsonic plasma aerodynamic effects, including flow re-attachment to airfoils and boundary layer modification; electrohydrodynamic (EDH) flow control of working gases; increasing the surface energy of materials; improving the adhesion of paints and electroplated layers: improving the wettability and wickability of fabrics; stripping of photoresist; and plasma deposition and directional etching of potential microelectronic relevance. [1] J. R. Roth, Industrial Plasma Engineering

  15. Field demonstration and commercialization of silent discharge plasma hazardous air pollutant control technology

    Energy Technology Data Exchange (ETDEWEB)

    Rosocha, L.A.; Coogan, J.J.; Korzekwa, R.A.; Secker, D.A. [Los Alamos National Lab., NM (United States); Reimers, R.F.; Herrmann, P.G.; Chase, P.J.; Gross, M.P. [High Mesa Technologies LLC, Santa Fe, NM (United States)]|[High Mesa Technologies LLC, Irvine, CA (United States); Jones, M.R. [Electric Power Research Inst., Palo Alto, CA (United States)

    1996-07-01

    Silent electrical discharge plasma (dielectric barrier) reactors can decompose gas-phase pollutants by free-radical attack or electron-induced fragmentation. The radicals or electrons are produced by the large average volume nonthermal plasmas generated in the reactor. In the past decade, the barrier configuration has attracted attention for destroying toxic chemical agents for the military, removing harmful greenhouse gases, and treating other environmentally- hazardous chemical compounds. At the Los Alamos National Laboratory, we have been studying the silent discharge plasma (SDP) for processing gaseous-based hazardous chemicals for approximately five years. The key objective is to convert hazardous or toxic chemicals into non-hazardous compounds or into materials which are more easily managed. The main applications have been for treating off-gases from thermal treatment units, and for abating hazardous air-pollutant emissions (e.g., industrial air emissions, vapors extracted from contaminated soil or groundwater). In this paper, we will summarize the basic principles of SDP processing, discuss illustrative applications of the technology, and present results from small-scale field tests that are relevant to our commercialization effort.

  16. Flame generation and maintenance by non-stationary discharge in mixture of air and natural gas

    Science.gov (United States)

    Medeiros, Henrique De Souza; Sagas, Julio; Lacava, Pedro

    2013-09-01

    Plasma assisted combustion is a promising research field, where the high generation of reactive species by non-equilibrium plasmas is used to modify the combustion kinetics in order to improve the process either by increasing the production of specific species (like molecular hydrogen) or by decreasing pollutant emission. One typical issue observed in plasma assisted combustion is the increase of inflammability limits, i.e the observation of combustion and flame in situation where it is not observed in conventional combustion. To study the effect of a non-stationary discharge in flame generation and maintenance in a mixture for air and natural gas, the air mass flow rate was fixed in 0.80 g/s and the natural gas flow rate was varied between 0.02 and 0.14 g/s, resulting in a variation of equivalence ratio from 0.4 to 3.0. It is observed a dependence of inflammability limits with the applied power. The analysis by mass spectrometry indicates that the increase of inflammability limits with plasma is due not only applied power, but also to hydrogen production in the discharge. Visual analysis together with high speed camera measurements show a modification in spatial distribution of the flame, probably due to modifications both in flow velocity and flame velocity. Supported by FAPESP PRONEX project grant 11/50773-0.

  17. Aqueous reactive species induced by a surface air discharge: Heterogeneous mass transfer and liquid chemistry pathways

    Science.gov (United States)

    Liu, D. X.; Liu, Z. C.; Chen, C.; Yang, A. J.; Li, D.; Rong, M. Z.; Chen, H. L.; Kong, M. G.

    2016-01-01

    Plasma-liquid interaction is a critical area of plasma science and a knowledge bottleneck for many promising applications. In this paper, the interaction between a surface air discharge and its downstream sample of deionized water is studied with a system-level computational model, which has previously reached good agreement with experimental results. Our computational results reveal that the plasma-induced aqueous species are mainly H+, nitrate, nitrite, H2O2 and O3. In addition, various short-lived aqueous species are also induced, regardless whether they are generated in the gas phase first. The production/loss pathways for aqueous species are quantified for an air gap width ranging from 0.1 to 2 cm, of which heterogeneous mass transfer and liquid chemistry are found to play a dominant role. The short-lived reactive oxygen species (ROS) and reactive nitrogen species (RNS) are strongly coupled in liquid-phase reactions: NO3 is an important precursor for short-lived ROS, and in turn OH, O2− and HO2 play a crucial role for the production of short-lived RNS. Also, heterogeneous mass transfer depends strongly on the air gap width, resulting in two distinct scenarios separated by a critical air gap of 0.5 cm. The liquid chemistry is significantly different in these two scenarios. PMID:27033381

  18. Aqueous reactive species induced by a surface air discharge: Heterogeneous mass transfer and liquid chemistry pathways.

    Science.gov (United States)

    Liu, D X; Liu, Z C; Chen, C; Yang, A J; Li, D; Rong, M Z; Chen, H L; Kong, M G

    2016-04-01

    Plasma-liquid interaction is a critical area of plasma science and a knowledge bottleneck for many promising applications. In this paper, the interaction between a surface air discharge and its downstream sample of deionized water is studied with a system-level computational model, which has previously reached good agreement with experimental results. Our computational results reveal that the plasma-induced aqueous species are mainly H(+), nitrate, nitrite, H2O2 and O3. In addition, various short-lived aqueous species are also induced, regardless whether they are generated in the gas phase first. The production/loss pathways for aqueous species are quantified for an air gap width ranging from 0.1 to 2 cm, of which heterogeneous mass transfer and liquid chemistry are found to play a dominant role. The short-lived reactive oxygen species (ROS) and reactive nitrogen species (RNS) are strongly coupled in liquid-phase reactions: NO3 is an important precursor for short-lived ROS, and in turn OH, O2(-) and HO2 play a crucial role for the production of short-lived RNS. Also, heterogeneous mass transfer depends strongly on the air gap width, resulting in two distinct scenarios separated by a critical air gap of 0.5 cm. The liquid chemistry is significantly different in these two scenarios.

  19. Singlet delta oxygen production in a 2D micro-discharge array in air: effect of gas residence time and discharge power

    Science.gov (United States)

    Nayak, Gaurav; Santos Sousa, João; Bruggeman, Peter J.

    2017-03-01

    The production of singlet delta oxygen (O2(a 1Δg)) is of growing interest for many applications. We report on the measurement of O2(a 1Δg) and ozone (O3) in a room temperature atmospheric pressure discharge in dry air. The plasma source is a 2D array of micro-discharges generated by an alternating current voltage at 20 kHz. The study focuses on the effect of gas flow through the discharge. The maximum investigated flow rate allows reducing the gas residence time in the discharge zone to half the discharge period. Results indicate that the residence time and discharge power have a major effect on the O2(a 1Δg) production. Different O2(a 1Δg) density dependencies on power are observed for different flow rates. Effects of collisional quenching on the as-produced and measured O2(a 1Δg) densities are discussed. The flow rate also allows for control of the O2(a 1Δg) to O3 density ratio in the effluent from 0.7 to conditions of pure O3.

  20. 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.

  1. 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.

  2. Ozone correlates with antibacterial effects from indirect air dielectric barrier discharge treatment of water

    Science.gov (United States)

    Pavlovich, Matthew J.; Chang, Hung-Wen; Sakiyama, Yukinori; Clark, Douglas S.; Graves, David B.

    2013-04-01

    Ambient-condition air plasma produced by indirect dielectric barrier discharges can rapidly disinfect aqueous solutions contaminated with bacteria and other microorganisms. In this study, we measured key chemical species in plasma-treated aqueous solutions and the associated antimicrobial effect for varying discharge power densities, exposure times, and buffer components in the aqueous medium. The aqueous chemistry corresponded to air plasma chemistry, and we observed a transition in composition from ozone mode to nitrogen oxides mode as the discharge power density increased. The inactivation of E. coli correlates well with the aqueous-phase ozone concentration, suggesting that ozone is the dominant species for bacterial inactivation under these conditions. Published values of ozone-water antibacterial inactivation kinetics as a function of the product of ozone concentration and contact time are consistent with our results. In contrast to earlier studies of plasma-treated water disinfection, ozone-dependent bacterial inactivation does not require acidification of the aqueous medium and the bacterial inactivation rates are far higher. Furthermore, we show that the antimicrobial effect depends strongly on gas-liquid mixing following plasma treatment, apparently because of the low solubility of ozone and the slow rate of mass transfer from the gas phase to the liquid. Without thorough mixing of the ozone-containing gas and bacteria-laden water, the antimicrobial effect will not be observed. However, it should be recognized that the complexity of atmospheric pressure plasma devices, and their sensitivity to subtle differences in design and operation, can lead to different results with different mechanisms.

  3. Bronchiolitis - discharge

    Science.gov (United States)

    RSV bronchiolitis - discharge; Respiratory syncytial virus bronchiolitis - discharge ... Your child has bronchiolitis , which causes swelling and mucus to build up in the smallest air passages of the lungs. In the hospital, ...

  4. The glow discharge inception and post-discharge relaxation of charged and neutral active particles in synthetic air at low pressure

    Science.gov (United States)

    Jovanović, A. P.; Marković, V. Lj; Stamenković, S. N.; Stankov, M. N.

    2015-11-01

    The study of dc glow discharge inception and post-discharge relaxation of charged and neutral active particles in synthetic air at low pressure is presented. The breakdown time delay dependence as a function of relaxation time \\overline{{{t}\\text{d}}}(τ ) (the memory curve) is measured and modelled from milliseconds to the saturation region determined by the cosmic rays and natural radioactivity level. Due to fast conversion \\text{N}2++{{\\text{O}}2}\\to {{\\text{N}}2}+\\text{O}2+ , relaxation of dc discharge in synthetic air in the time interval from one to about ninety milliseconds is dominated by the diffusion decay of molecular oxygen {{O}}_2^ + ions. The change of regimes, from ambipolar to the free diffusion limit, is investigated and the variation of effective diffusion coefficients is determined. The late relaxation is explained by the kinetics of nitrogen atoms, recombining on the surfaces of gas discharge tube and stainless steel electrodes and relevant surface recombination coefficients are determined.

  5. Surface-dependent inactivation of model microorganisms with shielded sliding plasma discharges and applied air flow.

    Science.gov (United States)

    Edelblute, Chelsea M; Malik, Muhammad A; Heller, Loree C

    2015-06-01

    Cold atmospheric plasma inactivates bacteria through reactive species produced from the applied gas. The use of cold plasma clinically has gained recent interest, as the need for alternative or supplementary strategies are necessary for preventing multi-drug resistant infections. The purpose of this study was to evaluate the antibacterial efficacy of a novel shielded sliding discharge based cold plasma reactor operated by nanosecond voltage pulses in atmospheric air on both biotic and inanimate surfaces. Bacterial inactivation was determined by direct quantification of colony forming units. The plasma activated air (afterglow) was bactericidal against Escherichia coli and Staphylococcus epidermidis seeded on culture media, laminate, and linoleum vinyl. In general, E. coli was more susceptible to plasma exposure. A bacterial reduction was observed with the application of air alone on a laminate surface. Whole-cell real-time PCR revealed a decrease in the presence of E. coli genomic DNA on exposed samples. These findings suggest that plasma-induced bacterial inactivation is surface-dependent.

  6. Abatement and degradation pathways of toluene in indoor air by positive corona discharge.

    Science.gov (United States)

    Van Durme, J; Dewulf, J; Sysmans, W; Leys, C; Van Langenhove, H

    2007-08-01

    Indoor air concentrations of volatile organic compounds often exceed outdoor levels by a factor of 5. There is much interest in developing new technologies in order to improve indoor air quality. In this work non-thermal plasma (DC positive corona discharge) is explored as an innovative technology for indoor air purification. An inlet gas stream of 10 l min(-1) containing 0.50+/-0.02 ppm toluene was treated by the plasma reactor in atmospheric conditions. Toluene removal proved to be achievable with a characteristic energy density epsilon(0) of 50 J l(-1). Removal efficiencies were higher for 26% relative humidity (epsilon(0)=35 J l(-1)), compared with those at increased humidities (50% relative humidity, epsilon(0)=49 J l(-1)). Reaction products such as formic acid, benzaldehyde, benzyl alcohol, 3-methyl-4-nitrophenol, 4-methyl-2-nitrophenol, 4-methyl-2-propyl furan, 5-methyl-2-nitrophenol, 4-nitrophenol, 2-methyl-4,6-dinitrophenol are identified by means of mass spectrometry. Based on these by-products a toluene degradation mechanism is proposed.

  7. Application of a pulse-discharge helium detector to the determination of neon in air and water.

    Science.gov (United States)

    Lasa, J; Mochalski, P; Lokas, E; Kedzior, L

    2002-08-30

    A pulse-discharge helium detector (Valco, PD-D2-I) is used to measure neon concentrations in air and water. The detection level is 0.5 x 10(-8) g/cm3 (0.2 ppm). Discharge gas doped with neon results in a linear response to the neon mass up to 10(-6) g. For measuring the neon concentration in water, a simple enrichment system is used.

  8. Experimental study of hard X-rays emitted from meter-scale positive discharges in air

    CERN Document Server

    Kochkin, P O; van Deursen, A P J; Ebert, U

    2012-01-01

    We investigate structure and evolution of long positive spark breakdown; and we study at which stage pulses of hard X-rays are emitted. Positive high-voltage pulses of standardized lightning impulse wave form of about 1 MV were applied to about 1 meter of ambient air. The discharge evolution was imaged with a resolution of tens of nanoseconds with an intensified CCD camera. LaBr3(Ce+) scintillation detectors recorded the X-rays emitted during the process. The voltage and the currents on both electrodes were measured synchronously. All measurements indicate that first a large and dense corona of positive streamers emerges from the high voltage electrode. When they approach the grounded electrode, negative counter-streamers emerge there, and the emission of hard X-rays coincides with the connection of the positive streamers with the negative counter-streamers.

  9. Characterization of dielectric barrier discharge in air applying current measurement, numerical simulation and emission spectroscopy

    CERN Document Server

    Rajasekaran, Priyadarshini; Awakowicz, Peter

    2012-01-01

    Dielectric barrier discharge (DBD) in air is characterized applying current measurement, numerical simulation and optical emission spectroscopy (OES). For OES, a non-calibrated spectrometer is used. This diagnostic method is applicable when cross-sectional area of the active plasma volume and current density can be determined. The nitrogen emission in the spectral range of 380 nm- 406 nm is used for OES diagnostics. Electric field in the active plasma volume is determined applying the measured spectrum, well-known Frank-Condon factors for nitrogen transitions and numerically- simulated electron distribution functions. The measured electric current density is used for determination of electron density in plasma. Using the determined plasma parameters, the dissociation rate of nitrogen and oxygen in active plasma volume are calculated, which can be used by simulation of the chemical kinetics.

  10. Nanoscratch technique for aligning multiwalled carbon nanotubes synthesized by the arc discharge method in open air

    Indian Academy of Sciences (India)

    A Joseph Berkmans; M Jagannatham; Prathap Haridoss

    2015-08-01

    Horizontally aligned and densely packed multiwalled carbon nanotubes (MWCNTs) were synthesized in an open air, without the need for a controlled atmosphere, using a rotating cathode arc discharge method with the help of a metal scraper. The physical force exerted by the scraper results in in-situ alignment of MWCNTs along the direction of scrape marks. This strategy, which enables the alignment of nanotubes in a controlled fashion to any length and direction of interest, was examined to determine the force required to align a nanotube. A model is developed to understand the alignment process. Using the nanoscratch technique to mimic this strategy, and incorporating the data obtained from the nanoscratch technique into the model developed, the minimum force required to align a MWCNT, as well as the energy required to align a gram of nanotubes, has been estimated. The method demonstrated represents an economical approach for large-scale synthesis of aligned MWCNTs at low costs.

  11. Time-lag properties of corona streamer discharges between impulse sphere and dc needle electrodes under atmospheric air conditions

    Science.gov (United States)

    Okano, Daisuke

    2013-02-01

    In this study of corona streamer discharges from an impulse generator using a dc power supply, the relationship of the discharge time-lag with the dc bias voltage between the sphere-to-needle electrodes under atmospheric conditions is investigated. Devices utilizing corona discharges have been used to purify air or water, destroy bacteria, and to remove undesirable substances, and in order to achieve fast response times and high power efficiencies in such devices, it is important to minimize the time-lag of the corona discharge. Our experimental results show that (a) the discharge path of a negatively biased needle electrode will be straighter than that of a positively biased needle and (b) the discharge threshold voltage in both the positive and the negative needle electrodes is nearly equal to 33 kV. By expressing the discharge voltage as a power function of time-lag, the extent of corona generation can be quantitatively specified using the exponent of this power function. The observed behavior of a corona streamer discharge between the negative spherical and the positive needle electrodes indicates that the largest power exponent is associated with the shortest time-lag, owing to the reduction in the statistical time-lag in the absence of a formative time-lag.

  12. Electro-hydrodynamics and kinetic modelling of polluted air flow activated by multi-tip-to-plane corona discharge

    Science.gov (United States)

    Meziane, M.; Eichwald, O.; Sarrette, J. P.; Ducasse, O.; Yousfi, M.; Marchal, F.

    2013-04-01

    The present paper is devoted to the 2D simulation of an Atmospheric Corona Discharge Reactor (ACDR) involving 10 pins powered by a DC high voltage and positioned 7 mm above a grounded metallic plane. The corona reactor is periodically crossed by thin mono filamentary streamers with a natural repetition frequency of some tens of kHz. The simulation involves the electro-dynamic, chemical kinetic, and neutral gas hydrodynamic phenomena that influence the kinetics of the chemical species transformation. Each discharge stage (including the primary and the secondary streamers development and the resulting thermal shock) lasts about one hundred nanoseconds while the post-discharge stages occurring between two successive discharge phases last one hundred microseconds. The ACDR is crossed by a lateral air flow including 400 ppm of NO. During the considered time scale of 10 ms, one hundred discharge/post-discharge cycles are simulated. The simulation involves the radical formation and thermal exchange between the discharges and the background gas. The results show how the successive discharges activate the flow gas and how the induced turbulence phenomena affect the redistribution of the thermal energy and the chemical kinetics inside the ACDR.

  13. Time-lag properties of corona streamer discharges between impulse sphere and dc needle electrodes under atmospheric air conditions.

    Science.gov (United States)

    Okano, Daisuke

    2013-02-01

    In this study of corona streamer discharges from an impulse generator using a dc power supply, the relationship of the discharge time-lag with the dc bias voltage between the sphere-to-needle electrodes under atmospheric conditions is investigated. Devices utilizing corona discharges have been used to purify air or water, destroy bacteria, and to remove undesirable substances, and in order to achieve fast response times and high power efficiencies in such devices, it is important to minimize the time-lag of the corona discharge. Our experimental results show that (a) the discharge path of a negatively biased needle electrode will be straighter than that of a positively biased needle and (b) the discharge threshold voltage in both the positive and the negative needle electrodes is nearly equal to 33 kV. By expressing the discharge voltage as a power function of time-lag, the extent of corona generation can be quantitatively specified using the exponent of this power function. The observed behavior of a corona streamer discharge between the negative spherical and the positive needle electrodes indicates that the largest power exponent is associated with the shortest time-lag, owing to the reduction in the statistical time-lag in the absence of a formative time-lag.

  14. Electro-hydrodynamics and kinetic modelling of polluted air flow activated by multi-tip-to-plane corona discharge

    Energy Technology Data Exchange (ETDEWEB)

    Meziane, M.; Eichwald, O.; Ducasse, O.; Marchal, F. [Universite de Toulouse, UPS, INPT, LAPLACE (Laboratoire Plasma et Conversion d' Energie), Toulouse Cedex 9 F-31062 (France); Sarrette, J. P.; Yousfi, M. [Universite de Toulouse, UPS, INPT, LAPLACE (Laboratoire Plasma et Conversion d' Energie), Toulouse Cedex 9 F-31062 (France); CNRS, LAPLACE, Toulouse F-31062 (France)

    2013-04-21

    The present paper is devoted to the 2D simulation of an Atmospheric Corona Discharge Reactor (ACDR) involving 10 pins powered by a DC high voltage and positioned 7 mm above a grounded metallic plane. The corona reactor is periodically crossed by thin mono filamentary streamers with a natural repetition frequency of some tens of kHz. The simulation involves the electro-dynamic, chemical kinetic, and neutral gas hydrodynamic phenomena that influence the kinetics of the chemical species transformation. Each discharge stage (including the primary and the secondary streamers development and the resulting thermal shock) lasts about one hundred nanoseconds while the post-discharge stages occurring between two successive discharge phases last one hundred microseconds. The ACDR is crossed by a lateral air flow including 400 ppm of NO. During the considered time scale of 10 ms, one hundred discharge/post-discharge cycles are simulated. The simulation involves the radical formation and thermal exchange between the discharges and the background gas. The results show how the successive discharges activate the flow gas and how the induced turbulence phenomena affect the redistribution of the thermal energy and the chemical kinetics inside the ACDR.

  15. Post-discharge treatment of air effluents polluted by butyl-mercaptan: the role of nitrate radical

    Science.gov (United States)

    Liu, Y. N.; Braci, L.; Cavadias, S.; Ognier, S.

    2011-03-01

    Dry air polluted by butyl-mercaptan was treated in a dielectric barrier discharge reactor at atmospheric pressure using air as plasmagene gas in discharge and post-discharge modes. The energy density was varied between 200 and 1300 J l-1. To assess the treatment efficiency, the concentrations of butyl-mercaptan, total volatile organic compounds (VOCs) and SO2 were determined in the exhaust gas. Whatever the energy density was, the treatment efficiency was better in the post-discharge mode. Butyl-mercaptan could be completely eliminated from 400 J l-1 and SO2 selectivity was always low, below 10%. Measurements of CO, CO2 and total VOCs indicated that 50-70% of the reaction products were condensed on the reactor wall in the form of micro-droplets, depending on the energy density. FTIR and XPS techniques were used to characterize the reaction products which were soluble in water. These analyses indicated that the reaction products contained oxygen, nitrogen and sulfur in an oxidized form. A reaction mechanism involving hydrogen abstraction from the -SH bond by the nitrate radical was proposed, pointing out the important role of nitrate radicals NO3 in the reactivity of air flowing post-discharge.

  16. Surface modification of chitosan/PEO nanofibers by air dielectric barrier discharge plasma for acetylcholinesterase immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Dorraki, Naghme, E-mail: n.dorraki@web.sbu.ac.ir [Laser and Plasma Research Institute, Shahid Beheshti University, Evin 1983963113, Tehran (Iran, Islamic Republic of); Safa, Nasrin Navab [Laser and Plasma Research Institute, Shahid Beheshti University, Evin 1983963113, Tehran (Iran, Islamic Republic of); Jahanfar, Mehdi [Protein Research Center, Shahid Beheshti University, Evin 1983963113, Tehran (Iran, Islamic Republic of); Ghomi, Hamid [Laser and Plasma Research Institute, Shahid Beheshti University, Evin 1983963113, Tehran (Iran, Islamic Republic of); Ranaei-Siadat, Seyed-Omid [Protein Research Center, Shahid Beheshti University, Evin 1983963113, Tehran (Iran, Islamic Republic of)

    2015-09-15

    Highlights: • We used an economical and effective method for surface modification. • Chitosan/PEO nanofibrous membranes were modified by air-DBD plasma. • The most NH{sub 3}{sup +} group was generated on the 6 min plasma modified membrane. • We immobilized acetylcholinesterase on the plasma modified and unmodified membranes. • More enzyme activity was detected on the modified membrane by plasma. - Abstract: There are different methods to modify polymer surfaces for biological applications. In this work we have introduced air-dielectric barrier discharge (DBD) plasma at atmospheric pressure as an economical and safe method for modifying the surface of electrospun chitosan/PEO (90/10) nanofibers for acetylcholinesterase (AChE) immobilization. According to the contact angle measurement results, the nanofibers become highly hydrophilic when they are exposed to the DBD plasma for 6 min in compared to unmodified membrane. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) results reveal hydroxyl, C=O and NH{sub 3}{sup +} polar groups increment after 6 min plasma treatment. Contact angle measurements and ATR-FTIR results are confirmed by X-ray photoelectron spectroscopy (XPS). AChE at pH 7.4 carries a negative charge and after immobilization on the surface of plasma-treated nanofibrous membrane attracts the NH{sub 3}{sup +} group and more enzyme activity is detected on the plasma-modified nanofibers for 6 min in compared to unmodified nanofibers. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) are used for the surface topography and morphology characterization. The results have proved that air-DBD plasma is a suitable method for chitosan/PEO nanofibrous membrane modification as a biodegradable and functionalized substrate for enzyme immobilization.

  17. Communication: The influence of CO2 poisoning on overvoltages and discharge capacity in non-aqueous Li-Air batteries

    DEFF Research Database (Denmark)

    Mekonnen, Yedilfana Setarge; Knudsen, Kristian Bastholm; Mýrdal, Jón Steinar Garðarsson;

    2014-01-01

    The effects of Li2CO3 like species originating from reactions between CO2 and Li2O2 at the cathode of non-aqueous Li-air batteries were studied by density functional theory (DFT) and galvanostatic charge-discharge measurements. Adsorption energies of CO2 at various nucleation sites on a stepped (1...

  18. Mark I Containment Program. Scaling analysis for modeling initial air clearing caused by reactor safety/relief valve discharge. [BWR

    Energy Technology Data Exchange (ETDEWEB)

    Schrum, R.W.

    1978-02-01

    A generalized method of similitude is introduced and applied to develop scaling relationships for a General Electric Mark I suppression pool. A scale model is proposed to model suppression pool wall loads due to air flow through a T-quencher discharge device. The scaling relationships developed provide the means for relating scale model parameters (i.e., pressure, velocity,) to full scale.

  19. Analytical model for estimating drag forces on rigid submerged structures caused by LOCA and safety relief valve ramshead air discharges. [BWR

    Energy Technology Data Exchange (ETDEWEB)

    1977-09-01

    Basic information is presented for estimating drag forces on rigid structural members submerged in a pressure suppression pool, caused by either the air discharge from a loss-of-coolant accident (LOCA), or the air bubble oscillation following safey relief valve ramshead discharge. Methods are described for estimating acceleration (unsteady) and standard (velocity-squared) drag force components for a variety of structural geometries.

  20. 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.

  1. Voltage dependence property of parameters for human body discharge in air through a small metal rod

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Discharge parameters are measured and calculated in electrostatic discharge (ESD) from charged human body through a small moving handheld metal rod. Correlation study has been performed on discharge parameters with charge voltage as well as approach speed. At charge voltage 800 V, difference of discharge parameters caused by fast and slow approach speed of electrode is found to reach extreme values. To explore the reason for this special case, an analysis with a short-gap ESD model is carried out.

  2. Dynamic Characteristics of Positive Pulsed Dielectric Barrier Discharge for Ozone Generation in Air

    Science.gov (United States)

    Wei, Linsheng; Peng, Bangfa; Li, Ming; Zhang, Yafang; Hu, Zhaoji

    2016-02-01

    A comprehensive dynamic model consisting of 66 reactions and 24 species is developed to investigate the dynamic characteristics of ozone generation by positive pulsed dielectric barrier discharge (DBD) using parallel-plate reactor in air. The electron energy conservation equation is coupled to the electron continuity equation, the heavy species continuity equation, and Poisson's equation for a better description. The reliability of the model is experimentally confirmed. The model can be used to predict the temporal and spatial evolution of species, as well as streamer propagation. The simulation results show that electron density increases nearly exponentially in the direction to the anode at the electron avalanche. Streamer propagation velocity is about 5.26 × 104 m/s from anode to cathode in the simulated condition. The primary positive ion, negative ion, and excited species are O2+, O3- and O2(1Δg) in pulsed DBD in air, respectively. N2O has the largest density among nitrogen oxides. e and N2+ densities in the streamer head increase gradually to maximum values with the development of the streamer. Meanwhile, the O2+, O, O3, N2(A3Σ) and N2O densities reach maximum values in the vicinity of the anode. supported by National Natural Science Foundation of China (Nos. 51366012 and 11105067), Jiangxi Province Young Scientists (Jinggang Star) Cultivation Plan of China (No. 20133BCB23008), Natural Science Foundation of Jiangxi, China (No. 20151BAB206047) and Jiangxi Province Higher School Science and Technology Landing Plan of China (No. KJLD-14015)

  3. Silent Discharge Plasma Technology for the Treatment of Air Toxics and Other Applications

    Energy Technology Data Exchange (ETDEWEB)

    Rosocha, Louis A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Chase, Peter J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Gross, Michael P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    1998-09-21

    Under this CRADA, the Los Alamos National Laboratory (LANL) and High Mesa Technologies, Inc. (HMT) carried out a joint project on the development of the silent discharge plasma (SDP) technology for the treatment of hazardous air pollutants and other hazardous or toxic chemicals. The project had two major components: a technology-demonstration part and a scale-up and commercialization part. In the first part, a small-scale, mobile SDP plasma processor, which was being developed under a CRADA with the Electric Power Research Institute (EPRI) was the mobile equipment was modified for higher capacity service and employed for an innovative remediation technologies demonstration on soil-vapor extraction off-gases at the McClellan Air Force Base near Sacramento, CA. The performance of the SDP system for the variety of volatile organic compounds (VOCs) encountered at the McClellan site was sufficiently promising to the project HMT and LANL worked together to formulate a scale-up strategy and commercialization/manufacturing plan, and to design a prototype scaled-up SDP unit. HMT and LANL are now in the final stages of completing a licensing agreement for the technology and HMT is in the process of raising funds to engineer and manufacture commercial prototype SDP equipment focused on stack-gas emissions control and environmental remediation. HMT, in collaboration with another Northern New Mexico business, Coyote Aerospace, has also been successful in receiving a Phase I Small Business Innovative Research (SBIR) award from the Army Research Office to develop, design, and construct a small non-thermal plasma reactor for laboratory studies ("Non-Thermal Plasma Reactor for Control of Fugitive Emissions of Toxic Gases")

  4. 2D simulation of active species and ozone production in a multi-tip DC air corona discharge

    Science.gov (United States)

    Meziane, M.; Eichwald, O.; Sarrette, J. P.; Ducasse, O.; Yousfi, M.

    2011-11-01

    The present paper shows for the first time in the literature a complete 2D simulation of the ozone production in a DC positive multi-tip to plane corona discharge reactor crossed by a dry air flow at atmospheric pressure. The simulation is undertaken until 1 ms and involves tens of successive discharge and post-discharge phases. The air flow is stressed by several monofilament corona discharges generated by a maximum of four anodic tips distributed along the reactor. The nonstationary hydrodynamics model for reactive gas mixture is solved using the commercial FLUENT software. During each discharge phase, thermal and vibrational energies as well as densities of radical and metastable excited species are locally injected as source terms in the gas medium surrounding each tip. The chosen chemical model involves 10 neutral species reacting following 24 reactions. The obtained results allow us to follow the cartography of the temperature and the ozone production inside the corona reactor as a function of the number of high voltage anodic tips.

  5. Uniform and non-uniform modes of nanosecond-pulsed dielectric barrier discharge in atmospheric air: fast imaging and spectroscopic measurements of electric field.

    Science.gov (United States)

    Liu, Chong; Dobrynin, Danil; Fridman, Alexander

    2014-06-25

    In this study, we report experimental results on fast ICCD imaging of development of nanosecond-pulsed dielectric barrier discharge (DBD) in atmospheric air and spectroscopic measurements of electric field in the discharge. Uniformity of the discharge images obtained with nanosecond exposure times were analyzed using chi-square test. The results indicate that DBD uniformity strongly depends on applied (global) electric field in the discharge gap, and is a threshold phenomenon. We show that in the case of strong overvoltage on the discharge gap (provided by fast rise times), there is transition from filamentary to uniform DBD mode which correlates to the corresponding decrease of maximum local electric field in the discharge.

  6. Improving Hydrophobicity of Glass Surface Using Dielectric Barrier Discharge Treatment in Atmospheric Air

    Institute of Scientific and Technical Information of China (English)

    FANG Zhi; QIU Yuchang; WANG Hui; E. KUFFEL

    2007-01-01

    Non-thermal plasmas under atmospheric pressure are of great interest in industrial applications, especially in material surface treatment. In this paper, the treatment of a glass surface for improving hydrophobicity using the non-thermal plasma generated by dielectric barrier discharge (DBD) at atmospheric pressure in ambient air is conducted, and the surface properties of the glass before and after the DBD treatment are studied by using contact angle measurement, surface resistance measurement and wet flashover voltage tests. The effects of the applied voltage and time duration of DBD on the surface modification are studied, and the optimal conditions for the treatment are obtained. It is found that a layer of hydrophobic coating is formed on the glass surface after spraying a thin layer of silicone oil and undergoing the DBD treatment, and the improvement of hydrophobicity depends on DBD voltage and treating time. It seems that there exists an optimum treating time for a certain applied voltage of DBD during the surface treatment. The test results of thermal aging and chemical aging show that the hydrophobic layer has quite stable characteristics. The interaction mechanism between the DBD plasma and the glass surface is discussed. It is concluded that CH3 and large molecule radicals can react with the radicals in the glass surface to replace OH, and the hydrophobicity of the glass surface is improved accordingly.

  7. Atomic oxygen dynamics in an air dielectric barrier discharge: a combined diagnostic and modeling approach

    Science.gov (United States)

    Baldus, Sabrina; Schröder, Daniel; Bibinov, Nikita; Schulz-von der Gathen, Volker; Awakowicz, Peter

    2015-06-01

    Cold atmospheric pressure plasmas are a promising alternative therapy for treatment of chronic wounds, as they have already shown in clinical trials. In this study an air dielectric barrier discharge (DBD) developed for therapeutic use in dermatology is characterized with respect to the plasma produced reactive oxygen species, namely atomic oxygen and ozone, which are known to be of great importance to wound healing. To understand the plasma chemistry of the applied DBD, xenon-calibrated two-photon laser-induced fluorescence spectroscopy and optical absorption spectroscopy are applied. The measured spatial distributions are shown and compared to each other. A model of the afterglow chemistry based on optical emission spectroscopy is developed to cross-check the measurement results and obtain insight into the dynamics of the considered reactive oxygen species. The atomic oxygen density is found to be located mostly between the electrodes with a maximum density of {{n}\\text{O}}=6× {{10}16} cm-3 . Time resolved measurements reveal a constant atomic oxygen density between two high voltage pulses. The ozone is measured up to 3 mm outside the active plasma volume, reaching a maximum value of {{n}{{\\text{O}3}}}=3× {{10}16} cm-3 between the electrodes.

  8. Pulsed nanosecond discharge in air at high specific deposited energy: fast gas heating and active particle production

    Science.gov (United States)

    Popov, N. A.

    2016-08-01

    The results of a numerical study on kinetic processes initiated by a pulsed nanosecond discharge in air at high specific deposited energy, when the dissociation degree of oxygen molecules is high, are presented. The calculations of the temporal dynamics of the electron concentration, density of atomic oxygen, vibrational distribution function of nitrogen molecules, and gas temperature agree with the experimental data. It is shown that quenching of electronically excited states of nitrogen N2(B3Πg), N2(C3Πu), N2(a‧1 Σ \\text{u}- ) by oxygen molecules leads to the dissociation of O2. This conclusion is based on the comparison of calculated dynamics of atomic oxygen in air, excited by a pulsed nanosecond discharge, with experimental data. In air plasma at a high dissociation degree of oxygen molecules ([O]/[O2] > 10%), relaxation of the electronic energy of atoms and molecules in reactions with O atoms becomes extremely important. Active production of NO molecules and fast gas heating in the discharge plasma due to the quenching of electronically excited N2(B3Πg, C3Πu, a‧1 Σ \\text{u}- ) molecules by oxygen atoms is notable. Owing to the high O atom density, electrons are effectively detached from negative ions in the discharge afterglow. As a result, the decay of plasma in the afterglow is determined by electron-ion recombination, and the electron density remains relatively high between the pulses. An increase in the vibrational temperature of nitrogen molecules at the periphery of the plasma channel at time delay t = 1-30 μs after the discharge is obtained. This is due to intense gas heating and, as a result, gas-dynamic expansion of a hot gas channel. Vibrationally excited N2(v) molecules produced near the discharge axis move from the axial region to the periphery. Consequently, at the periphery the vibrational temperature of nitrogen molecules is increased.

  9. Experimental Platform Design on Flowing Resistance of Air Vents for Bullet Train%高速动车换气口流动阻力实验台设计

    Institute of Scientific and Technical Information of China (English)

    何忠韬; 方海容

    2013-01-01

    探讨了高速动车换气口流动阻力实验台相关问题,根据流体力学相关原理,提出用低速风洞模拟列车外界风速场,换气口试件置于风洞试验段中,将列车外界风速、流经换气口的风量模拟量都设计成可调控的实验参数,搭建了用于换气口流动阻力及其影响因素的实验平台。实验实例表明,本文方法建立的高速动车换气口流动阻力实验台方案是可行的,测量结果是可信的。%Problems about an experimental platform are discussed,recurring to which,the flowing resistance of air vents on the bullet train can be researched.According to the principle of fluid mechanics,it is put forward that the train wind field outside can be simulated by the low speed wind tunnel,the ventilation test piece is placed in the test section of wind tunnel,the wind speed outside and the flowing rate through the air vents are tunable,then a experimental platform for flowing resistance of air vents is built.The experimental results show that the scheme of the experimental platform is feasible,and the measurement results are credible.

  10. AIR ATMOSPHERIC-PRESSURE DISCHARGERS FOR OPERATION IN HIGH-FREQUENCY SWITCHING MODE.

    Directory of Open Access Journals (Sweden)

    L.S. Yevdoshenko

    2013-10-01

    Full Text Available Operation of two designs of compact multigap dischargers has been investigated in a high-frequency switching mode. It is experimentally revealed that the rational length of single discharge gaps in the designs is 0.3 mm, and the maximum switching frequency is 27000 discharges per second under long-term stable operation of the dischargers. It is shown that in pulsed corona discharge reactors, the pulse front sharpening results in increasing the operating electric field strength by 1.3 – 1.8 times.

  11. Simulation of Thermal and Chemical Relaxation in a Post-Discharge Air Corona Reactor

    CERN Document Server

    Meziane, M; Ducasse, O; Yousfi, M

    2016-01-01

    In a DC point-to-plane corona discharge reactor, the mono filamentary streamers cross the inter electrode gap with a natural repetition frequency of some tens of kHz. The discharge phase (including the primary and the secondary streamers development) lasts only some hundred of nanoseconds while the post-discharge phases occurring between two successive discharge phases last some tens of microseconds. From the point of view of chemical activation, the discharge phases create radical and excited species located inside the very thin discharge filaments while during the post-discharge phases these radical and excited species induce a chemical kinetics that diffuse in a part of the reactor volume. From the point of view of hydrodynamics activation, the discharge phases induce thermal shock waves and the storage of vibrational energy which relaxes into thermal form only during the post-discharge phase. Furthermore, the glow corona discharges that persist during the post-discharge phases induce the so called electri...

  12. Understanding vented gas explosions

    Energy Technology Data Exchange (ETDEWEB)

    Lautkaski, R. [VTT Energy, Espoo (Finland). Energy Systems

    1997-12-31

    The report is an introduction to vented gas explosions for nonspecialists, particularly designers of plants for flammable gases and liquids. The phenomena leading to pressure generation in vented gas explosions in empty and congested rooms are reviewed. The four peak model of vented gas explosions is presented with simple methods to predict the values of the individual peaks. Experimental data on the external explosion of dust and gas explosions is discussed. The empirical equation relating the internal and external peak pressures in vented dust explosions is shown to be valid for gas explosion tests in 30 m{sup 3} and 550 m{sup 3} chambers. However, the difficulty of predicting the internal peak pressure in large chambers remains. Methods of explosion relief panel design and principles of vent and equipment layout to reduce explosion overpressures are reviewed. (orig.) 65 refs.

  13. A DC corona discharge on a flat plate to induce air movement

    OpenAIRE

    Magnier, Pierre; Hong, Dunpin; Leroy-Chesneau, Annie; Pouvesle, Jean-Michel; Hureau, Jacques

    2007-01-01

    International audience; This paper describes a DC surface corona discharge designed to modify the airflow around a flat plate. The electrode configuration consisted of two thin copper layers placed on each side of the plate's attack edge. Discharge optical measurements with a photomultiplier tube indicated that the light emitted by the plasma is pulsating, at a frequency that increases with applied voltage. Moreover, with voltage higher than a threshold value, the electric discharge changes r...

  14. Large-volume excitation of air, argon, nitrogen and combustible mixtures by thermal jets produced by nanosecond spark discharges

    Science.gov (United States)

    Stepanyan, Sergey; Hayashi, Jun; Salmon, Arthur; Stancu, Gabi D.; Laux, Christophe O.

    2017-04-01

    This work presents experimental observations of strong expanding thermal jets following the application of nanosecond spark discharges. These jets propagate in a toroidal shape perpendicular to the interelectrode axis, with high velocities of up to 30 m s‑1 and over distances of the order of a cm. Their propagation length is much larger than the thermal expansion region produced by the conventional millisecond sparks used in car engine ignition, thus greatly improving the volumetric excitation of gas mixtures. The shape and velocity of the jets is found to be fairly insensitive to the shape of the electrodes. In addition, their spatial extent is found to increase with the number of nanosecond sparks and with the discharge voltage, and to decrease slightly with the pressure between 1 and 7 atm at constant applied voltage. Finally, this thermal jet phenomenon is observed in experiments conducted with many types of gas mixtures, including air, nitrogen, argon, and combustible CH4/air mixtures. This makes nanosecond repetitively pulsed discharges particularly attractive for aerodynamic flow control or plasma-assisted combustion because of their ability to excite large volumes of gas, typically about 100 times the volume of the discharge.

  15. Hospital survival upon discharge of ill-neonates transported by ground or air ambulance to a tertiary center

    Directory of Open Access Journals (Sweden)

    Jorge Luis Alvarado-Socarras

    2016-06-01

    Full Text Available Abstract Objective: To evaluate the differences in hospital survival between modes of transport to a tertiary center in Colombia for critically ill neonates. Methods: Observational study of seriously ill neonates transported via air or ground, who required medical care at a center providing highly complex services. Data on sociodemographic, clinical, the Transport Risk Index of Physiologic Stability (TRIPS, and mode of transport were collected. Patients were described, followed by a bivariate analysis with condition (live or dead at time of discharge as the dependent variable. A multiple Poisson regression with robust variance model was used to adjust associations. Results: A total of 176 neonates were transported by ambulance (10.22% by air over six months. The transport distances were longer by air (median: 237.5 km than by ground (median: 11.3 km. Mortality was higher among neonates transported by air (33.33% than by ground (7.79%. No differences in survival were found between the two groups when adjusted by the multiple model. An interaction between mode of transport and distance was observed. Live hospital discharge was found to be associated with clinical severity upon admittance, birth weight, hemorrhaging during the third trimester, and serum potassium levels when admitted. Conclusions: Mode of transport was not associated with the outcome. In Colombia, access to medical services through air transport is a good option for neonates in critical condition. Further studies would determine the optimum distance (time of transportation to obtain good clinical outcomes according type of ambulance.

  16. Study on Detection of Negative Corona Discharge Generated in Rod-Plane Air Gap by Using External Electrode Method

    Institute of Scientific and Technical Information of China (English)

    N.ICHIKAWA

    2007-01-01

    A detective method of a negative corona discharge by means of an external electrode is presented.The relationship between an area of the external electrode and a detected voltage waveform is examined experimentally.This experimental study is carried out with the use of a rod-plane air gap.The results obtained will be applicable to problems associated with silos,ducts,and high-voltage equipment.

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

    Science.gov (United States)

    Pai, David Z.; Lacoste, Deanna A.; Laux, Christophe O.

    2010-05-01

    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 interelectrode gap distance) of each discharge regime. In particular, the experimental conditions necessary for the glow regime of NRP discharges have been determined, with the notable result that there exists a minimum and maximum gap distance for its existence at a given ambient gas temperature. The minimum gap distance increases with decreasing gas temperature, whereas the maximum does not vary appreciably. To explain the experimental results, an analytical model is developed to explain the corona-to-glow (C-G) and glow-to-spark (G-S) transitions. The C-G transition is analyzed in terms of the avalanche-to-streamer transition and the breakdown field during the conduction phase following the establishment of a conducting channel across the discharge gap. The G-S transition is determined by the thermal ionization instability, and we show analytically that this transition occurs at a certain reduced electric field for the NRP discharges studied here. This model shows that the electrode geometry plays an important role in the existence of the NRP glow regime at a given gas temperature. We derive a criterion for the existence of the NRP glow regime as a function of the ambient gas temperature, pulse repetition frequency, electrode radius of curvature, and interelectrode gap distance.

  18. ANALYSIS OF VENTING OF A RESIN SLURRY

    Energy Technology Data Exchange (ETDEWEB)

    Laurinat, J.; Hensel, S.

    2012-03-27

    A resin slurry venting analysis was conducted to address safety issues associated with overpressurization of ion exchange columns used in the Purex process at the Savannah River Site (SRS). If flow to these columns were inadvertently interrupted, an exothermic runaway reaction could occur between the ion exchange resin and the nitric acid used in the feed stream. The nitric acid-resin reaction generates significant quantities of noncondensable gases, which would pressurize the column. To prevent the column from rupturing during such events, rupture disks are installed on the column vent lines. The venting analysis models accelerating rate calorimeter (ARC) tests and data from tests that were performed in a vented test vessel with a rupture disk. The tests showed that the pressure inside the test vessel continued to increase after the rupture disk opened, though at a slower rate than prior to the rupture. Calculated maximum discharge rates for the resin venting tests exceeded the measured rates of gas generation, so the vent size was sufficient to relieve the pressure in the test vessel if the vent flow rate was constant. The increase in the vessel pressure is modeled as a transient phenomenon associated with expansion of the resin slurry/gas mixture upon rupture of the disk. It is postulated that the maximum pressure at the end of this expansion is limited by energy minimization to approximately 1.5 times the rupture disk burst pressure. The magnitude of this pressure increase is consistent with the measured pressure transients. The results of this analysis demonstrate the need to allow for a margin between the design pressure and the rupture disk burst pressure in similar applications.

  19. Preoperational test report, vent building ventilation system

    Energy Technology Data Exchange (ETDEWEB)

    Clifton, F.T.

    1997-11-04

    This represents a preoperational test report for Vent Building Ventilation Systems, Project W-030. Project W-030 provides a ventilation upgrade for the four Aging Waste Facility tanks. The system provides Heating, Ventilation, and Air Conditioning (HVAC) for the W-030 Ventilation Building. The tests verify correct system operation and correct indications displayed by the central Monitor and Control System.

  20. Prolongation of the lifetime of guided discharges triggered in atmospheric air by femtosecond laser filaments up to 130 μs

    Science.gov (United States)

    Arantchouk, L.; Honnorat, B.; Thouin, E.; Point, G.; Mysyrowicz, A.; Houard, A.

    2016-04-01

    The triggering and guiding of electric discharges produced in atmospheric air by a compact 100 kV Marx generator is realized in laboratory using an intense femtosecond laser pulse undergoing filamentation. We describe here an approach allowing extending the lifetime of the discharges by injecting a current with an additional circuit. Laser guiding discharges with a length of 8.5 cm and duration of 130 μs were obtained.

  1. Simulation of the propagation and reignition of atmospheric pressure air discharges behind a dielectric plane obstacle

    Science.gov (United States)

    Pechereau, Francois; Jansky, Jaroslav; Bourdon, Anne

    2012-10-01

    In recent years, experimental studies on flue gas treatment have demonstrated the efficiency of plasma assisted catalysis for the treatment of a wide range of pollutants at a low energetic cost. In plasma reactors, usual catalyst supports are pellets, monoliths or porous media, and then atmospheric pressure discharges have to interact with many obstacles and to propagate in microcavities and pores. As a first step to better understand atmospheric pressure discharge dynamics in these complex geometries, in this work, we have carried out numerical simulations using a 2D-axisymmetric fluid model for a point-to-plane discharge with a dielectric plane obstacle placed in the path of the discharge. First, we have simulated the discharge ignition at the point electrode, its propagation in the gap and its impact and expansion on the dielectric plane. Depending on the applied voltage, the dielectric plane geometry and permittivity, we have identified conditions for the reignition of a second discharge behind the plane obstacle. These conditions will be discussed and compared with recent experimental results on the same configuration.

  2. Interferometric and schlieren characterization of the plasmas and shock wave dynamics during laser-triggered discharge in atmospheric air

    Science.gov (United States)

    Wei, Wenfu; Li, Xingwen; Wu, Jian; Yang, Zefeng; Jia, Shenli; Qiu, Aici

    2014-08-01

    This paper describes our efforts to reveal the underlying physics of laser-triggered discharges in atmospheric air using a Mach-Zehnder interferometer and schlieren photography. Unlike the hemispherical shock waves that are produced by laser ablation, bell-like morphologies are observed during laser-triggered discharges. Phase shifts are recovered from the interferograms at a time of 1000 ns by the 2D fast Fourier transform method, and then the values of the refractive index are deduced using the Abel inversion. An abundance of free electrons is expected near the cathode surface. The schlieren photographs visualize the formation of stagnation layers at ˜600 ns in the interaction zones of the laser- and discharge-produced plasmas. Multiple reflected waves are observed at later times with the development of shock wave propagations. Estimations using the Taylor-Sedov self-similar solution indicated that approximately 45.8% and 51.9% of the laser and electrical energies are transferred into the gas flow motions, respectively. Finally, numerical simulations were performed, which successfully reproduced the main features of the experimental observations, and provided valuable insights into the plasma and shock wave dynamics during the laser-triggered discharge.

  3. Ozone generation in a kHz-pulsed He-O2 capillary dielectric barrier discharge operated in ambient air

    Science.gov (United States)

    Sands, Brian L.; Ganguly, Biswa N.

    2013-12-01

    The generation of reactive oxygen species using nonequilibrium atmospheric pressure plasma jet devices has been a subject of recent interest due to their ability to generate localized concentrations from a compact source. To date, such studies with plasma jet devices have primarily utilized radio-frequency excitation. In this work, we characterize ozone generation in a kHz-pulsed capillary dielectric barrier discharge configuration comprised of an active discharge plasma jet operating in ambient air that is externally grounded. The plasma jet flow gas was composed of helium with an admixture of up to 5% oxygen. A unipolar voltage pulse train with a 20 ns pulse risetime was used to drive the discharge at repetition rates between 2-25 kHz. Using UVLED absorption spectroscopy centered at 255 nm near the Hartley-band absorption peak, ozone was detected over 1 cm from the capillary axis. We observed roughly linear scaling of ozone production with increasing pulse repetition rate up to a "turnover frequency," beyond which ozone production steadily dropped and discharge current and 777 nm O(5P→5S°) emission sharply increased. The turnover in ozone production occurred at higher pulse frequencies with increasing flow rate and decreasing applied voltage with a common energy density of 55 mJ/cm3 supplied to the discharge. The limiting energy density and peak ozone production both increased with increasing O2 admixture. The power dissipated in the discharge was obtained from circuit current and voltage measurements using a modified parallel plate dielectric barrier discharge circuit model and the volume-averaged ozone concentration was derived from a 2D ozone absorption measurement. From these measurements, the volume-averaged efficiency of ozone production was calculated to be 23 g/kWh at conditions for peak ozone production of 41 mg/h at 11 kV applied voltage, 3% O2, 2 l/min flow rate, and 13 kHz pulse repetition rate, with 1.79 W dissipated in the discharge.

  4. Ozone production in parallel multichannel dielectric barrier discharge from oxygen and air: the influence of gas pressure

    Science.gov (United States)

    Yuan, Dingkun; Wang, Zhihua; Ding, Can; He, Yong; Whiddon, Ronald; Cen, Kefa

    2016-11-01

    This research aims to investigate the influence of gas pressure (0.1 Mpa-0.2 Mpa) on ozone generation in a parallel multichannel dielectric barrier discharge (DBD) reactor with a narrow gap (0.2 mm). In addition to determining ozone concentration and ozone yield characteristics with gas pressure variation, this paper examines the possible reasons leading to the inconsistency with previous reported results. All the experimental results are plotted on the basis of specific input energy (SIE) in order to conduct the comparison within identical power density. By reviewing the experimental results, the possible cause leading to the inconsistency concerning gas pressure dependences of ozone generation was found using different comparison bases. Results show that ozone generation is slightly suppressed with an increase of gas pressure with an initial increase in SIE. The results of the ozone yield show that an increase of gas pressure would have a favorable effect on ozone production efficiency with an SIE larger than 400 J l-1 in oxygen while ozone yield reaches the maximum at 0.14 Mpa with an SIE larger than 150 J l-1 in air. Increasing gas pressure would lead to a higher critical SIE value at which ozone yield firstly decreases with an increase of SIE both in oxygen and air. The results of nitrogen oxide byproducts show that both NO x byproducts emission and the discharge poisoning effect are suppressed by increasing gas pressure in air plasmas.

  5. Experimental study on hard X-rays emitted from metre-scale negative discharges in air

    CERN Document Server

    Kochkin, P O; Ebert, Ute

    2015-01-01

    We investigate the development of meter long negative discharges and focus on their X-ray emissions. We describe appearance, timing and spatial distribution of the X-rays. They appear in bursts of nanosecond duration mostly in the cathode area. The spectrum can be characterized by an exponential function with 200 keV characteristic photon energy. With nanosecond-fast photography we took detailed images of the pre-breakdown phenomena during the time when X-rays were registered. We found bipolar discharge structures, also called "pilot systems", in the vicinity of the cathode. As in our previous study of X-rays from positive discharges, we correlate the X-ray emission with encounters between positive and negative streamers. We suggest that a similar process is responsible for X-rays generated by lightning leaders.

  6. Study of the characteristics of a gas-discharge counter with a negatively charged wire in the air

    Energy Technology Data Exchange (ETDEWEB)

    Kalinnikov, V.A.; Kravchuk, N.P. E-mail: kravchuk@nusun.jinr.dubna.su; Kuchinsky, N.A

    1999-11-11

    Gas-discharge counters with a negative potential at the thin central electrode are studied. In a counter with thus applied high-voltage, electron avalanches develop in the direction away from the centre in a greatly decreasing electric field. The mechanism for this process and the effect of various factors are described. The counting and amplitude characteristics are given for one of the counters. The geometrically sensitive region and the dependence of its performance on the type of primary ionization is studied. The counter was tested in the air under normal conditions.

  7. Efficient new process for the desulfurization of mixtures of air and hydrogen sulfide via a dielectric barrier discharge plasma

    Directory of Open Access Journals (Sweden)

    S. Dahle

    2015-10-01

    Full Text Available The efficient removal of hydrogen sulfide, H2S, from streams of H2S in air via a dielectric barrier discharge (DBD plasma has been investigated using a quadrupole mass spectrometer. A suitable plasma device with a reservoir for storing sorbent powder of various kinds within the plasma region was constructed. Plasma treatments of gas streams with high concentrations of hydrogen sulfide in air yielded a removal of more than 98% of the initial hydrogen sulfide and a deposition of sulfur at the surface of the dielectric, while small amounts of sulfur dioxide were generated. The presence of calcium carbonate within the plasma region of the DBD device resulted in the removal of over 99% of the initial hydrogen sulfide content and the removal of 98% of the initial sulfur dioxide impurities from the gas mixture.

  8. Upstream petroleum industry flaring and venting report : industry performance for year ending December 31, 2008

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2009-06-15

    The Energy Resources Conservation Board (ERCB) has developed recommendations for a flaring and venting management framework for the province of Alberta. This report fulfilled the ERCB's information mandate regarding flaring and venting as part of a commitment made in Directive 060 for upstream petroleum industry flaring, incineration, and venting to make flaring and venting data more accessible. It included data on upstream petroleum industry flaring and venting with particular reference to solution gas conserved, flared and vented, from 1996 to 2008; solution gas flaring and venting performance; flaring from all upstream oil and gas sources, from 2000 to 2008; venting from all upstream oil and gas sources, from 2000 to 2008; solution gas flaring and venting maps; and solution gas emissions ranking of operators for 2007. The report also provided a summary of flaring and venting from various oil and gas industry sources, such as well tests, gas plants, gas gathering systems, transmission lines, and batteries. Ranking of companies was established based on solution gas flared plus vented; solution gas flared; and solution gas vented from crude oil and bitumen batteries. The data used in the preparation of this report was submitted by companies. The report revealed that considerable progress has been made in the reduction of flaring and venting volumes for all upstream oil and gas sources. The reduction can be attributed to the decline in new conventional oil production. It can also be correlated to the decline in volumes of solution gas formerly being flared, and now being vented. Solution gas vented in 2008 was 40.7 per cent less than the 2000 venting baseline. However, in 2008, there was a 25.9 per cent increase in venting from crude bitumen batteries which can be correlated to the increase in crude bitumen production. The ERCB is continuing to work with the Clean Air Strategic Alliance to examine options to further address solution gas venting. tabs., figs.

  9. 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.

  10. 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.

  11. Kinetics of excited states and radicals in a nanosecond pulse discharge and afterglow in nitrogen and air

    Science.gov (United States)

    Shkurenkov, Ivan; Burnette, David; Lempert, Walter R.; Adamovich, Igor V.

    2014-12-01

    The present kinetic modelling calculation results provide key new insights into the kinetics of vibrational excitation of nitrogen and plasma chemical reactions in nanosecond pulse, ‘diffuse filament’ discharges in nitrogen and dry air at a moderate energy loading per molecule, ˜0.1 eV per molecule. It is shown that it is very important to take into account Coulomb collisions between electrons because they change the electron energy distribution function and, as a result, strongly affect populations of excited states and radical concentrations in the discharge. The results demonstrate that the apparent transient rise of N2 ‘first level’ vibrational temperature after the discharge pulse, as detected in the experiments, is due to the net downward V-V energy transfer in N2-N2 collisions, which increases the N2(X 1Σ, v = 1) population. Finally, a comparison of the model's predictions with the experimental data shows that NO formation in the afterglow occurs via reactive quenching of multiple excited electronic levels of nitrogen molecule, N2\\ast , by O atoms. ) published in this volume, which focuses on the kinetic modelling of the experiments. This paper presents the results of the experiments.

  12. Assessment of Literature Related to Combustion Appliance Venting Systems

    Energy Technology Data Exchange (ETDEWEB)

    Rapp, V. H.; Less, B. D.; Singer, B. C.; Stratton, J. C.; Wray, C. P.

    2015-02-01

    In many residential building retrofit programs, air tightening to increase energy efficiency is often constrained by safety concerns with naturally vented combustion appliances. Tighter residential buildings more readily depressurize when exhaust equipment is operated, making combustion appliances more prone to backdraft or spill combustion exhaust into the living space. Several measures, such as installation guidelines, vent sizing codes, and combustion safety diagnostics, are in place with the intent to prevent backdrafting and combustion spillage, but the diagnostics conflict and the risk mitigation objective is inconsistent. This literature review summarizes the metrics and diagnostics used to assess combustion safety, documents their technical basis, and investigates their risk mitigations. It compiles information from the following: codes for combustion appliance venting and installation; standards and guidelines for combustion safety diagnostics; research evaluating combustion safety diagnostics; research investigating wind effects on building depressurization and venting; and software for simulating vent system performance.

  13. Influence of air flow parameters on nanosecond repetitively pulsed discharges in a pin-annular electrode configuration

    KAUST Repository

    Heitz, Sylvain A

    2016-03-16

    The effect of various air flow parameters on the plasma regimes of nanosecond repetitively pulsed (NRP) discharges is investigated at atmospheric pressure. The two electrodes are in a pin-annular configuration, transverse to the mean flow. The voltage pulses have amplitudes up to 15 kV, a duration of 10 ns and a repetition frequency ranging from 15 to 30 kHz. The NRP corona to NRP spark (C-S) regime transition and the NRP spark to NRP corona (S-C) regime transition are investigated for different steady and harmonically oscillating flows. First, the strong effect of a transverse flow on the C-S and S-C transitions, as reported in previous studies, is verified. Second, it is shown that the azimuthal flow imparted by a swirler does not affect the regime transition voltages. Finally, the influence of low frequency harmonic oscillations of the air flow, generated by a loudspeaker, is studied. A strong effect of frequency and amplitude of the incoming flow modulation on the NRP plasma regime is observed. Results are interpreted based on the cumulative effect of the NRP discharges and an analysis of the residence times of fluid particles in the inter-electrode region. © 2016 IOP Publishing Ltd.

  14. Trace analysis of organics in air by corona discharge atmospheric pressure ionization using an electrospray ionization interface.

    Science.gov (United States)

    Nikolaev, Eugene; Riter, Leah S; Laughlin, Brian C; Handberg, Eric; Cooks, R Graham

    2004-01-01

    A corona discharge ion source operating at atmospheric pressure in the point-to-plane configuration was constructed by reconfiguring the ion source of a commercial electrospray ionization (ESI) quadrupole mass spectrometer. This new source allows direct air analysis without modification to the mass spectrometer. Detection and quantitation of semi-volatile compounds in air is demonstrated. The analytical performance of the system was established using the chemical warfare agent simulants methyl salicylate and dimethyl methylphosphonate. Limits of detection are 60 pptr in the negative-ion mode and 800 pptr in the positive-ion mode for methyl salicylate and 800 pptr in the negative-ion mode and 3.6 ppb in the positive-ion mode for dimethyl methylphosphonate. A linear response was observed from 60 pptr to 8 ppb for methyl salicylate in air in the negative-ionization mode. Cluster ion formation versus production of analyte ions was investigated and it was found that dry air or an elevated capillary interface temperature (130 degrees C) was needed to avoid extensive clustering, mostly of water. Reagent gases are not needed as proton sources, as is usually the case for atmospheric pressure chemical ionization, and this, together with the simplicity, sensitivity and speed of the technique, makes it promising for miniaturization and future field studies.

  15. 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.

  16. Study of a Filamentary Dielectric Barrier Discharge in Air at Atmospheric Pressure

    Science.gov (United States)

    Celestin, Sebastien; Zeghondy, Barbar; Guaitella, Olivier; Bourdon, Anne; Rousseau, Antoine

    2006-10-01

    Dielectric Barrier Discharges (DBD) at atmospheric pressure have many applications, for instance ozone production, surface treatment, and waste gas treatment. Generally, such a discharge is filamentary but it can be diffuse under particular conditions. Understanding the formation of the filament, which is an ionization wave or so-called ``streamer'', is very hard theoretically, numerically, and experimentally. This is due, first, to the non-linearity of the equations concerned, and second, because of the scaling in space and time of this phenomenon: a streamer has a radius on the order of a few microns, and propagates through distances of several centimeters in a few nanoseconds. In this study we will present the results obtained in experiments and in simulations for a plane-to-plane DBD. We electrically characterized this device and have observed collective effects that are still poorly understood. A point-to-plane DBD has also been studied for producing a much more localized discharge. In parallel with the experimental study we have developed a numerical model based on the Immersed Boundary Method (IBM) to introduce an electrode having a complex geometry into a structured Cartesian mesh. The first results of the code will be discussed.

  17. Measurement of vibrationally excited N2(v) in an atmospheric-pressure air pulsed corona discharge using coherent anti-Stokes Raman scattering

    Science.gov (United States)

    Teramoto, Yoshiyuki; Ono, Ryo

    2014-08-01

    Vibrationally excited N2(v = 1, 2) in an atmospheric-pressure air pulsed corona discharge was measured using coherent anti-Stokes Raman scattering (CARS). In a dry air discharge, the vibrational temperature determined from the ratio N2(v = 2)/N2(v = 0), Tv2, was approximately 500 K higher than that determined from N2(v = 1)/N2(v = 0), Tv1, immediately after the discharge pulse. Both vibrational temperatures reached equilibrium within 100 μs after the discharge pulse by the vibration-to-vibration (V-V) process of N2-N2. The translational temperature was also measured using CARS. The rise in the translational temperature due to vibration-to-translation (V-T) energy transfer was not observed for a postdischarge time of 5 μs-1 ms in the dry-air discharge. However, when the air was humidified, a significant V-T energy transfer was observed. It was due to an extremely rapid V-T process of H2O-H2O following the V-V process of N2-H2O. Measurements showed that the humidification of the ambient air accelerated the decrease in the N2 vibrational temperature and increased the translational temperature. N2(v) was generated mostly in the secondary streamer, not in the primary one, according to estimation from the measured N2(v) density.

  18. On spatial stabilization of dielectric barrier discharge microfilaments by residual heat build-up in air

    Science.gov (United States)

    Ráhel, Jozef; Szalay, Zsolt; Čech, Jan; Morávek, Tomás

    2016-04-01

    Microfilaments of dielectric barrier discharge are known for their multiple re-appearance at the same spot on dielectrics. This effect of localized re-appearance is driven by residual excited species and ions, surface charge deposited on the dielectric and the local temperature build-up resulting in the local increase of reduced electric field E/ΔN. To assess the magnitude of the latter, the breakdown voltage vs. temperature up to 180 °C was carefully measured at coplanar DBD and used as an input into the numerical simulation of heat build-up by the train of discharge pulses. An average reduction of breakdown voltage was found to be 20 V/K. The model predicted a quasi-stable microfilament temperature into which the thermal build-up rapidly converges. Its magnitude agreed well with the reported rotational temperature of similar electrode configuration. The impact of quasi-stable temperature on microfilament formation dynamics is further discussed. Contribution to the Topical Issue "Recent Breakthroughs in Microplasma Science and Technology", edited by Kurt Becker, Jose Lopez, David Staack, Klaus-Dieter Weltmann and Wei Dong Zhu.

  19. Kinetic study on non-thermal volumetric plasma decay in the early afterglow of air discharge generated by a short pulse microwave or laser

    Science.gov (United States)

    Yang, Wei; Zhou, Qianhong; Dong, Zhiwei

    2016-08-01

    This paper reports a kinetic study on non-thermal plasma decay in the early afterglow of air discharge generated by short pulse microwave or laser. A global self-consistent model is based on the particle balance of complex plasma chemistry, electron energy equation, and gas thermal balance equation. Electron-ion Coulomb collision is included in the steady state Boltzmann equation solver to accurately describe the electron mobility and other transport coefficients. The model is used to simulate the afterglow of microsecond to nanosecond pulse microwave discharge in N2, O2, and air, as well as femtosecond laser filament discharge in dry and humid air. The simulated results for electron density decay are in quantitative agreement with the available measured ones. The evolution of plasma decay under an external electric field is also investigated, and the effect of gas heating is considered. The underlying mechanism of plasma density decay is unveiled through the above kinetic modeling.

  20. Optical and electrical characteristics of a single surface DBD micro-discharge produced in atmospheric-pressure nitrogen and synthetic air

    Science.gov (United States)

    Šimek, M.; Prukner, V.; Schmidt, J.

    2011-05-01

    Basic opto-electrical characteristics of a single micro-discharge generated in a surface DBD reactor with a coplanar electrode arrangement were studied with nanosecond time resolution. The discharge electrode geometry based on machinable glass-ceramic was optimized in order to get a system free of the circulating dielectric liquids that are frequently used to insulate and cool metallic electrodes. The build-up and decay of UV-vis-NIR emission by a single micro-discharge unaffected by concurrent or preceding discharge events was inspected during the first 10 µs of the micro-discharge evolution in nitrogen and in synthetic air. Obtained emission waveforms show a great similarity between the surface and volume streamers. The streamer volume-averaged N2(A) concentrations of ~8 × 1014 cm-3 were estimated at t = 1 µs decay time and concentrations of ~(2-4) × 1015 cm-3 were estimated during the streamer propagation phase in nitrogen.

  1. Dyeing mechanism and optimization of polyamide 6,6 functionalized with double barrier discharge (DBD) plasma in air

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Fernando Ribeiro [Departamento de Engenharia Têxtil, Universidade Federal do Rio Grande do Norte UFRN, 59.072-970 Natal (Brazil); Zille, Andrea, E-mail: azille@2c2t.uminho.pt [2C2T – Centro de Ciência e Tecnologia Têxtil, Departamento de Engenharia Têxtil, Universidade do Minho, 4800-058 Guimarães (Portugal); Souto, Antonio Pedro [2C2T – Centro de Ciência e Tecnologia Têxtil, Departamento de Engenharia Têxtil, Universidade do Minho, 4800-058 Guimarães (Portugal)

    2014-02-28

    The physico-chemical improvements occasioned by DBD plasma discharge in dyeing process of polyamide 6,6 (PA66) fibers were investigated. The SEM, fluorescence microscopy, UV–vis spectroscopy, surface energy, FTIR, XPS and pH of aqueous extracts confirm the high polar functionalization of PA66 fibers due to plasma incorporation of oxygen atoms from atmospheric air. DBD plasma-generated reactive species preferentially break the C-N bonds, and not the aliphatic C-C chain of PA66. Formation of low-molecular weight acidic molecules that act as dye “carrier” and creation of micro-channels onto PA66 surface seems to favor dye diffusion into the fiber cores. Plasma treatment allows high level of direct dye diffusion and fixation in PA66 fibers at lower temperatures and shorter dyeing times than traditional dyeing methods.

  2. Modeling of experimental treatment of acetaldehyde-laden air and phenol-containing water using corona discharge technique.

    Science.gov (United States)

    Faungnawakij, Kajornsak; Sano, Noriaki; Charinpanitkul, Tawatchai; Tanthapanichakoon, Wiwut

    2006-03-01

    Acetaldehyde-laden air and phenol-contaminated water were experimentally treated using corona discharge reactions and gas absorption in a single water-film column. Mathematical modeling of the combined treatment was developed in this work. Efficient removal of the gaseous acetaldehyde was achieved while the corona discharge reactions produced short-lived species such as O and O- as well as ozone. Direct contact of the radicals and ions with water was known to produce aqueous OH radical, which contributes to the decomposition of organic contaminants: phenol, absorbed acetaldehyde, and intermediate byproducts in the water. The influence of initial phenol concentration ranging from 15 to 50 mg L(-1) and that of influent acetaldehyde ranging from 0 to 200 ppm were experimentally investigated and used to build the math model. The maximum energetic efficiency of TOC, phenol, and acetaldehyde were obtained at 25.6 x 10(-9) mol carbon J(-1), 25.0 x 10(-9) mol phenol J(-1), and 2.0 x 10(-9) mol acetaldehyde J(-1), respectively. The predictions for the decomposition of acetaldehyde, phenol, and their intermediates were found to be in good agreement with the experimental results.

  3. Numerical simulations of compact intracloud discharges as the Relativistic Runaway Electron Avalanche-Extensive Air Shower process

    Science.gov (United States)

    Arabshahi, S.; Dwyer, J. R.; Nag, A.; Rakov, V. A.; Rassoul, H. K.

    2014-01-01

    Compact intracloud discharges (CIDs) are sources of the powerful, often isolated radio pulses emitted by thunderstorms. The VLF-LF radio pulses are called narrow bipolar pulses (NBPs). It is still not clear how CIDs are produced, but two categories of theoretical models that have previously been considered are the Transmission Line (TL) model and the Relativistic Runaway Electron Avalanche-Extensive Air Showers (RREA-EAS) model. In this paper, we perform numerical calculations of RREA-EASs for various electric field configurations inside thunderstorms. The results of these calculations are compared to results from the other models and to the experimental data. Our analysis shows that different theoretical models predict different fundamental characteristics for CIDs. Therefore, many previously published properties of CIDs are highly model dependent. This is because of the fact that measurements of the radiation field usually provide information about the current moment of the source, and different physical models with different discharge currents could have the same current moment. We have also found that although the RREA-EAS model could explain the current moments of CIDs, the required electric fields in the thundercloud are rather large and may not be realistic. Furthermore, the production of NBPs from RREA-EAS requires very energetic primary cosmic ray particles, not observed in nature. If such ultrahigh-energy particles were responsible for NBPs, then they should be far less frequent than is actually observed.

  4. 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.

  5. Validation of gas temperature measurements by OES in an atmospheric air glow discharge with water electrode using Rayleigh scattering

    Energy Technology Data Exchange (ETDEWEB)

    Verreycken, T; Van Gessel, A F H; Pageau, A; Bruggeman, P, E-mail: p.j.bruggeman@tue.n [Eindhoven University of Technology, Department of Applied Physics, PO Box 513, 5600 MB Eindhoven (Netherlands)

    2011-04-15

    Rayleigh scattering is used to determine the gas temperature of an atmospheric pressure dc excited glow discharge in air with a water electrode. The obtained temperatures are compared with calculated rotational temperatures measured by optical emission spectroscopy of OH(A-X) and N{sub 2}(C-B). At a current of 15 mA a deviation is found between T{sub rot}(OH) and the gas temperature obtained from Rayleigh scattering of about 1000 K. The gas temperatures obtained from Rayleigh scattering, N{sub 2}(C) and OH(A) in the positive column are, respectively, 2600 {+-} 100 K, 2700 {+-} 150 K and 3600 {+-} 200 K. It is shown that the rotational temperature of N{sub 2}(C) is a reliable measurement of the gas temperature while this is not the case for OH(A). The results are explained in the context of quenching processes of the excited states. Spatially resolved gas temperatures in both longitudinal and radial directions are presented. The observed strong temperature gradients near the electrodes are checked to be consistent with the power dissipation and the heat transfer in the discharge. The effect of the polarity of the water electrode and filamentation on the measured temperatures is discussed.

  6. Experimental study on surface modification of PET films under bipolar nanosecond-pulse dielectric barrier discharge in atmospheric air

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yunfei [State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710049 (China); Su, Chunqiang [Xi’an High Voltage Apparatus Research Institute, Xi’an 710077 (China); Ren, Xiang; Fan, Chuan; Zhou, Wenwu [State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710049 (China); Wang, Feng [School of Electrical and Information Engineering, Hunan University, Changsha 410082 (China); Ding, Weidong, E-mail: wdding@mail.xjtu.edu.cn [State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710049 (China)

    2014-09-15

    Highlights: • Homogeneous DBD is generated under bipolar nanosecond pulse in atmospheric air. • Effects of surface modification under homogeneous DBD are discussed. • Dielectric properties of the PET films are fully studied from relative dielectric constant ε{sub r}, dielectric loss tangent tan δ and breakdown voltages V{sub b}. • Oxygen-containing polar groups are considered to be the most essential reason for dielectric property changes. - Abstract: Dielectric barrier discharge (DBD) is widely used for surface modification of polymer films. In this paper, DBD characteristics under bipolar repetitive frequency nanosecond pulse in atmospheric air are studied and surface properties of polyethylene terephthalate films under homogeneous DBD and filamentary DBD modification are compared through scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and dielectric test equipment. It is found that the discharge is homogeneous when gap spacing d is less than 1.2 mm and filamentary when d is within the range of 3.0 mm to 5.8 mm. SEM pictures reveal that films under homogeneous DBD present a smooth surface while intensive “gully-like” etches appear on the surface of the films under filamentary DBD, which can result in local insulation defects and is disadvantageous to surface modification. It is found from the XPS analysis that a number of oxygen-containing polar groups are introduced onto the surface of the film modified by homogeneous DBD compared with the untreated one. Experimental results for dielectric properties indicate that the three parameters: relative dielectric constant ε{sub r}, dielectric loss tangent tan δ and breakdown voltages V{sub b} are all changed in different degree after surface modification. And possible reason for the phenomenon is discussed.

  7. Sub-nanosecond time resolved light emission study for diffuse discharges in air under steep high voltage pulses

    Science.gov (United States)

    Tardiveau, P.; Magne, L.; Marode, E.; Ouaras, K.; Jeanney, P.; Bournonville, B.

    2016-10-01

    Pin-to-plane discharges in centimetre air gaps and standard conditions of pressure and temperature are generated under very high positive nanosecond scale voltage pulses. The experimental study is based on recordings of sub-nanosecond time resolved and Abel-processed light emission profiles and their complete correlation to electrical current waveforms. The effects of the voltage pulse features (amplitude between 20 and 90 kV, rise time between 2 and 5.2 ns, and time rate between 4 and 40 kV · ns‑1) and the electrode configuration (gap distance between 10 and 30 mm, pin radius between 10 and 200 µm, copper, molybdenum or tungsten pin material) are described. A three time period development can be found: a glow-like structure with monotonic light profiles during the first 1.5 ns whose size depends on time voltage rate, a shell-like structure with bimodal profiles whose duration and extension in space depends on rise time, and either diffuse or multi-channel regime for the connection to the cathode plane according to gap distance. The transition of the light from monotonic to bimodal patterns reveals the relative effects and dynamics of streamer space charge and external laplacian field. A classical 2D-fluid model for streamer propagation has been used and adapted for very high and steep voltage pulses. It shows the formation of a strong space charge (streamer) very close to the pin, but also a continuity of emission between the pin and the streamer, and electric fields higher than the critical ionization field (28 kV · cm‑1 in air) almost in the whole gap and very early in the discharge propagation.

  8. Investigation of Space-Time Structure of the Discharge with an Electrolytic Anode and Face-Type, Air Half-Space Directed Cathode (Gatchina's Discharge)

    CERN Document Server

    Emelin, S E; Pirozerski, A L

    2008-01-01

    Despite of its limited capabilities for ball-lightning modeling, the chemically active dust plasma of electric discharges is a very interesting physical object. Gatchina's discharge, which gives a possibility to study the dust-gas fireball, represents a complex non-stationary process, combining the creation and the destruction of relatively long-living high-enthalpy microscopic states with non-ideal dust plasma and with a gas-dynamic form, resulting in appearance of a spherical luminous object. In the present work we studied spatial structure of the discharge and its dynamics with the help of electric and optical measurements.

  9. Antenna Deployment for the Localization of Partial Discharges in Open-Air Substations

    Directory of Open Access Journals (Sweden)

    Guillermo Robles

    2016-04-01

    Full Text Available Partial discharges are ionization processes inside or on the surface of dielectrics that can unveil insulation problems in electrical equipment. The charge accumulated is released under certain environmental and voltage conditions attacking the insulation both physically and chemically. The final consequence of a continuous occurrence of these events is the breakdown of the dielectric. The electron avalanche provokes a derivative of the electric field with respect to time, creating an electromagnetic impulse that can be detected with antennas. The localization of the source helps in the identification of the piece of equipment that has to be decommissioned. This can be done by deploying antennas and calculating the time difference of arrival (TDOA of the electromagnetic pulses. However, small errors in this parameter can lead to great displacements of the calculated position of the source. Usually, four antennas are used to find the source but the array geometry has to be correctly deployed to have minimal errors in the localization. This paper demonstrates, by an analysis based on simulation and also experimentally, that the most common layouts are not always the best options and proposes a simple antenna layout to reduce the systematic error in the TDOA calculation due to the positions of the antennas in the array.

  10. Antenna Deployment for the Localization of Partial Discharges in Open-Air Substations

    Science.gov (United States)

    Robles, Guillermo; Fresno, José Manuel; Sánchez-Fernández, Matilde; Martínez-Tarifa, Juan Manuel

    2016-01-01

    Partial discharges are ionization processes inside or on the surface of dielectrics that can unveil insulation problems in electrical equipment. The charge accumulated is released under certain environmental and voltage conditions attacking the insulation both physically and chemically. The final consequence of a continuous occurrence of these events is the breakdown of the dielectric. The electron avalanche provokes a derivative of the electric field with respect to time, creating an electromagnetic impulse that can be detected with antennas. The localization of the source helps in the identification of the piece of equipment that has to be decommissioned. This can be done by deploying antennas and calculating the time difference of arrival (TDOA) of the electromagnetic pulses. However, small errors in this parameter can lead to great displacements of the calculated position of the source. Usually, four antennas are used to find the source but the array geometry has to be correctly deployed to have minimal errors in the localization. This paper demonstrates, by an analysis based on simulation and also experimentally, that the most common layouts are not always the best options and proposes a simple antenna layout to reduce the systematic error in the TDOA calculation due to the positions of the antennas in the array. PMID:27092501

  11. Mid-section of a can-annular gas turbine engine with a radial air flow discharged from the compressor section

    Energy Technology Data Exchange (ETDEWEB)

    Little, David A.; McQuiggan, Gerard; Wasdell, David L.

    2016-10-25

    A midframe portion (213) of a gas turbine engine (210) is presented, and includes a compressor section (212) configured to discharge an air flow (211) directed in a radial direction from an outlet of the compressor section (212). Additionally, the midframe portion (213) includes a manifold (214) to directly couple the air flow (211) from the compressor section (212) outlet to an inlet of a respective combustor head (218) of the midframe portion (213).

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

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Ujjwal Man, E-mail: umjoshi@gmail.com; Subedi, Deepak Prasad, E-mail: deepaksubedi2001@yahoo.com [Department of Natural Sciences (Physics), School of Science, Kathmandu University P. O. Box No. 6250, Dhulikhel, Kathmandu, Nepal (India)

    2015-07-31

    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 (H{sub 2}O), glycerol (C{sub 3}H{sub 8}O{sub 3}) and diiodomethane (CH{sub 2}I{sub 2}) 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.

  13. [Toxicological and sanitary evaluation of air pollution by substances discharged during managing of urban dumping soil].

    Science.gov (United States)

    Prostakishin, G P; Osin, O M; Ivashina, L I; Markin, A A; Ivanova, I N; Gazie v, G A; Sotnikov, E E; Volkov, N N

    2001-01-01

    The paper presents the results of sanitary and hygienic investigations whose reason was the situation established with the removal of dumping earth in the dwelling area of Mitino Microdistrict 8 gamma. The removed dumping earth found to have formaldehyde, benzenes, acetaldehyde, phenols, aromatic hydro carbons, polyaromatic compounds was a source of bad smelling substances that had entered the ambient air. A special study of the earth showed that it might yield volatile and bad smelling compounds, such as organic sulfides, aldehydes, mercaptans, ketones, etc. Their harmful health effects (during operations and in the late period) seem to be unlikely. When such work is under way, it is necessary to inform the population about possible consequences.

  14. Two-color interferometer for the study of laser filamentation triggered electric discharges in air

    CERN Document Server

    Point, Guillaume; Arantchouk, Leonid; Carbonnel, Jérôme; Prade, Bernard; Mysyrowicz, André; Houard, Aurélien

    2014-01-01

    We present a space and time resolved interferometric plasma diagnostic for use on plasmas where neutral-bound electron contribution to the refractive index cannot be neglected. By recording simultaneously the plasma optical index at 532 and 1064 nm, we are able to extract independently the neutral and free electron density profiles. We report a phase resolution of 30 mrad, corresponding to a maximum resolution on the order of $4\\times10^{23}~\\mathrm{m}^{-3}$ for the electron density, and of $10^{24} ~ \\mathrm{m}^{-3}$ for the neutral density. The interferometer is demonstrated on centimeter-scale sparks triggered by laser filamentation in air with typical currents of a few tens of A.

  15. Estimation of Minimal Breakdown Point in a GaP Plasma Structure and Discharge Features in Air and Argon Media

    Science.gov (United States)

    Kurt, H. Hilal; Tanrıverdi, Evrim

    2016-08-01

    We present gas discharge phenomena in argon and air media using a gallium phosphide (GaP) semiconductor and metal electrodes. The system has a large-diameter ( D) semiconductor and a microscaled adjustable interelectrode gap ( d). Both theoretical and experimental findings are discussed for a direct-current (dc) electric field ( E) applied to this structure with parallel-plate geometry. As one of the main parameters, the pressure p takes an adjustable value from 0.26 kPa to 101 kPa. After collection of experimental data, a new theoretical formula is developed to estimate the minimal breakdown point of the system as a function of p and d. It is proven that the minimal breakdown point in the semiconductor and metal electrode system differs dramatically from that in metal and metal electrode systems. In addition, the surface charge density σ and spatial electron distribution n e are calculated theoretically. Current-voltage characteristics (CVCs) demonstrate that there exist certain negative differential resistance (NDR) regions for small interelectrode separations (i.e., d = 50 μm) and low and moderate pressures between 3.7 kPa and 13 kPa in Ar medium. From the difference of currents in CVCs, the bifurcation of the discharge current is clarified for an applied voltage U. Since the current differences in NDRs have various values from 1 μA to 7.24 μA for different pressures, the GaP semiconductor plasma structure can be used in microwave diode systems due to its clear NDR region.

  16. 24 CFR 3280.611 - Vents and venting.

    Science.gov (United States)

    2010-04-01

    ... Case Iron Soil Pipe and Fittings, or, Silicone Rubber, Low and High Temperature and Tear Resistant... 24 Housing and Urban Development 5 2010-04-01 2010-04-01 false Vents and venting. 3280.611 Section 3280.611 Housing and Urban Development Regulations Relating to Housing and Urban Development...

  17. 双机抬吊放空火炬塔架及空中组对%Application of double crane lifting and air assembly technique in venting and flare stack tower

    Institute of Scientific and Technical Information of China (English)

    蒋晓灵; 席明; 王开云; 刘乐意

    2009-01-01

    The venting and flare stack tower at the LG Natural Gas Treatment Plant is high, large and heavy. The application of traditional lifting techniques will result in longer construction period, higher costs and risks. To place the venting and flare stack tower in position in an economical, secure and speedy way, this paper analyzed several lifting schemes and made a comparison between them. Finally, the segment lifting process, so-called "double crane lifting and single crane tailing", and air assembly process were adopted. A 300-ton and a 260-ton crawler cranes were selected as the main hoisting cranes, whilst a 65-ton crane truck was selected as the tailing hoisting crane. The flare stack tower was successfully placed in position within 24 hours. The results show that the hoisting technique is capable of ensuring construction quality, reducing hoisting risks, greatly saving the lifting costs and reducing the project period. This technique has certain reference value to other relevant projects.%川渝气区某天然气净化厂工程放空火炬塔架高、大、重,若采用传统的吊装工艺则工期长、成本高、风险大.为了经济、安全、快速地将放空火炬塔架吊装就位,通过对多种吊装方案的对比分析论证,最终确定采取"双机抬吊、单机溜尾"分段吊装、空中组对的吊装新工艺:主吊吊车选用1台300 t履带吊和1台260 t履带吊,溜尾吊车为1台65 t汽车吊,历时24 h一次性成功地将火炬塔架吊装就位.工程实践证明:该吊装工艺既确保了塔架的施工质量、降低了吊装风险,又极大地节约了吊装成本,缩短了吊装工期,对相关工程具有一定的借鉴意义.

  18. The influence of the sand-dust environment on air-gap breakdown discharge characteristics of the plate-to-plate electrode

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The experiments of plane-plane gap discharge was carried out in an environment of artificial sandstorm. By comparing and analyzing the differences in gap breakdown voltage between the sand & dust environment and clean air, some problems were investigated, such as effects of wind speed and particle concentration on the breakdown voltage, differences of gap discharge characteristics between the dust & sand medium and the clean air medium. The results showed that compared with the clean air environment, the dust & sand environment had a decreased gap breakdown voltage. The longer the gap distance, the greater the voltage drop; the breakdown voltage decreased with the increase of particle concentration in flow. With the increase of wind speed, the breakdown voltage decreased at the beginning and rose afterwards. The results of the paper may helpful for further research regarding the unidentified flashover and external insulation characteristics of the HV power grid in the dust & sand environment.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kuzminova, Anna [Department of Macromolecular Physics, Faculty of Mathematics and Physics, Charles University, V Holešovickách 2, 180 00 Praha 8 (Czech Republic); Vandrovcová, Marta [Institute of Physiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20 Prague 4 (Czech Republic); Shelemin, Artem [Department of Macromolecular Physics, Faculty of Mathematics and Physics, Charles University, V Holešovickách 2, 180 00 Praha 8 (Czech Republic); Kylián, Ondřej, E-mail: ondrej.kylian@gmail.com [Department of Macromolecular Physics, Faculty of Mathematics and Physics, Charles University, V Holešovickách 2, 180 00 Praha 8 (Czech Republic); Choukourov, Andrei; Hanuš, Jan [Department of Macromolecular Physics, Faculty of Mathematics and Physics, Charles University, V Holešovickách 2, 180 00 Praha 8 (Czech Republic); Bačáková, Lucie [Institute of Physiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20 Prague 4 (Czech Republic); Slavínská, Danka; Biederman, Hynek [Department of Macromolecular Physics, Faculty of Mathematics and Physics, Charles University, V Holešovickách 2, 180 00 Praha 8 (Czech Republic)

    2015-12-01

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

  20. Study on structural, morphological and thermal properties of surface modified polyvinylchloride (PVC) film under air, argon and oxygen discharge plasma

    Science.gov (United States)

    Suganya, Arjunan; Shanmugavelayutham, Gurusamy; Serra Rodríguez, Carmen

    2016-09-01

    The effect of air, argon, oxygen DC glow discharge plasma on the polyvinylchloride (PVC) film synthesized by solution casting technique, were evaluated via changes in physio-chemical properties such as structural, morphological, crystalline, thermal properties. The PVC film was plasma treated as a function of exposure time and different plasma forming gases, while other operating parameters such as power and pressure remained constant at 100 W and 2 Pa respectively. The plasma treated PVC were characterized by static contact angle, ATR-FTIR, XPS, AFM and T-peel analysis. It was found that various gaseous plasma treatments have improved the polar components, surface roughness on the surface of PVC which was confirmed by XPS, AFM, resulting in highly enhanced wettability and adhesion. X-ray diffraction study showed that plasma treatment does not persuade considerable change, even though it vaguely induces the crystallinity. The thermal properties of plasma treated PVC were evaluated by Differential Scanning Calorimetry and it was observed that O2 plasma treatment gives higher glass transition temperature of 87.21 °C compared with the untreated one. The glass transition temperature slightly increased for Oxygen plasma treated material due to the presence of higher concentration of the polar functional groups on the PVC surface due to strong intramolecular bonding.

  1. Functionalization of Hydrogen-free Diamond-like Carbon Films using Open-air Dielectric Barrier Discharge Atmospheric Plasma Treatments

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Instituto de Materiales de Madrid, C.S.I.C., Cantoblanco, 28049 Madrid, Spain; Instituto de Quimica-Fisica" Rocasolano" C.S.I.C., 28006 Madrid, Spain; Mahasarakham University, Mahasarakham 44150, Thailand; CASTI, CNR-INFM Regional Laboratory, L' Aquila 67100, Italy; SUNY Upstate Medical University, Syracuse, NY 13210, USA; Endrino, Jose; Endrino, J. L.; Marco, J. F.; Poolcharuansin, P.; Phani, A.R.; Allen, M.; Albella, J. M.; Anders, A.

    2007-12-28

    A dielectric barrier discharge (DBD) technique has been employed to produce uniform atmospheric plasmas of He and N2 gas mixtures in open air in order to functionalize the surface of filtered-arc deposited hydrogen-free diamond-like carbon (DLC) films. XPS measurements were carried out on both untreated and He/N2 DBD plasma treated DLC surfaces. Chemical states of the C 1s and N 1s peaks were collected and used to characterize the surface bonds. Contact angle measurements were also used to record the short- and long-term variations in wettability of treated and untreated DLC. In addition, cell viability tests were performed to determine the influence of various He/N2 atmospheric plasma treatments on the attachment of osteoblast MC3T3 cells. Current evidence shows the feasibility of atmospheric plasmas in producing long-lasting variations in the surface bonding and surface energy of hydrogen-free DLC and consequently the potential for this technique in the functionalization of DLC coated devices.

  2. Application of Dielectric-Barrier Discharge to the Stabilization of Lifted Non-Premixed Methane/Air Jet Flames

    Science.gov (United States)

    Liao, Ying-Hao; Zhao, Xiang-Hong

    2016-11-01

    Recent studies have shown that the application of non-thermal plasma is a promising way to enhance the flame stabilization and combustion efficiency. The present study experimentally investigates the effect of a dielectric-barrier discharge (DBD) on the stabilization of lifted non-premixed methane/air jet flames. The jet flame with co-annular DBD is produced by a co-flow burner and has a Reynolds number of Re = 2500, 5000, 7000, and 9000. The application of DBD is seen to have an impact on the flame lift-off height, and the degree of impact is subject to flow conditions (such as Reynolds number and co-flow velocity) and plasma power. In general, the enhancement of flame stabilization, indicated by the decrease in lift-off height, is most evident at low Reynolds number and co-flow velocity. For flames with a Reynolds number less than Re = 5000, flames are attached to the nozzle regardless of the co-flow velocity and plasma power; at Re = 5000, flames are often intermittently attached. The enhancement is not that significant at high Reynolds number and co-flow velocity at least for the plasma power employed in the current study. A slight increase in plasma power leads to enhanced flame stabilization.

  3. Communication: The influence of CO2 poisoning on overvoltages and discharge capacity in non-aqueous Li-Air batteries

    Science.gov (United States)

    Mekonnen, Yedilfana S.; Knudsen, Kristian B.; Mýrdal, Jon S. G.; Younesi, Reza; Højberg, Jonathan; Hjelm, Johan; Norby, Poul; Vegge, Tejs

    2014-03-01

    The effects of Li2CO3 like species originating from reactions between CO2 and Li2O2 at the cathode of non-aqueous Li-air batteries were studied by density functional theory (DFT) and galvanostatic charge-discharge measurements. Adsorption energies of CO2 at various nucleation sites on a stepped ({1bar 100}) Li2O2 surface were determined and even a low concentration of CO2 effectively blocks the step nucleation site and alters the Li2O2 shape due to Li2CO3 formation. Nudged elastic band calculations show that once CO2 is adsorbed on a step valley site, it is effectively unable to diffuse and impacts the Li2O2 growth mechanism, capacity, and overvoltages. The charging processes are strongly influenced by CO2 contamination, and exhibit increased overvoltages and increased capacity, as a result of poisoning of nucleation sites: this effect is predicted from DFT calculations and observed experimentally already at 1% CO2. Large capacity losses and overvoltages are seen at higher CO2 concentrations.

  4. What matters most: Are summer stream temperatures more sensitive to changing air temperature, changing discharge, or changing riparian vegetation under future climates?

    Science.gov (United States)

    Diabat, M.; Haggerty, R.; Wondzell, S. M.

    2012-12-01

    We investigated stream temperature responses to changes in both air temperature and stream discharge projected for 2040-2060 from downscaled GCMs and changes in the height and canopy density of streamside vegetation. We used Heat Source© calibrated for a 37 km section of the Middle Fork John Day River located in Oregon, USA. The analysis used the multiple-variable-at-a-time (MVAT) approach to simulate various combinations of changes: 3 levels of air warming, 5 levels of stream flow (higher and lower discharges), and 6 types of streamside vegetation. Preliminary results show that, under current discharge and riparian vegetation conditions, projected 2 to 4 °C increase in air temperature will increase the 7-day Average Daily Maximum Temperature (7dADM) by 1 to 2 °C. Changing stream discharge by ±30% changes stream temperature by ±0.5 °C, and the influence of changing discharge is greatest when the stream is poorly shaded. In contrast, the 7dADM could change by as much as 11°C with changes in riparian vegetation from unshaded conditions to heavily shaded conditions along the study section. The most heavily shaded simulations used uniformly dense riparian vegetation over the full 37-km reach, and this vegetation was composed of the tallest trees and densest canopies that can currently occur within the study reach. While this simulation represents an extreme case, it does suggest that managing riparian vegetation to substantially increase stream shade could decrease 7dADM temperatures relative to current temperatures, even under future climates when mean air temperatures have increased from 2 to 4 °C.

  5. Nitric oxide PLIF measurement in a point-to-plane pulsed discharge in vitiated air of a propane/air flame

    Science.gov (United States)

    Schmidt, J. B.; Jiang, N.; Ganguly, B. N.

    2014-12-01

    The effect of a point-to-plane pulsed discharge on the vitiated downstream of a propane/air flame has been investigated by phase-locked NO planar laser-induced-fluorescence (PLIF) measurements. Phase-locked NO PLIF measurements with the variation of pulsed plasma energy, equivalence ratio and applied voltage rise time have been performed. Fast rise time (25 ns) and slower rise time (150 ns) high-voltage pulsers are used to produce NO radical densities greater than the ambient flame-produced NO radicals in lean, balanced and rich premixed flames. The pulsed plasma produced excess NO radical densities were found to decay to 50% level with time constants greater than 250 µs in the burnt gas regions with gas temperatures greater than 1000 K. The super-equilibrium NO populations were dependent on energy deposited and overall equivalence ratio, but independent of voltage pulse rise time for similar energy deposition per pulse. Due to long NO radical density decay lifetimes, super-equilibrium NO populations are convected away from production regions with the ambient flow and observed in downstream exhaust gas regions.

  6. Changes in the electro-physical properties of MCT epitaxial films affected by a plasma volume discharge induced by an avalanche beam in atmospheric-pressure air

    Science.gov (United States)

    Grigoryev, D. V.; Voitsekhovskii, A. V.; Lozovoy, K. A.; Tarasenko, V. F.; Shulepov, M. A.

    2015-11-01

    In this paper the influence of the plasma volume discharge of nanosecond duration formed in a non-uniform electric field at atmospheric pressure on samples of epitaxial films HgCdTe (MCT) films are discussed. The experimental data show that the action of pulses of nanosecond volume discharge in air at atmospheric pressure leads to changes in the electrophysical properties of MCT epitaxial films due to formation of a near-surface high- conductivity layer of the n-type conduction. The preliminary results show that it is possible to use such actions in the development of technologies for the controlled change of the properties of MCT.

  7. Suppression effect of CO2-twin fluid water mist on methane/air explosion in vented duct%CO2-双流体细水雾抑制管道甲烷爆炸实验

    Institute of Scientific and Technical Information of China (English)

    裴蓓; 余明高; 陈立伟; 杨勇; 牛攀; 朱新娜

    2016-01-01

    搭建了尺寸为120 mm×120 mm×840 mm 透明有机玻璃瓦斯爆炸管道实验平台,采用双流体喷嘴将二氧化碳和细水雾送入实验系统,从火焰速度、瓦斯爆炸超压两个方面探讨双流体细水雾的抑爆有效性。实验结果表明CO2双流体细水雾抑制瓦斯爆炸效果显著。随着喷雾时间的延长,火焰传播速度呈缓慢增加趋势,火焰传播速度峰值大幅降低;爆炸超压曲线呈先增大后缓慢减小的趋势,超压峰值大幅降低;当 CO2压力增至0.4 MPa 喷雾时间大于3 s 时,经多次点火无法引爆,说明 CO2-双流体细水雾抑制甲烷爆炸时具有协同效应,有利于提高细水雾的抑爆效率。%The experimental study on the synergistic suppression effect of carbon dioxide and ultrafine water mist on stoichiometric premixed methane/air mixture in a vented duct was carried out in this paper. The ultrafine water mist was generated from a twin fluid nozzle. The results indicated that CO2 and water mist had a synergistic suppression effect on methane/air explosion and the efficiency of explosion suppression was significantly improved. With the increase of mist spraying time, the peak flame propagation speed and peak overpressure decreased obviously. When the pressure of CO2 increased to 0.4 MPa and mist spraying time was more than 3 s, the methane/air mixture cannot be detonated after several times of ignition. It was beneficial to improve the explosion suppression efficiency of water mist.

  8. Neutral gas temperature maps of the pin-to-plate Argon micro discharge into the ambient air

    CERN Document Server

    Xu, Shaofeng; Majeed, Asif

    2015-01-01

    This study is designed to explore the two dimensional temperature maps of the atmospheric argon discharge consisting of pin-to-plane electrodes supplied by a high voltage DC source. After checking the stability of the micro discharge, the two dimensional image plane focused by a quartz lens was scanned by the fiber probe driven by a 3D Mobile Platform. The rotational and vibrational temperatures are calculated using nitrogen emissions collected by the high resolution spectrometer and high sensitive intensified charge coupled device (ICCD). The rotational temperature varies from 1558.15 K to 2621.14 K and vibrational temperature varies from 3010.38 K to 3774.69 K, indicating a great temperature gradient due to small discharge size. The temperature maps show a lateral expansion and a sharp truncation in the radial direction. A double layers discharge is identified, where an arc discharge coats the glow discharge.

  9. Macrofauna of shallow hydrothermal vents on the Arctic Mid-Ocean Ridge at 71N

    Science.gov (United States)

    Schander, C.; Rapp, H. T.; Pedersen, R. B.

    2007-12-01

    Deep-sea hydrothermal vents are usually associated with a highly specialized fauna and since their discovery in 1977, more than 400 species of animals have been described. Specialized vent fauna includes various animal phyla, but the most conspicuous and well known are annelids, mollusks and crustaceans. We have investigated the fauna collected around newly discovered hydrothermal vents on the Mohns Ridge north of Jan Mayen. The venting fields are located at 71°N and the venting takes place within two main areas separated by 5 km. The shallowest vent area is at 500-550 m water depth and is located at the base of a normal fault. This vent field stretches approximately 1 km along the strike of the fault, and it is composed of 10-20 major vent sites each with multiple chimney constructions discharging up to 260°C hot fluids. A large area of diffuse, low- temperature venting occurs in the area surrounding the high-temperature field. Here, partly microbial mediated iron-oxide-hydroxide deposits are abundant. The hydrothermal vent sites do not show any high abundance of specialized hydrothermal vent fauna. Single groups (i.e. Porifera and Mollusca) have a few representatives but groups otherwise common in hydrothermal vent areas (e.g. vestimentifera, Alvinellid worms, mussels, clams, galathaeid and brachyuran crabs) are absent. Up until now slightly more than 200 species have been identified from the vent area. The macrofauna found in the vent area is, with few exceptions, an assortment of bathyal species known in the area. One endemic, yet undescribed, species of mollusc has been found so far, an gastropod related to Alvania incognita Warén, 1996 and A. angularis Warén, 1996 (Rissoidae), two species originally described from pieces of sunken wood north and south of Iceland. It is by far the most numerous mollusc species at the vents and was found on smokers, in the bacterial mats, and on the ferric deposits. A single specimen of an undescribed tanaidacean has also

  10. Vente d'artisanat

    CERN Multimedia

    Staff Associaiton

    2014-01-01

      Éducation et Libération Vente d’artisanat du Tiers Monde Mardi 22 et mercredi 23 avril 2014 CERN, Bâtiment principal Togo, École Arc en ciel, construction des salles de classe. Appel pour le financement de ce chantier afin de libérer l’école de la charge des loyers payés pendant des années. Après nos réalisations en Amérique latine et au Bénin, nous mobilisons nos efforts pour l’école Arc en ciel de Kpémé, au Togo, sur les bords de l’Océan, à mi-chemin entre Lomé et la frontière entre le Bénin et le Togo. Il s’agit d’une école primaire privée, laïque qui a très bonne réputation en termes de résultats, notamment pour les écoliers en fin de scolar...

  11. Cement penetration after patella venting.

    Science.gov (United States)

    Jones, Christopher W; Lam, Li-On; Butler, Adam; Wood, David J; Walsh, William R

    2009-01-01

    There is a high rate of patellofemoral complications following total knee arthroplasty. Optimization of the cement-bone interface by venting and suction of the tibial plateau has been shown to improve cement penetration. Our study was designed to investigate if venting the patella prior to cementing improved cement penetration. Ten paired cadaver patellae were allocated prior to resurfacing to be vented or non-vented. Bone mineral density (BMD) was measured by DEXA scanning. In vented specimens, a 1.6 mm Kirschner wire was used to breach the anterior cortex at the center. Specimens were resurfaced with standard Profix instrumentation and Versabond bone cement (Smith and Nephew PLC, UK). Cement penetration was assessed from Faxitron and sectioned images by a digital image software package (ImageJ V1.38, NIH, USA). Wilcoxon rank sum test was used to assess the difference in cement penetration between groups. The relationship between BMD and cement penetration was analyzed by Pearson correlation coefficient. There was a strong negative correlation between peak BMD and cement penetration when analyzed independent of experimental grouping (r(2)=-0.812, p=0.004). Wilcoxon rank sum testing demonstrated no significant difference (rank sum statistic W=27, p=0.579) in cement penetration between vented (10.53%+/-4.66; mean+/-std dev) and non-vented patellae (11.51%+/-6.23; mean+/-std dev). Venting the patella using a Kirschner wire does not have a significant effect on the amount of cement penetration achieved in vitro using Profix instrumentation and Versabond cement.

  12. Study of the impact of photoionization on negative and positive needle-plane corona discharge in atmospheric air

    Science.gov (United States)

    Dordizadeh, Peyman; Adamiak, Kazimierz; Castle, G. S. Peter

    2016-12-01

    A 2D axisymmetric model of the atmospheric pressure needle-plane corona discharge incorporating the photoionization phenomenon is presented in this paper. The photoionization model was developed using a three-term exponential approximation based on a model suggested by Bourdon et al. The coefficients of the photoionization model were tuned by reproducing the results of a positive corona discharge and comparing them with the experimental data published previously in the literature. In fact, this photoionization model is an essential module for studying a self-sustained positive corona discharge. Incorporating the photoionization phenomenon in the numerical model for the negative corona discharge causes an average of 5% increase in both the frequency and the DC current of the discharge. The relative importance of the photoionization in both positive and negative coronas was put in a quantitative frame by introducing the ratio of the integral of the impact ionization source term (IIS) divided by the Integral of the photoionization source term (IPS). With the help of this ratio and the spatial distribution of the two source terms, the minor role played by the photoionization source term for the negative discharge is justified. In the case of the positive discharge, the vital importance of the photoionization for sustaining the discharge is explained. Moreover, for the negative corona discharge, comparison of the ratio of the secondary emitted electrons (SEE) from the cathode surface divided by the IPS, at different instants of the formation of a Trichel pulse was found to be beneficial for the purpose of evaluating the relative importance of the photoionization. It is concluded that, although SEE on the rising edge of the Trichel pulse is smaller than the IPS since the injected electrons from the cathode surface are generated in the area with the strongest electric field, they have a greater contribution to the discharge current.

  13. 空气中电晕放电与绝缘液体中流注放电的测量和分析%Time Sequential and Phase-resolved Measurement and Analysis of Corona Discharge in Air and Streamer Discharge in Insulating Liquid

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Insulation is one of the most important parts in a high voltage equipment. There are gaseous, liquid and solid insulations which are commonly used. In a high voltage transformer for example the insulating materials are all used. During operation of a high voltage equipment high electric stress may occur. Under extreme condition failure of the insulation may take place. Excessive electric field in air may cause corona discharges while in liquid insulation discharges may take place in the form of streamer. This paper reports experimental results on the corona and streamer discharges in air and silicone oil. The discharges were artificially generated around a needle tip in a needle-plane electrode system with gap length of 4 mm under sinusoidal and triangular voltages. The needle was made of steel with tip radius of 3 μm and curvature angle of 30°. The needle was made by Ogura Jewelry. The discharge pulses were measured using personal-computer based partial discharge (PD) measurement system with sensitivity of better than 0.5 pC. The system is able to measure discharge in time sequential. Phase-resolved analysis of the discharges was done to interpret the physical processes behind the discharges. The experimental results showed that corona discharges took place at negative half cycles. The discharges were concentrated around 270° of phase angle of applied voltage. The discharge magnitude and discharge number of corona clearly dependent on the instantaneous of applied voltage. These were strongly supported by the application of triangular voltage. Streamer discharges occurred at both positive and negative half cycles. The discharges pulses concentrated around the peak of applied voltage at phase angle of 90° and 270°. Experimental results under sinusoidal and triangular voltages revealed that streamer discharge magnitude as well as probability of occurrence was strongly dependent on the instantaneous applied voltage.

  14. Student Award Finalist - Simulation of the reignition of atmospheric pressure air discharges behind dielectric obstacles: comparison with experiments

    Science.gov (United States)

    Pechereau, Francois; Bourdon, Anne

    2013-09-01

    In recent years, experimental studies on plasma assisted catalysis for flue gas treatment have shown a significant reduction of pollutants at a low energetic cost. Catalyst supports are either random or organized two phase media such as pellets, monoliths or porous media. Then, in plasma reactors, atmospheric pressure discharges have to interact with many obstacles and to propagate in microcavities and pores. To better understand the discharge dynamics in these complex structures, experiments have been carried out at LPGP (Orsay, France) in a point-to-plane geometry with a dielectric plane obstacle placed in the discharge path. In this work, we have carried out discharge simulations in the experimental geometry. We have compared the dynamics of the discharge ignited at the point and its impact on the dielectric surface. Then, we have compared the conditions of a discharge reignition behind the dielectric obstacle. A good qualitative agreement with experiments has been obtained but to improve the quantitative comparison, we have carried out a detailed parametric numerical study. In this work, we will focus on the influence of the level of seed charges on the discharge reignition and discuss several physical processes that could have an impact on the level of seed charges. ALVEOPLAS project (Grant No. ANR-08-BLAN-0159-01).

  15. Technology Solutions Case Study: Design Guidance for Passive Vents in New Construction, Multifamily Buildings

    Energy Technology Data Exchange (ETDEWEB)

    None

    2016-02-12

    In an effort to improve indoor air quality in high-performance, new construction, multifamily buildings, dedicated sources of outdoor air are being implemented. Passive vents are being selected by some design teams over other strategies because of their lower first costs and operating costs. The U.S. Department of Energy’s Building America research team Consortium for Advanced Residential Buildings constructed eight steps, which outline the design and commissioning required for these passive vents to perform as intended.

  16. A study to investigate the fluid properties of fuel-vapour/air-mixtures of an automotive fuel system during refuelling. Determination of air-content, density and dynamic viscosity of the vapour-mixture in the venting of automotive fuel tanks during refuelling; Untersuchungen zur Bestimmung der Fluideigenschaften von Kraftstoffdampf-Luft-Gemischen von Kraftfahrzeuganlagen waehrend der Betankung. Bestimmung des Luftanteils, der Dichte und der dynamischen Viskositaet des Gasgemisches in der Entlueftung eines Kraftfahrzeugtanks waehrend der Betankung

    Energy Technology Data Exchange (ETDEWEB)

    Geurtz, Heinz-Juergen [Porsche AG, Weissach (Germany)

    2011-09-15

    This study investigates the methods of calculating the fluid-dynamic properties of fuel-vapour/air-mixtures. It aims to determine models for the calculation of the dynamic viscosity and density of these fuel-vapour/air-mixtures. For this purpose, fuels were analyzed. The data received were collected in a database which was complemented with the temperature-dependent vapour-pressures and dynamic viscosity-properties. Experiments were conducted in order to determine the air-content in the vapour venting from a fuel system during refueling. Based on these data conclusions can be drawn on the composition of the liquid fuel, which allows the assessment of the fuel-vapour and its properties. The results received were subsequently used to develop parametric models for the calculation of the average molecular weight, density and dynamic viscosity of fuel-vapour/air-mixtures. (orig.)

  17. Numerical Simulation Study on Wave Dissipating Performances of Air Bubbles Breakwater with Single & Double Air Discharge Pipes%单排与双排气幕防波堤消波性能数值模拟

    Institute of Scientific and Technical Information of China (English)

    张成兴; 王永学; 马加

    2011-01-01

    将气液两相流看成是变密度单流体,以连续方程、雷诺平均方程和k-ε模型为控制方程,采用VOF方法追踪两相流界面,通过UDF在连续方程中添加附加质量源项的方法,建立了气幕防波堤数学模型.通过数值计算得到的波浪透射系数同试验数据吻合较好.在此基础上讨论了不同原型入射波浪要素、不同气幕间距以及不同供气量等对单排与双排气幕防波堤消波性能的影响,进而通过分析得出相应的结论,为气幕防波堤的设计提供有意义的依据.%Assuming the two-phase fluid of water and air as a variable density fluid, a numerical model of air bubble breakwater is developed with the continuity equation, Reynolds average equation and k -e model taken as the governing equations, the VOF method for tracing the interface of the two-phase flows, and the additional source term of the air bubble model added to the continuity equation by the Macro of UDF. The transmission coefficients obtained at the different air amounts and the wave periods agree well with the experimental data. The effects of single & double air discharging pipes on the wave dissipating performance of the air bubble breakwater are analyzed with different incident wave characteristics, different distances between two air discharged pipes, the incident wave height and air amounts, then some conclusions are obtained, which are meaningful to study the wave dissipating performances of air bubble breakwaters.

  18. Aqueous-phase chemistry and bactericidal effects from an air discharge plasma in contact with water: evidence for the formation of peroxynitrite through a pseudo-second-order post-discharge reaction of H2O2 and HNO2

    Science.gov (United States)

    Lukes, P.; Dolezalova, E.; Sisrova, I.; Clupek, M.

    2014-02-01

    The formation of transient species (OH·, NO2·, NO radicals) and long-lived chemical products (O3, H2O2, NO_{3}^{-} , NO_{2}^{-} ) produced by a gas discharge plasma at the gas-liquid interface and directly in the liquid was measured in dependence on the gas atmosphere (20% oxygen mixtures with nitrogen or with argon) and pH of plasma-treated water (controlled by buffers at pH 3.3, 6.9 or 10.1). The aqueous-phase chemistry and specific contributions of these species to the chemical and biocidal effects of air discharge plasma in water were evaluated using phenol as a chemical probe and bacteria Escherichia coli. The nitrated and nitrosylated products of phenol (4-nitrophenol, 2-nitrophenol, 4-nitrocatechol, 4-nitrosophenol) in addition to the hydroxylated products (catechol, hydroquinone, 1,4-benzoquinone, hydroxy-1,4-benzoquinone) evidenced formation of NO2·, NO· and OH· radicals and NO+ ions directly by the air plasma at the gas-liquid interface and through post-discharge processes in plasma-activated water (PAW) mediated by peroxynitrite (ONOOH). Kinetic study of post-discharge evolution of H2O2 and NO_{2}^{-} in PAW has demonstrated excellent fit with the pseudo-second-order reaction between H2O2 and NO_{2}^{-} . The third-order rate constant k = 1.1 × 103 M-2 s-1 for the reaction NO_{2}^{-} +H_{2}O_{2}+H^{+}\\to ONOOH+H_{2}O was determined in PAW at pH 3.3 with the rate of ONOOH formation in the range 10-8-10-9 M s-1. Peroxynitrite chemistry was shown to significantly participate in the antibacterial properties of PAW. Ozone presence in PAW was proved indirectly by pH-dependent degradation of phenol and detection of cis,cis-muconic acid, but contribution of ozone to the inactivation of bacteria by the air plasma was negligible.

  19. Development of open-air type electrolyte-as-cathode glow discharge-atomic emission spectrometry for determination of trace metals in water

    Science.gov (United States)

    Kim, Hyo J.; Lee, Jeong H.; Kim, Myung Y.; Cserfalvi, T.; Mezei, P.

    2000-07-01

    The open-air type electrolyte cathode atomic glow discharge (ELCAD) has been developed and studied for fundamental and analytical applications for determination of trace heavy metals in water. The normal closed-type discharge cell shows some problems such as unstable plasma due to changes in the pressure inside the cell during the discharge, and water vapor condensing onto the window. Applying approximately 1500 V to the several-millimeter gap between the electrolyte solution cathode and a Pt rod anode in atmospheric air pressure produced a stable plasma and significantly improved sensitivity. The emission spectrum of de-ionized water containing 100 mg/l Cu was measured and some emission lines were found from Cu I (324.7 nm, 327.4 nm and 510.5 nm) and Cu II (224.7 nm and 229.4 nm). The LODs of Cr, Cu, Fe, Mn, Ni, Pb, and Zn are in the ranges from 0.01 mg/l to 0.6 mg/l. The LODs of Cu, Mn, Pb and Zn improve by approximately one order of magnitude compared to the previous closed-type ELCAD.

  20. Upstream petroleum industry flaring and venting report : Industry performance for year ending December 31, 2004

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-08-01

    Since 1938, the Alberta Energy and Utilities Board (EUB) has made the reduction of routine flaring and venting of solution gas a priority. The EUB has been acknowledged internationally for its achievements in reducing flaring and venting. The EUB's goal is to eliminate the routine flaring and venting of solution gas in order to address energy conservation and public safety. This report describes how the EUB fulfills its information mandate regarding flaring and venting. It is published in response to a commitment made by the EUB to make flaring and venting data more accessible. The EUB and the Clean Air Strategic Alliance have established baselines for flaring and venting. Regulations, enforcement and industry cooperation have resulted in major reductions in the amount of solution gas flared and vented. This report provides a summary of flared and vented volumes for the different oil and gas industry sources, such as well tests, gas plants, gas gathering systems, transmission lines, and batteries. It also contains detailed information on solution gas conserved, flared, and vented during 2003. Ranking of companies was established based on solution gas flared plus vented, solution gas flared, and solution gas vented, from crude oil and bitumen batteries. The data used in the preparation of this report was submitted by companies. The data demonstrates that considerable progress has been made in the reduction of flaring and venting volumes for all upstream oil and gas sources. Solution gas conservation for 2004 was 96.0 per cent, the highest conservation level achieved to date. Solution gas flaring for 2004 was 72.2 per cent less than the 1996 flaring baseline, compared to 70.0 per cent less than the baseline in 2003. tabs., figs.

  1. Upstream petroleum industry flaring and venting report : Industry performance for year ending December 31, 2003

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-05-01

    Solution gas is the largest source of flaring and venting in Alberta. The Alberta Energy and Utilities Board (EUB) has been acknowledged internationally for its success in reducing flaring and venting. The EUB's target is to eliminate the routine flaring and venting of solution gas to address conservation and public safety. This report describes how the EUB fulfills its information mandate regarding flaring and venting. It is published in response to a commitment made by the EUB to make flaring and venting data more accessible. The EUB and the Clean Air Strategic Alliance have established baselines for flaring and venting. Regulations, enforcement and industry cooperation have resulted in major reductions in the amount of solution gas flared and vented. This report provides a summary of flared and vented volumes for the different oil and gas industry sources, such as well tests, gas plants, gas gathering systems, transmission lines, and batteries. It also contains detailed information on solution gas conserved, flared, and vented during 2003. Ranking of companies was established based on solution gas flared plus vented, solution gas flared, and solution gas vented, from crude oil and bitumen batteries. The data used in the preparation of this report was submitted by companies. The data demonstrates that considerable progress has been made in the reduction of flaring and venting volumes for all upstream oil and gas sources. Solution gas conservation for 2003 was 95.4 per cent, the highest conservation level achieved to date. Solution gas flaring for 2003 was 70 per cent less than the 1996 flaring baseline. tabs., figs.

  2. Electricity generation from hydrothermal vents

    Science.gov (United States)

    Aryadi, Y.; Rizal, I. S.; Fadhli, M. N.

    2016-09-01

    Hydrothermal vent is a kind of manifestation of geothermal energy on seabed. It produces high temperature fluid through a hole which has a diameter in various range between several inches to tens of meters. Hydrothermal vent is mostly found over ocean ridges. There are some 67000 km of ocean ridges, 13000 of them have been already studied discovering more than 280 sites with geothermal vents. Some of them have a thermal power of up to 60 MWt. These big potential resources of energy, which are located over subsea, have a constraint related to environmental impact to the biotas live around when it becomes an object of exploitation. Organic Rankine Cycle (ORC) is a method of exploiting heat energy to become electricity using organic fluid. This paper presents a model of exploitation technology of hydrothermal vent using ORC method. With conservative calculation, it can give result of 15 MWe by exploiting a middle range diameter of hydrothermal vent in deep of 2000 meters below sea level. The technology provided here really has small impact to the environment. With an output energy as huge as mentioned before, the price of constructing this technology is low considering the empty of cost for drilling as what it should be in conventional exploitation. This paper also presents the comparison in several equipment which is more suitable to be installed over subsea.

  3. A Simulation of the Effects of Varying Repetition Rate and Pulse Width of Nanosecond Discharges on Premixed Lean Methane-Air Combustion

    Directory of Open Access Journals (Sweden)

    Moon Soo Bak

    2012-01-01

    Full Text Available Two-dimensional kinetic simulation has been carried out to investigate the effects of repetition rate and pulse width of nanosecond repetitively pulsed discharges on stabilizing premixed lean methane-air combustion. The repetition rate and pulse width are varied from 10 kHz to 50 kHz and from 9 ns to 2 ns while the total power is kept constant. The lower repetition rates provide larger amounts of radicals such as O, H, and OH. However, the effect on stabilization is found to be the same for all of the tested repetition rates. The shorter pulse width is found to favor the production of species in higher electronic states, but the varying effects on stabilization are also found to be small. Our results indicate that the total deposited power is the critical element that determines the extent of stabilization over this range of discharge properties studied.

  4. A morphological study of the changes in the ultrastructure of a bacterial biofilm disrupted by an ac corona discharge in air

    Science.gov (United States)

    Stepanova, Olga; Rybalchenko, Oksana; Astafiev, Alexander; Orlova, Olga; Kudryavtsev, Anatoly; Kapustina, Valentina

    2016-08-01

    The morphology of bacterial cells and biofilms subjected to a low frequency (˜105 Hz) ac (˜10-1 A) corona discharge was investigated using electron microscopy. A low-frequency ac corona discharge in air is shown to have a bactericidal and bacteriostatic effect on Escherichia coli M17 culture at both the cellular and population levels. Corona exposure inhibits the formation of a microbial community and results in the destruction of formed biofilms. This paper presents data on changes in the ultrastructure of cells and biofilms after corona treatment. Our results suggest that the E. coli M17 cells inside biofilms are affected with results similar to sub-lethal and lethal thermal exposure. Some of the biological aspects of colony and biofilm cells death are evaluated. Morphological changes in the ultrastructure of the biofilms under corona treatment are described. Our results indicate that the heating effect is the main factor responsible for the corona-induced inactivation of bacteria.

  5. Investigation of the coplanar barrier discharge in synthetic air at atmospheric pressure by cross-correlation spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hoder, T [Department of Physical Electronics, Masaryk University, Kotlarska 2, Brno 611 37 (Czech Republic); SIra, M [Department of Physical Electronics, Masaryk University, Kotlarska 2, Brno 611 37 (Czech Republic); Kozlov, K V [Institute of Physics, Ernst-Moritz-Arndt University, Felix-Hausdorff-Str. 6, D-17489 Greifswald (Germany); Wagner, H-E [Institute of Physics, Ernst-Moritz-Arndt University, Felix-Hausdorff-Str. 6, D-17489 Greifswald (Germany)

    2008-02-07

    The barrier discharge in the coplanar arrangement operating in a single-filament mode was studied spectroscopically. The evolution of the discharge luminosity was measured by the technique of cross-correlation spectroscopy. The 1D-spatially and temporally resolved luminosities of the first negative (at 391.5 nm) and the second positive (at 337.1 nm) system of molecular nitrogen were recorded using the above-mentioned technique. A cathode-directed ionizing wave (IW) was clearly seen on the plot for radiation intensity at 337.1 nm. In addition to this, also observed was a wave of the enhanced electric field propagating over the anode. In this paper, the propagation of these waves is described and their velocities are determined. The discharge evolution is divided into three phases-the Townsend phase, the phase of the IWs propagation and the extinction phase. Since the above-mentioned luminosity distributions could be interpreted approximately as the electric field (for 391.5 nm) and the electron density (for 337.1 nm) distribution, the qualitative description of the discharge is made accordingly. All these parameters are compared with similar measurements of the volume discharge. Apart from this, an attempt to determine the reduced electric field is made according to the kinetic model.

  6. Experimental investigation on nanosecond pulsed discharge under static air condition%静止空气条件纳秒脉冲放电实验研究

    Institute of Scientific and Technical Information of China (English)

    张百灵; 陈峰; 李益文; 张杨; 朱涛

    2012-01-01

    Experiment investigation on nanosecond pulse discharge under static air and big volume condition has been performed under different air pressure, discharge distance and voltage. Research shows that under the condition of the length of 200mm and the pressure of 250Pa, as voltage increases the discharge region extend from near of the conical electrode to the whole channel. When the voltage is 12kV, discharge can fill the whole channel; and with the pressure rise the initial discharge voltage increases. It is found that nanosecond pulsed ionization instability appears when the voltage is increased to a certain extent, as the radial fluctuations in the plasma when the pressure is relatively low, and the discharge tends to break initially uniform nonequilibrium plasma into narrow hot arcs at relatively high pressure. Analysis indicates that shorter rise time, shorter pulse width and higher voltage for the source are needed to realize long distance, large volume homogeneous plasma.%采用纳秒脉冲电源,在静止空气条件下,开展了不同气压、放电距离和电压条件下的大体积纳秒脉冲放电实验研究.研究表明,当长度固定为200mm时,气压为250Pa时,随着电压的增大,放电区域从圆锥电极附近扩展到整个通道.当电压为12kV时,放电布满整个通道;随气压升高,初始放电电压增大.实验中发现在电压升高到一定程度时纳秒脉冲电离出现不稳定性,表现在气压相对较低时等离子体出现径向波动,气压相对较高时非平衡等离子体放电向电弧放电转变.分析认为,为了实现大体积均匀放电等离子体的产生,阻止放电不稳定性发生,应该采用上升沿时间更短,脉宽更小,电压更高的纳秒脉冲电源.

  7. Pancreatitis - discharge

    Science.gov (United States)

    Chronic pancreatitis - discharge; Pancreatitis - chronic - discharge; Pancreatic insufficiency - discharge; Acute pancreatitis - discharge ... You were in the hospital because you have pancreatitis. This is a swelling of the pancreas. You ...

  8. The Production and Evolution of Atomic Oxygen in the Afterglow of Streamer Discharge in Atmospheric Pressure Fuel/Air Mixtures

    Science.gov (United States)

    2013-07-02

    OH where the C3H7 radical can be formed in two isomeric configurations with total rate coefficient k ~ 3 x 1011 cm3 s-1 at T = 1500 K [14, 18]. At...in air and air/fuel nanosecond pulse dillcharges by two photon laser induced fluorescence Proc. Combust. lnst. 32 929 -36 [10] Bowman S, Adamovich

  9. 大气压空气介质阻挡汤森放电%Townsend Dielectric Barrier Discharge in Atmospheric Pressure Air

    Institute of Scientific and Technical Information of China (English)

    罗海云; 冉俊霞; 王新新

    2012-01-01

    In order to experimentally study the possibility of homogenous dielectric barrier discharge (DBD) in atmospheric pressure air as well as its characteristics, the homogenous DBD in 3 mm air gap was obtained at atmospheric pressure, using 1-2 kHz sinusoidal high voltage and no less than 1. 5 mm thick alumina as the dielectrics. The discharge was proven as an atmospheric pressure Townsend discharge after analyzing the 10 ns exposure high-speed photographs and the current waveform. The steady breakdown voltage for 3 mm air DBD was calculated to be about 5. 7 kV, much lower than 11. 2 kV, the static breakdown voltage of 3 mm air gap; Extraordinary extinction was also observed in air just like in nitrogen. Both the two phenomena indicated the existence of the shallow traps and consequently the second-electron emissidn in the alumina surface, which were important for ignition and maintaining stage of Townsend DBD. It is found that the thickness of alumina is important for air DBD, and the thickness less than 1.5 mm can not avoid the filamentary discharge. If two 1 mm thick quartz plates are used instead of alumina, it is impossible to get homogenous DBD at 670 PaN 0. 1 MPa in air. The mechanism of Townsend DBD in 3 mm air gap is attributed to the combined effects of the unique shallow traps in the alumina surface and the current-limitation of the dielectrics.%为了实验研究大气压空气介质阻挡均匀放电的可能性,使用1.5mm以上厚度的A120s陶瓷片作为阻挡介质及1-2kHz的高压激励,在大气压3mm空气平板间隙中获得均匀放电。通过ICCD高速摄影得到的放电图像以及电流波形的分析表明这种放电是汤森放电。3mm空气间隙的稳态击穿电压仅约为5.7kV,远低于静态击穿电压11.2kv;还发现了类似氮气DBD汤森放电的“反常熄灭”现象,这两个现象表明陶瓷表面可能存在浅位阱及二次电子发射机制,这对空气汤森放电的起始和维持阶段都

  10. Application of post-discharge region of atmospheric pressure argon and air plasma jet in the contamination control of Candida albicans biofilms

    Directory of Open Access Journals (Sweden)

    Anelise Cristina Osório Cesar Doria

    Full Text Available Introduction:Candida species are responsible for about 80% of hospital fungal infections. Non-thermal plasmas operated at atmospheric pressure are increasingly used as an alternative to existing antimicrobial strategy. This work investigates the action of post-discharge region of a non-thermal atmospheric plasma jet, generated by a gliding arc reactor, on biofilms of standard strain of Candida albicans grown on polyurethane substrate. Methods Samples were divided into three groups: (i non-treated; (ii treated with argon plasma, and (iii treated with argon plus air plasma. Subsequently to plasma treatment, counting of colony-forming units (CFU/ml and cell viability tests were performed. In addition, the surface morphology of the samples was evaluated by scanning electron microscopy (SEM and optical profilometry (OP. Results Reduction in CFU/ml of 85% and 88.1% were observed in groups ii and iii, respectively. Cell viability after treatment also showed reduction of 33% in group ii and 8% in group iii, in comparison with group i (100%. The SEM images allow observation of the effect of plasma chemistry on biofilm structure, and OP images showed a reduction of its surface roughness, which suggests a possible loss of biofilm mass. Conclusion The treatment in post-discharge region and the chemistries of plasma jet tested in this work were effective in controlling Candida albicans biofilm contamination. Finally, it was evidenced that argon plus air plasma was the most efficient to reduce cell viability.

  11. The influence of a transverse magnetic field on a subnormal glow discharge in air

    Indian Academy of Sciences (India)

    D C Jana; S S Pradhan

    2001-01-01

    In subnormal glow discharge under d.c. excitation at different pressure in a varying transverse magnetic field (0 to 30 G) some measurements have been carried out for various initial average tube currents. The voltage across the discharge increases and average tube current and residual current decreases in the magnetic field. With the help of Beckman’s expression [4] for the axial field and the electron density distribution in a transverse magnetic field the observed variation of current and voltage can be satisfactorily explained. The variation of axial electric field with transverse magnetic field can be represented to a fair degree of accuracy by the derived equation. The behaviour of residual current with magnetic field has been observed in these oscillations.

  12. Ending emissions: Industry targets venting, while flaring progress lauded

    Energy Technology Data Exchange (ETDEWEB)

    Lea, N.

    2003-06-01

    The progress achieved by the multi-stakeholder solution gas flaring reduction program in Alberta is discussed. The program was initiated in 1999 by the Alberta Energy and Utilities Board (EUB); within the first three years upstream flaring of solution gas was reduced by 53 per cent. Progress has also been made in reducing volumes of solution gas venting: between 1996 and 2001, there has been a 32 per cent reduction in combined flared and vented volumes of solution gas. Well test flaring has also been reduced by reduced test durations and volumes, to wit: there has been a 3 per cent reduction in flaring volumes while well tests have increased by 23 per cent. At gas plants, the decrease in flaring and venting amounted to 19 per cent, attributed mostly to industry response to the EUB's Guide 60, which incorporates many of the recommendations of the 2002 report and recommendations of the Flaring/Venting Project Team of the Clean Air Strategic Alliance (CASA).

  13. Plasma induced degradation of Indigo Carmine by bipolar pulsed dielectric barrier discharge(DBD) in the water-air mixture

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ruo-bing; WU Yan; LI Guo-feng; WANG Ning-hui; LI Jie

    2004-01-01

    Degradation of the Indigo Carmine(IC) by the bipolar pulsed DBD in water-air mixture was studied. Effects of various parameters such as gas flow rate, solution conductivity, pulse repetitive rate and ect., on color removal efficiency of dying wastewater were investigated. Concentrations of gas phase O3 and aqueous phase H2O2 under various conditions were measured. Experimental results showed that air bubbling facilitates the breakdown of water and promotes generation of chemically active species. Color removal efficiency of IC solution can be greatly improved by the air aeration under various solution conductivities. Decolorization efficiency increases with the increase of the gas flow rate, and decreases with the increase of the initial solution conductivity. A higher pulse repetitive rate and a larger pulse capacitor Cp are favorable for the decolorization process. Ozone and hydrogen peroxide formed decreases with the increase of initial solution conductivity. In addition, preliminary analysis of the decolorization mechanisms is given.

  14. Air-Sea Fluxes and River Discharges in the Black Sea With a Focus on the Danube and Bosphorus

    Science.gov (United States)

    2008-01-01

    ANSI Std Z39.18 Available online at www.sciencedirect.com ELSEVIER ScienceDirect Journal of Marine Systems 74 (2008) 74 95 J () li R N A 1...response to the annual 20090306221 Ill Karaetal. / Journal of Marine Systems 74 iJ(H)S) 74 95 ’> cycle of buoyancy fluxes at the sea surface (e.g...al. Journal of Marine Systems 74 COOS) 74 l>5 is to discuss monthly and annual mean river flow values discharged into the Black Sea as

  15. Electrohydrodynamic force produced by a wire-to-cylinder dc corona discharge in air at atmospheric pressure

    Science.gov (United States)

    Moreau, Eric; Benard, Nicolas; Lan-Sun-Luk, Jean-Daniel; Chabriat, Jean-Pierre

    2013-11-01

    Wire-to-cylinder corona discharges are studied to better understand the electrohydrodynamic (EHD) phenomena that govern the performances of electric propulsion systems. First, theory associated with EHD thrusters is presented in order to be compared with experimental results. Secondly, direct thrust measurements are carried out to optimize the electrical and geometrical parameters of such devices. The main results are as follows: (1) the discharge current I is proportional to the square root of the grounded electrode diameter and to 1/d2 where d is the electrode gap; (2) for d ⩽ 20 mm, the mobility of negative ions is higher than that of positive ions while the mobility of both ions is equal for higher gaps; (3) therefore, for gap ⩾30 mm, positive and negative coronas results in the same current-to-thrust conversion; (4) the current-to-thrust conversion is equal to 33 N A-1 per centimetre of gap, and it is proportional to the gap; (5) the thruster effectiveness θ increases with \\sqrt d , decreases with the square root of thrust and reaches about 15 N kW-1 for d = 40 mm (6) the force computed from experimental velocity profiles is overestimated compared with the values measured with a balance, showing that this method cannot be used for thrust determination.

  16. Study on the transition from filamentary discharge to diffuse discharge by using a dielectric barrier surface discharge device

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Discharge characteristics have been investigated in different gases under different pressures using a dielectric barrier surface discharge device. Electrical measurements and optical emission spectroscopy are used to study the discharge,and the results obtained show that the discharges in atmospheric pressure helium and in low-pressure air are diffuse,while that in high-pressure air is filamentary. With decreasing pressure, the discharge in air can transit from filamentary to diffuse one. The results also indicate that corona discharge around the stripe electrode is important for the diffuse discharge. The spectral intensity of N2+ (391.4 nm) relative to N2 (337.1 nm) is measured during the transition from diffuse to filamentary discharge. It is shown that relative spectral intensity increases during the discharge transition. This phenomenon implies that the averaged electron energy in diffuse discharge is higher than that in the filamentary discharge.

  17. Removal of formaldehyde by a pulsed dielectric barrier discharge in dry air in the 20 °C to 300 °C temperature range

    Science.gov (United States)

    Blin-Simiand, N.; Pasquiers, S.; Magne, L.

    2016-05-01

    The influence of the gas mixture temperature, from 20 °C up to 300 °C, on the removal of formaldehyde, diluted at low concentration (less than 800 ppm) in dry air at atmospheric pressure, by a pulsed dielectric barrier discharge (DBD) is studied by means of Fourier transform infrared spectroscopy and micro gas chromatography. Efficient removal of CH2O is obtained and it is found that the characteristic energy, less than 200 J l-1, is a decreasing function of the temperature over the whole range of concentration values under consideration. Byproducts issued from the removal are identified and quantified (CO, CO2, HCOOH, HNO3). Experimental results are analysed using a zero-dimensional simplified DBD-reactor model in order to gain insights on the chemical processes involved. It is shown that the dissociation of the molecule competes with oxidation reactions at low temperature, whereas at high temperature oxidation processes dominate.

  18. The consequences of air flow on the distribution of aqueous species during dielectric barrier discharge treatment of thin water layers

    Science.gov (United States)

    Tian, Wei; Lietz, Amanda M.; Kushner, Mark J.

    2016-10-01

    The desired outcomes of wet tissue treatment by dielectric barrier discharges (DBDs) strongly depend on the integrated fluences of reactive species incident onto the tissue, which are determined by power, frequency and treatment time. The reactivity produced by such plasmas is often expected to be proportional to treatment time due to the accumulation of radicals in the liquid over the tissue. However, one of the typically uncontrolled parameters in DBD treatment of liquids and tissue is gas flow, which could affect the delivery of plasma produced radicals to the tissue. Gas flow can redistribute long-lived, plasma produced gas phase species prior to solvating in the liquid, while not greatly affecting the solvation of short-lived species. Gas flow can therefore potentially be a control mechanism for tailoring the fluences of reactive species to the tissue. In this paper, we report on a computational investigation of the consequences of gas flow on treatment of liquid layers covering tissue by atmospheric DBDs by up to 100 pulses. We found that gas flow (through residence time of the gas) can control the production of gas phase species requiring many collisions to form, such as reactive nitrogen species (RNS). The resulting solvation of the RNS in turn controls the production of aqueous species such as \\text{NO}\\text{3aq}- and \\text{ONOO}\\text{aq}- (aq denotes an aqueous species). With the exception of O3 and O3aq, reactive oxygen species (ROS) are less sensitive to gas flow, and so OHaq and H2O2aq, are determined primarily by discharge properties.

  19. Numerical Modelling of Mutual Effect among Nearby Needles in a Multi-Needle Configuration of an Atmospheric Air Dielectric Barrier Discharge

    Directory of Open Access Journals (Sweden)

    Xiaoxing Zhang

    2012-05-01

    Full Text Available A numerical study has been conducted to understand the mutual effect among nearby needles in a multi-needle electrode dielectric barrier discharge. In the present paper, a fluid-hydrodynamic model is adopted. In this model, the mutual effect among nearby needles in a multi-needle configuration of an atmospheric air dielectric barrier discharge are investigated using a fluid-hydrodynamic model including the continuity equations for electrons and positive and negative ions coupled with Poisson’s equation. The electric fields at the streamer head of the middle needle (MN and the side needles (SNs in a three-needle model decreased under the influence of the mutual effects of nearby needles compared with that in the single-needle model. In addition, from the same comparison, the average propagation velocities of the streamers from MN and SNs, the electron average energy profile of MN and SNs (including those in the streamer channel, at the streamer head, and in the unbridged gap, and the electron densities at the streamer head of the MN and SNs also decreased. The results obtained in the current paper agreed well with the experimental and simulation results in the literature.

  20. Electro-hydrodynamic force field and flow patterns generated by a DC corona discharge in the air

    Science.gov (United States)

    Monrolin, Nicolas; Plouraboue, Franck; Praud, Olivier

    2016-11-01

    Ionic wind refers to the electro-convection of ionised air between high voltage electrodes. Microscopic ion-neutral collisions are responsible for momentum transfer from accelerated ions, subjected to the electric field, to the neutral gas molecules resulting in a macroscopic airflow acceleration. In the past decades it has been investigated for various purposes from food drying through aerodynamic flow control and eventually laptop cooling. One consequence of air acceleration between the electrodes is thrust generation, often referred to as the Biefeld-Brown effect or electro-hydrodynamic thrust. In this experimental study, the ionic wind velocity field is measured with the PIV method. From computing the acceleration of the air we work out the electrostatic force field for various electrodes configurations. This enables an original direct evaluation of the force distribution as well as the influence of electrodes shape and position. Thrust computation based on the flow acceleration are compared with digital scale measurements. Complex flow features are highlighted such as vortex shedding, indicating that aerodynamic effects may play a significant role. Furthermore, the aerodynamic drag force exerted on the electrodes is quantified by choosing an appropriate control volume. Authors thank Region Midi-Pyrenee and CNES Launcher Directorate for financial support.

  1. Research on the application of 2-D air vented ionization chamber array MatriXX system%二维空气电离室矩阵MatriXX系统的应用研究

    Institute of Scientific and Technical Information of China (English)

    张书旭; 周凌宏; 陈光杰; 林生趣; 沈国辉; 王余峰

    2009-01-01

    Objective To investigate the features of 2-D air vented ionization chamber array MatriXX system to use the QA procedures of radiotherapy. Methods Some important QA procedure of clinical radiotherapy practice were investigated by using a MatriXX system and a phantom made in house, mainly including the calibration of MatriXX, the off-axis rate (OAR) of virtual wedge fields, the connection between two half-fields or two asymmetry-fields, the skillful adjustment of the clinac flat filter, the 2-D dose distribution verification of radiotherapy planning, the influence of scatter screen to a large area electron beam field, the effect and best thickness and shielding position of block for a large area electron beam fields with scatter screen. Results The OAR of any virtual wedge field can be measured by a MatriXX system in a single irradiation. The conjunction accuracy of two half-fields or two asymmetry-fields may be less than 1 ram. The difference between the calculated and measured dose of any point or any isodose or any OAR of a field can be determined by using a MatriXX system. After the adjustment of the elinae flat filter with the help of MatriXX system, the flatness and symmetry of the field are 1. 85 % and 0.98 %, respectively. The dose characteristic of a large area electron beam field may be distinctively influenced by a scatter screen, and under this condition, the block faraway from the shielded target can hardly protect the organ at risk, and directe block which is put on or near the organ at risk is perfect. Conclusion Compared with conventional ionization chamber (Farmer type) or film dose measuring, the MatriXX combined with the OmniPre I'mRT software is much more convenient and effective in QA practice of clinical radiotherapy, and it's a perfect tool for the QA procedure of radiation therapy.%目的 探讨二维空气电离室矩阵MatriXX系统应用于放疗质量控制中的特点.方法 用MatriXX系统和自制的剂量测量体模,对临床放疗

  2. Assessment of Literature Related to Combustion Appliance Venting Systems

    Energy Technology Data Exchange (ETDEWEB)

    Rapp, Vi H. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Singer, Brett C. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Stratton, Chris [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Wray, Craig P. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2012-06-01

    In many residential building retrofit programs, air tightening to increase energy efficiency is constrained by concerns about related impacts on the safety of naturally vented combustion appliances. Tighter housing units more readily depressurize when exhaust equipment is operated, making combustion appliances more prone to backdraft or spillage. Several test methods purportedly assess the potential for depressurization-induced backdrafting and spillage, but these tests are not robustly reliable and repeatable predictors of venting performance, in part because they do not fully capture weather effects on venting performance. The purpose of this literature review is to investigate combustion safety diagnostics in existing codes, standards, and guidelines related to combustion appliances. This review summarizes existing combustion safety test methods, evaluations of these test methods, and also discusses research related to wind effects and the simulation of vent system performance. Current codes and standards related to combustion appliance installation provide little information on assessing backdrafting or spillage potential. A substantial amount of research has been conducted to assess combustion appliance backdrafting and spillage test methods, but primarily focuses on comparing short-term (stress) induced tests and monitoring results. Monitoring, typically performed over one week, indicated that combinations of environmental and house operation characteristics most conducive to combustion spillage were rare. Research, to an extent, has assessed existing combustion safety diagnostics for house depressurization, but the objectives of the diagnostics, both stress and monitoring, are not clearly defined. More research is also needed to quantify the frequency of test “failure” occurrence throughout the building stock and assess the statistical effects of weather (especially wind) on house depressurization and in turn on combustion appliance venting

  3. Field Testing of an Unvented Roof with Fibrous Insulation, Tiles, and Vapor Diffusion Venting

    Energy Technology Data Exchange (ETDEWEB)

    Ueno, K. [Building Science Corporation, Westford, MA (United States); Lstiburek, J. W. [Building Science Corporation, Westford, MA (United States)

    2016-02-01

    This research is a test implementation of an unvented tile roof assembly in a hot-humid climate (Orlando, FL; Zone 2A), insulated with air permeable insulation (netted and blown fiberglass). Given the localized moisture accumulation and failures seen in previous unvented roof field work, it was theorized that a 'diffusion vent' (water vapor open, but air barrier 'closed') at the highest points in the roof assembly might allow for the wintertime release of moisture, to safe levels. The 'diffusion vent' is an open slot at the ridge and hips, covered with a water-resistant but vapor open (500+ perm) air barrier membrane. As a control comparison, one portion of the roof was constructed as a typical unvented roof (self-adhered membrane at ridge). The data collected to date indicate that the diffusion vent roof shows greater moisture safety than the conventional, unvented roof design.

  4. VOC transport in vented drums containing simulated waste sludge

    Energy Technology Data Exchange (ETDEWEB)

    Liekhus, K.J.; Gresham, G.L.; Rae, C.; Connolly, M.J.

    1994-02-01

    A model is developed to estimate the volatile organic compound (VOC) concentration in the headspace of the innermost layer of confinement in a lab-scale vented waste drum containing simulated waste sludge. The VOC transport model estimates the concentration using the measured VOC concentration beneath the drum lid and model parameters defined or estimated from process knowledge of drum contents and waste drum configuration. Model parameters include the VOC diffusion characteristic across the filter vent, VOC diffusivity in air, size of opening in the drum liner lid, the type and number of layers of polymer bags surrounding the waste, VOC permeability across the polymer, and the permeable surface area of the polymer bags. Comparison of model and experimental results indicates that the model can accurately estimate VOC concentration in the headspace of the innermost layer of confinement. The model may be useful in estimating the VOC concentration in actual waste drums.

  5. Almost twenty years' search of transuranium isotopes in effluents discharged to air from nuclear power plants with VVER reactors.

    Science.gov (United States)

    Hölgye, Z; Filgas, R

    2006-04-01

    Airborne effluents of 5 stacks (stacks 1-5) of three nuclear power plants, with 9 pressurized water reactors VVER of 4,520 MWe total power, were searched for transuranium isotopes in different time periods. The search started in 1985. The subject of this work is a presentation of discharge data for the period of 1998-2003 and a final evaluation. It was found that 238Pu, 239,240Pu, 241Am, 242Cm, and 244Cm can be present in airborne effluents. Transuranium isotope contents in most of the quarterly effluent samples from stacks 2, 4 and 5 were not measurable. Transuranium isotopes were present in the effluents from stack l during all 9 years of the study and from stack 3 since the 3rd quarter of 1996 as a result of a defect in the fuel cladding. A relatively high increase of transuranium isotopes in effluents from stack 3 occurred in the 3rd quarter of 1999, and a smaller increase occurred in the 3rd quarter of 2003. In each instance 242Cm prevailed in the transuranium isotope mixtures. 238Pu/239,240Pu, 241Am/239,240Pu, 242Cm/239,240Pu, and 244Cm/239,240Pu ratios in fuel for different burn-up were calculated, and comparison of these ratios in fuel and effluents was performed.

  6. Regional Venting in the Manus Basin, New Britain Back Arc

    Science.gov (United States)

    Massoth, G. J.; Puzic, J.; Crowhurst, P.; White, M.; Nakamura, K.; Walker, S. L.; Baker, E. T.

    2008-12-01

    During June 2008 we conducted a systematic reconnaissance for hydrothermal venting along 1540 km of back-arc features located throughout the Manus back-arc basin. Our search was guided by high-resolution bathymetric and side scan back scatter data obtained during historical and immediately preceding geophysical surveys. Using real-time plume mapping protocols to discern anomalies in light scattering, temperature, and oxidation-reduction potential, we detected ~45 venting sites, ~34 of which are believed new. On average, the venting site density was about 3 sites per 100 km of back-arc feature, comparable to that for surveyed fast-spreading MORs in the eastern Pacific (3.2, Baker and German, AGU Geophysical Monograph 148, 2004) and about twice the global mean for MORs (1.6, Baker et al., JGR 2008). By virtue of being basin-scale, our assessment of venting into the Bismarck Sea revealed several mid-depth plumes that are widespread within the region. In the eastern Manus basin (Southeast Ridges, Djaul Transform, Southern Rifts, and Manus Spreading Center regions) the mean plume depth was 1825 m (range: 1080-2625 m), compared to generally more shallow discharge (mean plume depth 1155 m, range: 725-2080 m) in the western basin (Manus Extensional Transform and the Willaumez Transform and Ridge regions). While extreme anomaly intensities were observed in both the eastern and western portions of the Manus basin, most plumes were more characteristic of MOR and back arc plumes displaying a range of weak-to-moderate plume signals. Subsequent seafloor reconnaissance by ROV has located massive sulfides coincident to several plumes.

  7. 长空气间隙放电过程的试验观测技术%Experimental Observation Technology for Long Air Gap Discharge

    Institute of Scientific and Technical Information of China (English)

    陈维江; 谷山强; 谢施君; 孙豹; 贺恒鑫; 陈家宏; 何俊佳; 钱冠军; 向念文

    2012-01-01

    Experimental observation technology applied to record the physical process of long air gap discharge is the key to the research of its physical mechanism and the establishment of a simulation model. High-speed optical observation technology, discharge current measurement technology, space electric field measurement technology and the method for the synchronization of the above technologies were studied in this paper. The image-forming principle of the high-speed charge coupled devices (CCD) camera was analyzed. According to the optical characteristics of the leader channel, a practical observation method was proposed. A novel electrode construction was proposed to reduce the impact of the displacement current and surface discharge current of the electrode body. A digital photoelectric isolation acquisition system was developed for the transmission of the current signal. Base on the Pockels effect, an integrated electric field measuring device with a measurement amplitude limit of 800 kV/m was developed. At last, a synchronization scheme for optical observation results and electrical measurement results using the exposure clock signal of the high-speed CCD camera was proposed. The work involved in this paper is beneficial for obtaining the key physical parameters accurately, and clarifying the physical process of long air gap discharge.%长空气间隙放电物理过程的试验观测研究是揭示长问隙放电机制和建立放电分析模型的基础。在高速光学观测技术、放电电流测量技术、空间瞬态电场测量技术和同步观测技术4方面开展了研究。通过分析高速摄影仪的成像原理,设计了针对不同放电阶段先导通道光学特性的观测方法;通过合理设计电极结构,研制全数字式光电隔离采集系统,实现了对高电位放电通道电流的全数字式测量;基于Pockels效应,研制出测量幅值上限达800kV/m的集成光波导瞬态电场仪;基于高速摄影仪

  8. Observations and Modeling of Long Negative Laboratory Discharges: Identifying the Physics Important to an Electrical Spark in Air

    Energy Technology Data Exchange (ETDEWEB)

    Biagi, C J; Uman, M A

    2011-12-13

    There are relatively few reports in the literature focusing on negative laboratory leaders. Most of the reports focus exclusively on the simpler positive laboratory leader that is more commonly encountered in high voltage engineering [Gorin et al., 1976; Les Renardieres Group, 1977; Gallimberti, 1979; Domens et al., 1994; Bazelyan and Raizer 1998]. The physics of the long, negative leader and its positive counterpart are similar; the two differ primarily in their extension mechanisms [Bazelyan and Raizer, 1998]. Long negative sparks extend primarily by an intermittent process termed a 'step' that requires the development of secondary leader channels separated in space from the primary leader channel. Long positive sparks typically extend continuously, although, under proper conditions, their extension can be temporarily halted and begun again, and this is sometimes viewed as a stepping process. However, it is emphasized that the nature of positive leader stepping is not like that of negative leader stepping. There are several key observational studies of the propagation of long, negative-polarity laboratory sparks in air that have aided in the understanding of the stepping mechanisms exhibited by such sparks [e.g., Gorin et al., 1976; Les Renardieres Group, 1981; Ortega et al., 1994; Reess et al., 1995; Bazelyan and Raizer, 1998; Gallimberti et al., 2002]. These reports are reviewed below in Section 2, with emphasis placed on the stepping mechanism (the space stem, pilot, and space leader). Then, in Section 3, reports pertaining to modeling of long negative leaders are summarized.

  9. Geochemistry of reduced fluids from shallow cold vents hosting chemosynthetic communities (Comau Fjord, Chilean Patagonia, ∼42°S)

    Science.gov (United States)

    Muñoz, Práxedes; Sellanes, Javier; Villalobos, Katherine; Zapata-Hernández, Germán; Mayr, Christoph; Araya, Karen

    2014-12-01

    Reduced fluids from shallow-marine vents sustain chemosynthetic bacterial mats located at the base of the volcano Barranco Colorado in Comau Fjord (X-Huinay; 42°23.279‧S, 72°27.635‧W). We characterized the chemical environment in which these bacteria thrive. To this end, we analyzed CH4, ∑H2S, O2, DIC, and stable isotopes (δ13C, δ2H and δ18O) and compared them with readings taken at a control station (which lacks evidence of fluid venting and mat-forming bacteria). In addition, CTD measurements, chlorophyll-a, and nutrient analyses were performed. At depths of approximately 5-7 m, the water column exhibited a pycnocline that formed under the influence of fresh water discharges, especially during the summer season, which also affected the surface temperature. Bacterial mats and elemental sulfur flocs were observed in the vicinity of the vents (X-Huinay station), and higher concentrations of reduced compounds (CH4 and ∑H2S) were found in the vent fluids, in particular at a depth of 36 m. No significant differences in the temperatures of vent and ambient waters were detected. The bottom water close to the vents possessed notably low concentrations of reduced compounds, indicating a rapid and large-quantity dilution of the chemicals from vents. The surface water featured light isotopic values of δ2H and 18O due to the freshwater input from melting ice and precipitation. A linear mixing trend was observed between the freshwater (negative isotopic values) and the fjord bottom water (positive values) that was not influenced by vent fluid. This trend suggests that the venting water corresponds to the mixing among local meteoric water, spring water, and seawater. This result is relevant to understanding how freshwater and meteoric water influence the chemical composition of seawater and how this mixing could impact the marine biota in the vicinities of the vents.

  10. Simulating the venting of radioactivity from a soviet nuclear test

    Science.gov (United States)

    Rodriguez, Daniel J.; Peterson, Kendall R.

    Fresh fission products were found in several routine air samples in Europe during the second and third weeks of March 1987. Initially, it was suspected that the radionuclides, principally 133Xe and 131I, had been accidentally released from a European facility handling nuclear materials. However, the announcement of an underground nuclear test at Semipalatinsk, U.S.S.R. on 26 February 1987 suggested that the elevated amounts of radioactivity may, instead, have been caused by a venting episode. Upon learning of these events, we simulated the transport and diffusion of 133Xe with our Hemispheric MEDIC and ADPIC models, assuming Semipalatinsk to be the source of the radioactive emissions. The correspondence between the calculated concentrations and the daily average 133Xe measurements made by the Federal Office for Civil Protection in F.R.G. was excellent. While this agreement does not, in itself, prove that an atmospheric venting of radioactive material occurred at Semipalatinsk, a body of circumstantial evidence exists which, when added together, strongly supports this conclusion. Our calculations suggested a total fission yield of about 40 kt, which is within the 20-150 kt range of tests acknowledged by the U.S.S.R. Finally, dose calculations indicated that no health or environmental impact occurred outside of the U.S.S.R. due to the suspected venting of 133Xe. However, the inhalation dose resulting from 133I, an unmodeled component of the radioactive cloud, represented a greater potential risk to public health.

  11. TURBULENCE,VORTEX AND EXTERNAL EXPLOSION INDUCED BY VENTING

    Institute of Scientific and Technical Information of China (English)

    姜孝海; 范宝春; 叶经方

    2004-01-01

    The process of explosion venting to air in a cylindrical vent vessel connected to a duct, filling with a stoichiometric methane-oxygen gas mixture, was simulated numerically by using a colocated grid SIMPLE scheme based on k-epsilon turbulent model and Eddydissipation combustion model. The characteristics of the combustible cloud, flame and pressure distribution in the external flow field during venting were analyzed in terms of the predicted results. The results show that the external explosion is generated due to violent turbulent combustion in the high pressure region within the external combustible cloud ignited by a jet flame. And the turbulence and vortex in the external flow field were also discussed in detail. After the jet flame penetrating into the external combustible cloud, the turbulent intensity is greater in the regions with greater average kinetic energy gradient, rather than in the flame front; and the vortex in the external flow field is generated primarily due to the baroclinic effect, which is greater in the regions where the pressure and density gradients are nearly perpendicular.

  12. A ‘tissue model’ to study the barrier effects of living tissues on the reactive species generated by surface air discharge

    Science.gov (United States)

    He, Tongtong; Liu, Dingxin; Xu, Han; liu, Zhichao; Xu, Dehui; Li, Dong; Li, Qiaosong; Rong, Mingzhe; Kong, Michael G.

    2016-05-01

    Gelatin gels are used as surrogates of human tissues to study their barrier effects on incoming reactive oxygen and nitrogen species (RONS) generated by surface air discharge. The penetration depth of nitrite into gelatin gel is measured in real time during plasma treatment, and the permeabilities of nitrite, nitrate, O3 and H2O2 through gelatin gel films are quantified by measuring their concentrations in the water underneath such films after plasma treatment. It is found that the penetration speed of nitrite increases linearly with the mass fraction of water in the gelatin gels, and the permeabilities of nitrite and O3 are comparably smaller than that for H2O2 and nitrate due to differences in their chemistry in gelatin gels. These results provide a quantitative basis to estimate the penetration processes of RONS in human tissues, and they also confirm that the composition of RONS is strongly dependent on the tissue depth and the plasma treatment time. A small electric field of up to 20 V cm-1 can greatly reduce the barrier effects of the tissue model regardless of their directions, for which the underlying mechanism is unclear. However, the electric field force on the objective RONS should not be the dominant mechanism.

  13. Des Vents et des Jets Astrophysiques

    Science.gov (United States)

    Sauty, C.

    well expected result from the theory. Although, collimation may be conical, paraboloidal or cylindrical (Part 4), cylindrical collimation is the more likely to occur. The shape of outflows may then be used as a tool to predict physical conditions on the flows or on their source. L'éjection continue de plasma autour d'objets massifs est un phénomène largement répandu en astrophysique, que ce soit sous la forme du vent solaire, de vents stellaires, de jets d'étoiles en formation, de jets stellaires autour d'objets compacts ou de jets extra-galactiques. Cette zoologie diversifiée fait pourtant l'objet d'un commun effort de modélisation. Le but de cette revue est d'abord de présenter qualitativement le développement, depuis leur origine, des diverses théories de vents (Partie 1) et l'inter disciplinarité dans ce domaine. Il s'agit d'une énumération, plus ou moins exhaustive, des idées proposées pour expliquer l'accélération et la morphologie des vents et des jets, accompagnée d'une présentation sommaire des aspects observationnels. Cette partie s'abstient de tout aspect faisant appel au formalisme mathématique. Ces écoulements peuvent être décrits, au moins partiellement, en résolvant les équations magnétohydrodynamiques, axisymétriques et stationnaires. Ce formalisme, à la base de la plupart des théories, est exposé dans la Partie 2. Il permet d'introduire quantitativement les intégrales premières qu'un tel système possède. Ces dernières sont amenées à jouer un rôle important dans la compréhension des phénomènes d'accélération ou de collimation, en particulier le taux de perte de masse, le taux de perte de moment angulaire ou l'énergie du rotateur magnétique. La difficulté de modélisation réside dans l'existence de points critiques, propres aux équations non linéaires, qu'il faut franchir. La nature physique et la localisation de ces points critiques fait l'objet d'un débat important car ils sont la clef de voute de la r

  14. Circle Points Discharge Tube Current Controller

    Institute of Scientific and Technical Information of China (English)

    Meng Jinjia; Meng Lisheng

    2005-01-01

    Circle points discharge tube current controller is a new type device to limit theoutput of high voltage discharge current. Circle points uniform corona discharge to form airionization current in the discharge tube. On the outside, even if the discharge electrode is sparkdischarging or the two discharge electrodes are short circuited, the air ionization current in the tuberemains within a stable range, and there is no spark discharge. In this case, when the dischargecurrent only increases slightly, the requirement to limited current is obtained. By installing thecontroller at a discharge pole with a small power but high voltage supply, we can realize the shiftbetween the continuous spark line discharge and corona discharge. This provides a new simpledevice for spark discharge research and is a supplement to the Townsend discharge experiment.

  15. Hip fracture - discharge

    Science.gov (United States)

    Inter-trochanteric fracture repair - discharge; Subtrochanteric fracture repair - discharge; Femoral neck fracture repair - discharge; Trochanteric fracture repair - discharge; Hip pinning surgery - discharge

  16. Modelling Discharge Inception in Thunderstorms

    NARCIS (Netherlands)

    Rutjes, Casper; Dubinova, Anna; Ebert, Ute; Buitink, Stijn; Scholten, Olaf; Trinh, Gia Thi Ngoc

    2015-01-01

    The electric fields in thunderstorms can exceed the breakdown value locally near hydrometeors. But are fields high enough and the regions large enough to initiate a streamer discharge? And where would a sufficient density of free electrons come from to start the discharge in the humid air that rapid

  17. 46 CFR 64.63 - Minimum emergency venting capacity.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Minimum emergency venting capacity. 64.63 Section 64.63... emergency venting capacity. (a) The total emergency venting capacity (Q) of the relief devices of an... ASME Code, 1974 edition, or 315. (b) The total emergency venting capacity (Q) of an insulated...

  18. 46 CFR 153.355 - PV venting systems.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false PV venting systems. 153.355 Section 153.355 Shipping... Systems § 153.355 PV venting systems. When Table 1 requires a PV venting system, the cargo tank must have a PV valve in its vent line. The PV valve must be located between the tank and any connection...

  19. 30 CFR 77.304 - Explosion release vents.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Explosion release vents. 77.304 Section 77.304... Dryers § 77.304 Explosion release vents. Drying chambers, dry-dust collectors, ductwork connecting dryers... explosion release vents which open directly to the outside atmosphere, and all such vents shall be:...

  20. 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.

  1. Gas Explosions Mitigation by Ducted Venting

    OpenAIRE

    2007-01-01

    The mitigation of effects of gas and dust explosions within industrial equipment is effective if venting the combustion products to safe location. The presence of relief duct is however likely to increase the severity of the explosion with respect to equipment vented to open atmosphere, due to secondary explosions occurring in the initial sections of duct, frictional drag and inertia of the gas column, acoustic and Helmholtz oscillations. The weights of these phenomena on explosion e...

  2. 针-板DBD微流注与微辉光交替生成的机理研究%Atmospheric pressure streamer and glow-discharge generated alternately by pin-to-plane dielectric barrier discharge in air

    Institute of Scientific and Technical Information of China (English)

    俞哲; 张芝涛; 于清旋; 许少杰; 姚京; 白敏冬; 田一平; 刘开颖

    2012-01-01

    Performance of producing a high energy electron can be improved, if the glow discharge is generated in a system of dielectric barrier discharge. In this paper, different discharge modes of pin-to-plane dielectric barrier discharge are investigated in atmospheric pressure. Different discharge modes are observed in the positive half-period and negative half-period of the discharge. When and applied voltage is 3 kV, a streamer mode appear in the positive half-period and a corona (or Trichel discharge) mode occurs in negative half-period. When the applied voltage is 6 kV, a streamer emerges in the positive half-period and a micro glow discharge is present in the negative half-period. The micro glow discharge has hierarchical structure like that typical low pressure glow discharge produces. The generation of micro glow discharge is due to, enough strong cathode electric field strength and effective secondary electron emission process around naked negative electrode. The glow discharge transforming to arc discharge is avoided due to dielectric layer.%在介质阻挡放电体系中产生辉光放电可以有效的提高放电体系产生高能电子的性能,为等离子体化学反应提供更加丰富的活性粒子.本文对针一板介质阻挡放电体系下的放电模式进行了研究,实验发现放电正负半周期表现出不同的放电模式,激励电压为3kV时放电正负半周期分别为微流注放电和电晕放电(或者Trichel脉冲放电),激励电压为6kV时放电正负半周期分别为微流注放电和微辉光放电.微辉光放电形貌具有与典型辉光放电相同的分层次放电结构,分析了激励电压6kV时的放电过程,认为足够强的阴极电场强度和裸露针状电极形成的有效的二次电子发射过程是形成微辉光放电的主要因素,绝缘介质层的存在避免了微辉光放电向弧光放电过渡.

  3. Long-term effects of multiply pulsed dielectric barrier discharges in air on thin water layers over tissue: stationary and random streamers

    Science.gov (United States)

    Tian, Wei; Kushner, Mark J.

    2015-12-01

    Tissue covered by thin liquid layers treated by atmospheric pressure plasmas for biomedical applications ultimately requires a reproducible protocol for human healthcare. The desired outcomes of wet tissue treatment by dielectric barrier discharges (DBDs) depend on the plasma dose which determines the integral fluence of radicals, ions, electric fields and UV/VUV photons incident onto the tissue. These fluences are controlled by power, frequency and treatment time. To first order, these parameters determine the energy deposition (J cm-2) onto the tissue. However, energy deposition may not be the only parameter that determines the fluences of reactants to the underlying tissue. In this paper, we report on a computational investigation of multipulse DBDs interacting with wet tissue. The DBDs were simulated for 100 pulses at different repetition rates and liquid thicknesses followed by 10 s or more of afterglow. Two schemes were investigated—stationary and random. In the stationary scheme, the DBD plasma streamer continues to strike at the same location on the liquid layer, whereas in the random scheme the plasma streamer strikes at random locations on the liquid layer. These differences in streamer locations strongly affect the spatial distribution of solvated species such as OHaq and H2O2aq (‘aq’ represents an aqueous species), which have high rates of solvation. The spatial distribution of species such as NOaq, which have low rates of solvation, are less affected by the location of the streamer due to the remediating effects of diffusion in the air. The end result is that fluences to the tissue are sensitive to the spatial location of the streamer due to the ensuing reactions in the liquid between species that have low and high rates of solvation. These reactions can be controlled not only through location of the streamer, but also by repetition rate and thickness of the liquid layer.

  4. Reasons of Air Separator Outage Accident Caused by Gas Discharging and Countermeasures%煤气放空造成安钢制氧机停车事故的原因和对策分析

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    Outage of many air separators caused by gas discharging is the first time in air separating history of Anyang Iron & Steel Co., Ltd. The accident causes are analyzed. The related improvement suggestions are offered to avoid such accident.%  煤气放空造成制氧机大面积停车是安钢制氧史上第一次。对事故原因进行了分析,提出了整改意见,避免了此事故再次发生。

  5. NIPPLE DISCHARGE

    Directory of Open Access Journals (Sweden)

    T. N. Bukharova

    2008-01-01

    Full Text Available According to the data available in the literature, as high as 50% of women have benign breast tumors frequently accompanied by nip- ple discharge. Nipple discharge may be serous, bloody, purulent, and colostric. The most common causes are breast abscess, injury, drugs, prolactinoma, intraductal pappiloma, ductal ectasia, intraductal cancer (not more than 10%.

  6. New insights into the initiation and venting of the Bronze-Age eruption of Santorini (Greece), from component analysis

    Science.gov (United States)

    Druitt, T. H.

    2014-02-01

    The late-seventeenth century BC Minoan eruption of Santorini discharged 30-60 km3 of magma, and caldera collapse deepened and widened the existing 22 ka caldera. A study of juvenile, cognate, and accidental components in the eruption products provides new constraints on vent development during the five eruptive phases, and on the processes that initiated the eruption. The eruption began with subplinian (phase 0) and plinian (phase 1) phases from a vent on a NE-SW fault line that bisects the volcanic field. During phase 1, the magma fragmentation level dropped from the surface to the level of subvolcanic basement and magmatic intrusions. The fragmentation level shallowed again, and the vent migrated northwards (during phase 2) into the flooded 22 ka caldera. The eruption then became strongly phreatomagmatic and discharged low-temperature ignimbrite containing abundant fragments of post-22 ka, pre-Minoan intracaldera lavas (phase 3). Phase 4 discharged hot, fluidized pyroclastic flows from subaerial vents and constructed three main ignimbrite fans (northwestern, eastern, and southern) around the volcano. The first phase-4 flows were discharged from a vent, or vents, in the northern half of the volcanic field, and laid down lithic-block-rich ignimbrite and lag breccias across much of the NW fan. About a tenth of the lithic debris in these flows was subvolcanic basement. New subaerial vents then opened up, probably across much of the volcanic field, and finer-grained ignimbrite was discharged to form the E and S fans. If major caldera collapse took place during the eruption, it probably occurred during phase 4. Three juvenile components were discharged during the eruption—a volumetrically dominant rhyodacitic pumice and two andesitic components: microphenocryst-rich andesitic pumices and quenched andesitic enclaves. The microphenocryst-rich pumices form a textural, mineralogical, chemical, and thermal continuum with co-erupted hornblende diorite nodules, and together

  7. Temporal and spatial variation in temperature experienced by macrofauna at Main Endeavour hydrothermal vent field

    Science.gov (United States)

    Lee, Raymond W.; Robert, Katleen; Matabos, Marjolaine; Bates, Amanda E.; Juniper, S. Kim

    2015-12-01

    A significant focus of hydrothermal vent ecological studies has been to understand how species cope with various stressors through physiological tolerance and biochemical resistance. Yet, the environmental conditions experienced by vent species have not been well characterized. This objective requires continuous observations over time intervals that can capture environmental variability at scales that are relevant to animals. We used autonomous temperature logger arrays (four roughly parallel linear arrays of 12 loggers spaced every 10-12 cm) to study spatial and temporal variations in the thermal regime experienced by hydrothermal vent macrofauna at a diffuse flow vent. Hourly temperatures were recorded over eight months from 2010 to 2011 at Grotto vent in the Main Endeavour vent field on the Juan de Fuca Ridge, a focus area of the Ocean Networks Canada cabled observatory. The conspicuous animal assemblages in video footage contained Ridgeia piscesae tubeworms, gastropods (primarily Lepetodrilus fucensis), and polychaetes (polynoid scaleworms and the palm worm Paralvinella palmiformis). Two dimensional spatial gradients in temperature were generally stable over the deployment period. The average temperature recorded by all arrays, and in some individual loggers, revealed distinctive fluctuations in temperature that often corresponded with the tidal cycle. We postulate that this may be related to changes in bottom currents or fluctuations in vent discharge. A marked transient temperature increase lasting over a period of days was observed in April 2011. While the distributions and behavior of Juan de Fuca Ridge vent invertebrates may be partially constrained by environmental temperature and temperature tolerance, except for the one transient high-temperature event, observed fluid temperatures were generally similar to the thermal preferences for some species, and typically well below lethal temperatures for all species. Average temperatures of the four arrays

  8. An Evaluation of a General Venting Strategy in CANDU 6 Reactor Building

    Energy Technology Data Exchange (ETDEWEB)

    Kim, See Darl; Kim, Dong Ha; Park, Soo Yong; Song, Yong Man; Jin, Young Ho

    2006-03-15

    If the reactor building sprays or local air coolers are not available, depressurization by reactor building venting is considered as a useful mitigation strategy for a severe accident management of the Wolsong plants. As the CFVS is not established in the Wolsong Units, the reactor building isolation system can be a substitute for reactor building venting. The D{sub 2}O Vapour recovery system which has a 30' diameter penetration is expected to meet the NRC requirements. To investigate the effectiveness of the Reactor Building Venting Strategy, three kinds of accidents are analyzed: a SBO, a SLOCA and a Large LOCA. The reactor building pressure behavior was analyzed with ISAAC 2.0.2 for four different cases: without venting, 55psig/50psig, 50psig/40psig and 50psig/30psig valve open/close pressures. It was found that applying venting for a SBO reduces the mass fraction of the CsI released to the environment by 67.8% (valve open/close pressure of 55psig/50psig), by 64.4% (valve open/close pressure of 50psig/40psig) and by 63.5% (valve open/close pressure of 50psig/30psig). For a SLOCA, venting strategy reduces the mass fraction of the CsI by 58.3% (valve open/close pressure of 55psig/50psig), by 55.0% (valve open/close pressure 50psig/40psig) and by 48.3% (valve open/close pressure 50psig/30psig). For a LLOCA, reactor building venting reduces the mass fraction of the CsI released to the environment by less than 10% when compared to that without reactor building venting. When the reactor building spray or local air coolers can not be operated, a depressurization strategy by using the D{sub 2}O Vapour Recovery System could prevent a reactor building failure and reduce the amount of CsI released to the environment. The present study shows that the operation of valves at a pressure of 55psig/50psig is safe and effective. Based on the current study, the strategy of reactor building venting is involved SAMG-5.

  9. 14 CFR 23.975 - Fuel tank vents and carburetor vapor vents.

    Science.gov (United States)

    2010-01-01

    ... will constitute a fire hazard or from which fumes may enter personnel compartments; and (7) Vents must... a separate vent line to lead vapors back to the top of one of the fuel tanks. If there is more than... line must lead back to the fuel tank to be used first, unless the relative capacities of the tanks...

  10. Discharge Dialogue

    DEFF Research Database (Denmark)

    Horsbøl, Anders

    2012-01-01

    less attention has been given to medical patients, who are often elderly and suffer from multiple diseases. This paper addresses the latter issue with a case study of a local initiative to improve transition from hospital to home (care) for medical patients at a Danish hospital, in which a discharge...... coordinator, employed at the hospital, is supposed to anticipate discharge and serve as mediator between the hospital and the municipal home care system. Drawing on methods from discourse and interaction analysis, the paper studies the practice of the discharge coordinator in two encounters between patients...

  11. Bulk soybean grain mass temperature in warehouses with isolated vents and vent-exhaust combined systems

    Directory of Open Access Journals (Sweden)

    Eliza Rigoni de Pontes

    Full Text Available ABSTRACT: This study aimed to compare the temperatures in the mass of bulk soybeans ( Glycine max in warehouses with isolated vents and vent-combined exhaustion. A completely randomized design was used, with two treatments and ten repetitions. Treatments consisted of warehouse with curved vents and warehouse with curved + static exhaust vents. Each repetition contained the average of all readings in three days in all cables of the warehouse part under study, totaling 10 repetitions per month. The variable analyzed was the temperature in the grain mass in the lower, middle and upper parts of the warehouse from January to May 2012. The environment temperature and humidity were also registered. Static hoods, along with curved vents on the roof of the warehouse showed a tendency to reduce the temperature of the soybean mass with decrease in environmental temperature and increase in relative environmental humidity.

  12. MicroVent (part III)

    DEFF Research Database (Denmark)

    Dreau, Jerome Le; Heiselberg, Per Kvols; Jensen, Rasmus Lund

    This study aims at using the InVentilate unit in the cooling case, without heat recovery. It results in a relatively low inlet air temperature. Different solutions have been tested to decrease the risk of draught in the occupied zone: ‐ Using a mixer (2 designs) ‐ Using an inlet grille ‐ Using an...

  13. 风引出料一体化粉碎机的设计%Design of Integration Grinder with Air-induced Discharging Device

    Institute of Scientific and Technical Information of China (English)

    王明友; 宋卫东; 李尚昆; 吴金姬; 王教领

    2016-01-01

    To meet the large-scale smashing production of soft straw and hard straw with high fiber materials and overcome the shortcomings of single-mission cutter and shredder, a straw grinder with air-induced discharging device was developed, which realized the force feeding of hard straws with high fiber. The results showed that soft straw could be directly fed into the smashing device without cutting with the average efficiency of 1.27 kg/h and electricity consumption o per ton of 32.0 kW·h. The hard straw with high fiber should be first fed into the shredding device with force feeding rol to cut and then grinded, for which the efficiency average was 0.67 kg/h and electricity consumption per ton was 60.5 kW·h. The machine was stable, safe and reliable with strong adaptability of materials and no-dust operating environ-ment, which satisfied the design requirements.%为满足软质秸秆和硬质高纤维物料规模化粉碎的生产需要,并克服单一切碎机、粉碎机的缺点,设计了一种带风引出料装置的切粉一体化组合式秸秆粉碎机,实现了硬质高纤维秸秆的强制喂入。结果表明,软质秸秆可直接通过粉碎装置喂料口喂入,无需切碎,平均生产率为1.27 kg/h,吨料电耗为32.0 kW·h;硬质高纤维秸秆需通过带有强制喂料辊的切碎装置后进行先切后粉,平均生产率为0.67 kg·h,吨料电耗为60.5 kW·h。该机器具有性能稳定、安全可靠、物料适应性强和操作环境无粉尘等优点,性能满足设计要求。

  14. 大气压空气中纳秒脉冲弥散放电实验研究%Experimental Study on Nanosecond-pulse Diffuse Discharge in Atmospheric Air

    Institute of Scientific and Technical Information of China (English)

    章程; 邵涛; 许家雨; 马浩; 严萍

    2012-01-01

    Nanosecond-pulse can generate extremely high power density and large-scale non-thermal plasma, which attracts attentions. We used a repetitive nanosecond-pulse generator based on magnetic compression system to drive gas discharge in atmospheric air with a tube-to-plane gap, and investigated characteristics of diffuse discharge by the measurement of electrical discharge parameters and discharge images. The experimental results show that large scale diffuse discharge can be obtained at atmospheric pressure with high pulse repetition frequency, and the diffuse discharge will transit to corona or spark mode with increasing or decreasing air gap spacing, respectively. Polarity effect occurs in repetitive nanosecond-pulse discharge, with a negative polarity of the electrode of small curvature radius, diffuse discharge needs more electric field for excitation than that with a positive polarity. In addition, intensity of the diffuse discharge decreases with the increase of the rise-time of pulse. Therefore, the diffuse discharge is likely available under certain conditions of proper air gap, high electric field with positive pulse, and fast rise time.%为了能够在大气压下获得大面积高能量密度的低温等离子体,近年来弥散放电的研究与应用受到广泛关注。采用基于磁脉冲压缩系统的重复频率ns脉冲电源来激励大气压空气中尖板电极结构放电,通过电压电流测量和发光图像拍摄研究了弥散放电的特性。实验结果表明,在常温常压和高重复频率下能够获得大面积均匀的弥散放电,气隙距离增大或减小时,弥散放电分别向电晕放电与火花放电转换。重频ns脉冲放电存在极性效应,电极的小曲率半径处施加负脉冲时需要比正脉冲更高的电场强度才能获得弥散放电。此外,弥散放电的强度随着脉冲上升时间的增大而减弱。因此合适的气隙距离、极不均匀电场的强场处施加正极性脉冲和较陡的脉

  15. Safety Injection System Filling Using Dynamic Venting

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sung Je; Kim, Wong Bae; Huh, Jin; Lee, Joo Hee; Im, In Young; Kim, Eun kee [KEPCO Engineering and Construction Company, Daejeon (Korea, Republic of)

    2015-05-15

    In the APR+, the water-level elevation of the in-containment refueling water storage tank (IRWST) is lower than the highest piping of the SIS. Since the gravity filling of water from IRWST cannot fill all SIS piping, an SIP or an SCP test line is newly provided in order to allow the dynamic venting of the SIS. NEI 09-10 Revision 1a-A has concluded that use of dynamic venting is an effective means to remove gas from local high points and traps in piping when correctly based on the dynamic flow rate, void volume, Floude number, and the system water volume. In this study, feasibility of the dynamic vent is investigated. The work presented in this study evaluates the SIS and the SCS filling using the dynamic venting which is supposed to be applied to the APR+. The main ideas are as follows; 1. Dynamic venting using SIPs for the APR+ is not appropriate on the basis of 12 inches in diameter and with the flow rate, 1,460 gpm. 2. Because the high point of the SIS and the SCS is located at the piping that the two systems are sharing, the accumulated gas at the highest point can be removed by using the SCPs, and the dimension of the new piping will be determined by its length of them and the number of elbows. The calculated results are shown in Table 2. 3. The applicability of the dynamic venting methods using the SCPs that are mentioned above should be evaluated in the aspect of the system operation after the piping arrangements are settled in the APR+. The assessments to determine the pump operation time are also required.

  16. Evaluation of Passive Vents in New Construction Multifamily Buildings

    Energy Technology Data Exchange (ETDEWEB)

    Maxwell, Sean [Steven Winter Associates, Inc., Norwalk, CT (United States); Berger, David [Steven Winter Associates, Inc., Norwalk, CT (United States); Zuluaga, Marc [Steven Winter Associates, Inc., Norwalk, CT (United States)

    2016-02-01

    Exhaust ventilation and corresponding outdoor air strategies are being implemented in high-performance new construction multifamily buildings to meet program or code requirements for improved indoor air quality, but a lack of clear design guidance is resulting in poor performance of these systems despite the best intentions of the programs or standards. CARB's 2014 'Evaluation of Ventilation Strategies in New Construction Multifamily Buildings' consistently demonstrated that commonly used outdoor air strategies are not performing as expected. Of the four strategies evaluated in 2014, the exhaust ventilation system that relied on outdoor air from a pressurized corridor was ruled out as a potential best practice due to its conflict with meeting requirements within most fire codes. Outdoor air that is ducted directly to the apartments was a strategy determined to have the highest likelihood of success, but with higher first costs and operating costs. Outdoor air through space conditioning systems was also determined to have good performance potential, with proper design and execution. The fourth strategy, passive systems, was identified as the least expensive option for providing outdoor air directly to apartments, with respect to both first costs and operating costs. However, little is known about how they actually perform in real-world conditions or how to implement them effectively. Based on the lack of data available on the performance of these low-cost systems and their frequent use in the high-performance building programs that require a provision for outdoor air, this research project sought to further evaluate the performance of passive vents.

  17. Vents et nuages la physique du ciel

    CERN Document Server

    2013-01-01

    Les nuages et les vents sont au cœur des attentions des climatologues et des météorologues. Les premiers s’intéressent à leurs interactions avec le réchauffement climatique. Les seconds cherchent à prédire le temps qu’il fera demain, mais aussi les manifestations extrêmes (tornades, orages, cyclones…). Un numéro pour rester le nez au vent et la tête dans les nuages !

  18. Composition of gases vented from a condenser

    Energy Technology Data Exchange (ETDEWEB)

    Lyon, R.N.

    1980-08-01

    Designers of systems that involve condensers often need to predict the amount of process vapor that accompanies the noncondensable gases that are vented from the condensers. An approximation is given that appears to provide, in many cases, reasonably accurate values for the mole ratio of process vapor to noncondensable gases in the vented mixture. The approximation is particularly applicable to flash and direct-contact power systems for geothermal brines and ocean thermal energy conversion (OTEC). More regorous relationships are available for exceptional cases.

  19. Cameras on the NEPTUNE Canada seafloor observatory: Towards monitoring hydrothermal vent ecosystem dynamics

    Science.gov (United States)

    Robert, K.; Matabos, M.; Sarrazin, J.; Sarradin, P.; Lee, R. W.; Juniper, K.

    2010-12-01

    Hydrothermal vent environments are among the most dynamic benthic habitats in the ocean. The relative roles of physical and biological factors in shaping vent community structure remain unclear. Undersea cabled observatories offer the power and bandwidth required for high-resolution, time-series study of the dynamics of vent communities and the physico-chemical forces that influence them. The NEPTUNE Canada cabled instrument array at the Endeavour hydrothermal vents provides a unique laboratory for researchers to conduct long-term, integrated studies of hydrothermal vent ecosystem dynamics in relation to environmental variability. Beginning in September-October 2010, NEPTUNE Canada (NC) will be deploying a multi-disciplinary suite of instruments on the Endeavour Segment of the Juan de Fuca Ridge. Two camera and sensor systems will be used to study ecosystem dynamics in relation to hydrothermal discharge. These studies will make use of new experimental protocols for time-series observations that we have been developing since 2008 at other observatory sites connected to the VENUS and NC networks. These protocols include sampling design, camera calibration (i.e. structure, position, light, settings) and image analysis methodologies (see communication by Aron et al.). The camera systems to be deployed in the Main Endeavour vent field include a Sidus high definition video camera (2010) and the TEMPO-mini system (2011), designed by IFREMER (France). Real-time data from three sensors (O2, dissolved Fe, temperature) integrated with the TEMPO-mini system will enhance interpretation of imagery. For the first year of observations, a suite of internally recording temperature probes will be strategically placed in the field of view of the Sidus camera. These installations aim at monitoring variations in vent community structure and dynamics (species composition and abundances, interactions within and among species) in response to changes in environmental conditions at different

  20. Modeling High Pressure Micro Hollow Cathode Discharges

    Science.gov (United States)

    2007-11-02

    cathode discharge excimer lamps , Phys. Plasmas 7, 286 (2000). [3] RH Stark and KH Schoenbach, Direct high pressure glow discharges, J. Appl. Phys...temperature profiles in argon glow discharges, J. Appl. Phys. 88, 2234 (2000) [8] M. Moselhy, W. Shi, R. Stark, A flat glow discharge excimer radiation...MHCD acts as a plasma cathode for a third electrode (anode). Some experimental results in this geometry are available for argon and for air from the

  1. A change in the electro-physical properties of narrow-band CdHgTe solid solutions acted upon by a volume discharge induced by an avalanche electron beam in the air at atmospheric pressure

    Science.gov (United States)

    Voitsekhovskii, A. V.; Grigor'ev, D. V.; Korotaev, A. G.; Kokhanenko, A. P.; Tarasenko, V. F.; Shulepov, M. A.

    2012-03-01

    The effect of a nanosecond volume discharge forming in an inhomogeneous electrical field at atmospheric pressure on the CdHgTe (MCT) epitaxial films of the p-type conduction with the hole concentration 2·1016 cm3 and mobility 500 cm2·V-1·s-1 is studied. The measurement of the electrophysical parameters of the MCT specimens upon irradiation shows that a layer exhibiting the n-type conduction is formed in the near-surface region of the epitaxial films. After 600 pulses and more, the thickness and the parameters of the layer are such that the measured field dependence of the Hall coefficient corresponds to the material of the n-type conduction. Analysis of the preliminary results reveals that the foregoing nanosecond volume discharge in the air at atmospheric pressure is promising for modification of electro-physical MCT properties.

  2. 120kV下常压空气纳秒脉冲电晕放电特性%Characteristic of nanosecond-pulsed corona discharge at 120 kV in atmospheric-pressure air

    Institute of Scientific and Technical Information of China (English)

    章程; 邵涛; 许家雨; 马浩; 徐蓉; 严萍

    2012-01-01

    With an excitation of negative repetitive pulses of 15 ns rise time and 30 to 40 ns duration, corona discharge in nanosecond-pulse regime at 120 kV in atmospheric-pressure air is experimentally investigated, and the characteristic of nanosecond-pulsed corona discharge is analyzed by the measurement of electrical discharge parameters, images and X-ray emission. The results show that X-ray emission occurs in nanosecond-pulsed corona discharge, but the intensity is weak. The counts of X rays decrease with the air gap spacing but increase with the pulse repetition frequency. In addition, owing to the fact that the residual particles in the gap enhance the local electric field when the next pulse is applied, separated corona channels are easily obtained at high pulse repetition frequency.%使用上升沿15 ns、脉宽30~40 ns的重复频率纳秒脉冲电源对120 kV下大气压空气中管-板电极结构电晕放电进行了实验研究,通过电压电流测量、放电图像拍摄和X射线探测分析了纳秒脉冲电晕放电特性.结果表明:纳秒脉冲电晕放电中存在X射线辐射,但辐射强度较弱,X射线辐射计数随着气隙距离的增大而减少,随着脉冲重复频率的增大而增多;放电空间的残余电荷加强了下一个脉冲到来时的局部电场,从而导致高重复频率下易于出现分散的电晕通道.

  3. Glow and pseudo-glow discharges in a surface discharge generator

    Institute of Scientific and Technical Information of China (English)

    Li Xue-Chen; Dong Li-Fang; Wang Long

    2005-01-01

    The glow discharge in flowing argon at one atmospheric pressure is realized in a surface discharge generator. The discharge current presents one peak per half-cycle of the applied voltage. The duration of the discharge pulse is more than 1μs when the frequency of the applied voltage is 60kHz. For the glow discharge in argon, the power consumption increases with the increase of voltage or the decrease of gas pressure.This relation is explained qualitatively based on the theory of the Townsend breakdown mechanism. In contrast, the discharge current in one atmospheric pressure air gives many spikes in each half-cycle, and correspondingly this kind of discharge is called pseudo-glow discharge. Every current spike oscillates with high-frequency damping. The pseudo-glow discharge in one atmospheric pressure air might result from the streamer breakdown mechanism.

  4. Collision-Induced Dissociation Study of the Adduct Ions Produced in NO3 (-)-Free Area of Atmospheric Pressure Negative Corona Discharges under Ambient Air Conditions.

    Science.gov (United States)

    Sekimoto, Kanako; Matsuda, Natsuki; Takayama, Mitsuo

    2013-01-01

    Collision-induced dissociation (CID) experiments of adducts [M+R](-) with negative atmospheric ions R(-) (O2 (-), HCO3 (-) and COO(-)(COOH)) produced in NO3 (-)-free discharge area in atmospheric pressure corona discharge ionization (APCDI) method were performed using aliphatic and aromatic compounds M. The [M+R](-) adducts for individual R(-) fragmented to form deprotonated analytes [M-H](-) as well as the specific product ions which also occurred in the CID of [M-H](-), independent of analytes with several different functional groups. The results obtained suggested that the specific product ions formed in the CID of [M+R](-), as well as CID of [M-H](-), are generated due to further fragmentation of the product ions [M-H](-). It was concluded, therefore, that CID of [M+R](-) formed in NO3 (-)-free discharge area can indirectly lead to the formation of the product ions originating from [M-H](-).

  5. 低海拔地区长空气间隙放电特性试验研究%Experimental Research of Long Air-Gap Discharge Characteristics in Low Altitude Area

    Institute of Scientific and Technical Information of China (English)

    许飞; 黄志都; 李恒灿; 廖永力; 刘磊; 高超

    2011-01-01

    In order to improve the external insulation design of UHV transmission lines, the discharge experiments of rod-plate long air gap under DC voltage, lightning impulse voltage and operating impulse voltage are carried out in Nanning, and it proves that the discharge voltage of rod-plate air gap with positive polarity is much lower than that with negative polarity. The experimental data are corrected with related standards, and then the results are compared with the data of rod-plate discharge in China Electric Power Research Institute in Beijing, which is in almost the same altitude as Nanning, showing that the correction methods recommended by IEC 60060-1, DL/T 620-1997 and 1EC 60060-1 are good for the positive discharge test in plain and that by DL/T 620-1997 are mainly for power frequency discharge voltage and positive impulse discharge voltage.%为进一步完善特高压线路的外绝缘设计,在南宁进行了棒一板长空气间隙的直流、雷电和操作冲击电压的放电试验,发现正极性的棒一板间隙放电电压比负极性的要低很多。应用相关标准对试验数据进行大气校正,并与海拔高度与南宁接近的北京中国电科院高压基地的棒一板间隙放电数据进行对比,结果显示: IEC 60060-1、DL/T 620-1997标准以及IEC 60060-1推荐校正方法适用于平原地区正极性放电试验的校正,DL/T 620-1997中的校正方法主要适用于对工频放电电压以及正极性冲击放电电压。

  6. Building America Case Study: Design Guidance for Passive Vents in New Construction Multifamily Buildings, New York, New York

    Energy Technology Data Exchange (ETDEWEB)

    2016-02-01

    This document addresses the use of passive vents as a source of outdoor air in multifamily buildings. The challenges associated with implementing passive vents and the factors affecting performance are outlined. A comprehensive design methodology and quantified performance metrics are provided. Two hypothetical design examples are provided to illustrate the process. This document is intended to be useful to designers, decision-makers, and contractors implementing passive ventilation strategies. It is also intended to be a resource for those responsible for setting high-performance building program requirements, especially pertaining to ventilation and outdoor air. To ensure good indoor air quality, a dedicated source of outdoor air is an integral part of high-performance buildings. Presently, there is a lack of guidance pertaining to the design and installation of passive vents, resulting in poor system performance. This report details the criteria necessary for designing, constructing, and testing passive vent systems to enable them to provide consistent and reliable levels of ventilation air from outdoors.

  7. 46 CFR 153.358 - Venting system flow capacity.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Venting system flow capacity. 153.358 Section 153.358 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SHIPS... Venting Systems § 153.358 Venting system flow capacity. (a) The cross-sectional flow area of any...

  8. 46 CFR 151.15-6 - Venting piping.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Venting piping. 151.15-6 Section 151.15-6 Shipping COAST... LIQUID HAZARDOUS MATERIAL CARGOES Tanks § 151.15-6 Venting piping. (a) The back pressure in the relief... condensate which may accumulate in the vent piping. (b)...

  9. 40 CFR 63.983 - Closed vent systems.

    Science.gov (United States)

    2010-07-01

    ... inspections for visible, audible, or olfactory indications of leaks. (ii) If the closed vent system is... 40 Protection of Environment 10 2010-07-01 2010-07-01 false Closed vent systems. 63.983 Section 63... Emission Standards for Closed Vent Systems, Control Devices, Recovery Devices and Routing to a Fuel...

  10. Discovery of a black smoker vent field and vent fauna at the Arctic Mid-Ocean Ridge.

    Science.gov (United States)

    Pedersen, Rolf B; Rapp, Hans Tore; Thorseth, Ingunn H; Lilley, Marvin D; Barriga, Fernando J A S; Baumberger, Tamara; Flesland, Kristin; Fonseca, Rita; Früh-Green, Gretchen L; Jorgensen, Steffen L

    2010-11-23

    The Arctic Mid-Ocean Ridge (AMOR) represents one of the most slow-spreading ridge systems on Earth. Previous attempts to locate hydrothermal vent fields and unravel the nature of venting, as well as the provenance of vent fauna at this northern and insular termination of the global ridge system, have been unsuccessful. Here, we report the first discovery of a black smoker vent field at the AMOR. The field is located on the crest of an axial volcanic ridge (AVR) and is associated with an unusually large hydrothermal deposit, which documents that extensive venting and long-lived hydrothermal systems exist at ultraslow-spreading ridges, despite their strongly reduced volcanic activity. The vent field hosts a distinct vent fauna that differs from the fauna to the south along the Mid-Atlantic Ridge. The novel vent fauna seems to have developed by local specialization and by migration of fauna from cold seeps and the Pacific.

  11. Biological and Agricultural Studies on Application of Discharge Plasma and Electromagnetic Fields 2.Sterilization by Electrical Discharges and Plasmas

    Science.gov (United States)

    Watanabe, Takayuki

    The use of electrical discharges and plasmas for sterilization is reviewed. Plasmas generated by a silent discharge, a pulse discharge, and a radio frequency discharge under atmospheric pressure have been used for sterilization. Furthermore, a microwave plasma, a radio frequency plasma, and a low temperature plasma with hydrogen peroxide under low pressure conditions have been also used for sterilization. Sterilization results from injury caused by the discharge current, and from the reaction of species affected by the discharge. A silent discharge with air or oxygen is most effective for the sterilization. Nitrogen discharge also has a significant effect, however, argon discharge does not have a significant effect.

  12. Angioplasty and stent - heart - discharge

    Science.gov (United States)

    Drug-eluting stents - discharge; PCI - discharge; Percutaneous coronary intervention - discharge; Balloon angioplasty - discharge; Coronary angioplasty - discharge; Coronary artery angioplasty - discharge; Cardiac ...

  13. A Design Tool for Clothing Applications: Wind Resistant Fabric Layers and Permeable Vents

    Directory of Open Access Journals (Sweden)

    Phillip Gibson

    2014-01-01

    Full Text Available A computational clothing design tool is used to examine the effects of different clothing design features upon performance. Computational predictions of total heat and mass transfer coefficients of the clothing design tool showed good agreement with experimental measurements obtained using a sweating thermal manikin for four different clothing systems, as well as for the unclothed bare manikin. The specific clothing design features examined in this work are the size and placement of air-permeable fabric vents in a protective suit composed primarily of a fabric-laminated polymer film layer. The air-permeable vents were shown to provide additional ventilation and to significantly decrease both the total thermal insulation and the water vapor resistance of the protective suit.

  14. Characteristics of atmospheric pressure air uniform discharge generated by a plasma needle%大气压等离子体针产生空气均匀放电特性研究

    Institute of Scientific and Technical Information of China (English)

    李雪辰; 袁宁; 贾鹏英; 常媛媛; 嵇亚飞

    2011-01-01

    Cold plasma generated by atmospheric air discharge has wide application prospect in industry because it does not need vacuum equipment and mass production is possible.In this paper,a stable uniform discharge is generated in open air by a plasma needle.Discharge mechanism is investigated by optical method,and plasma parameters are given by the spatially resolved measurement of emission spectrum from the discharge.Results show that the discharges have two modes.One is a corona discharge mode and the other is plasma plume mode.In the stable plasma plume mode,a strong emission area and a weak emission one can be distinguished from each other.The development velocity of the weak emission area is much faster than that of the strong emission area.Furthermore,the electron energy and the plasma density in the weak emission area are also bigger than those in the strong emission area.Therefore,the discharge in the strong emission area is dominated by Townsend mechanism,while that in the weak emission area is dominated by streamer discharge.Gas temperature and vibration temperature are also studied in this paper.The experimental results are of great importance to the industrial applications of atmospheric pressure discharge.%大气压空气放电由于脱离了真空装置,易于实现流水线生产,因而在工业上具有广泛的应用.采用等离子体针装置在空气中产生了稳定的大气压均匀放电.利用光谱法对等离子体的相关参数进行了空间分辨率测量,并通过光学方法对放电机理进行了研究.结果表明,等离子体针产生的放电存在电晕放电和等离子体羽放电两种模式.在稳定的等离子体羽放电模式中,发光分为强光区和弱光区.弱光区放电的发展速度远大于强光区的发展速度,电子能量和电子密度均是弱光区比强光区大.对均匀放电的气体温度和振动温度的研究表明,强光区放电遵循汤生击穿机理而弱光区为流光放电.这些结果对

  15. Investigation of Penning Ionization in Atmospheric Helium Dielectric Barrier Discharges With Air Impurity%含空气杂质大气压氦气介质阻挡放电中彭宁电离作用

    Institute of Scientific and Technical Information of China (English)

    郝艳捧; 阳林; 王晓蕾

    2009-01-01

    进行大气压氦气介质阻挡放电,通过测量放电起始电压和发射光谱,研究本底空气压强BAP在0.8~1000Pa时放电中彭宁电离作用的变化规律.结果发现:BAP<190Pa时,放电起始电压显著降低,N_2~+第一负区391.4nm谱线强度随BAP增大而增大;BAP>190Pa时,放电起始电压显著线性增大,391.4nm谱线强度随BAP增大而逐渐下降,最终几乎趋于零.He原子的各谱线强度随BAP增大而逐渐递减.探讨其物理过程为:放电起始电压的结果和发射光谱的结果均指出彭宁电离作用随BAP改变而变化;He原子各谱线强度变化是由于淬灭造成的.%The change law of Penning ionization in atmospheric helium dielectric barrier discharges (DBDs) with air impurity was investigated. Discharge inception voltage and emission spectra were measured under different background air pressures (BAPs) changing from 0.8Pa to 1000Pa. Results of these two kinds of methods showed that in a range of BAP from 0.8Pa to 190Pa, discharge inception voltage decreased obviously and the 391.4nm line intensity increased with the BAP. When BAP arrives at more than l90Pa, discharge inception voltage increased linearly obviously and 391.4nm line intensity gradually dropped to lower value with the BAP, even a zero value at last. Emission spectra of helium decreased with the BAP. Physical processes analysis indicated that the results from both discharge inception voltage and emission spectra illustrated that Penning ionization due to helium metastables and N_2 changed with the BAP, and the changes of all emission spectra intensities of helium are due to the quenching caused by N_2.

  16. 40 CFR 63.116 - Process vent provisions-performance test methods and procedures to determine compliance.

    Science.gov (United States)

    2010-07-01

    ... From the Synthetic Organic Chemical Manufacturing Industry for Process Vents, Storage Vessels, Transfer...) of this section is used. (1) A boiler or process heater with a design heat input capacity of 44... introduced with the combustion air or as a secondary fuel into a boiler or process heater with a...

  17. 40 CFR 63.117 - Process vent provisions-reporting and recordkeeping requirements for group and TRE determinations...

    Science.gov (United States)

    2010-07-01

    ... Organic Hazardous Air Pollutants From the Synthetic Organic Chemical Manufacturing Industry for Process... boiler or process heater. (iv) For a boiler or process heater with a design heat input capacity of less... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Process vent provisions-reporting...

  18. Production of extended plasma channels in atmospheric air by amplitude-modulated UV radiation of GARPUN-MTW Ti : sapphire—KrF laser. Part 2. Accumulation of plasma electrons and electric discharge control

    Science.gov (United States)

    Zvorykin, V. D.; Ionin, Andrei A.; Levchenko, A. O.; Mesyats, Gennadii A.; Seleznev, L. V.; Sinitsyn, D. V.; Smetanin, Igor V.; Sunchugasheva, E. S.; Ustinovskii, N. N.; Shutov, A. V.

    2013-04-01

    The problem of the production of extended (~1 m) plasma channels is studied in atmospheric air by amplitude-modulated laser pulses of UV radiation, which are a superposition of a subpicosecond USP train amplified in a regenerative KrF amplifier with an unstable confocal resonator and a quasi-stationary lasing pulse. The USPs possess a high (0.2-0.3 TW) peak power and efficiently ionise oxygen molecules due to multiphoton ionisation, and the quasi-stationary lasing pulse, which has a relatively long duration (~100 ns), maintains the electron density at a level ne = (3-5) × 1014 cm—3 by suppressing electron attachment to oxygen. Experiments in laser triggering of high-voltage electric discharges suggest that the use of combined pulses results in a significant lowering of the breakdown threshold and enables controlling the discharge trajectory with a higher efficiency in comparison with smooth pulses. It was shown that controlled breakdowns may develop with a delay of tens of microseconds relative to the laser pulse, which is many orders of magnitude greater than the lifetime of free electrons in the laser-induced plasma. We propose a mechanism for this breakdown, which involves speeding-up of the avalanche ionisation of the air by negative molecular oxygen ions with a low electron binding energy (~0.5 eV) and a long lifetime (~1 ms), which are produced upon cessation of the laser pulse.

  19. 地表紫外辐射对棒-板空气间隙工频放电的影响%Effect of Terrestrial Solar UV Radiation on Power Frequency Discharge Performance of Rod-Plane Air Gap

    Institute of Scientific and Technical Information of China (English)

    杨占刚; 舒立春; 蒋兴良; 胡琴; 邱宗奎

    2013-01-01

    It is significant to reveal the effect of terrestrial solar ultraviolet radiation (TSUVR) on discharge performance of power system external insulation for the design and operation of external insulation in the regions with strong TSUVR. The ultraviolet radiation (UVR) in atmospheric environment is simulated by artificial ultraviolet light source, and the effect of UVR on power frequency discharge characteristic of air-gap is researched in laboratory. The experimental results show that the TSUVR does not effect on both power frequency breakdown voltage of air-gap and corona discharge evidently. The experimental results are explained as following: the photon energy of TSUVR is smaller than the work function of iron, copper and their oxides, therefore it is impossible to photo-ionize out electrons from iron or copper electrodes and there is not evident influence on the discharge process. Although partial photon energy is higher than the work function of Al, Al is easy to be oxidized in the air and then its oxide film Al2O3 is formed in the air, and this Al2O3 layer prevents the electrons to be ionized out from the surface of Al electrode. Thus, there is not evident influence of TSUVR on power frequency discharge of electrodes of copper, iron and Al, which exposed in the air.%  揭示地表太阳紫外辐射对电力系统外绝缘放电特性的影响对于强紫外辐射地区外绝缘设计和运行有着重要的意义。利用人工紫外光源模拟大气环境中的紫外辐射,在实验室研究了紫外辐射对空气间隙工频放电特性的影响。试验结果表明地表太阳紫外辐射对空气间隙工频击穿电压和电晕放电均无明显影响。产生这种现象的原因是:地表太阳紫外辐射的光子能量小于铁和铜及其氧化物的逸出功,因此无法从铁、铜电极中电离出电子。同时,紫外辐射对空气间隙放电发展过程也没有明显影响。虽然这一波段的部分光子能量高于铝的

  20. Provisions for containment venting in Germany

    Energy Technology Data Exchange (ETDEWEB)

    Wilhelm, J.G.

    1997-08-01

    In this short paper an overlook is given of the systems developed in Germany for filtered containment venting and their implementation in nuclear power plants. More information on the development can be found in the Proceedings of the DOE/NRC Aircleaning Conferences. In Germany, 28.8 % of the electric energy is produced by 19 nuclear power reactors. No new power reactor is expected to be built at least within the next ten years, but France and Germany cooperate in the development of a future European Power Reactor (ERP). This reactor type will be fitted with a core catcher and passive cooling in order to avoid serious consequences of a hypothetical core meltdown accident so that provisions for containment venting are not required. 3 refs., 6 figs., 1 tab.

  1. Ulcerative colitis - discharge

    Science.gov (United States)

    Inflammatory bowel disease - ulcerative colitis - discharge; Ulcerative proctitis - discharge; Colitis - discharge ... were in the hospital because you have ulcerative colitis. This is a swelling of the inner lining ...

  2. Field Testing of an Unvented Roof with Fibrous Insulation, Tiles and Vapor Diffusion Venting

    Energy Technology Data Exchange (ETDEWEB)

    Ueno, K. [Building Science Corporation, Westford, MA (United States); Lstiburek, J. W. [Building Science Corporation, Westford, MA (United States)

    2016-02-05

    This research is a test implementation of an unvented tile roof assembly in a hot-humid climate (Orlando, FL; Zone 2A), insulated with air permeable insulation (netted and blown fiberglass). Given the localized moisture accumulation and failures seen in previous unvented roof field work, it was theorized that a 'diffusion vent' (water vapor open, but air barrier 'closed') at the highest points in the roof assembly might allow for the wintertime release of moisture, to safe levels. The 'diffusion vent' is an open slot at the ridge and hips, covered with a water-resistant but vapor open (500+ perm) air barrier membrane. As a control comparison, one portion of the roof was constructed as a typical unvented roof (self-adhered membrane at ridge). The data collected to date indicate that the diffusion vent roof shows greater moisture safety than the conventional, unvented roof design. The unvented roof had extended winter periods of 95-100% RH, and wafer (wood surrogate RH sensor) measurements indicating possible condensation; high moisture levels were concentrated at the roof ridge. In contrast, the diffusion vent roofs had drier conditions, with most peak MCs (sheathing) below 20%. In the spring, as outdoor temperatures warmed, all roofs dried well into the safe range (10% MC or less). Some roof-wall interfaces showed moderately high MCs; this might be due to moisture accumulation at the highest point in the lower attic, and/or shading of the roof by the adjacent second story. Monitoring will be continued at least through spring 2016 (another winter and spring).

  3. Ecology of deep-sea hydrothermal vent communities: A review

    Science.gov (United States)

    Lutz, Richard A.; Kennish, Michael J.

    1993-08-01

    Studies of the many active and inactive hydrothermal vents found during the past 15 years have radically altered views of biological and geological processes in the deep sea. The biological communities occupying the vast and relatively stable soft bottom habitats of the deep sea are characterized by low population densities, high species diversity, and low biomass. In contrast, those inhabiting the generally unstable conditions of hydrothermal vent environments exhibit high densities and biomass, low species diversity, rapid growth rates, and high metabolic rates. Biological processes, such as rates of metabolism and growth, in vent organisms are comparable to those observed in organisms from shallow-water ecosystems. An abundant energy source is provided by chemosynthetic bacteria that constitute the primary producers sustaining the lush communities at the hydrothermal sites. Fluxes in vent flow and fluid chemistry cause changes in growth rates, reproduction, mortality, and/or colonization of vent fauna, leading to temporal and spatial variation of the vent communities. Vent populations that cannot adapt to modified flow rates are adversely affected, as is evidenced by high mortality or lower rates of colonization, growth, or reproduction. Substantial changes in biota have been witnessed at several vents, and successional cycles have been proposed for the Galapagos vent fields. Dramatic temporal and spatial variations in vent community structure may also relate to variations in larval dispersal and chance recruitment, as well as biotic interactions.

  4. Influence of a single lightning discharge on the intensity of an air electric field and acoustic emission of near-surface rocks

    Directory of Open Access Journals (Sweden)

    S. E. Smirnov

    2012-10-01

    Full Text Available The effect was observed as a sharp fall of the electric potential gradient from +80 V m−1 down to –21 V m−1. After that the field returned to its normal level according to the formula of the capacitor discharge with 17 s characteristic time. Simultaneously, the response of the acoustic emission of surface rocks in the range of frequencies between 6.5 kHz and 11 kHz was evaluated.

  5. Retrieving eruptive vent conditions from dynamical properties of unsteady volcanic plume using high-speed imagery and numerical simulations

    Science.gov (United States)

    Tournigand, Pierre-Yves; Taddeucci, Jacopo; José Peña Fernandez, Juan; Gaudin, Damien; Sesterhenn, Jörn; Scarlato, Piergiorgio; Del Bello, Elisabetta

    2016-04-01

    Vent conditions are key parameters controlling volcanic plume dynamics and the ensuing different hazards, such as human health issues, infrastructure damages, and air traffic disruption. Indeed, for a given magma and vent geometry, plume development and stability over time mainly depend on the mass eruption rate, function of the velocity and density of the eruptive mixture at the vent, where direct measurements are impossible. High-speed imaging of eruptive plumes and numerical jet simulations were here non-dimensionally coupled to retrieve eruptive vent conditions starting from measurable plume parameters. High-speed videos of unsteady, momentum-driven volcanic plumes (jets) from Strombolian to Vulcanian activity from three different volcanoes (Sakurajima, Japan, Stromboli, Italy, and Fuego, Guatemala) were recorded in the visible and the thermal spectral ranges by using an Optronis CR600x2 (1280x1024 pixels definition, 500 Hz frame rate) and a FLIR SC655 (640x480 pixels definition, 50 Hz frame rate) cameras. Atmospheric effects correction and pre-processing of the thermal videos were performed to increase measurement accuracy. Pre-processing consists of the extraction of the plume temperature gradient over time, combined with a temperature threshold in order to remove the image background. The velocity and the apparent surface temperature fields of the plumes, and their changes over timescales of tenths of seconds, were then measured by particle image velocimetry and thermal image analysis, respectively, of the pre-processed videos. The parameters thus obtained are representative of the outer plume surface, corresponding to its boundary shear layer at the interface with the atmosphere, and may significantly differ from conditions in the plume interior. To retrieve information on the interior of the plume, and possibly extrapolate it even at the eruptive vent level, video-derived plume parameters were non-dimensionally compared to the results of numerical

  6. Concept for a cyclonic spray scrubber as a fission product removal system for filtered containment venting

    Energy Technology Data Exchange (ETDEWEB)

    Lebel, Luke S., E-mail: Luke.Lebel@cnl.ca; Piro, Markus H., E-mail: Markus.Piro@cnl.ca; MacCoy, Reilly, E-mail: Reilly.MacCoy@cnl.ca; Clouthier, Anthony, E-mail: Tony.Clouthier@cnl.ca; Chin, Yu-Shan, E-mail: Sammy.Chin@cnl.ca

    2016-02-15

    Graphical abstract: - Highlights: • A new cyclonic spray scrubber concept for filtered containment venting is presented. • Mechanistic particle removal model paired with discrete particle CFD simulations. • Calculations predict that very high decontamination factors can be achieved. - Abstract: The application of a cyclonic spray scrubber as a technology for filtered containment venting is proposed in this paper. This study has paired a mechanistic model for the kinetic particle coagulation of with Euler–Lagrange discrete particle simulations in order to predict particle decontamination factors. The continuous phase behavior has been investigated using computational fluid dynamics simulations together with phase Doppler anemometry measurements. Calculations show that spray scrubbing of radionuclide-bearing aerosols could be very effective, and predict that decontamination factors can be in excess of 10{sup 6} for micron sized particles and excess of 10{sup 3} for submicron particles. In the wake of the accident at the Fukushima Daiichi Nuclear Power Plant, filtered containment venting is being viewed as an increasingly important severe accident mitigation technology. Cyclonic spray scrubbing could be implemented as a passive technology for decontaminating containment gases in an emergency prior to their discharge to the atmosphere, and is a novel approach for this application.

  7. Microhollow cathode discharges

    Science.gov (United States)

    Schoenbach, K. H.; Moselhy, M.; Shi, W.; Bentley, R.

    2003-07-01

    By reducing the dimensions of hollow cathodes into the hundred micrometer range, stable, direct current, high (atmospheric) pressure glow discharges in rare gases, rare gas-halide mixtures and in air could be generated. The electron energy distribution in these microdischarges is non-Maxwellian, with a pronounced high-energy tail. The high electron energy together with the high gas density, which favors three-body collisions, is the reason for an efficient excimer generation in these microplasmas. Excimer efficiencies from 1% to 9% have been measured for argon, xenon, argon fluoride, and xenon chloride direct current excimer emitters, with a radiant excimer emittance of up to 2 W/cm2 for xenon. Adding small amounts of oxygen to argon has allowed us to generate vacuum ultraviolet line radiation at 130.5 nm with an efficiency approaching 1%. Pulsing xenon discharges with nanosecond electrical pulses has led to an increase in intensity to 15 W/cm2 and to a simultaneous increase in efficiency to more than 20%. Operating the discharges in an abnormal glow mode has allowed us to generate microdischarge arrays without individual ballast. Applications of these plasma arrays are excimer lamps and plasma reactors.

  8. Arc discharge sliding over a conducting surface

    NARCIS (Netherlands)

    Goor, van F.A.; Mitko, S.V.; Ochkin, V.N.; Paramonov, A.P.; Witteman, W.J.

    1997-01-01

    Results of experimental and theoretical studies of the arc discharge which slides over the surface of a conductor are reported. Experiments were performed in air and argon ambients at various pressures. It is found that the velocity of the discharge plasma front depends linearly on the strength of t

  9. COMPARISON OF VENTED AND ABSOLUTE PRESSURE TRANSDUCERS FOR WATER-LEVEL MONITORING IN HANFORD SITE CENTRAL PLATEAU WELLS

    Energy Technology Data Exchange (ETDEWEB)

    MCDONALD JP

    2011-09-08

    Automated water-level data collected using vented pressure transducers deployed in Hanford Site Central Plateau wells commonly display more variability than manual tape measurements in response to barometric pressure fluctuations. To explain this difference, it was hypothesized that vented pressure transducers installed in some wells are subject to barometric pressure effects that reduce water-level measurement accuracy. Vented pressure transducers use a vent tube, which is open to the atmosphere at land surface, to supply air pressure to the transducer housing for barometric compensation so the transducer measurements will represent only the water pressure. When using vented transducers, the assumption is made that the air pressure between land surface and the well bore is in equilibrium. By comparison, absolute pressure transducers directly measure the air pressure within the wellbore. Barometric compensation is achieved by subtracting the well bore air pressure measurement from the total pressure measured by a second transducer submerged in the water. Thus, no assumption of air pressure equilibrium is needed. In this study, water-level measurements were collected from the same Central Plateau wells using both vented and absolute pressure transducers to evaluate the different methods of barometric compensation. Manual tape measurements were also collected to evaluate the transducers. Measurements collected during this study demonstrated that the vented pressure transducers over-responded to barometric pressure fluctuations due to a pressure disequilibrium between the air within the wellbores and the atmosphere at land surface. The disequilibrium is thought to be caused by the relatively long time required for barometric pressure changes to equilibrate between land surface and the deep vadose zone and may be exacerbated by the restriction of air flow between the well bore and the atmosphere due to the presence of sample pump landing plates and well caps. The

  10. Using Large Eddy Simulation for understanding vented gas explosions in the presence of obstacles.

    Science.gov (United States)

    Di Sarli, Valeria; Di Benedetto, Almerinda; Russo, Gennaro

    2009-09-30

    In this work, a validated Large Eddy Simulation model of unsteady premixed flame propagation is used to study the phenomenology underlying vented gas explosions in the presence of obstacles. Computations are run of deflagrating flames in a small-scale combustion chamber closed at the bottom end and open at the opposite face. A single obstacle is centred inside the chamber. Methane-air mixtures of various compositions (ranging from lean to stoichiometric and rich), and obstacles with different area blockage ratios (30, 50 and 70%) and shapes (circular, rectangular and square cross-section in the flow direction) are investigated. All cases are initialized from stagnation. The competition between combustion rate and venting rate allows explaining both number and intensity of the overpressure peaks observed.

  11. El destí en el vent

    OpenAIRE

    2015-01-01

    El projecte de final de grau consisteix en la realització d'un producte audiovisual d'entreteniment. S'ha produït un curtmetratge creatiu utilitzant la tècnica d'animació stop motion. El vídeo narra, a través de dos fulls de paper, un relat inventat que parla de l'amor impossible, "El destí en el vent". El proyecto de fin de grado consiste en la realización de un producto audiovisual de entretenimiento. Se ha producido un cortometraje creativo utilizando la técnica de animación stop mot...

  12. COVIS Detects Interconnections Between Atmospheric, Oceanic and Geologic systems at a Deep Sea Hydrothermal Vent

    Science.gov (United States)

    Bemis, K. G.; Xu, G.; Lee, R.

    2015-12-01

    COVIS (Cabled Observatory Vent Imaging Sonar) is an innovative sonar system designed to quantitatively monitor focused and diffuse flows from deep-sea hydrothermal vent clusters. From 9/2010 to 9/2015, COVIS was connected to the NEPTUNE observatory at Grotto vent in the Main Endeavour Field, JdFR. COVIS monitored plumes and diffuse discharge by transmitting high-frequency (200-400 kHz), pulsed acoustic waves and recording the backscattered signals to yield time series of plume heat and volume transports, plume bending, and diffuse flow area. Temporal variations indicate the rate of hydrothermal plume mixing with the ambient seawater increases with the magnitude of ocean currents. Such current-driven entrainment links the dynamics of a deep-sea hydrothermal plume with oceanic and atmospheric processes. We estimate the direction and relative amplitude of the local bottom currents from the bending angles of the plumes. A comparison with currents from an ADCP (~80 m south of Grotto) reveals significant complexity in the mean bottom flow structure within a hydrothermal vent field. Diffuse flow area, temperature, and faunal densities vary periodically reflecting some combination of tidal pressure and current interactions. The heat transport time series suggests the heat source driving the plume remained relatively steady for 41 months. Local seismic data reveals that increased heat transport in 2000 followed seismic events in 1999 and 2000 and the steady heat flux from 10/2011 to 2/2015 coincided with quiescent seismicity. Such a correlation points to the close linkage of a seafloor hydrothermal system with geological processes. These findings demonstrate the intimate interconnections of seafloor hydrothermal systems with processes spanning the Earth's interior to the sea surface. Further, they (and the time-series acquired by COVIS) testify to the effectiveness and robustness of employing an acoustic-imaging sonar for long-term monitoring of a seafloor hydrothermal

  13. An authoritative global database for active submarine hydrothermal vent fields

    Science.gov (United States)

    Beaulieu, Stace E.; Baker, Edward T.; German, Christopher R.; Maffei, Andrew

    2013-11-01

    The InterRidge Vents Database is available online as the authoritative reference for locations of active submarine hydrothermal vent fields. Here we describe the revision of the database to an open source content management system and conduct a meta-analysis of the global distribution of known active vent fields. The number of known active vent fields has almost doubled in the past decade (521 as of year 2009), with about half visually confirmed and others inferred active from physical and chemical clues. Although previously known mainly from mid-ocean ridges (MORs), active vent fields at MORs now comprise only half of the total known, with about a quarter each now known at volcanic arcs and back-arc spreading centers. Discoveries in arc and back-arc settings resulted in an increase in known vent fields within exclusive economic zones, consequently reducing the proportion known in high seas to one third. The increase in known vent fields reflects a number of factors, including increased national and commercial interests in seafloor hydrothermal deposits as mineral resources. The purpose of the database now extends beyond academic research and education and into marine policy and management, with at least 18% of known vent fields in areas granted or pending applications for mineral prospecting and 8% in marine protected areas.

  14. Where are the undiscovered hydrothermal vents on oceanic spreading ridges?

    Science.gov (United States)

    Beaulieu, Stace E.; Baker, Edward T.; German, Christopher R.

    2015-11-01

    In nearly four decades since the discovery of deep-sea vents, one-third of the length of global oceanic spreading ridges has been surveyed for hydrothermal activity. Active submarine vent fields are now known along the boundaries of 46 out of 52 recognized tectonic plates. Hydrothermal survey efforts over the most recent decade were sparked by national and commercial interests in the mineral resource potential of seafloor hydrothermal deposits, as well as by academic research. Here we incorporate recent data for back-arc spreading centers and ultraslow- and slow-spreading mid-ocean ridges (MORs) to revise a linear equation relating the frequency of vent fields along oceanic spreading ridges to spreading rate. We apply this equation globally to predict a total number of vent fields on spreading ridges, which suggests that ~900 vent fields remain to be discovered. Almost half of these undiscovered vent fields (comparable to the total of all vent fields discovered during 35 years of research) are likely to occur at MORs with full spreading rates less than 60 mm/yr. We then apply the equation regionally to predict where these hydrothermal vents may be discovered with respect to plate boundaries and national jurisdiction, with the majority expected to occur outside of states' exclusive economic zones. We hope that these predictions will prove useful to the community in the future, in helping to shape continuing ridge-crest exploration.

  15. Antarctic marine biodiversity and deep-sea hydrothermal vents.

    Science.gov (United States)

    Chown, Steven L

    2012-01-01

    The diversity of many marine benthic groups is unlike that of most other taxa. Rather than declining from the tropics to the poles, much of the benthos shows high diversity in the Southern Ocean. Moreover, many species are unique to the Antarctic region. Recent work has shown that this is also true of the communities of Antarctic deep-sea hydrothermal vents. Vent ecosystems have been documented from many sites across the globe, associated with the thermally and chemically variable habitats found around these, typically high temperature, streams that are rich in reduced compounds and polymetallic sulphides. The animal communities of the East Scotia Ridge vent ecosystems are very different to those elsewhere, though the microbiota, which form the basis of vent food webs, show less differentiation. Much of the biological significance of deep-sea hydrothermal vents lies in their biodiversity, the diverse biochemistry of their bacteria, the remarkable symbioses among many of the marine animals and these bacteria, and the prospects that investigations of these systems hold for understanding the conditions that may have led to the first appearance of life. The discovery of diverse and unusual Antarctic hydrothermal vent ecosystems provides opportunities for new understanding in these fields. Moreover, the Antarctic vents south of 60°S benefit from automatic conservation under the Convention on the Conservation of Antarctic Marine Living Resources and the Antarctic Treaty. Other deep-sea hydrothermal vents located in international waters are not protected and may be threatened by growing interests in deep-sea mining.

  16. Hydrogen Vent Ground Umbilical Quick Disconnect - Flight Seal Advanced Development

    Science.gov (United States)

    Girard, Doug; Jankowski, Fred; Minich, Mark C.; Yu, Weiping

    2012-01-01

    This project is a team effort between NASA Engineering (NE) and Team QNA Engineering personnel to provide support for the Umbilical Systems Development project which is funded by Advanced Exploration Systems (AES) and 21st Century Launch Complex. Specifically, this project seeks to develop a new interface between the PPBE baselined Legacy SSP LH2 Vent Arm QD probe and SLS vent seal.

  17. 46 CFR 56.50-85 - Tank-vent piping.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Tank-vent piping. 56.50-85 Section 56.50-85 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND APPURTENANCES Design Requirements Pertaining to Specific Systems § 56.50-85 Tank-vent piping. (a) This...

  18. Sawdust discharge rate from aerated hoppers

    Institute of Scientific and Technical Information of China (English)

    Pan Chen; Zhulin Yuan; Chien-Song Chyang; Fu-Xiong Zhuan

    2011-01-01

    This paper presents a numerical and experimental study of the discharge rate of sawdust from an aerated hopper as an important parameter in many industrial processes involving the handling of other granular materials. Numerical experiments are conducted by means of an Eulerian-Eulerian approach coupled with the kinetic theory of granular flow (KTGF). Emphasis is given to the effects of particle size, hopper outlet width, hopper half angle, aeration height and air flow rate. The results show that the discharge rate is significantly affected by hopper outlet width, particle size and air flow rate, but is not sensitive to the hopper half angle and aeration height: increasing hopper outlet width or air flow rate increases discharge rate, while increasing particle size decreases discharge rate. Close agreement between numerical predictions and experimental results is obtained.

  19. Parallel Operation of Microhollow Cathode Discharges

    Science.gov (United States)

    Stark, Robert H.; Shi, Wenhui; Schoenbach, Karl H.

    1998-10-01

    The dc current-voltage characteristics of microhollow cathode discharges has, in certain ranges of the discharge current, a positive slope [1]. In these current ranges it should be possible to operate multiple discharges in parallel without individual ballast, and be used as flat panel excimer lamps [2] or large area plasma cathodes. In order to verify this hypothesis we have studied the parallel operation of two microhollow cathode discharges of 100 micrometer hole diameter in argon at pressures from 100 Torr to 800 Torr. Stable dc operation of the two discharges, without individual ballast, was obtained if the voltage-current characteristics of the individual discharges had a positive slope greater than 10 V/mA over a voltage range of more than 5 to obtain parallel operation over the entire current range of the microhollow cathode discharges, which includes regions of negative differential conductivity, we have replaced the metal anode by a semi-insulating semiconductor, which serves as distributed resistive ballast. With this method, we were able to ignite and sustain an array of dc microhollow cathode discharges over a wide range of pressure and discharge current. [1] K.H.Schoenbach et al. Appl. Phys. Lett. 68, 13 (1996). [2] A.El-Habachi and K.H.Schoenbach, APL. 72, 1 (1998). This work was funded by the Department of Energy, Advanced Energy Division, and by the Air Force Office of Scientific Research (AFOSR) in cooperation with the DDR&E Air Plasma Ramparts MURI Program.

  20. Eye muscle repair - discharge

    Science.gov (United States)

    ... Lazy eye repair - discharge; Strabismus repair - discharge; Extraocular muscle surgery - discharge ... You or your child had eye muscle repair surgery to correct eye muscle ... term for crossed eyes is strabismus. Children most often ...

  1. Tennis elbow surgery - discharge

    Science.gov (United States)

    ... epicondylitis surgery - discharge; Lateral tendinosis surgery - discharge; Lateral tennis elbow surgery - discharge ... long as you are told. This helps ensure tennis elbow will not return. You may be prescribed a ...

  2. Asthma - child - discharge

    Science.gov (United States)

    Pediatric asthma - discharge; Wheezing - discharge; Reactive airway disease - discharge ... Your child has asthma , which causes the airways of the lungs to swell and narrow. In the hospital, the doctors and nurses helped ...

  3. Differences in recovery between deep-sea hydrothermal vent and vent-proximate communities after a volcanic eruption

    NARCIS (Netherlands)

    Gollner, S.; Govenar, B.; Martinez Arbizu, P.; Mills, S.; Le Bris, N.; Weinbauer, M.; Shank, T.M.; Bright, M.

    2015-01-01

    Deep-sea hydrothermal vents and the surrounding basalt seafloor are subject to major natural disturbance events such as volcanic eruptions. In the near future, anthropogenic disturbance in the form of deep-sea mining could also significantly affect the faunal communities of hydrothermal vents. In th

  4. Unit vent airflow measurements using a tracer gas technique

    Energy Technology Data Exchange (ETDEWEB)

    Adams, D.G. [Union Electric Company, Fulton, MO (United States); Lagus, P.L. [Lagus Applied Technology, Inc., San Diego, CA (United States); Fleming, K.M. [NCS Corp., Columbus, OH (United States)

    1997-08-01

    An alternative method for assessing flowrates that does not depend on point measurements of air flow velocity is the constant tracer injection technique. In this method one injects a tracer gas at a constant rate into a duct and measures the resulting concentration downstream of the injection point. A simple equation derived from the conservation of mass allows calculation of the flowrate at the point of injection. Flowrate data obtained using both a pitot tube and a flow measuring station were compared with tracer gas flowrate measurements in the unit vent duct at the Callaway Nuclear Station during late 1995 and early 1996. These data are presented and discussed with an eye toward obtaining precise flowrate data for release rate calculations. The advantages and disadvantages of the technique are also described. In those test situations for which many flowrate combinations are required, or in large area ducts, a tracer flowrate determination requires fewer man-hours than does a conventional traverse-based technique and does not require knowledge of the duct area. 6 refs., 10 figs., 6 tabs.

  5. Solution gas flaring and venting at Alberta primary crude bitumen operations

    Energy Technology Data Exchange (ETDEWEB)

    Ruff, C. [Alberta Energy and Utilities Board, Calgary, AB (Canada)

    2005-11-01

    The Alberta Energy and Utilities Board is mandated by the Government of Alberta to ensure fair, responsible development and delivery of energy resources and utilities services in Alberta while maintaining the best public interest. One of the agencies' priorities is the reduction of solution gas flaring and venting. The performance of solution gas flaring and venting in Alberta and best practices respecting solution gas conservation are discussed. Data was presented on solution gas production, solution gas conserved, and solution gas conservation efficiency. The paper described best practices solutions such as increased gas to oil (GOR) test frequency; predetermination of economic gas conservation; collaboration with county gas utilities; and utilization of portable and scalable gas compression. The paper also presents a discussion of the Clean Air Strategic Alliance (CASA), a non-profit multistakeholder that recommended enhancements to Guide 60. Requirements discussed include the requirement to conserve solution gas at certain sites exceeding established flare and vent volumes, gas conservation prebuild requirements, and enhanced economic evaluation process. 5 figs.

  6. A conservation vent is not a safe substitute for a flame arrester

    Energy Technology Data Exchange (ETDEWEB)

    Siestrup, Francisco Hubertus Grosse [Protego Leser do Brasil Ltda., Rio de Janeiro, RJ (Brazil)

    2009-07-01

    For several decades state organizations and engineering societies have published strict engineering guidelines for the design and safe management of storage tanks. Storage tanks in refineries and chemical plants can contain flammable and hazardous chemicals. Accidents in these systems resulting from explosions can cause million dollar property loss and production interruption. In severe cases lawsuits may result and companies can even be driven into bankruptcy. This article focuses on tests which have been conducted by the PROTEGO Research and Development Group in Braunschweig, Germany. Latest research, in which conservation vents have been tested in accordance to the new ISO 16852 test method, have proven that conservation vents cannot be used to substitute a flame arrester if potentially explosive atmospheres are present in storage tanks. This research was conducted during the development of ISO 28300 and the test results are considered in this standard. This paper will prove that the use of conservation vents to protect tanks from atmospheric explosion is not a reliable protection method when the vapor/air mixtures in the tank have a concentration between the Upper and Lower Explosive Limits (UEL and LEL). This is very common for Ethanol storage which is globally in evidence. (author)

  7. Vented gas deflagrations; A detailed mathematical model tuned on a large set of experimental data

    Energy Technology Data Exchange (ETDEWEB)

    Canu, P.; Rota, R.; Carra, S. (Politecnico di Milano, Milan (Italy). Ist. di Chimica Fisica); Morbidelli, M. (Dipt. di Ingegneria Chimica e Materiali, Universita di Cagliari, 09123 Cagliari (IT))

    1990-04-01

    A detailed mathematical model based on conservation laws and physiochemical relationships has been developed to simulate vented gas deflagrations. The main phenomena involved are described using a priori relationships whenever well-established quantitative theories are available. In the case of flame front acceleration due to flame wrinkling in closed vessels or to turbulence induced by vent opening, where such theories do not exist two empirical relationships have been introduced. These have been tuned by comparison with a collection of about 160 literature experimental data, covering a wide range of values for vessel volume (0.001--199 m{sup 3}), initial pressure (0.1--0.4 MPa), and bursting pressure (0.1--2.96 MPa) and including various vessel shapes and fuel-air compositions. The obtained average relative error in the maximum explosion pressure values is equal to 10.4%, comparable with the uncertainty inherent to the vented deflagration data considered. A dedicated computer algorithm has been developed to provide a fast running simulation program (i.e., about 10 seconds of CPU time on a VAX 8650 for a typical deflagration process).

  8. ACL reconstruction - discharge

    Science.gov (United States)

    Anterior cruciate ligament reconstruction - discharge; ACL reconstruction - discharge ... had surgery to reconstruct your anterior cruciate ligament (ACL). The surgeon drilled holes in the bones of ...

  9. Heating dominated inception of pulsed discharges

    Science.gov (United States)

    Agnihotri, Ashutosh; Hundsdorfer, Willem; Ebert, Ute

    2016-09-01

    We simulate the inception of pulsed discharges with heating as the driving agent that leads to spark formation. To understand the phenomenon, we developed a 2D-cylindrically symmetric model that couples the electric discharge dynamics with the background gas dynamics. To capture the ion dynamics well, we reduced the classical drift-diffusion-reaction model of electric discharges to the timescale of ion motion. Additionally, we include secondary emission of electrons from the cathode. We employed the model to study electrical breakdown in air at STP conditions between planar electrodes under the application of pulsed voltages. Our model captures space-charge effects, thermal shocks and induced pressure waves. We observe a cycle of discharge pulses heating the gas and the thermal expansion helping the discharge. This cycle might either lead to spark formation or to discharge decay.

  10. 大气压直流正电晕放电暂态空间电荷分布仿真研究%Numerical simulation of transient space charge distribution of DC positive corona discharge under atmospheric pressure air

    Institute of Scientific and Technical Information of China (English)

    廖瑞金; 伍飞飞; 刘兴华; 杨帆; 杨丽君; 周之; 翟蕾

    2012-01-01

    本文提出了流体一化学动理学二维正电晕放电混合模型,该模型包含12种粒子间的27种化学反应,并且考虑光电离的影响.此外,在实验室内对该模型开展试验验证,单次脉冲波形及伏安特性曲线符合较好.基于上述模型,本文研究了在外施电压3kV时棒一板电极正电晕放电过程中的电场分布、电子温度分布、空间电荷分布的发展规律,并对电晕放电过程中粒子的成分进行了详细分析,讨论了电子、正负离子、中性粒子在放电过程中的生成规律及对电晕放电的影响.结果表明:在整个电晕放电过程中,电子温度分布和电场强度分布曲线相似,电子密度维持在10^19m-3左右,只发现带正电的等离子体特征.O4+密度是放电过程中数量最多的正离子,O2+和N2+在二次电子发射过程中具有重要作用,O2-离子和O分别是负离子和中性粒子中数量最多的粒子,由于负离子和中性粒子在电晕放电过程中数量较小,因而起的作用相对较小.%Corona discharges are usually generated at sharp points, edges or on thin wires where the electric field is strongly concentrated. With the rapid development of extra and ultra high-voltage transmission lines, the air corona discharge becomes one of the critical problems associated with high-voltage lines, which can lead to the deterioration of insulation systems, power loss, radio noise. Corona discharge studies have been undertaken for many years, not only because of the scientific interest in the corona mechanism but also because of its practical engineering importance. Transient space charge distribution effect that is one of the important canses in the process of corona discharge, is closely related to the corona discharge mechanism and onset, self-sustaining. In this paper, we present an improved self-consistent, multi-component and two-dimensional plasma hybrid model for simulating the

  11. The Chthonic Charging of Volcanic Flows: The Generation of Vent Lightning

    Science.gov (United States)

    Méndez Harper, J.; Dufek, J.

    2015-12-01

    While volcanic lightning has been reported for millennia, the physics that generate charge in plumes still require clarification. Lightning observations during the Augustine (2006) and Redoubt (2009) eruptions have revealed a new form of lightning: nearly continuous, vent discharges associated with the explosive phase of the eruption. Vent lightning is often small (10-100 m in length) and disorganized, suggesting the existence of multiple, transient charge centers proximal to the volcanic vent. Thomas et al., 2007 and Behnke et al., 2012 have postulated that this form of lightning is driven by fragmentation charging [James et al., 2008]. However, triboelectrification—frictional charging arising from particle-particle collisions as material is advected up to the vent—should also play an important role. Because tribocharging is modulated by collision rates and energies, it is within the conduit and the gas-thrust regions that this frictional process should be most efficient. Indeed, the work of Cimarelli et al., 2014 has suggested that lightning can be generated at the vent via triboelectric charging alone. Using an energy-based comparison, we investigate the relative efficiencies of fracto- and triboelectric charging. To generate charged particles via a fragmentation process, we employ Prince Rupert's Drops (PRDs), meta-stable, tadpole-shaped structures formed by quenching molten glass in water. While a PDR's head is extremely strong, even the slightest damage to the tail causes explosive disintegration of the drop [Silverman et al., 2012]. A set of PDRs are disrupted in a controlled environment and the charge on the resulting particles is measured using a set of Faraday cups. The energy density associated with the breaking of PRDs is on the order of 105-106 J/m3. Then, to investigate tribocharging at similar energies, we eject spherical particles at high velocities, producing particle-particle collisions in a novel Faraday cube sensor. Our setup allows us to

  12. The role of dense brines in the formation of vent-distal sedimentary-exhalative (SEDEX) lead-zinc deposits: field and laboratory evidence

    Science.gov (United States)

    Sangster, Donald F.

    2002-03-01

    A majority of the world's sediment-hosted exhalative (SEDEX) lead-zinc deposits are vent-distal. They are not underlain by a discordant alteration zone or stockwork vent complex that would indicate the path by which ore fluids reached the seafloor. The absence of a vent complex, together with sulfide mineral replacement of host rock mineral assemblages has led several investigators to suggest that, in spite of the well-layered nature of these deposits, mineralization was formed by sub-seafloor lateral migration of ore fluids along permeable strata. Field observations, supported by simple laboratory experiments, however, suggest an alternative process for characterizing the genesis of vent-distal SEDEX deposits. Cool, saline brines (e.g., ~120 °C and >15 wt% NaCl equiv.) are denser than seawater and, upon discharging into the sea, would flow away from the discharge vent as bottom-hugging fluids, similar to the behavior of turbidity currents. Their high densities and velocities prevent them from mixing with overlying seawater, thereby precluding significant cooling and dilution of the ore fluid. Upon coming to rest in a seafloor depression, the addition of H2S and/or dilution of the ore fluids to lower salinities result in the eventual precipitation of a vent-distal SEDEX deposit. Furthermore, the dense ore-forming fluid can sink into permeable sediments beneath the brine pool by displacing less dense pore water. The ore fluids are thus capable of effectively overprinting and/or replacing pre-existing minerals in the consolidating sediment pile.

  13. Preliminary comparisons between measurements and model calculations for the TMI venting of /sup 85/Kr

    Energy Technology Data Exchange (ETDEWEB)

    Dickerson, M.H.

    1980-08-01

    ARAC was on-line calculating hourly concentration values during the TMI-2 venting of /sup 85/Kr gas from June 28 to July 11, 1980. During this time hourly isopleths of normalized instantaneous concentration were calculated and transmitted to EPA in Middletown, PA. These isopleths were used to help locate the EPA and Penn State mobile air samplers and they were used for comparison to the EPA fixed 24 hr sampler measurements and the DOE helicopter measurements. This report summarizes preliminary comparisons for the EPA fixed samplers and the DOE helicopters.

  14. Measurement of the velocity field behind the automotive vent

    Directory of Open Access Journals (Sweden)

    Jedelský Jan

    2012-04-01

    Full Text Available Passenger comfort in a personal vehicle cabin strongly depends on the appropriate function of the cabin ventilation system. Great attention is therefore paid to the effective functioning of the automotive vents. Various techniques can be employed to evaluate the proper formation of the flow behind the ventilation outlet. Constant Temperature Anemometry (CTA was used in our case for accurate measurement of the velocity field and consequent assessment of jet boundaries and jet axis. A novel methodology has been developed for the simulation of realistic conditions when using just a single vent under laboratory conditions instead of the complete vehicle ventilation system. A special technique has also been developed for determination of the terminal inclination angles of vent vanes for the particular vent type, which can be completely closed by the adjustable horizontal vanes. A two wire CTA probe was used for measurement of the actual velocity over predefined planes, which were specified according to smoke visualization. Mean velocities and the turbulence intensity were evaluated on the basis of the obtained data and are presented in a form of charts. Both jet boundary and orientation of the jet for a given setup of the vent are important characteristics of particular vent type. Effectiveness of different vents could be compared using our methodology and hence contribute to development of advanced ventilation system.

  15. Measurement of the velocity field behind the automotive vent

    Science.gov (United States)

    Ležovič, Tomáš; Lízal, František; Jedelský, Jan; Jícha, Miroslav

    2012-04-01

    Passenger comfort in a personal vehicle cabin strongly depends on the appropriate function of the cabin ventilation system. Great attention is therefore paid to the effective functioning of the automotive vents. Various techniques can be employed to evaluate the proper formation of the flow behind the ventilation outlet. Constant Temperature Anemometry (CTA) was used in our case for accurate measurement of the velocity field and consequent assessment of jet boundaries and jet axis. A novel methodology has been developed for the simulation of realistic conditions when using just a single vent under laboratory conditions instead of the complete vehicle ventilation system. A special technique has also been developed for determination of the terminal inclination angles of vent vanes for the particular vent type, which can be completely closed by the adjustable horizontal vanes. A two wire CTA probe was used for measurement of the actual velocity over predefined planes, which were specified according to smoke visualization. Mean velocities and the turbulence intensity were evaluated on the basis of the obtained data and are presented in a form of charts. Both jet boundary and orientation of the jet for a given setup of the vent are important characteristics of particular vent type. Effectiveness of different vents could be compared using our methodology and hence contribute to development of advanced ventilation system.

  16. Control Systems for Platform Landings Cushioned by Air Bags

    Science.gov (United States)

    1987-07-01

    feedback control system (39) displayed behavior quite different from the other two controls. Many different pairs of values for Pi and P2 were found that...those of the paramameters. The control instructions, starting at line 23, are for the particular feedback control * " system studied in the report... feedback control system , see Equation (39) Pa Standard atmospheric pressure PC Critical (sonic) pressure in vent Q Dimensionless air-speed in vent q Air

  17. A novel vented microisolation container for caging animals: microenvironmental comfort in a closed-system filter cage.

    Science.gov (United States)

    Rivard, G F; Neff, D E; Cullen, J F; Welch, S W

    2000-01-01

    We designed a closed-system cage with vent ports that would allow continuous airflow in the occupied cage to ensure adequate ventilation and gas exchange. In this system, the metabolic heat loads of mice generate upward thermal air currents. Heat exits via the exhaust port, and room air enters via the intake port, providing adequate ventilation. Simulations based on computational fluid dynamics (CFD) helped us to optimize the cage's design. CFD simulations and smoke visualizations with a feeder-trough assembly illustrated the one-pass air circulation pattern and the lack of air recirculation, turbulence, and dead air space in our system. We used hot-film anemometry and smoke-test methodologies to show that adequate ventilation was provided. In a room with still air (0 air changes per hour [ACH]), a cage fitted with double wire-cloth filters (40 mesh size) and occupied by five mice has at least 12 ACH, whereas the same cage occupied by one mouse has 6 ACH. After five mice had occupied the cage for a week, its average temperature was 0.58C, relative humidity was 34%, and ammonia concentration was 3 ppm higher than that of the room. Our novel vented microisolation cage provides adequate intracage ACH, isolates mice from environmental contaminants, and contains allergenic particles within the cage in an environment appropriate for the species.

  18. Сombined Thermal Insulating Module of Mounted Vented Facades

    Directory of Open Access Journals (Sweden)

    Ryabukhina Svetlana

    2016-01-01

    Full Text Available In order to define an optimum type of mounted vented facades among the existing ones, comparative analysis of two façade modules has been conducted. The first module type is a widespread standard module of hinged vented facade and the second type is less applicable combined thermal insulating module. Those two technologies were compared thermal engineering and energy efficiency parameters. It was defined that the application of a thermal insulating module with combined insulation system improves thermal engineering parameters of the building as well as leads to a substantial savings. This article exposes innovative materials and structure of vented facades which can be applied in modern construction.

  19. A Review of Flaring and Venting at UK Offshore Oilfields

    OpenAIRE

    Stewart, Jamie R

    2014-01-01

    This study aims to re-address the issue of flaring and venting of reproduced gases in carbon dioxide enhanced oil recovery (CO2EOR) projects. Whilst a number of studies have not recognised the impact of flaring/venting in CO2EOR developments, a study completed at Scottish Carbon Capture and Storage (SCCS) “Carbon Accounting for Carbon Dioxide Enhanced Oil Recovery” highlighted the significant control that flaring/venting of reproduced gases may have on a projects life cycle greenhouse gas emi...

  20. Optimization of working parameters for double-dielectric non-thermal plasma reactor and spectrography analysis of air discharge%双介质低温等离子体反应器工作参数优化及空气放电光谱分析

    Institute of Scientific and Technical Information of China (English)

    王军; 李超; 唐炜; 何涛; 王兴华

    2015-01-01

    The working principal of selective catalytic reduction (SCR) system is that urea solution, whose mass fraction is 32.5%, is injected into exhaust pipe. NH3 and HNCO are generated and mixed with NOx under the condition of high-temperature exhaust. Finally, N2 and H2O are generated in the catalytic reduction reaction of NH3 and NOx. In the case that NO accounts for 90% or even more in NOxof the diesel engine exhaust, the standard SCR reaction plays a dominant role when using SCR system to deal with NOx of the diesel engine exhaust. This reaction can provide high reduction efficiency when the exhaust temperature is between 300 and 450℃. However, the reduction efficiency of NOx will drop rapidly at lower exhaust temperature. So how to improve the reduction efficiency of NOx at lower exhaust temperature is an urgent problem to be solved. Non-thermal plasma (NTP) technology combined with SCR system is one of the most effective means to solve this problem. Active substances, generated in NTP reactor, can oxidize the part of NO from diesel exhaust to NO2 and improve the conversion efficiency of NOx at lower exhaust temperature. The ideal working parameters selected in experiment, can not only increase the concentration of active substances, but also avoid combining main gas components in exhaust such as N2 and O2. A test system of a double-dielectric non-thermal plasma reactor was established to conduct the air discharge test. To study the effect of working parameters on the performance of double-dielectric non-thermal plasma reactor, the changing rules of the volume fractions of NO and NO2 with several parameters such as discharge voltage peak-peak value, discharge frequency and air flow were researched. The results showed that, discharge frequency had great influence on the volume fractions of NO and NO2. Reaction mechanism of air discharge in the NTP reactor changed as discharge frequency changed. The volume fractions of NO and NO2 grew linearly as discharge voltage

  1. Analysis of Discharge Fault in 35 kV Dry-type Air-Core Reactor%一起35 kV干式空心电抗器放电故障分析

    Institute of Scientific and Technical Information of China (English)

    张宁; 李洪伟

    2014-01-01

    本文介绍了一起500 kV变电站35 kV干式空心电抗器在运行当中发生放电烧损的故障情况,通过现场检查、试验,结合故障电抗器的解体检查结果,对故障原因进行了深入分析,发现故障的主要原因是由于在强磁场下涡流产生温升,破坏了电抗器本身绝缘,本文对防止同类故障的发生具有一定的借鉴意义。%In this paper, a fault of burn-out of 35 kV dry-type air-core reactor due to discharge in the operation at 500 kV substation is introduced. The reason of the fault is analyzed through site inspec-tion, test and disassembly inspection result of the faulty reactor. It is caused by high temperature rise caused by eddy current at strong magnetic field resulting to insulation damage of the reactor it-self. The analysis result has a definite reference to similar fault to be prevented.

  2. 40 CFR 63.172 - Standards: Closed-vent systems and control devices.

    Science.gov (United States)

    2010-07-01

    ... olfactory indications of leaks. (2) If the vapor collection system or closed-vent system is constructed of... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Standards: Closed-vent systems and... Standards: Closed-vent systems and control devices. (a) Owners or operators of closed-vent systems...

  3. Calculation and analysis of hydrogen volume concentrations in the vent pipe rigid proposed for NPP-L V; Calculo y analisis de concentraciones volumetricas de hidrogeno en el tubo de venteo rigido propuesto para la CNLV

    Energy Technology Data Exchange (ETDEWEB)

    Gomez T, A. M.; Xolocostli M, V. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Lopez M, R.; Filio L, C. [Comision Nacional de Seguridad Nuclear y Salvaguardias, Dr. Jose Ma. Barragan No. 779, Col. Narvarte, 03020 Mexico D. F. (Mexico); Royl, P., E-mail: armando.gomez@inin.gob.mx [Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz I, D-76344 Eggenstein-Leopoldshafen (Germany)

    2014-10-15

    In 2012 was modeled of primary and secondary container of the nuclear power plant of Laguna Verde (NPP-L V) for the CFD Gas-Flow code. These models were used to calculate hydrogen volume concentrations run release the reactor building in case of a severe accident. The results showed that the venting would produce detonation conditions in the venting level (level 33) and flammability at ground level of reload. One of the solutions to avoid reaching critical concentrations (flammable or detonable) inside the reactor building and thus safeguard the contentions is to make a rigid venting. The rigid vent is a pipe connected to the primary container could go to the level 33 of the secondary container and style fireplace climb to the top of the reactor building. The analysis of hydrogen transport inside the vent pipe can be influenced by various environmental criteria and factors vent, so a logical consequence of the 2012 analysis is the analysis of the gases transport within said pipe to define vent ideal conditions. For these evaluations the vent pipe was modeled with a fine mesh of 32 radial interior nodes and a coarse mesh of 4 radial interior nodes. With three-dimensional models were realized calculations that allow observing the influence of heat transfer in the long term, i.e. a complete analysis of exhaust (approx. 700 seconds). However, the most interesting results focus on the first milliseconds, when the H{sub 2} coming from the atmosphere of the primary container faces the air in the vent pipe. These first milliseconds besides allowing evaluating the detonation criteria in great detail in the different tubular sections similarly allow evaluating the pressure wave that occurs in the pipe and that at some point slows to the fluid on the last tubular section and could produce a detonation inside the pipe. Results are presented for venting fixed conditions, showing possible detonations into the pipe. (Author)

  4. Optical Detection of Organic Chemical Biosignatures at Hydrothermal Vents

    Science.gov (United States)

    Conrad, P. G.; Lane, A. L.; Bhartia, R.; Hug, W. H.

    2004-01-01

    We have developed a non-contact, optical life detection instrument that can detect organic chemical biosignatures in a number of different environments, including dry land, shallow aqueous, deep marine or in ice. Hence, the instrument is appropriate as a biosignature survey tool both for Mars exploration or in situ experiments in an ice-covered ocean such as one might wish to explore on Europa. Here, we report the results we obtained on an expedition aboard the Russian oceanographic vessel Akademik Mstislav Keldysh to hydrothermal vent sites in the Pacific Ocean using our life detection instrument MCDUVE, a multichannel, deep ultraviolet excitation fluorescence detector. MCDUVE detected organic material distribution on rocks near the vent, as well as direct detection of organisms, both microbial and microscopic. We also were able to detect organic material issuing directly from vent chimneys, measure the organic signature of the water column as we ascended, and passively observe the emission of light directly from some vents.

  5. Antarctic marine biodiversity and deep-sea hydrothermal vents.

    Directory of Open Access Journals (Sweden)

    Steven L Chown

    2012-01-01

    Full Text Available The diversity of many marine benthic groups is unlike that of most other taxa. Rather than declining from the tropics to the poles, much of the benthos shows high diversity in the Southern Ocean. Moreover, many species are unique to the Antarctic region. Recent work has shown that this is also true of the communities of Antarctic deep-sea hydrothermal vents. Vent ecosystems have been documented from many sites across the globe, associated with the thermally and chemically variable habitats found around these, typically high temperature, streams that are rich in reduced compounds and polymetallic sulphides. The animal communities of the East Scotia Ridge vent ecosystems are very different to those elsewhere, though the microbiota, which form the basis of vent food webs, show less differentiation. Much of the biological significance of deep-sea hydrothermal vents lies in their biodiversity, the diverse biochemistry of their bacteria, the remarkable symbioses among many of the marine animals and these bacteria, and the prospects that investigations of these systems hold for understanding the conditions that may have led to the first appearance of life. The discovery of diverse and unusual Antarctic hydrothermal vent ecosystems provides opportunities for new understanding in these fields. Moreover, the Antarctic vents south of 60°S benefit from automatic conservation under the Convention on the Conservation of Antarctic Marine Living Resources and the Antarctic Treaty. Other deep-sea hydrothermal vents located in international waters are not protected and may be threatened by growing interests in deep-sea mining.

  6. Experimental Study of Effect of Vents in Thermal Ventilation

    Institute of Scientific and Technical Information of China (English)

    LIU Dong; LIU Xiao-yu; ZHUANG Jiang-ting; SHEN Hui

    2009-01-01

    The effects of vents on thermal ventilation to save energy in the cold roUing workshop of Baosteel were investigated.According to the scale modeling theory,a small chamber was established.The details about construction of experiment On thermal ventilation and the preparation and arrangement of apparatus were dis-cussed,and then the effects of vents on thermal ventilation were studied through experiments,which includes the temperature distribution,the volume of ventilation,the temperature difference between inlets and outlets,the neutral plane,and the effective thermal coefficient of thermal natural ventilation.Based on this,the effects of natural ventilation based on varied area of inlets and oudets and those of vents on one side and on different sides were compared.According to the experiments,the area of inlet vents and outlet vents affect the tempera-ture distribution in chamber, and their effects on ventilation volume are difierent,but the effects of vents in sin-gle side or different sides aare the same under the condition that only thermal ventilation is considered.

  7. Carbon Dioxide Washout Testing Using Various Inlet Vent Configurations in the Mark-III Space Suit

    Science.gov (United States)

    Korona, F. Adam; Norcross, Jason; Conger, Bruce; Navarro, Moses

    2014-01-01

    Requirements for using a space suit during ground testing include providing adequate carbon dioxide (CO2) washout for the suited subject. Acute CO2 exposure can lead to symptoms including headache, dyspnea, lethargy, and eventually unconsciousness or even death. Symptoms depend on several factors including inspired partial pressure of CO2 (ppCO2), duration of exposure, metabolic rate of the subject, and physiological differences between subjects. Computational Fluid Dynamics (CFD) analysis has predicted that the configuration of the suit inlet vent has a significant effect on oronasal CO2 concentrations. The main objective of this test was to characterize inspired oronasal ppCO2 for a variety of inlet vent configurations in the Mark-III suit across a range of workload and flow rates. Data and trends observed during testing along with refined CFD models will be used to help design an inlet vent configuration for the Z-2 space suit. The testing methodology used in this test builds upon past CO2 washout testing performed on the Z-1 suit, Rear Entry I-Suit, and the Enhanced Mobility Advanced Crew Escape Suit. Three subjects performed two test sessions each in the Mark-III suit to allow for comparison between tests. Six different helmet inlet vent configurations were evaluated during each test session. Suit pressure was maintained at 4.3 psid. Suited test subjects walked on a treadmill to generate metabolic workloads of approximately 2000 and 3000 BTU/hr. Supply airflow rates of 6 and 4 actual cubic feet per minute were tested at each workload. Subjects wore an oronasal mask with an open port in front of the mouth and were allowed to breathe freely. Oronasal ppCO2 was monitored real-time via gas analyzers with sampling tubes connected to the oronasal mask. Metabolic rate was calculated from the CO2 production measured by an additional gas analyzer at the air outlet from the suit. Real-time metabolic rate measurements were used to adjust the treadmill workload to meet

  8. CO2 Washout Testing Using Various Inlet Vent Configurations in the Mark-III Space Suit

    Science.gov (United States)

    Korona, F. Adam; Norcross, Jason; Conger, Bruce; Navarro, Moses

    2014-01-01

    Requirements for using a space suit during ground testing include providing adequate carbon dioxide (CO2) washout for the suited subject. Acute CO2 exposure can lead to symptoms including headache, dyspnea, lethargy and eventually unconsciousness or even death. Symptoms depend on several factors including inspired partial pressure of CO2 (ppCO2), duration of exposure, metabolic rate of the subject and physiological differences between subjects. Computational Fluid Dynamic (CFD) analysis has predicted that the configuration of the suit inlet vent has a significant effect on oronasal CO2 concentrations. The main objective of this test was to characterize inspired oronasal ppCO2 for a variety of inlet vent configurations in the Mark-III suit across a range of workload and flow rates. Data and trends observed during testing along with refined CFD models will be used to help design an inlet vent configuration for the Z-2 space suit. The testing methodology used in this test builds upon past CO2 washout testing performed on the Z-1 suit, Rear Entry I-Suit (REI) and the Enhanced Mobility Advanced Crew Escape Suit (EM-ACES). Three subjects performed two test sessions each in the Mark-III suit to allow for comparison between tests. Six different helmet inlet vent configurations were evaluated during each test session. Suit pressure was maintained at 4.3 psid. Suited test subjects walked on a treadmill to generate metabolic workloads of approximately 2000 and 3000 BTU/hr. Supply airflow rates of 6 and 4 actual cubic feet per minute (ACFM) were tested at each workload. Subjects wore an oronasal mask with an open port in front of the mouth and were allowed to breathe freely. Oronasal ppCO2 was monitored real-time via gas analyzers with sampling tubes connected to the oronasal mask. Metabolic rate was calculated from the total oxygen consumption and CO2 production measured by additional gas analyzers at the air outlet from the suit. Real-time metabolic rate measurements were

  9. Payload bay atmospheric vent airflow testing at the Vibration and Acoustic Test Facility

    Science.gov (United States)

    Johnston, James D., Jr.

    1988-01-01

    Several concerns related to venting the Space Shuttle Orbiter payload bay during launch led to laboratory experiments with a flight-type vent box installed in the wall of a subsonic wind tunnel. This report describes the test setups and procedures used to acquire data for characterization of airflow through the vent box and acoustic tones radiated from the vent-box cavity. A flexible boundary-layer spoiler which reduced the vent-tone amplitude is described.

  10. Hydrogen risk in the Containment Filtered Venting System

    Energy Technology Data Exchange (ETDEWEB)

    Na, Young Su; Ha, Kwang Soon [KAERI, Daejeon (Korea, Republic of); Cho, Song-Won [NSE, Daejeon (Korea, Republic of)

    2015-05-15

    It was observed that the thermal hydraulic conditions in the CFVS (Containment Filtered Venting System) vessel sharply changed markedly, especially the steam condensation in the early CFVS operation can affect the hydrogen behavior such as the combustion. This paper summarizes the calculated results on hydrogen concentration in the CFVS vessel, which was presented at The Ninth Korea-Japan Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS9) last year. The MELCOR computer code calculated the thermal-hydraulic conditions in the containment building of OPR 1000, and in the cylindrical CFVS vessel with 3 m in diameter and 6.5 m in height under an SBO. After the operation of the CFVS, the pressure and temperature in the containment building decreased, and those in the CFVS vessel jumped from the initial conditions of atmosphere pressure and room temperature. These big differences of thermal-hydraulic conditions can make the volumetric concentrations of steam and gas mixtures in the CFVS vessel to be changed in comparison with those in the containment building. The volumetric concentration of hydrogen increased from 6% in the containment to 14% in the CFVS vessel after the operation of the CFVS, while the concentration of steam decreased from 58% in the containment to 3% in the CFVS vessel. The increased volumetric concentration of hydrogen (14%) with the other concentrations of steam (3%) and air (60%) in the CFVS vessel exists within the region of the burn limit in the Shapiro diagram. This possibility of the hydrogen combustion can threaten the integrity of the CFVS.

  11. Geology, sulfide geochemistry and supercritical venting at the Beebe Hydrothermal Vent Field, Cayman Trough

    Science.gov (United States)

    Webber, Alexander P.; Roberts, Stephen; Murton, Bramley J.; Hodgkinson, Matthew R. S.

    2015-09-01

    The Beebe Vent Field (BVF) is the world's deepest known hydrothermal system, at 4960 m below sea level. Located on the Mid-Cayman Spreading Centre, Caribbean, the BVF hosts high temperature (˜401°C) "black smoker" vents that build Cu, Zn and Au-rich sulfide mounds and chimneys. The BVF is highly gold-rich, with Au values up to 93 ppm and an average Au:Ag ratio of 0.15. Gold precipitation is directly associated with diffuse flow through "beehive" chimneys. Significant mass-wasting of sulfide material at the BVF, accompanied by changes in metal content, results in metaliferous talus and sediment deposits. Situated on very thin (2-3 km thick) oceanic crust, at an ultraslow spreading centre, the hydrothermal system circulates fluids to a depth of ˜1.8 km in a basement that is likely to include a mixture of both mafic and ultramafic lithologies. We suggest hydrothermal interaction with chalcophile-bearing sulfides in the mantle rocks, together with precipitation of Au in beehive chimney structures, has resulted in the formation of a Au-rich volcanogenic massive sulfide (VMS) deposit. With its spatial distribution of deposit materials and metal contents, the BVF represents a modern day analogue for basalt hosted, Au-rich VMS systems.

  12. Onsite survey on the mechanism of passive aeration and air flow path in a semi-aerobic landfill.

    Science.gov (United States)

    Matsuto, Toshihiko; Zhang, Xin; Matsuo, Takayuki; Yamada, Shuhei

    2015-02-01

    The semi-aerobic landfill is a widely accepted landfill concept in Japan because it promotes stabilization of leachates and waste via passive aeration without using any type of mechanical equipment. Ambient air is thought to be supplied to the landfill through a perforated pipe network made of leachate collection pipe laid along the bottom and a vertically erected gas vent. However, its underlying air flow path and driving forces are unclear because empirical data from real-world landfills is inadequate. The objective of this study is to establish scientific evidence about the aeration mechanisms and air flow path by an on-site survey of a full-scale, semi-aerobic landfill. First, all passive vents located in the landfill were monitored with respect to temperature level and gas velocity in different seasons. We found a linear correlation between the outflow rate and gas temperature, suggesting that air flow is driven by a buoyancy force caused by the temperature difference between waste in the landfill and the ambient temperature. Some vents located near the landfill bottom acted as air inflow vents. Second, we conducted a tracer test to determine the air flow path between two vents, by injecting tracer gas from an air sucking vent. The resulting slowly increasing gas concentration at the neighboring vent suggested that fresh air flow passes through the waste layer toward the gas vents from leachate collection pipes, as well as directly flowing through the pipe network. Third, we monitored the temperature of gas flowing out of a vent at night. Since the temperature drop of the gas was much smaller than that of the environment, the air collected at the gas vents was estimated to flow mostly through the waste layer, i.e., the semi-aerobic landfill has considerable aeration ability under the appropriate conditions.

  13. Aging behavior of Yunnan pine modified by air dielectric barrier discharge cold plasma treatment%DBD冷等离子体处理云南松表面时效性研究

    Institute of Scientific and Technical Information of China (English)

    王洪艳; 杜官本; 韩永国

    2013-01-01

    The surface of Yunnan pine wood was treated by air dielectric barrier discharge (DBD) cold plasma at atmospheric pressure,and the contact angles of the surface with water and diiodomethane for different standing time after treating were tested.The surface free energy and other parameters were calculated according to Young-Good-Girifalco-Fowkes expression.The results showed that after DBD cold plasma treatment the contact angles of treated wood surface decreased prominently and the surface free energy increased,the surface free energy increased by 55% for one hour after treating,however,then it decreased gradually with the time going on.it declined prominently during the period from 9 hours to one day and almost reached the level before treatment after 8 days.%采用空气介质阻挡放电(DBD)冷等离子体改性云南松木材表面,利用水和二碘甲烷测试不同放置时间木材表面接触角,根据Young-Good-Girifalco-Fowkes方程公式计算表面自由能及其色散力和极性力.结果表明,经DBD冷等离子体处理后松木表面接触角明显降低,自由能显著提高,lh后测得表面自由能提高55%;随放置时间的延长表面自由能都逐渐降低,9~24 h内活性降低比较迅速,放置8d后接近于改性前水平.

  14. The Tiptop coal-mine fire, Kentucky: Preliminary investigation of the measurement of mercury and other hazardous gases from coal-fire gas vents

    Science.gov (United States)

    Hower, J.C.; Henke, K.; O'Keefe, J. M. K.; Engle, M.A.; Blake, D.R.; Stracher, G.B.

    2009-01-01

    The Tiptop underground coal-mine fire in the Skyline coalbed of the Middle Pennsylvanian Breathitt Formation was investigated in rural northern Breathitt County, Kentucky, in May 2008 and January 2009, for the purpose of determining the concentrations of carbon dioxide (CO2), carbon monoxide (CO), and mercury (Hg) in the vent and for measuring gas-vent temperatures. At the time of our visits, concentrations of CO2 peaked at 2.0% and > 6.0% (v/v) and CO at 600 ppm and > 700 ppm during field analysis in May 2008 and January 2009, respectively. For comparison, these concentrations exceed the U.S. Occupational Safety & Health Administration (OSHA) eight-hour safe exposure limits (0.5% CO2 and 50 ppm CO), although the site is not currently mined. Mercury, as Hg0, in excess of 500 and 2100 ??g/m3, in May and January, respectively, in the field, also exceeded the OSHA eight-hour exposure limit (50 ??g/m3). Carbonyl sulfide, dimethyl sulfide, carbon disulfide, and a suite of organic compounds were determined at two vents for the first sampling event. All gases are diluted by air as they exit and migrate away from a gas vent, but temperature inversions and other meteorological conditions could lead to unhealthy concentrations in the nearby towns. Variation in gas temperatures, nearly 300 ??C during the January visit to the fire versus vent gases. ?? 2009 Elsevier B.V.

  15. Nearshore morphology, benthic structure, hydrodynamics, and coastal groundwater discharge near Kahekili Beach Park, Maui, Hawaii

    Science.gov (United States)

    Swarzenski, Peter W.; Storlazzi, Curt D.; Presto, M. Katherine; Gibbs, Ann E.; Smith, Christopher G.; Dimova, Natasha T.; Dailer, Meghan L.; Logan, Joshua B.

    2012-01-01

    This report presents a brief summary of recent fieldwork conducted off Kahekili Beach Park, Maui, Hawaii, the site of the newly established U.S. Coral Reef Task Force priority study area at Kaanapali and the Hawaii Department of Land and Natural Resources, Division of Aquatic Resources, Kahekili Herbivore Fisheries Management Area (HFMA). The goals of this fieldwork are to provide new baseline information to help guide future studies and to provide first insights into rates and drivers of coastal groundwater discharge and associated constituent loadings into the priority study area's coastal waters. This study presents the first swath acoustic mapping information, in situ oceanographic instrument measurements, and coastal groundwater discharge estimates at this site based on the submarine groundwater discharge tracer radon-222 (222Rn). Coastal groundwater discharge rates ranged from about 22 to 50 centimeters per day, depending on proximity of the sampling mooring to the primary discharge vent. The water chemistry of the discharging groundwater was at times dramatically different than ambient seawater. For example, at the primary vent site at Kahekili, the concentrations of total dissolved nitrogen (TDN), dissolved silicate (DSi), and total dissolved phosphorus (TDP) in the discharging groundwater were 43.75 micromolar (μM), 583.49 μM, and 12.04 μM, respectively. These data extend our basic understanding of the morphology, benthic structure, and oceanographic setting of this vent site and provide a first estimate of the magnitude and physical forcings of submarine groundwater discharge and associated trace metals and nutrient loads here.

  16. Vent Control as a Means of Enhancing Airbag Performance

    Directory of Open Access Journals (Sweden)

    Richard E. Zimmermann

    2002-01-01

    Full Text Available Typical automotive airbag systems have a fixed area vent for exiting gasses. The US Army Cockpit Airbag System (CABS is unvented to prolong the period during which the system can provide occupant protection during extended helicopter crash scenarios. In each application, system performance may be enhanced by providing a controlled vent area. This paper describes work conducted under a Phase I SBIR program sponsored by the NASA Langley Research Center. The work was focused on eventual inflatable restraint system applications in general aviation aircraft, and showed that appropriate vent control offers many enhancements. Two series of tests conducted during Phase I showed that inflatable restraint system size and weight can be reduced without degrading performance, injury potential in an out of position situation (OOPS deployment can be reduced, and peak bag pressures can be reduced (at any temperature during normal operation.

  17. Activity and abundance of denitrifying bacteria in the subsurface biosphere of diffuse hydrothermal vents of the Juan de Fuca Ridge

    Science.gov (United States)

    Bourbonnais, A.; Juniper, S. K.; Butterfield, D. A.; Devol, A. H.; Kuypers, M. M. M.; Lavik, G.; Hallam, S. J.; Wenk, C. B.; Chang, B. X.; Murdock, S. A.; Lehmann, M. F.

    2012-11-01

    Little is known about fixed nitrogen (N) transformation and elimination at diffuse hydrothermal vents where anoxic fluids are mixed with oxygenated crustal seawater prior to discharge. Oceanic N sinks that remove bio-available N ultimately affect chemosynthetic primary productivity in these ecosystems. Using 15N paired isotope techniques, we determined potential rates of fixed N loss pathways (denitrification, anammox) and dissimilatory nitrate reduction to ammonium (DNRA) in sulfidic hydrothermal vent fluids discharging from the subsurface at several sites at Axial Volcano and the Endeavour Segment on the Juan de Fuca Ridge. We also measured physico-chemical parameters (i.e., temperature, pH, nutrients, H2S and N2O concentrations) as well as the biodiversity and abundance of chemolithoautotrophic nitrate-reducing, sulfur-oxidizing γ-proteobacteria (SUP05 cluster) using sequence analysis of amplified small subunit ribosomal RNA (16S rRNA) genes in combination with taxon-specific quantitative polymerase chain reaction (qPCR) assays. Denitrification was the dominant N loss pathway in the subsurface biosphere of the Juan de Fuca Ridge, with rates of up to ~1000 nmol N l-1 day-1. In comparison, anammox rates were always waters. Taxon-specific qPCR revealed that γ-proteobacteria of the SUP05 cluster sometimes dominated the microbial community (SUP05/total bacteria up to 38%). Significant correlations were found between fixed N loss (i.e., denitrification, anammox) rates and in situ nitrate and dissolved inorganic nitrogen (DIN) deficits in the fluids, indicating that DIN availability may ultimately regulate N loss in the subsurface. Based on our rate measurements, and on published data on hydrothermal fluid fluxes and residence times, we estimated that up to ~10 Tg N yr-1 could globally be removed in the subsurface biosphere of hydrothermal vents systems, thus, representing a small fraction of the total marine N loss (~275 to > 400 Tg N yr-1).

  18. Numerical Study on Pressure Drop Factor in the Vent-Cap of CDQ Shaft

    Institute of Scientific and Technical Information of China (English)

    Bo Song; Yanhui Feng; Xinxin Zhang

    2008-01-01

    In CDQ (Coke Dry Quenching) shaft, the vent-cap with complex structure is installed in the cone-shaped funnel under the cooling chamber. It acts to introduce cooling gas and support the descending coke in the chamber. The designing and installation of vent-cap aim to get relatively uniform gas distribution, to reduce the temperature fluctuation of cokes at outlet and realize stable operation of CDQ apparatus. In this paper, the turbulent flow of gas in vent-cap of 1:7 scale CDQ experimental shaft is numerically simulated by using CFD (Computational Fluid Dynamics) software, CFX. The velocity field, the outlet flux distribution and the pressure drop factor of each outlet under three kinds of vent-cap (called high vent-cap, low vent-cap and elliptic vent-cap) are analysed and compared. The results turn out that the pressure drop factor of elliptic vent-cap is larger than the other two vent-caps, and that the pressure drop factors of high vent-cap and low vent-cap almost have the same value.While for a specified vent-cap, the pressure drop factor with pressing brick is larger than that without pressing brick. The work in this paper is valuable for the designing of vent-cap for large-acale CDQ shaft.

  19. 基于长间隙放电研究雷电屏蔽问题的进展%Review of the Lightning Shielding Against Direct Lightning Strokes Based on Laboratory Long Air Gap Discharges

    Institute of Scientific and Technical Information of China (English)

    陈维江; 贺恒鑫; 钱冠军; 陈家宏; 何俊佳; 谷山强; 谢施君; 向念文

    2012-01-01

    长间隙放电是研究地面物体雷电屏蔽问题的最有效手段之一。首先介绍了国内外在雷电击距、直击雷防护措施的屏蔽性能试验和雷电迎面先导过程研究3个方面所取得的进展,并结合最新开展的长达6m问隙尺度的放电试验观测,对现阶段上述3个方面研究所存在的问题进行了分析。认为基于雷电击距建立的电气几何模型(electricgeometrymodel,EGM)仅适用于小尺度目标物的雷电屏蔽性能分析,现有的雷电屏蔽模拟试验方法仅能近似模拟不存在雷电迎面先导时的雷击过程,无法完全证明以提前流注发射模型装置为代表的非传统防雷装置具有比传统措施更优越的屏蔽性能。大尺度目标物的雷电屏蔽问题应聚焦于雷电迎面先导过程的研究,建立并完善雷电迎面先导过程的模拟试验方法和物理仿真模型。%It is one of the most effective ways to use laboratory long air gap discharges for investigating the fundamental process involved in the lightning attachment. The research development on the lightning striking distance, the lightning simulation test and the positive upward connecting leader process by using laboratory long sparks were reviewed in this paper. According to the discharge observation results with the gap length up to 6m carried out in this paper, it is acceptable by using electric geometric model (EGM) to estimate the lightning shielding performance of small scale grounded objects, the existing lightning shielding simulation test does not take into account of the influence of upward connecting leaders, and the early streamer emission (ESE) device does not have the specified performance as it claimed. The lightning shielding performance investigation of largescale objects should focus on the inception and propagation of the positive upward leader, which aims to develop the simulation test methods of positive upward leader by using long sparks

  20. Analysis on Venting Time of Rarefaction Wave Gun

    Institute of Scientific and Technical Information of China (English)

    WANG Ying-ze; ZHANG Xiao-bing; YUAN Yax-iong

    2008-01-01

    Based on the operation principle of rarefaction wave gun, the selection and calculation methods for venting opportune moment are invastigated. Considering property of the rarefaction wave, taking the center of muzzle section as initial calculation point, supposing that at the moment projectile arrives to the muzzle, the rarefaction wave arrives to the base of projectile, the rarefaction wave velocity along the barrel can be obtained by fitting calculation of the interior ballis-tic data of the same closed gun and reverse deduction. And then, the optimal venting time can be found out correctly based on the rarefaction wave velocity.

  1. Pressure Venting Tests of Phenolic Impregnated Carbon Ablator (PICA)

    Science.gov (United States)

    Blosser, Max L.; Knutson, Jeffrey R.

    2015-01-01

    A series of tests was devised to investigate the pressure venting behavior of one of the candidate ablators for the Orion capsule heat shield. Three different specimens of phenolic impregnated carbon ablator (PICA) were instrumented with internal pressure taps and subjected to rapid pressure changes from near vacuum to one atmosphere and simulated Orion ascent pressure histories. The specimens vented rapidly to ambient pressure and sustained no detectable damage during testing. Peak pressure differences through the thickness of a 3-inch-thick specimen were less than 1 psi during a simulated ascent pressure history.

  2. Hydrothermal Vents and Methane Seeps: Rethinking the Sphere of Influence

    Directory of Open Access Journals (Sweden)

    Lisa Ann Levin

    2016-05-01

    Full Text Available Although initially viewed as oases within a barren deep ocean, hydrothermal vent and methane seep communities are now recognized to interact with surrounding ecosystems on the sea floor and in the water column, and to affect global geochemical cycles. The importance of understanding these interactions is growing as the potential rises for disturbance from oil and gas extraction, seabed mining and bottom trawling. Here we synthesize current knowledge of the nature, extent and time and space scales of vent and seep interactions with background systems. We document an expanded footprint beyond the site of local venting or seepage with respect to elemental cycling and energy flux, habitat use, trophic interactions, and connectivity. Heat and energy are released, global biogeochemical and elemental cycles are modified, and particulates are transported widely in plumes. Hard and biotic substrates produced at vents and seeps are used by benthic background fauna for attachment substrata, shelter, and access to food via grazing or through position in the current, while particulates and fluid fluxes modify planktonic microbial communities. Chemosynthetic production provides nutrition to a host of benthic and planktonic heterotrophic background species through multiple horizontal and vertical transfer pathways assisted by flow, gamete release, animal movements, and succession, but these pathways remain poorly known. Shared species, genera and families indicate that ecological and evolutionary connectivity exists among vents, seeps, organic falls and background communities in the deep sea; the genetic linkages with inactive vents and seeps and background assemblages however, are practically unstudied. The waning of venting or seepage activity generates major transitions in space and time that create links to surrounding ecosystems, often with identifiable ecotones or successional stages. The nature of all these interactions is dependent on water depth, as

  3. Hydrothermal vents and methane seeps: Rethinking the sphere of influence

    Science.gov (United States)

    Levin, Lisa A.; Baco, Amy; Bowden, David; Colaco, Ana; Cordes, Erik E.; Cunha, Marina; Demopoulos, Amanda; Gobin, Judith; Grupe, Ben; Le, Jennifer; Metaxas, Anna; Netburn, Amanda; Rouse, Greg; Thurber, Andrew; Tunnicliffe, Verena; Van Dover, Cindy L.; Vanreusel, Ann; Watling, Les

    2016-01-01

    Although initially viewed as oases within a barren deep ocean, hydrothermal vent and methane seep communities are now recognized to interact with surrounding ecosystems on the sea floor and in the water column, and to affect global geochemical cycles. The importance of understanding these interactions is growing as the potential rises for disturbance from oil and gas extraction, seabed mining and bottom trawling. Here we synthesize current knowledge of the nature, extent and time and space scales of vent and seep interactions with background systems. We document an expanded footprint beyond the site of local venting or seepage with respect to elemental cycling and energy flux, habitat use, trophic interactions, and connectivity. Heat and energy are released, global biogeochemical and elemental cycles are modified, and particulates are transported widely in plumes. Hard and biotic substrates produced at vents and seeps are used by “benthic background” fauna for attachment substrata, shelter, and access to food via grazing or through position in the current, while particulates and fluid fluxes modify planktonic microbial communities. Chemosynthetic production provides nutrition to a host of benthic and planktonic heterotrophic background species through multiple horizontal and vertical transfer pathways assisted by flow, gamete release, animal movements, and succession, but these pathways remain poorly known. Shared species, genera and families indicate that ecological and evolutionary connectivity exists among vents, seeps, organic falls and background communities in the deep sea; the genetic linkages with inactive vents and seeps and background assemblages however, are practically unstudied. The waning of venting or seepage activity generates major transitions in space and time that create links to surrounding ecosystems, often with identifiable ecotones or successional stages. The nature of all these interactions is dependent on water depth, as well as

  4. Volume Diffuse Dielectric Barrier Discharge Plasma Produced by Nanosecond High Voltage Pulse in Airflow

    Institute of Scientific and Technical Information of China (English)

    QI Haicheng; GAO Wei; FAN Zhihui; LIU Yidi; REN Chunsheng

    2016-01-01

    Volume diffuse dielectric barrier discharge (DBD) plasma is produced in subsonic airflow by nanosecond high-voltage pulse power supply with a plate-to-plate discharge cell at 6 mm air gap length.The discharge images,optical emission spectra (OES),the applied voltage and current waveforms of the discharge at the changed airflow rates are obtained.When airflow rate is increased,the transition of the discharge mode and the variations of discharge intensity,breakdown characteristics and the temperature of the discharge plasma are investigated.The results show that the discharge becomes more diffuse,discharge intensity is decreased accompanied by the increased breakdown voltage and time lag,and the temperature of the discharge plasma reduces when airflow of small vclocity is introduced into the discharge gap.These phenomena are because that the airflow changes the spatial distribution of the heat and the space charge in the discharge gap.

  5. Volume Diffuse Dielectric Barrier Discharge Plasma Produced by Nanosecond High Voltage Pulse in Airflow

    Science.gov (United States)

    Qi, Haicheng; Gao, Wei; Fan, Zhihui; Liu, Yidi; Ren, Chunsheng

    2016-05-01

    Volume diffuse dielectric barrier discharge (DBD) plasma is produced in subsonic airflow by nanosecond high-voltage pulse power supply with a plate-to-plate discharge cell at 6 mm air gap length. The discharge images, optical emission spectra (OES), the applied voltage and current waveforms of the discharge at the changed airflow rates are obtained. When airflow rate is increased, the transition of the discharge mode and the variations of discharge intensity, breakdown characteristics and the temperature of the discharge plasma are investigated. The results show that the discharge becomes more diffuse, discharge intensity is decreased accompanied by the increased breakdown voltage and time lag, and the temperature of the discharge plasma reduces when airflow of small velocity is introduced into the discharge gap. These phenomena are because that the airflow changes the spatial distribution of the heat and the space charge in the discharge gap. supported by National Natural Science Foundation of China (No. 51437002)

  6. The pH and pCO2 dependence of sulfate reduction in shallow-sea hydrothermal CO2 – venting sediments (Milos Island, Greece

    Directory of Open Access Journals (Sweden)

    Elisa eBayraktarov

    2013-05-01

    Full Text Available Microbial sulfate reduction is a dominant process of organic matter mineralization in sulfate-rich anoxic environments at neutral pH. Recent studies have demonstrated sulfate reduction in low pH environments, but investigations on the microbial activity at variable pH and CO2 partial pressure are still lacking. In this study, the effect of pH and pCO2 on microbial activity was investigated by incubation experiments with radioactive 35S targeting sulfate reduction in sediments from the shallow-sea hydrothermal vent system of Milos, Greece, where pH is naturally decreased by CO2 release. Sediments differed in their physicochemical characteristics with distance from the main site of fluid discharge. Adjacent to the vent site (T ~ 40 – 75 °C, pH ~ 5, maximal sulfate reduction rates were observed between pH 5 – 6. Sulfate reduction in hydrothermally influenced sediments decreased at neutral pH. Sediments unaffected by hydrothermal venting (T ~ 26°, pH ~ 8 expressed the highest sulfate reduction rates between pH 6 – 7. Further experiments investigating the effect of pCO2 on sulfate reduction revealed a steep decrease in activity when the partial pressure increased from 2 to 3 bar. Findings suggest that sulfate reducing microbial communities associated with hydrothermal vent system are adapted to low pH and high CO2, while communities at control sites required a higher pH for optimal activity.

  7. Numerical investigation of dielectric barrier discharges

    Science.gov (United States)

    Li, Jing

    1997-12-01

    A dielectric barrier discharge (DBD) is a transient discharge occurring between two electrodes in coaxial or planar arrangements separated by one or two layers of dielectric material. The charge accumulated on the dielectric barrier generates a field in a direction opposite to the applied field. The discharge is quenched before an arc is formed. It is one of the few non-thermal discharges that operates at atmospheric pressure and has the potential for use in pollution control. In this work, a numerical model of the dielectric barrier discharge is developed, along with the numerical approach. Adaptive grids based on the charge distribution is used. A self-consistent method is used to solve for the electric field and charge densities. The Successive Overrelaxation (SOR) method in a non-uniform grid spacing is used to solve the Poisson's equation in the cylindrically-symmetric coordinate. The Flux Corrected Transport (FCT) method is modified to solve the continuity equations in the non-uniform grid spacing. Parametric studies of dielectric barrier discharges are conducted. General characteristics of dielectric barrier discharges in both anode-directed and cathode-directed streamer are studied. Effects of the dielectric capacitance, the applied field, the resistance in external circuit and the type of gases (O2, air, N2) are investigated. We conclude that the SOR method in an adaptive grid spacing for the solution of the Poisson's equation in the cylindrically-symmetric coordinate is convergent and effective. The dielectric capacitance has little effect on the g-factor of radical production, but it determines the strength of the dielectric barrier discharge. The applied field and the type of gases used have a significant role on the current peak, current pulse duration and radical generation efficiency, discharge strength, and microstreamer radius, whereas the external series resistance has very little effect on the streamer properties. The results are helpful in

  8. Fractal characterization of surface electrical discharges

    Energy Technology Data Exchange (ETDEWEB)

    Egiziano, L.; Femia, N.; Lupo' , G.; Tucci, V. (Salerno Univ. (Italy). Ist. di Ingegneria Elettronica Naples Univ. (Italy). Dip. di Ingegneria Elettrica)

    1991-01-01

    The concepts of fractal geometry have been usefully applied to describe several physical processes whose growth mechanisms are characterized by complex topological structures. The fractal characterization of electrical discharges taking place at the air/solid dielectric interface is considered in this paper. A numerical procedure allowing the reproduction the typical discharge patterns, known as Lichtenberg figures, is presented: the growth process of the discharge is simulated by solving iteratively the Laplace equation with moving boundary conditions and by considering two power probability laws whose exponents determine the ramification level of the structure. The discharge patterns are then considered as fractal sets and their characteristic parameters are determined. The dependence of the typical structures on the two exponents of the probability laws are also discussed.

  9. Multiphase flow above explosion sites in debris-filled volcanic vents: Insights from analogue experiments

    Science.gov (United States)

    Ross, Pierre-Simon; White, James D. L.; Zimanowski, Bernd; Büttner, Ralf

    2008-11-01

    Discrete explosive bursts are known from many volcanic eruptions. In maar-diatreme eruptions, they have occurred in debris-filled volcanic vents when magma interacted with groundwater, implying that material mobilized by such explosions passed through the overlying and enclosing debris to reach the surface. Although other studies have addressed the form and characteristics of craters formed by discrete explosions in unconsolidated material, no details are available regarding the structure of the disturbed debris between the explosion site and the surface. Field studies of diatreme deposits reveal cross-cutting, steep-sided zones of non-bedded volcaniclastic material that have been inferred to result from sedimentation of material transported by "debris jets" driven by explosions. In order to determine the general processes and deposit geometry resulting from discrete, explosive injections of entrained particles through a particulate host, we ran a series of analogue experiments. Specific volumes of compressed (0.5-2.5 MPa) air were released in bursts that drove gas-particle dispersions through a granular host. The air expanded into and entrained coloured particles in a small crucible before moving upward into the host (white particles). Each burst drove into the host an expanding cavity containing air and coloured particles. Total duration of each run, recorded with high-speed video, was approximately 0.5-1 s. The coloured beads sedimented into the transient cavity. This same behaviour was observed even in runs where there was no breaching of the surface, and no coloured beads ejected. A steep-sided body of coloured beads was left that is similar to the cross-cutting pipes observed in deposits filling real volcanic vents, in which cavity collapse can result not only from gas escape through a granular host as in the experiments, but also through condensation of water vapour. A key conclusion from these experiments is that the geometry of cross-cutting volcaniclastic

  10. Chronic obstructive pulmonary disease - adults - discharge

    Science.gov (United States)

    COPD - adults - discharge; Chronic obstructive airways disease - adults - discharge; Chronic obstructive lung disease - adults - discharge; Chronic bronchitis - adults - discharge; Emphysema - adults - discharge; Bronchitis - ...

  11. Numerical Simulation of Unsteady Discharge Flow with Fluctuation in Positive Discharge Blower

    Institute of Scientific and Technical Information of China (English)

    LIU Zhengxian; WANG Dou; XU Lianhuan

    2009-01-01

    The operating performance of positive discharge blower/s markedly influenced by the pulsation of the discharge flow, but difficult to be measured with experimental methods. The internal and discharge flow of positive discharge blower with involute type three-lobe are numerically investigated, both in air cooling and countercurrent cooling conditions by means of computational fluid dynamics (CFD). The unsteady compressible flow equations are solved using RNG κ-ε turbulent model. The finite difference method and the second order upwind difference scheme are applied into discrete equations. In the numerical simulation, the dynamic mesh techniques are used to approach the rotating displacement of cell cubage and the alterability of inlet, outlet flow area. The non-uniform mesh is applied to the rotor-stator coupled area. The reliability of the numerical method is verified by simulating the inner flow and comparing with the semi-empirical theory. The flow flux curves and the distributing of velocity vector showed obvious vortex motion in all the discharge process, both in air cooling and countercurrent cooling conditions. These vortexes with different positions, intension and numbers at different rotating angles have remarkable influences on the discharge flux. For air cooling, the vortex produced a second pulsation with big-amplitude in a cycle, and led to the early appearance of maximum of backflow. For countercurrent cooling, the frequency of pulsation increased due to the pre-inflow, but the hackflow at the outlet is prevented, also the pulsation strength has greatly decreased.

  12. Characteristics of Repetitive Nanosecond-pulse Discharge in Atmospheric Air with a Tube-to-plane Gap%大气压空气中管-板电极结构重复频率纳秒脉冲的放电特性

    Institute of Scientific and Technical Information of China (English)

    章程; 邵涛; 于洋; 姜慧; 许家雨; 严萍

    2011-01-01

    Repetitive nanosecond-pulse is focused on because it can provide extremely high overvoltage for excitation of non-thermal plasma at atmospheric air.With an excitation of negative repetitive pulses of 15 ns rise-time and 30~40 ns duration,characteristics of repetitive nanosecond-pulse discharge in atmospheric air with a tube-to-plane gap are investigated by the measurement of their electrical discharge parameters,images,and X-ray diffraction.Results show that nanosecond-pulse discharge has 3 discharge forms,which is corona,diffuse,and filamentary discharge,respectively,and the discharge modes and their transition are affected by the air gap spacing.In addition,it is detected that the main part of X-ray energy in X-ray diffraction locates at 30 to 90 keV.%由于重复频率窄脉冲气体放电具有的高过电压倍数,能够稳定地激励大气压空气等离子体,近年来受到了广泛关注。为此,利用上升沿15ns、半高宽30~40ns的负极性ns脉冲激励大气压管-板电极结构空气放电,通过电压电流测量,放电图像拍摄和X射线探测研究了ns脉冲气体放电模式和X射线辐射特性。结果表明,ns脉冲放电存在电晕、弥散和丝状3种模式,各模式及其转换与气隙距离相关。放电中测得的X射线辐射能量主要集中在30~90keV。

  13. Experimental Observation of Travelling Hexagon Patterns in Dielectric Barrier Discharge

    Institute of Scientific and Technical Information of China (English)

    董丽芳; 贺亚峰; 尹增谦; 柴志方

    2003-01-01

    Travelling hexagon patterns have been observed in dielectric barrier discharge in an air-argon mixture. The phase diagram of hexagon pattern appearance as functions of applied voltage and air concentration is given. The spatial frequency of hexagon pattern increases with increasing applied voltage and air concentration. The current waveforms of hexagon pattern also vary with the air concentration. The drift velocity of travelling hexagon pattern changes from 4mm/s to 18mm/s.

  14. Air exchanges and indoor carbon dioxide concentration in Australian pig buildings: Effect of housing and management factors

    DEFF Research Database (Denmark)

    Banhazi, T. M.; Stott, P.; Rutley, D.

    2011-01-01

    factors on the concentrations of carbon dioxide (CO(2)) and air exchange rates in 160 representative Australian pig buildings. CO(2) concentrations were measured, air changes per hour (ACH) were estimated using a CO(2) balance method, and structural and management parameters were recorded. The mean CO(2......) concentration measured was 858 ppm and a mean air exchange rate of 22.8 ACH was estimated. The analysis showed that CO(2) concentrations were affected by the type of building, season, control of the wall and ridge vents, ceiling height, size of the wall vents and height of the ridge vents. Weaner buildings had...

  15. 46 CFR 119.450 - Vent pipes for fuel tanks.

    Science.gov (United States)

    2010-10-01

    ... flame arresters. The flame screens must consist of a single screen of corrosion resistant wire of at least 30×30 mesh. The flame screens or flame arresters must be of such size and design as to prevent... screens or arrester elements. (e) Where a flexible vent pipe section is necessary, suitable...

  16. Variation in the diets of hydrothermal vent gastropods

    Science.gov (United States)

    Govenar, Breea; Fisher, Charles R.; Shank, Timothy M.

    2015-11-01

    A prevailing paradigm of hydrothermal vent ecology is that primary consumers feed on chemoautotrophic bacteria. However, for the purposes of reconstructing vent food webs and for tracking energy flow from the generation of rock and fluid chemistry through primary/ secondary productivity and consumption to the overlying water column, it remains unclear which consumers feed on which bacteria. In paired analyses of carbon and nitrogen tissue stable isotope values with unique 16S rRNA sequences from the stomach contents, we determined that two species of gastropod grazers appear to feed on epsilon-proteobacteria, while two other species have more diverse diets, including one species that consumes alpha-proteobacteria, planctomycetes, and non-green sulfur bacteria. Different carbon fixation pathways used by epsilon- and alpha-proteobacteria may account for the variation in the carbon stable isotope values among the consumers. Furthermore, our results indicate that trophic specialization and niche partitioning may contribute to the distribution and abundance of vent-endemic gastropods and support the hypothesis that consumers in the warmer habitats commonly feed on epsilon-proteobacteria that use the rTCA cycle, while in the cooler habitats they feed on additional bacteria that use the CBB cycle. These results suggest that the phylogenetic and metabolic diversity of free-living bacteria may play an important and previously overlooked role in facilitating species coexistence among primary consumers at hydrothermal vents and other chemosynthesis-based ecosystems.

  17. 76 FR 44457 - Application of Regulations on Fuel Venting

    Science.gov (United States)

    2011-07-26

    ... Federal Aviation Administration 14 CFR Part 34 Application of Regulations on Fuel Venting AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Policy determination. SUMMARY: This document advises the public of a recent decision by the Federal Aviation Administration (FAA) concerning the application...

  18. Ephemerality of discrete methane vents in lake sediments

    Science.gov (United States)

    Scandella, Benjamin P.; Pillsbury, Liam; Weber, Thomas; Ruppel, Carolyn; Hemond, Harold F.; Juanes, Ruben

    2016-01-01

    Methane is a potent greenhouse gas whose emission from sediments in inland waters and shallow oceans may both contribute to global warming and be exacerbated by it. The fraction of methane emitted by sediments that bypasses dissolution in the water column and reaches the atmosphere as bubbles depends on the mode and spatiotemporal characteristics of venting from the sediments. Earlier studies have concluded that hot spots—persistent, high-flux vents—dominate the regional ebullitive flux from submerged sediments. Here the spatial structure, persistence, and variability in the intensity of methane venting are analyzed using a high-resolution multibeam sonar record acquired at the bottom of a lake during multiple deployments over a 9 month period. We confirm that ebullition is strongly episodic, with distinct regimes of high flux and low flux largely controlled by changes in hydrostatic pressure. Our analysis shows that the spatial pattern of ebullition becomes homogeneous at the sonar's resolution over time scales of hours (for high-flux periods) or days (for low-flux periods), demonstrating that vents are ephemeral rather than persistent, and suggesting that long-term, lake-wide ebullition dynamics may be modeled without resolving the fine-scale spatial structure of venting.

  19. Carbon fluxes from hydrothermal vents off Milos, Aegean Volcanic Arc, and the influence of venting on the surrounding ecosystem.

    Science.gov (United States)

    Dando, Paul; Aliani, Stefano; Bianchi, Nike; Kennedy, Hilary; Linke, Peter; Morri, Carla

    2014-05-01

    The island of Milos, in the Aegean Sea, has extensive hydrothermal fields to the east and southeast of the island with additional venting areas near the entrance to and within the central caldera. A calculation of the total area of the vent fields, based on ship and aerial surveys, suggested that the hydrothermal fields occupy 70 km2, twice the area previously estimated. The vents ranged in water depth from the intertidal to 300 m. As a result of the low depths there was abundant free gas release: in places water boiled on the seabed. The stream of gas bubbles rising through the sandy seabed drove a shallow re-circulation of bottom seawater. The majority of the water released with the gas, with a mean pH of 5.5, was re-circulated bottom water that had become acidified in contact with CO2 gas and was often diluted by admixture with the vapour phase from the deeper fluids. The major component of the free gas, 80%, was CO2, with an estimated total flux of 1.5-7.5 x 1012 g a-1. The methane flux, by comparison, was of the order of 1010 g a.-1 Using methane as a tracer it was shown that the major gas export from the vents was below the thermocline towards the southwest, in agreement with the prevailing currents. Areas of hydrothermal brine seepage occurred between the gas vents and occasional brine pools were observed in seabed depressions. Under relatively calm conditions, many of the brine seeps were covered by thick minero-bacterial mats consisting of silica and sulphur and surrounded by mats of diatoms and cyanobacteria. The minerals were not deposited in the absence of bacteria. Storms disrupted the mats, leading to an export of material to the surrounding area. Stable isotope data from sediments and sediment trap material suggested that exported POM was processed by zooplankton. The combined effects of the geothermal heating of the seabed, the large gas flux, variation in the venting and the effect of the brine seeps had a dramatic effect on the surrounding

  20. 40 CFR 63.491 - Batch front-end process vents-recordkeeping requirements.

    Science.gov (United States)

    2010-07-01

    ...)(2). (3) When using a flare to comply with § 63.487(a)(1): (i) The flare design (i.e., steam-assisted... process vents and § 63.490(e) for aggregate batch vent streams; (ii) For a boiler or process heater, a description of the location at which the vent stream is introduced into the boiler or process heater;...

  1. 40 CFR 63.1104 - Process vents from continuous unit operations: applicability assessment procedures and methods.

    Science.gov (United States)

    2010-07-01

    ... vent. (iv) Design analysis based on accepted chemical engineering principles, measurable process... be monitored to ensure the process vent is operated in conformance with its design or process and... 40 Protection of Environment 10 2010-07-01 2010-07-01 false Process vents from continuous...

  2. 30 CFR 250.1160 - When may I flare or vent gas?

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false When may I flare or vent gas? 250.1160 Section... GAS AND SULPHUR OPERATIONS IN THE OUTER CONTINENTAL SHELF Oil and Gas Production Requirements Flaring, Venting, and Burning Hydrocarbons § 250.1160 When may I flare or vent gas? (a) You must request...

  3. Characterization of Bacterial Communities in Deep-Sea Hydrothermal Vents from Three Oceanic Regions.

    Science.gov (United States)

    He, Tianliang; Zhang, Xiaobo

    2016-04-01

    Deep-sea hydrothermal vents are considered to be one of the most spectacular ecosystems on Earth. Microorganisms form the basis of the food chain in vents controlling the vent communities. However, the diversity of bacterial communities in deep-sea hydrothermal vents from different oceans remains largely unknown. In this study, the pyrosequencing of 16S rRNA gene was used to characterize the bacterial communities of the venting sulfide, seawater, and tubeworm trophosome from East Pacific Rise, South Atlantic Ridge, and Southwest Indian Ridge, respectively. A total of 23,767 operational taxonomic units (OTUs) were assigned into 42 different phyla. Although Proteobacteria, Actinobacteria, and Bacteroidetes were the predominant phyla in all vents, differences of bacterial diversity were observed among different vents from three oceanic regions. The sulfides of East Pacific Rise possessed the most diverse bacterial communities. The bacterial diversities of venting seawater were much lower than those of vent sulfides. The symbiotic bacteria of tubeworm Ridgeia piscesae were included in the bacterial community of vent sulfides, suggesting their significant ecological functions as the primary producers in the deep-sea hydrothermal vent ecosystems. Therefore, our study presented a comprehensive view of bacterial communities in deep-sea hydrothermal vents from different oceans.

  4. 40 CFR 60.482-10 - Standards: Closed vent systems and control devices.

    Science.gov (United States)

    2010-07-01

    ..., audible, or olfactory indications of leaks. (2) If the vapor collection system or closed vent system is... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Standards: Closed vent systems and..., 2006 § 60.482-10 Standards: Closed vent systems and control devices. (a) Owners or operators of...

  5. Geophysical Signatures of cold vents on the northern Cascadia margin

    Science.gov (United States)

    Riedel, M.; Paull, C. K.; Spence, G.; Hyndman, R. D.; Caress, D. W.; Thomas, H.; Lundsten, E.; Ussler, W.; Schwalenberg, K.

    2009-12-01

    The accretionary prism of the northern Cascadia margin is a classic gas hydrate research area. Ocean Drilling Program Leg 146 and Integrated Ocean Drilling Program (IODP) Expedition 311 documented that gas hydrate is widely distributed across the margin. In recent years an increased research focus has been on cold vents, where methane gas is actively released. Two recent expeditions funded by the Monterey Bay Aquarium Research Institute (MBARI) were conducted in the area of IODP Sites U1327 and U1328. An autonomous underwater vehicle (AUV) was used to map the seafloor bathymetry followed by dives with the ROV Doc Ricketts for ground truth information of various seafloor morphological features identified. The two cruises revealed many new seafloor features indicative of methane venting that were previously unknown. Bullseye Vent (BV) has been extensively studied using seismic imaging, piston coring, heat-flow, controlled-source EM, and deep drilling. BV is seismically defined by a circular wipe-out zone but the new AUV data show that BV is rather an elongated depression. BV is associated with a shoaling in the BSR, but lacks evidence for the existence of an underlying fault in the previous data. Although a massive gas-hydrate plug was encountered within the top 40 mbsf in the IODP holes, the ROV observations only revealed some platy methane derived carbonate outcrops at the outer-most rim of the depressions, a few beds of Vesicomya clams, and no observed gas vents, which together do not indicate that BV is especially active now. Further northeast of BV, but along the same trend, active gas venting was found associated with seafloor blistering and bacterial mats suggesting that there is an underlying fault system providing a fluid flow conduit. The newly discovered vent area has few seismic line crossings; however the available seismic data surprisingly are not associated with wipe-out zones. Another prominent fault-related gas vent also was investigated during the

  6. NatVent. A better way to work: Overcoming barriers to natural ventilation

    Energy Technology Data Exchange (ETDEWEB)

    Wouters, P.; Demeester, J. (eds.)

    1999-01-01

    NatVent is a European project which is being carried out by a consortium of nine partners, across seven countries - Great Britain, Belgium, Denmark, the Netherlands, Sweden, Norway and Switzerland. The main objective of this project was to reduce primary energy use consumption in buildings by overcoming barriers which prevent the uptake of natural ventilation for office-type buildings. It is intended for countries with low winter and moderate summer temperatures and where summer overheating from solar and internal gains can be significantly reduced by good natural ventilation. The project has investigated and developed 'smart' components to provide natural ventilation for office-type building which could be naturally ventilated, but because of various technical barriers are, at present, inadequately ventilated, fully mechanically ventilated or air-conditioned. (ed)

  7. NatVent. A better way to work: Overcoming barriers to natural ventilation

    Energy Technology Data Exchange (ETDEWEB)

    Wouters, P.; Demeester, J. [eds.

    1999-10-01

    NatVent is a European project which is being carried out by a consortium of nine partners, across seven countries - Great Britain, Belgium, Denmark, the Netherlands, Sweden, Norway and Switzerland. The main objective of this project was to reduce primary energy use consumption in buildings by overcoming barriers which prevent the uptake of natural ventilation for office-type buildings. It is intended for countries with low winter and moderate summer temperatures and where summer overheating from solar and internal gains can be significantly reduced by good natural ventilation. The project has investigated and developed `smart` components to provide natural ventilation for office-type building which could be naturally ventilated, but because of various technical barriers are, at present, inadequately ventilated, fully mechanically ventilated or air-conditioned. (ed)

  8. Cumulus cloud venting of mixed layer ozone

    Science.gov (United States)

    Ching, J. K. S.; Shipley, S. T.; Browell, E. V.; Brewer, D. A.

    1985-01-01

    Observations are presented which substantiate the hypothesis that significant vertical exchange of ozone and aerosols occurs between the mixed layer and the free troposphere during cumulus cloud convective activity. The experiments utilized the airborne Ultra-Violet Differential Absorption Lidar (UV-DIAL) system. This system provides simultaneous range resolved ozone concentration and aerosol backscatter profiles with high spatial resolution. Evening transects were obtained in the downwind area where the air mass had been advected. Space-height analyses for the evening flight show the cloud debris as patterns of ozone typically in excess of the ambient free tropospheric background. This ozone excess was approximately the value of the concentration difference between the mixed layer and free troposphere determined from independent vertical soundings made by another aircraft in the afternoon.

  9. 17th DOE nuclear air cleaning conference: proceedings. Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    First, M.W. (ed.)

    1983-02-01

    Volume 2 contains papers presented at the following sessions: adsorption; noble gas treatment; personnel education and training; filtration and filter testing; measurement and instrumentation; air cleaning equipment response to accident related stress; containment venting air cleaning; and an open end session. Twenty-eight papers were indexed separately for inclusion in the Energy Data Base. Ten papers had been entered earlier.

  10. CO-AXIAL DISCHARGES

    Science.gov (United States)

    Luce, J.S.; Smith, L.P.

    1960-11-22

    A method and apparatus are given for producing coaxial arc discharges in an evacuated enclosure and within a strong, confining magnetic field. The arcs are maintained at a high potential difference. Electrons will diffuse to the more positive arc from the negative arc, and positive ions will diffuse from the more positive arc to the negative arc. Coaxial arc discharges have the advantage that ions which return to strike the positive arc discharge will lose no energy since they do not strike a solid wall or electrode. Those discharges are useful in confining an ionized plasma between the discharges, and have the advantage of preventing impurities from the walls of the enclosure from entering ihe plasma area because of the arc barrier set up bv the cylindrical outer arc.

  11. EFFECTIVE DISCHARGE CALCULATION GUIDE

    Institute of Scientific and Technical Information of China (English)

    D.S.BIEDENHARN; C.R.THORNE; P.J.SOAR; R.D.HEY; C.C.WATSON

    2001-01-01

    This paper presents a procedure for calculating the effective discharge for rivers with alluvial channels.An alluvial river adjusts the bankfull shape and dimensions of its channel to the wide range of flows that mobilize the boundary sediments. It has been shown that time-averaged river morphology is adjusted to the flow that, over a prolonged period, transports most sediment. This is termed the effective discharge.The effective discharge may be calculated provided that the necessary data are available or can be synthesized. The procedure for effective discharge calculation presented here is designed to have general applicability, have the capability to be applied consistently, and represent the effects of physical processes responsible for determining the channel, dimensions. An example of the calculations necessary and applications of the effective discharge concept are presented.

  12. Predicting tile drainage discharge

    DEFF Research Database (Denmark)

    Iversen, Bo Vangsø; Kjærgaard, Charlotte; Petersen, Rasmus Jes;

    of the water load coming from the tile drainage system is therefore essential. This work aims at predicting tile drainage discharge using dynamic as well as a statistical predictive models. A large dataset of historical tile drain discharge data, daily discharge values as well as yearly average values were......More than 50 % of Danish agricultural areas are expected to be artificial tile drained. Transport of water and nutrients through the tile drain system to the aquatic environment is expected to be significant. For different mitigation strategies such as constructed wetlands an exact knowledge...... used in the analysis. For the dynamic modelling, a simple linear reservoir model was used where different outlets in the model represented tile drain as well as groundwater discharge outputs. This modelling was based on daily measured tile drain discharge values. The statistical predictive model...

  13. 40 CFR 63.115 - Process vent provisions-methods and procedures for process vent group determination.

    Science.gov (United States)

    2010-07-01

    ... From the Synthetic Organic Chemical Manufacturing Industry for Process Vents, Storage Vessels, Transfer... accepted chemical engineering principles, measurable process parameters, or physical or chemical laws or...-77 as indicated in paragraph (d)(2)(ii) of this section. Hj=Net heat of combustion of compound...

  14. Reduction of Carbon Dioxide in Filtering Facepiece Respirators with an Active-Venting System: A Computational Study.

    Directory of Open Access Journals (Sweden)

    Erik Birgersson

    Full Text Available During expiration, the carbon dioxide (CO2 levels inside the dead space of a filtering facepiece respirator (FFR increase significantly above the ambient concentration. To reduce the CO2 concentration inside the dead space, we attach an active lightweight venting system (AVS comprising a one-way valve, a blower and a battery in a housing to a FFR. The achieved reduction is quantified with a computational-fluid-dynamics model that considers conservation of mass, momentum and the dilute species, CO2, inside the FFR with and without the AVS. The results suggest that the AVS can reduce the CO2 levels inside the dead space at the end of expiration to around 0.4% as compared to a standard FFR, for which the CO2 levels during expiration reach the same concentration as that of the expired alveolar air at around 5%. In particular, during inspiration, the average CO2 volume fraction drops to near-to ambient levels of around 0.08% with the AVS. Overall, the time-averaged CO2 volume fractions inside the dead space for the standard FFR and the one with AVS are around 3% and 0.3% respectively. Further, the ability of the AVS to vent the dead-space air in the form of a jet into the ambient - similar to the jets arising from natural expiration without a FFR - ensures that the expired air is removed and diluted more efficiently than a standard FFR.

  15. Reduction of Carbon Dioxide in Filtering Facepiece Respirators with an Active-Venting System: A Computational Study.

    Science.gov (United States)

    Birgersson, Erik; Tang, Ee Ho; Lee, Wei Liang Jerome; Sak, Kwok Jiang

    2015-01-01

    During expiration, the carbon dioxide (CO2) levels inside the dead space of a filtering facepiece respirator (FFR) increase significantly above the ambient concentration. To reduce the CO2 concentration inside the dead space, we attach an active lightweight venting system (AVS) comprising a one-way valve, a blower and a battery in a housing to a FFR. The achieved reduction is quantified with a computational-fluid-dynamics model that considers conservation of mass, momentum and the dilute species, CO2, inside the FFR with and without the AVS. The results suggest that the AVS can reduce the CO2 levels inside the dead space at the end of expiration to around 0.4% as compared to a standard FFR, for which the CO2 levels during expiration reach the same concentration as that of the expired alveolar air at around 5%. In particular, during inspiration, the average CO2 volume fraction drops to near-to ambient levels of around 0.08% with the AVS. Overall, the time-averaged CO2 volume fractions inside the dead space for the standard FFR and the one with AVS are around 3% and 0.3% respectively. Further, the ability of the AVS to vent the dead-space air in the form of a jet into the ambient - similar to the jets arising from natural expiration without a FFR - ensures that the expired air is removed and diluted more efficiently than a standard FFR.

  16. Stage Identification in Air-gap Discharge of Oil-impregnated Paper Insulation Based on Wavelet Packet Energy Entropy%基于小波包能量熵的油纸绝缘气隙放电阶段识别

    Institute of Scientific and Technical Information of China (English)

    陈伟根; 谢波; 龙震泽; 崔鲁; 李永森; 周渠; 陈曦

    2016-01-01

    Air-gap discharge is the main type of partial discharge (PD) within power transformer. It is of great significance to study the discharge development stage for the monitoring and diagnosis of transformer potential faults. This paper build an air-gap discharge model in simulative transformer tank, collecting PD signals based on constant voltage method, utilizing wavelet packet decomposition method to partition the PD signal bands obtaining signal energy distribution in each frequency band as well as total signal energy tendency along with PD development process. The new PD parameter describing the development process, wavelet packet energy entropy, was proposed based on the signal energy variation in each frequency band. Due to the cyclic change of wavelet packet energy entropy, the step points of wavelet packet entropy are taken as the way to effectively divide the PD development stage. According to the thresholds of wavelet packet energy entropy in different stages, the PD development stages were identified.%能量分布以及局放发展过程信号总能量发展情况,基于不同频带下信号能量变化特征提出以小波包能量熵作为局部放电发展特性的新特征量,通过小波包能量熵在整个过程中的循环变化特征规律,提出以小波包能量熵"阶跃"断层点为支点的局部放电阶段有效划分方式,并根据小波包能量熵在不同阶段的阈值特点,建立通过阈值判定来识别局部放电发展阶段的模型.

  17. Dielectric barrier discharge processing of aerospace materials

    Science.gov (United States)

    Scott, S. J.; Figgures, C. C.; Dixon, D. G.

    2004-08-01

    We report the use of atmospheric pressure, air based, dielectric barrier discharges (DBD) to treat materials commonly used in the aerospace industries. The material samples were processed using a test-bed of a conventional DBD configuration in which the sample formed one of the electrodes and was placed in close proximity to a ceramic electrode. The discharges generated a powerful, cold oxidizing environment which was able to remove organic contaminants, etch primer and paint layers, oxidize aluminium and roughen carbon fibre composites by the selective removal of resin.

  18. Heat flux measured acoustically at Grotto Vent, a hydrothermal vent cluster on the Endeavour Segment, Juan de Fuca Ridge

    Science.gov (United States)

    Xu, G.; Jackson, D. R.; Bemis, K. G.; Rona, P. A.

    2013-12-01

    Over the past several decades, quantifying the heat output has been a unanimous focus of studies at hydrothermal vent fields discovered around the global ocean. Despite their importance, direct measurements of hydrothermal heat flux are very limited due to the remoteness of most vent sites and the complexity of hydrothermal venting. Moreover, almost all the heat flux measurements made to date are snapshots and provide little information on the temporal variation that is expected from the dynamic nature of a hydrothermal system. The Cabled Observatory Vent Imaging Sonar (COVIS, https://sites.google.com/a/uw.edu/covis/) is currently connected to the Endeavour node of the NEPTUNE Canada observatory network (http://www.neptunecanada.ca) to monitor the hydrothermal plumes issuing from a vent cluster (Grotto) on the Endeavour Segment of the Juan de Fuca Ridge. COVIS is acquiring a long-term (20-months to date) time series of the vertical flow rate and volume flux of the hydrothermal plume above Grotto through the Doppler analysis of the acoustic backscatter data (Xu et al., 2013). We then estimate the plume heat flux from vertical flow rate and volume flux using our newly developed inverse method. In this presentation, we will briefly summarize the derivation of the inverse method and present the heat-flux time series obtained consequently with uncertainty quantification. In addition, we compare our heat-flux estimates with the one estimated from the plume in-situ temperatures measured using a Remotely Operative Vehicle (ROV) in 2012. Such comparison sheds light on the uncertainty of our heat flux estimation. Xu, G., Jackson, D., Bemis, K., and Rona, P., 2013, Observations of the volume flux of a seafloor hydrothermal plume using an acoustic imaging sonar, Geochemistry, Geophysics Geosystems, 2013 (in press).

  19. Discovery of abundant hydrothermal venting on the ultraslow-spreading Gakkel ridge in the Arctic Ocean.

    Science.gov (United States)

    Edmonds, H N; Michael, P J; Baker, E T; Connelly, D P; Snow, J E; Langmuir, C H; Dick, H J B; Mühe, R; German, C R; Graham, D W

    2003-01-16

    Submarine hydrothermal venting along mid-ocean ridges is an important contributor to ridge thermal structure, and the global distribution of such vents has implications for heat and mass fluxes from the Earth's crust and mantle and for the biogeography of vent-endemic organisms. Previous studies have predicted that the incidence of hydrothermal venting would be extremely low on ultraslow-spreading ridges (ridges with full spreading rates discovery of such abundant venting, and its apparent localization near volcanic centres, requires a reassessment of the geologic conditions that control hydrothermal circulation on ultraslow-spreading ridges.

  20. Glow discharge based device for solving mazes

    Energy Technology Data Exchange (ETDEWEB)

    Dubinov, Alexander E., E-mail: dubinov-ae@yandex.ru; Mironenko, Maxim S.; Selemir, Victor D. [Russian Federal Nuclear Center − All-Russian Scientific and Research Institute of Experimental Physics (RFNC-VNIIEF), Sarov, Nizhni Novgorod region 607188 (Russian Federation); Sarov Institute of Physics and Technology (SarFTI) of National Research Nuclear University “MEPhI,” Sarov, Nizhni Novgorod region 607188 (Russian Federation); Maksimov, Artem N.; Pylayev, Nikolay A. [Russian Federal Nuclear Center − All-Russian Scientific and Research Institute of Experimental Physics (RFNC-VNIIEF), Sarov, Nizhni Novgorod region 607188 (Russian Federation)

    2014-09-15

    A glow discharge based device for solving mazes has been designed and tested. The device consists of a gas discharge chamber and maze-transformer of radial-azimuth type. It allows changing of the maze pattern in a short period of time (within several minutes). The device has been tested with low pressure air. Once switched on, a glow discharge has been shown to find the shortest way through the maze from the very first attempt, even if there is a section with potential barrier for electrons on the way. It has been found that ionization waves (striations) can be excited in the maze along the length of the plasma channel. The dependancy of discharge voltage on the length of the optimal path through the maze has been measured. A reduction in discharge voltage with one or two potential barriers present has been found and explained. The dependency of the magnitude of discharge ignition voltage on the length of the optimal path through the maze has been measured. The reduction of the ignition voltage with the presence of one or two potential barriers has been observed and explained.

  1. Filament Discharge Phenomena in Fingerprint Acquisition by Dielectric Barrier Discharge

    Institute of Scientific and Technical Information of China (English)

    WENG Ming; XU Weijun; LIU Qiang

    2007-01-01

    In this paper, the dielectric barrier discharge fingerprint acquisition technique is introduced. The filament discharge phenomena were observed in the process of fingerprint acquisition. The filament discharge reduced the quality of fingerprint images. Obviously, it was necessary to eliminate streamer discharges in order to get good fingerprint images. The streamer discharge was considered to be the cause of the filament discharge in the experiment. The relationship between the critical electric field and the discharge gap was calculated with the Raether's model of streamer discharge. The calculated results and our experiment proved that it would be difficult for the streamer discharge to occur when the discharge gap was narrow. With a narrow discharge gap, the discharge was homogeneous, and the fingerprint images were clear and large in area. The images obtained in the experiment are very suitable for fingerprint identification as they contain more information.

  2. Analysis of containment venting following a core damage at a BWR Mark I using THALES-2

    Energy Technology Data Exchange (ETDEWEB)

    Widodo, Surip [Nuclear Safety Technology Development Center, National Nuclear Energy Agency (BATAN), Tangerang (Indonesia); Ishikawa, Jun; Muramatsu, Ken [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Sakamoto, Toru [Toshiba Advanced System Co., Kawasaki, Kanagawa (Japan)

    2000-11-01

    Analysis of containment venting following a core damage at a boiling water reactor (BWR) Mark I using THALES-2 was performed. In this analysis, the effect of various parameters, namely, the areas of the vent path, containment venting pressure, and accident sequences on the containment thermodynamic response, and radionuclide transport and release in the containment venting at a BWR was examined. The code THALES-2B developed by the Japan Atomic Energy Research Institute (JAERI) was used in this analysis. The model plant in this analysis was the Browns Ferry plant. From this analysis was found that the 4-inch pipe of containment venting flow path is sufficient to maintain the containment pressure in the specified range if the containment was pressurized by the decay heat power. The entrainment by the pool swelling as well as by the flashing was not occurred during the containment venting. The source terms are not sensitive to the variation of containment venting flow path area. The containment venting pressure operation setting point has important rule in the containment venting. In the containment venting, the source terms are not sensitive to the accident sequence, except for Sr source term. In order to get better understanding on the containment venting strategy, the following analyses are necessary. Analyses of accident sequence which has a high power such as anticipated transient without scram are necessary, as well as analyses of accident sequence which pressurize the containment before the core damage. (author)

  3. Quantitative spatiotemporal characterization of methane venting from lake sediments

    Science.gov (United States)

    Scandella, B.; Pillsbury, L.; Weber, T.; Ruppel, C. D.; Hemond, H.; Juanes, R.

    2014-12-01

    Methane is a potent greenhouse gas, and the production and emission of methane from sediments in inland waters and shallow oceans both contributes to and may be exacerbated by climate change. In some of these shallow-water settings, methane fluxes are often controlled by episodic free-gas venting. The fraction of the methane released from the sediments that bypasses dissolution in the water column and reaches the atmosphere impacts the magnitude of the climate forcing, and this fraction depends critically on the mode and spatiotemporal characteristics of the bubble releases. The spacing and persistence of the gas vents may be determined by the heterogeneity of the methane source, but within regions of uniform methanogenesis they arise from the competition between mechanisms driving lateral and vertical transport of methane in the sediments. Here, we present measurements of the spacing, persistence and variability in intensity of methane vents within a wide area of lake sediments (~400 m2) and over a multi-month period. The measurements were made using a fixed-location Imagenex DeltaT 837B multibeam sonar, which was calibrated to quantify gas fluxes with unprecedented spatial and temporal resolution (~0.5 m, 6 Hz). Drops in hydrostatic pressure were a characteristic trigger for the sonar-detected ebullition events, and the episodicity of the fluxes is reproduced with a mechanistic numerical model of methane venting through dynamic conduits that dilate in response to hydrostatic unloading. The spatial characteristics of the sonar-detected vents inform conceptual and mathematical models of methane transport and release from deformable sediments, as well as the uncertainty associated with upscaling. Taken together, these results point towards a better understanding of the microscale processes controlling methane venting from deformable sediments, as well as their impact on large-scale methane fluxes from shallow-water bodies. Figure: Top: time series of daily sonar

  4. Capacitor discharge engineering

    CERN Document Server

    Früngel, Frank B A

    1976-01-01

    High Speed Pulse Technology, Volume III: Capacitor Discharge Engineering covers the production and practical application of capacitor dischargers for the generation and utilization of high speed pulsed of energy in different forms. This nine-chapter volume discusses the principles of electric current, voltage, X-rays, gamma rays, heat, beams of electrons, neutrons and ions, magnetic fields, sound, and shock waves in gases and liquids. Considerable chapters consider the applications of capacitor discharges, such as impulse hardening of steel, ultrapulse welding of precision parts, X-ray flash t

  5. Cheyenne Mountain Air Force Station NPDES Permit

    Science.gov (United States)

    Under NPDES permit CO-0034762, the Cheyenne Mountain Air Force Station is authorized to discharge from the interior storm drainage system and air exhaust stacks at the Cheyenne Mountain Complex, in El Paso County, Colorado, to tributaries Fountain Creek.

  6. Experimental Study on Gas Discharge Excited by 60 kHz High Voltage Power Supply with Pin-to-pin Electrode in Atmospheric Air%大气压空气中尖-尖间隙60kHz高压放电实验研究

    Institute of Scientific and Technical Information of China (English)

    许家雨; 章程; 邵涛; 段立伟; 任成燕; 严萍

    2012-01-01

    大气压低温放电等离子体在点火和辅助燃烧方面有着广泛的应用前景。为此,基于60kHz的高频高压电源,利用尖-尖电极的极不均匀场结构,在空气中获得了稳定的大气压辉光放电,通过测量电压电流并拍摄放电图像,分析了放电过程,并计算得到了电极压降和位移电流。间隙击穿前,间隙距离不变时位移电流随着施加电压而呈线性变化;问隙击穿后,电源输出电压不变时间隙放电电压随着间隙距离而呈线性变化。结果表明放电过程经历3种放电模式(电晕放电、火花放电、辉光放电),放电稳定性随着气体体积流量的增大而减小,在气体体积流量〈3L/min时,可以实现稳定辉光放电。相关结果可为等离子体点火和辅助燃烧提供参考。%Atmospheric-pressure non-thermal plasma has been widely used in plasma-induced ignition and plasma- assisted combustion. In this article, stable glow discharge excited by a high frequency and high voltage power supply is obtained with a pin-to-pin electrode geometry, and the discharge process is investigated by the measurement of voltage-current and the discharge images. Furthermore, the voltage drop at the electrodes and the displacement current is calculated. When the air gap is fixed, displacement current linearly changes with the applied voltage before breakdown. After breakdown takes place, the voltage across the gap changes linearly with the air gap when the output voltage of the generator is fixed. The experimental results show that corona spark, and g)ow discharge occurs in the development of the discharge process, respectively. The stability of the discharge decreases as the increase of the air flow, and the glow discharge can be kept when the air flow is below 3 L/rain. The experimental results can be referred in ignition and combustion.

  7. 30 CFR 250.1161 - When may I flare or vent gas for extended periods of time?

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false When may I flare or vent gas for extended... Production Requirements Flaring, Venting, and Burning Hydrocarbons § 250.1161 When may I flare or vent gas... flare or vent gas for an extended period of time. The Regional Supervisor will specify the...

  8. Pneumonia - children - discharge

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000011.htm Pneumonia in children - discharge To use the sharing features ... this page, please enable JavaScript. Your child has pneumonia, which is an infection in the lungs. In ...

  9. Pneumonia - adults - discharge

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000017.htm Pneumonia in adults - discharge To use the sharing features on this page, please enable JavaScript. You have pneumonia, which is an infection in your lungs. In ...

  10. Pectus excavatum - discharge

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000298.htm Pectus excavatum - discharge To use the sharing features on this ... You or your child had surgery to correct pectus excavatum. This is a deformity of the front of ...

  11. Cosmetic breast surgery - discharge

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000273.htm Cosmetic breast surgery - discharge To use the sharing features on this page, please enable JavaScript. You had cosmetic breast surgery to change the size or shape ...

  12. Chest radiation - discharge

    Science.gov (United States)

    Radiation - chest - discharge; Cancer - chest radiation; Lymphoma - chest radiation ... When you have radiation treatment for cancer, your body goes through changes. About 2 weeks after your first treatment: It may be hard ...

  13. Breast radiation - discharge

    Science.gov (United States)

    Radiation - breast - discharge ... away around 4 to 6 weeks after the radiation treatment is over. You may notice changes in ... breast looks or feels (if you are getting radiation after a lumpectomy). These changes include: Soreness or ...

  14. Abdominal radiation - discharge

    Science.gov (United States)

    Radiation - abdomen - discharge; Cancer - abdominal radiation; Lymphoma - abdominal radiation ... When you have radiation treatment for cancer, your body goes through changes. About 2 weeks after radiation treatment starts, you might notice changes ...

  15. Corneal transplant - discharge

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000243.htm Corneal transplant - discharge To use the sharing features on this page, please enable JavaScript. You had a corneal transplant. Most of the tissue of your cornea (the ...

  16. Brain radiation - discharge

    Science.gov (United States)

    Radiation - brain - discharge; Cancer-brain radiation; Lymphoma - brain radiation; Leukemia - brain radiation ... Decadron) while you are getting radiation to the brain. It may make you hungrier, cause leg swelling ...

  17. Capacitor discharge pulse analysis.

    Energy Technology Data Exchange (ETDEWEB)

    Baker, Michael Sean; Griffiths, Stewart K.; Tanner, Danelle Mary

    2013-08-01

    Capacitors used in firing sets and other high discharge current applications are discharge tested to verify performance of the capacitor against the application requirements. Parameters such as capacitance, inductance, rise time, pulse width, peak current and current reversal must be verified to ensure that the capacitor will meet the application needs. This report summarizes an analysis performed on the discharge current data to extract these parameters by fitting a second-order system model to the discharge data and using this fit to determine the resulting performance metrics. Details of the theory and implementation are presented. Using the best-fit second-order system model to extract these metrics results in less sensitivity to noise in the measured data and allows for direct extraction of the total series resistance, inductance, and capacitance.

  18. Earthquakes increase hydrothermal venting and nutrient inputs into the Aegean

    Science.gov (United States)

    Dando, P. R.; Hughes, J. A.; Leahy, Y.; Taylor, L. J.; Zivanovic, S.

    1995-05-01

    Areas of submarine gas and water venting around the island of Milos, in the Hellenic volcanic island arc, were mapped. Water samples were collected from five stations in the geothermally active Paleohori Bay on 15 March 1992. Seismic events, of M s 5.0 and 4.4, occurred south of the Bay on 20 March and the sampling was repeated after these. Phosphate and manganese in the water column increased by 360% after the seismic activity. Analysis of water samples collected from gas and water seeps and of interstitial water from sediment cores showed that the hot sediment in the Bay was enriched in phosphate, to a mean concentration of 65 μmol l -1 in the interstitial water. The number of geothermally active areas in the Aegean, together with the extent of venting and the frequency of earthquakes suggests that the hydrothermal areas may be an important source of phosphate in this oligotrophic Sea.

  19. Managing reservoir sedimentation by venting turbidity currents:A review

    Institute of Scientific and Technical Information of China (English)

    Sabine Chamoun; Giovanni De Cesare; Anton J. Schleiss

    2016-01-01

    Reservoir sedimentation is an issue that dam operators are increasingly facing as dams are aging. Not only does it reduce a reservoir's capacity but it also affects its outlet structures such as bottom outlets and powerhouse intakes. Sedimentation may also impoverish downstream ecosystems. For these reasons, several strategies for sediment management are being investigated and applied worldwide. Among these methods, venting of turbidity currents reaching the dam can be very beneficial and economical. This measure helps in preserving a certain continuity of sediment transport in rivers obstructed by dams. However, several practical but also theoretical challenges hamper this technique, rendering its use less common and its aspects rela-tively unknown. The present paper aims to gather the actual state-of-the-art concerning turbidity currents venting and to present an outlook for future development and research in this field.

  20. Identifying discharge practice training needs.

    Science.gov (United States)

    Lees, L; Emmerson, K

    A training needs analysis tool was developed to identify nurses' discharge training needs and to improve discharge practice. The tool includes 49 elements of discharge practice subdivided into four areas: corporate, operational, clinical and nurse-led discharge. The tool was disseminated to 15 wards on two hospital sites with assistance from the practice development team. Analysis of discharge training is important to assess discharge training needs and to identify staff who may assist with training.

  1. Sprite discharges on Venus and Jupiter-like planets: a laboratory investigation.

    NARCIS (Netherlands)

    Dubrovin, S.; Nijdam, S.; Veldhuizen, E.M. van; Ebert, U.; Yair, Y.; Price, C.

    2010-01-01

    Large sprite discharges at high atmospheric altitudes have been found to be physically similar to small streamer discharges in air at sea level density. Based on this understanding, we investigate possible sprite discharges on Venus or Jupiter‐like planets through laboratory experiments on streamers

  2. Hydro-Thermal Vent Mapping with Multiple AUV’s

    Science.gov (United States)

    2016-06-07

    Lisbon (IST) have a long standing memorandum of agreement dating back to 1994 for the exchange of scientific ideas, visits of faculty and students...and to perform collaborative work . In the past we have collaborated on joint papers, the shared supervision of doctoral work , and a shared effort on the...a scientific need to study the vents with more detail than possible using divers and cameras, this also presents a parallel to the mine field

  3. Catalytic Diversity in Alkaline Hydrothermal Vent Systems on Ocean Worlds

    Science.gov (United States)

    Cameron, Ryan D.; Barge, Laura; Chin, Keith B.; Doloboff, Ivria J.; Flores, Erika; Hammer, Arden C.; Sobron, Pablo; Russell, Michael J.; Kanik, Isik

    2016-10-01

    Hydrothermal systems formed by serpentinization can create moderate-temperature, alkaline systems and it is possible that this type of vent could exist on icy worlds such as Europa which have water-rock interfaces. It has been proposed that some prebiotic chemistry responsible for the emergence of life on Earth and possibly other wet and icy worlds could occur as a result ofredox potential and pH gradients in submarine alkaline hydrothermal vents (Russell et al., 2014). Hydrothermal chimneys formed in laboratory simulations of alkaline vents under early Earth conditions have precipitate membranes that contain minerals such as iron sulfides, which are hypothesized to catalyze reduction of CO2 (Yamaguchi et al. 2014, Roldan et al. 2014) leading to further organic synthesis. This CO2 reduction process may be affected by other trace components in the chimney, e.g. nickel or organic molecules. We have conducted experiments to investigate catalytic properties of iron and iron-nickel sulfides containing organic dopants in slightly acidic ocean simulants relevant to early Earth or possibly ocean worlds. We find that the electrochemical properties of the chimney as well as the morphology/chemistry of the precipitate are affected by the concentration and type of organics present. These results imply that synthesis of organics in water-rock systems on ocean worlds may lead to hydrothermal precipitates which can incorporate these organic into the mineral matrix and may affect the role of gradients in alkaline vent systems.Therefore, further understanding on the electroactive roles of various organic species within hydrothermal chimneys will have important implications for habitability as well as prebiotic chemistry. This work is funded by NASA Astrobiology Institute JPL Icy Worlds Team and a NAI Director's Discretionary Fund award.Yamaguchi A. et al. (2014) Electrochimica Acta, 141, 311-318.Russell, M. J. et al. (2014), Astrobiology, 14, 308-43.Roldan, A. (2014) Chem. Comm. 51

  4. Halophilic Archaea determined from geothermal steam vent aerosols.

    Science.gov (United States)

    Ellis, Dean G; Bizzoco, Richard W; Kelley, Scott T

    2008-06-01

    Hydrothermal vents, known as 'fumaroles', are ubiquitous features of geothermal areas. Although their geology has been extensively characterized, little is known about the subsurface microbial ecology of fumaroles largely because of the difficulty in collecting sufficient numbers of cells from boiling steam water for DNA extraction and culture isolation. Here we describe the first collection, molecular analysis and isolation of microbes from fumarole steam waters in Russia (Kamchatka) and the USA (Hawaii, New Mexico, California and Wyoming). Surprisingly, the steam vent waters from all the fumaroles contained halophilic Archaea closely related to the Haloarcula spp. found in non-geothermal salt mats, saline soils, brine pools and salt lakes around the world. Microscopic cell counting estimated the cell dispersal rate at approximately 1.6 x 10(9) cells year(-1) from a single fumarole. We also managed to enrich microbes in high-salt media from every vent sample, and to isolate Haloarcula from a Yellowstone vent in a 20% salt medium after a month-long incubation, demonstrating both salt tolerance and viability of cells collected from high-temperature steam. Laboratory tests determined that microbes enriched in salt media survived temperatures greater than 75 degrees C for between 5 and 30 min during the collection process. Hawaiian fumaroles proved to contain the greatest diversity of halophilic Archaea with four new lineages that may belong to uncultured haloarchaeal genera. This high diversity may have resulted from the leaching of salts and minerals through the highly porous volcanic rock, creating a chemically complex saline subsurface.

  5. Simulation of nonstationary phenomena in atmospheric-pressure glow discharge

    Science.gov (United States)

    Korolev, Yu. D.; Frants, O. B.; Nekhoroshev, V. O.; Suslov, A. I.; Kas'yanov, V. S.; Shemyakin, I. A.; Bolotov, A. V.

    2016-06-01

    Nonstationary processes in atmospheric-pressure glow discharge manifest themselves in spontaneous transitions from the normal glow discharge into a spark. In the experiments, both so-called completed transitions in which a highly conductive constricted channel arises and incomplete transitions accompanied by the formation of a diffuse channel are observed. A model of the positive column of a discharge in air is elaborated that allows one to interpret specific features of the discharge both in the stationary stage and during its transition into a spark and makes it possible to calculate the characteristic oscillatory current waveforms for completed transitions into a spark and aperiodic ones for incomplete transitions. The calculated parameters of the positive column in the glow discharge mode agree well with experiment. Data on the densities of the most abundant species generated in the discharge (such as atomic oxygen, metastable nitrogen molecules, ozone, nitrogen oxides, and negative oxygen ions) are presented.

  6. Containment Depressurization Capabilities of Filtered Venting System in 1000 MWe PWR with Large Dry Containment

    Directory of Open Access Journals (Sweden)

    Sang-Won Lee

    2014-01-01

    Full Text Available After the Fukushima Daiichi nuclear power plant accident, the Korean government and nuclear industries performed comprehensive safety inspections on all domestic nuclear power plants against beyond design bases events. As a result, a total of 50 recommendations were defined as safety improvement action items. One of them is installation of a containment filtered venting system (CFVS or portable backup containment spray system. In this paper, the applicability of CFVS is examined for OPR1000, a 1000 MWe PWR with large dry containment in Korea. Thermohydraulic analysis results show that a filtered discharge flow rate of 15 [kg/s] at 0.9 [MPa] is sufficient to depressurize the containment against representative containment overpressurization scenarios. Radiological release to the environment is reduced to 10-3 considering the decontamination factor. Also, this cyclic venting strategy reduces noble gas release by 50% for 7 days. The probability of maintaining the containment integrity in level 2 probabilistic safety assessment (PSA initiating events is improved twofold, from 43% to 87%. So, the CFVS can further improve the containment integrity in severe accident conditions.

  7. A Method for Generating Diffuse Discharge via Repetitive Nanosecond Pulses and Wire Electrodes in Room-temperature Atmospheric Air%利用重复频率纳秒脉冲和线电极产生常温常压下的大气压弥散放电

    Institute of Scientific and Technical Information of China (English)

    李黎; 刘云龙; 俞斌; 葛亚峰; 林福昌

    2014-01-01

    The non-equilibrium plasmas produced by diffuse discharges have a great potential of application in many high technology fields. In room-temperature atmospheric air, the formation mechanism of non-equilibrium plasma is discussed and analysed. It is concluded that generating diffuse discharge in open air should meet the three conditions: low-voltage excitation, plentiful electron avalanches and temperature inhibition of spatial charge particles. A method of generating diffuse discharge is proposed and implemented. Based on runaway electrons breakdown theory, a low duty-ratio, high voltage repetitive nanosecond pulse generator is chosen as discharge excitation source. Using the wire-electrodes with small curvature radius, the gaps with highly non-uniform electrical field are structured. The experiments are performed in linear-type and ring-type electrode pairs. The results prove that the proposed method can generate typical diffuse discharges in cm. gaps via nanosecond pluses with less than 100kV peak voltage, hundreds of Hz repetitive frequency.%大气压弥散放电产生非热平衡等离子体在诸多高新技术领域具有较大应用潜力。分析了在常温常压的大气压条件下,形成和维持非热平衡等离子体的机制,提出了实现弥散放电应设法满足低放电电压、多电子崩发展和带电粒子温度抑制的条件。由此设计了在开放的大气压空气环境中实现大面积弥散放电的装置。根据逃逸电子击穿理论,选择重复频率、较低占空比的纳秒脉冲电激励方式作为弥散放电的低电压驱动源。利用线型电极的小曲率半径,构成极不均匀电场间隙。弥散放电分别在直线型电极和圆环型电极中进行。实验结果表明,所研制的放电装置能够以百kV以内峰值纳秒脉冲电压、数百Hz的频率激励若干厘米等级间距的大气压弥散放电。

  8. Vent sizing: analysis of the blowdown of a hybrid non tempered system.

    Science.gov (United States)

    Véchot, Luc; Minko, Wilfried; Bigot, Jean-Pierre; Kazmierczak, Marc; Vicot, Patricia

    2011-07-15

    The runaway and blowdown of a non tempered hybrid chemical system (30% cumene hydroperoxide) exposed to an external heat input was investigated using a 0.1l scale tool. The maximum temperature and the maximum temperature rise rate were showed to be sensitive to the vent size. An Antoine type correlation between the maximum temperatures and pressures was observed. These resulted from the presence of vapour, mainly generated by the reaction products. Increasing the initial filling ratio resulted in an earlier vent opening but did not have a significant influence on the blow-down. Three types of mass venting behaviour were observed, when changing the vent area to volume ratio (A/V): • for large A/V, two-phase venting occurred from the vent opening until the end of the second pressure peak; • for medium A/V, two-phase venting occurred before and after the turnaround. The data seem to indicate that gas only venting occurred at turn-around; • for low A/V, two-phase venting was observed only after the second pressure peak. Two-phase venting after the second pressure peak probably results from the boiling of the hot reaction products at low pressure.

  9. Upstream petroleum industry flaring and venting report : industry performance for year ending December 31, 2005

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-10-15

    This report provided statistical data concerning solution gas flaring and venting in the upstream petroleum industry in Alberta. In their 2003 Upstream Petroleum Industry Flaring and Venting Report, the Alberta Energy and Utilities Board (EUB) made commitments to identify and implement a number of conservation measures aimed at reducing the volumes of solution gas vented from crude bitumen operations. As a result of the measures, venting from crude bitumen batteries decreased by 18.9 per cent in 2005. Solution gas conservation for 2005 was 96.3 per cent, the highest conservation level achieved to date. Solution gas flaring for 2005 was 71.9 per cent less than the 1996 baseline. A slight increase in solution gas flaring was attributed to crude bitumen operations. Solution gas venting for 2005 was 58.6 per cent less than the 2000 venting baseline. An analysis of the data suggested that significant progress has been made in reducing solution gas flaring in Alberta, and that venting reductions realized in 2005 continue the trend of significant reductions since 2000. Although the downward trend in the reduction of venting since 2000 is encouraging, the EUB continues to be concerned about solution gas venting associated with crude bitumen projects. It was concluded that the EUB will continue to work with all stakeholders to identify additional venting reduction strategies. 5 tabs., 3 figs.

  10. Euryhaline Halophilic Microorganisms From the Suiyo Seamount Hydrothermal Vents.

    Science.gov (United States)

    Okamoto, T.; Kimura, H.; Maruyama, A.; Naganuma, T.

    2002-12-01

    The euryhaline halophilic microorganisms grow in a wide salinity range from 15% NaCl or to even saturation (about 30% NaCl). A number of euryhaline halophiles have been found in a wide range of habitats from oceanic and terrestrial regimes, from deep-sea vents and seeps, and from Antarctic sea ice and terrains. We have isolated the euryhaline strains independently from a Mid-Atlantic Ridge vent fluids and Antarctic terrains are closely related species of the genus Halomonas. Some euryhaline halophiles maintain intracellular osmotic balance by controlling the concentration of compatible solute such as ectoine. This compatible solute not only stabilizes the proteins from denaturation caused by high salt concentration but also serves as a protectant against stresses such as heating, freezing and drying. The sub-seafloor structure of a hydrothermal vent is highly complicated with mosaic heterogeneity of physicochemical parameters such as temperature and salinity. This premise led us to the hypothesis that some euryhaline halophiles including Halomonas species well adapt to a wide salinity-ranged habitat in the sub-vent. To test this hypothesis, isolation and characterization of euryhaline halophiles from the Suiyo Seamount hydrothermal vents were conducted the drill-cored rock samples from the sites APSK-02, 03, and 07 and the filter-trapped fluid particle samples from the sites APSK-01 and 05 were used. For initial cultivation, a heterotrophic bacterial medium of 15% NaCl was used. The samples was added to the medium and incubated under both aerobic and anaerobic conditions at room temperature. A total of 5 euryhaline halophilic strains were obtained and phylogenetically characterized: two strains (both related to Marinobacter) from APSK-02 core section 2; one strain (related to H. meridiana) from APSK-07 core section 3; and two strains (related to H. meridiana and H. variabilis) from APSK-01 trapped particles. In addition, some thermophilic halophiles that grow at 20

  11. ZnO Nanowire-Based Corona Discharge Devices Operated Under Hundreds of Volts

    OpenAIRE

    Yang, Wenming; Zhu, Rong; Zong, Xianli

    2016-01-01

    Minimizing the voltage of corona discharges, especially when using nanomaterials, has been of great interest in the past decade or so. In this paper, we report a new corona discharge device by using ZnO nanowires operated in atmospheric air to realize continuous corona discharge excited by hundreds of volts. ZnO nanowires were synthesized on microelectrodes using electric-field-assisted wet chemical method, and a thin tungsten film was deposited on the microchip to enhance discharging perform...

  12. Self-deformation in a dc driven helium jet micro discharge

    CERN Document Server

    Xu, Shaofeng

    2016-01-01

    We report on the experimental observation of three dimensional self-deformation in an atmospheric micro discharge of the helium microjet through a tube into the ambient air upon a water electrode. The geometry of the discharge system is axial symmetric. While decreasing the discharge current, three dimensional collective motion of plasma filaments are directly observed. The three dimensional configuration of the discharge self changed from an axial symmetrical horn to a rectangular horn when the water acts as a cathode.

  13. Self-deformation in a direct current driven helium jet micro discharge

    Energy Technology Data Exchange (ETDEWEB)

    Xu, S. F.; Zhong, X. X., E-mail: xxzhong@sjtu.edu.cn [State Key Laboratory of Advanced Optical Communication Systems and Networks and Key Laboratory for Laser Plasmas (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2016-01-15

    We report on the experimental observation of three dimensional self-deformation in an atmospheric micro discharge of the helium microjet through a tube into the ambient air upon a water electrode. The geometry of the discharge system is axial symmetric. While decreasing the discharge current, three dimensional collective motion of plasma filaments is directly observed. The three dimensional configuration of the discharge self changed from an axial symmetrical horn to a rectangular horn when the water acts as a cathode.

  14. Vent fluid chemistry in Bahía Concepción coastal submarine hydrothermal system, Baja California Sur, Mexico

    Science.gov (United States)

    Prol-Ledesma, R. M.; Canet, C.; Torres-Vera, M. A.; Forrest, M. J.; Armienta, M. A.

    2004-10-01

    Shallow submarine hydrothermal activity has been observed in the Bahía Concepción bay, located at the Gulf coast of the Baja California Peninsula, along faults probably related to the extensional tectonics of the Gulf of California region. Diffuse and focused venting of hydrothermal water and gas occurs in the intertidal and shallow subtidal areas down to 15 m along a NW-SE-trending onshore-offshore fault. Temperatures in the fluid discharge area vary from 50 °C at the sea bottom up to 87 °C at a depth of 10 cm in the sediments. Chemical analyses revealed that thermal water is enriched in Ca, As, Hg, Mn, Ba, HCO 3, Li, Sr, B, I, Cs, Fe and Si, and it has lower concentrations of Cl, Na, SO 4 and Br than seawater. The chemical characteristics of the water samples indicate the occurrence of mixing between seawater and a thermal end-member. Stable isotopic oxygen and hydrogen composition of thermal samples plot close to the Local Meteoric Water Line on a mixing trend between a thermal end-member and seawater. The composition of the thermal end-member was calculated from the chemistry of the submarine samples data by assuming a negligible amount of Mg for the thermal end-member. The results of the mixing model based on the chemical and isotopic composition indicate a maximum of 40% of the thermal end-member in the submarine vent fluid. Chemical geothermometers (Na/Li, Na-K-Ca and Si) were applied to the thermal end-member concentration and indicate a reservoir temperature of approximately 200 °C. The application of K-Mg and Na/Li geothermometers for vent fluids points to a shallow equilibrium temperature of about 120 °C. Results were integrated in a hydrogeological conceptual model that describes formation of thermal fluids by infiltration and subsequent heating of meteoric water. Vent fluid is generated by further mixing with seawater.

  15. Springs, streams, and gas vent on and near Mount Adams volcano, Washington

    Science.gov (United States)

    Nathenson, Manuel; Mariner, Robert H.

    2013-01-01

    Springs and some streams on Mount Adams volcano have been sampled for chemistry and light stable isotopes of water. Spring temperatures are generally cooler than air temperatures from weather stations at the same elevation. Spring chemistry generally reflects weathering of volcanic rock from dissolved carbon dioxide. Water in some springs and streams has either dissolved hydrothermal minerals or has reacted with them to add sulfate to the water. Some samples appear to have obtained their sulfate from dissolution of gypsum while some probably involve reaction with sulfide minerals such as pyrite. Light stable isotope data for water from springs follow a local meteoric water line, and the variation of isotopes with elevation indicate that some springs have very local recharge and others have water from elevations a few hundred meters higher. No evidence was found for thermal or slightly thermal springs on Mount Adams. A sample from a seeping gas vent on Mount Adams was at ambient temperature, but the gas is similar to that found on other Cascade volcanoes. Helium isotopes are 4.4 times the value in air, indicating that there is a significant component of mantle helium. The lack of fumaroles on Mount Adams and the ambient temperature of the gas indicates that the gas is from a hydrothermal system that is no longer active.

  16. Microwave Discharge Ion Sources

    CERN Document Server

    Celona, L

    2013-01-01

    This chapter describes the basic principles, design features and characteristics of microwave discharge ion sources. A suitable source for the production of intense beams for high-power accelerators must satisfy the requirements of high brightness, stability and reliability. The 2.45 GHz off-resonance microwave discharge sources are ideal devices to generate the required beams, as they produce multimilliampere beams of protons, deuterons and singly charged ions. A description of different technical designs will be given, analysing their performance, with particular attention being paid to the quality of the beam, especially in terms of its emittance.

  17. Dielectric Barrier Discharge Air Plasma at Atmospheric Pressure Induced Oxidative Stress in Saccharomyces cerevisiae%大气压介质阻挡放电空气等离子体引起酿酒酵母氧化应激的研究

    Institute of Scientific and Technical Information of China (English)

    陈慧黠; 修志龙; 白凤武

    2013-01-01

    在产生等离子体的过程中会同时产生大量的自由基和准分子.作者研究了经大气压介质阻挡放电(dielectric barrier discharge,DBD)空气等离子体处理后酿酒酵母(Saccharomyce cerevisiae)细胞的氧化应激,发现酿酒酵母细胞在DBD空气等离子体处理后,胞内总抗氧化能力和谷胱甘肽还原酶活力都不同程度被激活,丙二醛含量也随处理时间的延长不断增加,胞内活性氧(reactive oxygen species,ROS)含量明显增加,细胞周期也出现严重的G1期阻滞,说明等离子体产生的大量自由基可引发酵母细胞的氧化应激.%Atmospheric pressure dielectric barrier discharge (DBD) air plasma is a source of reactive species,such as OH*,H*,O*,H2O2,O3,etc.The oxidative stress in Saccharomyces cerevisiae which was exposed to DBD air plasma at atmospheric pressure was studied.It was showed that the intracellular total antioxidant capability (T-AOC) and activity of glutathione reductase (GR) were activated,malondialdehyde (MDA) content increased in a treatment time-dependent manner,intracellular reactive oxygen species (ROS) content increased,and cell cycle arrested in G1 phase significantly.It was proved that oxidative stress was induced in S.cerevisiae when the cells were exposed to DBD air plasma.

  18. Zero Gravity Cryogenic Vent System Concepts for Upper Stages

    Science.gov (United States)

    Ravex, Alain; Flachbart, Robin; Holt, Barney

    The capability to vent in zero gravity without resettling is a technology need that involves practically all uses of sub-critical cryogenics in space. Venting without resettling would extend cryogenic orbital transfer vehicle capabilities. However, the lack of definition regarding liquid/ullage orientation coupled with the somewhat random nature of the thermal stratification and resulting pressure rise rates, lead to significant technical challenges. Typically a zero gravity vent concept, termed a thermodynamic vent system (TVS), consists of a tank mixer to destratify the propellant, combined with a Joule-Thomson (J-T) valve to extract thermal energy from the propellant. Marshall Space Flight Center's (MSFC's) Multipurpose Hydrogen Test Bed (MHTB) was used to test both spray bar and axial jet TVS concepts. The axial jet system consists of a recirculation pump heat exchanger unit. The spray bar system consists of a recirculation pump, a parallel flow concentric tube, heat exchanger, and a spray bar positioned close to the longitudinal axis of the tank. The operation of both concepts is similar. In the mixing mode, the recirculation pump withdraws liquid from the tank and sprays it into the tank liquid, ullage, and exposed tank surfaces. When energy extraction is required, a small portion of the recirculated liquid is passed sequentially through the J-T expansion valve, the heat exchanger, and is vented overboard. The vented vapor cools the circulated bulk fluid, thereby removing thermal energy and reducing tank pressure. The pump operates alone, cycling on and off, to destratify the tank liquid and ullage until the liquid vapor pressure reaches the lower set point. At that point, the J-T valve begins to cycle on and off with the pump. Thus, for short duration missions, only the mixer may operate, thus minimizing or even eliminating boil-off losses. TVS performance testing demonstrated that the spray bar was effective in providing tank pressure control within a 6

  19. Functional and hierarchical interactions among zebrafish vox/vent homeobox genes.

    Science.gov (United States)

    Gilardelli, Claudio N; Pozzoli, Ombretta; Sordino, Paolo; Matassi, Giorgio; Cotelli, Franco

    2004-07-01

    The vertebrate Vox/Vent family of transcription factors plays a crucial role in the establishment of the dorsoventral (DV) axis, by repressing organizer genes such as bozozok/dharma, goosecoid, and chordino. In Danio rerio (zebrafish), members of the vox/vent gene family (vox/vega1, vent/vega2, and ved) are thought to share expression patterns and functional properties. Bringing novel insights in the differential activity of the zebrafish vox/vent genes, we propose a critical role for the ved gene in DV patterning of vertebrate embryos. ved is not only expressed as a maternal gene, but it also appears to function as a repressor of dorsal factors involved in organizer formation. At early- and mid-gastrula stage, ved appears to be finely controlled by antagonist crosstalks in a complex regulatory network, involving gradients of bone morphogenetic protein (BMP) activity, dorsal factors, and vox/vent family members. We show that ved transcripts are ventrally restricted by BMP factors such as bmp2b, bmp7, smad5, and alk8, and by dorsal factors (chd and gsc). Alteration of ved expression in both vox and vent deletion mutants and vox and vent mRNAs-injected embryos, suggests that vox and vent function downstream of BMP signaling to negatively regulate ved expression. This inhibitory role is emphasized by a vox and vent redundant activity, compared with single gene effects.

  20. Upstream petroleum industry flaring and venting report : Industry performance for year ending December 31, 2002

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-09-01

    The largest source of flaring and venting in Alberta is solution gas, accounting for 66 per cent of total emissions in 2002. A summary of flared and vented volumes for the different oil and gas industry sources, such as well tests, gas plants, gas gathering systems, transmission lines, and batteries was presented in this report. It also contained detailed information on solution gas conserved, flared, and vented during 2002. Rankings of companies was established based on solution gas flared plus vented, solution gas flared, and solution gas vented, from crude oil and bitumen batteries. The ranking is provincial and also by the Energy Utilities Board (EUB) Field Centre area. The data used in the preparation of this report is submitted by companies. Considerable progress was made in the reduction of flaring and venting volumes for all upstream oil and gas sources, as demonstrated by the data. A reduction of 62 per cent from the 1996 flaring baseline was achieved. A reduction of 29 per cent was achieved for the venting of solution gas from the 2000 venting baseline. There was a 44 per cent reduction in the volume of solution gas flared and vented from the 1996 volume. tabs., figs.

  1. Sill intrusion driven fluid flow and vent formation in volcanic basins: Modeling rates of volatile release and paleoclimate effects

    Science.gov (United States)

    Iyer, Karthik; Schmid, Daniel

    2016-04-01

    Evidence of mass extinction events in conjunction with climate change occur throughout the geological record and may be accompanied by pronounced negative carbon isotope excursions. The processes that trigger such globally destructive changes are still under considerable debate. These include mechanisms such as poisoning from trace metals released during large volcanic eruptions (Vogt, 1972), CO2 released from lava degassing during the formation of Large Igneous Provinces (LIPs) (Courtillot and Renne, 2003) and CH4 release during the destabilization of sub-seafloor methane (Dickens et al., 1995), to name a few. Thermogenic methane derived from contact metamorphism associated with magma emplacement and cooling in sedimentary basins has been recently gaining considerable attention as a potential mechanism that may have triggered global climate events in the past (e.g. Svensen and Jamtveit, 2010). The discovery of hydrothermal vent complexes that are spatially associated with such basins also supports the discharge of greenhouse gases into the atmosphere (e.g. Jamtveit et al., 2004; Planke et al., 2005; Svensen et al., 2006). A previous study that investigated this process using a fluid flow model (Iyer et al., 2013) suggested that although hydrothermal plume formation resulting from sill emplacement may indeed release large quantities of methane at the surface, the rate at which this methane is released into the atmosphere is too slow to trigger, by itself, some of the negative δ13C excursions observed in the fossil record over short time scales observed in the fossil record. Here, we reinvestigate the rates of gas release during sill emplacement in a case study from the Harstad Basin off-shore Norway with a special emphasis on vent formation. The presented study is based on a seismic line that crosses multiple sill structures emplaced around 55 Ma within the Lower Cretaceous sediments. A single well-defined vent complex is interpreted above the termination of the

  2. The Origin of Life in Alkaline Hydrothermal Vents.

    Science.gov (United States)

    Sojo, Victor; Herschy, Barry; Whicher, Alexandra; Camprubí, Eloi; Lane, Nick

    2016-02-01

    Over the last 70 years, prebiotic chemists have been very successful in synthesizing the molecules of life, from amino acids to nucleotides. Yet there is strikingly little resemblance between much of this chemistry and the metabolic pathways of cells, in terms of substrates, catalysts, and synthetic pathways. In contrast, alkaline hydrothermal vents offer conditions similar to those harnessed by modern autotrophs, but there has been limited experimental evidence that such conditions could drive prebiotic chemistry. In the Hadean, in the absence of oxygen, alkaline vents are proposed to have acted as electrochemical flow reactors, in which alkaline fluids saturated in H2 mixed with relatively acidic ocean waters rich in CO2, through a labyrinth of interconnected micropores with thin inorganic walls containing catalytic Fe(Ni)S minerals. The difference in pH across these thin barriers produced natural proton gradients with equivalent magnitude and polarity to the proton-motive force required for carbon fixation in extant bacteria and archaea. How such gradients could have powered carbon reduction or energy flux before the advent of organic protocells with genes and proteins is unknown. Work over the last decade suggests several possible hypotheses that are currently being tested in laboratory experiments, field observations, and phylogenetic reconstructions of ancestral metabolism. We analyze the perplexing differences in carbon and energy metabolism in methanogenic archaea and acetogenic bacteria to propose a possible ancestral mechanism of CO2 reduction in alkaline hydrothermal vents. Based on this mechanism, we show that the evolution of active ion pumping could have driven the deep divergence of bacteria and archaea.

  3. Electrical Discharge Machining.

    Science.gov (United States)

    Montgomery, C. M.

    The manual is for use by students learning electrical discharge machining (EDM). It consists of eight units divided into several lessons, each designed to meet one of the stated objectives for the unit. The units deal with: introduction to and advantages of EDM, the EDM process, basic components of EDM, reaction between forming tool and workpiece,…

  4. Novel Molecular Discharges

    NARCIS (Netherlands)

    Hilbig, R.; Koerber, A.; Schwan, S.; Hayashi, D.

    2011-01-01

    A systematic investigation into halides and ~oxides showed the high potential of transition metal oxides as visible radiators for highly efficient gas discharge light sources. Zirconium monoxide (ZrO) has been identified as most promising candidate combining highly attractive green and red emission

  5. Graywater Discharges from Vessels

    Science.gov (United States)

    2011-11-01

    addition, based on personal contact with the shipping company, storing graywater in ballast tanks while in port can limit vessel stability considering...enters the treatment system and mixes with the aerated liquid already in the aeration chamber. EPDM Air diffuser injects air near the bottom of the

  6. Application of dielectric surface barrier discharge for food storage

    Directory of Open Access Journals (Sweden)

    Yassine BELLEBNA

    2015-12-01

    Full Text Available Ozone (O3 is a powerful oxidizer and has much higher disinfection potential than chlorine and other disinfectants. Ozone finds its application mainly in water treatment and air purification Dielectric barrier discharge (DBD method has proved to be the best method to produce ozone. Dried air or oxygen is forced to pass through a 1-2 mm gap. The aim of this study was to show that disinfection system using ozone generated by dielectric barrier discharge (DBD is an effective alternative to be used in food industry and ensures a safe quality of air for optimum preservation of fruits and vegetables. The DBDs are specific kind of discharges because one (or sometimes both electrodes is covered by a dielectric material, thereby preventing the discharge to move towards electrical breakdown. A succession of microdischarges occurs rapidly; their "lifetime" is in the range of a few nanoseconds. One of their most important applications is the production of ozone for air treatment, used mainly in the area of food industry, for extending the storage life of foods. After the achievement of a surface DBD reactor of cylindrical shape and its electrical characterization, it was then used as an ozone generator for air disinfection. Obtained results have shown that this reactor used as an ozone generator is effective for disinfection of air by removing viruses, bacteria and pathogens, causing the slowdown of the ripening process of fruits and vegetables.

  7. Particle tracking velocimetry of a gliding arc discharge

    DEFF Research Database (Denmark)

    Zhu, Jiajian; Gao, Jinlong; Ehn, Andreas;

    2014-01-01

    A 35 kHz AC gliding arc discharge at atmospheric pressure is generated between two diverging electrodes and extended by an air flow. The gas flow velocity is measured by particle tracking velocimetry (PTV) while the moving velocity of the plasma column of the gliding arc discharge is measured...... by analyzing the movie taken by a high-speed camera. The two-dimensional velocity vector of the gas flow and of the gliding arc in the imaging plane was determined....

  8. A preliminary survey of the broadband seismic wavefield at Puu Oo, the active vent of Kilauea volcano, Hawaii

    Directory of Open Access Journals (Sweden)

    P. Okubo

    1996-06-01

    Full Text Available The seismic wavefield near an active volcanic vent consists of superimposed signals in a wide range of frequency bands from sources inside and outside the volcano. To characterize the broadband wavefield near Puu Oo, we deployed a profile of three three-component broadband sensors in a 200 m long line about 1.5 km WSW of the active vent. During this period, Puu Oo maintained a constant, but very low level of activity. The digital data logger recorded the wavefield continuously in the frequency band between 0.01 and 40 Hz between June 25 and July 9, 1994. At the same time, local wind conditions along with air temperature and pressure were monitored by a portable digital weather station. On the basis of characteristic elements, such as waveform, spatial coherence between stations, particle motion and power spectra, the wavefield can be divided into three bands. The dominant signals in the frequency band between 0.01 and 0.1 Hz are not coherent among the stations. Their ground velocities correlate with the wind speed. The signals in the 0.1 to 0.5 Hz band are coherent across the profile and most probably represent a superposition of volcanic tremor and microseisms from the Pacific Ocean. Much of the energy above 0.5 Hz can be attributed to activity at the vent. Power spectra from recordings of the transverse components show complex peaks between 0.5 and 3 Hz which vary in amplitude due to site effects and distance. On the other hand, power spectra calculated from the radial components show a clearly periodic pattern of peaks at 1 Hz intervals for some time segments. A further remarkable feature of the power spectra is that they are highly stationary.

  9. High Pressure Micro-Slot Hollow Cathode Discharge

    Institute of Scientific and Technical Information of China (English)

    Wang Xinbing; Zhou Lina; Yao Xilin

    2005-01-01

    A direct current glow discharge source structure operating at high pressure based on the micro-slot hollow cathode is presented in this article. A 100 μm width slot cathode was fabricated of copper, and a stable DC glow discharge with an area of 0.5 mm2 was produced in noble gases (He, Ne) and air over a wide pressure range (kPa ~ 10 kPa). The current-voltage characteristics and the near UV radiation emission of the discharge were studied.

  10. Research on Power Frequency Discharge Characteristics and Mechanism of the Protection Gap of the Combined Fluid of Air And Water Used on Transformer Neutral Points%变压器中性点气水两相组合流体保护间隙的工频放电特性与机制研究

    Institute of Scientific and Technical Information of China (English)

    李博江; 文习山; 严玉婷; 李博洋; 王贺; 于建立

    2014-01-01

    为克服变压器中性点传统空气保护间隙存在的缺陷,提出了“气水间隙”概念,并在武汉大学电气工程学院高电压与绝缘技术试验室进行了气水间隙工频放电特性试验。试验结果表明:当水流从低压电极喷射到高压电极时,间隙很难击穿;当间隙总长度固定,工频放电电压随喷射水流长度减小呈先减小后增大的变化趋势;当喷射水流长度略小于间隙总长度时,工频放电电压与间隙总长度呈线性递增关系;同等长度的气水间隙比空气间隙和全水间隙易击穿,等等。基于气泡击穿理论和空气与水不同的电特性,对试验观察到的放电现象、规律和机制进行分析,指出水流的击穿起因是其中的“气泡桥”的存在和发展,以及水中电离子作用的结果;在气水间隙中,空气段率先击穿形成的电弧高温加热水流促使水中气泡的产生和发展,最终导致水流段的击穿;气水间隙放电特性曲线具有先减小后增大的变化趋势特征是空气和水流不同的电特性相互作用的结果;将气水间隙应用于变压器中性点保护,具有较可观的研究价值和应用前景。%To overcome the disadvantages of traditional protection air gaps of transformer neutral points, the concept of the gap of water and air was presented. The power frequency discharge test between the gap of air and water was conducted in high voltage test room of School of Electrical Engineering in Wuhan University. Test results show that breakdown of the gap is very hard to occur when flow is jetted to the high voltage electrode from low voltage electrode; power frequency discharge voltage will decrease first and increase then with flow length decreasing when the total length of the gap is constant; there is a linear increasing relation between power frequency discharge voltage and total length of the gap when the flow length is somewhat less than the

  11. Electron heating in atmospheric pressure glow discharges

    Science.gov (United States)

    Stark, Robert H.; Schoenbach, Karl H.

    2001-04-01

    The application of nanosecond voltage pulses to weakly ionized atmospheric pressure plasmas allows heating the electrons without considerably increasing the gas temperature, provided that the duration of the pulses is less than the critical time for the development of glow-to-arc transitions. The shift in the electron energy distribution towards higher energies causes a temporary increase in the ionization rate, and consequently a strong rise in electron density. This increase in electron density is reflected in an increased decay time of the plasma after the pulse application. Experiments in atmospheric pressure air glow discharges with gas temperatures of approximately 2000 K have been performed to explore the electron heating effect. Measurements of the temporal development of the voltage across the discharge and the optical emission in the visible after applying a 10 ns high voltage pulse to a weakly ionized steady state plasma demonstrated increasing plasma decay times from tens of nanoseconds to microseconds when the pulsed electric field was raised from 10 to 40 kV/cm. Temporally resolved photographs of the discharge have shown that the plasma column expands during this process. The nonlinear electron heating effect can be used to reduce the power consumption in a repetitively operated air plasma considerably compared to a dc plasma operation. Besides allowing power reduction, pulsed electron heating also has the potential to enhance plasma processes, which require elevated electron energies, such as excimer generation for ultraviolet lamps.

  12. Building America Case Study: Evaluation of Passive Vents in New-Construction Multifamily Buildings, New York, New York

    Energy Technology Data Exchange (ETDEWEB)

    2015-10-15

    Exhaust ventilation and corresponding outdoor air strategies are being implemented in high-performance new construction multifamily buildings to meet program or code requirements for improved indoor air quality, but a lack of clear design guidance is resulting in poor performance of these systems despite the best intentions of the programs or standards. CARB's 2014 'Evaluation of Ventilation Strategies in New Construction Multifamily Buildings' consistently demonstrated that commonly used outdoor air strategies are not performing as expected. Of the four strategies evaluated in 2014, the exhaust ventilation system that relied on outdoor air from a pressurized corridor was ruled out as a potential best practice due to its conflict with meeting requirements within most fire codes. Outdoor air that is ducted directly to the apartments was a strategy determined to have the highest likelihood of success, but with higher first costs and operating costs. Outdoor air through space conditioning systems was also determined to have good performance potential, with proper design and execution. The fourth strategy, passive systems, was identified as the least expensive option for providing outdoor air directly to apartments, with respect to both first costs and operating costs. However, little is known about how they actually perform in real-world conditions or how to implement them effectively. Based on the lack of data available on the performance of these low-cost systems and their frequent use in the high-performance building programs that require a provision for outdoor air, this research project sought to further evaluate the performance of passive vents.

  13. Discharge pulse phenomenology

    Science.gov (United States)

    Frederickson, A. R.

    1985-01-01

    A model was developed which places radiation induced discharge pulse results into a unified conceptual framework. Only two phenomena are required to interpret all space and laboratory results: (1) radiation produces large electrostatic fields inside insulators via the trapping of a net space charge density; and (2) the electrostatic fields initiate discharge streamer plasmas similar to those investigated in high voltage electrical insulation materials; these streamer plasmas generate the pulsing phenomena. The apparent variability and diversity of results seen is an inherent feature of the plasma streamer mechanism acting in the electric fields which is created by irradiation of the dielectrics. The implications of the model are extensive and lead to constraints over what can be done about spacecraft pulsing.

  14. Computing Air Demand Using the Takagi–Sugeno Model for Dam Outlets

    Directory of Open Access Journals (Sweden)

    Mohammad Zounemat-Kermani

    2013-09-01

    Full Text Available An adaptive neuro-fuzzy inference system (ANFIS was developed using the subtractive clustering technique to study the air demand in low-level outlet works. The ANFIS model was employed to calculate vent air discharge in different gate openings for an embankment dam. A hybrid learning algorithm obtained from combining back-propagation and least square estimate was adopted to identify linear and non-linear parameters in the ANFIS model. Empirical relationships based on the experimental information obtained from physical models were applied to 108 experimental data points to obtain more reliable evaluations. The feed-forward Levenberg-Marquardt neural network (LMNN and multiple linear regression (MLR models were also built using the same data to compare model performances with each other. The results indicated that the fuzzy rule-based model performed better than the LMNN and MLR models, in terms of the simulation performance criteria established, as the root mean square error, the Nash–Sutcliffe efficiency, the correlation coefficient and the Bias.

  15. Electrostatic Discharge Training Manual

    Science.gov (United States)

    1980-09-01

    NAVSEA SE 003-AA-TRN-OO LEYE V ELECTROSTATIC DISCHARGE TRAINING MANUAL s DTIC ,T OF I!ELECTE, ,4MA 0W\\R 9 981 E PUBLISHED BY DIRECTION OF COMMANDER...AS: F (QIQ2 . . . ................................................. (1) WHERE: F = FORCE ( NEWTONS ) Q, AND Q2 = MAGNITUDES OF THE CHARGES (COULOMB) R...RATIONALIZED MKS UNITS IN EQUATION (1), WE HAVE: & I 9(5 X 1 - )(lO ř I ’ 32 I I I I. & I = .5 NEWTON

  16. Observations of nearshore groundwater discharge: Kahekili Beach Park submarine springs, Maui, Hawaii

    Science.gov (United States)

    Swarzenski, Peter W.; Dulai, H.; Kroeger, K.D.; Smith, C.G.; Dimova, N.; Storlazzi, C. D.; Prouty, N.G.; Gingerich, S.B.; Glenn, C. R.

    2016-01-01

    Study regionThe study region encompasses the nearshore, coastal waters off west Maui, Hawaii. Here abundant groundwater—that carries with it a strong land-based fingerprint—discharges into the coastal waters and over a coral reef.Study focusCoastal groundwater discharge is a ubiquitous hydrologic feature that has been shown to impact nearshore ecosystems and material budgets. A unique combined geochemical tracer and oceanographic time-series study addressed rates and oceanic forcings of submarine groundwater discharge at a submarine spring site off west Maui, Hawaii.New hydrological insights for the regionEstimates of submarine groundwater discharge were derived for a primary vent site and surrounding coastal waters off west Maui, Hawaii using an excess 222Rn (t1/2 = 3.8 d) mass balance model. Such estimates were complemented with a novel thoron (220Rn,t1/2 = 56 s) groundwater discharge tracer application, as well as oceanographic time series and thermal infrared imagery analyses. In combination, this suite of techniques provides new insight into the connectivity of the coastal aquifer with the near-shore ocean and examines the physical drivers of submarine groundwater discharge. Lastly, submarine groundwater discharge derived constituent concentrations were tabulated and compared to surrounding seawater concentrations. Such work has implications for the management of coastal aquifers and downstream nearshore ecosystems that respond to sustained constituent loadings via this submarine route.

  17. Electrochemical Discharge Machining Process

    Directory of Open Access Journals (Sweden)

    Anjali V. Kulkarni

    2007-09-01

    Full Text Available Electrochemical discharge machining process is evolving as a promising micromachiningprocess. The experimental investigations in the present work substantiate this trend. In the presentwork, in situ, synchronised, transient temperature and current measurements have been carriedout. The need for the transient measurements arose due to the time-varying nature of the dischargeformation and time varying circuit current. Synchronised and transient measurements revealedthe discrete nature of the process. It also helped in formulating the basic mechanism for thedischarge formation and the material removal in the process. Temperature profile on workpieceand in electrochemical discharge machining cell is experimentally measured using pyrometer,and two varieties of K-type thermocouples. Surface topography of the discharge-affected zoneson the workpiece has been carried out using scanning electron microscope. Measurements andsurface topographical studies reveal the potential use of this process for machining in micronregime. With careful experimental set-up design, suitable supply voltage and its polarity, theprocess can be applied for both micromachining and micro-deposition. It can be extended formachining and or deposition of wide range of materials.

  18. Modeling electronegative plasma discharge

    Energy Technology Data Exchange (ETDEWEB)

    Lichtenberg, A.J.; Lieberman, M.A. [Univ. of California, Berkley, CA (United States)

    1995-12-31

    Macroscopic analytic models for a three-component electronegative gas discharge are developed. Assuming the negative ions to be in Boltzmann equilibrium, a positive ion ambipolar diffusion equation is derived. The discharge consists of an electronegative core and electropositive edges. The electron density in the core is nearly uniform, allowing a parabolic approximation to the plasma profile to be employed. The resulting equilibrium equations are solved analytically and matched to a constant mobility transport model of an electropositive edge plasma. The solutions are compared to a simulation of a parallel-plane r.f. driven oxygen plasma for p = 50 mTorr and n{sub eo}= 2.4 x 10{sup 15} m{sup -3}. The ratio {alpha}{sub o} of central negative ion density to electron density, and the electron temperature T{sub e}, found in the simulation, are in reasonable agreement with the values calculated from the model. The model is extended to: (1) low pressures, where a variable mobility model is used in the electropositive edge region; and (2) high {alpha}{sub o} in which the edge region disappears. The inclusion of a second positive ion species, which can be very important in describing electronegative discharges used for materials processing, is a possible extension of the model.

  19. Formation of gas discharging from Taketomi submarine hot spring off Ishigaki Island in the southern Ryukyu Islands, Japan

    Science.gov (United States)

    Toki, Tomohiro; Iwata, Daigo; Tsunogai, Urumu; Komatsu, Daisuke D.; Sano, Yuji; Takahata, Naoto; Hamasaki, Hiroshi; Ishibashi, Jun-ichiro

    2017-01-01

    Taketomi submarine hot spring lies off Ishigaki Island in the southern Ryukyu Islands and vents hot spring waters at temperatures up to 50 °C from the seafloor at a depth of 20 m. We investigated the chemical and isotopic composition of gases discharging from Taketomi hot spring. The gases were composed mainly of methane, with secondary nitrogen at higher than atmospheric concentration. Carbon and hydrogen isotope data suggest that the methane in the discharging gases was derived mainly from thermal decomposition of organic matter. Helium isotopes were enriched in 3He relative to the atmosphere, suggesting a supply of mantle-derived helium to the discharging gases. The mantle-derived gases transfer the deep-originated thermal energy to the hot spring and thermogenesis of organic matter. The hydrocarbons in the venting gas could be sourced from sedimentary rocks of the Yaeyama or Shimajiri Groups, or Yaeyama metamorphic rocks, and added to the ascending gases as they pass through those source rocks on their way to the surface. Because the Pleistocene rocks of the Ryukyu Group beneath the hot spring have been altered by the spring activity, the Taketomi hot spring began venting after the Pleistocene.

  20. Spleen removal - open - adults - discharge

    Science.gov (United States)

    Splenectomy - adult - discharge; Spleen removal - adult - discharge ... You had surgery to remove your spleen. This operation is called splenectomy . The surgeon made a cut (incision) in the middle of your belly or on the left side ...

  1. Theory of gas discharge plasma

    CERN Document Server

    Smirnov, Boris M

    2015-01-01

    This book presents the theory of gas discharge plasmas in a didactical way. It explains the processes in gas discharge plasmas. A gas discharge plasma is an ionized gas which is supported by an external electric field. Therefore its parameters are determined by processes in it. The properties of a gas discharge plasma depend on its gas component, types of external fields, their geometry and regimes of gas discharge. Fundamentals of a gas discharge plasma include elementary, radiative and transport processes which are included in its kinetics influence. They are represented in this book together with the analysis of simple gas discharges. These general principles are applied to stationary gas discharge plasmas of helium and argon. The analysis of such plasmas under certain conditions is theoretically determined by numerical plasma parameters for given regimes and conditions.

  2. Living with the Heat. Submarine Ring of Fire--Grades 5-6. Hydrothermal Vent Ecology.

    Science.gov (United States)

    National Oceanic and Atmospheric Administration (DOC), Rockville, MD.

    This activity is designed to teach about hydrothermal vent ecology. Students are expected to describe how hydrothermal vents are formed and characterize the physical conditions at these sites, explain chemosynthesis and contrast this process with photosynthesis, identify autotrophic bacteria as the basis for food webs in hydrothermal vent…

  3. 49 CFR 179.300-13 - Venting, loading and unloading valves.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Venting, loading and unloading valves. 179.300-13... Venting, loading and unloading valves. (a) Valves shall be of approved type, made of metal not subject to rapid deterioration by lading, and shall withstand tank test pressure without leakage. The valves...

  4. Technology Solutions Case Study: Evaluation of Passive Vents in New-Construction Multifamily Buildings

    Energy Technology Data Exchange (ETDEWEB)

    S. Puttagunta, S. Maxwell, D. Berger, and M. Zuluaga

    2015-10-01

    The Consortium for Advanced Residential Buildings (CARB) conducted research to gain more insight into passive vents. Because passive vents are meant to operate in a general environment of negative apartment pressure, the research assessed whether these negative pressures prevail through a variety of environmental conditions.

  5. 40 CFR 63.114 - Process vent provisions-monitoring requirements.

    Science.gov (United States)

    2010-07-01

    ... Manufacturing Industry for Process Vents, Storage Vessels, Transfer Operations, and Wastewater § 63.114 Process... accurately. Monitoring is not required for process vents with TRE index values greater than 4.0 as specified...) Maintains a TRE greater than 1.0 but less than or equal to 4.0 without a recovery device or with a...

  6. Survey of genome size in 28 hydrothermal vent species covering 10 families.

    Science.gov (United States)

    Bonnivard, Eric; Catrice, Olivier; Ravaux, Juliette; Brown, Spencer C; Higuet, Dominique

    2009-06-01

    Knowledge of genome size is a useful and necessary prerequisite for the development of many genomic resources. To better understand the origins and effects of DNA gains and losses among species, it is important to collect data from a broad taxonomic base, but also from particular ecosystems. Oceanic thermal vents are an interesting model to investigate genome size in very unstable environments. Here we provide data estimated by flow cytometry for 28 vent-living species among the most representative from different hydrothermal vents. We also report the genome size of closely related coastal decapods. Haploid C-values were compared with those previously reported for species from corresponding orders or infraorders. This is the first broad survey of 2C values in vent organisms. Contrary to expectations, it shows that certain hydrothermal vent species have particularly large genomes. The vent squat lobster Munidopsis recta has the largest genome yet reported for any anomuran: 2C=31.1 pg=30.4x10(9) bp. In several groups, such as Brachyura, Phyllodocida, and Veneroida, vent species have genomes that clearly rank at the high end of published values for each group. We also describe the highest DNA content yet recorded for the Brachyura (coastal crabs Xantho pilipes and Necora puber). Finally, analysis of genome size variation across populations revealed unexpected intraspecific variation in the vent shrimp Mirocaris fortunata that could not be attributed simply to ploidy changes.

  7. Spatial and Alignment Analyses for a field of Small Volcanic Vents South of Pavonis Mons Mars

    Science.gov (United States)

    Bleacher, J. E.; Glaze, L. S.; Greeley, R.; Hauber, E.; Baloga, S. M.; Sakimoto, S. E. H.; Williams, D. A.; Glotch, T. D.

    2008-01-01

    The Tharsis province of Mars displays a variety of small volcanic vent (10s krn in diameter) morphologies. These features were identified in Mariner and Viking images [1-4], and Mars Orbiter Laser Altimeter (MOLA) data show them to be more abundant than originally observed [5,6]. Recent studies are classifying their diverse morphologies [7-9]. Building on this work, we are mapping the location of small volcanic vents (small-vents) in the Tharsis province using MOLA, Thermal Emission Imaging System, and High Resolution Stereo Camera data [10]. Here we report on a preliminary study of the spatial and alignment relationships between small-vents south of Pavonis Mons, as determined by nearest neighbor and two-point azimuth statistical analyses. Terrestrial monogenetic volcanic fields display four fundamental characteristics: 1) recurrence rates of eruptions,2 ) vent abundance, 3) vent distribution, and 4) tectonic relationships [11]. While understanding recurrence rates typically requires field measurements, insight into vent abundance, distribution, and tectonic relationships can be established by mapping of remotely sensed data, and subsequent application of spatial statistical studies [11,12], the goal of which is to link the distribution of vents to causal processes.

  8. Effectiveness of horizontal air flow fans supporting natural ventilation in a Mediterranean multi-span greenhouse

    Directory of Open Access Journals (Sweden)

    Alejandro López

    2013-08-01

    Full Text Available Natural ventilation is the most important method of climate control in Mediterranean greenhouses. In this study, the microclimate and air flow inside a Mediterranean greenhouse were evaluated by means of sonic anemometry. Experiments were carried out in conditions of moderate wind (≈ 4.0 m s-1, and at low wind speed (≈ 1.8 m s-1 the natural ventilation of the greenhouse was supplemented by two horizontal air flow fans. The greenhouse is equipped with a single roof vent opening to the windward side and two side vents, the windward one being blocked by another greenhouse close to it, while the leeward one is free of obstacles. When no fans are used, air enters through the roof vent and exits through both side vents, thus flowing contrary to the thermal effect which causes hot air to rise and impairing the natural ventilation of the greenhouse. Using fans inside the greenhouse helps the air to circulate and mix, giving rise to a more homogeneous inside temperature and increasing the average value of normalized air velocity by 365 %. These fans also increase the average values of kinetic turbulence energy inside the greenhouse by 550 % compared to conditions of natural ventilation. As the fans are placed 4 m away from the side vents, their effect on the entrance of outside air is insufficient and they do not help to reduce the inside temperature on hot days with little wind. It is therefore recommended to place the fans closer to the side vents to allow an additional increase of the air exchange rate of greenhouses.

  9. Endemic hydrothermal vent species identified in the open ocean seed bank.

    Science.gov (United States)

    Gonnella, Giorgio; Böhnke, Stefanie; Indenbirken, Daniela; Garbe-Schönberg, Dieter; Seifert, Richard; Mertens, Christian; Kurtz, Stefan; Perner, Mirjam

    2016-06-13

    Hydrothermal vent systems host microbial communities among which several microorganisms have been considered endemic to this type of habitat. It is still unclear how these organisms colonize geographically distant hydrothermal environments. Based on 16S rRNA gene sequences, we compare the bacterial communities of sixteen Atlantic hydrothermal vent samples with our own and publicly available global open ocean samples. Analysing sequences obtained from 63 million 16S rRNA genes, the genera we could identify in the open ocean waters contained 99.9% of the vent reads. This suggests that previously observed vent exclusiveness is, in most cases, probably an artefact of lower sequencing depth. These findings are a further step towards elucidating the role of the open ocean as a seed bank. They can explain the predicament of how species expected to be endemic to vent systems are able to colonize geographically distant hydrothermal habitats and contribute to our understanding of whether 'everything is really everywhere'.

  10. Plasma Discharge Process in a Pulsed Diaphragm Discharge System

    Science.gov (United States)

    Duan, Jianjin; Hu, Jue; Zhang, Chao; Wen, Yuanbin; Meng, Yuedong; Zhang, Chengxu

    2014-12-01

    As one of the most important steps in wastewater treatment, limited study on plasma discharge process is a key challenge in the development of plasma applications. In this study, we focus on the plasma discharge process of a pulsed diaphragm discharge system. According to the analysis, the pulsed diaphragm discharge proceeds in seven stages: (1) Joule heating and heat exchange stage; (2) nucleated site formation; (3) plasma generation (initiation of the breakdown stage); (4) avalanche growth and plasma expansion; (5) plasma contraction; (6) termination of the plasma discharge; and (7) heat exchange stage. From this analysis, a critical voltage criterion for breakdown is obtained. We anticipate this finding will provide guidance for a better application of plasma discharges, especially diaphragm plasma discharges.

  11. Colonization by Cladosporium spp. of painted metal surfaces associated with heating and air conditioning systems

    Science.gov (United States)

    Ahearn, D. G.; Simmons, R. B.; Switzer, K. F.; Ajello, L.; Pierson, D. L.

    1991-01-01

    Cladosporium cladosporioides and C. hebarum colonized painted metal surfaces of covering panels and register vents of heating, air conditioning and ventilation systems. Hyphae penetrated the paint film and developed characteristic conidiophores and conidia. The colonies were tightly appressed to the metal surface and conidia were not readily detectable via standard air sampling procedures.

  12. Study of Mechanisms of Filamentary Pulse Electric Discharge Interaction with Gaseous Flow of Nonuniform Composition

    Science.gov (United States)

    2013-06-01

    current and power characteristics of the discharge in air at atmospheric pressure are presented in Fig.2.1.2. It is seen that current in air has...and flame acceleration by non-equilibrium corona or barrier discharges ; see for example [16-17]. As a rule in those works the conditions are rather...obtained in early experiments [22] for the spark current of 5 kA in the air at atmospheric pressure and discharge duration of 10-15 us: V = V(1 – e-at

  13. 介质阻挡放电协同催化对空气中苯的降解%Synergy of dielectric barrier discharges and catalysts for removal of benzene from air

    Institute of Scientific and Technical Information of China (English)

    王升高; 徐开伟; 卢文平; 孔垂雄

    2013-01-01

    为提高介质阻挡放电技术对空气中苯的去除效率,降低尾气中的残余有害气体的含量,采用等离子体结合二氧化锰或氧化铜/二氧化锰催化剂的方法.采用水热法和浸渍法分别合成了二氧化锰和氧化铜/二氧化锰催化剂,通过气相色谱仪和碘量滴定法测定了尾气中苯、二氧化碳、一氧化碳和臭氧的含量,研究了苯氧化降解过程等离子体与催化剂协同效应.结果表明,当不加催化剂时,随放电功率增加,苯的降解率可达68.2%,臭氧体积分数上升至595×10-6,二氧化碳的选择比为51.9%;采用氧化铜/二氧化锰催化剂对尾气中臭氧和一氧化碳降解最好,尾气中的臭氧降低为108×10-6,同时二氧化碳选择比提高至94.2%.%To improve the dielectric barrier discharge technology on benzene removal efficiency and reduce concentration of residual harmful gases in the tail gas, the method of plasma combined with MnO2 or CuO/MnO2 catalysts was used. MnO2 and CuO/MnO2 catalysts were prepared by hydrothermal method and impregnation, respectively. The concentration of residue benzene, CO2, CO and ozone was analyzed by gas chromatograph and iodine quantity method. The synergistic effect between plasma and catalysts in the benzene oxidation process was studied. Results show that when no catalyst is used, the degradation rate of benzene and the CO2 selectivity reach 68. 2% and 51. 9% respectively, but the concentration of ozone rises to 595×1O-6 as the discharge power increasing. The CuO/MnO2 catalysts show higher catalytic activity for ozone decomposition and CO oxidation, the concentration of ozone reduces to 108×10-6,meanwhile the CO2 selectivity rises to 94. 2%.

  14. Electrical and mechanical characteristics of nanosecond pulsed sliding dielectric barrier discharges with different electrode gaps

    Science.gov (United States)

    Bayoda, K. D.; Benard, N.; Moreau, E.

    2015-10-01

    This study proposes the characterization of a surface sliding discharge that extends over a length of 80 mm. The gas ionization is caused by series of high voltage pulses with nanosecond rising and decaying times while ion drift is forced by a negative DC component. Different plasma diagnostics such as electrical measurements, iCCD visualizations and strioscopy have been performed. They highlight that a threshold mean electric field between both air-exposed electrodes is required to fully establish a sliding discharge. Compared to a single nanosecond pulsed dielectric barrier discharge, the sliding discharge results in an energy consumption increase. Moreover, the pressure wave induced by the discharge is strongly impacted.

  15. Compact Intracloud Discharges

    Energy Technology Data Exchange (ETDEWEB)

    Smith, David A. [Univ. of Colorado, Boulder, CO (United States)

    1998-11-01

    In November of 1993, mysterious signals recorded by a satellite-borne broadband VHF radio science experiment called Blackboard led to a completely unexpected discovery. Prior to launch of the ALEXIS satellite, it was thought that its secondary payload, Blackboard, would most often detect the radio emissions from lightning when its receiver was not overwhelmed by noise from narrowband communication carriers. Instead, the vast majority of events that triggered the instrument were isolated pairs of pulses that were one hundred times more energetic than normal thunderstorm electrical emissions. The events, which came to be known as TIPPs (for transionospheric pulse pairs), presented a true mystery to the geophysics community. At the time, it was not even known whether the events had natural or anthropogenic origins. After two and one half years of research into the unique signals, two ground-based receiver arrays in New Mexico first began to detect and record thunderstorm radio emissions that were consistent with the Blackboard observations. On two occasions, the ground-based systems and Blackboard even recorded emissions that were produced by the same exact events. From the ground based observations, it has been determined that TIPP events areproduced by brief, singular, isolated, intracloud electrical discharges that occur in intense regions of thunderstorms. These discharges have been dubbed CIDS, an acronym for compact intracloud discharges. During the summer of 1996, ground-based receiver arrays were used to record the electric field change signals and broadband HF emissions from hundreds of CIDS. Event timing that was accurate to within a few microseconds made possible the determination of source locations using methods of differential time of arrival. Ionospheric reflections of signals were recorded in addition to groundwave/line-of-sight signals and were used to determine accurate altitudes for the discharges. Twenty-four CIDS were recorded from three

  16. Commissioning of filtered containment venting test loop Java plus

    Energy Technology Data Exchange (ETDEWEB)

    Beiseigel, A.; El-Rharbaoui, F.; Wich, M.

    2013-07-01

    AREVA GmbH operates a unique Thermal-hydraulic platform in Germany, France and USA. It is recognized as a test body according to ISO 17025. The Deutsche Akkreditierungsstelle GmbH (DAkkS - German Society for Accreditation) has also certified the Thermal-hydraulic platform as an independent inspection body Type C according to ISO 17020. A part of this platform is the Component Laboratory located in Karlstein, Germany which is in operation for more than 50 years. The testing activities cover a wide range as: Critical Heat Flux Tests, Valve Testing and LOCA Qualification of safety related components. Since 2012 the component Qualification Karlstein reactivated their testing scope for Filtered Containment Venting System (FCVS) Tests which is to our knowledge the largest (mass flow and volume) dedicated FCVS test facility.

  17. 30 CFR 250.1164 - What are the requirements for flaring or venting gas containing H2S?

    Science.gov (United States)

    2010-07-01

    ... venting gas containing H2S? 250.1164 Section 250.1164 Mineral Resources MINERALS MANAGEMENT SERVICE... requirements for flaring or venting gas containing H2S? (a) You may not vent gas containing H2S, except for... average atmosphere concentration of H2S of 20 ppm or higher anywhere on the platform. (b) You may...

  18. 78 FR 58574 - Maintenance, Testing, and Replacement of Vented Lead-Acid Storage Batteries for Nuclear Power Plants

    Science.gov (United States)

    2013-09-24

    ... COMMISSION Maintenance, Testing, and Replacement of Vented Lead-Acid Storage Batteries for Nuclear Power..., Testing, and Replacement of Vented Lead-Acid Storage Batteries for Nuclear Power Plants.'' The guide... with regard to the maintenance, testing, and replacement of vented lead-acid storage batteries...

  19. Continuous pile discharging machine

    Science.gov (United States)

    Smith, Phillips P.

    1976-05-11

    A device for discharging cartridges from tubes under fluid pressure includes a cylindrical housing adapted to be seated in a leak-tight manner on the end of one of the tubes, a chute depending from the cylindrical housing near the end seated on the end of the tube, a rotatable piston having a wrench on the forward end thereof disposed in the cylindrical housing and adapted to manipulate a plug in the end of the tube, and a telescopic hydraulic ram adapted to move the piston toward the plug. In addition the wrench contains a magnet which prevents inadvertent uncoupling of the wrench and the plug.

  20. Testing Geyser Models using Down-vent Data

    Science.gov (United States)

    Wang, C.; Munoz, C.; Ingebritsen, S.; King, E.

    2013-12-01

    Geysers are often studied as an analogue to magmatic volcanoes because both involve the transfer of mass and energy that leads to eruption. Several conceptual models have been proposed to explain geyser eruption, but no definitive test has been performed largely due to scarcity of down-vent data. In this study we compare simulated time histories of pressure and temperature against published data for the Old Faithful geyser in the Yellowstone National Park and new down-vent measurements from geysers in the El Tatio geyser field of northern Chile. We test two major types of geyser models by comparing simulated and field results. In the chamber model, the geyser system is approximated as a fissure-like conduit connected to a subsurface chamber of water and steam. Heat supplied to the chamber causes water to boil and drives geyser eruptions. Here the Navier-Stokes equation is used to simulate the flow of water and steam. In the fracture-zone model, the geyser system is approximated as a saturated fracture zone of high permeability and compressibility, surrounded by rock matrix of relatively low permeability and compressibility. Heat supply from below causes pore water to boil and drives geyser eruption. Here a two-phase form of Darcy's law is assumed to describe the flow of water and steam (Ingebritsen and Rojstaczer, 1993). Both models can produce P-T time histories qualitatively similar to field results, but the simulations are sensitive to assumed parameters. Results from the chamber model are sensitive to the heat supplied to the system and to the width of the conduit, while results from the fracture-zone model are most sensitive to the permeability of the fracture zone and the adjacent wall rocks. Detailed comparison between field and simulated results, such as the phase lag between changes of pressure and temperature, may help to resolve which model might be more realistic.

  1. Lipid Adaptation of Shrimp Rimicaris exoculata in Hydrothermal Vent.

    Science.gov (United States)

    Zhu, Si; Ye, Mengwei; Yan, Xiaojun; Zhou, Yadong; Wang, Chunsheng; Xu, Jilin

    2015-12-01

    The shrimp Rimicaris exoculata is the most abundant species in hydrothermal vents. Lipids, the component of membranes, play an important role in maintaining their function normally in such extreme environments. In order to understand the lipid adaptation of R. exoculata (HV shrimp) to hydrothermal vents, we compared its lipid profile with the coastal shrimp Litopenaeus vannamei (EZ shrimp) which lives in the euphotic zone, using ultra performance liquid chromatography electrospray ionization-quadrupole time-of-flight mass spectrometry. As a result, the following lipid adaptation can be observed. (1) The proportion of 16:1 and 18:1, and non-methylene interrupted fatty acid (48.9 and 6.2 %) in HV shrimp was higher than that in EZ shrimp (12.7 and 0 %). While highly-unsaturated fatty acids were only present in the EZ shrimp. (2) Ceramide and sphingomyelin in the HV shrimp were enriched in d14:1 long chain base (96.5 and 100 %) and unsaturated fatty acids (67.1 and 57.7 %). While in the EZ shrimp, ceramide and sphingomyelin had the tendency to contain d16:1 long chain base (68.7 and 75 %) and saturated fatty acids (100 and 100 %). (3) Triacylglycerol content (1.998 ± 0.005 nmol/mg) in the HV shrimp was higher than that in the EZ shrimp (0.092 ± 0.005 nmol/mg). (4) Phosphatidylinositol and diacylglycerol containing highly-unsaturated fatty acids were absent from the HV shrimp. (5) Lysophosphatidylcholine and lysophosphatidylethanolamine were rarely detected in the HV shrimp. A possible reason for such differences was the result of food resources and inhabiting environments. Therefore, these lipid classes mentioned above may be the biomarkers to compare the organisms from different environments, which will be benefit for the further exploitation of the hydrothermal environment.

  2. 38 CFR 17.46 - Eligibility for hospital, domiciliary or nursing home care of persons discharged or released from...

    Science.gov (United States)

    2010-07-01

    ..., domiciliary or nursing home care of persons discharged or released from active military, naval, or air service... Hospital, Domiciliary and Nursing Home Care § 17.46 Eligibility for hospital, domiciliary or nursing home care of persons discharged or released from active military, naval, or air service. (a) In...

  3. Decline of a Hydrothermal Vent Field - Escanaba Trough 12 Years Later

    Science.gov (United States)

    Zierenberg, R. A.; Clague, D. A.; Davis, A. S.; Lilley, M. D.; McClain, J. S.; Olson, E. S.; Ross, S. L.; Von Damm, K. L.

    2001-12-01

    Hydrothermal venting was discovered in Escanaba Trough, the southern sediment-covered portion of the Gorda Ridge, in 1988. Large pyrrhotite-rich massive sulfide mounds are abundant at each of the volcanic/intrusive centers that have been investigated in Escanaba Trough, but the only area of known hydrothermal venting is the NESCA site along the ridge axis at 41\\deg N. Hydrothermal fluids venting at 217\\deg C and 108\\deg C were sampled in 1988 on two sulfide mounds separated by about 275 m. The end-member fluid compositions were indistinguishable within analytical errors. Several sulfide mounds were observed in 1988 which had diffusely venting low temperature (holes were drilled in the NESCA area in 1996 on ODP Leg 169, including Hole 1036I that penetrated to basaltic basement at 405 m below sea floor (mbsf). Surveys of the area using the drill string camera located only one area of active venting at the same mound where 217\\deg C vent fluids were sampled from two active vents in 1988. Drill hole 1036A was spudded between the two active vents on this sulfide mound (approximately 4 and 8 m away) and penetrated to 115 mbsf. The NESCA site was revisited in 2000 using MBARI's R/V Western Flyer and ROV Tiburon. The hydrothermal vents appeared essentially identical to observations made from the drill string camera in 1996 despite the presence of a drill hole within meters of the two vents. The maximum vent temperature measured in 2000 was 212\\deg C. Fluid samples have major element and isotopic compositions very similar to those collected in 1988. The vent fluids have higher methane ( ~19 mmol/kg) than those from the geologically similar Middle Valley vent field, but lower values than those at Guaymas Basin. Drill hole 1036A was weakly venting, but the diffuse hydrothermal fluids could not be sampled with the equipment available. The walls of the drill hole were colonized by palm worms, limpets, and snails. Four other drill holes showed no hydrothermal flow nor

  4. Validation of computer simulation of air parameters at a longwall vs results on an in situ experiment

    Energy Technology Data Exchange (ETDEWEB)

    Dziurzynski, W.; Krach, A.; Palka, T.; Wasilewski, S. [Polish Academy of Sciences, Krakow (Poland). Strata Mechanics and Research Inst.

    2010-07-01

    The ventilation conditions in a mine, or part of a mine, can be analyzed and forecasted using simulation software that mathematically models various phenomena associated with mining. This paper discussed the validation of the VentGraph simulation tool which incorporates the VentGoaf module that takes into consideration air parameters near the longwall in a selected region of a mine. VentGraph was used to simulate the flow of air and methane in a network of headings, while the VentGoaf module was used to simulate flow phenomena in the goaf and also in the adjacent headings. A working shift at a longwall mine in Poland was used in the experiment in which air parameters were measured during regular exploitation. The longwall was considered to be one of the most difficult in Poland's mining sector in terms of methane hazard. Air disturbances caused by shearer operation and movement of the powered roof support during mining were measured along several points of the longwall. Air velocity, barometric pressure and methane concentration were also registered. The operation of the shearer was simulated in 2 directions with a standstill period. The study compared the air flows obtained by the simulation and those measured in the mine. The study confirmed the usefulness of the VentGoaf module for forecasting the state of ventilation of the longwall area, provided that the appropriate input data was obtained from monitoring systems. 12 refs., 8 figs.

  5. The Sponge Community of a Subtidal Area with Hydrothermal Vents: Milos Island, Aegean Sea

    Science.gov (United States)

    Pansini, M.; Morri, C.; Bianchi, C. N.

    2000-11-01

    Sponges were sampled by SCUBA diving at six subtidal rocky sites, three of which were close to hydrothermal vents, a common feature on the sea-floor off the south-east coast of Milos. Twenty-five species (2 Calcarea and 23 Demospongiae) were found, few compared with the 589 recorded for the Mediterranean, but an important addition to the scant information on the sponge fauna of the Aegean Sea. The number of species found at vent sites was consistently higher than that found at non-vent sites, but no vent-obligate species could be identified. However, Geodia cydonium and three species of Cliona ( C. copiosa, C. nigricans and C. rhodensis) showed a tendency to colonize vent areas. The former might take advantage of increased silica availability, the latter of the enhanced deposition of carbonates near vents. Substratum cover by sponges (estimated from wire-framed photographs of 0·7 m 2), varied greatly both among and within sites, mostly according to slope. Most sponge species preferred vertical to overhanging, shaded substrata. Proximity to vents seemed to have little or no influence on sponge cover, notwithstanding a primary effect on species diversity.

  6. Quantifying volcanic hazard at Campi Flegrei caldera (Italy) with uncertainty assessment: 1. Vent opening maps

    Science.gov (United States)

    Bevilacqua, Andrea; Isaia, Roberto; Neri, Augusto; Vitale, Stefano; Aspinall, Willy P.; Bisson, Marina; Flandoli, Franco; Baxter, Peter J.; Bertagnini, Antonella; Esposti Ongaro, Tomaso; Iannuzzi, Enrico; Pistolesi, Marco; Rosi, Mauro

    2015-04-01

    Campi Flegrei is an active volcanic area situated in the Campanian Plain (Italy) and dominated by a resurgent caldera. The great majority of past eruptions have been explosive, variable in magnitude, intensity, and in their vent locations. In this hazard assessment study we present a probabilistic analysis using a variety of volcanological data sets to map the background spatial probability of vent opening conditional on the occurrence of an event in the foreseeable future. The analysis focuses on the reconstruction of the location of past eruptive vents in the last 15 ka, including the distribution of faults and surface fractures as being representative of areas of crustal weakness. One of our key objectives was to incorporate some of the main sources of epistemic uncertainty about the volcanic system through a structured expert elicitation, thereby quantifying uncertainties for certain important model parameters and allowing outcomes from different expert weighting models to be evaluated. Results indicate that past vent locations are the most informative factors governing the probabilities of vent opening, followed by the locations of faults and then fractures. Our vent opening probability maps highlight the presence of a sizeable region in the central eastern part of the caldera where the likelihood of new vent opening per kilometer squared is about 6 times higher than the baseline value for the whole caldera. While these probability values have substantial uncertainties associated with them, our findings provide a rational basis for hazard mapping of the next eruption at Campi Flegrei caldera.

  7. Upstream petroleum industry flaring and venting report : industry performance for year ending December 31, 2001

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-07-01

    Solution gas, gas from oil and bitumen batteries, is the largest source of flaring and venting in Alberta. A summary of solution gas conserved, flared and vented in Alberta during the year ending December 31, 2001 was presented along with flared volumes for the various oil and gas industry sectors such as gas plants, gas gathering systems, well tests and oil, bitumen and gas batteries. The report identifies the sources of flaring and venting in Alberta and monitors the progress the industry has made in reducing the volume of solution gas flared since 1996. Operators were ranked provincially, as well as within each field centre of the Alberta Energy and Utilities Board, based on solution gas flared, vented, total solution gas produced, and total oil from crude oil and bitumen batteries. The report demonstrates the significant progress industry has made towards reducing solution flare gas and vent volumes in the province. In 2001, the industry decreased overall flared and vented volumes by 16 per cent compared to year 2000 from all sources. Two new tables in this year's report indicate the top 25 solution gas producers in Alberta and the top 25 companies venting solution gas. The table provides information regarding each company's conservation performance and production volumes as a percentage of the provincial total.

  8. Quantifying dispersal from hydrothermal vent fields in the western Pacific Ocean.

    Science.gov (United States)

    Mitarai, Satoshi; Watanabe, Hiromi; Nakajima, Yuichi; Shchepetkin, Alexander F; McWilliams, James C

    2016-03-15

    Hydrothermal vent fields in the western Pacific Ocean are mostly distributed along spreading centers in submarine basins behind convergent plate boundaries. Larval dispersal resulting from deep-ocean circulations is one of the major factors influencing gene flow, diversity, and distributions of vent animals. By combining a biophysical model and deep-profiling float experiments, we quantify potential larval dispersal of vent species via ocean circulation in the western Pacific Ocean. We demonstrate that vent fields within back-arc basins could be well connected without particular directionality, whereas basin-to-basin dispersal is expected to occur infrequently, once in tens to hundreds of thousands of years, with clear dispersal barriers and directionality associated with ocean currents. The southwest Pacific vent complex, spanning more than 4,000 km, may be connected by the South Equatorial Current for species with a longer-than-average larval development time. Depending on larval dispersal depth, a strong western boundary current, the Kuroshio Current, could bridge vent fields from the Okinawa Trough to the Izu-Bonin Arc, which are 1,200 km apart. Outcomes of this study should help marine ecologists estimate gene flow among vent populations and design optimal marine conservation plans to protect one of the most unusual ecosystems on Earth.

  9. Venting of gas explosion through relief ducts: interaction between internal and external explosions.

    Science.gov (United States)

    Ferrara, G; Willacy, S K; Phylaktou, H N; Andrews, G E; Di Benedetto, A; Salzano, E; Russo, G

    2008-06-30

    Relief ducts fitted to venting openings is a widespread configuration in the industrial practice. The presence of a duct has been reported to severely increase the violence of the vented explosion posing a problem for the proper design of the venting device. Several studies have reported the leading importance--in the whole complex explosion phenomenology--of a secondary explosion in the duct. Modern approaches in the study of simply vented explosions (without ducts) have focused on the study of the interaction between internal and external explosion as a key issue in the mechanisms of pressure generation. The issue is even more relevant when a duct is fitted to the vent due the confined nature of the external explosion. In this work the interaction between internal and external events is experimentally investigated for gas explosions vented through a relief duct. The work has aimed at studying mechanisms underlying the pressure rise of this venting configuration. The study has put the emphasis on the mutual nature of the interaction. A larger scale than laboratory has been investigated allowing drawing results with a greater degree of generality with respect to data so far presented in literature.

  10. Heart bypass surgery - minimally invasive - discharge

    Science.gov (United States)

    ... invasive direct coronary artery bypass - discharge; MIDCAB - discharge; Robot assisted coronary artery bypass - discharge; RACAB - discharge; Keyhole ... M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health ...

  11. ["Piggyback" shot: ballistic parameters of two simultaneously discharged airgun pellets].

    Science.gov (United States)

    Frank, Matthias; Schönekess, Holger C; Grossjohann, Rico; Ekkernkamp, Axel; Bockholdt, Britta

    2014-01-01

    Green and Good reported an uncommon case of homicide committed with an air rifle in 1982 (Am. J. Forensic Med. Pathol. 3: 361-365). The fatal wound was unusual in that two airgun pellets were loaded in so-called "piggyback" fashion into a single shot air rifle. Lack of further information on the ballistic characteristics of two airgun pellets as opposed to one conventionally loaded projectile led to this investigation. The mean kinetic energy (E) of the two pellets discharged in "piggyback" fashion was E = 3.6 J and E = 3.4 J, respectively. In comparison, average kinetic energy values of E = 12.5 J were calculated for conventionally discharged single diabolo pellets. Test shots into ballistic soap confirmed the findings of a single entrance wound as reported by Green and Good. While the ballistic background of pellets discharged in "piggyback" fashion could be clarified, the reason behind this mode of shooting remains unclear.

  12. Effect of Background Ions on the Selection of the Discharge Path

    Institute of Scientific and Technical Information of China (English)

    HE Zheng-Hao; LI Jin

    2001-01-01

    The effects of the background ions on the selection of the discharge path in an air gap have been studied with two different methods. The lightning impulse air discharge experiment is conducted using an independent ion generator, while the air discharge experiment uses a lightning impulse superimposed on a dc high voltage used to produce background ions. The influence of different background ions on the leader development, and thus on the discharge path, is observed. Consistent results have been obtained with the two methods. The probability for the discharge path passing through the negative ion space is much higher than that for the passing through the positive ion space. The mechanism of the effects of background ions is analysed based on the eleetron avalanche and the electric field.

  13. Dielectric barrier Discharge Plasma Actuator Characterization and Application

    NARCIS (Netherlands)

    Correale, G.

    2016-01-01

    An experimental investigation about nanosecond Dielectric Barrier Discharge (ns-DBD) plasma actuator is presented in this thesis. This work aimed to answer fundamental questions on the actuation mechanism of this device. In order to do so, parametric studies in a quiescent air as well as laminar bou

  14. FLOW REGIMES BELOW AERATORS FOR DISCHARGE TUNNELS

    Institute of Scientific and Technical Information of China (English)

    MA Fei; WU Jian-hua

    2012-01-01

    The flow regimes below an aerator influence directly the air entrainment and the cavitation damage control.Based on the theoretical considerations,the experiments of the aerator for a discharge tunnel were conducted,and the relationships between the flow regime and hydraulic and geometric parameters were investigated.The results showed that,there are two kinds of threshold values for the flow regime conversions.One is Fr1-2 standing for the conversion from the fully filled cavity to the partially filled cavity,and the other is Fr2-3 which shows the change from the partially filled cavity to the net air cavity.Two empirical expressions were obtained for the conversions of the flow regimes,which can be used in the designs of the aerators.

  15. Tests of the cryogenic target for lithium and hydrogen isotopes extraction from the chamber of T-11M tokamak without its venting

    Energy Technology Data Exchange (ETDEWEB)

    Mirnov, Sergey V., E-mail: mirnov@triniti.ru [SSC RF TRINITI Troitsk, Moscow 142 190 (Russian Federation); NRNU MEPhI, Kashirskoye sh. 31, Moscow 115409 (Russian Federation); Djigailo, Nadejda T.; Dzhurik, Sergey P.; Kostina, Anastasiya N.; Kravchuk, Sergey I.; Lazarev, Vladimir B. [SSC RF TRINITI Troitsk, Moscow 142 190 (Russian Federation); Lyublinski, Igor E. [JSC “Red Star”, Elektrolitnyj pr. 1A, Moscow 113 230 (Russian Federation); NRNU MEPhI, Kashirskoye sh. 31, Moscow 115409 (Russian Federation); Nesterenko, Vladislav M.; Petrov, Yuri V. [SSC RF TRINITI Troitsk, Moscow 142 190 (Russian Federation); Vertkov, Aleksei V.; Zharkov, Mikhail Yu. [JSC “Red Star”, Elektrolitnyj pr. 1A, Moscow 113 230 (Russian Federation)

    2014-12-15

    Graphical abstract: - Highlights: • We tested the cryogenic target as pump of Li ions sputtered from tokamak chamber by glow discharge. • We found a positive effect on the Li collection an addition of the residual gases to glow discharge. • Cooled target can be used during plasma operation to collect and remove Li and H from tokamak chamber. - Abstract: T-11M lithium program is focused on a solution of technological issues of a steady-state tokamak with liquid lithium plasma facing components (PFC). Lithium, collected by the chamber wall of such tokamak is able to capture a considerable amount of tritium, which is unacceptable. In order to restrict the level of lithium deposited on the chamber wall and captured tritium it was suggested early to use a cryogenic target technique. Such target placed in the plasma of glow discharge (GDH, He or Ar) during the tokamak conditioning can play the role of collector of lithium and tritium atoms which were sputtered by GD bombardment of the wall. The collected lithium and tritium can be evacuated mechanically together with target from tokamak chamber through vacuum lock without venting. Cryogenic target, cooled by liquid nitrogen (LN), was installed in the T-11M and tested in different modes of wall conditioning and tokamak operations. The maximum speed of the lithium collection during GDH was 3.5 mg/h, that corresponds “to contamination” of wall by lithium during approximately 200 regular shots of T-11M which are equivalent to two-week regular operations. It was established that considerable part of lithium was collected in ionized state. On this basis it can be suggested the creation in tokamak chamber an equivalent ionic pump for extraction both lithium and tritium from chamber without venting during regular tokamak operation.

  16. Influence of Plasma Temperature on the Concentration of NO Produced by Pulsed Arc Discharge

    Institute of Scientific and Technical Information of China (English)

    胡辉; 陈卫鹏; 张锦丽; 陆僖; 何俊佳

    2012-01-01

    This study conducted experiments on producing inhaled medical nitric oxide (iNO) by pulsed arc discharge in dry and clean air under different discharge current. The concentration of NO and NO2 produced by air discharge, as well as the change of the ratio of NO2/NO under different discharge current were investigated. Through the analysis of plasma emission spectrum, the relationship between discharge current and arc plasma temperature was studied. The results indicate that, as discharge current increases, the arc plasma temperature increases, which then leads to the increase of NO concentration, the decrease of NO2 concentration, and the rapid decrease of the ratio of NO2/NO. When the plasma temperature is 9000 K, the ratio of NO2/NO is approximately 60%, while when the plasma temperature varies between 10550 K and 11300 K, the NO2/NO ratio is within the range of 4.2% to 4.6%.

  17. An analysis of flaring and venting activity in the Alberta upstream oil and gas industry.

    Science.gov (United States)

    Johnson, Matthew R; Coderre, Adam R

    2011-02-01

    Alberta, Canada, is an important global producer of petroleum resources. In association with this production, large amounts of gas (1.14 billion m3 in 2008) are flared or vented. Although the amount of flaring and venting has been measurably reduced since 2002, data from 2005 reveal sharp increases in venting, which have important implications in terms of resource conservation and greenhouse gas emissions (which exceeded 8 million tonnes of carbon dioxide equivalent in 2008). With use of extensive monthly production data for 18,203 active batteries spanning the years 2002-2008 obtained in close cooperation with the Alberta Energy Resources Conservation Board, a detailed analysis has been completed to examine activity patterns of flaring and venting and reasons behind these trends in the Alberta upstream oil and gas industry. In any given year, approximately 6000 batteries reported flaring and/or venting, but the distribution of volumes flared and vented at individual sites was highly skewed, such that small numbers of sites handled large fractions of the total gas flaring and venting in the Province. Examination of month-to-month volume variability at individual sites, cast in terms of a nominal turndown ratio that would be required for a compressor to capture that gas and direct it into a pipeline, further revealed that volumes at a majority of sites were reasonably stable and there was no evidence that larger or more stable sites had been preferentially reduced, leaving potential barriers to future mitigation. Through linking of geospatial data with production data coupled with additional statistical analysis, the 31.2% increase in venting volumes since 2005 was revealed to be predominantly associated with increased production of heavier oils and bitumen in the Lloydminster region of the Province. Overall, the data suggest that quite significant reductions in flaring and venting could be realized by seeking mitigation solutions for only the largest batteries in

  18. Hydrodynamic calculation of a filter washing in liquids type used in containment venting systems; Calculo hidrodinamico de un filtro tipo lavado en liquidos usados en los sistemas de venteo de la contencion

    Energy Technology Data Exchange (ETDEWEB)

    Reyes G, A. A.; Sainz M, E.; Ortiz V, J., E-mail: alejandroantonioreyess@gmail.com [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2015-09-15

    From the nuclear accident of Chernobyl, the European nuclear power plants have chosen to install filters on the venting pipes of the containment, whose function is to help to mitigate the consequences of a severe accident, by controlled depressurization of the containment passively through a filtered venting of the containment system. These systems are designed to relieve the internal pressure of the containment by means of the deliberate opening of pressure relief devices, either a valve or rupture disc during a severe accident and be channeled to the filter unit. In this paper the hydraulic response of a filter system of gases washing by liquid is evaluated, due to this information is necessary to estimate the effect that has the pressure increase of the contention on the discharge capacity of the venting pipes. By simulation of computational of fluid dynamics with the programs: CAELINUX-2014 and OpenFOAM, the hydrodynamic characteristics of the Multi Venturi System for gases washing from the containment, which could be included in the general model of the venting pipe, were obtained. Representative models of the Venturi tubes of each concentric area that forming the washing system were generated; and using parametric calculations the average mass flow rate established through each venturi, depending on its size and depth in which it is located inside the tank was estimated. Also, the pressure and mass flow rate required to activate each concentric area depending on the pressure and mass load from the containment were calculated, to estimate the maximum flow that is established through the filter. Finally, the velocity profiles and the characteristic pressure at which each area operates as well as the pressure drop of local and global discharge also were calculated. (Author)

  19. Morphology of cone-fields in SW Elysium Planitia - Traces of hydrothermal venting on Mars?

    Science.gov (United States)

    Lanz, J. K.; Saric, M. B.

    2008-09-01

    lower atmospheric pressure causes stronger decompression and expansion of gases. With increasing distance and increasing APF-thickness the surface manifestation of the processes weakens and phreatic explosive activity decreases. The cracked domes and elongated ridges may then be the surface expression of sediment pipes and dikes that have cooled and degassed before reaching the surface. The flow structures surrounding many cones and ridges could be interpreted in this context as fluidized sediment as lava would not have been discharged from the vents. This kind of sediment volcanism took place after the erosion of the APF and marks the end of the hydrothermal activity. Phase 4: Erosion of the APF, enhanced by the cone-forming processes themselves, later exhumed deeper parts of the vents and the brecciated sediment cores, leaving remnants of APF sediments in central pits and on top of cones, ridges and domes. References: [1] Plescia J. B. (1980) NASA Tech. Memo., 82385, 263-265. [2] Bridges J. C. et al. (2003) JGR, 180(E1), 5001, doi:10.1029/2001JE001820. [3] Fagents S. A. (2002) LPSC XXXIII, Abstract #1594. [4] Bruno B. C. (2004) JGR, 109, doi:1029/2004JE002273. [5] Theilig E. and Greeley R. (1979) J. Geophys. Res., 84, 7994-8010. [6] Page and Murray (2006) Icarus, 183, 46-54. [7] Skinner J. A. and Tanaka K. L. (2006) Icarus, 186, 41-59. [7] Watters T. R. et al. (2007) Sciencexpress, science. 1148112, 10.1126.

  20. Formation of an Apokampic Discharge Under Atmospheric Pressure Conditions

    Science.gov (United States)

    Skakun, V. S.; Panarin, V. A.; Pechenitsyn, D. S.; Sosnin, É. A.; Tarasenko, V. F.

    2016-09-01

    A new phenomenon is observed in a spark discharge developing under normal conditions in air in a discharge circuit with a capacitive decoupling. It consists in the current channel bending becoming a source of a 4-6 cm long plasma jet directed across the channel. The phenomenon is termed an apokampic discharge or an apokamp. Its emission spectrum contains the bands of electron-vibration transitions from the second positive group of molecular nitrogen. The conditions of formation of an apokamp are experimentally determined. A conclusion is drawn that in order construct a physical model of an apokamp, one has to take into account: 1) the presence of a local gas overheating in the site of the current channel bending, 2) the similarity of the current and voltage time dependences in the corona discharge and in the current channel (becoming a source of an apokamp), and 3) the length of the apokamp plasma jet.