WorldWideScience

Sample records for atmospheric pressure fluctuations

  1. Radon entry into buildings: Effects of atmospheric pressure fluctuations and building structural factors

    International Nuclear Information System (INIS)

    An improved understanding of the factors that control radon entry into buildings is needed in order to reduce the public health risks caused by exposure to indoor radon. This dissertation examines three issues associated with radon entry into buildings: (1) the influence of a subslab gravel layer and the size of the openings between the soil and the building interior on radon entry; (2) the effect of atmospheric pressure fluctuations on radon entry; and (3) the development and validation of mathematical models which simulate radon and soil-gas entry into houses. Experiments were conducted using two experimental basements to examine the influence of a subslab gravel layer on advective radon entry driven by steady indoor-outdoor pressure differences. These basement structures are identical except that in one the floor slab lies directly on native soil whereas in the other the slab lies on a high-permeability gravel layer. The measurements indicate that a high permeability subslab gravel layer increases the advective radon entry rate into the structure by as much as a factor of 30. The magnitude of the enhancement caused by the subslab gravel layer depends on the area of the openings in the structure floor; the smaller the area of these openings the larger the enhancement in the radon entry rate caused by the subslab gravel layer. A three-dimensional, finite-difference model correctly predicts the effect of a subslab gravel layer and open area configuration on advective radon entry driven by steady indoor-outdoor pressure differences; however, the model underpredicts the absolute entry rate into each structure by a factor of 1.5

  2. Instrument measures dynamic pressure fluctuations

    Science.gov (United States)

    Coats, J. W.; Penko, P. E.; Reshotko, M.

    1977-01-01

    Pressure probe instrument, incorporating "infinite line" principle, can be used to remotely measure dynamic pressure fluctuations in hot high-pressure environemnts too severe for sensors. System is designed and can be utilized for measurements in core of operating turbofan engine.

  3. A model for the effective diffusion of gas or the vapor phase in a fractured media unsaturated zone driven by periodic atmospheric pressure fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Vold, E.L.

    1997-03-01

    There is evidence for migration of tritiated water vapor through the tuff in the unsaturated zone from the buried disposal shafts located on a narrow mesa top at Area G, Los Alamos, NM. Field data are consistent with an effective in-situ vapor phase diffusion coefficient of 1.5x10{sup {minus}3} m{sup s}/s, or a factor of 60 greater than the binary diffusion coefficient for water vapor in air. A model is derived to explain this observation of anomolously large diffusion, which relates an effective vapor or gas phase diffusion coefficient in the fractured porous media to the subsurface propagation of atmospheric pressure fluctuations (barometric pumping). The near surface (unattenuated) diffusion coefficient is independent of mode period under the simplified assumptions of a complete {open_quote}mixing mechanism{close_quote} for the effective diffusion process. The unattenuated effective diffusion driven by this barometric pumping is proportional to an average media permeability times the sum of the square of pressure mode amplitudes, while the attenuation length is proportional to the squarer root of the product of permeability times mode period. There is evidence that the permeability needed to evaluate the pressure attenuation length is the in-situ value, approximately that of the matrix. The diffusion which results using Area G parameter values is negligible in the matrix but becomes large at the effective permeability of the fractured tuff matrix. The effective diffusion coefficient predicted by this model, due to pressure fluctuations and the observed fracture characteristics, is in good agreement with the observed in-situ diffusion coefficient for tritium field measurements. It is concluded that barometric pumping in combination with the enhanced permeability of the fractured media is a likely candidate to account for the observed in-field migration of vapor in the near surface unsaturated zone at Area G.

  4. PRESSURE FLUCTUATIONS BENEATH SPATIAL HYDRAULIC JUMPS

    Institute of Scientific and Technical Information of China (English)

    YAN Zhong-min; ZHOU Chun-tian; LU Shi-qiang

    2006-01-01

    This article deals with statistical analysis of pressure fluctuations at the bottom of spatial hydraulic jumps with abrupt lateral expansions. The effects of the channel expansion ratio and inflow condition on the power spectral and dominant frequency were examined. Pressure data were recorded for different Froude numbers ranging from 3.52 to 6.86 and channel expansion ratios ranging from 1.5 to 3.0. A sampling frequency of 100 Hz was selected. The measurements were conducted in the bed of a glass-walled laboratory flume by means of pressure transducers and data acquisition systems. Power spectra as well as dominant frequency and some other statistical characteristics of fluctuating pressure beneath hydraulic jumps were obtained. Test results were compared with those of classical jump, which indicates that the peak frequencies and intensity coefficients of pressure fluctuations are higher than those of the corresponding classical jumps.

  5. Fluctuation Pressure Assisted Ejection of DNA From Bacteriophage

    CERN Document Server

    Harrison, Michael J

    2010-01-01

    The role of thermal pressure fluctuation excited within tightly packaged DNA prior to ejection from protein capsid shells is discussed in a model calculation. At equilibrium before ejection we assume the DNA is folded many times into a bundle of parallel segments that forms an equilibrium conformation at minimum free energy, which presses tightly against internal capsid walls. Using a canonical ensemble at temperature T we calculate internal pressure fluctuations against a slowly moving or static capsid mantle for an elastic continuum model of the folded DNA bundle. It is found that fluctuating pressure on the capsid internal wall from thermal excitation of longitudinal acoustic vibrations in the bundle may have root-mean-square values which are several tens of atmospheres for typically small phage dimensions. Comparisons are given with measured data on three mutants of lambda phage with different base pair lengths and total genome ejection pressures.

  6. Rapid Fluctuations in the Lower Solar Atmosphere

    CERN Document Server

    Lawrence, J K; Christian, D J; Jess, D B; Mathioudakis, M

    2011-01-01

    The Rapid Oscillations in the Solar Atmosphere (ROSA) instrument reveals solar atmospheric fluctuations at high frequencies. Spectra of variations of the G-band intensity (IG) and CaII K-line intensity (IK) show correlated fluctuations above white noise to frequencies beyond 300 mHz and 50 mHz, respectively. The noise-corrected G-band spectrum for f = 28 - 326 mHz shows a power law with exponent -1.21 \\pm, 0.02, consistent with the presence of turbulent motions. G-band spectral power in the 25 - 100 mHz ("UHF") range is concentrated at the locations of magnetic bright points in the intergranular lanes and is highly intermittent in time. The intermittence of the UHF G-band fluctuations, shown by a positive kurtosis {\\kappa}, also suggests turbulence. Combining values of IG, IK, UHF power, and {\\kappa}, reveals two distinct states of the solar atmosphere. State 1, including almost all the data, is characterized by low IG, IK, and UHF power and {\\kappa} \\approx 6. State 2, including only a very small fraction of...

  7. Vacuum Radiation Pressure Fluctuations and Barrier Penetration

    CERN Document Server

    Huang, Haiyan

    2016-01-01

    We apply recent results on the probability distribution for quantum stress tensor fluctuations to the problem of barrier penetration by quantum particles. The probability for large stress tensor fluctuations decreases relatively slowly with increasing magnitude of the fluctuation, especially when the quantum stress tensor operator has been averaged over a finite time interval. This can lead to large vacuum radiation pressure fluctuations on charged or polarizable particles, which can in turn push the particle over a potential barrier. The rate for this effect depends sensitively upon the details of the time averaging of the stress tensor operator, which might be determined by factors such as the shape of the potential. We make some estimates for the rate of barrier penetration by this mechanism and argue that in some cases this rate can exceed the rate for quantum tunneling through the barrier. The possibility of observation of this effect is discussed.

  8. Atmospheric Pressure Indicator.

    Science.gov (United States)

    Salzsieder, John C.

    1995-01-01

    Discusses observable phenomena related to air pressure. Describes a simple, unobtrusive, semiquantitative device to monitor the changes in air pressure that are associated with altitude, using a soft-drink bottle and a balloon. (JRH)

  9. Internal pressure fluctuations in coacervates and syneresis

    Science.gov (United States)

    Mohanty, B.; Bohidar, H. B.

    2006-12-01

    Syneresis exhibited by a heterogeneous polyampholyte coacervate (polymer-rich phase) is discussed through non-equilibrium statistical thermodynamics. It has been shown that the coacervate phase is associated with fluctuating excess internal pressure that gives rise to syneresis. It is proposed that energy is dissipated to the environment only by the surface of coacervate, whereas in the bulk, gelatin chains only exchange energy with each other with negligible or no dissipation. Consequently, the internal pressure inside the coacervate follows a damped oscillatory behaviour that relaxes slowly with time, independently of amplitude. We connect the volume of the supernatant released with time (exponential relaxation behavior) with the presence of long-lived nonlinear localized modes (the existence of breathers).

  10. Atmospheric Pressure During Landing

    Science.gov (United States)

    1997-01-01

    This figure shows the variation with time of pressure (dots) measured by the Pathfinder MET instrument during the landing period shown in image PIA00797. The two diamonds indicate the times of bridal cutting and 1st impact. The overall trend in the data is of pressure increasing with time. This is almost certainly due to the lander rolling downhill by roughly 10 m. The spacing of the horizontal dotted lines indicates the pressure change expected from 10 m changes in altitude. Bounces may also be visible in the data.

  11. Algorithmic Summaries of Perioperative Blood Pressure Fluctuations.

    Science.gov (United States)

    Toddenroth, Dennis; Ganslandt, Thomas; Drescher, Caroline; Weith, Thomas; Prokosch, Hans-Ulrich; Schuettler, Juergen; Muenster, Tino

    2016-01-01

    Automated perioperative measurements such as cardiovascular monitoring data are commonly compared to established upper and lower thresholds, but could also allow for more complex interpretations. Analyzing such time series in extensive electronic medical records for research purposes may itself require customized automation, so we developed a set of algorithms for quantifying different aspects of temporal fluctuations. We implemented conventional measures of dispersion, summaries of absolute gradients between successive values, and Poincaré plots. We aggregated the severity and duration of hypotensive episodes by calculating the average area under different mean arterial pressure (MAP) thresholds. We applied these methods to 30,452 de-identified MAP series, and analyzed the similarity between alternative indices via hierarchical clustering. To explore the potential utility of these propositional metrics, we computed their statistical association with presumed complications due to cardiovascular instability. We observed that hierarchical clustering reliably segregated features that had been designed to quantify dissimilar aspects. Summaries of temporary hypotension turned out to be significantly increased among patient subgroups with subsequent signs of a complicated recovery. These associations were even stronger for measures that were specifically geared to capturing short-term MAP variability. These observations suggest the potential capability of our proposed algorithms for quantifying heterogeneous aspects of short-term MAP fluctuations. Future research might also target a wider selection of outcomes and other attributes that may be subject to intraoperative variability. PMID:27577440

  12. Molecular dynamic study of pressure fluctuations spectrum in plasma

    Science.gov (United States)

    Bystryi, R. G.

    2015-11-01

    Pressure of plasma is calculated by using classical molecular dynamics method. The formula based on virial theorem was used. Spectrum pressure's fluctuations of singly ionized non-ideal plasma are studied. 1/f-like spectrum behavior is observed. In other words, flicker noise is observed in fluctuations of pressure equilibrium non-ideal plasma. Relations between the obtained result and pressure fluctuations within the Gibbs and Einstein approaches are discussed. Special attention is paid to features of calculating the pressure in strongly coupled systems.

  13. Similarity law of fluctuating pressure spectrum beneath hydraulic jump

    Institute of Scientific and Technical Information of China (English)

    LIAN JiJian; WANG JiMin; GU JinDe

    2008-01-01

    Similarity law is the conversion rule between model and prototype, on which a lot of research works have been done, with no agreement reached referring to the similarity law of fluctuating pressure fre-quency spectrum. Experimental data of peak frequency and dominant frequency range of fluctuating pressure spectrum beneath hydraulic jump obtained from serial models of scales 1:1, 1:2 and 1:5 are compared. As a result, similarity law of fluctuating pressure spectrum in the strongly rolling area agrees with the gravity law. As peak frequency and dominant frequencies of fluctuating pressures in hydraulic normalized spectrums of fluctuating pressures show that the similarity nearly agrees with the gravity law.

  14. Combustion instability detection using the wavelet detail of pressure fluctuations

    Institute of Scientific and Technical Information of China (English)

    Junjie JI; Yonghao LUO

    2008-01-01

    A combustion instability detection method that uses the wavelet detail of combustion pressure fluctuations is put forward. To confirm this method, combustion pressure fluctuations in a stoker boiler are recorded at stable and unstable combustion with a pressure transducer. Daubechies one-order wavelet is chosen to obtain the wavelet details for comparison. It shows that the wavelet approximation indicates the general pressure change in the furnace, and the wavelet detail magnitude is consistent with the intensity of turbulence and combustion noise. The magnitude of the wavelet detail is nearly constant when the combustion is stable, however, it will fluctuate much when the combustion is unstable.

  15. Numerical simulation of pressure fluctuation in Kaplan turbine

    Institute of Scientific and Technical Information of China (English)

    LIU ShuHong; SHAO Jie; WU ShangFeng; WU YuLin

    2008-01-01

    As it is almost impossible to carry out the prototype hydro-turbine experiment be-fore the power plant is built up, rational prediction of pressure fluctuations in the prototype turbine is very important at the design stage. From this viewpoint, we at first treated the unsteady turbulent flow computation based on the modified RNG k-ε turbulence model through the whole flow passage to simulate the pressure fluctuation in a model turbine. Since fair agreement was recognized between the numerical results and the experimental data, this numerical method was applied to simulate the pressure fluctuations in the prototype turbine. From the comparison of them with the model turbine results, it is seen that their qualitative trend of pres-sure fluctuations are similar, but an appreciable difference is observed between the amplitudes of pressure fluctuation of the prototype turbine and that of the model turbine. Though the present findings may be explained by the effect of Reynolds number, further studies are expected for quantitative interpretation. We paid atten-tion to the interaction between the fluid and turbine structure. Adopting a weak fluid-solid coupling method, we studied the pressure fluctuation in the prototype turbine to clarify how the elastic behavior of runner blades influenced the charac-teristics of pressure fluctuation.

  16. Numerical simulation of pressure fluctuation in Kaplan turbine

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    As it is almost impossible to carry out the prototype hydro-turbine experiment be- fore the power plant is built up, rational prediction of pressure fluctuations in the prototype turbine is very important at the design stage. From this viewpoint, we at first treated the unsteady turbulent flow computation based on the modified RNG k-ε turbulence model through the whole flow passage to simulate the pressure fluctuation in a model turbine. Since fair agreement was recognized between the numerical results and the experimental data, this numerical method was applied to simulate the pressure fluctuations in the prototype turbine. From the comparison of them with the model turbine results, it is seen that their qualitative trend of pres- sure fluctuations are similar, but an appreciable difference is observed between the amplitudes of pressure fluctuation of the prototype turbine and that of the model turbine. Though the present findings may be explained by the effect of Reynolds number, further studies are expected for quantitative interpretation. We paid atten- tion to the interaction between the fluid and turbine structure. Adopting a weak fluid-solid coupling method, we studied the pressure fluctuation in the prototype turbine to clarify how the elastic behavior of runner blades influenced the charac- teristics of pressure fluctuation.

  17. Two-color correlation between intensity fluctuations in atmospheric turbulence

    Science.gov (United States)

    Luo, Meilan; Zhao, Daomu

    2016-06-01

    The correlation between intensity fluctuations generated by two varying wavelengths through a turbulent medium is investigated, where the influences arising from source correlation and perturbation of atmosphere are mainly emphasized. It is demonstrated that the correlation between intensity fluctuations can be enhanced or reduced by modulating the difference of two incident wavelengths. For shorter wavelength, the correlation between intensity fluctuations is stronger at the far field. In addition, in the case of single wavelength, a relationship λ1z1 =λ2z2 =λnzn holding in free space could be found, from which the distance where the peak value occurs may be inferred. However, it can be destroyed by increasing the strength of atmosphere.

  18. Slipstream-induced pressure fluctuations on a wing panel

    Science.gov (United States)

    Ljunggren, Sten; Samuelsson, Ingemar; Widig, Kurt

    1989-10-01

    Propeller-induced pressure fluctuations have been measured on a wind-tunnel model. The results show that the main contribution on the wing panels can be attributed to the propeller tip vortex, which gives a pressure level at least 20 dB above the level from the inner parts of the propeller. The pressure fluctuations are predominantly periodic and the spectrum shows strong peaks at the blade passage frequency and its harmonics. The pressure level at the blade passage frequency is approximately the same on wing panel and fuselage, while the level of the higher harmonics is substantially higher on the wing panel than on the fuselage.

  19. Determining Atmospheric Pressure Using a Water Barometer

    Science.gov (United States)

    Lohrengel, C. Frederick, II; Larson, Paul R.

    2012-01-01

    The atmosphere is an envelope of compressible gases that surrounds Earth. Because of its compressibility and nonuniform heating by the Sun, it is in constant motion. The atmosphere exerts pressure on Earth's surface, but that pressure is in constant flux. This experiment allows students to directly measure atmospheric pressure by measuring the…

  20. Energy harvesting from hydraulic pressure fluctuations

    Science.gov (United States)

    Cunefare, K. A.; Skow, E. A.; Erturk, A.; Savor, J.; Verma, N.; Cacan, M. R.

    2013-02-01

    State-of-the-art hydraulic hose and piping systems employ integral sensor nodes for structural health monitoring to avoid catastrophic failures. Energy harvesting in hydraulic systems could enable self-powered wireless sensor nodes for applications such as energy-autonomous structural health monitoring and prognosis. Hydraulic systems inherently have a high energy intensity associated with the mean pressure and flow. Accompanying the mean pressure is the dynamic pressure ripple, which is caused by the action of pumps and actuators. Pressure ripple is a deterministic source with a periodic time-domain behavior conducive to energy harvesting. An energy harvester prototype was designed for generating low-power electricity from pressure ripples. The prototype employed an axially-poled off-the-shelf piezoelectric stack. A housing isolated the stack from the hydraulic fluid while maintaining a mechanical coupling allowing for dynamic-pressure-induced deflection of the stack. The prototype exhibited an off-resonance energy harvesting problem since the fundamental resonance of the piezoelectric stack was much higher than the frequency content of the pressure ripple. The prototype was designed to provide a suitable power output for powering sensors with a maximum output of 1.2 mW. This work also presents electromechanical model simulations and experimental characterization of the piezoelectric power output from the pressure ripple in terms of the force transmitted into the harvester.

  1. PRESSURE FLUCTUATIONS IN GAS-SOLIDS FLUIDIZED BEDS

    Institute of Scientific and Technical Information of China (English)

    Hsiaotao Bi; Aihua Chen

    2003-01-01

    Pressure fluctuation data measured in a series of fluidized beds with diameters of 0.05, 0.1, 0.29, 0.60 and 1.56 m showed that the maximum amplitude or standard deviation increased with increasing the superficial gas velocity and static bed height for relatively shallow beds and became insensitive to the increase in static bed height in relatively deep beds. The amplitude appeared to be less dependent on the measurement location in the dense bed. Predictions based on bubble passage, bubble eruption at the upper bed surface and bed oscillation all failed to explain all observed trends and underestimated the amplitude of pressure fluctuations, suggesting that the global pressure fluctuations in gas-solids bubbling fluidized beds are the superposition of local pressure variations, bed oscillations and pressure waves generated from the bubble formation in the distributor region, bubble coalescence during their rise and bubble eruption at the upper bed surface.

  2. Domestic atmospheric pressure thermal deaerators

    Science.gov (United States)

    Egorov, P. V.; Gimmelberg, A. S.; Mikhailov, V. G.; Baeva, A. N.; Chuprakov, M. V.; Grigoriev, G. V.

    2016-04-01

    Based on many years of experience and proven technical solutions, modern atmospheric pressure deaerators of the capacity of 0.4 to 800 t/h were designed and developed. The construction of such deaerators is based on known and explored technical solutions. A two-stage deaeration scheme is applied where the first stage is a jet dripping level (in a column) and the second one is a bubble level (in a tank). In the design of deaeration columns, low-pressure hydraulic nozzles (Δ p heat and mass exchange processes in the apparatus. The use of the two efficient stages in a column and a "flooded" sparger in a tank allows to reliably guarantee the necessary water heating and deaeration. Steam or "superheated" water of the temperature of t ≥ 125°C can be used as the coolant in the deaerators. The commissioning tests of the new deaerator prototypes of the capacity of 800 and 500 t/h in the HPP conditions showed their sustainable, reliable, and efficient work in the designed range of hydraulic and thermal loads. The content of solved oxygen and free carbon dioxide in make-up water after deaerators meets the requirements of State Standard GOST 16860-88, the operating rules and regulations, and the customer's specifications. Based on these results, the proposals were developed on the structure and the design of deaerators of the productivity of more than 800 t/h for the use in circuits of large heating systems and the preparation of feed water to the TPP at heating and industrial-heating plants. The atmospheric pressure thermal deaerators developed at NPO TsKTI with consideration of the current requirements are recommended for the use in water preparation schemes of various power facilities.

  3. Unsteady Turbulent Simulation and Pressure Fluctuation Analysis for Centrifugal Pumps

    Institute of Scientific and Technical Information of China (English)

    YUAN Shouqi; NI Yongyan; PAN Zhongyong; YUAN Jianping

    2009-01-01

    The pressure fluctuation in the flow passage of both impeller and casing is addressed on design condition. The initial conditions for the unsteady turbulent simulation are resulted from the steady calculations, and the three dimensional unsteady turbulent simulation concerning the rotor-stator interaction is executed by a Navier-Stoke solver embedded with k -ε turbulence model and with appropriate moving interface boundary conditions. Detecting points are distributed in the flow passage in different radial and circumferential positions to capture the static pressure fluctuation character for one cycle of the impeller. The time-domain spectrums show that the static pressure curves are periodic and have five peaks and five valleys. With the radius increasing, the pressure fluctuation peak-to-peak values in the impeller are increasing, and reach the maximum value on the interface. In the casing flow passage, those values are about 7% of local static pressure except some ones near the tongue. The values become decreasingly in the diffuser pipe. The frequency spectrums transformed by fast Fourier transform (FFT) show that the dominant frequency is approximate with the blade passing frequency, and the pressure fluctuations in impeller passage have high frequency content while those in casing ones have no such information.

  4. Atmospheric pressure plasma jet applications

    Energy Technology Data Exchange (ETDEWEB)

    Park, J.; Herrmann, H.W.; Henins, I.; Selwyn, G.S. [Los Alamos National Lab., NM (United States)

    1998-12-31

    The atmospheric pressure plasma jet (APPJ) is a non-thermal, high pressure plasma discharge that produces a high velocity effluent stream of highly reactive chemical species. The discharge operates on a feedstock gas (e.g., He/O2/H2O) which flows between two concentric cylindrical electrodes: an outer grounded electrode and an inner electrode powered at 13.56 MHz RF. While passing through the plasma, the feedgas becomes excited, ionized or dissociated by electron impact. The fast-flowing effluent consists of ions and electrons, which are rapidly lost by recombination, highly reactive radicals (e.g., O, OH), and metastable species (e.g., O2). The metastable O2, which is reactive to hydrocarbon and other organic species, has been observed through optical emission spectroscopy to decrease by a factor of 2 from the APPJ nozzle exit to a distance of 10 cm. Unreacted metastable O2, and that which does not impinge on a surface, will then decay back to ordinary ground state O2, resulting in a completely dry, environmentally-benign form of surface cleaning. Applications such as removal of photoresist, oxide films and organic residues from wafers for the electronics industry, decontamination of civilian and military areas and personnel exposed to chemical or biological warfare agents, and paint (e.g., graffiti) removal are being considered.

  5. Power-law distribution of pressure fluctuations in multiphase flow

    OpenAIRE

    Gheorghiu, S.; J.R. van Ommen; Coppens, M.-O.

    2003-01-01

    The power-law distribution of pressure fluctuation in multiphase flow was discussed. It was found that the probability density function exhibited a power-law drop-off and was well represented by a Tsallis distribution. The analysis showed that the Tsallis statistics arised as a result of bubble polydispersity, rather than system nonextensivity.

  6. Modelling surface pressure fluctuation on medium-rise buildings

    NARCIS (Netherlands)

    Snæbjörnsson, J.T.; Geurts, C.P.W.

    2006-01-01

    This paper describes the results of two experiments into the fluctuating characteristics of windinduced pressures on buildings in a built-up environment. The experiments have been carried out independently in Iceland and The Netherlands and can be considered to represent two separate cases of buildi

  7. CHARACTERISTICS OF CORRELATION AND SPECTRUM BETWEEN WALL FLUCTUATING PRESSURE AND FLUCTUATING VELOCITY OF IMPING-ING JET

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The correlation, the spectrum and the turbu-lent scale between wall fluctuating pressure and fluctuating ve-locity, on the bed of plunging pool under the action of single and twin impinging jet, are investigated in the paper by using 2-D LDA and the dynamic pressure scanning system of multi-ple points. It is found that the cross correlation between the horizontal fluctuating velocity and the fluctuating pressure of twin jet is bigger than that of sinlge jet, and the spectrum be-tween horizontal fluctuating velocity and fluctuating pressure obviously has approximately dominant frequency. The rela-tionship between the fluctuation pressure coefficient on wall and the turbulent intensity near the wall can be described with logarithmic curve.

  8. Study on temperature fluctuation phenomena in pressurizer spray pipe of pressurized water reactor

    International Nuclear Information System (INIS)

    Damage of a pressurizer spray piping in a PWR plant is potentially considered from a safety point of views. Gas-liquid interface is formed in the pressurizer spray pipe of the PWR under a rated power operating condition. Temperature fluctuation may occur if the interface may move periodically. Measurement of inner wall and fluid temperature in the test section simulating the real pressurizer spray pipe was conducted to study mechanism of the temperature fluctuation phenomena. The temperature fluctuations were observed. Visualization experiment was conducted to understand the flow phenomena. It was estimated that Kelvin-Helmholtz instability occurred in the liquid layer in a horizontal pipe in the spray piping. (author)

  9. An Atmospheric Pressure Ping-Pong "Ballometer"

    Science.gov (United States)

    Kazachkov, Alexander; Kryuchkov, Dmitriy; Willis, Courtney; Moore, John C.

    2006-01-01

    Classroom experiments on atmospheric pressure focus largely on demonstrating its existence, often in a most impressive way. A series of amusing physics demonstrations is widely known and practiced by educators teaching the topic. However, measuring the value of atmospheric pressure(P[subscript atm]) is generally done in a rather mundane way,…

  10. Pressure Fluctuations as a Diagnostic Tool for Fluidized Beds

    Energy Technology Data Exchange (ETDEWEB)

    Ethan Bure; Joel R. Schroeder; Ramon De La Cruz; Robert C. Brown

    1998-05-01

    The purpose of this project was to investigate the origin of pressure fluctuations in fluidized bed systems. The study assessed the potential for using pressure fluctuations as an indicator of fluidized bed hydrodynamics in both laboratory scale cold-models and industrial scale boilers. Both bubbling fluidized beds and circulating fluidized beds were evaluated. Testing including both cold-flow models and laboratory and industrial-scale combustors operating at elevated temperatures. The study yielded several conclusions on the relationship of pressure fluctuations and hydrodynamic behavior in fluidized beds. The study revealed the importance of collecting sufficiently long data sets to capture low frequency (on the order of 1 Hz) pressure phenomena in fluidized beds. Past research has tended toward truncated data sets collected with high frequency response transducers, which miss much of the spectral structure of fluidized bed hydrodynamics. As a result, many previous studies have drawn conclusions concerning hydrodynamic similitude between model and prototype fluidized beds that is insupportable from the low resolution data presented.

  11. EXPERIMENTAL STUDY ON INFLUENCE OF SUPPLIED PRESSURE FLUCTUATION ON OUTPUT ARACTERISTIC OF PRESSURE CONTROL SYSTEM OF ROLLING MILL

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    The infulence of supplied pressure fluctuation on output accuracy for the electro-hydraulic pressure control system of the rolling mill is discussed.Based on the bond graph theory and experimental study,the relationship between the variation of system output pressure and the supplied pressure fluctuation and the influence of the system bandwidth on system output pressure are provided.A theoretical base for determining the allowable fluctuation range of pressure and accurate design of constant pressure source system is obtained.

  12. Detrended Fluctuation Analysis of Systolic Blood Pressure Control Loop

    CERN Document Server

    Galhardo, C E C; de Menezes, M Argollo; Soares, P P S

    2009-01-01

    We use detrended fluctuation analysis (DFA) to study the dynamics of blood pressure oscillations and its feedback control in rats by analyzing systolic pressure time series before and after a surgical procedure that interrupts its control loop. We found, for each situation, a crossover between two scaling regions characterized by exponents that reflect the nature of the feedback control and its range of operation. In addition, we found evidences of adaptation in the dynamics of blood pressure regulation a few days after surgical disruption of its main feedback circuit. Based on the paradigm of antagonistic, bipartite (vagal and sympathetic) action of the central nerve system, we propose a simple model for pressure homeostasis as the balance between two nonlinear opposing forces, successfully reproducing the crossover observed in the DFA of actual pressure signals.

  13. Characteristics of fluctuating pressure generated in BWR main steam lines

    International Nuclear Information System (INIS)

    The BWR-3 steam dryer in the Quad Cities Unit 2 Nuclear Power Plant was damaged by high cycle fatigue due to acoustic-induced vibration. The dryer failure was as attributed to flow-induced acoustic resonance at the stub pipes of safety relief valves (SRVs) in the main steam lines (MSLs). The acoustic resonance was considered to be generated by interaction between the sound field and an unstable shear layer across the closed side branches with SRV stub pipes. We have started a research program on BWR dryers to develop their loading evaluation methods. Moreover, it has been necessary to evaluate the dryer integrity of BWR-5 plants which are the main type of BWR in Japan. In the present study, we used 1/10-scale BWR tests and analyses to investigate the flow-induced acoustic resonance and acoustic characteristics in MSLs. The test apparatus consisted of a steam dryer, a steam dome and 4 MSLs with 20 SRV stub pipes. A finite element method (FEM) was applied for the calculation of three-dimensional wave equations in acoustic analysis. We demonstrated that remarkable fluctuating pressures occurred in high and low frequency regions. High frequency fluctuating pressures was generated by the flow-induced acoustic resonance in the SRV stub pipes. Low frequency fluctuating pressure was generated in an MSL with the dead leg. The frequency of the latter almost coincided with the natural frequency of the MSL with the dead leg. The amplitude of the fluctuating pressures in the multiple stub pipes became more intense because of interaction between them compared with that in the single stub pipe. Acoustic analysis results showed that the multiple stub pipes caused several natural frequencies in the vicinity of the natural frequency of the single stub pipe and several modes of the standing wave in the MSLs. (author)

  14. Prediction of propeller-induced hull-pressure fluctuations

    OpenAIRE

    Van Wijngaarden, H.C.J.

    2011-01-01

    The cavitating propeller often forms the primary source of noise and vibration on board ships. The propeller induces hydroacoustic pressure fluctuations due to the passing blades and, more importantly, the dynamic activity of cavities in the propeller’s immediate vicinity. The accurate prediction of the resulting vibratory hull-excitation forces is indispensible in the ship design process, but is not always warranted. From this follows the main objective of the thesis, which is the developmen...

  15. Investigation of temperature fluctuation phenomena in pressurizer spray pipe of pressurized water reactor

    International Nuclear Information System (INIS)

    Gas liquid interface is formed in a pressurizer spray pipe of a pressurized water reactor when flow rate is small at normal reactor operation. Temperature fluctuation may occur if the interface moves periodically. Measurement of inner wall and fluid temperature in the test section simulating the real pressurizer spray pipe was conducted to study mechanism of the temperature fluctuation phenomena. The effect of non-condensable gas was investigated by injecting helium gas into test section. When helium gas was injected, the condensation of the vapor was suppressed and the temperature fluctuation was reduced. Richardson number increases with the helium gas injection, which is higher than 0.25 in all conditions of the present experiment. Brunt Vaisala frequency nearly equal to the peak of temperature power spectral density. It seemed that the internal gravity waves caused temperature fluctuations in water layer below the interface. (author)

  16. Alternative theories of atmospheric telecommunications and low-frequency fluctuations

    Science.gov (United States)

    Frederiksen, Jorgen S.; Webster, Peter J.

    1988-08-01

    Observational studies have revealed a rich low-frequency structure in the atmosphere. A review of the theories, observations, and model studies of this low-frequency atmospheric variability is presented. On time scales of weeks or longer the atmosphere appears to possess distinct oscillatory behavior in well-defined and persistent "centers of action." This behavior is also an endemic feature of surrogate atmospheric data sets emerging from experiments with complicated climate models. Many theories have attempted to determine the dominant physical processes responsible for the low-frequency variance but have usually failed when compared carefully with observations. For example, simple linear steady state and Rossby wave dispersion theories have been used in an attempt to explain the observed global response to low-latitude perturbation. However, the observed structures of mature anomalies are often quite distinct from the vertical structures of disturbances predicted in these theories. Also, in general circulation and model studies, the sign of the nonlinear response is not simply related to the sign of the forcing as predicted by linear steady state theories. It is argued that the theories fail because either the full three-dimensional complexity of the basic state is not considered or its inherent instability structure is not recognized or is, in fact, ignored. It is shown that three-dimensional instability theory provides a natural generalization and marriage of the zonally averaged instability theory of Charney and Eady and the Rossby wave dispersion theory of Rossby and Yeh. As such, it provides a formalism which may be used to understand a wide variety of atmospheric fluctuations including the locations of eddy flux covariance maxima and storm tracks in both the tropics and extratropics and the generation of blocking, teleconnection patterns, and other quasi-stationary anomaly features. Attention is focused on two particular mechanisms within this formalism

  17. Evaporation of urea at atmospheric pressure.

    Science.gov (United States)

    Bernhard, Andreas M; Czekaj, Izabela; Elsener, Martin; Wokaun, Alexander; Kröcher, Oliver

    2011-03-31

    Aqueous urea solution is widely used as reducing agent in the selective catalytic reduction of NO(x) (SCR). Because reports of urea vapor at atmospheric pressure are rare, gaseous urea is usually neglected in computational models used for designing SCR systems. In this study, urea evaporation was investigated under flow reactor conditions, and a Fourier transform infrared (FTIR) spectrum of gaseous urea was recorded at atmospheric pressure for the first time. The spectrum was compared to literature data under vacuum conditions and with theoretical spectra of monomolecular and dimeric urea in the gas phase calculated with the density functional theory (DFT) method. Comparison of the spectra indicates that urea vapor is in the monomolecular form at atmospheric pressure. The measured vapor pressure of urea agrees with the thermodynamic data obtained under vacuum reported in the literature. Our results indicate that considering gaseous urea will improve the computational modeling of urea SCR systems.

  18. Pressure fluctuations induced by fluid flow in singular points of industrial circuits

    International Nuclear Information System (INIS)

    Flow singularities (enlargements, bards, valves, tees, ...) generate in the circuits of industrial plants wall pressure fluctuations which are the main cause of vibration. A methodical study of the most current singularities has been performed at C.E.A./D.E.M.T. On one hand a theory of noise generation by unsteady flow in internal acoustics has been developed. This theory uses the basic ideas initiated by LIGHTILL. As a result it is shown that the plane wave propagation is a valid assumption and that a singularity can be acoustically modelled by a pressure and a mass-flow-rate discontinuities. Both are random functions of time, the spectra of which are determined from the local fluctuations characteristics. On other hand, characteristics of several singularities have been measured: intercorrelation spectra of local pressure fluctuations. Autocorrelation spectra of associated acoustical sources (the measure of the acoustical pressures in the experimental circuit are interpreted by using the D.E.M.T. computer code VIBRAPHONE which gives the acoustical response of a complex circuit. Experimental atmospheric air and water loops have been used. The Reynolds number has been changed between about 105 and 106; the Mach number between about 0,01 and 0,5. Simple laws with dimensionless parameters are formulated and can be used for the estimation of the acoustical and mechanical vibration level of a circuit with given singularities

  19. A decadal precession of atmospheric pressures over the North Pacific

    Science.gov (United States)

    Anderson, Bruce T.; Gianotti, Daniel J. S.; Furtado, Jason C.; Di Lorenzo, Emanuele

    2016-04-01

    Sustained droughts over the Northwestern U.S. can alter water availability to the region's agricultural, hydroelectric, and ecosystem service sectors. Here we analyze decadal variations in precipitation across this region and reveal their relation to the slow (~10 year) progression of an atmospheric pressure pattern around the North Pacific, which we term the Pacific Decadal Precession (PDP). Observations corroborate that leading patterns of atmospheric pressure variability over the North Pacific evolve in a manner consistent with the PDP and manifest as different phases in its evolution. Further analysis of the data indicates that low-frequency fluctuations of the tropical Pacific Ocean state energize one phase of the PDP and possibly the other through coupling with the polar stratosphere. Evidence that many recent climate variations influencing the North Pacific/North American sector over the last few years are consistent with the current phase of the PDP confirms the need to enhance our predictive understanding of its behavior.

  20. The major influence of the atmosphere on intracranial pressure: an observational study

    Science.gov (United States)

    Herbowski, Leszek

    2016-06-01

    The impact of the atmosphere on human physiology has been studied widely within the last years. In practice, intracranial pressure is a pressure difference between intracranial compartments and the surrounding atmosphere. This means that gauge intracranial pressure uses atmospheric pressure as its zero point, and therefore, this method of pressure measurement excludes the effects of barometric pressure's fluctuation. The comparison of these two physical quantities can only take place through their absolute value relationship. The aim of this study is to investigate the direct effect of barometric pressure on the absolute intracranial pressure homeostasis. A prospective observational cross-sectional open study was conducted in Szczecin, Poland. In 28 neurosurgical patients with suspected normal-pressure hydrocephalus, intracranial intraventricular pressure was monitored in a sitting position. A total of 168 intracranial pressure and atmospheric pressure measurements were performed. Absolute atmospheric pressure was recorded directly. All values of intracranial gauge pressure were converted to absolute pressure (the sum of gauge intracranial pressure and local absolute atmospheric pressure). The average absolute mean intracranial pressure in the patients is 1006.6 hPa (95 % CI 1004.5 to 1008.8 hPa, SEM 1.1), and the mean absolute atmospheric pressure is 1007.9 hPa (95 % CI 1006.3 to 1009.6 hPa, SEM 0.8). The observed association between atmospheric and intracranial pressure is strongly significant (Spearman correlation r = 0.87, p < 0.05) and all the measurements are perfectly reliable (Bland-Altman coefficient is 4.8 %). It appears from this study that changes in absolute intracranial pressure are related to seasonal variation. Absolute intracranial pressure is shown to be impacted positively by atmospheric pressure.

  1. The major influence of the atmosphere on intracranial pressure: an observational study

    Science.gov (United States)

    Herbowski, Leszek

    2016-06-01

    The impact of the atmosphere on human physiology has been studied widely within the last years. In practice, intracranial pressure is a pressure difference between intracranial compartments and the surrounding atmosphere. This means that gauge intracranial pressure uses atmospheric pressure as its zero point, and therefore, this method of pressure measurement excludes the effects of barometric pressure's fluctuation. The comparison of these two physical quantities can only take place through their absolute value relationship. The aim of this study is to investigate the direct effect of barometric pressure on the absolute intracranial pressure homeostasis. A prospective observational cross-sectional open study was conducted in Szczecin, Poland. In 28 neurosurgical patients with suspected normal-pressure hydrocephalus, intracranial intraventricular pressure was monitored in a sitting position. A total of 168 intracranial pressure and atmospheric pressure measurements were performed. Absolute atmospheric pressure was recorded directly. All values of intracranial gauge pressure were converted to absolute pressure (the sum of gauge intracranial pressure and local absolute atmospheric pressure). The average absolute mean intracranial pressure in the patients is 1006.6 hPa (95 % CI 1004.5 to 1008.8 hPa, SEM 1.1), and the mean absolute atmospheric pressure is 1007.9 hPa (95 % CI 1006.3 to 1009.6 hPa, SEM 0.8). The observed association between atmospheric and intracranial pressure is strongly significant (Spearman correlation r = 0.87, p Altman coefficient is 4.8 %). It appears from this study that changes in absolute intracranial pressure are related to seasonal variation. Absolute intracranial pressure is shown to be impacted positively by atmospheric pressure.

  2. Fluctuations, Response, and Resonances in a Simple Atmospheric Model

    CERN Document Server

    Gritsun, Andrey

    2016-01-01

    We study the response of a simple quasi-geostrophic barotropic model of the atmosphere to various classes of perturbations affecting its forcing and its dissipation using the formalism of the Ruelle response theory. We investigate the geometry of such perturbations using the covariant Lyapunov vectors on the unperturbed system and discover in one specific case - orographic forcing - a substantial projection of the perturbation onto the stable directions of the flow. As a result, we find a clear violation of the fluctuation-dissipation theorem, in agreement with the basic tenets of nonequilibrium statistical mechanics. This results into a very strong response in the form of a forced Rossby-like wave that has no resemblance to the natural variability in the same range of spatial and temporal scales. We further analyze such a feature and discover it can be interpreted as resonant response to a specific group of rarely visited unstable periodic orbits of the unperturbed system. Our results reinforce the idea of u...

  3. Graphene Membranes for Atmospheric Pressure Photoelectron Spectroscopy.

    Science.gov (United States)

    Weatherup, Robert S; Eren, Baran; Hao, Yibo; Bluhm, Hendrik; Salmeron, Miquel B

    2016-05-01

    Atmospheric pressure X-ray photoelectron spectroscopy (XPS) is demonstrated using single-layer graphene membranes as photoelectron-transparent barriers that sustain pressure differences in excess of 6 orders of magnitude. The graphene serves as a support for catalyst nanoparticles under atmospheric pressure reaction conditions (up to 1.5 bar), where XPS allows the oxidation state of Cu nanoparticles and gas phase species to be simultaneously probed. We thereby observe that the Cu(2+) oxidation state is stable in O2 (1 bar) but is spontaneously reduced under vacuum. We further demonstrate the detection of various gas-phase species (Ar, CO, CO2, N2, O2) in the pressure range 10-1500 mbar including species with low photoionization cross sections (He, H2). Pressure-dependent changes in the apparent binding energies of gas-phase species are observed, attributable to changes in work function of the metal-coated grids supporting the graphene. We expect atmospheric pressure XPS based on this graphene membrane approach to be a valuable tool for studying nanoparticle catalysis.

  4. Runaway electron beam in atmospheric pressure discharges

    Science.gov (United States)

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

    2015-11-01

    A numerical simulation was performed to study the formation of a runaway electron (RAE) beam from an individual emission zone in atmospheric pressure air discharges with a highly overvolted interelectrode gap. It is shown that the formation of a RAE beam in discharges at high overvoltages is much contributed by avalanche processes.

  5. Atmospheric pressure femtosecond laser imaging mass spectrometry

    Science.gov (United States)

    Coello, Yves; Gunaratne, Tissa C.; Dantus, Marcos

    2009-02-01

    We present a novel imaging mass spectrometry technique that uses femtosecond laser pulses to directly ionize the sample. The method offers significant advantages over current techniques by eliminating the need of a laser-absorbing sample matrix, being suitable for atmospheric pressure sampling, and by providing 10μm resolution, as demonstrated here with a chemical image of vegetable cell walls.

  6. Experimental Analysis of Pressure Fluctuations behind a Bottom Aerator

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Experimental observations show that the random process of two-phase flow beh ind an aerator is an ergodic process and its amplitude distribution is similar t o a normal distribution. The maximum pressure fluctuation is at the re-attachme n t point where the jet-trajectory flow over the aerator re-attaches to bottom o f the channel, and its amplitude is 2-3 times larger than when there is no aerato r. There is a dominant frequency of 1.24 Hz in the model, but the coherence in th e frequency domain is not obvious for other frequencies beside the dominant frequ ency. There is a large vortex at the re-attachment point behind the aerator but correlation among the measurement points is not obvious in the time domain.

  7. Atmospheric pressure plasma research activity in korea

    International Nuclear Information System (INIS)

    Plasma is generated by electrical discharge. Most plasma generation has been carried out at low-pressure gas typically less than one millionth of atmospheric pressure. Plasmas are in general generated from impact ionizations of neutral gas molecules by accelerated electrons. The energy gain of electrons accelerated in an electrical field is proportional to the mean free path. Electrons gain more energy at low-pressure gas and generate plasma easily by the ionization of neutrals, because the mean free path is longer. For this reason conventional plasma generation is carried out at low pressures. However, many practical applications require plasmas at high-pressure. In order to avoid the requirement for vacuum pump, researchers in Korea start to develop plasmas in high-pressure chambers where the pressure is 1 atmosphere or greater. Material processing, environmental protection/restoration and improved energy production efficiency using plasma are only possible for inexpensive bulk plasmas. We thus generate plasmas by new methods and plan to set foundations for new plasma technologies for 21st century industries. This technological research will play a central role in material processing, environmental and energy production industries

  8. Response of cyanobacteria to low atmospheric pressure

    Science.gov (United States)

    Qin, Lifeng; Yu, Qingni; Ai, Weidang; Tang, Yongkang; Ren, Jin; Guo, Shuangsheng

    2014-10-01

    Maintaining a low pressure environment in a controlled ecological life support system would reduce the technological complexity and resupply cost in the course of the construction of a future manned lunar base. To estimate the effect of a hypobaric environment in a lunar base on biological components, such as higher plants, microbes, and algae, cyanobacteria was used as the model by determining their response of growth, morphology, and physiology when exposed to half of standard atmospheric pressure for 16 days (brought back to standard atmospheric pressure 30 minutes every two days for sampling). The results indicated that the decrease of atmospheric pressure from 100 kPa to 50 kPa reduced the growth rates of Microcystis aeruginosa, Merismopedia sp., Anabaena sp. PCC 7120, and Anabaena flos-aquae. The ratio of carotenoid to chlorophyll a content in the four tested strains increased under low pressure conditions compared to ambient conditions, resulting from the decrease of chlorophyll a and the increase of carotenoid in the cells. Moreover, low pressure induced the reduction of the phycocyanin content in Microcystis aeruginosa, Anabaena sp. PCC 7120, and Anabaena flos-aquae. The result from the ultrastructure observed using SEM indicated that low pressure promoted the production of more extracellular polymeric substances (EPSs) compared to ambient conditions. The results implied that the low pressure environment of 50 kPa in a future lunar base would induce different effects on biological components in a CELSS, which must be considered during the course of designing a future lunar base. The results will be a reference for exploring the response of other biological components, such as plants, microbes, and animals, living in the life support system of a lunar base.

  9. Diagnostics of atmospheric pressure air plasmas

    International Nuclear Information System (INIS)

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

  10. Characterization of a steam plasma jet at atmospheric pressure

    International Nuclear Information System (INIS)

    An atmospheric steam plasma jet generated by an original dc water plasma torch is investigated using electrical and spectroscopic techniques. Because it directly uses the water used for cooling electrodes as the plasma-forming gas, the water plasma torch has high thermal efficiency and a compact structure. The operational features of the water plasma torch and the generation of the steam plasma jet are analyzed based on the temporal evolution of voltage, current and steam pressure in the arc chamber. The influence of the output characteristics of the power source, the fluctuation of the arc and current intensity on the unsteadiness of the steam plasma jet is studied. The restrike mode is identified as the fluctuation characteristic of the steam arc, which contributes significantly to the instabilities of the steam plasma jet. In addition, the emission spectroscopic technique is employed to diagnose the steam plasma. The axial distributions of plasma parameters in the steam plasma jet, such as gas temperature, excitation temperature and electron number density, are determined by the diatomic molecule OH fitting method, Boltzmann slope method and Hβ Stark broadening, respectively. The steam plasma jet at atmospheric pressure is found to be close to the local thermodynamic equilibrium (LTE) state by comparing the measured electron density with the threshold value of electron density for the LTE state. Moreover, based on the assumption of LTE, the axial distributions of reactive species in the steam plasma jet are estimated, which indicates that the steam plasma has high chemical activity.

  11. Detached eddy simulation of unsteady cavitation and pressure fluctuation around 3-D NACA66 hydrofoil

    Directory of Open Access Journals (Sweden)

    Zhang De-Sheng

    2015-01-01

    Full Text Available The unsteady cavitating flow and pressure fluctuation around the 3-D NACA66 hydrofoil were simulated and validated based on detached eddy simulation turbulence model and a homogeneous cavitation model. Numerical results show that detached eddy simulation can predict the evolution of cavity inception, sheet cavitation growth, cloud cavitation shedding, and breakup, as well as the pressure fluctuation on the surface of hydrofoil. The sheet cavitation growth, detachment, cloud cavitation shedding are responsible for the features of the pressure fluctuation.

  12. Research on atmospheric pressure plasma processing sewage

    Science.gov (United States)

    Song, Gui-cai; Na, Yan-xiang; Dong, Xiao-long; Sun, Xiao-liang

    2013-08-01

    The water pollution has become more and more serious with the industrial progress and social development, so it become a worldwide leading environmental management problem to human survival and personal health, therefore, countries are looking for the best solution. Generally speaking, in this paper the work has the following main achievements and innovation: (1) Developed a new plasma device--Plasma Water Bed. (2) At atmospheric pressure condition, use oxygen, nitrogen, argon and helium as work gas respectively, use fiber spectrometer to atmospheric pressure plasma discharge the emission spectrum of measurement, due to the different work gas producing active particle is different, so can understand discharge, different particle activity, in the treatment of wastewater, has the different degradation effects. (3) Methyl violet solution treatment by plasma water bed. Using plasma drafting make active particles and waste leachate role, observe the decolorization, measurement of ammonia nitrogen removal.

  13. A microwave pressure sounder. [for remote measurement of atmospheric pressure

    Science.gov (United States)

    Peckham, G. E.; Flower, D. A.

    1981-01-01

    A technique for the remote measurement of atmospheric surface pressure will be described. Such measurements could be made from a satellite in polar orbit and would cover many areas for which conventional meteorological data are not available. An active microwave instrument is used to measure the strength of return echoes from the ocean surface at a number of frequencies near the 60 GHz oxygen absorption band. Factors which affect the accuracy with which surface pressure can be deduced from these measurements will be discussed and an instrument designed to test the method by making measurements from an aircraft will be described.

  14. Special issue: diagnostics of atmospheric pressure microplasmas

    Science.gov (United States)

    Bruggeman, Peter; Czarnetzki, Uwe; Tachibana, Kunihide

    2013-11-01

    In recent decades, a strong revival of non-equilibrium atmospheric pressure plasma studies has developed in the form of microplasmas. Microplasmas have typical scales of 1 mm or less and offer a very exciting research direction in the field of plasma science and technology as the discharge physics can be considerably different due to high collisionality and the importance of plasma-surface interaction. These high-pressure small-scale plasmas have a diverse range of physical and chemical properties. This diversity coincides with various applications including light/UV sources [1], material processing [2], chemical analysis [3], material synthesis [4], electromagnetics [5], combustion [6] and even medicine [7]. At atmospheric pressure, large scale plasmas have the tendency to become unstable due to the high collision rates leading to enhanced heating and ionization compared to their low-pressure counterparts. As low-pressure plasmas typically operate in reactors with sizes of tens of centimetres, scaling up the pressure to atmospheric pressure the size of the plasma reduces to typical sizes below 1 mm. A natural approach of stabilizing atmospheric pressure plasmas is thus the use of microelectrode geometries. Traditionally microplasmas have been produced in confined geometries which allow one to stabilize dc excited discharges. This stabilization is intrinsically connected to the large surface-to-volume ratio which enhances heat transfer and losses of charged and excited species to the walls. Currently challenging boundaries are pushed by producing microcavity geometries with dimensions of the order of 1 µm [8]. The subject of this special issue, diagnostics of microplasmas, is motivated by the many challenges in microplasma diagnostics in view of the complex chemistry and strong spatial (and even temporal) gradients of species densities and plasma properties. Atmospheric pressure plasmas have a very long history dating back more than 100 years, with early work of

  15. Martian Atmospheric Pressure Static Charge Elimination Tool

    Science.gov (United States)

    Johansen, Michael R.

    2014-01-01

    A Martian pressure static charge elimination tool is currently in development in the Electrostatics and Surface Physics Laboratory (ESPL) at NASA's Kennedy Space Center. In standard Earth atmosphere conditions, static charge can be neutralized from an insulating surface using air ionizers. These air ionizers generate ions through corona breakdown. The Martian atmosphere is 7 Torr of mostly carbon dioxide, which makes it inherently difficult to use similar methods as those used for standard atmosphere static elimination tools. An initial prototype has been developed to show feasibility of static charge elimination at low pressure, using corona discharge. A needle point and thin wire loop are used as the corona generating electrodes. A photo of the test apparatus is shown below. Positive and negative high voltage pulses are sent to the needle point. This creates positive and negative ions that can be used for static charge neutralization. In a preliminary test, a floating metal plate was charged to approximately 600 volts under Martian atmospheric conditions. The static elimination tool was enabled and the voltage on the metal plate dropped rapidly to -100 volts. This test data is displayed below. Optimization is necessary to improve the electrostatic balance of the static elimination tool.

  16. Atmospheric pressure loading effects on Global Positioning System coordinate determinations

    Science.gov (United States)

    Vandam, Tonie M.; Blewitt, Geoffrey; Heflin, Michael B.

    1994-01-01

    Earth deformation signals caused by atmospheric pressure loading are detected in vertical position estimates at Global Positioning System (GPS) stations. Surface displacements due to changes in atmospheric pressure account for up to 24% of the total variance in the GPS height estimates. The detected loading signals are larger at higher latitudes where pressure variations are greatest; the largest effect is observed at Fairbanks, Alaska (latitude 65 deg), with a signal root mean square (RMS) of 5 mm. Out of 19 continuously operating GPS sites (with a mean of 281 daily solutions per site), 18 show a positive correlation between the GPS vertical estimates and the modeled loading displacements. Accounting for loading reduces the variance of the vertical station positions on 12 of the 19 sites investigated. Removing the modeled pressure loading from GPS determinations of baseline length for baselines longer than 6000 km reduces the variance on 73 of the 117 baselines investigated. The slight increase in variance for some of the sites and baselines is consistent with expected statistical fluctuations. The results from most stations are consistent with approximately 65% of the modeled pressure load being found in the GPS vertical position measurements. Removing an annual signal from both the measured heights and the modeled load time series leaves this value unchanged. The source of the remaining discrepancy between the modeled and observed loading signal may be the result of (1) anisotropic effects in the Earth's loading response, (2) errors in GPS estimates of tropospheric delay, (3) errors in the surface pressure data, or (4) annual signals in the time series of loading and station heights. In addition, we find that using site dependent coefficients, determined by fitting local pressure to the modeled radial displacements, reduces the variance of the measured station heights as well as or better than using the global convolution sum.

  17. MINING PROCESS AND PRODUCT INFORMATION FROM PRESSURE FLUCTUATIONS WITHIN A FUEL PARTICLE COATER

    Energy Technology Data Exchange (ETDEWEB)

    Douglas W. Marshall

    2009-10-01

    The Next Generation Nuclear Power/Advanced Gas Reactor (NGNP/AGR) Fuel Development and Qualification Program included the design, installation, and testing of a 6-inch diameter nuclear fuel particle coater to demonstrate quality TRISO fuel production on a small industrial scale. Scale-up from the laboratory-scale coater faced challenges associated with an increase in the kernel charge mass, kernel diameter, and a redesign of the gas distributor to achieve adequate fluidization throughout the deposition of the four TRISO coating layers. TRISO coatings are applied at very high temperatures in atmospheres of dense particulate clouds, corrosive gases, and hydrogen concentrations over 45% by volume. The severe environment, stringent product and process requirements, and the fragility of partially-formed coatings limit the insertion of probes or instruments into the coater vessel during operation. Pressure instrumentation were installed on the gas inlet line and exhaust line of the 6-inch coater to monitor the bed differential pressure and internal pressure fluctuations emanating from the fuel bed as a result of bed and gas “bubble” movement. These instruments are external to the particle bed and provide a glimpse into the dynamics of fuel particle bed during the coating process and data that could be used to help ascertain the adequacy of fluidization and, potentially, the dominant fluidization regimes. Pressure fluctuation and differential pressure data are not presently useful as process control instruments, but data suggest a link between the pressure signal structure and some measurable product attributes that could be exploited to get an early estimate of the attribute values.

  18. MINING PROCESS AND PRODUCT INFORMATION FROM PRESSURE FLUCTUATIONS WITHIN A FUEL PARTICLE COATER

    Energy Technology Data Exchange (ETDEWEB)

    Douglas W. Marshall; Charles M. Barnes

    2008-09-01

    The Next Generation Nuclear Power (NGNP) Fuel Development and Qualification Program included the design, installation, and testing of a 6-inch diameter nuclear fuel particle coater to demonstrate quality TRISO fuel production on a small industrial scale. Scale-up from the laboratory-scale coater faced challenges associated with an increase in the kernel charge mass, kernel diameter, and a redesign of the gas distributor to achieve adequate fluidization throughout the deposition of the four TRISO coating layers. TRISO coatings are applied at very high temperatures in atmospheres of dense particulate clouds, corrosive gases, and hydrogen concentrations over 45% by volume. The severe environment, stringent product and process requirements, and the fragility of partially-formed coatings limit the insertion of probes or instruments into the coater vessel during operation. Pressure instrumentation were installed on the gas inlet line and exhaust line of the 6-inch coater to monitor the bed differential pressure and internal pressure fluctuations emanating from the fuel bed as a result of bed and gas “bubble” movement. These instruments are external to the particle bed and provide a glimpse into the dynamics of fuel particle bed during the coating process and data that could be used to help ascertain the adequacy of fluidization and, potentially, the dominant fluidization regimes. Pressure fluctuation and differential pressure data are not presently useful as process control instruments, but data suggest a link between the pressure signal structure and some measurable product attributes that could be exploited to get an early estimate of the attribute values.

  19. Wind-tunnel investigation of surface-pressure fluctuations associated with aircraft buffet

    Science.gov (United States)

    Riddle, D. W.

    1975-01-01

    Fluctuating pressures and forces that cause aircraft buffeting have been measured on a semispan rigid-wing model of a typical variable-sweep fighter-type aircraft at transonic speeds. The rms spectral and spatial correlation characteristics of wing fluctuating pressures, fluctuating pressure summations, and structural responses are presented and discussed for a Mach number of 0.85, wing sweep angles of 26 and 72 deg, and angles of attack up to 12 deg. The fluctuating pressure characteristics beneath wing shock waves and leading-edge vortices and in regions of attached and separated flows are presented. Results indicate that: (1) the mean and fluctuating static pressure characteristics are related; (2) a circulation oscillation exists for attached flow conditions below buffet onset; and (3) a significant coupling exists between the wing shock-wave oscillation and the wing first torsional mode when shock-induced separation is present.

  20. Fluctuations in Precambrian atmospheric oxygenation recorded by chromium isotopes

    Science.gov (United States)

    Frei, Robert; Gaucher, Claudio; Poulton, Simon W.; Canfield, Don E.

    2009-09-01

    Geochemical data suggest that oxygenation of the Earth's atmosphere occurred in two broad steps. The first rise in atmospheric oxygen is thought to have occurred between ~2.45 and 2.2Gyr ago, leading to a significant increase in atmospheric oxygen concentrations and concomitant oxygenation of the shallow surface ocean. The second increase in atmospheric oxygen appears to have taken place in distinct stages during the late Neoproterozoic era (~800-542Myr ago), ultimately leading to oxygenation of the deep ocean ~580Myr ago, but details of the evolution of atmospheric oxygenation remain uncertain. Here we use chromium (Cr) stable isotopes from banded iron formations (BIFs) to track the presence of Cr(VI) in Precambrian oceans, providing a time-resolved picture of the oxygenation history of the Earth's atmosphere-hydrosphere system. The geochemical behaviour of Cr is highly sensitive to the redox state of the surface environment because oxidative weathering processes produce the oxidized hexavalent [Cr(VI)] form. Oxidation of reduced trivalent [Cr(III)] chromium on land is accompanied by an isotopic fractionation, leading to enrichment of the mobile hexavalent form in the heavier isotope. Our fractionated Cr isotope data indicate the accumulation of Cr(VI) in ocean surface waters ~2.8 to 2.6Gyr ago and a likely transient elevation in atmospheric and surface ocean oxygenation before the first great rise of oxygen 2.45-2.2Gyr ago (the Great Oxidation Event). In ~1.88-Gyr-old BIFs we find that Cr isotopes are not fractionated, indicating a decline in atmospheric oxygen. Our findings suggest that the Great Oxidation Event did not lead to a unidirectional stepwise increase in atmospheric oxygen. In the late Neoproterozoic, we observe strong positive fractionations in Cr isotopes (δ53Cr up to +4.9‰), providing independent support for increased surface oxygenation at that time, which may have stimulated rapid evolution of macroscopic multicellular life.

  1. Atmospheric Pressure Plasma Processing for Polymer Adhesion: A Review

    DEFF Research Database (Denmark)

    Kusano, Yukihiro

    2014-01-01

    Atmospheric pressure plasma processing has attracted significant interests over decades due to its usefulness and a variety of applications. Adhesion improvement of polymer surfaces is among the most important applications of atmospheric pressure plasma treatment. Reflecting recent significant...... development of the atmospheric pressure plasma processing, this work presents its fundamental aspects, applications, and characterization techniques relevant to adhesion....

  2. New development of atmospheric pressure plasma polishing

    Institute of Scientific and Technical Information of China (English)

    Bo Wang; Jufan Zhang; Shen Dong

    2009-01-01

    Atmospheric pressure plasma polishing (APPP) is a precision machining technology used for manufacturing high quality optical surfaces. The changes of surface modulus and hardness after machining prove the distinct improvement of surface mechanical properties. The demonstrated decrease of surfacc residual stresses testifies the removal of the former deformation layer.And the surface topographies under atomic force microscope (AFM) and scanning electron microscope (SEM) indicate obvious amelioration of the surface status,showing that the 0.926-nm average surface roughness has been achieved.

  3. Nanocapillary Atmospheric Pressure Plasma Jet: A Tool for Ultrafine Maskless Surface Modification at Atmospheric Pressure.

    Science.gov (United States)

    Motrescu, Iuliana; Nagatsu, Masaaki

    2016-05-18

    With respect to microsized surface functionalization techniques we proposed the use of a maskless, versatile, simple tool, represented by a nano- or microcapillary atmospheric pressure plasma jet for producing microsized controlled etching, chemical vapor deposition, and chemical modification patterns on polymeric surfaces. In this work we show the possibility of size-controlled surface amination, and we discuss it as a function of different processing parameters. Moreover, we prove the successful connection of labeled sugar chains on the functionalized microscale patterns, indicating the possibility to use ultrafine capillary atmospheric pressure plasma jets as versatile tools for biosensing, tissue engineering, and related biomedical applications.

  4. Fluctuations in Precambrian atmospheric oxygenation recorded by chromium isotopes.

    Science.gov (United States)

    Frei, Robert; Gaucher, Claudio; Poulton, Simon W; Canfield, Don E

    2009-09-10

    Geochemical data suggest that oxygenation of the Earth's atmosphere occurred in two broad steps. The first rise in atmospheric oxygen is thought to have occurred between approximately 2.45 and 2.2 Gyr ago, leading to a significant increase in atmospheric oxygen concentrations and concomitant oxygenation of the shallow surface ocean. The second increase in atmospheric oxygen appears to have taken place in distinct stages during the late Neoproterozoic era ( approximately 800-542 Myr ago), ultimately leading to oxygenation of the deep ocean approximately 580 Myr ago, but details of the evolution of atmospheric oxygenation remain uncertain. Here we use chromium (Cr) stable isotopes from banded iron formations (BIFs) to track the presence of Cr(VI) in Precambrian oceans, providing a time-resolved picture of the oxygenation history of the Earth's atmosphere-hydrosphere system. The geochemical behaviour of Cr is highly sensitive to the redox state of the surface environment because oxidative weathering processes produce the oxidized hexavalent [Cr(VI)] form. Oxidation of reduced trivalent [Cr(III)] chromium on land is accompanied by an isotopic fractionation, leading to enrichment of the mobile hexavalent form in the heavier isotope. Our fractionated Cr isotope data indicate the accumulation of Cr(VI) in ocean surface waters approximately 2.8 to 2.6 Gyr ago and a likely transient elevation in atmospheric and surface ocean oxygenation before the first great rise of oxygen 2.45-2.2 Gyr ago (the Great Oxidation Event). In approximately 1.88-Gyr-old BIFs we find that Cr isotopes are not fractionated, indicating a decline in atmospheric oxygen. Our findings suggest that the Great Oxidation Event did not lead to a unidirectional stepwise increase in atmospheric oxygen. In the late Neoproterozoic, we observe strong positive fractionations in Cr isotopes (delta(53)Cr up to +4.9 per thousand), providing independent support for increased surface oxygenation at that time, which may

  5. Does respiratory sinus arrhythmia serve a buffering role for diastolic pressure fluctuations?

    OpenAIRE

    Tan, Can Ozan; Taylor, J. Andrew

    2010-01-01

    Though many consider the magnitude of respiratory sinus arrhythmia as an index of cardiac vagal control, its physiological origins remain unclear. One influential model postulates that the systolic pressure rise within a given beat stimulates the baroreflex arc to adjust the following heart period such that diastolic pressure is “stabilized” and hence displays lesser fluctuation. Accordingly, the magnitude of diastolic pressure fluctuations with respiration should change reciprocally after au...

  6. Enhancement in Surface Atmospheric Pressure Variability Associated with a Major Geomagnetic Storm

    CERN Document Server

    Selvam, A M; Athale, S U; Tinmaker, M I R

    1998-01-01

    Observational studies indicate that there is a close association between geomagnetic storm and meteorological parameters. Geomagnetic field lines follow closely the isobars of surface pressure . A Physical mechanism linking upper atmospheric geomagnetic storm disturbances with tropospheric weather has been proposed by the author and her group where it is postulated that vertical mixing by turbulent eddy fluctuations results in the net transport upward of positive charges originating from lower levels accompanied simultaneously by downward flow of negative charges from higher levels. The present study reports enhancement of high frequency (<15 days period) fluctuations in daily surface pressure during March 1989 in association with major geomagnetic storm (Ap index = 246) on 13 march 1989.

  7. Climate variability and atmospheric teleconnection from satellite observed cloud fluctuations

    Science.gov (United States)

    Lau, K. M.; Chan, P. H.

    1983-01-01

    To investigate the low-frequency variability of the large-scale circulation over the tropics and its relationship with different regions of the globe, statistics of cloud fluctuations, as inferred from outgoing longwave radiation (OLR) are used. The data consists of seven years of global OLR in a 2.5 x 2.5-deg grid derived from NOAA polar orbiting satellite observations. The time series of area-averaged monthly deviation from the seven-year mean of OLR over an equatorial Central Pacific region is presented. It is shown that positive and negative deviations reflect local drier and wetter than normal conditions, respectively. Consideration is given to teleconnection based on the Central Pacific variations and to southern oscillation contributions.

  8. Response of cyanobacteria to low atmosphere pressure

    Science.gov (United States)

    Qin, Lifeng; Ai, Weidang; Guo, Shuangsheng; Tang, Yongkang; Yu, Qingni; Shen, Yunze; Ren, Jin

    Maintaining a low pressure environment would reduce the technological complexity and constructed cost of future lunar base. To estimate the effect of hypobaric of controlled ecological life support system in lunar base on terrestrial life, cyanobacteria was used as the model to exam the response of growth, morphology, physiology to it. The decrease of atmosphere pressure from 100 KPa to 50 KPa reducing the growth rates of Microcystis aeruginosa, Merismopedia.sp, Anabaena sp. PCC 7120, Anabaena Hos-aquae, the chlorophyll a content in Microcystis aeruginosa, Merismopedia.sp, Anabaena Hos-aquae, the carotenoid content in Microcystis aeruginosa, Merismopedia.sp and Anabaena sp. PCC 7120, the phycocyanin content in Microcystis aeruginosa. This study explored the biological characteristics of the cyanobacteria under low pressure condition, which aimed at understanding the response of the earth's life to environment for the future moon base, the results enrich the research contents of the lunar biology and may be referred for the research of other terrestrial life, such as human, plant, microbe and animal living in life support system of lunar base.

  9. Variation in the Earth's Angular Velocity Resulting from Fluctuations in Atmospheric and Oceanic Circulation

    OpenAIRE

    Munk, W. H.; Miller, R. L.

    2011-01-01

    Fluctuations in the circulation of the atmosphere are associated with very small anomalies in the angular velocity of the earth. The seasonal component of these anomalies has been computed from weather maps, and is found to agree, with respect to magnitude and phase, with anomalies first reported by STOKYO in 1936 on the basis of astronomic observations. The effects of fluctuations in the oceanic circulation, and of shifting of air and water masses, have been estimated to account for not more...

  10. Fluctuating surface pressure measurements on USB wing using two types of transducers

    Science.gov (United States)

    Reed, J. B.

    1975-01-01

    Measurements of the fluctuating pressures on the wing surface of an upper-surface-blown powered-lift model and a JT15 engine were obtained using two types of pressure transducers. The pressures were measured using overall-fluctuating pressures and power spectral density analyses for various thrust settings and two jet impingement angles. Comparison of the data from the two transducers indicate that similar results are obtained in the lower frequency ranges for both transducers. The data also indicate that for this configuration, the highest pressure levels occur at frequencies below 2000 Hz.

  11. Experimental study on pore pressure in rock-soil slope during reservoir water level fluctuation

    Institute of Scientific and Technical Information of China (English)

    LIU; Yuewu; CHEN; Huixin; LIU; Qingquan; GONG; Xin; ZHANG

    2005-01-01

    A test system was developed for measuring the pore pressure in porous media, and a new model was devised for the pore pressure testing in both saturated and unsaturated rock-soil. Laboratory experiments were carried out to determine the pore pressure during water level fluctuation. The variations of transient pore pressure vs. time at different locations of the simulated rock-soil system were acquired and processed, and meanwhile the deformation and failure of the model are observed. The experiment results show that whether the porous media are saturated or not, the transient pore pressure is mainly dependent on the water level fluctuation, and coupled with the variation of the stress field.

  12. Study on temperature and flow fluctuation phenomena in pressurizer spray pipe of PWR

    International Nuclear Information System (INIS)

    Thermal fatigue cracking may initiate in pressurizer spray pipe of PWR where oscillations of water surface may exist. In order to clarify the flow and thermal conditions in the pressurizer spray pipe, an experiment was conducted for a steam-water flow using a mock-up pressurizer spray pipe. It was shown that the fluid temperature fluctuations were not caused by the waves on the water surface, but were caused by temperature fluctuations in water layer below the interface. Visualization tests were conducted to investigate the detail mechanism of the fluctuation using the rectangular pipe made of polycarbonate resin. The clouds were observed below the steam-water interface and it seemed like an internal wave. It was shown that the maximum of the temperature fluctuations increases with increase the steam-water temperature difference and the prominent frequency of the fluctuations was nearly equal to 0.1Hz∼1Hz. (author)

  13. Pore Pressure Response to Groundwater Fluctuations in Saturated Double-Layered Soil

    OpenAIRE

    Hongwei Ying; Lisha Zhang; Kanghe Xie; Dazhong Huang

    2015-01-01

    Analytical solutions are developed for one-dimensional consolidation of double-layered saturated soil subjected to groundwater fluctuations. The solutions are derived by an explicit mathematical procedure using Duhamel’s theorem in conjunction with a Fourier series, when groundwater fluctuation is described by a general time-dependent function and assumed to be the pore water pressure variations at the upper boundary. Taking as an example the harmonic groundwater fluctuation, the relevant res...

  14. Structure formation of atmospheric pressure discharge

    Science.gov (United States)

    Medvedev, Alexey E.

    2016-02-01

    In this paper it is shown, by analyzing the results of experimental studies, that the outer boundary of the atmospheric pressure discharge pinch is determined by the condition of equality of plasma flows based on the thermal and electric field energy. In most cases, the number of charged particles coming from near-electrode zones is sufficient to compensate for losses in the discharge bulk. At large currents and enhanced heating, plasma is in the diffusion mode of losses, with recombination of charged particles at the pinch boundary. 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.

  15. PROPER ORTHOGONAL DECOMPOSITION AND LOW-DIMENSIONAL APPROXIMATION OF WALL PRESSURE FLUCTUATION

    Institute of Scientific and Technical Information of China (English)

    LIU Shi-he; DUAN Hong-dong; LU Jing

    2004-01-01

    Wall pressure fluctuation is one of the source terms which result in the vibration of hydraulic structures. To consider both the space and time correlation of the pressure field, the method of proper orthogonal decomposition and low-dimensional approximation were used here to describe the pressure signals of the turbulent boundary layer, the apron of the stilling pond and the vertically impinging jet.

  16. Special issue: diagnostics of atmospheric pressure microplasmas

    Science.gov (United States)

    Bruggeman, Peter; Czarnetzki, Uwe; Tachibana, Kunihide

    2013-11-01

    In recent decades, a strong revival of non-equilibrium atmospheric pressure plasma studies has developed in the form of microplasmas. Microplasmas have typical scales of 1 mm or less and offer a very exciting research direction in the field of plasma science and technology as the discharge physics can be considerably different due to high collisionality and the importance of plasma-surface interaction. These high-pressure small-scale plasmas have a diverse range of physical and chemical properties. This diversity coincides with various applications including light/UV sources [1], material processing [2], chemical analysis [3], material synthesis [4], electromagnetics [5], combustion [6] and even medicine [7]. At atmospheric pressure, large scale plasmas have the tendency to become unstable due to the high collision rates leading to enhanced heating and ionization compared to their low-pressure counterparts. As low-pressure plasmas typically operate in reactors with sizes of tens of centimetres, scaling up the pressure to atmospheric pressure the size of the plasma reduces to typical sizes below 1 mm. A natural approach of stabilizing atmospheric pressure plasmas is thus the use of microelectrode geometries. Traditionally microplasmas have been produced in confined geometries which allow one to stabilize dc excited discharges. This stabilization is intrinsically connected to the large surface-to-volume ratio which enhances heat transfer and losses of charged and excited species to the walls. Currently challenging boundaries are pushed by producing microcavity geometries with dimensions of the order of 1 µm [8]. The subject of this special issue, diagnostics of microplasmas, is motivated by the many challenges in microplasma diagnostics in view of the complex chemistry and strong spatial (and even temporal) gradients of species densities and plasma properties. Atmospheric pressure plasmas have a very long history dating back more than 100 years, with early work of

  17. Numerical Investigation of Pressure Fluctuation Characteristics in a Centrifugal Pump with Variable Axial Clearance

    Directory of Open Access Journals (Sweden)

    Lei Cao

    2016-01-01

    Full Text Available Clearance flows in the sidewall gaps of centrifugal pumps are unsteady as well as main flows in the volute casing and impeller, which may cause vibration and noise, and the corresponding pressure fluctuations are related to the axial clearance size. In this paper, unsteady numerical simulations were conducted to predict the unsteady flows within the entire flow passage of a centrifugal pump operating in the design condition. Pressure fluctuation characteristics in the volute casing, impeller, and sidewall gaps were investigated with three axial clearance sizes. Results show that an axial clearance variation affects the pressure fluctuation characteristics in each flow domain by different degree. The greatest pressure fluctuation occurs at the blade pressure surface and is almost not influenced by the axial clearance variation which has a certainly effect on the pressure fluctuation characteristics around the tongue. The maximum pressure fluctuation amplitude in the sidewall gaps is larger than that in the volute casing, and different spectrum characteristics show up in the three models due to the interaction between the clearance flow and the main flow as well as the rotor-stator interaction. Therefore, clearance flow should be taken into consideration in the hydraulic design of centrifugal pumps.

  18. Numerical prediction of pressure fluctuations in a prototype pump turbine base on PANS methods

    Science.gov (United States)

    Liu, J. T.; Li, Y.; Gao, Y.; Hu, Q.; Wu, Y. L.

    2016-05-01

    Unsteady flow and pressure fluctuations within a prototypel pump turbine are numerically studied using a nonlinear Partial Averaged Navier Stokes (PANS) model. Pump turbine operating at different conditions with guide vanes opening angle 6° is simulated. Results revealed that the predictions of performance and relative peak-to-peak amplitude by PANS approach agree well with the experimental data. The amplitude of the pressure fluctuation in the vaneless space at turbine mode on a “S” curve increases with the decrease of the flow rate, and it has maximum value when it runs close to runaway line at turbine braking mode. The amplitude of the pressure fluctuation in the vaneless space at turbine braking mode on a “S” curve decreases with the reduce of the flow rate. The above high pressure fluctuations should be avoided during the design of pump turbines especially those operating at high-head condition.

  19. Spectral Measurement of Atmospheric Pressure Plasma by Means of Digital Camera

    Institute of Scientific and Technical Information of China (English)

    葛袁静; 张广秋; 刘益民; 赵志发

    2002-01-01

    A digital camera measuring system has been used successfully to measure the space fluctuation behaviors of Induced Dielectric Barrier Discharge (IDBD) plasma at atmospheric pressure. The experimental results showed that: (1) The uniformity of electron temperature in space depends on discharge condition and structure of web electrode. For a certain web electrode the higher the discharge voltage is, the more uniform distribution of electron temperature in space will be. For a certain discharge the finer and denser the holes on web electrode are, the more uniform distribution of electron temperature in space will be (2). Digital camera is an available equipment to measure some behaviors of the plasma working at atmospheric pressure.

  20. Spectral measurement of atmospheric pressure plasma by means of digital camera

    International Nuclear Information System (INIS)

    A digital camera measuring system has been used successfully to measure the space fluctuation behaviors of Induced Dielectric Barrier Discharge (IDBD) plasma at atmospheric pressure. The experimental results showed that: (1) The uniformity of electron temperature in space depends on discharge condition and structure of web electrode. For a certain web electrode the higher the discharge voltage is, the more uniform distribution of electron temperature in space will be. For a certain discharge the finer and denser the holes on web electrode are, the more uniform distribution of electron temperature in space will be. (2) Digital camera is an available equipment to measure some behaviors of the plasma working at atmospheric pressure

  1. Atmospheric pressure variations and abdominal aortic aneurysm rupture.

    LENUS (Irish Health Repository)

    Killeen, S D

    2012-02-03

    BACKGROUND: Ruptured abdominal aortic aneurysm (RAAA) presents with increased frequency in the winter and spring months. Seasonal changes in atmospheric pressure mirrors this pattern. AIM: To establish if there was a seasonal variation in the occurrence of RAAA and to determine if there was any association with atmospheric pressure changes. METHODS: A retrospective cohort-based study was performed. Daily atmospheric pressure readings for the region were obtained. RESULTS: There was a statistically significant monthly variation in RAAA presentation with 107 cases (52.5%) occurring from November to March. The monthly number of RAAA and the mean atmospheric pressure in the previous month were inversely related (r = -0.752, r (2) = 0.566, P = 0.03), and there was significantly greater daily atmospheric pressure variability on days when patients with RAAA were admitted. CONCLUSION: These findings suggest a relationship between atmospheric pressure and RAAA.

  2. Numerical investigation of pressure fluctuation for a mixed flow pump impeller and vanes diffuser

    International Nuclear Information System (INIS)

    In order to investigate the effect of rotor-stator interaction between impeller and vanes diffuser on the pressure fluctuation of a mixed flow pump, the pressure fluctuations at three representative locations under the design condition are obtained, unsteady flow feature is analyzed by RNG κ–ε turbulence model with sliding mesh technology. Experimental results show that there is the positive slope of head-flow performance curve under 0.6 and 0.85 design condition, which unsteady prediction is not seen based on Reynolds-averaged equation. The pressure fluctuation is analysed by the characteristics of amplitude and frequency, the amplitude of pressure fluctuation, which the maximum is in the rim of impeller outlet and the minimum is in the hub of impeller inlet, is gradually increasing along the hub to rim, the amplitude of monitoring points located the rim of impeller inlet and impeller and vanes diffuser is two times than the hub. The amplitude of pressure fluctuation, which the maximum is in the vanes diffuser outlet, is gradually increasing along impeller inlet to vanes diffuser outlet, while there is a low-frequency pressure fluctuation caused by unsteady flow in the vanes diffuser.

  3. Numerical simulation of pressure fluctuations in a large Francis turbine runner

    Science.gov (United States)

    Wang, Fujun; Liao, Cuilin; Tang, Xuelin

    2012-11-01

    The pressure fluctuation caused by unsteady flow in runner is one of the main reasons of vibration for a large Francis hydraulic turbine. It directly affects the steady operation of the hydraulic turbine unit. The existing research of the pressure fluctuation in hydraulic turbine mainly focuses on the unsteady flow in draft tube. Accurate distribution of pressure fluctuations inside a runner is not very clear. In this paper, the numerical method for predicting the pressure fluctuations in runner is investigated and the numerical simulation is performed for a large Francis hydraulic turbine. It is proved that the combination of shear-stress transport(SST) k- ω turbulence model and pressure-implicit with splitting of operators(PISO) algorithm could give more reliable prediction of pressure fluctuations in runner. The frequencies of pressure fluctuations in runner are affected by the flow in guide vane and the flow in draft tube. The first dominant frequency is significantly determined by the flow in draft tube, especially at part load condition. This frequency is approximately equal to one-third of the runner rotating frequency. The evident second dominant frequency is exactly equal to the guide vane passing frequency. The peak-to-peak amplitudes of pressure fluctuations in runner at small guide vane open angle are larger than that at large open angle at the same operating head. The amplitudes at points on blade pressure surface are generally greater than that on suction surface. The research results could be used to direct the hydraulic design and operation stability improvement of a large Francis hydraulic turbine.

  4. PIV-based pressure fluctuations in the turbulent boundary layer

    Science.gov (United States)

    Ghaemi, Sina; Ragni, Daniele; Scarano, Fulvio

    2012-12-01

    The unsteady pressure field is obtained from time-resolved tomographic particle image velocimetry (Tomo-PIV) measurement within a fully developed turbulent boundary layer at free stream velocity of U ∞ = 9.3 m/s and Reθ = 2,400. The pressure field is evaluated from the velocity fields measured by Tomo-PIV at 10 kHz invoking the momentum equation for unsteady incompressible flows. The spatial integration of the pressure gradient is conducted by solving the Poisson pressure equation with fixed boundary conditions at the outer edge of the boundary layer. The PIV-based evaluation of the pressure field is validated against simultaneous surface pressure measurement using calibrated condenser microphones mounted behind a pinhole orifice. The comparison shows agreement between the two pressure signals obtained from the Tomo-PIV and the microphones with a cross-correlation coefficient of 0.6 while their power spectral densities (PSD) overlap up to 3 kHz. The impact of several parameters governing the pressure evaluation from the PIV data is evaluated. The use of the Tomo-PIV system with the application of three-dimensional momentum equation shows higher accuracy compared to the planar version of the technique. The results show that the evaluation of the wall pressure can be conducted using a domain as small as half the boundary layer thickness (0.5δ99) in both the streamwise and the wall normal directions. The combination of a correlation sliding-average technique, the Lagrangian approach to the evaluation of the material derivative and the planar integration of the Poisson pressure equation results in the best agreement with the pressure measurement of the surface microphones.

  5. A New Atmospheric Pressure Microwave Plasma Source (APMPS)

    Institute of Scientific and Technical Information of China (English)

    LIU Liang; ZHANG Guixin; LI Yinan; ZHU Zhijie; WANG Xinxin; LUO Chengmu

    2008-01-01

    An atmospheric pressure microwave plasma source (APMPS) that can generate a large volume of plasma at an atmospheric pressure has been developed at Tsinghua University. This paper presents the design of this APMPS, the theoretical consideration of microwave plasma ignition and the simulation results, including the distributions of the electric field and power density inside the cavity as well as the accuracy of the simulation results. In addition, a method of producing an atmospheric pressure microwave plasma and some relevant observations of the plasma are also provided. It. is expected that this research would be useful for further developing atmospheric pressure microwave plasma sources and expanding the scope of their applications.

  6. Piston slap induced pressure fluctuation in the water coolant passage of an internal combustion engine

    Science.gov (United States)

    Ohta, Kazuhide; Wang, Xiaoyu; Saeki, Atsushi

    2016-02-01

    Liner cavitation is caused by water pressure fluctuation in the water coolant passage (WCP). When the negative pressure falls below the saturated vapor pressure, the impulsive pressure following the implosion of cavitation bubbles causes cavitation erosion of the wet cylinder liner surface. The present work establishes a numerical model for structural-acoustic coupling between the crankcase and the acoustic field in the WCP considering their dynamic characteristics. The coupling effect is evaluated through mutual interaction terms that are calculated from the mode shapes of the acoustic field and of the crankcase vibration on the boundary. Water pressure fluctuations in the WCP under the action of piston slap forces are predicted and the contributions of the uncoupled mode shapes of the crankcase and the acoustic field to the pressure waveform are analyzed. The influence of sound speed variations on the water pressure response is discussed, as well as the pressure on the thrust sides of the four cylinders.

  7. Airfoil Trailing Edge Noise Generation and Its Surface Pressure Fluctuation

    DEFF Research Database (Denmark)

    Zhu, Wei Jun; Shen, Wen Zhong

    2015-01-01

    where the time history pressure data are recorded by the surface pressure microphones. After the flow-field is stabilized, the generated noise from the airfoil Trailing Edge (TE) is predicted using the acoustic analogy solver, where the results from LES are the input. It is found that there is a strong...

  8. Atmospheric Pressure Glow Discharge with Liquid Electrode

    Science.gov (United States)

    Tochikubo, Fumiyoshi

    2013-09-01

    Nonthermal atmospheric pressure plasmas in contact with liquid are widely studied aiming variety of plasma applications. DC glow discharge with liquid electrode is an easy method to obtain simple and stable plasma-liquid interface. When we focus attention on liquid-phase reaction, the discharge system is considered as electrolysis with plasma electrode. The plasma electrode will supply electrons and positive ions to the liquid surface in a different way from the conventional metal electrode. However, the phenomena at plasma-liquid interface have not been understood well. In this work, we studied physical and chemical effect in liquid induced by dc atmospheric pressure glow discharge with liquid electrode. The experiment was carried out using H-shaped Hoffman electrolysis apparatus filled with electrolyte, to separate the anodic and cathodic reactions. Two nozzle electrodes made of stainless steel are set about 2 mm above the liquid surface. By applying a dc voltage between the nozzle electrodes, dc glow discharges as plasma electrodes are generated in contact with liquid. As electrolyte, we used aqueous solutions of NaCl, Na2SO4, AgNO3 and HAuCl4. AgNO3 and HAuCl4 are to discuss the reduction process of metal ions for synthesis of nanoparticles (NPs). OH radical generation yield in liquid was measured by chemical probe method using terephthalic acid. Discharge-induced liquid flow was visualized by Schlieren method. Electron irradiation to liquid surface (plasma cathode) generated OH- and OH radical in liquid while positive ion irradiation (plasma anode) generated H+ and OH radical. The generation efficiency of OH radical was better with plasma anode. Both Ag NPs in AgNO3 and Au NPs in HAuCl4 were synthesized with plasma cathode while only Au NPs were generated with plasma anode. Possible reaction process is qualitatively discussed. The discharge-induced liquid flow such as convection pattern was strongly influenced by the gas flow on the liquid surface. This work

  9. Distinguishing Thermal Fluctuations from Instrumental Error for High Pressure Charged Gas

    CERN Document Server

    Bedroya, Alek

    2016-01-01

    Thermodynamic parameters such as temperature and pressure could be defined from the statistical behavior of the system. Therefore, always there exists a natural thermal fluctuations in these parameters which leads to fluctuations in experimental data. Analyzing these data fluctuations are very useful in studying systems in their critical points such as the phase transition points. But unfortunately it is hard to distinguish these fluctuations from the fluctuations due to the instrumental errors. In this article we have offered a method by which an experimenter can separate these fluctuations from each other. Additionally we have introduced a new computational idea which reduces the simulation time considerably. We have used the Euler algorithm which generally does not hold the internal energy conserved. However we have used this fact as a positive chance which allows us to travel in the phase space and reach different energies in much less time. This would be an acceptable only if system does spend enough tim...

  10. Wind-induced internal pressure fluctuations of structure with single windward opening

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A frequency domain method for estimating wind-induced fluctuating internal pressure of structure with single windward opening is presented in this paper and wind tunnel tests were carried out to verify the theory. The nonlinear differential equation of intemal pressure dynamics and iteration algorithm were applied to calculate fluctuating internal pressure and time domain analysis was used to verify the accuracy of the proposed method. A simplified estimation method is also provided and its scope of application is clarified. The mechanism of internal pressure fluctuation is obtained by using the proposed method in the frequency domain and a new equivalent opening ratio is defined to evaluate internal pressure fluctuation. A series of low-rise building models with various openings and internal volumes were designed for wind tunnel tests with results agreeing well with analytical results. It is shown that the proposed frequency domain method based on Gaussian distribution of internal pressure fluctuations can be applied to predict the RMS internal pressure coefficient with adequate accuracy for any opening dimensions,while the simplified method can only be used for structure with single dominant opening. Helmholtz resonance is likely to occur when the equivalent opening ratio is adequately high, and controlling individual opening dimension is an effective strategy for avoiding Helmholtz resonance in engineering.

  11. Atmospheric pressure changes and unexplained variability in INR measurements.

    Science.gov (United States)

    Ernst, Michael E; Shaw, Robert F; Ernst, Erika J; Alexander, Bruce; Kaboli, Peter J

    2009-06-01

    Changes in atmospheric pressure may influence hepatic blood flow and drug metabolism. Anecdotal experience suggests international normalized ratio (INR) variability may be temporally related to significant atmospheric pressure changes. We investigated this potential association in a large sample of patients with multiple INRs. This is a retrospective review of outpatient anticoagulation records from the Iowa City Veteran's Affairs Medical Center and affiliated outpatient clinics from October 1999 to July 2007. All patients, receiving at least one prescription for warfarin and INR at least 30 days or more from the date of the first warfarin prescription, were identified. INRs during periods of hospitalization and vitamin K use were excluded. Proximity analysis using geocoding of ZIP codes of identified patients to the nearest National Oceanic and Atmospheric Administration station was performed to assign atmospheric pressure with INR. Spearman's Rho and Pearson's correlation were used to evaluate atmospheric pressure and INR. Unique patients (1441) with 45 187 INRs were analyzed. When limited to nontherapeutic INRs following a previously therapeutic INR (1121 unique patients/5256 INRs), a small but clinically insignificant association between delta INR and delta atmospheric pressure was observed (r = -0.025; P = 0.038), but not for actual INR and atmospheric pressure (P = 0.06). Delta atmospheric pressure demonstrated greater variation during fall/winter months compared with spring/summer (0.23 vs. 0.15 inHg; P atmospheric pressure changes and INR variability. These findings refute the anecdotal experience seen in our anticoagulation clinic.

  12. Numerical simulation on pressure fluctuation of reactor coolant pump with complex impeller based on CFD technique

    International Nuclear Information System (INIS)

    In order to decrease pressure fluctuation of the reactor coolant pump under different conditions, three different inlet diameters of short blade of the reactor coolant pump were compared using numerical simulation, and the results show that the change of flow or inlet diameter of short blade does not change the dominant frequency of impeller. The high frequency of the suction side of blade gradually decreases and the high frequency of the pressure face gradually increases with the increase of inlet diameter of short blade. The pressure fluctuation amplitude of different inlet diameters of short blade with small flow is large. The wave energy of each monitoring point in the low frequency region and the high frequency region on the suction side of blade is significantly larger than that of the pressure face in the design condition. The band width of the low frequency region and wave energy of the high frequency region of monitoring points near the suction side of blade significantly increase at large flow fluctuation. The fluctuation amplitude of monitoring points near the pressure face of the blade has a large increase. The pulsation amplitude of each monitoring point near the suction side of the short blade is significantly higher than that of the long blade. The comprehensive analysis shows that when the inlet diameter of the short blade is 0.72D2, the pressure fluctuation in a variety of conditions reaches minimum. (authors)

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

    Science.gov (United States)

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

    2012-03-01

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

  14. Numerical Investigation on Pressure Fluctuations for Different Configurations of Vaned Diffuser Pumps

    Directory of Open Access Journals (Sweden)

    Jianjun Feng

    2007-01-01

    Full Text Available Numerical simulations on impeller-diffuser interactions in radial diffuser pumps are conducted to investigate the unsteady flow, and more attention is paid to pressure fluctuations on the blade and vane surfaces. Calculations are performed at different operating points, different blade number configurations, and different radial gaps between the impeller and diffuser to examine their effects on the unsteady flow. Computational results show that a jet-wake flow structure is observed at the impeller outlet. The biggest pressure fluctuation on the blade is found to occur at the impeller trailing edge, on the pressure side near the impeller trailing edge, and at the diffuser vane leading edge, independent of the flow rate, radial gap, and blade number configuration. All of the flow rate, blade number configuration, and radial gap influence significantly the pressure fluctuation and associated unsteady effects in the diffuser pumps.

  15. Calculation and analysis of thermal–hydraulics fluctuations in pressurized water reactors

    International Nuclear Information System (INIS)

    Highlights: • Single-phase thermal–hydraulics noise equations are originally derived in the frequency domain. • The fluctuations of all the coolant parameters are calculated, without any simplifying assumptions. • The radial distribution of the temperature fluctuations in the fuel, gap and cladding are taken into account. • The closed-loop calculations are performed by means of the point kinetics noise theory. • Both the space- and frequency-dependence of the thermal–hydraulics fluctuations are analyzed. - Abstract: Analysis of thermal–hydraulics fluctuations in pressurized water reactors (e.g., local and global temperature or density fluctuations, as well as primary and charging pumps fluctuations) has various applications in calculation or measurement of the core dynamical parameters (temperature or density reactivity coefficients) in addition to thermal–hydraulics surveillance and diagnostics. In this paper, the thermal–hydraulics fluctuations in PWRs are investigated. At first, the single-phase thermal–hydraulics noise equations (in the frequency domain) are originally derived, without any simplifying assumptions. The fluctuations of all the coolant parameters, as well as the radial distribution of the temperature fluctuations in the fuel, gap and cladding are taken into account. Then, the derived governing equations are discretized using the finite volume method (FVM). Based on the discretized equations and the proposed algorithm of solving, a single heated channel noise calculation code (SHC-Noise) is developed, by which the steady-state and fluctuating parameters of PWR fuel assemblies can be calculated. The noise sources include the inlet coolant temperature and velocity fluctuations, in addition to the power density noises. The developed SHC-Noise code is benchmarked in different cases and scenarios. Furthermore, to show the effects of the power feedbacks, the closed-loop calculations are performed by means of the point kinetics noise

  16. Investigation on pressure fluctuation in a Francis turbine with improvement measures

    Science.gov (United States)

    Feng, J. J.; Li, W. F.; Wu, H.; Lu, J. L.; Liao, W. L.; Luo, X. Q.

    2014-03-01

    For a prototype turbine operating under part load conditions, the turbine output power is fluctuating strongly. The test for the prototype turbine at site shows that the main reason is the resonance between the draft tube vortex frequency and the generator natural frequency. In order to reduce the fluctuation of power output, different measures are investigated with using CFD methods. To keep the turbine unchanged, four kinds of draft tubes are examined, including the original draft, the draft tube with extending runner cone, the draft tube with damping gates and the draft tube with flow deflectors. The results are analyzed and compared in order to examine the effects on pressure fluctuation and formation of vortex rope of draft tube. It is found that adding flow deflector is the most effective to change the frequency of the draft tube vortex rope and reduce the amplitude of pressure fluctuation.

  17. Time series analysis of pressure fluctuation in gas-solid fluidized beds

    Directory of Open Access Journals (Sweden)

    C. Alberto S. Felipe

    2004-09-01

    Full Text Available The purpose of the present work was to study the differentiation of states of typical fluidization (single bubble, multiple bubble and slugging in a gas-solid fluidized bed, using spectral analysis of pressure fluctuation time series. The effects of the method of measuring (differential and absolute pressure fluctuations and the axial position of the probes in the fluidization column on the identification of each of the regimes studied were evaluated. Fast Fourier Transform (FFT was the mathematic tool used to analysing the data of pressure fluctuations, which expresses the behavior of a time series in the frequency domain. Results indicated that the plenum chamber was a place for reliable measurement and that care should be taken in measurement in the dense phase. The method allowed fluid dynamic regimes to be differentiated by their dominant frequency characteristics.

  18. Experimental research on pressure fluctuation and vibration in a mixed flow pump

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Kai; Liu, Houlin; Wang, Wenbo [National Research Center of Pumps and Pumping System Engineering and Technology, Jiangsu University, Zhenjiang (China); Zhou, Xiaohua [Gree Electric Appliance Inc. of Zhuhai, Zhuhai (China)

    2016-01-15

    To study the pressure fluctuation and vibration in mixed flow pumps, we chose a mixed flow pump with specific speed of 436.1 to measure. The time domains and frequency domain at each monitoring point on diffuser and outlet elbow were analyzed, as well as the vibration frequency domain characteristics at the impeller outlet and near the motor. The results show that the peak value of pressure fluctuation peak decreased gradually with the increase of flow rate. The pressure fluctuation of each monitoring point had periodicity, and the frequency domain dominated by blade passing frequency and multiple shaft frequency. The vibration frequency of each monitoring point occurred at shaft frequency and its multiple shaft frequency. The dominant frequency and the second frequency were distributed in shaft frequency and double shaft frequency.

  19. New insights from well responses to fluctuations in barometric pressure

    Science.gov (United States)

    Butler, J.J.; Jin, W.; Mohammed, G.A.; Reboulet, E.C.

    2011-01-01

    Hydrologists have long recognized that changes in barometric pressure can produce changes in water levels in wells. The barometric response function (BRF) has proven to be an effective means to characterize this relationship; we show here how it can also be utilized to glean valuable insights into semi-confined aquifer systems. The form of the BRF indicates the degree of aquifer confinement, while a comparison of BRFs between wells sheds light on hydrostratigraphic continuity. A new approach for estimating hydraulic properties of aquitards from BRFs has been developed and verified. The BRF is not an invariant characteristic of a well; in unconfined or semi-confined aquifers, it can change with conditions in the vadose zone. Field data from a long-term research site demonstrate the hydrostratigraphic insights that can be gained from monitoring water levels and barometric pressure. Such insights should be of value for a wide range of practical applications. ?? 2010 The Author(s). Journal compilation ?? 2010 National Ground Water Association.

  20. WALL PRESSURE FLUCTUATIONS OF TURBULENT FLOW OVER BACKWARD-FACING STEP WITH AND WITHOUT ENTRAINMENT: MICROPHONE ARRAY MEASUREMENT

    Institute of Scientific and Technical Information of China (English)

    KE Feng; LIU Ying-zheng; WANG Wei-zhe; CHEN Han-ping

    2006-01-01

    Wall pressure fluctuations in turbulent boundary layer flow over backward-facing step with and without entrainment were investigated. Digital array pressure sensors and multi-arrayed microphones were employed to acquire the time-averaged static pressure and fluctuating pressure, respectively. The differences of two flows were scrutinized in terms of static pressure characteristics, pressure fluctuations, cross-correlation and coherence of wall pressure. Introduction of the entrainment increased scale of large-scale vortical structure and reduced its convection velocity. However, shedding frequency of large-scale vortical structures was found to be the same for both flows.

  1. Analysis on the blade inlet pressure fluctuation of the centrifugal pump based on LES

    Science.gov (United States)

    Wang, W. J.; Cui, Y. R.; Wang, Y.; Li, G. D.; Liang, Q. H.; Yin, G.

    2013-12-01

    In order to study the characteristics of the blade inlet pressure fluctuation under unsteady flow in centrifugal pump, a three-dimensional model of a pump ns=50 was built. Based on large eddy simulation (LES), the inner flow field of the pump was simulated by the flow field simulation software Fluent in design condition and off-design conditions. The pressure fluctuation of the monitored points was obtained at the blade suction surface and pressure surface at impeller inlet, which was analyzed by time and frequency domain with Fast Fourier Transformation (FFT). The results show that the pressure fluctuation of inlet and outlet in large flow rate is more obvious than low flow rate. It is easily found that the static pressure of outlet in 1.2Qd condition has five peaks and five valleys, but this phenomenon does not exist in 0.6 Qd condition. In the time domain spectrums, the static pressure curve has five peaks and five valleys that the maximum pressure is positive number and the minimum pressure is negative number. In the frequency domains spectrums, the frequency of FFT factors peak is lower than the blade passing frequency 241.65Hz.

  2. Atmospheric pressure plasma for surface modification

    CERN Document Server

    Wolf, Rory A

    2012-01-01

    This Book's focus and intent is to impart an understanding of the practical application of atmospheric plasma for the advancement of a wide range of current and emerging technologies. The primary key feature of this book is the introduction of over thirteen years of practical experimental evidence of successful surface modifications by atmospheric plasma methods. It offers a handbook-based approach for leveraging and optimizing atmospheric plasma technologies which are currently in commercial use. It also offers a complete treatment of both basic plasma physics and industrial plasma process

  3. A root-mean-square pressure fluctuations model for internal flow applications

    Science.gov (United States)

    Chen, Y. S.

    1985-01-01

    A transport equation for the root-mean-square pressure fluctuations of turbulent flow is derived from the time-dependent momentum equation for incompressible flow. Approximate modeling of this transport equation is included to relate terms with higher order correlations to the mean quantities of turbulent flow. Three empirical constants are introduced in the model. Two of the empirical constants are estimated from homogeneous turbulence data and wall pressure fluctuations measurements. The third constant is determined by comparing the results of large eddy simulations for a plane channel flow and an annulus flow.

  4. The Physical Origin of Severe Low-Frequency Pressure Fluctuations in Giant Francis Turbines

    Science.gov (United States)

    Zhang, R.-K.; Cai, Q.-D.; Wu, J.-Z.; Wu, Y.-L.; Liu, S.-H.; Zhang, L.

    The physical origin of severe low-frequency pressure fluctuation frequently observed in Francis hydraulic turbines under off-design conditions, which greatly damages the structural stability of turbines and even power stations, is analyzed based on the hydrodynamic stability theory and our Reynolds-averaged Navier-Stokes equation simulation (RANS) of the flow in the entire passage of a Francis turbine. We find that spontaneous unsteady vortex ropes, which induce severe pressure fluctuations, are formed due to the absolute instability of the swirling flow at the conical inlet of the turbine's draft tube.

  5. Comparison of the ocular perfusion pressure fluctuation between medically controlled and operated eyes with glaucoma

    Directory of Open Access Journals (Sweden)

    Carolina Engelbrecht

    2014-04-01

    Full Text Available Purpose: To compare the fluctuation of the OPP between eyes treated with glaucoma medication and eyes with a functioning filtering bleb. Design: cross-sectional controlled paired-eye design. Methods: Fourteen patients with POAG with one eye operated on (trabeculectomy and the fellow eye treated with medication enrolled the study. Blood pressure and intraocular pressure were measured at 7 a.m., 1 p.m., and 7 p.m. Systolic, diastolic and mean OPP were calculated for the three time points and the fluctuation (range between the highest and the lowest values compared between the eyes. Results: Mean values of the mean OPP fluctuation were 7.2 ± 3.9 mmHg and 8.5 ± 4.0 mmHg, for operated eyes and medically treated eyes, respectively (P = 0.149; mean systolic OPP fluctuation was 20.7 ± 11.2 mmHg for operated eyes and 21.2 ± 11.7 mmHg for medically treated eyes (P = 0.478; the mean diastolic OPP fluctuation was 8.4 ± 4.4 mmHg for operated eyes and 10.5 ± 5.4 mmHg for medically treated eyes (P= 0.085. Conclusion: In this small cohort of patients with POAG the mean, systolic and diastolic OPP fluctuation did not differ between the operated eyes and medically treated ones. Financial disclosure: none.

  6. Modelling the soil-atmosphere exchange of POPs: Long-term steady state and diurnal fluctuations

    Science.gov (United States)

    Bao, Z.; Beckingham, B.; Maier, U.; Haberer, C.; Grathwohl, P.

    2014-12-01

    Soil-atmosphere exchange is an important transport process influencing environmental fate and transport of many persistent organic pollutants (POPs). This study focuses on modelling the gaseous exchange of a semi-volatile polycyclic aromatic hydrocarbon (phenanthrene) between soil and the atmosphere using the multicomponent reactive transport code MIN3P. MIN3P is typically applied to simulate aqueous and vapor phase subsurface transport and reaction processes. We extended the code to also include an atmospheric boundary layer where eddy diffusion and photodegradation take place. The relevant processes and parameters affecting soil-atmosphere exchange were investigated in several scenarios and at various time scales. We found that phenanthrene is well-mixed in the atmospheric boundary layer under neutral or stable atmospheric conditions due to fast eddy diffusion. Uptake of airborne phenanthrene to soils is limited by the soil properties and initially depends on diffusion in soil gas and sorption to the solids. On the long term seepage water dominates transport into deeper soil layers; biodegradation finally leads to steady-state concentration profiles in the subsurface typically achieved after a few centuries. If concentrations in the atmosphere decrease, e.g. due to environmental legislation, then soils become sources for the POPs for the first two months and function as sinks again for the POPs until new steady state concentrations are reached (after decades to centuries). MIN3P was also used to simulate diurnal soil-atmosphere exchanges of airborne pollutants due to temperature changes and photodegradation, both which cause fluctuations in atmospheric concentrations and therefore affect mass transfer between soil and the atmosphere. The model can further be applied to estimate the environmental fate of other POPs between soil and the atmosphere under different environmental pollution and climate change scenarios.

  7. Pore Pressure Response to Groundwater Fluctuations in Saturated Double-Layered Soil

    Directory of Open Access Journals (Sweden)

    Hongwei Ying

    2015-01-01

    Full Text Available Analytical solutions are developed for one-dimensional consolidation of double-layered saturated soil subjected to groundwater fluctuations. The solutions are derived by an explicit mathematical procedure using Duhamel’s theorem in conjunction with a Fourier series, when groundwater fluctuation is described by a general time-dependent function and assumed to be the pore water pressure variations at the upper boundary. Taking as an example the harmonic groundwater fluctuation, the relevant response of the excess pore water pressure is discussed in detail, and the main influencing factors of the excess pore pressure distribution are analyzed. A dimensionless parameter θ has been introduced because it significantly affects the phase and the amplitude of excess pore pressures. The influences of the coefficients of permeability and compressibility of soil on the excess pore pressure distribution are different and cannot be incorporated into the coefficient of consolidation in double-layered soil. The relative permeability ratio of two clayey soils also plays an important role on the curves of the distributions of the excess pore pressures. The effects of the thickness of the soil layer on the excess pore pressure distribution should be considered together with the dimensionless parameter θ and the permeability and compressibility of the double-layered soil system.

  8. Numerical simulations of pressure fluctuations at branch piping in BWR main steam line

    International Nuclear Information System (INIS)

    The power uprating of a nuclear power plant may increase/accelerate degradation phenomena such as flow-induced vibration and wall thinking. A steam dryer was damaged by a high cycle fatigue due to an acoustic-induced vibration at the branch piping of safety relief valves (SRVs) in main steam lines. In this study, we conducted the numerical simulations of steam/air flow around a simplified branch piping to clarify the basic characteristics of resonance. LES simulations were conducted in ordinary pressure/temperature air and steam under BWR plant conditions. In both cases, the excitation of the pressure fluctuations at the branch was observed under some inlet velocity conditions. These fluctuations and inlet conditions were normalized and the obtained results were compared. The normalized results showed that the range and maximum amplitude of pressure fluctuations were almost the same in low-pressure/temperature air and high-pressure/temperature steam. We found that ordinary pressure/temperature air experiments and simulations can possibly clarify the characteristics of the resonance in high-pressure/temperature steam. (author)

  9. Mechanism of temperature fluctuation phenomena below steam-water interface in a pressurizer spray pipe

    International Nuclear Information System (INIS)

    In a PWR plant, a steam-water two-phase flow may exist in the pressurizer spray pipe under a normal operating condition since the flow rate of the spray water is not sufficient to fill the horizontal section of the pipe completely. Initiation of high cycle fatigue cracks is suspected to occur under such thermally stratified two phase flow conditions. Experiments for a steam-water flow have been conducted to investigate the temperature fluctuation phenomena. It has been shown that the wall temperature fluctuations were not caused by the waves on the water surface, but were caused by temperature fluctuations in water layer below the interface. An experiment with visualization test section of rectangular pipe was conducted to investigate the temperature fluctuation mechanism in water layer in this paper. The black stripe pattern was observed below the steam-water interface due to the density change. The water temperature fluctuations had the dominant frequency of about 1Hz. The Richardson number calculated with the measured temperature and velocity gradient was larger than 0.25. The dominant frequency of temperature fluctuations was nearly equal to the Brunt-Väisälä frequency. It was shown that the temperature fluctuations in water layer below the interface were caused by the internal gravity wave in the thermal stratified flow. (author)

  10. Pressure, density, temperature and entropy fluctuations in compressible turbulent plane channel flow

    CERN Document Server

    Gerolymos, G A

    2013-01-01

    We investigate the fluctuations of thermodynamic state-variables in compressible aerodynamic wall-turbulence, using results of direct numerical simulation (DNS) of compressible turbulent plane channel flow. The basic transport equations governing the behaviour of thermodynamic variables (density, pressure, temperature and entropy) are reviewed and used to derive the exact transport equations for the variances and fluxes (transport by the fluctuating velocity field) of the thermodynamic fluctuations. The scaling with Reynolds and Mach number of compressible turbulent plane channel flow is discussed. Correlation coefficients and higher-order statistics of the thermodynamic fluctuations are examined. Finally, detailed budgets of the transport equations for the variances and fluxes of the thermodynamic variables from a well-resolved DNS are analysed. Implications of these results both to the understanding of the thermodynamic interactions in compressible wall-turbulence and to possible improvements in statistical...

  11. Buffering blood pressure fluctuations by respiratory sinus arrhythmia may in fact enhance them: a theoretical analysis

    CERN Document Server

    Buchner, Teodor; Gielerak, Grzegorz

    2010-01-01

    Using a three-compartment model of blood pressure dynamics, we analyze theoretically the short term cardiovascular variability: how the respiratory-related blood pressure fluctuations are buffered by appropriate heart rate changes: i.e. the respiratory sinus arrhythmia. The buffering is shown to be crucially dependent on the time delay between the stimulus (such as e.g. the inspiration onset) and the application of the control (the moment in time when the efferent response is delivered to the heart). This theoretical analysis shows that the buffering mechanism is effective only in the upright position of the body. It explains a paradoxical effect of enhancement of the blood pressure fluctuations by an ineffective control. Such a phenomenon was observed experimentally. Using the basis of the model, we discuss the blood pressure variability and heart rate variability under such clinical conditions as the states of expressed adrenergic drive and the tilt-test during the parasympathetic blockade or fixed rate atr...

  12. Pressure Fluctuation in a Vaned Diffuser Downstream from a Centrifugal Pump Impeller

    Directory of Open Access Journals (Sweden)

    Akinori Furukawa

    2003-01-01

    Full Text Available Periodic flows downstream from a centrifugal pump impeller in vaneless and vaned diffusers were measured by using a single hole yawmeter and a phase-locked sampling method. The flows were also calculated by an inviscid flow analysis using the blade-surface singularity method. The periodic variations in calculated static pressure with the impeller rotating quantitatively agree well with the measured ones. The flow behaviors in the vaned diffuser are discussed, citing measured and calculated results. The potential interaction between the impeller and the diffuser blades appears more strongly than the impeller-wake interaction. The appearance of static pressure fluctuations due to the impeller's rotating in the fully vaned zone is different from that in the semivaned zone of the diffuser. The existence of the peripheral blade surface of the impeller outlet with an outlet edge of the pressure surface causes violent pressure fluctuations in the vaned diffuser.

  13. Sulphate chemistry under pressurized oxidizing, reducing and fluctuating conditions; Sulfatkemi under trycksatta oxiderande, reducerande och fluktuerande foerhaallanden

    Energy Technology Data Exchange (ETDEWEB)

    Hupa, M.; Yrjas, P.; Backman, P. [Aabo Akademi, Turku (Finland). Combustion Chemistry Research Group

    1997-10-01

    In the literature it has been reported that sulfur capture with limestone (CaCO{sub 3}) under atmospheric fluidized bed combustion conditions reaches a maximum at about 850 deg C. Previously, the maximum has been attributed to the sintering of sorbent particles which decreases the reactive surface area. Lately, also another explanation has been reported. In this case the sulfur capture decrease at higher temperatures was concluded to be due to fluctuating oxidizing/reducing conditions in the atmospheric combustor. In this work the influence of alternating oxidizing/reducing conditions on SO{sub 2} capture at atmospheric and elevated pressure (15 bar) has been studied. In the pressurized case, the CO{sub 2} partial pressure was kept high enough to prevent CaCO{sub 3} from calcining and therefore the CaSO{sub 4} would not form CaO but CaCO{sub 3} under reducing conditions. The experiments were done with a pressurized TGA by periodically changing the gas environment between oxidizing (O{sub 2}. SO{sub 2}, CO{sub 2} and N{sub 2}) and slightly reducing (CO, SO{sub 2}, CO{sub 2} and N{sub 2}) gas mixtures at different temperatures. The results from the experiments showed that under normal pressure and slightly reducing conditions CaO formation from CaSO{sub 4} increased with temperature as expected. However, no significant amounts of CaCO{sub 3} were formed from CaSO{sub 4} at elevated pressure. It was also concluded that since the formation of CaO from CaSO{sub 4} was relatively slow it could not explain the sharp sulfur capture maximum at about 850 deg C. Therefore, it was assumed that the strongly reducing zones, where CaS thermodynamically is the stable compound, play a more important role concerning the sulfur capture in fluidized bed combustors. (orig.)

  14. Charge Exchange Reaction in Dopant-Assisted Atmospheric Pressure Chemical Ionization and Atmospheric Pressure Photoionization.

    Science.gov (United States)

    Vaikkinen, Anu; Kauppila, Tiina J; Kostiainen, Risto

    2016-08-01

    The efficiencies of charge exchange reaction in dopant-assisted atmospheric pressure chemical ionization (DA-APCI) and dopant-assisted atmospheric pressure photoionization (DA-APPI) mass spectrometry (MS) were compared by flow injection analysis. Fourteen individual compounds and a commercial mixture of 16 polycyclic aromatic hydrocarbons were chosen as model analytes to cover a wide range of polarities, gas-phase ionization energies, and proton affinities. Chlorobenzene was used as the dopant, and methanol/water (80/20) as the solvent. In both techniques, analytes formed the same ions (radical cations, protonated molecules, and/or fragments). However, in DA-APCI, the relative efficiency of charge exchange versus proton transfer was lower than in DA-APPI. This is suggested to be because in DA-APCI both dopant and solvent clusters can be ionized, and the formed reagent ions can react with the analytes via competing charge exchange and proton transfer reactions. In DA-APPI, on the other hand, the main reagents are dopant-derived radical cations, which favor ionization of analytes via charge exchange. The efficiency of charge exchange in both DA-APPI and DA-APCI was shown to depend heavily on the solvent flow rate, with best efficiency seen at lowest flow rates studied (0.05 and 0.1 mL/min). Both DA-APCI and DA-APPI showed the radical cation of chlorobenzene at 0.05-0.1 mL/min flow rate, but at increasing flow rate, the abundance of chlorobenzene M(+.) decreased and reagent ion populations deriving from different gas-phase chemistry were recorded. The formation of these reagent ions explains the decreasing ionization efficiency and the differences in charge exchange between the techniques. Graphical Abstract ᅟ.

  15. Numerical simulation of pressure fluctuation in 1000MW Francis turbine under small opening condition

    Science.gov (United States)

    Gong, R. Z.; Wang, H. G.; Yao, Y.; Shu, L. F.; Huang, Y. J.

    2012-11-01

    In order to study the cause of abnormal vibration in large Francis turbine under small opening condition, CFD method was adopted to analyze the flow filed and pressure fluctuation. Numerical simulation was performed on the commercial CFD code Ansys FLUENT 12, using DES method. After an effective validation of the computation result, the flow behaviour of internal flow field under small opening condition is analyzed. Pressure fluctuation in different working mode is obtained by unsteady CFD simulation, and results is compared to study its change. Radial force fluctuation is also analyzed. The result shows that the unstable flow under small opening condition leads to an increase of turbine instability in reverse pump mode, and is one possible reason of the abnormal oscillation.

  16. Non-Thermal Sanitation By Atmospheric Pressure Plasma Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ORBITEC's Non-Thermal Sanitation by Atmospheric Pressure Plasma technology sanitizes fresh fruits and vegetables without the use of consumable chemicals and without...

  17. Non-Thermal Sanitation By Atmospheric Pressure Plasma Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ORBITEC proposes to develop a non-thermal technology based on atmospheric-pressure (AP) cold plasma to sanitize foods, food packaging materials, and other hardware...

  18. Pressure Dependence of the Critical Fluctuations in the Singlet-Ground-State System, Pr3TI

    DEFF Research Database (Denmark)

    Kjems, Jørgen; Nielsen, Mourits; Buyers, W. J. L;

    1979-01-01

    The pressure dependence of the magnetization and of the critical fluctuations in a polycrystalline sample of Pr3Tl have been studied by neutron scattering. Above Tc the quasielastic intensity is better reproduced by a theory In which the excitons are strongly damped by the conduction electrons than...

  19. Numerical Investigation on Pressure Fluctuations for Different Configurations of Vaned Diffuser Pumps

    OpenAIRE

    Jianjun Feng; Friedrich-Karl Benra; Hans Josef Dohmen

    2007-01-01

    Numerical simulations on impeller-diffuser interactions in radial diffuser pumps are conducted to investigate the unsteady flow, and more attention is paid to pressure fluctuations on the blade and vane surfaces. Calculations are performed at different operating points, different blade number configurations, and different radial gaps between the impeller and diffuser to examine their effects on the unsteady flow. ...

  20. Experimental investigation of pressure fluctuations caused by a vortex rope in a draft tube

    Science.gov (United States)

    Kirschner, O.; Ruprecht, A.; Göde, E.; Riedelbauch, S.

    2012-11-01

    In the last years hydro power plants have taken the task of power-frequency control for the electrical grid. Therefore turbines in storage hydro power plants often operate outside their optimum. If Francis-turbines and pump-turbines operate at off-design conditions, a vortex rope in the draft tube can develop. The vortex rope can cause pressure oscillations. In addition to low frequencies caused by the rotation of the vortex rope and the harmonics of these frequencies, pressure fluctuations with higher frequencies can be observed in some operating points too. In this experimental investigation the flow structure and behavior of the vortex rope movement in the draft tube of a model pump-turbine are analyzed. The investigation focuses on the correlation of the pressure fluctuation frequency measured at the draft tube wall with the movement of the vortex rope. The movement of the vortex rope is analyzed by the velocity field in the draft tube which was measured with particle image velocimetry. Additionally, the vortex rope movement has been analyzed with the captures of high-speed-movies from the cavitating vortex rope. Besides the rotation of the vortex rope due to pressure fluctuation with low frequencies the results of the measurement also show a correlation between the rotation of the elliptical or deformed rope cross-section and the higher frequency pressure pulsation. An approximation shows that the frequencies of the pressure fluctuation and the movement of the vortex rope are also connected with the velocity of the flow. Taking into account the size and position of the cavitating vortex core as well as the velocity at the position of the surface of the cavitating vortex core the time-period of the rotation of the vortex core can be approximated. The results show that both, the low frequency pressure fluctuation and the higher frequency pressure fluctuation are correlating with the vortex rope movement. With this estimation, the period of the higher frequency

  1. Atmospheric pressure plasma enhanced spatial ALD of silver

    NARCIS (Netherlands)

    Van Den Bruele, F.J.; Smets, M.; Illiberi, A.; Creyghton, Y.; Buskens, P.; Roozeboom, F.; Poodt, P.

    2014-01-01

    The authors have investigated the growth of thin silver films using a unique combination of atmospheric process elements: spatial atomic layer deposition and an atmospheric pressure surface dielectric barrier discharge plasma source. Silver films were grown on top of Si substrates with good purity a

  2. A Spectacular Experiment Exhibiting Atmospheric Pressure

    Science.gov (United States)

    Le Noxaïc, Armand

    2014-01-01

    The experiment described here is fairly easy to reproduce and dramatically shows the magnitude of ambient air pressure. Two circular plates of aluminum are applied one against the other. How do you make their separation very difficult? With only the help of an elastic band! You don't have to use a vacuum pump for this experiment.

  3. Vapor phase growth of functional pentacene films at atmospheric pressure

    NARCIS (Netherlands)

    Rolin, C.; Vasseur, K.; Niesen, B.; Willegems, M.; Müller, R.; Steudel, S.; Genoe, J.; Heremans, P.

    2012-01-01

    Compared to traditional vacuum evaporation techniques for small organic molecules, organic vapor phase deposition (OVPD) possesses a extra processing parameter: the pressure of process gas Pch. Here, the influence of large Pch variations (from 0.1 mbar to atmospheric pressure) on pentacene thin film

  4. Renal blood flow regulation and arterial pressure fluctuations: a case study in nonlinear dynamics

    DEFF Research Database (Denmark)

    Holstein-Rathlou, N H; Marsh, D J

    1994-01-01

    The arterial blood pressure, a physiological variable on which all renal excretory processes depend, fluctuates over a wide range of amplitudes and frequencies. Much of this variation originates in nonrenal vascular beds to support nonrenal tasks, and the fluctuations provide a noisy environment...... a relatively noise-free environment in which to work. Because of the time-varying nature of the blood pressure, we have concentrated in this review on the now substantial body of work on the dynamics of renal blood flow regulation and the underlying mechanisms. Renal vascular control mechanisms are not simply...... of experimental hypertension provide tubular pressure records that pass statistical tests for ordered structure and sensitive dependence on initial conditions in the reconstructed state space, two of the hallmarks of deterministic chaos. These records also pass recent more stringent tests for chaos...

  5. Relationship of Early Spontaneous Type V Blood Pressure Fluctuation after Thrombolysis in Acute Cerebral Infarction Patients and the Prognosis

    OpenAIRE

    Lian Zuo; Ting Wan; Xiahong Xu; Feifeng Liu; Changsong Li; Ying Li; Yue Zhang; Jing Zhang; Huan Bao; Gang Li

    2016-01-01

    We examined the relationship between an early spontaneous type V blood pressure fluctuation and the post-thrombolysis prognosis of patients with acute cerebral infarction. Patients were admitted consecutively. All patients were categorized into the type V blood pressure fluctuation group or non-type V blood pressure group. Their blood pressure was monitored before thrombolysis and until 6 h after thrombolysis. Baseline data and clinical outcomes were compared. Of 170 patients, 43 (25.2%) had ...

  6. Gas Line Pressure Fluctuation Analysis of a Gas-Liquid Reactor

    Institute of Scientific and Technical Information of China (English)

    J.J.J. CHEN; J.C. ZHAO

    2005-01-01

    To ensure efficient operation of metallurgical gas-liquid reactors, the gas bubbles must be uniformly distributed.For high temperature metallurgical reactors, it is impractical and unsafe to carry out visual observations.An air-water model was used to study the relationship between the bubble flow patterns and the pressure fluctuation signals.The fluctuation signals captured in the time domain were transformed into the frequency domain. Various parameters obtained from the transformed data were analysed for their suitability for delineating the bubble flow pqtterns observed.These parameters and the flow patterns were found to be well-correlated using the gas flow number.

  7. Ultrasound enhanced plasma surface modification at atmospheric pressure

    DEFF Research Database (Denmark)

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

    2012-01-01

    Efficiency of atmospheric pressure plasma treatment can be highly enhanced by simultaneous high power ultrasonic irradiation onto the treating surface. It is because ultrasonic waves with a sound pressure level (SPL) above ∼140 dB can reduce the thickness of a boundary gas layer between the plasma...... arc at atmospheric pressure to study adhesion improvement. The effect of ultrasonic irradiation with the frequency diapason between 20 and 40 kHz at the SPL of ∼150 dB was investigated. After the plasma treatment without ultrasonic irradiation, the wettability was significantly improved...

  8. Ultrasound enhanced plasma surface modification at atmospheric pressure

    DEFF Research Database (Denmark)

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

    Atmospheric pressure plasma treatment can be highly enhanced by simultaneous high-power ultrasonic irradiation onto the treating surface. It is because ultrasonic waves with a sound pressure level (SPL) above approximately 140 dB can reduce the thickness of a boundary gas layer between the plasma...... and the material surface, and thus many reactive species generated in the plasma can reach the surface before inactivated, and be efficiently utilized for surface modification. In the present work polyester plates are treated using a dielectric barrier discharge (DBD) and a gliding arc at atmospheric pressure...

  9. Influence of the turbulent boundary layer pressure fluctuation on the sound intensity measurement in a mean flow

    DEFF Research Database (Denmark)

    SHI, Xiao-jun; Jacobsen, Finn

    2010-01-01

    The influence of turbulent boundary layer pressure fluctuation on the sound intensity measurement in a flow is a subject of practical concern, because the sound intensity probe is generally exposed to the airflow and is sensed the turbulent boundary layer (TBL) pressure fluctuation which may even...

  10. Temperature field simulation of gob influenced by atmospheric pressure

    Institute of Scientific and Technical Information of China (English)

    王刚; 罗海珠; 梁运涛; 王继仁

    2015-01-01

    The current temperature field model of mine gob does not take the boundary conditions of the atmospheric pressure into account, while the actual atmospheric pressure is influenced by weather, so as to produce differences between ventilation negative pressure of the working face and the negative pressure of gas drainage in gob, thus interfering the calculated results of gob temperature field. According to the characteristics of the actual air flow and temperature change in gob, a two-dimensional temperature field model of the gob was built, and the relational model between the air pressure of intake and outlet of the gob and the atmospheric pressure was established, which was introduced into the boundary conditions of temperature field to conduct calculation. By means of analysis on the simulation example, and comparison with the traditional model, the results indicate that atmospheric pressure change had notable impact on the distribution of gob temperature field. The laboratory test system of gob temperature field was constructed, and the relative error between simulated and measured value was no greater than 9.6%, which verified the effectiveness of the proposed model. This work offers theoretical basis for accurate calculation of temperature and prediction of ignition source in mine gob, and has important implications on preventing spontaneous combustion of coal.

  11. Detection of atmospheric pressure loading using very long baseline interferometry measurements

    Science.gov (United States)

    Vandam, T. M.; Herring, T. A.

    1994-01-01

    Loading of the Earth by the temporal redistribution of global atmospheric mass is likely to displace the positions of geodetic monuments by tens of millimeters both vertically and horizontally. Estimates of these displacements are determined by convolving National Meteorological Center (NMC) global values of atmospheric surface pressure with Farrell's elastic Green's functions. An analysis of the distances between radio telescopes determined by very long baseline interferometry (VLBI) between 1984 and 1992 reveals that in many of the cases studied there is a significant contribution to baseline length change due to atmospheric pressure loading. Our analysis covers intersite distances of between 1000 and 10,000 km and is restricted to those baselines measured more than 100 times. Accounting for the load effects (after first removing a best fit slope) reduces the weighted root-mean-square (WRMS) scatter of the baseline length residuals on 11 of the 22 baselines investigated. The slight degradation observed in the WRMS scatter on the remaining baselines is largely consistent with the expected statistical fluctuations when a small correction is applied to a data set having a much larger random noise. The results from all baselines are consistent with approximately 60% of the computed pressure contribution being present in the VLBI length determinations. Site dependent coefficients determined by fitting local pressure to the theoretical radial displacement are found to reproduce the deformation caused by the regional pressure to within 25% for most inland sites. The coefficients are less reliable at near coastal and island stations.

  12. Modeling short-term concentration fluctuations of semi-volatile pollutants in the soil-plant-atmosphere system.

    Science.gov (United States)

    Bao, Zhongwen; Haberer, Christina M; Maier, Uli; Beckingham, Barbara; Amos, Richard T; Grathwohl, Peter

    2016-11-01

    Temperature changes can drive cycling of semi-volatile pollutants between different environmental compartments (e.g. atmosphere, soil, plants). To evaluate the impact of daily temperature changes on atmospheric concentration fluctuations we employed a physically based model coupling soil, plants and the atmosphere, which accounts for heat transport, effective gas diffusion, sorption and biodegradation in the soil as well as eddy diffusion and photochemical oxidation in the atmospheric boundary layer of varying heights. The model results suggest that temperature-driven re-volatilization and uptake in soils cannot fully explain significant diurnal concentration fluctuations of atmospheric pollutants as for example observed for polychlorinated biphenyls (PCBs). This holds even for relatively low water contents (high gas diffusivity) and high sorption capacity of the topsoil (high organic carbon content and high pollutant concentration in the topsoil). Observed concentration fluctuations, however, can be easily matched if a rapidly-exchanging environmental compartment, such as a plant layer, is introduced. At elevated temperatures, plants release organic pollutants, which are rapidly distributed in the atmosphere by eddy diffusion. For photosensitive compounds, e.g. some polycyclic aromatic hydrocarbons (PAHs), decreasing atmospheric concentrations would be expected during daytime for the bare soil scenario. This decline is buffered by a plant layer, which acts as a ground-level reservoir. The modeling results emphasize the importance of a rapidly-exchanging compartment above ground to explain short-term atmospheric concentration fluctuations. PMID:27341116

  13. Mitigation of pressure fluctuations in the discharge cone of hydraulic turbines using flow-feedback

    Science.gov (United States)

    Tanasa, C.; Susan-Resiga, R.; Bosioc, A.; Muntean, S.

    2010-08-01

    Our previous experimental and numerical investigations of decelerated swirling flows in conical diffusers have demonstrated that water jet injection along the symmetry axis mitigates the pressure fluctuations associated with the precessing vortex rope. However, for swirling flows similar to Francis turbines operated at partial discharge, the jet becomes effective when the jet discharge is larger than 10% from the turbine discharge, leading to large volumetric losses when the jet is supplied from upstream the runner. As a result, we introduce in this paper a new approach for supplying the jet by using a fraction of the discharge collected downstream the conical diffuser. We present the technical implementation of this flow-feedback approach, and we investigated experimentally its capability in mitigating the pressure fluctuations generated by the precessing vortex rope. The main advantage of this flow-feedback approach is that is does not require additional energy to supply the jet and it does not decrease the turbine efficiency.

  14. Wavelet analysis of pressure fluctuation signals in a gas-solid fluidized bed

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    It has been shown that much dynamic information is hidden in the pressure fluctuation signals of a gas-solid fluidized bed. Unfortunately, due to the random and capricious nature of this signal, it is hard to realize reliable analysis using traditional signal processing methods such as statistical analysis or spectral analysis, which is done in Fourier domain. Information in different frequency band can be extracted by using wavelet analysis. On the evidence of the composition of the pressure fluctuation signals, energy of low frequency (ELF) is proposed to show the transition of fluidized regimes from bubbling fluidization to turbulent fluidization. Plots are presented to describe the fluidized bed's evolution to help identify the state of different flow regimes and provide a characteristic curve to identify the fluidized status effectively and reliably.

  15. Phase-Plane Invariant Analysis of Pressure Fluctuations in Fluidized Beds

    Institute of Scientific and Technical Information of China (English)

    WANG Xiaoliang; HE Rong; Toshiyuki Suda; Junichi Sato

    2007-01-01

    Partial agglomeration is a major problem in fluidized beds. A chaotic analytical method based on the phase-plane invariant of the pressure fluctuations in the fluidized beds has been used to warn of agglomeration at an early stage. Cold tests (no combustion) and hot tests (combustion) in fluidized beds show that the phase-plane invariant of the pressure fluctuations can distinguish the dynamic behavior of fluidized beds with different flow rates in cold tests. With combustion, when the flow rate was kept constant, agglomeration was detected very early by looking at the phase-plane invariant. The phase-plane invariant can be used to distinguish changes in fluidized beds due to changes in the flow rate, agglomeration, or various other factors. Therefore, this reliable agglomeration early warning system can be used for better control of circulating fluidized beds.

  16. Numerical analyses of pressure fluctuations induced by interblade vortices in a model Francis turbine

    Institute of Scientific and Technical Information of China (English)

    左志钢; 刘树红; 刘德民; 覃大清; 吴玉林

    2015-01-01

    Interblade vortices can greatly influence the stable operations of Francis turbines. As visible interblade vortices are essentially cavitating flows, i.e., the ones to cause interblade vortex cavitations, an unsteady simulation with a method using the RNG k-εturbulence model and the Zwart-Gerber-Belamri (ZGB) cavitation model is carried out to predict the pressure fluctuations induced. Modifications of the turbulence viscosity are made to improve the resolutions. The interblade vortices of two different appearances are observed from the numerical results, namely, the columnar and streamwise vortices, as is consistent with the experimental results. The pressure fluctuations of different frequencies are found to be induced by the interblade vortices on incipient and developed interblade vortex lines, respectively, on the Hill diagram of the model runner’s parameters. From the centrifugal Rayleigh instability criterion, it follows that the columnar interblade vortices are stable and the streamwise interblade vortices are unstable in the model Francis turbine.

  17. Francis turbine draft tube modelling for prediction of pressure fluctuations on prototype

    Science.gov (United States)

    Alligné, S.; Landry, C.; Favrel, A.; Nicolet, C.; Avellan, F.

    2015-12-01

    The prediction of pressure fluctuations amplitudes on Francis turbine prototype is a challenge for hydro-equipment industry since it is subjected to guarantees to ensure smooth and reliable operation of the hydro units. The European FP7 research project Hyperbole aims to setup a methodology to transpose the pressure fluctuations measured on the reduced scale model to the prototype generating units. This paper presents this methodology which relies on an advanced modelling of the draft tube cavitation flow, and focuses on the transposition to the prototype of the draft tube model parameters identified on the reduced scale model. Different modelling assumptions of the draft tube are considered and their influence on the eigenmodes and the forced response of the system are presented.

  18. Spectrum of turbulent-boundary-layer fluctuation pressure and response of a polyvinylidence fluoride hydrophone

    Institute of Scientific and Technical Information of China (English)

    GE Huiliang; HE Zuoyong; BAO Xuemei

    2001-01-01

    The point power spectrum density and the wavenumber frequency spectrum density of turbulent-boundary-layer fluctuation pressure were measured in water-tunnel by use of a φ8 mm hydrophone and a 20-element array, respectively. The non-dimensional representation of measured point power spectrum coincides with the measured results by Bull M. K. et. al. in wind tunnel. The convection peak can be seen clearly in the measured wavenumber frequencyspectrum and the convection velocity can be calculated from the location of the convection peak.The response spectrum of a polyvinylidence fluoride (PVDF) hydrophone, which receiving area is 100 mm × 60 mm, was also measured. By comparing it with the response spectrum of the φ8 mm hydrophone, it is shown that the PVDF hyrdophone has a strong wavenumber filtering effect on turbulent-boundary-layer pressure fluctuation.

  19. RANS simulation of cavitation and hull pressure fluctuation for marine propeller operating behind-hull condition

    Science.gov (United States)

    Paik, Kwang-Jun; Park, Hyung-Gil; Seo, Jongsoo

    2013-12-01

    Simulations of cavitation flow and hull pressure fluctuation for a marine propeller operating behind a hull using the unsteady Reynolds-Averaged Navier-Stokes equations (RANS) are presented. A full hull body submerged under the free surface is modeled in the computational domain to simulate directly the wake field of the ship at the propeller plane. Simulations are performed in design and ballast draught conditions to study the effect of cavitation number. And two propellers with slightly different geometry are simulated to validate the detectability of the numerical simulation. All simulations are performed using a commercial CFD software FLUENT. Cavitation patterns of the simulations show good agreement with the experimental results carried out in Samsung CAvitation Tunnel (SCAT). The simulation results for the hull pressure fluctuation induced by a propeller are also compared with the experimental results showing good agreement in the tendency and amplitude, especially, for the first blade frequency.

  20. Blade Section Design of Marine Propellers with Minimum Cavitation Induced Pressure Fluctuations

    Science.gov (United States)

    Zeng, Zhibo; Kuiper, Gert

    2015-12-01

    To minimize cavitation induced pressure fluctuations by marine propellers with minimum efficiency loss, the paper presents a new design and optimization method using a blade section design method. The sheet cavity volume variation on a two-dimensional blade section in quasi-steady condition has been simplified to a relation with only a limited number of non-dimensional parameters. This results in a fast prediction method of the cavity volume of a blade section passing a wake peak, using a pre-calculated database. This makes optimization feasible. The optimization method was applied to the propeller of a container ship. Extensive tests in a towing tank and a cavitation channel validated the reduction of pressure fluctuations: 33% reduction in the first blade frequency amplitude and 18% reduction in the second blade frequency amplitude, with the same open water efficiency.

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

    Science.gov (United States)

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

    2014-01-01

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

  2. Small size plasma tools for material processing at atmospheric pressure

    Science.gov (United States)

    Ionita, E. R.; Ionita, M. D.; Stancu, E. C.; Teodorescu, M.; Dinescu, G.

    2009-03-01

    A small size radiofrequency plasma jet source able to produce cold plasma jets at atmospheric pressure is presented. The surface modification of polyethylene terephtalate, polyethylene and polytetrafluorethylene foils is performed by using a scanning procedure. The contact angle measurements reveal that the treatment leads to hydrophilicity increase. The roughening of surface, specific to each material is noticed. A significant improvement of adhesion is obtained as result of atmospheric plasma treatments.

  3. Elimination of Fuel Pressure Fluctuation and Multi-injection Fuel Mass Deviation of High Pressure Common-rail Fuel Injection System

    Institute of Scientific and Technical Information of China (English)

    LI Pimao; ZHANG Youtong; LI Tieshuan; XIE Lizhe

    2015-01-01

    The influence of fuel pressure fluctuation on multi-injection fuel mass deviation has been studied a lot, but the fuel pressure fluctuation at injector inlet is still not eliminated efficiently. In this paper, a new type of hydraulic filter consisting of a damping hole and a chamber is developed for elimination of fuel pressure fluctuation and multi-injection fuel mass deviation. Linear model of the improved high pressure common-rail system(HPCRS) including injector, the pipe connecting common-rail with injector and the hydraulic filter is built. Fuel pressure fluctuation at injector inlet, on which frequency domain analysis is conducted through fast Fourier transformation, is acquired at different target pressure and different damping hole diameter experimentally. The linear model is validated and can predict the natural frequencies of the system. Influence of damping hole diameter on fuel pressure fluctuation is analyzed qualitatively based on the linear model, and it can be inferred that an optimal diameter of the damping hole for elimination of fuel pressure fluctuation exists. Fuel pressure fluctuation and fuel mass deviation under different damping hole diameters are measured experimentally, and it is testified that the amplitude of both fuel pressure fluctuation and fuel mass deviation decreases first and then increases with the increasing of damping hole diameter. The amplitude of main injection fuel mass deviation can be reduced by 73%at most under pilot-main injection mode, and the amplitude of post injection fuel mass deviation can be reduced by 92%at most under main-post injection mode. Fuel mass of a single injection increases with the increasing of the damping hole diameter. The hydraulic filter proposed by this research can be potentially used to eliminate fuel pressure fluctuation at injector inlet and improve the stability of HPCRS fuel injection.

  4. Characteristics of RF Cold Plasma at Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    QIU Liang; MENG Yuedong; SHU Xingsheng

    2007-01-01

    The characteristics of a stable discharge at atmospheric pressure is investigated.The plasma source consisted of two closely spaced parallel-plated perforated electrodes,driven by a radio frequency power to generate a uniform cold plasma in Helium at atmospheric pressure.Both alpha and gamma modes were clearly observed.The hollow cathode effects were found in the discharge.The influence of the dielectric barrier on the discharge was also investigated by utilizing a surface-anodized aluminium electrode as the anode.

  5. A simplified nitrogen laser setup operated at atmospheric pressure

    Science.gov (United States)

    Ruangsri, Artit; Wungmool, Piyachat; Tesana, Siripong; Suwanatus, Suchat; Hormwantha, Tongchai; Chiangga, Surasak; Luengviriya, Chaiya

    2015-07-01

    A transversely excited atmospheric pressure nitrogen laser (TEA N2 Laser) is a molecular pulse gas laser, operated at atmospheric pressure, which generates an electromagnetic wave in ultraviolet wavelength of 337.1 nm. It can operate without an optical resonator. We present a TEA N2 laser setup excited by an electronic discharge circuit known as the Blumlein circuit. Our setup is composed of simple components commonly found in everyday life. The setup can be utilized in classroom to demonstrate the dependence of the laser intensity on the flow rate of nitrogen gas.

  6. Image measurements of unsteady pressure fluctuation by a pressure-sensitive coating on porous anodized aluminium

    Science.gov (United States)

    Kameda, M.; Tabei, T.; Nakakita, K.; Sakaue, H.; Asai, K.

    2005-12-01

    Pressure-sensitive luminescent coating on porous anodized aluminium (AA-PSP) was applied to measure non-periodic unsteady pressure distribution on a wind-tunnel model. A high-speed digital video camera was used to capture the PSP signal. The pressure-sensitive dye was tris(4,7-diphenylphenanthroline) ruthenium(II) ([Ru(dpp)3]2+). The coating has a short response time of O(10 µs), although it exhibits temperature and humidity sensitivities. A hydrophobic coating was applied on the anodized aluminium surface to suppress the humidity sensitivity. A temperature sensitive paint was used to obtain the temperature distribution instantaneously with the pressure. The temperature data were used to correct the PSP response. An appropriate data acquisition procedure as well as digital image processing algorithm was established to compensate for the error from the temperature and humidity sensitivities. The present system was applied to measure the pressure distribution on a delta wing at a high angle of attack in transonic flow, whose flow is unsteady due to the interaction between shock waves and leading edge vortices. The non-periodic unsteady pressure distribution on the delta wing was successfully measured with the sampling rate of 1 kHz and within a few per cent error in absolute pressure level.

  7. The diversification of Paleozoic fire systems and fluctuations in atmospheric oxygen concentration.

    Science.gov (United States)

    Scott, Andrew C; Glasspool, Ian J

    2006-07-18

    By comparing Silurian through end Permian [approximately 250 million years (Myr)] charcoal abundance with contemporaneous macroecological changes in vegetation and climate we aim to demonstrate that long-term variations in fire occurrence and fire system diversification are related to fluctuations in Late Paleozoic atmospheric oxygen concentration. Charcoal, a proxy for fire, occurs in the fossil record from the Late Silurian (approximately 420 Myr) to the present. Its presence at any interval in the fossil record is already taken to constrain atmospheric oxygen within the range of 13% to 35% (the "fire window"). Herein, we observe that, as predicted, atmospheric oxygen levels rise from approximately 13% in the Late Devonian to approximately 30% in the Late Permian so, too, fires progressively occur in an increasing diversity of ecosystems. Sequentially, data of note include: the occurrence of charcoal in the Late Silurian/Early Devonian, indicating the burning of a diminutive, dominantly rhyniophytoid vegetation; an apparent paucity of charcoal in the Middle to Late Devonian that coincides with a predicted atmospheric oxygen low; and the subsequent diversification of fire systems throughout the remainder of the Late Paleozoic. First, fires become widespread during the Early Mississippian, they then become commonplace in mire systems in the Middle Mississippian; in the Pennsylvanian they are first recorded in upland settings and finally, based on coal petrology, become extremely important in many Permian mire settings. These trends conform well to changes in atmospheric oxygen concentration, as predicted by modeling, and indicate oxygen levels are a significant control on long-term fire occurrence.

  8. Pressure dependence of spin-fluctuation effects in the specific heat of the heavy-fermion superconductor UPt3

    International Nuclear Information System (INIS)

    UPt3 is a heavy-fermion superconductor with indications of coexisting long-range ferromagnetic spin fluctuations. Measurements of its specific heat at pressures of 0, 3.8, and 8.9 kbar between 0.35 and 20 K show that the spin-fluctuation terms are extremely sensitive to pressure: the linear term decreases by --25% at 8.9 kbar; the T3 and T3 lnT terms decrease by factors of the order of 4. Comparison with the pressure dependence of the critical temperature suggests that the superconductivity is of a form that is enhanced by spin fluctuations

  9. On the permanent hip-stabilizing effect of atmospheric pressure.

    Science.gov (United States)

    Prietzel, Torsten; Hammer, Niels; Schleifenbaum, Stefan; Kaßebaum, Eric; Farag, Mohamed; von Salis-Soglio, Georg

    2014-08-22

    Hip joint dislocations related to total hip arthroplasty (THA) are a common complication especially in the early postoperative course. The surgical approach, the alignment of the prosthetic components, the range of motion and the muscle tone are known factors influencing the risk of dislocation. A further factor that is discussed until today is atmospheric pressure which is not taken into account in the present THA concepts. The aim of this study was to investigate the impact of atmospheric pressure on hip joint stability. Five joint models (Ø 28-44 mm), consisting of THA components were hermetically sealed with a rubber capsule, filled with a defined amount of fluid and exposed to varying ambient pressure. Displacement and pressure sensors were used to record the extent of dislocation related to intraarticular and ambient pressure. In 200 experiments spontaneous dislocations of the different sized joint models were reliably observed once the ambient pressure was lower than 6.0 kPa. Increasing the ambient pressure above 6.0 kPa immediately and persistently reduced the joint models until the ambient pressure was lowered again. Displacement always exceeded half the diameter of the joint model and was independent of gravity effects. This experimental study gives strong evidence that the hip joint is permanently stabilized by atmospheric pressure, confirming the theories of Weber and Weber (1836). On basis of these findings the use of larger prosthetic heads, capsular repair and the deployment of an intracapsular Redon drain are proposed to substantially decrease the risk of dislocation after THA.

  10. Atmospheric pressure and suicide attempts in Helsinki, Finland

    Science.gov (United States)

    Hiltunen, Laura; Ruuhela, Reija; Ostamo, Aini; Lönnqvist, Jouko; Suominen, Kirsi; Partonen, Timo

    2012-11-01

    The influence of weather on mood and mental health is commonly debated. Furthermore, studies concerning weather and suicidal behavior have given inconsistent results. Our aim was to see if daily weather changes associate with the number of suicide attempts in Finland. All suicide attempts treated in the hospitals in Helsinki, Finland, during two separate periods, 8 years apart, were included. Altogether, 3,945 suicide attempts were compared with daily weather parameters and analyzed with a Poisson regression. We found that daily atmospheric pressure correlated statistically significantly with the number of suicide attempts, and for men the correlation was negative. Taking into account the seasonal normal value during the period 1971-2000, daily temperature, global solar radiation and precipitation did not associate with the number of suicide attempts on a statistically significant level in our study. We concluded that daily atmospheric pressure may have an impact on suicidal behavior, especially on suicide attempts of men by violent methods ( P suicide attempts. Men seem to be more vulnerable to attempt suicide under low atmospheric pressure and women under high atmospheric pressure. We show only statistical correlations, which leaves the exact mechanisms of interaction between weather and suicidal behavior open. However, suicidal behavior should be assessed from the point of view of weather in addition to psychiatric and social aspects.

  11. Negative ion-atmospheric pressure photoionization-mass spectrometry

    NARCIS (Netherlands)

    Kauppila, T.J.; Kotiaho, T.; Kostiainen, R; Bruins, A.P.

    2004-01-01

    The ionization mechanism in the novel atmospheric pressure photoionization mass spectrometry (APPI-MS) in negative ion mode was studied thoroughly by the analysis of seven compounds in 17 solvent systems. The compounds possessed either gas-phase acidity or positive electron affinity, whereas the sol

  12. Atmospheric pressure plasma treatment of glassy carbon for adhesion improvement

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Mortensen, Henrik Junge; Stenum, Bjarne;

    2007-01-01

    Glassy carbon plates were treated with an atmospheric pressure dielectric barrier discharge (DBD). He gas, gas mixtures of He and reactive gases such as O2, CO2 and NH3, Ar gas and Ar/NH3 gas mixture were used as treatment gases. The oxygen and nitrogen contents on the surface as well as defect...

  13. Einstein's Tea Leaves and Pressure Systems in the Atmosphere

    Science.gov (United States)

    Tandon, Amit; Marshall, John

    2010-01-01

    Tea leaves gather in the center of the cup when the tea is stirred. In 1926 Einstein explained the phenomenon in terms of a secondary, rim-to-center circulation caused by the fluid rubbing against the bottom of the cup. This explanation can be connected to air movement in atmospheric pressure systems to explore, for example, why low-pressure…

  14. Atmospheric pressure and suicide attempts in Helsinki, Finland.

    Science.gov (United States)

    Hiltunen, Laura; Ruuhela, Reija; Ostamo, Aini; Lönnqvist, Jouko; Suominen, Kirsi; Partonen, Timo

    2012-11-01

    The influence of weather on mood and mental health is commonly debated. Furthermore, studies concerning weather and suicidal behavior have given inconsistent results. Our aim was to see if daily weather changes associate with the number of suicide attempts in Finland. All suicide attempts treated in the hospitals in Helsinki, Finland, during two separate periods, 8 years apart, were included. Altogether, 3,945 suicide attempts were compared with daily weather parameters and analyzed with a Poisson regression. We found that daily atmospheric pressure correlated statistically significantly with the number of suicide attempts, and for men the correlation was negative. Taking into account the seasonal normal value during the period 1971-2000, daily temperature, global solar radiation and precipitation did not associate with the number of suicide attempts on a statistically significant level in our study. We concluded that daily atmospheric pressure may have an impact on suicidal behavior, especially on suicide attempts of men by violent methods (P atmospheric pressure and women under high atmospheric pressure. We show only statistical correlations, which leaves the exact mechanisms of interaction between weather and suicidal behavior open. However, suicidal behavior should be assessed from the point of view of weather in addition to psychiatric and social aspects.

  15. Spacecraft Sterilization Using Non-Equilibrium Atmospheric Pressure Plasma

    Science.gov (United States)

    Cooper, Moogega; Vaze, Nachiket; Anderson, Shawn; Fridman, Gregory; Vasilets, Victor N.; Gutsol, Alexander; Tsapin, Alexander; Fridman, Alexander

    2007-01-01

    As a solution to chemically and thermally destructive sterilization methods currently used for spacecraft, non-equilibrium atmospheric pressure plasmas are used to treat surfaces inoculated with Bacillus subtilis and Deinococcus radiodurans. Evidence of significant morphological changes and reduction in viability due to plasma exposure will be presented, including a 4-log reduction of B. subtilis after 2 minutes of dielectric barrier discharge treatment.

  16. Fluctuation pressure on a bio-membrane confined within a parabolic potential well

    Institute of Scientific and Technical Information of China (English)

    L. B. Freund

    2012-01-01

    A compliant bio-membrane with a nominally flat reference configuration is prone to random transverse deflections when placed in water,due primarily to the Brownian motion of the water molecules.On the average,these fluctuations result in a state of thermodynamic equilibrium between the entropic energy of the water and the total free energy of the membrane.When the membrane is in close proximity to a parallel surface,that surface restricts the fluctuations of the membrane which,in turn,results in an increase in its free energy.The amount of that increase depends on the degree of confinement,and the resulting gradient in free energy with degree of confinement implies the existence of a confining pressure.In the present study,we assume that the confinement is in the form of a continuous parabolic potential well resisting fluctuation.Analysis leads to a closed form expression for the mean pressure resulting from this confinement,and the results are discussed within the broader context of results in this area.In particular,the results provide insights into the roles of membrane stiffness,number of degrees of freedom in the model of the membrane and other system parameters.

  17. Atmospheric-pressure guided streamers for liposomal membrane disruption

    Science.gov (United States)

    Svarnas, P.; Matrali, S. H.; Gazeli, K.; Aleiferis, Sp.; Clément, F.; Antimisiaris, S. G.

    2012-12-01

    The potential to use liposomes (LIPs) as a cellular model in order to study interactions of cold atmospheric-pressure plasma with cells is herein investigated. Cold atmospheric-pressure plasma is formed by a dielectric-barrier discharge reactor. Large multilamellar vesicle liposomes, consisted of phosphatidylcholine and cholesterol, are prepared by the thin film hydration technique, to encapsulate a small hydrophilic dye, i.e., calcein. The plasma-induced release of calcein from liposomes is then used as a measure of liposome membrane integrity and, consequently, interaction between the cold atmospheric plasma and lipid bilayers. Physical mechanisms leading to membrane disruption are suggested, based on the plasma characterization including gas temperature calculation.

  18. Atmospheric-pressure guided streamers for liposomal membrane disruption

    Energy Technology Data Exchange (ETDEWEB)

    Svarnas, P.; Aleiferis, Sp. [High Voltage Laboratory, Department of Electrical and Computer Engineering, University of Patras, Rion 26504 (Greece); Matrali, S. H. [Pharmaceutical Technology Laboratory, Department of Pharmacy, University of Patras, Rion 26504 (Greece); Gazeli, K. [High Voltage Laboratory, Department of Electrical and Computer Engineering, University of Patras, Rion 26504 (Greece); IPREM-LCABIE, Plasmas et Applications, UPPA, 64000 Pau (France); Clement, F. [IPREM-LCABIE, Plasmas et Applications, UPPA, 64000 Pau (France); Antimisiaris, S. G. [Pharmaceutical Technology Laboratory, Department of Pharmacy, University of Patras, Rion 26504 (Greece); Institute of Chemical Engineering Sciences (ICES)-FORTH, Rion 26504 (Greece)

    2012-12-24

    The potential to use liposomes (LIPs) as a cellular model in order to study interactions of cold atmospheric-pressure plasma with cells is herein investigated. Cold atmospheric-pressure plasma is formed by a dielectric-barrier discharge reactor. Large multilamellar vesicle liposomes, consisted of phosphatidylcholine and cholesterol, are prepared by the thin film hydration technique, to encapsulate a small hydrophilic dye, i.e., calcein. The plasma-induced release of calcein from liposomes is then used as a measure of liposome membrane integrity and, consequently, interaction between the cold atmospheric plasma and lipid bilayers. Physical mechanisms leading to membrane disruption are suggested, based on the plasma characterization including gas temperature calculation.

  19. An Experimental Study of the Statistical Scaling of Turbulent Surface Pressure in the Atmospheric Boundary Layer

    Science.gov (United States)

    Lyons, G. W.; Murray, N. E.

    2015-12-01

    Turbulence in the atmospheric boundary layer (ABL) produces fluctuations in the static pressure. The instantaneous pressure at a point depends on an integral over the entire flow; therefore, the effects from turbulence far aloft may be felt at the earth's surface. The statistics of fluctuating pressure at the surface have been studied extensively in the context of wall-bounded engineering-type flows. At best, these neutral flows are a special case of the thermally-stratified ABL, but relatively few experimental studies have considered pressure at the ground under various stability conditions. Here the scaling of pressure statistics at the surface, particularly the spectral density, is reported over a range of convective and stable conditions for both inner and outer turbulence parameters. Measurements of turbulent surface pressure were made using low-frequency microphones buried flush to the ground in a field near Laramie, Wyoming. Simultaneous measurements from three near-surface sonic anemometers and a 50-meter wind tower give estimates of the mean surface-layer parameters. The normalization of the pressure spectrum with the inner scales collapses the spectra along the high-frequency viscous power-law band. The wall shear stress, Obukhov length, L, and horizontal integral scale, λ, are identified as outer scaling parameters for the surface pressure spectrum from an integral solution employing a Monin-Obukhov-similar profile and a simple model of inhomogeneous surface-layer turbulence. Normalization with the outer scales collapses the spectra at low frequencies. Spectral scaling also reveals trends with λ/L in the low-frequency region for both convective and stable boundary layers.

  20. Ir/thz Double Resonance Signatures at Atmospheric Pressure

    Science.gov (United States)

    Phillips, Dane J.; Tanner, Elizabeth A.; Everitt, Henry O.; Medvedev, Ivan R.; Neese, Christopher F.; Holt, Jennifer; De Lucia, Frank C.

    2010-06-01

    IR/THz double resonance (DR) spectroscopy, historically used to investigate molecular collision dynamics and THz molecular lasers at low pressures (remote sensing at atmospheric pressure. Molecular specificity is obtained through the rare coincidence(s) between molecule-specific ro-vibrational energy levels and CO2 laser lines. The resulting molecule-specific, DR-induced, THz spectroscopic signatures strongly depend on the type of ro-vibrational transition involved (P, Q, or R), the type of vibrational level excited (stretching or bending), and the molecular mass. To illustrate these sensitivities, calculated DR spectra of prototypical molecules such as methyl fluoride, methyl chloride, and methyl cyanide will be discussed. Although atmospheric pressure broadening obfuscates pure rotational spectra, we show how it can enhance the DR signature in two ways: by relaxing the pump coincidence requirement and by adding the DR signatures of multiple nearby transitions. We will present estimates of this enhancement, including cases where the coincidences that produce the strongest DR signatures at atmospheric pressure do not exist at low pressures.

  1. Quality characteristics of the radish grown under reduced atmospheric pressure

    Science.gov (United States)

    Levine, Lanfang H.; Bisbee, Patricia A.; Richards, Jeffrey T.; Birmele, Michele N.; Prior, Ronald L.; Perchonok, Michele; Dixon, Mike; Yorio, Neil C.; Stutte, Gary W.; Wheeler, Raymond M.

    This study addresses whether reduced atmospheric pressure (hypobaria) affects the quality traits of radish grown under such environments. Radish (Raphanus sativus L. cv. Cherry Bomb Hybrid II) plants were grown hydroponically in specially designed hypobaric plant growth chambers at three atmospheric pressures; 33, 66, and 96 kPa (control). Oxygen and carbon dioxide partial pressures were maintained constant at 21 and 0.12 kPa, respectively. Plants were harvested at 21 days after planting, with aerial shoots and swollen hypocotyls (edible portion of the radish referred to as the “root” hereafter) separated immediately upon removal from the chambers. Samples were subsequently evaluated for their sensory characteristics (color, taste, overall appearance, and texture), taste-determining factors (glucosinolate and soluble carbohydrate content and myrosinase activity), proximate nutrients (protein, dietary fiber, and carbohydrate) and potential health benefit attributes (antioxidant capacity). In roots of control plants, concentrations of glucosinolate, total soluble sugar, and nitrate, as well as myrosinase activity and total antioxidant capacity (measured as ORACFL), were 2.9, 20, 5.1, 9.4, and 1.9 times greater than the amount in leaves, respectively. There was no significant difference in total antioxidant capacity, sensory characteristics, carbohydrate composition, or proximate nutrient content among the three pressure treatments. However, glucosinolate content in the root and nitrate concentration in the leaf declined as the atmospheric pressure decreased, suggesting perturbation to some nitrogen-related metabolism.

  2. Pressure dependence of critical temperature of bulk FeSe from spin fluctuation theory

    Science.gov (United States)

    Hirschfeld, Peter; Kreisel, Andreas; Wang, Yan; Tomic, Milan; Jeschke, Harald; Jacko, Anthony; Valenti, Roser; Maier, Thomas; Scalapino, Douglas

    2013-03-01

    The critical temperature of the 8K superconductor FeSe is extremely sensitive to pressure, rising to a maximum of 40K at about 10GPa. We test the ability of the current generation of fluctuation exchange pairing theories to account for this effect, by downfolding the density functional theory electronic structure for each pressure to a tight binding model. The Fermi surface found in such a procedure is then used with fixed Hubbard parameters to determine the pairing strength using the random phase approximation for the spin singlet pairing vertex. We find that the evolution of the Fermi surface captured by such an approach is alone not sufficient to explain the observed pressure dependence, and discuss alternative approaches. PJH, YW, AK were supported by DOE DE-FG02-05ER46236, the financial support of MT, HJ, and RV from the DFG Schwerpunktprogramm 1458 is kindly acknowledged.

  3. Pressure and temperature fluctuation simulation of J-PARC cryogenic hydrogen system

    Science.gov (United States)

    Tatsumoto, H.; Ohtsu, K.; Aso, T.; Kawakami, Y.

    2015-12-01

    The J-PARC cryogenic hydrogen system provides supercritical cryogenic hydrogen to the moderators at a pressure of 1.5 MPa and temperature of 18 K and removes 3.8 kW of nuclear heat from the 1 MW proton beam operation. We prepared a heater for thermal compensation and an accumulator, with a bellows structure for volume control, to mitigate the pressure fluctuation caused by switching the proton beam on and off. In this study, a 1-D simulation code named DiSC-SH2 was developed to understand the propagation of pressure and temperature propagations through the hydrogen loop due to on and off switching of the proton beam. We confirmed that the simulated dynamic behaviors in the hydrogen loop for 300-kW and 500-kW proton beam operations agree well with the experimental data under the same conditions.

  4. A Micromachined Pressure Sensor with Integrated Resonator Operating at Atmospheric Pressure

    Directory of Open Access Journals (Sweden)

    Sen Ren

    2013-12-01

    Full Text Available A novel resonant pressure sensor with an improved micromechanical double-ended tuning fork resonator packaged in dry air at atmospheric pressure is presented. The resonator is electrostatically driven and capacitively detected, and the sensor is designed to realize a low cost resonant pressure sensor with medium accuracy. Various damping mechanisms in a resonator that is vibrating at atmospheric pressure are analyzed in detail, and a formula is developed to predict the overall quality factor. A trade-off has been reached between the quality factor, stress sensitivity and drive capability of the resonator. Furthermore, differential sense elements and the method of electromechanical amplitude modulation are used for capacitive detection to obtain a large signal-to-noise ratio. The prototype sensor chip is successfully fabricated using a micromachining process based on a commercially available silicon-on-insulator wafer and is hermetically encapsulated in a custom 16-pin Kovar package. Preliminary measurements show that the fundamental frequency of the resonant pressure sensor is approximately 34.55 kHz with a pressure sensitivity of 20.77 Hz/kPa. Over the full scale pressure range of 100–400 kPa and the whole temperature range of −20–60 °C, high quality factors from 1,146 to 1,772 are obtained. The characterization of the prototype sensor reveals the feasibility of a resonant pressure sensor packaged at atmospheric pressure.

  5. Atmospheric pressure loading parameters from very long baseline interferometry observations

    Science.gov (United States)

    Macmillan, D. S.; Gipson, John M.

    1994-01-01

    Atmospheric mass loading produces a primarily vertical displacement of the Earth's crust. This displacement is correlated with surface pressure and is large enough to be detected by very long baseline interferometry (VLBI) measurements. Using the measured surface pressure at VLBI stations, we have estimated the atmospheric loading term for each station location directly from VLBI data acquired from 1979 to 1992. Our estimates of the vertical sensitivity to change in pressure range from 0 to -0.6 mm/mbar depending on the station. These estimates agree with inverted barometer model calculations (Manabe et al., 1991; vanDam and Herring, 1994) of the vertical displacement sensitivity computed by convolving actual pressure distributions with loading Green's functions. The pressure sensitivity tends to be smaller for stations near the coast, which is consistent with the inverted barometer hypothesis. Applying this estimated pressure loading correction in standard VLBI geodetic analysis improves the repeatability of estimated lengths of 25 out of 37 baselines that were measured at least 50 times. In a root-sum-square (rss) sense, the improvement generally increases with baseline length at a rate of about 0.3 to 0.6 ppb depending on whether the baseline stations are close to the coast. For the 5998-km baseline from Westford, Massachusetts, to Wettzell, Germany, the rss improvement is about 3.6 mm out of 11.0 mm. The average rss reduction of the vertical scatter for inland stations ranges from 2.7 to 5.4 mm.

  6. Radiometric correction of atmospheric path length fluctuations in interferometric experiments. [in radio astronomy

    Science.gov (United States)

    Resch, G. M.; Hogg, D. E.; Napier, P. J.

    1984-01-01

    To support very long baseline interferometric experiments, a system has been developed for estimating atmospheric water vapor path delay. The system consists of dual microwave radiometers, one operating at 20.7 GHz and the other at 31.4 GHz. The measured atmospheric brightness temperatures at these two frequencies yield the estimate of the precipitable water present in both vapor and droplets. To determine the accuracy of the system, a series of observations were undertaken, comparing the outputs of two water vapor radiometers with the phase variation observed with two connected elements of the very large array (VLA). The results show that: (1) water vapor fluctuations dominate the residual VLA phase and (2) the microwave radiometers can measure and correct these effects. The rms phase error after correction is typically 15 deg at a wavelength of 6 cm, corresponding to an uncertainty in the path delay of 0.25 cm. The residual uncertainty is consistent with the stability of the microwave radiometer but is still considerably larger than the stability of the VLA. The technique is less successful under conditions of heavy cloud.

  7. Numerical study of pressure fluctuations transfer law in different flow rate of turbine mode in a prototype pump turbine

    International Nuclear Information System (INIS)

    Numerical simulation using SST k-w turbulence model was carried out, to predict pressure fluctuation transfer law in turbine mode. Three operating points with different mass flow rates are simulated. The results of numerical simulation show that, the amplitude and frequency of pressure fluctuations in different positions are very different. The transfer law of amplitude and frequency of pressure fluctuations change with different position and different mass flow rate. Blade passing frequency (BPF) is the first dominant frequency in vaneless space, while component in this frequency got smaller in the upstream and downstream of vaneless space when the mass flow is set. Furthermore triple blade passing frequency (3BPF) component obtained a different transfer law through the whole flow passage. The amplitude and frequency of pressure fluctuations is also different in different circumference position of vaneless space. When the mass flow is different, the distribution of pressure fluctuations in circumference is different. The frequency component of pressure fluctuations in all the positions is different too

  8. Pressure Fluctuations in the Gasostatic Bearing Supply System on Supercritical Operation Mode

    Directory of Open Access Journals (Sweden)

    Prodan Nikolay Vasilevich

    2014-07-01

    Full Text Available This study discusses the oscillatory mode occurring in the gap between the stator and the rotor in gas-static bearing during the outflow of under expanded gas jets out of the supply system, which interacts with the surface of the rotor. The results of studies on the oscillation regimes, their causes, mechanisms and frequency characteristics of pressure fluctuations in the working fluid supply system and the lubricating layer of gas bearing. A one-dimensional model of central shock oscillations in a gas jet leaking on a perpendicular barrier is considered. Experiments were carried out. The regions, where oscillation regimes exist are revealed.

  9. Fluctuating pressures on wing surfaces in the slipstream of a single-rotor propfan

    Science.gov (United States)

    Swift, G.; Bartel, H. W.

    1989-04-01

    Measurements of the fluctuating pressure levels (FPLs) induced on a Propfan Test Assessment wing by the SR-7L propfan slipstream within the airplane flight envelope were obtained as a function of propfan operating conditions. It is shown that FPLS were high over most of the flight envelope, and that the spectra were dominated by the propfan first-order blade passage frequency tone. The highest FPLs were found at the lowest aircraft test altitudes and Mach numbers and for propfan conditions of lowest rotational tip speed and highest power.

  10. Large-scale fluctuations in Precambrian atmospheric and oceanic oxygen levels from the record of U in shales

    Science.gov (United States)

    Partin, C. A.; Bekker, A.; Planavsky, N. J.; Scott, C. T.; Gill, B. C.; Li, C.; Podkovyrov, V.; Maslov, A.; Konhauser, K. O.; Lalonde, S. V.; Love, G. D.; Poulton, S. W.; Lyons, T. W.

    2013-05-01

    The atmosphere-ocean system experienced a progressive change from anoxic to more oxidizing conditions through time. This oxidation is traditionally envisaged to have occurred as two stepwise increases in atmospheric oxygen at the beginning and end of the Proterozoic Eon. Here, we present a study of the redox-sensitive element, uranium, in organic-rich shales to track the history of Earth's surface oxidation at an unprecedented temporal resolution. Fluctuations in the degree of uranium enrichment in organic-rich shales suggest that the initial rise of atmospheric oxygen ~2.4 billion yr ago was followed by a decline to less oxidizing conditions during the mid-Proterozoic. This redox state persisted for almost 1 billion yr, ending with a second oxygenation event in the latest Neoproterozoic. The U record tracks major fluctuations in surface oxygen level and challenges conventional models that suggest the Earth underwent a unidirectional rise in atmospheric oxygen during the Precambrian.

  11. Characteristic analysis on the pressure fluctuation in the impeller of a low specific speed mixed flow pump

    Science.gov (United States)

    Zhang, W. W.; Yu, Z. Y.; Zhu, B. S.

    2016-05-01

    To explore the pressure fluctuation characteristics of a low speed specific speed mixed flow pump caused by rotor-stator interaction, the unsteady flow was simulated with CFX for the whole flow passage of a mixed flow pump with a specific speed of 148.8. The structured mesh of the computation domain was generated with ICEM CFD and TurboGrid, and mesh-independent analysis was done in the design condition. Through the comparison with the experiment data, the reliability of the simulation was verified. In different locations of the impeller passage, monitoring points were set. With Fast Fourier Transform (FFT), the characteristic analysis on the pressure fluctuation in the impeller passage was done for three flow rate conditions (0.75Qd, Qd, 1.25Qd). The results show that the pressure fluctuation amplitude increases from the inlet to the outlet. And the maximum values in different flow rates exist near the hub of the outlet; The pressure fluctuation is small in the design condition, but the largest in the small flow rate condition, accompanied by the secondary dominant frequencies with large amplitudes; In the small flow rate condition and design condition, the dominant frequency varies from the inlet to the outlet because the combine action of the impeller and guide vane; while in the large flow rate condition, the pressure fluctuation in the whole impeller passage is affected significantly by the guide vane, and the domain frequency is 8 times the rotational frequency of impeller. In addition, the change of pressure fluctuation from the pressure surface to the suction surface in the off-design conditions is investigated, and the results demonstrates that the intensity of the pressure fluctuation in the impeller passage is closely related with the impeller as well as the distribution of the vorticity and the pressure.

  12. Optimizing a remote sensing instrument to measure atmospheric surface pressure

    Science.gov (United States)

    Peckham, G. E.; Gatley, C.; Flower, D. A.

    1983-01-01

    Atmospheric surface pressure can be remotely sensed from a satellite by an active instrument which measures return echoes from the ocean at frequencies near the 60 GHz oxygen absorption band. The instrument is optimized by selecting its frequencies of operation, transmitter powers and antenna size through a new procedure baesd on numerical simulation which maximizes the retrieval accuracy. The predicted standard deviation error in the retrieved surface pressure is 1 mb. In addition the measurements can be used to retrieve water vapor, cloud liquid water and sea state, which is related to wind speed.

  13. Dynamics behavior of homogeneous dielectric barrier discharge at atmospheric pressure

    Science.gov (United States)

    Zhang, Yan; Gu, Biao; Wang, Wenchun; Wang, Dezhen; Peng, Xuwen

    2009-07-01

    An experimental study on the dynamics behavior of homogeneous dielectric barrier discharge (HDBD) at atmospheric pressure is described in this paper. Two kinds of discharge mode, glow and Townsend discharge modes, can be easily identified according to the differential conductivity of current-voltage relationship in the ascent stage of discharge current for the atmospheric HDBD. A (three-dimensional) 3D phase space made by discharge current, gas gap voltage, and charge density of dielectric-plate surface was utilized in the study. By projecting the discharge evolution trajectory in the 3D space, the 3D trajectory of multiple current peaks discharge in atmospheric helium shows a limited cycle with convolutions and undergoes a series of bifurcation process; however, the 3D trajectory of atmospheric N2 HDBD is a limited cycle without any convolution and bifurcation process. In addition, the first ionization coefficient of working gas plays a key role to determine the discharge mode of atmospheric HDBD, the transition of discharge mode and the dynamics stability of atmospheric HDBD.

  14. Pressure fluctuation prediction of a model pump turbine at no load opening by a nonlinear k-ε turbulence model

    International Nuclear Information System (INIS)

    In this paper, a new nonlinear k-ε turbulence model based on RNG k-ε turbulence model and Wilcox's k-ω turbulence model was proposed to simulate the unsteady flow and to predict the pressure fluctuation through a model pump turbine for engineering application. Calculations on a curved rectangular duct proved that the nonlinear k-ε turbulence model is applicable for high pressure gradient flows and large curvature flows. The numerically predicted relative pressure amplitude (peak to peak) in time domain to the pump turbine head at no load condition is very close to the experimental data. It is indicated that the prediction of the pressure fluctuation is valid by the present nonlinear k-ε method. The high pressure fluctuation in this area is the main issue for pump turbine design, especially at high head condition

  15. Microwave-assisted atmospheric pressure plasma polymerization of hexamethyldisiloxane

    Science.gov (United States)

    Matsubayashi, Toshiki; Hidaka, Hiroki; Muguruma, Hitoshi

    2016-07-01

    Microwave-assisted atmospheric pressure plasma polymerization is presented. A system with a re-entrant microwave cavity realizes simple matching, stable plasma, and free space under the orifice of plasma steam. Hexamethyldisiloxane is employed as a monomer, while argon is used as a carrier gas. The effective area of the hydrophobic coating film used corresponds to a circle of 20 mm diameter and the deposition rate considered is 5 nm/min. Matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy shows that the coating film has a large molecular weight (>200 kDa), suggesting that a high-crosslinking and three-dimensional polymer matrix is formed and microwave-assisted atmospheric pressure plasma polymerization is fulfilled.

  16. Ferrous alloys cast under high pressure gas atmosphere

    Directory of Open Access Journals (Sweden)

    Pirowski Z.

    2007-01-01

    Full Text Available The main objective of this paper is describing the essence of the process of introducing nitrogen to the melt of ferrous alloys by application of overpressure above the metal bath. The problem was discussed in terms of both theory (the thermodynamic aspects of the process and practice (the technical and technological aspects, safety of the furnace stand operation, and technique of conducting the melt. The novel technique of melting under high pressure of the gas atmosphere (up to 5 MPa has not been used so far in the domestic industry, mainly because of the lack of proper equipment satisfyng the requirements of safe operation. Owing to cooperation undertaken with a partner from Bulgaria, a more detailed investigation of this technology has become possible and melting of selected ferrous alloys was conducted under the gas atmosphere at a pressure of about 3,5 MPa.

  17. Simulation of low temperature atmospheric pressure corona discharge in helium

    Science.gov (United States)

    Bekasov, Vladimir; Kirsanov, Gennady; Eliseev, Stepan; Kudryavtsev, Anatoly; Sisoev, Sergey

    2015-11-01

    The main objective of this work was to construct a numerical model of corona discharge in helium at atmospheric pressure. The calculation was based on the two-dimensional hybrid model. Two different plasma-chemical models were considered. Models were built for RF corona and negative DC corona discharge. The system of equations is solved by the finite element method in the COMSOL Multiphysics. Main parameters of the discharge (the density of charged and excited particles, the electron temperature) and their dependence on the input parameters of the model (geometry, electrode voltage, power) were calculated. The calculations showed that the shape of the electron distribution near the electrode depends on the discharge power. The neutral gas heating data obtained will allow predicting the temperature of the gases at the designing of atmospheric pressure helium plasma sources.

  18. Cellular membrane collapse by atmospheric-pressure plasma jet

    Science.gov (United States)

    Kim, Kangil; Jun Ahn, Hak; Lee, Jae-Hyeok; Kim, Jae-Ho; Sik Yang, Sang; Lee, Jong-Soo

    2014-01-01

    Cellular membrane dysfunction caused by air plasma in cancer cells has been studied to exploit atmospheric-pressure plasma jets for cancer therapy. Here, we report that plasma jet treatment of cervical cancer HeLa cells increased electrical conductivity across the cellular lipid membrane and caused simultaneous lipid oxidation and cellular membrane collapse. We made this finding by employing a self-manufactured microelectrode chip. Furthermore, increased roughness of the cellular lipid membrane and sequential collapse of the membrane were observed by atomic force microscopy following plasma jet treatment. These results suggest that the cellular membrane catastrophe occurs via coincident altered electrical conductivity, lipid oxidation, and membrane roughening caused by an atmospheric-pressure plasma jet, possibly resulting in cellular vulnerability to reactive species generated from the plasma as well as cytotoxicity to cancer cells.

  19. Cellular membrane collapse by atmospheric-pressure plasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kangil; Sik Yang, Sang, E-mail: jsjlee@ajou.ac.kr, E-mail: ssyang@ajou.ac.kr [Department of Electrical and Computer Engineering, Ajou University, Suwon 443-749 (Korea, Republic of); Jun Ahn, Hak; Lee, Jong-Soo, E-mail: jsjlee@ajou.ac.kr, E-mail: ssyang@ajou.ac.kr [Department of Biological Sciences, Ajou University, Suwon 443-749 (Korea, Republic of); Lee, Jae-Hyeok; Kim, Jae-Ho [Department of Molecular Science and Technology, Ajou University, Suwon 443-749 (Korea, Republic of)

    2014-01-06

    Cellular membrane dysfunction caused by air plasma in cancer cells has been studied to exploit atmospheric-pressure plasma jets for cancer therapy. Here, we report that plasma jet treatment of cervical cancer HeLa cells increased electrical conductivity across the cellular lipid membrane and caused simultaneous lipid oxidation and cellular membrane collapse. We made this finding by employing a self-manufactured microelectrode chip. Furthermore, increased roughness of the cellular lipid membrane and sequential collapse of the membrane were observed by atomic force microscopy following plasma jet treatment. These results suggest that the cellular membrane catastrophe occurs via coincident altered electrical conductivity, lipid oxidation, and membrane roughening caused by an atmospheric-pressure plasma jet, possibly resulting in cellular vulnerability to reactive species generated from the plasma as well as cytotoxicity to cancer cells.

  20. Thermally induced atmospheric pressure gas discharges using pyroelectric crystals

    Science.gov (United States)

    Johnson, Michael J.; Linczer, John; Go, David B.

    2014-12-01

    Using a heated pyroelectric crystal, an atmospheric pressure gas discharge was generated through the input of heat. When put through a change in temperature, the polarization of a pyroelectric can change significantly, creating a substantial electric potential at its surface. When configured with a grounded sharp counter electrode, a large inhomogeneous electric field forms in the interstitial gas to initiate a corona-like discharge. Under constant heating conditions, gaseous ions drifting to the pyroelectric accumulate and screen the electric field, extinguishing the discharge. By thermally cycling the pyroelectric, negative and positive discharges are generated during heating and cooling, respectively, with peak currents on the order of 80 nA. Time-integrated visualization confirmed the generation of both a corona-like discharge and a surface discharge on the pyroelectric. Parametric studies identified that thermal cycling conditions significantly influence discharge formation for this new atmospheric pressure discharge approach.

  1. Removal of paper microbial contamination by atmospheric pressure DBD discharge

    Science.gov (United States)

    Vrajova, J.; Chalupova, L.; Novotny, O.; Cech, J.; Krcma, F.; Stahel, P.

    2009-08-01

    In this paper the removal of the microbial contamination from paper material using the plasma treatment at atmospheric pressure is investigated. The Aspergillus niger has been chosen as a bio-indicator enabling to evaluate the effect of plasma assisted microbial inactivation. Dielectric barrier discharge (DBD) operated at atmospheric pressure was used for the paper sterilization. The working gas (nitrogen, argon and helium), plasma exposition time and the plasma power density were varied in order to see the effect of the plasma treatment on the fungi removal. After the treatment, the microbial abatement was evaluated by the standard plate count method. This proved a positive effect of the DBD plasma treatment on fungi removal. Morphological and colorimetric changes of paper substrate after plasma treatment were also investigated.

  2. Relationship of Early Spontaneous Type V Blood Pressure Fluctuation after Thrombolysis in Acute Cerebral Infarction Patients and the Prognosis.

    Science.gov (United States)

    Zuo, Lian; Wan, Ting; Xu, Xiahong; Liu, Feifeng; Li, Changsong; Li, Ying; Zhang, Yue; Zhang, Jing; Bao, Huan; Li, Gang

    2016-01-01

    We examined the relationship between an early spontaneous type V blood pressure fluctuation and the post-thrombolysis prognosis of patients with acute cerebral infarction. Patients were admitted consecutively. All patients were categorized into the type V blood pressure fluctuation group or non-type V blood pressure group. Their blood pressure was monitored before thrombolysis and until 6 h after thrombolysis. Baseline data and clinical outcomes were compared. Of 170 patients, 43 (25.2%) had an early type V blood pressure fluctuation. The National Institute of Health Stroke Scale (NIHSS) score before thrombolysis and 24 h after thrombolysis, and the modified Rankin scale score at 90 days differed significantly between the two groups (P V blood pressure fluctuation is common in patients with acute cerebral infarction who received venous thrombolysis, especially if they have a higher NIHSS score before thrombolysis. The type V blood pressure fluctuation may not influence patients' prognosis; however, this needs to be confirmed in future trials. PMID:27278121

  3. Plasma deposition of thiophene derivatives under atmospheric pressure

    OpenAIRE

    DAMS, Roel; VANGENEUGDEN, Dirk; Vanderzande, Dirk

    2006-01-01

    Plasma deposition of conjugated polymer films under atmospheric pressure is described. Three thiophene derivatives (thiophene, 3-methylthiophene, and 3,4-ethylenedioxythiophene) are used as monomers. The plasma depositions with the various precursors are compared using analytical techniques such as X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, UV-vis spectroscopy, and resistance measurements. Good results are obtained with pulsed plasma depositions of...

  4. Laser ablation of zirconium in gas atmospheres at low pressures

    International Nuclear Information System (INIS)

    Pulsed nitrogen laser induced ablation of solid zirconium targets was monitored using laser induced fluorescence. Starting from 'new' surfaces, the density evolution under the influence of different gas atmospheres (oxygen, helium, hydrogen and nitrogen) with pressures up to 10-3 mbar has been studied. It was observed that even small amounts of gas lead to a large increase in the velocity and the density of the ablated atomic cloud. (author)

  5. Atmospheric oxygenation caused by a change in volcanic degassing pressure.

    Science.gov (United States)

    Gaillard, Fabrice; Scaillet, Bruno; Arndt, Nicholas T

    2011-10-12

    The Precambrian history of our planet is marked by two major events: a pulse of continental crust formation at the end of the Archaean eon and a weak oxygenation of the atmosphere (the Great Oxidation Event) that followed, at 2.45 billion years ago. This oxygenation has been linked to the emergence of oxygenic cyanobacteria and to changes in the compositions of volcanic gases, but not to the composition of erupting lavas--geochemical constraints indicate that the oxidation state of basalts and their mantle sources has remained constant since 3.5 billion years ago. Here we propose that a decrease in the average pressure of volcanic degassing changed the oxidation state of sulphur in volcanic gases, initiating the modern biogeochemical sulphur cycle and triggering atmospheric oxygenation. Using thermodynamic calculations simulating gas-melt equilibria in erupting magmas, we suggest that mostly submarine Archaean volcanoes produced gases with SO(2)/H(2)S atmosphere.

  6. Effects of Shelves on Amplification of Long Waves Generated by Atmospheric Pressure Differences

    Science.gov (United States)

    Duha Metin, Ayse; Cevdet Yalciner, Ahmet; Ozyurt Tarakcıoglu, Gulizar; Zaytsev, Andrey

    2016-04-01

    Meteotsunami is a type of long period ocean wave generated by different types of meteorological disturbances such as atmospheric gravity waves, spatial and temporal pressure distributions and squall lines. The main idea behind the occurrence of this type of long wave is that low atmospheric pressure leads to static water level rise in a part of the marine area and high atmospheric pressure leads to static water level drop in another zone. Then, it causes deformation of the water level throughout the entire sea area. The relation between the pressure difference and change of water level from normal position (η =0.99Δ P where η is the water level change (cm) according to the pressure difference from normal pressure Δ P) can be used to determine the sea level deformation. The relation represents that 1 hPa decrease in air pressure causes 1 cm rise in mean sea level. Due to the spatial and temporal changes of atmospheric pressure, the respective small amplitude long waves propagate along the entire marine area. This type of tsunami-like waves can propagate through long distances and can also be amplified due to resonant effects in the enclosed basins, offshore shelves, and nearshore/offshore coastal morphology. Therefore, it can result in considerable amplifications and causes unexpected effects in some coastal regions. This study is mainly focused on understanding of amplification of long waves generated by atmospheric pressure differences when they encounter the offshore shelves while it is propagating towards to the shore. The problem is investigated by numerically solving nonlinear shallow water equations by using regular shaped basins with different depth and shelf characteristics. In all cases, the rectangular shape large basin is triggered by spatial and temporal distributions of atmospheric pressure. The water depth and shelf formation is changed for different cases. Initially, a deep flat bottom basin is used in simulations and the reference data of water

  7. Load variation effects on the pressure fluctuations exerted on a Kaplan turbine runner

    International Nuclear Information System (INIS)

    Introduction of intermittent electricity production systems like wind power and solar systems to electricity market together with the consumption-based electricity production resulted in numerous start/stops, load variations and off-design operation of water turbines. The hydropower systems suffer from the varying loads exerted on the stationary and rotating parts of the turbines during load variations which they are not designed for. On the other hand, investigations on part load operation of single regulated turbines, i.e., Francis and propeller, proved the formation of rotating vortex rope (RVR) in the draft tube. The RVR induces oscillating flow both in plunging and rotating modes which results in oscillating force with two different frequencies on the runner blades, bearings and other rotating parts of the turbine. The purpose of this study is to investigate the effect of transient operations on the pressure fluctuations on the runner and mechanism of the RVR formation/mitigation. Draft tube and runner blades of the Porjus U9 model, a Kaplan turbine, were equipped with pressure sensors. The model was run in off-cam mode during different load variation conditions to check the runner performance under unsteady condition. The results showed that the transients between the best efficiency point and the high load happens in a smooth way while transitions to/from the part load, where rotating vortex rope (RVR) forms in the draft tube induces high level of fluctuations with two frequencies on the runner; plunging and rotating mode of the RVR

  8. Load variation effects on the pressure fluctuations exerted on a Kaplan turbine runner

    Science.gov (United States)

    Amiri, K.; Mulu, B.; Raisee, M.; Cervantes, M. J.

    2014-03-01

    Introduction of intermittent electricity production systems like wind power and solar systems to electricity market together with the consumption-based electricity production resulted in numerous start/stops, load variations and off-design operation of water turbines. The hydropower systems suffer from the varying loads exerted on the stationary and rotating parts of the turbines during load variations which they are not designed for. On the other hand, investigations on part load operation of single regulated turbines, i.e., Francis and propeller, proved the formation of rotating vortex rope (RVR) in the draft tube. The RVR induces oscillating flow both in plunging and rotating modes which results in oscillating force with two different frequencies on the runner blades, bearings and other rotating parts of the turbine. The purpose of this study is to investigate the effect of transient operations on the pressure fluctuations on the runner and mechanism of the RVR formation/mitigation. Draft tube and runner blades of the Porjus U9 model, a Kaplan turbine, were equipped with pressure sensors. The model was run in off-cam mode during different load variation conditions to check the runner performance under unsteady condition. The results showed that the transients between the best efficiency point and the high load happens in a smooth way while transitions to/from the part load, where rotating vortex rope (RVR) forms in the draft tube induces high level of fluctuations with two frequencies on the runner; plunging and rotating mode of the RVR.

  9. Stimulation of wound healing by helium atmospheric pressure plasma treatment

    Science.gov (United States)

    Vasile Nastuta, Andrei; Topala, Ionut; Grigoras, Constantin; Pohoata, Valentin; Popa, Gheorghe

    2011-03-01

    New experiments using atmospheric pressure plasma have found large application in treatment of living cells or tissues, wound healing, cancerous cell apoptosis, blood coagulation on wounds, bone tissue modification, sterilization and decontamination. In this study an atmospheric pressure plasma jet generated using a cylindrical dielectric-barrier discharge was applied for treatment of burned wounds on Wistar rats' skin. The low temperature plasma jet works in helium and is driven by high voltage pulses. Oxygen and nitrogen based impurities are identified in the jet by emission spectroscopy. This paper analyses the natural epithelization of the rats' skin wounds and two methods of assisted epithelization, a classical one using polyurethane wound dressing and a new one using daily atmospheric pressure plasma treatment of wounds. Systemic and local medical data, such as haematological, biochemical and histological parameters, were monitored during entire period of study. Increased oxidative stress was observed for plasma treated wound. This result can be related to the presence in the plasma volume of active species, such as O and OH radicals. Both methods, wound dressing and plasma-assisted epithelization, provided positive medical results related to the recovery process of burned wounds. The dynamics of the skin regeneration process was modified: the epidermis re-epitelization was accelerated, while the recovery of superficial dermis was slowed down.

  10. Stimulation of wound healing by helium atmospheric pressure plasma treatment

    Energy Technology Data Exchange (ETDEWEB)

    Nastuta, Andrei Vasile; Topala, Ionut; Pohoata, Valentin; Popa, Gheorghe [Faculty of Physics, Alexandru Ioan Cuza University, Bd. Carol No. 11, 700506, Iasi (Romania); Grigoras, Constantin, E-mail: andrei.nastuta@uaic.ro [Physiopathology Department, Grigore T. Popa University of Medicine and Pharmacy, 700115, Iasi (Romania)

    2011-03-16

    New experiments using atmospheric pressure plasma have found large application in treatment of living cells or tissues, wound healing, cancerous cell apoptosis, blood coagulation on wounds, bone tissue modification, sterilization and decontamination. In this study an atmospheric pressure plasma jet generated using a cylindrical dielectric-barrier discharge was applied for treatment of burned wounds on Wistar rats' skin. The low temperature plasma jet works in helium and is driven by high voltage pulses. Oxygen and nitrogen based impurities are identified in the jet by emission spectroscopy. This paper analyses the natural epithelization of the rats' skin wounds and two methods of assisted epithelization, a classical one using polyurethane wound dressing and a new one using daily atmospheric pressure plasma treatment of wounds. Systemic and local medical data, such as haematological, biochemical and histological parameters, were monitored during entire period of study. Increased oxidative stress was observed for plasma treated wound. This result can be related to the presence in the plasma volume of active species, such as O and OH radicals. Both methods, wound dressing and plasma-assisted epithelization, provided positive medical results related to the recovery process of burned wounds. The dynamics of the skin regeneration process was modified: the epidermis re-epitelization was accelerated, while the recovery of superficial dermis was slowed down.

  11. Transmission geometry laserspray ionization vacuum using an atmospheric pressure inlet.

    Science.gov (United States)

    Lutomski, Corinne A; El-Baba, Tarick J; Inutan, Ellen D; Manly, Cory D; Wager-Miller, James; Mackie, Ken; Trimpin, Sarah

    2014-07-01

    This represents the first report of laserspray ionization vacuum (LSIV) with operation directly from atmospheric pressure for use in mass spectrometry. Two different types of electrospray ionization source inlets were converted to LSIV sources by equipping the entrance of the atmospheric pressure inlet aperture with a customized cone that is sealed with a removable glass plate holding the matrix/analyte sample. A laser aligned in transmission geometry (at 180° relative to the inlet) ablates the matrix/analyte sample deposited on the vacuum side of the glass slide. Laser ablation from vacuum requires lower inlet temperature relative to laser ablation at atmospheric pressure. However, higher inlet temperature is required for high-mass analytes, for example, α-chymotrypsinogen (25.6 kDa). Labile compounds such as gangliosides and cardiolipins are detected in the negative ion mode directly from mouse brain tissue as intact doubly deprotonated ions. Multiple charging enhances the ion mobility spectrometry separation of ions derived from complex tissue samples.

  12. Atmospheric pressure thermospray ionization using a heated microchip nebulizer.

    Science.gov (United States)

    Keski-Rahkonen, Pekka; Haapala, Markus; Saarela, Ville; Franssila, Sami; Kotiaho, Tapio; Kostiainen, Risto; Auriola, Seppo

    2009-10-30

    When a standard atmospheric pressure chemical ionization (APCI) or atmospheric pressure photoionization (APPI) ion source is used without applying the corona discharge or photoirradiation, atmospheric pressure thermospray ionization (APTSI) of various compounds can be achieved. Although largely ignored, this phenomenon has recently gained interest as an alternative ionization technique. In this study, this technique is performed for the first time on a miniaturized scale using a microchip nebulizer. Sample ionization with the presented microchip-APTSI (microAPTSI) is achieved by applying only heat and gas flow to a nebulizer chip, without any other methods to promote gas-phase ionization. To evaluate the performance of the described microAPTSI setup, ionization efficiency for a set of test compounds was monitored as the microchip positioning, temperature, nebulizer gas flow rate, sample solution composition, and solvent flow rate were varied. The microAPTSI mass spectra of the test compounds were also compared to those obtained with ESI and APCI. The microAPTSI produces ESI-like spectra with low background noise, favoring the formation of protonated or deprotonated molecules of compounds that are ionizable in solution. Multiple charging of peptides without in-source fragmentation was also observed. Unlike ESI, however, the microAPTSI source can tolerate the presence of mobile phase additives like trifluoroacetic acid (TFA) without significant ion suppression. The microAPTSI source can be used with standard mass spectrometer ion source hardware, being a unique alternative to the present interfacing techniques.

  13. Stimulation of wound healing by helium atmospheric pressure plasma treatment

    International Nuclear Information System (INIS)

    New experiments using atmospheric pressure plasma have found large application in treatment of living cells or tissues, wound healing, cancerous cell apoptosis, blood coagulation on wounds, bone tissue modification, sterilization and decontamination. In this study an atmospheric pressure plasma jet generated using a cylindrical dielectric-barrier discharge was applied for treatment of burned wounds on Wistar rats' skin. The low temperature plasma jet works in helium and is driven by high voltage pulses. Oxygen and nitrogen based impurities are identified in the jet by emission spectroscopy. This paper analyses the natural epithelization of the rats' skin wounds and two methods of assisted epithelization, a classical one using polyurethane wound dressing and a new one using daily atmospheric pressure plasma treatment of wounds. Systemic and local medical data, such as haematological, biochemical and histological parameters, were monitored during entire period of study. Increased oxidative stress was observed for plasma treated wound. This result can be related to the presence in the plasma volume of active species, such as O and OH radicals. Both methods, wound dressing and plasma-assisted epithelization, provided positive medical results related to the recovery process of burned wounds. The dynamics of the skin regeneration process was modified: the epidermis re-epitelization was accelerated, while the recovery of superficial dermis was slowed down.

  14. Highly physical penumbra solar radiation pressure modeling with atmospheric effects

    Science.gov (United States)

    Robertson, Robert; Flury, Jakob; Bandikova, Tamara; Schilling, Manuel

    2015-10-01

    We present a new method for highly physical solar radiation pressure (SRP) modeling in Earth's penumbra. The fundamental geometry and approach mirrors past work, where the solar radiation field is modeled using a number of light rays, rather than treating the Sun as a single point source. However, we aim to clarify this approach, simplify its implementation, and model previously overlooked factors. The complex geometries involved in modeling penumbra solar radiation fields are described in a more intuitive and complete way to simplify implementation. Atmospheric effects are tabulated to significantly reduce computational cost. We present new, more efficient and accurate approaches to modeling atmospheric effects which allow us to consider the high spatial and temporal variability in lower atmospheric conditions. Modeled penumbra SRP accelerations for the Gravity Recovery and Climate Experiment (GRACE) satellites are compared to the sub-nm/s2 precision GRACE accelerometer data. Comparisons to accelerometer data and a traditional penumbra SRP model illustrate the improved accuracy which our methods provide. Sensitivity analyses illustrate the significance of various atmospheric parameters and modeled effects on penumbra SRP. While this model is more complex than a traditional penumbra SRP model, we demonstrate its utility and propose that a highly physical model which considers atmospheric effects should be the basis for any simplified approach to penumbra SRP modeling.

  15. Contributions of tidal lung inflation to human R-R interval and arterial pressure fluctuations

    Science.gov (United States)

    Koh, J.; Brown, T. E.; Beightol, L. A.; Eckberg, D. L.

    1998-01-01

    We studied the effects of mechanical lung inflation on respiratory frequency R-R interval and arterial pressure fluctuations in nine healthy young adults undergoing elective orthopedic surgery. We conducted this research to define the contribution of pulmonary and thoracic stretch receptor input to respiratory sinus arrhythmia. We compared fast Fourier transform spectral power during three modes of ventilation: (1) spontaneous, frequency-controlled (0.25 Hz) breathing, (2) intermittent positive pressure ventilation (0.25 Hz, with a tidal volume of 8 ml/kg) and (3) high frequency jet ventilation (5.0 Hz, 2.5 kg/cm2), after sedation and vecuronium paralysis. Mean R-R intervals, arterial pressures and arterial blood gas levels were comparable during all three breathing conditions. Respiratory frequency systolic pressure spectral power was comparable during spontaneous breathing and conventional mechanical ventilation, but was significantly reduced during high frequency jet ventilation (P mechanical, than high frequency jet ventilation (P pulmonary and thoracic stretch receptors make a statistically significant contribution to respiratory sinus arrhythmia, that contribution is small.

  16. Quantum polarization fluctuations of an Airy beam in turbulent atmosphere in a slant path.

    Science.gov (United States)

    Yin, Xia; Zhang, Licheng

    2016-07-01

    Polarization of light has many applications in quantum information processing, including quantum teleportation and dense coding. In this paper, we investigate the polarization fluctuations of Airy beams propagating in a slant turbulent channel under the "few-photon" limit. Using the quantum Stokes parameters and the quantum degree of polarization, we demonstrate that the degree of polarization of Airy beams increases significantly with the large number of the detection photons, and a higher photon-number level can retain the stability of polarization. Numerical simulations show that the longer propagation distance and the stronger turbulence will lead to less oscillatory behaviors and a decrease in the polarization degree of Airy beams, but a bigger exponential truncation factor will cause an increase in the polarization degree of Airy beams. In contrast with Gaussian beams, the degree of polarization of Airy beams is less affected by atmospheric turbulence and propagation distance under the same conditions, which means that Airy beams possess a resilient ability against turbulence-induced perturbations. These results indicate that Airy beams have great potential for applications in long-distance free-space optical communications to improve the performance of a polarization-encoded free-space quantum communication system. PMID:27409692

  17. Deconstructing an Atmospheric Model: Variability and Response, Unstable Periodic Orbits, and the Fluctuation-Dissipation Theorem

    Science.gov (United States)

    Gritsun, Andrei; Lucarini, Valerio

    2016-04-01

    Unstable periodic orbits (UPOs) provide the so-called skeletal dynamics of a sufficiently well-behaved chaotic dynamical system and provide a powerful tool for relating the response of the system to its variability. In fact, UPOs constitute natural modes of variability of the system, and resonant behaviour of the response of the system to can be associated to good correspondence between the geometry of one UPO and of the forcing term and between their periodicities. We have here analyzed a simple barotropic model of the atmosphere and constructed and found algorithmically a large number of UPOs. We have then studied the change in the climate resulting from changes in the forcing, in the orography, and in the Eckman friction. The most interesting result is the presence of a strong resonance in the orographic response on time scales of the order of about 3 days, corresponding to forced waves. Interestingly, such a spectral feature is entirely absent from the natural variability of the system and correspond to the excitation of a specific group of UPOs. This clarifies the fact that, as opposed to the case of quasi-equilibrium systems, it is far from obvious to associate forced and free variability in the spirit of the fluctuation-dissipation theorem (FDT). Reassuringly, ysing the complementary point of view of covariant Lyapunov vectors, we discover that the forcing projects substantially in the stable direction of the flow, which is exactly the mathematical setting under which the FDT cannot be applied.

  18. The updated bottom up solution applied to atmospheric pressure photoionization and electrospray ionization mass spectrometry

    Science.gov (United States)

    The Updated Bottom Up Solution (UBUS) was recently applied to atmospheric pressure chemical ionization (APCI) mass spectrometry (MS) of triacylglycerols (TAGs). This report demonstrates that the UBUS applies equally well to atmospheric pressure photoionization (APPI) MS and to electrospray ionizatio...

  19. When API Mass Spectrometry Meets Super Atmospheric Pressure Ion Sources.

    Science.gov (United States)

    Chen, Lee Chuin

    2015-01-01

    In a tutorial paper on the application of free-jet technique for API-MS, John Fenn mentioned that "…for a number of years and a number of reasons, it has been found advantageous in many situations to carry out the ionization process in gas at pressures up to 1000 Torr or more" (Int. J. Mass Spectrom. 200: 459-478, 2000). In fact, the first ESI mass spectrometer constructed by Yamashita and Fenn had a counter-flow curtain gas source at 1050 Torr (ca. 1.4 atm) to sweep away the neutral (J. Phys. Chem. 88: 4451-4459, 1984). For gaseous ionization using electrospray plume, theoretical analysis also shows that "super-atmospheric operation would be more preferable in space-charge-limited situations."(Int. J. Mass Spectrom. 300: 182-193, 2011). However, electrospray and the corona-based chemical ion source (APCI) in most commercial instrument are basically operated under an atmospheric pressure ambient, perhaps out of the concern of safety, convenience and simplicity in maintenance. Running the ion source at pressure much higher than 1 atm is not so common, but had been done by a number of groups as well as in our laboratory. A brief review on these ion sources will be given in this paper.

  20. Decomposition of benzene in a corona discharge at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Satoh, Kohki [Department of Electrical and Electronic Engineering, Muroran Institute of Technology, 27-1 Mizumoto, Muroran 050-8585 (Japan); Centre of Environmental Science and Disaster Mitigation for Advanced Research, Muroran Institute of Technology, 27-1 Mizumoto, Muroran 050-8585 (Japan); Matsuzawa, Toshiharu; Itoh, Hidenori [Department of Electrical and Electronic Engineering, Muroran Institute of Technology, 27-1 Mizumoto, Muroran 050-8585 (Japan)

    2008-05-01

    We investigated the decomposition characteristics of benzene in a positive DC corona discharge between multineedle and plane electrodes with a background gas of nitrogen-oxygen mixture at atmospheric pressure. We obtained C{sub 2}H{sub 2}, HCN, HCOOH, CO and CO{sub 2} as benzene fragments and by-products, and C{sub 2}H{sub 2} and HCN as minor intermediate products. Benzene was primarily converted into CO{sub 2} via CO at low oxygen concentrations (0.2%) and via CO and HCOOH at the atmospheric oxygen concentration (20%). Further, 57% and 24% of carbon atoms were deposited on the plane electrode and the discharge chamber at oxygen concentrations of 0.2% and 20%, respectively.

  1. Surface analysis of polymers treated by remote atmospheric pressure plasma.

    Science.gov (United States)

    Gonzalez, Eleazar; Hicks, Robert F

    2010-03-01

    The surfaces of high-density polyethylene (HDPE), poly(methyl methacrylate) (PMMA), and polyethersulfone (PES) were treated with a low-temperature, atmospheric pressure oxygen and helium plasma. The polymers were exposed to the downstream afterglow of the plasma, which contained primarily oxygen atoms and metastable oxygen molecules ((1)Delta(g) O(2)), and no ions or electrons. X-ray photoelectron spectroscopy (XPS) of HDPE revealed that 20% of the carbon atoms were converted into oxidized functional groups, with about half of these being carboxylic acids. Attenuated total reflection infrared spectroscopy of all three polymers was obtained in order to determine the types of functional groups formed by atmospheric plasma exposure. It was found that the polymers were rapidly oxidized with addition of alcohols, ketones, and carboxylic acids to the carbon backbone. Chain scission occurred on HDPE and PMMA, while on PES the aromatic groups underwent ring-opening and insertion of carboxylic acid. PMID:19950952

  2. Improvements of model-test method for cavitation-induced pressure fluctuation in marine propeller

    Institute of Scientific and Technical Information of China (English)

    LEE Jeung-Hoon; HAN Jae-Moon; PARK Hyung-Gil; SEO Jong-Soo

    2013-01-01

    Although the prediction of propeller cavitation-induced pressure fluctuation strongly depends on the model-scalemeasurement in a cavitation tunnel,there is still a lack of correlation with full-scale data.This paper deals with the enhancement of such a correlation deficiency by improving the conventional model-test technique,two majors of which are in the following.One is to take into account the boundary layer effect of wooden fairing plate at the ceiling of water cavitation tunnel.The other is to avoid the resonance frequency range of model-ship via adjusting the revolution speed of model propeller.Through a case study,for which both model and full-scale test data are available,the improved method in this study shows its validness,and furthermore a close correlation with full scale measurement.

  3. Driven Motion and Instability of an Atmospheric Pressure Arc

    Energy Technology Data Exchange (ETDEWEB)

    Max Karasik

    1999-12-01

    Atmospheric pressure arcs are used extensively in applications such as welding and metallurgy. However, comparatively little is known of the physics of such arcs in external magnetic fields and the mechanisms of the instabilities present. In order to address questions of equilibrium and stability of such arcs, an experimental arc furnace is constructed and operated in air with graphite cathode and steel anode at currents 100-250 A. The arc is diagnosed with a gated intensified camera and a collimated photodiode array, as well as fast voltage and current probes.

  4. Driven Motion and Instability of an Atmospheric Pressure Arc

    International Nuclear Information System (INIS)

    Atmospheric pressure arcs are used extensively in applications such as welding and metallurgy. However, comparatively little is known of the physics of such arcs in external magnetic fields and the mechanisms of the instabilities present. In order to address questions of equilibrium and stability of such arcs, an experimental arc furnace is constructed and operated in air with graphite cathode and steel anode at currents 100-250 A. The arc is diagnosed with a gated intensified camera and a collimated photodiode array, as well as fast voltage and current probes

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

    Science.gov (United States)

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

    2009-11-01

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

  6. Electrical characterization of atmospheric pressure DBD in air

    International Nuclear Information System (INIS)

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

  7. Atmospheric pressure cold plasma as an antifungal therapy

    International Nuclear Information System (INIS)

    A microhollow cathode based, direct-current, atmospheric pressure, He/O2 (2%) cold plasma microjet was used to inactive antifungal resistants Candida albicans, Candida krusei, and Candida glabrata in air and in water. Effective inactivation (>90%) was achieved in 10 min in air and 1 min in water. Antifungal susceptibility tests showed drastic reduction of the minimum inhibitory concentration after plasma treatment. The inactivation was attributed to the reactive oxygen species generated in plasma or in water. Hydroxyl and singlet molecular oxygen radicals were detected in plasma-water system by electron spin resonance spectroscopy. This approach proposed a promising clinical dermatology therapy.

  8. Application of Atmospheric Pressure Plasma in Polymer and Composite Adhesion

    OpenAIRE

    Yu, Hang

    2015-01-01

    An atmospheric pressure helium and oxygen plasma was used to investigate surface activation and bonding in polymer composites. This device was operated by passing 1.0-3.0 vol% of oxygen in helium through a pair of parallel plate metal electrodes powered by 13.56 or 27.12 MHz radio frequency power. The gases were partially ionized between the capacitors where plasma was generated. The reactive species in the plasma were carried downstream by the gas flow to treat the substrate surface. The...

  9. Diagnostics of Atmospheric Pressure Surface Discharge Plasmas in Argon

    Institute of Scientific and Technical Information of China (English)

    张锐; 詹如娟; 温晓辉

    2003-01-01

    Atmospheric pressure surface discharge is shown to have great prospects for a number of industrial applications.To acquire better results in application fields and considering that the study of the basic parameters including electron temperature and electron density is desirable,we develop an equivalent circuit model and the diagnostic techniques based on optical emission spectroscopy and electrical measurement in our laboratory.The electron temperature has been determined to be about 0.7eV by a Fermi-Dirac model.The electron density has been calculated to be near 1010 cm-3 from a time resolved electrical measurement(Ohmic heating method).

  10. Experiment and Simulation of Atmospheric Pressure Glow Surface Discharge

    Institute of Scientific and Technical Information of China (English)

    江中和; 胡希伟; 刘明海; 辜承林; 潘垣

    2003-01-01

    Atmospheric pressure glow discharge was observed in a surface discharge generator. The frequency of ac power supply is more than 9 kHz and the sinusoidal peak-to-peak applied voltage is 9 Ky. The electric field intensity in a kind of surface discharge generators is calculated with the boundary element method. Then a two-dimensional fluid model was used to simulate the ion trapping and electron trapping in a surface discharge just before the breakdown. The simulation results are in good agreement with our observation.

  11. Assessment of Pressure Fluctuation Effect for Thermal Fatigue in a T-junction Using Thermo-Hydro Analysis

    International Nuclear Information System (INIS)

    As a result, when evaluating thermal fatigue for the mixing tee, temperature fluctuation is dominant for this phenomenon, it can be reasonably assumed that the pressure is constant on the pipe inner wall. Recently, thermal fatigue due to mixing of the fluids having different temperatures has been considered as an important issue on the fatigue evaluation of nuclear piping. Mainly, this phenomenon occurs in a T-junction operating with the fluids consisted of different temperatures. Because of the turbulent mixing of hot and cold water, the temperature on the inner wall of the pipe fluctuates rapidly, causing the variation of thermal stresses in the pipe and resulting in high cycle thermal fatigue. In practice, cracking by high cycle thermal fatigue is reported at a T-junction in the residual heat removal system at Civaux unit 1 in France. However, because of irregular flow inside the pipe, the pressure also fluctuates rapidly as well as temperature in the inner wall of the pipe. Therefore, in this paper, three-dimensional thermo-hydro analysis was performed for the mixing tee of the shutdown cooling system of the pressurized water reactor plant, examining the pressure variation at the pipe inner wall. Based on the analysis result, this study aims at assessing the pressure fluctuation effect on the thermal fatigue. In this paper, it is verified that there is pressure fluctuation as well as temperature on the inner wall of mixing tee operating with the fluids having different temperatures. However, since the amplitude of pressure is relatively smaller than design pressure of the shutdown cooling system, the effect wouldn't be important for the thermal fatigue

  12. Investigation of temperature fluctuations caused by steam-water two-phase flow in pressurizer spray piping

    International Nuclear Information System (INIS)

    In a PWR plant, a steam-water two-phase flow may possibly exist in the pressurizer spray pipe under a normal operating condition since the flow rate of the spray water is not sufficient to fill the horizontal section of the pipe completely. Initiation of high cycle fatigue cracks is suspected to occur under such thermally stratified two phase flow conditions due to cyclic thermal stress fluctuations caused by oscillations of the water surface. Such oscillations cannot be detected by the measurement of temperature on outer surface of the pipe. In order to clarify the flow and thermal conditions in the pressurizer spray pipe and assess their impact on the pipe structure, an experiment was conducted for a steam-water flow at a low flow rate using a mock-up pressurizer spray pipe. The maximum temperature fluctuation of about 0.2 times of the steam-water temperature difference was observed at the inner wall around water surface in the test section. Visualization tests were conducted to investigate the temperature fluctuation phenomena. It was shown that the fluid temperature fluctuations were not caused by the waves on the water surface, but were caused by liquid temperature fluctuations in water layer below the interface. The influence of small amount of non-condensable gas dissolved in the reactor coolant on the liquid temperature fluctuation phenomena was investigated by injecting air into the experimental loop. The air injection attenuated the liquid temperature fluctuations in the water layer since the condensation was suppressed by the non-condensable gas. It is not expected that wall temperature fluctuation in the actual PWR plant may exceed the temperature equivalent to the fatigue limit stress amplitude when it is assumed to be proportional to the steam-water temperature difference. (author)

  13. Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Robert F. Hicks; Hans W. Herrmann

    2003-12-15

    The purpose of this project was to demonstrate a practical, environmentally benigh technology for the surface decontamination and decommissioning of radioactive waste. A low temperature, atmospheric pressure plasma has been developed with initial support from the DOE, Environmental Management Sciences Program. This devise selectively etches radioactive metals from surfaces, rendering objects radiation free and suitable for decommissioning. The volatile reaction products are captured on filters, which yields a tremendous reduction in the volume of the waste. The technology shows a great potential for accelerating the clean-up effort for the equipment and structures contaminated with radioactive materials within the DOE complex. The viability of this technology has been demonstrated by selectively and rapidly stripping uranium from stainless steel surfaces at low temperature. Studies on uranium oxide have shown that etch rates of 4.0 microns per minute can be achieved at temperature below 473 K. Over the past three years, we have made numerous improvements in the design of the atmospheric pressure plasma source. We are now able to scale up the plasma source to treat large surface areas.

  14. Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces

    International Nuclear Information System (INIS)

    The purpose of this project was to demonstrate a practical, environmentally benigh technology for the surface decontamination and decommissioning of radioactive waste. A low temperature, atmospheric pressure plasma has been developed with initial support from the DOE, Environmental Management Sciences Program. This devise selectively etches radioactive metals from surfaces, rendering objects radiation free and suitable for decommissioning. The volatile reaction products are captured on filters, which yields a tremendous reduction in the volume of the waste. The technology shows a great potential for accelerating the clean-up effort for the equipment and structures contaminated with radioactive materials within the DOE complex. The viability of this technology has been demonstrated by selectively and rapidly stripping uranium from stainless steel surfaces at low temperature. Studies on uranium oxide have shown that etch rates of 4.0 microns per minute can be achieved at temperature below 473 K. Over the past three years, we have made numerous improvements in the design of the atmospheric pressure plasma source. We are now able to scale up the plasma source to treat large surface areas

  15. Compact atmospheric pressure plasma self-resonant drive circuits

    International Nuclear Information System (INIS)

    This paper reports on compact solid-state self-resonant drive circuits that are specifically designed to drive an atmospheric pressure plasma jet and a parallel-plate dielectric barrier discharge of small volume (0.5 cm3). The atmospheric pressure plasma (APP) device can be operated with helium, argon or a mixture of both. Equivalent electrical models of the self-resonant drive circuits and discharge are developed and used to estimate the plasma impedance, plasma power density, current density or electron number density of three APP devices. These parameters and the kinetic gas temperature are dependent on the self-resonant frequency of the APP device. For a fixed switching frequency and APP device geometry, the plasma parameters are controlled by adjusting the dc voltage at the primary coil and the gas flow rate. The resonant frequency is controlled by the selection of the switching power transistor and means of step-up voltage transformation (ferrite core, flyback transformer, or Tesla coil). The flyback transformer operates in the tens of kHz, the ferrite core in the hundreds of kHz and Tesla coil in the MHz range. Embedded within this work is the principle of frequency pulling which is exemplified in the flyback transformer circuit that utilizes a pickup coil for feedback control of the switching frequency. (paper)

  16. Compact atmospheric pressure plasma self-resonant drive circuits

    Science.gov (United States)

    Law, V. J.; Anghel, S. D.

    2012-02-01

    This paper reports on compact solid-state self-resonant drive circuits that are specifically designed to drive an atmospheric pressure plasma jet and a parallel-plate dielectric barrier discharge of small volume (0.5 cm3). The atmospheric pressure plasma (APP) device can be operated with helium, argon or a mixture of both. Equivalent electrical models of the self-resonant drive circuits and discharge are developed and used to estimate the plasma impedance, plasma power density, current density or electron number density of three APP devices. These parameters and the kinetic gas temperature are dependent on the self-resonant frequency of the APP device. For a fixed switching frequency and APP device geometry, the plasma parameters are controlled by adjusting the dc voltage at the primary coil and the gas flow rate. The resonant frequency is controlled by the selection of the switching power transistor and means of step-up voltage transformation (ferrite core, flyback transformer, or Tesla coil). The flyback transformer operates in the tens of kHz, the ferrite core in the hundreds of kHz and Tesla coil in the MHz range. Embedded within this work is the principle of frequency pulling which is exemplified in the flyback transformer circuit that utilizes a pickup coil for feedback control of the switching frequency.

  17. Bacteria Inactivation Using DBD Plasma Jet in Atmospheric Pressure Argon

    Institute of Scientific and Technical Information of China (English)

    XU Guimin; ZHANG Guanjun; SHI Xingmin; MA Yue; WANG Ning; LI Yuan

    2009-01-01

    A coaxial dielectric barrier discharge plasma jet Was designed,which can be operated in atmospheric pressure argon under an intermediate frequency sinusoidal resonant power supply,and an atmospheric pressure glow-like discharge Was achieved.Two kinds of typical bacteria,i.e.,the Staphylococcus aureus(S.aurens)and Escherichia coil(E.coil),were employed to study the bacterial inactivation mechanism by means of the non-thermal plasma.The killing log value (KLV)of S.aureus reached up to 5.38 with a treatment time of 90 s and that of E.coil up to 5.36 with 60 s,respectively.According to the argon emission spectra of the plasma jet and the scanning electron microscope (SEM) images of the two bacteria before and after the plasma treatment.it is concluded that the reactive species in the argon plasma played a major role in the bacterial inactivation,while the heat,electric field and UV photons had little effect.

  18. Nonlinear lumped circuit modeling of an atmospheric pressure rf discharge

    Science.gov (United States)

    Lapke, M.; Ziegler, D.; Mussenbrock, T.; Gans, T.; Schulz-von der Gathen, V.

    2006-10-01

    The subject of our modeling approach is a specifically modified version of the atmospheric pressure plasma jet (APPJ, originally proposed by Selwyn and coworkers^1) with reduced discharge volume, the micro atmospheric pressure plasma jet (μ-APPJ). The μ-APPJ is a homogeneous nonequilibrium discharge operated with Argon or Helium as the feedstock gas and a percentage volume admixture of a molecular gas (O2, H2, N2). The efficiency of the discharge is mainly due to the dissociated and activated molecules in the effluent that can be selected depending on the application. A variety of applications in surface treatment have already been demonstrated, e.g., in semiconductor technology, restoration and bio-medicine. In this contribution we present and analyze a nonlinear lumped circuit model of the μ-APPJ. We apply a two-scale formalism. The bulk is modeled by a generalized Ohm's law, whereas the sheath is described on a considerably higher level of mathematical sophistication. The main focus lies on the spectrum of the discharge current in order to support the characterization of the discharge via model-based diagnostics, i.e., the estimation of the spatially averaged electron density from the frequency of certain self-excitated collective resonance modes. J. Park et al., Appl. Phy. Lett. 76, 288 (2000)

  19. Hazardous gas treatment using atmospheric pressure microwave discharges

    Energy Technology Data Exchange (ETDEWEB)

    Mizeraczyk, Jerzy; Jasinski, Mariusz; Zakrzewski, Zenon [Centre for Plasma and Laser Engineering, Institute of Fluid Flow Machinery, Polish Academy of Sciences, Fiszera 14, 80-231 Gdansk (Poland)

    2005-12-15

    Atmospheric pressure microwave discharge methods and devices used for producing non-thermal plasmas for control of gaseous pollutants are described in this paper. The main part of the paper is concerned with microwave torch discharges (MTDs). Results of laboratory experiments on plasma abatement of several volatile organic compounds (VOCs) in their mixtures with either synthetic air or nitrogen in low ({approx}100 W) and moderate (200-400 W) microwave torch plasmas at atmospheric pressure are presented. Three types of MTD generators, i.e. low-power coaxial-line-based MTDs, moderate-power waveguide-based coaxial-line MTDs and moderate-power waveguide-based MTDs were used. The gas flow rate and microwave (2.45 GHz) power delivered to the discharge were in the range of 1-3 litre min{sup -1} and 100-400 W, respectively. The concentrations of the processed gaseous pollutants were from several to several tens of per cent. The results showed that the MTD plasmas fully decomposed the VOCs at a relatively low energy cost. The energy efficiency of decomposition of several gaseous pollutants reached 1000 g (kW-h){sup -1}. This suggests that MTD plasmas can be useful tools for decomposition of highly concentrated VOCs.

  20. Centrifugal compressor surge detecting method based on wavelet analysis of unsteady pressure fluctuations in typical stages

    Science.gov (United States)

    Izmaylov, R.; Lebedev, A.

    2015-08-01

    Centrifugal compressors are complex energy equipment. Automotive control and protection system should meet the requirements: of operation reliability and durability. In turbocompressors there are at least two dangerous areas: surge and rotating stall. Antisurge protecting systems usually use parametric or feature methods. As a rule industrial system are parametric. The main disadvantages of anti-surge parametric systems are difficulties in mass flow measurements in natural gas pipeline compressor. The principal idea of feature method is based on the experimental fact: as a rule just before the onset of surge rotating or precursor stall established in compressor. In this case the problem consists in detecting of unsteady pressure or velocity fluctuations characteristic signals. Wavelet analysis is the best method for detecting onset of rotating stall in spite of high level of spurious signals (rotating wakes, turbulence, etc.). This method is compatible with state of the art DSP systems of industrial control. Examples of wavelet analysis application for detecting onset of rotating stall in typical stages centrifugal compressor are presented. Experimental investigations include unsteady pressure measurement and sophisticated data acquisition system. Wavelet transforms used biorthogonal wavelets in Mathlab systems.

  1. Turbulent flow and pressure fluctuation prediction of the impeller in an axial-flow pump based on LES

    International Nuclear Information System (INIS)

    The Large Eddy Simulation method with sliding mesh technique has been used for analyzing the unsteady flow in an axial-flow pump at five different flow rates. The tip leakage flow in the tip-gap region and the pressure pulsations on the blade surface were examined. The results indicate that the agreement between predicted pump performance and experimental data was reasonably good. The dominate tip-leakage vortex(TLV) extended to the pressure side of the neighboring blade for all five investigated flow rates. As the flow rate increases from 0.7Qd to 1.2Qd, the angle between the dominate TLV and the blade reduced from 20 deg to 14 deg. The results also showed that the amplitude of pressure fluctuation on the near-tip zone of the blade surface increases as the flow rate farer from the design flow rate, especially on the pressure side of the blade. At the 0.7Qd operation condition, the pressure fluctuation amplitude of the monitoring point PP3 (at the near-tip zone on the pressure side of the blade close to the blade leading edge) was 8.5 times of the one at design flow rate, and the high-frequency(18fr) pulsation occurred due to tip leakage vortex. When the flow rate was more than 1.0Qd, the pressure fluctuations of PP3 was dominated by the rotation frequency(fr)

  2. Turbulent flow and pressure fluctuation prediction of the impeller in an axial-flow pump based on LES

    Science.gov (United States)

    Shen, J. F.; Li, Y. J.; Liu, Z. Q.; Tang, X. L.

    2013-12-01

    The Large Eddy Simulation method with sliding mesh technique has been used for analyzing the unsteady flow in an axial-flow pump at five different flow rates. The tip leakage flow in the tip-gap region and the pressure pulsations on the blade surface were examined. The results indicate that the agreement between predicted pump performance and experimental data was reasonably good. The dominate tip-leakage vortex(TLV) extended to the pressure side of the neighboring blade for all five investigated flow rates. As the flow rate increases from 0.7Qd to 1.2Qd, the angle between the dominate TLV and the blade reduced from 20 deg to 14 deg. The results also showed that the amplitude of pressure fluctuation on the near-tip zone of the blade surface increases as the flow rate farer from the design flow rate, especially on the pressure side of the blade. At the 0.7Qd operation condition, the pressure fluctuation amplitude of the monitoring point PP3 (at the near-tip zone on the pressure side of the blade close to the blade leading edge) was 8.5 times of the one at design flow rate, and the high-frequency(18fr) pulsation occurred due to tip leakage vortex. When the flow rate was more than 1.0Qd, the pressure fluctuations of PP3 was dominated by the rotation frequency(fr).

  3. Measurement of viscosity of gaseous mixtures at atmospheric pressure

    Science.gov (United States)

    Singh, J. J.; Mall, G. H.; Chegini, H.

    1986-01-01

    Coefficients of viscosity of various types of gas mixtures, including simulated natural-gas samples, have been measured at atmospheric pressure and room temperature using a modified capillary tube method. Pressure drops across the straight capillary tube section of a thermal mass flowmeter were measured for small, well-defined, volume flow rates for the test gases and for standard air. In this configuration, the flowmeter provides the volumetric flow rates as well as a well-characterized capillary section for differential pressure measurements across it. The coefficients of viscosity of the test gases were calculated using the reported value of 185.6 micro P for the viscosity of air. The coefficients of viscosity for the test mixtures were also calculated using Wilke's approximation of the Chapman-Enskog (C-E) theory. The experimental and calculated values for binary mixtures are in agreement within the reported accuracy of Wilke's approximation of the C-E theory. However, the agreement for multicomponent mixtures is less satisfactory, possible because of the limitations of Wilkes's approximation of the classical dilute-gas state model.

  4. Surface Modification by Atmospheric Pressure Plasma for Improved Bonding

    Science.gov (United States)

    Williams, Thomas Scott

    An atmospheric pressure plasma source operating at temperatures below 150?C and fed with 1.0-3.0 volume% oxygen in helium was used to activate the surfaces of the native oxide on silicon, carbon-fiber reinforced epoxy composite, stainless steel type 410, and aluminum alloy 2024. Helium and oxygen were passed through the plasma source, whereby ionization occurred and ˜10 16 cm-3 oxygen atoms, ˜1015 cm -3 ozone molecules and ˜1016 cm-3 metastable oxygen molecules (O21Deltag) were generated. The plasma afterglow was directed onto the substrate material located 4 mm downstream. Surface properties of the plasma treated materials have been investigated using water contact angle (WCA), atomic force microscopy (AFM), infrared spectroscopy (IR), and x-ray photoelectron spectroscopy (XPS). The work presented herein establishes atmospheric-pressure plasma as a surface preparation technique that is well suited for surface activation and enhanced adhesive bond strength in a variety of materials. Atmospheric plasma activation presents an environmentally friendly alternative to wet chemical and abrasive methods of surface preparation. Attenuated total internal reflection infrared spectroscopy was used to study the aging mechanism of the native oxide on silicon. During storage at ambient conditions, the water contact angle of a clean surface increased from composite, stainless steel type 410, and aluminum alloy 2024 was demonstrated with the atmospheric pressure helium-oxygen plasma. All surfaces studied were converted from a hydrophobic state with a water contact angle of 65° to 80° into a hydrophilic state with a water contact angle between 20° and 40° within 5 seconds of plasma exposure. X-ray photoelectron spectroscopy confirmed that the carbon atoms on the carbon-fiber/epoxy composite were oxidized, yielding 17 atom% carboxylic acid groups, 10% ketones or aldehydes and 9% alcohols. Analysis of stainless steel and aluminum by XPS illustrate oxidation of the metal

  5. On the phase between pressure and heat release fluctuations for propane/hydrogen flames and its role in mode transitions

    KAUST Repository

    Hong, Seunghyuck

    2013-12-01

    This paper presents an experimental investigation into mode-transitions observed in a 50-kW, atmospheric pressure, backward-facing step combustor burning lean premixed C3H8/H2 fuel mixtures over a range of equivalence ratios, fuel compositions and preheat temperatures. The combustor exhibits distinct acoustic response and dynamic flame shape (collectively referred to as "dynamic modes") depending on the operating conditions. We simultaneously measure the dynamic pressure and flame chemiluminescence to examine the phase between pressure (p\\') and heat release fluctuations (q\\') in the observed dynamic modes. Results show that the heat release is in phase with the pressure oscillations (θqp≈0) at the onset of a dynamic mode, while as the operating conditions change within the mode, the phase grows until it reaches a critical value θqp=θc, at which the combustor switches to another dynamic mode. According to the classical Rayleigh criterion, this critical phase (θc) should be π/2, whereas our data show that the transition occurs well below this value. A linear acoustic energy balance shows that this critical phase marks the point where acoustic losses across the system boundaries equal the energy addition from the combustion process to the acoustic field. Based on the extended Rayleigh criterion in which the acoustic energy fluxes through the system boundaries as well as the typical Rayleigh source term (p\\'q\\') are included, we derive an extended Rayleigh index defined as Re=θqp/θc, which varies between 0 and 1. This index, plotted against a density-weighted strained consumption speed, indicates that the impact of the operating parameters on the dynamic mode selection of the combustor collapses onto a family of curves, which quantify the state of the combustor within a dynamic mode. At Re=0, the combustor enters a mode, and switches to another as Re approaches 1. The results provide a metric for quantifying the instability margins of fuel

  6. Specific interaction between negative atmospheric ions and organic compounds in atmospheric pressure corona discharge ionization mass spectrometry.

    Science.gov (United States)

    Sekimoto, Kanako; Sakai, Mami; Takayama, Mitsuo

    2012-06-01

    The interaction between negative atmospheric ions and various types of organic compounds were investigated using atmospheric pressure corona discharge ionization (APCDI) mass spectrometry. Atmospheric negative ions such as O(2)(-), HCO(3)(-), COO(-)(COOH), NO(2)(-), NO(3)(-), and NO(3)(-)(HNO(3)) having different proton affinities served as the reactant ions for analyte ionization in APCDI in negative-ion mode. The individual atmospheric ions specifically ionized aliphatic and aromatic compounds with various functional groups as atmospheric ion adducts and deprotonated analytes. The formation of the atmospheric ion adducts under certain discharge conditions is most likely attributable to the affinity between the analyte and atmospheric ion and the concentration of the atmospheric ion produced under these conditions. The deprotonated analytes, in contrast, were generated from the adducts of the atmospheric ions with higher proton affinity attributable to efficient proton abstraction from the analyte by the atmospheric ion. PMID:22528201

  7. Specific interaction between negative atmospheric ions and organic compounds in atmospheric pressure corona discharge ionization mass spectrometry.

    Science.gov (United States)

    Sekimoto, Kanako; Sakai, Mami; Takayama, Mitsuo

    2012-06-01

    The interaction between negative atmospheric ions and various types of organic compounds were investigated using atmospheric pressure corona discharge ionization (APCDI) mass spectrometry. Atmospheric negative ions such as O(2)(-), HCO(3)(-), COO(-)(COOH), NO(2)(-), NO(3)(-), and NO(3)(-)(HNO(3)) having different proton affinities served as the reactant ions for analyte ionization in APCDI in negative-ion mode. The individual atmospheric ions specifically ionized aliphatic and aromatic compounds with various functional groups as atmospheric ion adducts and deprotonated analytes. The formation of the atmospheric ion adducts under certain discharge conditions is most likely attributable to the affinity between the analyte and atmospheric ion and the concentration of the atmospheric ion produced under these conditions. The deprotonated analytes, in contrast, were generated from the adducts of the atmospheric ions with higher proton affinity attributable to efficient proton abstraction from the analyte by the atmospheric ion.

  8. Research of fluid-induced pressure fluctuation due to impeller-volute interaction in a centrifugal pump

    International Nuclear Information System (INIS)

    The fluid pressure fluctuation generated by unsteady flow is a very important factor to induce vibration of the centrifugal pump. The relative movement between impeller and volute generates an unsteady interaction which affects not only the overall pump performance, but is also responsible for pressure fluctuations. Pressure fluctuations interact with the volute casing or even with the circuit and give rise to dynamic effects over the mechanical parts, which are one of the most important sources of vibration and hydraulic noise. To investigate the flow characteristic in the centrifugal pump, the unsteady flow is simulated by CFD methods in this paper. Unsteady flow characteristic in the centrifugal pump is obtained considering the impeller-volute interaction in the whole flow field. Based on the unsteady flow simulation, amplitude-frequency characteristics of the pressure fluctuation in the centrifugal pump are obtained through setting up monitoring point at the impeller outlet. The research shows that the frequency component include the blade passing frequency as the main component, the multiplication of blade passing frequency, and the harmonic interference due to the unsteady flow

  9. Research of fluid-induced pressure fluctuation due to impeller-volute interaction in a centrifugal pump

    Science.gov (United States)

    Liu, Q. Z.; Yang, K.; Y Li, D.; Gong, R. Z.

    2013-12-01

    The fluid pressure fluctuation generated by unsteady flow is a very important factor to induce vibration of the centrifugal pump. The relative movement between impeller and volute generates an unsteady interaction which affects not only the overall pump performance, but is also responsible for pressure fluctuations. Pressure fluctuations interact with the volute casing or even with the circuit and give rise to dynamic effects over the mechanical parts, which are one of the most important sources of vibration and hydraulic noise. To investigate the flow characteristic in the centrifugal pump, the unsteady flow is simulated by CFD methods in this paper. Unsteady flow characteristic in the centrifugal pump is obtained considering the impeller-volute interaction in the whole flow field. Based on the unsteady flow simulation, amplitude-frequency characteristics of the pressure fluctuation in the centrifugal pump are obtained through setting up monitoring point at the impeller outlet. The research shows that the frequency component include the blade passing frequency as the main component, the multiplication of blade passing frequency, and the harmonic interference due to the unsteady flow.

  10. Optical properties of the atmospheric pressure helium plasma jet generated by alternative current (a.c.) power supply

    Science.gov (United States)

    Ilik, Erkan; Akan, Tamer

    2016-05-01

    In this work, an atmospheric pressure plasma jet (APPJ) was produced to generate cold flowing post-discharge plasma of pure helium gas. The main aim of this study was to generate cold flowing APPJ of pure helium gas and to determine how their optical emission spectrum change influences varying different flow rates. Lengths of early, middle, and late post-discharge plasma (jet) regions and their fluctuations were determined, respectively. Then, ignition condition dependence of the post-discharge plasma for flow rate was specified at a constant voltage. Spectroscopic studies of an atmospheric pressure plasma jet of helium were presented via analyzing OH, N2, N2+, oxygen, and helium intensities for various flow rates.

  11. Atmospheric pressure dielectric barrier discharges for sterilization and surface treatment

    Energy Technology Data Exchange (ETDEWEB)

    Chin, O. H.; Lai, C. K.; Choo, C. Y.; Wong, C. S.; Nor, R. M. [Plasma Technology Research Centre, Physics Department, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Thong, K. L. [Microbiology Division, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2015-04-24

    Atmospheric pressure non-thermal dielectric barrier discharges can be generated in different configurations for different applications. For sterilization, a parallel-plate electrode configuration with glass dielectric that discharges in air was used. Gram-negative bacteria (Escherichia coli and Salmonella enteritidis) and Gram-positive bacteria (Bacillus cereus) were successfully inactivated using sinusoidal high voltage of ∼15 kVp-p at 8.5 kHz. In the surface treatment, a hemisphere and disc electrode arrangement that allowed a plasma jet to be extruded under controlled nitrogen gas flow (at 9.2 kHz, 20 kVp-p) was applied to enhance the wettability of PET (Mylar) film.

  12. Luminous Activity Study of a Long Atmospheric Pressure DBD Afterglow

    Institute of Scientific and Technical Information of China (English)

    E.PANOUSIS; F.CLEMENT; N.SPYROU; J.F.LOISEAU; C.MONGE; B.HELD

    2007-01-01

    The experimental work reported here is devoted to the study of the luminous activity of a long dielectric barrier discharge (DBD) afterglow at atmospheric pressure.The discharge plasma is generated in a commercially available (AcXys Technologies) reactor,using a N2 flow of a few tens SL/min,whereas the luminous afterglow when channelled into a quartz tube extends at a distance of 50 cm,finishing in a luminous arrow at the tube's exit.The luminous activity of the afterglow is studied by means of photomultiplier scans and optical emission spectroscopy,revealing an interesting transient phase.An attempt is made to correlate this effect with the active species' creation and destruction mechanisms.

  13. Sterilization of Turmeric by Atmospheric Pressure Dielectric Barrier Discharge Plasma

    Science.gov (United States)

    Setareh, Salarieh; Davoud, Dorranian

    2013-11-01

    In this study atmospheric pressure dielectric barrier discharge (DBD) plasma has been employed for sterilizing dry turmeric powders. A 6 kV, 6 kHz frequency generator was used to generate plasma with Ar, Ar/O2, He, and He/O2 gases between the 5 mm gap of two quartz covered electrodes. The complete sterilization time of samples due to plasma treatment was measured. The most important contaminant of turmeric is bacillus subtilis. The results show that the shortest sterilization time of 15 min is achieved by exposing the samples to Ar/O2 plasma. Survival curves of samples are exponential functions of time and the addition of oxygen to plasma leads to a significant increase of the absolute value of time constant of the curves. Magnitudes of protein and DNA in treated samples were increased to a similar value for all samples. Taste, color, and solubility of samples were not changed after the plasma treatment.

  14. Development of ac corona discharge modes at atmospheric pressure

    International Nuclear Information System (INIS)

    Corona discharges in gases exist under several distinctive forms. In this paper, a survey study has been made of ac corona discharge modes generated in some different gases fed in a wire-duct reactor with a constant rate of flowing at atmospheric pressure. The properties of different corona modes are analyzed under some condition transitions from Trichel pulses to a steady glow. In the course of the presented experimental work, numerous apparent contradictions with earlier observations necessitated further study and are given to provide more information on the physical mechanisms of the ac corona discharges. Furthermore, we have gained insight into some new technologies and applications of the environmentally friendly corona and plasma discharges.

  15. Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Robert F. Hicks; Gary S. Selwyn

    2001-01-09

    Project was to develop a low-cost, environmentally benign technology for the decontamination and decommissioning of transuranic waste. With the invention of the atmospheric-pressure plasma jet the goal was achieved. This device selectively etches heavy metals from surfaces, rendering objects radiation free and suitable for decommissioning. The volatile reaction products are captured on filters, which yields a tremendous reduction in the volume of the waste. Studies on tantalum, a surrogate material for plutonium, have shown that etch rate of 6.0 microns per minute can be achieved under mild conditions. Over the past three years, we have made numerous improvements in the design of the plasma jet. It may now be operated for hundreds of hours and not undergo any degradation in performance. Furthermore, small compact units have been developed, which are easily deployed in the field.

  16. Surface wave propagation characteristics in atmospheric pressure plasma column

    International Nuclear Information System (INIS)

    In the typical experiments of surface wave sustained plasma columns at atmospheric pressure the ratio of collision to wave frequency (ν/ω) is much greater than unity. Therefore, one might expect that the usual analysis of the wave dispersion relation, performed under the assumption ν/ω = 0, cannot give adequate description of the wave propagation characteristics. In order to study these characteristics we have analyzed the wave dispersion relationship for arbitrary ν/ω. Our analysis includes phase and wave dispersion curves, attenuation coefficient, and wave phase and group velocities. The numerical results show that a turning back point appears in the phase diagram, after which a region of backward wave propagation exists. The experimentally observed plasma column is only in a region where wave propagation coefficient is higher than the attenuation coefficient. At the plasma column end the electron density is much higher than that corresponding to the turning back point and the resonance

  17. Diagnostics of atmospheric pressure capillary DBD oxygen plasma jet

    CERN Document Server

    Roy, N C; Pramanik, B K

    2015-01-01

    Atmospheric pressure capillary dielectric barrier oxygen discharge plasma jet is developed to generate non-thermal plasma using unipolar positive pulse power supply. Both optical and electrical techniques are used to investigate the characteristics of the produced plasma as function of applied voltage and gas flow rate. Analytical results obtained from the optical emission spectroscopic data reveal the gas temperature, rotational temperature, excitation temperature and electron density. Gas temperature and rotational temperature are found to decrease with increasing oxygen flow rate but increase linearly with applied voltage. It is exposed that the electron density is boosting up with enhanced applied voltage and oxygen flow rate, while the electron excitation temperature is reducing with rising oxygen flow rate. Electrical characterization demonstrates that the discharge frequency is falling with flow rate but increasing with voltage. The produced plasma is applied preliminarily to study the inactivation yie...

  18. 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.

  19. Acetonitrile Ion Suppression in Atmospheric Pressure Ionization Mass Spectrometry

    Science.gov (United States)

    Colizza, Kevin; Mahoney, Keira E.; Yevdokimov, Alexander V.; Smith, James L.; Oxley, Jimmie C.

    2016-11-01

    Efforts to analyze trace levels of cyclic peroxides by liquid chromatography/mass spectrometry gave evidence that acetonitrile suppressed ion formation. Further investigations extended this discovery to ketones, linear peroxides, esters, and possibly many other types of compounds, including triazole and menadione. Direct ionization suppression caused by acetonitrile was observed for multiple adduct types in both electrospray ionization and atmospheric pressure chemical ionization. The addition of only 2% acetonitrile significantly decreased the sensitivity of analyte response. Efforts to identify the mechanism were made using various nitriles. The ion suppression was reduced by substitution of an acetonitrile hydrogen with an electron-withdrawing group, but was exacerbated by electron-donating or steric groups adjacent to the nitrile. Although current theory does not explain this phenomenon, we propose that polar interactions between the various functionalities and the nitrile may be forming neutral aggregates that manifest as ionization suppression.

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

    International Nuclear Information System (INIS)

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

  1. Controlled Microdroplet Transport in an Atmospheric Pressure Microplasma

    CERN Document Server

    Maguire, P D; Kelsey, C P; Bingham, A; Montgomery, E P; Bennet, E D; Potts, H E; Rutherford, D; McDowell, D A; Diver, D A; Mariotti, D

    2015-01-01

    We report the controlled injection of near-isolated micron-sized liquid droplets into a low temperature He-Ne steady-state rf plasma at atmospheric pressure. The H2O droplet stream is constrained within a 2 mm diameter quartz tube. Imaging at the tube exit indicates a log-normal droplet size distribution with an initial count mean diameter of 15 micrometers falling to 13 micrometers with plasma exposure. The radial velocity profile is approximately parabolic indicating near laminar flow conditions with the majority of droplets travelling at >75% of the local gas speed and having a plasma transit time of < 100 microseconds. The maximum gas temperature, determined from nitrogen spectral lines, was below 400 K and the observed droplet size reduction implies additional factors beyond standard evaporation, including charge and surface chemistry effects. The successful demonstration of controlled microdroplet streams opens up possibilities for gas-phase microreactors and remote delivery of active species for pla...

  2. Electron-ion recombination study in argon at atmospheric pressure

    International Nuclear Information System (INIS)

    This study deals with a wall-stabilized arc burning in argon at atmospheric pressure. A transient mode is obtained using a fast thyristor connected to the electrodes, which short-circuits the discharge. By means of two wavelengths laser interferometry and spectroscopy measurements we have determined the temporal changes of the electron density, ground state atom density and excited atom density. We have shown that, when the electric field is suppressed, the electron temperature rapidly decreases to the gas temperature before changing electron and atom densities. This phenomenon is applied to determine the gas temperature and to evaluate the role played by ionization in electron density balance. The coefficients of ambipolar diffusion, ionization and recombination and an apparent recombination coefficient are determined versus electron temperature and compared with theoretical values

  3. Sterilization of Surfaces with a Handheld Atmospheric Pressure Plasma

    Science.gov (United States)

    Hicks, Robert; Habib, Sara; Chan, Wai; Gonzalez, Eleazar; Tijerina, A.; Sloan, Mark

    2009-10-01

    Low temperature, atmospheric pressure plasmas have shown great promise for decontaminating the surfaces of materials and equipment. In this study, an atmospheric pressure, oxygen and argon plasma was investigated for the destruction of viruses, bacteria, and spores. The plasma was operated at an argon flow rate of 30 L/min, an oxygen flow rate of 20 mL/min, a power density of 101.0 W/cm^3 (beam area = 5.1 cm^2), and at a distance from the surface of 7.1 mm. An average 6log10 reduction of viable spores was obtained after only 45 seconds of exposure to the reactive gas. By contrast, it takes more than 35 minutes at 121^oC to sterilize anthrax in an autoclave. The plasma properties were investigated by numerical modeling and chemical titration with nitric oxide. The numerical model included a detailed reaction mechanism for the discharge as well as for the afterglow. It was predicted that at a delivered power density of 29.3 W/cm^3, 30 L/min argon, and 0.01 volume% O2, the plasma generated 1.9 x 10^14 cm-3 O atoms, 1.6 x 10^12 cm-3 ozone, 9.3 x 10^13 cm-3 O2(^1δg), and 2.9 x 10^12 cm-3 O2(^1σ^+g) at 1 cm downstream of the source. The O atom density measured by chemical titration with NO was 6.0 x 10^14 cm-3 at the same conditions. It is believe that the oxygen atoms and the O2(^1δg) metastables were responsible for killing the anthrax and other microorganisms.

  4. Mass Spectrometry of Atmospheric Pressure Surface Wave Discharges

    Science.gov (United States)

    Ridenti, M. A.; Souza-Corrêa, J. A.; Amorim, J.

    2016-05-01

    By applying mass spectrometry techniques, we carried out measurements of ionic mass spectrum and their energy distribution in order to investigate an atmospheric argon discharge by using a surfatron surface-wave device. The mass and energy distribution measurements were performed with fixed flow rate (2.5 SLM) of pure argon gas (99.999%) and different Ar-O2 gas mixture compositions (99-1, 98-2 and 97-3). The mass spectra and energy distributions were recorded for Ar+, O+, O+ 2, N+ and N2 +. The axial distribution profiles of ionic mass and their energy were obtained for different experimental conditions as a function of the plasma length. The results showed that the peak of the positive ion energy distributions shifted to higher energies and also that the distribution width increased as the distance between the sampling orifice and the launcher gap was increased. It was also found that under certain experimental conditions the ion flux of atomic species were higher than the ion flux of their diatomic counterpart. The motivation of this study was to obtain a better understanding of a surface wave discharge in atmospheric pressure that may play a key role on new second generation biofuel technologies.

  5. Atmospheric Pressure Effects on Cryogenic Storage Tank Boil-Off

    Science.gov (United States)

    Sass, J. P.; Frontier, C. R.

    2007-01-01

    The Cryogenics Test Laboratory (CTL) at the Kennedy Space Center (KSC) routinely utilizes cryostat test hardware to evaluate comparative and absolute thermal conductivities of a wide array of insulation systems. The test method is based on measurement of the flow rate of gas evolved due to evaporative boil-off of a cryogenic liquid. The gas flow rate typically stabilizes after a period of a couple of hours to a couple of days, depending upon the test setup. The stable flow rate value is then used to calculate the thermal conductivity for the insulation system being tested. The latest set of identical cryostats, 1,000-L spherical tanks, exhibited different behavior. On a macro level, the flow rate did stabilize after a couple of days; however the stable flow rate was oscillatory with peak to peak amplitude of up to 25 percent of the nominal value. The period of the oscillation was consistently 12 hours. The source of the oscillation has been traced to variations in atmospheric pressure due to atmospheric tides similar to oceanic tides. This paper will present analysis of this phenomenon, including a calculation that explains why other cryostats are not affected by it.

  6. Trends in surface engineering of biomaterials: atmospheric pressure plasma deposition of coatings for biomedical applications

    Science.gov (United States)

    da Ponte, G.; Sardella, E.; Fanelli, F.; D'Agostino, R.; Favia, P.

    2011-11-01

    Cold plasma processes for surface engineering of biomaterials and biomedical devices are traditionally performed at low pressure; more and more, though, surface modification plasma processes at atmospheric pressure are also gaining popularity. This short review is aimed to list briefly atmospheric pressure plasma processes reported, in the last decade, for adapting the surface of materials to the best interactions with cells, bacteria and biomolecules.

  7. Comparison of Intraocular Pressure, Blood Pressure, Ocular Perfusion Pressure and Blood Flow Fluctuations During Dorzolamide Versus Timolol Add-On Therapy in Prostaglandin Analogue Treated Glaucoma Subjects

    Directory of Open Access Journals (Sweden)

    Ruta Barsauskaite

    2012-03-01

    Full Text Available Objective: To compare the effects of dorzolamide and timolol add-on therapy in open-angle glaucoma (OAG patients previously treated with prostaglandin analogue (Pg, by evaluating fluctuations in the intraocular (IOP, blood (BP, ocular perfusion pressures (OPP and retrobulbar blood flow (RBF parameters. Methods: 35 OAG patients (35 eyes, 31 women (88.6% age 63.3 (8.9 years were evaluated in a 3 month randomized, cross-over, single-masked study. During the experiments BP, heart rate, IOP and OPP were assessed 4 times per day (8–12–16–20 h. RBF was measured twice per day (8–20 h using Color Doppler imaging in the ophthalmic (OA, central retinal (CRA, nasal (nSPCA and temporal (tSPCA posterior ciliary arteries. In each vessel, peak systolic velocity (PSV and end-diastolic velocity (EDV were assessed and vascular resistance (RI calculated. Results: Both add-on therapies lowered IOP in a statistically significant manner from 15.7 ± 2.4 mmHg at latanoprost baseline to 14.9 ± 2.2 mmHg using dorzolamide (p < 0.001 and 14.2 ± 1.9 mmHg using timolol (p < 0.001. The IOP lowering effect was statistically significant at 20 h, favoring timolol as compared to dorzolamide (1.4 ± 2.4 vs. 0.2 ± 2.1 mmHg, (p < 0.05. Dorzolamide add-on therapy showed smaller IOP (2.0 ± 1.4, SPP (13.3 ± 7.9, systolic BP (13.5 ± 8.7 and diastolic BP (8.4 ± 5.4 fluctuations as compared to both latanoprost baseline or timolol add-on therapies. Higher difference between morning and evening BP was correlated to decreased evening CRA EDV in the timolol group (c = −0.41; p = 0.01. With increased MAP in the morning or evening hours, we found increased evening OA RI in timolol add-on group (c = 0.400, p = 0.02; c = 0.513, p = 0.002 accordingly. Higher MAP fluctuations were related to impaired RBF parameters during evening hours-decreased CRA EDV (c = −0.408; p = 0.01, increased CRA RI (c = 0.576; p < 0.001 and tSPCA RI (c = 0.356; p = 0.04 in the dorzolamide group and

  8. Development of Simplified Atmospheric-Pressure Plasma Nitriding

    Science.gov (United States)

    Yamamoto, Hirofumi; Ichiki, Ryuta; Maeda, Akihide; Yamanouchi, Kenta; Akamine, Shuichi; Kanazawa, Seiji; Oita University Team

    2015-09-01

    Nitriding treatment is one of the surface hardening technologies, applied to dies and automobile components. In recent industry, low-pressure nitriding treatment using vacuum system is mainstream. On the other hand, we have originally developed an atmospheric-pressure plasma nitriding which do not need vacuum system. However we needed an air-tight container to purge residual oxygen and external heater to control treatment temperature. To make this technique practical, we addressed to construct a simplified treatment system, where treatment temperature is controlled by thermal plasma itself and oxygen purging is achieved by a simple cover. This means that any air-tight container and external heater is not necessary. As a result, surface temperature is controlled by changing treatment gap from nozzle tip to steel surface. We succeeded in controlling well thickness of hardened layer by adjusting treatment temperature even in such a simplified system. In the conference, we also discuss experimental results for hardening complex shaped materials by using our simplified nitriding.

  9. Numerical investigation on pressure fluctuations in centrifugal compressor with different inlet guide vanes pre-whirl angles

    Science.gov (United States)

    Wang, Y. C.; Shi, M.; Cao, S. L.; Li, Z. H.

    2013-12-01

    The pressure fluctuations in a centrifugal compressor with different inlet guide vanes (IGV) pre-whirl angles were investigated numerically, as well as the pre-stress model and static structural of blade. The natural frequency was evaluated by pre-stress model analysis. The results show that, the aero-dynamic pressure acting on blade surface is smaller than rotation pre-stress, which wouldn't result in large deformation of blade. The natural frequencies with rotation pre-stress are slightly higher than without rotation pre-stress. The leading mechanism of pressure fluctuations for normal conditions is the rotor-stator (IGVs) interaction, while is serious flow separations for conditions that are close to surge line. A few frequency components in spectra are close to natural frequency, which possibly result in resonant vibration if amplitude is large enough, which is dangerous for compressor working, and should be avoided.

  10. The ionization mechanisms in direct and dopant-assisted atmospheric pressure photoionization and atmospheric pressure laser ionization.

    Science.gov (United States)

    Kauppila, Tiina J; Kersten, Hendrik; Benter, Thorsten

    2014-11-01

    A novel, gas-tight API interface for gas chromatography-mass spectrometry was used to study the ionization mechanism in direct and dopant-assisted atmospheric pressure photoionization (APPI) and atmospheric pressure laser ionization (APLI). Eight analytes (ethylbenzene, bromobenzene, naphthalene, anthracene, benzaldehyde, pyridine, quinolone, and acridine) with varying ionization energies (IEs) and proton affinities (PAs), and four common APPI dopants (toluene, acetone, anisole, and chlorobenzene) were chosen. All the studied compounds were ionized by direct APPI, forming mainly molecular ions. Addition of dopants suppressed the signal of the analytes with IEs above the IE of the dopant. For compounds with suitable IEs or Pas, the dopants increased the ionization efficiency as the analytes could be ionized through dopant-mediated gas-phase reactions, such as charge exchange, proton transfer, and other rather unexpected reactions, such as formation of [M + 77](+) in the presence of chlorobenzene. Experiments with deuterated toluene as the dopant verified that in case of proton transfer, the proton originated from the dopant instead of proton-bound solvent clusters, as in conventional open or non-tight APPI sources. In direct APLI using a 266 nm laser, a narrower range of compounds was ionized than in direct APPI, because of exceedingly high IEs or unfavorable two-photon absorption cross-sections. Introduction of dopants in the APLI system changed the ionization mechanism to similar dopant-mediated gas-phase reactions with the dopant as in APPI, which produced mainly ions of the same form as in APPI, and ionized a wider range of analytes than direct APLI.

  11. Ionization of EPA contaminants in direct and dopant-assisted atmospheric pressure photoionization and atmospheric pressure laser ionization.

    Science.gov (United States)

    Kauppila, Tiina J; Kersten, Hendrik; Benter, Thorsten

    2015-06-01

    Seventy-seven EPA priority environmental pollutants were analyzed using gas chromatography-mass spectrometry (GC-MS) equipped with an optimized atmospheric pressure photoionization (APPI) and an atmospheric pressure laser ionization (APLI) interface with and without dopants. The analyzed compounds included e.g., polycyclic aromatic hydrocarbons (PAHs), nitro compounds, halogenated compounds, aromatic compounds with phenolic, acidic, alcohol, and amino groups, phthalate and adipatic esters, and aliphatic ethers. Toluene, anisole, chlorobenzene, and acetone were tested as dopants. The widest range of analytes was ionized using direct APPI (66/77 compounds). The introduction of dopants decreased the amount of compounds ionized in APPI (e.g., 54/77 with toluene), but in many cases the ionization efficiency increased. While in direct APPI the formation of molecular ions via photoionization was the main ionization reaction, dopant-assisted (DA) APPI promoted ionization reactions, such as charge exchange and proton transfer. Direct APLI ionized a much smaller amount of compounds than APPI (41/77 compounds), showing selectivity towards compounds with low ionization energies (IEs) and long-lived resonantly excited intermediate states. DA-APLI, however, was able to ionize a higher amount of compounds (e.g. 51/77 with toluene), as the ionization took place entirely through dopant-assisted ion/molecule reactions similar to those in DA-APPI. Best ionization efficiency in APPI and APLI (both direct and DA) was obtained for PAHs and aromatics with O- and N-functionalities, whereas nitro compounds and aliphatic ethers were the most difficult to ionize. Halogenated aromatics and esters were (mainly) ionized in APPI, but not in APLI.

  12. Application of atmospheric pressure plasma in polymer and composite adhesion

    Science.gov (United States)

    Yu, Hang

    An atmospheric pressure helium and oxygen plasma was used to investigate surface activation and bonding in polymer composites. This device was operated by passing 1.0-3.0 vol% of oxygen in helium through a pair of parallel plate metal electrodes powered by 13.56 or 27.12 MHz radio frequency power. The gases were partially ionized between the capacitors where plasma was generated. The reactive species in the plasma were carried downstream by the gas flow to treat the substrate surface. The temperature of the plasm gas reaching the surface of the substrate did not exceed 150 °C, which makes it suitable for polymer processing. The reactive species in the plasma downstream includes ~ 1016-1017 cm-3 atomic oxygen, ~ 1015 cm-3 ozone molecule, and ~ 10 16 cm-3 metastable oxygen molecule (O2 1Deltag). The substrates were treated at 2-5 mm distance from the exit of the plasma. Surface properties of the substrates were characterized using water contact angle (WCA), atomic force microscopy (AFM), infrared spectroscopy (IR), and X-ray photoelectron spectroscopy (XPS). Subsequently, the plasma treated samples were bonded adhesively or fabricated into composites. The increase in mechanical strength was correlated to changes in the material composition and structure after plasma treatment. The work presented hereafter establishes atmospheric pressure plasma as an effective method to activate and to clean the surfaces of polymers and composites for bonding. This application can be further expanded to the activation of carbon fibers for better fiber-resin interactions during the fabrication of composites. Treating electronic grade FR-4 and polyimide with the He/O2 plasma for a few seconds changed the substrate surface from hydrophobic to hydrophilic, which allowed complete wetting of the surface by epoxy in underfill applications. Characterization of the surface by X-ray photoelectron spectroscopy shows formation of oxygenated functional groups, including hydroxyl, carbonyl, and

  13. PRESSURE COMPENSATION METHOD OF UNDERWATER HYDRAULIC SYSTEM WITH HYDRAULIC POWER UNIT BEING UNDER ATMOSPHERIC CIRCUMSTANCE AND PRESSURE COMPENSATED VALVE

    Institute of Scientific and Technical Information of China (English)

    Wang Qingfeng; Li Yanmin; Zhong Tianyu; Xu Guohua

    2005-01-01

    Based on the analysis of the-state-of-the-art of pressure compensation of underwater hydraulic systems (UHSs), a new method of pressure compensation of UHSs, whose hydraulic power unit is in the atmospheric circumstance, is proposed. And a pilot-operated relief valve with pressure compensation is realized. The pressure compensation precision is guaranteed by direct detection. Its dynamic performance and stability are improved by a dynamic feedback. Theoretical study, simulation and experiment show that the pilot-operated relief valve with pressure compensation has a fine property of tracking underwater ambient pressure and meet the requirement of underwater ambient pressure compensation.

  14. High Pressure Atmospheric Sampling Inlet System for Venus or the Gas Giants Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Thorleaf Research, Inc. proposes to develop a miniaturized high pressure atmospheric sampling inlet system for sample acquisition in extreme planetary environments,...

  15. Mean, tidal, and fluctuating winds in the middle atmosphere and lower thermosphere observed during MAP/WINE in Northern Scandinavia

    Science.gov (United States)

    Roettger, J.

    1989-01-01

    During the MAP/WINE campaign in winter 1983 to 1984 several instrumental techniques, such as meteorological rockets, sounding rockets, MST radar and incoherent scatter radar, were applied to measure wind velocities in the middle atmosphere. Profiles of mean, tidal and fluctuating wind velocities were obtained up to 90 to 100 km altitude. These are compared with profiles from models, measurements at other locations and at other times as well as satellite derived data. The results are discussed in terms of ageostropic winds, planetary waves, tidal modes and the possibility of a saturated gravity wave spectrum in the mesosphere.

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

    Science.gov (United States)

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

    2011-10-01

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

  17. Atmospheric pressure X-ray photoelectron spectroscopy apparatus: Bridging the pressure gap.

    Science.gov (United States)

    Velasco-Vélez, J J; Pfeifer, V; Hävecker, M; Wang, R; Centeno, A; Zurutuza, A; Algara-Siller, G; Stotz, E; Skorupska, K; Teschner, D; Kube, P; Braeuninger-Weimer, P; Hofmann, S; Schlögl, R; Knop-Gericke, A

    2016-05-01

    One of the main goals in catalysis is the characterization of solid/gas interfaces in a reaction environment. The electronic structure and chemical composition of surfaces become heavily influenced by the surrounding environment. However, the lack of surface sensitive techniques that are able to monitor these modifications under high pressure conditions hinders the understanding of such processes. This limitation is known throughout the community as the "pressure gap." We have developed a novel experimental setup that provides chemical information on a molecular level under atmospheric pressure and in presence of reactive gases and at elevated temperatures. This approach is based on separating the vacuum environment from the high-pressure environment by a silicon nitride grid-that contains an array of micrometer-sized holes-coated with a bilayer of graphene. Using this configuration, we have investigated the local electronic structure of catalysts by means of photoelectron spectroscopy and in presence of gases at 1 atm. The reaction products were monitored online by mass spectrometry and gas chromatography. The successful operation of this setup was demonstrated with three different examples: the oxidation/reduction reaction of iridium (noble metal) and copper (transition metal) nanoparticles and with the hydrogenation of propyne on Pd black catalyst (powder). PMID:27250406

  18. Influence of geomagnetic activity and atmospheric pressure on human arterial pressure during the solar cycle 24

    Science.gov (United States)

    Azcárate, T.; Mendoza, B.; Levi, J. R.

    2016-11-01

    We performed a study of the systolic (SBP) and diastolic (DBP) arterial blood pressure behavior under natural variables such as the atmospheric pressure (AtmP) and the horizontal geomagnetic field component (H). We worked with a sample of 304 healthy normotense volunteers, 152 men and 152 women, with ages between 18 and 84 years in Mexico City during the period 2008-2014, corresponding to the minimum, ascending and maximum phases of the solar cycle 24. The data was divided by gender, age and day/night cycle. We studied the time series using three methods: Correlations, bivariate and superposed epochs (within a window of three days around the day of occurrence of a geomagnetic storm) analysis, between the SBP and DBP and the natural variables (AtmP and H). The correlation analysis indicated correlation between the SBP and DBP and AtmP and H, being the largest during the night. Furthermore, the correlation and bivariate analysis showed that the largest correlations are between the SBP and DBP and the AtmP. The superposed epoch analysis found that the largest number of significant SBP and DBP changes occurred for women. Finally, the blood pressure changes are larger during the solar minimum and ascending solar cycle phases than during the solar maximum; the storms of the minimum were more intense than those of the maximum and this could be the reason of behavior of the blood pressure changes along the solar cycle.

  19. The effects of atmospheric pressure on infrared reflectance spectra of Martian analogs

    Science.gov (United States)

    Bishop, Janice L.; Pieters, Carle M.; Pratt, Stephen F.; Patterson, William

    1993-01-01

    The use of terrestrial samples as analogs of Mars soils are complicated by the Martian atmosphere. Spectral features due to the Martian atmosphere can be removed from telescopic spectra of Mars and ISM spectra of Mars, but this does not account for any spectral differences resulting from atmospheric pressure or any interactions between the atmosphere and the surface. We are examining the effects of atmospheric pressure on reflectance spectra of powdered samples in the laboratory. Contrary to a previous experiment with granite, no significant changes in albedo or the Christiansen feature were observed from 1 bar pressure down to a pressure of 8 micrometers Hg. However, reducing the atmospheric pressure does have a pronounced affect on the hydration features, even for samples retained in a dry environment for years.

  20. Atmospheric pressure plasma assisted calcination of composite submicron fibers

    Science.gov (United States)

    Medvecká, Veronika; Kováčik, Dušan; Tučeková, Zlata; Zahoranová, Anna; Černák, Mirko

    2016-08-01

    The plasma assisted calcination of composite organic/inorganic submicron fibers for the preparation of inorganic fibers in submicron scale was studied. Aluminium butoxide/polyvinylpyrrolidone fibers prepared by electrospinning were treated using low-temperature plasma generated by special type of dielectric barrier discharge, so called diffuse coplanar surface barrier discharge (DCSBD) at atmospheric pressure in ambient air, synthetic air, oxygen and nitrogen. Effect of plasma treatment on base polymer removal was investigated by using Attenuated total reflectance - Fourier transform infrared (ATR-FTIR) spectroscopy. Influence of working gas on the base polymer reduction was studied by energy-dispersive X-ray spectroscopy (EDX) and CHNS elemental analysis. Changes in fibers morphology were observed by scanning electron microscopy (SEM). High efficiency of organic template removal without any degradation of fibers was observed after plasma treatment in ambient air. Due to the low-temperature approach and short exposure time, the plasma assisted calcination is a promising alternative to the conventional thermal calcination. Contribution to the topical issue "6th Central European Symposium on Plasma Chemistry (CESPC-6)", edited by Nicolas Gherardi, Ester Marotta and Cristina Paradisi

  1. Atmospheric pressure arc discharge with ablating graphite anode

    Energy Technology Data Exchange (ETDEWEB)

    Nemchinsky, V. A. [Keiser University, Fort Lauderdale Campus, FL, 33309, USA; Raitses, Y. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

    2015-05-18

    The anodic carbon arc discharge is used to produce carbon nanoparticles. Recent experiments with the carbon arc at atmospheric pressure helium demonstrated the enhanced ablation rate for narrow graphite anodes resulting in high deposition rates of carbonaceous products on the copper cathode (Fetterman et al 2008 Carbon 46 1322–6). The proposed model explains these results with interconnected steady-state models of the cathode and the anode processes. When considering cathode functioning, the model predicts circulation of the particles in the near-cathode region: evaporation of the cathode material, ionization of evaporated atoms and molecules in the near-cathode plasma, return of the resulting ions to the cathode, surface recombination of ions and electrons followed again by cathode evaporation etc. In the case of the low anode ablation rate, the ion acceleration in the cathode sheath provides the major cathode heating mechanism. In the case of an intensive anode ablation, an additional cathode heating is due to latent fusion heat of the atomic species evaporated from the anode and depositing at the cathode. Using the experimental arc voltage as the only input discharge parameter, the model allows us to calculate the anode ablation rate. A comparison of the results of calculations with the available experimental data shows reasonable agreement.

  2. Using atmospheric pressure plasma treatment for treating grey cotton fabric.

    Science.gov (United States)

    Kan, Chi-Wai; Lam, Chui-Fung; Chan, Chee-Kooi; Ng, Sun-Pui

    2014-02-15

    Conventional wet treatment, desizing, scouring and bleaching, for grey cotton fabric involves the use of high water, chemical and energy consumption which may not be considered as a clean process. This study aims to investigate the efficiency of the atmospheric pressure plasma (APP) treatment on treating grey cotton fabric when compared with the conventional wet treatment. Grey cotton fabrics were treated with different combinations of plasma parameters with helium and oxygen gases and also through conventional desizing, scouring and bleaching processes in order to obtain comparable results. The results obtained from wicking and water drop tests showed that wettability of grey cotton fabrics was greatly improved after plasma treatment and yielded better results than conventional desizing and scouring. The weight reduction of plasma treated grey cotton fabrics revealed that plasma treatment can help remove sizing materials and impurities. Chemical and morphological changes in plasma treated samples were analysed by FTIR and SEM, respectively. Finally, dyeability of the plasma treated and conventional wet treated grey cotton fabrics was compared and the results showed that similar dyeing results were obtained. This can prove that plasma treatment would be another choice for treating grey cotton fabrics. PMID:24507269

  3. Pulsed, atmospheric pressure plasma source for emission spectrometry

    Science.gov (United States)

    Duan, Yixiang; Jin, Zhe; Su, Yongxuan

    2004-05-11

    A low-power, plasma source-based, portable molecular light emission generator/detector employing an atmospheric pressure pulsed-plasma for molecular fragmentation and excitation is described. The average power required for the operation of the plasma is between 0.02 W and 5 W. The features of the optical emission spectra obtained with the pulsed plasma source are significantly different from those obtained with direct current (dc) discharge higher power; for example, strong CH emission at 431.2 nm which is only weakly observed with dc plasma sources was observed, and the intense CN emission observed at 383-388 nm using dc plasma sources was weak in most cases. Strong CN emission was only observed using the present apparatus when compounds containing nitrogen, such as aniline were employed as samples. The present apparatus detects dimethylsulfoxide at 200 ppb using helium as the plasma gas by observing the emission band of the CH radical. When coupled with a gas chromatograph for separating components present in a sample to be analyzed, the present invention provides an apparatus for detecting the arrival of a particular component in the sample at the end of the chromatographic column and the identity thereof.

  4. Hydrocarbon analysis using desorption atmospheric pressure chemical ionization

    KAUST Repository

    Jjunju, Fred P M

    2013-07-01

    Characterization of the various petroleum constituents (hydronaphthalenes, thiophenes, alkyl substituted benzenes, pyridines, fluorenes, and polycyclic aromatic hydrocarbons) was achieved under ambient conditions without sample preparation by desorption atmospheric pressure chemical ionization (DAPCI). Conditions were chosen for the DAPCI experiments to control whether ionization was by proton or electron transfer. The protonated molecule [M+H]+ and the hydride abstracted [MH]+ form were observed when using an inert gas, typically nitrogen, to direct a lightly ionized plasma generated by corona discharge onto the sample surface in air. The abundant water cluster ions generated in this experiment react with condensed-phase functionalized hydrocarbon model compounds and their mixtures at or near the sample surface. On the other hand, when naphthalene was doped into the DAPCI gas stream, its radical cation served as a charge exchange reagent, yielding molecular radical cations (M+) of the hydrocarbons. This mode of sample ionization provided mass spectra with better signal/noise ratios and without unwanted side-products. It also extended the applicability of DAPCI to petroleum constituents which could not be analyzed through proton transfer (e.g., higher molecular PAHs such as chrysene). The thermochemistry governing the individual ionization processes is discussed and a desorption/ionization mechanism is inferred. © 2012 Elsevier B.V.

  5. Basic characteristics of an atmospheric pressure rf generated plasma jet

    Institute of Scientific and Technical Information of China (English)

    Wang Shou-Guo; Li Hai-Jiang; Ye Tian-Chun; Zhao Ling-Li

    2004-01-01

    A plasma jet has been developed which operates using radio frequency (rf) power and produces a stable homogeneous discharge at atmospheric pressure. Its discharge characteristics, especially the dependence of stable discharge operating range on the feed gas, were studied, and the electric parameters such as RMS current, RMS voltage and reflected power were obtained with different gas flows. These studies indicate that there is an optimum range of operation of the plasma jet for a filling with a gas mixture of He and O2. Two "failure" modes of the discharge are identified.One is a filamentary arc when the input power is raised above a critical level, another is that the discharge disappears gradually as the addition of O2 approaches 3.2%. Possible explanations for the two failure modes have been given. The current and voltage waveform measurements show that there is a clear phase shift between normal and failure modes.In addition, Ⅰ-Ⅴ curves as a function of pure helium and for 1% addition of oxygen have been studied.

  6. Methane coupling in microwave plasma under atmospheric pressure

    Institute of Scientific and Technical Information of China (English)

    Changsheng Shen; Dekun Sun; Hongsheng Yang

    2011-01-01

    Methane coupling in microwave plasma under atmospheric pressure has been investigated.The effects of molar ratio n(CH4)/n(H2),flow rate and microwave power on the reaction have been studied.(1) With the decrease of n(CH4)/n(H2) ratio,methane conversion,C2 hydrocarbon yield,energy yield and space-time yield of acetylene increased,but the yield of carbon deposit decreased.(2) With the increase of microwave power,energy yield of acetylene decreased,but space-time yield of acetylene increased.(3) With the increase of flow rate,energy yield and space-time yield of acetylene increased first and then decreased.Finally,under the reaction conditions of CH4 flow rate of 700 mL/min,n(CH4)/n(H2) ratio of 1/4 and microwave power of 400 W,the energy yield and space-time yield of acetylene could reach 0.337 mmol/kJ and 12.3 mol/(s·m3),respectively.The reaction mechanism of methane coupling in microwave plasma has been investigated based on the thermodynamics of chemical reaction.Interestingly,the acetylene yield of methane coupling in microwave plasma was much higher than the maximum thermodynamic yield of acetylene.This phenomenon was tentatively explained from non-expansion work in the microwave plasma system.

  7. On the mechanism of atmospheric pressure plasma plume

    Science.gov (United States)

    Chen, Longwei; Zhao, Peng; Shu, Xingsheng; Shen, Jie; Meng, Yuedong

    2010-08-01

    For the purpose of unveiling the parameters influencing the length of atmospheric pressure plasma plume, an over 165 cm long argon plasma plume is generated in the quartz tube attached to the nozzle of the device. Dependence of plasma length on discharge parameters such as applied voltage, frequency of power supply, and argon gas flow rate was investigated. Experimental results indicated that (a) the applied voltage plays crucial roles on plasma plume length, that is, the plasma plume length exponentially increases with the applied voltage, (b) the plasma plume length increases with frequency, more obviously when the applied voltage is higher, (c) the plasma plume length increases with argon gas flow rate, reaches its maximum at critical value of the gas flow rate, and then decreases again. An evaluation of the physical phenomena involved in streamer propagation, particularly of the energy balance, was investigated. The numerical results were qualitatively consistent with previous experimental results by successfully indicating the high velocity of "plasma bullet" and providing physical mechanism of energy balance determining streamer length.

  8. Characteristics of Atmospheric Pressure Rotating Gliding Arc Plasmas

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hao; ZHU Fengsen; TU Xin; BO Zheng; CEN Kefa; LI Xiaodong

    2016-01-01

    In this work,a novel direct current (DC) atmospheric pressure rotating gliding arc (RGA) plasma reactor has been developed for plasma-assisted chemical reactions.The influence of the gas composition and the gas flow rate on the arc dynamic behaviour and the formation of reactive species in the N2 and air gliding arc plasmas has been investigated by means of electrical signals,high speed photography,and optical emission spectroscopic diagnostics.Compared to conventional gliding arc reactors with knife-shaped electrodes which generally require a high flow rate (e.g.,10-20 L/min) to maintain a long arc length and reasonable plasma discharge zone,in this RGA system,a lower gas flow rate (e.g.,2 L/min) can also generate a larger effective plasma reaction zone with a longer arc length for chemical reactions.Two different motion patterns can be clearly observed in the N2 and air RGA plasmas.The time-resolved arc voltage signals show that three different arc dynamic modes,the arc restrike mode,takeover mode,and combined modes,can be clearly identified in the RGA plasmas.The occurrence of different motion and arc dynamic modes is strongly dependent on the composition of the working gas and gas flow rate.

  9. Characteristics of Atmospheric Pressure Rotating Gliding Arc Plasmas

    Science.gov (United States)

    Zhang, Hao; Zhu, Fengsen; Tu, Xin; Bo, Zheng; Cen, Kefa; Li, Xiaodong

    2016-05-01

    In this work, a novel direct current (DC) atmospheric pressure rotating gliding arc (RGA) plasma reactor has been developed for plasma-assisted chemical reactions. The influence of the gas composition and the gas flow rate on the arc dynamic behaviour and the formation of reactive species in the N2 and air gliding arc plasmas has been investigated by means of electrical signals, high speed photography, and optical emission spectroscopic diagnostics. Compared to conventional gliding arc reactors with knife-shaped electrodes which generally require a high flow rate (e.g., 10-20 L/min) to maintain a long arc length and reasonable plasma discharge zone, in this RGA system, a lower gas flow rate (e.g., 2 L/min) can also generate a larger effective plasma reaction zone with a longer arc length for chemical reactions. Two different motion patterns can be clearly observed in the N2 and air RGA plasmas. The time-resolved arc voltage signals show that three different arc dynamic modes, the arc restrike mode, takeover mode, and combined modes, can be clearly identified in the RGA plasmas. The occurrence of different motion and arc dynamic modes is strongly dependent on the composition of the working gas and gas flow rate. supported by National Natural Science Foundation of China (No. 51576174), the Specialized Research Fund for the Doctoral Program of Higher Education of China (No. 20120101110099) and the Fundamental Research Funds for the Central Universities (No. 2015FZA4011)

  10. Ultrasonic nebulization atmospheric pressure glow discharge - Preliminary study

    Science.gov (United States)

    Greda, Krzysztof; Jamroz, Piotr; Pohl, Pawel

    2016-07-01

    Atmospheric pressure glow microdischarge (μAPGD) generated between a small-sized He nozzle jet anode and a flowing liquid cathode was coupled with ultrasonic nebulization (USN) for analytical optical emission spectrometry (OES). The spatial distributions of the emitted spectra from the novel coupled USN-μAPGD system and the conventional μAPGD system were compared. In the μAPGD, the maxima of the intensity distribution profiles of the atomic emission lines Ca, Cd, In, K, Li, Mg, Mn, Na and Sr were observed in the near cathode region, whereas, in the case of the USN-μAPGD, they were shifted towards the anode. In the novel system, the intensities of the analytical lines of the studied metals were boosted from several to 35 times. As compared to the conventional μAPGD-OES with the introduction of analytes through the sputtering and/or the electrospray-like nebulization of the flowing liquid cathode solution, the proposed method with the USN introduction of analytes in the form of a dry aerosol provides improved detectability of the studied metals. The detection limits of metals achieved with the USN-μAPGD-OES method were in the range from 0.08 μg L- 1 for Li to 52 μg L- 1 for Mn.

  11. Blow-out limits of nonpremixed turbulent jet flames in a cross flow at atmospheric and sub-atmospheric pressures

    KAUST Repository

    Wang, Qiang

    2015-07-22

    The blow-out limits of nonpremixed turbulent jet flames in cross flows were studied, especially concerning the effect of ambient pressure, by conducting experiments at atmospheric and sub-atmospheric pressures. The combined effects of air flow and pressure were investigated by a series of experiments conducted in an especially built wind tunnel in Lhasa, a city on the Tibetan plateau where the altitude is 3650 m and the atmospheric pressure condition is naturally low (64 kPa). These results were compared with results obtained from a wind tunnel at standard atmospheric pressure (100 kPa) in Hefei city (altitude 50 m). The size of the fuel nozzles used in the experiments ranged from 3 to 8 mm in diameter and propane was used as the fuel. It was found that the blow-out limit of the air speed of the cross flow first increased (“cross flow dominant” regime) and then decreased (“fuel jet dominant” regime) as the fuel jet velocity increased in both pressures; however, the blow-out limit of the air speed of the cross flow was much lower at sub-atmospheric pressure than that at standard atmospheric pressure whereas the domain of the blow-out limit curve (in a plot of the air speed of the cross flow versus the fuel jet velocity) shrank as the pressure decreased. A theoretical model was developed to characterize the blow-out limit of nonpremixed jet flames in a cross flow based on a Damköhler number, defined as the ratio between the mixing time and the characteristic reaction time. A satisfactory correlation was obtained at relative strong cross flow conditions (“cross flow dominant” regime) that included the effects of the air speed of the cross flow, fuel jet velocity, nozzle diameter and pressure.

  12. Use of Heated Helium to Simulate Surface Pressure Fluctuations on the Launch Abort Vehicle During Abort Motor Firing

    Science.gov (United States)

    Panda, Jayanta; James, George H.; Burnside, Nathan J.; Fong, Robert; Fogt, Vincent A.

    2011-01-01

    The solid-rocket plumes from the Abort motor of the Multi-Purpose Crew Vehicle (MPCV, also know as Orion) were simulated using hot, high pressure, Helium gas to determine the surface pressure fluctuations on the vehicle in the event of an abort. About 80 different abort situations over a wide Mach number range, (0.3Helium plume and wind tunnel conditions were used to bracket different flow matching critera. This unique, yet cost-effective test used a custom-built hot Helium delivery system, and a 6% scale model of a part of the MPCV, known as the Launch Abort Vehicle. The test confirmed the very high level of pressure fluctuations on the surface of the vehicle expected during an abort. In general, the fluctuations were found to be dominated by the very near-field hydrodynamic fluctuations present in the plume shear-layer. The plumes were found to grow in size for aborts occurring at higher flight Mach number and altitude conditions. This led to an increase in the extent of impingement on the vehicle surfaces; however, unlike some initial expectations, the general trend was a decrease in the level of pressure fluctuations with increasing impingement. In general, the highest levels of fluctuations were found when the outer edges of the plume shear layers grazed the vehicle surface. At non-zero vehicle attitudes the surface pressure distributions were found to become very asymmetric. The data from these wind-tunnel simulations were compared against data collected from the recent Pad Abort 1 flight test. In spite of various differences between the transient flight situation and the steady-state wind tunnel simulations, the hot-Helium data were found to replicate the PA1 data fairly reasonably. The data gathered from this one-of-a-kind wind-tunnel test fills a gap in the manned-space programs, and will be used to establish the acoustic environment for vibro-acoustic qualification testing of the MPCV.

  13. Part 1 - Experimental study of the pressure fluctuations on propeller turbine runner blades during steady-state operation

    Science.gov (United States)

    Houde, S.; Fraser, R.; Ciocan, G. D.; Deschênes, C.

    2012-11-01

    A good evaluation of the unsteady pressure field on hydraulic turbine blades is critical in evaluating the turbine lifespan and its maintenance schedule. Low-head turbines such as Kaplan and Propeller, using a relatively low number of blades supported only at the hub, may also undergo significant deflections at the blade tips which will lead to higher amplitude vibration compared to Francis turbines. Furthermore, the precise evaluation of the unsteady pressure distribution on low-head turbines is still a challenge for computational fluid dynamics (CFD). Within the framework of an international research consortium on low-head turbines, a research project was instigated at the Hydraulic Machines Laboratory in Laval University (LAMH) to perform experimental measurements of the unsteady pressure field on propeller turbine model runner blades. The main objective of the project was to measure the pressure fluctuations on a wide band of frequencies, both in a blade-to-blade channel and on the pressure and suction side of the same blade, to provide validation data for CFD computations. To do so, a 32 channels telemetric data transmission system was used to extract the signal of 31 pressure transducers and two strain gages from the rotating part at an acquisition frequency of 5 KHz. The miniature piezoelectric pressure transducers were placed on two adjacent runner blades according to an estimated pressure distribution coming from flow simulations. Two suction sides and one pressure side were instrumented. The strain gages were mounted in full-bridge on both pressure and suction sides to measure the blade span wise deflection. In order to provide boundary conditions for flow simulations, the test bench conditions during the measurements were acquired. The measurements were made in different operating conditions ranging from part load, where a cavitating vortex occurs, to full load under different heads. The results enabled the identification and the quantification of the

  14. Pore pressure fluctuations of overlying aquifer during residual coal mining and water-soil stress coupling analysis

    Institute of Scientific and Technical Information of China (English)

    DONG Qing-hong; SUI Wang-hua; ZHANG Xiao-cui; MAO Zeng-min

    2009-01-01

    Three test models and a simulation model were constructed based on the prevailing conditions of the Taiping coalmine in order to analyze pore pressure fluctuations of an overlying aquifer during residual coal mining. As well, the relation between pore pressure and soil stress was evaluated. The model tests show the vibrations of pore pressure and soil stress as a result of mining activities. The simulation model tells of the response characteristics of pore pressure after mining and its distribution in the sand aquifer. The comparative analysis reveals that pore pressure and soil stress vibration are activated by unexpected events occurring in mines, such as collapsing roofs. An increased pore pressure zone always lies above the wall in front or behind the working face of a mine. Both pore pressure and vertical stress result in increasing and decreasing processes during movements of the working face of a mine. The vibration of pore pressure always precedes soil stress in the same area and ends with a sharp decline. Changes in pore pressure of sand aquifer are limited to the area of stress changes. Obvious changes are largely located in a very small frame over the mining face.

  15. The growth of organosilicon film using a hexamethyldisilazane/oxygen atmospheric pressure plasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Chun, E-mail: chunhuang@saturn.yzu.edu.tw; Wu, Shin-Yi; Tsai, Ching-Yuan; Liu, Wei-Ting

    2013-02-01

    An atmospheric pressure plasma jet, using a hexamethyldisilazane and oxygen mixture, was used to deposit an organosilicon thin film on polycarbonate (PC) substrates. The atmospheric pressure plasma jet deposited homogeneous thin films without unfavorable contamination from the plasma source. The surface properties of the organosilicon thin films were studied as a function of oxygen gas flow rate. The atmospheric pressure plasma deposited organosilicon thin films were analyzed using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, UV–vis spectrometry and atomic forced microscopy. Surface analysis showed that atmospheric pressure plasma deposited films are more inorganic as the oxygen flow rate increases. The UV–vis spectra, detected in the range 300–800 nm, demonstrated improved transparency in the visible region and increased absorption in UV region of the spectrum. The improved hardness of the atmospheric pressure plasma deposited PC substrates was measured using a pencil hardness testing method and this was related to the chemical composition of the plasma deposited organosilicon thin films. The plasma jet allowed deposition of the coating without a chamber. - Highlights: ► Organosilicon thin films on polycarbonate (PC) by atmospheric pressure plasma jet. ► Properties of SiOx films vary with the injected oxygen flow rate in the plasma jet. ► Improved hardness of atmospheric pressure plasma deposited SiOx films achieved. ► Double-pipe atmospheric pressure plasma jet suitable for chamberless deposition.

  16. The growth of organosilicon film using a hexamethyldisilazane/oxygen atmospheric pressure plasma jet

    International Nuclear Information System (INIS)

    An atmospheric pressure plasma jet, using a hexamethyldisilazane and oxygen mixture, was used to deposit an organosilicon thin film on polycarbonate (PC) substrates. The atmospheric pressure plasma jet deposited homogeneous thin films without unfavorable contamination from the plasma source. The surface properties of the organosilicon thin films were studied as a function of oxygen gas flow rate. The atmospheric pressure plasma deposited organosilicon thin films were analyzed using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, UV–vis spectrometry and atomic forced microscopy. Surface analysis showed that atmospheric pressure plasma deposited films are more inorganic as the oxygen flow rate increases. The UV–vis spectra, detected in the range 300–800 nm, demonstrated improved transparency in the visible region and increased absorption in UV region of the spectrum. The improved hardness of the atmospheric pressure plasma deposited PC substrates was measured using a pencil hardness testing method and this was related to the chemical composition of the plasma deposited organosilicon thin films. The plasma jet allowed deposition of the coating without a chamber. - Highlights: ► Organosilicon thin films on polycarbonate (PC) by atmospheric pressure plasma jet. ► Properties of SiOx films vary with the injected oxygen flow rate in the plasma jet. ► Improved hardness of atmospheric pressure plasma deposited SiOx films achieved. ► Double-pipe atmospheric pressure plasma jet suitable for chamberless deposition

  17. Estimating global natural wetland methane emissions using process modelling: spatio-temporal patterns and contributions to atmospheric methane fluctuations

    Science.gov (United States)

    Zhu, Qiuan; Peng, Changhui; Chen, Huai; Fang, Xiuqin; Liu, Jinxun; Jiang, Hong; Yang, Yanzheng; Yang, Gang

    2015-01-01

    Aim The fluctuations of atmospheric methane (CH4) that have occurred in recent decades are not fully understood, particularly with regard to the contribution from wetlands. The application of spatially explicit parameters has been suggested as an effective method for reducing uncertainties in bottom-up approaches to wetland CH4 emissions, but has not been included in recent studies. Our goal was to estimate spatio-temporal patterns of global wetland CH4 emissions using a process model and then to identify the contribution of wetland emissions to atmospheric CH4fluctuations. Location Global. Methods A process-based model integrated with full descriptions of methanogenesis (TRIPLEX-GHG) was used to simulate global wetland CH4emissions. Results Global annual wetland CH4 emissions ranged from 209 to 245 Tg CH4 year−1 between 1901 and 2012, with peaks occurring in 1991 and 2012. There is a decreasing trend between 1990 and 2010 with a rate of approximately 0.48 Tg CH4 year−1, which was largely caused by emissions from tropical wetlands showing a decreasing trend of 0.44 Tg CH4 year−1 since the 1970s. Emissions from tropical, temperate and high-latitude wetlands comprised 59, 26 and 15% of global emissions, respectively. Main conclusion Global wetland CH4 emissions, the interannual variability of which was primary controlled by tropical wetlands, partially drive the atmosphericCH4 burden. The stable to decreasing trend in wetland CH4 emissions, a result of a balance of emissions from tropical and extratropical wetlands, was a particular factor in slowing the atmospheric CH4 growth rate during the 1990s. The rapid decrease in tropical wetland CH4emissions that began in 2000 was supposed to offset the increase in anthropogenic emissions and resulted in a relatively stable level of atmospheric CH4 from 2000 to 2006. Increasing wetland CH4 emissions, particularly after 2010, should be an important contributor to the growth in

  18. Atmospheric pressure plasma treatment of flat aluminum surface

    International Nuclear Information System (INIS)

    Highlights: • DCSBD plasma is applicable for activation and cleaning of flat aluminum surfaces. • Decrease in the value of the contact angle after 1 s plasma treatment was 93%. • EDX measurements confirmed removal of oil contamination by 50% decreasing of carbon. • XPS analyze shown decrease of carbon content and increase of aluminum hydroxide and oxyhydroxide. - Abstract: The atmospheric pressure ambient air and oxygen plasma treatment of flat aluminum sheets using the so-called Diffuse Coplanar Surface Barrier Discharge (DCSBD) were investigated. The main objective of this study is to show the possibility of using DCSBD plasma source to activate and clean aluminum surface. Surface free energy measurements, X-ray photoelectron spectroscopy (XPS), Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy (SEM/EDX) and Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) were used for the characterization of the aluminum surface chemistry and changes induced by plasma treatment. Short plasma exposure times (several seconds) led to a significant increase in the surface free energy due to changes of its polar components. Various ageing effects, depending on the storage conditions were observed and discussed. Effects of air and oxygen plasmas on the removal of varying degrees of artificial hydrocarbon contamination of aluminum surfaces were investigated by the means of EDX, ATR-FTIR and XPS methods. A significant decrease in the carbon surface content after the plasma treatment indicates a strong plasma cleaning effect, which together with high energy efficiency of the DCSBD plasma source points to potential benefits of DCSBD application in processing of the flat aluminum surfaces

  19. Collaborative Research. Atmospheric Pressure Microplasma Chemistry-Photon Synergies

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sung-Jin [Univ. of Illinois, Urbana, IL (United States); Eden, James Gary [Univ. of Illinois, Urbana, IL (United States)

    2015-12-01

    Combining the effects of low temperature, atmospheric pressure microplasmas and microplasma photon sources offers the promise of greatly expanding the range of applications for each of them. The plasma sources create active chemical species and these can be activated further by the addition of photons and the associated photochemistry. There are many ways to combine the effects of plasma chemistry and photochemistry, especially if there are multiple phases present. This project combined the construction of appropriate test experimental systems, various spectroscopic diagnostics and mathematical modeling. Through a continuous discussion and co-design process with the UC-Berkeley Team, we have successfully completed the fabrication and testing of all components for a microplasma array-assisted system designed for photon-activated plasma chemistry research. Microcavity plasma lamps capable of generating more than 20 mW/cm2 at 172 nm (Xe dimer) were fabricated with a custom form factor to mate to the plasma chemistry setup, and a lamp was current being installed by the Berkeley team so as to investigate plasma chemistry-photon synergies at a higher photon energy (~7.2 eV) as compared to the UVA treatment that is afforded by UV LEDs operating at 365 nm. In particular, motivated by the promising results from the Berkeley team with UVA treatment, we also produced the first generation of lamps that can generate photons in the 300-370 nm wavelength range. Another set of experiments, conducted under the auspices of this grant, involved the use of plasma microjet arrays. The combination of the photons and excited radicals produced by the plasma column resulted in broad area deactivation of bacteria.

  20. Atmospheric pressure dielectric barrier discharges interacting with liquid covered tissue

    International Nuclear Information System (INIS)

    The interaction of plasmas with liquids is of increasing importance in biomedical applications. Tissues treated by atmospheric pressure dielectric barrier discharges (DBDs) in plasma medicine are often covered by a thin layer of liquid, typically a blood serum like water with dissolved gases and proteins up to hundreds of micrometres thick. The liquid processes the plasma-produced radicals and ions prior to their reaching the tissue. In this paper, we report on a computational investigation of the interaction of DBDs in humid air with a thin water layer covering tissue. The water layer, 50–400 µm thick, contains dissolved O2aq (aq means an aqueous species) and alkane-like hydrocarbons (RHaq). In the model, the DBDs are operated with multiple pulses at 100 Hz followed by a 1 s afterglow. Gas phase reactive oxygen and nitrogen species (RONS) intersect the water-vapour saturated air above the liquid and then solvate when reaching the water. The photolysis of water by plasma-produced UV/VUV plays a significant role in the production of radicals. Without RHaq, O2aq−, ONOOaq−, NO3aq− and hydronium (H3Oaq+) dominate the water ions with H3Oaq+ determining the pH. The dominant RONS in the liquid are O3aq, H2O2aq, and HNOxaq. Dissolved O2aq assists the production of HNO3aq and HOONOaq during the afterglow. With RHaq, reactive oxygen species are largely consumed, leaving an R·aq (alkyl radical) to reach the tissue. These results are sensitive to the thickness of the water layer. (paper)

  1. Helium atmospheric pressure plasma jets touching dielectric and metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Norberg, Seth A., E-mail: norbergs@umich.edu; Johnsen, Eric, E-mail: ejohnsen@umich.edu [Department of Mechanical Engineering, University of Michigan, 2350 Hayward Street, Ann Arbor, Michigan 48109-2125 (United States); Kushner, Mark J., E-mail: mjkush@umich.edu [Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Avenue, Ann Arbor, Michigan 48109-2122 (United States)

    2015-07-07

    Atmospheric pressure plasma jets (APPJs) are being investigated in the context plasma medicine and biotechnology applications, and surface functionalization. The composition of the surface being treated ranges from plastics, liquids, and biological tissue, to metals. The dielectric constant of these materials ranges from as low as 1.5 for plastics to near 80 for liquids, and essentially infinite for metals. The electrical properties of the surface are not independent variables as the permittivity of the material being treated has an effect on the dynamics of the incident APPJ. In this paper, results are discussed from a computational investigation of the interaction of an APPJ incident onto materials of varying permittivity, and their impact on the discharge dynamics of the plasma jet. The computer model used in this investigation solves Poisson's equation, transport equations for charged and neutral species, the electron energy equation, and the Navier-Stokes equations for the neutral gas flow. The APPJ is sustained in He/O{sub 2} = 99.8/0.2 flowing into humid air, and is directed onto dielectric surfaces in contact with ground with dielectric constants ranging from 2 to 80, and a grounded metal surface. Low values of relative permittivity encourage propagation of the electric field into the treated material and formation and propagation of a surface ionization wave. High values of relative permittivity promote the restrike of the ionization wave and the formation of a conduction channel between the plasma discharge and the treated surface. The distribution of space charge surrounding the APPJ is discussed.

  2. Novel applications of atmospheric pressure plasma on textile materials

    Science.gov (United States)

    Cornelius, Carrie Elizabeth

    Various applications of atmospheric pressure plasma are investigated in conjunction with polymeric materials including paper, polypropylene non-woven fabric, and cotton. The effect of plasma on bulk and surface properties is examined by treating both cellulosic pulp and prefabricated paper with various plasma-gas compositions. After treatment, pulp is processed into paper and the properties are compared. The method of pulp preparation is found to be more significant than the plasma, but differences in density, strength, and surface roughness are apparent for the pulp vs. paper plasma treatments. The plasma is also used to remove sizes of PVA and starch from poly/cotton and cotton fabric respectively. In both cases plasma successfully removes a significant amount of size, but complete size removal is not achieved. Subsequent washes (PVA) or scouring (cotton) to remove the size are less successful than a control, suggesting the plasma is crosslinking the size that is not etched away. However, at short durations in cold water using an oxygen plasma, slightly more PVA is removed than with a control. For the starch sized samples, plasma and scouring are never as successful at removing starch as a conventional enzyme, but plasma improves dyeability without need for scouring. Plasma is also used to graft chemicals to the surface of polypropylene and cotton fabric. HTCC, an antimicrobial is grafted to polypropylene with successful grafting indicated by x-ray photoemission spectroscopy (XPS), dye tests, and Fourier transform infrared spectroscopy (FTIR). Antimicrobial activity of the grafted samples is also characterized. 3ATAC, a vinyl monomer is also grafted to polypropylene and to cotton. Additives including Mohr's salt, potassium persulfate, and diacrylate are assessed to increase yield. Successful grafting of 3ATAC is confirmed by XPS and dye testing. A combination of all three additives is identified as optimum for maximizing graft yield.

  3. Tailoring non-equilibrium atmospheric pressure plasmas for healthcare technologies

    Science.gov (United States)

    Gans, Timo

    2012-10-01

    Non-equilibrium plasmas operated at ambient atmospheric pressure are very efficient sources for energy transport through reactive neutral particles (radicals and metastables), charged particles (ions and electrons), UV radiation, and electro-magnetic fields. This includes the unique opportunity to deliver short-lived highly reactive species such as atomic oxygen and atomic nitrogen. Reactive oxygen and nitrogen species can initiate a wide range of reactions in biochemical systems, both therapeutic and toxic. The toxicological implications are not clear, e.g. potential risks through DNA damage. It is anticipated that interactions with biological systems will be governed through synergies between two or more species. Suitable optimized plasma sources are improbable through empirical investigations. Quantifying the power dissipation and energy transport mechanisms through the different interfaces from the plasma regime to ambient air, towards the liquid interface and associated impact on the biological system through a new regime of liquid chemistry initiated by the synergy of delivering multiple energy carrying species, is crucial. The major challenge to overcome the obstacles of quantifying energy transport and controlling power dissipation has been the severe lack of suitable plasma sources and diagnostic techniques. Diagnostics and simulations of this plasma regime are very challenging; the highly pronounced collision dominated plasma dynamics at very small dimensions requires extraordinary high resolution - simultaneously in space (microns) and time (picoseconds). Numerical simulations are equally challenging due to the inherent multi-scale character with very rapid electron collisions on the one extreme and the transport of chemically stable species characterizing completely different domains. This presentation will discuss our recent progress actively combining both advance optical diagnostics and multi-scale computer simulations.

  4. Common 0.1 bar Tropopause in Thick Atmospheres Set by Pressure-Dependent Infrared Transparency

    CERN Document Server

    Robinson, Tyler D

    2014-01-01

    A minimum atmospheric temperature, or tropopause, occurs at a pressure of around 0.1 bar in the atmospheres of Earth, Titan, Jupiter, Saturn, Uranus and Neptune, despite great differences in atmospheric composition, gravity, internal heat and sunlight. In all these bodies, the tropopause separates a stratosphere with a temperature profile that is controlled by the absorption of shortwave solar radiation, from a region below characterised by convection, weather, and clouds. However, it is not obvious why the tropopause occurs at the specific pressure near 0.1 bar. Here we use a physically-based model to demonstrate that, at atmospheric pressures lower than 0.1 bar, transparency to thermal radiation allows shortwave heating to dominate, creating a stratosphere. At higher pressures, atmospheres become opaque to thermal radiation, causing temperatures to increase with depth and convection to ensue. A common dependence of infrared opacity on pressure, arising from the shared physics of molecular absorption, sets t...

  5. Comparison of Regression Methods to Compute Atmospheric Pressure and Earth Tidal Coefficients in Water Level Associated with Wenchuan Earthquake of 12 May 2008

    Science.gov (United States)

    He, Anhua; Singh, Ramesh P.; Sun, Zhaohua; Ye, Qing; Zhao, Gang

    2016-07-01

    The earth tide, atmospheric pressure, precipitation and earthquake fluctuations, especially earthquake greatly impacts water well levels, thus anomalous co-seismic changes in ground water levels have been observed. In this paper, we have used four different models, simple linear regression (SLR), multiple linear regression (MLR), principal component analysis (PCA) and partial least squares (PLS) to compute the atmospheric pressure and earth tidal effects on water level. Furthermore, we have used the Akaike information criterion (AIC) to study the performance of various models. Based on the lowest AIC and sum of squares for error values, the best estimate of the effects of atmospheric pressure and earth tide on water level is found using the MLR model. However, MLR model does not provide multicollinearity between inputs, as a result the atmospheric pressure and earth tidal response coefficients fail to reflect the mechanisms associated with the groundwater level fluctuations. On the premise of solving serious multicollinearity of inputs, PLS model shows the minimum AIC value. The atmospheric pressure and earth tidal response coefficients show close response with the observation using PLS model. The atmospheric pressure and the earth tidal response coefficients are found to be sensitive to the stress-strain state using the observed data for the period 1 April-8 June 2008 of Chuan 03# well. The transient enhancement of porosity of rock mass around Chuan 03# well associated with the Wenchuan earthquake (Mw = 7.9 of 12 May 2008) that has taken its original pre-seismic level after 13 days indicates that the co-seismic sharp rise of water well could be induced by static stress change, rather than development of new fractures.

  6. Altered phase interactions between spontaneous blood pressure and flow fluctuations in type 2 diabetes mellitus: Nonlinear assessment of cerebral autoregulation

    Science.gov (United States)

    Hu, Kun; Peng, C. K.; Huang, Norden E.; Wu, Zhaohua; Lipsitz, Lewis A.; Cavallerano, Jerry; Novak, Vera

    2008-04-01

    Cerebral autoregulation is an important mechanism that involves dilatation and constriction in arterioles to maintain relatively stable cerebral blood flow in response to changes of systemic blood pressure. Traditional assessments of autoregulation focus on the changes of cerebral blood flow velocity in response to large blood pressure fluctuations induced by interventions. This approach is not feasible for patients with impaired autoregulation or cardiovascular regulation. Here we propose a newly developed technique-the multimodal pressure-flow (MMPF) analysis, which assesses autoregulation by quantifying nonlinear phase interactions between spontaneous oscillations in blood pressure and flow velocity during resting conditions. We show that cerebral autoregulation in healthy subjects can be characterized by specific phase shifts between spontaneous blood pressure and flow velocity oscillations, and the phase shifts are significantly reduced in diabetic subjects. Smaller phase shifts between oscillations in the two variables indicate more passive dependence of blood flow velocity on blood pressure, thus suggesting impaired cerebral autoregulation. Moreover, the reduction of the phase shifts in diabetes is observed not only in previously-recognized effective region of cerebral autoregulation (type 2 diabetes mellitus alters cerebral blood flow regulation over a wide frequency range and that this alteration can be reliably assessed from spontaneous oscillations in blood pressure and blood flow velocity during resting conditions. We also show that the MMPF method has better performance than traditional approaches based on Fourier transform, and is more suitable for the quantification of nonlinear phase interactions between nonstationary biological signals such as blood pressure and blood flow.

  7. Atmospheric radiocarbon calibration to 45,000 yr BP : Late glacial fluctuations and cosmogenic isotope production

    NARCIS (Netherlands)

    Kitagawa, H; van der Plicht, J

    1998-01-01

    More than 250 carbon-14 accelerator mass spectrometry dates of terrestrial macrofossils from annually laminated sediments from Lake Suigetsu (Japan) provide a first atmospheric calibration for almost the total range of the radiocarbon method (45,000 years before the present), The results confirm the

  8. Fast PSP measurements of wall-pressure fluctuation in low-speed flows: improvements using proper orthogonal decomposition

    Science.gov (United States)

    Peng, Di; Wang, Shaofei; Liu, Yingzheng

    2016-04-01

    Fast pressure-sensitive paint (PSP) is very useful in flow diagnostics due to its fast response and high spatial resolution, but its applications in low-speed flows are usually challenging due to limitations of paint's pressure sensitivity and the capability of high-speed imagers. The poor signal-to-noise ratio in low-speed cases makes it very difficult to extract useful information from the PSP data. In this study, unsteady PSP measurements were made on a flat plate behind a cylinder in a low-speed wind tunnel (flow speed from 10 to 17 m/s). Pressure fluctuations (Δ P) on the plate caused by vortex-plate interaction were recorded continuously by fast PSP (using a high-speed camera) and a microphone array. Power spectrum of pressure fluctuations and phase-averaged Δ P obtained from PSP and microphone were compared, showing good agreement in general. Proper orthogonal decomposition (POD) was used to reduce noise in PSP data and extract the dominant pressure features. The PSP results reconstructed from selected POD modes were then compared to the pressure data obtained simultaneously with microphone sensors. Based on the comparison of both instantaneous Δ P and root-mean-square of Δ P, it was confirmed that POD analysis could effectively remove noise while preserving the instantaneous pressure information with good fidelity, especially for flows with strong periodicity. This technique extends the application range of fast PSP and can be a powerful tool for fundamental fluid mechanics research at low speed.

  9. Multi-scale and multi-fractal analysis of pressure fluctuation in slurry bubble column bed reactor

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The Daubechies second order wavelet was applied to decompose pressure fluctuation signals with the gas flux varying from 0.18 to 0.90 m3/h and the solid mass fraction from 0 to 20% and scales 1-9 detail signals and the 9th scale approximation signals. The pressure signals were studied by multi-scale and R/S analysis method. Hurst analysis method was applied to analyze multi-fractal characteristics of different scale signals. The results show that the characteristics of mono-fractal under scale 1 and scale 2, and bi-fractal under scale 3-9 are effective in deducing the hydrodynamics in slurry bubbling flow system. The measured pressure signals are decomposed to micro-scale signals, meso-scale signals and macro-scale signals. Micro-scale and macro-scale signals are of mono-fractal characteristics, and meso-scale signals are of bi-fractal characteristics. By analyzing energy distribution of different scale signals, it is shown that pressure fluctuations mainly reflects meso-scale interaction between the particles and the bubble.

  10. Laser induced chemical vapour deposition of TiN coatings at atmospheric pressure

    OpenAIRE

    Croonen, Y.; Verspui, G.

    1993-01-01

    Laser induced Chemical Vapour Deposition of a wide variety of materials has been studied extensively at reduced pressures. However, for this technique to be economically and industrially applicable, processes at atmospheric pressure are preferred. A model study was made on the substrate-coating system molybdenum-titaniumnitride focussing on the feasibility to deposit TiN films locally at atmospheric pressure. The results of this study turned out to be very promising. A Nd-YAG laser beam ([MAT...

  11. Pressure Fluctuation in the Submerged Circulative Impinging Stream Reactor%浸没循环撞击流反应器内的压力波动

    Institute of Scientific and Technical Information of China (English)

    孙怀宇; 伍沅; 徐成海

    2006-01-01

    Pressure fluctuation in the submerged circulative impinging stream reactor (SCISR) is studied by measuring the dynamic pressure with micro pressure sensors of high accuracy, with water as the process material. Experimental results show that the maximum amplitude of fluctuation can be up to about 1.6kPa. On the power spectra the fluctuation is relatively concentrated in the range of <1000Hz, with some weak peeks in acoustic wave range.The space profile of intensive fluctuation region in the reactor is determined. The region is found to take the form of a couple truncated cones of empty core, with coincided bottoms, and is symmetrical with respect to the impinging plane and approximately symmetrical about the axis, essentially independent of u0. The integral intensity of fluctuation increases as the impinging velocity, u0 increasing.

  12. Quantum polarization fluctuations of partially coherent dark hollow beams in non-Kolmogorov turbulence atmosphere

    Science.gov (United States)

    Yan, Xiang; Zhang, Peng-Fei; Zhang, Jing-Hui; Qiao, Chun-Hong; Fan, Cheng-Yu

    2016-08-01

    Non-classical polarization properties of dark hollow beams propagating through non-Kolmogorov turbulence are studied. The analytic equation for the polarization degree of the quantization partially coherent dark hollow beams is obtained. It is found that the polarization fluctuations of the quantization partially coherent dark hollow beams are dependent on the turbulence factors and beam parameters with the detection photon numbers. Furthermore, an investigation of the changes in the on-axis propagation point and off-axis propagation point shows that the polarization degree of the quantization partially coherent dark hollow beams presents oscillation for a short propagation distance and gradually returns to zero for a sufficiently long distance. Project supported by the Major Research Plan of the National Natural Science Foundation of China (Grant No. 61405205).

  13. Gas chromatography coupled to atmospheric pressure ionization mass spectrometry (GC-API-MS): review.

    Science.gov (United States)

    Li, Du-Xin; Gan, Lin; Bronja, Amela; Schmitz, Oliver J

    2015-09-01

    Although the coupling of GC/MS with atmospheric pressure ionization (API) has been reported in 1970s, the interest in coupling GC with atmospheric pressure ion source was expanded in the last decade. The demand of a "soft" ion source for preserving highly diagnostic molecular ion is desirable, as compared to the "hard" ionization technique such as electron ionization (EI) in traditional GC/MS, which fragments the molecule in an extensive way. These API sources include atmospheric pressure chemical ionization (APCI), atmospheric pressure photoionization (APPI), atmospheric pressure laser ionization (APLI), electrospray ionization (ESI) and low temperature plasma (LTP). This review discusses the advantages and drawbacks of this analytical platform. After an introduction in atmospheric pressure ionization the review gives an overview about the history and explains the mechanisms of various atmospheric pressure ionization techniques used in combination with GC such as APCI, APPI, APLI, ESI and LTP. Also new developments made in ion source geometry, ion source miniaturization and multipurpose ion source constructions are discussed and a comparison between GC-FID, GC-EI-MS and GC-API-MS shows the advantages and drawbacks of these techniques. The review ends with an overview of applications realized with GC-API-MS.

  14. Investigation of Wall Pressure Fluctuations in a Turbulent Boundary Layer by Large Eddy Simulation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Large eddy simulation (LES) was used to investigate the space-time field of the low Mach number, fully developed turbulent boundary layer on a smooth, rigid flat plate. The wall-pressure field simulated by LES was analyzed to obtain the pressure statistics , including the wall-pressure root-mean square, skewness and flatness factors, which show the wall pressure distribution was not Gaussian. The profile of the auto-power spectral density and the contour of the streamwise wavenumber-frequency spectral density of wall-pressure were plotted. The "convection ridge" can be observed clearly and the convection velocity can be calculated from the location of the convection peak.

  15. Springtime surface ozone fluctuations at high Arctic latitudes and their possible relationship to atmospheric bromine

    Science.gov (United States)

    Oltmans, Samuel J.; Sheridan, Patrick J.; Schnell, Russell C.; Winchester, John W.

    1988-01-01

    At high Arctic stations such as Barrow, Alaska, springtime near-surface ozone amounts fluctuate between the highest and lowest values seen during the course of the year. Episodes when the surface ozone concentration is essentially zero last up to several days during this time of year. In the Arctic Gas and Aerosol Sampling Program (AGASP-I and AGASP-II) in 1983 and 1986, it was found that ozone concentrations often showed a very steep gradient in altitude with very low values near the surface. The cold temperatures, and snow-covered ground make it unlikely that the surface itself would rapidly destroy significant amounts of ozone. The AGASP aircraft measurements that found low ozone concentrations in the lowest layers of the troposphere also found that filterable excess bromine (the amount of bromine in excess of the sea salt component) in samples collected wholly or partially beneath the temperature inversion had higher bromine concentrations than other tropospheric samples. Of the four lowest ozone minimum concentrations, three of them were associated with the highest bromine enrichments. Surface measurements of excess filterable bromine at Barrow show a strong seasonal dependence with values rising dramatically early in March, then declining in May. The concentration of organic bromine gases such as bromoform rise sharply during the winter and then begin to decline after March with winter and early spring values at least three times greater than the summer minimum.

  16. Simulation of rarefied gas flows in atmospheric pressure interfaces for mass spectrometry systems.

    Science.gov (United States)

    Garimella, Sandilya; Zhou, Xiaoyu; Ouyang, Zheng

    2013-12-01

    The understanding of the gas dynamics of the atmospheric pressure interface is very important for the development of mass spectrometry systems with high sensitivity. While the gas flows at high pressure (>1 Torr) and low pressure (pressure stage (1 to 10(-3) Torr) remains challenging. In this study, we used the direct simulation Monte Carlo (DMSC) method to develop the gas dynamic simulations for the continuous and discontinuous atmospheric pressure interfaces (API), with different focuses on the ion transfer by gas flows through a skimmer or directly from the atmospheric pressure to a vacuum stage, respectively. The impacts by the skimmer location in the continuous API and the temporal evolvement of the gas flow with a discontinuous API were characterized, which provide a solid base for the instrument design and performance improvement.

  17. The effect of atmospheric temperature and pressure on the occurrence of acute myocardial infarction in Kaunas.

    Science.gov (United States)

    Radišauskas, Ričardas; Vaičiulis, Vidmantas; Ustinavičienė, Rūta; Bernotienė, Gailutė

    2013-01-01

    OBJECTIVE. The aim of the study was to evaluate the impact of meteorological variables (atmospheric temperature and pressure) on the daily occurrence of acute myocardial infarction (AMI). MATERIAL AND METHODS. The study used the daily values of atmospheric temperature and pressure in 2000-2007. The meteorological data were obtained from the Lithuanian Hydrometeorological Service for Kaunas. The relative risks of event occurrence were computed for 5°C atmospheric temperature and for 10-hPa atmospheric pressure variations by means of the Poisson regression model. RESULTS. The occurrence of AMI and atmospheric temperature showed an inverse linear relationship, while the occurrence of AMI and atmospheric pressure, a positive linear relationship. Among the youngest subjects (25-44 years old), no relationships were detected. Contrary, among the subjects aged 45-64 years and those aged 65 years and older, the occurrence of AMI significantly decreased with higher temperature (P=0.001 and P=0.002, respectively). A decrease in atmospheric temperature by 10ºC reduced the risk of AMI by 8.7% in the age groups of 45-64 and 65 years and older and by 19% in the age group of 25 years and older. Among the first AMI cases, the risk increased by 7.5% in the age group of 45-64-year olds and by 6.4% in the age group of 25-64-year olds. The relationship between atmospheric temperature and pressure, and AMI occurrence was found to be linear but inverse. An increase in atmospheric pressure by 10 hPa resulted in an increase in risk by 4% among the subjects aged 65 years and more and by 3% among the subjects aged 25 years and more. CONCLUSIONS. Atmospheric temperature and pressure variations had the greatest effect on middle-aged and aging subjects (starting from 45 years). At younger age, the effect of such factors on the AMI risk was considerably lower.

  18. Atmospheric Pressure Plasma-Electrospin Hybrid Process for Protective Applications

    Science.gov (United States)

    Vitchuli Gangadharan, Narendiran

    2011-12-01

    Chemical and biological (C-B) warfare agents like sarin, sulfur mustard, anthrax are usually dispersed into atmosphere in the form of micro aerosols. They are considered to be dangerous weapon of mass destruction next to nuclear weapons. The airtight protective clothing materials currently available are able to stop the diffusion of threat agents but not good enough to detoxify them, which endangers the wearers. Extensive research efforts are being made to prepare advanced protective clothing materials that not only prevent the diffusion of C-B agents, but also detoxify them into harmless products thus ensuring the safety and comfort of the wearer. Electrospun nanofiber mats are considered to have effective filtration characteristics to stop the diffusion of submicron level particulates without sacrificing air permeability characteristics and could be used in protective application as barrier material. In addition, functional nanofibers could be potentially developed to detoxify the C-B warfare threats into harmless products. In this research, electrospun nanofibers were deposited on fabric surface to improve barrier efficiency without sacrificing comfort-related properties of the fabrics. Multi-functional nanofibers were fabricated through an electrospinning-electrospraying hybrid process and their ability to detoxify simulants of C-B agents was evaluated. Nanofibers were also deposited onto plasma-pretreated woven fabric substrate through a newly developed plasma-electrospinning hybrid process, to improve the adhesive properties of nanofibers on the fabric surface. The nanofiber adhesion and durability properties were evaluated by peel test, flex and abrasion resistance tests. In this research work, following tasks have been carried out: i) Controlled deposition of nanofiber mat onto woven fabric substrate Electrospun Nylon 6 fiber mats were deposited onto woven 50/50 Nylon/Cotton fabric with the motive of making them into protective material against submicron

  19. Super-Atmospheric Pressure Ion Sources: Application and Coupling to API Mass Spectrometer.

    Science.gov (United States)

    Chen, Lee Chuin; Rahman, Md Matiur; Hiraoka, Kenzo

    2014-01-01

    Pressurizing the ionization source to gas pressure greater than atmospheric pressure is a new tactic aimed at further improving the performance of atmospheric pressure ionization (API) sources. In principle, all API sources, such as ESI, APCI and AP-MALDI, can be operated at pressure higher than 1 atm if suitable vacuum interface is available. The gas pressure in the ion source can have different role for different ionization. For example, in the case of ESI, stable electrospray could be sustained for high surface tension liquid (e.g., pure water) under super-atmospheric pressure, owing to the absence of electric discharge. Even for nanoESI, which is known to work well with aqueous solution, its stability and sensitivity were found to be enhanced, particularly in the negative mode when the ion source was pressurized. For the gas phase ionization like APCI, measurement of gaseous compound also showed an increase in ion intensity with the ion source pressure until an optimum pressure at around 4-5 atm. The enhancement was due to the increased collision frequency among reactant ion and analyte that promoted the ion/molecule reaction and a higher intake rate of gas to the mass spectrometer. Because the design of vacuum interface for API instrument is based on the upstream pressure of 1 atm, some coupling aspects need to be considered when connecting the high pressure ion source to the mass spectrometer. Several coupling strategies are discussed in this paper.

  20. Diagnostics of plasma-biological surface interactions in low pressure and atmospheric pressure plasmas

    Science.gov (United States)

    Ishikawa, Kenji; Hori, Masaru

    2014-08-01

    Mechanisms of plasma-surface interaction are required to understand in order to control the reactions precisely. Recent progress in atmospheric pressure plasma provides to apply as a tool of sterilization of contaminated foodstuffs. To use the plasma with safety and optimization, the real time in situ detection of free radicals - in particular dangling bonds by using the electron-spin-resonance (ESR) technique has been developed because the free radical plays important roles for dominantly biological reactions. First, the kinetic analysis of free radicals on biological specimens such as fungal spores of Penicillium digitatum interacted with atomic oxygen generated plasma electric discharge. We have obtained information that the in situ real time ESR signal from the spores was observed and assignable to semiquinone radical with a g-value of around 2.004 and a line width of approximately 5G. The decay of the signal was correlated with a link to the inactivation of the fungal spore. Second, we have studied to detect chemical modification of edible meat after the irradiation. Using matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF-MS) and ESR, signals give qualification results for chemical changes on edible liver meat. The in situ real-time measurements have proven to be a useful method to elucidate plasma-induced surface reactions on biological specimens.

  1. Preflame zone structure and main features of fuel conversion in atmospheric pressure premixed laminar hydrocarbon flames

    Energy Technology Data Exchange (ETDEWEB)

    Ksandopulo, G.I.

    1995-08-25

    This report describes the structure study of the premixed hydrocarbon-oxidizer Bunsen flames burning at the atmospheric pressure and also the ones with some inhibitors added. Studies were performed on hexane, propane, methane, acetylene, and hexene flames.

  2. Relating landfill gas emissions to atmospheric pressure using numerical modeling and state-space analysis

    DEFF Research Database (Denmark)

    Poulsen, T.G.; Christophersen, Mette; Moldrup, P.;

    2003-01-01

    were applied: (I) State-space analysis was used to identify relations between gas flux and short-term (hourly) variations in atmospheric pressure. (II) A numerical gas transport model was fitted to the data and used to quantify short-term impacts of variations in atmospheric pressure, volumetric soil......-water content, soil gas permeability, soil gas diffusion coefficients, and biological CH4 degradation rate upon landfill gas concentration and fluxes in the soil. Fluxes and concentrations were found to be most sensitive to variations in volumetric soil water content, atmospheric pressure variations and gas...... permeability whereas variations in CH4 oxidation rate and molecular coefficients had less influence. Fluxes appeared to be most sensitive to atmospheric pressure at intermediate distances from the landfill edge. Also overall CH4 fluxes out of the soil over longer periods (years) were largest during periods...

  3. Atmospheric-Pressure Plasma Interaction with Soft Materials as Fundamental Processes in Plasma Medicine.

    Science.gov (United States)

    Takenaka, Kosuke; Miyazaki, Atsushi; Uchida, Giichiro; Setsuhara, Yuichi

    2015-03-01

    Molecular-structure variation of organic materials irradiated with atmospheric pressure He plasma jet have been investigated. Optical emission spectrum in the atmospheric-pressure He plasma jet has been measured. The spectrum shows considerable emissions of He lines, and the emission of O and N radicals attributed to air. Variation in molecular structure of Polyethylene terephthalate (PET) film surface irradiated with the atmospheric-pressure He plasma jet has been observed via X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). These results via XPS and FT-IR indicate that the PET surface irradiated with the atmospheric-pressure He plasma jet was oxidized by chemical and/or physical effect due to irradiation of active species.

  4. Adhesion improvement of fibres by continuous plasma treatment at atmospheric pressure

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Løgstrup Andersen, Tom; Sørensen, Bent F.;

    2013-01-01

    Carbon fibres and ultra-high-molecular-weight polyethylene (UHMWPE) fibres were continuously treated by a dielectric barrier discharge plasma at atmospheric pressure for adhesion improvement with epoxy resins. The plasma treatment improved wettability, increased the oxygen containing polar...

  5. Ion-ion reactions for charge reduction of biopolymer at atmospheric pressure ambient

    Institute of Scientific and Technical Information of China (English)

    Yue Ming Zhou; Jian Hua Ding; Xie Zhang; Huan Wen Chen

    2007-01-01

    Extractive electrospray ionization source (EESI) was adapted for ion-ion reaction, which was demonstrated by using a linear quadrupole ion trap mass spectrometer for the first ion-ion reaction of biopolymers in the atmospheric pressure ambient.

  6. Experimental study on unsteady cloud cavity behaviour and induced pressure fluctuation in a convergent-divergent channel using simultaneous measurement technique

    International Nuclear Information System (INIS)

    To address the unsteady cavity behaviour and induced pressure fluctuation in cloud cavitating flow, cavitation images and pressure fluctuation signals are simultaneously acquired by high speed visualization system and 4 piezo-electric transducers in a convergent-divergent channel. The cavitation images are processed by using a home-developed software to obtain the time evolutions of global cavity area. Frequency analysis is conducted for both global cavity area and pressure signal. Bubble dynamics is introduced to analyze the correlation between pressure fluctuation in the downstream and global cavity behaviour. Two conclusions are achieved: First, in cloud cavitating flow, the time evolution of both the cavity behaviour and pressure fluctuation are quasi-periodic, one quasi-period can be divided into three main stages: growth of attached cavity, shedding of attached cavity, coalescence and collapse of detached cavity. Second, the dominant frequency of global cavity area and pressure fluctuation on 4 transducers are the same, it's 20Hz in this study. Third, it's found that during the stage of growth of attached cavity and growth, collapse of detached cavity, the correlation between global cavity area and induced pressure in the downstream is similar with that of a single bubble; while, such correlation is not clear when several travelling cavities exist at the same time

  7. Measurements of the beam-wave fluctuations over a 142 km atmospheric path

    Science.gov (United States)

    Perlot, N.; Giggenbach, D.; Henniger, H.; Horwath, J.; Knapek, M.; Zettl, K.

    2006-08-01

    An optical link has been established between the Canary Islands La Palma and Tenerife. A 1064-nm transmitting laser was located on La Palma whereas a BPSK communication receiver and measurement instruments were installed in ESA's OGS on Tenerife. Beside the demonstration of a high-data-rate coherent signal transmission, the goal of the experiment was to measure the effects of the atmosphere on the beam propagation in order to estimate its impact on optical links. In particular, wavefront distortions have been investigated by means of a DIMM instrument and scintillation was observed by imaging the pupil of the OGS telescope on a CCD camera. Strong scintillation was observed during all the experiment with scintillation peaks at sunsets and sunrises, and saturation at about noon. Because of the narrowness of the beam (15-μrad divergence), beam wander has been a serious issue. Statistical results are compared with theory. Recommendations regarding the specifications of optical coherent systems in such detrimental conditions are given.

  8. A Minimized Mutual Information retrieval for simultaneous atmospheric pressure and temperature

    OpenAIRE

    Koner, Prabhat K.; Drummond, James R.

    2010-01-01

    The primary focus of the Mars Trace Gas Orbiter (TGO) collaboration between NASA and ESA is the detection of the temporal and spatial variation of the atmospheric trace gases using a solar occultation Fourier transform spectrometer. To retrieve any trace gas mixing ratios from these measurements, the atmospheric pressure and temperature have to be known accurately. Thus, a prototype retrieval model for the determination of pressure and temperature from a broadband high resolution infrared Fou...

  9. Application of fractal characteristic quantities of pressure fluctuation in subcooled boiling regime recognition

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The dynamical behavior of the subcoole d boiling two-phase system ws introduced and discussed. With the introduction of fractal concept, an analysis of the fractal feature of pressure wave signals fiom nonlinear dynamics point of view. was carried out. Meanwhile, the pseudo phase diagrans of typical time series of sound pressure were given. Finally, through dynamic clustering and on the basis of calculating correlation dimension and Hurst exponent of pressure wave time series on different subcooling conditions, the recognition of developing regime of the two-phase system was delivered, which might provide a promising approach of recognition and diagnosis of a boiling system.

  10. Atmospheric-pressure plasma-enhanced chemical vapor deposition of electrochromic organonickel oxide thin films with an atmospheric pressure plasma jet

    International Nuclear Information System (INIS)

    Deposition of electrochromic organonickel oxide (NiOxCy) films onto glass/indium tin oxide (ITO) substrates using atmospheric-pressure plasma-enhanced chemical vapor deposition with an atmospheric pressure plasma jet under various precursor injection angles is investigated. A precursor [nickelocene, Ni(C5H5)2] vapor, carried by argon gas and mixed with oxygen gas, is injected into an air plasma torch for the deposition of NiOxCy films by a short exposure of the substrate, 20 s, in the plasma. Uniform light modulation on glass/ITO/NiOxCy is produced while the moving glass/ITO substrate is exposed to the plasma torch at room temperature (∼ 23 °C) and under atmospheric pressure. Light modulation with up to a 40.9% transmittance variation at a wavelength of 513.9 nm under Li+ intercalation and de-intercalation in a 1 M LiClO4–propylene carbonate electrolyte is achieved. - Highlights: ► Rapid deposition of electrochromic NiOxCy film by atmospheric pressure plasma jet ► Uniform light modulation on NiOxCy film is produced. ► Nano-grains in NiOxCy films offer fast coloration and bleaching

  11. Super-atmospheric pressure ionization mass spectrometry and its application to ultrafast online protein digestion analysis.

    Science.gov (United States)

    Chen, Lee Chuin; Ninomiya, Satoshi; Hiraoka, Kenzo

    2016-06-01

    Ion source pressure plays a significant role in the process of ionization and the subsequent ion transmission inside a mass spectrometer. Pressurizing the ion source to a gas pressure greater than atmospheric pressure is a relatively new approach that aims to further improve the performance of atmospheric pressure ionization sources. For example, under a super-atmospheric pressure environment, a stable electrospray can be sustained for liquid with high surface tension such as pure water, because of the suppression of electric discharge. Even for nano-electrospray ionization (nano-ESI), which is known to work with aqueous solution, its stability and sensitivity can also be enhanced, particularly in the negative mode when the ion source is pressurized. A brief review on the development of super-atmospheric pressure ion sources, including high-pressure electrospray, field desorption and superheated ESI, and the strategies to interface these ion sources to a mass spectrometer will be given. Using a recent ESI prototype with an operating temperature at 220 °C under 27 atm, we also demonstrate that it is possible to achieve an online Asp-specific protein digestion analysis in which the whole processes of digestion, ionization and MS acquisition could be completed on the order of a few seconds. This method is fast, and the reaction can even be monitored on a near-real-time basis. Copyright © 2016 John Wiley & Sons, Ltd.

  12. Super-atmospheric pressure ionization mass spectrometry and its application to ultrafast online protein digestion analysis.

    Science.gov (United States)

    Chen, Lee Chuin; Ninomiya, Satoshi; Hiraoka, Kenzo

    2016-06-01

    Ion source pressure plays a significant role in the process of ionization and the subsequent ion transmission inside a mass spectrometer. Pressurizing the ion source to a gas pressure greater than atmospheric pressure is a relatively new approach that aims to further improve the performance of atmospheric pressure ionization sources. For example, under a super-atmospheric pressure environment, a stable electrospray can be sustained for liquid with high surface tension such as pure water, because of the suppression of electric discharge. Even for nano-electrospray ionization (nano-ESI), which is known to work with aqueous solution, its stability and sensitivity can also be enhanced, particularly in the negative mode when the ion source is pressurized. A brief review on the development of super-atmospheric pressure ion sources, including high-pressure electrospray, field desorption and superheated ESI, and the strategies to interface these ion sources to a mass spectrometer will be given. Using a recent ESI prototype with an operating temperature at 220 °C under 27 atm, we also demonstrate that it is possible to achieve an online Asp-specific protein digestion analysis in which the whole processes of digestion, ionization and MS acquisition could be completed on the order of a few seconds. This method is fast, and the reaction can even be monitored on a near-real-time basis. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27270863

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

    Science.gov (United States)

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

    2002-01-01

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

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

    Science.gov (United States)

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

    2014-07-01

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

  15. Physiological responses to low atmospheric pressure stunning and the implications for welfare

    NARCIS (Netherlands)

    Mckeegan, D.E.F.; Sandercock, D.A.; Gerritzen, M.A.

    2013-01-01

    In low atmospheric pressure stunning (LAPS), poultry are rendered unconscious before slaughter by gradually reducing oxygen tension in the atmosphere to achieve a progressive anoxia. The effects of LAPS are not instantaneous, so there are legitimate welfare concerns around the experience of birds be

  16. Experimental investigation on unsteady pressure fluctuation of rotor tip region in high pressure stage of a vaneless counter-rotating turbine

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    An experimental investigation has been performed to study the unsteady pressure fluctuation of rotor tip region in high pressure stage of a vaneless counter-rotating turbine.The experiment is carried out on a blow-down short duration turbine facility.The investigation indicates that the blow-down short duration turbine facility is capable of substituting continuous turbine facilities in most turbine testing.Through this experimental investigation,a distinct blade-to-blade variation is observed.The results indicate that the combined effects of vane wake,tip leakage flow,complicated wave systems and rotor wake induce the remarkable blade-to-blade variations.The results also show that the unsteady effect is intensified along the flow direction.

  17. Simulation of Electron-Beam Generating Plasma at Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    OUYANG Liang; LI Hong; LI Benben; ZHOU Junqing; YAN Hong; SU Tie; WANG Huihui; LIUWandong

    2007-01-01

    As electron-beam generating plasma is widely applied,the software tool EGS4(Electron-Gamma Shower) was used to simulate the transmission and energy deposition of electron-beam in air.The simulation results indicated that the range of the electron-beam was inversely proportional to the gas pressure in a wide range of gas pressure,and the electron-beam of 200 keV could generate a plasma with a density 1011 cm-3 in air of latm.In addition,the energy distribution of the beam-electron and plasma density profile produced by the beam were achieved.

  18. Modified drug release using atmospheric pressure plasma deposited siloxane coatings

    Science.gov (United States)

    Dowling, D. P.; Maher, S.; Law, V. J.; Ardhaoui, M.; Stallard, C.; Keenan, A.

    2016-09-01

    This pilot study evaluates the potential of atmospheric plasma polymerised coatings to modify the rate of drug release from polymeric substrates. The antibiotic rifampicin was deposited in a prototype multi-layer drug delivery system, consisting of a nebulized layer of active drug between a base layer of TEOS deposited on a plastic substrate (polystyrene) and an overlying layer of plasma polymerised PDMS. The polymerised TEOS and PDMS layers were deposited using a helium atmospheric plasma jet system. Elution of rifampicin was measured using UV-VIS spectroscopy, in addition to a antimicrobial well diffusion assay with an established indicator organism. The multi-layered plasma deposited coatings significantly extended the duration of release of the rifampicin from 24 h for the uncoated polymer to 144 h for the coated polymer.

  19. Watching the wind: seismic data contamination at long-periods due to atmospheric pressure-field-induced tilting

    Science.gov (United States)

    de Angelis, S.; Bodin, P.; Hagel, K.; Fletcher, D.

    2010-12-01

    Long-period noise generated by the elastic response of the Earth to atmospheric pressure fluctuations has long been recognized as a limiting factor for seismic investigations. The quality of seismic data recorded by sensitive, near-surface broadband seismometers can be severely corrupted by this effect. During the recent installation of a new broadband site on the Olympic Peninsula in Washington, the Pacific Northwest Seismic Network recorded and investigated elevated daytime noise levels at periods exceeding 30 seconds. Substantial power spectral density variations of the background noise field, 15-20 dB, were observed in the horizontal component seismograms. The pattern of the long-period noise exhibited striking correlations with local fluctuations of the air temperature and wind speed as measured nearby the seismic station by the National Weather Service Forecast Office, Seattle, Washington, and the National Oceanic and Atmospheric Administration. Several past studies have demonstrated that local wind systems may lead to variations of the atmospheric pressure field that deform the ground and perturb seismograms. The rotational component of this motion is detected by horizontal-component seismometers because at periods longer than the sensor’s low corner frequency the sensor is acting essentially as a tiltmeter. We obtained a transfer function that describes the response of the broadband seismometer to a tilt step change and estimated the amplitude of tilt noise to be on the order of 10-9 - 10-8 radians. Within the seismic pass-band of the sensor, it is not possible to remove the tilt signal from the observed seismograms because the details of the tilting depend on the pressure field variations, the compliance of the near surface to pressure variations, and the design and construction of the seismometer vault itself. At longer periods, using the seismic data to recover tilts of tectonic origin is made challenging because of the needed instrument correction

  20. Atmospheric sugar alcohols: evaporation rates and saturation vapor pressures

    DEFF Research Database (Denmark)

    Bilde, Merete; Zardini, Alessandro Alessio; Hong, Juan;

    are allowed to evaporate in a laminar flow reactor, and changes in particle size as function of evaporation time are determined using a scanning mobility particle sizer system. In this work saturation vapor pressures of sugar alcohols at several temperatures have been inferred from such measurements using...

  1. The Effect of Atmospheric Pressure on Rocket Thrust -- Part I.

    Science.gov (United States)

    Leitner, Alfred

    1982-01-01

    The first of a two-part question asks: Does the total thrust of a rocket depend on the surrounding pressure? The answer to this question is provided, with accompanying diagrams of rockets. The second part of the question (and answer) are provided in v20 n7, p479, Oct 1982 of this journal. (Author/JN)

  2. ATMOSPHERIC-PRESSURE-IONIZATION MASS-SPECTROMETRY .1. INSTRUMENTATION AND IONIZATION TECHNIQUES

    NARCIS (Netherlands)

    BRUINS, AP

    1994-01-01

    Mass spectrometer ion sources are normally located inside a high-vacuum envelope. Such low-pressure ion sources can make use of a range of different ionization methods and are in routine use in analytical mass spectrometers. An ion source operating at atmospheric pressure is better suited, and may b

  3. Vertical thermal structure of the Venus atmosphere from temperature and pressure measurements

    Energy Technology Data Exchange (ETDEWEB)

    Linkin, V.M.; Blamon, Z.; Lipatov, A.P.; Devyatkin, S.I.; Dyachkov, A.V.; Ignatova, S.I.; Kerzhanovich, V.V.; Malyk, K.; Stadny, V.I.; Sanotskiy, Y.V.

    1986-05-01

    Accurate temperature and pressure measurements were made on the Vega-2 lander during its entire descent. The temperature and pressure at the surface were 733 K and 89.3 bar, respectively. A strong temperature inversion was found in the upper troposphere. Several layers with differing static stability were visible in the atmospheric structure.

  4. Decontamination of objects in a sealed container by means of atmospheric pressure plasmas

    DEFF Research Database (Denmark)

    Leipold, Frank; Schultz-Jensen, Nadja; Kusano, Yukihiro;

    2011-01-01

    The decontamination of objects (food) in a sealed container by means of atmospheric pressure plasmas is investigated. The target is Listeria monocytogenes, a bacterium which causes listeriosis and can be found in plants and food. The non-pathogenic species, Listeria innocua, is used....... The ambient atmosphere was air at atmospheric pressure. A plasma is generated inside the bag forming ozone from the oxygen. The maximum ozone concentration in the bag was found to be 140 ppm. A log 6 reduction of L. innocua is obtained after 15 min of exposure time. The temperature of the slides after...

  5. Investigations of the fluctuating pressure field in the suppression pool of the Marviken containment during blowdown

    International Nuclear Information System (INIS)

    From August 1972 until May 1973 blowdown tests were performed at the Marviken reactor plant. The tests were intended to provide information about the behaviour of a reactor safety containment with pressure suppression system in case of a loss-of-coolant accident resulting from a rupture in the primary circuit. Besides of experiments on the behaviour of the containment parallel experiments were conducted relative to the transport of iodine, the behaviour of components, and the tightness of the containment. Within this test program the Gesellschaft fuer Kernforschung measured the local pressure pulsation field in the water pool as well as the mass flows entering the pressure suppression system. The measurements were performed to provide first a general view of the vibration phenomena in the water pool to allow subsequent interpretation by means of physical models and processing by computation. (Auth.)

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

    Science.gov (United States)

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

    1983-01-01

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

  7. Cancer therapy using non-thermal atmospheric pressure plasma with ultra-high electron density

    International Nuclear Information System (INIS)

    Cancer therapy using non-thermal atmospheric pressure plasma is a big challenge in plasma medicine. Reactive species generated from plasma are key factors for treating cancer cells, and thus, non-thermal atmospheric pressure plasma with high electron density has been developed and applied for cancer treatment. Various cancer cell lines have been treated with plasma, and non-thermal atmospheric plasma clearly has anti-tumor effects. Recent innovative studies suggest that plasma can both directly and indirectly affect cells and tissues, and this observation has widened the range of applications. Thus, cancer therapy using non-thermal atmospheric pressure plasma is promising. Animal experiments and understanding the mode of action are essential for clinical application in the future. A new academic field that combines plasma science, the biology of free radicals, and systems biology will be established

  8. Cancer therapy using non-thermal atmospheric pressure plasma with ultra-high electron density

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Hiromasa [Institute of Innovation for Future Society, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Center for Advanced Medicine and Clinical Research, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Mizuno, Masaaki [Center for Advanced Medicine and Clinical Research, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Toyokuni, Shinya [Department of Pathology and Biological Responses, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Maruyama, Shoichi [Department of Nephrology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Kodera, Yasuhiro [Department of Gastroenterological Surgery (Surgery II), Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Terasaki, Hiroko [Department of Ophthalmology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Adachi, Tetsuo [Laboratory of Clinical Pharmaceutics, Gifu Pharmaceutical University, 501-1196 Gifu (Japan); Kato, Masashi [Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Kikkawa, Fumitaka [Department of Obstetrics and Gynecology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Hori, Masaru [Institute of Innovation for Future Society, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2015-12-15

    Cancer therapy using non-thermal atmospheric pressure plasma is a big challenge in plasma medicine. Reactive species generated from plasma are key factors for treating cancer cells, and thus, non-thermal atmospheric pressure plasma with high electron density has been developed and applied for cancer treatment. Various cancer cell lines have been treated with plasma, and non-thermal atmospheric plasma clearly has anti-tumor effects. Recent innovative studies suggest that plasma can both directly and indirectly affect cells and tissues, and this observation has widened the range of applications. Thus, cancer therapy using non-thermal atmospheric pressure plasma is promising. Animal experiments and understanding the mode of action are essential for clinical application in the future. A new academic field that combines plasma science, the biology of free radicals, and systems biology will be established.

  9. Cancer therapy using non-thermal atmospheric pressure plasma with ultra-high electron density

    Science.gov (United States)

    Tanaka, Hiromasa; Mizuno, Masaaki; Toyokuni, Shinya; Maruyama, Shoichi; Kodera, Yasuhiro; Terasaki, Hiroko; Adachi, Tetsuo; Kato, Masashi; Kikkawa, Fumitaka; Hori, Masaru

    2015-12-01

    Cancer therapy using non-thermal atmospheric pressure plasma is a big challenge in plasma medicine. Reactive species generated from plasma are key factors for treating cancer cells, and thus, non-thermal atmospheric pressure plasma with high electron density has been developed and applied for cancer treatment. Various cancer cell lines have been treated with plasma, and non-thermal atmospheric plasma clearly has anti-tumor effects. Recent innovative studies suggest that plasma can both directly and indirectly affect cells and tissues, and this observation has widened the range of applications. Thus, cancer therapy using non-thermal atmospheric pressure plasma is promising. Animal experiments and understanding the mode of action are essential for clinical application in the future. A new academic field that combines plasma science, the biology of free radicals, and systems biology will be established.

  10. Space-time characteristics of wall-pressure and wall shear-stress fluctuations in wall-modeled large eddy simulation

    Science.gov (United States)

    Park, George Ilhwan; Moin, Parviz

    2016-06-01

    We report the space-time characteristics of the wall-pressure fluctuations and wall shear-stress fluctuations from wall-modeled large eddy simulation (WMLES) of a turbulent channel flow at Reτ=2000 . Two standard zonal wall models (equilibrium stress model and nonequilibrium model based on unsteady RANS) are employed, and it is shown that they yield similar results in predicting these quantities. The wall-pressure and wall shear-stress fields from WMLES are analyzed in terms of their r.m.s. fluctuations, spectra, two-point correlations, and convection velocities. It is demonstrated that the resolution requirement for predicting the wall-pressure fluctuations is more stringent than that for predicting the velocity. At least δ /Δ x >20 and δ /Δ z >30 are required to marginally resolve the integral length scales of the pressure-producing eddies near the wall. Otherwise, the pressure field is potentially aliased. Spurious high wave number modes dominate in the streamwise direction, and they contaminate the pressure spectra leading to significant overprediction of the second-order pressure statistics. When these conditions are met, the pressure statistics and spectra at low wave number or low frequency agree well with the DNS and experimental data. On the contrary, the wall shear-stress fluctuations, modeled entirely through the RANS-based wall models, are largely underpredicted and relatively insensitive to the grid resolution. The short-time, small-scale near-wall eddies, which are neither resolved nor modeled adequately in the wall models, seem to be important for accurate prediction of the wall shear-stress fluctuations.

  11. Atmospheric oxygenation caused by a change in volcanic degassing pressure

    OpenAIRE

    Gaillard, Fabrice; Scaillet, Bruno; Arndt, Nicholas T.

    2011-01-01

    International audience; The Precambrian history of our planet is marked by two major events: a pulse of continental crust formation at the end of the Archaean eon and a weak oxygenation of the atmosphere (the Great Oxidation Event) that followed, at 2.45 billion years ago. This oxygenation has been linked to the emergence of oxygenic cyanobacteria1,2 and to changes in the compositions of volcanic gases3,4, but not to the composition of erupting lavas--geochemical constraints indicate that the...

  12. A Microwave Air Plasma Source under Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    LIU Liang; ZHANG Gui-Xin; FENG Jian; WANG Xin-Xin; LUO Cheng-Mu

    2008-01-01

    @@ We develop a new cavity with a mode similar to TE13 to produce microwave plasma,named APMPS Ⅱ,which is able to produce a mass of air plasma with diameter of around 6cm,equipped with about 3kW input power under one atmosphere.The plasma seems to be homogeneous without significant filamentous discharge as observed by common camera device.We present the theory of this cavity,show the distribution of electric field of several planes inside the cavity and give some experimental results.

  13. Germination and growth of lettuce (Lactuca sativa) at low atmospheric pressure

    Science.gov (United States)

    Spanarkel, Robert; Drew, Malcolm C.

    2002-01-01

    The response of lettuce (Lactuca sativa L. cv. Waldmann's Green) to low atmospheric pressure was examined during the initial 5 days of germination and emergence, and also during subsequent growth to vegetative maturity at 30 days. Growth took place inside a 66-l-volume low pressure chamber maintained at 70 kPa, and plant response was compared to that of plants in a second, matching chamber that was at ambient pressure (approximately 101 kPa) as a control. In other experiments, to determine short-term effects of low pressure transients, plants were grown at ambient pressure until maturity and then subjected to alternating periods of 24 h of low and ambient atmospheric pressures. In all treatments the partial pressure of O2 was maintained at 21 kPa (approximately the partial pressure in air at normal pressure), and the partial pressure of CO2 was in the range 66.5-73.5 Pa (about twice that in normal air) in both chambers, with the addition of CO2 during the light phase. With continuous exposure to low pressure, shoot and root growth was at least as rapid as at ambient pressure, with an overall trend towards slightly greater performance at the lower pressure. Dark respiration rates were greater at low pressure. Transient periods at low pressure decreased transpiration and increased dark respiration but only during the period of exposure to low pressure. We conclude that long-term or short-term exposure to subambient pressure (70 kPa) was without detectable detriment to vegetative growth and development.

  14. Silicon-based quantum dots: synthesis, surface and composition tuning with atmospheric pressure plasmas

    International Nuclear Information System (INIS)

    The synthesis of silicon and silicon-based quantum dots (diameter < 5 nm) is discussed. Specifically the synthesis of Si-based quantum dots (QDs) by atmospheric pressure plasmas is reviewed and the most recent developments are also reported. Atmospheric pressure plasmas are then compared with other synthesis methods that include low pressure plasmas, wet chemistry, electrochemical etching and laser-based methods. Finally, progress in the synthesis of alloyed silicon QDs is discussed where the nanoscale Si–Sn and Si–C systems are reported. The report also includes a theoretical analysis that highlights some fundamental differences offered by plasmas at atmospheric pressure and that may provide opportunities for novel materials with advantageous properties. (review article)

  15. Chain elongation of diacylphosphatidylcholine induces fully bilayer interdigitation under atmospheric pressure.

    Science.gov (United States)

    Goto, Masaki; Wilk, Agnieszka; Kazama, Akira; Chodankar, Shirish; Kohlbrecher, Joachim; Matsuki, Hitoshi

    2011-05-01

    The phase transitions of dibehenoylphosphatidylcholine (C22PC) bilayer membrane were observed by differential scanning calorimetry under atmospheric pressure and light-transmittance measurements under high pressure. The constructed temperature-pressure phase diagram suggests that the gel phase at low temperatures is the interdigitated gel phase. To confirm the phase state, we performed small-angle neutron scattering and fluorescence measurements using a polarity-sensitive probe Prodan for the C22PC bilayer membrane under atmospheric pressure. The peaks obtained in both measurements clearly showed the characteristic patterns of the fully interdigitated gel phase. Taking into account of previous studies on the gel phase for long-chain PC bilayers under atmospheric pressure and our studies on the pressure-induced bilayer interdigitaion of diacyl-PCs, it turned out that the interdigitation of diacyl-PC bilayer membranes occurs when the carbon number of acyl chain reaches at least 22. The present study revealed that the interdigitation of PC bilayer membranes occurs not only by weakening the attractive force of polar head groups but also by strengthening the cohesive force of acyl chains. When dominating the force of acyl chains, the interdigitation can be induced even in a diacyl-PC bilayer membrane by only hydration under atmospheric pressure.

  16. Water-Level Responses to Barometric-Pressure Fluctuations in Wells in Semi-Confined Aquifers

    Science.gov (United States)

    Jin, W.; Butler, J. J.

    2009-12-01

    Hydrologists have long recognized that changes in barometric pressure can produce changes in water levels in wells. The relationship between barometric pressure and water level has traditionally been characterized using the barometric efficiency (BE), the ratio of the change in water level to the change in barometric pressure head. Although BE has proven to be an effective means of characterizing the short-term response of a well to a change in barometric pressure, the barometric response function (BRF) is a more effective means to characterize the longer-term response. The BRF, which can be determined through a regression deconvolution procedure developed by Rasmussen and co-workers (Rasmussen and Crawford, 1997; Toll and Rasmussen, 2007), characterizes the water level response over time to a step change in barometric pressure, essentially BE as a function of the time since the imposed load. We have extended earlier work of Rasmussen and Spane (Rasmussen and Crawford, 1997; Spane, 2002) to show that the BRF can be utilized to glean important insights into semi-confined aquifer systems. The form of the BRF indicates the degree of aquifer confinement, while a comparison of BRFs from different wells provides insight into aquitard continuity. Recently, we have developed a new approach for estimating aquitard K by fitting type curves to experimentally determined BRFs. We will demonstrate the power of the BRF using field data from a long-term monitoring site of the Kansas Geological Survey at which a four-day pumping test has previously been performed. The aquitard K estimates obtained from the BRFs are in good agreement at this site with the estimate determined from the pumping test. We will also show how the BRF for a well in a semi-confined aquifer can be used to gain insights into conditions in the overlying unconfined aquifer and vadose zone. Although the BE is considered an invariant parameter of a well, we will show that the BRF of a well in a semi

  17. Investigation of wall temperature fluctuations by visualization tests for steam-water two-phase flow in the pressurizer spray piping

    International Nuclear Information System (INIS)

    In a PWR plant, a steam-water two phase flow may possibly exist in the pressurizer spray pipe under a rated power operating condition since the flow rate of the spray water is not sufficient to fill the horizontal section of the pipe completely. Under such thermally stratified two phase flow conditions, the initiation of high cycle fatigue cracks is suspected to occur due to cyclic thermal stress fluctuations caused by oscillations of the water surface, which cannot be detected by the measurement of temperature on outer surface of the pipe. In order to clarify the flow and thermal conditions in the pressurizer spray pipe and assess their impact on the pipe structure, an experiment was conducted for a steam-water flow at a low flow rate using a mock-up pressurizer spray pipe. By measuring inner wall temperature fluctuations, continuous temperature fluctuations, which were around 0.2 times of the steam water temperature difference in the maximum range, were observed at the inclined section where the water surface contacted the pipe wall. Then, we investigated the causes of the fluctuations by visualization tests. As a result of the experiment, it seemed that wall temperature fluctuations were not caused by waves on the water surface, but were caused by liquid temperature fluctuations a layer below the steam-water interface. The influence of a small amount of non-condensable gas dissolved in the reactor coolant on the wall temperature fluctuations was investigated by injecting air into the experimental loop. The liquid temperature fluctuations in the layer which caused wall temperature fluctuations were attenuated after air was injected. (author)

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

    Science.gov (United States)

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

    2016-01-01

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

  19. Pressure Fluctuation in a Vaned Diffuser Downstream from a Centrifugal Pump Impeller

    OpenAIRE

    Akinori Furukawa; Hisasada Takahara; Takahiro Nakagawa; Yusuke Ono

    2003-01-01

    Periodic flows downstream from a centrifugal pump impeller in vaneless and vaned diffusers were measured by using a single hole yawmeter and a phase-locked sampling method. The flows were also calculated by an inviscid flow analysis using the blade-surface singularity method. The periodic variations in calculated static pressure with the impeller rotating quantitatively agree well with the measured ones. The flow behaviors in the vaned diffuser are discussed, citing measured and calculated re...

  20. The Atmospheric Mutual Coherence Function From the First and Second Rytov Approximations and Its Comparison to That of Strong Fluctuation Theory

    Science.gov (United States)

    Manning, Robert M.

    2011-01-01

    An expression for the mutual coherence function (MCF) of an electromagnetic beam wave propagating through atmospheric turbulence is derived within the confines of the Rytov approximation. It is shown that both the first and second Rytov approximations are required. The Rytov MCF is then compared to that which issues from the parabolic equation method of strong fluctuation theory. The agreement is found to be quite good in the weak fluctuation case. However, an instability is observed for the special case of beam wave intensities. The source of the instabilities is identified to be the characteristic way beam wave amplitudes are treated within the Rytov method.

  1. Effects of initiating anaerobic digestion of layer-hen poultry dung at sub-atmospheric pressure

    Directory of Open Access Journals (Sweden)

    Chima C. Ngumah

    2013-12-01

    Full Text Available This study investigated the effects of initiating anaerobic digestion (AD of dry layer-hen poultry dung at the sub-atmospheric pressure of -30 cmHg on biodegradation, biogasification, and biomethanation. The setup was performed as a batch process at an average ambient temperature of 29±2 0C and a retention time of 15 days. Comparisons were made with two other experiments which were both begun at ambient atmospheric pressure; one was inoculated with digestate from a previous layer-hen dung AD, while the other was not inoculated. The bioreactors initiated at sub-atmospheric pressure, ambient atmospheric pressure without inoculum, and ambient atmospheric pressure with inoculum showed the following for biogas and biomethane yields respectively: 16.8 cm3 g-1 VS and 15.46 cm3 g 1 VS, 25.10 cm3 g-1 VS and 12.85 cm3 g-1 VS, 21.44 cm3 g-1 VS and 14.88 cm3 g 1 VS. In the same order, after AD, the following values were recorded for volatile solids and total viable counts (prokaryotes and fungi in the digestates: 40.33% and 23.22 x 106 cfu mL-1, 43.42% and 22.17 x 106 cfu mL-1, 41.11% and 13.3 x 106 cfu mL-1. The feedstock showed values of 83.93% and 3.98 x 106 cfu mL-1 for volatile solids and total viable count respectively. There was a slight difference in the volatile solids of the digestates of the three bioreactors after AD. The pH recorded for the feedstock slurry before AD was 7.9 at 30oC, while after AD, the digestates from all the three bioreactors showed the same pH of 5.9 at 29 0C. Statistical analysis using ANOVA showed no significant difference in biogas yields of the feedstock for the three bioreactors (A, B, C. ANOVA showed no significant difference for biomethane yields in the bioreactors initiated at sub-atmospheric pressure and for those initiated at ambient atmospheric pressure with inoculums. However, it showed significant difference in the bioreactor initiated at sub-atmospheric pressure and that initiated at ambient atmospheric

  2. Pressure sensing of the atmosphere by solar occultation using broadband CO2 absorption

    Science.gov (United States)

    Park, J. H.; Russell, J. M., III; Drayson, S. R.

    1979-01-01

    A technique for obtaining pressure at the tangent point in an IR solar occulation experiment is described. By measuring IR absorption in bands of atmospheric CO2 (e.g., 2.0, 2.7, or 4.3 microns), mean pressure values for each tangent point layer (vertical thickness 2 km or less) of the atmosphere can be obtained with rms errors of less than 3%. The simultaneous retrieval of pressure and gas concentration in a remote-sensing experiment will increase the accuracy of inverted gas concentrations and minimize the dependence of the experiment on pressure or mass path error resulting from use of climatological pressure data, satellite ephemeris, and instrument pointing accuracy.

  3. Breaking the pumping speed barrier in mass spectrometry: discontinuous atmospheric pressure interface.

    Science.gov (United States)

    Gao, Liang; Cooks, R Graham; Ouyang, Zheng

    2008-06-01

    The performance of mass spectrometers with limited pumping capacity is shown to be improved through use of a discontinuous atmospheric pressure interface (DAPI). A proof-of-concept DAPI interface was designed and characterized using a miniature rectilinear ion trap mass spectrometer. The interface consists of a simple capillary directly connecting the atmospheric pressure ion source to the vacuum mass analyzer region; it has no ion optical elements and no differential pumping stages. Gases carrying ionized analytes were pulsed into the mass analyzer for short periods at high flow rates rather than being continuously introduced at lower flow rates; this procedure maximized ion transfer. The use of DAPI provides a simple solution to the problem of coupling an atmospheric pressure ionization source to a miniature instrument with limited pumping capacity. Data were recorded using various atmospheric pressure ionization sources, including electrospray ionization (ESI), nano-ESI, atmospheric pressure chemical ionization (APCI), and desorption electrospray ionization (DESI) sources. The interface was opened briefly for ion introduction during each scan. With the use of the 18 W pumping system of the Mini 10, limits of detection in the low part-per-billion levels were achieved and unit resolution mass spectra were recorded. PMID:18461971

  4. Plasma Treatment of Industrial Landfill Leachate by Atmospheric Pressure Dielectric Barrier Discharges%Plasma Treatment of Industrial Landfill Leachate by Atmospheric Pressure Dielectric Barrier Discharges

    Institute of Scientific and Technical Information of China (English)

    赵迪; 王达成; 严贵; 马宏; 熊小京; 罗津晶; 张先徽; 刘东平; 杨思泽

    2011-01-01

    An dielectric barrier discharge (DBD) system in atmospheric pressure utilized for the treatment of industrial landfill leachate is reported. The discharge parameters, such as the operating frequency, gas flow rate, and treating duration, were found to affect significantly the removal of ammonia nitrogen (AN) in industrial landfill leachate. An increase in treating duration leads to an obvious increase in the removal efficiency of AN (up to 83%) and the leachate color changed from deep grey-black to transparent. Thus the dielectric barrier discharges in atmospheric pressure could degrade the landfill leachate effectively. Typical waveforms of both applied voltage and discharge current were also presented for analyzing the discharge processes under different discharge parameters. Optical emission spectra measurements indicate that oxidation species generated in oxygen DBD plasma play a crucial role in removing AN, oxidizing organic and inorganic substances and decolorizing the landfill leachate.

  5. Adaptation to fluctuating temperatures in an RNA virus is driven by the most stringent selective pressure.

    Directory of Open Access Journals (Sweden)

    María Arribas

    Full Text Available The frequency of change in the selective pressures is one of the main factors driving evolution. It is generally accepted that constant environments select specialist organisms whereas changing environments favour generalists. The particular outcome achieved in either case also depends on the relative strength of the selective pressures and on the fitness costs of mutations across environments. RNA viruses are characterized by their high genetic diversity, which provides fast adaptation to environmental changes and helps them evade most antiviral treatments. Therefore, the study of the adaptive possibilities of RNA viruses is highly relevant for both basic and applied research. In this study we have evolved an RNA virus, the bacteriophage Qβ, under three different temperatures that either were kept constant or alternated periodically. The populations obtained were analyzed at the phenotypic and the genotypic level to characterize the evolutionary process followed by the virus in each case and the amount of convergent genetic changes attained. Finally, we also investigated the influence of the pre-existent genetic diversity on adaptation to high temperature. The main conclusions that arise from our results are: i under periodically changing temperature conditions, evolution of bacteriophage Qβ is driven by the most stringent selective pressure, ii there is a high degree of evolutionary convergence between replicated populations and also among populations evolved at different temperatures, iii there are mutations specific of a particular condition, and iv adaptation to high temperatures in populations differing in their pre-existent genetic diversity takes place through the selection of a common set of mutations.

  6. Three electrode atmospheric pressure plasma jet in helium flow

    Science.gov (United States)

    Maletic, Dejan; Puac, Nevena; Malovic, Gordana; Petrovic, Zoran Lj.

    2015-09-01

    Plasma jets are widely used in various types of applications and lately more and more in the field of plasma medicine. However, it is not only their applicability that distinguishes them from other atmospheric plasma sources, but also the behavior of the plasma. It was shown that plasma plume is not continuous, but discrete set of plasma packages. Here we present iCCD images and current voltage characteristics of a three electrode plasma jet. Our plasma jet has a simple design with body made of glass tube and two transparent electrodes wrapped around it. The additional third metal tip electrode was positioned at 10 and 25 mm in front of the jet nozzle and connected to the same potential as the powered electrode. Power transmitted to the plasma was from 0.5 W to 4.0 W and the helium flow rate was kept constant at 4 slm. For the 10 mm configuration plasma is ignited on the metal tip in the whole period of the excitation signal and in the positive half cycle plasma ``bullet'' is propagating beyond the metal tip. In contrast to that, for the 25 mm configuration at the tip electrode plasma can be seen only in the minimum and maximum of the excitation signal, and there is no plasma ``bullet'' formation. This research has been supported by the Ministry of Education, Science and Technological Development, Republic of Serbia, under projects ON171037 and III41011.

  7. Characterization of Dust-Plasma Interactions In Non-Thermal Plasmas Under Low Pressure and the Atmospheric Pressure

    Science.gov (United States)

    Bilik, Narula

    This dissertation research focuses on the experimental characterization of dust-plasma interactions at both low and atmospheric pressure. Its goal is to fill the knowledge gaps in (1) the fundamental research of low pressure dusty plasma electrons, which mainly relied on models with few experimental results; and (2) the nanoparticle synthesis process in atmospheric pressure uniform glow plasmas (APGDs), which is largely unexplored in spite of the economical advantage of APGDs in nanotechnology. The low pressure part of the dissertation research involves the development of a complete diagnostic process for an argon-siline capacitively-coupled RF plasma. The central part of the diagnostic process is the Langmuir probe measurement of the electron energy probability function (EEPF) in a dusty plasma, which has never been measured before. This is because the dust particles in the plasma cause severe probe surface contamination and consequently distort the measurement. This problem is solved by adding a solenoid-actuated shield structure to the Langmuir probe, which physically protects the Langmuir probe from the dust particle deposition to ensure reliable EEPF measurements. The dusty plasma EEPFs are characterized by lower electron density and higher electron temperature accompanied by a drop in the low energy electron population. The Langmuir probe measurement is complemented with other characterizations including the capacitive probe measurement, power measurement, and dust particle collection. The complete diagnostic process then gives a set of local plasma parameters as well as the details of the dust-electron interactions reflected in the EEPFs. This set of data serves as input for an analytical model of nanoparticle charging to yield the time evolution of nanoparticle size and charge in the dusty plasma. The atmospheric pressure part of the dissertation focuses on the design and development of an APGD for zinc oxide nanocrystal synthesis. One of the main

  8. Differential equations governing slip-induced pore-pressure fluctuations in a water-saturated granular medium

    Science.gov (United States)

    Iverson, R.M.

    1993-01-01

    Macroscopic frictional slip in water-saturated granular media occurs commonly during landsliding, surface faulting, and intense bedload transport. A mathematical model of dynamic pore-pressure fluctuations that accompany and influence such sliding is derived here by both inductive and deductive methods. The inductive derivation shows how the governing differential equations represent the physics of the steadily sliding array of cylindrical fiberglass rods investigated experimentally by Iverson and LaHusen (1989). The deductive derivation shows how the same equations result from a novel application of Biot's (1956) dynamic mixture theory to macroscopic deformation. The model consists of two linear differential equations and five initial and boundary conditions that govern solid displacements and pore-water pressures. Solid displacements and water pressures are strongly coupled, in part through a boundary condition that ensures mass conservation during irreversible pore deformation that occurs along the bumpy slip surface. Feedback between this deformation and the pore-pressure field may yield complex system responses. The dual derivations of the model help explicate key assumptions. For example, the model requires that the dimensionless parameter B, defined here through normalization of Biot's equations, is much larger than one. This indicates that solid-fluid coupling forces are dominated by viscous rather than inertial effects. A tabulation of physical and kinematic variables for the rod-array experiments of Iverson and LaHusen and for various geologic phenomena shows that the model assumptions commonly are satisfied. A subsequent paper will describe model tests against experimental data. ?? 1993 International Association for Mathematical Geology.

  9. Plasma polymerization of acrylic acid onto polystyrene by cyclonic plasma at atmospheric pressure

    Science.gov (United States)

    Chang, Yi-Jan; Lin, Chin-Ho; Huang, Chun

    2016-01-01

    The cyclonic atmospheric-pressure plasma is developed for chamberless deposition of poly(acrylic acid) film from argon/acrylic acid mixtures. The photoemission plasma species in atmospheric-pressure plasma polymerization was identified by optical emission spectroscopy (OES). The OES diagnosis data and deposition results indicated that in glow discharge, the CH and C2 species resulted from low-energy electron-impact dissociation that creates deposition species, but the strong CO emission lines are related to nondeposition species. The acrylic acid flow rate is seen as the key factor affecting the film growth. The film surface analysis results indicate that a smooth, continuous, and uniform surface of poly(acrylic acid) films can be formed at a relatively low plasma power input. This study reveals the potential of chamberless film growth at atmospheric pressure for large-area deposition of poly(acrylic acid) films.

  10. Optical Emission Spectroscopy of an Atmospheric Pressure Plasma Jet During Tooth Bleaching Gel Treatment.

    Science.gov (United States)

    Šantak, Vedran; Zaplotnik, Rok; Tarle, Zrinka; Milošević, Slobodan

    2015-11-01

    Optical emission spectroscopy was performed during atmospheric pressure plasma needle helium jet treatment of various tooth-bleaching gels. When the gel sample was inserted under the plasma plume, the intensity of all the spectral features increased approximately two times near the plasma needle tip and up to two orders of magnitude near the sample surface. The color change of the hydroxylapatite pastille treated with bleaching gels in conjunction with the atmospheric pressure plasma jet was found to be in correlation with the intensity of OH emission band (309 nm). Using argon as an additive to helium flow (2 L/min), a linear increase (up to four times) of OH intensity and, consequently, whitening (up to 10%) of the pastilles was achieved. An atmospheric pressure plasma jet activates bleaching gel, accelerates OH production, and accelerates tooth bleaching (up to six times faster).

  11. Selective cytotoxicity of indirect nonequilibrium atmospheric pressure plasma against ovarian clear-cell carcinoma.

    Science.gov (United States)

    Utsumi, Fumi; Kajiyama, Hiroaki; Nakamura, Kae; Tanaka, Hiromasa; Hori, Masaru; Kikkawa, Fumitaka

    2014-01-01

    Ovarian clear cell carcinoma (CCC) is a histological type of epithelial ovarian cancer that is less responsive to chemotherapy and associated with a poorer prognosis than serous and endometrioid carcinoma. Non-thermal atmospheric pressure plasma which produces reactive species has recently led to an explosion of research in plasma medicine. Plasma treatment can be applied to cancer treatment to induce apoptosis and tumor growth arrest. Furthermore, recent studies have shown that a medium exposed to plasma also has an anti-proliferative effect against cancer in the absence of direct exposure to plasma. In this study, we confirmed whether this indirect plasma has an anti-tumor effect against CCC, and investigated whether this efficacy is selective for cancer cells. Non-thermal atmospheric pressure plasma induced apoptosis in CCC cells, while human peritoneal mesothelial cells remained viable. Non-thermal atmospheric pressure plasma exhibits selective cytotoxicity against CCC cells which are resistant to chemotherapy.

  12. Polymer Surface Treatment by Atmospheric Pressure Low Temperature Surface Discharge Plasma:Its Characteristics and Comparison with Low Pressure Oxygen Plasma Treatment

    Institute of Scientific and Technical Information of China (English)

    Atsushi KUWABARA; Shin-ichi KURODA; Hitoshi KUBOTA

    2007-01-01

    The polymer treatment with a low-temperature plasma jet generated on the atmospheric pressure surface discharge (SD) plasma is performed.The change of the surface property over time,in comparison with low pressure oxygen (O2) plasma treatment,is examined.As one compares the treatment by atmospheric pressure plasma to that by the low pressure O2 plasma of PS (polystyrene) the treatment effects were almost in complete agreement.However,when the atmospheric pressure plasma was used for PP(polypropylene),it produced remarkable hydrophilic effects.

  13. Phase Synchronization of Pressure-Flow Fluctuations: A measure of cerebral autoregulation dynamics

    CERN Document Server

    Chen, Z; Ivanov, P C; Novák, V; Stanley, H E

    2006-01-01

    We employ a synchronization method to investigate the relationship between the blood flow velocities (BFV) in the middle cerebral arteries (MCA) and beat-to-beat blood pressure (BP) recorded from a finger in healthy and post-stroke subjects during four different physiologic conditions: supine, head-up tilt, hyperventilation and CO$_2$ rebreathing in upright position. To evaluate whether instantaneous BP changes are synchronized with changes in the BFV, we compare dynamical patterns in the instantaneous phases of these signals, obtained from the Hilbert transform, as a function of time. We find that in post-stroke subjects the instantaneous phase increments of BP and BFV exhibit well pronounced patterns that remain stable in time for all four physiologic conditions, while in healthy subjects these patterns are different, less pronounced and more variable. Further, we show that the instantaneous phase increments of BP and BFV are cross-correlated even within a single heartbeat cycle. The maximum correlation str...

  14. Atmospheric Airborne Pressure Measurements Using the Oxygen A Band for the ASCENDS Mission

    Science.gov (United States)

    Riris, Haris; Rodriguez, Mike; Stephen, Mark; Hasselbrack, William; Allan, Graham; Mao, Jiamping,; Kawa, Stephan R.; Weaver, Clark J.

    2011-01-01

    We report on airborne atmospheric pressure measurements using new fiber-based laser technology and the oxygen A-band at 765 nm. Remote measurements of atmospheric temperature and pressure are required for a number of NASA Earth science missions and specifically for the Active Sensing of CO2 Emissions Over Nights, Days, and Seasons (ASCENDS) mission. Accurate measurements of tropospheric CO2 on a global scale are very important in order to better understand its sources and sinks and to improve predictions on any future climate change. The ultimate goal of a CO2 remote sensing mission, such as ASCENDS, is to derive the CO2 concentration in the atmosphere in terms of mole fraction in unit of parts-per-million (ppmv) with regard to dry air. Therefore, both CO2 and the dry air number of molecules in the atmosphere are needed in deriving this quantity. O2 is a stable molecule and uniformly mixed in the atmosphere. Measuring the O2 absorption in the atmosphere can thus be used to infer the dry air number of molecules and then used to calculate CO2 concentration. With the knowledge of atmospheric water vapor, we can then estimate the total surface pressure needed for CO2 retrievals. Our work, funded by the ESTO IIP program, uses fiber optic technology and non-linear optics to generate 765 nm laser radiation coincident with the Oxygen A-band. Our pulsed, time gated technique uses several on- and off-line wavelengths tuned to the O2 absorption line. The choice of wavelengths allows us to measure the pressure by using two adjacent O2 absorptions in the Oxygen A-band. Our retrieval algorithm fits the O2 lineshapes and derives the pressure. Our measurements compare favorably with a local weather monitor mounted outside our laboratory and a local weather station.

  15. Atmospheric pressure ionization-tandem mass spectrometry of the phenicol drug family.

    Science.gov (United States)

    Alechaga, Élida; Moyano, Encarnación; Galceran, M Teresa

    2013-11-01

    In this work, the mass spectrometry behaviour of the veterinary drug family of phenicols, including chloramphenicol (CAP) and its related compounds thiamphenicol (TAP), florfenicol (FF) and FF amine (FFA), was studied. Several atmospheric pressure ionization sources, electrospray (ESI), atmospheric pressure chemical ionization and atmospheric pressure photoionization were compared. In all atmospheric pressure ionization sources, CAP, TAP and FF were ionized in both positive and negative modes; while for the metabolite FFA, only positive ionization was possible. In general, in positive mode, [M + H](+) dominated the mass spectrum for FFA, while the other compounds, CAP, TAP and FF, with lower proton affinity showed intense adducts with species present in the mobile phase. In negative mode, ESI and atmospheric pressure photoionization showed the deprotonated molecule [M-H](-), while atmospheric pressure chemical ionization provided the radical molecular ion by electron capture. All these ions were characterized by tandem mass spectrometry using the combined information obtained by multistage mass spectrometry and high-resolution mass spectrometry in a quadrupole-Orbitrap instrument. In general, the fragmentation occurred via cyclization and losses or fragmentation of the N-(alkyl)acetamide group, and common fragmentation pathways were established for this family of compounds. A new chemical structure for the product ion at m/z 257 for CAP, on the basis of the MS(3) and MS(4) spectra is proposed. Thermally assisted ESI and selected reaction monitoring are proposed for the determination of these compounds by ultra high-performance liquid chromatography coupled to tandem mass spectrometry, achieving instrumental detection limits down to 0.1 pg.

  16. Spectral characteristics of atmospheric pressure and electric field variations under severe weather conditions at high latitudes

    OpenAIRE

    Kasatkina, E. A.; Shumilov, O. I.; Vinogradov, Y. A.; Vasilyev, A. N.

    2006-01-01

    International audience The time-dependent relationships between atmospheric parameters (electric field, positive and negative conductivity, variations of atmospheric pressure) and different meteorological phenomena (rain, fogs, snowstorms, thunderstorms) were investigated through spectral analysis. These parameters were measured with help of a high-latitude computer-aided complex installed at Apatity (66.5 N, 33.4 E). The complex consists of three spaced microbarographs for measurements of...

  17. Atmospheric Airborne Pressure Measurements Using the Oxygen A Band for the ASCENDS Mission

    Science.gov (United States)

    Rodriguez, M.; Riris, H.; Abshire, J. B.; Allan, G. R.; Stephen, M.; Hasselbrack, W.; Mao, J.

    2012-12-01

    We report on airborne atmospheric pressure measurements using fiber-based laser technology and the oxygen A-band at 765 nm. Remote atmospheric temperature and pressure measurements are needed for NASA's Active Sensing of CO2 Emissions Over Nights, Days, and Seasons (ASCENDS) mission. ASCENDS will measure atmospheric CO2 dry mixing ratios on a global scale. Remote atmospheric pressure measurements are necessary to normalize ASCENDS CO2 measurements. Our work, funded by the ESTO IIP program, uses erbium doped fiber optic amplifiers and non-linear optics technology to tune laser radiation over the Oxygen A-band between 764.5 nm and 765 nm. Surface reflections are fiber-coupled from a receiver telescope to photon counting detectors. Our pulsed, time gated approach resolves ground reflections from cloud returns. This system successfully recorded O2 absorption spectra during two airborne campaigns aboard a NASA DC-8. Airborne data has been analyzed and fitted to HITRAN reference spectra based upon aircraft meteorological data. Our algorithm linearly scales the HITRAN reference until measurement errors are minimized. Atmospheric pressure changes are estimated by comparing the differential optical depth of the optimum scaled HITRAN spectra to the differential optical depth of the nominal HITRAN spectra. On flights over gradually sloping terrain, these results compare favorably with ground-based observations and predictions from computer models. Measurement uncertainty is commensurate with photon counting noise. We plan to reduce measurement uncertainty in future campaigns by improving transmitter pulse energy and increasing wavelength sweep frequency.

  18. Scaling laws for gas breakdown for nanoscale to microscale gaps at atmospheric pressure

    Science.gov (United States)

    Loveless, Amanda M.; Garner, Allen L.

    2016-06-01

    Electronics miniaturization motivates gas breakdown predictions for microscale and smaller gaps, since traditional breakdown theory fails when gap size, d, is smaller than ˜15 μm at atmospheric pressure, patm. We perform a matched asymptotic analysis to derive analytic expressions for breakdown voltage, Vb, at patm for 1 nm ≤ d ≤ 35 μm. We obtain excellent agreement between numerical, analytic, and particle-in-cell simulations for argon, and show Vb decreasing as d → 0, instead of increasing as predicted by Paschen's law. This work provides an analytic framework for determining Vb at atmospheric pressure for various gap distances that may be extended to other gases.

  19. Plasma chemistry in an atmospheric pressure Ar/NH3 dielectric barrier discharge

    DEFF Research Database (Denmark)

    Fateev, A.; Leipold, F.; Kusano, Y.;

    2005-01-01

    An atmospheric pressure dielectric barrier discharge (DBD) in Ar/NH3 (0.1 - 10%) mixtures with a parallel plate electrode geometry was studied. The plasma was investigated by emission and absorption spectroscopy in the UV spectral range. Discharge current and voltage were measured as well. UV...... of an atmospheric pressure Ar/NH3 DBD are H-2, N-2 and N2H4. The hydrazine (N2H4) concentration in the plasma and in the exhaust gases at various ammonia concentrations and different discharge powers was measured. Thermal N2H4 decomposition into NH2 radicals may be used for NOx reduction processes....

  20. 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...

  1. Decontamination of a rotating cutting tool during operation by means of atmospheric pressure plasmas

    DEFF Research Database (Denmark)

    Leipold, Frank; Kusano, Yukihiro; Hansen, F.;

    2010-01-01

    The decontamination of a rotating cutting tool used for slicing in the meat industry by means of atmospheric pressure plasmas is investigated. The target is Listeria monocytogenes, a bacterium which causes listeriosis and can be found in plants and food. The non-pathogenic species, Listeria innocua......, is used for the experiments. A rotating knife was inoculated with L. innocua. The surface of the rotating knife was partly exposed to an atmospheric pressure dielectric barrier discharge operated in air, where the knife itself served as a ground electrode. The rotation of the knife ensures a treatment...

  2. Effects of initiating anaerobic digestion of layer-hen poultry dung at sub-atmospheric pressure

    OpenAIRE

    Chima C. Ngumah; Jude N. Ogbulie; Justina C. Orji; Ekperechi S. Amadi

    2013-01-01

    This study investigated the effects of initiating anaerobic digestion (AD) of dry layer-hen poultry dung at the sub-atmospheric pressure of -30 cmHg on biodegradation, biogasification, and biomethanation. The setup was performed as a batch process at an average ambient temperature of 29±2 0C and a retention time of 15 days. Comparisons were made with two other experiments which were both begun at ambient atmospheric pressure; one was inoculated with digestate from a previous layer-hen dung AD...

  3. Relation among Summer Rainfall in South Shandong and High Pressure in South Asia and Atmospheric Circulation

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    [Objective] The aim was to study the relation among summer rainfall in south Shandong and high pressure in South Asia and atmospheric circulation.[Method] Taking the precipitation in south Shandong along the Yellow River and Huaihe River,using the NCEP/NCAR data and summer rainfall data in south Shandong in summer from 1961 to 2005,the characteristics of high pressure in South Asia and atmospheric circulation in drought year and flood year in summer in south Shandong Province were expounded.The mechanism of...

  4. Thermodynamic analysis and experimental study of the effect of atmospheric pressure on the ice point

    Science.gov (United States)

    Harvey, A. H.; McLinden, M. O.; Tew, W. L.

    2013-09-01

    We present a detailed thermodynamic analysis of the temperature of the ice point as a function of atmospheric pressure. This analysis makes use of accurate international standards for the properties of water and ice, and of available high-accuracy data for the Henry's constants of atmospheric gases in liquid water. The result is an ice point of 273.150 019(5) K at standard atmospheric pressure, with higher ice-point temperatures (varying nearly linearly with pressure) at lower pressures. The effect of varying ambient CO2 concentration is analyzed and found to be significant in comparison to other uncertainties in the model. The thermodynamic analysis is compared with experimental measurements of the temperature difference between the ice point and the triple point of water performed at elevations ranging from 145 m to 4302 m, with atmospheric pressures from 101 kPa to 60 kPa. At the request of the authors and the Proceedings Editor the above article has been replaced with a corrected version. The original PDF file supplied to AIP Publishing contained several equations with incorrect/missing characters resulting from processes used to create the PDF file. The article has been replaced and the equations now display correctly.

  5. Using Dimers to Measure Biosignatures and Atmospheric Pressure for Terrestrial Exoplanets

    CERN Document Server

    Misra, Amit; Claire, Mark; Crisp, Dave

    2013-01-01

    We present a new method to probe atmospheric pressure on Earthlike planets using (O2-O2) dimers in the near-infrared. We also show that dimer features could be the most readily detectable biosignatures for Earthlike atmospheres, and may even be detectable in transit transmission with the James Webb Space Telescope (JWST). The absorption by dimers changes more rapidly with pressure and density than that of monomers, and can therefore provide additional information about atmospheric pressures. By comparing the absorption strengths of rotational and vibrational features to the absorption strengths of dimer features, we show that in some cases it may be possible to estimate the pressure at the reflecting surface of a planet. This method is demonstrated by using the O2 A band and the 1.06 $\\mu$m dimer feature, either in transmission or reflected spectra. It works best for planets around M dwarfs with atmospheric pressures between 0.1 and 10 bars, and for O2 volume mixing ratios above 50% of Earth's present day lev...

  6. Prediction of Atmospheric Pressure at Ground Level using Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    Angshuman Ray

    2013-01-01

    Full Text Available Prediction of Atmospheric Pressure is one important and challenging task that needs lot of attention and study for analyzing atmospheric conditions. Advent of digital computers and development of data driven artificial intelligence approaches like Artificial Neural Networks (ANN have helped in numerical prediction of pressure. However, very few works have been done till now in this area. The present study developed an ANN model based on the past observations of several meteorological parameters like temperature, humidity, air pressure and vapour pressure as an input for training the model. The novel architecture of the proposed model contains several multilayer perceptron network (MLP to realize better performance. The model is enriched by analysis of alternative hybrid model of k-means clustering and MLP. The improvement of the performance in the prediction accuracy has been demonstrated by the automatic selection of the appropriate cluster

  7. Atmospheric pressure X-ray photoelectron spectroscopy apparatus: Bridging the pressure gap

    OpenAIRE

    Velasco-Vélez, J.; Pfeifer, V.; Hävecker, M.; R. Wang; Centeno, A.; Zurutuza, A.; Algara-Siller, G.; Stotz, E.; Skorupska, K.; Teschner, D; Kube, P.; Braeuninger-Weimer, P.; Hofmann, S.; Schlögl, R.; Knop-Gericke, A.

    2016-01-01

    One of the main goals in catalysis is the characterization of solid/gas interfaces in a reaction environment. The electronic structure and chemical composition of surfaces become heavily influenced by the surrounding environment. However, the lack of surface sensitive techniques that are able to monitor these modifications under high pressure conditions hinders the understanding of such processes. This limitation is known throughout the community as the “pressure gap”. We have developed a nov...

  8. Time Invariant Surface Roughness Evolution during Atmospheric Pressure Thin Film Depositions

    OpenAIRE

    Thomas Merkh; Robert Spivey; Toh Ming Lu

    2016-01-01

    The evolution of thin film morphology during atmospheric pressure deposition has been studied utilizing Monte Carlo methods. Time invariant root-mean-squared roughness and local roughness morphology were both observed when employing a novel simulation parameter, modeling the effect of the experimental high pressure condition. This growth regime, where the surface roughness remains invariant after reaching a critical value, has not been classified by any existing universality class. An anti-sh...

  9. EDITORIAL: Atmospheric pressure non-thermal plasmas for processing and other applications

    Science.gov (United States)

    Massines, Françoise

    2005-02-01

    Interest has grown over the past few years in applying atmospheric pressure plasmas to plasma processing for the benefits this can offer to existing and potential new processes, because they do not require expensive vacuum systems and batch processing. There have been considerable efforts to efficiently generate large volumes of homogeneous atmospheric pressure non-thermal plasmas to develop environmentally friendly alternatives for surface treatment, thin film coating, sterilization, decontamination, etc. Many interesting questions have arisen that are related to both fundamental and applied research in this field. Many concern the generation of a large volume discharge which remains stable and uniform at atmospheric pressure. At this pressure, depending on the experimental conditions, either streamer or Townsend breakdown may occur. They respectively lead to micro-discharges or to one large radius discharge, Townsend or glow. However, the complexity arises from the formation of large radius streamers due to avalanche coupling and from the constriction of the glow discharge due to too low a current. Another difficulty is to visually distinguish many micro-discharges from one large radius discharge. Other questions relate to key chemical reactions in the plasma and at the surface. Experimental characterization and modelling also need to be developed to answer these questions. This cluster collects up-to-date research results related to the understanding of different discharges working at atmospheric pressure and the application to polymer surface activation and thin film coating. It presents different solutions for generating and sustaining diffuse discharges at atmospheric pressure. DC, low-frequency and radio-frequency excitations are considered in noble gases, nitrogen or air. Two specific methods developed to understand the transition from Townsend to streamer breakdown are also presented. They are based on the cross-correlation spectroscopy and an electrical

  10. Collision-induced dissociation analysis of negative atmospheric ion adducts in atmospheric pressure corona discharge ionization mass spectrometry.

    Science.gov (United States)

    Sekimoto, Kanako; Takayama, Mitsuo

    2013-05-01

    Collision-induced dissociation (CID) experiments were performed on atmospheric ion adducts [M + R](-) formed between various types of organic compounds M and atmospheric negative ions R(-) [such as O2(-), HCO3(-), COO(-)(COOH), NO2(-), NO3(-), and NO3(-)(HNO3)] in negative-ion mode atmospheric pressure corona discharge ionization (APCDI) mass spectrometry. All of the [M + R](-) adducts were fragmented to form deprotonated analytes [M - H](-) and/or atmospheric ions R(-), whose intensities in the CID spectra were dependent on the proton affinities of the [M - H](-) and R(-) fragments. Precursor ions [M + R](-) for which R(-) have higher proton affinities than [M - H](-) formed [M - H](-) as the dominant product. Furthermore, the CID of the adducts with HCO3(-) and NO3(-)(HNO3) led to other product ions such as [M + HO](-) and NO3(-), respectively. The fragmentation behavior of [M + R](-) for each R(-) observed was independent of analyte type (e.g., whether the analyte was aliphatic or aromatic, or possessed certain functional groups). PMID:23479312

  11. Collision-induced dissociation analysis of negative atmospheric ion adducts in atmospheric pressure corona discharge ionization mass spectrometry.

    Science.gov (United States)

    Sekimoto, Kanako; Takayama, Mitsuo

    2013-05-01

    Collision-induced dissociation (CID) experiments were performed on atmospheric ion adducts [M + R](-) formed between various types of organic compounds M and atmospheric negative ions R(-) [such as O2(-), HCO3(-), COO(-)(COOH), NO2(-), NO3(-), and NO3(-)(HNO3)] in negative-ion mode atmospheric pressure corona discharge ionization (APCDI) mass spectrometry. All of the [M + R](-) adducts were fragmented to form deprotonated analytes [M - H](-) and/or atmospheric ions R(-), whose intensities in the CID spectra were dependent on the proton affinities of the [M - H](-) and R(-) fragments. Precursor ions [M + R](-) for which R(-) have higher proton affinities than [M - H](-) formed [M - H](-) as the dominant product. Furthermore, the CID of the adducts with HCO3(-) and NO3(-)(HNO3) led to other product ions such as [M + HO](-) and NO3(-), respectively. The fragmentation behavior of [M + R](-) for each R(-) observed was independent of analyte type (e.g., whether the analyte was aliphatic or aromatic, or possessed certain functional groups).

  12. Assessing fluctuating evolutionary pressure in yeast and mammal evolutionary rate covariation using bioinformatics of meiotic protein genetic sequences

    Science.gov (United States)

    Dehipawala, Sunil; Nguyen, A.; Tremberger, G.; Cheung, E.; Holden, T.; Lieberman, D.; Cheung, T.

    2013-09-01

    The evolutionary rate co-variation in meiotic proteins has been reported for yeast and mammal using phylogenic branch lengths which assess retention, duplication and mutation. The bioinformatics of the corresponding DNA sequences could be classified as a diagram of fractal dimension and Shannon entropy. Results from biomedical gene research provide examples on the diagram methodology. The identification of adaptive selection using entropy marker and functional-structural diversity using fractal dimension would support a regression analysis where the coefficient of determination would serve as evolutionary pathway marker for DNA sequences and be an important component in the astrobiology community. Comparisons between biomedical genes such as EEF2 (elongation factor 2 human, mouse, etc), WDR85 in epigenetics, HAR1 in human specificity, clinical trial targeted cancer gene CD47, SIRT6 in spermatogenesis, and HLA-C in mosquito bite immunology demonstrate the diagram classification methodology. Comparisons to the SEPT4-XIAP pair in stem cell apoptosis, testesexpressed taste genes TAS1R3-GNAT3 pair, and amyloid beta APLP1-APLP2 pair with the yeast-mammal DNA sequences for meiotic proteins RAD50-MRE11 pair and NCAPD2-ICK pair have accounted for the observed fluctuating evolutionary pressure systematically. Regression with high R-sq values or a triangular-like cluster pattern for concordant pairs in co-variation among the studied species could serve as evidences for the possible location of common ancestors in the entropy-fractal dimension diagram, consistent with an example of the human-chimp common ancestor study using the FOXP2 regulated genes reported in human fetal brain study. The Deinococcus radiodurans R1 Rad-A could be viewed as an outlier in the RAD50 diagram and also in the free energy versus fractal dimension regression Cook's distance, consistent with a non-Earth source for this radiation resistant bacterium. Convergent and divergent fluctuating evolutionary

  13. Self-sustained carbon monoxide oxidation oscillations on size-selected platinum nanoparticles at atmospheric pressure

    DEFF Research Database (Denmark)

    Jensen, Robert; Andersen, Thomas; Nierhoff, Anders Ulrik Fregerslev;

    2013-01-01

    High-quality mass spectrometry data of the oscillatory behavior of CO oxidation on SiO2 supported Pt-nanoparticles at atmospheric pressure have been acquired as a function of pressure, coverage, gas composition and nanoparticle size. The oscillations are self-sustained for several days at constant......, temperature, pressure and CO/O2 ratio. The frequency of the oscillations is very well defined and increases over time. The oscillation frequency is furthermore strongly temperature dependent with increasing temperature resulting in increasing frequency. A plausible mechanism for the oscillations is proposed...

  14. Sterilization of packed matter by means of low temperature atmospheric pressure plasmas

    DEFF Research Database (Denmark)

    Leipold, Frank

    2010-01-01

    Summary form only given. The decontamination of material in closed containers by means of atmospheric pressure plasmas is investigated. The target is Listeria monocytogenes, a bacterium which causes listeriosis and can be found in plants and food. The non-pathogenic species, Listeria innocua, is...

  15. High-throughput processes for industrially scalable deposition of zinc oxide at atmospheric pressure

    NARCIS (Netherlands)

    Illiberi, A.; Grob, F.; Kniknie, B.; Frijters, C.; Deelen, J. van; Poodt, P.; Beckers, E.H.A.; Bolt, P.J.

    2014-01-01

    ZnO films have been grown on a moving glass substrate by high temperature (480 0C) chemical vapour deposition (CVD) and low temperature (200 0C) plasma enhanced CVD (PE-CVD) process at atmospheric pressure. Deposition rates above 7 nm/s have been achieved for substrate speeds from 20 to 500 mm/min.

  16. Quasi-static vapor pressure measurements on reactive systems in inert atmosphere box

    Science.gov (United States)

    Fischer, A. K.

    1968-01-01

    Apparatus makes vapor pressure measurements on air-sensitive systems in an inert atmosphere glove box. Once the apparatus is loaded with the sample and all connections made, all measuring operations may be performed outside the box. The apparatus is a single-tube adaptation of the double-tube quasi-static technique.

  17. Synthesis of 1,1'-binaphthyl-2,2'-diamine from 2-naphthol under atmospheric pressure

    Institute of Scientific and Technical Information of China (English)

    Qiang Feng; Chao Zhang; Qiang Tang; Mei Ming Luo

    2009-01-01

    A practical protocol to obtain 1,1'-binaphthyl-2,2'-diamine was developed from 2-naphthol and 2-naphthylhydrazine under mild conditions: solvent-free, 125-130 ℃, atmospheric pressure. The convenient procedure makes the process amenable for large-scale synthesis of the versatile compound.

  18. Atmospheric pressure cold plasma synthesis of submicrometer-sized pharmaceuticals with improved physicochemical properties

    NARCIS (Netherlands)

    Radacsi, N.; Ambrus, R.; Szabó-Révész, P.; Heijden, A.E.D.M. van der; Horst, J.H. ter

    2012-01-01

    A reduction in particle size is one of the strategies to enhance the dissolution behavior of low water-soluble drugs such as niflumic acid. Atmospheric pressure cold plasma crystallization is a novel technique to achieve such submicrometer particles. This technique uses a surface dielectric barrier

  19. 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...

  20. Sterilization of packed matter by means of low temperature atmospheric pressure plasmas

    DEFF Research Database (Denmark)

    Leipold, Frank

    2010-01-01

    Summary form only given. The decontamination of material in closed containers by means of atmospheric pressure plasmas is investigated. The target is Listeria monocytogenes, a bacterium which causes listeriosis and can be found in plants and food. The non-pathogenic species, Listeria innocua...

  1. Comparison of the sensitivity of mass spectrometry atmospheric pressure ionization techniques in the analysis of porphyrinoids.

    Science.gov (United States)

    Swider, Paweł; Lewtak, Jan P; Gryko, Daniel T; Danikiewicz, Witold

    2013-10-01

    The porphyrinoids chemistry is greatly dependent on the data obtained in mass spectrometry. For this reason, it is essential to determine the range of applicability of mass spectrometry ionization methods. In this study, the sensitivity of three different atmospheric pressure ionization techniques, electrospray ionization, atmospheric pressure chemical ionization and atmospheric pressure photoionization, was tested for several porphyrinods and their metallocomplexes. Electrospray ionization method was shown to be the best ionization technique because of its high sensitivity for derivatives of cyanocobalamin, free-base corroles and porphyrins. In the case of metallocorroles and metalloporphyrins, atmospheric pressure photoionization with dopant proved to be the most sensitive ionization method. It was also shown that for relatively acidic compounds, particularly for corroles, the negative ion mode provides better sensitivity than the positive ion mode. The results supply a lot of relevant information on the methodology of porphyrinoids analysis carried out by mass spectrometry. The information can be useful in designing future MS or liquid chromatography-MS experiments.

  2. Surface modification of nanofibrillated cellulose films by atmospheric pressure dielectric barrier discharge

    DEFF Research Database (Denmark)

    Siró, Istvan; Kusano, Yukihiro; Norrman, Kion;

    2013-01-01

    of atmospheric pressure plasma treatment, the water contact angle of NFC films increased and the values were comparable with those of PLA films. On the other hand, surface chemical characterization revealed inhomogeneity of the plasma treatment and limited improvement in adhesion between NFC and PLA films...

  3. Atmospheric pressure plasma treatment of glass fibre composite for adhesion improvement

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Mortensen, H.; Stenum, Bjarne;

    2007-01-01

    Glass-fibre-reinforced polyester composite plates were treated with an atmospheric pressure dielectric barrier discharge. Synthetic air was used as the treatment gas. The water contact angle dropped markedly from 84 to 22° after a 2-s treatment, and decreased to 0° when the composite plates were...

  4. Characterization of typical chemical background interferences in atmospheric pressure ionization liquid chromatography-mass spectrometry

    NARCIS (Netherlands)

    Guo, Xinghua; Bruins, Andries P.; Covey, Thomas R.

    2006-01-01

    The structures and origins of typical chemical background noise ions in positive atmospheric pressure ionization liquid chromatography/mass spectrometry (API LC/MS) are investigated and summarized in this study. This was done by classifying chemical background ions using precursor and product ion sc

  5. Atmospheric pressure plasma surface modification of titanium for high temperature adhesive bonding

    NARCIS (Netherlands)

    Akram, M.; Jansen, K.M.B.; Ernst, L.J.; Bhowmik, S.

    2011-01-01

    In this investigation surface treatment of titanium is carried out by plasma ion implantation under atmospheric pressure plasma in order to increase the adhesive bond strength. Prior to the plasma treatment, titanium surfaces were mechanically treated by sand blasting. It is observed that the contac

  6. treatment of polyimide by an atmospheric pressure plasma of capacitive rf discharge for liquid crystal alignment

    International Nuclear Information System (INIS)

    Uniform planar alignment of liquid crystals is obtained by polyimide films obliquely treated by a stream of argon plasma from capacitive RF discharge at atmospheric pressure. Two liquid crystal alignment modes are discovered differing by their longitudinal or transverse orientation with respect to treatment direction. Optimum parameters of the treatment for obtaining these orientation modes are determined.

  7. Atmospheric pressure photoionisation : An ionization method for liquid chromatography-mass spectrometry

    NARCIS (Netherlands)

    Robb, DB; Covey, TR; Bruins, AP

    2000-01-01

    Atmospheric pressure photoionization (APPI) has been successfully demonstrated to provide high sensitivity to LC-MS analysis. A vacuum-ultraviolet lamp designed for photoionization detection in gas chromatography is used as a source of 10-eV photons. The mixture of samples and solvent eluting from a

  8. Real-Time Flavor Release from French Fries Using Atmospheric Pressure Chemical Ionization-Mass Spectrometry

    NARCIS (Netherlands)

    Loon, W.A.M.; Linssen, J.P.H.; Boelrijk, A.E.M.; Burgering, M.J.M.; Voragen, A.G.J.

    2005-01-01

    Flavor release from French fries was measured with atmospheric pressure chemical ionization-mass spectrometry (APCI-MS) using both assessors (in vivo) and a mouth model system (in vitro). Several volatiles measured with APCI were identified with MS-MS. The effect of frying time, salt addition, and a

  9. Polysilicon Prepared from SIC14 by Atmospheric-Pressure Non-Thermal Plasma%Polysilicon Prepared from SIC14 by Atmospheric-Pressure Non-Thermal Plasma

    Institute of Scientific and Technical Information of China (English)

    李小松; 王楠; 杨晋华; 王友年; 朱爱民

    2011-01-01

    Non-thermal plasma at atmospheric pressure was explored for the preparation of polysilicon from SiCl4. The power supply sources of positive pulse and alternating current (8 kHz and 100 kHz) were compared for polysilicon preparation. The samples prepared by using the 100 kHz power source were crystalline silicon. The effects of H2 and SiCl4 volume fractions were investigated. The optical emission spectra showed that silicon species played an important role in polysilicon deposition

  10. Surface-initiated graft polymerization on multiwalled carbon nanotubes pretreated by corona discharge at atmospheric pressure.

    Science.gov (United States)

    Xu, Lihua; Fang, Zhengping; Song, Ping'an; Peng, Mao

    2010-03-01

    Surface-initiated graft polymerization on multi-walled carbon nanotubes pretreated with a corona discharge at atmospheric pressure was explored. The mechanism of the corona-discharge-induced graft polymerization is discussed. The results indicate that MWCNTs were encapsulated by poly(glycidyl methacrylate) (PGMA), demonstrating the formation of PGMA-grafted MWCNTs (PGMA-g-MWCNTs), with a grafting ratio of about 22 wt%. The solubility of PGMA-g-MWCNTs in ethanol was dramatically improved compared to pristine MWCNTs, which could contribute to fabricating high-performance polymer/MWCNTs nanocomposites in the future. Compared with most plasma processes, which operate at low pressures, corona discharge has the merit of working at atmospheric pressure. PMID:20644821

  11. Gas permeation barriers deposited by atmospheric pressure plasma enhanced atomic layer deposition

    International Nuclear Information System (INIS)

    This paper reports on aluminum oxide (Al2O3) thin film gas permeation barriers fabricated by atmospheric pressure atomic layer deposition (APPALD) using trimethylaluminum and an Ar/O2 plasma at moderate temperatures of 80 °C in a flow reactor. The authors demonstrate the ALD growth characteristics of Al2O3 films on silicon and indium tin oxide coated polyethylene terephthalate. The properties of the APPALD-grown layers (refractive index, density, etc.) are compared to that deposited by conventional thermal ALD at low pressures. The films films deposited at atmospheric pressure show water vapor transmission rates as low as 5 × 10−5 gm−2d−1

  12. Airborne and ground based lidar measurements of the atmospheric pressure profile

    Science.gov (United States)

    Korb, C. Laurence; Schwemmer, Geary K.; Dombrowski, Mark; Weng, Chi Y.

    1989-01-01

    The first high accuracy remote measurements of the atmospheric pressure profile have been made. The measurements were made with a differential absorption lidar system that utilizes tunable alexandrite lasers. The absorption in the trough between two lines in the oxygen A-band near 760 nm was used for probing the atmosphere. Measurements of the two-dimensional structure of the pressure field were made in the troposphere from an aircraft looking down. Also, measurements of the one-dimensional structure were made from the ground looking up. Typical pressure accuracies for the aircraft measurements were 1.5-2 mbar with a 30-m vertical resolution and a 100-shot average (20 s), which corresponds to a 2-km horizontal resolution. Typical accuracies for the upward viewing ground based measurements were 2.0 mbar for a 30-m resolution and a 100-shot average.

  13. A Minimized Mutual Information retrieval for simultaneous atmospheric pressure and temperature

    CERN Document Server

    Koner, Prabhat K

    2010-01-01

    The primary focus of the Mars Trace Gas Orbiter (TGO) collaboration between NASA and ESA is the detection of the temporal and spatial variation of the atmospheric trace gases using a solar occultation Fourier transform spectrometer. To retrieve any trace gas mixing ratios from these measurements, the atmospheric pressure and temperature have to be known accurately. Thus, a prototype retrieval model for the determination of pressure and temperature from a broadband high resolution infrared Fourier Transform spectrometer experiment with the Sun as a source on board a spacecraft orbiting the planet Mars is presented. It is found that the pressure and temperature can be uniquely solved from remote sensing spectroscopic measurements using a Regularized Total Least Squares method and selected pairs of micro-windows without any a-priori information of the state space parameters and other constraints. The selection of the pairs of suitable micro-windows is based on the information content analysis. A comparative info...

  14. Gas permeation barriers deposited by atmospheric pressure plasma enhanced atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Hoffmann, Lukas, E-mail: lhoffmann@uni-wuppertal.de; Theirich, Detlef; Hasselmann, Tim; Räupke, André; Schlamm, Daniel; Riedl, Thomas, E-mail: t.riedl@uni-wuppertal.de [Institute of Electronic Devices, University of Wuppertal, Rainer-Gruenter-Str. 21, 42119 Wuppertal (Germany)

    2016-01-15

    This paper reports on aluminum oxide (Al{sub 2}O{sub 3}) thin film gas permeation barriers fabricated by atmospheric pressure atomic layer deposition (APPALD) using trimethylaluminum and an Ar/O{sub 2} plasma at moderate temperatures of 80 °C in a flow reactor. The authors demonstrate the ALD growth characteristics of Al{sub 2}O{sub 3} films on silicon and indium tin oxide coated polyethylene terephthalate. The properties of the APPALD-grown layers (refractive index, density, etc.) are compared to that deposited by conventional thermal ALD at low pressures. The films films deposited at atmospheric pressure show water vapor transmission rates as low as 5 × 10{sup −5} gm{sup −2}d{sup −1}.

  15. Fluctuation of Brain Tissue Oxygen Partial Pressure: A Biochemical Landmark in the Arctic Ground Squirrel's Spontaneous Arousal

    Directory of Open Access Journals (Sweden)

    Yi L. Ma

    2011-01-01

    Full Text Available Hibernation in the Arctic ground Squirrel (AGS is a regulated, adaptive response to arctic environmental conditions. Problem statement: Regional brain Blood Flow (rCBF has been observed to increase dramatically during arousal in hibernators. However, the real time dynamic change in PtO2 during arousal has not been studied, we hypothesized that PtO2 is Interdependent of Tbrain and a key component in the arousal process. Approach: Simultaneous in vivo measurements of PtO2 and brain temperature (Tbrain in conjunction with oxygen consumption (V02 were conducted in the striatum of non-sedated, non-anesthetized Arctic ground squirrels during spontaneous arousal from hibernation. Results: A dramatic fluctuation of brain tissue oxygen partial pressure (PtO2 is associated with the complex phenomena of spontaneous arousal. In this study, we observed that: (1 a PtO2 elevation precedes changes in Tbrain and V02; (2 PtO2 changes do not correlate with changes in V02 during arousal and (3, endogenous O2 shift from O2 enriched blood to brain in hibernating AGS induces an arousal with the pharmaceutical chemical, efaproxiral (RSR-13. Conclusion: The four turning points of PtO2 appearing at different Tbrain during arousal suggest that changes in PtO2 are Tbrain interdependent and support the concept that arousal from hibernation is complex process invoking different feedbacks.

  16. Weather forecasting by insects: modified sexual behaviour in response to atmospheric pressure changes.

    Science.gov (United States)

    Pellegrino, Ana Cristina; Peñaflor, Maria Fernanda Gomes Villalba; Nardi, Cristiane; Bezner-Kerr, Wayne; Guglielmo, Christopher G; Bento, José Maurício Simões; McNeil, Jeremy N

    2013-01-01

    Prevailing abiotic conditions may positively or negatively impact insects at both the individual and population levels. For example while moderate rainfall and wind velocity may provide conditions that favour development, as well as movement within and between habitats, high winds and heavy rains can significantly decrease life expectancy. There is some evidence that insects adjust their behaviours associated with flight, mating and foraging in response to changes in barometric pressure. We studied changes in different mating behaviours of three taxonomically unrelated insects, the curcurbit beetle, Diabrotica speciosa (Coleoptera), the true armyworm moth, Pseudaletia unipuncta (Lepidoptera) and the potato aphid, Macrosiphum euphorbiae (Hemiptera), when subjected to natural or experimentally manipulated changes in atmospheric pressure. In response to decreasing barometric pressure, male beetles exhibited decreased locomotory activity in a Y-tube olfactometer with female pheromone extracts. However, when placed in close proximity to females, they exhibited reduced courtship sequences and the precopulatory period. Under the same situations, females of the true armyworm and the potato aphid exhibited significantly reduced calling behaviour. Neither the movement of male beetles nor the calling of armyworm females differed between stable and increasing atmospheric pressure conditions. However, in the case of the armyworm there was a significant decrease in the incidence of mating under rising atmospheric conditions, suggesting an effect on male behaviour. When atmospheric pressure rose, very few M. euphorbiae oviparae called. This was similar to the situation observed under decreasing conditions, and consequently very little mating was observed in this species except under stable conditions. All species exhibited behavioural modifications, but there were interspecific differences related to size-related flight ability and the diel periodicity of mating activity. We

  17. High-pressure synchrotron Mössbauer and X-ray diffraction studies: Exploring the structure-related valence fluctuation in EuNi2P2

    Science.gov (United States)

    Li, Chunyu; Yu, Zhenhai; Bi, Wenli; Zhao, Jiyong; Hu, Michael Y.; Zhao, Jinggeng; Wu, Wei; Luo, Jianlin; Yan, Hao; Alp, Esen E.; Liu, Haozhe

    2016-11-01

    The high-pressure effect on valence fluctuation of the ThCr2Si2-type intermetallic compound EuNi2P2 has been investigated using in situ synchrotron Mössbauer spectroscopy (SMS). The isomer shift of 151Eu in EuNi2P2 increases monotonically with increasing pressure up to 50 GPa, suggesting a valence transition of the Eu from mixed toward trivalent. The synchrotron angle-dispersive X-ray diffraction (AD-XRD) experiment shows that EuNi2P2 remains in the tetragonal structure up to 32.5 GPa at room temperature. We propose that the evolutions of bonding distance with pressure have an obvious effect on the valence fluctuation.

  18. 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.

  19. Pulmonary and heart diseases with inhalation of atmospheric pressure plasma flow

    Science.gov (United States)

    Hirata, Takamichi; Murata, Shigeru; Kishimoto, Takumi; Tsutsui, Chihiro; Kondo, Akane; Mori, Akira

    2012-10-01

    We examined blood pressure in the abdominal aorta of mini pig under plasma inhalation of atmospheric pressure plasma flow. The coaxial atmospheric pressure plasma source has a tungsten wire inside a glass capillary, that is surrounded by a grounded tubular electrode. Plasma was generated under the following conditions; applied voltage: 8 kVpp, frequency: 3 kHz, and helium (He) gas flow rate: 1 L/min. On the other hand, sphygmomanometry of a blood vessel proceeded using a device comprising a disposable force transducer, and a bedside monitor for simultaneous electrocardiography and signal pressure measurements. We directly measured Nitric oxide (NO) using a catheter-type NO sensor placed in the coronary sinus through an angiography catheter from the abdomen. Blood pressure decreased from 110/65 to 90/40 mm Hg in the animals in vivo under plasma inhalation. The NO concentration in the abdominal aorta like the blood pressure, reached a maximum value at about 40 s and then gradually decreased.

  20. LC-MS analysis of estradiol in human serum and endometrial tissue: Comparison of electrospray ionization, atmospheric pressure chemical ionization and atmospheric pressure photoionization.

    Science.gov (United States)

    Keski-Rahkonen, Pekka; Huhtinen, Kaisa; Desai, Reena; Harwood, D Tim; Handelsman, David J; Poutanen, Matti; Auriola, Seppo

    2013-09-01

    Accurate measurement of estradiol (E2) is important in clinical diagnostics and research. High sensitivity methods are critical for specimens with E2 concentrations at low picomolar levels, such as serum of men, postmenopausal women and children. Achieving the required assay performance with LC-MS is challenging due to the non-polar structure and low proton affinity of E2. Previous studies suggest that ionization has a major role for the performance of E2 measurement, but comparisons of different ionization techniques for the analysis of clinical samples are not available. In this study, female serum and endometrium tissue samples were used to compare electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) in both polarities. APPI was found to have the most potential for E2 analysis, with a quantification limit of 1 fmol on-column. APCI and ESI could be employed in negative polarity, although being slightly less sensitive than APPI. In the presence of biological background, ESI was found to be highly susceptible to ion suppression, while APCI and APPI were largely unaffected by the sample matrix. Irrespective of the ionization technique, background interferences were observed when using the multiple reaction monitoring transitions commonly employed for E2 (m/z 271 > 159; m/z 255 > 145). These unidentified interferences were most severe in serum samples, varied in intensity between ionization techniques and required efficient chromatographic separation in order to achieve specificity for E2.

  1. Thermoeconomic analysis of large solid oxide fuel cell plants: Atmospheric vs. pressurized performance

    International Nuclear Information System (INIS)

    A detailed thermoeconomic analysis of two large solid oxide fuel cell-based power plants operating at atmospheric pressure and 20 bar, respectively, is assessed in this work. The analyzed systems employ SOFC-GT (gas turbine) modules as main power generators; a bottom HRSC (heat recovery steam cycle) to generate additional electricity from the SOFC-GT exhaust hot gases is also included. The thermodynamic and economic performance of the two plant configurations are studied in detail: the exergy analysis shows an enhanced exergetic performance for the pressurized cycle that features components with higher efficiency and consequently a lower rate of exergy destruction (∼20% less than the atmospheric plant). The economic analysis considers the capital cost of each component within the system and is developed aiming at estimating the levelized cost of electricity. In order to match both exergetic and economic parts, a rigorous thermoeconomic analysis following the theory of Valero and Bejan [1,2] is implemented. A well-defined set of rules for the exergoeconomic balance around each plant component is specified and specific cost balance equations are thus derived. Results show how pressurized plant outperforms the atmospheric one, with a (on exergo-economic base) cost of electricity of 47.7 $/MWh instead of 64.2 $/MWh. Therefore, both exergetic and economic advantages result from the adoption of a pressurized SOFC-GT cycle in the framework of future advance power plants based on high-temperature fuel cells. - Highlights: • Exergy analysis of atmospheric and pressurized SOFC plants. • Exergy destruction in a fuel cell hybrid power plant. • Rigorous thermoeconomic methodology to assess the performance of different power generation plants. • Economic performance of SOFC plants

  2. Simulation Tool for Dielectric Barrier Discharge Plasma Actuators at Atmospheric and Sub-Atmospheric Pressures: SBIR Phase I Final Report

    Science.gov (United States)

    Likhanskii, Alexandre

    2012-01-01

    This report is the final report of a SBIR Phase I project. It is identical to the final report submitted, after some proprietary information of administrative nature has been removed. The development of a numerical simulation tool for dielectric barrier discharge (DBD) plasma actuator is reported. The objectives of the project were to analyze and predict DBD operation at wide range of ambient gas pressures. It overcomes the limitations of traditional DBD codes which are limited to low-speed applications and have weak prediction capabilities. The software tool allows DBD actuator analysis and prediction for subsonic to hypersonic flow regime. The simulation tool is based on the VORPAL code developed by Tech-X Corporation. VORPAL's capability of modeling DBD plasma actuator at low pressures (0.1 to 10 torr) using kinetic plasma modeling approach, and at moderate to atmospheric pressures (1 to 10 atm) using hydrodynamic plasma modeling approach, were demonstrated. In addition, results of experiments with pulsed+bias DBD configuration that were performed for validation purposes are reported.

  3. Restraint Effect of Filaments on Applied Voltage in Atmospheric Pressure Glow Discharge%Restraint Effect of Filaments on Applied Voltage in Atmospheric Pressure Glow Discharge

    Institute of Scientific and Technical Information of China (English)

    李森; 陈强; 刘忠伟

    2012-01-01

    In this study, argon and nitrogen were used as the discharge gases in radio-frequency (RF: 13.56 MHz) powered dielectric barrier atmospheric plasma. It was noticed that in single dielectric barrier discharge (DBD) with nitrogen as the discharge gas, or in argon plasma with a high applied power, micro-filament channels were easily formed. The channels in these two kinds of discharge were both constrictive on the bare metallic electrode and expansive on the opposite electrode covered with a quartz layer. The number of micro-channels was increased along with the input power, which caused the change in the I-V curve shape, i.e., the current kept increasing and the voltage fluctuated within a confined range. With double dielectric layers, however, no micro-channels appeared in the ICCD images, and the I-V curve demonstrated a totally different shape. It was assumed that micro-filaments exhibited a restraining effect on the discharge voltage. The mechanism of this restraining effect was explored in this work.

  4. Where do winds come from? A new theory on how water vapor condensation influences atmospheric pressure and dynamics

    OpenAIRE

    Makarieva, A. M.; V. G. Gorshkov; D. Sheil; A. D. Nobre; B.-L. Li

    2013-01-01

    Phase transitions of atmospheric water play a ubiquitous role in the Earth's climate system, but their direct impact on atmospheric dynamics has escaped wide attention. Here we examine and advance a theory as to how condensation influences atmospheric pressure through the mass removal of water from the gas phase with a simultaneous account of the latent heat release. Building from fundamental physical principles we show that condensation is associated with a decline in air pressure in t...

  5. Where do winds come from? A new theory on how water vapor condensation influences atmospheric pressure and dynamics

    OpenAIRE

    Makarieva, A. M.; V. G. Gorshkov; D. Sheil; A. D. Nobre; B.-L. Li

    2010-01-01

    Phase transitions of atmospheric water play a ubiquitous role in the Earth's climate system, but their direct impact on atmospheric dynamics has escaped wide attention. Here we examine and advance a theory as to how condensation influences atmospheric pressure through the mass removal of water from the gas phase with a simultaneous account of the latent heat release. Building from fundamental physical principles we show that condensation is associated with a decline in air pressure in t...

  6. Influence of piping layout upon the characteristics of flow separation and pressure fluctuation in the primary cold-leg of sodium cooled fast reactor

    International Nuclear Information System (INIS)

    In this study, the influence of the inflow condition upon the flow separation and pressure fluctuation characteristic was evaluated by using a 1/7-scale mockup of the cold-leg piping of Japan Sodium-cooled Fast Reactor. The inflow condition to the 3rd elbow was changed from previous studies by varying the distance between the 2nd and 3rd elbows from 6.4D to 9.4D, where D is the pipe diameter. Flow visualization with the two-dimensional particle image velocimetry and pressure measurement with fiber-optic pressure sensors were conducted to reveal the velocity and pressure fields of the flow in the piping. In the experiment, the Reynolds number was changed from 300,000 to 1,000,000, which belongs to the post-critical regime corresponding to the actual condition of the velocity. The visualization experiment showed that the flow separation appeared in the intrados of the 3rd elbow as was the case with 6.4D and separated regions became larger than that in the case of 6.4D. This is because a swirling flow observed at the inlet of the 3rd elbow became weaker than that of the case of 6.4D. The frequency analysis of pressure fluctuations showed that gentle but apparent peaks in the power spectral density (PSD) distributions of pressure fluctuations were observed at about 0.4 of the Strouhal number around the separated regions, and this peak value was half of that in the case of 6.4D. In addition, prominent peaks in the PSD distributions were observed at about 0.6 of the Strouhal number in the downstream of the reattachment point in the intrados. The peak value was approximately 3 times larger than that in the case of 6.4D. These results showed that the magnitude of the pressure fluctuations increased with expansion of the separated region. The results revealed the weakened swirling flow made the separated region larger in the downstream and the pressure fluctuation magnitude stronger. (author)

  7. High frequency glow discharges at atmospheric pressure with micro-structured electrode arrays

    Science.gov (United States)

    Baars-Hibbe, L.; Sichler, P.; Schrader, C.; Lucas, N.; Gericke, K.-H.; Büttgenbach, S.

    2005-02-01

    Micro-structured electrode (MSE) arrays allow the generation of large-area uniform glow discharges over a wide pressure range up to atmospheric pressure. The electrode widths, thicknesses and distances in the micrometre range are realized by means of modern micro-machining and galvanic techniques. The electrode distance, the gap width d, is small enough to generate sufficiently high electric field strengths to ignite gas discharges by applying only moderate radio frequency (RF, 13.56 MHz) voltages (80-390 V in Ne, He, Ar, N2 and air). The non-thermal plasma system is characterized by a special probe measuring the electric parameters. We tested MSE arrays with d = 70, 25 and 15 µm. The MSE driven plasmas show a different behaviour from conventional RF discharge plasmas. Due to the very small electrode gap width we can describe the behaviour of the charged particles in the RF field of our system with the dc Townsend breakdown theory, depending on the pressure range and gas. With decreasing pressure, the gas discharges, especially in Ne and He, are increasingly dominated by field electron emission. With the MSE arrays as plasma sources several applications were developed and successfully tested, e.g. decomposition of waste gases and sterilization of food packaging materials at atmospheric pressure.

  8. High frequency glow discharges at atmospheric pressure with micro-structured electrode arrays

    International Nuclear Information System (INIS)

    Micro-structured electrode (MSE) arrays allow the generation of large-area uniform glow discharges over a wide pressure range up to atmospheric pressure. The electrode widths, thicknesses and distances in the micrometre range are realized by means of modern micro-machining and galvanic techniques. The electrode distance, the gap width d, is small enough to generate sufficiently high electric field strengths to ignite gas discharges by applying only moderate radio frequency (RF, 13.56 MHz) voltages (80-390 V in Ne, He, Ar, N2 and air). The non-thermal plasma system is characterized by a special probe measuring the electric parameters. We tested MSE arrays with d = 70, 25 and 15 μm. The MSE driven plasmas show a different behaviour from conventional RF discharge plasmas. Due to the very small electrode gap width we can describe the behaviour of the charged particles in the RF field of our system with the dc Townsend breakdown theory, depending on the pressure range and gas. With decreasing pressure, the gas discharges, especially in Ne and He, are increasingly dominated by field electron emission. With the MSE arrays as plasma sources several applications were developed and successfully tested, e.g. decomposition of waste gases and sterilization of food packaging materials at atmospheric pressure

  9. Fabrication of YBCO film by TFA-MOD process at low-pressure atmosphere

    International Nuclear Information System (INIS)

    Influence of the process conditions, including the water partial pressure and the total annealing pressure, on YBa2Cu3O7-y (YBCO) film growth has been investigated in order to increase the growth rate. YBCO films have been fabricated on SrTiO3 substrate by metal-organic deposition using trifluoroacetates (TFA) as a solute source under the low-pressure atmosphere. It was observed that the growth rate of the YBCO film was in proportion to the square root of the water partial pressure and was in inverse proportion to the total pressure. A higher YBCO growth rate was achieved about 3 times as fast as that under the atmospheric fabrication conditions with maintaining the high Jc performance. On the other hand, the volume fraction of a-axis oriented grains in the YBCO film was strongly dependent on the growth rate, a-axis oriented YBCO grains were clearly recognized in the films grown with either very low or very high growth rate. As a result, it was found that the growth region should be controlled to prevent from the growth of the a-axis oriented grains

  10. Tribological Performance of Silahydrocarbons Used as Steel-Steel Lubricants under Vacuum and Atmospheric Pressure

    Directory of Open Access Journals (Sweden)

    Hai-Zhong Wang

    2014-01-01

    Full Text Available The silahydrocarbons of tetraalkylsilanes with different substituted alkyl groups (named as SiCH were synthesized and evaluated as lubricants for steel-steel contacts by a home-made vacuum four-ball tribometer (VFBT-4000 under atmospheric pressure and under vacuum pressure (5×10-4 Pa. The SiCH oils possess better thermal stability, low temperature fluidity, and lower saturated vapor pressure than those of multialkylatedcyclopentanes (MACs. The tribological performances of the SiCH oils are also superior to those of MACs and PFPE-Z25 in terms of friction-reduction ability and antiwear capacity under sliding friction at vacuum. The SEM/EDS and XPS results reveal that the boundary lubricating film consisting of (-O-Si-R-n compounds is formed by tribochemical reactions and serious adhesion wear under atmospheric pressure and the film consisting of (-Si-R-Si-n compounds is formed on the worn surface under vacuum pressure.

  11. Super-atmospheric pressure ionization mass spectrometry and its application to ultrafast online protein digestion analysis.

    Science.gov (United States)

    Chen, L C; Ninomiya, S; Hiraoka, K

    2016-06-01

    Pressure is a key parameter for an ionization source. In this Special Feature article, Lee Chuin Chen and colleagues review super-atmospheric pressure ionization MS with electrospray, corona-discharge-based chemical ionization, and field desorption. They routinely run their mass spectrometer with ion source pressures ranging from several to several tens of atmospheres. A number of strategies have been used to preserve the high vacuum of the instrument while working with a high-pressure (HP) ion source. A recent prototype uses a booster pump with variable pumping speed added to the first pumping stage of the mass spectrometer to regulate a constant vacuum pressure. Further, a new HP-ESI source allowing rapid (a few seconds) online protein digestion MS is also reported. Dr. Lee Chuin Chen is Associate Professor in the Department of Interdisciplinary Research at the University of Yamanashi (Yamanashi, Japan). His main research interest is the development of novel mass spectrometric methods for in-situ medical diagnosis. PMID:27270871

  12. Medium Vacuum Electron Emitter as Soft Atmospheric Pressure Chemical Ionization Source for Organic Molecules.

    Science.gov (United States)

    Liedtke, Sascha; Ahlmann, Norman; Marggraf, Ulrich; Schütz, Alexander; Vautz, Wolfgang; Franzke, Joachim

    2016-05-01

    An electron emitter as a soft atmospheric pressure chemical ionization source is presented, which operates at inner pressures of the device in the medium vacuum range (>10(-3) hPa). Conventional nonradioactive electron emitters require high vacuum (pump-by 2% compared to high-vacuum conditions. This can be compensated with an increase of the electron source output. The functionality of this ion source is demonstrated with mass spectrometric and ion mobility measurements of acetone, eucalyptol, and diisopropyl methanephosphonate. Additional mass spectrometric measurements of 20 different organic compounds demonstrate the soft characteristics of this ionization source. PMID:27046293

  13. The effect of meteorological data on atmospheric pressure loading corrections in VLBI data analysis

    Science.gov (United States)

    Balidakis, Kyriakos; Glaser, Susanne; Karbon, Maria; Soja, Benedikt; Nilsson, Tobias; Lu, Cuixian; Anderson, James; Liu, Li; Andres Mora-Diaz, Julian; Raposo-Pulido, Virginia; Xu, Minghui; Heinkelmann, Robert; Schuh, Harald

    2015-04-01

    Earth's crustal deformation is a manifestation of numerous geophysical processes, which entail the atmosphere and ocean general circulation and tidal attraction, climate change, and the hydrological circle. The present study deals with the elastic deformations induced by atmospheric pressure variations. At geodetic sites, APL (Atmospheric Pressure Loading) results in displacements covering a wide range of temporal scales which is undesirable when rigorous geodetic/geophysical analysis is intended. Hence, it is of paramount importance that the APL signal are removed at the observation level in the space geodetic data analysis. In this study, elastic non-tidal components of loading displacements were calculated in the local topocentric frame for all VLBI (Very Long Baseline Interferometry) stations with respect to the center-of-figure of the solid Earth surface and the center-of-mass of the total Earth system. The response of the Earth to the load variation at the surface was computed by convolving Farrell Green's function with the homogenized in situ surface pressure observations (in the time span 1979-2014) after the subtraction of the reference pressure and the S1, S2 and S3 thermal tidal signals. The reference pressure was calculated through a hypsometric adjustment of the absolute pressure level determined from World Meteorological Organization stations in the vicinity of each VLBI observatory. The tidal contribution was calculated following the 2010 International Earth Rotation and Reference Systems Service conventions. Afterwards, this approach was implemented into the VLBI software VieVS@GFZ and the entirety of available VLBI sessions was analyzed. We rationalize our new approach on the basis that the potential error budget is substantially reduced, since several common errors are not applicable in our approach, e.g. those due to the finite resolution of NWM (Numerical Weather Models), the accuracy of the orography model necessary for adjusting the former as

  14. Ultrasound enhanced 50 Hz plasma treatment of glass-fiber-reinforced polyester at atmospheric pressure

    DEFF Research Database (Denmark)

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

    2013-01-01

    Glass-fiber-reinforced polyester (GFRP) plates are treated using a 50Hz dielectric barrier discharge at a peak-to-peak voltage of 30 kV in helium at atmospheric pressure with and without ultrasonic irradiation to study adhesion improvement. The ultrasonic waves at the fundamental frequency...... of around 30 kHz with the sound pressure level of approximately 155 dB were introduced vertically to the GFRP surface through a cylindrical waveguide. The polar component of the surface energy was almost unchanged after the plasma treatment without ultrasonic irradiation, but drastically increased...

  15. 50-Hz plasma treatment of glass fibre reinforced polyester at atmospheric pressure enhanced by ultrasonic irradiation

    DEFF Research Database (Denmark)

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

    2011-01-01

    Glass fibre reinforced polyester (GFRP) plates are treated using a 50-Hz dielectric barrier discharge at peak-to-peak voltage of 30 kV in helium at atmospheric pressure with and without ultrasonic irradiation to study adhesion improvement. The ultrasonic waves at the fundamental frequency of around...... 30 kHz with the sound pressure level of approximately 155 dB were introduced vertically to the GFRP surface through a cylindrical waveguide. The polar component of the surface energy was almost unchanged after the plasma treatment without ultrasonic irradiation, but drastically increased...

  16. Hydrogen production by radio frequency plasma stimulation in methane hydrate at atmospheric pressure

    OpenAIRE

    Putra, Andi Erwin Eka

    2013-01-01

    Methane hydrate, formed by injecting methane into 100 g of shaved ice at a pressure of 7 MPa and reactor temperature of 0 ??C, was decomposed by applying 27.12 MHz radio frequency plasma in order to produce hydrogen. The process involved the stimulation of plasma in the methane hydrate with a variable input power at atmospheric pressure. It was observed that production of CH4 is optimal at a slow rate of CH4 release from the methane hydrate, as analyzed by in light of the steam...

  17. Black pepper powder microbiological quality improvement using DBD systems in atmospheric pressure

    Science.gov (United States)

    Grabowski, Maciej; Hołub, Marcin; Balcerak, Michał; Kalisiak, Stanisław; Dąbrowski, Waldemar

    2015-07-01

    Preliminary results are given regarding black pepper powder decontamination using dielectric barrier discharge (DBD) plasma in atmospheric pressure. Three different DBD reactor constructions were investigated, both packaged and unpackaged material was treated. Due to potential, industrial applications, in addition to microbiological results, water activity, loss of mass and the properties of packaging material, regarding barrier properties were investigated. Argon based treatment of packed pepper with DBD reactor configuration is proposed and satisfactory results are presented for treatment time of 5 min or less. Contribution to the topical issue "The 14th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XIV)", edited by Nicolas Gherardi, Ronny Brandenburg and Lars Stollenwark

  18. Pressure fluctuation prediction in pump mode using large eddy simulation and unsteady Reynolds-averaged Navier–Stokes in a pump–turbine

    Directory of Open Access Journals (Sweden)

    De-You Li

    2016-06-01

    Full Text Available For pump–turbines, most of the instabilities couple with high-level pressure fluctuations, which are harmful to pump–turbines, even the whole units. In order to understand the causes of pressure fluctuations and reduce their amplitudes, proper numerical methods should be chosen to obtain the accurate results. The method of large eddy simulation with wall-adapting local eddy-viscosity model was chosen to predict the pressure fluctuations in pump mode of a pump–turbine compared with the method of unsteady Reynolds-averaged Navier–Stokes with two-equation turbulence model shear stress transport k–ω. Partial load operating point (0.91QBEP under 15-mm guide vane opening was selected to make a comparison of performance and frequency characteristics between large eddy simulation and unsteady Reynolds-averaged Navier–Stokes based on the experimental validation. Good agreement indicates that the method of large eddy simulation could be applied in the simulation of pump–turbines. Then, a detailed comparison of variation for peak-to-peak value in the whole passage was presented. Both the methods show that the highest level pressure fluctuations occur in the vaneless space. In addition, the propagation of amplitudes of blade pass frequency, 2 times of blade pass frequency, and 3 times of blade pass frequency in the circumferential and flow directions was investigated. Although the difference exists between large eddy simulation and unsteady Reynolds-averaged Navier–Stokes, the trend of variation in different parts is almost the same. Based on the analysis, using the same mesh (8 million, large eddy simulation underestimates pressure characteristics and shows a better result compared with the experiments, while unsteady Reynolds-averaged Navier–Stokes overestimates them.

  19. Effect of ambient pressure and radiation reabsorption of atmosphere on the flame spreading over thermally thin combustibles in microgravity

    Institute of Scientific and Technical Information of China (English)

    杜文峰; 胡文瑞

    2003-01-01

    For the flame spread over thermally thin combustibles in an atmosphere, if the atmosphere cannot emit and absorb the thermal radiation (e.g. for atmosphere of O2-N2), the conductive heat transfer from the flame to the fuel surface dominates the flame spread at lower ambient atmosphere. As the ambient pressure increases, the flame spread rate increases, and the radiant heat transfer from the flame to the fuel surface gradually becomes the dominant driving force for the flame spread. In contrast, if the atmosphere is able to emit and absorb the thermal radiation (e.g. for atmosphere of O2-CO2), at lower pressure, the heat transfer from flame to the fuel surface is enhanced by the radiation reabsorption of the atmosphere at the leading edge of the flame, and both conduction and thermal radiation play important roles in the mechanism of flame spread. With the increase in ambient pressure, the oxygen diffuses more quickly from ambient atmosphere into the flame, the chemical reaction in the flame is enhanced, and the flame spread rate increases. When the ambient pressure is greater than a critical value, the thermal radiation from the flame to the solid surface is hampered by the radiation reabsorption of ambient atmosphere with the further increase in ambient pressure. As a result, with the increase in ambient pressure, the flame spread rate decreases and the heat conduction gradually dominates the flame spread over the fuel surface.

  20. Effect of anisotropic fluctuations of the refractive index on transhorizon ultrashort-wave propagation in the atmosphere

    Science.gov (United States)

    Koshel', K. V.; Shishkarev, A. A.

    1993-02-01

    A perturbation theory for complex propagation constants is considered, based on the invariant imbedding method. This approach makes it possible to describe the effect of nonstratified fluctuations of the refractive index on transhorizon propagation of ultrashort waves in the framework of the adiabatic approximation in the case when an evaporation duct exists. Examples of calculations are presented, and characteristic stochastic effects are studied.

  1. Gas Breakdown of Radio Frequency Glow Discharges in Helium at near Atmospheric Pressure

    Science.gov (United States)

    Liu, Xinkun; Xu, Jinzhou; Cui, Tongfei; Guo, Ying; Zhang, Jing; Shi, Jianjun

    2013-07-01

    A one-dimensional self-consistent fluid model was developed for radio frequency glow discharge in helium at near atmospheric pressure, and was employed to study the gas breakdown characteristics in terms of breakdown voltage. The effective secondary electron emission coefficient and the effective electric field for ions were demonstrated to be important for determining the breakdown voltage of radio frequency glow discharge at near atmospheric pressure. The constant of A was estimated to be 64±4 cm-1Torr-1, which was proportional to the first Townsend coefficient and could be employed to evaluate the gas breakdown voltage. The reduction in the breakdown voltage of radio frequency glow discharge with excitation frequency was studied and attributed to the electron trapping effect in the discharge gap.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-05-15

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

  3. Discharge Characteristics in Atmospheric Pressure Glow Surface Discharge in Helium Gas

    Institute of Scientific and Technical Information of China (English)

    LI Xue-Chen; WANG Long

    2005-01-01

    @@ Atmospheric pressure glow discharge is observed for the first time in a surface discharge generator in flowing helium. Electrical and optical methods are used to measure the characteristics of atmospheric pressure glow discharge for different voltages. The results show that discharge current waveforms are asymmetric for the different polarities of the applied voltage. A continuous discharge profile with a width of several microseconds appears for per half cycle of the applied voltage when the voltage is increased to a certain value. The short-pulsed discharge and the continuous current would result from the Townsend breakdown and glow discharge mechanisms respectively. The properties of surface discharge in stagnant helium are completely different from that in flowing helium.

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

    International Nuclear Information System (INIS)

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

  5. Atmospheric pressure spatial atomic layer deposition web coating with in situ monitoring of film thickness

    International Nuclear Information System (INIS)

    Spectral reflectometry was implemented as a method for in situ thickness monitoring in a spatial atomic layer deposition (ALD) system. Al2O3 films were grown on a moving polymer web substrate at 100 °C using an atmospheric pressure ALD web coating system, with film growth of 0.11–0.13 nm/cycle. The modular coating head design and the in situ monitoring allowed for the characterization and optimization of the trimethylaluminum and water precursor exposures, purge flows, and web speed. A thickness uniformity of ±2% was achieved across the web. ALD cycle times as low as 76 ms were demonstrated with a web speed of 1 m/s and a vertical gap height of 0.5 mm. This atmospheric pressure ALD system with in situ process control demonstrates the feasibility of low-cost, high throughput roll-to-roll ALD

  6. Electrical and optical properties of Ar/NH3 atmospheric pressure plasma jet

    Science.gov (United States)

    Chang, Zheng-Shi; Yao, Cong-Wei; Chen, Si-Le; Zhang, Guan-Jun

    2016-09-01

    Inspired by the Penning effect, we obtain a glow-like plasma jet by mixing ammonia (NH3) into argon (Ar) gas under atmospheric pressure. The basic electrical and optical properties of an atmospheric pressure plasma jet (APPJ) are investigated. It can be seen that the discharge mode transforms from filamentary to glow-like when a little ammonia is added into the pure argon. The electrical and optical analyses contribute to the explanation of this phenomenon. The discharge mode, power, and current density are analyzed to understand the electrical behavior of the APPJ. Meanwhile, the discharge images, APPJ's length, and the components of plasma are also obtained to express its optical characteristics. Finally, we diagnose several parameters, such as gas temperature, electron temperature, and density, as well as the density number of metastable argon atoms of Ar/NH3 APPJ to help judge the usability in its applications.

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

    Science.gov (United States)

    Tarasenko, V. F.

    2011-05-01

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

  8. Transparent conductive indium-doped zinc oxide films prepared by atmospheric pressure plasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Kow-Ming [Department of Electronics Engineering and Institute of Electronics, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu, Taiwan 30010 (China); College of Electrical and Information Engineering, I-Shou University, Kaohsiung County, Taiwan 84001 (China); Huang, Sung-Hung, E-mail: sunghunghuang@gmail.com [Department of Electronics Engineering and Institute of Electronics, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu, Taiwan 30010 (China); Wu, Chin-Jyi [Industrial Technology Research Institute, Mechanical and Systems Research Laboratories, 195, Sec. 4, Chung Hsing Rd., Chutung, Hsinchu, 31040, Taiwan (China); Lin, Wei-Li; Chen, Wei-Chiang; Chi, Chia-Wei [Department of Electronics Engineering and Institute of Electronics, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu, Taiwan 30010 (China); Lin, Je-Wei; Chang, Chia-Chiang [Industrial Technology Research Institute, Mechanical and Systems Research Laboratories, 195, Sec. 4, Chung Hsing Rd., Chutung, Hsinchu, 31040, Taiwan (China)

    2011-05-31

    Atmospheric-pressure plasma processing has attracted much interest for industrial applications due to its low cost, high processing speed and simple system. In this study, atmospheric-pressure plasma jet technique was developed to deposit indium-doped zinc oxide films. The inorganic metal salts of zinc nitrate and indium nitrate were used as precursors for Zn ions and In ions, respectively. The effect of different indium doping concentration on the morphological, structural, electrical and optical properties of the films was investigated. Grazing incidence X-ray diffraction results show that the deposited films with a preferred (002) orientation. The lowest resistivity of 1.8 x 10{sup -3} {Omega} cm was achieved with the 8 at.% indium-doped solution at the substrate temperature of 200 deg. C in open air, and average transmittance in the visible region was more than 80%.

  9. Role of ambient dielectric in propagation of Ar atmospheric pressure nonequilibrium plasma jets

    Science.gov (United States)

    Song, Jian; Tang, Jingfeng; Wang, Youyin; Wei, Liqiu; Ren, Chunsheng; Yu, Daren

    2015-05-01

    A single-electrode atmospheric pressure nonequilibrium plasma jet surrounded with different ambient dielectrics is investigated driven by AC power supply. Another three ambient dielectrics, distilled water, ethanol, and carbon tetrachloride, are adopted to compare with air. By examining electrical and optical characteristics, it was found that the molecular polarity of ambient dielectrics had its significant effect on the propagation of atmospheric pressure nonequilibrium plasma jets. When the polarization of molecules was enhanced, the discharge current and the bullet velocity were also increased. For nonpolar dielectric of carbon tetrachloride, this was mainly resulted from the electron polarization in the built-in electric field. For polar dielectrics of ethanol and distilled water, in addition to the electron polarization, orientation polarization was the main cause for the further increase in discharge current and bullet velocity.

  10. Synergistic effects of atmospheric pressure plasma-emitted components on DNA oligomers: a Raman spectroscopic study.

    Science.gov (United States)

    Edengeiser, Eugen; Lackmann, Jan-Wilm; Bründermann, Erik; Schneider, Simon; Benedikt, Jan; Bandow, Julia E; Havenith, Martina

    2015-11-01

    Cold atmospheric-pressure plasmas have become of increasing importance in sterilization processes especially with the growing prevalence of multi-resistant bacteria. Albeit the potential for technological application is obvious, much less is known about the molecular mechanisms underlying bacterial inactivation. X-jet technology separates plasma-generated reactive particles and photons, thus allowing the investigation of their individual and joint effects on DNA. Raman spectroscopy shows that particles and photons cause different modifications in DNA single and double strands. The treatment with the combination of particles and photons does not only result in cumulative, but in synergistic effects. Profilometry confirms that etching is a minor contributor to the observed DNA damage in vitro. Schematics of DNA oligomer treatment with cold atmospheric-pressure plasma.

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

    Science.gov (United States)

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

    2013-11-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-05-07

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

  13. Diffuse α-mode atmospheric pressure radio-frequency discharge in neon

    International Nuclear Information System (INIS)

    In this work, a radio-frequency (RF) atmospheric pressure glow discharge burning in neon between planar metal electrodes is achieved for the first time. The RF discharge can operate in two stable modes: in a diffuse α-mode with uniformly covered electrode surfaces and in a constricted γ-mode. Similarities are revealed when the discharge is compared against the RF atmospheric pressure glow discharge in helium, namely both discharges show a discontinuity and a hysteresis in the current–voltage characteristic at the mode transition; the spatio-temporal profiles of the light emission in the α-mode from neon, helium and atomic oxygen are also similar. (fast track communication)

  14. Apoptotic effects on cultured cells of atmospheric-pressure plasma produced using various gases

    Science.gov (United States)

    Tominami, Kanako; Kanetaka, Hiroyasu; Kudo, Tada-aki; Sasaki, Shota; Kaneko, Toshiro

    2016-01-01

    This study investigated the effects of low-temperature atmospheric-pressure plasma on various cells such as rat fibroblastic Rat-1 cell line, rat neuroblastoma-like PC12 cell line, and rat macrophage-like NR8383 cell line. The plasma was irradiated directly to a culture medium containing plated cells for 0-20 s. The applied voltage, excitation frequency, and argon or helium gas flow were, respectively, 3-6 kV, 10 kHz, and 3 L/min. Cell viability and apoptotic activity were evaluated using annexin-V/propidium iodide staining. Results showed that the low-temperature atmospheric-pressure plasma irradiation promoted cell death in a discharge-voltage-dependent and irradiation-time-dependent manner. Furthermore, different effects are produced depending on the cell type. Moreover, entirely different mechanisms might be responsible for the induction of apoptosis in cells by helium and argon plasma.

  15. Atmospheric Pressure non-thermal plasmas for surface treatment of polymer films

    Science.gov (United States)

    Huang, Hsiao-Feng; Wen, Chun-Hsiang; Wei, Hsiao-Kuan; Kou, Chwung-Shan

    2006-10-01

    Interest has grown over the past few years in applying atmospheric pressure non-thermal plasmas to surface treatment. In this work, we used an asymmetric glow dielectric-barrier discharge (GDBD), at atmospheric pressure in nitrogen, to improve the surface hydrophilicity of three kinds of polymer films, biaxially oriented polypropylene (BOPP), polyimide (PI), and triacetyl cellulose (TAC). This set-up consists of two asymmetric electrodes covered by dielectrics. And to prevent the filamentary discharge occur, the frequency, gas flow rate and uniformity of gas flow distribution should be carefully controlled. The discharge performance is monitored through an oscilloscope, which is connected to a high voltage probe and a current monitor. The physical and chemical properties of polymer surfaces before and after GDBD treatment were analyzed via water contact angle (CA) measurements, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) techniques.

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

    Science.gov (United States)

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

    2013-05-01

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

  17. Eradication of Bacterial Biofilms Using Atmospheric Pressure Non-Thermal Plasmas

    Science.gov (United States)

    Alkawareek, Mahmoud; Gilmore, Brendan; Gorman, Sean; Algwari, Qais; Graham, William; O'Connell, Deborah

    2011-10-01

    Bacterial biofilms are ubiquitous in natural and clinical settings and form a major health risk. Biofilms are recognised to be the predominant mode of bacterial growth, and are an immunological challenge compared to planktonic bacteria of the same species. Eradication of biofilms with atmospheric pressure plasma jets is investigated. Cold non-equilibrium plasmas, operated at ambient atmospheric pressure and temperature, are efficient sources for controlled energy transport through highly reactive neutrals (e.g. ROS, RNS), charged particles (ions and electrons), UV radiation, and electro-magnetic fields. A focused panel of clinically significant biofilms, including Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, and Bacillus cereus, are exposed to various plasma jet configurations operated in helium and oxygen mixtures. Viability of surviving cells was determined using both standard plate counting method and XTT viability assay. These are correlated with measurements and simulations of relevant reactive plasma species.

  18. ATMOSPHERIC PRESSURE AND ITS INFLUENCE ON TOURISTS AND TOURISM ACTIVITIES IN THE PRAHOVA CORRIDOR

    Directory of Open Access Journals (Sweden)

    HAVRIŞ LOREDANA-ELENA

    2014-03-01

    Full Text Available In the climate literature it is known that the atmospheric temperature directly and permanently acts on the all organisms and all geographical environment components, influencing the wellness of the weather sensitive persons and implicitly the wellness of tourists in this region. In the same time, its evolution is a good indicator in shaping the short and medium term meteorological forecast, considering that the region chosen for research is a very tripper one, especially during the winter season when the atmospheric pressure variation trend is much more pronounced. Within this framework, the present paper tries to develop a climatic diagnosis on the reference climate parameters (annual and monthly average pressure values, seasonal values, minimum and maximum absolute values and their emergence probability but also the non-periodic variability based on data recorded during 1961-2007 at Câmpina, Sinaia 1500, Predeal, Omu Peak and Braşov weather stations.

  19. Promoted cell and material interaction on atmospheric pressure plasma treated titanium

    Energy Technology Data Exchange (ETDEWEB)

    Han, Inho [Convergence Technology Exam. Div. II, Korean Intellectual Patent Office, Daejeon (Korea, Republic of); Vagaska, Barbora [Cellbiocontrol Laboratory, Department of Medical Engineering, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752 (Korea, Republic of); Seo, Hyok Jin [Cellbiocontrol Laboratory, Department of Medical Engineering, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752 (Korea, Republic of); Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752 (Korea, Republic of); Kang, Jae Kyeong [Cellbiocontrol Laboratory, Department of Medical Engineering, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752 (Korea, Republic of); Kwon, Byeong-Ju [Cellbiocontrol Laboratory, Department of Medical Engineering, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752 (Korea, Republic of); Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752 (Korea, Republic of); Lee, Mi Hee [Cellbiocontrol Laboratory, Department of Medical Engineering, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752 (Korea, Republic of); Park, Jong-Chul, E-mail: parkjc@yuhs.ac [Cellbiocontrol Laboratory, Department of Medical Engineering, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752 (Korea, Republic of); Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752 (Korea, Republic of)

    2012-03-01

    Surface carbon contamination is a natural phenomenon. However, it interferes with cell-biomaterial interaction. In order to eliminate the interference, atmospheric pressure plasma treatment was employed. Dielectric barrier discharge treatment of titanium surface for less than 10 min turned titanium super-hydrophilic. Adsorption of fibronectin which is the major cell adhesive protein increased after plasma treatment. Cell attachment parameters of osteoblast cells such as population, cell area, perimeter, Feret's diameter and cytoskeleton development were also enhanced. Cell proliferation increased on the plasma treated titanium. In conclusion, dielectric barrier discharge type atmospheric pressure plasma system is effective to modify titanium surface and the modified titanium promotes cell and material interactions.

  20. Modification of silicon carbide surfaces by atmospheric pressure plasma for composite applications.

    Science.gov (United States)

    Rodriguez-Santiago, Victor; Vargas-Gonzalez, Lionel; Bujanda, Andres A; Baeza, Jose A; Fleischman, Michelle S; Yim, Jacqueline H; Pappas, Daphne D

    2013-06-12

    In this study, we explore the use of atmospheric pressure plasmas for enhancing the adhesion of SiC surfaces using a urethane adhesive, as an alternative to grit-blasting. Surface analysis showed that He-O2 plasma treatments resulted in a hydrophilic surface mostly by producing SiOx. Four-point bending tests and bonding pull tests were carried out on control, grit-blasted, and plasma-treated surfaces. Grit-blasted samples showed enhanced bonding but also a decrease in flexural strength. Plasma treated samples did not affect the flexural strength of the material and showed an increase in bonding strength. These results suggest that atmospheric pressure plasma treatment of ceramic materials is an effective alternative to grit-blasting for adhesion enhancement. PMID:23639326

  1. Studies of velocity fluctuations in the lower atmosphere using the MU radar. I - Azimuthal anisotropy. II - Momentum fluxes and energy densities

    Science.gov (United States)

    Vanzandt, T. E.; Smith, S. A.; Tsuda, T.; Sato, T.; Fritts, D. C.

    1990-01-01

    Results are presented from a six-day campaign to observe velocity fluctuations in the lower atmosphere using the MU radar (Fukao et al., 1985) in Shigaraki, Japan in March, 1986. Consideration is given to the azimuthal anisotropy, the frequency spectra, the vertical profiles of energy density, and the momentum flux of the motion field. It is found that all of the observed azimuthal variations are probably caused by a gravity wave field whose parameters vary with time. The results show significant differences between the mean zonal and meridional frequency spectra and different profiles of mean energy density with height for different frequency bands and for zonal and meridional components.

  2. Using dimers to measure biosignatures and atmospheric pressure for terrestrial exoplanets.

    Science.gov (United States)

    Misra, Amit; Meadows, Victoria; Claire, Mark; Crisp, Dave

    2014-02-01

    We present a new method to probe atmospheric pressure on Earth-like planets using (O2-O2) dimers in the near-infrared. We also show that dimer features could be the most readily detectable biosignatures for Earth-like atmospheres and may even be detectable in transit transmission with the James Webb Space Telescope (JWST). The absorption by dimers changes more rapidly with pressure and density than that of monomers and can therefore provide additional information about atmospheric pressures. By comparing the absorption strengths of rotational and vibrational features to the absorption strengths of dimer features, we show that in some cases it may be possible to estimate the pressure at the reflecting surface of a planet. This method is demonstrated by using the O2 A band and the 1.06 μm dimer feature, either in transmission or reflected spectra. It works best for planets around M dwarfs with atmospheric pressures between 0.1 and 10 bar and for O2 volume mixing ratios above 50% of Earth's present-day level. Furthermore, unlike observations of Rayleigh scattering, this method can be used at wavelengths longer than 0.6 μm and is therefore potentially applicable, although challenging, to near-term planet characterization missions such as JWST. We also performed detectability studies for JWST transit transmission spectroscopy and found that the 1.06 and 1.27 μm dimer features could be detectable (SNR>3) for an Earth analogue orbiting an M5V star at a distance of 5 pc. The detection of these features could provide a constraint on the atmospheric pressure of an exoplanet and serve as biosignatures for oxygenic photosynthesis. We calculated the required signal-to-noise ratios to detect and characterize O2 monomer and dimer features in direct imaging-reflected spectra and found that signal-to-noise ratios greater than 10 at a spectral resolving power of R=100 would be required.

  3. Effect of Atmospheric Pressure Glow Discharge Treatment on Polymerization of Acrylic Fabric and Its Printing Behavior

    Directory of Open Access Journals (Sweden)

    D M El-Zeer

    2014-03-01

    Full Text Available Acrylic fibers have been treated by atmospheric pressure glow discharge (APGD plasma in open air to enhance surface antistatic properties. The treated surfaces are investigated by scanning electron microscopy (SEM, Fourier-Transition Infrared Spectroscopy (FTIR and Atomic Force Microscope (AFM. Plasma treatment of acrylic fabric has been found to increase the surface roughness, modify the nature and density of surface functionalities, and drastically improve the wettability and antistatic ability of acrylic fibers.

  4. Behavior of ZnO-coated alumina dielectric barrier discharge in atmospheric pressure air

    CERN Document Server

    Li, Meng; Tao, Xiaoping

    2011-01-01

    A complete investigation of the discharge behavior of dielectric barrier discharge device using ZnO-coated dielectric layer in atmospheric pressure is made. Highly conductive ZnO film was deposited on the dielectric surface. Discharge characteristic of the dielectric barrier discharge are examined in different aspects. Experimental result shows that discharge uniformity is improved definitely in the case of ZnO-coated dielectric barrier discharge. And relevant theoretical models and explanation are presented to describing its discharge physics.

  5. Characterization of a Dielectric Barrier Plasma Gun Discharging at Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    ZHANG Guang-Qiu; GE Yuan-Jing; ZHANG Yue-Fei; CHEN Guang-Liang

    2004-01-01

    @@ We develop a plasma gun based on dielectric barrier discharge and working at atmospheric pressure. A theoretical model to predict the gun discharge voltage is built, which is in agreement with the experimental results. After investigating the characterization of discharging gun and utilizing it for polymerization, we find that the gun can be used as a source to generate a stable uniform plasma for different plasma-processing technologies.

  6. The measurement of the electron temperature in a spark discharge in air at atmospheric pressure

    International Nuclear Information System (INIS)

    The electron temperature in atmospheric pressure spark surface discharge was measured from the relative intensity ratio using several well-resolved atomic N I, N II, O II lines. The evaluated value is of 18 000 K. The repeated sparks were glowed by a pulsed high voltage source which restricted the are phase of sparks by appropriate low value of capacitors in voltage multiplier. (Authors)

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

    OpenAIRE

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

    2010-01-01

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

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

    Science.gov (United States)

    Yang, Shujun; Tang, Jiansheng

    2013-10-01

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

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

    Science.gov (United States)

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

    2014-06-01

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

  10. Atomic Oxygen Cleaning Shown to Remove Organic Contaminants at Atmospheric Pressure

    Science.gov (United States)

    Rutledge, Sharon K.

    1998-01-01

    The NASA Lewis Research Center has developed and filed for a patent on a method to produce atomic oxygen at atmospheric pressure by using a direct current arc in a gas flow mixture of oxygen and helium. A prototype device has been tested for its ability to remove various soot residues from surfaces exposed to fire, and various varnishes such as acrylic and egg white.

  11. Concentric-Ring Patterns in a Helium Dielectric Barrier Discharge at Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    SHANG Wan-Li; WANG De-Zhen

    2007-01-01

    We perform the theoretical simulation of the concentric-ring patterns between two parallel electrodes covered with thin dielectric layers within the scope of a two-dimensional diffusion-drift model at atmospheric pressure. The time evolution of the discharge patterns is studied and the concentric-ring patterns with different radii shift alternately. The spatial-temporal evolution of electron density in a cycle at different time scales is performed.

  12. 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.

  13. Physical features of atmospheric pressure microdischarge system with vortex gas flows

    Directory of Open Access Journals (Sweden)

    Prysiazhnevych Iryna

    2014-11-01

    Full Text Available The parameters for microdischarges of plasma medicine in air and argon vortex flows at atmospheric pressure for different shapes of electrodes (outlet nozzle and axis electrode diameters ratio set have been investigated. The current-voltage characteristics of the designed systems have been analyzed, the parameters of the generated jets plasma have been investigated by means of the optical emission spectroscopy, and the form of plasma jets has been studied by using video camera.

  14. Novel Therapeutic Effects of Non-thermal atmospheric pressure plasma for Muscle Regeneration and Differentiation

    OpenAIRE

    Jae Won Choi; Sung Un Kang; Yang Eun Kim; Ju Kyeong Park; Sang Sik Yang; Yeon Soo Kim; Yun Sang Lee; Yuijina Lee; Chul-Ho Kim

    2016-01-01

    Skeletal muscle can repair muscle tissue damage, but significant loss of muscle tissue or its long-lasting chronic degeneration makes injured skeletal muscle tissue difficult to restore. It has been demonstrated that non-thermal atmospheric pressure plasma (NTP) can be used in many biological areas including regenerative medicine. Therefore, we determined whether NTP, as a non-contact biological external stimulator that generates biological catalyzers, can induce regeneration of injured muscl...

  15. Effect of Pressure Broadening on Molecular Absorption Cross Sections in Exoplanetary Atmospheres

    CERN Document Server

    Hedges, Christina

    2016-01-01

    Spectroscopic observations of exoplanets are leading to unprecedented constraints on their atmospheric compositions. However, molecular abundances derived from spectra are degenerate with the absorption cross sections which form critical input data in atmospheric models. Therefore, it is important to quantify the uncertainties in molecular cross sections to reliably estimate the uncertainties in derived molecular abundances. However, converting line lists into cross sections via line broadening involves a series of prescriptions for which the uncertainties are not well understood. We investigate and quantify the effects of various factors involved in line broadening in exoplanetary atmospheres - the profile evaluation width, pressure versus thermal broadening, broadening agent, spectral resolution, and completeness of broadening parameters - on molecular absorption cross sections. We use H$_2$O as a case study as it has the most complete absorption line data. For low resolution spectra (R$\\lesssim$100) for re...

  16. Pressure-dependent water absorption cross sections for exoplanets and other atmospheres

    CERN Document Server

    Barton, Emma J; Yurchenko, Sergei N; Tennyson, Jonathan; Dudaryonok, Anna S; Lavrentieva, Nina N

    2016-01-01

    Many atmospheres (cool stars, brown dwarfs, giant planets, extrasolar planets) are predominately composed of molecular hydrogen and helium. H$_2{}^{16}$O is one of the best measured molecules in extrasolar planetary atmospheres to date and a major compound in the atmospheres of brown-dwarfs and oxygen-rich cool stars, yet the scope of experimental and theoretical studies on the pressure broadening of water vapour lines by collision with hydrogen and helium remains limited. Theoretical H$_2$- and He-broadening parameters of water vapour lines (rotational quantum number $J$ up to 50) are obtained for temperatures in the range 300 - 2000 K. Two approaches for calculation of line widths were used: (i) the averaged energy difference method and (ii) the empirical expression for $J$\\p $J$\\pp-dependence. Voigt profiles based on these widths and the BT2 line list are used to generate high resolution ($\\Delta \\tilde{\

  17. Charge dependence of the plasma travel length in atmospheric-pressure plasma

    Science.gov (United States)

    Yambe, Kiyoyuki; Konda, Kohmei; Masuda, Seiya

    2016-06-01

    Plasma plume is generated using a quartz tube, helium gas, and foil electrode by applying AC high voltage under the atmosphere. The plasma plume is released into the atmosphere from inside of the quartz tube and is seen as the continuous movement of the plasma bullet. The travel length of plasma bullet is defined from plasma energy and force due to electric field. The drift velocity of plasma bullet has the upper limit under atmospheric-pressure because the drift velocity is determined from the balance between electric field and resistive force due to collisions between plasma and air. The plasma plume charge depends on the drift velocity. Consequently, in the laminar flow of helium gas flow state, the travel length of the plasma plume logarithmically depends on the plasma plume charge which changes with both the electric field and the resistive force.

  18. Development of superhydrophobic surface on glass substrate by multi-step atmospheric pressure plasma treatment

    Energy Technology Data Exchange (ETDEWEB)

    Han, Duksun [Department of Applied Plasma Engineering, Chonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju, Jeollabuk-do 561-756 (Korea, Republic of); Moon, Se Youn, E-mail: symoon@jbnu.ac.kr [Department of Applied Plasma Engineering, Chonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju, Jeollabuk-do 561-756 (Korea, Republic of); Department of Quantum system Engineering, Chonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju, Jeollabuk-do 561-756 (Korea, Republic of)

    2015-07-31

    Superhydrophobic surface was prepared on a glass by helium based CH{sub 4} and C{sub 4}F{sub 8} atmospheric pressure plasmas, and its water wettability was investigated by a water droplet contact angle method. The water droplet spread over on the untreated glasses that showed the initial hydrophilic property of the glass surface. Then, the static contact angles became about 85° and 98° after a single step CH{sub 4} plasma treatment and a single step C{sub 4}F{sub 8} plasma treatment, respectively. The contact angle was remarkably increased to 152°, indicating a superhydrophobic property, after a sequential multi-step CH{sub 4} and C{sub 4}F{sub 8} plasma treatment. From the X-ray photoelectron spectroscopy and the field emission scanning electron microscope measurements, it was found that the physical morphologies and the chemical compositions were depending on the substrate materials, which were important factors for the superhydrophobicity. - Highlights: • Development of rapid and simple method for superhydrophobic surface • Effects of atmospheric pressure plasma for superhydrophobic surface preparation • Observation of chemical and physical surface modification by atmospheric pressure plasma • Effects of substrate properties for plasma–surface interaction.

  19. Patterning of graphene for flexible electronics with remote atmospheric-pressure plasma using dielectric barrier

    Science.gov (United States)

    Kim, Duk Jae; Park, Jeongwon; Geon Han, Jeon

    2016-08-01

    We show results of the patterning of graphene layers on poly(ethylene terephthalate) (PET) films through remote atmospheric-pressure dielectric barrier discharge plasma. The size of plasma discharge electrodes was adjusted for large-area and role-to-role-type substrates. Optical emission spectroscopy (OES) was used to analyze the characteristics of charge species in atmospheric-pressure plasma. The OES emission intensity of the O2* peaks (248.8 and 259.3 nm) shows the highest value at the ratio of \\text{N}2:\\text{clean dry air (CDA)} = 100:1 due to the highest plasma discharge. The PET surface roughness and hydrophilic behavior were controlled with CDA flow rate during the process. Although the atmospheric-pressure plasma treatment of the PET film led to an increase in the FT-IR intensity of C–O bonding at 1240 cm‑1, the peak intensity at 1710 cm‑1 (C=O bonding) decreased. The patterning of graphene layers was confirmed by scanning electron microscopy and Raman spectroscopy.

  20. Efficacy of Atmospheric Pressure Plasma as an Antibacterial Agent Against Enterococcus Faecalis in Vitro

    Science.gov (United States)

    Cao, Yingguang; Yang, Ping; Lu, Xinpei; Xiong, Zilan; Ye, Tao; Xiong, Qing; Sun, Ziyong

    2011-02-01

    Enterococcus faecalis (E. faecalis) is a microorganism that can survive extreme challenges in obturated root canals. The aim of this study was to evaluate the efficacy of a non-thermal atmospheric pressure plasma plume against E. faecalis in vitro. A non-thermal atmospheric pressure plasma jet device which could generate a cold plasma plume carrying a peak current of 300 mA was used. The antibacterial efficacy of this device against E. faecalis and its biofilm under different conditions was detected. The antibacterial efficacy of the plasma against E. faecalis and Staphylococcus aureus (S. aureus) was also evaluated. After plasma treatment, the average diameter of inhibition zone on S. aureus and E. faecalis was 2.62±0.26 cm and 1.06±0.30 cm, respectively (P < 0.05). The diameter was increased with prolongation of the treatment duration. The diameters of inhibition zone of the sealed Petri dishes were larger than those of the uncovered Petri dishes. There was significant difference in colony-forming units between plasma group and control group on E. faecalis biofilm (P < 0.01). The transmission electron microscopy revealed that the ultrastructural changes cytoderm of E. faecalis were observed after treatment for 2 min. It is concluded that the non-thermal atmospheric pressure plasma could serve as an effective adjunct to standard endodontic microbial treatment.

  1. Sampling of ions at atmospheric pressure: ion transmission and ion energy studied by simulation and experiment

    Science.gov (United States)

    Große-Kreul, Simon; Hübner, Simon; Benedikt, Jan; von Keudell, Achim

    2016-04-01

    Mass spectrometry of ions from atmospheric pressure plasmas is a challenging diagnostic method that has been applied to a large variety of cold plasma sources in the past. However, absolute densities can usually not be obtained, moreover, the process of sampling of ions and neutrals from such a plasma inherently influences the measured composition. These issues are studied in this contribution by a combination of experimental and numerical methods. Different numerical domains are sequentially coupled to calculate the ion transmission from the source to the mass analyzer. It is found that the energy of the sampled ions created by a radio-frequency microplasma operated in a He-N2 mixture at atmospheric pressure is of the order of 0.1 eV and that it depends linearly on the ion mass in good agreement with the expectation for seeded particles accelerated in a supersonic expansion. Moreover, the measured ion energy distribution from an afterglow of an atmospheric pressure plasma can be reproduced on basis of the particle trajectories in the sampling system. Eventually, an estimation of the absolute flux of ions to the detector is deduced.

  2. Surface chemical changes of atmospheric pressure plasma treated rabbit fibres important for felting process

    Science.gov (United States)

    Štěpánová, Vlasta; Slavíček, Pavel; Stupavská, Monika; Jurmanová, Jana; Černák, Mirko

    2015-11-01

    We introduce the atmospheric pressure plasma treatment as a suitable procedure for in-line industrial application of rabbit fibres pre-treatment. Changes of rabbit fibre properties due to the plasma treatment were studied in order to develop new technology of plasma-based treatment before felting. Diffuse Coplanar Surface Barrier Discharge (DCSBD) in ambient air at atmospheric pressure was used for plasma treatment. Scanning electron microscopy was used for determination of the fibres morphology before and after plasma treatment. X-ray photoelectron spectroscopy and attenuated total reflectance-Fourier transform infrared spectroscopy were used for evaluation of reactive groups. The concentration of carbon decreased and conversely the concentration of nitrogen and oxygen increased after plasma treatment. Aging effect of plasma treated fibres was also investigated. Using Washburn method the significant increase of fibres wettability was observed after plasma treatment. New approach of pre-treatment of fibres before felting using plasma was developed. Plasma treatment of fibres at atmospheric pressure can replace the chemical method which consists of application of strong acids on fibres.

  3. Atmospheric pressure plasma enhanced chemical vapor deposition of zinc oxide and aluminum zinc oxide

    International Nuclear Information System (INIS)

    Zinc oxide (ZnO) and aluminum-doped zinc oxide (AZO) thin films were deposited via atmospheric pressure plasma enhanced chemical vapor deposition. A second-generation precursor, bis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)(N,N′-diethylethylenediamine) zinc, exhibited significant vapor pressure and good stability at one atmosphere where a vaporization temperature of 110 °C gave flux ∼ 7 μmol/min. Auger electron spectroscopy confirmed that addition of H2O to the carrier gas stream mitigated F contamination giving nearly 1:1 metal:oxide stoichiometries for both ZnO and AZO with little precursor-derived C contamination. ZnO and AZO thin film resistivities ranged from 14 to 28 Ω·cm for the former and 1.1 to 2.7 Ω·cm for the latter. - Highlights: • A second generation precursor was utilized for atmospheric pressure film growth. • Addition of water vapor to the carrier gas stream led to a marked reduction of ZnF2. • Carbonaceous contamination from the precursor was minimal

  4. Atmospheric pressure plasma jet with high-voltage power supply based on piezoelectric transformer

    International Nuclear Information System (INIS)

    The dielectric barrier discharge plasma jet, an example of the nonthermal atmospheric pressure plasma jet (APPJ), generates low-temperature plasmas that are suitable for the atomization of volatile species and can also be served as an ionization source for ambient mass and ion mobility spectrometry. A new design of APPJ for mass spectrometry has been built in our group. In these plasma sources magnetic transformers (MTs) and inductors are typically used in power supplies but they present several drawbacks that are even more evident when dealing with high-voltage normally used in APPJs. To overcome these disadvantages, high frequency generators with the absence of MT are proposed in the literature. However, in the case of miniaturized APPJs these conventional power converters, built of ferromagnetic cores and inductors or by means of LC resonant tank circuits, are not so useful as piezoelectric transformer (PT) based power converters due to bulky components and small efficiency. We made and examined a novel atmospheric pressure plasma jet with PT supplier served as ionization source for ambient mass spectrometry, and especially mobile spectrometry where miniaturization, integration of components, and clean plasma are required. The objective of this paper is to describe the concept, design, and implementation of this miniaturized piezoelectric transformer-based atmospheric pressure plasma jet

  5. An Experimental Study on Atmospheric Pressure Glow Discharge in Different Gases

    Institute of Scientific and Technical Information of China (English)

    刘鹏; 詹如娟; 等

    2002-01-01

    Usually,the electrical breakdown of dielectric barrier discharge(DBD) at atmospheric pressure leads to a filamentary non-homogeneous discharge,However,it is also possible to obtain a diffuse DBD in homogeneous form,called atmospheric pressure glow discharge(APGD).We obtained a uniform APGD in helium and in the mixture of argon with alcohol,and studied the electrical characteristics of helium APGD.It if found that the relationship between discharge current and source frequency is different depending on the difference in gas gap when the applied voltage is kept constant.The discharge current shows an increasing trend with the increased frequency when gas gap is 0.8cm ,but the discharge current tends to decrease with the increased frequency when the gas gap increases.The discharge current always increases with the increased applied voltage when the source frequency is kept constant.We also observed a glow-like discharge in nitrogen at atmospheric pressure.

  6. Non-thermal atmospheric-pressure plasma possible application in wound healing.

    Science.gov (United States)

    Haertel, Beate; von Woedtke, Thomas; Weltmann, Klaus-Dieter; Lindequist, Ulrike

    2014-11-01

    Non-thermal atmospheric-pressure plasma, also named cold plasma, is defined as a partly ionized gas. Therefore, it cannot be equated with plasma from blood; it is not biological in nature. Non-thermal atmospheric-pressure plasma is a new innovative approach in medicine not only for the treatment of wounds, but with a wide-range of other applications, as e.g. topical treatment of other skin diseases with microbial involvement or treatment of cancer diseases. This review emphasizes plasma effects on wound healing. Non-thermal atmospheric-pressure plasma can support wound healing by its antiseptic effects, by stimulation of proliferation and migration of wound relating skin cells, by activation or inhibition of integrin receptors on the cell surface or by its pro-angiogenic effect. We summarize the effects of plasma on eukaryotic cells, especially on keratinocytes in terms of viability, proliferation, DNA, adhesion molecules and angiogenesis together with the role of reactive oxygen species and other components of plasma. The outcome of first clinical trials regarding wound healing is pointed out.

  7. THE CONCEPT OF ATMOSPHERIC PRESSURE FROM THE PERSPECTIVE OF UNDERGRADUATE GEOGRAPHY STUDENTS: A PHENOMENOGRAPHIC STUDY

    Directory of Open Access Journals (Sweden)

    Fikret TUNA

    2013-08-01

    Full Text Available The main subject of this study is to determine the geography and geography education students’ perceptions of "atmospheric pressure" by the method of phenomenographic analysis. Total of 150 undergraduate geography students in Marmara University Faculty of Education and Faculty of Arts and Science were included in the study in the academic year 2011-2012. Of 150 students, 103 were male (68.67% and 47 were female (31.33%. Of these students, 57 were studying in the department of geography (38% and 93 (62% were geography education.In the study, a semi-structured questionnaire was used for data collection. In order to analyze the data, followings stages were conducted respectively: (1 coding and classification, (2 the creation of leading categories, (3 the creation of description categories and (4 creation of description map. As a result of the analysis of the data obtained, it was revealed that the students described atmospheric pressure in eight different categories and six different ways. Among the categories, the metaphor of "atmospheric pressure is the air force that is exerted on the earth" hasthe highest number of metaphors with total of 42 records (28%.

  8. Intracellular effects of atmospheric-pressure plasmas on melanoma cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Ishaq, M., E-mail: ishaqmusarat@gmail.com [Peter MacCallum Cancer Centre, East Melbourne, VIC 3002 (Australia); Comonwealth Scientific and Industrial Research Organization, Sydney, New South Wales (Australia); Bazaka, K. [Institute for Health and Biomedical Innovation, School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, QLD 4000 (Australia); Ostrikov, K. [Comonwealth Scientific and Industrial Research Organization, Sydney, New South Wales (Australia); Institute for Health and Biomedical Innovation, School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, QLD 4000 (Australia)

    2015-12-15

    Gas discharge plasmas formed at atmospheric pressure and near room temperature have recently been shown as a promising tool for cancer treatment. The mechanism of the plasma action is attributed to generation of reactive oxygen and nitrogen species, electric fields, charges, and photons. The relative importance of different modes of action of atmospheric-pressure plasmas depends on the process parameters and specific treatment objects. Hence, an in-depth understanding of biological mechanisms that underpin plasma-induced death in cancer cells is required to optimise plasma processing conditions. Here, the intracellular factors involved in the observed anti-cancer activity in melanoma Mel007 cells are studied, focusing on the effect of the plasma treatment dose on the expression of tumour suppressor protein TP73. Over-expression of TP73 causes cell growth arrest and/or apoptosis, and hence can potentially be targeted to enhance killing efficacy and selectivity of the plasma treatment. It is shown that the plasma treatment induces dose-dependent up-regulation of TP73 gene expression, resulting in significantly elevated levels of TP73 RNA and protein in plasma-treated melanoma cells. Silencing of TP73 expression by means of RNA interference inhibited the anticancer effects of the plasma, similar to the effect of caspase inhibitor z-VAD or ROS scavenger N-acetyl cysteine. These results confirm the role of TP73 protein in dose-dependent regulation of anticancer activity of atmospheric-pressure plasmas.

  9. Intracellular effects of atmospheric-pressure plasmas on melanoma cancer cells

    Science.gov (United States)

    Ishaq, M.; Bazaka, K.; Ostrikov, K.

    2015-12-01

    Gas discharge plasmas formed at atmospheric pressure and near room temperature have recently been shown as a promising tool for cancer treatment. The mechanism of the plasma action is attributed to generation of reactive oxygen and nitrogen species, electric fields, charges, and photons. The relative importance of different modes of action of atmospheric-pressure plasmas depends on the process parameters and specific treatment objects. Hence, an in-depth understanding of biological mechanisms that underpin plasma-induced death in cancer cells is required to optimise plasma processing conditions. Here, the intracellular factors involved in the observed anti-cancer activity in melanoma Mel007 cells are studied, focusing on the effect of the plasma treatment dose on the expression of tumour suppressor protein TP73. Over-expression of TP73 causes cell growth arrest and/or apoptosis, and hence can potentially be targeted to enhance killing efficacy and selectivity of the plasma treatment. It is shown that the plasma treatment induces dose-dependent up-regulation of TP73 gene expression, resulting in significantly elevated levels of TP73 RNA and protein in plasma-treated melanoma cells. Silencing of TP73 expression by means of RNA interference inhibited the anticancer effects of the plasma, similar to the effect of caspase inhibitor z-VAD or ROS scavenger N-acetyl cysteine. These results confirm the role of TP73 protein in dose-dependent regulation of anticancer activity of atmospheric-pressure plasmas.

  10. Efficacy of Atmospheric Pressure Plasma as an Antibacterial Agent Against Enterococcus Faecalis in Vitro

    International Nuclear Information System (INIS)

    Enterococcus faecalis (E. faecalis) is a microorganism that can survive extreme challenges in obturated root canals. The aim of this study was to evaluate the efficacy of a non-thermal atmospheric pressure plasma plume against E. faecalis in vitro. A non-thermal atmospheric pressure plasma jet device which could generate a cold plasma plume carrying a peak current of 300 mA was used. The antibacterial efficacy of this device against E. faecalis and its biofilm under different conditions was detected. The antibacterial efficacy of the plasma against E. faecalis and Staphylococcus aureus (S. aureus) was also evaluated. After plasma treatment, the average diameter of inhibition zone on S. aureus and E. faecalis was 2.62±0.26 cm and 1.06±0.30 cm, respectively (P < 0.05). The diameter was increased with prolongation of the treatment duration. The diameters of inhibition zone of the sealed Petri dishes were larger than those of the uncovered Petri dishes. There was significant difference in colony-forming units between plasma group and control group on E. faecalis biofilm (P < 0.01). The transmission electron microscopy revealed that the ultrastructural changes cytoderm of E. faecalis were observed after treatment for 2 min. It is concluded that the non-thermal atmospheric pressure plasma could serve as an effective adjunct to standard endodontic microbial treatment.

  11. Controlling hydrophilicity of polymer film by altering gas flow rate in atmospheric-pressure homogeneous plasma

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Controlling hydrophilicity of polymer film by varying gas flow rate is proposed in atmospheric-pressure homogeneous plasma treatment. • Without employing additional reactive gas, requiring more plasma power and longer treatment time, hydrophilicity of polyimide films was improved after the low-gas-flow plasma treatment. • The gas flow rate affects the hydrophilic properties of polymer surface by changing the discharge atmosphere in the particular geometry of the reactor developed. • Low-gas-flow induced wettability control suggests effective and economical plasma treatment. - Abstract: This paper reports on controlling the hydrophilicity of polyimide films using atmospheric-pressure homogeneous plasmas by changing only the gas flow rate. The gas flow changed the discharge atmosphere by mixing the feed gas with ambient air because of the particular geometry of the reactor developed for the study, and a low gas flow rate was found to be favorable because it generated abundant nitrogen or oxygen species that served as sources of hydrophilic functional groups over the polymer surface. After low-gas-flow plasma treatment, the polymer surface exhibited hydrophilic characteristics with increased surface roughness and enhanced chemical properties owing to the surface addition of functional groups. Without adding any reactive gases or requiring high plasma power and longer treatment time, the developed reactor with low-gas-flow operation offered effective and economical wettability control of polyimide films

  12. Where do winds come from? A new theory on how water vapor condensation influences atmospheric pressure and dynamics

    CERN Document Server

    Makarieva, A M; Sheil, D; Nobre, A D; Li, B -L

    2010-01-01

    Phase transitions of atmospheric water play a ubiquitous role in the Earth's climate system, but their direct impact on atmospheric dynamics has escaped wide attention. Here we examine and advance a theory as to how condensation influences atmospheric pressure through the mass removal of water from the gas phase with a simultaneous account of the latent heat release. Building from the fundamental physical principles we show that condensation is associated with a decline in air pressure in the lower atmosphere. This decline occurs up to a certain height, which ranges from 3 to 4 km for surface temperatures from 10 to 30 deg C. We then estimate the horizontal pressure differences associated with water vapor condensation and find that these are comparable in magnitude with the pressure differences driving observed circulation patterns. The water vapor delivered to the atmosphere via evaporation represents a store of potential energy available to accelerate air and thus drive winds. Our estimates suggest that the...

  13. Trunk muscle co-activation using functional electrical stimulation modifies center of pressure fluctuations during quiet sitting by increasing trunk stiffness

    OpenAIRE

    Milosevic, Matija; Masani, Kei; Wu, Noel; McConville, Kristiina M. V.; Popovic, Milos R.

    2015-01-01

    Background The purpose of this study was to examine the impact of functional electrical stimulation (FES) induced co-activation of trunk muscles during quiet sitting. We hypothesized that FES applied to the trunk muscles will increase trunk stiffness. The objectives of this study were to: 1) compare the center of pressure (COP) fluctuations during unsupported and FES-assisted quiet sitting - an experimental study and; 2) investigate how FES influences sitting balance - an analytical (simulati...

  14. Pressure Fluctuations on the Bed of Surge Tank at the H.P. Zimapan, Hgo., with Different Arrangements Studied on Hydraulic Model, with the Lowest Operation Conditions

    OpenAIRE

    H. Marengo–Mogollón; F.J. Ochoa–Álvarez; C. Cortés–Cortés

    2009-01-01

    In this paper, the pressure fluctuations of the surge tank in the Zimapan Hydroelectric Project are compared in a hydraulic model. The shaft is located lateral, over the conduction tunnel and in the simple form (permitting the tunnel entering the shaft), with and without orifice plates taking into account the demand and supply condition of energy with the minimum level of water of the conduction. It was determined the hydraulic efficiency and it was found that it was the best constructive opt...

  15. ANNEALING OF POLYCRYSTALLINE THIN FILM SILICON SOLAR CELLS IN WATER VAPOUR AT SUB-ATMOSPHERIC PRESSURES

    Directory of Open Access Journals (Sweden)

    Peter Pikna

    2014-10-01

    Full Text Available Thin film polycrystalline silicon (poly-Si solar cells were annealed in water vapour at pressures below atmospheric pressure. PN junction of the sample was contacted by measuring probes directly in the pressure chamber filled with steam during passivation. Suns-VOC method and a Lock-in detector were used to monitor an effect of water vapour to VOC of the solar cell during whole passivation process (in-situ. Tested temperature of the sample (55°C – 110°C was constant during the procedure. Open-circuit voltage of a solar cell at these temperatures is lower than at room temperature. Nevertheless, voltage response of the solar cell to the light flash used during Suns-VOC measurements was good observable. Temperature dependences for multicrystalline wafer-based and polycrystalline thin film solar cells were measured and compared. While no significant improvement of thin film poly-Si solar cell parameters by annealing in water vapour at under-atmospheric pressures was observed up to now, in-situ observation proved required sensitivity to changing VOC at elevated temperatures during the process.

  16. Hydrogen discharges operating at atmospheric pressure in a semiconductor gas discharge system

    Science.gov (United States)

    Aktas, K.; Acar, S.; Salamov, B. G.

    2011-08-01

    Analyses of physical processes which initiate electrical breakdown and spatial stabilization of current and control it with a photosensitive cathode in a semiconductor gas discharge system (SGDS) are carried out in a wide pressure range up to atmospheric pressure p, interelectrode distance d and diameter D of the electrode areas of the semiconductor cathode. The study compares the breakdown and stability curves of the gas discharge in the planar SGDS where the discharge gap is filled with hydrogen and air in two cases. The impact of the ionizing component of the discharge plasma on the control of the stable operation of the planar SGDS is also investigated at atmospheric pressure. The loss of stability is primarily due to modification of the semiconductor-cathode properties on the interaction with low-energy hydrogen ions and the formation of a space charge of positive ions in the discharge gap which changes the discharge from Townsend to glow type. The experimental results show that the discharge current in H2 is more stable than in air. The breakdown voltages are measured for H2 and air with parallel-plane electrodes, for pressures between 28 and 760 Torr. The effective secondary electron emission (SEE) coefficient is then determined from the breakdown voltage results and compared with the experimental results. The influence of the SEE coefficient is stated in terms of the differences between the experimental breakdown law.

  17. Hydrogen discharges operating at atmospheric pressure in a semiconductor gas discharge system

    Energy Technology Data Exchange (ETDEWEB)

    Aktas, K; Acar, S; Salamov, B G [Physics Department, Faculty of Arts and Sciences, Gazi University, 06500 Ankara (Turkey)

    2011-08-15

    Analyses of physical processes which initiate electrical breakdown and spatial stabilization of current and control it with a photosensitive cathode in a semiconductor gas discharge system (SGDS) are carried out in a wide pressure range up to atmospheric pressure p, interelectrode distance d and diameter D of the electrode areas of the semiconductor cathode. The study compares the breakdown and stability curves of the gas discharge in the planar SGDS where the discharge gap is filled with hydrogen and air in two cases. The impact of the ionizing component of the discharge plasma on the control of the stable operation of the planar SGDS is also investigated at atmospheric pressure. The loss of stability is primarily due to modification of the semiconductor-cathode properties on the interaction with low-energy hydrogen ions and the formation of a space charge of positive ions in the discharge gap which changes the discharge from Townsend to glow type. The experimental results show that the discharge current in H{sub 2} is more stable than in air. The breakdown voltages are measured for H{sub 2} and air with parallel-plane electrodes, for pressures between 28 and 760 Torr. The effective secondary electron emission (SEE) coefficient is then determined from the breakdown voltage results and compared with the experimental results. The influence of the SEE coefficient is stated in terms of the differences between the experimental breakdown law.

  18. An improved film evaporation correlation for saline water at sub-atmospheric pressures

    KAUST Repository

    Shahzada, Muhammad Wakil

    2011-10-03

    This paper presents an investigation of heat transfer correlation in a falling-film evaporator working with saline water at sub-atmospheric pressures. The experiments are conducted at different salinity levels ranging from 15000 to 90000 ppm, and the pressures were maintained between 0.92 to 2.81 kPa (corresponds to saturation temperatures of 5.9 – 23 0C). The effect of salinity, saturation pressures and chilled water temperatures on the heat transfer coefficient are accounted in the modified film evaporation correlations. The results are fitted to the Han & Fletcher\\'s and Chun & Seban\\'s falling-film correlations which are used in desalination industry. We modify the said correlations by adding salinity and saturation temperature corrections with respective indices to give a better agreement to our measured data.

  19. Pressure transducer used for measuring close-in shock waves of nuclear explosions in the atmosphere

    International Nuclear Information System (INIS)

    This paper introduces a variable reluctance pressure transducer. It has been successfully used for the measurement of close-in shock waves of nuclear explosions in the atmosphere. This transducer's highest pressure range is 100kg/cm2 and its response rise time for all ranges is lms. It uses a specially made oil-filled pressure which allows the transducer to be able to realize underground installation. In this way, it can endure the intense nuclear radiation of nuclear explosions without losing its fast speed response characteristics. This transducer has undergone a series of environmental tests and dynamic standardizations. Therefore, it was used to measure the complete waveform of shock wave overpressure in areas near the fire ball of nuclear explosions. This paper lists the test data of a group of nuclear explosion tests

  20. Meteorology in ruptured abdominal aortic aneurysm: an institutional study and a meta-analysis of published studies reporting atmospheric pressure.

    Science.gov (United States)

    Takagi, H; Watanabe, T; Mizuno, Y; Kawai, N; Umemoto, T

    2014-12-01

    The aim of this paper was to determine whether weather factors including atmospheric pressure are associated with the occurrence of ruptured abdominal aortic aneurysm (RAAA). We investigated our institutional experiences of RAAA in more than 150 patients during 8 years. Further, we performed a meta-analysis of published studies reporting the influence of atmospheric pressure on RAAA. We retrospectively evaluated 152 patients who underwent surgery for RAAA (including ruptured iliac arterial aneurysm) at our institute between 1 January 2006 and 31 December 2013. Daily regional meteorological data (in the nearest weather station located 3.5 km from the hospital) were obtained online from Japan Meteorological Agency. To identify comparative studies of mean atmospheric pressure on the day with RAAA versus that on the day without RAAA, MEDLINE and EMBASE were searched through January 2014 using Web-based search engines (PubMed and OVID). Mean sea level atmospheric pressure, delta mean atmospheric pressure (difference between mean sea level atmospheric pressure on the day and that on the previous day), and sunshine duration on the day with RAAA were significantly lower than those on the day without RAAA: 1012.43±7.44 versus 1013.71±6.49 hPa, P=0.039, -1.18±5.15 versus 0.05±5.62 hPa, P=0.005; and 4.76±3.76 versus 5.47±3.88 h, P=0.026; respectively. A pooled analysis of 8 studies (including our institutional study) demonstrated that mean atmospheric pressure on the day with RAAA was significantly lower than that on the day without RAAA: standardized mean difference, -0.09; 95% confidence interval, -0.14 to -0.04; P=0.0009. Atmospheric pressure on the day with RAAA appears lower than that on the day without RAAA. Atmospheric pressure may be associated with the occurrence of RAAA.

  1. Production of stable, non-thermal atmospheric pressure rf capacitive plasmas using gases other than helium or neon

    Science.gov (United States)

    Park, Jaeyoung; Henins, Ivars

    2005-06-21

    The present invention enables the production of stable, steady state, non-thermal atmospheric pressure rf capacitive .alpha.-mode plasmas using gases other than helium and neon. In particular, the current invention generates and maintains stable, steady-state, non-thermal atmospheric pressure rf .alpha.-mode plasmas using pure argon or argon with reactive gas mixtures, pure oxygen or air. By replacing rare and expensive helium with more readily available gases, this invention makes it more economical to use atmospheric pressure rf .alpha.-mode plasmas for various materials processing applications.

  2. Airborne Lidar Measurements of Atmospheric Pressure Made Using the Oxygen A-Band

    Science.gov (United States)

    Riris, Haris; Rodriquez, Michael D.; Allan, Graham R.; Hasselbrack, William E.; Mao, Jianping; Stephen, Mark A.; Abshire, James B.

    2012-01-01

    Accurate measurements of greenhouse gas mixing ratios on a global scale are currently needed to gain a better understanding of climate change and its possible impact on our planet. In order to remotely measure greenhouse gas concentrations in the atmosphere with regard to dry air, the air number density in the atmosphere is also needed in deriving the greenhouse gas concentrations. Since oxygen is stable and uniformly mixed in the atmosphere at 20.95%, the measurement of an oxygen absorption in the atmosphere can be used to infer the dry air density and used to calculate the dry air mixing ratio of a greenhouse gas, such as carbon dioxide or methane. OUT technique of measuring Oxygen uses integrated path differential absorption (IPDA) with an Erbium Doped Fiber Amplifier (EDF A) laser system and single photon counting module (SPCM). It measures the absorbance of several on- and off-line wavelengths tuned to an O2 absorption line in the A-band at 764.7 nm. The choice of wavelengths allows us to maximize the pressure sensitivity using the trough between two absorptions in the Oxygen A-band. Our retrieval algorithm uses ancillary meteorological and aircraft altitude information to fit the experimentally obtained lidar O2 line shapes to a model atmosphere and derives the pressure from the profiles of the two lines. We have demonstrated O2 measurements from the ground and from an airborne platform. In this paper we will report on our airborne measurements during our 2011 campaign for the ASCENDS program.

  3. Atmospheric pressure plasma CVD as a tool to functionalise wound dressings.

    Science.gov (United States)

    Spange, Sebastian; Pfuch, Andreas; Wiegand, Cornelia; Beier, Oliver; Hipler, Uta C; Grünler, Bernd

    2015-02-01

    The main goal of this investigation was the preparation of an antibacterial layer system for additional modification of wound dressings with atmospheric plasma. Furthermore, the modified wound dressings were checked on there bactericidal and cytotoxic activity. The layer system was applied by using a novel atmospheric pressure plasma chemical vapour deposition technique on a variety of textile substrates which are suitable as wound dressing materials. The layer system composed of silicon dioxide with in situ generated embedded silver nanoparticles. The bactericidal activity of the produced wound dressings was investigated against different bacteria like Staphylococcus aureus and Klebsiella pneumoniae while the cytotoxic potential of the coated wound dressings was verified using human keratinocytes. Even at low concentrations of silver precursor a strong antibacterial effect was observed in direct contact with S. aureus and K. pneumoniae. Furthermore, extractions produced from the coated textiles showed a good antibacterial effect. By means of optimised coating parameters a therapeutic window for those wound dressings could be identified. Consequently, the atmospheric pressure plasma chemical vapour deposition technique promise an effective and low cost modification of wound dressing materials.

  4. The habitable zone of Earth-like planets with different levels of atmospheric pressure

    CERN Document Server

    Vladilo, Giovanni; Silva, Laura; Provenzale, Antonello; Ferri, Gaia; Ragazzini, Gregorio

    2013-01-01

    As a contribution to the study of the habitability of extrasolar planets, we implemented a 1-D Energy Balance Model (EBM), the simplest seasonal model of planetary climate, with new prescriptions for most physical quantities. Here we apply our EBM to investigate the surface habitability of planets with an Earth-like atmospheric composition but different levels of surface pressure. The habitability, defined as the mean fraction of the planet's surface on which liquid water could exist, is estimated from the pressure-dependent liquid water temperature range, taking into account seasonal and latitudinal variations of surface temperature. By running several thousands of EBM simulations we generated a map of the habitable zone (HZ) in the plane of the orbital semi-major axis, a, and surface pressure, p, for planets in circular orbits around a Sun-like star. As pressure increases, the HZ becomes broader, with an increase of 0.25 AU in its radial extent from p=1/3 bar to p=3 bar. At low pressure, the habitability is...

  5. Variations in atmospheric pressure as a source of errors in polychromatic X-ray experiments

    CERN Document Server

    Matjushin, A M

    2000-01-01

    The influence of the atmospheric pressure on the accuracy of energy diffractometry (ED), X-ray fluorescence analysis (XRF) using a semiconductor Si(Li) detector, polychromatic diffractometry without the energy dispersion (PDWED) using a coordinate detector has been considered. It is shown that in the interval of pressures 710-810 mm Hg, errors in the determination of interplanar spaces can reach 2% for PDWED, which is caused by the displacement of the maximum of spectral distribution due to changes in absorption by air gaps of the device, and by changes in the quantum efficiency of the coordinate detector. In the ED and XRF methods, changes in the spectrum lead to errors in the determination of relative intensities of diffraction and fluorescence peaks, respectively. The changes in integral intensity are about 1% and can be neglected in the majority of experiments. The curves of the displacement of the spectral distribution maximum and spectral changes were calculated as a function of the atmospheric pressure...

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

    Science.gov (United States)

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

    2007-07-01

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

  7. Growth of carbon nanowalls at atmospheric pressure for one-step gas sensor fabrication

    Directory of Open Access Journals (Sweden)

    Zhu Yanwu

    2011-01-01

    Full Text Available Abstract Carbon nanowalls (CNWs, two-dimensional "graphitic" platelets that are typically oriented vertically on a substrate, can exhibit similar properties as graphene. Growth of CNWs reported to date was exclusively carried out at a low pressure. Here, we report on the synthesis of CNWs at atmosphere pressure using "direct current plasma-enhanced chemical vapor deposition" by taking advantage of the high electric field generated in a pin-plate dc glow discharge. CNWs were grown on silicon, stainless steel, and copper substrates without deliberate introduction of catalysts. The as-grown CNW material was mainly mono- and few-layer graphene having patches of O-containing functional groups. However, Raman and X-ray photoelectron spectroscopies confirmed that most of the oxygen groups could be removed by thermal annealing. A gas-sensing device based on such CNWs was fabricated on metal electrodes through direct growth. The sensor responded to relatively low concentrations of NO2 (g and NH3 (g, thus suggesting high-quality CNWs that are useful for room temperature gas sensors. PACS: Graphene (81.05.ue, Chemical vapor deposition (81.15.Gh, Gas sensors (07.07.Df, Atmospheric pressure (92.60.hv

  8. Constraints on early Mars atmospheric pressure inferred from small ancient craters

    CERN Document Server

    Kite, Edwin S; Lucas, Antoine; Aharonson, Oded

    2013-01-01

    The single most important control on long-term climate change on Mars is thought to be decay of the CO2-dominated atmosphere, but direct constraints on paleoatmospheric pressure P are lacking. Of particular interest is the climate that allowed rivers to flow early in Mars history, which was affected by P via direct and indirect greenhouse effects. The size of craters embedded within ancient layered sediments is a proxy for P: the smaller the minimum-sized craters that form, the thinner the past atmosphere. Here we use high-resolution orthophotos and Digital Terrain Models (DTMs) to identify ancient craters among the river deposits of Aeolis, and compare their sizes to models of atmospheric filtering of impactors by thicker atmospheres. The best fit is P <= 760+/-70 mbar, rising to P <= 1640+/-180 mbar if rimmed circular mesas are excluded. Surveys tend to undercount smaller craters, so these fits are upper limits. Our work assumes target properties appropriate for desert alluvium: if sediment developed ...

  9. Correlation between helium atmospheric pressure plasma jet (APPJ) variables and plasma induced DNA damage

    Science.gov (United States)

    Adhikari, Ek R.; Ptasinska, Sylwia

    2016-09-01

    A helium atmospheric pressure plasma jet (APPJ) source with a dielectric capillary and two tubular electrodes was used to induce damage in aqueous plasmid DNA. The fraction of different types of DNA damage (i.e., intact or undamaged, double strand breaks (DSBs), and single strand breaks (SSBs)) that occurred as the result of plasma irradiation was quantified through analysis of agarose gel electrophoresis images. The total DNA damage increased with an increase in both flow rate and duration of irradiation, but decreased with an increase in distance between the APPJ and sample. The average power of the plasma was calculated and the length of APPJ was measured for various flow rates and voltages applied. The possible effects of plasma power and reactive species on DNA damage are discussed. Contribution to the Topical Issue "Low-Energy Interactions related to Atmospheric and Extreme Conditions", edited by S. Ptasinska, M. Smialek-Telega, A. Milosavljevic, B. Sivaraman.

  10. Atmospheric Radiocarbon Calibration to 45,000 yr B.P. : Late Glacial Fluctuations and Cosmogenic Isotope Production

    NARCIS (Netherlands)

    Kitagawa, H.; Plicht, J. van der

    1998-01-01

    More than 250 carbon-14 accelerator mass spectrometry dates of terrestrial macrofossils from annually laminated sediments from Lake Suigetsu (Japan) provide a first atmospheric calibration for almost the total range of the radiocarbon method (45,000 years before the present). The results confirm the

  11. Reactive species in non-equilibrium atmospheric-pressure plasmas: Generation, transport, and biological effects

    Science.gov (United States)

    Lu, X.; Naidis, G. V.; Laroussi, M.; Reuter, S.; Graves, D. B.; Ostrikov, K.

    2016-05-01

    Non-equilibrium atmospheric-pressure plasmas have recently become a topical area of research owing to their diverse applications in health care and medicine, environmental remediation and pollution control, materials processing, electrochemistry, nanotechnology and other fields. This review focuses on the reactive electrons and ionic, atomic, molecular, and radical species that are produced in these plasmas and then transported from the point of generation to the point of interaction with the material, medium, living cells or tissues being processed. The most important mechanisms of generation and transport of the key species in the plasmas of atmospheric-pressure plasma jets and other non-equilibrium atmospheric-pressure plasmas are introduced and examined from the viewpoint of their applications in plasma hygiene and medicine and other relevant fields. Sophisticated high-precision, time-resolved plasma diagnostics approaches and techniques are presented and their applications to monitor the reactive species and plasma dynamics in the plasma jets and other discharges, both in the gas phase and during the plasma interaction with liquid media, are critically reviewed. The large amount of experimental data is supported by the theoretical models of reactive species generation and transport in the plasmas, surrounding gaseous environments, and plasma interaction with liquid media. These models are presented and their limitations are discussed. Special attention is paid to biological effects of the plasma-generated reactive oxygen and nitrogen (and some other) species in basic biological processes such as cell metabolism, proliferation, survival, etc. as well as plasma applications in bacterial inactivation, wound healing, cancer treatment and some others. Challenges and opportunities for theoretical and experimental research are discussed and the authors' vision for the emerging convergence trends across several disciplines and application domains is presented to

  12. Influence of atmospheric pressure plasma treatment on surface properties of PBO fiber

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Ruiyun; Pan Xianlin [Key Laboratory of Textile Science and Technology, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China); Jiang Muwen [Key Laboratory of Science and Technology of Eco-Textile, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China); Peng Shujing [Key Laboratory of Textile Science and Technology, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China); Qiu Yiping, E-mail: ypqiu@dhu.edu.cn [Key Laboratory of Science and Technology of Eco-Textile, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer PBO fibers were treated with atmospheric pressure plasmas. Black-Right-Pointing-Pointer When 1% of oxygen was added to the plasma, IFSS increased 130%. Black-Right-Pointing-Pointer Increased moisture regain could enhance plasma treatment effect on improving IFSS with long treatment time. - Abstract: In order to improve the interfacial adhesion property between PBO fiber and epoxy, the surface modification effects of PBO fiber treated by atmospheric pressure plasma jet (APPJ) in different time, atmosphere and moisture regain (MR) were investigated. The fiber surface morphology, functional groups, surface wettability for control and plasma treated samples were analyzed by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle measurements, respectively. Meanwhile, the fiber interfacial shear strength (IFSS), representing adhesion property in epoxy, was tested using micro-bond pull-out test, and single fiber tensile strength was also tested to evaluate the mechanical performance loss of fibers caused by plasma treatment. The results indicated that the fiber surface was etched during the plasma treatments, the fiber surface wettability and the IFSS between fiber and epoxy had much improvement due to the increasing of surface energy after plasma treatment, the contact angle decreased with the treatment time increasing, and the IFSS was improved by about 130%. The processing atmosphere could influence IFSS significantly, and moisture regains (MR) of fibers also played a positive role on improving IFSS but not so markedly. XPS analysis showed that the oxygen content on fiber surface increased after treatment, and C=O, O-C=O groups were introduced on fiber surface. On the other hand, the observed loss of fiber tensile strength caused by plasma treatment was not so remarkable to affect the overall performance of composite materials.

  13. Influence of atmospheric pressure plasma treatment on surface properties of PBO fiber

    International Nuclear Information System (INIS)

    Highlights: ► PBO fibers were treated with atmospheric pressure plasmas. ► When 1% of oxygen was added to the plasma, IFSS increased 130%. ► Increased moisture regain could enhance plasma treatment effect on improving IFSS with long treatment time. - Abstract: In order to improve the interfacial adhesion property between PBO fiber and epoxy, the surface modification effects of PBO fiber treated by atmospheric pressure plasma jet (APPJ) in different time, atmosphere and moisture regain (MR) were investigated. The fiber surface morphology, functional groups, surface wettability for control and plasma treated samples were analyzed by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle measurements, respectively. Meanwhile, the fiber interfacial shear strength (IFSS), representing adhesion property in epoxy, was tested using micro-bond pull-out test, and single fiber tensile strength was also tested to evaluate the mechanical performance loss of fibers caused by plasma treatment. The results indicated that the fiber surface was etched during the plasma treatments, the fiber surface wettability and the IFSS between fiber and epoxy had much improvement due to the increasing of surface energy after plasma treatment, the contact angle decreased with the treatment time increasing, and the IFSS was improved by about 130%. The processing atmosphere could influence IFSS significantly, and moisture regains (MR) of fibers also played a positive role on improving IFSS but not so markedly. XPS analysis showed that the oxygen content on fiber surface increased after treatment, and C=O, O-C=O groups were introduced on fiber surface. On the other hand, the observed loss of fiber tensile strength caused by plasma treatment was not so remarkable to affect the overall performance of composite materials.

  14. Rapid inactivation of Penicillium digitatum spores using high-density nonequilibrium atmospheric pressure plasma

    Science.gov (United States)

    Iseki, Sachiko; Ohta, Takayuki; Aomatsu, Akiyoshi; Ito, Masafumi; Kano, Hiroyuki; Higashijima, Yasuhiro; Hori, Masaru

    2010-04-01

    A promising, environmentally safe method for inactivating fungal spores of Penicillium digitatum, a difficult-to-inactivate food spoilage microorganism, was developed using a high-density nonequilibrium atmospheric pressure plasma (NEAPP). The NEAPP employing Ar gas had a high electron density on the order of 1015 cm-3. The spores were successfully and rapidly inactivated using the NEAPP, with a decimal reduction time in spores (D value) of 1.7 min. The contributions of ozone and UV radiation on the inactivation of the spores were evaluated and concluded to be not dominant, which was fundamentally different from the conventional sterilizations.

  15. Bacterial inactivation using atmospheric pressure single pin electrode microplasma jet with a ground ring

    Science.gov (United States)

    Kim, Sun Ja; Chung, T. H.; Bae, S. H.; Leem, S. H.

    2009-04-01

    Bacterial inactivation experiment was performed using atmospheric pressure microplasma jets driven by radio-frequency wave of 13.56 MHz and by low frequency wave of several kilohertz. With addition of a ground ring electrode, the discharge current, the optical emission intensities from reactive radicals, and the sterilization efficiency were enhanced significantly. When oxygen gas was added to helium at the flow rate of 5 SCCM, the sterilization efficiency was enhanced. From the survival curve of Escherichia coli, the primary role in the inactivation was played by reactive species with minor aid from heat, UV photons, charged particles, and electric fields.

  16. Genetic effects of radio-frequency, atmospheric-pressure glow discharges with helium

    Science.gov (United States)

    Li, Guo; Li, He-Ping; Wang, Li-Yan; Wang, Sen; Zhao, Hong-Xin; Sun, Wen-Ting; Xing, Xin-Hui; Bao, Cheng-Yu

    2008-06-01

    Due to low gas temperatures and high densities of active species, atmospheric-pressure glow discharges (APGDs) would have potential applications in the fields of plasma-based sterilization, gene mutation, etc. In this letter, the genetic effects of helium radio-frequency APGD plasmas with the plasmid DNA and oligonucleotide as the treated biomaterials are presented. The experimental results show that it is the chemically active species, instead of heat, ultraviolet radiation, intense electric field, and/or charged particles, that break the double chains of the plasmid DNA. The genetic effects depend on the plasma operating parameters, e.g., power input, helium flow rate, processing distance, time, etc.

  17. Time-resolved mass spectroscopic studies of an atmospheric-pressure helium microplasma jet

    OpenAIRE

    Oh, Jun-Seok; Aranda-Gonzalvo, Yolanda; James W. Bradley

    2011-01-01

    Abstract Using molecular beam mass spectroscopy, time-resolved measurements of the ionic species 12 in the plasma plume of an atmospheric-pressure helium microplasma jet have been made for 13 a range of excitation frequencies (5, 10 and 25 kHz) and source-instruments orifice distances 14 (1, 7 and 11 mm). Ionic species can only be observed in the visible plasma plume, with the 15 main positive species being N 2 + (65.26%) and O 2 + (21.11%), and few percentages of N +, O +, 16 NO + and He ...

  18. Plasma Disinfection and the Deterioration of Surgical Tools at Atmospheric Pressure Plasma

    Science.gov (United States)

    Zaaba, Siti Khadijah; Akitsu, Tetsuya; Ohkawa, Hiroshi; Katayama-Hirayama, Keiko; Tsuji, Masao; Shimizu, Naohiro; Imanishi, Yuichirou

    The purpose of this paper is to present and compare disinfection effect of plasma by means of Atmospheric Pressure Glow plasma and streamer discharge. Geobacillus stearothermophilus was used as biological indicator for disinfection process. The effect of blades after irradiated in plasma was also studied by SEM analysis. It was found that the disinfection process was effective when the cylindrical configuration was applied. Carbon steel blade was also found to be deteriorated after immersed in plasma irradiation. Results indicate that disinfection can be achieved and at the same time deteriorations of the tools were observed.

  19. Supercontinuum Generation in Atmospheric-Pressure Nitrogen Using a Tightly Focused Intense Femtosecond Laser Beam

    Institute of Scientific and Technical Information of China (English)

    QIN Yuan-Dong; ZHU Chang-Jun; YANG Hong; GONG Qi-Huang

    2000-01-01

    Supercontinuum generation in atmospheric-pressure nitrogen by a focused intense femtosecond Ti: sapphire laser was studied at various pulse durations and energies. The generated supercontinuum was greatly blue-broadened due to self-phase modulation in the plasma produced. The measured blue-broadening △ω is proportional to pulse intensity for fixed pulse duration, and values up to 0. 7ω (ω being the originaI laser frequency) was obtained with a pulse energy of 9.5 mJ and minimum duration of 100 fs.

  20. Theoretical Computation for Non-Equilibrium Air Plasma Electrical Conductivity at Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    HAN Dong; GUO Wen-Kang; XU Ping; LIANG Rong-Qing

    2007-01-01

    @@ Based on the Chapman-Enskog theory, we calculate the electrical conductivity of non-equilibrium air plasma in the two-temperature model. We consider different degrees of non-equilibrium, which is defined by the ratio of electronic temperature to heavy particles temperature. The method of computing the composition of air plasma is demonstrated. After calculating the electrical conductivity from electron temperature 1000 K to 15000K, the present result is compared with Murphy's study [Plasma Chem. Plasma Process 15 (1994) 279] for equilibrium case. All the calculation is completed at atmospheric pressure. The present results may have potential applications in numerical calculation of non-equilibrium air plasma.