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. 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.

  4. Pressure fluctuations in swirling turbulent flows

    OpenAIRE

    Fauve, S.; Laroche, C; Castaing, B.

    1993-01-01

    We report measurements of pressure fluctuations in swirling turbulent flows generated in the gap between two rotating coaxial disks. We relate the pressure spectra to the observed flow regimes in the case of co-rotating and counter-rotating disks. In the latter case, we show that the pressure probability density function is strongly non-Gaussian and displays an exponential tail toward low pressures which might be ascribed to intermittent vorticity concentrated on tube-like structures. Similar...

  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. Fluctuation Pressure Assisted Ejection of DNA From Bacteriophage

    Science.gov (United States)

    Harrison, Michael J.

    2011-03-01

    The role of thermal pressure fluctuations excited within tightly packaged DNA while it is ejected 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 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 pressures on the capsid from thermal excitation of longitudinal acoustic vibrations in the bundle whose wavelengths are exceeded by the bend persistence length may have root-mean-square values that 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.

  7. Fluctuation Theorem in an Atmospheric Circulation Model

    CERN Document Server

    Schalge, Bernd; Wouters, Jeroen; Fraedrich, Klaus; Lunkeit, Frank

    2012-01-01

    Evidence for the validity of the Fluctuation Theorem (FT) in an atmospheric Global Circulation Model is found. The model is hydrostatic with variable numbers of vertical levels and different horizontal resolutions. For finite time intervals the largest local Lyapunov exponent (LLLE) is found to be negative consistent with predictions of the FT. The effect is present for resolutions up to wave numbers l=42 (~ 250km) and 10 levels.

  8. 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...

  9. 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

  10. 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.

  11. Microplasma jet at atmospheric pressure

    International Nuclear Information System (INIS)

    A nitrogen microplasma jet operated at atmospheric pressure was developed for treating thermally sensitive materials. For example, the plasma sources in treatment of vulnerable biological materials must operate near the room temperature at the atmospheric pressure, without any risk of arcing or electrical shock. The microplasma jet device operated by an electrical power less than 10 W exhibited a long plasma jet of about 6.5 cm with temperature near 300 K, not causing any harm to human skin. Optical emission measured at the wide range of 280-800 nm indicated various reactive species produced by the plasma jet

  12. 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.

  13. 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 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.

  14. 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.

  15. 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.

  16. 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.

  17. Fluctuations of Quantum Radiation Pressure in Dissipative Fluid

    CERN Document Server

    Wu, C H; Wu, Chun-Hsien; Lee, Da-Shin

    2003-01-01

    Using the generalized Langevin equations involving the stress tensor approach, quantum fluctuations of electromagnetic radiation pressure in the presence of a dissipative environment have been studied. We consider a perfectly reflecting mirror which is exposed to the electromagnetic radiation pressure in a fluid at finite temperature. The dynamics of velocity fluctuations of the mirror is studied analytically in both small time and large time limits. In the small time limit, the minimum uncertainty of the mirror's position measurement from both quantum and thermal noises effects including the photon counting error in the laser interferometer is obtained based on the fluctuation-dissipation theorem as compared with the ''standard quantum limit''. In addition, the result of the large time behavior of fluctuations of the mirror's velocity in a dissipative environment can be applied to the laser interferometer of the ground-based gravitational wave detector. The role of the dissipative effects in this case is pla...

  18. Transition in fluctuation behaviour of normal liquids under high pressures

    Science.gov (United States)

    Postnikov, Eugene B.; Chora&¸zdot; ewski, Mirosław

    2016-05-01

    We explore the behaviour of the inverse reduced density fluctuations and the isobaric expansion coefficient using α , ω-dibromoalkanes as an example. Two different states are revealed far from the critical point: the region of exponentially decaying fluctuations near the coexistence curve and the state with longer correlations under sufficiently high pressures. The crossing of the isotherms of the isobaric expansion coefficient occurs within the PVT range of the mentioned transition. We discuss the interplay of this crossing with the changes in molecular packing structure connected with the analysed function of the density, which represents inverse reduced volume fluctuations.

  19. 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.

  20. 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.

  1. Fluctuation Pressure of a Membrane Between Walls Through Five Loops

    OpenAIRE

    Kastening, Boris

    2002-01-01

    An earlier four-loop calculation of the fluctuation pressure of a fluid membrane between two infinite walls is extended to five loops. Variational perturbation theory is used to extract the hard-wall limit from perturbative results obtained with a smooth potential. Comparison with a structurally similar quantum mechanics problem of a particle in a box is used for an alternative way of extracting the membrane pressure and also to estimate the quality of the results. Our values lie above the be...

  2. 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.

  3. 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

  4. 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)

  5. 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.

  6. Detrended fluctuation analysis of a systolic blood pressure control loop

    Energy Technology Data Exchange (ETDEWEB)

    Galhardo, C E C; Penna, T J P; Argollo de Menezes, M [Instituto de Fisica, Universidade Federal Fluminense, Av. Litoranea, s/n, 24210-340, Niteroi, RJ (Brazil); Soares, P P S [Instituto Biomedico, Universidade Federal Fluminense, R. Prof. Hernani Melo n. 101, 24210-130, Niteroi, RJ (Brazil)], E-mail: marcio@mail.if.uff.br

    2009-10-15

    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 evidence 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.

  7. 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.

  8. 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)

  9. 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...

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

    International Nuclear Information System (INIS)

    Gas liquid inter 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 it 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. Experiments with and without non-condensable gas, air were conducted. The significant temperature fluctuation was not observed in air-water system and air-vapor-water system. The temperature fluctuation was observed in vapor-water system. Visualization was carried out at the horizontal part of the spray pipe. No interface movement was observed but vortices in the liquid layer near the interface were observed without non-condensable gas. It was estimated that Kelvin-Helmholtz instabilities occurred in the liquid layer near the interface. (author)

  11. 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)

  12. Low Temperature Atmospheric Pressure Plasma Sterilization Shower

    Science.gov (United States)

    Gandhiraman, R. P.; Beeler, D.; Meyyappan, M.; Khare, B. N.

    2012-10-01

    Low-temperature atmospheric pressure plasma sterilization shower to address both forward and backward biological contamination issues is presented. The molecular effects of plasma exposure required to sterilize microorganisms is also analysed.

  13. Computational investigations of atmospheric pressure discharges

    OpenAIRE

    Iqbal, Muhammad Munawar

    2010-01-01

    This research work presents the numerical simulations of multispecies multi-dimensional fluid model of atmospheric pressure discharge. The semi-implicit sequential iterative scheme is used to solve the coupled system of plasma fluid model equations with a proper set of boundary conditions. A one- dimensional self consistent drift-diffusion fluid model is developed to investigate the characteristics of atmospheric pressure discharge in pure helium and He-N2 gases. The uniform atmos...

  14. 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

  15. 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.

  16. 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...

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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

  2. 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.

  3. Standard deviation of absolute and differential pressure fluctuations in fluidized beds of group B particles

    OpenAIRE

    Sobrino, Celia; Sánchez-Delgado, Sergio; García-Hernando, Néstor; Vega, Mercedes

    2008-01-01

    This work describes the behaviour of the standard deviation of pressure fluctuations in fluidized beds for group B particles in the bubbling regime. An empirical–theoretical function, which depends on the gas velocity, is proposed for predicting the pressure signal fluctuations, and the corresponding values of are calculated. The differences in the standard deviation of pressure fluctuations obtained for absolute or differential sensors are analyzed and compared to experimental values corresp...

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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 de...

  9. Formation Mechanism of Atmospheric Pressure Plasma Jet

    CERN Document Server

    Jiang, Nan; Cao, Zexian

    2008-01-01

    Atmospheric pressure plasma jet can protrude some 5.0 cm into air. It holds promise for multivarious innovative applications, but its formation mechanism remains unsettled. We show that the plasma jet is essentially a streamer corona totally independent of, but obscured by, dielectric barrier discharge. Consequently, the jets can be equally successfully generated even with one single bare metal electrode attached to the tube orifice, both downstream and upstream simultaneously, and at a significantly reduced voltage. These results will help understand the underlying physics and facilitate a safer and more flexible implementation of this marvelous plasma source.

  10. 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...

  11. 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.

  12. 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.

  13. Synoptic-scale fluctuations of total ozone in the atmosphere

    OpenAIRE

    Galliani, A.; Siani, A. M.; Muthama, N. J.; Palmieri, S

    1996-01-01

    A model, based on ozone-concentration tendency equation, is developed to study synoptic ozone-column variations. The application is referred to a middle-latitude site and to an atmospheric layer extending from the surface up to about 35-km altitude. Photochemical effects at the considered location for synoptic time scales are considered negligible. The data input consists of umkehr ozone profile, total ozone (obtained by Brewer No. 067, located at Rome) and horizontal wind at various levels. ...

  14. 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...

  15. 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.

  16. 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.

  17. 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)

  18. 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.

  19. Analysis of pressure fluctuations in swirling turbulent flows

    OpenAIRE

    Abry, P.; Fauve, S.; Flandrin, P; Laroche, C

    1994-01-01

    Turbulent flows display intermittent pressure drops associated with vorticity concentrations. Using wavelet transform, we characterize these low pressure events and study some of their statistical characteristics in a flow generated between the gap of two counter-rotating disks. We show that the mean frequency of intermittent pressure drops decreases with increasing Reynolds number.


  20. 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

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  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. 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...

  8. 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)

  9. 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.

  10. 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

  11. 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.

  12. Lateral Stability Analysis of Hypersonic Vehicle under Pressure Fluctuation by Solving Mathieu Differential Equation

    CERN Document Server

    Wei, Qingkai

    2012-01-01

    Two recent test failures of Hypersonic Technology Vehicle 2 impose a strike to the increasingly growing enthusiasm, not only on the United States side. It is important to find out the exact failure reason, otherwise a solution is impossible. In this Note, we propose a potential failure reason from the perspective of lateral stability analysis. We argue that the time variant pressure fluctuations, which are normally omitted in classical aircraft dynamics analysis, could not be neglected in dynamic analysis of hypersonic vehicles. To demonstrate the idea, a hypersonic model is imagined in this work and its aerodynamic parameters are estimated using fundamental fluid principles. Pressure fluctuations are thereafter estimated by an empirical formula. A lateral dynamic equation is set up, taking those time variant fluctuations into account. The resulted equation is a Mathieu differential equation. Numerical solutions of this equation show that the inclusion of fluctuation terms generates more complicated dynamics ...

  13. Modelling pressure fluctuations during flow boiling in microchannels with inlet compressibility and resistance

    OpenAIRE

    Gedupudi, S; Karayiannis, TG; Kenning, DBR

    2009-01-01

    Confined bubble growth during flow boiling at low pressures in microchannels generates pressure fluctuations that may cause transient flow reversals that disturb the flow distribution in heat sinks formed of parallel channels joined by plena. A simple model is developed for the effects of upstream compressibility and flow resistance at the channel inlet on the magnitude of the pressure transient during the growth of one bubble in a single channel. Preliminary results are presented.

  14. Hypobaric pressure exposure effects on cochlear frequency selectivity in fluctuating, low-frequency hearing loss.

    OpenAIRE

    Brännström, K. J.; Grenner, Jan

    2009-01-01

    Aim:To study the effects of hypobaric pressure chamber exposure on the cochlear frequency selectivity of subjects with monaural, fluctuating, low-frequency hearing loss, such as occurs in Ménière's disease.Methods:We used a hypobaric pressure chamber to create relative underpressure in the ear canal, in order to impose positive pressure gradients on the inner ear. Psychophysical tuning curves, transiently evoked otoacoustic emissions and speech recognition scores in noise were measured in...

  15. Surface atmospheric pressure excitation of the translational mode of the inner core

    CERN Document Server

    Rosat, Séverine; Rogister, Yves

    2014-01-01

    Using hourly atmospheric surface pressure field from ECMWF (European Centre for Medium-Range Weather Forecasts) and from NCEP (National Centers for Environmental Prediction) Climate Forecast System Reanalysis (CFSR) models, we show that atmospheric pressure fluctuations excite the translational oscillation of the inner core, the so-called Slichter mode, to the sub-nanogal level at the Earth surface. The computation is performed using a normal-mode formalism for a spherical, self-gravitating anelastic PREM-like Earth model. We determine the statistical response in the form of power spectral densities of the degree-one spherical harmonic components of the observed pressure field. Both hypotheses of inverted and non-inverted barometer for the ocean response to pressure forcing are considered. Based on previously computed noise levels, we show that the surface excitation amplitude is below the limit of detection of the superconducting gravimeters, making the Slichter mode detection a challenging instrumental task...

  16. Requirements for plasma synthesis of nanocrystals at atmospheric pressures

    International Nuclear Information System (INIS)

    While well-defined high quality semiconductor nanocrystals have been synthesized successfully in low pressure nonthermal plasmas, moving the field of plasma nanoparticle synthesis to atmospheric pressures is important for lowering its cost and making the process attractive for some industrial applications. Here we present a heating and charging model for silicon nanoparticles during their synthesis in plasmas maintained over a wide range of pressures (10 − 105 Pa). We consider three collisionality regimes and determine the dominant contribution of each regime to heating and charging of nanoparticles under various plasma conditions. For plasmas maintained at atmospheric pressures we find that the ion current is mainly due to the collisional hydrodynamic contribution. Based on the model, we predict that the formation of nanocrystals at atmospheric pressure requires significantly higher plasma densities than those at low pressures. Strong nanoparticle cooling at atmospheric pressures necessitates high ion densities to reach temperatures required for crystallization of nanoparticles. Using experimentally determined plasma properties from the literature we estimate the nanoparticle temperature that can be achieved during synthesis at atmospheric pressures and predict that temperatures well above those required for crystallization can be achieved. Based on these results we suggest design principles for nanocrystal synthesis at atmospheric pressures. (paper)

  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. Experimental investigation of wall static pressure fluctuations in parallel boiling flow

    International Nuclear Information System (INIS)

    Measurements of the statistical characteristics of channel wall static pressure fluctuations in parallel one-component boiling flow are reported. The measurements span a wide range of local subcooling and vapor volume fraction, and correspond to flow regimes ranging from highly subcooled bubbly to saturated slug-annular. Vapor volume fraction measurements at the pressure measurement station are also reported in conjunction with visual observation of the flow structure. Variation of static pressure fluctuation intensity and spectral content with local thermal-hydraulic condition is demonstrated. Finally, it is suggested that diagnosis of local two-phase flow regime on the basis of (i) statistical characteristics of the pressure data, and (ii) time trace of pressure signal, may be possible. 15 refs

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

    International Nuclear Information System (INIS)

    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

  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. 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.

  3. Large eddy simulation of vortex shedding and pressure fluctuation in aerostatic bearings

    Science.gov (United States)

    Zhu, Jincheng; Chen, Han; Chen, Xuedong

    2013-07-01

    In aerostatic bearings, high speed air flow may induce small vibration, which has been harmful to the improvement of moving and positioning accuracy of aerostatically supported devices in ultra-precision applications. In this paper, the transient flow field in the aerostatic bearing is numerically investigated using the large eddy simulation method. Turbulent structures are studied and vortex shedding phenomenon is discovered in the bearing recess. Our computational results demonstrate that vortex shedding causes pressure fluctuation in the bearing clearance. Relationship between pressure fluctuation and bearing vibration is established based on our simulation results and experimentally measured vibration strength.

  4. 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

  5. Perspectives on atmospheric-pressure plasmas for nanofabrication

    International Nuclear Information System (INIS)

    Low-pressure, low-temperature plasmas are widely used for materials applications in industries ranging from electronics to medicine. To avoid the high costs associated with vacuum equipment, there has always been a strong motivation to operate plasmas at higher pressures, up to atmospheric. However, high-pressure operation of plasmas often leads to instabilities and gas heating, conditions that are unsuitable for materials applications. The recent development of microscale plasmas (i.e. microplasmas) has helped realize the sustainment of stable, non-thermal plasmas at atmospheric pressure and enable low-cost materials applications. There has also been an unexpected benefit of atmospheric-pressure operation: the potential to fabricate nanoscale materials which is not possible by more conventional, low-pressure plasmas. For example, in a high-pressure environment, nanoparticles can be nucleated in the gas phase from vapour (or solid metal) precursors. Alternatively, non-thermal, atmospheric-pressure plasmas can be coupled with liquids such as water or ethanol to nucleate and modify solution-phase nanoparticles. In this perspective paper, we review some of these recent efforts and provide an outlook for the rapidly emerging field of atmospheric-pressure plasmas for nanofabrication.

  6. 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)

  7. 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)

  8. 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.

  9. 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.

  10. 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...

  11. 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.)

  12. 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

    2016-04-01

    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.

  13. Far field pressure fluctuations and coherent structures in a low mach number turbulent jet flow

    OpenAIRE

    Camussi, Roberto; Felli, Mario

    2005-01-01

    Simultaneous far field pressur/in-flow velocity fluctuations are measured in a turbulent jet flow at low Ma number. The experiment is conducted in an acustically controlled enviroment using LDV and standard microphones. Velocity signals acquired in several positions within the flow field are conditioned on the far field pressure peaks and signatures of ensamble averaged noise emitting event are retrieved. Present results confirms previous findings obtained on the same apparatus showing that i...

  14. 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...

  15. 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...

  16. 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...

  17. 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. ...

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

    International Nuclear Information System (INIS)

    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

  19. Quantitative millimetre wavelength spectrometry at pressures approaching atmospheric II. Determination of oxygen at atmospheric pressure

    International Nuclear Information System (INIS)

    A millimetre wavelength (MMW) Fabry-Perot cavity spectrometer described in earlier work has been applied to the measurement of oxygen absorption at 60 GHz and atmospheric pressure in a gas matrix of nitrogen. The spectrometer has also been modified such that the MMW source is stabilised by a sub-harmonic microwave signal transmitted by an infrared carrier on a single mode telecommunications fibre optic. This is a step towards developing an instrument comprising minimal electronic components that can perform MMW spectrometry remotely. Oxygen determinations were achieved by monitoring the change in the quality factor (Q) of a resonant Fabry-Perot cavity due to the presence of an absorbing sample. The MMW absorption of the sample was determined by incrementing the frequency modulation (FM) deviation of the source frequency scanning the cavity resonance profile. The response curve of absorption signal versus fraction of oxygen in nitrogen was found to be linear throughout the working range of 1-100% O2 (v/v) in N2 with a slope of (1.407±0.007)x10-4 m-1 (% O2)-1. The detection limit (3x standard deviation of the background) was found to be ∼0.8% (v/v). The MMW technique employed is advantageous since, unlike common MMW techniques, there is no vacuum requirement. Application of this method, to the monitoring of oxygen in gas mixtures of practical importance, is proposed. Values of the oxygen spectral absorption coefficients of lines between 55 and 60 GHz were measured at reduced pressure and found to be within ±2% of previous literature values. A pressure correction coefficient for O2 absorption at 60 GHz in the 45-121 kPa range was obtained and found to be (1.354±0.014)x10-4 m-1 kPa-1

  20. Effect of heat flux on fluctuating pressure in steam-water two-phase flow

    International Nuclear Information System (INIS)

    Experiments are carried out to study the feature of pressure fluctuating in helical coil for both adiabatic and boiling steam-water two-phase flows. And the effects of heat flux on the fluctuations are stressed study. It shows that heat flux has great influence on the fluctuation feature. The root mean square (RMS) of the fluctuation process under the condition of low heat flux is similar as that of adiabatic flow, while the RMS of great heat flux differs greatly for that of adiabatic flow. The fractal dimension is close to 1.50 under the condition of great heat flux, which means the pressure fluctuating is approaching stochastic process. The correlation dimension increases with increasing of heat flux. The Kolmogorov entropy on the condition of low heat flux is greater than that of adiabatic flow, while the contrary appears under the condition of great heat flux. It can be concluded that the flow pattern map and transition theories for flow patterns on basis of adiabatic flow just can be extrapolated to boiling flow with low heat flux

  1. 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.

  2. Fluctuation emergence of bubbles under a rapid drop of pressure in a liquid

    Science.gov (United States)

    Pavlov, P. A.; Vinogradov, V. E.

    2015-07-01

    Explosive cavitation at the front of a negative-pressure pulse has been studied. Conditions for the emergence of bubbles by the mechanism of homogeneous fluctuation nucleation were identified. Those conditions feature a high rate of the phase transformation, with the vapor formation process being concentrated in time at the instant of attainment of a certain pressure. Under such conditions, the liquid cavitation strength is maximal, and its value can be predicted by the homogeneous nucleation theory. For implementing the regime with high nucleation frequency, a method based on passing a negative-pressure pulse across a region with locally heated liquid was employed. The cavitation kinetics was examined by monitoring the perturbation of the heat flow from a miniature heater. The experimental data were generalized using the theory of explosive vapor formation in shock boiling mode. A method for calculating the cavitation in the regime of the fluctuation emergence of bubbles was approbated.

  3. 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 ...

  4. 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.

  5. Application of Relationship Between Groundwater Level and Atmospheric Pressure Change

    Science.gov (United States)

    Kim, S. J.; Lee, K.

    2013-12-01

    Change in atmospheric pressure affects ground water levels. Barometric efficiency, which is an indicator for different exposure to the atmospheric pressure of observation well and adjacent ground cover, can be used as an effective tool for estimating some groundwater properties. If the top of an observation well is sealed and contact with the atmosphere is blocked, there would be no pressure difference between the well and adjacent ground cover. As a result, the difference between barometric efficiency values of sealed and unsealed well of identical condition can indicates the effect of atmospheric pressure changes on the groundwater level. One month observation data of hydraulic head and atmospheric pressure at Wonju-si in Gangwon-do, Korea are used. Two different methods, Clark's method and graphical method, are adopted to estimate the barometric efficiency. Because the efficiency has implication on the properties of aquifer covering condition, mapping of this efficiency might be used for estimating groundwater vulnerability of contamination from surface-loaded sources.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  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. 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.

  14. Numerical study on in-situ leaching uranium with pressure fluctuation

    International Nuclear Information System (INIS)

    Recent researches and innovation of in-situ leaching focus on the chemical process, which can not solve the low recovery in 'dead leaching zone' and 'non-preferential zone' caused by preferential flow and solute transport phenomena in heterogeneous ore deposits. Based on hydrodynamic effects and phenomena in highly heterogeneous porous media, gas injection experiments and laboratory experiment results, an innovative method for in-situ leaching, named as leaching with pressure fluctuation, was put forward to enhance the leaching effect and uranium recovery, especially in those uranium ore deposits with high heterogeneity. Based on the characteristics of gas/liquid mixture and flow-reactive-transport theory, a numerical modeling tool is established. By the numerical simulation, the field-scale traditional leaching method and the new method were studied. The simulation results show that the gas-liquid mixture will expand/shrink greatly in different flow zone during the pressure fluctuation process, and the deformation will enhance the solute transport effect among different flow zones, especially in non-preferential flow zone, and enhance the uranium recovery. The primary results show that in-situ leaching with pressure fluctuation is feasible technically. (authors)

  15. Effect of a downstream ventilated gas cavity on turbulent boundary layer wall pressure fluctuation spectra

    Science.gov (United States)

    Young, Steven D.; Brungart, Timothy A.; Lauchle, Gerald C.; Howe, Michael S.

    2005-12-01

    An analytical and experimental investigation is made of the effect of a 2-D ventilated gas cavity on the spectrum of turbulent boundary layer wall pressure fluctuations upstream of a gas cavity on a plane rigid surface. The analytical model predicts the ratio of the wall pressure spectrum in the presence of the cavity to the blocked wall pressure spectrum that would exist if the cavity were absent. The ratio is found to oscillate in amplitude with upstream distance (-x) from the edge of the cavity. It approaches unity as -ωx/Uc-->∞, where ω is the radian frequency and Uc is the upstream turbulence convection velocity. To validate these predictions an experiment was performed in a water tunnel over a range of mean flow velocities. Dynamic wall pressure sensors were flush mounted to a flat plate at various distances upstream from a backward facing step. The cavity was formed downstream of the step by injecting carbon dioxide gas. The water tunnel measurements confirm the predicted oscillatory behavior of the spectral ratio, as well as its relaxation to unity as -ωx/Uc-->∞. For -ωx/Uc>7 the cavity has a negligible influence on the upstream wall pressure fluctuations.

  16. Characterization of base pressure fluctuations in a blunt trailing edge wake with three-dimensional forcing

    Science.gov (United States)

    Clark, Heather; Lavoie, Philippe

    2015-11-01

    The wakes of many nominally two-dimensional bluff bodies exhibit multiple intrinsic three-dimensional instabilities whose spatiotemporal structure and growth rate depend on geometry and Reynolds number. Here, these features are investigated experimentally for a blunt trailing edge profiled body using simultaneous measurements of velocity and fluctuating surface pressure on the model rear face near separation. Passive three-dimensional forcing of the wake is implemented with an array of vortex generators that are distributed according to the characteristic spanwise wavelength of the dominant secondary instability. For a Reynolds number of 8000 based on model thickness, the control strategy is found to increase the base pressure coefficient by 26% while globally reducing the amplitude of base pressure fluctuations, relative to the unforced flow. Additionally, amplitude modulation of the pressure signals that is observed in the natural wake decreases in strength with distributed forcing as a result of the modified three-dimensional flow structure. The spanwise distribution of pressure will be further examined for the baseline and controlled flows via temporal spectral analysis and spatial modal decomposition.

  17. 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.

  18. 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.

  19. 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.

  20. 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

    overwhelm the true source pressure in some cases. In this paper, the model of the sound intensity caused by the TBL pressure fluctuation is described firstly. Based upon the developed model, the sound intensity caused by the TBL pressure fluctuation is calculated using the available models of the wave-vector...... frequency spectra of the TBL pressure fluctuation. In order to validate the model and the numerical results, a serious of measurements were carried out. It is shown that the calculated results of the TBL pressure fluctuation agree fairly well with the measured results which are corrected with the estimated...... spatial response function of the microphone. Also, the characteristics of the measured sound intensity are consistent with that of the calculated sound intensity....

  1. 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

  2. Numerical study of pressure fluctuations in different guide vanes' opening angle in pump mode of a pump turbine

    International Nuclear Information System (INIS)

    A numerical model based on a pumped storage power station was built to develop the numerical simulation, to analyze the pressure fluctuations in a pump turbine in different guide vanes' opening angle. The different guide vanes' opening angles were simulated using the SST k-ω turbulence model and SIMPLEC Pressure-Velocity coupling scheme. The pressure sensor were placed in mainly three positions, they are: bottom ring between runner and the wicket gates, downstream and left side in the draft tube cone below the runner. All the peak to peak values of pressure fluctuation meet signal probability of 97%. The frequency is gained by Fast Fourier Transform. The pressure fluctuations in different positions of the model in pump condition were showed when the guide vanes' opening angels were different. The simulation results confirmed the results gained in model tests. The results show that pressure fluctuations in design opening angle were much lower than those in off design opening angle. The main source of pressure fluctuations between runner and guide vanes is rotor stator interaction. While a lower frequency is the main frequency of the pressure fluctuation in draft tube.

  3. Numerical study of pressure fluctuations in different guide vanes' opening angle in pump mode of a pump turbine

    Science.gov (United States)

    Sun, Y. K.; Zuo, Z. G.; Liu, S. H.; Liu, J. T.; Wu, Y. L.

    2012-11-01

    A numerical model based on a pumped storage power station was built to develop the numerical simulation, to analyze the pressure fluctuations in a pump turbine in different guide vanes' opening angle. The different guide vanes' opening angles were simulated using the SST k-ω turbulence model and SIMPLEC Pressure-Velocity coupling scheme. The pressure sensor were placed in mainly three positions, they are: bottom ring between runner and the wicket gates, downstream and left side in the draft tube cone below the runner. All the peak to peak values of pressure fluctuation meet signal probability of 97%. The frequency is gained by Fast Fourier Transform. The pressure fluctuations in different positions of the model in pump condition were showed when the guide vanes' opening angels were different. The simulation results confirmed the results gained in model tests. The results show that pressure fluctuations in design opening angle were much lower than those in off design opening angle. The main source of pressure fluctuations between runner and guide vanes is rotor stator interaction. While a lower frequency is the main frequency of the pressure fluctuation in draft tube.

  4. 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.

  5. Atmospheric pressure photoionization using tunable VUV synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Giuliani, A., E-mail: alexandre.giuliani@synchrotron-soleil.fr [Synchrotron SOLEIL, L' Orme des Merisiers, Saint Aubin, 91192 Gif-sur-Yvette (France); INRA, U1008 CEPIA, Rue de la Geraudiere, F-44316 Nantes (France); Giorgetta, J.-L.; Ricaud, J.-P. [Synchrotron SOLEIL, L' Orme des Merisiers, Saint Aubin, 91192 Gif-sur-Yvette (France); Jamme, F. [Synchrotron SOLEIL, L' Orme des Merisiers, Saint Aubin, 91192 Gif-sur-Yvette (France); INRA, U1008 CEPIA, Rue de la Geraudiere, F-44316 Nantes (France); Rouam, V.; Wien, F. [Synchrotron SOLEIL, L' Orme des Merisiers, Saint Aubin, 91192 Gif-sur-Yvette (France); Laprevote, O. [Laboratoire de Spectrometrie de Masse, ICSN-CNRS, 1 Avenue de la Terrasse, 91190 Gif-sur-Yvette (France); Laboratoire de Chimie-Toxicologie Analytique et cellulaire, IFR 71, Faculte des Sciences Pharmaceutiques et Biologiques, Universite Paris Descartes, 4 Avenue de l' Observatoire, 75006 Paris (France); Refregiers, M. [Synchrotron SOLEIL, L' Orme des Merisiers, Saint Aubin, 91192 Gif-sur-Yvette (France)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer Coupling of an atmospheric pressure photoionization source with a vacuum ultra-violet (VUV) beamline. Black-Right-Pointing-Pointer The set up allows photoionization up to 20 eV. Black-Right-Pointing-Pointer Compared to classical atmospheric pressure photoionization (APPI), our set up offers spectral purity and tunability. Black-Right-Pointing-Pointer Allows photoionization mass spectrometry on fragile and hard to vaporize molecules. - Abstract: We report here the first coupling of an atmospheric pressure photoionization (APPI) source with a synchrotron radiation beamline in the vacuum ultra-violet (VUV). A commercial APPI source of a QStar Pulsar i from AB Sciex was modified to receive photons from the DISCO beamline at the SOLEIL synchrotron radiation facility. Photons are delivered at atmospheric pressure in the 4-20 eV range. The advantages of this new set up, termed SR-APPI, over classical APPI are spectral purity and continuous tunability. The technique may also be used to perform tunable photoionization mass spectrometry on fragile compounds difficult to vaporize by classical methods.

  6. 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…

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

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Mortensen, Henrik Junge; Stenum, Bjarne; Goutianos, Stergios; Mitra, Susanta; Ghanbari-Siahkali, Afshin; Kingshott, Peter; Sørensen, Bent F.; Bindslev, Henrik

    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...

  8. 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.

  9. Electrolytic synthesis of ammonia in molten salts under atmospheric pressure.

    Science.gov (United States)

    Murakami, Tsuyoshi; Nishikiori, Tokujiro; Nohira, Toshiyuki; Ito, Yasuhiko

    2003-01-15

    Ammonia was successfully synthesized by using a new electrochemical reaction with high current efficiency at atmospheric pressure and at lower temperatures than the Haber-Bosch process. In this method, nitride ion (N3-), which is produced by the reduction from nitrogen gas at the cathode, is anodically oxidized and reacts with hydrogen to produce ammonia at the anode. PMID:12517136

  10. 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.

  11. 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.

  12. Atmospheric-pressure guided streamers for liposomal membrane disruption

    International Nuclear Information System (INIS)

    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.

  13. 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.

  14. Model of a stationary microwave argon discharge at atmospheric pressure

    International Nuclear Information System (INIS)

    The many applications of microwave gas discharges at atmospheric pressure in various fields of science, technology and medicine require an adequate model of these discharges. Such a model is based on the electromagnetic wave's propagation properties and on the elementary processes in the discharge bulk. In contrast to the microwave discharges at low-gas pressures, where many elementary processes might be ignored because of their negligible contribution to the electron and heavy particle's balance equations, for such discharges at atmospheric pressure the consideration of a large number of collisional processes is mandatory. For the build of a successful discharge-column model one needs three important quantities, notably the power θ necessary for sustaining an electron - ion pair, electron - neutral collision frequency for momentum transfer ven, and gas temperature Tg. The first two key parameters are obtained by a collisional-radiative model of the argon at atmospheric pressure, while the microwave frequency ω/2π = 2.45 GHz, plasma column radius R, gas pressure p and gas temperature Tg are fixed external parameters determined by the experimental conditions. Here, we present a model of a capillary argon microwave plasma column with a length L ≅ 14 cm, sustained by wave power of 110 W - the model yields the longitudinal distributions of the plasma density, expended wave power, wave electric field magnitude, and complex wave number

  15. Model of a stationary microwave argon discharge at atmospheric pressure

    Science.gov (United States)

    Zhelyazkov, I.; Pencheva, M.; Benova, E.

    2008-03-01

    The many applications of microwave gas discharges at atmospheric pressure in various fields of science, technology and medicine require an adequate model of these discharges. Such a model is based on the electromagnetic wave's propagation properties and on the elementary processes in the discharge bulk. In contrast to the microwave discharges at low-gas pressures, where many elementary processes might be ignored because of their negligible contribution to the electron and heavy particle's balance equations, for such discharges at atmospheric pressure the consideration of a large number of collisional processes is mandatory. For the build of a successful discharge-column model one needs three important quantities, notably the power θ necessary for sustaining an electron—ion pair, electron—neutral collision frequency for momentum transfer ven, and gas temperature Tg. The first two key parameters are obtained by a collisional-radiative model of the argon at atmospheric pressure, while the microwave frequency ω/2π = 2.45 GHz, plasma column radius R, gas pressure p and gas temperature Tg are fixed external parameters determined by the experimental conditions. Here, we present a model of a capillary argon microwave plasma column with a length L ≈ 14 cm, sustained by wave power of 110 W—the model yields the longitudinal distributions of the plasma density, expended wave power, wave electric field magnitude, and complex wave number.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Non-thermal atmospheric pressure discharges for surface modification

    International Nuclear Information System (INIS)

    Throughout the last decades, plasma technology has been established in a series of surface treatment applications, e.g. for semiconductor processing or optical coatings. The majority of plasma assisted technologies is based on low pressure processes. In recent years, however, non-thermal atmospheric pressure discharges have attracted considerable interest because of their simplified technical devices for industrial applications as compared to low pressure processes which require vacuum equipment. Hence, batch processing can be avoided, thus facilitating the implementation of plasma process steps into production lines. Investment costs are cut down significantly. The use of atmospheric pressure plasmas for technical applications dates back to the ozone production with dielectric barrier discharges (DBD) by Siemens in 1857. Lately, the application of atmospheric pressure plasmas for surface treatment has been reported, e.g. for the treatment of foils to improve printability, for surface cleaning and protective coatings. The DBD is known as a strongly inhomogeneous, filamentary discharge. A non filamentary, homogeneous DBD was observed in He, N2, other gases, and mixtures. An example of this discharge type and its application for the deposition of thin films by plasma polymerization is discussed in more detail. The standard planar electrode geometry of the DBD is characterized by a narrow inter-electrode gap in the mm-Region. Hence, surface treatment has been restricted to thin, flat substrates. Attempts to overcome these limitations involve micro discharge arrays and jet geometries, which are evoked by an enhanced gas flow, partly in combination with the electric field. Jets are created out of several plasma types, among them corona discharge, DBD, microwave discharge and RF discharge. With these plasma sources, substrate geometries displaying 3-dimensional features can be treated, too. Critical parameters for the comparison of atmospheric pressure surface

  1. 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.

  2. Experimental study of the pressure fluctuations on propeller turbine runner blades: part 2, transient conditions

    Science.gov (United States)

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

    2012-11-01

    Transient conditions such as load rejection will often lead to high amplitude pressure fluctuations that will affect a turbine residual-life. If Computational Fluid Dynamic offers a promising tool to study the flow dynamic under transient regime, focused validation data on the runner are still lacking to assess the accuracy of different simulation strategies. Hence within the framework of the AxialT project of the International Consortium on Hydraulic Machines, exploratory measurements of the pressure field on the runner blades of a propeller turbine model were performed in transient conditions. The model was setup on the test stand of the LAMH of Laval University. The test stand control procedures were adapted to mimic transient condition such as load rejection or the transition from a normal operating condition to a speed-no-load condition. The pressure on the runner blades were measured using miniature piezo-resistive transducer linked to a high frequency telemetric system. Using specifically adapted data processing routines, it was possible to characterize the variations of the energy content during the transient runs. Specifically, the main fluctuations appear to occur in the sub-synchronous range in both cases.

  3. 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.

  4. 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

  5. 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.

  6. On some consequences resulting in employment of pressurized water reactors operated with fluctuating load

    International Nuclear Information System (INIS)

    Load-flexible employment of nuclear power plants may extend to concern in day-night cycle. For vessel-type pressurized water reactors this mode of operation brings essential technological and economic consequences about. As compared with operation on base load, the decrease of load factor and increase of demand for reactivity result in raising of cost. Rise in fuel cost, on the other hand, may be damped by artificially lowering efficiency near the end of campaign. Changes in cost including the influence of efficiency lowering may be calculated starting from the fluctuating load parameters

  7. 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.

  8. Model for energy transfer by coherent Fermi pressure fluctuations in quantum soft matter

    CERN Document Server

    Peterson, Mark A

    2015-01-01

    A 1-dimensional model for coherent quantum energy transfer through a complex of compressible boxes is investigated by numerical integration of the time-dependent Schr\\"odinger equation. Energy is communicated from one box to the next by the resonant fluctuating Fermi pressure of the electrons in each box pushing on the walls and doing work on adjacent boxes. Parameters are chosen similar to the chain molecules of typical light harvesting complexes. For some parameter choices the system is found to have an instability leading to self-induced coherent energy transfer transparency.

  9. 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.

  10. Propagation of atmospheric pressure fronts in long vacuum tubes

    International Nuclear Information System (INIS)

    This experimental work was undertaken during the development of a system using fast acting valves to protect the Intersecting Storage Rings (ISR) vacuum chamber at CERN against damage from the implosion of thin wall vacuum chambers. A 30 m cylindrical tube with a diameter of 130 mm and similar to that used on the ISR, was evacuated to 10-2 torr. Following the sudden entry of atmospheric pressure at one end the pressure versus time diagram was observed a several points along the tube. These diagrams show a characteristic 'staircase' function which permits the determination of the propagation velocity. There is an initial weak pressure front of a few torr, propagated at 950 m s-1, which presents little mechanical danger, even to delicate components such as ionisation gauges. After a formation time of 0.1 s, one or more large amplitude (several tens of torr) and potentially dangerous pressure fronts are propagated with a velocity of 770 m s-1

  11. Reduced atmospheric pressure in Radish: Alteration of NCER and transpiration at decreased oxygen partial pressures

    Science.gov (United States)

    Wehkamp, Cara Ann; Stasiak, Michael; Wheeler, Raymond; Dixon, Mike

    Fundamental to the future of space exploration is the development of advanced life support systems capable of maintaining crews for significant periods without re-supply from Earth. Significant research is focused on the development of bioregenerative life support systems to be used in conjunction with the current physico-chemical methods. These bioregenerative life support systems harness natural ecosystem processes and employ plant photosynthesis and transpiration to produce food, oxygen and regenerate water while consuming carbon dioxide. The forthcoming exploration of the Moon and Mars has prompted interest into the effects of hypobaria on plant development. Reduced atmospheric pressures will lessen the pressure gradient between the structure and the local environment thereby decreasing gas leakage and possibly the structural mass of the plant growth facility. In order to establish the optimal specifications for reduced pressure plant growth structures it is essential to determine the atmospheric pressure limits required for conventional plant development and growth. Due to its physiological importance, oxygen will compose a significant portion of these minimal environments. The objective of this study was to test the hypothesis that reduced atmospheric pressure and decreased oxygen partial pressures had no effect on radish productivity. Radishes (Raphanus sativa L. cv. Cherry Bomb II) were grown from seed in the University of Guelph's Hypobaric Plant Growth Chambers for a period of 21 days. Treatments included total pressures of 10, 33, 66 and 96 kPa and oxygen partial pressures of 2, 7, 14 and 20 kPa. Experiments demonstrated that reduced partial pressures of oxygen had a greater effect on radish growth than hypobaria. Results showed a reduction in net carbon exchange rate and transpiration with decreasing oxygen partial pressures leading to diminished productivity. Keywords: hypobaric, radish, oxygen partial pressure, variable pressure chamber

  12. 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

  13. 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.

  14. The main properties of microwave argon plasma at atmospheric pressure

    International Nuclear Information System (INIS)

    Plasma torch sustained by surface wave at atmospheric pressure is theoretically studied by means of 1D model. A steady-state Boltzmann equation in an effective field approximation coupled with a collisional-radiative model for high-pressure argon discharge is numerically solved together with Maxwell's equations for an azimuthally symmetric TM surface wave. The axial dependences of the electrons, excited atoms, atomic and molecular ions densities as well as the electron temperature, the mean power per electron and the effective electron-neutral collision frequency are determined. A strong dependence of the plasma properties on the discharge conditions and the gas temperature is obtained.

  15. The main properties of microwave argon plasma at atmospheric pressure

    Science.gov (United States)

    Benova, E.; Pencheva, M.

    2010-01-01

    Plasma torch sustained by surface wave at atmospheric pressure is theoretically studied by means of 1D model. A steady-state Boltzmann equation in an effective field approximation coupled with a collisional-radiative model for high-pressure argon discharge is numerically solved together with Maxwell's equations for an azimuthally symmetric TM surface wave. The axial dependences of the electrons, excited atoms, atomic and molecular ions densities as well as the electron temperature, the mean power per electron and the effective electron-neutral collision frequency are determined. A strong dependence of the plasma properties on the discharge conditions and the gas temperature is obtained.

  16. The main properties of microwave argon plasma at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Benova, E; Pencheva, M, E-mail: benova_phys@deo.uni-sofia.b [Department for Language Teaching and International Students, University of Sofia, 27 Kosta Loulchev Street, BG-1111 Sofia (Bulgaria)

    2010-01-01

    Plasma torch sustained by surface wave at atmospheric pressure is theoretically studied by means of 1D model. A steady-state Boltzmann equation in an effective field approximation coupled with a collisional-radiative model for high-pressure argon discharge is numerically solved together with Maxwell's equations for an azimuthally symmetric TM surface wave. The axial dependences of the electrons, excited atoms, atomic and molecular ions densities as well as the electron temperature, the mean power per electron and the effective electron-neutral collision frequency are determined. A strong dependence of the plasma properties on the discharge conditions and the gas temperature is obtained.

  17. 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.

  18. 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

  19. Thermally induced atmospheric pressure gas discharges using pyroelectric crystals

    International Nuclear Information System (INIS)

    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. (paper)

  20. Atmospheric-pressure plasma sources for biomedical applications

    International Nuclear Information System (INIS)

    Atmospheric-pressure plasmas (APPs) have attracted great interest and have been widely applied in biomedical applications, as due to their non-thermal and reactive properties, they interact with living tissues, cells and bacteria. Various types of plasma sources generated at atmospheric pressure have been developed to achieve better performance in specific applications. This article presents an overview of the general characteristics of APPs and a brief summary of their biomedical applications, and reviews a wide range of these sources developed for biomedical applications. The plasma sources are classified according to their power sources and cover a wide frequency spectrum from dc to microwaves. The configurations and characteristics of plasma sources are outlined and their biomedical applications are presented. (invited review)

  1. 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.

  2. Cellular membrane collapse by atmospheric-pressure plasma jet

    International Nuclear Information System (INIS)

    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

  3. 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.

  4. 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.

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

    International Nuclear Information System (INIS)

    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. aureus) 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. (plasma technology)

  6. The first experiments on dielectric barrier discharge under atmospheric pressure

    International Nuclear Information System (INIS)

    In order to obtain uniform and stable discharge plasma in atmospheric pressure, dielectric barrier discharge experiments were carried out. Main purpose is to examine the applicability of dielectric barrier discharge to production processes of semi-conductors. LSIs and flat display panels. In the experiments, at first, quite stable and uniform discharge was obtained at atmospheric pressure. Effects of applied voltage and frequency on plasma uniformity were studied. Improvement of discharge uniformity by introducing gas flow of helium or nitrogen between the discharge gap was observed. Finally, surface cleaning effect of the present plasma was confirmed by observing contact angle of liquid droplet. At least for cleaning process, possibility of application as process plasma was suggested

  7. Atmospheric pressure plasma jet for liquid spray treatment

    Science.gov (United States)

    Mitić, S.; Philipps, J.; Hofmann, D.

    2016-05-01

    Atmospheric pressure plasma jets have been intensively studied in recent years due to growing interest in their use for biomedical applications and surface treatments. Either surfaces can be treated by a plasma jet afterglow for cleaning or activation or a material can be deposited by a reactive gas component activated by plasma. Effects of plasma on liquid have been reported several times where the electron spin trapping method was used for radical detection. Here we propose another method of liquid treatment using the atmospheric pressure plasma jet. In the device presented here, liquid was sprayed in droplets from an inner electrode directly into a plasma jet where it was treated and sprayed out by gas flow. Optical end electrical measurements were done for diagnostics of the plasma while electron paramagnetic resonance measurements were used for detection of radicals (\\text{OH},\\text{OOH},\\text{CH} ) produced by plasma treatment of liquids.

  8. 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.

  9. Classification of gas-liquid flow patterns by the norm entropy of wavelet decomposed pressure fluctuations across a bluff body

    Science.gov (United States)

    Sun, Zhiqiang; Chen, Yanping; Gong, Hui

    2012-12-01

    Identification of gas-liquid flow patterns remains one of the paramount needs in multiphase flow metering. It is hardly possible to realize accurate measurement and control of parameters in a gas-liquid flow system without a clear understanding of its flow pattern. Here we explore the characterization of gas-liquid flow patterns using the norm entropy extracted from the wavelet decomposed pressure fluctuations across a bluff body. Experiments on air-water two-phase flow at ambient temperature and atmospheric pressure are carried out in the bubble, plug, slug and annular flow patterns. On the basis of the experimental results, two original flow-pattern maps are constructed: one is coordinated with the average norm entropy versus the total mass flow rate, and the other is the average norm entropy versus the volumetric void fraction. Verification tests demonstrate that the overall identification rates of the flow-pattern maps developed exceed 95%. This approach provides an effective and simple solution to the classification of gas-liquid flow patterns.

  10. Classification of gas–liquid flow patterns by the norm entropy of wavelet decomposed pressure fluctuations across a bluff body

    International Nuclear Information System (INIS)

    Identification of gas–liquid flow patterns remains one of the paramount needs in multiphase flow metering. It is hardly possible to realize accurate measurement and control of parameters in a gas–liquid flow system without a clear understanding of its flow pattern. Here we explore the characterization of gas–liquid flow patterns using the norm entropy extracted from the wavelet decomposed pressure fluctuations across a bluff body. Experiments on air–water two-phase flow at ambient temperature and atmospheric pressure are carried out in the bubble, plug, slug and annular flow patterns. On the basis of the experimental results, two original flow-pattern maps are constructed: one is coordinated with the average norm entropy versus the total mass flow rate, and the other is the average norm entropy versus the volumetric void fraction. Verification tests demonstrate that the overall identification rates of the flow-pattern maps developed exceed 95%. This approach provides an effective and simple solution to the classification of gas–liquid flow patterns. (paper)

  11. 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)

  12. Electrical, Optical and acoustic diagnostics of atmospheric pressure gas discharges

    OpenAIRE

    O'Connor, Niall

    2011-01-01

    This thesis presents original diagnostic investigations of atmospheric pressure gaseous discharges, operating in owing helium and helium with low concentrations (0.1 - 1 %) of gas admixtures, together with novel biomedical surface functionalisations. The initial body of this work focuses on comprehensive electrical and optical diagnostics of the operation of an industrial scale dielectric barrier discharge (DBD), maintained in a 10 l/min w of both helium and helium with 1% admixed ...

  13. Temperature profiles in filamentary dielectric barrier discharges at atmospheric pressure

    OpenAIRE

    Jidenko, N; Bourgeois, E; Borra, J-P

    2010-01-01

    Abstract The physico-chemical properties of atmospheric pressure filamentary Dielectric Barrier Discharge (f-DBD) depend on its electrical characteristics and thermal profile. In this paper, a method for separating thermal and electrical effects is developed. Therefore, thermal profiles of f-DBD are studied for well defined electrical characteristics of filaments: all filaments are quasi identical with a controlled spatio-temporal density. The temperatures of gas, dielectric surface and pl...

  14. BIOLOGICAL APPLICATIONS OF ATMOSPHERIC PRESSURE DIELECTRIC BARRIER DISCHARGES

    OpenAIRE

    Dodet, Bénédicte; Odic, Emmanuel; Salamitou, Sylvie; Goldman, Alice; Goldman, Max

    2006-01-01

    A reduction of more than 4 orders of magnitude of survivors was obtained by exposing a Bacillus Stearothermophilus spores - contaminated surface to an atmospheric pressure DBD post-discharge for 20 minutes. Decontamination mechanisms are investigated assuming that (i) inactivation is obtained when the bacteria DNA is fragmented, (ii) the protein coats are the main protection of the cell core DNA in the case of bacteria spores. The degradation of DNA (plasmid) and protein (RNAse A) samples sub...

  15. Atmospheric pressure plasmas for aerosols processes in materials and environment

    OpenAIRE

    Borra, J.P.; Jidenko, N; Bourgeois, E

    2009-01-01

    Abstract The paper highlights applications of some atmospheric pressure plasmas (dc-corona, streamer and spark and ac-Dielectric Barrier Discharges) to aerosol processes for Materials and Environment (filtration, diagnostics). The production of vapor i.e. condensable gaseous species, leads to nano-sized particles by physical and chemical routes of nucleation in these AP plasmas: (i) when dc streamer and spark filamentary discharges as well as ac filamenta...

  16. 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...

  17. Assessment of Atmospheric Pressure Plasma Treatment for Implant Osseointegration

    OpenAIRE

    Danna, Natalie R.; Beutel, Bryan G.; Nick Tovar; Lukasz Witek; Charles Marin; Bonfante, Estevam A.; Rodrigo Granato; Marcelo Suzuki; Coelho, Paulo G

    2015-01-01

    This study assessed the osseointegrative effects of atmospheric pressure plasma (APP) surface treatment for implants in a canine model. Control surfaces were untreated textured titanium (Ti) and calcium phosphate (CaP). Experimental surfaces were their 80-second air-based APP-treated counterparts. Physicochemical characterization was performed to assess topography, surface energy, and chemical composition. One implant from each control and experimental group (four in total) was placed in one ...

  18. Thin film deposition on powder surfaces using atmospheric pressure discharge

    International Nuclear Information System (INIS)

    The deposition of SiOx containing films on NaCl and KBr particles in dielectric barrier discharge under atmospheric pressure was investigated. As precursor hexamethyldisiloxane (HMDSO) and tetraethoxysilane (TEOS) in argon-oxygen gas mixtures were used. The deposited layers were studied by means of light microscopy, SEM and XPS investigations. The particles could be completely covered by SiOx. With increasing oxygen content in the coating the carbon content decreases

  19. 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.

  20. 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

  1. 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

  2. Atmospheric pressure plasma analysis by modulated molecular beam mass spectrometry

    International Nuclear Information System (INIS)

    Fractional number density measurements for a rf plasma 'needle' operating at atmospheric pressure have been obtained using a molecular beam mass spectrometer (MBMS) system designed for diagnostics of atmospheric plasmas. The MBMS system comprises three differentially pumped stages and a mass/energy analyzer and includes an automated beam-to-background measurement facility in the form of a software-controlled chopper mechanism. The automation of the beam modulation allows the neutral components in the plasma to be rapidly and accurately measured using the mass spectrometer by threshold ionization techniques. Data are reported for plasma generated by a needle plasma source operated using a helium/air mixture. In particular, data for the conversion of atmospheric oxygen and nitrogen into nitric oxide are discussed with reference to its significance for medical applications such as disinfecting wounds and dental cavities and for microsurgery

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Numerical simulation of the influence of distributor pitch diameter on performance and pressure fluctuations in a pump-turbine

    International Nuclear Information System (INIS)

    In order to analyse the influence of distributor pitch diameter on performance and pressure fluctuations in a pump turbine, a numerical model based on a pumped storage power station was built to develop the numerical simulation. Steady and unsteady flows were simulated using the SST k-ω turbulence model and SIMPLEC Pressure-Velocity coupling scheme. The performance, inner flow and pressure fluctuations between runner blades and guide vanes of both turbine and pump mode was contrasted in different distributor pitch diameters. The result shows there was a maximum total efficiency in a given distributor pitch diameter instead of the design diameter. Amplitudes and frequencies of pressure fluctuations on this diameter and design diameter were analysed, minor differences were observed. This position can be considered to help improving the flow of the pump turbine.

  9. Numerical simulation of the influence of distributor pitch diameter on performance and pressure fluctuations in a pump-turbine

    Science.gov (United States)

    Sun, Y. K.; Zuo, Z. G.; Liu, S. H.; Wu, Y. L.; Liu, J. T.

    2012-11-01

    In order to analyse the influence of distributor pitch diameter on performance and pressure fluctuations in a pump turbine, a numerical model based on a pumped storage power station was built to develop the numerical simulation. Steady and unsteady flows were simulated using the SST k-ω turbulence model and SIMPLEC Pressure-Velocity coupling scheme. The performance, inner flow and pressure fluctuations between runner blades and guide vanes of both turbine and pump mode was contrasted in different distributor pitch diameters. The result shows there was a maximum total efficiency in a given distributor pitch diameter instead of the design diameter. Amplitudes and frequencies of pressure fluctuations on this diameter and design diameter were analysed, minor differences were observed. This position can be considered to help improving the flow of the pump turbine.

  10. 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

  11. 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.

  12. 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...

  13. Interfacial instability induced by lateral vapor pressure fluctuation in bounded thin liquid-vapor layers

    CERN Document Server

    Kanatani, Kentaro

    2008-01-01

    We study an instability of thin liquid-vapor layers bounded by rigid parallel walls from both below and above. In this system, the interfacial instability is induced by lateral vapor pressure fluctuation, which is in turn attributed to the effect of phase change: evaporation occurs at the hotter portion of the interface and condensation at the colder one. The high vapor pressure drives the liquid away and the low one pulls it up. A set of equations describing the temporal evolution of the interface of the liquid-vapor layers is derived. This model neglects the effect of mass loss or gain at the interface and guarantees the mass conservation of the liquid layer. The result of linear stability analysis of the model shows that the presence of the pressure dependence of the local saturation temperature suppresses the growth of long-wave disturbances. We find the stability criterion, which suggests that only slight temperature gradients are sufficient to overcome the stabilizing gravitational effect for a water an...

  14. 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.

  15. Measurement of Turbulent Pressure and Temperature Fluctuations in a Gas Turbine Combustor

    Science.gov (United States)

    Povinelli, Louis (Technical Monitor); LaGraff, John E.; Bramanti, Cristina; Pldfield, Martin; Passaro, Andrea; Biagioni, Leonardo

    2004-01-01

    The report summarizes the results of the redesign efforts directed towards the gas-turbine combustor rapid-injector flow diagnostic probe developed under sponsorship of NASA-GRC and earlier reported in NASA-CR-2003-212540. Lessons learned during the theoretical development, developmental testing and field-testing in the previous phase of this research were applied to redesign of both the probe sensing elements and of the rapid injection device. This redesigned probe (referred to herein as Turboprobe) has been fabricated and is ready, along with the new rapid injector, for field-testing. The probe is now designed to capture both time-resolved and mean total temperatures, total pressures and, indirectly, one component of turbulent fluctuations.

  16. 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

  17. 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.

  18. Excitation dynamics of micro-structured atmospheric pressure plasma arrays

    OpenAIRE

    Boettner, H; Waskoenig, J.; Connell, D O '; Winter, J; Schulz-von der Gathen, V

    2010-01-01

    Abstract The spatial dynamics of the optical emission from an array of 50 times 50 individual micro cavity plasma devices are investigated. The array is operated in argon and argon-neon mixtures close to atmospheric pressure with an AC voltage. The optical emission is analysed with phase and space resolution. It has been found that the emission is not continuous over the entire AC period, but occurs once per half period. Each of the observed emission phases shows a self-pulsing of the disc...

  19. Heat transport of nitrogen in helium atmospheric pressure microplasma

    CERN Document Server

    Xu, Shaofeng

    2013-01-01

    Stable DC atmospheric pressure normal glow discharges in ambient air were produced between the water surface and the metallic capillary coupled with influx of helium gas. Multiple independent repeated trials indicated that vibrational temperature of nitrogen rises from 3200 to 4622 K, and rotational temperature of nitrogen decreases from 1270 to 570 K as gas flux increasing from 20 to 80 sccm and discharge current decreasing from 11 to 3 mA. Furthermore, it was found that the vibrational degree of the nitrogen molecule has priority to gain energy than the rotational degree of nitrogen molecule in nonequilibrium helium microplasma.

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

    DEFF Research Database (Denmark)

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

    2007-01-01

    density increased with the plasma treatments. Adhesion test of the treated glassy carbon covered with cured epoxy showed cohesive failure, indicating strong bonding after the treatments. This is in contrast to the adhesion tests of untreated samples where the epoxy readily peeled off the glassy carbon.......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...

  1. 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

  2. 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.

  3. 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)

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

    International Nuclear Information System (INIS)

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

  5. 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.

  6. 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.

  7. 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...

  8. Cold atmospheric pressure plasma jet interactions with plasmid DNA

    International Nuclear Information System (INIS)

    The effect of a cold (<40 deg. C) radio frequency-driven atmospheric pressure plasma jet on plasmid DNA has been investigated. Gel electrophoresis was used to analyze the DNA forms post-treatment. The experimental data are fitted to a rate equation model that allows for quantitative determination of the rates of single and double strand break formation. The formation of double strand breaks correlates well with the atomic oxygen density. Taken with other measurements, this indicates that neutral components in the jet are effective in inducing double strand breaks.

  9. Atmospheric pressure plasma surface modification of carbon fibres

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Løgstrup Andersen, Tom; Michelsen, Poul

    2008-01-01

    Carbon fibres are continuously treated with dielectric barrier discharge plasma at atmospheric pressure in various gas conditions for adhesion improvement in mind. An x-ray photoelectron spectroscopic analysis indicated that oxygen is effectively introduced onto the carbon fibre surfaces by He, He...... temperature for a month the O/C ratio at the plasma treated surfaces decreased to 0.151, which is close to that of the untreated ones. It can be attributed to the adsorption of hydrocarbon contamination at the plasma treated surfaces....

  10. 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....... The ultrasonic irradiation during the plasma treatment consistently enhanced the treatment efficiency. The principal effect of ultrasonic irradiation can be attributed to enhancing surface oxidation during plasma treatment. In addition, ultrasonic irradiation can suppress arcing, and the uniformity of...... and the material surface, and thus, many reactive species generated in the plasma can reach the surface before they are inactivated and can be efficiently utilised for surface modification. In the present work, glass fibre reinforced polyester plates were treated using a dielectric barrier discharge...

  11. 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...... air are separated using a polyethylene film. The gliding arc was extended by a high speed air flow into ambient air, directed the polyester surface at an angle of approximately 30o. The ultrasonic waves were introduced vertically to the surface. After the plasma treatment using each plasma source...... without ultrasonic irradiation, the water contact angle dropped markedly, and tended to decrease furthermore at higher power. The ultrasonic irradiation during the plasma treatment consistently improved the wettability. Oxygen containing polar functional groups were introduced at the surface by the plasma...

  12. 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

  13. Nearly critical spin and charge fluctuations in KFe2As2 observed by high-pressure NMR

    Science.gov (United States)

    Wang, P. S.; Zhou, P.; Dai, J.; Zhang, J.; Ding, X. X.; Lin, H.; Wen, H. H.; Normand, B.; Yu, R.; Yu, Weiqiang

    2016-02-01

    We report a high-pressure 75As NMR study on the heavily hole-doped iron pnictide superconductor KFe2As2 (Tc≈3.8 K). The low-energy spin fluctuations are found to decrease with applied pressure up to 2 GPa, but then to increase again, changing in lockstep with the pressure-induced evolution of Tc. Their diverging nature suggests close proximity to a magnetic quantum critical point at a negative pressure of P ≃-0.6 GPa. Above 2.2 GPa, the 75As satellite spectra split below 40 K, indicating a breaking of As site symmetry and an incipient charge order. These pressure-controlled phenomena demonstrate the presence of nearly critical fluctuations in both spin and charge, providing essential input for the origin of superconductivity.

  14. 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)

  15. A dc non-thermal atmospheric-pressure plasma microjet

    International Nuclear Information System (INIS)

    A direct current (dc), non-thermal, atmospheric-pressure plasma microjet is generated with helium/oxygen gas mixture as working gas. The electrical property is characterized as a function of the oxygen concentration and show distinctive regions of operation. Side-on images of the jet were taken to analyze the mode of operation as well as the jet length. A self-pulsed mode is observed before the transition of the discharge to normal glow mode. Optical emission spectroscopy is employed from both end-on and side-on along the jet to analyze the reactive species generated in the plasma. Line emissions from atomic oxygen (at 777.4 nm) and helium (at 706.5 nm) were studied with respect to the oxygen volume percentage in the working gas, flow rate and discharge current. Optical emission intensities of Cu and OH are found to depend heavily on the oxygen concentration in the working gas. Ozone concentration measured in a semi-confined zone in front of the plasma jet is found to be from tens to ∼120 ppm. The results presented here demonstrate potential pathways for the adjustment and tuning of various plasma parameters such as reactive species selectivity and quantities or even ultraviolet emission intensities manipulation in an atmospheric-pressure non-thermal plasma source. The possibilities of fine tuning these plasma species allows for enhanced applications in health and medical related areas. (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. Charging of aerosol and nucleation in atmospheric pressure electrical discharges

    Energy Technology Data Exchange (ETDEWEB)

    Borra, J P [Laboratoire de Physique des Gaz et Plasmas, CNRS-Univ. Paris-Sud, F-91405, SUPELEC, 3 Rue Joliot Curie, Gif-sur-Yvette, F-91192 (France)], E-mail: jp.borra@pgp.u-psud.fr

    2008-12-15

    The paper focuses on applications of atmospheric pressure plasmas (dc corona, streamer, spark and ac dielectric barrier discharges (DBDs)) in aerosol processes for materials and environment. Since aerosol kinematics depends mainly on electric forces acting on charged particles, the two mechanisms of aerosol charging by the collection of ions are presented in corona, post-corona and DBDs. In such defined charging conditions, field and diffusion charging laws are depicted, with respect to applications of controlled kinematics of charged aerosol. Then key parameters controlling the formation by nucleation and the growth by coagulation of particles in plasmas are presented. Sources of vapor leading to nucleated nanoparticles are depicted in atmospheric pressure electrical discharges: (i) when filamentary dc streamer and spark as well as ac-DBDs interact with metal or dielectric surfaces and (ii) when discharges induce reactions with gaseous precursors in volume. In both cases, condensable gaseous species are produced, leading to nano-sized particles by physical and chemical routes of nucleation. The composition, size and structure of primary nanoparticles as well as the final size of agglomerates are related to plasma parameters (energy, number per unit surface and time and thermal gradients around each filament as well as the transit time)

  18. 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.

  19. 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

  20. Etching process of silicon dioxide with nonequilibrium atmospheric pressure plasma

    International Nuclear Information System (INIS)

    An ultrahigh etch rate (14 μm/min) of SiO2 and a high selectivity of SiO2/Si over 200 were achieved using a microwave-excited nonequilibrium atmospheric pressure plasma source employing He, NF3, and H2O gases, which have been developed for application to microelectromechanical systems and other bionanotechnology fields. In order to clarify the etching mechanism, two diagnostic methods have been performed: (1) imaging of plasma emission with an intensified charge-coupled device camera, and (2) absorption measurements using Fourier transform infrared spectroscopy. The etching characteristics are discussed in relation to the spatial distributions of the species involved. The etch rate depended considerably on the distance between the plasma and the substrate. Some radicals generated from the feed gases reached the substrate directly, while other radicals recombined into different species, which reached the substrate. An abundance of HF molecules were produced through a reaction between radicals generated by the atmospheric pressure discharge of NF3 and H2O. From these measurements, it has been found that the HF molecules generated played a role in producing the high etch rate of SiO2 and high etch selectivity of SiO2/Si

  1. 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)

  2. Atmospheric pressure plasma jet for treatment of polymers

    Directory of Open Access Journals (Sweden)

    M. Wolter

    2009-12-01

    Full Text Available Purpose: Polymers are commonly used as packing materials as well as for optical and microelectronic applications. For these purposes different requirements like impermeability for different gases, scratching firmness and electrical conductivity are demanded. Since, polymers usually do not exhibit these attributes a surface modification is necessary.Design/methodology/approach: This paper describes possibilities for coating of polymers with a cold atmospheric pressure plasma jet (APPJ. Due to the rather low temperature of the process the plasma jet is suitable for the treatment of temperature-sensitive materials with melting points below 150°C. For coating of polymers the organic precursor Hexamethyldisiloxane (HMDSO has been used to deposit silicon oxide layers on surface.Findings: Spatial distributions of reactive species have been measured by optical emission spectroscopy (OES in the range between 280 and 1100 nm during the plasma process. The energy influx to the substrate was determined by thermal probe measurements. For the affirmation of the chemical composition of the surface X-ray photon spectroscopy (XPS has been performed.Practical implications: It could be confirmed that SiOx thin film deposition on polymeric substrate using commercially available APPJ with no internal precursor feeding is possible.Originality/value: The examinations of atmospheric pressure plasma jet for treatment of polymers.

  3. 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.

  4. 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)

  5. 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.

  6. The influence of atmospheric pressure on landfill methane emissions

    International Nuclear Information System (INIS)

    Landfills are the largest source of anthropogenic methane (CH4) emissions to the atmosphere in the United States. However, few measurements of whole landfill CH4 emissions have been reported. Here, we present the results of a multi-season study of whole landfill CH4 emissions using atmospheric tracer methods at the Nashua, New Hampshire Municipal landfill in the northeastern United States. The measurement data include 12 individual emission tests, each test consisting of 5-8 plume measurements. Measured emissions were negatively correlated with surface atmospheric pressure and ranged from 7.3 to 26.5 m3 CH4 min-1. A simple regression model of our results was used to calculate an annual emission rate of 8.4x106 m3 CH4 year-1. These data, along with CH4 oxidation estimates based on emitted landfill gas isotopic characteristics and gas collection data, were used to estimate annual CH4 generation at this landfill. A reported gas collection rate of 7.1x106 m3 CH4 year-1 and an estimated annual rate of CH4 oxidation by cover soils of 1.2x106 m3 CH4 year-1 resulted in a calculated annual CH4 generation rate of 16.7x106 m3 CH4 year-1. These results underscore the necessity of understanding a landfill's dynamic environment before assessing long-term emissions potential

  7. 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)

  8. 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).

  9. 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.

  10. 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

  11. 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

  12. Use of Pressure Fluctuations to Determine Online the Regime of Gas-Solids Suspensions from Incipient Fluidization to Transport

    Czech Academy of Sciences Publication Activity Database

    Hartman, Miloslav; Trnka, Otakar; Svoboda, Karel

    2009-01-01

    Roč. 48, č. 14 (2009), s. 6830-6835. ISSN 0888-5885 R&D Projects: GA AV ČR IAA400720701 Institutional research plan: CEZ:AV0Z40720504 Keywords : fluidized beds * fluidization regimes * pressure fluctuations Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.758, year: 2009

  13. 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.

  14. 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

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

    International Nuclear Information System (INIS)

    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

  16. 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.

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

    International Nuclear Information System (INIS)

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

  18. A dielectric barrier discharge in neon at atmospheric pressure

    International Nuclear Information System (INIS)

    A dielectric barrier discharge in neon at atmospheric pressure is investigated with electrical measurement and fast photography. It is found that a stable diffuse discharge can be easily generated in a gap with a gap space of 0.5-6 mm and is identified with a glow discharge. The first breakdown voltage of the gap is considerably higher than that of the same gap working in a stable diffuse discharge mode, which indicates that Penning ionization of neon metastables from the previous discharge with inevitable gas impurities plays an important role in the decrease in the breakdown voltage. Discharge patterns are observed in a gap shorter than 1 mm. From the experiments with a wedge-like gap, it is found that the discharge patterns are formed in the area with a higher applied electric field, which suggests that a higher applied electric field may cause a transition from a diffuse glow to discharge patterns.

  19. 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...

  20. 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.

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

    International Nuclear Information System (INIS)

    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

  2. Plasmid DNA damage induced by helium atmospheric pressure plasma jet

    Science.gov (United States)

    Han, Xu; Cantrell, William A.; Escobar, Erika E.; Ptasinska, Sylwia

    2014-03-01

    A helium atmospheric pressure plasma jet (APPJ) is applied to induce damage to aqueous plasmid DNA. The resulting fractions of the DNA conformers, which indicate intact molecules or DNA with single- or double-strand breaks, are determined using agarose gel electrophoresis. The DNA strand breaks increase with a decrease in the distance between the APPJ and DNA samples under two working conditions of the plasma source with different parameters of applied electric pulses. The damage level induced in the plasmid DNA is also enhanced with increased plasma irradiation time. The reactive species generated in the APPJ are characterized by optical emission spectra, and their roles in possible DNA damage processes occurring in an aqueous environment are also discussed.

  3. 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

  4. 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.

  5. Controlling the NO production of an atmospheric pressure plasma jet

    International Nuclear Information System (INIS)

    The production of NO radicals by an atmospheric pressure plasma jet has been investigated by means of absorption spectroscopy in the mid-infrared region (IR) and optical emission spectroscopy (OES) in the ultraviolet (UV) part of the spectrum. The plasma jet investigated here operates in argon with air admixtures up to 1%. The study shows that OES can be used to characterize the relative NO production at small air admixtures. The Production of NO radicals can be controlled by variation of air admixture. Important to note—especially for operation in ambient conditions—is that a small addition of water vapour strongly affects the production of NO radicals especially at higher air admixtures (greater than 0.2%). (paper)

  6. Analysis of the cathodic region of atmospheric pressure discharges

    International Nuclear Information System (INIS)

    The cathodic region of atmospheric pressure arcs is dominated by a number of different mechanisms. This makes a theoretical model extremely difficult. A description of this region based on fundamental physical principles is given. Using a previously published model of the inhomogeneous boundary layer of a Saha plasma (Schmitz H and Riemann K-U 2001 J. Phys. D: Appl. Phys. 34 1193), the description is set on a firm theoretical basis. A number of equations including the energy balances of plasma boundary and cathode body lead to a maximum closure of the system. The values for the boundary conditions toward the plasma column could be motivated by a simple minimum principle argument thus eliminating all arbitrary fitting parameters. Results are given for a variety of external parameters and three different discharge gases. The comparison with experimental results shows excellent agreement. (author)

  7. Surface wave propagation characteristics in atmospheric pressure plasma column

    Science.gov (United States)

    Pencheva, M.; Benova, E.; Zhelyazkov, I.

    2007-04-01

    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.

  8. Surface wave propagation characteristics in atmospheric pressure plasma column

    Energy Technology Data Exchange (ETDEWEB)

    Pencheva, M [Faculty of Physics, Sofia University, 5 James Bourchier Blvd., BG-1164 Sofia (Bulgaria); Benova, E [Department for Language Teaching and International Students, Sofia University, 27 Kosta Loulchev Street, BG-1111 Sofia (Bulgaria); Zhelyazkov, I [Faculty of Physics, Sofia University, 5 James Bourchier Blvd., BG-1164 Sofia (Bulgaria)

    2007-04-15

    In the typical experiments of surface wave sustained plasma columns at atmospheric pressure the ratio of collision to wave frequency ({nu}/{omega}) is much greater than unity. Therefore, one might expect that the usual analysis of the wave dispersion relation, performed under the assumption {nu}/{omega} = 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 {nu}/{omega}. 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.

  9. 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.

  10. Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces

    International Nuclear Information System (INIS)

    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

  11. 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...

  12. 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.

  13. 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

  14. Bacterial Inactivation by Atmospheric Pressure Dielectric Barrier Discharge Plasma Jet

    Science.gov (United States)

    Deng, Sanxi; Cheng, Cheng; Ni, Guohua; Meng, Yuedong; Chen, Hua

    2008-08-01

    Bacillus subtilis and Escherichia coli seeded in two media (agar and filter papers) were exposed to after-glow plasma emitted from a atmospheric pressure dielectric barrier discharge (DBD) plasma jet generator in open air with a temperature of about 30-80 °C. In order to estimate the inactivation of microorganism using DBD plasma jet, various plasma conditions (such as treatment time and feed-gas composition of plasma jet) were changed. The results shown that the effective area of inactivation increased with the plasma treatment time as the bacteria seeded in Agar medium. The effective area of inactivation was much bigger than plasma jet treatment area after 5 min treatment. With the use of filter papers as the supporting media, the addition of reactive gases (oxygen, hydrogen peroxide vapor) into the plasma jet system, compared with only pure noble gas, led to a significant improvement in the bacterial Inactivation efficacy.

  15. Deposition of carbon nanostructures on metal substrates at atmospheric pressure

    Science.gov (United States)

    Dimitrov, Zh; Nikovski, M.; Kiss'ovski, Zh

    2016-03-01

    The microwave-plasma-enhanced CVD of carbon nanostructures at atmospheric pressure allows shorter deposition times and reduces the complexity of the experimental set-up. In our study, the substrate temperature was varied in a wide range (300 – 700 C) using microwave plasma heating, as well as an additional heater. The distance between the substrate and the plasma flame was also varied in order to establish the conditions for an efficient deposition process, the latter being carried out at specific argon/hydrogen/methane gas mixtures. Optical measurements of the plasma flame spectrum were conducted to obtain the gas temperature and the plasma density and to analyze the existence of reactive species. The carbon nanostructures deposited on the metal samples were investigated by SEM. The relation between the morphology and the gas-discharge conditions is discussed.

  16. 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.

  17. 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.

  18. 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

  19. 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.

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

    International Nuclear Information System (INIS)

    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

  1. 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.

  2. Comparison of electrospray ionization, atmospheric pressure chemical ionization and atmospheric pressure photoionization for a lipidomic analysis of Leishmania donovani.

    Science.gov (United States)

    Imbert, Laurent; Gaudin, Mathieu; Libong, Danielle; Touboul, David; Abreu, Sonia; Loiseau, Philippe M; Laprévote, Olivier; Chaminade, Pierre

    2012-06-15

    A comparison of electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) for the analysis of a wide range of lipids has been performed on standard mixtures and extracts of Leishmania donovani promastigotes resistant to Amphotericin B (AmB). Calibration model, precision, limits of detection and quantification (LOD and LOQ) were assessed for each source. APPI provided the highest signal, signal-to-noise (S/N), and sensitivity for non-polar and low-polarity lipids, while ESI and APCI gave better results for the most polar ones. The linear model was valid for all lipids, except for one class with APPI, six classes with ESI, and eleven classes with APCI. LODs ranged from 0.2 to 20 μg mL(-1) for ESI, from 0.1 to 10 μg mL(-1) for APCI, and from 0.02 to 9.5 μg mL(-1) for APPI. LOQs ranged from 0.2 to 61 μg mL(-1) for ESI, from 0.4 to 31 μg mL(-1) for APCI, and from 0.1 to 29 μg mL(-1) for APPI. Each source provided similar lipid composition and variations in a comparison of three different L. donovani samples: miltefosine-treated, miltefosine-resistant and treated miltefosine-resistant parasites. A treated miltefosine-resistant sample was finally analyzed with each ion source in order to verify that the same lipid molecular species are detected. PMID:22560453

  3. 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. PMID:25828352

  4. 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

  5. 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,...

  6. Partial pharmacologic blockade shows sympathetic connection between blood pressure and cerebral blood flow velocity fluctuations.

    Science.gov (United States)

    Hilz, Max J; Wang, Ruihao; Marthol, Harald; Liu, Mao; Tillmann, Alexandra; Riss, Stephan; Hauck, Paulina; Hösl, Katharina M; Wasmeier, Gerald; Stemper, Brigitte; Köhrmann, Martin

    2016-06-15

    Cerebral autoregulation (CA) dampens transfer of blood pressure (BP)-fluctuations onto cerebral blood flow velocity (CBFV). Thus, CBFV-oscillations precede BP-oscillations. The phase angle (PA) between sympathetically mediated low-frequency (LF: 0.03-0.15Hz) BP- and CBFV-oscillations is a measure of CA quality. To evaluate whether PA depends on sympathetic modulation, we assessed PA-changes upon sympathetic stimulation with and without pharmacologic sympathetic blockade. In 10 healthy, young men, we monitored mean BP and CBFV before and during 120-second cold pressor stimulation (CPS) of one foot (0°C ice-water). We calculated mean values, standard deviations and sympathetic LF-powers of all signals, and PAs between LF-BP- and LF-CBFV-oscillations. We repeated measurements after ingestion of the adrenoceptor-blocker carvedilol (25mg). We compared parameters before and during CPS, without and after carvedilol (analysis of variance, post-hoc t-tests, significance: p<0.05). Without carvedilol, CPS increased BP, CBFV, BP-LF- and CBFV-LF-powers, and shortened PA. Carvedilol decreased resting BP, CBFV, BP-LF- and CBFV-LF-powers, while PAs remained unchanged. During CPS, BPs, CBFVs, BP-LF- and CBFV-LF-powers were lower, while PAs were longer with than without carvedilol. With carvedilol, CPS no longer shortened resting PA. Sympathetic activation shortens PA. Partial adrenoceptor blockade abolishes this PA-shortening. Thus, PA-measurements provide a subtle marker of sympathetic influences on CA and might refine CA evaluation. PMID:27206903

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

    Science.gov (United States)

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

    2011-10-01

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

  8. Repetitive nanosecond glow discharge in atmospheric pressure air

    Science.gov (United States)

    Packan, Denis

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

  9. 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.

  10. Fluctuations of the orbital angular momentum of a laser beam, carrying an optical vortex, in the turbulent atmosphere

    International Nuclear Information System (INIS)

    The evolution of the orbital angular momentum (OAM) of a Laguerre-Gaussian beam interacting with turbulent inhomogeneities of the atmosphere is studied theoretically. The integral representations are obtained for the OAM in terms of the distributions of the random intensity and random field of the permittivity of the medium, and also for OAM statistical characteristics in terms of corresponding correlation functions. It is found that the average OAM value is preserved during the propagation of the laser beam in a random medium. The dependence of the dispersion of OAM fluctuations on the atmospheric turbulence and beam parameters is calculated. It is shown that the dependence of the OAM dispersion on the initial angular momentum of the laser beam disappears in the case of very strong turbulence. (laser beams)

  11. 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)

  12. Breakdown of atmospheric pressure microgaps at high excitation frequencies

    International Nuclear Information System (INIS)

    Microwave (mw) breakdown of atmospheric pressure microgaps is studied by a one-dimensional Particle-in-Cell Monte Carlo Collisions numerical model. The effect of both field electron emission and secondary electron emission (due to electron impact, ion impact, and primary electron reflection) from surfaces on the breakdown process is considered. For conditions where field emission is the dominant electron emission mechanism from the electrode surfaces, it is found that the breakdown voltage of mw microdischarge coincides with the breakdown voltage of direct-current (dc) microdischarge. When microdischarge properties are controlled by both field and secondary electron emission, breakdown voltage of mw microdischarge exceeds that of dc microdischarge. When microdischarge is controlled only by secondary electron emission, breakdown voltage of mw microdischarge is smaller than that of dc microdischarge. It is shown that if the interelectrode gap exceeds some critical value, mw microdischarge can be ignited only by electrons initially seeded within the gap volume. In addition, the influence of electron reflection and secondary emission due to electron impact is studied

  13. 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.

  14. 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.

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

    Science.gov (United States)

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

    2015-07-01

    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/O2 = 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.

  16. Temperature profiles in filamentary dielectric barrier discharges at atmospheric pressure

    International Nuclear Information System (INIS)

    Physico-chemical properties of atmospheric pressure filamentary dielectric barrier discharges (f-DBD) depend on coupled electrical characteristics and thermal profiles. In this paper, a method for studying thermal and electrical effects is developed. Therefore, thermal profiles of f-DBD are studied for well-defined electrical characteristics of quasi-identical filaments with controlled distribution in time and space. The temperatures of gas, dielectric surface and plasma depend on the surface density and on the temporal frequency of filaments, defining the input power, and can be tuned by controlling heat transfers. Different methods to control these temperatures are depicted. Moreover, heat transfer through conduction and convection from dielectric surface is shown to be the dominant heating mechanism of the flowing gas in the reactor. Finally, experimental results show that the local temperature gradient around each filament can be controlled by the frequency of the applied voltage. Actually, the temperature difference between the filament and the surrounding gas is constant below 10 kHz but increases linearly with the frequency above 10 kHz. At high frequency, the time between two successive filaments occurring at the same position becomes smaller than the relaxation time constant of thermal exchanges (∼0.1 ms). Hence, this rise in local temperature can be attributed to time-limited heat transfers from the filament axis.

  17. Temperature profiles in filamentary dielectric barrier discharges at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Jidenko, N; Bourgeois, E; Borra, J-P [Laboratoire de Physique des Gaz et des Plasmas (UMR 8578 CNRS-Univ Paris-Sud Orsay, F-91405) SUPELEC, Plateau Moulon, F-91192 Gif-Sur-Yvette (France)

    2010-07-28

    Physico-chemical properties of atmospheric pressure filamentary dielectric barrier discharges (f-DBD) depend on coupled electrical characteristics and thermal profiles. In this paper, a method for studying thermal and electrical effects is developed. Therefore, thermal profiles of f-DBD are studied for well-defined electrical characteristics of quasi-identical filaments with controlled distribution in time and space. The temperatures of gas, dielectric surface and plasma depend on the surface density and on the temporal frequency of filaments, defining the input power, and can be tuned by controlling heat transfers. Different methods to control these temperatures are depicted. Moreover, heat transfer through conduction and convection from dielectric surface is shown to be the dominant heating mechanism of the flowing gas in the reactor. Finally, experimental results show that the local temperature gradient around each filament can be controlled by the frequency of the applied voltage. Actually, the temperature difference between the filament and the surrounding gas is constant below 10 kHz but increases linearly with the frequency above 10 kHz. At high frequency, the time between two successive filaments occurring at the same position becomes smaller than the relaxation time constant of thermal exchanges ({approx}0.1 ms). Hence, this rise in local temperature can be attributed to time-limited heat transfers from the filament axis.

  18. Mass spectrometric diagnosis of an atmospheric pressure helium microplasma jet

    International Nuclear Information System (INIS)

    Ambient molecular beam mass spectrometry (MBMS) has been used to study how different capillary widths (530 µm and 2.4 mm) and excitation waveforms (continuous wave kHz and pulsed dc) affect the ionic composition of atmospheric pressure plasma jets. It is shown from time-averaged ion intensities that reducing the width of the jet capillary results in a significant increase in the variety of both positive and negative ions detected within the discharge. We discuss this in terms of changes in flow velocity and the onset of turbulence within the plasma plume. Changing the mode of excitation had little effect on the ionic species detected from the microplasma jet; however, there was a notable shift in dominance towards higher mass ions when operated in a continuous wave kHz mode. The temporal evolution of the ions within the microplasma jet was observed for both excitation sources, operated at 5 and 15 kHz. Positive ions were created during periods correlated with the positive and negative peaks in discharge current, while negative ions were predominantly created at times when the discharge current peak was negative. This phenomenon was independent of the driving waveform. For pulsed dc excitation, considerably fewer positive ions were created in periods related to the negative current peaks, especially at higher frequencies. We propose a simple explanation for these processes based on ideas of streamer propagation and the influence of self-induced electric fields in the plasma plume. (paper)

  19. 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.

  20. Gas flow dependence of atmospheric pressure plasma needle discharge characteristics

    Science.gov (United States)

    Qian, Muyang; Yang, Congying; Liu, Sanqiu; Chen, Xiaochang; Ni, Gengsong; Wang, Dezhen

    2016-04-01

    In this paper, a two-dimensional coupled model of neutral gas flow and plasma dynamics is presented to explain the gas flow dependence of discharge characteristics in helium plasma needle at atmospherics pressure. The diffusional mixing layer between the helium jet core and the ambient air has a moderate effect on the streamer propagation. The obtained simulation results present that the streamer shows the ring-shaped emission profile at a moderate gas flow rate. The key chemical reactions which drive the streamer propagation are electron-impact ionization of helium neutral, nitrogen and oxygen molecules. At a moderate gas flow rate of 0.5 slm, a significant increase in propagation velocity of the streamer is observed due to appropriate quantity of impurities air diffuse into the helium. Besides, when the gas flow rate is below 0.35 slm, the radial density of ground-state atomic oxygen peaks along the axis of symmetry. However, when the gas flow rate is above 0.5 slm, a ring-shaped density distribution appears. The peak density is on the order of 1020 m-3 at 10 ns in our work.

  1. 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.

  2. 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.

  3. Microemulsion electrokinetic chromatography hyphenated to atmospheric pressure photoionization mass spectrometry.

    Science.gov (United States)

    Schappler, Julie; Guillarme, Davy; Rudaz, Serge; Veuthey, Jean-Luc

    2008-01-01

    CZE is an appropriate technique for separating charged species, but lacks selectivity for neutral compounds. Alternative approaches such as microemulsion electrokinetic chromatography (MEEKC) have been developed to broaden its range of applications. Hyphenation of MEEKC with MS is an attractive perspective since it can enhance sensitivity and selectivity. The on-line coupling of MEEKC with MS, however, is not straightforward due to the low compatibility of non-volatile surfactant additives (e.g. SDS) and the commonly used API source, namely ESI. In order to hyphenate MEEKC with MS detection, the atmospheric pressure photoionization (APPI) source was investigated. Possibilities offered by the coupling of MEEKC with APPI-MS were highlighted for the complex separation of ionized and neutral compounds in both the positive and negative modes. MEEKC-APPI-MS performance, in terms of selectivity, efficiency and sensitivity was compared to CZE-ESI-MS and MEEKC-ESI-MS for the screening of doping substances (beta-blockers, central stimulants, diuretics, etc). Relevant selectivity and detectability, particularly for neutral, structurally related and isobaric compounds was demonstrated with the MEEKC-APPI-MS approach opening new avenues for CE-MS, in addition to the well-established CZE-ESI-MS technique. PMID:18161697

  4. 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

  5. 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.

  6. 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

  7. 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.

  8. A laboratory scale piezoelectric array for underwater measurements of the fluctuating wall pressure beneath turbulent boundary layers

    International Nuclear Information System (INIS)

    To capture the full spectrum of the fluctuating wall pressure beneath a turbulent boundary layer (TBL) provides a unique challenge in transducer design. This paper discusses the design, construction and testing of an array of surface-mounted piezoelectric ceramic elements with the goal of having both the spatial resolution and the frequency bandwidth to accurately sense the low-frequency, low-wavenumber events beneath a TBL at moderately low Reynolds numbers. The array is constructed from twenty 1.27 cm tall prismatic rods with 0.18 cm × 0.16 cm cross-section made of Navy type II piezoelectric ceramic material. Calibration was performed by comparing the response of a Navy H56 precision-calibrated hydrophone to the outputs of each element on the array for a given input from a Navy J9 projector. The elements show an average sensitivity of −184 dB (re: 1 V μPa−1) and are assembled with a centre-to-centre spacing of 0.2 cm. Measurements of the fluctuating wall pressure below a 2d TBL with Reynolds numbers (based on momentum thickness) ranging from 2100 to 4300 show that the dimensions of the elements are between 64 and 107 viscous length units, respectively. A spatial and temporal footprint of the fluctuating wall pressure reveals convective speeds averaging 75% of the free stream velocity. (paper)

  9. 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.

  10. 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

  11. 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.

  12. 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

  13. Forbush-effects and atmospheric pressure dynamics at high-altitude Tien Shan station

    International Nuclear Information System (INIS)

    We present atmospheric pressure dynamics studies at the high-altitude Tien Shan station (3340 m above sea level) during 23rd cycle of solar activity after Forbush-effects. It is established that 80 % of Forbush effects with delay 1 ÷ 3 days are accompanied with steady depression of atmospheric pressure irrespective of geomagnetic field conditions. We found that atmospheric pressure dynamics at mountains and ground levels during investigated periods is different. Experimental results are compared with possible mechanisms of influence of sporadic effects of solar activity on circulation of the lower atmosphere.

  14. Steps Toward Real-Time Atmospheric Phase Fluctuation Correction for a High Resolution Radar System

    Science.gov (United States)

    Denn, Grant R.; Geldzahler, Barry; Birr, Rick; Brown, Robert; Hoblitzell, Richard; Grant, Kevin; Miller, Michael; Woods, Gary; Archuleta, Arby; Ciminera, Michael; Cornish, Timothy; davarian, faramaz; kocz, jonathan; lee, dennis; Morabito, David Dominic; Soriano, Melissa; Tsao, Philip; Vilnrotter, Victor; Jakeman-Flores, Hali; Ott, melanie; Thomes, W. Joe; Soloff, Jason; NASA Kennedy Space Center, Jet Propulsion Laboratory, NASA Goddard Space Flight Center, NASA Johnson Space Flight Center, Metropolitan State University of Denver

    2016-01-01

    NASA is pursuing a demonstration of coherent uplink arraying at 7.145-7.190 GHz (X-band) and 30-31 GHz (Ka-band) using three 12m diameter COTS antennas separated by 60m at the Kennedy Space Center in Florida, with the goal of a high-power, high-resolution radar array that employs real-time correction for tropospheric phase fluctuation. The major uses for this array will be (a) observations of Near Earth Objects, (b) detection and tracking of orbital debris, (c) high power emergency uplink capability for spacecraft, and (d) radio science experiments.

  15. 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

  16. Pulsed microwave discharge at atmospheric pressure for NOx decomposition

    International Nuclear Information System (INIS)

    A 3.0 GHz pulsed microwave source operated at atmospheric pressure with a pulse power of 1.4 MW, a maximum repetition rate of 40 Hz, and a pulse length of 3.5 μs is experimentally studied with respect to the ability to remove NOx from synthetic exhaust gases. Experiments in gas mixtures containing N2/O2/NO with typically 500 ppm NO are carried out. The discharge is embedded in a high-Q microwave resonator, which provides a reliable plasma ignition. Vortex flow is applied to the exhaust gas to improve gas treatment. Concentration measurements by Fourier transform infrared spectroscopy confirm an NOx reduction of more than 90% in the case of N2/NO mixtures. The admixture of oxygen lowers the reductive potential of the reactor, but NOx reduction can still be observed up to 9% O2 concentration. Coherent anti-Stokes Raman scattering technique is applied to measure the vibrational and rotational temperature of N2. Gas temperatures of about 400 K are found, whilst the vibrational temperature is 3000-3500 K in pure N2. The vibrational temperature drops to 1500 K when O2 and/or NO are present. The randomly distributed relative frequency of occurrence of selected breakdown field intensities is measured by a calibrated, short linear-antenna. The breakdown field strength in pure N2 amounts to 2.2x106 V m-1, a value that is reproducible within 2%. In the case of O2 and/or NO admixture, the frequency distribution of the breakdown field strength scatters more and extends over a range from 3 to 8x106 V m-1

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

    International Nuclear Information System (INIS)

    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/O2 = 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

  18. 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)

  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. 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.

  1. 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...

  2. 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.

  3. 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

    2016-05-01

    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.

  4. Study on mechanism of pressure fluctuation in a primary circuit hot-leg pipings of a sodium-cooled fast reactor

    International Nuclear Information System (INIS)

    In a conceptual design of Japan Sodium-cooled Fast Reactor (JSFR), short-elbow pipings with large-diameter are adopted for cooling system, in which the coolant flow causes periodical pressure fluctuation at the short-elbow. However, the mechanism of the periodical pressure fluctuation has not been clarified yet. In this paper, unsteady three-dimensional analysis by a finite element large-eddy-simulation (LES) code is carried out in order to explore the mechanism of the periodical pressure fluctuation in short-elbow pipings, based on visualizations of dynamic flow structure in the numerical results. (author)

  5. Applications of a versatile technique for trace analysis: atmospheric pressure negative chemical ionization.

    OpenAIRE

    Thomson, B A; Davidson, W R; Lovett, A M

    1980-01-01

    The ability to use ambient air as a carrier and reagent gas in an atmospheric pressure chemical ionization source allows instantaneous air analysis to be combined with hypersensitivity toward a wide variety of compounds. The TAGA (Trace Atmospheric Gas Analyser) is an instrument which is designed to use both positive and negative atmospheric pressure chemical ionization (APCI) for trace gas analysis; this paper describes several applications of negative APCI which demonstrates that the techni...

  6. 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.

  7. 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.

  8. 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.

  9. 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...

  10. 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.

  11. 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.; Kjeldsen, Peter

    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...

  12. 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

  13. Time-frequency analysis of Hilbert spectrum of pressure fluctuation time series in a Kenics Static Mixer based on empirical mode decomposition

    Directory of Open Access Journals (Sweden)

    Huibo Meng

    2012-03-01

    Full Text Available The turbulent flow in a Kenics Static Mixer (KSM was intensified under the mutual-coupling effect between the twisted leaves and the tube-wall. In order to understand the intrinsic features of turbulent flow in KSM, the Hilbert-Huang Transform based on Empirical Mode Decomposition were first introduced to describe the time-frequency features of the pressure fluctuation. The Hilbert spectra of pressure fluctuation time series were quantitatively evaluated under different Reynolds numbers, and different radial and axial positions, respectively. The experimental results showed that: the fluctuation frequencies of pressure signals in a KSM were mainly distributed below 40 Hz, and more than 68% of the energy of signals is concentrated within 10 Hz. Compared with the other IMFs, the pressure component of C6 in the range of 7.82~15.63 Hz has the maximum fluctuation energy ratio. As the flow rate increases, the energy of fluctuation of fluid micelles and the proportion of low-frequency energy increases. The pressure fluctuation with higher energy ratio of low frequency (0~10 Hz had lower amplitudes at r/R=0.3 because of the core of forced vortex. Nevertheless, the effect of the free vortex was that the pressure fluctuation with lower energy ratio of low frequency had higher amplitudes at r/R=0.8. The higher amplitudes of pressure fluctuation at cross sections of CS3 (z=420 mm and CS5 (z=620 mm proved that the transitions between the adjacent mixing element had better mixing performance.

  14. Effect that atmospheric pressure exerts to DC tracking of polyethylene irradiated with gamma ray

    International Nuclear Information System (INIS)

    In the testing method of tracking resistance carried out generally, particular stipulation is not made on atmospheric pressure. But there is the case that electric and electronic equipments are used in the place of low pressure. The lowering of atmospheric pressure affects the phenomenon of tracking deterioration, and it is sufficiently conceivable that tracking resistance changes. So far, the effect that atmospheric pressure exerts on tracking resistance at the time of applying AC voltage has been mainly studied, however recently, DC voltage has become widely utilized, and the elucidation of DC tracking phenomena has become important. The experiment of irradiating Co-60 gamma ray to polyethylene and obtaining the basic data on the effect that atmospheric pressure exerts to DC tracking using those samples was carried out. The experimental setup, the samples and the tracking resistance test are reported. The relation of the weight loss with atmospheric pressure, the relation of the maximum erosion depth and atmospheric pressure, the measurement of the amount of residual carbide and the tracking resistance using brass electrodes are described. (K.I.)

  15. 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.

  16. 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

  17. Applications of tunable high energy/pressure pulsed lasers to atmospheric transmission and remote sensing

    Science.gov (United States)

    Hess, R. V.; Seals, R. K.

    1974-01-01

    Atmospheric transmission of high energy C12 O2(16) lasers were improved by pulsed high pressure operation which, due to pressure broadening of laser lines, permits tuning the laser 'off' atmospheric C12 O2(16) absorption lines. Pronounced improvement is shown for horizontal transmission at altitudes above several kilometers, and for vertical transmission through the entire atmosphere. The atmospheric transmission of tuned C12 O2(16) lasers compares favorably with C12 O2(18) isotope lasers and CO lasers. The advantages of tunable, high energy, high pressure pulsed lasers over tunable diode lasers and waveguide lasers, in combining high energies with a large tuning range, are evaluated for certain applications to remote sensing of atmospheric constituents and pollutants. Pulsed operation considerably increases the signal to noise ratio without seriously affecting the high spectral resolution of signal detection obtained with laser heterodyning.

  18. 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.

  19. 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.

  20. Estimating Global Natural Wetland Methane Emissions Using Process Modeling: The Spatiotemporal Patterns and the Contributions to Atmospheric Methane Fluctuations

    Science.gov (United States)

    Zhu, Q.; Peng, C.; Liu, J.; Fang, X.; Jiang, H.

    2014-12-01

    Global wetland methane (CH4) emissions and its spatiotemporal patterns were evaluated using a new process-based model called TRIPLEX-GHG. The model was developed based on the Integrated Biosphere Simulator (IBIS), coupled with a new CH4 biogeochemistry module and a water table module to simulate CH4 emission processes in natural wetlands. The model has been validated using a number of field observations successfully. This study reported the initial results of global scale application, including total CH4 emissions, spatiotemporal patterns, and contributions to the atmospheric CH4 fluctuations. Global annual wetland CH4 emission ranged from 150 TgC yr-1 to 174 TgC yr-1 between 1901 and 2012 with the peak occurring in 1991 and 2012. Between 1990 and 2010, global CH4 emission decreased with a rate of approximately 0.38 TgC yr-1. It was largely due to the decrease of CH4 emissions from topical wetlands, which had a decreasing trend with a rate of 0.33 TgC yr-1 since the 1970s. CH4 emissions from tropical, temperate, and high latitude wetlands comprised 63%, 22% and 15% of global CH4 emission, respectively. Tropical wetlands are the primary contributor of the inter-annual variability of global wetland CH4 emissions as well as atmospheric CH4. The stable-to-decreasing wetland CH4 emissions owing to the balance of emissions between tropical and extratropical wetlands was a contributing factor to the slow-down atmospheric CH4 growth rate during 1990s. The rapid drop in tropical wetland CH4 emissions from 2000 onwards is supposed to offset the increases of the anthropogenic CH4 emissions, hence leading to a relatively stable level of atmospheric CH4 during 2000-2006. Increases of wetland CH4 emissions particularly after 2010 can be considered as an important contributor to the resumed growth of atmospheric CH4 since 2007 and for further increasing in the near future.

  1. The 1991-1992 atmospheric methane anomaly: Southern hemisphere 13C decrease and growth rate fluctuations

    Science.gov (United States)

    Lowe, David C.; Manning, Martin R.; Brailsford, G. W.; Bromley, A. M.

    Measurements of atmospheric methane from 1989-1996 at Baring Head, New Zealand, and at Scott Base, Antarctica show a seasonal cycle in the mixing ratio with a peak to peak amplitude of 28 ppb. This is superposed on a trend varying between 16 ppb yr-1 and near zero. δ13C values also show a seasonal cycle, with an amplitude of 0.1-0.3‰, approximately 6 months out of phase with the mixing ratio cycle. A pronounced negative anomaly in δ13C occurred in 1992 with annual average values dropping from -47.08‰ to -47.28‰. From 1992 to 1996, average δ13C values recovered slowly at an average rate of about 0.04‰ yr-1. The simultaneous changes in the mixing ratio growth rate and δ13C together with the rapid drop and slow recovery in the latter provide a stringent test of possible causes. Although a combination of causes cannot be ruled out, decreased emissions from an isotopically heavy source such as biomass burning best meet the constraints of the data.

  2. 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...

  3. Development of propulsion for high atmospheric pressure or dense environments

    Science.gov (United States)

    Varsi, G.; Back, L. H.; Dowler, W. L.

    1973-01-01

    The development of a propulsion system that employs a detonating propellant is described, and the need for such a system and its use in certain planetary atmospheres are demonstrated. A theoretical formulation of the relevant gas-dynamic processes was developed, and a related series of experimental tests were pursued.

  4. 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

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. Strong-Coupling Calculation of Fluctuation Pressure of a Membrane Between Walls

    OpenAIRE

    Bachmann, M; Kleinert, H.; Pelster, A.

    1999-01-01

    We calculate analytically the proportionality constant in the pressure law of a membrane between parallel walls from the strong-coupling limit of variational perturbation theory up to third order. Extrapolating the zeroth to third approximations to infinity yields the pressure constant alpha=0.0797149. This result lies well within the error bounds of the most accurate available Monte-Carlo result 0.0798 +- 0.0003.

  10. A new humane method of stunning broilers using low atmospheric pressure

    Science.gov (United States)

    This research project evaluated an alternative method of controlled atmosphere stunning of commercial broilers to induce anoxia utilizing a vacuum pump to reduce the oxygen tension, low atmospheric pressure stun (LAPS). A custom built 2 cage-module system (holding a total of 600 broilers each) with...

  11. 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.

  12. Statistical Fluctuation in Gas Amplification Factor of a Low-Pressure Proportional Counter

    International Nuclear Information System (INIS)

    Full text: The electron avalanche formation in low-pressure argon-based gas mixtures at strong non-uniform electric fields was studied by a proportional counter. Concentration of admixtures (propane, DME, isobutane) varied between 1% and 80% and total pressures from 2 kPa to 90 kPa. Gas amplification M and energy resolution R were measured by the 55Fe source as a function of admixture concentration and total gas pressure. The relative variance f of the avalanche size distribution was determined by measuring single-electron (SE) spectra. In pure gases and in mixtures with high content of the admixture, the SE spectra have always a peaked distribution, f1. The f value depends on the partial pressure p of the admixture and on M. Over-exponential increase of gas gain with high voltage above a certain gas gain, M0, was determined in all mixtures. The gas gain where the SE spectra change their shape, f∼1, is roughly equal to M0. Both effects in M and f are caused by avalanche chain formation due to insufficient quenching of the admixture. Energy resolution is directly determined by the f-value, therefore, in 'thin' mixtures above M0 it degrades very quickly. Since this limiting value M0 depends on p, we conclude that partial pressure should be above ∼10 kPa to assure good quenching even at the highest gains obtained in the present experiment. (author)

  13. Terrestrial Gravity Fluctuations

    Directory of Open Access Journals (Sweden)

    Jan Harms

    2015-12-01

    Full Text Available Different forms of fluctuations of the terrestrial gravity field are observed by gravity experiments. For example, atmospheric pressure fluctuations generate a gravity-noise foreground in measurements with super-conducting gravimeters. Gravity changes caused by high-magnitude earthquakes have been detected with the satellite gravity experiment GRACE, and we expect high-frequency terrestrial gravity fluctuations produced by ambient seismic fields to limit the sensitivity of ground-based gravitational-wave (GW detectors. Accordingly, terrestrial gravity fluctuations are considered noise and signal depending on the experiment. Here, we will focus on ground-based gravimetry. This field is rapidly progressing through the development of GW detectors. The technology is pushed to its current limits in the advanced generation of the LIGO and Virgo detectors, targeting gravity strain sensitivities better than 10^–23 Hz^–1/2 above a few tens of a Hz. Alternative designs for GW detectors evolving from traditional gravity gradiometers such as torsion bars, atom interferometers, and superconducting gradiometers are currently being developed to extend the detection band to frequencies below 1 Hz. The goal of this article is to provide the analytical framework to describe terrestrial gravity perturbations in these experiments. Models of terrestrial gravity perturbations related to seismic fields, atmospheric disturbances, and vibrating, rotating or moving objects, are derived and analyzed. The models are then used to evaluate passive and active gravity noise mitigation strategies in GW detectors, or alternatively, to describe their potential use in geophysics. The article reviews the current state of the field, and also presents new analyses especially with respect to the impact of seismic scattering on gravity perturbations, active gravity noise cancellation, and time-domain models of gravity perturbations from atmospheric and seismic point sources. Our

  14. Terrestrial Gravity Fluctuations

    Science.gov (United States)

    Harms, Jan

    2015-12-01

    Different forms of fluctuations of the terrestrial gravity field are observed by gravity experiments. For example, atmospheric pressure fluctuations generate a gravity-noise foreground in measurements with super-conducting gravimeters. Gravity changes caused by high-magnitude earthquakes have been detected with the satellite gravity experiment GRACE, and we expect high-frequency terrestrial gravity fluctuations produced by ambient seismic fields to limit the sensitivity of ground-based gravitational-wave (GW) detectors. Accordingly, terrestrial gravity fluctuations are considered noise and signal depending on the experiment. Here, we will focus on ground-based gravimetry. This field is rapidly progressing through the development of GW detectors. The technology is pushed to its current limits in the advanced generation of the LIGO and Virgo detectors, targeting gravity strain sensitivities better than 10^-23 Hz^-1/2 above a few tens of a Hz. Alternative designs for GW detectors evolving from traditional gravity gradiometers such as torsion bars, atom interferometers, and superconducting gradiometers are currently being developed to extend the detection band to frequencies below 1 Hz. The goal of this article is to provide the analytical framework to describe terrestrial gravity perturbations in these experiments. Models of terrestrial gravity perturbations related to seismic fields, atmospheric disturbances, and vibrating, rotating or moving objects, are derived and analyzed. The models are then used to evaluate passive and active gravity noise mitigation strategies in GW detectors, or alternatively, to describe their potential use in geophysics. The article reviews the current state of the field, and also presents new analyses especially with respect to the impact of seismic scattering on gravity perturbations, active gravity noise cancellation, and time-domain models of gravity perturbations from atmospheric and seismic point sources. Our understanding of

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

    DEFF Research Database (Denmark)

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

    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...

  16. 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)

  17. 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.

  18. 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

  19. 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 constan...

  20. 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.)

  1. 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.

  2. 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.

  3. 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.

  4. 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

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

    Science.gov (United States)

    Askari, Sadegh; Macias-Montero, Manuel; Velusamy, Tamilselvan; Maguire, Paul; Svrcek, Vladmir; Mariotti, Davide

    2015-08-01

    The synthesis of silicon and silicon-based quantum dots (diameter 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.

  6. Modelling of microwave sustained capillary plasma columns at atmospheric pressure

    International Nuclear Information System (INIS)

    In this work we present a model of argon microwave sustained discharge at high pressure (1 atm), which includes two self-consistently linked parts - electrodynamic and kinetic ones. The model is based on a steady-state Boltzmann equation in an effective field approximation coupled with a collisional-radiative model for high-pressure argon discharge numerically solved together with Maxwell's equation for an azimuthally symmetric TM surface wave and wave energy balance equation. It is applied for the purpose of theoretical description of the discharge in a stationary state. The phase diagram, the electron energy distribution function as well as the dependences of the electron and heavy particles densities and the mean input power per electron on the electron number density and wave number are presented

  7. Modelling of microwave sustained capillary plasma columns at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Pencheva, M [Faculty of Physics, Sofia University, 5 James Bourchier Blvd., BG-1164 Sofia (Bulgaria); Petrova, Ts [Berkeley Research Associate, Inc., Beltsville MD 20705 (United States); Benova, E [Department of Language Learning, Sofia University, 27 Kosta Loulchev Street, BG-1111 Sofia (Bulgaria); Zhelyazkov, I [Faculty of Physics, Sofia University, 5 James Bourchier Blvd., BG-1164 Sofia (Bulgaria)

    2006-07-15

    In this work we present a model of argon microwave sustained discharge at high pressure (1 atm), which includes two self-consistently linked parts - electrodynamic and kinetic ones. The model is based on a steady-state Boltzmann equation in an effective field approximation coupled with a collisional-radiative model for high-pressure argon discharge numerically solved together with Maxwell's equation for an azimuthally symmetric TM surface wave and wave energy balance equation. It is applied for the purpose of theoretical description of the discharge in a stationary state. The phase diagram, the electron energy distribution function as well as the dependences of the electron and heavy particles densities and the mean input power per electron on the electron number density and wave number are presented.

  8. Modelling of microwave sustained capillary plasma columns at atmospheric pressure

    Science.gov (United States)

    Pencheva, M.; Petrova, Ts; Benova, E.; Zhelyazkov, I.

    2006-07-01

    In this work we present a model of argon microwave sustained discharge at high pressure (1 atm), which includes two self-consistently linked parts - electrodynamic and kinetic ones. The model is based on a steady-state Boltzmann equation in an effective field approximation coupled with a collisional-radiative model for high-pressure argon discharge numerically solved together with Maxwell's equation for an azimuthally symmetric TM surface wave and wave energy balance equation. It is applied for the purpose of theoretical description of the discharge in a stationary state. The phase diagram, the electron energy distribution function as well as the dependences of the electron and heavy particles densities and the mean input power per electron on the electron number density and wave number are presented.

  9. 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.

  10. The last 41.000 years fluctuation in atmospheric CO2 concentration inferred from the changes in oxygen and carbon stable isotopes ratios of marine sediments

    International Nuclear Information System (INIS)

    The past atmospheric CO2 concentrations were reconstructed based on the results of measurements of stable oxygen and carbon isotopic ratios of fossil foraminifera and total organic carbon contained in marine sediment taken from the Okinawa Trough. East China Sea. In' this study, we utilized two models of Popp et al and Rau et al, for the reconstruction. The results show that the whole trends of the changes in CO2 concentrations are very similar, even when it is compared to the atmospheric CO2 concentration of air trapped in ice core from southern pole. Changes in atmospheric CO2 concentrations are interpreted as a consequence of fluctuation in ocean surface water utilization of CO2 by marine organism and those are closely related to glacial interglacial (cold-warm) fluctuations between maximum and minimum values through most Quaternary. (author)

  11. 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)

  12. 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

  13. 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)

  14. 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.

  15. 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...

  16. 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

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. Atmospheric pressure change associated with the 2003 Tokachi-Oki earthquake

    OpenAIRE

    Watada, Shingo; Kunugi, Takashi; Hirata, Kenji; Sugioka, Hiroko; Nishida, Kiwamu; Sekiguchi, Shoji; Oikawa, Jun; Tsuji, Yoshinobu; Kanamori, Hiroo

    2006-01-01

    Clear atmospheric pressure changes associated with the 2003 Tokachi-Oki, Japan, earthquake with Mw 8.3 were recorded with the microbarographs distributed in Japan. The pressure change starts at the arrival of seismic waves and reaches its maximum amplitude at the arrival of Rayleigh waves, suggesting that the observed pressure change was driven by the ground motion of seismic waves passing by the site. We computed the seismic-to-pressure transfer function (i.e., the spectral ratio of the pres...

  5. 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...

  6. Interactions between breathing rate and low-frequency fluctuations in blood pressure and cardiac intervals.

    Science.gov (United States)

    Horsman, H M; Peebles, K C; Tzeng, Y C

    2015-10-01

    Evidence derived from spontaneous measures of cardiovagal baroreflex sensitivity (BRS) suggests that slow breathing at 6 breaths/min augments BRS. However, increases in BRS associated with slow breathing may simply reflect the frequency-dependent nature of the baroreflex rather than the modulation of baroreflex function by changes in breathing rate per se. To test this hypothesis we employed a crossover study design (n = 14) wherein breathing rate and systolic arterial blood pressure (SAP) oscillation induced via the application of oscillating lower body negative pressure (OLBNP) were independently varied at fixed frequencies. Breathing rate was controlled at 6 or 10 breaths/min with the aid of a metronome, and SAP oscillations were driven at 0.06 Hz and 0.1 Hz using OLBNP. The magnitudes of SAP and R-R interval (cardiac period) oscillations were quantified using power spectral analysis, and the transfer function gain between SAP and R-R interval was used to estimate BRS. Linear mixed-effects models were used to examine the main effects and interactions between breathing rate and OLBNP frequency. There was no statistical interaction between breathing and OLBNP frequency (P = 0.59), indicating that the effect of breathing rate on BRS did not differ according to OLBNP frequency (and vice versa). Additionally, there was no main effect for breathing rate (P = 0.28). However, we observed a significant main effect for OLBNP frequency (P = 0.01) consistent with the frequency-dependent nature of baroreflex. These findings suggest that increases in spectral indices of BRS reflect the frequency dependence of the baroreflex and are not due to slow breathing per se. PMID:26205543

  7. Effect of the atmospheric pressure nonequilibrium plasmas on the conformational changes of plasmid DNA

    International Nuclear Information System (INIS)

    The cold atmospheric pressure plasma, which has been widely used for biomedical applications, may potentially affect the conformation of DNA. In this letter, an atmospheric pressure plasma plume is used to investigate its effects on the conformational changes of DNA of plasmid pAHC25. It is found that the plasma plume could cause plasmid DNA topology alteration, resulting in the percentage of the supercoiled plasmid DNA form decreased while that of the open circular and linearized form of plasmid DNA increased as detected by agrose gel electrophoresis. On the other hand, further investigation by using polymerase chain reaction method shows that the atmospheric pressure plasma jet treatments under proper conditions does not affect the genes of the plasmid DNA, which may have potential application in increasing the transformation frequency by genetic engineering.

  8. 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.

  9. Self-Consistent Model for Atmospheric Pressure Dielectric Barrier Discharges in Helium

    International Nuclear Information System (INIS)

    We show the necessity of leaving out the approximation of constant average electron energy in many fluid models. For this purpose a one-dimensional self-consistent model for He atmospheric barrier discharges is developed. With this model, the electron energy distribution function in the atmospheric pressure glow discharge is obtained without introducing much difficulty, and the new model is readily implemented for investigating discharges in complicated gases. (gases, plasmas, and electric discharges)

  10. Emission properties of an atmospheric pressure argon plasma jet excited by barrier discharge

    International Nuclear Information System (INIS)

    An atmospheric-pressure argon plasma jet is initiated by the barrier discharge in a capillary, through which argon was flown. The spectral composition of radiation emitted by the jet in the atmosphere and its variation in the space are analyzed in detail. The jet radiation spectrum is shown to be predominantly formed by spectral transitions of argon and oxygen atoms, by electron-vibrational transitions of the first positive system of nitrogen molecules N2, and by transitions of hydroxyl radical OH

  11. 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.

  12. 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...

  13. 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...

  14. 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...

  15. [Determination of electron density in atmospheric pressure radio frequency dielectric barrier discharges by Stark broadening].

    Science.gov (United States)

    Li, Sen; Liu, Zhong-wei; Chen, Qiang; Liu, Fu-ping; Wang, Zheng-duo; Yang, Li-zhen

    2012-01-01

    The use of high frequency power to generate plasma at atmospheric pressure is a relatively new development. An apparatus of atmospheric pressure radio frequency dielectric barrier discharge was constructed. Plasma emission based measurement of electron density in discharge columns from Stark broadening Ar is discribed. The spacial profile of electron density was studied. In the middle of the discharge column, as the input power increases from 138 to 248 W, the electron density rises from 4.038 x 10(21) m(-3) to 4.75 x 10(21) m(-3). PMID:22497121

  16. Generations and applications of atmospheric pressure glow discharge by integration of microplasmas

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, O; Tachibana, K [Department of Electronic Science and Engineering, Kyoto University, Kyoto-daigaku Katsura, Nishikyo-ku, Kyoto 615-8510 (Japan)

    2007-10-15

    Integration of microplasmas enables us to obtain atmospheric pressure discharges with good macroscopic uniformity and various functions. We demonstrate two specific electrodes of microplasmas for generations of dielectric barrier discharges at atmospheric pressure, and integrated microplasmas on large two-dimensional area are sustained with electron density more than 10{sup 12}cm{sup -3}. Especially 'fabric' type electrode has a promising structure to provide various flexible discharge space and plasma processing on winding surface. Integrated microplasmas in array structure will serve as electromagnetic-wave control devices as well as processing tools, and two aspects are discussed in terms of equivalent dielectrics and metals.

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

    DEFF Research Database (Denmark)

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

    2014-01-01

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

  18. Biomedical Applications of Low Temperature Atmospheric Pressure Plasmas to Cancerous Cell Treatment and Tooth Bleaching

    Science.gov (United States)

    Lee, Jae Koo; Kim, Myoung Soo; Byun, June Ho; Kim, Kyong Tai; Kim, Gyoo Cheon; Park, Gan Young

    2011-08-01

    Low temperature atmospheric pressure plasmas have attracted great interests and they have been widely applied to biomedical applications to interact with living tissues, cells, and bacteria due to their non-thermal property. This paper reviews the biomedical applications of low temperature atmospheric pressure plasmas to cancerous cell treatment and tooth bleaching. Gold nanoparticles conjugated with cancer-specific antibodies have been introduced to cancerous cells to enhance selective killing of cells, and the mechanism of cell apoptosis induced by plasma has been investigated. Tooth exposed to helium plasma jet with hydrogen peroxide has become brighter and the productions of hydroxyl radicals from hydrogen peroxide have been enhanced by plasma exposure.

  19. 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.

  20. Premixed flame response to pressure fluctuations using an implicit solver with detailed chemistry

    Science.gov (United States)

    Malik, Nadeem

    2015-11-01

    A major challenge in combustion research is the coupling of the compressible flow field to the detailed thermochemistry. Recent advances in numerical solvers has met this challenge within an implicit numerical framework, retaining the full stiffness of the realistic comprehensive chemistry and multicomponent transport properties in the system. Here, the solver TARDIS (Transient Advection Reaction Diffusion Implicit Simulations) is demonstrated, first, by investigating the laminar flame speed in stoichiometric H2/air and CH4/air flames as a function of the flame curvature and found to follow non-linear regimes, contrary to previous thinking. Second, planar and curved laminar flames are subjected to pressure and equivalence ratio oscillations and found to respond through a spectrum of time and length scales. TARDIS has the potential to elucidate fundamental aspects of flame structure and thermochemistry, and could be the basis for a new generation of implicit DNS solvers. The author acknowledge financial support from SABIC, #SB101018, through the Dean of Scientific Research at KFUPM.

  1. 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.

  2. 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...

  3. 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

  4. 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...

  5. 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...

  6. Melt-vapor phase transition in the lead-selenium system at atmospheric and low pressure

    Science.gov (United States)

    Volodin, V. N.; Burabaeva, N. M.; Trebukhov, S. A.

    2016-03-01

    The boiling temperature and the corresponding vapor phase composition in the existence domain of liquid solutions were calculated from the partial pressures of saturated vapor of the components and lead selenide over liquid melts in the lead-selenium system. The phase diagram was complemented with the liquid-vapor phase transition at atmospheric pressure and in vacuum of 100 Pa, which allowed us to judge the behavior of the components during the distillation separation.

  7. 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

  8. 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

  9. Effects of long-term low atmospheric pressure on gas exchange and growth of lettuce

    Science.gov (United States)

    Tang, Yongkang; Guo, Shuangsheng; Dong, Wenping; Qin, Lifeng; Ai, Weidang; Lin, Shan

    2010-09-01

    The objectives of this research were to determine photosynthesis, evapotranspiration and growth of lettuce at long-term low atmospheric pressure. Lettuce ( Lactuca sativa L . cv. Youmaicai) plants were grown at 40 kPa total pressure (8.4 kPa p) or 101 kPa total pressure (20.9 kPa p) from seed to harvest for 35 days. Germination rate of lettuce seeds decreased by 7.6% at low pressure, although this was not significant. There was no significant difference in crop photosynthetic rate between hypobaria and ambient pressure during the 35-day study. The crop evapotranspiration rate was significantly lower at low pressure than that at ambient pressure from 20 to 30 days after planting (DAP), but it had no significant difference before 20 DAP or after 30 DAP. The growth cycle of lettuce plants at low pressure was delayed. At low pressure, lettuce leaves were curly at the seedling stage and this disappeared gradually as the plants grew. Ambient lettuce plants were yellow and had an epinastic growth at harvest. The shoot height, leaf number, leaf length and shoot/root ratio were lower at low pressure than those at ambient pressure, while leaf area and root growth increased. Total biomass of lettuce plants grown at two pressures had no significant difference. Ethylene production at low pressure decreased significantly by 38.8% compared with ambient pressure. There was no significant difference in microelements, nutritional phytochemicals and nitrate concentrations at the two treatments. This research shows that lettuce can be grown at long-term low pressure (40 kPa) without significant adverse effects on seed germination, gas exchange and plant growth. Furthermore, ethylene release was reduced in hypobaria.

  10. 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

  11. 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

  12. 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

  13. 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.

  14. 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.

  15. The PWM auto-control circuit of neutron tube atmospheric pressure

    International Nuclear Information System (INIS)

    Ion source atmospheric pressure auto-control circuit for C/O logging neutron generator is introduced. The pulse circuit of ion source adopts zero-voltage quasi-resonant switch technique and the heating circuit for replenisher adopts PWM converter

  16. 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

  17. 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

  18. 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 ...

  19. Atmospheric pressure plasma polymerization of 1,3-butadiene for hydrophobic finishing of textile substrates

    International Nuclear Information System (INIS)

    Atmospheric pressure plasma processing of textile has both ecological and economical advantages over the wet-chemical processing. However, reaction in atmospheric pressure plasma has important challenges to be overcome before it can be successfully used for finishing applications in textile. These challenges are (i) generating stable glow plasma in presence liquid/gaseous monomer, and (ii) keeping the generated radicals active in the presence of contaminants such as oxygen and air. In this study, a stable glow plasma was generated at atmospheric pressure in the mixture of gaseous reactive monomer-1,3-butadiene and He and was made to react with cellulosic textile substrate. After 12 min of plasma treatment, the hydrophilic surface of the cellulosic substrate turned into highly hydrophobic surface. The hydrophobic finish was found to be durable to soap washing. After soap washing, a water drop of 37 μl took around 250 s to get absorbed in the treated sample compared to 0. Both top and bottom sides of the fabric showed similar hydrophobic results in terms of water absorbency and contact angle. The results may be attributed to chemical reaction of butadiene with the cellulosic textile substrate. The surface characterization of the plasma modified samples under SEM and AFM revealed modification of the surface under <100 nm. The results showed that atmospheric pressure plasma can be successfully used for carrying out reaction of 1,3-butadiene with cellulosic textile substrates for producing hydrophobic surface finish.

  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, is...

  1. 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

  2. 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

  3. Bivariate wavelet-based clustering of sea-level and atmospheric pressure time series

    Science.gov (United States)

    Barbosa, Susana; Gouveia, Sonia; Scotto, Manuel; Alonso, Andres

    2015-04-01

    The atmospheric pressure is responsible for a downward force acting on the sea surface which is compensated, to some extent, by corresponding sea-level variations. The static response of the sea surface can be linearly modelled, a decrease (increase) in atmospheric pressure of 1 mb raising (depressing) sea level by 1 cm. However, the dynamic sea surface response to atmospheric pressure loading, associated with ocean dynamics and wind effects, is scale-dependent and difficult to establish. The present study addresses the co-variability of sea-level and pressure time series in the Baltic Sea from the bivariate analysis of tide gauge and reanalysis records. The time series are normalised by the corresponding standard deviation and the wavelet covariance is computed as a measure of the association between sea-level and pressure across scales. A clustering procedure using a dissimilarity matrix based on the wavelet covariance is then implemented. Different classical clustering techniques, including average, single and complete linkage criteria are applied and the group linkage is selected in order to maximise the dendrogram's goodness-of-fit.

  4. 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

  5. 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

  6. Deposition of anti-corrosion coatings by atmospheric pressure plasma jet

    International Nuclear Information System (INIS)

    An atmospheric-pressure, non-equilibrium plasma jet is currently under investigation at Chalk River Laboratories for the application of anti-corrosion coatings. This device produces concentrations of chemically-active species, similar to those observed in low-pressure plasma deposition systems, with the advantage of operating in an ambient pressure atmosphere. This paper describes measurements of the properties of a bench-scale plasma jet operating in etch and deposition mode. The jet effluent was characterized by various methods, including optical emission spectroscopy. Films deposited on metallic and insulating substrates have been characterized by optical microscopy and surface analytical techniques. The potential for scale-up of this process to treatment of reactor components is discussed. (author)

  7. 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...

  8. Correlation measurements of Atmospheric Pressure variations and Seismicity during Hurricane Dennis

    CERN Document Server

    Peters, R D

    2005-01-01

    During the passage of hurricane Dennis, two functionally different instruments made continuous recordings from their location in Macon, Georgia. These were (i) a non-conventional vertical seismometer, and (ii) a low-level differential pressure sensor. Data were collected for 72 hours, beginning when the eye of the storm was located in the vicinity of Key West, Florida. Over the ensuing three-day period, fluctuations in the outputs from the two instruments were found to be highly correlated, with the exception of one eight hour interval.

  9. 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.

  10. Effect of pressure broadening on molecular absorption cross sections in exoplanetary atmospheres

    Science.gov (United States)

    Hedges, Christina; Madhusudhan, Nikku

    2016-05-01

    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 H2O as a case study as it has the most complete absorption line data. For low-resolution spectra (R ≲ 100) for representative temperatures and pressures (T ˜ 500-3000 K, P ≲ 1 atm) of H2-rich exoplanetary atmospheres, we find the median difference in cross-sections (δ) introduced by various aspects of pressure broadening to be ≲1 per cent. For medium resolutions (R ≲ 5000), including those attainable with James Webb Space Telescope, we find that δ can be up to 40 per cent. For high resolutions (R ˜ 105), δ can be ≳100 per cent, reaching ≳1000 per cent for low temperatures (T ≲ 500 K) and high pressures (P ≳ 1 atm). The effect is higher still for self-broadening. We generate a homogeneous data base of absorption cross-sections of molecules of relevance to exoplanetary atmospheres for which high-temperature line lists are available, particularly H2O, CO, CH4, CO2, HCN, and NH3.

  11. Photosynthesis and growth response of almond to increased atmospheric ozone partial pressures

    International Nuclear Information System (INIS)

    Uniform nursery stock of five almond cultivars [Prunus dulcis (Mill) D.A. Webb syn. P. amygdalus Batsch, cv. Butte, Carmel, Mission, Nonpareil, and Sonora] propagated on peach (P. domstica L. Batsch.) rootstock were exposed to three different atmospheric ozone (O3) partial pressures. The trees were planted in open-top fumigation chambers on 19 Apr. 1989 at the University of California Kearny Agricultural Center located in the San Joaquin Valley of California. Exposures of the trees to three atmospheric O3 partial pressures lasted from 1 June to 2 Nov. 1989. The mean 12-h [0800-2000 h Pacific Daylight Time (PDT)] O3 partial pressures measured in the open-top chambers during the experimental period were 0.038, 0.060, and 0.112 μPa Pa-1 O3 in the charcoal filtered, ambient, and ambient + O3 treatments, respectively. Leaf net CO2 assimilation, trunk cross-sectional area growth, and root, trunk, foliage, and total dry weight of Nonpareil were reduced by increased atmospheric O3 partial pressures. Mission was unaffected by O3 and Butte, Carmel, and Sonora were intermediate in their responses. Foliage of Nonpareil also abscised prematurely in the ambient and ambient + O3 treatments. The results indicate that there are almond cultivars that are sensitive to O3 exposure

  12. Thermodynamic and economic analysis of polygeneration system integrating atmospheric pressure coal pyrolysis technology with circulating fluidized bed power plant

    International Nuclear Information System (INIS)

    Highlights: • A lignite pyrolysis-based polygeneration plant was proposed and modeled. • Polygeneration plant has a 9.04% point higher efficiency than CFB power plant. • Polygeneration plant increases ca. 14% point of IRR based on CFB power plant. • Electricity price rise makes polygeneration plant less competitive. - Abstract: Lignite-based polygeneration system has been considered as a feasible technology to realize clean and efficient utilization of coal resources. A newly polygeneration system has been proposed, featuring the combination of a 2 × 300 MW circulating fluidized bed (CFB) power plant and atmospheric pressure fluidized bed pyrolyzers. Xiaolongtan lignite is pyrolyzed in pyrolyzers. Pyrolyzed volatiles are further utilized for the co-generation of methanol, oil, and electricity, while char residues are fired in CFB boilers to maintain the full load condition of boilers. Detailed system models were built, and the optimum operation parameters of the polygeneration plant were sought. Technical and economic performances of optimum design of the polygeneration plant were analyzed and compared with those of the conventional CFB power plant based on the evaluation of energy and exergy efficiency, internal rate of return (IRR), and payback period. Results revealed that system efficiency and the IRR of the polygeneration plant are ca. 9% and 14% points higher than those of the power plant, respectively. The study also analyzed the effects of market fluctuations on the economic condition of the polygeneration plant, and found that prices of fuel, material, and products have great impacts on the economic characteristics of the polygeneration plant. Polygeneration plant is more economic than CFB power plant even when prices fluctuate within a wide range. This paper provides a thorough evaluation of the polygeneration plant, and the study indicates that the proposed polygeneration plant has a bright prospect

  13. 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

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

    International Nuclear Information System (INIS)

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

  15. 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)

  16. 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...

  17. 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...

  18. 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

  19. 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.

  20. 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

  1. 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.

  2. 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

  3. Experimental characterization of an argon laminar plasma jet at atmospheric pressure

    International Nuclear Information System (INIS)

    This paper deals with a dc laminar pure argon plasma jet operating at atmospheric pressure in ambient air that was experimentally studied in order to obtain temperature and velocity. Plasma jet temperature was evaluated by optical emission spectroscopy and the plasma jet velocity was determined by various methods using a pressure sensor. It is shown that the maximum plasma jet temperature is 15 000 K and the maximum plasma jet velocity is 250 m s-1 at the plasma jet centre. Finally, a study of the ambient air amount entrained into the plasma jet is presented.

  4. Experimental characterization of an argon laminar plasma jet at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Langlois-Bertrand, Emilie; De Izarra, Charles, E-mail: charles.de_izarra@univ-orleans.fr [Groupe de Recherche sur l' Energetique des Milieux Ionises, UMR6606 Universite d' Orleans - CNRS, Faculte des Sciences, Site de Bourges, rue Gaston Berger, BP 4043, 18028 BOURGES Cedex (France)

    2011-10-19

    This paper deals with a dc laminar pure argon plasma jet operating at atmospheric pressure in ambient air that was experimentally studied in order to obtain temperature and velocity. Plasma jet temperature was evaluated by optical emission spectroscopy and the plasma jet velocity was determined by various methods using a pressure sensor. It is shown that the maximum plasma jet temperature is 15 000 K and the maximum plasma jet velocity is 250 m s{sup -1} at the plasma jet centre. Finally, a study of the ambient air amount entrained into the plasma jet is presented.

  5. 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...

  6. 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

  7. Development of data logger for atmospheric pressure, temperature and relative humidity for gas-filled detector

    International Nuclear Information System (INIS)

    At IoP-NISER an initiative has been taken to build and test micro-pattern gas detector such as Gas Electron Multiplier (GEM) for several upcoming High-Energy Physics (HEP) experiment projects. Temperature (t), atmospheric pressure (p) and relative humidity (RH) monitor and recording is very important for gas filled detector development. A data logger to monitor and record the ambient parameters such as temperature, relative humidity and pressure has been developed. With this data logger continuous recording of t, p, RH and time stamp can be done with a programmable sampling interval. This data is necessary to correct the gain of a gas filled detector

  8. 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)

    DU; Wenfeng; (杜文峰); HU; Wenrui; (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.

  9. 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.

  10. 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...... absorption spectroscopy was also employed for the detection of stable products in the exhaust gas. To clarify the different processes for ammonia decomposition, N-2(2 - 10%) was added to the plasma. Modeling of the chemical kinetics in an Ar/NH3 plasma was performed as well. The dominant stable products 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....

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-05-07

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

  12. 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 for the exper......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...... for the experiments. Glass slides were inoculated with L. innocua. The slides were placed inside a low density polyethylene (LDPE) bag. The bag was filled with a gas mixture of 97.5 Vol% Ar and 2.5 Vol% O2 and subsequently sealed. The bag was placed between the electrodes of a dielectric barrier discharge...

  13. 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.

  14. 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)

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

    International Nuclear Information System (INIS)

    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.

  16. Effect of Atmospheric Pressure Plasma and Subsequent Enzymatic Treatment on Flax Fabrics

    Science.gov (United States)

    Zhong, Shaofeng; Yang, Bin; Ou, Qiongrong

    2015-09-01

    The objective is to investigate the effect of atmospheric pressure dielectric barrier discharge (APDBD) plasma and subsequent cellulase enzyme treatment on the properties of flax fabrics. The changes of surface morphology and structure, physico-mechanical properties, hydrophilicity, bending properties, whiteness, and dyeing properties of the treated substrate were investigated. The results indicated that atmospheric pressure dielectric barrier discharge plasma pre-treatment and subsequent cellulase enzyme treatment could diminish the hairiness of flax fabrics, endowing the flax fabrics with good bending properties, water uptake and fiber accessibility while keeping their good mechanical properties compared with those treated with cellulase enzyme alone. supported by the Science and Technology Project of the Education Department of Zhejiang Province, China (No. Y201432680) and the Professional Leaders Leading Project of the Education Department of Zhejiang Province, China (No. lj2013131), the Teaching and Research Award Program for Outstanding Young Teachers in Higher Education Institutions of the Education Department of Zhejiang Province, China (No. 1097802072012001)

  17. 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.

  18. 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

  19. 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. PMID:25656637

  20. Numerical simulation of torus breakdown to chaos in an atmospheric-pressure dielectric barrier discharge

    International Nuclear Information System (INIS)

    Understanding the routes to chaos occurring in atmospheric-pressure dielectric barrier discharge systems by changing controlling parameters is very important to predict and control the dynamical behaviors. In this paper, a route of a quasiperiodic torus to chaos via the strange nonchaotic attractor is observed in an atmospheric-pressure dielectric barrier discharge driven by triangle-wave voltage. By increasing the driving frequency, the discharge system first bifurcates to a quasiperiodic torus from a stable single periodic state, and then torus and phase-locking periodic state appear and disappear alternately. In the meantime, the torus becomes increasingly wrinkling and stretching, and gradually approaches a fractal structure with the nonpositive largest Lyapunov exponent, i.e., a strange nonchaotic attractor. After that, the discharge system enters into chaotic state. If the driving frequency is further increased, another well known route of period-doubling bifurcation to chaos is also observed

  1. 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.

  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. 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

  4. 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.

  5. 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%.

  6. 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.

  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. 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.

  9. 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.

  10. 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. PMID:24432758

  11. 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.

  12. 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.

  13. Nano-Coating Process for Si [1 0 0] Wafer Using Atmospheric Pressure Plasma Jet (APPJ)

    OpenAIRE

    Ahmed Rida Galaly

    2012-01-01

    Three-electrode plasma jet system consisting of a perforated dielectric tube with two outer and one floating inner electrodes was developed and employed for nano-coating processes of Si [1 0 0] wafer. Lowered gas breakdown voltage, increasing plasma density and increased discharge current were achieved by using the floating inner electrode. The low temperature (Nonthermal) Atmospheric Pressure Plasma protective coating technique using precursor-containing gases (Ar, O2 and OMCTS mixture) whic...

  14. 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

  15. Improvement of stability of sinusoidally driven atmospheric pressure plasma jet using auxiliary bias voltage

    OpenAIRE

    Hyun-Jin Kim; Jae Young Kim; Jae Hyun Kim; Dong Ha Kim; Duck-Sik Lee; Choon-Sang Park; Hyung Dal Park; Bhum Jae Shin; Heung-Sik Tae

    2015-01-01

    In this study, we have proposed the auxiliary bias pulse scheme to improve the stability of atmospheric pressure plasma jets driven by an AC sinusoidal waveform excitation source. The stability of discharges can be significantly improved by the compensation of irregular variation in memory voltage due to the effect of auxiliary bias pulse. From the parametric study, such as the width, voltage, and onset time of auxiliary bias pulse, it has been demonstrated that the auxiliary bias pulse plays...

  16. Radiative ion-ion neutralization: a new gas-phase atmospheric pressure ion transduction mechanism.

    Science.gov (United States)

    Davis, Eric J; Siems, William F; Hill, Herbert H

    2012-06-01

    All atmospheric pressure ion detectors, including photo ionization detectors, flame ionization detectors, electron capture detectors, and ion mobility spectrometers, utilize Faraday plate designs in which ionic charge is collected and amplified. The sensitivity of these Faraday plate ion detectors are limited by thermal (Johnson) noise in the associated electronics. Thus approximately 10(6) ions per second are required for a minimal detection. This is not the case for ion detection under vacuum conditions where secondary electron multipliers (SEMs) can be used. SEMs produce a cascade of approximately 10(6) electrons per ion impinging on the conversion dynode. Similarly, photomultiplier tubes (PMTs) can generate approximately 10(6) electrons per photon. Unlike SEMs, however, PMTs are evacuated and sealed so that they are commonly used under atmospheric pressure conditions. This paper describes an atmospheric pressure ion detector based on coupling a PMT with light emitted from ion-ion neutralization reactions. The normal Faraday plate collector electrode was replaced with an electrode "needle" used to concentrate the anions as they were drawn to the tip of the needle by a strong focusing electric field. Light was emitted near the surface of the electrode when analyte ions were neutralized with cations produced from the anode. Although radiative-ion-ion recombination has been previously reported, this is the first time ions from separate ionization sources have been combined to produce light. The light from this radiative-ion-ion-neutralization (RIIN) was detected using a photon multiplier such that an ion mobility spectrum was obtained by monitoring the light emitted from mobility separated ions. An IMS spectrum of nitroglycerin (NG) was obtained utilizing RIIN for tranducing the mobility separated ions into an analytical signal. The implications of this novel ion transduction method are the potential for counting ions at atmospheric pressure and for obtaining ion

  17. Influence of gap width on discharge asymmetry in atmospheric pressure glow dielectric barrier discharges

    International Nuclear Information System (INIS)

    In this letter, a one-dimensional fluid model is used to investigate the mechanism of discharge asymmetry in atmospheric pressure helium glow dielectric barrier discharges (GDBDs). By observing the evolutionary process between the successive peak currents, the effect of the gap width on the discharge asymmetry is thoroughly discussed. It is shown that when the gap width is too large, the very severe nonuniformity of electric field distribution over the gas gap leads to the discharge asymmetry.

  18. Study of Dielectric Barrier Discharges in nitrogen and afterglows at atmospheric pressure

    International Nuclear Information System (INIS)

    This article is devoted to the study of Dielectric Barrier Discharges (DBD) and afterglows obtained at atmospheric pressure in nitrogen. Electrical and optical analysis of the DBD reactor are carried out in order to characterize specific activated gaseous species, which can travel with low energy dispersion for long distances in tubes. A hypothesis for the explanation of the presence of long-lived species in such afterglows is finally explained as related to a solitary wave effect.

  19. Numerical simulations of superlattice patterns in dielectric barrier discharges at atmospheric pressure

    Science.gov (United States)

    Liu, Fucheng; Wang, Xiaofei; He, Yafeng; Dong, Lifang

    2016-03-01

    This paper presents the numerical investigation on superlattice patterns in atmospheric pressure glow discharges in dielectric barrier discharges by using a self-consistent 2D fluid model. It is found that the superlattice pattern is an interleaving of two filamentary sub-patterns with alternate spatial and temporal characteristics. The competition between the volume ionization and the memory effects of both surface charges and space charges is expected to the formation mechanism of this superlattice pattern.

  20. Characterization of transient discharges under atmospheric pressure conditions applying nitrogen photoemission and current measurements

    OpenAIRE

    Keller, Sandra; Rajasekaran, Priyadarshini; Bibinov, Nikita; Awakowicz, Peter

    2011-01-01

    The plasma parameters such as electron distribution function and electron density of three atmospheric-pressure transient discharges namely filamentary and homogeneous dielectric barrier discharges in air, and the spark discharge of argon plasma coagulation (APC) system are determined. A combination of numerical simulation as well as diagnostic methods including current measurement and optical emission spectroscopy (OES) based on nitrogen emissions is used. The applied methods supplement each...

  1. Study of Dielectric Barrier Discharges in nitrogen and afterglows at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Clement, F; Panousis, E; Lecoq, E; Loiseau, J-F; Held, B [Universite de Pau - LEGP, IPREM - 64000 Pau (France); Ricard, A [Universite Paul Sabatier - LAPLACE - 31000 Toulouse (France)

    2010-01-01

    This article is devoted to the study of Dielectric Barrier Discharges (DBD) and afterglows obtained at atmospheric pressure in nitrogen. Electrical and optical analysis of the DBD reactor are carried out in order to characterize specific activated gaseous species, which can travel with low energy dispersion for long distances in tubes. A hypothesis for the explanation of the presence of long-lived species in such afterglows is finally explained as related to a solitary wave effect.

  2. 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...... functional groups at the surface, and subsequently improved adhesion to the epoxy and fracture resistance of epoxy composites. Hansen solubility parameters (HSP), quantitatively describing physical interactions among molecules, were measured for the UHMWPE fibre surfaces. The result identifies two distinct...

  3. Investigation of the Process of Methane-Oxygen Combustion in Steam Under the Atmospheric Pressure

    Science.gov (United States)

    Pribaturin, N. A.; Bogomolov, A. R.; Azikhanov, S. S.; Shevyrev, S. A.

    2016-02-01

    In the article presented results of combustion methane-oxygen mixtures in the slightly superheated water steam under the atmospheric pressure. It is shown that exist dependence of flow rate combustible mixture and steam ratio (Gg.s./Gs) on the composition of the reacting mixture at the outlet of combustion chamber. There is a trend of increasing CO2 concentration in the reacting mixture at the outlet of combustion chamber with increase of Gg.s./Gs.

  4. 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.

  5. Analysis of insect triacylglycerols using liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry

    Czech Academy of Sciences Publication Activity Database

    Kofroňová, Edita; Cvačka, Josef; Jiroš, Pavel; Sýkora, D.; Valterová, Irena

    2009-01-01

    Roč. 111, č. 5 (2009), s. 519-525. ISSN 1438-7697 R&D Projects: GA AV ČR IAA4055403; GA MŠk 2B06007 Institutional research plan: CEZ:AV0Z40550506 Keywords : atmospheric pressure chemical ionization * bumblebees * fat body * NARP-HPLC Subject RIV: CC - Organic Chemistry Impact factor: 1.831, year: 2009

  6. 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.

  7. Characterisation of PMMA/ATH Layers Realised by Means of Atmospheric Pressure Plasma Powder Deposition

    OpenAIRE

    Wallenhorst, Lena M.; Sebastian Dahle; Matej Vovk; Lisa Wurlitzer; Leander Loewenthal; Nils Mainusch; Christoph Gerhard; Wolfgang Viöl

    2015-01-01

    We report on the characteristics of aluminium trihydrate filled poly(methyl methacrylate) composite (PMMA/ATH) coatings realised by plasma deposition at atmospheric pressure. For this purpose, PMMA/ATH powder was fed to a plasma jet where the process and carrier gas was compressed air. The deposited coatings were investigated by X-ray photoelectron spectroscopy and water contact angle measurements. Further, the raw material was characterised before deposition. It was found that, with respect ...

  8. Enhancing the mechanical properties of superhydrophobic atmospheric pressure plasma deposited siloxane coatings

    OpenAIRE

    Nwankire, Charles E.; Favaro, Gregory; Duong, Quynh-Huong; Denis P. Dowling

    2011-01-01

    Surfaces with water contact angles above 150° are regarded as superhydrophobic. In this study the use of atmospheric pressure plasma jet system called PlasmaStreamTM to deposit superhydrophobic coatings is investigated. The coatings were deposited from the following liquid precursors: HMDSO, tetramethyl cyclotetrasiloxane (Tomcats) and a mixture of Tomcats and fluorosiloxane. The objective of the study is to investigate how precursor type and deposition conditions, influences t...

  9. 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.

  10. Thin layer chromatography/desorption atmospheric pressure photoionization-mass spectrometry of lipids

    Czech Academy of Sciences Publication Activity Database

    Rejšek, Jan; Vrkoslav, Vladimír; Cvačka, Josef

    Praha: Ústav organické chemie a biochemie AV ČR, 2016 - (Kuda, O.). s. 30 ISBN 978-80-86241-54-8. [Česká lipidomická konference /5./. 21.04.2016-22.04.2016, Praha] Institutional support: RVO:61388963 Keywords : desorption atmospheric pressure photoionization * ambient mass spectrometry * thin layer chromatography * lipids Subject RIV: CB - Analytical Chemistry, Separation

  11. 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.

  12. 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...

  13. Atmospheric pressure plasma polymerization of 1,3-butadiene for hydrophobic finishing of textile substrates

    Energy Technology Data Exchange (ETDEWEB)

    Samanta, Kartick K; Jassal, Manjeet; Agrawal, Ashwini K, E-mail: ashwini@smita-iitd.co, E-mail: manjeet.jassal@smita-iitd.co [Smart and Innovative Textile Materials Group (SMITA), Department of Textile Technology, Indian Institute of Technology, Hauz Khas, New Delhi-110016 (India)

    2010-02-01

    Atmospheric pressure plasma processing of textile has both ecological and economical advantages over the wet-chemical processing. However, reaction in atmospheric pressure plasma has important challenges to be overcome before it can be successfully used for finishing applications in textile. These challenges are (i) generating stable glow plasma in presence liquid/gaseous monomer, and (ii) keeping the generated radicals active in the presence of contaminants such as oxygen and air. In this study, a stable glow plasma was generated at atmospheric pressure in the mixture of gaseous reactive monomer-1,3-butadiene and He and was made to react with cellulosic textile substrate. After 12 min of plasma treatment, the hydrophilic surface of the cellulosic substrate turned into highly hydrophobic surface. The hydrophobic finish was found to be durable to soap washing. After soap washing, a water drop of 37 {mu}l took around 250 s to get absorbed in the treated sample compared to < 1 s in the untreated samples. The plasma modified samples showed water contact angle of around 134{sup 0}. Both top and bottom sides of the fabric showed similar hydrophobic results in terms of water absorbency and contact angle. The results may be attributed to chemical reaction of butadiene with the cellulosic textile substrate. The surface characterization of the plasma modified samples under SEM and AFM revealed modification of the surface under <100 nm. The results showed that atmospheric pressure plasma can be successfully used for carrying out reaction of 1,3-butadiene with cellulosic textile substrates for producing hydrophobic surface finish.

  14. 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)

  15. 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...

  16. Sequential Atmospheric Pressure Plasma-Assisted Laser Ablation of Photovoltaic Cover Glass for Improved Contour Accuracy

    OpenAIRE

    Christoph Gerhard; Maximilian Dammann; Stephan Wieneke; Wolfgang Viöl

    2014-01-01

    In this paper, we present sequential atmospheric pressure plasma-assisted laser ablation of photovoltaic cover glass. First, glass samples were plasma pre-treated using a hydrogenous plasma process gas in order to accomplish a modification of the near-surface glass network by a chemical reduction and the implantation of hydrogen. As a result, the transmission at a wavelength of 355 nm was reduced by approximately 2% after plasma treatment duration of 60 min. Further, the surface polarity was ...

  17. 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.

  18. 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.

  19. 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...

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

    Science.gov (United States)

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

    2015-12-01

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

  1. 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.

  2. 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.

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

    International Nuclear Information System (INIS)

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

  4. PFC decomposition with atmospheric pressure microwave plasma using resonant and non-resonant structure

    International Nuclear Information System (INIS)

    PFC (Perfluoro Carbon Compound) decomposition using resonant structure microwave plasma at atmospheric pressure has been investigated in comparison with conventional non-resonant plasma system. In the atmospheric pressure plasma abatement the high flow rate of N2 purging gas (>30slm) remains to be a difficult problem in obtaining the stable discharge and sufficient DRE (Destruction Removal Efficiency). In order to increase the residence time of gas molecules in discharge, we designed the resonant structure chamber with strongly coupled TE31/TM010 mode, which generates the large area (dia.> 60mm) plasma. For the CF4/Ar etch recipes with oxygen and water vapor, the DRE has been estimated as about 95-99% from the result measured by Fourier Transform Infrared Spectrometer (FTIR) and Quadrupole Mass Spectrometer (QMS) in detuned resonant and non-resonant system. With the coupled cavity, it is achieved to sustain the stable atmospheric pressure plasma and demonstrated higher energy efficiency and availability than those by the conventional plasma scrubb process under high flow rate condition. (author)

  5. 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.

  6. 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.

  7. 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

  8. 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

  9. Development of superhydrophobic surface on glass substrate by multi-step atmospheric pressure plasma treatment

    International Nuclear Information System (INIS)

    Superhydrophobic surface was prepared on a glass by helium based CH4 and C4F8 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 CH4 plasma treatment and a single step C4F8 plasma treatment, respectively. The contact angle was remarkably increased to 152°, indicating a superhydrophobic property, after a sequential multi-step CH4 and C4F8 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

  10. Atmospheric pressure plasma polymerization of 1,3-butadiene for hydrophobic finishing of textile substrates

    Science.gov (United States)

    Samanta, Kartick K.; Jassal, Manjeet; Agrawal, Ashwini K.

    2010-02-01

    Atmospheric pressure plasma processing of textile has both ecological and economical advantages over the wet-chemical processing. However, reaction in atmospheric pressure plasma has important challenges to be overcome before it can be successfully used for finishing applications in textile. These challenges are (i) generating stable glow plasma in presence liquid/gaseous monomer, and (ii) keeping the generated radicals active in the presence of contaminants such as oxygen and air. In this study, a stable glow plasma was generated at atmospheric pressure in the mixture of gaseous reactive monomer-1,3-butadiene and He and was made to react with cellulosic textile substrate. After 12 min of plasma treatment, the hydrophilic surface of the cellulosic substrate turned into highly hydrophobic surface. The hydrophobic finish was found to be durable to soap washing. After soap washing, a water drop of 37 μl took around 250 s to get absorbed in the treated sample compared to textile substrate. The surface characterization of the plasma modified samples under SEM and AFM revealed modification of the surface under textile substrates for producing hydrophobic surface finish.

  11. 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.

  12. 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.

  13. Atmospheric pressure plasma enhanced chemical vapor deposition of zinc oxide and aluminum zinc oxide

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Kyle W. [Center for Nanoscale Science and Engineering, North Dakota State University, Fargo, ND (United States); Department of Mechanical Engineering, North Dakota State University, Fargo, ND (United States); Guruvenket, Srinivasan; Sailer, Robert A. [Center for Nanoscale Science and Engineering, North Dakota State University, Fargo, ND (United States); Ahrenkiel, S. Phillip [Department of Nanoscience and Nanoengineering, South Dakota School of Mines and Technology, Rapid City, SD (United States); Schulz, Douglas L., E-mail: SBRconsulting@hotmail.com [Center for Nanoscale Science and Engineering, North Dakota State University, Fargo, ND (United States); Department of Mechanical Engineering, North Dakota State University, Fargo, ND (United States)

    2013-12-02

    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 H{sub 2}O 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 ZnF{sub 2}. • Carbonaceous contamination from the precursor was minimal.

  14. Atmospheric pressure plasma jet with high-voltage power supply based on piezoelectric transformer.

    Science.gov (United States)

    Babij, Michał; Kowalski, Zbigniew W; Nitsch, Karol; Silberring, Jerzy; Gotszalk, Teodor

    2014-05-01

    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. PMID:24880391

  15. Intracellular effects of atmospheric-pressure plasmas on melanoma cancer cells

    International Nuclear Information System (INIS)

    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

  16. High-resolution atmospheric pressure infrared laser desorption/ionization mass spectrometry imaging of biological tissue.

    Science.gov (United States)

    Römpp, Andreas; Schäfer, Karl Christian; Guenther, Sabine; Wang, Zheng; Köstler, Martin; Leisner, Arne; Paschke, Carmen; Schramm, Thorsten; Spengler, Bernhard

    2013-09-01

    An atmospheric pressure laser desorption/ionization mass spectrometry imaging ion source has been developed that combines high spatial resolution and high mass resolution for the in situ analysis of biological tissue. The system is based on an infrared laser system working at 2.94 to 3.10 μm wavelength, employing a Nd:YAG laser-pumped optical parametrical oscillator. A Raman-shifted Nd:YAG laser system was also tested as an alternative irradiation source. A dedicated optical setup was used to focus the laser beam, coaxially with the ion optical axis and normal to the sample surface, to a spot size of 30 μm in diameter. No additional matrix was needed for laser desorption/ionization. A cooling stage was developed to reduce evaporation of physiological cell water. Ions were formed under atmospheric pressure and transferred by an extended heated capillary into the atmospheric pressure inlet of an orbital trapping mass spectrometer. Various phospholipid compounds were detected, identified, and imaged at a pixel resolution of up to 25 μm from mouse brain tissue sections. Mass accuracies of better than 2 ppm and a mass resolution of 30,000 at m/z = 400 were achieved for these measurements. PMID:23877173

  17. 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%.

  18. 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

  19. Ellipsometric investigations during plasma cleaning: Comparison between low-pressure rf-plasma and barrier discharge at atmospheric pressure

    International Nuclear Information System (INIS)

    The removal of hydrocarbon containing compounds using a barrier discharge at atmospheric pressure (air) as well as a capacitively coupled 13.56 MHz low-pressure rf-discharge has been examined. Al plates, Si-wafer and Al coated Si-wafer served as substrate materials. In the rf-discharge, power and gas pressure were varied. Argon, oxygen, and hydrogen were used as process gases. In the barrier discharge, power variation was investigated. Spectroscopic ellipsometry was used to determine thickness and optical properties of the contamination. The removal of the contamination layers was observed by means of in-situ kinetic ellipsometry. In the rf-discharge the thickness of the lubricant decreases linearly with the treatment time. The determined removal rates per discharge power are 0.1 nm/Ws for O2 and about 0.01 nm/Ws for Ar and H2. In the barrier discharge the etching rate decreases about exponentially with treatment time. This is due to a beginning polymerization shown by the increase of the optical constants of the lubricant. The etching rate reaches values up to 0. 1 mm/Ws. After the removal of the lubricant the thickness of the surface oxide increases significantly. (author)

  20. 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...