Showing papers on "Atmospheric pressure published in 1989"

The influence of formation material properties on the response of water levels in wells to Earth tides and atmospheric loading

Abstract: The water level in an open well can change in response to deformation of the surrounding material, either because of applied strains (tidal or tectonic) or surface loading by atmospheric pressure changes. Under conditions of no vertical fluid flow and negligible well bore storage (static-confined conditions), the sensitivities to these effects depend on the elastic properties and porosity which characterize the surrounding medium. For a poroelastic medium, high sensitivity to applied areal strains occurs for low porosity, while high sensitivity to atmospheric loading occurs for high porosity; both increase with decreasing compressibility of the solid matrix. These material properties also influence vertical fluid flow induced by areally extensive deformation and can be used to define two types of hydraulic diffusivity which govern pressure diffusion, one for applied strain and one for surface loading. The hydraulic diffusivity which governs pressure diffusion in response to surface loading is slightly smaller than that which governs fluid flow in response to applied strain. Given the static-confined response of a water well to atmospheric loading and Earth tides, the in situ drained matrix compressibility and porosity (and hence the one-dimensional specific storage) can be estimated. Analysis of the static-confined response of five wells to atmospheric loading and Earth tides gives generally reasonable estimates for material properties.

Method and apparatus for simultaneous heat and mass transfer

Abstract: A method and apparatus for heat and mass transfer is described that is applicable to: concentration, crystallization, purification, fractionation, stripping, absorption, and/or heat exchange for liquid media; drying for solid or gel media; and temperature and humidity modification for gas media. Generally, using a moving gas, such as air at a constant and atmospheric pressure, a continual change in a vapor-liquid equilibrium is created between proximate but continually changing gas and liquid temperatures within energy transferring chambers. Chamber wetting, implemented segmentedly, allows mass transfer into and from the moving gas. A forced temperature differential in each chamber causes heat transfer between chambers by means of thermally conductive partitions. This transfer can allow condensation causing further evaporation in the opposite chamber resulting in a recycling of energy. Concurrent with temperature variances, the segmented wetting can further allow wetting substance concentrations caused by evaporation, selective condensation, or absorption to vary between wetted sectors. A migratory movement connecting these wetted sectors generally provides for development of applicable concentration gradients between the wetted sectors along the chamber length.

Kinetic simulation of gaseous species created by an electrical discharge in dry or humid oxygen

Abstract: A kinetic simulation of various neutral species created by the corona effect in dry or humid oxygen is presented. The physical conditions of the pulsed electrical discharge used are: atmospheric pressure, a gas discharge channel temperature in the 200 to 800 K range and an electron density Ne=5*1015 cm-3 or 1016 cm-3 with the electron energy assumed to be larger than 5 eV. The presence of water vapour leads to a non-negligible H2O2 production. Temperature and humidity have a cumulative effect on the O3 production. With multiple pulses, the maximal O3 concentration is obtained for a finite number of pulses.

Low‐temperature selective epitaxial growth of silicon at atmospheric pressure

Abstract: Epitaxial Si has been grown selectively on oxide‐patterned substrates from 850 down to 600 °C for the first time in the Si‐Cl‐H system at atmospheric pressure. Si deposition was achieved by hydrogen reduction of dichlorosilane in an ultraclean system using a load lock. Epitaxy was achieved at low temperatures only when the hydrogen was purified to remove traces of H2O and O2 implying that an oxygen‐free environment is the most important factor controlling epitaxy at low temperatures. Cross‐sectional transmission electron micrographs reveal perfect crystallinity in the epitaxial layer and a totally clean and featureless interface between epitaxy and substrate.

Glow plasma treatment at atmospheric pressure for surface modification and film deposition

Abstract: A plasma treatment at atmospheric pressure was developed employing a stable glow plasma at atmospheric pressure under selected conditions. The structure of the electrode, the kind of dilute gas, and the frequency of power were controlled. The surface fluorination of PET (polyethylene terephthalate) film, carbon thin film deposition and polymerization of ethylene by such a plasma are described here. The surface energy could be controlled by plasma treatment at various concentrations (O 2 /CF 2 /He). The ageing effect has been observed for 9 months by measuring the contact angle of a water drop on the surface and surface composition by XPS. The friction coefficients were measured at the fluorinated surface.

Absolute measurements of the thermal conductivity of mixtures of alkene-glycols with water

Abstract: New absolute measurements of the thermal conductivity of mixtures of methanol, ethanol, and propanol with water are presented. The measurements were performed in a tantalum-type transient hot-wire instrument at atmospheric pressure, in the temperature range 300–345 K. The overall uncertainty of the reported values is estimated to be less than ±0.5%, an estimate confirmed by measurements of the thermal conductivity of water. The mixtures with water studied have compositions of 25. 50, and 75%, by weight, of methanol and ethanol and 50%, by weight, of propanol. A recently proposed semiempirical scheme for the prediction of the thermal conductivity of pure liquids is extended to allow the prediction of the thermal conductivity of these mixtures from the pure components, as a function of both composition and temperature.

Method and apparatus for introduction of liquid effluent into mass spectrometer and other gas-phase or particle detectors

Abstract: Methods and apparatus for liquid sample introduction into chemical detectors that require the sample to be transformed from a flowing stream into either gaseous or particulate states. The effluent from either a process stream or a liquid chromatograph is nebulized by combined thermal and penumatic processes within an inner fused silicon capillary tube heated by conduction through a relatively conductive sheathing gas such as helium or hydrogen from a surrounding electrical resistance heated outer capillary tube composed of a pure metal having a comparatively high linear relationship between temperature and electrical resistance to provide a uniform conduction of heat energy to the inner tube to form a well-collimated, partially or completely desolvated aerosol, with the less volatile solute components of the sample stream remaining in the particulate state. An expansion chamber at atmospheric pressure or less pressure slows the sheathing gas which surrounds the solvent vapor and solute particles sufficiently to form a stream which carries the solute particles in a manner that they avoid impacting the walls of the expansion chamber. The gaseous components of the aerosol are then separated from the solvent-depleted solute particles using either cryotrapping or momentum separation. The enriched solute particles are vaporized, ionized, and/or detected by suitable gas-phase or particle detectors. The device is primarily an interface between the liquid chromatograph or process streams and the mass spectrometer.

Atmospheric Structure and Momentum Balance during a Gap-Wind Event in Shelikof Strait, Alaska

Abstract: Gap winds occur in topographically restricted channels when a component of the pressure gradient is parallel to the channel axis. Aircraft flight-level data are used to examine atmospheric structure and momentum balance during an early spring gap-wind event in Shelikof Strait, Alaska. Alongshore sea level pressure ridging was observed. Vertical cross sections show that across-strait gradients of boundary-layer temperature and depth accounted for the pressure distribution. Geostrophic adjustment of the mass field to the along-strait wind component contributed to development of the observed pressure pattern. Boundary-layer structure and force balance during this event was similar to that often observed along isolated barriers. However, the Rossby radius was lager than the strait width, and atmospheric structure in the strait exit region indicates transition of the flow to open coastline conditions. Two across-strait momentum budgets show that the Coriolis force and across-strait pressure gradient w...

Apparatus for control and intake air amount prediction in an internal combustion engine

Abstract: An apparatus to calculate the intake pipe pressure using the degree of throttle opening and the engine speed, to use this intake pipe pressure to calculate a current intake pipe pressure, and to determine a predicted value from this current intake pipe pressure and control fuel injection duration and/or spark timing. Because changes in the atmospheric pressure and changes in the air amount flowing through a bypass bypassing the throttle, etc., cause errors in the values predicted for the intake pipe pressure, there are irregularities in the exhaust emissions. The atmospheric pressure and the intake pipe pressure, etc., detected by a pressure sensor are used to correct the predicted value, and prevent irregularities and the like in exhaust emissions.

Transmission of externally applied negative pressure to the underlying tissue. A study on the upper arm of man.

Abstract: The transmission to the underlying tissue of externally applied negative pressure (2-50 mmHg) was studied in 15 male volunteers on a segment of the upper arm 8 cm in length enclosed in a clear plastic cylinder sealed hermetically against the skin. Pressure recordings were obtained from the anterior and posterior tissue compartments from sites along the entire tissue segment exposed to negative pressure at depths from the skin surface ranging from 5 to 62 mm. Reduction of pressure in the cylinder caused rapid decline, and cessation of external negative pressure rapid recovery, of tissue pressure. In the steady-state phase of negative tissue pressure, the applied external pressure change was in the great majority of experiments transmitted fully or almost fully to the tissue, regardless of from which position along the tissue segment and from which tissue depth pressure was recorded and regardless of the magnitude of the applied negative pressure. The described findings suggest that a defined reduction of atmospheric pressure leads to a similar alteration of vascular transmural pressure and that the technique of external negative pressure can be used for not only qualitative but also quantitative studies of local circulatory reactions evoked by such transmural pressure changes.

Influence of Gas-Injector Geometry on Atomization Performance of Aerated-Liquid Nozzles

Abstract: The atomizing performance of an aerated-liquid nozzle is examined with special emphasis on the influence of gas-injector geometry on spray characteristics. A Malvern spray analyzer is used to measure mean drop sizes and drop-size distributions. All measurements are carried out when spraying water into air at normal atmospheric pressure and temperature. The gas employed is nitrogen. Injection pressures are varied from 34.5 to 690 kPa (5 to 100 psid) and gas/liquid mass ratios from 0.002 to 0.023. Two different gas injectors are used, one having a single hole of 0.63 mm diameter, and the other 20 holes, each of 0.5 mm diameter. These two configurations were selected to provide a wide variation in gas-injector geometry. They are used in conjunction with three injector-orifice diameter. Measurements of liquid flow rates indicate that the injector orifice diameters of 0.8, 1.6, and 2.4 mm. The results show that atomization quality depends mainly on injection pressure and gas/liquid ratio, and is less sensitive to gas-injector geometry and injector-orifice diameter. Measurements of liquid flow rates indicate that the injector orifice has a very low discharge coefficient. This could prove very advantageous in applications where the liquid to be atomized contains solid particles or contaminants that would tend to block the small holes and passages of conventional nozzles.

Methane oxidation at room temperature and atmospheric pressure activated by light via polytungstate dispersed on titania

Abstract: Reference LPI-ARTICLE-1989-010View record in Web of Science Record created on 2006-02-21, modified on 2017-05-12

Viscosity of liquid hydrocarbons, mixtures and petroleum cuts, as a function of pressure and temperature

Abstract: The viscosity and density of petroleum fractions obtained from «Arabian light» has been measured as a function of pressure (1-1000 bar) and temperature. Different models previously tested on simpler systems (pure alkanes, pure alkylbenzenes, and mixtures of alkanes) have been used, and the experimental data have been fitted to a mean deviation of 2.1% and a maximum deviation of 7.3% for 216 experimental values. The model selected here needs only one viscosity measurement at atmospheric pressure and at one temperature, for a given fraction

Atmospheric pressure ionization tandem mass spectrometric system for real-time detection of low-level pollutants in air

Abstract: An atmospheric pressure ionization tandem mass spectrometric (API) (MS/MS) system is described that is capable of detecting, in real time, very low levels of contaminant ( 90/degrees/C), high humidity (>90% RH), and the presence of 3% CO/sub 2/ and >400 ppm NO/sub x/. This source is versatile enough to easily replace conventional electron impact or chemical ionization sources in existing mass spectrometers.

Pressure-jump volume-relaxation studies of polystyrene in the glass transition region

Abstract: An apparatus has been constructed that permits the measurement of time-dependent changes in pressure near the point of vitrification. The same instrument is used for measuring steady-state PVT properties, which are necessary for a proper analysis of the dynamic measurements. The former experiments are referred to as pressure-jump volume-relaxation (PJVR) measurements and serve as a direct probe of the structural relaxation process that occurs in all glasses. Experiments have been performed on polystyrene from 110 to 150°C and up to 2 kbar using pressure steps of 500 bars. The qualitative observations are analogous to those obtained at atmospheric pressure by rapid changes in temperature, namely (1) nonlinearity, (2) asymmetry, and (3) memory effects associated with complicated temperature or pressure histories. Each of these effects is accounted for semiquantitatively by a phenomenological order-parameter model that has been extended to include the effect of pressure. Deviations between theory and experiment increase as temperature and pressure increase, this being manifest mostly in a predicted recovery curve (expansion isobar) that recovers the equilibrium volume more quickly than the experimental data; the contraction isobars are in most cases predicted within experimental error. The adjustable parameters of the model are found to vary somewhat with pressure and temperature, apparently due to variations in δ and Δκ. The activation volume suggests that 10–20 monomer segments are involved in the recovery process, assuming that the activation volume itself represents only a fraction of the dynamic unit (as observed in molecular glasses).

Method and apparatus for PCVD internal coating a metallic pipe by means of a microwave plasma

Abstract: A microwave plasma method/of depositing a coating of a prescribed material on the internal surface of a pipe by means of a reaction of a vapor phase providing a prescribed material in which: (a) an atmosphere at a pressure less than atmospheric pressure containing the vapor phase is introduced into the pipe, (b) microwave energy is beamed into the pipe which is propagated along the length of the inside of the pipe, (c) a magnetic field is generated in a localized area of the pipe in which electron cyclotron resonance occurs for the the frequency of the microwaves, and in which, pressure, field strength of the magnetic field and the power of the high-frequency field are selected that a low-pressure gas discharge results in the area of the magnetic field to trigger the reaction furnishing the prescribed material, and (d) in which the magnetic field and thus the plasma are transposed along the length of the pipe.

Spark ignition of methane and methanol in ozonized air

Abstract: Spark ignition experiments using constant voltage and constant current electric pulses were performed in a closed vessel at reduced pressure for premixed methane and methanol mixtures with partially ozonized air. Minimum pulse durations for successful ignition were determined for various equivalence ratios and ozone contents. The pulse duration could be shortened considerably by adding small amounts of ozone to both fuels, particularly to methane. The effects were clearly observed with a 0.2% ozone fraction of oxygen in the ozonized air. The burning velocity of premixed methane/air at room temperature and atmospheric pressure was also measured and found to be increased somewhat in the presence of ozone. Kinetic model calculations for the ignition process of methane and methanol mixtures with ozonized air were carried out numerically at given elevated temperatures. The ignition delay times obtained reproduced the trends found in the experimentally determined minimum pulse durations. Inspection of the calculated evolution of species concentrations indicates that the acceleration effect is caused by the production of oxygen atoms which attack parent fules to induce radical chain reactions. Thus ozonezed air may be useful for improving the ignitability of various fuel mixtures.

Method and apparatus for pressure sticking a thin film to a base plate

Abstract: Apparatus and method for pressure and heat sticking a thin film to a base plate. The thin film and a base plate on a film like carrier are introduced into a vacuum chamber having upper and lower contact members for compressing the thin film, base member and carrier into a stratified body. The thin film and base plate are held separate from one another in the chamber. The lower contact member moves upward to contact the carrier and base plate and to compress the stratified body between it and the upper contact member. The upper contact member is convex in shape and made of an elastic material so that the contact pressure on the thin film and base plate starts near the center and spreads toward the periphery resulting in improved sticking of thin film to the base plate with no air bubbles and no wrinkling. The pressure is applied in a vacuum or reduced atmospheric pressure and heat is simultaneously applied. A further compression in the air at atmospheric pressure is carried out by a heat and pressure roller.

Femtosecond Laser Melting of Graphite

Abstract: Although graphite sublimes when heated adiabatically at atmospheric pressure, molten carbon is created under pulsed laser irradiation There have been conflicting claims, however, that the liquid phase is electrically insulating2,3 or conducting4,5 The former claim is based on time-resolved optical reflectivity measurements2 using 20 ps. pulses, in which reflectivity rapidly decreased after excitation above the melting threshold, suggesting creation of an insulating liquid phase.

Effect of Hydrostatic Pressure on the Swelling of n-Butylammonium Vermiculite

Abstract: The osmotic swelling of an n-butylammonium vermiculite in a 0.1 M solution of n-butylammonium chloride has been studied as a function of temperature and hydrostatic pressure by neutron diffraction. On application of a pressure of 1050 bar the vermiculite swelled macroscopically at 20°C, the c-axis spacing changing from 19.4 to 126 A. The phase transition was completely reversible with respect to both pressure and temperature, and a complete study of the temperature-pressure phase diagram was made at pressures as high as 2000 bar. The heat capacity change with temperature across the swelling transition was measured at atmospheric pressure, and the enthalpy and entropy of the change from crystalline to osmotic phases were found to be, respectively, 5.2 J/g and 0.0183 J/K·g of dry clay. The combination of the entropy change with the gradient of the pressure-temperature phase boundary gave the volume change accompanying the transition. The total volume of the swollen phase was less than that of the crystalline phase plus the appropriate amount of solution, corresponding to a fractional decrease of about 0.1% in the water volume from bulk solution to between the plates.

Method and apparatus for generating electricity using wave energy

Abstract: A wave power generating system for generating electricity using natural wave power, includes wave energy converters for converting wave energy into air pressure, a constant air pressure tank for storing the air pressure from the wave energy converters to equalize the fluctuation of the air pressure, an air turbine stationarily driven by the equalized air pressure, and an electric generator for generating stable electricity using the rotating power of the air turbine. The wave energy converters are settled to the bottom of the sea and are sufficiently tall to function as wave dissipation facilities. The air pressure in the constant air pressure tank is automatically controlled toward a target value by a controller and the target value is calculated by the controller in accordance with measured values of wave amplitude and period and the current air pressure of the constant air pressure tank. The wave power generating system can operate at the most efficiency when the air pressure in the constant air pressure tank is set to the target value.

Investigation of light emission from a parallel-plate avalanche chamber filled with noble gases and with TEA, TMAE, and H2O vapours at atmospheric pressure

Abstract: The light emission from avalanches in parallel-plate chambers, filled with noble gases and with TEA, TMAE, and H2O vapours at a total pressure p = 1 atm under the condition of low gas gain, has been investigated. Three important results have been obtained. 1. (1)|At partial pressures of more than a few Torr, and for a given charge gain, the light output from TEA, TMAE, and H2O in the spectral region 200–700 nm is much higher than from all other common quenching gases. 2. (2)|For these vapours, the ratio of light to charge is independent of their concentration when their partial pressure is more than a few Torr. 3. (3)|The best energy resolution achieved with the light-emitting chamber is ∼18% for 5.9 keV. Qualitative models explaining these results are given.

Impact of cathode evaporation on a free-burning arc

Abstract: A free-burning, high-intensity argon arc at atmospheric pressure was modelled during the evaporation of copper from the cathode. The effect of cathode evaporation on the temperature, mass flow, current flow and Cu concentration was studied for the entire plasma region. The copper evaporates from the tip of the cathode with an evaporation rate of 1 mg s-1. The copper vapour in the cathode region has a velocity of 210 m s-1 with a mass concentration of above 90% within 0.5 mm from the arc axis. The vapour passes from the cathode toward the anode with a slight diffusion in the argon plasma. Higher temperatures and current densities were calculated in the core of the arc caused by the cathode evaporation.

Communications. Furnace atomisation plasma emission spectrometry (FAPES)

Abstract: The development and initial evaluation of an atmospheric pressure helium radiofrequency plasma excitation source, established in a graphite furnace, are discussed for use in atomic emission spectrometry.