Showing papers on "Atmospheric pressure published in 1971"

Tropospheric Effect on Electromagnetically Measured Range: Prediction from Surface Weather Data

Abstract: Knowledge of the height integral of atmospheric refractivity (n — 1), where n is the refractive index, is essential for prediction of atmospheric range effect at any elevation angle. Observed values of the height integral for the lower, nonionized atmosphere can be obtained from weather balloon ascent data. Year-long collections of data from widely separated locations were used to relate this integral to surface data. Although (n — 1) at any point in a dry atmosphere depends on both pressure and temperature (the ratio P/T), the height integral of the observed dry part of (n — 1) is a linear function of surface pressure only, not of temperature. This is theoretically correct since P/T is equivalent to density, and the integral of density with height yields surface pressure. By application of this finding, the equivalent height for a (theoretically justified) quartic (n — 1) model (dry part) should be found to vary directly as surface temperature; the value obtained (least-squares fit to observed data) is 40.1 km for surface T = 0°C with a height expansion coefficient of 0.149 km per surface degree C. This would reduce the equivalent height to zero near 0° Kelvin. This theoretical model matches observed height integrals with an rms error of a few millimeters out of 2.3 meters (far less than 1%). Agreement between stations is excellent. A study of the more variable but much smaller wet part is in progress. The wet part is significant at radio but not at optical frequencies.

Mariner ultraviolet spectrometer: topography and polar cap.

Abstract: Mars, the red planet, reflects sunlight in the ultraviolet, but it is the atmosphere, not the surface, that is responsible for the reflected light. Even though there are atmospheric scatterers in addition to the molecular scatterers, it is possible to relate the intensity of the scattered radiation with the atmospheric pressure. The variation of pressure over the planet reveals the topography to vary over 7 kilometers in height and to be correlated with visible features. The carbon dioxide polar cap, in addition to being a cold trap for volatile gases in the atmosphere, may alsobe a very efficient adsorption trap for nonvolatiles. This last property may make the cap a repository for gases produced by geological or biological activity (15).

Method and apparatus for increasing power output and/or thermal efficiency of a gas turbine power plant

Abstract: A gas turbine power plant having a modified gas turbine cycle (Brayton cycle) wherein the compressor inlet air is super-chilled before it enters the compressor. Superchilling, as defined herein, means to supercharge the inlet air to increase the pressure thereof to a pressure level moderately greater than the atmospheric pressure and to chill the supercharged air to decrease the temperature thereof, the preferred temperature level being in the vicinity of about 40* Fahrenheit. A heat recovery cycle is provided to supply the energy necessary to superchill the compressor inlet air.

Improved excitation techniques for atmospheric pressure CO2 lasers

Abstract: A simple and rugged electrode structure is described for the production of uniform pulse-excited discharges throughout large volumes at atmospheric pressure. Output energy densities of 18 mJ/cm3 have been achieved in a multimode CO2 laser. The performance is compared with that of a novel mesh-cathode electrode system.

Measurements of atmospheric pressure on wind-generated sea waves

Abstract: Simultaneous measurements of wave elevation and atmospheric pressure on wind-driven sea waves were made using a vertical wave-sensing rod and a small (23 cm diameter) pancake-shaped styrofoam buoy in which was embedded a sensitive pressure transducer; the wave probe constrained the buoy to move with the waves only in the vertical direction. Care was taken to avoid contamination of the pressure signal with dynamic pressures caused by flow distortion around the buoy.Results are presented as power and cross-spectra of wave elevation and pressure, spectra of the fluxes of energy and momentum from the wind to the waves, and spectra of ζ the fractional increase in wave energy per radian.The phase shifts of the pressure signal are compared with the laboratory and field results of other investigators, and with the theoretical predictions of Miles's (1957) inviscid laminar model of wave growth. Agreement is reasonably good among the experimental results, but observed phase shifts are an order of magnitude larger than the theoretically predicted values.Integrals under the momentum flux spectra are compared in all runs with the predictions of the standard empirical formula, and in two cases are compared with the values of the total wind stress as measured with a sonic anemometer; the indication is that a large fraction of the total flux of momentum from the air to the sea goes initially into the wave field.The ζ spectra are compared with the field results of Snyder & Cox (1966) and with the theoretical predictions of Miles's (1957) model; agreement is again good between the field results while the theory underpredicts ζ by factors of between 5 and 8.A simple dimensionless relation is found between ζ and the ratio of wind speed to wave phase speed.

Atmospheric pressure CO 2 lasers giving high output energy per unit volume

Abstract: Two electrode designs are described that are capable of producing high output energy densities from pulsed atmospheric pressure CO 2 -N 2 -He lasers. In both cases a uniform volumetric excitation is obtained by the use of an auxiliary discharge. The first system uses a mesh cathode and has produced 4.8 J from an excited volume of 800 cm3(6 J.1-1). The second system uses a solid cathode and has produced 2 J from an excited volume of 110 cm3(18 J.1-1). Results of a parametric study of the solid cathode system are given. The output pulse energy, peak power, and pulse shape have been studied as functions of the energy-storage capacitor value, charging voltage, and gas composition. Partial self-mode-locking and the effect of single-mode operation on the pulsewidth have been observed.

The History and Stability of Atmospheric Oxygen

Abstract: There are three processes weakly concentration-dependent that keep changes in concentration of atmospheric pressure from being a random walk—inhibition of net photosynthesis by oxygen, the passage of hydrogen through the oxidizing part of the atmosphere before it escapes from the earth, and burial of reduced carbon in anaerobic water. A stronger regulator seems desirable but remains to be found. The cause of the initial rise in oxygen concentration presents a serious and unresolved quantitative problem.

Physical and Analytical Aspects of a Microwave Excited Plasma

Abstract: A microwave generator operated at about 100 W was used to maintain a narrow plasma (6 cm long × 0.3 mm diam) in flowing argon at atmospheric pressure. A tapered rectangular cavity was used to couple microwave power to the plasma discharge. Approximate temperature and electron density measurements of the plasma were made with and without water being nebulized; the temperature measurements indicated a lack of thermodynamic equilibrium. The plasma discharge was examined as a source of excitation in atomic emission spectrometry. An aerosol (produced by a system consisting of a pneumatic sprayer, a heated chamber, and a special condenser) was introduced into a plasma having an excitation and ionization temperature of about 5000 K and an electron density of about 1015 cm−3 at a position 0.3 mm from the center of the plasma. Limits of detection were measured for cadmium, gallium, indium, mercury, and zinc. Appreciable signals were also observed for calcium, lead, strontium, and boron, but no limits of detection were measured.

A simple expression for the saturation vapour pressure of water in the range −50 to 140°C

Abstract: Letp3=psexp(13?3815t-1?9760t2-0?6445t3-0?1299t4) where t=(1-Ts/T), T is absolute temperature, suffix s denotes the steam point and ps is standard atmospheric pressure, exactly 101 325 N m?2. Then p3 differs from the saturation pressure p of water vapour over a plane surface of the pure liquid phase at temperature T, as predicted by the generally accepted formulations, by less than ?0?1% of p at all temperatures between ?50 and 140?C.

Combustion of boron particles at elevated pressures

Abstract: Combustion of single boron particles, about 75 microns in diameter, from a crystalline powder sample has been studied. Particles were, ignited by being dropped through a focused laser beam in several oxidizing gases over a range of pressures In pure oxygen, in air, and in O2/Ar (20/80), particles were merely preheated to a temperature about 2000°K; ignition took place spontaneously after a measurable induction period. Quantitative values of both the induction period and the subsequent self-sustained combustion period are listed. In air and in the O2/Ar mixture, the burning times decrease from about 45 msec to about 20 msec as the pressure is increased from 1 to 35 atm. In pure O2 at atmospheric pressure, the total burning time is only 6.8 msec. In pure CO2 and in O2/N2 (7/93), there is no induction period, no selfignition, and no steady-state combustion; particles must be brought to a burning regime by an external energy flux, and they are able to maintain that regime for only a limited time before extinguishment. It is shown that the classical theory of ignition and combustion can account for all three observed burning modes: metastable surface reaction during the pre-ignition period rapid self-sustained diffusion combustion, and decaying combustion. Previously reported reaction-rate and ignition-limit data are used for quantitative estimates of parameters pertaining to the three regimes.

Sewage treatment process

Abstract: Domestic sewage and other polluted waters may be treated under a pressure of 1/2 to 5 atmospheres gauge or more with dissolved oxygen, or air, to supply the BOD. The oxygen-containing gas is drawn into the suction of a feed and recycle pump which agitates the liquid-gas mixture, and increases gas solubilization as it is being compressed. Simultaneously, any solids which are present are comminuted in being pumped to the pressure oxidation tank. The higher than atmospheric pressure increases oxygen solubility, concentration, and hence chemical or biochemical reactivity. Thus, a much smaller residence time and vessel is required, the polluted water is withdrawn and depressurized to atmospheric pressure at which pressure some of the dissolved oxygen and other gases are released due to lower solubility, and vented. Most of the liquid after depressurization is recycled to the influent stream for repressurization and additional oxygen dissolution. The recycle may amount to 2 to 50 times, and some sludge obtained may also be recycled. A water turbine may recover some of the mechanical energy used by the pump. The process may be used by itself or as an adjunct to other processes for treating polluted waters, and also for the oxidation of sludge.

Experimental investigation of transport properties of low-temperature plasma by means of electric arc

Abstract: The results of experimental investigations into the transport properties of low-temperature plasma carried out since 1960 in the Institute for High Temperatures of the USSR Academy of Sciences are summed up. Serving as the source of plasma was a well-stabilized dc arc. Properties of argon, nitrogen, air, and carbon dioxide plasma were studied at atmospheric pressure and at temperatures ranging from 7000° to 16 000°K. Data are presented on electric and thermal conductivity, total radiation of the aforementioned gases, as well as the results of investigations of argon viscosity up to 13 000°K.

Study on Distribution of Flow Rates and Flow Stabilities in Parallel Long Evaporators

Abstract: Distributions of flow rates and flow stabilities in parallel evaporator tube systems have been experimentally investigated. The evaporator is composed of three parallel copper tubes of 4mm inside diameter and 40 m long. Experiments were carried out by using refrigerant R-113 as the fluid in pressure range from atmospheric pressure to supercritical pressure, in order to simulate phenomena in steam generators. It has been shown that distributions of flow rates, their hysterisis and onset of excursion phenomena can be estimated from pressure drop versus flow rate curves for single tubes. Moreover, description is made of behaviors of thermal oscillative instability which are observed at relatively low flow rate. In addition to the experimental results, by a theoretical analysis of a simple model, stability criteria in parallel tube system have been described.

A Spectroscopic Source with Improved Analytical Properties and Remote Sampling Capability

Abstract: A direct current capillary arc operating in argon at atmospheric pressure has been combined with a device which produces fine particles directly from the surface of a solid metal sample. The aerosol generator is a simple device in which the sample acts as the cathode of a dc arc discharge. Rapid movement of the cathode spot produces uniform sampling over a well-defined area. A flowing gas stream transports the aerosol particles to the capillary arc discharge. Reproducibility and analytical curves are shown for ten elements in low alloy, stainless, and tool steel samples, for total analytical times of 10 sec.

High‐pressure laser action in 13 gases with transverse excitation

Abstract: Laser action has been achieved in 13 gases at high pressures using pulsed transverse excitation. A total of 149 wavelengths from 0.8 to 28μ was observed. Pulse lengths were found to lie in the range 0.2–5μsec. Several gases operate at atmospheric pressure and above and promise to give very high power outputs.

Erratum: high‐pressure laser action in 13 gases with transverse excitation

Abstract: Laser action has been achieved in 13 gases at high pressures using pulsed transverse excitation. A total of 149 wavelengths from 0.8 to 28μ was observed. Pulse lengths were found to lie in the range 0.2–5μsec. Several gases operate at atmospheric pressure and above and promise to give very high power outputs.

Nonequilibrium effects in an atmospheric argon arc plasma

Abstract: Thermal conditions in asymptotic region of atmospheric pressure Ar arc plasma, considering nonequilibrium ionization due to ambipolar diffusion

Raman Spectra in Molecular Solids II. Low Frequency Raman Spectroscopy as a Means to Study Phase Changes: More about the “Anomalous” γ-Phase of p-Dichlorobenzene

Abstract: The temperature dependence of the Raman low frequency spectra of the three solid polymorphic phases of p-dichlorobenzene has allowed us to prove that the so-called “anomalous” γ-phase is, in fact, the actual stable low temperature modification (below 279 K): we have shown that the transformation (α, γ) is reversible at atmospheric pressure. Our results and previous ones obtained under pressure by others lead us to deduce the existence of a triple point between the three solid phases of p-dichlorobenzene around room temperature and at pressures of the order of 500 bars.

Method for feeding dry coal to superatmospheric pressure

Abstract: A method for continuous feeding of dry coal particles from essentially atmospheric pressure to the superatmospheric pressure level of a coal gasifier or coal liquefaction reactor is achieved by a series of screw feeding devices each partially boosting the pressure level of the coal in stages to provide the dry coal at reactor pressure.

Motor-cycle suspensions

Abstract: A suspension system for motorcycles including an air pressure operated hydraulic ram connected between the wheels and body of the motorcycle. Instead of applying air pressure from a separate source to counteract heavy loads on the motorcycle and then releasing this pressure to atmosphere after removing the load, an adjustable volume chamber is provided wherein the air pressure acting on the ram may be raised or lowered by increasing or decreasing the volume of the chamber thus eliminating the need to release excess pressure to atmosphere or to replenish the pressure from an outside source everytime the load on the cycle is changed.

Transversely Pulse-Initiated Chemical Lasers: Atmospheric-Pressure Operation of an HF Laser

Abstract: Chemical laser action at atmospheric pressure has been observed from vibrational‐rotational transitions of HF produced by multiple transverse spark discharges in C3H8–He–SF6 mixtures. Lasing action was also observed when C4F8, C2F6, or CF4 replaced the SF6 and H2, CH4, C2H6, or C4H10 replaced C3H8. Peak‐pulse powers in excess of 0.5 MW were obtained at low pressures; at atmospheric pressure, peak powers were of the order of 30 kW. In some instances, the laser was superradiant at pressures up to 1 atm. P‐branch transitions from the v=3, 2, 1 vibrational levels of HF were observed. The pumping reaction was F + RH = HF† + R.

Electron-ion recombination in a dense molecular gas

Abstract: A semi-quantal method is developed for treating the recombination of electrons and positive ions in a dense molecular gas. Extensive calculations are carried out relating to recombination in hydrogen, in nitrogen, in carbon dioxide and in damp mixtures of gases. This latter case is of special interest, recombination being greatly facilitated by the presence of quite a small amount of water vapour. A very high recombination coefficient is possible. For example in a nitrogen + hydrogen mixture which contains 20 % by volume of water vapour and which is at atmospheric pressure and at 2000 K the recombination coefficient is predicted to be between about 5.1 x 10 -9 cm 3 s -1 and 8.7 x 10 -9 cm 3 s -1 : here the lower limit is calculated by the semi-quantal method assuming that the energy levels of the recombining system are hydrogenic while the upper limit is calculated by a purely classical method assuming that the energy levels of the recombining system form a continuum. Recombination coefficients have been deduced from measurements on the ionization in flames at atmospheric pressure. The values obtained lie satisfactorily between the predicted limits.

Effects of humidity on the velocity of sound in air

Abstract: Measurements have been made of the effects of humidity on the velocity of sound in air at 20.00°C and normal atmospheric pressure in the audio frequency range. The velocity of sound was determined from measurements of the frequency of the decay of normal frequencies of a spherical chamber of very high Q. Contrary to the often‐made assumption that the addition of moisture increases the velocity of sound in air, these results show that as moisture is added to dry air the velocity of sound at first decreases. The velocity is minimum at a relative humidity (RH) of about 14%; then it rises. Above about 30% RH, the velocity increases linearly with increasing moisture content.

Preliminary Measurements of a Transversely Excited Atmospheric Pressure CO2 Laser

Abstract: The design parameters of a transversely excited atmospheric pressure CO2 laser using 1000 Ω. ballast resistors are determined from a series of energy measurements. Peak powers of the order of 1 MW/...