This paper deals with electron flux densities and electron energy flux densities in positive column discharges. Recent kinetic calculations by Uhrlandt and Winkler have revealed the interesting physical phenomenon of radially inward directed energy flux densities in positive column plasmas. We have used a self-consistent positive column model, based on an accurate and highly detailed Monte Carlo code, to study this effect in more depth. The results of this study show a rather complex physical picture of electron particle and energy flux densities. Electrons with low energies usually exhibit radially outward directed particle and energy flux densities. At energies above the threshold for electronic excitation particle and energy flux densities are usually inward directed. Only close to the wall, at total energies above the wall potential energy, do these flux densities point towards the wall. The thickness of this 'wall loss ...
In this paper we study theoretically a pulsed corona discharge plasma in air at atmospheric pressure. A selfconsistent one-dimensional model, using a flux-corrected transport numerical scheme, is presented to achieve it. The charged particle kinetics in this model are described by one-dimensional continuity equations coupled with Poisson's equations. The spatio-temporal local field, charge density variations and the velocity profile of an ionizing front are calculated to describe the dynamical behavior of corona discharge plasmas. The simulation results of a wire-in-cylinder corona discharge plasma explain the physical mechanisms of discharge processes. These results may also be apply to obtain the optimizing parameters for designing the plasma reactor.
Gyrokinetic particle simulation of edge pedestal formation and plasma rotation dynamics will be presented, and compared with experimental observations. Realistic tokamak edge geometry is used which include separatrix/X-point and material wall from EFIT g-eqdsk data. In order to handle adequately the spatially inhomogeneous electric potential in the scrape-off region, the full-f electron technique is used, in addition to the full-f ions. Monte Carlo neutral particles with wall recycling coefficient will be included self-consistently with the plasma kinetics. Ion-ion Coulomb collisions will be particle, momentum and energy conserving. Energy source for the pedestal and scrape-off plasmas is the heat flow from the core plasma, and the particle source is the ionization of the neutral atoms which are either wall recycled and/or gas puffed. The simulation will be self-consistent with the first principles nonlinear neoclassical ...
We develop a large scale parallel viscous-elastic analysis program incorporating a mesoscopic self-consistent model developed by Laws. In the model, macroscopic elastic constants are treated as variables depending on the shape and statistical properties of pre-existing microscopic pores and change due to neutron irradiation. We apply this program to the visco-elastic analysis of nuclear graphite structures under neutron irradiation environment in High Temperature Gas-cooled Reactor (HTGR), as an example problem. Furthermore the calculated results by this parallel computational program are compared with those by one of commercial finite element analysis codes, FINAS, for validating elastic and thermal stress analysis function. (author)
The high pressure discharges (pulsed or D C corona, barrier, gliding and the others), have been studied both experimentally and theoretically as sources of low temperature plasma for pollution control technologies. The potential of electrical discharge methods has been demonstrated for the decomposition of many types of VOC. The air or oxygen are used as a feed gas in which pollutant is diluted. The ozone production in air or oxygen in such discharges is also discussed
Results are described of a study and of the characteristics of sources of a non-equilibrium gas-discharge plasma. The plasma generators considered include glow, high frequency, and arc discharge generators. Thermodynamic, ionic, and electronic processes occurring in the plasmas are evaluated.
The present article studies the electret state of polymers when moving through an alternating-current corona discharge plasma and investigates means for the determination of the transition of the polymeric material from the initial state of the electret when the corona-displaying voltage is increased.
We discuss the foundations of factor or regression models in the light of the self-consistency condition that the market portfolio (and more generally the risk factors) is (are) constituted of the assets whose returns it is (they are) supposed to explain. As already reported in several articles, self-consistency implies correlations between the return disturbances. As a consequence, the alpha's and beta's of the factor model are unobservable. Self-consistency leads to renormalized beta's with zero effective alpha's, which are observable with standard OLS regressions. Analytical derivations and numerical simulations show that, for arbitrary choices of the proxy which are different from the true market portfolio, a modified linear regression holds with a non-zero value $\\alpha_i$ at the origin between an asset $i$'s return and the proxy's return. Self-consistency also introduces ``orthogonality'' and ...
TIGER integral-field spectrography and HST/WFPC2 imaging of the E3 galaxy NGC 2974 are used to derive the kinematics of the stellar and ionized gas components in its central 500 pc. We derive a numerical two-integral distribution function from a MGE mass model using the HQ formalism. The TIGER as well as published long-slit stellar kinematics are well fitted with this self-consistent model, requiring neither the addition of a significant mass contribution from a hidden disc structure, nor the presence of a central dark mass. The data reveal the presence of a striking, highly contrasted, two-arm gaseous spiral structure within a radius of ~200 pc, corresponding to a total mass of 6.8x10^4 Msun of ionized gas. We use a deconvolved TIGER datacube to probe its kinematics at a resolution of about 0.35 arcsec. Strong departures from circular motions are observed, as well as high velocity dispersion values on the inner side of the ...
Ozone formation by a pulse positive corona discharge generated in the gas phase between a planar high voltage electrode made from reticulated vitreous carbon and a water surface with an immersed ground stainless steel plate electrode was investigated under various operating conditions. The effects of gas flow rate (0.5-3 litre min"-"1), discharge gap spacing (2.5-10 mm), applied input power (2-45 W) and gas composition (oxygen containing argon or nitrogen) on ozone production were determined. Ozone concentration increased with increasing power input and with increasing discharge gap. The production of ozone was significantly affected by the presence of water vapour formed through vaporization of water at the gas-liquid interface by the action of the gas phase discharge. The highest energy efficiency ...
With the help of heat balance equation and high temperature thermodynamic function, the calibration relation of jet temperature with discharge power, gas flow rate was obtained for nitrogen thermal plasma. It was shown that the results were agreed with the principle of similarity. The jet temperature was a function of Peff/f, instead of a general two variables function of Peff and f, which were effective discharge power and working gas flow rate, respectively. A related discussion has been given; it will be referable to thermal plasma applications. (authors)
Pulsed DC-plasma nitriding has been applied to form nitride layer having only a diffusion layer. The discharge current with the variation of discharge gases is proportional to the intensity of N{sub 2}{sup +} peak in optical emission spectroscopy during the plasma nitriding. The discharge current, microhardness in surface of substrate and depth of nitride layer increased with the ratio of N{sub 2} to H{sub 2} gas in discharge gases. When the ratio of N{sub 2} to H{sub 2} is lower than 60% in the discharge gases, high microhardness value of 1100Hv nitride layer which contains no compound layer has been formed. (author). 20 refs., 6 figs., 1 tab.
Doped ultrafine silicon dioxide powder with a narrow particle size distribution was obtained by RF discharge-stimulated dichlorosilane (SiH2C) oxidation at a low pressure using isobutylene as the combustion inhibitor and chromium hexacarbonyl (Cr(CO)6) as the dopant. The formation and morphology of the ultrafine particles are governed by the parameters of the RF discharge and by the chemical mechanism of the combustion reaction yielding the aerosol. Submicron-sized filamentous carbon structures can be obtained by isobutylene decomposition under spark discharge conditions in the presence of a molybdenum metal catalyst.
O.K. Andersen has recently introduced a linear augmented plane wave method (LAPW) for the calculation of electronic structure that was shown to be computationally fast. A more general formulation of an LAPW method is presented here. It makes use of a freely disposable number of eigenfunctions of the radial Schroedinger equation. These eigenfunctions can be selected in a self-consistent way. The present formulation also results in a computationally fast method. It is shown that Andersen's LAPW is obtained in a special limit from the present formulation. Self-consistent test calculations for copper show the present method to be remarkably accurate. As an application, scalar-relativistic self-consistent calculations are presented for the band structure of FCC lanthanum. (author).
In this article, the results of low-current gas-discharge plasma generator investigations carried out by a group of scientists from the Kazan' Aviation Institute are presented. When considered necessary, the results are compared with the data obtained by other authors. The basic configurations and theoretical calculation peculiarities of plasma generators are described. The electrical, thermal and energy characteristics of discharges in gas flows, as well as summarised empirical formulae and experimental data necessary for calculations and design of plasma devices are presented. (author)
A physical explanation is given for the positive differential voltage-current characteristic seen at low current in weakly ionized, low-pressure positive column discharges in argon/mercury gas mixtures. {copyright} {ital 1996 The American Physical Society.}
This report documents the activities by Rogers and Associates Engineering Corporation personnel in the second year of a grant from the Office of Health and Environmental Research at the US Department of Energy. The project objective is to integrate theories of all significant radon generation and transport mechanisms into a unified, self-consistent theory. During the second year of the project, the following activities were performed. Several field permeabilities were measured to develop a soils data base for a simple permeability correlation. Simple soil gas permeability and radon diffusion coefficient correlations were developed from the RAE data base. A methodology was developed to characterize the air permeabilities and radon diffusion coefficients of soils in general, and the Soil Conservation Service soil classifications in particular. The RAETRAN code was benchmarked against two different sets of measurements. Using RAETRAD, a ...
We propose a method of plasma production by capacity-coupled multidischarge (CCMD) at atmospheric pressure. The discharge gaps in the CCMD consist of a common electrode and a number of compact electrodes (CCE) which are directly coupled with small capacitors for quenching the discharge. A simple CCE structure is provided by a cylindrical capacitor, the inner conductor of which is used as a gap electrode. A short pulse discharge is observed to appear homogeneously at each CCE. A charge transfer for the single-pulsed discharge is 10-100 times as large as that of the conventional dielectric barrier discharge. A high efficiency of ozone production has been confirmed in the CCMD using O_2 gas. A device configuration of the CCMD is quite flexible with respect to its geometrical shape and size. The CCMD could be used to produce plasmas for various kinds of industrial ...
This book discusses the progress and problems of current interest in gaseous dielectrics and their use, with special emphasis on insulation in high-voltage transmission lines and substations. Topics covered include: basic physics of gaseous dielectrics; basic mechanisms; gas decomposition, reactions and toxicity; diagnostics and field probes; gases and mixtures for GIS transformers and circuit breakers; gaseous media for discharge chemistry and etching/corona; gas engineering for pulsed power and switching; gas breakdown under steep-fronted voltages; new developments in gas-insulated equipment and gas handling; gas/insulator interface/flashover; and quality control in testing gas-insulated equipment. Contains approximately 85 papers.
A flowing carbon dioxide laser was operated at low pressures up to 4 torr. Excitation of the laser was provided using various combinations of direct current (DC), pulsed microwave, and continuous wave (CW) microwave excitation. The microwaves were in the 2.45 GHz band and were coupled into the gas using a slow-wave interdigital transmission line. Laser output of 25 milliwatts (mw) was achieved using a DC discharge only. A combination of a DC discharge and pulsed microwaves doubled the output and resulted in some modulation. Changing the laser gas mixture and pulsed microwave field characteristics allowed some flexibility in the modulation. Lasing was not achieved with excitation from the CW microwaves alone due to the formation of localized discharges. Using pulsed microwaves to sustain the discharge and CW microwaves to pump the laser, a quasi-CW output of 55 ...
Using a simple model for soft self-consistent nonperturbative string fragmentation-recombination loops, we find that, in an open-string theory, ground-state particles necessary for the standard model either become tachyons or acquire large (Planck-scale) masses, making them unacceptable for sub-Planck-scale phenomenology. No comparable difficulties are evident for closed-string theories.
The applicability of Broyden's second method for accelerating the convergence of self-consistent electronic-structure calculations based on the linearized augmented-plane-wave method is discussed in terms of a W(001) surface calculation. It is found that its use results in a significant improvement in the convergence of the calculation, and based on this it is concluded that its use should increase the size of the systems for which such calculations are feasible.
The paper deals with a model in which the motion of a gas in plasma accerators and high-curent discharges in the present of a skin effect is treated as expulsion by a 'magnetic piston' under the action of surface current flow. Specifically examined is the situation where the initial gas pressure is negligible in comparison with the magnetic pressure, and the motion of the gas may be treated as a self-simulating one. A system of hydrodynamic equations of the problem is derived and integrated by Adam's method. Results are plotted and discussed.
We have demonstrated that, with simple pH adjustment, volatile drugs such as methamphetamine, amphetamine, 3,4-methylenedioxymethamphetamine (MDMA), ketamine, and valproic acid could be analyzed rapidly from raw biofluid samples (e.g. urine and serum) without dilution, or extraction, using atmospheric pressure ionization. The ion source was a variant type of atmospheric pressure chemical ionization (APCI) that used a dielectric barrier discharge (DBD) to generate the metastable helium gas and reagent ions. The sample solution was loaded in a disposable glass pipette, and the volatile compounds were purged by nitrogen gas to be reacted with the metastable helium gas. The electrodes of the DBD were arranged in such a way that the generated glow discharge was confined within the discharge tub...
The purpose of this rulemaking is to amend the effluent limitations guidelines and standards for the control of discharges of certain pollutants associated with the use of synthetic-based drilling fluids (SBFs) and other non-aqueous drilling fluids in portions of the Offshore Subcategory and Cook Inlet portion of the Coastal Subcategory of the Oil and Gas Extraction Point Source Category. These proposed limitations apply to discharges or effluent generated when oil and gas wells are drilled using SBFs or other non-aqueous drilling fluids (collectively referred to simply as SBFs) in coastal and offshore regions in locations where drilling wastes may be discharged.
The phenomenon of runaway electrons (REs) at high values of the ratio field intensity/gas number density {ital E}/{ital N} and {ital N} up to the Loshmidt number {ital N}{sub {ital L}}{approx_equal}2.7{times}10{sup 19} cm{sup {minus}3} is described. REs are shown to govern the breakdown and discharges at such condition. {copyright} {ital 1996 American Institute of Physics.}
Plasma nitriding in glow discharge is a process of modifying surface properties of a material by which surface hardness, corrosion resistance, fatigue strength etc. of a material can be improved
In this paper we study different effects of excited molecules on swarm parameters, electron energy distribution functions and gasdischarge modeling. First we discuss a possible experiment in parahydrogen to resolve the discrepancy in hydrogen vibrational excitation cross section data. Negative differential conductivity (NDC) is a kinetic phenomenon which manifests itself in a particular dependence of the drift velocity on E=N and it is affected by superelastic collisions with excited states. A complete kinetic scheme for argon required to model excited state densities in gasdischarges is also described. These results are used to explain experiments in capacitively and inductively coupled RF plasmas used for processing. The paper illustrates the application of atomic and molecular collision data, swarm data and the theoretical techniques in modeling of gas ...
This report is devoted to the investigation of the influence of electron collisions and radial non-uniformity of plasma density on phase characteristics, spatial attenuation and wave field structure of slow symmetric electromagnetic waves that propagate along cylindrical waveguide structure. It has been shown that collision rate and radial non-uniformity of plasma density for various parameters of waveguide structure and dielectric affect essentially on the wave characteristics and consequently, on the parameters of gasdischarge that is sustained by this wave. The results obtained are of large importance for the construction of the theory of gasdischarges that are sustained by the surface electromagnetic waves.
A study is made into microhardness and structure of coatings on various system steels (37G2S, 25Kh5M, R6M5), obtained by ion nitriding in a low pressure (10"-"1 Pa) arc discharge plasma. A comparison of properties is accomplished for steels nitrided in an arc gasdischarge and in a furnace. It is stated that ion-plasma nitriding in an arc gas plasma generator is an efficient method of alloy steels hardening which allows changing the structure and increasing the hardness of a surface layer up to rather great depth
Vacuum arc with cathode spots on the cold electrode is widely used as a plasma generator in a such kind of devices like metal ion sources, plasma cathode electron guns, thing films deposition facilities and others. Most vacuum arc devices utilize a high voltage discharge across an insulator surface to provide a trigger plasma which in turn initiates the main arc discharge. Operation of vacuum arc in a repetitively pulsed mode required a stable triggering system for the long time. But with a discharge across the insulators the number of stable pulses is limited by 100,000 or little bit more. The better method for vacuum arc ignition is low pressure discharge. As shown in this paper it is possible to increase the lifetime of the ignition system in 10 times at least, but negative characteristic of this system is a relatively high pressure (about 0.1 mtorr). In some kinds of vacuum arc applications it is ...
A self-consistent pseudopotential method together with a mixed-basis set of plane waves and Gaussian orbitals are used to determine the electronic structure of the (001) surface of molybdenum. The pseudopotential is derived from a self-consistent calculation of the atomic levels and wave functions, and is tested for bulk molybdenum. The resulting bulk band structure and density of states are compared with existing augmented-plane-wave APW calculations. The same potential is applied to investigate the electronic structure of an uncontracted Mo (001) surface. A complete analysis of the surface states is given in terms of their distribution in the two-dimensional surface Brillouin zone, charge-density distribution, and the local density of states. The results are in very good agreement with recent photoemission measurements.
In order to judge the potential fluorescent lamp applications of various low-pressure positive column discharges it is necessary to measure the absolute power emitted in the ultraviolet region of the spectrum. For rare-gasdischarges the principle emission occurs in the vacuum ultraviolet so that it is difficult to measure the radiant emittance (power per unit area) of the resonance radiation by standard methods. Two independent techniques are discussed for measuring the radiant emittance of positive column discharges in the vacuum ultraviolet. These techniques are used to study xenon positive column discharges at the resonance wavelength of 147 nm. The first method relies on the measurement of the resonance level density by absorption techniques. The effective decay rate of the resonance level is then determined by the simulation of resonance radiation transport. These two ...
The pure xenon dc positive column discharge has been characterized for various xenon pressures, currents, and discharge tube radii. The absolute output at the 147 nm resonance transition has been measured using two independent techniques to yield the radiant emittance at 147 nm (power per unit surface area). The efficiency of 147 nm production is obtained by combining the measured radiant emittance with the measured electrical power per unit length deposited in the gas. The radiant emittance and the efficiency are the two principle figures of merit for characterizing the discharge as a source of VUV radiation. It is observed that the trends in efficiency and radiant emittance change substantially when the discharge transitions from two-step electron impact excitation/ionization at higher pressures to single-step electron impact ionization at lower pressures. Modeling of the xenon ...
A brief comparative review of possible mercury free fluorescent lighting technologies is presented, including rare-gas positive column discharges, molecular discharges, and dielectric barrier discharges. Detailed experimental results on xenon positive column discharges will then be considered. In order to judge whether xenon-based discharges are a viable UV source it is necessary to measure the radiant emittance (power per unit area) for the vacuum ultraviolet (VUV) resonance xenon emission at 147 nm. Two techniques to determine the VUV radiant emittance have been developed and applied to xenon discharges. One method combines the measured resonance level density using absorption spectroscopy and a calculation of the trapped decay rate for the resonance radiation to arrive at the radiant emittance at 147 nm. A second method utilizes a direct ...
In this paper, a novel type of a corona discharge plasma reactor was designed, which consists of needle-plate-combined electrodes, in which a series of needle electrodes are placed in a glass container filled with flue gas, and a plate electrode is immersed in the water. Based on this model, the removal of NO and SO2 was tested experimentally. In addition, the effect of streamer polarity on the reduction of SO2 and NO was investigated in detail. The experimental results show that the corona wind formed between the high-voltage needle electrode and the water by corona discharge enhances the cleaning efficiency of the flue gas because of the presence of water, and the cleaning efficiency will increase with the increase of applied dc voltage within a definite range. The removal efficiency of SO2 up to 98%, and about 85% of NOx removal under suitable conditions is obtained in our experiments.
An algorithm is proposed which treats the ECH generated potential in a self-consistent way, by extending the Monte-Carlo Fokker-Planck method used by Murakami [S. Murakami et al., Proc. 17th IAEA Fusion Energy Conference, Yokohama, 1998 (International Atomic Energy Agency, Vienna, in press), paper CN-69/TH2/1]. The additional physics is expected to influence the transport of both thermal and suprathermal electrons in a helical toroidal system. (author)
The self-consistent relativistic linearized-augmented-plane-wave method is applied to local-density calculation of electronic structure of TmS. It is found that thulium monosulphide is a compound with a trivalent state of thulium. The influence of spin-orbital interaction is shown for different symmetry states of electrons. Calculated densities of states are used for the estimation of the electron-phonon coupling constant. And in conclusion it is shown that TmS is a high temperature Kondo-like system. (author).
A high-voltage cathode initiates an electron emission, resulting in a reduction in the carbon dioxide concentration in exhaust gas from the burning of hydrocarbon fuel. Assuming that the observed carbon dioxide reduction is originated from the molecular decomposition, the energy needed for the endothermic reaction of this carbon dioxide reduction may stem primarily from the internal energy reduction in the exhaust gas in accordance of the first law of the thermodynamics. An oxygen increase due to the reduction in carbon dioxide in a dischargegas was observed in real time.
Cesium recovery from the polluted layers in the 1/3 scale hydrogen negative ion source for LHD-NBI system has tested. It was found, that the cesium recovery can be produced by additional discharges as from the cesium layer, aged by tungsten and residual gas, so as from the cesium layers, polluted by an occasional water leak. The highest cesium recovery to NI production was produced by a xenon arc, while glow discharge and arcing in hydrogen were less effective. The mechanism of recovery is the ejection of cesium from the underlying enriched layer by the arc and its transport to the surface. (author)
A high-density gas jet supersonic nozzle is reported in this paper. The jitter and actuation time of the nozzle is determined by the pin discharge and laser spark radiation respectively. The jitter time of the nozzle is within 10 ?s with the backing pressure as high as 25 bar. With a nanosecond laser pulse focused on the gas jet about 1 mm below the nozzle, the actuation time is calculated to be about 15 ms by detecting the laser produced spark radiation, which reveals the existence of the gas jet and the relative gas density evolving with time. Consequently the gas density is estimated to be well above 1019 cm-3, compared with theoretical simulations from the nozzle parameters.
The production of ozone in a negative corona discharge fed by carbon dioxide with embedded traces of oxygen and water has been studied. The presence of traces of oxygen in both pure and dry CO_2 leads to an increase in nascent ozone concentrations. In contrast, traces of water vapour (0-800 ppm) are shown to rapidly suppress ozone concentrations with the largest decreases being observed at lowest gas pressures in the discharge (300 Torr). The presence of water vapour did not considerably affect the electrical properties of negative dc corona suggesting that a chemical process is responsible for the ozone loss. We have shown that the addition of water up to a concentration of 1500 ppm has only a marginal effect on the processes of ozone formation but the catalytic cycle of ozone destruction involving OH radicals can be the reason for observed decrease in the total ozone concentration with increasing water concentration.
Results of experiments performed utilizing high-power microwave sources for laser-discharge switching and preionization are reported. These results are not definitive, but are promising. Significant preionization using microwaves is possible. Some ability to switch the discharge and operate a laser have been demonstrated. More work needs to be performed to perfect the microwave coupling to the laser mixture. In particular, experiments with the microwaves better concentrated between the electrodes should be performed. The best way to accomplish this appears to be using the side-feed geometry; however, a large expansion of the microwaves should occur (to well below the power able to break down the window), and then a cylindrical lens should be used to focus the microwaves between the electrodes. 2 references.
The decomposition of three ?-lactam antibiotics (amoxicillin, oxacillin and ampicillin) in aqueous solution was investigated using a dielectric barrier discharge (DBD) in coaxial configuration. Solutions of concentration 100 mg/L were made to flow as a film over the surface of the inner electrode of the plasma reactor, so the discharge was generated at the gas-liquid interface. The electrical discharge was operated in pulsed regime, at room temperature and atmospheric pressure, in oxygen. Amoxicillin was degraded after 10 min plasma treatment, while the other two antibiotics required about 30 min for decomposition. The evolution of the degradation process was continuously followed using liquid chromatography-mass spectrometry (LC-MS), total organic carbon (TOC) and chemical oxygen demand (COD) analyses. PMID:21514950
Purge water from a typical wet flue gas desulfurization system contains myriad chemical constituents and heavy metals whose mixture is determined by the fuel source and combustion products as well as the stack gas treatment process. A well-designed water treatment system can tolerate upstream fuel and sorbent arranged in just the right order to produce wastewater acceptable for discharge. This article presents state-of-the-art technologies for treating the waste water that is generated by wet FGD systems. 11 figs., 3 tabs.
The phenomenology of wire chamber aging is discussed and fundamentals of proportional counters are presented. Free-radical polymerization and plasma polymerization are discussed. The chemistry of wire aging is reviewed. Similarities between wire chamber plasma (>1 atm dc-discharge) and low-pressure rf-discharge plasmas, which have been more widely studied, are suggested. Construction and use of a system to allow study of the plasma reactions occurring in wire chambers is reported. A proportional tube irradiated by an {sup 55}Fe source is used as a model wire chamber. Condensable species in the proportional tube effluent are concentrated in a cryotrap and analyzed by gas chromatography/mass spectrometry. Several different wire chamber gases (methane, argon/methane, ethane, argon/ethane, propane, argon/isobutane) are tested and their reaction products qualitatively identified. For all gases tested except those containing ...
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 ...
Production of ozone and OH radical is required to advance the plasma chemical reactions in the NOx removal processes for combustion gas treatment. The corona discharge to the water surface is expected to induce the good conditions for the proceeding of the NO oxidation and the NO_2 dissolution removal into water. In order to get the fundamental data of the corona discharge over the water surface, the positive and negative V-I characteristics and the ozone production were measured with the multi needle and the saw-edge type of the discharge electrodes. The pulse corona characteristics were also measured with some different waveforms of the applied pulse voltage. The experiments were carried out under the atmospheric pressure and room temperature. Both the DC and the pulse corona to the water surface showed a stable and almost the same V-I characteristics as to plate electrodes though the surface of water ...
The most striking achievement in magnetic fusion experiments during last few years was the discovery of plasma detachment from material targets, a much needed effect for plasmas with high power fusion parameters. Due to the very low heat loads on the targets observed in these regimes and potentially low erosion of the targets, detached regimes look attractive from the International Thermonuclear Experimental Reactor (ITER) design point of view. Thus the author has experimental proof for the possibility for a co-existence of fusion relevant hot plasma in the core and a low temperature partly ionized plasma at the edge of magnetic fusion device. Although somewhat similar behavior of edge plasma was considered theoretically even before plasma detachment was found experimentally, it was not clear in the beginning how these theoretical and experimental findings would fit together. Now, after a few years of intensive additional experimental and theoretical studies, a ...
The energy bands and the nature of the conduction electrons have been studied for two intermetallic compounds of dysprosium, i.e, DyZn and DyRh, following the self-consistent augmented-plane-wave (APW) method. The convergence of energy was found to be rapid for DyZn because the shell of 3d"1"0 electrons for Zn lies below the conduction band. The Fermi energies (E/sub F/) have been calculated to be 0.421 and 0.477 Ry for DyZn and DyRh, respectively. The densities and the numbers of conduction electrons inside and outside the APW spheres in each of these compounds are calculated, and it is shown that the character of conduction electrons inside the APW sphere of Dy is predominantly of d type. In order to see the accuracy of these results, self-consistent calculations were done for DyZn for different choices of the exchange potentials, and the calculated number of conduction electrons did not change significantly. The consequence of the ...
The Green's function method in the Quasiparticle Time Blocking Approximation is applied to nuclear excitations in {sup 132}Sn and {sup 208}Pb. The calculations are performed self-consistently using a Skyrme interaction. The method combines the conventional RPA with an exact single-particle continuum treatment and considers in a consistent way the particle-phonon coupling. We reproduce not only the experimental values of low-and high-lying collective states but we also obtain fair agreement with the data of non-collective low-lying states that are strongly influenced by the particle-phonon coupling. (orig.)
The hyperfine interactions at the uranium site in the antiferromagnetic USb2 compound were calculated within the density functional theory (DFT) employing the augmented plane wave plus local orbital (APW+lo) method. We investigated the dependence of the nuclear quadruple interactions to the magnetic structure in USb2 compound. The investigation were performed applying the so called band correlated LDA+U theory selfconsistently. The selfconsistent LDA+U calculations were gradually added to the performed generalized gradient approximation (GGA) including scalar relativistic spin orbit interactions in a second variation scheme. The result, which is in agreement with experiment, shows that the 5f-electrons have the tendency to be hybridized with the conduction electrons in the ferromagnetic uranium planes.
The self-consistent-pseudopotential method is applied to the A-15 compounds Nb_3Ge and Nb_3Al. The Fermi energy is found to lie in a region of very flat bands having a bonding character along the Nb chains. Comparison with the band structures of the (nonexistent) A-15 materials Nb_3Nb and Nb_3/sup asterisk/ (chains only) suggest that the p states on the Ge and Al atoms are instrumental in determining the position of the Fermi level. There is little evidence for rigid-band behavior in the Nb_3Al/sub x/Ge/sub 1-x/ system. Studies of the effects of chain dimerization in Nb_3Ge suggest that states at R and M are more likely candidates to participate in structural transitions than states at GAMMA or X.
Exposure of teachers of physics to X-radiation emitted by instruments which are used for demonstrating rarefied gasdischarges during physics lessons at secondary schools is discussed. The measurements performed provide an explicit evidence that an effective, annual exposure dose under the most unfavorable conditions does not exceed admissible levels according to Polish regulations pertaining to persons non-occupationally exposed to ionizing radiation. (author). 3 refs,1 fig.
On handling nitric solutions in the glove box nitrous gases are formed that are sucked off via a heated activated charcoal filter and a catalyst cartridge containing e.g. the FG 590 H catalist (Degussa). By the activated charcoal the nitrous gases are reduced to N/sub 2/ and CO gas; the catalyst will oxidize CO to CO/sub 2/. The CO/sub 2/ obtained is discharged through an exhaust air filter in the glove box.
The possibility of surface modification of high-speed steel cutting tool by means of vacuum-plasma treatment including ion nitriding in gas plasma followed by the deposition of wear resistant (Ti, Al)N coatings in metal-gas plasma of a vacuum arc discharge is studied. The regularities of nitrided layer formation and the structure of these layers under various operation conditions of cutting tool are investigated. Optimum conditions of vacuum-plasma treatment providing the best wear resistance of cutting are determined
Non-thermal plasma treatment is a promising technique for the destruction of volatile organic compounds in waste gas. A relatively unexplored technique is the atmospheric negative dc multi-pin-to-plate glow discharge. This paper reports experimental results of allyl alcohol degradation and ozone production in this type of plasma. A new model was developed to describe these processes quantitatively. The model contains a detailed chemical degradation scheme, and describes the physics of the plasma by assuming that the fraction of electrons that takes part in chemical reactions is an exponential function of the reduced field. The model captured the experimental kinetic data to less than 2 ppm standard deviation.
An embodiment of a mercury-free fluorescent lamp combines a low pressure rare gasdischarges with a phosphor having a quantum efficiency grater than one. The choice of the rare gas depends on a number of factors, one of which is the resonance transition energy. Less demand is placed the quantum efficiency of the phosphor for a lower energy resonance photon. Xenon has the lowest energy resonance transition of the stable rare gases at 8.5 eV (147 nm) and thus is a good candidate to study. The usefulness of a xenon-based discharge depends on the radiant emittance of the discharge at the resonance wavelength of 147 nm. The radiant emittance from a low pressure xenon positive column discharge is measured using two independent techniques. The first relies on the measurement of the resonance level density using absorption techniques. The effective decay rate of the ...
Paraquat is a nonselective contact herbicide of great toxicological importance, being associated with high mortality rates, mainly due to respiratory failure. We report the case of a 22-year-old male admitted to the emergency room with a sore throat, dysphagia, hemoptysis, and retrosternal pain after the ingestion of 50 mL of a paraquat solution, four days prior to admission. Chest CT scans revealed pulmonary opacities, pneumomediastinum, pneumothorax, and subcutaneous emphysema. The patient was submitted to two cycles of immunosuppressive therapy with cyclophosphamide, methylprednisolone, and dexamethasone. The pulmonary gas exchange parameters gradually improved, and the patient was discharged four weeks later. The clinical and tomographic follow-up evaluations performed at four months after discharge showed that there had been further clinical improvement. We also present a brief review of the literature, as well as a ...
Paraquat is a nonselective contact herbicide of great toxicological importance, being associated with high mortality rates, mainly due to respiratory failure. We report the case of a 22-year-old male admitted to the emergency room with a sore throat, dysphagia, hemoptysis, and retrosternal pain after the ingestion of 50 mL of a paraquat solution, four days prior to admission. Chest CT scans revealed pulmonary opacities, pneumomediastinum, pneumothorax, and subcutaneous emphysema. The patient was submitted to two cycles of immunosuppressive therapy with cyclophosphamide, methylprednisolone, and dexamethasone. The pulmonary gas exchange parameters gradually improved, and the patient was discharged four weeks later. The clinical and tomographic follow-up evaluations performed at four months after discharge showed that there had been further clinical improvement. We also present a brief review of the literature, as well as a ...
We have studied the nature of continuum emitted in the visible spectral range from a noncontracted positive column of discharge in a cesium vapor-xenon mixture at a pressure of 45 Torr and at a degree of ionization below 3 ? 10?6. The main contribution to the continuous emission under such conditions is due to electron-xenon atom bremsstrahlung. The intensity of emission has been experimentally and theoretically studied as a function of the electric field strength and electron density in the positive column. It is established that an increase in the visible emission intensity with the electric field strength is related to an increase in the number of hot electrons in plasma.
Experiments of plasma nitriding of titanium are carried out by two plasma sources. One is a microwave discharge plasma source under several Torr, and the other is a nitrogen arc jet generated under atmospheric pressure followed by rapid expansion into a gas wind tunnel. The relationship between the surface density of nitrogen atoms in the #alpha#-Ti and various plasma parameters is systematically studied. For the microwave nitrogen plasma, it is found that the effect of the vibration temperature is the most essential for the surface nitriding, whereas the effect of electron temperature, density and rotation temperature is less remarkable. It is also found that the higher vibration temperature of the microwave discharge nitrogen plasma makes the target temperature higher, and consequently, the surface density of atomic nitrogen remarkably increased. However, the effect of target temperature is less remarkable for the arc jet ...
An apparatus capable of producing current or voltage controlled positive and negative ion beams in 1-atm oxidizing and nonoxidizing ambients between 25/sup 0/ and 950 /sup 0/C is presented. The apparatus utilizes a point-to-plane corona discharge in the gas phase. Room-temperature experiments revealed that the small differences in ion beam shape between the two polarities is primarily due to the difference in applied voltage required to produce the same current for the two polarities. Due to increased ion mobility and decreased threshold voltage at higher temperatures, a slight broadening of the ion beam current-density profiles for both positive and negative ions is predicted.
The authors investigated the application of pulsed corona discharge process to the removal of SO{sub 2} and NO{sub x} from industrial flue gas of an ioron-ore sintering plant. This study was performed on a pilot scale, which is the most advanced demonstration of this process. The flow rate of 5000 m{sup 3}/h of the flue gas was successfully treated. The electrode structure of the corona reactor is the same with that of conventional electrostatic precipitator. The authors made use of magnetic pulse compression technology to produce repetitive high voltage pulse. Pulse width (full width at half maximum) was reduced to less than 1 {micro}s by connecting a resister in parallel with the corona reactor. An inductor was added to the resister in series to minimize the loss by restricting the current flowing through the resister. By this way, they were able to deliver pulse power with peak voltage of 110 kV and peak current of 2.3 ...
Model phosphate-metal solvation complexes have been studied by ab-initio self-consistent-field techniques. The complexes studied include (RO)2PO2-(R = H or CH3) with Li+, Na+, K+, Be++, Mg++, Ca++,...Full Text Available
The mechanism proposed by Kormendy (1984) for the formation of counterrotating cores in elliptical galaxies is investigated using self-consistent numerical simulations of mergers between a high- and a low-luminosity elliptical galaxies. The conditions for a counterrotation to appear are determined, observational properties of the remnants are described, and the evolution of the structural and kinematic parameters of the larger galaxy is analyzed. It is shown that a counterrotation results only when the merging orbits are retrograde, due to a large change in the secondary spin during the merger. 36 refs.
Field reversed configuration (FRC) is a prospective high ? magnetic system for high efficiency D- 3He fusion reactor. Self-consistent FRC plasma profiles and static electric field for reactor calculations are discussed in framework of the model including flow equilibrium and collisionless transport equations. The extrapolations to reactor regimes of plasma confinement scaling laws are considered.
The effect of two-body nature of the nuclear shell model potential on the recent numerical calculations of the nuclear level density has been examined. For the two most widely used single particle energy level schemes based on harmonic oscillator and Woods-Saxon potential, this effect is shown to significantly modify the excitation energy dependence of the level densities. (author).
We apply our previously developed first-principles nonlocal pseudopotentials (obtained for all atoms of rows 1--5 in the Periodic Table) to study self-consistently the electronic structure of Si and Ge and the transition metals Mo and W. For Si and Ge we find that the first-principles pseudopotentials yield valence-band states in good agreement with the empirically adjusted pseudopotential and photoemission data, whereas the low conduction-band states appear to be consistently lower in energy due apparently to incomplete cancellation of the self-interaction effects. The calculated x-ray scattering factors (obtained by core orthogonalization of the pseudo-wave-functions) are in excellent agreement with experiment. The self-consistent valence charge density shows a distinct elongation of the covalent bond along the internuclear axis, in good agreement with the experimentally synthesized density. The systematic deviations of the empirical ...
Solid state effects are taken into account in an internal conversion coefficients computation by using Wigner-Seitz boundary conditions. Both the bound and free electron wave functions are calculated from an atomic Dirac-Hartree-Fock-Slater selfconsistent potential. These internal conversion coefficients are compared with those obtained from the usual free atom boundary conditions.
Solid state effects are taken into account in an internal conversion coefficients computation by using Wigner-Seitz boundary conditions. Both the bound and free electron wave functions are calculated from an atomic Dirac-Hartree-Fock-Slater selfconsistent potential. These internal conversion coefficients are compared with those obtained from the usual free atom boundary conditions. (orig.).
The defect-induced electron lifetime and energy-gap anisotropy effects on the T/sub c/ of the A-15 compounds are examined. A self-consistent model calculation demonstrates that the various defect dependences of T/sub c/ can be qualitatively understood in terms of the electron-lifetime effect.
The defect-induced electron lifetime and energy-gap anisotropy effects on the T/sub c/ of the A-15 compounds are examined. A self-consistent model calculation demonstrates that the various defect dependences of T/sub c/ can be qualitatively understood in terms of the electron-lifetime effect.
New measurements of relative gamma-ray emission probabilities in the decay of [sup 101]Mo and [sup 101]Tc are reported. Previously published conversion-electron data have been used along with the gamma-ray data to formulate self-consistent decay schemes. (orig.)
New measurements of relative gamma-ray emission probabilities in the decay of "1"0"1Mo and "1"0"1Tc are reported. Previously published conversion-electron data have been used along with the gamma-ray data to formulate self-consistent decay schemes. (orig.).
Coherent oscillator radiation is considered. A comparison is made with classical particle radiation with gauss distribution. Decay probability for coherent state in spontaneous radiation is estimated. The method suggested for describing harmonic oscillator allows to separate the effect of classical field radiation from quantum description of particle state within the framework of a self-consistent quantum mechanical problem.
To calculate the energy band structures in semiconductors using the relativistic augmented plane wave method, atomic potential and charge density are needed, which are calculated by self-consistent method. Wave function for one electron is determined by solving the Dirac equation with the Hartree-Fock equation based on the slater's exchange potential. The results of calculation for Cu"+"1 are given. (Author).
Calculations of the Compton profiles for the transition metals Ta and W are performed, using electron wave functions obtained from self-consistent augmented plane wave (APW) band structure calculations within the local density formalism of Hedin-Lundqvist. Relativistic effects are included except for the spin-orbit interaction. The observed structures of the Compton profiles in these metals are understood in terms of the topology of their Fermi surfaces. (author).
A series of experimental measurements of ozone concentration produced by irradiation of noble gas (He, Ne, and Ar)-O_2 and noble gas-O_2- SF_6 mixtures with energetic (MeV) helium and lithium ions are reported. Continuous irradiations at dose rates of 10"1"5-10"1"7 eV cm"-"3 S"-"1 for a few hundred milliseconds were used. The resulting ozone concentration was found to be nonlinear with dose rate for a given irradiation time. This nonlinearity was effectively reduced by an increase in noble gas pressure. Few mole percent addition of SF_6 generally resulted in an increase in the ozone concentration. This increase was highest for lower noble gas pressures and longer irradiation times. Further SF_6 addition, however, caused a reduction in the ozone concentration. Results are explained by considering the relevant reactions responsible for ozone production and loss.
The design and parameters of a UV-VUV spontaneous radiation source - an excilamp operating on chlorides of rare gases ArCl{sup *}, KrCl{sup *} and XeCl{sup *} in the wavelength range 175-308 nm are presented. The Ne-Xe(Kr, Ar)-HCl mixtures were excited by a high-pressure self-sustained discharge with spark preionisation. It is shown that upon pumping mixtures of rare gases and halogens by a transverse discharge, the intensities of the B-X emission band of molecules ArCl{sup *}, KrCl{sup *} and XeCl{sup *} are comparable and up to 90% of the emission energy of excilamps can be concentrated in the UV region. The peak UV power density at 222 and 308 nm on the output window of the excilamp was {approx}2 kW cm{sup -2} for the pulse energy up to {approx} 3 mJ. The output emission energy of the excilamp at 175 nm achieved {approx}0.6 mJ and the peak power density was {approx}0.4 kW cm{sup -2}. (laser applications and other topics in quantum ...
Based on the results obtained for C-N and Si-C-N films, a systematic investigation of reactive magnetron sputtering of hard quaternary Si-B-C-N materials has been carried out. The Si-B-C-N films were deposited on p-type Si(100) substrates by dc magnetron co-sputtering using a single C-Si-B target (at a fixed 20% boron fraction in the target erosion area) in nitrogen-argon gas mixtures. Elemental compositions of the films, their surface bonding structure and mechanical properties, together with their oxidation resistance in air, were controlled by the Si fraction (5-75%) in the magnetron target erosion area, the Ar fraction (0-75%) in the gas mixture, the rf induced negative substrate bias voltage (from a floating potential to -500 V) and the substrate temperature (180-350 deg. C). The total pressure and the discharge current on the magnetron target were held constant at 0.5 Pa and 1 A, respectively. The energy and flux of ...
Fully-fired combined cycle plants utilizing the high temperature gas turbine discharge as gas intake for a coal-fired steam generator were developed in the 1960's. Long-term experience and the excellent reliability statistics of the gas turbines of these plants have proven that the thermodynamic, economical and ecological advantages of combined cycle units over conventional units strongly suggest such plants for fossil-fuel applications. This paper describes the design and operation of these plants. Topics are Gersteinwerk Unit K combined-cycle power plant, plant design concept, design criteria and performance, gas turbines, steam generators, steam turbines, various modes of operation, typical plant start-up, environmental considerations, prototype plants and topping old steam turbine plants. It concludes that combined-cycle plants provide efficiencies over 45% with low ...
A simple analytical model of the barrier discharge in a long gap between opposing plane electrodes is developed. It is shown that the plasma density becomes uniform over large part of the gap in the course of the discharge development, so that one can speak of a formation of a dynamic positive column. The column completely controls the dynamics of the barrier discharge and determines such characteristics as the discharge current, discharge duration, light output, etc. Using the proposed model, all discharge parameters can be easily evaluated
Object: To provide a tank, which can safely and reliably accommodate high temperature sodium containing radioactive substance in case of occurrence of an accident in a sodium system and thus prevent spread of contamination. Structure: A sodium drain duct inserted into a tank from above the tank is provided at the position of its lower end with a buffer means for preventing direct flow-down of sodium to a bottom plate. A means for preventing the discharge of radioactive substance to the cover gas is provided above the lower end of the sodium drain tube so as to surround the sodium drain tube. (Kamimura, M.).
With the aim of optimizing the nitriding process parameters (temperature and gas mixture ) experimental studies of the plasma nitriding of Ck 15 steel were carried out, using a D. C. glow discharge. Nitriding treatments were performed at 450, 500 and 550 and N_2/H_2 volume ratio of 3/1, 1/1 and 1/3 for 5 hours. Nitriding treatment produces modified surface layer consisting of an outer compound layer and an inner diffusion layer.The plasma nitriding of Ck 15 produce single white layer consisting of #gamma#-(Fe_4N).
Experimentally it is shown that a movable grounded metallic plate placed inside a multi-dipole magnetic cage can vary the diffused plasma parameters such as density, plasma potential and electron temperature. Plasma is solely produced in the source section of a double plasma device by a dc hot filament discharge and a low-density plasma is produced in the target section by local ionization of neutral gas by the high energetic electrons coming from the source section. A grounded movable stainless steel plate is inserted in the target section of the device. The floating potential of the plate also changes depending on the position of the plate inside the magnetic cage.
Field studies were conducted May 28-June 1, 1979, to determine the chemical composition and physical behavior of discharges from an offshore gas drilling rig in the central basin of Lake Erie. The drilling operation was observed for four days, from rig jackup to the circulation of mud through the borehole after drilling had been completed. Resuspension studies using nephelometry, supplemented with chemical analyses, indicated little resuspension of lake bottom materials or release of metals to the water column during rig jack-up. Portions of the turbidity plumes generated during drilling were buoyant. Three surface turbidity plumes were mapped with nephelometry to a point at which particulate concentrations reached background levels in the Lake. Detectable plumes were approx. 400 to 1500 m in length and had maximum widths < 230 m. A chemical survey conducted in the plume during early gas shows indicated that ...
The analysis is submitted in support of the effluent limitations guidelines and standards for the Coastal Oil and Gas Industry. The report analyzes the cost-effectiveness of 10 regulatory options organized by three wastestreams. The document compares the total annualized cost incurred for each of the regulatory options within each wastestream to the corresponding effectiveness of that option in reducing the discharge of pollutants. Section Two discusses the cost-effectiveness methodology used and identifies the pollutants included in the analysis, presenting their toxic weighting factors and removal efficiencies. Section Three presents the results of the analysis. In Section Four, the cost-effectiveness values are compared to cost-effectiveness values for other promulgated rules. Appendix A presents data on pollutants, pollutant removals, annualized costs, and other, more detailed information.
We provide a numerically efficient procedure to perform LDA+Hubbard I calculations including self-consistency over the charge density in the FP-LAPW basis. The method is applied to Pu, Am, and PuAm and PuCe alloys. Our results for valence photoemission spectra (PES) agree with experimental data and with previous LDA+DMFT calculations. Analysis of the J=5/2 and J=7/2 contributions to the f-occupation supports the intermediate-coupling picture of f-states in heavy actinides. The electronic specific heat coefficient is calculated for PuAm and PuCe alloys in reasonable agreement with recent experiments. We show that Pu atoms keep their mixed-valence character in these alloys. Next, we study electronic and spectral properties of Pu-based superconductor PuCoGa_5 and obtain good agreement with experimental PES. Finally, we analyze surface effects. In Pu monolayer, we find substantial modification of PES due to 5f-electron localization consistent with experimental ...
The possibility of improving the cold formability of wrought magnesium alloys is considered in light of their good hot forming characteristics. Magnesium alloy AZ31B sheet is selected as a model system. Parameters affecting formability, such as strain hardening rate, strain rate sensitivity, and the degree of anisotropy are examined systematically by conducting tensile tests over a range of temperatures (room temperature to 250 C) and strain rates (1 x 10{sup -5} to 0.1 s{sup -1}). The plastic anisotropy and deformation texture evolution are examined in samples aligned with the sheet rolling and transverse directions. Polycrystal plasticity simulations using a viscoplastic self-consistent (VPSC) formulation are used to model the observed anisotropy and texture evolution. The adjustable parameters in the model are the relative critical resolved shear stresses of the dislocation mechanisms known to operate within magnesium. The experimental results suggest that an ...
The Economic Analysis (EA) report is written to address the impacts of this proposed Effluent Limitation Guidelines and Standards for Synthetic-Based and Other Non-Aqueous Drilling Fluids. Currently, effluent guidelines pertaining to the discharge of drilling fluids address two specific types of fluids: Oil-based drilling fluids (OBFs) that use diesel and mineral oil, which are prohibited from being discharged; and Water-based drilling Fluids (WBFs), which can be discharged subject to meeting certain discharge requirements, including a sheen test and an aqueous toxicity test, in certain limited offshore regions. Section Two presents sources of data, Section Three presents the industry profile, Section Four discusses the regulatory costs of options under consideration for the proposed rulemaking, and Section Five discusses the impacts of the proposed rule on firms, well drilling, and production, and also ...
Extensive research into the treatment and control of Volatile Organic Compounds (VOCs) from semiconductor industry manufacturing processes has identified the need for alternatives to existing combustion devices. Specifically, semiconductor manufacturing design is moving toward exploiting effective, small-scale, abatement control technologies for specific point-of-use (POU) waste streams associated with a particular component or manufacturing tool. The Silent Discharge Plasma (SDP) developed at Los Alamos National Laboratory is a nonthermal plasma technology created by a dielectric-ballasted electrical discharge. Influent gas-phase pollutants are destroyed in the reactor by the free radicals or electrons generated by the plasma. This paper examines the potential for SDP to be used in niche circumstances for POU control of VOC exhaust streams specific to the semiconductor industry. A sensitivity analysis is presented, showing ...
The effects of various approximations used in performing augmented-plane-wave calculations were studied for elements of the fifth and sixth columns of the Periodic Table, namely V, Nb, Ta, Cr, Mo, and W. Two kinds of approximations have been checked: (i) variation of the number of k points used to iterate to self-consistency, and (ii) approximations for the treatment of the core states. In addition a comparison between relativistic and nonrelativistic calculations is made, and an approximate method of calculating the spin-orbit splitting is given.
The effects of various approximations used in performing augmented-plane-wave calculations were studied for elements of the fifth and sixth columns of the Periodic Table, namely V, Nb, Ta, Cr, Mo, and W. Two kinds of approximations have been checked: (i) variation of the number of k points used to iterate to self-consistency, and (ii) approximations for the treatment of the core states. In addition a comparison between relativistic and nonrelativistic calculations is made, and an approximate method of calculating the spin-orbit splitting is given.
Full text: Magnetic multilayer materials are becoming technologically important as they provide a more efficient means of magnetic reading and storage through utilisation of their giant magnetoresistance and oscillatory magnetic coupling. This study presents preliminary tight-binding calculations with a view of developing a consistent tight-binding model of `spin valve` Fe-Cu-Fe tri-layer materials. Further work involves using a self-consistent tight-binding approach to obtain a more accurate picture of this system and a better understanding of surface effects at the Fe-Cu interface 1 fig., 4 refs.
The phenomenon of time resonances (or explosions) can explain the exponential reduction of the energy, which is accompanied for the certain degree by slight fluctuations under some conditions in the range of the energy strongly overlapped compound-resonances. These resonant explosions correspond to formation of several highly-exited non-exponentially decaying nuclear clots (partial compound nuclei consisting of several small groups of projectile nucleons and targets). This paper is a continuation and expansion of theoretical authors' work, which is a more general self-consistent version of the time-evolution approach in comparison with the traditional Izumo-Araseki time compound-nucleus model.
The possibility of the existence of stable tetrahedral deformations at spin zero is investigated using the Skyrme-HFBCS approach and the generator coordinate method (GCM). The study is limited to nuclei in which the tetrahedral mode has been predicted to be favored on the basis of non self-consistent models. Our results indicate that a clear identification of tetrahedral deformations is unlikely as they are strongly mixed with the axial octupole mode. However, the excitation energies related to the tetrahedral mode are systematically lower than those of the axial octupole mode in all the nuclei included in this study.
Self-consistent electronic structure calculations have been performed on two compositions of scandium sulfide ScS and Sc/sub 3/S/sub 4/. The results of the calculation of ScS are similar to those obtained for other transition metal chalcogenides and are in excellent agreement with heat capacity and reflectance measurements as well as UPS experiments. The calculation of the defect structure indicates the creation of sulfur p nonbonding states in metal-deficient ScS. The valency of the metal ions remains unchanged upon the creation of vacancies.
In this paper we report on multi-physics, multi-billion macroparticle simulation of beam transport in a free electron laser (FEL) linac for future light source applications. The simulation includes a self-consistent calculation of 3D space-charge effects, short-range geometry wakefields, longitudinal coherent synchrotron radiation (CSR) wakefields, and detailed modeling of RF acceleration and focusing. We discuss the need for and the challenges associated with such large-scale simulation. Applications to the study of the microbunching instability in an FEL linac are also presented.
For a given linac design, the dosimetric characteristics of a photon beam are determined uniquely by the energy and radial distributions of the electron beam striking the x-ray target. However, in the usual commissioning of a beam from measured data, a large number of variables can be independently tuned, making it difficult to derive a unique and self-consistent beam model. For example, the measured dosimetric penumbra in water may be attributed in various proportions to the lateral secondary electron range, the focal spot size and the transmission through the tips of a non-divergent collimator; the head-scatter component in the tails of the transverse profiles may not be easy to resolve from phantom scatter and head leakage; and the head-scatter tails corresponding to a certain extra-focal source model may not agree self-consistently with in-air output factors measured on the central axis. To reduce the number of adjustable variables in beam ...
The electronic structure and properties of the cubic Laves phase (C15) compounds ZrZn_2 and ZrV_2 have been determined using our all-electron full-potential linearized-augmented-plane-wave (FLAPW) method for bulk solids. The computations were performed in two stages: (i) self-consistent warped muffin tin and (ii) self-consistent full potential. Spin-orbit coupling was included after either stage. The effects of the inclusion of the nonspherical terms inside the muffin tins on the eigenvalues is found to be small (of order 1 mRy). However, due to the fact that some of the bands near the Fermi level are flat, this effect leads to a much higher value of the density of states at E/sub F/ in ZnZr_2. The most important difference between the materials ZrZn_2 and ZrV_2 is the position of the d bands derived from the Zr and V atoms. Consequently, these materials have completely different Fermi surfaces. We have investigated the magnetic properties of ...
The electronic structure and properties of the cubic Laves phase (C15) compounds ZrZn/sub 2/ and ZrV/sub 2/ have been determined using our all-electron full-potential linearized-augmented-plane-wave (FLAPW) method for bulk solids. The computations were performed in two stages: (i) self-consistent warped muffin tin and (ii) self-consistent full potential. Spin-orbit coupling was included after either stage. The effects of the inclusion of the nonspherical terms inside the muffin tins on the eigenvalues is found to be small (of order 1 mRy). However, due to the fact that some of the bands near the Fermi level are flat, this effect leads to a much higher value of the density of states at E/sub F/ in ZnZr/sub 2/. The most important difference between the materials ZrZn/sub 2/ and ZrV/sub 2/ is the position of the d bands derived from the Zr and V atoms. Consequently, these materials have completely different Fermi surfaces. We have investigated the ...
The relationship between the current density distribution and the electron density profile during the flat-top phase of Ohmic discharges in TEXTOR has been investigated by means of far-infrared interferometry and polarimetry. It is found that neither gradual nor rapid changes of the electron density distribution (induced by continuous gas feed or pellet injection) alter the current profile significantly. The conclusion is drawn from the temporal evolution of the measured Faraday rotation signals #alpha#_e_x_p(x,t) which are proportional to the line integrals of n_c times the poloidal magnetic field component B_p_c along the probing beam paths (x is the distance of a chord from the plasma centre). By taking into account the known variation of the density profile but keeping the current distribution fixed, theoretical signals #alpha#_s_i_m(x,t) can be calculated which match the observed waveforms very well without any need to readjust the ...
Corona discharge has been investigated for the treatment of off-gases arising from nuclear fuel reprocessing operations, in particular Dissolver off-Gases (DOG). Results are presented of studies carried out on single tube, wire-in-tube experimental rigs to examine the behaviour of molecular iodine, organic iodine and oxides of nitrogen (NOx). The effect of corona current, gas residence time, electrode configuration, oxygen concentration and moisture content are discussed. Decontamination Factors (DF's) of greater than 104 (> 99.99% removal) have been achieved for both molecular and organic iodine. Efficient NOx removal has also been demonstrated. Moisture and NOx both interfere with iodine removal above certain concentrations. To overcome this a two stage corona system has been developed consisting of a primary continuously irrigated corona unit followed by a dehumidifier prior to a secondary dry corona unit.
A shock wave appears when the release of accumulated energy is instantaneous. For instance, it accompanies gunpowder explosion, electric discharge, laser beam convergence, collision of high-speed objects, release of high-pressure gas, and supersonic flight. The shock wave research center of Institute of Fluid Science, Tohoku University, is engaged in researches to elucidate the basics of various shock wave phenomena and to apply the fruit to engineering, science, and medicine. In this report, some examples of recent application studies at the center are described, and the trend of shock wave researches in the future is introduced. The ultimate state of the stagnation point of a nozzle flow simulating a reentry into the atmosphere is produced by shock wave compression in a free piston shock tube which is a ground-borne experimental apparatus. Los Alamos National Laboratory, U.S., succeeded in generating metallic hydrogen of a crystalline ...
Study was made on the city bus driven by the series hybrid system composed of a small ceramic gas turbine (100kW), generator and lead storage battery. Two driving modes were adopted, 10-driving mode and real driving mode assuming a certain bus route in Tokyo. The motor is driven mainly by generated power and additionally by battery power, however, the engine/generator system is controlled at an optimum operation point (driving mode and regenerating mode) with a maximum thermal efficiency considering depth of discharge. Design voltage of the battery had nearly no effect on fuel consumption, while its capacity as large as possible was desirable unless its weight has an adverse effect on the system. The real driving mode was lower in fuel consumption by 39% than the 10-driving mode. Since real fuel consumption is largely affected by recovery rate of regenerable energy, the operation point of the motor should be optimized according to driving mode. ...
In a PWR type reactor, a primary coolant circuit system using a steam generator is adopted in order to accelerate depressurization of a primary coolant circuit upon small rupture LOCA in which the pressure of the primary coolant circuit is moderately depressurized. A secondary coolant circuit depressurization valve is disposed to a main steam pipeline. The valve has a performance of automatically opening to remove heat by evaporation of water stored in SG for a short period of time when the pressure in the primary circuit is decreased to about 50kg/cm[sup 2] upon occurrence of LOCA or the like. Then, the secondary side of the SG is depressurized to about atmospheric pressure and gravitational water injection from a condensate tank is started. Further, a gas vent valve is disposed to a water chamber of the steam generator. The valve has a performance of automatically opening to discharge incondensible gas mixed to the ...
The US Environmental Protection Agency (EPA) conducted a cost-effectiveness (CE) analysis to estimate the incremental cost of complying with the proposed effluent limitation guidelines (ELGs) for the coastal oil and gas industry (EPA 1995a). EPA`s CE analysis calculates the pounds of each pollutant that would be removed if the chosen discharge option is selected. In 1993, EPA issued final ELGs for the offshore oil and gas industry and published an offshore CE analysis. The chemical characteristics of produced water from the offshore region are essentially the same as those of produced water from the coastal region. It was surprising, therefore, that EPA chose a much longer list of pollutants and generally stricter weighting factors for the coastal CE analysis. This report reviews the data, assumptions, and analyses used in EPA`s coastal CE analysis and identifies alternate data, assumptions, and analyses that could lead to ...
This study attempts to elucidate some of the effects of adding argon, neon and hydrogen to low pressure thermionically supported discharges used for plasma nitriding AISI M2 steel substrates. Four runs were performed at the same substrate temperature (550 C) and bias voltage (500 V), using the following gas mixtures: 8% N{sub 2} in Ar, 8% N{sub 2} in Ne, N{sub 2}+H{sub 2} in equal proportions, and N{sub 2} only. By careful control of the discharge parameters, most of the bombardment energy was transported to the substrates by 500 eV ions in all cases; these were mainly Ar{sup +} ions in the N{sub 2}+Ar run and N{sub 2}{sup +} ions in the other runs, notably by the action of Penning ionization in the N{sub 2}+Ne run. We found that the surface hardness was not significantly influenced by the type of ion delivering the bombardment energy, although we suggest that ions would need sufficient mass to cause (for example) ...
In many regions of the world, flooded mines are a potentially cost-effective option for heating and cooling using geothermal heat pump systems. For example, a single coal seam in Pennsylvania, West Virginia, and Ohio contains 5.1 x 1012 L of water. The growing volume of water discharging from this one coal seam totals 380,000 L/min, which could theoretically heat and cool 20,000 homes. Using the water stored in the mines would conservatively extend this option to an order of magnitude more sites. Based on current energy prices, geothermal heat pump systems using mine water could reduce annual costs for heating by 67% and cooling by 50% over conventional methods (natural gas or heating oil and standard air conditioning).
The growth of an oxide interfacial layer was recently found to increase the open-circuit voltage (OCV) and efficiency by up to 60 per cent in GaAs metal-semiconductor solar cells. Details of oxidation techniques to provide the necessary oxide thickness and chemical structure and using ozone, water-vapor-saturated oxygen, or oxygen gasdischarges are described, as well as apparent crystallographic orientation effects. Preliminary results of the oxide chemistry obtained from X-ray, photoelectron spectroscopy are given. Ratios of arsenic oxide to gallium oxide of unity or less seem to be preferable. Samples with the highest OVC predominantly have As(+3) in the arsenic oxide rather than As(+5). A major difficulty at this time is a reduction in OCV by 100-200 mV when the antireflection coating is vacuum deposited.
Adding capacity to coal-fired plants in small increments of an overall integrated program may be the solution to the 10-year lead time required for the construction of a new plant. A preliminary study evaluates the technical and economic feasibility of a modular natural gas and coal-fired combined-cycle power plant which can be installed in three distinct phases. The plant sizes are suitable for large industrial and utility applications. The Modular Block Power Plant (MBPP) concept offers the advantages of phase construction, lower capital cost, lower cost electricity, lower air emissions, lower water requirements, and reduced solid waste discharge. Other advantages include part load availability, reduced coal inventory requirements, and easier plant siting. 11 figures, 4 tables.
In the present investigation, the properties of plasma nitrided AISI 304 steel were studied by changing the presence of nitrogen in the gas mixture. The plasma nitriding was performed at temperature -560 deg C, pressure -4 mbar and duration 24 hours. The nitrided samples were characterized by evaluating the phase composition, micro hardness, and diffusion layer thickness. The phase analysis indicates the mixed phases of CrN and Fe_3N, Fe_3N and Fe_4N which has the highest intensity. The results show the glow discharge plasma nitriding in presence of N_2 (80 vol. %) and H_2 (rest) produced higher hardness as well as higher case depth. (author)
New results for two types of nano-size silicon, prepared via thermal vapour deposition either with or without a graphite substrate are presented. Their superior reversible charge capacity and cycle life as negative electrode material for lithium-ion batteries have already been shown in previous work. Here the lithiation reaction of the materials is investigated more closely via different electrochemical in situ techniques: Raman spectroscopy, dilatometry and differential electrochemical mass spectrometry (DEMS). The Si/graphite compound material shows relatively high kinetics upon discharge. The moderate relative volume change and low gas evolution of the nano silicon based electrode, both being important points for a possible future use in real batteries, are discussed with respect to a standard graphite electrode. (author)
The thermal analysis of a turbine stack discharging exhaust gases to the atmosphere is presented. The examined turbine stack belongs to a gas lift plant for oil extraction located in the Gulf area. The analysis has been performed because an overheating of the anchor flange/bolts and of the concrete foundation occurred and caused small cracks in the upper layer of the foundation. A qualitative thermal analysis of the stack has pointed out that the main cause of the overheating was the thermal radiation in the air-filled region underneath the stack bottom plate. Detailed calculations performed by using a CFD code (Fluent ver. 6.0.12), cross-checked with measurements taken from site, have shown that a significant reduction of the heat flux to the foundation could be obtained by filling the above mentioned air region with an insulating material. The benefits of this solution are prevailing over those achievable with the installation of external ...
Soufriere Hills Volcano had two periods of repetitive Vulcanian activity in 1997. Each explosion discharged the contents of the upper 0.5-2km of the conduit as pyroclastic flows and fallout: frothy pumices from a deep, gas-rich zone, lava and breadcrust bombs from a degassed lava plug, and dense pumices from a transition zone. Vesicles constitute 1-66vol.% of breadcrust bombs and 24-79% of pumices, all those larger than a few tens of m being interconnected. Small vesicles (few hundreds of m) in pumices are interpreted as pre-dating explosion, implying pre-explosive conduit porosities up to 55%. About a sixth of large vesicles in pumices, and all those in breadcrust bombs, are angular voids formed by syn-explosive fracturing of amphibole phenocrysts. An intermediate-sized vesicle population...
Crankshafts of the pearlitic-sorbitic nodular cast iron type JUS NL.80 (similar to DIN GGG-80) heat treated to get a tensile strength of 820-900 GPa (i.e. a Vickers hardness of 268-295 HV) were plasma and ammonia gas nitrided. The glow discharge plasma nitriding was performed for 20 h at about 500degC in a gas mixture of 55% N{sub 2} and 45% H{sub 2}. The gas nitriding was performed for 28 h at 510degC in the ammonia gas. Evaluation of the nitrided surfaces was conducted by optical microscopy, X-ray diffractometry and microhardness measurements. Journal and crank pin dimensions and surface roughness were measured both before and after nitriding. Bending fatigue testing of crankshafts was performed using a fatigue testing rig. The fatigue limit was evaluated at 5.0x10{sup 6} cycles. The fractures happened at the transition radius of the journal with cracks starting beneath the ...
The purpose of this report is to determine if it is feasible to utilize the hot exhaust gasdischarged from gas turbines in direct applications. This report illustrates the technical feasibility and economic viability of using gas turbines in drying applications. The size of turbines in this investigation ranges from 2 MW to 10 MW. In addition, an implementation strategy has been developed to employ this new system. The method used to structure the scope of this undertaking is as follows: Step 1. Collecting information by contacting dryer manufacturer and companies drying different products. Information was also gathered by literature studies and the internet. Thomas register is a great tool when it comes to company and market searches. Step 2. Looking into if it is technically possible to use the exhaust gas directly into dryers. The parameters needed for these calculations were ...
This paper systematically introduces the supervision monitoring for radiation environment around the Guangdong Daya Bay and Ling Ao nuclear power station by the Guangdong Environmental Radiation Research and Monitoring Center. It includes the monitoring plan, methods, quality assurance, main results and conclusions. The results show that: (1) The gasdischarge have not caused any detectable impacts to the terrestrial and atmospheric environment since their operation; (2) "1"1"0"mAg could only be detected in seawater in the West Daya Bay in 1995 and 1997 and in sediments in 1997. The maximum annual average in seawater was 3.1 Bq/m"3, annual average of "1"1"0"mAg in sediments was 1.0 Bq/kg(dry). But it was always detectable in pearl oyster, gulfweed and cuttlefish in the West Daya Bay. The "1"1"0"mAg concentrations in halobios were relatively higher in 1994, 1996 and 1997. The maximum concentrations in pearl oyster, gulfweed and cuttlefish were ...
A zinc-air battery using zinc regeneration electrolysis with propanol oxidation as a counter electrode reaction is reported in this paper. It possesses functions of both zincate reduction and electrochemical preparation, showing the potential for increasing the electronic energy utilization. Charge/discharge tests and scanning electron microscopy (SEM) micrographs reveal that when a nickel sheet plated with the high-H{sub 2}-overpotential metal, cadmium, was used as the negative substrate electrode, the dendritic formation and hydrogen evolution are suppressed effectively, and granular zinc deposits become larger but relatively dense with the increase of charge time. The performance of batteries is favorable even if the charge time is as long as 5 h at the current density of 20 mA cm{sup -2}. Better discharge performance is achieved using a 'cavity-opening' configuration for the discharge cell rather than ...
In the next few decades, the probable strengthening of the greenhouse effect may bring about considerable changes in energy production and consumption, which depend on climate. It is presumed that some of the changes will occur even if the rise in greenhouse gas concentration will be reduced. Because the investments in energy production have a long-term influence, decision-makers should have an idea about the impact of the strengthening of the greenhouse effect on energy production and consumption in Finland. According to the results of this study, the effects of climate change on the total consumption and production of electricity will be limited. The structure of both electricity consumption and production will remain rather similar, the most important changes applying to hydro power. The consumption of heating electricity will decrease substantially. Because the non- climate-dependent sectors of electricity consumption (process industry and services) account for ...
The WEGA stellarator is used to confine low temperature, overdense (densities exceeding the cut-off density of the heating wave) plasmas by magnetic fields in the range of B=50-500 mT. Microwave heating systems are used to ignite gasdischarges using hydrogen, helium, neon or argon as working gases. The produced plasmas have been analyzed using Langmuir and emissive probes, a single-channel interferometer and ultra-high resolution Doppler spectroscopy. For a typical argon discharge in the low field operation, B=56 mT, the maximum electron density is n{sub e}{proportional_to}10{sup 18} m{sup -3} with temperatures in the range of T=4-12 eV. The plasma parameters are determined by using Langmuir probes and are cross-checked with interferometry. It is demonstrated within this work that the joint use of emissive probes and ultra-high resolution Doppler spectroscopy allows a precise measurement of the radial electric field. The ...
The study examined the possibility for fuel ignition by spark discharge caused by induction effects under high voltage transmission lines. Theoretical background information on capacitive spark discharges and fuel ignition processes is given. Laboratory experiments were conducted to test the dependence of fuel ignition on three parameters: impedance in discharge path, multiple discharges, and larger electrode shapes. The results of these tests are discussed in terms of fuel ignition possibilities under high voltage transmission lines.
A series of measurements of O_3 yield in nuclear induced O_2 and O_2-SF_6 discharges created by bombardment with energetic particles from the "1"0B(n,#alpha#)"7Li reaction are reported. Continuous irradiation at dose ratios of 10"1"5-10"1"7 eV.cm"-"3.s"-"1 and pulsed irradiation (approx.10 ms FWHM) at a peak dose rate of approx.10"2"0 eV.cm"-"3.s"-"1 were conducted. At the lower dose rates, SF_6 addition generally increased the ozone yield, which at the high dose rates, SF_6 addition decreased the observed ozone concentration. A numerical model was developed and applied to experimental conditions. The steady-state ozone concentration was found to be limited by the reaction O_3"- + O_3 #-># 2O_2 + O_2"-. A simplified analytical model of steady-state conditions was used to predict model sensitivity to various parameters. In addition to dose rate effects, pressure and temperature effect on ozone production were discussed. The present study was extended to noble ...
Products of a power plant flue gas desulfurization scrubber are discharged into a pond as sludge consisting of calcite (initial delta13C 3.2-3.8 per thousand), gypsum (initial delta34S 7.6-8.6 per thousand), and aqueous solution. Reducing conditions exist below a boundary that appears to move vertically as a function of changes in pond water level. Under reducing conditions, bacteria partially reduce aqueous sulfate to low-delta34S sulfide, consuming organic carbon and generating low-delta13C bicarbonate. Under oxidizing conditions, sulfide is converted to sulfate, leading to calcite dissolution, gypsum precipitation, and isotopic re-equilibration of remaining calcite with dissolved bicarbonate near the pond surface. The gypsum has delta34S near 6 per thousand, and calcite has delta13C as low as -1.7 per thousand; the changes from initial values correspond to predictions based on isotopic balance and reaction stoichiometry. The pond largely ...
The recent attempt to degassify a self contained liquid filled (SCLF) cable in Ontario Hydro is described. In September 1989, there was a high pressure alarm on one phase of a SCLF 115 kV cable circuit. The direct buried cable circuit is about 1,890 m long with two joints and was installed in 1968. Oil samples from the cable had 10 to 12% gas content with high levels of hydrogen, methane, and ethane, and very low levels of carbon monoxide, carbon dioxide, and acetylene. From these results it was concluded that the gas was generated by low energy electrical discharges and the paper insulation was not degraded. Various utilities and cable manufacturers were contacted to find if they had experienced similar problems. The cable duct oil was flushed and gasified and the successive oil samples were analyzed in order to locate the gassing site. The joints were examined and oil samples were taken through holes drilled in the cable ...
The 380 MW combined cycle gas turbine power station in Peterborough changed its water supply from town mains to high purity reverse osmosis permeate in October 2000. The high purity water is produced from secondary treated sewage effluent using advanced membrane technology. Alpheus Environmental and British Gas staff have recently completed a study of the power station's demineralization plant to identify the differences in operating costs associated with the change in feedwater. The results show that the ultrapure water produced after the change to a high purity feed is of improved quality and that the demineralization plant regeneration operating costs have been reduced by over 90%. The demineralization plant availability has increased from 78 to 98% enabling almost 20% more ultra pure water to be produced. The change in feedwater has also improved the local environment by significantly reducing the amount of waste chemicals ...
In order to investigate the effect of humidity on laminar burning velocity(S), the effect of humidity on the combustion reaction and radiation intensity was studied, taking account of dilution gases such as CO/sub 2/ and Ar which has the approximately identical characteristics to exhaust gas circulation(EGR) gas used to prevent NOx discharge from engines. According to the heat reaction theory, mean specific heat(C) of mixture, mean molecular weight(M) and adiabatic flame temperature(T) etc. were said to affect S but from experimental results, the effect of M and C could be ignored, compared with the effect of T. The relationship between S and H/sub 2/O, Ar of CO/sub 2/% in mixture of diluted gases was clarified. The effect of H/sub 2/O on S was mainly caused by changes of T. The effect of radical C/sub 2/, CH and OH on radiation intensity was similar to that of H/sub 2/O and Ar and the effect of H/sub 2/O on combustion was ...
To develop oxygen electrodes for rechargeable metal-air batteries, the electrochemical behaviour of gas-diffusion-type carbon electrodes loaded with Pr-Mn-Fe-based perovskite-type oxides was examined for the reduction and evolution of oxygen in 8 M KOH at 60 C. Among the oxides tested, Pr{sub 0.2}Ca{sub 0.8}Mn{sub 0.1}Fe{sub 0.9}O{sub 3} gave the highest electrode performances, e.g., current densities of 275 mA/cm{sup 2} (for oxygen reduction) and 225 mA/cm{sup 2} (for oxygen evolution) at -300 and +650 mV vs. Hg/HgO, respectively. The electrode performances were found to depend on both the catalytic activity of the oxides for H{sub 2}O{sub 2} decomposition reaction and the amounts of oxygen desorbed from the oxides. Furthermore, it was confirmed that the small zinc-air battery including the gas-diffusion-type electrode loaded with Pr{sub 0.2}Ca{sub 0.8}Mn{sub 0.1}Fe{sub 0.9}O{sub 3} showed good discharge and charge ...
The objectives of this paper are to document the physicochemical and aquatic toxicological quality of a beneficial-use produced-water discharge and its effect on a receiving stream in Wyoming. Fish and water-flea survival, growth, and reproduction tests indicated that the discharge and all other sampling stations passed the state effluent biomonitoring acute toxicity testing endpoints. while benthic macroinvertebrates were absent at the discharge point designated by the Natl. Pollutant Discharge Elimination System (NPDES), productive and reproducing populations were present at all other downstream and mixing-zone stations. This investigation confirmed the validity of the beneficial-use subcategory for this oilfield discharge.
We present results from a kinetic Monte Carlo simulation of boron transient enhanced diffusion (TED) in silicon. Our approach avoids the use of phenomenological fits to experimental data by using a complete and self-consistent set of values for defect and dopant energetics derived mostly from {ital ab initio} calculations. The results predict that, during annealing of 40 keV B-implanted Si at 800{degree}C, there exists a time window during which all the implanted boron atoms are substitutional. At earlier or later times, the interactions between free silicon self-interstitials and boron atoms drive the growth of boron clusters and result in an inactive boron fraction. The results show that the majority of boron TED takes place during the growth period of interstitial clusters and not during their dissolution. {copyright} {ital 1998 American Institute of Physics.}
We present results from a kinetic Monte Carlo simulation of boron transient enhanced diffusion (TED) in silicon. Our approach avoids the use of phenomenological fits to experimental data by using a complete and self-consistent set of values for defect and dopant energetics derived mostly from ab initio calculations. The results predict that, during annealing of 40 keV B-implanted Si at 800 degree C, there exists a time window during which all the implanted boron atoms are substitutional. At earlier or later times, the interactions between free silicon self-interstitials and boron atoms drive the growth of boron clusters and result in an inactive boron fraction. The results show that the majority of boron TED takes place during the growth period of interstitial clusters and not during their dissolution. copyright 1998 American Institute of Physics.
The texture influence on tensile tests of AZ31, one of the common Mg alloys, has been studied. Starting material was a rectangular extruded bar, which has a strong texture. Due to the preparation of three tensile samples with 0 , 45 , 90 to the extrusion direction, the initial bar texture influences differently on the mechanical behaviour under tensile load. This results in a variation of the yield strength (90 MPa and 175 MPa) the ultimate tensile strength (250 MPa - 278 MPa) and the final texture. Experimental texture analysis was completed by texture simulations using the VPSC-model (visco plastic self-consistent). The good agreement between experimental and simulated pole figures allows the determination of the activated deformation modes related to the initial texture. (orig.)
We estimate the TeV {gamma}-ray fluxes expected from the population of young pulsars in terms of the self-consistent time-dependent hadronic-leptonic model for the high-energy processes inside the pulsar wind nebulae (PWNe). This radiation model is based on the hypothesis of Arons and collaborators who postulate that leptons are accelerated inside the nebulae as a result of resonant scattering on heavy nuclei, which in turn are accelerated in the pulsar wind region or the pulsar inner magnetosphere. Our aim is to find out which PWNe on the northern hemisphere are the best candidates for detection at energies above 60 GeV and 200 GeV by the next generation of low-threshold Cherenkov telescopes.
The magnicon is a highly attractive candidate to be the RF source for a future multi-Tev linear collider. Physical models and computer codes have been developed which can provide start-to-end self-consistent simulations of a magnicon, including precise simulations of the high-convergence electron gun, RF-system, magnetic system, and beam collector. The 3-D beam dynamics simulations include realistic fields, finite beam size and transverse space charge effects. The codes allow one to provide steady-state simulations of the entire tube, so as to evaluate transient process of magnicon excitation, parasitic mode self-excitation, stability analysis, and tolerance analysis. The results of the simulations are found to be in good agreement with magnicon experiments. A brief description of the physical models and simulation codes employed will be given.
A model for the simulation of the time dependent behavior and the analysis of the equilibrium of the coupled system of storage ring and Free Electron Laser (FEL) is presented. The analysis comprises both amplifier and oscillator FEL. Bunch lengthening and energy widening due to wake forces are taken into account in a self-consistent way. The method is based on a mapping algorithm for means and correlations of the electron distribution function, pioneered by K. Hirata. The evolution of the laser field in the oscillator FEL is described by K. Hirata. The evolution of the laser field in the oscillator FEL is described by supermodes. The model is used to simulate an FEL in a small 500 MeV storage ring with 100 m circumference. Typical values for the output power, spatial, and spectral characteristics of the emitted radiation are presented.
We have studied the features of formation and the possible stationary structures of a self-consistent magnetic field in a relativistic collisionless plasma, which are characteristic of a simple geometry of the Weibel instability that is well known in the nonrelativistic case. The universal condition is established, the growth rate is determined, and the criteria of saturation of the Weibel instability are analyzed for a broad class of anisotropic particle distribution functions (for definiteness, in application to an electron-positron plasma). A nonlinear equation of the Grad-Shafranov type describing the potential current structures is derived and its solutions are analytically studied. Special attention is paid to spatially harmonic, nonlinear current configurations with parameters determined by the properties of the initial homogeneous plasma subject to the Weibel instability. It is demonstrated that the magnetic field energy density in the obtained solutions ...
We study the spike statistics of neurons in a network with dynamically balanced excitation and inhibition. Our model, intended to represent a generic cortical column, comprises randomly connected excitatory and inhibitory leaky integrate-and-fire neurons, driven by excitatory input from an external population. The high connectivity permits a mean field description in which synaptic currents can be treated as gaussian noise, the mean and autocorrelation function of which are calculated self-consistently from the firing statistics of single model neurons. Within this description, a wide range of Fano factors is possible. We find that the irregularity of spike trains is controlled mainly by the strength of the synapses relative to the difference between the firing threshold and the postfiring reset level of the membrane potential. For moderately strong synapses, we find spike statistics very similar to those observed in primary visual cortex.
This paper presents a method to evaluate and improve the performance of quantum dot infrared photodetectors (QDIPs). We proposed a device model for QDIPs. The developed model accounts for the self-consistent potential distribution, features of the electron capture and transport in realistic QDIPs in dark and illumination conditions. This model taking the effect of donor charges on the spatial distribution of the electric potential in the QDIP active region. The model is used for the calculation of the dark current, photocurrent and detectivity as a function of the structural parameters such as applied voltage, doping QD density, QD layers, and temperature. It explains strong sensitivity of dark current to the density of QDs and the doping level of the active region. In order to confirm our...
We present a unified self-consistent review of the approach to spherical harmonics developed in the second half of the 19th century by Maxwell and by Thomson and Tait. We remark how this spherical coordinate-free approach straightforwardly leads to physically very important results of the theory of solid and surface harmonics which become rather tedious to work out when using spherical coordinates and associated Legendre functions. These results include, among others, the addition theorem, spherical wave expansions, the construction of the standard set of normalized spherical harmonics, Y_lm - together with their rotational properties-, and recursion relations. We provide new proofs for Maxwell's theorem, the addition theorem and Hobson's theorem, respectively, using in the latter some elementary notions of the symbolic techniques proper of the theory of invariants. Also, we give an approach based on compact vector methods to express the elements of the rotation ...
Causal paradoxes arising in the tachyon theory have been systematically solved by using the reinterpretation principle as a consequence of which cause and effect no longer retain an absolute meaning. However, even in the tachyon theory, a cause is always seen to chronologically precede its effect, but this is obtained at the price of allowing cause and effect to be interchanged when required. A recent result has shown that this interchange-ability of cause and effect must not be unlimited if heavy paradoxes are to be avoided. This partial recovery of the classical concept of causality has been expressed by the conjecture that transcendent tachyons cannot be absorbed by a tachyon detector. In this paper the directional properties of the flow of information between two observers in relative motion and its consequences on the logical self-consistency of the theory of superluminal particles are analyzed. It is shown that the above conjecture does not provide a ...
Within the framework of the Bianchi type-IX homogeneous space, we set up a system of coupled equations for the cosmic scale factors, scalar field, and radiative energy density. At the tree level, the equations are written in a self-consistent, Hartree-Fock form. For phi/sup 4/ theory, the system of nine first-order differential equations is solved numerically for a varying ratio of the energy of anisotropy to the vacuum energy. As the vacuum energy increases, there appears to be less reheating, since the energy of anisotropy is more efficiently converted into isotropic expansion. If the energy of anisotropy is large enough, the inflationary phase is prevented. In this case, a series of cosmological phase transitions will take place each time the square of the effective mass changes its sign.
Within the framework of the Bianchi type-IX homogeneous space, we set up a system of coupled equations for the cosmic scale factors, scalar field, and radiative energy density. At the tree level, the equations are written in a self-consistent, Hartree-Fock form. For phi"4 theory, the system of nine first-order differential equations is solved numerically for a varying ratio of the energy of anisotropy to the vacuum energy. As the vacuum energy increases, there appears to be less reheating, since the energy of anisotropy is more efficiently converted into isotropic expansion. If the energy of anisotropy is large enough, the inflationary phase is prevented. In this case, a series of cosmological phase transitions will take place each time the square of the effective mass changes its sign.
The evolution of intergranular lattice strains in a textured, forged bar (Bar) sample of the #alpha# - #beta# titanium alloy Ti-6Al-4V has been characterised using in situ X-ray diffraction. A two-phase elastic-plastic self-consistent (EPSC) model has been developed to rationalise the results. Of the orientations analysed, it is found that the #left brace#2 0 0#right brace# #beta# orientation is the most compliant and that load partitions to this orientation during plasticity. The results from the bar material have then been used to predict the response of unidirectionally rolled plate (UD) Ti-6Al-4V. It is predicted that the residual lattice strains in the #left brace#101-bar0#right brace# and #left brace#112-bar0#right brace# orientations will be significantly higher in the UD material.
Electron charge distributions are presented for Nb_3Ge, Nb_3Al, and two other hypothetical A-15 structures. Results indicate that the bonding in these materials is mainly metallic in character with some covalentlike bonding between Nb-chain atoms. We find significant coupling between neighboring chains and also between chain atoms and atoms at the cubic site. Comparison is made with various theoretical models. Investigation of the charge character of states near E/sub F/ suggests further developments in current theories on the structural transformation of A-15 compounds. The effect of chain dimerization on electronic states and charge distribution of Nb_3Ge is also investigated.
Electron charge distributions are presented for Nb3Ge, Nb3Al, and two hypothetical A-15 structures. Results indicate that the bonding in these materials is mainly metallic in character with some covalentlike bonding between Nb-chain atoms. We find significant coupling between neighboring chains and also between chain atoms and atoms at the cubic site. Comparison is made with various theoretical models. Investigation of the charge character of states near EF suggests further developments in current theories on the structural transformation of A-15 compounds. The effect of chain dimerization on electronic states and charge distribution of Nb3Ge is also investigated.
Electron charge distributions are presented for Nb/sub 3/Ge, Nb/sub 3/Al, and two other hypothetical A-15 structures. Results indicate that the bonding in these materials is mainly metallic in character with some covalentlike bonding between Nb-chain atoms. We find significant coupling between neighboring chains and also between chain atoms and atoms at the cubic site. Comparison is made with various theoretical models. Investigation of the charge character of states near E/sub F/ suggests further developments in current theories on the structural transformation of A-15 compounds. The effect of chain dimerization on electronic states and charge distribution of Nb/sub 3/Ge is also investigated.
The electron-phonon spectral distribution function #alpha#"2(#omega#) F (#omega#) has been calculated for niobium. The electron energy bands and wave functions were obtained from a self-consistent augmented-plane-wave muffin-tin potential, and the electron-phonon matrix elements were evaluated using the so-called rigid-ion approximation. With this approximation it is found that #alpha#"2(#omega#) is constant over the whole energy spectrum. The electron-phonon mass enhancement has also been calculated for local regions of the Fermi surface and found to be anisotropic. The calculated local values of the enhancement do not agree with experimental values available for different orbits from de Haas--van Alphen measurements. The discrepancy seems to arise because the bare-rigid-ion matrix elements are relatively small between states with nearly pure l = 2 character.
From self-consistent band structure calculations using the 'augmented plane wave'(APW) method, the density of states can be decomposed into local partial (according to azimuthal quantum number l) components, the l-character densities. Within the APW formalism the intensity of X-ray emission spectra is determined by radial transition probabilities and l-character densities of such valence states, which reside inside the same atomic sphere as the core vacancy and whose quantum number l differs by +-1 from the one corresponding to the core state. By taking into account lifetime broadening of the core and valence states and also the instrumental broadening the computed spectra (non-metal K-, vanadium K- and Lsub(III)-spectra) agree well with experiment. (orig.).
Accurate full-potential self-consistent linearized augmented-plane-wave (FLAPW) calculations have been carried out for hexagonal boron nitride. The resulting energy-band structure indicates that this material is an indirect-gap insulator and shows the existence of two unoccupied interlayer bands, similar to those found in graphite and graphite intercalation compounds. Chemical bonding is mainly covalent, with a small charge transfer towards the nitrogen atoms. Moreover, model-potential calculations, based on first-principles FLAPW wave functions and potentials, have been used to study slabs of thickness up to 35 layers. Contrary to the case of graphite, our results do not provide evidence of surface states associated with the interlayer bands.
We have performed ab initio calculations on a wide range of small molecules, demonstrating the accuracy and flexibility of an alternative method for calculating the electronic structure of molecules, solids, and surfaces. It is based on the local-density approximation (LDA) for exchange and correlation and the nonlinear augmented-plane-wave method. Very accurate atomic forces are obtained directly. This allows for implementation of Car-Parrinello-like techniques to determine simultaneously the self-consistent electron wave functions and the equilibrium atomic positions within an iterative scheme. We find excellent agreement with the best existing LDA-based calculations and remarkable agreement with experiment for the equilibrium geometries, vibrational frequencies, and dipole moments of a wide variety of molecules, including strongly bound homopolar and polar molecules, hydrogen-bound and electron-deficient molecules, and weakly bound alkali and noble-metal dimers, ...
In 1991/1992, VEAG decided to convert its 500 MW plants at Jaenschwalde and Boxberg to the latest state of technology. This even included the discharge of the cleaned flue gas through the existing cooling towers. The site of the flue gas desulphurization plant and also the existing cooling tower shells required routeing of the clean gas lines similar to the routes in the existing plants of RWE. The positive experience accrued with the pipework material `glass-fibre reinforced vinyl ester resin` has also led to the selection of this material here. The universally positive experience gained from existing clean gas lines via cooling towers by very different power station operators induced VEAG and its partners also to equip new construction operations in the new Federal states with this technology. (orig.) [Deutsch] In den Jahren 1991/1992 entschloss sich die VEAG, ihre 500-MW-Anlagen ...
Treatment chemicals are used in all facets of the natural gas industry (NGI) from well development through transmission and storage of natural gas. The multitude of chemicals used, combined with the dozens of chemical manufacturers and/or suppliers has lead to the availability of hundreds of possible chemical products. Because of the widespread use of chemical products and their numerous sources, the NGI needs access to consistent data regarding their effectiveness and potential environmental impacts. The objective of this work was to evaluate the effectiveness and potential environmental impacts of, chemical products used in the NGI. This assessment was initially focused on biocides and corrosion inhibitors and their use in the gas production, storage and transmission facilities, The overall approach was obtain the necessary data on chemical use and effectiveness directly from the oil and gas industry, ...
discharges. Proposed Stormwater ELG from Construction Sites - EPA has proposed effluent limitations guidelines (ELGs) and new source performance standards (NSPS) to control...
We investigate a two-orbital Anderson lattice model with Ising orbital intersite exchange interactions on the basis of a dynamical mean field theory combined with the static mean field approximation of intersite orbital interactions. Focusing on Ce-based heavy-fermion compounds, we examine the orbital crossover between two orbital states, when the total f-electron number per site n_f is #approx#1. We show that a 'meta-orbital' transition, at which the occupancy of two orbitals changes steeply, occurs when the hybridization between the ground-state f-electron orbital and conduction electrons is smaller than that between the excited f-electron orbital and conduction electrons at low pressures. Near the meta-orbital critical end point, orbital fluctuations are enhanced and couple with charge fluctuations. A critical theory of meta-orbital fluctuations is also developed by applying the self-consistent renormalization theory of itinerant electron magnetism to orbital ...
Results of self-consistent local-spin-density-functional calculations are reported for the first time for the Ni(110) surface, represented by one-, three-, and five-layer slabs. Calculations for one- and five-layer slabs of Ni(100) are also reported. The behavior of the surface magnetization with varying slab thickness elucidates the nature and origin of the surface magnetic moment. We predict a 13% enhancement of the Ni(110) surface magnetic moment compared to the bulk value. For the Ni(100) surface, we find a smaller surface enhancement about 7%, compared to bulk, which agrees with the results of Jepsen et al. The enhancement of surface magnetic moments on Ni(100) and Ni(110) surfaces is attributed to s-d dehybridization at the surface and to the presence of electrostatic shifts required to maintain layer-by-layer charge neutrality. We find that the total d-electron charge is the same in each layer, which contradicts the sp-to-d charge transfer found by Tersoff ...
The isostructural #gamma#-#alpha# phase transition of Ce which occurs at 8 kbar has been studied by means of fully self-consistent (non-muffin-tin potential) linearized-augmented-plane-wave energy band calculations carried out for five different values of the lattice constant. In contradiction to the 4f electron promotional model of the transition, the results yield essentially one 4f electron to be occupied in each phase but with the 4f wave function somewhat less localized, and therefore more bandlike, in the ''collapsed'' #alpha# phase. A singly occupied 4f state is shown to be consistent with the available experimental data. These results strongly support the picture of a 4f localized bold-arrow-left-right itinerant transition at the #gamma#-#alpha# transition and conflict with the promotional model in which some fraction of 4f electrons are transferred to the sd conduction bands. The weaker bonding of the 4f electrons, compared to that of the 6s-5d valence ...
The technology for flue gas desulfurization (FGD) with seawater is widely adopted by coal-fired power plants in coastal areas. SO2 in the flue gas is absorbed by alkaline seawater and transfered in aqueous phase as sulfite (SO3(2-)), and most SO3(2-) is transformed to sulfate (SO4(2-)) after an aeration process. The remaining SO3(2-) in the seawater discharged to sea area may be harmful to marine organism because of its biological toxicity, thus it is necessary to determine the concentration of SO3(2-) in the seawater for desulfurization. In this study, the method of determination of SO3(2-) in the seawater by ion chromatography was investigated. The separation was achieved on an IonPac AS14A column with 14 mmol/L NaOH-12 mmol/L Na2 CO3 solution as the mobile phase at a flow rate of 1.2 mL/min, and the detection was performed by a pulsed amperometric detector. Formaldehyde was added as a protective agent when sampling ...
The Coal Fired Combined Cycle (CFCC) power system thermodynamic cycle is illustrated schematically. Pressurized air supplied at the discharge of gas turbine compressors is ducted to the pressure vessel of pressurized, fluidized-bed, combustor-steam generator modules. The air is introduced in parallel to the beds, entering through distribution grids beneath each bed. Steam generation tubes are buried within the beds and are also arranged as membrane tube walls enclosing the four sides. Crushed coal (1/4 inch x 0) is pneumatically fed at locations just above the air inlet grids at the bottom of each bed. Dolomite is similarly fed to the individual beds. The coal is burned at a temperature below the ash fusion point. Sulfur is removed in the fluid beds through reaction of the SO/sub 2/ with CaCO/sub 3/ and O/sub 2/ to form solid CaSO/sub 4/ and CO/sub 2/ gas. The combustion gases leave the beds at a temperature in the range of ...
Results are presented of experiments on partial discharge in liquid nitrogen, including insulation breakdown characteristics of liquid nitrogen, partial discharge characteristics of composite insulation systems, lifetime of polymer films, impulse breakdown of polymer films in liquid nitrogen, etc. The partial discharge characteristics of liquid nitrogen are examined with increasing liquid-nitrogen pressure. It is concluded that a composite insulation structure of polymer film and liquid nitrogen can be used as effective electrical insulators at cryogenic temperatures.
Results from scanning electron microscopy, Fourier transform infrared spectroscopy and the measurement of thermally stimulated current show that a high density of the physical defects and the chemical defects are introduced into the surface of the silicone rubber plates after they are treated by corona discharge plasma. These defects behave electrically as shallow electron traps, leading to the formation of a uniform discharge in air at higher pressure when the corona-modified silicone rubber is used in dielectric barrier discharge.
A line-to-plate reactor was set-up in the experimental study on the application of nanosecond pulsed corona discharge plasma technology in environmental pollution control. Investigation on the attenuation and distortion of the amplitude of the pulse wave front and the discharge image as well as the waveform along the corona wire was conducted. The results show that the wave front decreases sharply during the corona discharge along the corona wire. The higher the amplitude of the applied pulse is, the more the amplitude of the wave front decreased. The wave attenuation responds in a lower corona discharge inversely. To get a higher efficiency of the line-to-plate reactor a sharp attenuation of the corona has to be considered in practical design.
The isotopic enrichment of copper ions in a positive column Cu-Nu discharge using optogalvanic excitation is analyzed with a rate equation model With excitation at 510.6 nm, the fraction of the ions belonging to the 63-amu isotope of copper is enriched relative to the neutral abundance. Enrichment as large as 10% is calculated when the initial abundance of the neutral isotope is small (< or =0.1) and the discharge current density is large (> or =75 mA/cm/sup 2/). The degree of enrichment is examined as a function of the initial abundance, discharge current, the rate of charge exchange, and the diameter of the discharge tube.
Object: To limit the discharge amount of reactor water in a primary system at the time of scram to prevent excessive outflow of reactor water outside the system. Structure: A signal from an upper limit position indicator detects the fact that control rods are completely inserted when the reactor is urgently stopped and the detection signal causes a valve in an outflow line of the discharge water from a control rod driving mechanism to be closed to limit the amount of discharge flown into the scram discharge vessel, thus preventing outflow of reactor water in the primary system after the scram has been initiated. (Kamimura, M.).
Washboard (WB) modes (Smeulders P et al 1999 Plasma Phys. Control. Fusion 41 1303) are a very common edge instability regularly observed in the H-mode regime in JET. They are detected as (normally several) bands of continuously fluctuating magnetic activity rotating in the direction of the electron diamagnetic drift with typical frequencies in the range of 10-90 kHz. The time evolution of the WB mode frequency is found to follow qualitatively the evolution of the electron temperature measured near the pedestal top, probably due to the strong diamagnetic drift associated with the large pedestal gradients. Evidence for their involvement in the pedestal and ELM dynamics will be presented. Increasing WB mode amplitude is correlated with an increase in the time between consecutive type-I ELMs. In situations in which a sudden increase (decrease) of WB mode activity is observed, the build-up of the pedestal temperature (and, linked to this, also of the pedestal pressure) of the electrons is ...
In this work, amorphous hydrocarbon (a-C:H) film deposition on metallic mirrors was studied during working shots in tokamak T-10 and at exposure in Ar/CHD3/D2 dc magnetron discharge in a special laboratory high vacuum setup. Analysis of film composition (including hydrogen content) was carried out using nuclear physical methods. Thickness and optical parameters (refractive and extinction coefficients) of the films were estimated by ellipsometry. Laboratory films can be characterized as soft a-C:H films in comparison with hard tokamak films (? = 1.2 and 1.8 g/cm3, respectively). For the first one, a linear dependence of deposition rate on mirror temperature was observed in a wide temperature range. The addition of methane into initial Ar/D2 magnetron gas mixture leads to an increase of deposition rate. The data obtained should be taken into account to prevent hydrocarbon film formation on the surface of first mirrors in ITER.
A theoretical model is presented to describe the electromagnetic, heat transfer and fluid flow phenomena within a magnetron plasma torch and in the resultant plume, by using a commercial computational fluid dynamics (CFD) code FLUENT. Specific calculations are presented for a pure argon system (i.e., an argon plasma discharging into an argon environment), operated in a turbulent mode. An important finding of this work is that the external axial magnetic field (AMF) may have a significant effect on the behavior of arc plasma and thus affects the resulting plume. The AMF impels the plasma to retract axially and expand radially. As a result, the plasma intensity distribution on the cross section of torch seems to be more uniform. Numerical results also show that with AMF, the highest plasma temperature decreases and the anode arc root moves upstream significantly, while the current density distribution at the anode is more concentrated with a higher peak value. In ...
Electron and ion beam dynamics of the PF-1000 facility were investigated for the first time at its upper energy limit (?1 MJ) in relation to neutron emission, the pinch's plasma ('target') characteristics and some other parameters with the help of a number of diagnostics with ns temporal resolution. Special attention was paid to the temporal and the spatial cross correlations of different phenomena. Results of these experiments are in favour of a neutron emission model based on ion beam-plasma interaction with three important features: (1) the plasma target is hot and confined during a few 'inertial confinement times'; (2) the ions of the main part of the beam are magnetized and entrapped around the pinch plasma target for a period longer than the characteristic time of the plasma inductive storage system and (3) ion-ion collisions (both fusion collisions, due to head-on impacts and Coulomb collisions) are responsible for neutron emission. Analysis has shown that one of the ways for ...
Direct current (DC) glow discharge plasma nitriding was carried out on three selected surface-roughened AISI 304 stainless steel samples at 833 K under 4 mbar pressures for 24 h in the presence of N{sub 2}:H{sub 2} gas mixtures of 50 : 50 ratios. After plasma nitriding, the phase formation, case depth, surface roughness, and microhardness of a plasma-nitrided layer were evaluated by glancing angle x-ray diffractogram, optical microscope, stylus profilometer, and Vickers microhardness tester techniques. The case depth, surface hardness, and phase formation variations were observed with a variation in initial surface roughness. The diffraction patterns of the plasma-nitrided samples showed the modified intensities of the {alpha} and {gamma} phases along with those of the CrN, Fe{sub 4}N, and Fe{sub 3}N phases. Hardness and case depth variations were observed with a variation in surface roughness. A maximum hardness of 1058 Hv and a case depth of ...
A brief description of a method for producing relatively intense molecular negative ion beams for the difficult Group IIA elements is given which offers considerable improvement in terms of source operation and beam intensity stability over other methods conventionally utilized. It is particularly suited for use in cesium plasma sources such as the Aarhus geometry and axial geometry versions of the source. The method utilizes H/sub 2/ source feed gas for the production of a hydrogen-rich plasma discharge which sputters a negatively biased probe made of elemental or copper alloy material. Negative ion beams of MgH/sub 3//sup -/>=12 ..mu.. A have been realized during routine operation of the 25 MV tandem accelerator. Negative ion beam intensity data, typical source operational parameters, and examples of mass spectra associated with their production are given. Interesting intermetallic molecular negative ion beams consisting of the particular ...
Production of hydrogen sulfide in produced waters due to the activity of sulfate-reducing bacteria (SRB) is a potentially serious problem. The hydrogen sulfide is not only a safety and environmental concern, it also contributes to corrosion, solids formation, a reduction in produced oil and gas values, and limitations on water discharge. Waters produced from seawater-flooded reservoirs typically contain all of the nutrients required to support SRB metabolism. Surface processing facilities provide a favorable environment in which SRB flourish, converting water-borne nutrients into biomass and H{sub 2}S. This paper will present results from a field trial in which a new technology for the biochemical control of SRB metabolism was successfully applied. A slip stream of water downstream of separators on a produced water handling facility was routed through a bioreactor in a side-steam device where microbial growth was allowed to develop fully. This ...
Nitriding leads to improved tribological and corrosive properties of iron alloy components. In order to study the effect of plasma nitriding parameters on the structure of compound layer and diffusion zone, a systematic variation of process parameters, temperature and process gas atmosphere has been carried out. Metallographic inspection, X-ray diffraction and glow discharge optical spectroscopy analysis (GDOES) were used in this investigation. The results clarified that depending on the amount of nitrogen in the gas atmosphere nitrided layers with and without compound layer can be generated in the surface of M2 tool steel for temperatures from 350 C to 500 C. For plasma nitriding in 5 vol.% Nitrogen and 95 vol.% Hydrogen no compact compound layer was formed. The gas mixture of 76 vol.% Nitrogen resulted in compound layer formation for all temperatures from 350 C to 500 C. X-ray phase analysis indicated ...
The effect of ultrasound waves, airflow and combined ultrasound with the airflow on the thermal instability suppression of a hollow needle-to-plate electrical discharge was studied experimentally. To evaluate the thermal instability suppression we used the V-A characteristics of the discharge in stationary air, with ultrasound applied in stationary air, and finally when the airflow was supplied into the discharge through the needle without and with ultrasound application. To illustrate the effect of ultrasound, airflow and combined ultrasound with airflow on the discharge thermal instability suppression we also studied the discharge ozone production. We found that in stationary air the application of ultrasound only slightly suppresses thermal instability. A substantial increase of ozone generation was not detected. Application of the airflow through the needle suppressed ...
Ozone production in a negative corona discharge has been studied experimentally at atmospheric pressure in mixtures of N_2O+O_2 at ambient temperature. Ozone formation was found to be dramatically reduced with increase in the content of N_2O in the mixture. The reaction of O("1D) with nitrous oxide is the most likely process reducing the rate of ozone generation. A considerable decrease in the mean discharge current at a constant voltage was also observed with increasing content of nitrous oxide in the mixture and is attributed to the formation of anions in the discharge. The low values of the calculated mobility of negative charge carriers in the drift region of the discharge is caused by the formation of O"- #centre dot# (N_2O)_n and NO"-#centre dot#(N_2O)_n cluster anions in the drift region of the negative corona discharge.
In June 2003, we conducted a two-part field exercise to examine biogeochemical characteristics of water in the lower Mississippi river during the 4 days prior to discharge and in the Mississippi river plume over 2 days after discharge. Here we describe the fates of materials immediately after their discharge through Southwest Pass of the Mississippi delta into the northern Gulf of Mexico. Changes in surface water properties immediately after discharge were much larger and more rapid than changes prior to discharge. Total suspended matter (TSM) declined, probably due to sinking, dissolved macronutrients were rapidly diminished by mixing and biological uptake, and phytoplankton populations increased dramatically, and then declined. This decline appeared to begin at salinities of approximatel...
Electrochemical discharge machining (ECDM) is a promising hybrid process for high-performance machining of non-conductive glass. ECDM drilling has been found to have different characteristics and material removal mechanisms in discharge regime (less than 300??m in depth) and hydrodynamic regime (more than 300??m in depth); however, these regimes are never separately modeled in existing ECDM models, which leads to large prediction error, especially at low applied voltages and high machining depths. Until now, no model is particularly designed for discharge regime, where most material is removed. In this paper, a finite element based model for ECDM drilling in discharge regime is presented. Material removal subjected to a single spark was simulated using finite element method. The drilling d...
The ab initio pseudopotential method is used to study transient-enhanced-diffusion (TED) related processes. The electronic degrees of freedom are included explicitly, together with the fully self-consistent treatment of the electron charge density. A large supercell and a fine k-point mesh are used to ensure numerical convergence. Such method has been demonstrated to give quantitative description of defect energetic. We will show that boron diffusion is significantly enhanced in the presence of the Si interstitial due to the substantial lowering of the migrational barrier through a kick-out mechanism. The resulting mobile boron can also be trapped by another substitutional boron, forming an immobile and elect rically inactive two-boron pair. Similarly, carbon diffusion is also enhanced significantly due to the pairing with Si interstitial. However, carbon binds to Si interstitial much more strongly than boron does, taking away most Si interstitial from boron at ...
K"#pi#=20"- and 49/2"- yrast isomers have been discovered in "1"7"6Ta and "1"7"7Ta, with meanlives of 1.4 ms and 0.19 ms, respectively. The long meanlives arise from substantial K-hindrance in the "1"7"6Ta case but from spin-trapping in the "1"7"7Ta case. Quasiparticle calculations, which treat the Fermi and pairing energies self-consistently, reproduce the excitation energies of these isomers and the other multi-quasiparticle high-K states observed. Due to blocking, pairing is significantly reduced in the 3-quasiparticle states, the extent depending on the specific configurations. It is completely quenched for both protons and neutrons in the highest seniority states. Yrast traps of even higher spin are predicted to exist in "1"7"6Ta and "1"7"7Ta. ((orig.)).
The near-yrast states of "1"0"1_4_2Mo_5_9 and "1"0"3","4_4_4 Ru_5_9_,_6_0 have been studied following their population via heavy-ion multinucleon transfer reactions between a "1"3"6Xe beam and a thin, self-supporting "1"0"0Mo target. The ground state sequence in "1"0"4Ru can be understood as demonstrating a simple evolution from a quasi-vibrational structure at lower spins to statically deformed, quasi-rotational excitation involving the population of a pair of low-#OMEGA# h_1_1_/_2 neutron orbitals. The effect of the decoupled h_1_1_/_2 orbital on this vibration-to-rotational evolution is demonstrated by an extension of the ''E-GOS'' prescription to include odd-A nuclei. The experimental results are also compared with self-consistent Total Routhian Surface calculations which also highlight the polarising role of the highly aligned neutron h_1_1_/_2 orbital in these nuclei. (author)
We calculated the energies of asymmetric nuclear matter at zero and finite temperatures with the cluster variational method. At zero temperature, the expectation value of the two-body Hamiltonian composed of the kinetic energies and the AV18 two-body forces is calculated with the Jastrow wave function in the two-body cluster approximation. The obtained two-body energy is in good agreement with the result with the Fermi Hypernetted Chain (FHNC) calculation by Akmal et al. The energy caused by the UIX three-body forces is treated somewhat phenomenologically so that the total energy reproduces the empirical saturation point. Furthermore, the parameters included in the three-body energy are readjusted so that the Thomas-Fermi (TF) calculations with use of the obtained energy of nuclear matter reproduce the gross feature of the experimental data on atomic nuclei. The nuclear species in the neutron star crust obtained by the TF calculation are reasonable. The free energies of asymmetric ...
(abridged) The accretion disk in AGN is expected to produce strong outflows, in particular a UV-line driven wind. Despite providing a good fit to the data, current spectral models of the X-ray spectrum of AGN observed through an accretion disk wind are ad-hoc in their treatment of the properties of the wind material. In order to address these limitations we adopt a numerical computation method that links a series of radiative transfer calculations, incorporating the effect of a global velocity field in a self-consistent manner (XSCORT). We present a series of example spectra from the XSCORT code that allow us to examine the shape of AGN X-ray spectra seen through a wind, for a range of velocity and density distributions, total column densities and initial ionization parameters. These detailed spectral models clearly show considerable complexity and structure that is strongly affected by all these factors. The presence of sharp features in the XSCORT spectra ...
Lyman-limit absorption systems can play many important roles during and after cosmological reionization. Unfortunately, due to the prohibitively large dynamic range required, it is impossible to self-consistently include these systems in cosmological simulations. Using fast and versatile semi-numeric simulations, we systematically explore the spatial distribution of absorption systems during and following reionization. We self-calibrate the resulting number of absorbers to the mean free path (mfp) of the ionizing ultraviolet background (UVB), and present results at a given mfp and neutral hydrogen fraction. We use a simple optical depth criterion to identify the locations of absorbers. Our approach is fairly robust to uncertainties such as missing subgrid structure. Unlike at lower redshifts where the UVB is relatively uniform, at higher redshifts the fluctuations in the UVB and the HII morphology of reionization can drive the large-scale distribution of absorption ...
The Sloan Digital Sky Survey (SDSS) started a new phase in August 2008, with new instrumentation and new surveys focused on Galactic structure and chemical evolution, measurements of the baryon oscillation feature in the clustering of galaxies and the quasar Ly{alpha} forest, and a radial velocity search for planets around {approx}8000 stars. This paper describes the first data release of SDSS-III (and the eighth counting from the beginning of the SDSS). The release includes 5-band imaging of roughly 5200 deg{sup 2} in the Southern Galactic Cap, bringing the total footprint of the SDSS imaging to 14,555 deg{sup 2}, or over a third of the Celestial Sphere. All the imaging data have been reprocessed with an improved sky-subtraction algorithm and a final, self-consistent recalibration and flat-field determination. This release also includes all data from the second phase of the Sloan Extension for Galactic Understanding and Evolution (SEGUE-2), consisting of ...
We improve the steady-state ab initio laser theory (SALT) of Tureci et al. by expressing its fundamental self-consistent equation in a basis set of threshold constant flux states that contains the exact threshold lasing mode. For cavities with non-uniform index and/or non-uniform gain, the new basis set allows the steady-state lasing properties to be computed with much greater efficiency. This formulation of the SALT can be solved in the single-pole approximation, which gives the intensities and thresholds, including the effects of nonlinear hole-burning interactions to all orders, with negligible computational effort. The approximation yields a number of analytic predictions, including a "gain-clamping" transition at which strong modal interactions suppress all higher modes. We show that the single-pole approximation agrees well with exact SALT calculations, particularly for high-Q cavities. Within this range of validity, it provides an extraordinarily efficient ...
In a relativistic density-functional theory the importance of the transverse photon contribution to the exchange potential in the high-density regime is pointed out. A neutral atom /sup 92/U is studied and its orbital energies calculated in the present scheme are compared with previous calculations based on relativistic Hartree, Dirac-Slater, and Dirac-Fock schemes and with experimental values from (electron spectroscopy for chemical analysis) ESCA studies. The present scheme is also used to calculate the orbital and total energies of some highly stripped ions of the Li isoelectronic sequence which occur as impurities in controlled thermonuclear plasma. These energies are found to be in close agreement with more involved Dirac-Fock results. Also, the relativistic effects significantly increase in going from C/sup 3 +/ to W/sup 71 +/ because the electronic density reaches values for which relativistic effects become large.
We report the results of a linearized augmented-plane-wave calculation of the electronic structure of fcc La at three lattice constants corresponding to ambient pressure, 50, and 120 kbars. The Kohn-Sham-Gaspar approximation for exchange and correlation is used and the potential is allowed a fully non-muffin-tin form. The f bands lie approx.2--2.5 eV above the Fermi level and are approx.1 eV wide, resulting in a very small (0.05 electrons) localized f occupation. Under pressure the f bands rise and broaden appreciably, resulting in only a slight increase in f occupation. The rigid-muffin-tin approximation for the electron-phonon interaction lambda overestimates the superconducting transition temperature T/sub c/ by 40%, but we find that the drastic increase in T/sub c/ under pressure can be attributed primarily to changes in the electronic stiffness eta. Structural transitions which occur at 25 and 53 kbars may be related to changes in Fermi-surface topology which we find to occur ...
Recent developments in solid-state radio frequency (RF) power technologies allow for the practical consideration of RF heated plasmas for space propulsion. These technologies permit the use of any electrical power source, de-couple the power and propellant sources, and allow for the effcient use of both the propellant mass and power. Effcient use of the propellant is obtained by expelling the rocket exhaust at the highest possible velocity, which can be orders of magnitude higher than those achieved in chemical rockets. Handling the hot plasma exhaust requires the use of magnetic nozzles, and the basic physics of ion detachment from the magnetic eld is discussed. The plasma can be generated by RF using helicon waves to heat electrons. Further direct heating of the ions helps to reduce the line radiation losses, and the magnetic geometry is tailored to allow ion cyclotron resonance heating. RF eld and ion trajectory calculations are presented to give a reasonably ...
A critical issues study of a symmetric illumination, direct drive laser fusion reactor called SIRIUS has been conducted. In particular, the uniformity requirements for direct drive targets have been assessed and it is shown that respectable gains (more than 60) could be obtained at modest (2MJ) KrF laser energies. Previous ICF cavity designs have been examined for use in a symmetric illumination geometry and features from several designs have been combined into a dry wall cavity design with a radius of 8 meters. Neutronic and photonic analysis shows that the present SIRIUS cavity design can breed sufficient tritium (breeding ratio = 1.17) even with 32 laser ports penetrating the cavity. However, it was found that there are a few critical issues that remain to be solved before a self-consistent reactor design could be initiated. Radiation damage to final optics, thermal performance of SiC tiles on the SIRIUS cavity wall, and performance of direct drive targets to ...
In vacuum arcs of interest for ion deposition, in which a magnetic filter is used, significant plasma rotation about the filter axis can develop. In the present work we present experimental evidence and simplified models to interpret relatively fast rotation of plasma generated in a pulsed vacuum arc with a straight magnetic filter and with a magnetic field strength in the range 52-430 G. The plasma rotation is produced in the first part of the filter (the driving region) where either the expanding or the contracting plasma encounters a mainly axial magnetic field. In the next part of the filter (the rotation region) a quasi-equilibrium is achieved and the plasma does not evolve further significantly. A rigid-rotor type of equilibrium is considered to model the rotation region, with experimentally obtained parameters, and a simple model is employed in the driving region to quantify the magnitude of the plasma rotation. It is found that at the quoted values of the magnetic field plasma ...
We are attempting to characterize and model the micromechanical response of highly-filled polymers. In this class of materials, the continuous plastic binder used to bond the highly-filled material dominates the observed viscoelastic response. As a result, realistic lifetime analysis of these materials will require a thorough understanding of the contribution of the plastic binder. Laboratory applications of these materials include plastic bonded explosives, propellants, a variety of specialized filled organic materials for stockpile systems, and highly filled epoxy dielectric materials for the National Ignition Facility. We have explored numerous techniques to characterize the local microstructure of plastic bonded explosives. However, insufficient funding was obtained to bring these technologies to maturity, nevertheless our present tool set is significantly better than 2 years ago. We have also made some progress in developing an appropriate micromechanical constitutive modeling ...
Local-density-functional calculations of the energy bands, equilibrium lattice constant, bulk modulus, and cohesive energy have been performed using a newly developed self-consistent full-potential linearized augmented-plane-wave (LAPW) program. Scalar-relativistic effects are included for the band states, and the core-level states are treated fully relativistically in a central-field approximation. Excellent agreement is obtained with the experimental lattice constant and bulk modulus. Generally good agreement is obtained with the scalar-relativistic pseudopotential results of Bylander and Kleinman. In this context, the impact of various approximations used in including the core states is assessed, and these findings are related to the frozen-core and pseudopotential approximations, especially with regard to the treatment of the somewhat overlapping 5p semicore states and their effect on ground-state properties. Comparison with the recent LAPW results of Jansen ...
We present new results from BRAVA, a large-scale radial velocity survey of the Galactic bulge, using M giant stars selected from the Two Micron All Sky Survey catalog as targets for the Cerro Tololo Inter-American Observatory 4 m Hydra multi-object spectrograph. The purpose of this survey is to construct a new generation of self-consistent bar models that conform to these observations. We report the dynamics for fields at the edge of the Galactic bulge at latitudes b = -8 deg. and compare to the dynamics at b = -4 deg. We find that the rotation curve V(r) is the same at b = -8 deg. as at b = -4 deg. That is, the Galactic boxy bulge rotates cylindrically, as do boxy bulges of other galaxies. The summed line-of-sight velocity distribution at b = -8 deg. is Gaussian, and the binned longitude-velocity plot shows no evidence for either a (disk) population with cold dynamics or for a (classical bulge) population with hot dynamics. The observed kinematics are well modeled ...
Isomers have been populated in "2"4"6Cm and "2"5"2No with quantum numbers K"#pi#=8"-, which decay through K"#pi#=2"- rotational bands built on octupole vibrational states. For N=150 isotones with (even) atomic number Z=94-102, the K"#pi#=8"- and 2"- states have remarkably stable energies, indicating neutron excitations. An exception is a singular minimum in the 2"- energy at Z=98, due to the additional role of proton configurations. The nearly constant energies, in isotones spanning an 18% increase in Coulomb energy near the Coulomb limit, provide a test for theory. The two-quasiparticle K"#pi#=8"- energies are described with single-particle energies given by the Woods-Saxon potential and the K"#pi#=2"- vibrational energies by quasiparticle random-phase approximation calculations. Ramifications for self-consistent mean-field theory are discussed.
Due to the increased computer power and advanced algorithms, quantum mechanical calculations based on Density Functional Theory are more and more widely used to solve real materials science problems. In this context large nonlinear generalized eigenvalue problems must be solved repeatedly to calculate the electronic ground state of a solid or molecule. Due to the nonlinear nature of this problem, an iterative solution of the eigenvalue problem can be more efficient provided it does not disturb the convergence of the self-consistent-field problem. The blocked Davidson method is one of the widely used and efficient schemes for that purpose, but its performance depends critically on the preconditioning, i.e. the procedure to improve the search space for an accurate solution. For more diagonally dominated problems, which appear typically for plane wave based pseudopotential calculations, the inverse of the diagonal of (H - ES) is used. However, for the more efficient ...
The growth of SrBi{sub 2}Ta{sub 2}O{sub 9} (SBT) films on top of Pt electrode substrates is an important issue for the fabrication of ferroelectric based memories. In a recent publication, SBT thin films grown using seeded and unseeded procedures were studied by PIXE and RBS. Difficulties and misfits found in the comparison of results from both techniques were, at that time, overcome by physical considerations. These, although not rendering interpretation impossible, left out the possibility of understanding the exact nature of the differences between the interface behavior in each case. In the present work it is shown that the reanalysis of the same data using the recently developed RBS-PIXE simultaneous and self-consistent calculation present in NDF leads to stronger conclusions on the solid state reaction occurring during the deposition stage for both types of samples. Allowing for the occurrence of solid state reactions between the deposited film and the Pt ...
The present work concerns the numeric modeling of the sea-wave instability under the effect of the logarithmic wind at hurricane conditions (ignoring non-linear effects, such as wave breaking, foam production, etc. Powell et al. (2003)^1, Shtemler et al. (2003)^2. The central point of the study is the calculation of the growth rate, which is proportional to the fractional input energy from the wind to the wave exponentially varied with time. The present modeling demonstrates that the Miles-type model applying Charnock's formula Charnock (1955)^3 for roughness to the hurricane -wind parameters underestimates the growth rate of the wind waves 5-40 times as compared with the model employing the roughness and friction velocity adopted from experimental data for hurricane winds.^1 This occurs due to Charnock's formula fails at large wind speeds. The stability characteristics obtained on the base of the hurricane-wind experimental parameters are self-consistent with the ...
The linearized-augmented-plane-wave (LAPW) method for thin films is generalized by removing the remaining shape approximation to the potential inside the atomic spheres. A new technique for solving Poisson's equation for a general charge density and potential is described and implemented in the film LAPW method. In the resulting full-potential LAPW method (FLAPW), all contributions to the potential are completely taken into account in the Hamiltonian matrix elements. The accuracy of the method: already well known for clean metal surfaces: is demonstrated for the case of a nearly free (noninteracting) O_2 molecule which is a severe test case of the method because of its large anisotropic charge distribution. Detailed comparisons show that the accuracy of the FLAPW results for O_2 exceeds that of existing state-of-the-art local-density linear-combination-of-atomic-orbitals (LCAO)-type calculations, and that taking the full potential LAPW results as a reference, the LCAO basis can be ...
Cu"2"+ ions are alternatively bridged by end-on and asymmetrical end-to-end (EE) azido groups in copper (II)-azido compound [#left brace#Cu(L)(N_3)_2#right brace#_n] (L=benzylamine). The electronic structure of its ferromagnetic ground state has been calculated using the self-consistent full-potential linearized augmented plane wave method based on the density functional theory. The spin populations have been found to be strongly positive on the Cu"2"+ ions, weakly positive on the terminal nitrogen atoms of the azido groups as well as on the nitrogen atoms of the benzylamine, and feeble on the central nitrogen atoms of the azido groups. Based on the spin distribution obtained from calculation, the ferromagnetic coupling through the azido groups has been analyzed as resulting from a spin delocalization from the Cu"2"+ ions toward the azido groups. But the result also indicates that the spin polarization effect may also take part in the magnetic coupling through the ...
The ion-velocity dependence of the ionization probability for an atom ejected from a surface is examined by using a quantum approach in which the coupled motion between electrons and the outgoing nucleus is followed along the whole trajectory by solving the stationary Schroedinger equation. We choose a very-small-cluster-model system in which the motion of the atom is restricted to one dimension, and with energy potential curves corresponding to the involved channels varying appreciably with the atom position. We found an exponential dependence on the inverse of the asymptotic ion velocity for high emission energies, and a smoother behavior with slight oscillations at low energies. These results are compared with those obtained within a dynamical-trajectory approximation using either a constant velocity equal to the asymptotic ionic value, or expressions for the velocity derived from the eikonal approximation and from the classical limit of the current vector. Both approaches give ...
We examine the observable properties of simulated barred galaxies including radial mass profiles, edge-on structure and kinematics, bar lengths and pattern speed evolution for detailed comparison to real systems. We have run several simulations in which bars are created through inherent instabilities in self-consistent simulations of a realistic disc+halo galaxy model with a disc-dominated, flat rotation curve. These simulations were run at high (N=20M particles) and low (N=500K) resolution to test numerical convergence. We determine the pattern speeds in simulations directly from the phase angle of the bar versus time and the Tremaine-Weinberg method. Fundamental dynamics do not change between the high and low resolution, suggesting that convergence has been reached in this case. We find the higher resolution is needed to simulate structural and kinematic properties accurately. The edge-on view of the higher-resolution system clearly shows the bending instability ...
The development of modern techniques for the cooling and the manipulation of atoms in recent years, and the possibility to create Bose-Einstein condensates and degenerate Fermi gases and to load them into regular optical lattices or disordered optical potentials, has evoked new interest for the disorder-induced localization of ultra-cold atoms. This work studies the transport properties of matter waves in disordered optical potentials, which are also known as speckle potentials. The effect of correlated disorder on localization is first studied numerically in the framework of the Anderson model. The relevant transport parameters in the configuration average over many different realizations of the speckle potential are then determined analytically, using self-consistent diagrammatic perturbation techniques. This allows to make predictions for a possible experimental observation of coherent transport phenomena for cold atoms in speckle potentials. Of particular ...
Present in over 45% of local spirals, boxy and peanut-shaped bulges are generally interpreted as edge-on bars and may represent a key phase in the evolution of bulges. Aiming to test such claims, the kinematic properties of self-consistent 3D N-body simulations of bar-unstable disks are studied. Using Gauss-Hermite polynomials to describe the stellar kinematics, a number of characteristic bar signatures are identified in edge-on disks: 1) a major-axis light profile with a quasi-exponential central peak and a plateau at moderate radii (Freeman Type II profile); 2) a ``double-hump'' rotation curve; 3) a sometime flat central velocity dispersion peak with a plateau at moderate radii and occasional local central minimum and secondary peak; 4) an h3-V correlation over the projected bar length. All those kinematic features are spatially correlated and can easily be understood from the orbital structure of barred disks. They thus provide a reliable and easy-to-use tool to ...
This work is based on the study of cesium ({sup 118,146}Cs) and francium ({sup 207-213}Fr,{sup 220-228}Fr) isotopes by hyperfine atomic spectroscopy and on the interpretation of these results from the nuclear physics point of view. The measured nuclear quantities are: the spin, the magnetic moment, the electric quadrupole moment and the mean square charge radius. The experimental method which is based on hyperfine optical pumping with a tunable laser, followed by magnetic analysis of the atoms is described in the first part. Results related to atomic physics are also presented. In the second part, these data are interpreted in the framework of nuclear models. The deformation of light cesium isomers are compared to values obtained from a theoretical self-consistent calculation. Heavy francium isotopes are situated in an area where the existence of static octupole deformations have been predicted. The odd-even staggering measured on the mean square radius is abnormal ...
We investigate the form factors of the chiral-odd nucleon matrix element of the tensor current. In particular, we aim at the anomalous tensor magnetic form factors of the nucleon within the framework of the SU(3) and SU(2) chiral quark-soliton model. We consider 1/N{sub c} rotational corrections and linear effects of SU(3) symmetry breaking with the symmetry-conserving quantization employed. We first obtain the results of the anomalous tensor magnetic moments for the up and down quarks: {kappa}{sub T}{sup u}=3.56 and {kappa}{sub T}{sup d}=1.83, respectively. The strange anomalous tensor magnetic moment is yielded to be {kappa}{sub T}{sup s}=0.2{approx}-0.2, that is compatible with zero. We also calculate the corresponding form factors {kappa}{sub T}{sup q}(Q{sup 2}) up to a momentum transfer Q{sup 2{<=}}1 GeV{sup 2} at a renormalization scale of 0.36 GeV{sup 2}.
The National Bureau of Standards' (NBS) CW racetrack microtron (RTM) will be utilized as a driver for a free electron laser (FEL) oscillator. The NBS RTM possesses many exceptional properties of value for the FEL: i) CW operation, ii) energy from 20-185 MeV, iii) small energy spread and emittance, iv) excellent energy stability, and v) high average power. The 1-D FEL gain formula predicts that the FEL would oscillate at the fundamental approximately from 0.25 #mu#m to 10 #mu#m when up-grading the peak current to #>=# 2 A. In this paper, the authors present 3-D self-consistent numerical results including several realistic effects, such as emittance, betatron oscillations, diffraction and refraction. The results indicate that the design value of the transverse emittance is small enough that it does not degrade the FEL performance for intermediate to long wavelengths, and only slightly degrades the performance at the shortest wavelength under consideration. Due to ...
We have developed a new method for calculating common envelope (CE) events based on explicit consideration of the donor star's structural response to adiabatic mass loss. In contrast to existing CE prescriptions, which specify a priori the donor's remnant mass, we determine this quantity self-consistently and find that it depends on binary and CE parameters. This aspect of our model is particularly important to realistic modeling for upper main-sequence star donors without strongly degenerate cores (and hence without a clear core/envelope boundary). We illustrate the central features of our method by considering CE events involving 10 M_s_u_n donors on or before their red giant branch. For such donors, the remnant core mass can be as much as 30% larger than the star's He-core mass. Applied across a population of such binaries, our methodology results in a significantly broader remnant mass and final orbital separation distribution and a 20% increase in CE survival ...
We present an analytical model for jets in Fanaroff & Riley Class I (FRI) radio galaxies, in which an initially laminar, relativistic flow is surrounded by a shear layer. We apply the appropriate conservation laws to constrain the jet parameters, starting the model where the radio emission is observed to brighten abruptly. We assume that the laminar flow fills the jet there and that pressure balance with the surroundings is maintained from that point outwards. Entrainment continuously injects new material into the jet and forms a shear layer, which contains material from both the environment and the laminar core. The shear layer expands rapidly with distance until finally the core disappears, and all of the material is mixed into the shear layer. Beyond this point, the shear layer expands in a cone and decelerates smoothly. We apply our model to the well-observed FRI source 3C31 and show that there is a self-consistent solution. We derive the jet power, ...
A model for coherent fluctuations of the nuclear density including all nucleons in the fluctuation movement is formulated. The wave function of the flucton satisfies a Schroedinger-type equation in which the role of potential energy is played by the energy of the nuclear matter for the A nucleons. The appearance of high-momentum components in the one-particle momentum distribution is related to the volume fluctuations of the density. These fluctuations are supposed to be of coherent nature, i.e. all nucleons are involved in the motion. An explicit expression for the momentum distribution of the nucleons in "1"2C and "1"8"1Ta nuclei is obtained and compared with the phenomenological momentum distribution as well as with the results given by the model of a non-relativistic harmonic oscillator and by the Dirac equation in the self-consistent model. The differential cross-section of 1 GeV proton scattering by the "2"8Si, "3"2S, "4"0Ca, "4"8Ca, "5"8Ni, "2"0"8Pb are ...
A 12-month program was conducted to advance the technology of the Electrical Discharge Machining (EDM) process to be applicable to the stringent requirements of gun barrel boring and rifling. The type of barrels employed in the test were .220 swift gun ba...
The report details the economic impact of two alternative regulatory options; a Treated Discharge Option and a Zero Discharge Option on facilities that would have to comply with the regulations as part of the reproposal of effluent limitations and standar...
The report analyzes the cost-effectiveness of two alternative regulatory options: A Treated Discharge Option and a Zero Discharge Option. The report compares the total annualized cost incurred for each of the two regulatory options to the corresponding ef...
Through the analysis of the relations between "3H monitoring results of sea water in West Daya Bay carried out by Guangdong Environmental Radiation Research and Monitoring Center (GERC) from 1994 to 2000 and the quantity of liquid "3H discharges made by Guangdong Nuclear Power Station (GNPS), the function has been found by fitting to describe the relation between "3H average concentrations (hereafter as to average concentration or concentration) for all sampling points at the same time and the quantity of liquid "3H discharges. "3H instantaneous concentrations or yearly average concentration in West Daya Bay can be estimated conveniently by using this function corresponding to either actual discharges or supposed discharges (the way for hydrodynamic calculation) from the GNPS's yearly "3H liquid discharge. The results have shown that the general influences both actual ...
The device is designed for automatic testing of the degree of discharge of tractive storage batteries (AB) for electric loaders, electric cars and electric ore locomotives. The basic electrical schematic of the device is cited.
We have performed self-consistent (SC) band structure calculations for the A15 compounds V_3X and Nb_3X, X = Al, Ga, Si, Ge, and Sn, using the augmented-plane-wave (APW) method. Relativistic effects (except the spin-orbit interaction) have been included in each SC cycle, along with corrections to the usual muffin-tin approximation. The latter apply the APW wave functions outside of the muffin-tin spheres to compute the interstitial charge densities and potentials. The resulting interstitial potential has full cubic symmetry (no spherical averaging), although a spherically averaged muffin-tin form is retained inside the spheres. The final SC potentials were used to generate energies and wave functions on a cubic mesh of 35 k points in 1/48th of the Brillouin zone. These results were interpolated onto a finer mesh of 969 k points using a symmetrized Fourier method; the densities of states (DOS), N (E), were determined using tetrahedral integration. These accurate ...
Transverse glow discharges in supersonic air and methane flows are studied both experimentally and theoretically. The experiments show that a diffuse volume discharge filling the whole cross section of the flow can easily be initiated in air, whereas a diffuse discharge in a methane flow shows a tendency to transition into a constricted mode. The electron transport coefficients (mobility and drift velocity) and the kinetic coefficients (such as collisional excitation rates of the vibrational levels of a methane molecule, as well as dissociation and ionization rates) are calculated by numerically solving the Boltzmann equation for the electron energy distribution function. The calculated coefficients are used to estimate the parameters of the plasma and the electric field in the positive co...
During spring and autumn, the total number of amoebae and the number of acanthamoeba species able to grow at 37 degrees C were determined in six thermally polluted factory discharges and the surrounding surface waters. The isolated Acanthamoeba strains were studied for growth in axenic medium, cytopathic effect in Vito cell cultures, and virulence in mice. Although more amoebae were isolated in autumn, the number of Acanthamoeba species was lower than in spring, when the percent of pathogenic strains among the isolates was highest. Higher concentrations of amoebae were found in warm discharges, and more virulent strains occurred in thermal discharges than in surface waters.
It is experimentally demonstrated that a relatively strong ion-rich sheath formed at a fixed negative bias of the grid can be changed to a rather weak ion sheath (sheath potential weakly retards electrons) only by increasing the discharge voltage in the system. At sufficiently high negative grid bias, an increase of discharge voltage enhances the ion collection current at the grid. An explanation is put forward in support of this experimental observation. A slight density enhancement with a fall in plasma electron temperature is also observed with the increasing negative grid bias. (authors)
For users and manufacturers affected by unwanted electrostatic discharges, the publication of standards concerning the control of such discharges is a great improvement and helps to prevent unwanted electrostatic discharges in potentially explosive atmospheres as well as around electrostatically sensitive devices. There are, for instance, handbook-like documents giving recommendations to help set up effective electrostatic suppressing measures and programs. Another group of standards focuses on certain products and processes and is, thus, more specific. A third group deals with test methods and specifications to help manufacturers develop products that are safe. It also helps in comparisons with other products and thus meets the customer's real needs. To assist manufacturers and customers ...
Results of researches on nitriding process of EJ961 steel are presented in this work. This steel was subjected to nitriding both on the cathode and on the isolated from cathode and anode substrate, that is at so called potential of glow discharged plasma. Nitriding processes were performed using device for glow discharge treatments with cooled anode. (author)
Craters were produced in the surface of a Pt-specimen by plasma discharge. Using a Focussed Ion Beam (FIB), TEM-foils of the cross section of the craters were prepared in order to examine the microstructural changes occurring as a result of the discharge impact. The molten material pushed to the edge of the craters was able to be identified. The grains beneath the craters reached the surface of the crater by a mechanism of epitaxial growth. (orig.)
The developed countries are implementing a policy minimizing damage from environmental pollution by reducing discharge in advance as well as the aftermath of a pollutant. The typical example is to use BAT (Best Available Technology). This is to prevent environmental damage by reducing the discharge of pollutants with available technology and to secure environmental margin to enable industrial activities of future generation. Therefore, the feasibility of introducing BAT requirement system was reviewed by considering foreign examples and Korean situation. 38 refs., 8 figs., 69 tabs.
A simple model is described to simulate kinetic processes in dielectric barrier discharges for O_2/NO_x mixtures. A threshold of ozone production found experimentally is confirmed by the calculations of this modeling, and the underlying chemical reaction mechanisms are discussed. It is also found that the effects of diffusion processes in the period of the lifetime of O atoms are not important to micro-discharge channels with a large radius, i.e. larger than 150 #mu#m
Using infra-red (IR) thermography, power loads onto the MKII Gas-Box divertor targets have been investigated in Type-I ELMy H-Mode plasmas at JET in medium current discharges (Ip = 2.6 MA and BT = 2.7 T). Heat fluxes are calculated from the measured divertor target tile surface temperatures taking into account the influence of co-deposited surface layers on tile surfaces. This is particularly important when estimating the energy deposition during transient events such as ELMs. Detailed energy balance analysis is used, both from IR and tile embedded thermocouples, to demonstrate an approximately constant ELM-averaged in/out divertor target asymmetry of ?0.55 and to show that the ELM in/out energy deposition ratio ranges from 1 : 1 to 2 : 1. The inter-ELM in/out ratio is close to the ELM-averaged value at low pedestal collisionalities and decreases down to values close to zero when the inner target plasma detaches at the highest pedestal ...
The opportunity of use self-maintained plasma-beam discharge in an extended pulsing plasma diode of low pressure for making powerful sources of the soft X-rays is investigated. Conditions of formation of the self-maintained plasma-beam discharge are determined. The mode of making of dense high-temperature plasma on the basis of stannum ions in the discharge is shown. The stannum ions are used as a working element of a radiation sources at pulsing power of electron beam P?10...100 MW. Results of the examination on formation of the dense (np?1016 cm3), small sizes (le?100 eV in conditions of working material evaporation from the anode are given. The total contribution of energy to the discharge has made W < 20 J.
The characteristics of diffuse glow discharges in pure argon and the Ar + 1%N2 mixture at pressures of 2?80 Torr were studied experimentally and numerically. The discharge operated in a molybdenumglass tube with an inner diameter of 2.8 cm and interelectrode distance of 75 cm. The current-voltage characteristic of the discharge and the populations of the N2(B3? g ) and N2(C3? u ) states were measured. It is shown that, at relatively low pressures (P 15 Torr), the current-voltage characteristic of a discharge in the mixture lies lower than that in pure argon. As the pressure increases, the effect of the reduction in the discha...
This engineering report compiles information on types and quantities of liquid waste discharged from B-Plant directly to cribs, ditches, reverse wells, etc., that are associated with B-Plant. Waste discharges to these cribs via overflow form 241-B, 241-BX, and 241-BY tank farms, and waste discharged to these cribs from sources other than B-Plant are discussed.Discharges from B-Plant to other cribs, unplanned releases, or waste remaining in tanks are not included in the report. Waste stream composition information is used to predict quantities of individual chemicals sent to cribs. This provides an accurate mass balance of waste streams from B-Plant to these cribs. These predictions are compared with known crib inventories as a verification of the process.
New non-stationary non-contracted form of the erosive radially-slotted discharge as a thin round sheet with the current of the azimuth direction have been discovered, its existence beings stipulated by a radial transport-wave fluxes. Characteristic features of this discharge is self-confinement of the discharge current magnitude, corresponding decrease of the current pulse duration and occurrence of an energy and substance ejection with rather unusual properties. Measurements of kinetics of the discharge current, the plasma radiation intensity and an electrical probe signal, as well as the transmission electron microscope investigations of characteristic aerodisperse aggregates arising the erosive phase, have been carried out. The probe signal duration was about 10 times greater than that of the current; its kinetics was complicated suggesting existence in the slot of two components with fundamentally ...
With appropriate circuit resistance and inductance and sufficient stored energy, discharging a charged human body or component through an exploding bridgewire (EBW) detonator may cause the detonator to function or may damage the detonator. We have studied the effects of electrostatic discharge (ESD) on a number of exploding bridgewire detonators which were subjected to discharges which passed directly through the bridgewires (pin-to-pin), as well as discharges which passed from the bridge to the metal case of the detonator (pin-to-case). We have performed calculations to determine the values of inductance and resistance for which burst and melt may occur for given ESD sources, using a phenomenological model of bridgewire burst in a computer code called FIRESET. Bridge melt was computed using the same computer code, but using experimental values of bridge resistivity and specific heat up to melt. 13 ...
Ocean thermal energy conversion (OTEC) plants discharge large volumes of cold water into the upper ocean. A three-dimensional, limited-area model was developed to investigate the regional influence of the far-field effluent plume created by the negatively buoyant discharge. The model was applied to discharges from a 40-MW/sub e/ OTEC plant into coastal waters characterized by various ambient ocean conditions. A typical ambient temperature structure and nutrient distribution, as well as the behavior of the effluent plume itself, were strongly modified by the discharge-induced circulation. Although temperature perturbations in the plume were small, upward entrainment of nutrients from below the thermocline was significant. The regional influence of discharges from an 80-MW/sub e/ OTEC plant, the interactions between the discharges from two adjacent 40-MW/sub e/ ...
Electron trapping in crossed electric and magnetic fields is an important mechanism by which electrical discharges can develop in low pressure gases. The authors report observations of discharges produced by this mechanism around a spherical anode in two space simulation chambers, namely the Space Plasma Interaction Experiment (SPIE) at the University of Maryland, and the NASA-Lewis B-2 chamber. They have identified two types of discharges in these experiments. In the B-2 chamber, the breakdown takes the form of a runaway dischage with spherical topology, limited only by the ability of the power supply to provide the current. In the SPIE chamber this type of discharge also occurs, in addition to a low current toroidal discharge which is observed at higher magnetic fields. They present measurements of both types of discharge and show how the trapping effect of ...
We have studied the efficiency of ozone production by pulsed positive corona discharge in coaxial wire-cylinder geometry at atmospheric pressure. A corona discharge was generated by short (#approx#150 ns) high voltage pulses applied between a silver coated copper wire anode and stainless steel cylinder cathode in synthetic air. A pyrex probe and Teflon tube was used for collecting discharge products and an ozone concentration was monitored outside of the discharge chamber by a non-dispersive UV absorption technique. The production of ozone was investigated as a function of energy density (10"-"4-3x10"-"1 Wh l"-"1) delivered to the discharge volume by combining the discharge frequency (0.1-10 Hz) and airflow rate (1-32 l min"-"1). From ozone concentration measurements we have evaluated the ozone production, yield and production energy cost. The ozone production ...
Polymers are required to use in radiation environments as insulation materials. However, they often suffer from tracking failure. There is an increasing demand to evaluate radiation effects on dielectric performance. This paper presents a recurrence plot (RP) approach to analyse surface discharge sequences of gamma-ray irradiated polymer materials based on tracking test. Studying the non-linear characteristics of discharge sequences can assist in understanding the underlying mechanism of the discharge process. Discharge sequences of the test are extended to m-dimensional phase space by using the phase space reconstructed method. As test samples, polybutylene terephthalate (PBT) and polybutylene naphthalate (PBN) were irradiated to 100 kGy and then up to 1 MGy with a dosage rate of 10 kGy h{sup -1} by using a {sup 60}Co gamma source. The tracking tests were carried out according to the test method ...
The invention relates to a method for purifying a gas mixture containing at least one undesirable gas compound utilizing certain sulfonamide or sulfamide solvents.
The gel electrolyte for the zinc-air cell was prepared by mixing hydroponics gel with a 6M potassium hydroxide aqueous solution. The self-discharge of cells was characterized by measuring the open-circuit voltage. The effect of a discharge rate of 50mA constant current on cell voltage and plateau hour, as well as the voltage-current and current density-power density were measured and analysed. The electrode degradation after discharge cycling was characterized by structural and surface methods. The oxidation of the electrode surface further blocked the utilization of the Zn anode and was identified as a cause for the failure of the cell. (author)
Oxidation of propylene with oxygen, air and a mixture of nitrogen?oxygen in a barrier discharge is investigated. The selectivity towards formation of propylene oxide in pure oxygen is shown to be as high as 45 wt% and the propylene conversion ratio is found to be 12.9 wt%. In the oxidation with air, the propylene oxide selectivity is 23 wt%, while the conversion is 7.5 wt%. The values of propylene conversion and selectivity towards formation of propylene oxide in a barrier discharge are consistent with those obtained by the thermocatalytic methods for production of propylene oxide.
This patent describes an ignition system of an internal combustion engine which consists of: a permanent magnet supported by a rotary member of the engine adapted to rotate in synchronism with a rotary shaft of the engine; a generating coil for generating an electromotive force to produce an electric current as the permanent magnet acts on the generating coil during the rotation of the rotary member; an ignition capacitor charged by the electric current generated by the generating coil; a thyristor caused to turn on by a counter electromotive force generated by the generating coil to thereby cause the ignition capacitor to begin to discharge; and an ignition coil generating a high voltage as the ignition capacitor begins to discharge, to cause a spark discharge to take place in an ignition plug of the internal combustion engine.
Glow discharge plasma nitriding of AISI 304 austenitic stainless steel has been carried out for different processing time under optimum discharge conditions established by spectroscopic analysis. The treated samples were analysed by X-ray diffraction (XRD) to explore the changes induced in the crystallographic structure. The XRD pattern confirmed the formation of an expanded austenite phase (#gamma#_N) owing to incorporation of nitrogen as an interstitial solid solution in the iron lattice. A Vickers microhardness tester was used to evaluate the surface hardness as a function of indentation depth (#mu#m). The results showed clear evidence of surface changes with substantial increase in surface hardness.
In this work a flat receiver of self construction is shown with relatively low cost and easy manufacture, but with a thermal efficiency superior to 40% for applications at temperatures less than 60 degrees Celsius, that allows satisfying international standards in this respect. The heater has been matter of study in open courses distributed in the Universidad Autonoma de la Ciudad de Mexico (UACM) oriented to that the participants construct their own system, in addition to its installation and tests. The obtained results have been excellent. The massive use of efficient solar receivers of self-construction can truly help to the decreasing of the gasdischarges of greenhouse effect. [Spanish] En este trabajo se presenta un captador plano de auto construccion con relativamente bajo costo y facil manufactura, pero con un rendimiento termico superior a 40% para aplicaciones a temperatura menos de 60 grados centigrados que le permite satisfacer ...
Among the most promising technological alternatives for the development of photovoltaic modules and cells of a low cost, good energetic conversion and feasibility for mass production, polycrystalline silicon thin film solar cells deposited directly on a transparent substrate are currently being considered the best. We have developed in our laboratory a PECVD reactor capable of producing the deposition of amorphous hydrogenated silicon at rates of above 2 nm/seg, allowing a significant production per line on the plant. Dischargegas is silane, to which diborane or phosphine is added so as to form the cell. Basically, work is done on a structure of cell type TCO/n+/p-/p+/M, which has 2 {mu}m of total thickness. Schott AF-37 glass is used as a substrate, for their ability to withstand temperatures of up to 800 C. The amorphous cell is subsequently annealed at gradual temperatures of 100 C to achieve dehydrogenation up to 650-700 C for 12 h until ...
High quality single-walled carbon nanotubes (SWNT) have been synthesized at large scales by the method of direct evaporation of carbon black and metallic catalyst mixtures, using induction thermal plasma technology. The processing system consists mainly of an RF plasma torch, which generates a plasma jet of extremely high temperature (?15 000 K), with a high energy density and abundance of reactive species (ions and neutrals). With the present reactor system, it has been demonstrated that carbon soot product which contains approximately 40 wt% of SWNT can be continuously synthesized at the high production rate of ?100 g h-1. The processing parameters involved have been examined closely in order to evaluate their individual influences on SWNT synthesis. The results have shown that the quality and purity of the SWNT produced are critically affected by the grade of carbon black, the plasma gas composition and the metallic catalyst employed. Theoretical calculations, ...
The liquefaction reaction system of an NEDOL process coal liquefaction 1t/d PSU was opened and checked to investigate the cause of the rise of differential pressure between liquefaction reactors of the PSU. The liquefaction test at a coal concentration of 50 wt% using Tanito Harum coal was conducted, and it was found that the differential pressure between reactors was on the increase. By the two-phase flow pressure loss method, deposition thickness of deposit in pipelines was estimated at 4.4mm at the time of end operation, which agreed with a measuring value obtained from a {gamma} ray. The rise of differential pressure was caused by deposit formation in pipelines connecting reactors. The main component of the deposit is calcite (CaCO3 60-70%) and is the same as the usual one. It is also the same type as the deposit on the reactor wall. Ca in coal ash is concerned with this. To withdraw solid matters deposited in the reactor, there are installed pipelines for the withdrawal at the ...
In the design of natural gas compressor stations, a check valve is a critical element which is commonly placed on the discharge side of the compressor to prevent reverse flow that can cause serious damage to the compressor itself and other components such as seals and bearings. One of the selection criteria of the check valve for this particular application is the valve flow characteristics in steady flow, and its dynamic characteristics in unsteady flow operation. With regards to steady flow valve characteristics, current models for the determination of the check valve open angle vs. mean flow velocity are based on semi-empirical data obtained from water tests, which were found to deviate from measurements in compressible flows. This paper presents results of steady compressible flow testing of an NPS 4 swing type check valve in air. Mean flow velocities vs. disc angles were measured together with several local pressure measurements at the ...
Some magnetron sputtering systems experience rapid oscillations in the current and voltage of the plasma discharge after several hours when equipped with certain targets. These oscillations often lead to the plasma becoming extinguished, a condition known as ''flame-out.'' This article details the study of two 90% W--10% Ti magnetron targets which differed in density. The higher density targets sometimes experienced flame-out after approximately 3 h of sputtering. The less dense material could be sputtered for the entire 15 h life of the target. Scanning electron microscopy pictures and atomic composition depth profiles were obtained using Auger electron spectroscopy. In addition, a Colutron-based ion source with a high vacuum system was used to measure ion-induced secondary electron emission coefficients as a function of energy, ion specie, and gas coverage. Analysis of the sample from the group that suffers flame-out showed large regions of ...
In the design of natural gas compressor stations, a check valve is a critical element which is commonly placed on the discharge side of the compressor to prevent reverse flow that can cause serious damage to the compressor itself and other components such as seals and bearings. One of the selection criteria of the check valve for this particular application is the valve flow characteristics in steady flow, and its dynamic characteristics in unsteady flow operation. With regards to steady flow valve characteristics, current models for the determination of the check valve open angle versus mean flow velocity are based on semi-empirical data obtained from water tests, which were found to deviate from measurements involving fluids of relatively higher compressibility. This paper presents results of steady flow testing of an NPS 4 swing-type check valve in air. Mean flow velocities versus disk angles were measured together with several local ...
The potential for detoxification and deodorization of sulfide-laden water (sour water) by microbial treatment was evaluated at a petroleum production site under field conditions. A sulfide-tolerant strain of the chemautotroph and facultative anaerobe, Thiobacillus denitrificans, was introduced into an oil-skimming pit of the Amoco Production Company LACT 10 Unit of the Salt Creek Field, Wyoming. Field-produced water enters this pit from the oil/water separation treatment train at an average flowrate of 5,000 bbl/D (795 m{sup 3}/D) with a potential maximum of 98,000 bbl/D (15,580 m{sup 3}/D). Water conditions at the pit inlet are 4,800 mg/l TDS, 100 mg/l sulfide, pH 7.8, and 107{degrees}F. To this water an aqueous solution of ammonium nitrate and diphosphorous pentoxide was added to provide required nutrients for the bacteria. The first 20% of the pit was aerated to a maximum depth of 5 ft (1.5 m) to facilitate the aerobic oxidation of sulfide. No provisions for pH control or biomass ...
This report describes the preliminary thermalhydraulic analysis of HTR-10 steady state full power initial core to provide a benchmark calculation of VHTGR(Very High-Temperature Gas-Cooled Reactors) safety analysis code of GAMMA(GAs Multicomponent Mixture Analysis). The input data of GAMMA code are produced for the models of fluid block, wall block, radiation heat transfer and each component material properties in HTR-10 reactor. The temperature and flow distributions of HTR-10 steady state 10 MW{sub th} full power initial core are calculated by GAMMA code with boundary conditions of total reactor inlet flow rate of 4.32 kg/s, inlet temperature of 250 .deg. C, inlet pressure of 3 MPa, outlet pressure of 2.992 MPa and the fixed temperature at RCCS water cooling tube of 50 .deg C. The calculation results are compared with the measured solid material temperatures at 22 fixed instrumentation positions in HTR-10. The wall temperature distribution in ...
TOXCHEM is a microcomputer based modelling system for predicting the fate of toxic contaminants in wastewater treatment plants. The package evaluates concentrations of toxics in final effluent and waste sludge, and mass air emissions from municipal or industrial activated sludge wastewater treatment plants. Maximum allowable influent concentrations of toxics required to meet effluent discharge or air emission limits can also be estimated. The package contains a read-only database with treatability parameters for over 100 contaminants, including organic compounds and metals. If effluent or sludge quality limits have been specified, treatment plant owners and operators can use the package to estimate the permissable discharge limits for dischargers to their collection system. A hypothetical example is provided of application of the software to a planning problem involving the start up of a new operation that would ...
Objectives: To evaluate the training of pharmacists in Accra, Ghana, in the syndromic management of STIs. Methods: We randomly selected 50 pharmacy outlets that had...Full Text Available
Provisions (a) NPDES field personnel shall be currently trained and certified in CPR and basic first-aid procedures. (b) NPDES field personnel shall be aware of the...
... explosive (shotgun shells, etc.) method of forming is being replaced--for the most part--by the electri- cal discharge and magnetic forming methods. ...
At atmospheric pressure and room temperature, dielectric barrier discharge induced plasma oxidation for achieving supported TiO2 photocatalysts derived from TiCl4 adsorbed onto ?-Al2O3 pellets was studied. The supported TiO2/?-Al2O3photocatalysts prepared by a cyclic 'adsorption-discharge' approach, without requirement of heat treatment, exhibit high activity in the photocatalytic degradation reaction of formaldehyde. The mass spectra and optical emission spectra during O2/Ar discharge for oxidizing the adsorbed-state TiCl4 were measured. The mechanism for the TiO2 formation from adsorbed-state TiCl4 by plasma oxidation was discussed.
The ozone production process in a pulsed positive dielectric barrier discharge (DBD) is studied by measuring the spatial distribution of ozone density using a two-dimensional laser absorption method. DBD occurs in a 6 mm point-to-plane gap with a 1 mm-thick glass plate placed on the plane electrode. First, the propagation of DBD is observed using a short-gated ICCD camera. It is shown that DBD develops in three phases: primary streamer, secondary streamer and surface discharge phases. Next, the spatial distribution of ozone density is measured. It is shown that ozone is mostly produced in the secondary streamer and surface discharge, while only a small amount of ozone is produced in the primary streamer. The rate coefficient of the ozone production reaction, O + O_2 + M #-># O_3 + M, is estimated to be 2.5 x 10"-"3"4 cm"6 s"-"1.
By Charles E. Watkins. 2458. An Instrument Employing a Coronal Discharge for ..... Grover, W. S. Hyler, and L. R. Jackson. 2640. Interaction of Column and ...
This progress report consists of an article, the abstract of which follows, and apparently the references and vita from a proposal. A review of perturbation diagnostics applied to microwave resonant cavity discharges is presented. The classical microwave perturbation technique examines the shift in the resonant frequency and cavity quality factor of the resonant cavity caused by low electron density discharges. However, modifications presented here allow the analysis to be applied to discharges with electron densities beyond the limit predicted by perturbation theory. An {open_quote}exact{close_quote} perturbation analysis is presented which models the discharge as a separate dielectric, thereby removing the restrictions on electron density imposed by the classical technique. The {open_quote}exact{close_quote} method also uses measurements of the shifts in the resonant conditions of the cavity. Thirdly, ...
The tide field at the time of liquid effluent discharging from Daya Bay nuclear power station, and the average water speed at the monitoring points in west Daya Bay from the time of discharging to the time of sampling were calculated by ADI (Alternating Direction Implicit) method. By comparing analysis, the difference of "3H diffusion between spring tide and neap tide (the expansion of "3H within one day of spring tide is greater than that within one day of neap tide) was found. So, an equivalent diffusion time is introduced to modify the original model, and a better attenuation relation between the average "3He concentration in west Daya Bay and the time since the liquid "3H discharging is obtained. (authors)
Plasma Technologies in Institute of Plasma Physics of the NSC KIPT are recently developed in the following directions. Material surfaces modification under their irradiation with pulsed plasma streams of different working gases. Besides traditional analysis of improvements of tribological characteristics and structural-phase changes of the modified layers recently we started investigations of material corrosions characteristic improvement under influence of pulsed plasma on the material surfaces. As to the surface coatings in arc discharges of Bulat type devices, new trends are related with multi-layers coatings, using Ti-AI-N coatings in cutting tools, using high frequency discharges or combined HF- and arc discharges for increasing the nomenclature of goods to be coated. Development of ozonators is respectively new area for IPP NSC KIPT. On the base of barrier high-frequency discharge there were ...
The kinetic and guiding center fluid theories of high-..beta.. plasma containment in mirror machines have been developed in a number of self-consistent models. The geometrical effects of magnetic field and ambipolar potential variation have been incorporated in a bounce-averaged Fokker-Planck code which shows that the square-well model somewhat overestimates the n tau and ..beta.. achievable in a mirror field. Simple analytic approximations to the resulting pressure profiles have been incorporated in three-dimensional fluid-equilibrium codes which show the effect of coil geometry on the maximum ..beta... Strongly curved vacuum fields allow higher ..beta.., but short plasmas in weakly curved fields tend to reverse the curvature locally before the mirror-mode limit is reached. Adiabaticity of particle orbits is described in terms of general formulas, applicable in high-..beta.. plasma equilibria, and is shown to break down close to the mirror-mode limit. Two ...
The magnetic structure of the cubic compound CeAl{sub 2} is incommensurate and double-k. The moments on the two Ce sites describe two elliptical helices of opposed chiralities and lie in the (11-bar0) plane, with their Fourier components m{sup k} close to the [111] direction. Recent symmetry considerations, including for the first time the inversion center of the crystal, have reduced the number of parameters of this structure and have underlined the existence of a phase difference between the projections m{sub x}{sup k}, m{sub y}{sup k} and m{sub z}{sup k} of m{sup k}. Up to now, although many neutron investigations have been carried out on CeAl{sub 2} single crystals, no set of magnetic intensities was available which was large and good enough to check whether this phase difference exists or not. We have measured such a set of data, taking great care of the instrumental resolution in order to avoid unwanted contributions to the intensities from other domains. As the magnetic form ...
The magnetic structure of the cubic compound CeAl_2 is incommensurate and double-k. The moments on the two Ce sites describe two elliptical helices of opposed chiralities and lie in the (11-bar0) plane, with their Fourier components m"k close to the [111] direction. Recent symmetry considerations, including for the first time the inversion center of the crystal, have reduced the number of parameters of this structure and have underlined the existence of a phase difference between the projections m_x"k, m_y"k and m_z"k of m"k. Up to now, although many neutron investigations have been carried out on CeAl_2 single crystals, no set of magnetic intensities was available which was large and good enough to check whether this phase difference exists or not. We have measured such a set of data, taking great care of the instrumental resolution in order to avoid unwanted contributions to the intensities from other domains. As the magnetic form factor of the #GAMMA#_7 ground state of CeAl_2 ...
We report an analysis of four strains of baker's yeast (Saccharomyces cerevisiae) using biocavity laser spectroscopy. The four strains are grouped in two pairs (wild type and altered), in which one strain differs genetically at a single locus, affecting mitochondrial function. In one pair, the wild-type rho+ and a rho0 strain differ by complete removal of mitochondrial DNA (mtDNA). In the second pair, the wild-type rho+ and a rho- strain differ by knock-out of the nuclear gene encoding Cox4, an essential subunit of cytochrome c oxidase. The biocavity laser is used to measure the biophysical optic parameter Deltalambda, a laser wavelength shift relating to the optical density of cell or mitochondria that uniquely reflects its size and biomolecular composition. As such, Deltalambda is a powerful parameter that rapidly interrogates the biomolecular state of single cells and mitochondria. Wild-type cells and mitochondria produce Gaussian-like distributions with a single peak. In ...
I present an exact calculation of free-electron-laser (FEL) eigenmodes (fundamental as well as higher order modes) in the exponential-gain regime. These eigenmodes specify transverse profiles and exponential growth rates of the laser field, and they are self-consistent solutions of the coupled Maxwell-Vlasov equations describing the FEL interaction taking into account the effects due to energy spread, emittance and betatron oscillations of the electron beam, and diffraction and guiding of the laser field. The unperturbed electron distribution is assumed to be of Gaussian shape in four dimensional transverse phase space and in the energy variable, but uniform in longitudinal coordinate. The focusing of the electron beam is assumed to be matched to the natural wiggler focusing in both transverse planes. With these assumptions the eigenvalue problem can be reduced to a numerically manageable integral equation and solved exactly with a kernel iteration method. An ...
First-principles self-consistent band-structure calculations of potassium titanyl arsenate, KTiOAsO_4 (KTA), have been made using the full potential linearized augmented plane wave (FP-LAPW) method. Total and partial densities of states of the constituent atoms of KTA have been derived. The results obtained show that the valence band of KTA is dominated by contributions of the O 2p-like states, while the Ti 3d-like states are the main contributors into the conduction band of the compound. Additionally, the FP-LAPW calculations have revealed that potassium atoms are highly ionized in KTA. In the present work, the X-ray emission spectroscopy (XES) and X-ray photoelectron spectroscopy (XPS) methods were also employed to investigate experimentally the electronic structure of potassium titanyl arsenate. For the mentioned compound, the XES K Ll, Ti L#alpha#, As K#beta#_2 and O K#alpha# bands reflecting the valence K s-, Ti s,d-, As p- and O p-like states, respectively, ...
The total and state-specific electron-ion recombination rate coefficients are obtained for FeI. The calculations are carried out using a new ab initio method that incorporates both the radiative and the dielectronic recombination processes in an unified and self-consistent manner. The computations employ the close coupling approximation and the R-matrix method from atomic collision theory. A 52 state close coupling eigenfunction expansion dominated by the states of the ground 3d{sup 6}4s and excited 3d{sup 7}, 3d{sup 6}4p, 3d{sup 5}4s{sup 2}, and 3d{sup 5}4s4p configurations of FeII are used in the present calculations. The important electron correlation and radiation damping effects are included via explicit coupling of autoionization and radiative channels. This is the first detailed atomic calculation for the recombination rates for FeI. The present rates are considerably higher than the radiative recombination rates being used currently in the low-temperature ...
Motivated by the strong discrepancy between the main-sequence turnoff age and the white dwarf cooling age in the metal-rich open cluster NGC 6791, we compute a grid of white dwarf evolutionary sequences that incorporates for the first time the energy released by the processes of "2"2Ne sedimentation and of carbon/oxygen phase separation upon crystallization. The grid covers the mass range from 0.52 to 1.0 M _s_u_n, and is appropriate for the study of white dwarfs in metal-rich clusters. The evolutionary calculations are based on a detailed and self-consistent treatment of the energy released from these two processes, as well as on the employment of realistic carbon/oxygen profiles, of relevance for an accurate evaluation of the energy released by carbon/oxygen phase separation. We find that "2"2Ne sedimentation strongly delays the cooling rate of white dwarfs stemming from progenitors with high metallicities at moderate luminosities, while carbon/oxygen phase ...
The projector augmented-wave (PAW) method was developed by Bloechl as a method to accurately and efficiently calculate the electronic structure of materials within the framework of density-functional theory. It contains the numerical advantages of pseudopotential calculations while retaining the physics of all-electron calculations, including the correct nodal behavior of the valence-electron wave functions and the ability to include upper core states in addition to valence states in the self-consistent iterations. It uses many of the same ideas developed by Vanderbilt in his open-quotes soft pseudopotentialclose quotes formalism and in earlier work by Bloechl in his open-quotes generalized separable potentials,close quotes and has been successfully demonstrated for several interesting materials. We have developed a version of the PAW formalism for general use in structural and dynamical studies of materials. In the present paper, we investigate the accuracy of ...
Active galactic nuclei (AGNs) and quasars (QSOs) appear to emit roughly equal energy per decade from radio to gamma-ray energies (e.g. Ramaty and Ligenfelter 1982). This argues strongly for a nonthermal radiation mechanism (see Rees 1984). In addition, statistical studies have indicated that the spectra of these objects in the IR-UV and 2 to 50 keV x-ray band, can be fitted very well with power laws of specific indices. These spectral indices do not seem to depend on the luminosity or morphology of the objects (Rothschild et al. 1983; Malkan 1984), and any theory should account for them in a basic and model independent way. If shocks accelerate relativistic protons via the first-order Fermi mechanism (e.g. Axfor 1981), the radiating electrons can be produced as secondaries throughout the source by proton-proton (p-p) collisions and pion decay, thus eliminating Compton losses (Protheroe and Kazanas 1983). As shown by Kazanas (1984), if relativistic electrons are injected at high ...
A publication on Norwegian gas and gas export. The content is wide spread from use of gas in daily life via sub sea pipeline repair systems to an overview over tomorrows gas fields. (AG)
Electron Cyclotron Heating experiments have been performed on the TEXT tokamak using Varian gyrotron. Some degradation of electron energy confinement is observed for sawtoothing and non-sawtoothing discharges. Sharp electron temperature profiles are produced in high-q discharges by extremely localized ECH power deposition.
The effect of atmospheric radioactive emissions from United Kingdom nuclear installations on acid deposition is assessed. Nitrogen oxide and ozone production resulting from and associated with discharges of airborne radioactivity, comparison with conventional emissions, and the direct effects of radioactive emissions on trees, are all discussed. (UK).
The experimental superconducting magnetic system of 0.5 MJ energy storage is described. The step variation of the winding inductance provides a control by the discharge current at the energy output on a high-ohmic load. The voltage on a load is 45 kV at the current 1100 A under the controllable discharge conditions. The energy transfer coefficient constitutes 0,76 under the maximum-to-minimal current ratio equal to 1.3. 7 refs., 3 figs., 2 tabs.
Solutions have been found for the problems encountered with the coil power and switching systems of the International Fusion Superconducting Magnet Test Facility (IFSMTF). The coil power system provides the filtered dc sources (+- 12 V dc; 25,000 A) for charging and discharging the coils of the IFSMTF experiment. The switching system provides the means of transferring the coil current into a dump resistor when a rapid discharge of a coil is required due to a coil failure (quench) or other system abnormalities.
Abstract An analytical model is developed to predict transient discharge flow into a tunnel drilled at various speeds through a heterogeneous formation. This model relies on simplifying assumptions commonly enforced in hydrogeologic engineering, and combines the convolution and superposition principles to account for composite sections with arbitrary parametric contrasts. An application to the data monitored during the exploratory drilling of an Alpine tunnel confirms the validity of the approach.
In this study, Cu{sub 2}O/Cu composite particles were synthesized using an innovative chemical reduction method without any template and surfactant. X-ray diffraction (XRD) analysis revealed that the product mainly consisted of Cu{sub 2}O phase coexisting with a Cu phase. FE-SEM images showed that the octahedral shaped particles were Cu{sub 2}O. The electrochemical performance of the Cu{sub 2}O/Cu particles was investigated with regards to the working electrode material in alkaline solution. The particles had a maximum discharge capacity of 222.9 mAh/g at a discharge current density of 60 mA/g and a high value of 109.1 mAh/g after 50 charge-discharge cycles. Cyclic voltammetry revealed that the reaction between Cu{sub 2}O and Cu is the major electrochemical reaction during the charging and discharging process. Electrochemical impedance spectroscopy revealed that the formation of Cu{sub 2}O on the ...
Stream temperature is an important physical characteristic of headwater streams that plays a critical role in the presence and health of juvenile salmonids. Headwater stream temperature was documented in two geomorphic settings on the Kenai Peninsula, Alaska, focusing on the variation in temperature induced by diffuse groundwater discharge and variable air temperature. Eighteen headwater stream reaches were studied in four watersheds, with 11 drainageway sites and seven discharge-slope sites. In drainageway sites, low-gradient streams flow through broad valleys with groundwater-fed fen wetlands; in discharge-slope sites, high-gradient streams flow through narrow valleys with groundwater-fed slope wetlands. At all 18 sites, hourly stream temperatures were measured for one year. At one drainageway and one discharge-slope site, groundwater temperatures, stream stages, and groundwater heads in the local ...
A gas diffusion semiconductor electrode and solar cell and a process for gaseous fixation, such as nitrogen photoreduction, CO/sub 2/ photoreduction and fuel gas photo-oxidation are described. The gas diffusion photosensitive electrode has a central electrolyte porous matrix with an activated semiconductor material on one side adapted to be in contact with an electrolyte and a hydrophobic gas diffusion region on the opposite side adapted to be in contact with a supply of molecular gas.
An efficient method of hydrogen storage in nano-porous carbons is its reversible sorption by electrochemical decomposition of a KOH water solution according to the following equation: C + xH{sub 2}O + xe{sup -} {yields} (CH{sub x}) + xOH{sup -} where (CH{sub x}) stands for the hydrogen inserted into the nano-porous carbon during charging and oxidized during discharging. Although various carbon materials have been investigated as hydrogen adsorbents, the information about the storage mechanism as well as the nature of the hydrogen/carbon interaction is still not sufficient. In order to extend the understanding of the process, carbon samples charged electrochemically were investigated by temperature programmed desorption (TPD). The nature of the hydrogen/carbon interaction was studied by electrochemical analysis at different temperatures. The TPD experiments consist of heating the samples from room temperature to 950 C and of quantitative analysis by On-line mass ...
The book tries about the International and national aspects, natural gas situation, production, consumption, prices, demand projection, energetic plans, norms and laws of the natural gas in Colombia
This document provides information on the supply and disposition of natural gas to a wide audience. The 1996 data are presented in a sequence that follows natural gas from it`s production to it`s end use.
The origin of natural gas in the Japanese oil and gas fields are geochemically studied. Samples are taken from structural natural gas, surface gas seepage, water-dissolved natural gas and coal-field gas of the Japan Sea coast area. The origins of primary hydrocarbons are classified into bacteria gas and thermogenic gas, the latter being subclassified into gas in oil production zone with the per million deviation of the carbon isotope (/sup 13/C/sup 1/) of methane less than -35 and those gases with maturity higher than this. Surface gas seepage is subjected to migration and bacterial oxidation. Coal gas is similar to oil gas. The CO/sub 2/ concentration is 0 - 2% and /sup 13/CO/sub 2/ deviations from -30 - +30. The origin can be barely ...
The circulating cooling water flowrate of GNPS and LNPS is totally about 190 m"3/s. Both stations are located on the western coast of semi-closed Daya Bay. A lot of studies concerning thermal impact of GNPS and LNPS have been carried out since 1987, including mathematical model, physical model, on-site survey and satellite remote sensing, etc. This paper describes the hydrological features of Daya Bay and discharge characteristics of circulating water of GNPS and LNPS, estimates the actual thermal impact of GNPS and LNPS, and indicates that it is advantageous for the dilution of circulating water while the two discharge channels of GNPS and LNPS are combined together towards east
In this paper as a result of the theoretical studies and a numerical simulation we presented the following main conclusions: (i) for humid air at increasing pressure of 1.0133 10"5 Pa until 5.0665 10"5 Pa ozone concentrations during 2 centre dot 10"-"3 s become higher in 22 times. This fact we clear with structure of ozone-production reactions. In this case the harmful NO_x concentrations are 2-3 order lower than ozone one; (ii) it is shown that nitrogen is useful to ozone production in the discharge; (iii) based on ion collection we cleared increasing ignition discharge voltage at growing ozone concentrations even with low ozone concentrations.
A large database (507 station-years) of daily suspended particulate matter (SPM) concentration and discharge data from 36 stations on river basins ranging from 600?km2 to 600,000?km2 in size (USA and Europe) was collected to assess the effects of SPM transport regime on bias and imprecision of flux estimates when using infrequent surveys and the discharge-weighted mean concentration method. By extracting individual SPM concentrations and corresponding discharge values from the database, sampling frequencies from 12 to 200 per year were simulated using Monte Carlo techniques. The resulting estimates of yearly SPM fluxes were compared to reference fluxes derived from the complete database. For each station and given frequency, bias was measured by the median of relative errors between estima...
An attempt is made to induce in mud crab (Scylla serrata) epileptiform activities that resemble the generalized epileptic seizures. Cerebral ganglion of crab was exposed in situ, to a convulsant drug pentylenetetrazole (PTZ) 100?mM, for induction of seizures. Also, crabs were pretreated with antiepileptic drug viz sodium valproate (120??mol/l) to inhibit epileptiform activities. The surface electrical discharges of cerebral ganglion were recorded using Unkelscope (MIT, USA) in control as well as experimental animals. The cerebral ganglion of crab showed a pattern of high cerebral electrical discharges after PTZ treatment compared to control. The sodium valproate promoted sedative action in control and prevented PTZ-mediated epileptiform discharges. Glutamate and GABA contents in cerebral g...
Increase in power utility loads in industrialized countries, as well as developing countries, demands a higher level of transmission line voltage. Radio interference (RI) problems have been determined to be a limiting factor in selecting the size of transmission line conductors. Transmission line noise is primarily caused by corona discharges in the immediate vicinity of the conductor. It has been observed that discharges occur during both half-cycles of the applied voltage, but positive corona is usually predominant at AM radio frequencies range with practical high-voltage and extra high-voltage transmission lines. The corona radio noise effect is highly dependent upon the presence of particles on the surface of the conductor and the increase of the electrical gradient beyond the breakdown value of the air. Therefore, corona radio noise varies significantly with the weather and atmospheric conditions and generally increases by 10 to 30 dB in ...
Increase in power utility loads in industrialized countries, as well as developing countries, demands a higher level of transmission line voltage. Radio interference (RI) problems have been determined to be a limiting factor in selecting the size of transmission line conductors. Transmission line noise is primarily caused by corona discharges in the immediate vicinity of the conductor. It has been observed that discharges occur during both half-cycles of the applied voltage, but positive corona is usually predominant at AM radio frequencies range with practical high-voltage and extra high-voltage transmission lines. The corona radio noise effect is highly dependent upon the presence of particles on the surface of the conductor and the increase of the electrical gradient beyond the breakdown value of the air. Therefore, corona radio noise varies significantly with the weather and atmospheric conditions and generally increases by 10 to 30 dB in ...
Increase in power utility loads in industrialized countries, as well as developing countries, demands a higher level of transmission line voltage. Radio interference (RI) problems have been determined to be a limiting factor in selecting the size of transmission line conductors. Transmission line noise is primarily caused by corona discharges in the immediate vicinity of the conductor. It has been observed that discharges occur during both half-cycles of the applied voltage, but positive corona is usually predominant at AM radio frequencies range with practical high-voltage and extra high-voltage transmission lines. The corona radio noise effect is highly dependent upon the presence of particles on the surface of the conductor and the increase of the electrical gradient beyond the breakdown value of the air. Therefore, corona radio noise varies significantly with the weather and atmospheric conditions and generally increases by 10 to 30 dB in ...
The closed-cycle hydrogen-oxygen PEM regenerative fuel cell (RFC) at Nasa Glenn Research Center has successfully demonstrated closed-cycle operation at rated power for multiple charge/discharge cycles. During the charge cycle the RFC has absorbed input electrical power simulating a solar day cycle ranging from zero to 15 kWe peak, and delivered steady 5 kWe output power for periods exceeding 8 h. Orderly transitions from charge to discharge mode, and return to charging after full discharge, have been accomplished without incident. The RFC is beginning to demonstrate its potential as an energy storage device for aerospace solar power systems such as solar electric aircraft, lunar and planetary surface installations - any airless environment where minimum system weight is critical. This hard...
New methods have been established to enhance the ozone production of the surface discharge arrangement. One method sets the discharge electrode a short distance away from the surface of the dielectric material, whilst another uses a special power supply system resulting in a superimposed discharge. According to the experiments, significant differences have been found in the ozone production capacity of the different arrangements. The characteristics of the electric field distribution of the designs have been calculated using the finite element method for the potential; and the Donor-Cell method for the space charge calculation, and the results have been analysed. A method of analysis has been established for the calculated field characteristics, which provides two index numbers. The reasons are highlighted for the differences in ozone production in relation to the index numbers obtained from the fields' distributions of the ...
The development of a new configuration of chemical ionization (CI)-based ion source is presented. The ambient air containing the gaseous sample is sniffed into an enclosed ionization chamber which is of sub-ambient pressure, and is subsequently mixed with metastable species in front of the ion inlet of the mass spectrometer. Metastable helium atoms (He*) are used in this study as the primary ionizing agents and are generated from a dielectric barrier discharge (DBD) source. The DBD is powered by an AC high-voltage supply and the configuration of the electrodes is in such a way that the generated plasma is confined within the discharge tube and is not extended into the ionization chamber. The construction of the ion source is simple, and volatile compounds released from the bulky sample can...
Silicon thin film with thickness in range 1000-5300 A deposited on rough Cu foil by a radio frequency magnetron sputtering is used as anode materials for Li-ion rechargeable batteries. The SEM, XRD and TEM analysis reveals that the Si thin film has a floccular nano-sized multi-crystalline structure. Li ions insertion/extraction evaluation is performed mainly with constant current charge/discharge cycling and cyclic voltammetry (CV) at room temperature. The cycleability and reversible discharge capacity are found to depend on the film thickness, and thinner films give larger accommodation capacity. A 3120 A Si film provides a reversible specific capacity over 3500 mA hg{sup -1} with excellent cycleability under 0.5 C charge/discharge rate.
Many older homes are equipped with mercury-containing gas regulators that reduce the pressure of natural gas in the mains to the low pressure used in home gas piping. Removal of these regulators can...Full Text Available
In the context of safety assessment of radioactive waste repositories, complex radionuclide transport models covering key safety-relevant processes play a major role. In recent Swiss safety assessments, such as Kristallin-I, an important drawback was the limitation in geosphere modelling capability to account for geosphere heterogeneities. In marked contrast to this limitation in modelling capabilities, great effort has been put into investigating the heterogeneity of the geosphere as it impacts on hydrology. Structural geological methods have been used to look at the geometry of the flow paths on a small scale and the diffusion and sorption properties of different rock materials have been investigated. This huge amount of information could however be only partially applied in geosphere transport modelling. To make use of these investigations the 'PICNIC project' was established as a joint cooperation of PSI/Nagra and QuantiSci to provide a new geosphere transport ...
By placing a discharge or 'dump' tube across an exploding bridgewire load, it is possible to by-pass the electrical energy and terminate the explosion of the wire. The dump tube is triggered by a signal derived from the energy removed from the storage cap...
Graphene nanosheets (GNSs) were synthesized and used as cathode active materials in a nonaqueous lithium-oxygen battery. The GNSs electrode delivered an extremely high discharge capacity in comparison to carbon powders, which is attributed to its unique morphology and structure. PMID:21779551
This report presents by state the status of awarded grants, requested grants, and the estimated time required to achieve required control of combined sewer overflow pollution. It also compares discharges of pollutants from treated municipal effluent with ...
Sewage waste disposal facilities in the Florida Keys include septic tanks and individual package plants in place of municipal collection facilities in most locations. In Key Largo, both facilities discharge...Full Text Available
The Nilsson Plate High Frequency Adaptation of the Static Electrification Monitor developed by Electric Research and Management, Inc. for EPRI has demonstrated that the Nilsson Plate can be utilized as a practical high frequency antenna to record partial discharge activity within a transformer. Tests in the ABB factory at Muncie, IN on a 650 MVA, 345/20.9 kV, three-phase unit step-up transformer for TU Electric showed the Nilsson plate detecting partial discharge activity. Although this test was the first attempt at using the Nilsson plate in this manner, and in spite of higher than expected electrical noise levels, the data demonstrated that partial discharges can be detected. The tests also demonstrated that corona activity external to the transformer was not recorded by the plate. Some development work needs to be completed to eliminate the noise source from other monitors on the Static Electrification monitor, and to ...
This manual provides information to assist in selection and designing control measures for reducing pollutant discharges from combined sewer overflows (CSOs). he manual will be useful for municipal public works staff, design engineers, and regulatory agency staff tasked with the ...
twenty 350 V, 2.5 mF aluminum electrolytic capacitors with 10.8 mH inductors made of multi-strand wire. The PFN discharge was controlled using an silicon ...
The barrier glow discharge between two planar electrodes, covered with dielectric, is studied under high-voltage pulsed power supply. Wide applications of such type of discharges, in particular, for ozone production, stimulated a number of investigations in this direction. In this work we investigated the dependence of ozone concentration on the duration and the rate of pulse rise of the applied voltage. The thyristor converter circuit with the shortening of input pulses on the base of the saturable throttle was used for the realization of this task. The output pulses with amplitude up to 15 kV, repetition frequency of 1 kHz, pulse duration of 0.3 #mu#s (or 7 #mu#s) and the rate of pulse rise of 0.1 #mu#s were generated with this scheme. Measurements of the ozone concentration produced in the air mixture have shown that its value increased by factor two with variation of the rate of pulse rise from 0.5 #mu#s to 0.1 #mu#s (for pulse duration of ...
OBJECTIVES: To describe the immediate reported management, by general practitioners (GPs), of men presenting with symptoms of urethral discharge, or dysuria only. SUBJECTS: All 692 GPs in practice in...Full Text Available
The report summarizes the environmental significance of the priority pollutants being discharged from thirteen subcategories of the ore mining and dressing point source category. In addition, the impact of proposed effluent limitations guidelines is assessed from an environmental perspective.
MmMg{sub 12}-Ni amorphous or nanocrystalline composites (Mm: Ce-rich mischmetal) were prepared through the ball-milling method, and their electrochemical hydrogen storage performance was investigated and compared with that of ball-milled CeMg{sub 12}-Ni composites. It was found that the ball-milled MmMg{sub 12}-Ni composites had larger initial discharge capacities and better high rate dischargeability. Analysis of electrochemical impedance spectra (EIS) shows that the reaction resistance and hydrogen diffusion resistance of the ball-milled MmMg{sub 12}-Ni composites are lower as a result of the decrease in Ce content, and thus can contribute to the larger discharge capacity and better high rate dischargeability. Additionally, the cycle performance of the ball-milled MmMg{sub 12}-Ni composites is better than those of the ball-milled CeMg{sub 12}-Ni composites. This may be related to the formation of a Nd ...
The effect of atmospheric pressure on tracking resistance of organic insulating materials were investigated in the range of 500 to 1007 hPa. The tracking resistance for Polycarbonate (PC), Modified Polyphenylene Oxide (M-PPO) and Paper Base Phenolic Resin Laminate (PL) increase with the decrease in atmospheric pressure. The scintillating discharges on these samples surface lead to the ignition. The tracking failure on these results from the ignition on the surface. For Polybutylene Terephthalate (PBT) and Polyethylene Terephthalate (PET), the tracking resistance decrease with the decrease in atmospheric pressure. The discharges observed on the these surface are the glow-like. The discharge area spreads on the surface between the electrodes at the lower pressure. The failure on this group results from the carbonization by the discharges on the surface. However, the tracking resistance for Unsaturated ...
We investigated the effects of wastewater treatment plant (WWTP) discharge on the ecology of bacterial communities in the sediment of a small, low-gradient stream in South Australia. The quantification...Full Text Available
A numerical technique is developed for estimating water quality violation frequencies due to pollutant discharges from urban areas during combined sewer overflow events. The first four moments of in-stream pollutant concentration are found by integrating a pollutant loading - wat...
Several theories have proposed a functional role for synchronous neuronal firing in generating the neural code of a sensory perception. Synchronous neural activity develops during a critical...Full Text Available
This document is a technical background document for proposed regulations to limit effluent discharges to waters of the United States and introductions of pollutants into publicly owned treatment works from facilities engaged in porcelain enameling. The p...
A type of electromyographic activity, formerly referred to as "pseudomyotonia", can be recorded from the striated muscle of the urethral sphincter using a concentric needle electrode. There are two...Full Text Available
The stability of a solid ice cover subjected to rapidly varying water levels and discharge was investigated. The support from the bank limits the stress in the ice cover and consequently bank contact must be maintained to ensure ice cover stability. An analysis was required of the stability of ice hinges, a flexible connection between a solid ice cover and the riverbank. Phase II and phase III of the research involved a field study of the Peace River, investigating the evolution of ice hinges with water level variation, from initial ice cover cracking parallel to the banks, to a fully developed hinge. A test program of midwinter discharge variations was undertaken to gather specific data and measurements of ice hinge link length, ice thickness, hinge joint behavior, riverbank geometry, and response of ice hinging to water level variation. This volume of appendices to the study presents detailed observations and comments from field notes through ...
The objective of this retrospective field study was to associate the type and smell of discharge, the size of the uterus, the ovarian and treatment status, and the time to diagnosis of animals with...Full Text Available
The agglomerate for the element is made from activated charcoal powder, an electrically conducting additive and a neutral electrolyte. The activated charcoal makes up 30 to 50 percent of the weight of the agglomerate. It is a mixture of hydrophobized and unhydrophobized powder in a ratio of 85 to 70 to 15 to 30. The element has high discharge characteristics.
Sewage gas or biogas as a product of anaerobic digestion contains methane and carbon dioxide as its main components. Biogas is scrubbed off carbon dioxide in absorption columns and purified to natural-gas quality. The purified gas then is piped to the gas pressure control station and fed into the public network. Description of process and plant is given.
Volume 2 of the water resources data for the 1992 water year for Oklahoma consists of record of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes or reservoirs; and water levels of ground-water well. The report contains discharge records for 136 gaging stations; stage and contents for 31 lakes or reservoirs; water quality for 50 gaging stations. Also included are 61 partial-record or miscellaneous streamflow stations and 28 ground-water sites.
The low alloy steels were nitrided in the plasma atmosphere generated by using hollow cathode discharge. For comparison, specimens of 40 Cr steel were in two different potential states. One kind is isolated from cathode and anode between them the discharge was created. The other kind is placed on the plate which is connected to the cathode. The nitriding was carried out at different temperatures. The surface morphology, phase of compound layers and microhardness profiles were analyzed. The optical microscopy observation and X-ray diffraction showed that the compound layers were formed in all experiments. The results of the nitriding treatment are weakly dependent on the potentials applied on the specimens.
This paper reported on a study in which partial discharge (PD) measurements were performed on 6 underground transmission cable circuits to determine the effectiveness of PD measurements on fluid fill cables. The cables were between 37 and 56 years old. PD activity was detected from the terminations of H11L and H3L Cable 2. However, for cables from H3L Basin TS to Mill Street junction, PD activity was detected originating from within the main cable insulation.
A numerical model has been developed to simulate the charging and discharge behaviour of an electrically rechargeable alkaline zinc-air battery. Further a galvanostatic experiment including three charge/discharge cycles has been performed. The cell voltages, the Zn electrode potentials versus a Zn reference, and the O{sub 2} electrode potentials versus a Zn reference calculated with the model are in fairly good agreement with the corresponding experimental data. The model is expected to be useful for zinc-air battery design and for analysis of experimental data. (author)
This paper presents the first results of a study of plasma nitriding in various regions of a d.c. glow discharge, i.e. on the cathode, on the anode, and on a substrate isolated from the cathode and anode (at plasma potential). The results obtained reveal differences in the growth kinetics and surface morphology of the nitriding layers, depending on the region where the nitriding process took place. The aim of this work was to study the role of low temperature plasma in the plasma nitriding process. The processes were carried out in an apparatus for plasma treatment with a hot anode. (orig.)
Argon ion laser induced fluorescence measurements were carried out in a multipolar filament discharge with a broadband diode laser centered on 668 nm, which stimulated a transition from the metastable state in Ar(II) 3d4F7/2 to 4p4D05/2. The intensity of the induced fluorescence at 442 nm was maximized by the optimization of the discharge parameters and the laser power. From the recovery of the background fluorescence after the laser was turned off, the ion diffusion coefficient was deduced and compared with the result inferred from the experiments of ion acoustic wave (IAW) damping.
High interelectrode voltage peaks have been observed simultaneously with the emission of hard X-ray bursts from a flash X-ray tube. The magnitude of the voltage peaks may exceed twice the initial charging voltage. It has also been observed that the discharge emits bursts of X-and P-band microwaves radiation which are coincident with the emission of the hard X-ray bursts. The results indicate that the microwaves and X-rays have a common origin in discharge plasma movements and an acceleration model for electrons in the plasma is presented as one possible explanation of the observed phenomena.
A nanoparticle generator based on the principle of electrical discharge (PALAS GFG-1000) was used to produce nanoparticles of different chemical natures. The fractions of electrically neutral particles were then measured by means of a Spectrometre de Mobilite Electrique Circulaire (SMEC, i.e. radial-flow mobility analyzer) for different operating conditions. The experimental results were compared with the theoretical values calculated from the Fuchs extended charge equilibrium model for spherical particles and agglomerates. For the smallest particles (below 20 nm), the deviations observed remain below 10%, and tend towards 20% for larger particles (over 35 nm).
The authors investigated the influence of tartaric acid, which possesses complex-forming properties. In order to establish the optimum system of possible refinement of tellurium, the authors study the kinetics of both the cathodic and the anodic processes. The investigation of processes of discharging-ionization of tellurium from nitric acid electrolytes in the presence of tartrate ions showed the possibility of preparing a nitric-tartaric acid electrolyte which can be used for commercial purposes and from which a high-purity raffinate was obtained from technical tellurium.
An empirical model of detonator electrical performance which describes the resistance of the exploding bridgewire (EBW) or exploding foil initiator (EFI or slapper) as a function of energy, deposition will be described. This model features many parameters that can be adjusted to obtain a close fit to experimental data. This has been demonstrated using recent experimental data taken with the cable discharge system located at Sandia National Laboratories. This paper will be a continuation of the paper entitled ``Cable Discharge System for Fundamental Detonator Studies`` presented at the 2nd NASA/DOD/DOE Pyrotechnic Workshop.
An aspiration cover is proposed for the site of loading a belt conveyer including a housing arranged above the belt conveyer in whose cover there is an aspiration sleeve and a discharge chute from the upper wall and a guide having a cushioning plate on the lower end. It is distinguished by the fact that in order to improve the effectiveness of removing dust by decreasing the volume of aspirated air, the cover between the aspiration sleeve and the upper wall of the loading chute is convex in the inside of the housing and has a smooth connection to the upper wall of the discharge chute turned towards the cushioning plate.
A compartment model is described which is currently used by the Ministry of Agriculture, Fisheries and Food to calculate collective radiation exposure due to liquid radioactive wastes discharged to sea from UK nuclear sites. Collective dose is a useful indicator of the radiological impact of a disposal practice and is one of the quantities needed to show compliance with the ICRP system of dose limitation. The model has been used for the purposes of the Sizewell Inquiry to predict the collective radiation exposure from reactor operation at Sizewell and, on the basis of current Sellafield experience, correlations between dose and discharge for disposals of fuel reprocessing wastes. (author).
We report the performance of a micro gas turbine on biomass producer gas and mixtures of biomass producer gas with natural gas. The micro gas turbine delivers full power on gas mixtures with a heating value of at least 15 MJ/Nm{sup 3}. For gas of lower heating value, the maximum fuel gas flow limits the attainable power. The lower limit for stable operation is about 8 MJ/Nm{sup 3}. The gross efficiency of the micro gas turbine depends on output power but not on the gas heating value, within our measurement accuracy. Above 70% of full power, emissions of CO and NO are 40 and 10 times lower than those of a gas engine of similar size. At part load below 70% of full power, the micro gas turbine burner switches to a different operating mode ...
The most effective way to generate electricity out of biomass is the gasification and the use of the gas in a gas engine. The conversion of the organic carbon with the gasification of biomass is higher than 95 %. Depending on the gasification concept, the efficiency of gasifiers is found between 70 and 90 %. If the pyrolysis gas is used in a gas engine, an electric efficiency of about 26 % referring to the primary amount of energy can be obtained. With efficient gas cleaning (cleaning for tar and dust), pyrolysis gas is well qualified for engine combustion. Through modern state of engine controlling there are ways to have complete control of the fluctuations in the gas composition. Furthermore, the minor calorific value of offered wood gas poses no problem for turbo charged lean-burn gas engines. ...
This patent describes an electrodeless lamp. It comprises: a microwave cavity; a source of microwaves in communication with the cavity; a lamp envelope containing a plasma-forming medium mounted within the microwave cavity; a gas manifold for feeding gas to at least one gas passageway for directing a stream of gas to the outer surface of the envelope; a gas leak passageway leading from the gas manifold; a conductive mesh assembly for retaining microwaves within the cavity and permitting light to be emitted from the cavity. The assembly including gas flow blocking means for preventing the flow of gas through the gas leak passageway when the screen is in place in the lamp; and means for shutting off the source of microwaves when the gas pressure in the manifold drops below a ...
This report summarises nearly 20 biosphere reports and gives a synthesis of the work performed within the SR-Site Biosphere project, i.e. the biosphere part of SR-Site. SR-Site Biosphere provides the main project with dose conversion factors (LDFs), given a unit release rate, for calculation of human doses under different release scenarios, and assesses if a potential release from the repository would have detrimental effects on the environment. The intention of this report is to give sufficient details for an overview of methods, results and major conclusions, with references to the biosphere reports where methods, data and results are presented and discussed in detail. The philosophy of the biosphere assessment was to make estimations of the radiological risk for humans and the environment as realistic as possible, based on the knowledge of present-day conditions at Forsmark and the past and expected future development of the site. This was achieved by using the best available ...
Appendices to this summary consist of twelve individual status reports that will be available through the National Technical Information Service (NTIS) in the United States and of course limited copies will be available through NATO. The twelve report titles which are appendices to the summary are: (A) Status Report on the Limestone/Sludge Flue Gas Desulfurization Process; (B) Status Report on the Lime/Sludge Flue Gas Desulfurization Process; (C) Status Report on the Double Alkali/Sludge Flue Gas Desulfurization Process; (D) Status Report on the Sea Water Scrubbing Flue Gas Desulfurization Process; (E) Status Report on the Limestone/Gypsum Flue Gas Desulfurization Process; (F) Status Report on the Lime/Gypsum Flue Gas Desulfurization Process; (G) Status Report on the Double Alkali/Gypsum Flue Gas Desulfurization Process; (H) Status Report on ...
Gas hydrates have impacted the oil and gas industry since 1934, when they were first found to plug pipelines. Today we know that in deep oceans and in permafrost, very substantial gas reserves are present in hydrated form. Concerns are being raised about in situ dissociation for both energy and greenhouse implications upon methane release. In Japan work is underway to consider the storage of carbon dioxide, concentrated in clathrates. This talk will deal with some basic questions. Why should we be interested in gas hydrates? What are gas hydrates? How do gas hydrates form? How might hydrates impact on the energy/environmental picture?
Gas hydrates are crystalline substances composed of water and gas, in which a solid-water-lattice accommodates gas molecules in a cage-like structure. Gas hydrates are globally widespread in permafrost regions and beneath the sea in sediment of outer continental margins. While methane, propane, and other gases can be included in the clathrate structure, methane hydrates appear to be the most common in nature. The amount of methane sequestered in gas hydrates is probably enormous, but estimates are speculative and range over three orders of magnitude from about 100,000 to 270,000,000 trillion cubic feet. The amount of gas in the hydrate reservoirs of the world greedy exceeds the volume of known conventional gas reserves. Gas hydrates also represent a significant drilling and production hazard. A fundamental question ...
Gas hydrates are crystalline substances composed of water and gas, in which a solid-water-lattice accommodates gas molecules in a cage-like structure. Gas hydrates are globally widespread in permafrost regions and beneath the sea in sediment of outer continental margins. While methane, propane, and other gases can be included in the clathrate structure, methane hydrates appear to be the most common in nature. The amount of methane sequestered in gas hydrates is probably enormous, but estimates are speculative and range over three orders of magnitude from about 100,000 to 270,000,000 trillion cubic feet. The amount of gas in the hydrate reservoirs of the world greedy exceeds the volume of known conventional gas reserves. Gas hydrates also represent a significant drilling and production hazard. A fundamental question ...
We report the performance of a commercial recuperated micro gas turbine on biomass producer gas and mixtures of biomass producer gas with natural gas. The biomass producer gas, obtained by gasification at 850{sup o}C with air at atmospheric pressure, contains about 7% H2, 17% CO, 15% CO2, 4% CH4, 2% other hydrocarbons, 2% H2O, and a balance of N2 and Ar from air. It has a net heating value of about 6 MJ/(Nm{sup 3}). The micro gas turbine delivers full power (30 kW{sub e}) on gas mixtures with a net heating value of at least 15 MJ/(Nm{sup 3}). For gas of lower heating value, the maximum fuel gas flow allowed by the fuel control unit limits the attainable power. At reduced power, the lower limit for stable operation is a net heating value of about 8 MJ/(Nm{sup 3}). The gross efficiency of the micro ...
Some hypo-stoichiometric Zr-based Laves phase alloys were prepared and studied from a viewpoint of discharge capacity for electrochemical application. After careful alloy design of ZrMn{sub 2}-based hydrogen storage alloys through changing their stoichiometry while substituting or adding some alloying elements, the Zr(Mn{sub 0.2}V{sub 0.2}Ni{sub 0.6}){sub 1.8} alloy reveals relatively good properties with regard to hydrogen storage capacity, hydrogen equilibrium pressure and electrochemical discharge capacity. In order to improve the discharge capacity and rate-capability, Zr is partially replaced by Ti. The discharge capacity of Zr{sub 1-x}Ti{sub x}(Mn{sub 0.2}V{sub 0.2}Ni{sub 0.6}){sub 1.8} (x=0.0, 0.2, 0.3, 0.4, 0.6) alloy electrodes at 30 C reaches a maximum value and decreases as the Ti fraction increases. In view of electrochemical and thermodynamic characteristics, the occurrence of a maximal ...
The situation of natural gas in the Federal Republic of Germany is described, with particular emphasis on the advantages and consequences of natural gas supply. The brochure discusses the role of natural gas on the energy market, the reliability of natural gas supply, the environmental impacts, the energy-saving effect of natural gas, natural gas prices, the competitive strength of the German gas industry, and the long-term reliability of natural gas supply. (orig.) [German] Die Situation des Erdgases in der Bundesrepublik Deutschland wird beschrieben, wobei die wichtigsten Vorteile und Auswirkungen der Erdgasversorgung besonders hervorgehoben werden. Es geht um die Stellung des Erdgases im Energiemarkt, die Sicherheit der Energieversorgung, Umweltschutz, Energieeinsparung durch Erdgaseinsatz, Erdgaspreise, ...
Effects of combustion conditions on the critical calorific value of flame blowout were reported for low calorific gas on the assumption of using coal derived gaseous fuel. Further, calculations of adiabatic flame temperature by using chemical equilibrium calculation were conducted in order to get a possibility of increasing exit gas temperature of gas turbine combustor to 1,300 C for low calorific value gas fuel. As a result, effects of (1) fuel composition, (2) preheating fuel temperature, (3) calorific value, and (4) combustion air velocity and fuel nozzle diameter, on the critical calorific values of flame blowout were clarified. In increasing exit gas temperature of gas turbine combustor to 1,300 C when using low calorific value gas fuel, it is essential to get an advanced cooling technology for the gas turbine ...
The genetic type, source and charging history of natural gas in the Yulin gas field in the Ordos Basin have been studied by combining the carbon isotopic composition of natural gas and geochemical characteristics of light hydrocarbons with carbon isotope fractionation model results and fluid inclusion analysis. The carbon isotopic composition of methane and ethane in the Yulin gas field is relatively enriched in {sup 13}C with {delta}{sup 13}C{sub 1} values ranging from - 35.3 permille to - 29.8 permille (average value = - 32.4 permille) and {delta}{sup 13}C{sub 2} ranging from - 26.3 permille to - 23.5 permille (average value = - 24.8 permille). The C{sub 7} light hydrocarbons are predominated by methylcyclohexane, accounting for 65.8% to 80.9% (average value = 71.6%), which is characteristic of coal-derived gas. Furthermore, the gas geochemistry indicates ...
The production, principal applications, characteristics and properties, advantages of the gas natural is showed. A sectorial overview of the ceramic industry and the utilization of the natural gas in the ceramic industry is presented. The expectations are systematized and the impact of the natural gas utilization in the ceramic industry is evaluated. Some conclusions are withdrawn and recommendations suggested.
A combined gas/steam turbine process includes a high-pressure furnace and a high pressure gasification unit with a mounted upstream of a combustion chamber there is a gas turbine with a waste heat system. Combustion heat which is not needed to heat the flue gas to combustion temperature is released from the furnace and transferred to ths combustion air going into the combustion chamber.
Nomographs have been developed to simplify site performance estimates for various types of gas turbine engines used for industrial applications. The nomographs can provide valuable data for engineers to use for an initial appraisal of projects where gas turbines are to be considered. General guidelines for the selection of gas turbines are also discussed. In particular, site conditions that influence the performance of gas turbines are described.
The budding natural gas markets in East Europe attract a great deal of interest from natural gas industries in the Western countries. Dutch companies, institutions and the government, too, are active in this market. So far the results have not been spectacular. An analysis is made of the present situation and the Dutch approach
An efficient method of hydrogen storage in nano-porous carbons is its reversible sorption by electrochemical decomposition of a KOH water solution [1-3] according to the following equation: C + xH{sub 2}O + xe{sup -} {yields} (CH{sub x}) + xOH{sup -} where (CH{sub x}) stands for the hydrogen inserted into the nano-porous carbon during charging and oxidized during discharging. Although various carbon materials have been investigated as hydrogen adsorbents, the information about the storage mechanism as well as the nature of the hydrogen/carbon interaction is still not sufficient. In order to extend the understanding of the process, carbon samples charged electrochemically were investigated by temperature programmed desorpt(TPD). The nature of the hydrogen/carbon interaction was studied by electrochemical analysis at different temperatures. The TPD experiments consist of heating the samples from room temperature to 950 C and of quantitative analysis by on-line mass ...
In 1999, the plasma parameters of reversed shear (RS) plasmas had been extended in 1) DT-equivalent fusion power gain Q_D_T"e"q - 0.5 (n_D(0)#tau#_ET_i(0) - 4x10"2"0 m"-"3#centre dot#keV#centre dot#s) for 0.8 s and 2) full non-inductive current drive with 80% of the bootstrap current fraction. Physics of the internal transport barriers (ITBs) in RS plasmas, including the energy transport and the formation of ITB, were extensively studied. A nearly full current drive (92% non-inductively) was obtained with negative ion based neutral beam (NNB) injection (360 keV, 3.4 MW) in a high #beta#_p H-mode plasma (I_p=1.5 MA, B_T=3.7 T, q_9_5=4.2) with high plasma performance (#beta#_N=2.4 and H_8_9=2.56). Rise in the central electron temperature (T_e - 9 keV) resulted in the current drive efficiency #eta#_C_D of NNB reached 1.3x10"1"9 A/W/m"2, the highest for the neutral beam current drive. As for the H-mode plasmas, decrease in the pedestal ion temperature due to strong gas ...
The Forsmark area consists of a number of natural wetlands. As a part of the evaluation of wetlands in the safety assessment for the area, possible future wetlands are being studied with respect to hydrology and transport mechanisms. A sensitivity analyses is performed to point out the governing parameters for the wetland hydraulics. The analysis of future wetlands is carried out using the hydrological model system Mike SHE. Mike SHE has been used to describe the near-surface hydrology for a regional model area in Forsmark. Three types of areas have been chosen. Today's lake Bolundfjaerden is because of its shallow depth likely to develop into a mire in the future. As it is situated in the downstream part of the regional model area, the runoff to the lake from upstream surface water system is significant. Lake Eckarfjaerden is situated in the upstream part of the catchment at a higher altitude and with a smaller inflow. Lake Puttan is situated above a planned layout of the ...
Powder mold type solid state battery was fabricated, and positive electrode compounding ratio and the battery characteristics were studied. The current density depended greatly on the TiS2 content of positive electrode material, and the current density showed maximum value of 800 {mu}A/cm{sup 2} at a TiS2 content of 40 wt%. This composition is expected to be the best to provide better charge-discharge characteristics. The rate capability of TiS2 is dominated by Li{sup +} ion in positive electrode. Further, the diffusion of lithium ion is greatly dominated by TiS2 in positive electrode, compounding ratio of solid state electrolyte and its particle size. Results of charge-discharge characteristics studied for various charge-discharge current densities revealed that the rate capability of TiS2 was more than 50% for a current density of less than 254 {mu}A/cm{sup 2}, and this battery system proved the possibility of high rate ...
The recent rapid progress in surface treatment techniques dictates that the titanium alloys should have an improved resistance to frictional wear without any loss of their high corrosion resistance. These requirements can be satisfied by producing surface layers of specified microstructure and phase composition. The present paper describes a modification of the plasma discharge nitriding treatment of titanium alloys, i.e. the glow discharge-assisted oxycarbonitriding, which by introducing oxygen, nitrogen and carbon into the surface zone of the layer [a Ti(NCO) type layer] improves its useful properties, primarily the resistance to frictional wear and the resistance to corrosion [T. Wierzchon, J. Sobiecki, Vacuum, 44 (1993) 975; T. Wierzchon et al., in: G. Hecht, F. Richter, J. Hahn (Eds.), Thin Films, DGM Informationgesellschaft, Germany, 1994, p. 195] [1:2]. This is because titanium shows a good affinity to oxygen, carbon and nitrogen, ...
Environmental Survey Laboratory at Tarapur, Maharashtra site carries out environmental radioactivity measurements in different matrices to evaluate the impact of operating nuclear installations. In this paper, the evaluation of data of 1983-2007 (25 years) is presented. Time trends of particulate radioactivity, correlation between "1"3"7Cs in discharge canal seawater and station discharged activity and correlation of "1"3"7Cs, "6"0Co, and "1"3"1I in marine species like Sponge and Nerita and corresponding discharged activity were carried out. Statistical analysis of environmental data of seawater and marine fish for several radionuclides, for distributions, showed that the data best fits lognormal distribution. A strong correlation between "1"3"7Cs in seawater and "1"3"7Cs in liquid waste discharge was observed (R"2 = 0.8, P = 0.000). Similarly correlation was very good for Nerita and ...
The Co-Si composites with a molar ratio of 2:1 are synthesized by ball-milling method and their potential as negative electrode materials of Ni-MH batteries is investigated. The microstructure, morphology and chemical state of the ball-milled Co-Si composites are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). XRD patterns show that the ball-milled samples for 10 and 20 h contain Co, Si and Co{sub 2}Si phases, and the ball-milled samples for 40 and 60 h are mainly amorphous Co{sub 2}Si alloys. In contrast to the high initial discharge capacity (1012 mAh/g) obtained for the sample ball-milled for 10 h, the discharge capacities of the samples ball-milled for 40 and 60 h are very low. It indicates that the hydrogen storage capacity of pure Co{sub 2}Si alloy is very low. It is found that the formation of active Co nanoparticles and Si oxidation are responsible for the high ...
This article puts the case for coal fired combined cycle gas turbine (CCGT) power plants. The need to gasify the coal for the CCGT, use of fluidised bed combustors or gasification systems, the difference in prices of coal and natural gas, and coal and natural gas reserves are discussed. (UK)
Natural gas is essential to the world economy. Gas now accounts for almost a quarter of OECD primary energy requirements and is expected to become the second most important fuel in the world in the next decade. Industrial and residential consumers increasingly rely on natural gas to keep their houses warm, their lights on and their factories running. Meanwhile the gas industry itself has entered a new phase. Where gas used to be restricted to regional markets, it is now increasingly traded on a global scale. While gas production and transport requires long-term investment, now it is optimised on a short-term basis. Demand continues to grow, but local gas production has become much more expensive. How should we react? How will demand be satisfied? What changes are required to promote flexibility and trade? What are the implications for ...
Mist eliminators for flue gas desulphurisation units remove liquid droplets entrained in the flue gas leaving the SO/sub 2/-absorber vessels. The commercial designs currently available are described.
The purpose of this project was to build a long-range, parallel hybrid gas/electric vehicle capable of driving beyond the communter capabilities of series hybrid vehicles. It was envisioned that since the gas engine would be able to independently propel t...
Radon-222 has been measured in natural gas produced from experimental geopressured-geothermal test wells. Comparison with published data suggests that while radon activity of this unconventional natural gas resource is higher than conventional gas produced in the gulf coast, it is within the range found for conventional gas produced throughout the US. A method of predicting the likely radon activity of this unconventional gas is described on the basis of the data presented, methane solubility, and known or assumed reservoir conditions of temperature, fluid pressure, and formation water salinity.
Water-resources data for the 1993 water year for Texas are presented in four volumes, and consist of records of stage, discharge, and water quality of streams and canals; and stage, contents, and water quality of lakes and reservoirs; and water levels and water quality of ground-water wells. Volume 3 contains records for water discharge at 134 gaging stations; stage only at 1 gaging stations; stage and contents at 13 lakes and reservoirs; water quality at 81 gaging stations; and data for 30 partial-record and 4 flood-hydrograph partial-record stations. Also included are lists of discontinued surface-water discharge or stage-only stations and discontinued surface-water-quality stations; crest-stage and flood-hydrograph partial-record stations, reconnaissance partial-record stations, and low-flow partial-record stations.
The A2P-X2+Dv=-3 bands of the 12C14N radical have been observed by time-resolved Fourier transform spectroscopy in the 1850-3100cm-1 region with a wavenumber resolution of 0.025cm-1. The radical was produced in a pulsed positive column discharge in a cyanogene and helium mixture. Seven bands of v=0-3, 1-4, 2-5, 3-6, 4-7, 5-8, and 6-9 were analyzed to give the molecular constants of each state by least-squares fitting of 801 lines. The pulsed discharge was found to be efficient for production of CN in the excited A2P state. The vibrational excitation temperature was determined to be 6680+-835K and 6757+-534K for the A2P and X2+ states, respectively. The population of the A2P was found to be 4% of that of the X2+ state in the time after turning off the discharge.
Single-electrode transient behavior was measured mainly during the discharging process for a model cell of electric double layer capacitor with nano-porous carbon electrodes and reference electrode. Apparent conductivity in the cell, which we call `effective conductivity,` is determined with approximation of current in transient behavior to a one-dimensional electrophoretic model. A comparison of effective conductivity with conductivity of bulk solution suggests an interesting mechanism of transfer of electrolyte ions. The difference in transient behavior between various electrolyte ions was not conspicuous in spite of distinctive differences in conductivity of each bulk solution. The large pore diameter of the carbon electrode results in rapid transient behavior and such an electrode should be suitable for rapid charge and discharge. The effect of origin of carbon electrode is found to be significant to bring considerable differences in ...
Pyrethroid pesticides occur in urban creek sediments at concentrations acutely toxic to sensitive aquatic life. To better understand the source of these residues, runoff from residential neighborhoods around Sacramento, California was monitored over the course of a year. Pyrethroids were present in every sample. Bifenthrin, found at up to 73 ng/L in the water and 1211 ng/g on suspended sediment, was the pyrethroid of greatest toxicological concern, with cypermethrin and cyfluthrin of secondary concern. The bifenthrin could have originated either from use by consumers or professional pest controllers, though the seasonal pattern of discharge from the drain was more consistent with professional use as the dominant source. Stormwater runoff was more important than dry season irrigation runoff in transporting pyrethroids to urban creeks. A single intense storm was capable of discharging as much bifenthrin to an urban creek in 3h as that ...
Pyrethroid pesticides occur in urban creek sediments at concentrations acutely toxic to sensitive aquatic life. To better understand the source of these residues, runoff from residential neighborhoods around Sacramento, California was monitored over the course of a year. Pyrethroids were present in every sample. Bifenthrin, found at up to 73 ng/L in the water and 1211 ng/g on suspended sediment, was the pyrethroid of greatest toxicological concern, with cypermethrin and cyfluthrin of secondary concern. The bifenthrin could have originated either from use by consumers or professional pest controllers, though the seasonal pattern of discharge from the drain was more consistent with professional use as the dominant source. Stormwater runoff was more important than dry season irrigation runoff in transporting pyrethroids to urban creeks. A single intense storm was capable of discharging as much bifenthrin to an urban creek in 3 h as that ...
This paper reports the result obtained during fiscal 1994 on a demonstration research on photovoltaic power generating systems. Solar cells with an output of 750 kW, storage battery facilities with an output of 3,058 kWh, three DC-AC converters with a rating of 250 kW, and a diesel generator with an output of 300 kW having been installed up to the previous fiscal year were combined to perform comprehensive adjustments and tests such as battery charge/discharge tests and AC parallel operation tests. The battery charge/discharge tests revealed that the 10 hour rate discharge capacity meets the specifications, and the batteries are free of deterioration after a demonstration operation of about 4.5 months. Difference between the power generation record and the planned value is thought due to the following reasons: the array output data in a power line connected system come about 90% of the simulation result due to correction ...
This paper builds on earlier work to give a consistent treatment of the positive column of discharges in electronegative gases covering the transition from collisionless to collisional. In particular it seeks to elucidate the conditions under which there is an ion-ion plasma core surrounded by an electron-ion plasma, and when there is not. The parameters which describe the processes of ionization, attachment, detachment and recombination are related to the central negative ion density relative to the electron density and, where appropriate, the size of the core. The use, by earlier workers, of the Boltzmann approximation to describe the negative ion distribution and to obtain ambipolar diffusion coefficients at higher pressures is shown not to be justified. This leads to the clarification of an inconsistency in the literature. Where possible, the work is related to other recent treatments of the same problem in order to begin to build a comprehensive picture of ...
Over the last four decades the Irish Sea has received controlled discharges of radioactive effluents from the Sellafield (Windscale) nuclear fuel reprocessing plant in Cumbria, UK. Enhanced levels of a range of fission, activation and transuranic elements have been reported in a variety of environmental media. Most of the {sup 239,240}Pu and {sup 241}Am and about 10% of the {sup 137}Cs have been retained in a deposit of the fine sediment near the discharge point. The quantities of radionuclides discharged annually from Sellafield decreased by two orders of magnitude from the mid-1970s to 1990, but estimated critical group internal and external exposure decreased by less than one order of magnitude over this period. Redistribution of the contaminated marine sediment is potentially of major significance. In this paper, a review is presented of published work and recent our study relating to Sellafield waste long-lived ...
Two plasma chemistries, i.e., CH_4/H_2/Ar and Cl_2/Ar, were compared for the etching of InGaP, AlInP, and AlGaP under inductively coupled plasma (ICP) conditions. While the etching with CH_4/H_2/Ar discharges appears to be ion driven, Cl_2/Ar discharges showed an additional strong chemical enhancement. The highest etch rate (#approx#1 #mu#m/min) for InGaP was achieved at high ICP source power (#>=#750 W) with the Cl_2/Ar chemistry. Cl_2/Ar discharges provided very smooth surfaces in all three materials with root-mean-square roughness measured by atomic force microscopy around 2 nm. This result may be due to the efficient ion-assisted product desorption in this chemistry. The etched near-surface region of InGaP (#approx#100 Angstrom) with Cl_2/Ar maintained almost the same stoichiometry as that of the unetched control. By contrast, the CH_4/H_2/Ar plasma chemistry produced somewhat rougher surfaces and depletion of ...
Na/S battery can have the higher energy density and higher power density than that of existing high performance secondary battery. This battery is expected to use for electric load leveling and electric vehicle. Ni/MH battery was developed in advanced countries, but it is one of the advanced technologies which are preserved in their own country. In the study on Na/S battery, properties of B{sup -}alumina electrolyte was investigated. Also the construction technologies of this test cell was established by combining tube type of B{sup -}alumina solid electrolyte with Na-, S- electrode etc. Especially of this cell, charge/discharge performance and open circuit voltage was examined. Mi/MH battery sample were tested with SBT500 system for self-discharge rate at room temp, was measured. It was found that the electrolyte and separator can be optimized to minimize the self-discharge rate. (author). refs., figs., tabs.
The K Reactor at the Savannah River Site (SRS) shut-down in spring 1988 for maintenance and safety upgrades. Since that time the receiving stream for thermal effluent, Indian Grave Branch and Pen Branch, have undergone a pattern of post-thermal recovery that is typical of other SRS streams following removal of thermal stress. Divesity of fish and aquatic macroinvertebrate communities has increased and available habitats have been colonized by numerous species of herbaceous and woody plants. K Reactor is scheduled to resume operation in 1991 and operate through 1992 without a cooling tower to cool the discharge. It is likely that the reactor will operate at approximately one-third to one-half of full power (800--1200 MW thermal) during this period and effluent temperatures will be substantially lower than earlier operation at full power. Monthly average discharge temperatures at half-power operation will range from approximately 42 degrees C in ...
The purpose of this assessment is to develop a versatile process that will provide a mechanism for evaluating both present and future risks to this environment. Much of the regulatory and environmental interest in the port has centered around a Ballast Water Treatment facility that treats and discharges up to 30 mgd of oily ballast water brought in by crude oil tankers. However, six point discharges and other potential sources of pollution exist in the area. The authors have delineated eleven subareas in the port in order to identify the potential anthropogenic stressors, as well as the receptors that could be exposed to these stressors. Potential effects were then characterized for each exposure. Each component is ranked and integrated, resulting in a relative risk estimate in each subarea. Both the discernible risks, based on available data, and the data gaps are presented. Uncertainty is expressed as a range of high and low risk associated ...
BackgroundEmphysematous cholecystitis is a variant of acute cholecystitis which is generally caused by gas-forming organisms. Emphysematous cholecystitis may cause gas spreading...Full Text Available
... Accession Number : ADD135818. Title : Performance of Titanium in Flue Gas Desulfurization Scrubber Systems,. Descriptive Note : Journal Article,. ...
The properties of the ideal gas of classical (nonquantum) tachyons are considered. Starting from the definition of thermodynamic functions for this system, it may be found that tachyons and bradyons gases are similar. (AA).
A new surveillance system for Oil-Filled cable, which can provide continuous monitoring, using a newly developed optical gas sensor that can detect the concentration of the gas dissolved in the oil with extremely high sensitivity has been developed. It was proved that the degree of deterioration of the insulating oil can be detected by measuring C{sub 2}H{sub 2} and CH{sub 4} by investigating the relation between the degree of deterioration and amount of combustible gas generated. In order to detect extremely small amounts of gas, a new gas detecting method using absorption line of the gas using a frequency modulated technique has been developed. The gas detection ability was also confirmed by examination using a 66 kV of cable and the possibility of detection at an early stage is expected.
Rapid technology improvements, resulting in high efficiency, emissions reduction and low generation cost, are making gas turbines the generation technology of choice despite some recent reliability problems. The basic reason for the dominance is high efficiency. The rapid pace of gas-turbine technology improvement in the 1990s drove combined-cycle thermal efficiency to nearly 60 percent with natural gas as the fuel. It will probably go even higher after the year 2000. In addition, the gas-fired combined cycle is a bargain. With natural gas prices where they are right now, it is the least-cost generation operation for power producers with access to gas. Many will replace older, high-cost power plants with new gas-fired combined cycle power plants.
The oxygen production of a photosynthetic gas exchanger containing Chlorella pyrenoidosa (1% packed cell volume) was measured when various concentrations of carbon dioxide were present...Full Text Available
The purpose of this publication is to provide a better understanding of flue gas desulfurization. It provides brief answers to questions concerning its applicability, cost, effectiveness, and operation.
This bibliography contains 3920 references including abstracts, to information on the technology of flue gas desulfurization and denitrification. These references and others are included in the Department of Energy's Energy Data Base (EDB) through Decembe...
Tests to measure the maximum horsepower of commercial vehicles converted for use with natural gas fuel indicate a reduction of approximately 20% in horsepower compared with gasoline-driven vehicles. This reduction in horsepower resulting from the use of gas is due basically to the lower thermal efficiency of the cycle of natural gas compared with that of gasoline and to its lower volumetric efficiency, since natural gas is injected into the combustion chamber in gaseous form, unlike gasoline, in which part of the fuel entering the cylinder is in the liquid phase. Natural gas used as a fuel generates lower quantities of air pollutants, particularly unburned hydrocarbons (HCs) and carbon monoxide (CO). Despite the downside of reduced horsepower, the use of natural gas as a fuel for automotive vehicles equipped with Otto-cycle engines is economically viable owing ...
Water-resources data for the 1993 water year for Minnesota consists of records of stage, discharge and water quality of streams; stage, contents, and water quality of lakes and reservoirs; and water levels and water quality in wells and springs. This volume contains discharge records for 58 gaging stations; stage and contents for 9 lakes and reservoirs; water quality 15 stream stations, 1 lakes station, 1 precipitation station, and water levels for 15 observation wells. Also included are 61 high-flow partial-record stations. Additional water data were collected at various sites, not part of the systematic data collection program and are pulished as miscellaneous measurements.
Water-resources data for the 1991 water year for Minnesota consist of records of stage, discharge and water quality of streams; stage, contents, and water quality of lakes and reservoirs; and water levels and water quality in wells and springs. The volume contains discharge records for 60 gaging stations; stage and contents for 9 lakes and reservoirs; water quality for 18 stream stations, 1 lake station, 22 partial-record sites, 1 precipitation station, 108 wells; and water levels for 119 observation wells. Also included are 59 high-flow partial-record stations. Additional water data were collected at various sites, not part of the systematic data collection program and are published as miscellaneous measurements or low-flow investigations.
It is an object of the claimed invention to combine chemical treatment with microfiltration process to treat groundwater, leachate from contaminated soil washing, surface and run-off waters contaminated with toxic metals, radionuclides and trace amounts of organics from variety of sources. The process can also be used to treat effluents from industrial processes such as discharges associated with smelting, mining and refining operations. Influent contaminants amenable to treatment are from a few mg/L to hundreds of mg/L. By selecting appropriate precipitation, ion exchange and adsorption agents and conditions, efficiencies greater than 99.9 percent can be achieved for removal of contaminants. The filtered water for discharge can be targeted with either an order of magnitude greater or lower than contaminant levels for drinking water.
Volume III of the documentation for the Phase I Data Analysis Task performed in support of the current Regional Flow Model, Transport Model, and Risk Assessment for the Nevada Test Site Underground Test Area Subproject contains the data covering groundwater recharge and discharge. Because of the size and complexity of the model area, a considerable quantity of data was collected and analyzed in support of the modeling efforts. The data analysis task was consequently broken into eight subtasks, and descriptions of each subtask's activities are contained in one of the eight volumes that comprise the Phase I Data Analysis Documentation.
Reliability analysis is now being used to a large extent for several civil engineering structures. Such analysis has not been used for rockfill dams, the most common dams in Norway. Following work on reliability analysis for breakwaters, reliability analysis was then used to investigate the ability of the stone material on the upstream face of a rockfill dam to withstand wind generated waves. An attempt is made to follow up this work by including discharge overtopping on a rockfill dam in a reliability analysis. This report primarily goes through previous work on the required weight of protective stones on the downstream face of the dam for specified discharges over the dam and also deals with the probability formulation of extreme floods. A failure function with partial coefficients is formulated. But for reasons of economy the calibration of the partial coefficients remains for a next phase of the project. 14 refs., 17 figs.
The precedence effect (PE) is thought to be beneficial for proper localization and perception of sounds. The majority of recent physiological studies focus on the neural discharges correlated with PE in the inferior colliculus (IC). Pentobarbital anesthesia is widely used in physiological studies. However, little is known of the effect of pentobarbital on the discharge of neurons in PE. Neuronal responses in the IC from 23 male SD rats were recorded by standard extracellular recording techniques following presentation of 4ms white noise bursts, presented from either or both of two loud speakers, at different interstimulus delays (ISDs). The neural responses were recorded for off-line analysis before or after intraperitoneal administration of pentobarbital at a loading or maintenance dose. ...
For the development of a long-lived, electrically rechargeable zinc-air battery the structure and wettability of pasted zinc electrodes were optimized. Pasted zinc electrodes containing 1 to 10% cellulose, but having almost the same nominal capacities, were prepared and tested in zinc/oxygen cells. The effect of discharge rate on cell voltage and delivered capacity, as well as the maximum power, were measured. Furthermore, cell charge-discharge behaviour and cycle life were examined. After different times of operation, the porosity and the pore size distribution of the pasted zinc electrodes were measured by means of mercury porosimetry. The life cycle and peak power drain capability of the Zn/oxygen battery could be substantially improved by the addition of 10 wt% cellulose to the pasted zinc electrode. (author)
With the aim of optimizing the nitriding process, experimental studies of the plasma nitriding of four selected steels were carried out, using a d.c. glow discharge. The process parameters were varied systematically. By means of transmission and scanning electron microscopy and X-ray diffraction, the microstructures, including the thicknesses of the compound zones and the diffusion zones of the nitrided steels, were obtained. Using cross-sectional samples and a micro-Vickers indenter, hardness depth profiles were also obtained. From the time and temperature dependences of the hardness profiles, effective diffusion constants and corresponding activation enthalpies were obtained. Furthermore, in an attempt to shed some light on the atomistic nitriding mechanisms, the glow discharges were studied by measuring energy spectra of the energetic ions hitting the cathode (the steel test specimens). It was shown that an increase of the mean energy of the ...
Nanocrystalline MnO thin film has been prepared by a pulsed laser deposition (PLD) method. The reversible lithium storage capacity of the MnO thin film electrodes at 0.125C is over 472 mAh g{sup -1} (3484 mAh cm{sup -3}) and can be retained more than 90% after 25 cycles. At a rate of 6C, 55% value of the capacity at 0.125C rate can be obtained for both charge and discharge. As-prepared MnO thin film electrodes show the lowest values of overpotential for both charge and discharge among transition metal oxides. All these performances make MnO a promising high capacity anode material for Li-ion batteries. (author)
Aims and objectives.- To investigate infant well-being as measured by feeding and sleeping and parental support following discharge from the NICU in infants following major cardiac surgery. Background.- Infant feeding and sleeping have been identified as two of the most important concerns reported by parents. These concerns have been reported anecdotally for infants who have undergone cardiac surgery in the neonatal period. Design.- A prospective study using questionnaires and phone interviews followed a cohort of parents of neonates who underwent surgery in the neonatal period for congenital heart disease. Methods.- The study was conducted using validated questionnaires and phone interviews with a semi-structured questionnaire. The questionnaires were administered prior to discharge from ...
This work investigated the inactivation of Microcystis aeruginosa (MA) with contact glow discharge electrolysis (CGDE). The influences of applied voltage, current and treatment time on the inactivation rate were critically examined. Based on the above results, the optimal conditions were chosen to sufficiently utilize chemically active species and enhance the inactivation of MA. Under the optimal conditions (voltage: 530?V; current: 30?mA; treatment time: 20?min), the inactivation rate of algae was more than 90% within 5?days incubation after inoculating. At the same time, the concentrations of Chlorophyll-a and dehydrogenase decreased, which demonstrated that 20?min CGDE treatment could effectively inhibit the growth of MA and caused deterioration of cell integrity. The present work would...
Nanocomposites comprising nanocrystal silicon (Si), disordered carbon (DC), and multi-walled carbon nanotubes (MWCNTs) - denoted as Si/DC/MWCNTs - have been prepared by pyrolyzing the phenol-formaldehyde resin (PFR) mixed with Si and MWCNTs. This nanocomposite anode material showed a discharge capacity of 1216 mAh/g in the first cycle, and a charge capacity of 711 mAh/g after 20 charge-discharge, much higher than that of Si/DC composite. It can be observed that Si particles wrapped in MWCNTs were homogeneously embedded into the matrix of the DC. The improved electrochemical performance is hypothesized to be mainly attributed to the morphology stability of the composite due to the excellent resiliency and distinct electric conductivity of the MWCNTs.
The Electric Fuel zinc-air battery yielded energy densities from 6.8 to 10.2 times higher than those of the lead-acid batteries. The higher the power and the more difficult the driving cycle, the higher this ratio of energy densities grew. Not only was the Electric Fuel battery capable of extended high-power discharge, the impact of such discharge conditions on energy and driving range was show to be quite small, and was much smaller than the comparable impact on lead-acid traction batteries. At the time of writing this paper, tests are scheduled to continue with the 110-kWh battery in the Mercedes van, and preliminary plans have been made for testing of additional batteries on other vehicle types.
A compact and supersensitive device that can rapidly detect minute trace vapors from concealed explosives has been developed by scientists at Oak Ridge National Laboratory (ORNL). The new explosives sensor can detect and chemically identify organic nitrogen-oxygen compounds which are the building blocks of explosives such as TNT, plastiques, and nitroglycerine. The device could be used to scan persons entering airport terminals, nuclear power plants, defense installations, or other sensitive locations, providing greater security against potential terrorism. This device works on a glow discharge principle, and is more specifically called an ''Atmospheric Sampling Glow Discharge Ionization'' (ASGDI) source. The new detector is a highly automated, miniaturized version of research mass spectrometers widely used to trace constituents of chemical mixtures. Detail of this device's construction and ...
The nuclear complex in Tarapur, Maharashtra is a multi facility nuclear site comprising of power reactors and research facilities. Each facility has independent liquid effluent discharge line to Arabian Sea. Experimental studies were conducted to evaluate dilution factors in the aquatic environment using liquid effluent releases as tracer from one of the facilities. 3H and 137Cs radioisotopes present in the routine releases were used as simulated tracer nuclides. The dilution factors(D.F) observed for tritium were in the range of 20-20000 in a distance range of 10 m to 1500 m respectively and for 137Cs the D.F. were in the range of 50 to 900 over a distance range of 10-200 m. The paper describes the analytical methodology and sampling scenarios and the results of dilution factors obtained for Tarapur aquatic environment. (author)
Environmental data were collected for most environmental media including air, Columbia River water, external radiation, foodstuffs (milk, beef, eggs, poultry, and produce) and wildlife (deer, fish, and game birds), as well as soil and vegetation samples. In general, offsite levels of radionuclides attributable to Hanford operations during 1979 were indistinguishable from background levels. The data are summarized in the following highlights. Air quality measurements of NO/sub 2/ in the vicinity of the Hanford Site and releases of SO/sub 2/ onsite were well within the applicable federal and state standards. Particulate air concentrations exceed the standards primarily because of agricultural activities in the area. Discharges of waste water from Hanford facilities in the Columbia River under the National Pollution Discharge Elimination System (NPDES) permit were all within the parameter limits on the permit.
Ultrafine particles of Co-P were synthesized by direct ball milling of Co and P powders and also investigated as a reversible hydrogen storage electrode material. The electrochemical results demonstrated that the reversible charge-discharge capacity of the Co-P electrode can reach more than 300mAh/g. In addition, the cycling ability and high rate capability of the Co-P electrode are excellent with only 5% capacity decay after 100 cycles at a high rate of 300mA/g. The temperature-programmed desorption measurements (TPD) of the Co-P electrode revealed that the charge and discharge reactions of the Co-P electrode proceeds predominantly through electrochemical hydrogen storage mechanism and the electrooxidation of cobalt contributes only a negligible part to the reversible electrochemical capacity. (author)
This contribution describes our research and development efforts towards the demonstration of a light-weight, low-cost 12 V/20 Ah electrically rechargeable Zn/air battery. We successfully developed electrodes having active areas of up to 200 cm{sup 2}. Deep discharge cycles at different currents as well as current-voltage curves are reported for a 10 cell Zn/air battery (serial connection) with a rated capacity of 20 Ah. Based on the discharge cycle at a power of 19 W, and the weight of the battery, a specific energy of more than 90 Wh/kg could be evaluated for the whole system. (author) 4 figs., 1 tab., 5 refs.
The effect of a sawtooth crash on the radial distribution of the slowing down fusion product tritons and on beams ions, is examined with measurements of the 2.5 MeV and 14 MeV neutron emission line-integrals before and after sawtooth crashes. In deuterium discharges, the 14 MeV neutron production was wholly attributable to burnup of the 1 MeV fusion product tritons from d-d fusion. The local emissivity of 14 MeV neutrons, and hence of the profile of thermalizing tritons, is shown to be only weakly affected by crashes in the discharges studied. This is in contradiction with the apparent behaviour of injected beam ions as deduced from a study of the considerable changes in local emissivity of the 2.5 MeV neutrons. Nevertheless, the behaviour of the fusion product tritons is consistent with the scaling of the beam injected deuterium. 1 ref., 6 figs.
The homogeneity of a helium dielectric barrier discharge, working at atmospheric pressure and containing oxygen as contaminant, is assessed by mapping the spatial distribution of oxygen metastable atoms in relation to the uniformity of surface properties. Tunable diode laser absorption spectroscopy is used to monitor the time evolution of the absorption coefficient corresponding to the oxygen metastable atoms on the 35S2 level, as a function of the laser absorbing path, whereas bi-dimensional Abel transform is used to obtain local information on the space distribution of the metastable atoms in the discharge. The radial distribution of the surface properties is investigated using atomic force microscopy, contact angle measurement and X-ray photoelectron spectroscopy. The results show that ...
The Formula Not Shown system of Formula Not Shown was first observed in auroral emissions by Meinel in 1950. Although the Formula Not Shown band system has been reinvestigated since this first spectral study, no laboratory spectrum of the (2,1) vibronic band has been obtained. We have recently built a continuous-wave cavity ringdown spectrometer, and as a first test of this spectrometer we observed the (2,1) band of Formula Not Shown in a positive column discharge cell. Many lines of the first positive band system of Formula Not Shown were also identified during the process of assigning this spectrum. The relative intensities of the Formula Not Shown and Formula Not Shown bands were found to change with discharge cell pressure, and so each spectral region was observed at two pressures to a...
Major forecast errors on the background error covariance from initial conditions, atmospheric forcing, model open boundary conditions, and the river discharges are examined in a coastal model of northern South China Sea. The analysis of background error covariance matrix produced by model ensemble shows that the perturbations of the initial conditions and atmospheric forcing play major roles in producing and maintaining the amplitude of ensemble spread except for the sea surface height (SSH) field. The perturbation of model open boundary conditions can influence ensemble spread of all variables and covariance between temperature and velocity or between temperature and SSH. The perturbation of river discharge mainly affects the covariance of salinity in river estuary. A data assimilation ex...
The interscalenic block technique is widely used for ambulatory shoulder surgery despite a substantial number of failures and adverse effects. We prospectively evaluated satisfaction in 40 consecutive patients who underwent open Bankart repair under a single general anesthesic performed in an ambulatory care unit. The mean age of the patients was 23 years. There were 29 men and 11 women. Patients were evaluated postoperatively with a visual analog scale of pain (in the recovery room, at the time of discharge, and the day after and 1 week after surgery) via a home assessment questionnaire that included the following: effectiveness of oral pain medication, ability to perform activities of daily life, and overall satisfaction. One patient failed to be discharged because of a feeling of faintn...
A study on the distribution of "1"3"7Cs in coastal waters up to a distance of 15 km was undertaken for a decade (1995-2004) and observed that the activity has reduced by 15-20 fold. Statistical and trend analysis was carried out to resolve the contribution of different facilities at a distance of 5 km (north and south) from the discharge point by log normal probability analysis and found that at 5 km south, the median value of "1"3"7Cs due to TAPS and FRP discharges were 3.7 mBq/l and 1.50 mBq/l respectively. The observed levels of "1"3"7Cs are of no consequences from the point of view of dose to members of the public. (author)
Much attention is being paid to electric vehicles from environmental standpoints. One disadvantage of the electric vehicle is that its operative range is short. A means to overcome this difficulty is to use a hybrid battery which consist of a energy battery and a power battery. A method to make it possible to calculate the discharge characteristics of the battery hybrid system taking into account the charging behavior from the energy battery to the power battery is presented. In the proposed method, first the output voltage and the output current of an equivalent battery, which is required for realizing the given operating pattern are calculated. Next, the conduction ratio of the main chopper and the equivalent discharge of electric charge of each battery are calculated. These calculated data are used to calculate the operating range.
Plasma erosion craters caused by electrical discharges on the surface of materials are important features of the erosion processes resulting in the degradation of electrodes. In the present work, electrical discharges were produced on a bi-metallic Ni/Cu multilayered surface. By means of dual beam techniques, coupling a focused ion beam (FIB) and a scanning electron microscope (SEM), not only the surface but also the sub-surface structure of the craters were investigated. Using the combination of SEM, FIB and STEM-EDX, a complete three-dimensional investigation of the craters were carried out. The analysis of the microstructure modifications as a function of depth enabled to determine the field of interaction between the plasma and the material. (orig.)
The natural gas industry has proposed an increase in the DOE gas R&D budget from about $100 million to about $250 million per year for each of the next 10 years. The proposal includes four programs: natural gas supplies, fuel cells, natural gas vehicles and stationary combustion systems. This paper is a qualitative assessment of the gas industry proposal and recommends a natural gas R&D strategy for the DOE. The methodology is a conceptual framework based on an analysis of market failures and the energy policy objectives of the DOE`s (1991) National Energy Strategy. This framework would assist the DOE in constructing an R&D portfolio that achieves energy policy objectives. The natural gas supply program is recommended to the extent that it contributes to energy price stability. Stationary combustion programs are supported on ...
Prepared to make housing project managers, maintenance engineering staff, and designers and architects of HUD - assisted and HUD - insured housing projects and mobile home parks aware of their responsibilities under the Natural Gas Pipeline Safety Act, this handbook provides technical guidance for the reduction of gas leaks and the handling of gas leak incidents in residential areas. The hazards of natural gas, concern over gas safety in residential areas, applicable codes and standards, and sources of information and help are reviewed, along with maintenance and engineering considerations relating to gas pipe failures, the detection of gas leaks, appliance servicing, and pipe installation, repair, and replacement. Housing management considerations are also examined, with attention to recordkeeping and reporting, emergency contingency ...
Gas Supplies of Interstate Natural Gas Pipeline Companies 1987 was prepared by the Reserves and Natural Gas Division, Office of Oil and Gas, Energy Information Administration (EIA). The publication provides information on the total reserves, production, and deliverability capabilities of the 87 interstate pipeline companies required to file the Federal Energy Regulatory Commission (FERC) Form 15, ''Interstate Pipeline's Annual Report of Gas Supply.'' This publication is the 25th in a series of annual reports on the total gas supplies of interstate pipeline companies since the inception of individual company reports to the Federal Power Commission (FPC) in 1964 for report year 1963. This publication provides information on the interstate pipeline companies' supply of natural gas during ...
The corrosion behavior of 304 stainless steel was characterized with cyclic voltammetry in a eutectic Li/K and Li/Na carbonate melt under anode and cathode gas of the molten-carbonate fuel cell (MCFC). The corrosion rate of 304 steel was determined in four different environments of the MCFC with electrochemical methods and from cross-sectional analysis of corrosion layers. These four environments were open-circuit and MCFC-load conditions both under anode and cathode gas. At open-circuit conditions corrosion was more severe under the oxidizing cathode gas then under the reducing anode gas. On the contrary, at load conditions corrosion was more severe under anode than under cathode gas. The anodic polarization under anode gas enhances corrosion, whereas the high anodic polarization under cathode gas leads to anodic protection. Corrosion ...
Full text: Chemical-technology approaches allowing to intensification the prevention processes of gas hydrates formation at motion of gas-liquid stream of natural gas in system natural gas well - gas wire have been worked up. Technological regimes of treatment of gas stream have been determined. Linear correlation dependences inhibitor electrolytes contained hydrated ions with different ion radii and charges of subgroups of alkali elements with one - type electron configuration were obtained. Important physico-chemical parameters of electrolytes have been determined: activity; coefficients of activity, viscosity, diffusion; density; heat capacity; heat conductivity; surface tension and freezing-point. The features of continuous influence of inhibitory factors on process of gas flow at low temperatures and relatively high pressure differences ...
The passive continental margin in the northern South China Sea is a weakly active area. It has been found to be favorable for large gas field development and also to be profitable for gas hydrate. The active faults, diapir structure, slump deposits, faults break of slopes, gas chimneys and sandstone of submarine fan, control the concentration of gas hydrate. Gas chimneys are widely distributed in the northern South China Sea. They supply the pathway for migration of deeper gas to gas hydrate stability zones especially in the basin of tectonic inactive zone. This paper discussed the geological structures of gas hydrate occurrence in gas fields and presented a detailed analysis of gas chimneys within the northern slope of the South China Sea. The paper described the geological ...
Gas contaminated with at least one noxious component, such as SO/sub 2/, HF or NOx, is scrubbed with a clear, calcium-containing, initially-basic washing liquid which also comprises the anion of a strong inorganic acid, that of a polybasic carboxylic acid and, optionally, that of a monobasic carboxylic acid. Apparatus is provided for scrubbing the gas, oxidizing produced calcium bisulfite to calcium sulfate, separating out and removing solids, and recirculating clarified liquid for scrubbing contaminated gas.
The Rayleigh scattering length has been calculated for rare-gas liquids in the ultraviolet for the frequencies at which they luminesce. The calculations are based on the measured dielectric constants in the gas phase, except in the case of xenon for which measurements are available in the liquid. The scattering length mayplace constraints on the design of some large-scale detectors, using uv luminescence, being proposed to observe solar neutrinos and dark matter. Rayleigh scattering in mixtures of rare-gas mixtures is also discussed.
The fission gas xenon bonded in bubbles, in pore, and in the lattice of mixed carbide fuels is measured by electron-probe microanalysis. Radial xenon distribution and release curves are determined and are calibrated by gas chromatography of the bonded fission gas and by burnup analysis in the respective pin sections of the irradiation experiments FR2 6A and 6C, Mol 11/K 2, and DFR 330/1. The results are correlated to the microstructure of the fuel, bonding medium, temperature, and burnup. (Auth.).
Analysis of the coke gas combustion porcess is presented. Standard kinetic relationships were utilized. Calculations were performed for coke gas with high and low content of H/sub 2/ and for blasting air 20 and 100/sup 0/C. Temperature relationships, composition of gas combustion products and release of nitrogen oxides were determined. Results are analyzed which will make it possible to control the composition of combustion products.
This thesis dealt with the metal-organic gas phase epitaxy with nitrogen as carrier gas. For this first by means of three-dimensional modelings of the epitaxy process the influence of the carrier gas on the processes was explained. The optimization of the growth parameter for the whole light-emitting-diode structure in double-hetero arrangement resulted that an a temperature of 770 C and a V/ III-ratio of 150 layers with a high crystal quality could be reached.
Plasma with a gas temperature below room temperature is not yet fully understood although it is expected to be an attractive tool for applications to material processing. In the present work, gas-temperature-dependent generation of a cryoplasma jet was studied. So far, we have generated a helium cryoplasma jet (296-5 K) under atmospheric pressure. At gas temperatures below 20 K, the helium excimer, He2, was observed clearly from by optical emission spectroscopy.
The gas composition of recent thermal waters is in perfect conformity with their geologic-tectonic positions. The composition of gas-liquid inclusions in the basic-hyperbasic xenoliths of basaltoid lavas depends on the depth from which xenoliths are supplied. (The depth is determined by using the methods of geological thermobarometers). By comparing available data the conclusion was drawn that the gas compositions of thermal waters reflect the depth of generation of deep fluid which heats them and depends on the penetration depth of the fluid-conducting fissure zones.
Spark ignition internal combustion engines perform satisfactorily when the fueled with biomass producer gas from a fluidized bed gasifier. Although power output is reduced compared to natural gas levels, full power recovery can be achieved with a relatively low level of supercharging. Important considerations are an adequate fuel delivery system and adquate gas cleaning. ref.
... harassment, incidental to construction and operation of an offshore liquefied natural gas (LNG) facility. Under the Marine Mammal Protection ... ...
The primary objective of this study is to assess the oil and gas potential of the West Siberian Basin of Russia. The study does not analyze the costs or technology necessary to achieve the estimates of the ultimate recoverable oil and gas. This study uses reservoir data to estimate recoverable oil and gas quantities which were aggregated to the field level. Field totals were summed to a basin total for discovered fields. An estimate of undiscovered oil and gas, from work of the US Geological Survey (USGS), was added to give a total basin resource volume. Recent production decline points out Russia`s need to continue development of its discovered recoverable oil and gas. Continued exploration is required to discover additional oil and gas that remains undiscovered in the basin.
Details of a 1 day conference designed to create more efficient interactions between the gas supply and electricity systems in Ontario and new models for gas supply and the electricity system were presented. Market efficiency, generators' perspectives on critical gas issues, an overview of the North American gas and an outline of issues concerning Ontario were discussed. A natural gas industry forecast and issues concerning marketers and producers were presented. The terms on which gas is bought and sold were discussed. Regulatory tools, cost allocation and issues relating to unbundling were also presented. Infrastructure needs were reviewed, as well as basic market structures. It was suggested that appropriate commercial service options need to be developed and approved, including cross-utility services.
The Department of Energy has proposed a rulemaking process to set minimum standards for the efficiency of gas ranges under the National Appliance Energy Conservation Act (NAECA). The Gas Research Institute is compiling information on annual household range gas usage in order to prepare a response to the proposed rulemaking. The data base from the Northern Illinois Gas residential load study provides recent information (data taken from 1990 through 1992) over a comprehensive study of household types and appliance and user characteristics (150 variables noted for each household). The stated Objective is to study the Northern Illinois Gas residential load study data base and to evaluate its effectiveness in predicting annual household gas usage.
Research was performed to assess the feasibility of barrier membrane substances, for use within mining or associated high risk environments, in restricting the diffusion transport of radon gas quantities. Specific tests were conducted to determine permeability parameters of a variety of membrane materials with reference to radon flow capabilities. Tests were conducted both within laboratory and in-situ emanation environments where concentrations and diffusion flows of radon gas were known to exist. Equilibrium radon gas concentrations were monitored in initially radon-free chambers adjacent to gas sources, but separated by specified membrane substances. Membrane barrier effectiveness was demonstrated to result in reduced emanation concentrations of radon gas within the sampling chamber atmosphere. Minimum gas concentrations were evidenced where the barrier ...
The light gain due to S/sub 2/ molecules in a supersonically cooled gas mixture is calculated. The S/sub 2/ molecules formed due to the recombination of the sulfur atoms, and the combustion gas mixture was preheated in a precombustion chamber. Optimal gas flow and nozzle parameters are found which correspond to the highest possible light gain using Cs/sub 2/-Ar and S/sub 2/-Ar gas mixtures. The steady state gas flow in the nozzle was calculated, taking into account the chemical reactions in the one-dimensional approximation. It is shown that the maximum gain values vary in the 0.0001-0.002 range for gas pressures in the precombustion chamber in the range 10-100 atm. The optimal initial relative concentration of Cs/sub 2/ molecules and S/sub 2/ molecules are given. 32 references.
The use of natural gas in China is still relatively immature, as gas production only supplies a low percentage of the domestic energy system. In contrast, Chinese economy mainly relies on coal with a 67% share of the total primary energy supply. The environmental impact from this high coal dependence is significant and planners have sought for cleaner energy sources. Natural gas is both cleaner and generally more efficient than coal and gas consumption is rising quickly due to these facts. The growth tendency indicates that natural gas will become an important substitution for coal in some parts of the Chinese primary energy consumption. To quantify this tendency, this paper uses a system dynamics model to create a possible outlook. The results show that the gas consumption in China will c...
Biomass gasification provides the potential to efficiently and economically produce a renewable source of a clean gaseous fuel suitable for power generation or synthesis gas (syngas) applications. An important side benefit of the use of biomass is the effective minimization of the primary greenhouse gas, carbon dioxide (CO{sub 2}), by providing a means to close-loop the CO{sub 2} cycle. However, high molecular weight hydrocarbon constituents (tar) in the product gas from gasification can complicate the downstream uses of the gas. This paper discusses both the development of a low cost, disposable catalyst system that can eliminate these heavy hydrocarbons from the gas and the use of the catalyst in conjunction with the Battelle high-throughput gasification process for power generation and synthesis applications. (author)
The presence of an extraneous light gas must be taken into account in consideration of centrifugal separation of uranium isotopes, when there is inevitable leakage of such a gas through the gas sealant and/or leaking in from the atmosphere. Consideration is first given to the influence of the presence of the light gas on the maximum separative power. Then the basic equation for isotope separation containing a light gas is derived from Hirschfelder's diffusion equations. This equation is solved and the separative performance is expressed in terms of the shape factor and reflux parameter. The formulas for expressing the flow configurations of the gases are obtained for a simple model in which inflow and outflow prevail throughout the centrifuge. The corresponding equation for a model in which the gases flow in two concentric thin streams is also derived. It is concluded that the ...
A patent is claimed for a process by which a low-hydrogen gas containing at least 90 percent by volume of methane which is suited for natural gas substitution is produced by transformation of vaporizable hydrocarbons with the aid of steam in the presence of a catalyst containing nickel, at temperatures of 350 to 600/sup 0/C and at increased pressure. Hydrocarbons and steam are supplied to the reaction in mixed form with recycle product gas. Per kilogramme of hydrocarbons to be converted in the high btu gas reactor, less than 1 kilogramme of fresh steam is needed. High btu gas is fed back from the high btu gas reactor to the input end of the same via a gas cycle comprising a cooler, a carbon dioxide absorption device, and a saturator. Between the carbon dioxide absorption device and the saturator a product gas is branched ...
The performance of the gas-jet transport system coupled to the RIKEN gas-filled recoil ion separator GARIS was investigated using 255No produced in the 238U(22Ne, 5n)255No reaction. Alpha particles of 255No separated with GARIS and transported by the gas-jet system were measured with a rotating wheel apparatus for ? spectrometry under low background condition. The high gas-jet efficiencies of about 75% were independent of the recoil ranges of 255No in the gas-jet chamber. The present results suggest that the GARIS/gas-jet system is a promising tool for the next-generation superheavy element chemistry: (1) the background radioactivities of unwanted reaction products are strongly suppressed, (2) the intense beam is absent in the gas-jet chamber and hence the high gas-jet efficiency is achieved, and (3) the beam-free ...
The purpose of this study is to identify the radiative heat transfer augmentation by a coaxial cylinder introduced in the infinite cylindrical pipe enclosing a participating gas. The gas is either a mixture of water vapor and carbon dioxide or gray. The gas is assumed to be homogeneous at a constant temperature, and has a refractive index of unity. All of the surfaces are opaque and gray, diffusely emitting and reflecting at a constant temperature. The effect of system diameter, diameter ratio, wall emittances, gas and surface temperatures, mixture component on heat transfer augmentation are studied by using the zone method with participating gas radiative properties evaluated from the weighted sum of gray gases model. From the radiative equilibrium condition, the installed wall temperature is formulated and calculated by the iteration method. If the medium is a gray ...
Visible smoke of exhaust gas from iron ore sintering plants spoil the scenery around the works. In this paper, the mechanism of formation of visible smoke is discussed by detailed analysis of the exhaust gas components and dust in the Oita No. 1 sintering plant. The main substance of visible smoke was mist condensing in the air during the cooling of exhaust gas that contained 0.1 ppm of sulfuric acid. Sulfuric acid is considered to raise the dew point and so facilitate mist condensation, and to lower the vaporization of visible mist containing sulfuric acid solution. Dust in the exhaust gas is also considered to act as nucleation sites for mist condensation. This proposed mechanism was confirmed by the test remixing SOx-rich gas with desulfurization gas in the Nagoya No. 3 sintering plant. Long trails of visible smoke were observed by remixing SOx-rich ...
The Guarantee Outline presents the technical demands of design and contents of assessment for radiation hardening in satellite engineering in China. It includes the basis of design in space environment of polar orbit, the contents of design for general radiation hardening, the requirements and assessments of the single-board computer, the requirements of design for circuits (including hardware and software), the choices and assessments for devices, and the primary stipulations for the requirements of design and assessments against the phenomenon of charge and discharge.