WorldWideScience

Sample records for high critical gas

  1. A Study of the Critical Nozzle for Flow Rate Measurement of High-Pressure Hydrogen Gas

    Institute of Scientific and Technical Information of China (English)

    H.D.Kim; J.H.Lee; K.A.Park; T.Setoguchi; S.Matsuo

    2007-01-01

    The mass flow rate measurement using a critical nozzle shows the validity of the inviscid theory, indicating that the discharge coefficient increases and approaches unity as the Reynolds number increases under the ideal gas law.However, when the critical nozzle measures the mass flow rate of a real gas such as hydrogen at a pressure of hundreds bar, the discharge coefficient exceeds unity, and the real gas effects should be taken into account. The present study aims at investigating the flow features of the critical nozzle using high-pressured hydrogen gas. The axisymmetric, compressible Navier-Stokes computation is employed to simulate the critical nozzle flow, and a fully implicit finite volume method is used to discretize the governing equation system. The real gas effects are simulated to consider the intermolecular forces, which account for the possibility of liquefying hydrogen gas. The computational results are compared with past experimental data. It has been found that the coefficient of discharge for real gas can be corrected properly below unity adopting the real gas assumption.

  2. Prediction calculations and experiments for the first criticality of the 10 MW High Temperature Gas-cooled Reactor-Test Module

    Energy Technology Data Exchange (ETDEWEB)

    Jing Xingqing E-mail: jingxq@d103.inet.tsinghua.edu.cn; Xu Xiaolin; Yang Yongwei; Qu Ronghong

    2002-10-01

    The 10 MW High Temperature Gas-cooled Reactor-Test Module (HTR-10) is a pebble bed experimental reactor built by the Institute of Nuclear Energy Technology (INET), Tsinghua University. This paper introduces the first critical prediction calculations and the experiments for the HTR-10. The German VSOP neutronics code is used for the prediction calculations of the first loading. The characteristics of pebble-bed high temperature gas-cooled reactors are taken into account, including the double heterogeneity of the fuel element, the buckling feedback of the spectrum calculation, the effect of the mixture of fuel elements and graphite balls, and the correction of the diffusion coefficients in the upper cavity based on transport theory. Also considered are the effects of impurities in the fuel elements, in the graphite balls and in the reflector graphite on the reactivity. The number of fuel elements and graphite balls in the initial core is predicted to provide reference for the first criticality experiment. The critical experiment adopts a method of extrapolating to approach criticality. The first criticality was attained on December 1, 2000. The first criticality experiment shows that the predicted critical number of the fuel elements and graphite balls is in close agreement with the experimental results. Their relative error is less than 1.0%, implying the physical predictions and the results of the criticality experiment are much beyond expectations.

  3. High enthalpy gas dynamics

    CERN Document Server

    Rathakrishnan, Ethirajan

    2014-01-01

    This is an introductory level textbook which explains the elements of high temperature and high-speed gas dynamics. written in a clear and easy to follow style, the author covers all the latest developments in the field including basic thermodynamic principles, compressible flow regimes and waves propagation in one volume covers theoretical modeling of High Enthalpy Flows, with particular focus on problems in internal and external gas-dynamic flows, of interest in the fields of rockets propulsion and hypersonic aerodynamics High enthalpy gas dynamics is a compulsory course for aerospace engine

  4. Anomalous waves in gas-liquid mixtures near gas critical point in Gardner equation approximation

    Science.gov (United States)

    Gasenko, V. G.

    2016-10-01

    The waves in a bubbled incompressible liquid with Van der Waals gas in a bubbles being near critical points is considered in a frame of Gardner equation. It is shown that both coefficients on quadratic and cubic nonlinear terms in Gardner equation change the sign near gas critical point and it results the anomalous waves: negative and limited solitons, kinks, antikinks and breathers. The dynamics and interactions of these waves was studied numerically by high accuracy Fourier methods with periodically boundary conditions. In particular it is revealed that limited solitons always arise from initial distribution with a few identical soliton's pair and stand stable in their form after numerous interactions.

  5. Constraining the abundance of high emitters is critical to mitigating the effect of abandoned oil and gas wells on methane emissions

    Science.gov (United States)

    Townsend-Small, A.; Ferrara, T.; Fries, A. E.

    2016-12-01

    Recent studies have suggested that methane inventories may underrepresent emissions from the oil and gas supply chain, and this has led to an effort by several groups to assess whether abandoned wells are a significant source. Our work has shown that unplugged wells are a larger source than plugged wells, and that a small percentage of unplugged wells likely make up the majority of emissions. Preliminary work also suggests that the oldest oil and gas producing region, the Appalachian Basin, has the largest emitters. However, many of these wells are over 100 years old and state databases lack accurate plugging and location data. Our current work is focused on determining the proportion of high emitters among abandoned wells in the Appalachian basin of Ohio. We are also making component-level measurements of conventional oil and gas wells on federal land for comparison. Our methods include analysis of gas composition to identify the relative contributions of biogenic and thermogenic methane to emissions. Identifying the location and emission rate of abandoned wells will not only mitigate a potential regionally important methane source, but will also help prevent interactions of these older wells with new drilling for shale gas as well as groundwater.

  6. [High Pressure Gas Tanks

    Science.gov (United States)

    Quintana, Rolando

    2002-01-01

    Four high-pressure gas tanks, the basis of this study, were especially made by a private contractor and tested before being delivered to NASA Kennedy Space Center. In order to insure 100% reliability of each individual tank the staff at KSC decided to again submit the four tanks under more rigorous tests. These tests were conducted during a period from April 10 through May 8 at KSC. This application further validates the predictive safety model for accident prevention and system failure in the testing of four high-pressure gas tanks at Kennedy Space Center, called Continuous Hazard Tracking and Failure Prediction Methodology (CHTFPM). It is apparent from the variety of barriers available for a hazard control that some barriers will be more successful than others in providing protection. In order to complete the Barrier Analysis of the system, a Task Analysis and a Biomechanical Study were performed to establish the relationship between the degree of biomechanical non-conformities and the anomalies found within the system on particular joints of the body. This relationship was possible to obtain by conducting a Regression Analysis to the previously generated data. From the information derived the body segment with the lowest percentage of non-conformities was the neck flexion with 46.7%. Intense analysis of the system was conducted including Preliminary Hazard Analysis (PHA), Failure Mode and Effect Analysis (FMEA), and Barrier Analysis. These analyses resulted in the identification of occurrences of conditions, which may be becoming hazardous in the given system. These conditions, known as dendritics, may become hazards and could result in an accident, system malfunction, or unacceptable risk conditions. A total of 56 possible dendritics were identified. Work sampling was performed to observe the occurrence each dendritic. The out of control points generated from a Weighted c control chart along with a Pareto analysis indicate that the dendritics "Personnel not

  7. High Energy Gas Fracturing Test

    Energy Technology Data Exchange (ETDEWEB)

    Schulte, R.

    2001-02-27

    The Rocky Mountain Oilfield Testing Center (RMOTC) has recently completed two tests of a high-energy gas fracturing system being developed by Western Technologies of Crossville, Tennessee. The tests involved the use of two active wells located at the Naval Petroleum Reserve No. 3 (NPR-3), thirty-five miles north of Casper, Wyoming (See Figure 1). During the testing process the delivery and operational system was enhanced by RMOTC, Western Technologies, and commercial wireline subcontractors. RMOTC has assisted an industrial client in developing their technology for high energy gas fracturing to a commercial level. The modifications and improvements implemented during the technology testing process are instrumental in all field testing efforts at RMOTC. The importance of well selection can also be critical in demonstrating the success of the technology. To date, significant increases in well productivity have been clearly proven in well 63-TPX-10. Gross fluid production was initially raised by a factor of three. Final production rates increased by a factor of six with the use of a larger submersible pump. Well productivity (bbls of fluid per foot of drawdown) increased by a factor of 15 to 20. The above results assume that no mechanical damage has occurred to the casing or cast iron bridge plug which could allow well production from the Tensleep ''B'' sand. In the case of well 61-A-3, a six-fold increase in total fluid production was seen. Unfortunately, the increase is clouded by the water injection into the well that was necessary to have a positive fluid head on the propellant tool. No significant increase in oil production was seen. The tools which were retrieved from both 63-TPX-10 and 61-A-3 indicated a large amount of energy, similar to high gram perforating, had been expended downhole upon the formation face.

  8. Critical-like behavior in a lattice gas model

    CERN Document Server

    Wieloch, A; Lukasik, J; Pawlowski, P; Pietrzak, T; Trautmann, W

    2010-01-01

    ALADIN multifragmentation data show features characteristic of a critical behavior, which are very well reproduced by a bond percolation model. This suggests, in the context of the lattice gas model, that fragments are formed at nearly normal nuclear densities and temperatures corresponding to the Kertesz line. Calculations performed with a lattice gas model have shown that similarly good reproduction of the data can also be achieved at lower densities, particularly in the liquid-gas coexistence region.

  9. Microscopic structure and gas-gas critical line of the Ar-water system

    Energy Technology Data Exchange (ETDEWEB)

    Ricci, M.A. [Dipartimento di Fisica ' E. Amaldi' , Universita degli Studi ' Roma Tre' , Via della Vasca Navale 84, 00146 Rome (Italy)]. E-mail: riccim@fis.uniroma3.it; Mancinelli, R. [Dipartimento di Fisica ' E. Amaldi' , Universita degli Studi ' Roma Tre' , Via della Vasca Navale 84, 00146 Rome (Italy); Lu Russo, M. [ESRF, European Synchrotron Radiation Facility, 6 rue Jules Horowitz, BP 220, 38043 Grenoble (France); Botti, A. [Dipartimento di Fisica ' E. Amaldi' , Universita degli Studi ' Roma Tre' , Via della Vasca Navale 84, 00146 Rome (Italy); Bruni, F. [Dipartimento di Fisica ' E. Amaldi' , Universita degli Studi ' Roma Tre' , Via della Vasca Navale 84, 00146 Rome (Italy); Soper, A.K. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire, OX11 0QX (United Kingdom)

    2006-11-15

    The dependence of the derivative of the gas-gas critical temperature on the microscopic structure of a mixture is analyzed using neutron diffraction on the Ar-water system at two solute concentrations. At low Ar concentration the critical line departs from the critical point of the solvent with negative derivative: at a microscopic level this corresponds to a repulsive solute-solvent interaction, keeping Ar atoms outside the first water-water neighboring shell. As the solute concentration increases at constant temperature and pressure, the critical temperature goes through a minimum and eventually Ar atoms enter the first neighbor water shell. At this point, no H-bonding between water molecules is visible.

  10. Critical evaluation of ex vivo restoration of carious equine maxillary cheek teeth infundibulae following high-pressure gas and micro-particle abrasion.

    Science.gov (United States)

    Dixon, P M; Savill, D; Horbyl, A; Reardon, R J M; Liuti, T

    2014-06-01

    Infundibular caries of the equine maxillary cheek teeth is an important disorder that can lead to dental fracture or apical infection. Treatment by removing food debris and carious dental tissue from affected infundibulae using high-pressure abrasion with aluminium hydroxide micro-particles, followed by filling the cleaned defect with endodontic restorative materials is a recommended treatment. However, although anecdotally considered a successful treatment option, there is currently no objective evidence to support this claim. Forty maxillary cheek teeth (CT) that contained 55 infundibulae with caries (mainly grade 2) were extracted post-mortem from 21 adult horses. Five of the CT were sectioned prior to treatment to facilitate visual examination of the carious infundibulae. The remaining carious infundibulae were cleaned using high-pressure abrasion with aluminium hydroxide particles and five CT were sectioned to assess the efficacy of this cleaning process. The remaining 30 CT containing 39 carious infundibulae were then filled with a composite restorative material. The efficacy of this restoration was assessed by computed tomography imaging followed by direct visual examination after sectioning the teeth. Only 46% (18/39) of restored infundibulae, all with shallow (mean 9.6 mm deep) defects, were fully cleaned of food debris and carious material, and filled with restorative material to their full depth. Of these 18, 11 had peripheral defects around the restoration, leaving just 18% (7/39) of restorations without any gross defects. The remaining 54% (21/39) of infundibulae (mean depth of infundibular caries defect, 18.3 mm) still contained food debris and/or carious material in more apical locations, with infundibulae with the deepest caries defects being the least effectively cleaned. The findings of this study indicate that high-pressure micro-particle abrasion is only effective in cleaning food debris from shallow, carious CT infundibulae and consequently

  11. Critical review of mercury chemistry in flue gas.

    Energy Technology Data Exchange (ETDEWEB)

    Mendelsohn, M. H.; Livengood, C. D.

    2006-11-27

    Mercury (Hg) and its compounds have long been recognized as potentially hazardous to human health and the environment. Many man-made sources of mercury have been reduced in recent years through process changes and control measures. However, emissions of mercury from coal-fired power plants, while exceedingly dilute by the usual pollution standards, still constitute a major source when considered in the aggregate. Concerns over those emissions and the prospect of impending emissions regulations have led to a wide range of research projects dealing with the measurement and control of mercury in flue gas. This work has made considerable progress in improving the understanding of mercury emissions and their behavior, but inconsistencies and unexpected results have also shown that a better understanding of mercury chemistry is needed. To develop a more complete understanding of where additional research on mercury chemistry is needed, the U.S. Department of Energy (DOE) asked Argonne National Laboratory (Argonne) to conduct a critical review of the available information as reported in the technical literature. The objectives were to summarize the current state of the art of chemistry knowledge, identify significant knowledge gaps, and recommend future research to resolve those gaps. An initial evaluation of potential review topics indicated that the scope of the review would need to be limited and focused on the most important topics relative to mercury control. To aid in this process, Argonne developed a brief survey that was circulated to researchers in the field who could help identify and prioritize the many aspects of the problem. The results of the survey were then used to design and guide a highly focused literature search that identified key papers for analysis. Each paper was reviewed, summarized, and evaluated for the relevance and quality of the information presented. The results of that work provided the basis for conclusions regarding the state of knowledge

  12. Gas-turbine critical research and advanced technology support project

    Science.gov (United States)

    Clark, J. S.; Lowell, C. E.; Niedzwiecki, R. W.; Nainiger, J. J.

    1979-01-01

    The technical progress made during the first 15 months of a planned 40-month project to provide a critical-technology data base for utility gas-turbine systems capable of burning coal-derived fuels is summarized. Tasks were included in the following areas: (1) combustion, to study the combustion of coal-derived fuels and conversion of fuel-bound nitrogen to NOx; (2) materials, to understand and prevent hot corrosion; and (3) system studies, to integrate and guide the other technologies. Significant progress was made.

  13. Gas Bearing Control for Safe Operation in Critical Speed Regions - Experimental Verification

    DEFF Research Database (Denmark)

    Theisen, Lukas R. S.; Niemann, Hans H.; Galeazzi, Roberto

    2015-01-01

    Gas bearings are popular for their high speed capabilities, low friction and clean operation, but require low clearances and suffer from poor damping properties. The poor damping properties cause high disturbance amplification near the natural frequencies. These become critical when the rotation...... supported by gas bearings to extend their operating range. Using H∞-design methods, active lubrication techniques are proposed to enhance the damping, which in turn reduces the vibrations to a desired safe level. The control design is validated experimentally on a laboratory test rig, and shown to allow...

  14. High potential recovery -- Gas repressurization

    Energy Technology Data Exchange (ETDEWEB)

    Madden, M.P.

    1998-05-01

    The objective of this project was to demonstrate that small independent oil producers can use existing gas injection technologies, scaled to their operations, to repressurize petroleum reservoirs and increase their economic oil production. This report gives background information for gas repressurization technologies, the results of workshops held to inform small independent producers about gas repressurization, and the results of four gas repressurization field demonstration projects. Much of the material in this report is based on annual reports (BDM-Oklahoma 1995, BDM-Oklahoma 1996, BDM-Oklahoma 1997), a report describing the results of the workshops (Olsen 1995), and the four final reports for the field demonstration projects which are reproduced in the Appendix. This project was designed to demonstrate that repressurization of reservoirs with gas (natural gas, enriched gas, nitrogen, flue gas, or air) can be used by small independent operators in selected reservoirs to increase production and/or decrease premature abandonment of the resource. The project excluded carbon dioxide because of other DOE-sponsored projects that address carbon dioxide processes directly. Two of the demonstration projects, one using flue gas and the other involving natural gas from a deeper coal zone, were both technical and economic successes. The two major lessons learned from the projects are the importance of (1) adequate infrastructure (piping, wells, compressors, etc.) and (2) adequate planning including testing compatibility between injected gases and fluids, and reservoir gases, fluids, and rocks.

  15. Molecular Gas at High Redshift

    CERN Document Server

    Solomon, P M

    2005-01-01

    The Early Universe Molecular Emission Line Galaxies (EMGs) are a population of galaxies with only 36 examples that hold great promise for the study of galaxy formation and evolution at high redshift. The classification, luminosity of molecular line emission, molecular mass, far-infrared (FIR) luminosity, star formation efficiency, morphology, and dynamical mass of the currently known sample are presented and discussed. The star formation rates derived from the FIR luminosity range from about 300 to 5000 M(sun)per year and the molecular mass from 4 x 10^9 to 1 x 10^{11} M(sun). At the lower end, these star formation rates, gas masses, and diameters are similar to those of local ultraluminous infrared galaxies, and represent starbursts in centrally concentrated disks, sometimes, but not always, associated with active galactic nuclei. The evidence for large (> 5 kpc) molecular disks is limited. Morphology and several high angular resolution images suggest that some EMGs are mergers with a massive molecular inter...

  16. Advanced materials for critical components in industrial gas turbines

    Energy Technology Data Exchange (ETDEWEB)

    Gibbons, T.B. (Div. of Materials Metrology, National Physical Lab., Teddington (United Kingdom))

    1992-06-01

    Combined-cycle plant for power production has advantages in terms of capital costs and flexibility compared to large power plants either nuclear of fossil-fired, used for base load. In combined-cycle plant the overall efficiency is highly dependent on the performance of the gas turbine and turbine entry temperatures of > 1200deg C will be required to obtain attractive levels of efficiency. Bearing in mind the need for reliability and longterm performance from components such as turbine blades, the challenge to the materials enginer is formidable. In this paper some of the recent developments in Ni - Cr-base alloys are described and the potential for advanced materials such as ceramics and intermetallics is briefly considered. Development in coating technology to provide effective thermal barriers and good resistance to aggressive environments are discussed. (orig./MM).

  17. Two critical issues in Langevin simulation of gas flows

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jun [James Weir Fluids Laboratory, Department of Mechanical and Aerospace Engineering, University of Strathclyde, Glasgow G1 1XJ, United Kingdom and State Key Laboratory of High Temperature Gas Dynamics, Institute of Mechanics, Chinese Academy of Sciences (China); Fan, Jing [State Key Laboratory of High Temperature Gas Dynamics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-12-09

    A stochastic algorithm based on the Langevin equation has been recently proposed to simulate rarefied gas flows. Compared with the direct simulation Monte Carlo (DSMC) method, the Langevin method is more efficient in simulating small Knudsen number flows. While it is well-known that the cell sizes and time steps should be smaller than the mean free path and the mean collision time, respectively, in DSMC simulations, the Langevin equation uses a drift term and a diffusion term to describe molecule movements, so no direct molecular collisions have to be modeled. This enables the Langevin simulation to proceed with a much larger time step than that in the DSMC method. Two critical issues in Langevin simulation are addressed in this paper. The first issue is how to reproduce the transport properties as that described by kinetic theory. Transport coefficients predicted by Langevin equation are obtained by using Green-Kubo formulae. The second issue is numerical scheme with boundary conditions. We present two schemes corresponding to small time step and large time step, respectively. For small time step, the scheme is similar to DSMC method as the update of positions and velocities are uncoupled; for large time step, we present an analytical solution of the hitting time, which is the crucial factor for accurate simulation. Velocity-Couette flow, thermal-Couette flow, Rayleigh-Bénard flow and wall-confined problem are simulated by using these two schemes. Our study shows that Langevin simulation is a promising tool to investigate small Knudsen number flows.

  18. High-rangeability ultrasonic gas flowmeter for monitoring flare gas.

    Science.gov (United States)

    Mylvaganam, K S

    1989-01-01

    A transit-time ultrasonic gas flowmeter for high-rangeability requirements, such as those encountered in flare-gas flow-metering, is presented. The concept of ray rescue angle for the orientation of the ultrasonic transducers in single-beam transit-time ultrasonic flowmeters is introduced to overcome the problem of ultrasonic beam drift in high-velocity flows. To overcome problems associated with noise at high velocities, a chirp signal is used. To preserve the accuracy of the meter at low velocities near zero flow, a combination of chirp and continuous-wave signals is used to interrogate the flow. Overall system performance is presented, based on results from extensive wind-tunnel tests.

  19. Technology characterization: high Btu gas transmission

    Energy Technology Data Exchange (ETDEWEB)

    None

    1977-04-01

    A technology characterization for high Btu gas transmission was prepared. The scope of work was confined to a literature review. The work was divided into four specific areas as follows: (1) a summary of pertinent information from the environmental report of the Great Lakes Gas Company for a 365-mile high pressure pipeline serving American Natural Gas Company's proposed lignite gasification plant in North Dakota; (2) statistical information concerning the operation of the existing United States natural gas transmission pipeline network; (3) a summary of pertinent information from the environmental impact statement of the United States Department of Interior for the proposed 1,619-mile Northern Border Pipeline from Morgan, Montana to Delmont, Pennsylvania; and (4) a summary of pertinent information from the environmental impact statement of the Federal Power Commission for a proposed El Paso Natural Gas Company 418-mile pipeline within the State of Texas which was to be constructed in response to the displacement of natural gas by Liquefied Natural Gas (LNG) importation on the East Coast.

  20. Gas and RRR distribution in high purity Niobium EB welded in Ultra-High Vacuum

    Science.gov (United States)

    Anakhov, S.; Singer, X.; Singer, W.; Wen, H.

    2006-05-01

    Electron beam (EB) welding in UHV (ultra-high vacuum, 10-5÷10-8 mbar) is applied in the standard fabrication of high gradient niobium superconducting radio frequency (SRF) cavities of TESLA design. The quality of EB welding is critical for cavity performance. Experimental data of gas content (H2, O2, N2) and RRR (residual resistivity ratio) measurements in niobium (Nb) welding seams are presented. EB welding in UHV conditions allow to preserve low gas content (1÷3 wt. ppm hydrogen and 5÷7 ppm oxygen and nitrogen), essential for high values of RRR — 350÷400 units. Gas content redistribution in the electron beam welded and heat affected region take place in the welding process. Correlation between gas solubility parameters, RRR and thermal conductivity are presented. Mechanisms of gas solubility in EB welding process are discussed.

  1. Gas drainage technology of high gas and thick coal seam

    Institute of Scientific and Technical Information of China (English)

    HE Tian-cai; LI Hai-gui; ZHANG Hai-jun

    2009-01-01

    Gas drainage in Jincheng Mining Group Co., Ltd. was introduced briefly and the importance of gas drainage in gas control was analyzed. Combined with coal-bed gas oc-currence and gas emission, the double system of gas drainage was optimized and a pro-gressive gas drainage model was experimented on. For guaranteed drainage, excavation and mining and realization of safety production and reasonable exploitation of gas in coal seams, many drainage methods were adopted to solve the gas problem of the working face.

  2. Third-order gas-liquid phase transition and the nature of Andrews critical point

    Directory of Open Access Journals (Sweden)

    Tian Ma

    2011-12-01

    Full Text Available The main objective of this article is to study the nature of the Andrews critical point in the gas-liquid transition in a physical-vapor transport (PVT system. A dynamical model, consistent with the van der Waals equation near the Andrews critical point, is derived. With this model, we deduce two physical parameters, which interact exactly at the Andrews critical point, and which dictate the dynamic transition behavior near the Andrews critical point. In particular, it is shown that 1 the gas-liquid co-existence curve can be extended beyond the Andrews critical point, and 2 the transition is first order before the critical point, second-order at the critical point, and third order beyond the Andrews critical point. This clearly explains why it is hard to observe the gas-liquid phase transition beyond the Andrews critical point. Furthermore, the analysis leads naturally the introduction of a general asymmetry principle of fluctuations and the preferred transition mechanism for a thermodynamic system. The theoretical results derived in this article are in agreement with the experimental results obtained in (K. Nishikawa and T. Morita, Fluid behavior at supercritical states studied by small-angle X-ray scattering, Journal of Supercritical Fluid, 13 (1998, pp. 143-148. Also, the derived second-order transition at the critical point is consistent with the result obtained in (M. Fisher, Specific heat of a gas near the critical point, Physical Review, 136:6A (1964, pp. A1599-A1604.

  3. Critical superfluid velocity in a trapped dipolar gas.

    Science.gov (United States)

    Wilson, Ryan M; Ronen, Shai; Bohn, John L

    2010-03-01

    We investigate the superfluid properties of a dipolar Bose-Einstein condensate (BEC) in a fully three-dimensional trap. Specifically, we estimate a superfluid critical velocity for this system by applying the Landau criterion to its discrete quasiparticle spectrum. We test this critical velocity by direct numerical simulation of condensate depletion as a blue-detuned laser moves through the condensate. In both cases, the presence of the roton in the spectrum serves to lower the critical velocity beyond a critical particle number. Since the shape of the dispersion, and hence the roton minimum, is tunable as a function of particle number, we thereby propose an experiment that can simultaneously measure the Landau critical velocity of a dipolar BEC and demonstrate the presence of the roton in this system.

  4. Measure Guideline: High Efficiency Natural Gas Furnaces

    Energy Technology Data Exchange (ETDEWEB)

    Brand, L.; Rose, W.

    2012-10-01

    This Measure Guideline covers installation of high-efficiency gas furnaces. Topics covered include when to install a high-efficiency gas furnace as a retrofit measure, how to identify and address risks, and the steps to be used in the selection and installation process. The guideline is written for Building America practitioners and HVAC contractors and installers. It includes a compilation of information provided by manufacturers, researchers, and the Department of Energy as well as recent research results from the Partnership for Advanced Residential Retrofit (PARR) Building America team.

  5. Measure Guideline. High Efficiency Natural Gas Furnaces

    Energy Technology Data Exchange (ETDEWEB)

    Brand, L. [Partnership for Advanced Residential Retrofit (PARR), Des Plaines, IL (United States); Rose, W. [Partnership for Advanced Residential Retrofit (PARR), Des Plaines, IL (United States)

    2012-10-01

    This measure guideline covers installation of high-efficiency gas furnaces, including: when to install a high-efficiency gas furnace as a retrofit measure; how to identify and address risks; and the steps to be used in the selection and installation process. The guideline is written for Building America practitioners and HVAC contractors and installers. It includes a compilation of information provided by manufacturers, researchers, and the Department of Energy as well as recent research results from the Partnership for Advanced Residential Retrofit (PARR) Building America team.

  6. High temperature gas-cooled reactor: gas turbine application study

    Energy Technology Data Exchange (ETDEWEB)

    1980-12-01

    The high-temperature capability of the High-Temperature Gas-Cooled Reactor (HTGR) is a distinguishing characteristic which has long been recognized as significant both within the US and within foreign nuclear energy programs. This high-temperature capability of the HTGR concept leads to increased efficiency in conventional applications and, in addition, makes possible a number of unique applications in both electrical generation and industrial process heat. In particular, coupling the HTGR nuclear heat source to the Brayton (gas turbine) Cycle offers significant potential benefits to operating utilities. This HTGR-GT Application Study documents the effort to evaluate the appropriateness of the HTGR-GT as an HTGR Lead Project. The scope of this effort included evaluation of the HTGR-GT technology, evaluation of potential HTGR-GT markets, assessment of the economics of commercial HTGR-GT plants, and evaluation of the program and expenditures necessary to establish HTGR-GT technology through the completion of the Lead Project.

  7. Susceptibility Measurements Near the He-3 Liquid-Gas Critical Point

    Science.gov (United States)

    Barmatz, Martin; Zhong, Fang; Hahn, Inseob

    2000-01-01

    An experiment is now being developed to measure both the linear susceptibility and specific heat at constant volume near the liquid-gas critical point of He-3 in a microgravity environment. An electrostriction technique for measuring susceptibility will be described. Initial electrostriction measurements were performed on the ground along the critical isochore in a 0.5 mm high measurement cell filled to within 0.1 % of the critical density. These measurements agreed with the susceptibility determined from pressure-density measurements along isotherms. The critical temperature, T(sub c), determined separately from specific heat and susceptibility measurements was self-consistent. Susceptibility measurements in the range t = T/T(sub c) - 1 > 10(exp -4)were fit to Chi(sup *)(sub T) = Gamma(sup +)t(exp -lambda)(1 + Gamma(sup +)(sub 1)t(sup delta). Best fit parameters for the asymptotic amplitude Gamma(sup +) and the first Wegner amplitude Gamma(sup +)(sub 1) will be presented and compared to previous measurements.

  8. Critical temperature of Bose-Einstein condensation for weakly interacting bose gas in a potential trap

    Institute of Scientific and Technical Information of China (English)

    YU; Xuecai; YE; Yutang; WU; Yunfeng; XIE; Kang; CHENG; Lin

    2005-01-01

    The critical temperature of Bose-Einstein condensation at minimum momentum state for weakly interacting Bose gases in a power-law potential and the deviation of the critical temperature from ideal bose gas are studied. The effect of interaction on the critical temperature is ascribed to the ratiao α/λc, where α is the scattering length for s wave and λc is de Broglie wavelength at critical temperature. As α/λc<<1/(2π)2, the interaction is negligible. The presented deviation of the critical temperature for three dimensional harmonic potential is well in agreement with recent measurement of critical temperature for 87Rb bose gas trapped in a harmonic well.

  9. Characterization of non equilibrium effects on high quality critical flows

    Energy Technology Data Exchange (ETDEWEB)

    Camelo, E.; Lemonnier, H.; Ochterbeck, J. [Commissariat a l Energie Atomique, Grenoble (France)] [and others

    1995-09-01

    The appropriate design of various pieces of safety equipment such as relief systems, relies on the accurate description of critical flow phenomena. Most of the systems of industrial interest are willing to be described by one-dimensional area-averaged models and a large fraction of them involves multi-component high gas quality flows. Within these circumstances, the flow is very likely to be of an annular dispersed nature and its description by two-fluid models requires various closure relations. Among the most sensitive closures, there is the interfacial area and the liquid entrained fraction. The critical flowrate depends tremendously on the accurate description of the non equilibrium which results from the correctness of the closure equations. In this study, two-component flows are emphasized and non equilibrium results mainly form the differences in the phase velocities. It is therefore of the utmost importance to have reliable data to characterize non equilibrium phenomena and to assess the validity of the closure models. A comprehensive description of air-water nozzle flows, with emphasis on the effect of the nozzle geometry, has been undertaken and some of the results are presented here which helps understanding the overall flow dynamics. Besides the critical flowrate, the presented material includes pressure profiles, droplet size and velocity, liquid film flowrate and liquid film thickness.

  10. The Evolution of High Temperature Gas Sensors.

    Energy Technology Data Exchange (ETDEWEB)

    Garzon, F. H. (Fernando H.); Brosha, E. L. (Eric L.); Mukundan, R. (Rangachary)

    2001-01-01

    Gas sensor technology based on high temperature solid electrolytes is maturing rapidly. Recent advances in metal oxide catalysis and thin film materials science has enabled the design of new electrochemical sensors. We have demonstrated prototype amperometric oxygen sensors, nernstian potentiometric oxygen sensors that operate in high sulfur environments, and hydrocarbon and carbon monoxide sensing mixed potentials sensors. Many of these devices exhibit part per million sensitivities, response times on the order of seconds and excellent long-term stability.

  11. Gas film disturbance characteristics analysis of high-speed and high-pressure dry gas seal

    Science.gov (United States)

    Chen, Yuan; Jiang, Jinbo; Peng, Xudong

    2016-08-01

    The dry gas seal(DGS) has been widely used in high parameters centrifugal compressor, but the intense vibrations of shafting, especially in high-speed condition, usually result in DGS's failure. So the DGS's ability of resisting outside interference has become a determining factor of the further development of centrifugal compressor. However, the systematic researches of which about gas film disturbance characteristics of high parameters DGS are very little. In order to study gas film disturbance characteristics of high-speed and high-pressure spiral groove dry gas seal(S-DGS) with a flexibly mounted stator, rotor axial runout and misalignment are taken into consideration, and the finite difference method and analytical method are used to analyze the influence of gas film thickness disturbance on sealing performance parameters, what's more, the effects of many key factors on gas film thickness disturbance are systematically investigated. The results show that, when sealed pressure is 10.1MPa and seal face average linear velocity is 107.3 m/s, gas film thickness disturbance has a significant effect on leakage rate, but has relatively litter effect on open force; Excessively large excitation amplitude or excessively high excitation frequency can lead to severe gas film thickness disturbance; And it is beneficial to assure a smaller gas film thickness disturbance when the stator material density is between 3.1 g/cm3 to 8.4 g/cm3; Ensuring sealing performance while minimizing support axial stiffness and support axial damping can help to improve dynamic tracking property of dry gas seal. The proposed research provides the instruction to optimize dynamic tracking property of the DGS.

  12. Gas dilution system using critical flow Venturi nozzles for generating primary trace-moisture standards in multiple gas species

    Science.gov (United States)

    Amano, Minami; Abe, Hisashi

    2017-02-01

    Gas dilution systems are commonly used to generate calibration gas mixtures for secondary gas standards. However, if a gas dilution system is used to generate gas mixtures for primary trace-moisture standards in multiple gas species, difficulty arises; flow control with relative stability of better than 0.009% is required although the relative uncertainty of the best gas flow meter to date is around 0.3%. In this study, we developed a novel gas dilution system using critical flow Venturi nozzles to address this problem. The developed dilution system can measure and control the flow rates of gases in the range of approximately 0.05 l min-1 to 7 l min-1 (when converted to those measured at 101 325 Pa and 273.15 K) with relative stability of better than 0.007%. Using the dilution system, we developed a magnetic suspension balance/diffusion-tube humidity generator capable of generating trace moisture in N2 in the range of approximately 10 nmol mol-1 to 5 µmol mol-1 in amount fraction. The accuracy of the generated trace-moisture standard was verified by measurement with cavity ring-down spectroscopy.

  13. Gas and RRR Distribution in High Purity Niobium EB Welded in Ultra-High Vacuum.

    OpenAIRE

    Anakhov, S.; Singer, X.; W. Singer; Wen, H.

    2006-01-01

    Electron beam (EB) welding in UHV (ultra-high vacuum, 10(-5) divided by 10(-8) mbar) is applied in the standard fabrication of high gradient niobium superconducting radio frequency (SRF) cavities of TESLA design. The quality of EB welding is critical for cavity performance. Experimental data of gas content (H-2, O-2, N-2) and RRR (residual resistivity ratio) measurements in niobium (Nb) welding seams are presented. EB welding in UHV conditions allow to preserve low gas content (1 divided by 3...

  14. High Energy Vibration for Gas Piping

    Science.gov (United States)

    Lee, Gary Y. H.; Chan, K. B.; Lee, Aylwin Y. S.; Jia, ShengXiang

    2017-07-01

    In September 2016, a gas compressor in offshore Sarawak has its rotor changed out. Prior to this change-out, pipe vibration study was carried-out by the project team to evaluate any potential high energy pipe vibration problems at the compressor’s existing relief valve downstream pipes due to process condition changes after rotor change out. This paper covers high frequency acoustic excitation (HFAE) vibration also known as acoustic induced vibration (AIV) study and discusses detailed methodologies as a companion to the Energy Institute Guidelines for the avoidance of vibration induced fatigue failure, which is a common industry practice to assess and mitigate for AIV induced fatigue failure. Such detailed theoretical studies can help to minimize or totally avoid physical pipe modification, leading to reduce offshore plant shutdown days to plant shutdowns only being required to accommodate gas compressor upgrades, reducing cost without compromising process safety.

  15. On the Interpretation of Near-Critical Gas-Liquid Heat Capacities

    Science.gov (United States)

    Woodcock, Leslie V.

    2017-09-01

    This comment is in response to a comment by Sengers and Anisimov on the article "Gibbs density surface of fluid argon" that contradicts prevailing theory. It has not "been established experimentally that the thermodynamic properties of fluids satisfy scaling laws with universal critical exponents asymptotically close to a single critical point of the vapor-liquid phase transition." Here we explain why an apparent divergence of Cv, in historical experimental "evidence," is based upon a misinterpretation of near-critical gas-liquid heat capacity measurements in the two-phase coexistence region. The conclusion that there is no "singular critical point" on Gibbs density surface still stands.

  16. Observation of monoenergetic protons from a near-critical gas target tailored by a hydrodynamic shock

    Science.gov (United States)

    Chen, Y.-H.; Helle, M. H.; Ting, A.; Gordon, D. F.; Polyanskiy, M. N.; Pogorelsky, I.; Babzien, M.; Najmudin, Z.

    2015-05-01

    We present our recent experimental results of monoenergetic protons accelerated from the interaction of an intense terawatt CO2 laser pulse with a near-critical hydrogen gas target, with its density profile tailored by a hydrodynamic shock. A 5-ns Nd:YAG laser pulse is focused onto a piece of stainless steel foil mounted at the front edge of the gas jet nozzle orifice. The ablation launches a spherical shock into the near-critical gas column, which creates a sharp density gradient at the front edge of the target, with ~ 6X local density enhancement up to several times of critical density within ~<100 microns. With such density profile, we have obtained monoenergetic proton beams with good shot-to-shot reproducibility and energies up to 1.2 MeV.

  17. Development of high temperature superconductors having high critical current density

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Gye Wong; Kim, C. J.; Lee, H.G.; Kwon, S. C.; Lee, H. J.; Kim, K. B.; Park, J. Y.; Jung, C. H

    2000-08-01

    Fabrication of high T{sub c} superconductors and its applications for electric power device were carried out for developing superconductor application technologies. High quality YBCO superconductors was fabricated by melt texture growth, top-seeded melt growth process and multi-seeded melt growth process and the properties was compared. The critical current density of the melt processed YBCO superconductors was about few 10,000 A/cm{sup 2} and the levitation force was 50 N. The processing time needed for the growth of the 123 single grain was greatly reduced by applying multi-seeding without no significant degradation of the levitation force. The multi-seeded melt growth process was confirmed as a time-saving and cost-effective method for the fabrication of bulk superconductors with controlled crystallographic orientation.

  18. High performance hand-held gas chromatograph

    Energy Technology Data Exchange (ETDEWEB)

    Yu, C.M.

    1998-04-28

    The Microtechnology Center of Lawrence Livermore National Laboratory has developed a high performance hand-held, real time detection gas chromatograph (HHGC) by Micro-Electro-Mechanical-System (MEMS) technology. The total weight of this hand-held gas chromatograph is about five lbs., with a physical size of 8{close_quotes} x 5{close_quotes} x 3{close_quotes} including carrier gas and battery. It consumes about 12 watts of electrical power with a response time on the order of one to two minutes. This HHGC has an average effective theoretical plate of about 40k. Presently, its sensitivity is limited by its thermal sensitive detector at PPM. Like a conventional G.C., this HHGC consists mainly of three major components: (1) the sample injector, (2) the column, and (3) the detector with related electronics. The present HHGC injector is a modified version of the conventional injector. Its separation column is fabricated completely on silicon wafers by means of MEMS technology. This separation column has a circular cross section with a diameter of 100 pm. The detector developed for this hand-held GC is a thermal conductivity detector fabricated on a silicon nitride window by MEMS technology. A normal Wheatstone bridge is used. The signal is fed into a PC and displayed through LabView software.

  19. Critical temperature for the nuclear liquid-gas phase transition (from multifragmentation and fission)

    CERN Document Server

    Karnaukhov, V A; Budzanowski, A; Avdeyev, S P; Botvina, A S; Cherepanov, E A; Karcz, W; Kirakosyan, V V; Rukoyatkin, P A; Skwirczynska, I; Norbeck, E

    2008-01-01

    Critical temperature Tc for the nuclear liquid-gas phase transition is stimated both from the multifragmentation and fission data. In the first case,the critical temperature is obtained by analysis of the IMF yields in p(8.1 GeV)+Au collisions within the statistical model of multifragmentation (SMM). In the second case, the experimental fission probability for excited 188Os is compared with the calculated one with Tc as a free parameter. It is concluded for both cases that the critical temperature is higher than 16 MeV.

  20. Measurements of the Coexistence Curve near the Liquid-Gas Critical Point

    Science.gov (United States)

    Hahn, Inseob

    2003-01-01

    The shape of the liquid-gas coexistence curve of He-3 very near the critical point (-2x10(exp -6) critical point was strongly affected by the gravitational field. Away from the critical point, the coexistence curve obtained using this technique was also consistent with the earlier work using the local density measurements of Pittman et al. The recent crossover parametric model of the equation-of-state are used to analyze the height-dependent measured coexistence curves. Data analyses have indicated that microgravity will permit measurements within two additional decades in reduced temperatures beyond the best gravity-free data obtained in Earth-bound experiments.

  1. Picosecond High Pressure Gas Switch experiment

    Energy Technology Data Exchange (ETDEWEB)

    Cravey, W.R.; Freytag, E.K.; Goerz, D.A.; Poulsen, P.; Pincosy, P.A.

    1993-08-01

    A high Pressure Gas Switch has been developed and tested at LLNL. Risetimes on the order of 200 picoseconds have been observed at 1 kHz prf and 1 atmosphere pressures. Calculations show that switching closure times on the order of tens of picoseconds can be achieved at higher pressures and electric fields. A voltage hold-off of 1 MV/cm has been measured at 10 atmospheres and several MV/cm appears possible with the HPGS. With such high electric field levels, energy storage of tens of Joules in a reasonably sized package is achievable. Initial HPGS performance has been characterized using the WASP pulse generator at LLNL. A detailed description of the switch used for initial testing is given. Switch recovery times of 1-ms have been measured at 1 atmosphere. Data on the switching uniformity, voltage hold-off recovery, and pulse repeatability, is presented. In addition, a physics switch model is described and results are compared with experimental data. Modifications made to the WASP HV pulser in order to drive the HPGS will also be discussed. Recovery times of less than 1 ms were recorded without gas flow in the switch chambers. Low pressure synthetic air was used as the switch dielectric. Longer recovery times were required when it was necessary to over-voltage the switch.

  2. THE STRUCTURE OF GAS-ACCRETING PROTOPLANETS AND THE CONDITION OF THE CRITICAL CORE MASS

    Energy Technology Data Exchange (ETDEWEB)

    Kanagawa, Kazuhiro D. [Department of Cosmosciences, Graduate School of Science, Hokkaido University, N10 W8, Sapporo 060-0810 (Japan); Fujimoto, Masayuki Y., E-mail: kanagawa@astro1.sci.hokudai.ac.jp [Nuclear Reaction Data Center, Graduate School of Science, Hokkaido University, Kita 10 Nishi 8, Kita-ku, Sapporo 060-0810 (Japan)

    2013-03-01

    In the core accretion model for the formation of gas giant planets, runaway gas accretion onto a core is the primary requisite, triggered when the core mass reaches a critical value. The recently revealed wide diversity of the extrasolar giant planets suggests the necessity to further the understanding of the conditions resulting in the critical core mass that initiates runaway accretion. We study the internal structure of protoplanets under hydrostatic and thermal equilibria represented in terms of a polytropic equation of state to investigate what factors determine and affect the critical core mass. We find that the protoplanets, embedded in protoplanetary disks, have the same configuration as red giants, characterized by the envelope of the centrally condensed type solution. Applying the theory of stellar structure with homology invariants, we demonstrate that there are three types of criteria for the critical core mass depending on the stiffness of polytrope and the nature of outer boundary condition. For the stiff polytropes of index N {<=} 3 with the Bondi radius as the outer boundary, the criterion governing the critical core mass occurs at the surface. For stiff polytropes with the Hill outer boundary and for soft polytropes of N > 3, this criterion acts at the bottom of gaseous envelope. Further, we elucidate the roles and effects of coexistent radiative and convective zones in the envelope of critical core mass. Based on the results, we discuss the relevance of Bondi and Hill surface conditions and explore the parameter dependences of critical core mass.

  3. Research on Axial Trail of High-Speed Gas Painting Automizor

    Institute of Scientific and Technical Information of China (English)

    杨志永; 张大卫; 黄田

    2003-01-01

    The non-linear dynamic model is set up of one type of high-speed painting automizor with gas supporting system. The stability of motion and dynamic response of the gas painting automizor system are studied over a relatively wide range of rotating speed by numerical analytic method, the critical velocity under working condition is found, and rotate stability and critical condition are discussed in theory. Furthermore, the range of the critical parameter of the system when Hopf bifurcation occurs and the law between axis trace and bearing clearance are acquired, too.

  4. High Critical Current in Metal Organic Derived YBCO Films

    Science.gov (United States)

    2010-10-31

    Contract No. FA9550-07-C-0034 “High Critical Current in Metal Organic Derived YBCO Films” Final Report Prepared for: Dr. Harold...Critical Current in Metal Organic Derived YBCO Films 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT...Project focused on optimization of the Metal Organic Deposition (MOD) process for deposition thick, high critical current YBCO films for use in the

  5. Evaluation of a transcutaneous blood gas monitoring system in critically ill dogs.

    Science.gov (United States)

    Holowaychuk, Marie K; Fujita, Hiroshi; Bersenas, Alexa M E

    2014-01-01

    To describe the use of a transcutaneous blood gas monitoring system in critically ill dogs, determine if transcutaneous and arterial blood gas values have good agreement, and verify if clinical or laboratory variables are correlated with differences between transcutaneous and arterial blood gas measurements. Prospective observational study. University teaching hospital ICU. Twenty-three client-owned dogs. In critically ill dogs undergoing arterial blood gas monitoring, a transcutaneous blood gas monitor was used to measure transcutaneous partial pressure of carbon dioxide (PtcCO2 ) and transcutaneous partial pressure of oxygen (PtcO2 ) values 30 minutes after sensor placement, which were compared to PaCO2 and PaO2 values measured simultaneously. Clinical and laboratory variables were concurrently recorded to determine if they were correlated with the difference between transcutaneous and arterial blood gas measurements. Bland-Altman analysis revealed a mean bias of 4.6 ± 26.3 mm Hg (limits of agreement [LOA]: -46.9/+56.1 mm Hg) between PtcO2 and PaO2 and a mean bias of 9.3 ± 8.5 mm Hg (LOA: -7.5/+26.0 mm Hg) between PtcCO2 and PaCO2 . The difference between PtcCO2 -PaCO2 was strongly negatively correlated with HCO3 (-) (r(2) = 0.52, P blood pressure (r(2) = 0.21, P = 0.044), whereas the difference between PtcCO2 -PaCO2 was moderately negatively correlated with diastolic blood pressure (r(2) = 0.33, P = 0.008). Agreement between transcutaneous and arterial PO2 and PCO2 measurements in these critically ill dogs was inferior to that reported in similar adult and pediatric human studies. The transcutaneous monitor consistently over-estimated PaO2 and PaCO2 and should not be used to replace arterial blood gas measurements in critically ill dogs requiring blood gas interpretation. © Veterinary Emergency and Critical Care Society 2014.

  6. Theoretical Analysis of Thermodynamic Measurements near a Liquid-Gas Critical Point

    Science.gov (United States)

    Barmatz, M.; Zhong, Fang; Hahn, Inseob

    2003-01-01

    Over the years, many ground-based studies have been performed near liquid-gas critical points to elucidate the expected divergences in thermodynamic quantities. The unambiguous interpretation of these studies very near the critical point is hindered by a gravity-induced density stratification. However, these ground-based measurements can give insight into the crossover behavior between the asymptotic critical region near the transition and the mean field region farther away. We have completed a detailed analysis of heat capacity, susceptibility and coexistence curve measurements near the He-3 liquid-gas critical point using the minimal-subtraction renormalization (MSR) scheme within the phi(exp 4) model. This MSR scheme, using only two adjustable parameters, provides a reasonable global fit to all of these experimental measurements in the gravity-free region out to a reduced temperature of |t| approx. 2x10(exp -2). Recently this approach has also been applied to the earlier microgravity measurements of Haupt and Straub in SF(sub 6) with surprising results. The conclusions drawn from the MSR analyses will be presented. Measurements in the gravity-affected region closer to the He-3 critical point have also been analyzed using the recent crossover parametric model (CPM) of the equation-of-state. The results of fitting heat capacity measurements to the CPM model along the He-3 critical isochore in the gravity-affected region will also be presented.

  7. Affective and neural reactivity to criticism in individuals high and low on perceived criticism.

    Science.gov (United States)

    Hooley, Jill M; Siegle, Greg; Gruber, Staci A

    2012-01-01

    People who have remitted from depression are at increased risk for relapse if they rate their relatives as being critical of them on a simple self-report measure of Perceived Criticism (PC). To explore neural mechanisms associated with this we used functional magnetic resonance imaging (fMRI) to examine how people with different levels of PC responded to hearing criticism from their own mothers. To maximize variability in affective reactivity, depressed, recovered depressed, and healthy control participants (n = 33) were classified as high or low in PC based on a median split. They were then exposed to personally-relevant critical and praising comments from their mothers. Perceived Criticism levels were unrelated to depression status and to negative mood change after hearing criticism. However, compared to low PC participants, those who scored high on PC showed differential activation in a network of regions associated with emotion reactivity and regulation, including increased amygdala activity and decreased reactions in prefrontal regulatory regions when they heard criticism. This was not the case for praise. Criticism may be a risk factor for relapse because it helps to "train" pathways characteristic of depressive information processing. The Perceived Criticism measure may help identify people who are more susceptible to this vulnerability.

  8. Smart Onboard Inspection of High Pressure Gas Fuel Cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Beshears, D.L.; Starbuck, J.M.

    1999-09-27

    The use of natural gas as an alternative fuel in automotive applications is not widespread primarily because of the high cost and durability of the composite storage tanks. Tanks manufactured using carbon fiber are desirable in weight critical passenger vehicles because of the low density of carbon fiber. The high strength of carbon fiber also translates to a weight reduction because thinner wall designs are possible to withstand the internal pressure loads. However, carbon fiber composites are prone to impact damage that over the life of the storage tank may lead to an unsafe condition for the vehicle operator. A technique that potentially may be a reliable indication of developing hazardous conditions in composite fuel tanks is imbedded fiber optics. The applicability of this technique to onboard inspection is discussed and results from preliminary lab testing indicate that fiber optic sensors can reliably detect impact damage.

  9. Ben Macdhui High Altitude Trace Gas and Aerosol Transport Experiment

    CSIR Research Space (South Africa)

    Piketh, SJ

    1999-01-01

    Full Text Available The Ben Macdhui High Altitude Aerosol and Trace Gas Transport Experiment (BHATTEX) was started to characterize the nature and magnitude of atmospheric, aerosol and trace gas transport paths recirculation over and exiting from southern Africa...

  10. Decomposition of water into highly combustible hydroxyl gas used in ...

    African Journals Online (AJOL)

    Decomposition of water into highly combustible hydroxyl gas used in internal ... of alternative sources of energy that produce less amounts of carbon dioxide. ... The by-product obtained from combustion of this gas is water vapour and oxygen ...

  11. Criticality safety in high explosives dissolution

    Energy Technology Data Exchange (ETDEWEB)

    Troyer, S.D.

    1997-06-01

    In 1992, an incident occurred at the Pantex Plant in which the cladding around a fissile material component (pit) cracked during dismantlement of the high explosives portion of a nuclear weapon. Although the event did not result in any significant contamination or personnel exposures, concerns about the incident led to the conclusion that the current dismantlement process was unacceptable. Options considered for redesign, dissolution tooling design considerations, dissolution tooling design features, and the analysis of the new dissolution tooling are summarized. The final tooling design developed incorporated a number of safety features and provides a simple, self-contained, low-maintenance method of high explosives removal for nuclear explosive dismantlement. Analyses demonstrate that the tooling design will remain subcritical under normal, abnormal, and credible accident scenarios. 1 fig.

  12. Quantitative determination of wine highly volatile sulfur compounds by using automated headspace solid-phase microextraction and gas chromatography-pulsed flame photometric detection. Critical study and optimization of a new procedure.

    Science.gov (United States)

    López, Ricardo; Lapeña, Ana Cristina; Cacho, Juan; Ferreira, Vicente

    2007-03-02

    The quantitative determination of wine volatile sulfur compounds by automated headspace solid-phase microextraction (HS-SPME) with a carboxen-polydimethylsiloxane (CAR-PDMS) fiber and subsequent gas chromatography-pulsed flame photometric detection (GC-PFPD) has been evaluated. The direct extraction of the sulfur compounds in 5 ml of wine has been found to suffer from matrix effects and short linear ranges, problems which could not be solved by the use of different internal standards or by multiple headspace SPME. These problems were attributed to saturation of the fiber and to competitive effects between analytes, internal standards and other wine volatiles. Another problem was the oxidation of analytes during the procedure. The reduction in sample volume by a factor 50 (0.1 ml diluted with water or brine) brought about a reduction in the amount of sulfur compounds taken in the fiber by a factor just 3.3. Consequently, a new procedure has been proposed. In a sealed vial containing 4.9 ml of saturated NaCl brine, the air is thoroughly displaced with nitrogen, and the wine (0.1 ml) and the internal standards (0.02 ml) are further introduced with a syringe through the vial septum. This sample is extracted at 35 degrees C for 20 min. This procedure makes a satisfactory determination possible of hydrogen sulfide, methanethiol, ethanethiol, dimethyl sulfide, diethyl sulfide and dimethyl disulfide. The linear dynamic ranges cover the normal ranges of occurrence of these analytes in wine with typical r2 between 0.9823 and 0.9980. Reproducibility in real samples ranges from 10 to 20% and repeatability is better than 10% in most cases. The method accuracy is satisfactory, with errors below 20% for hydrogen sulfide and mostly below 10% for the other compounds. The proposed method has been applied to the analysis of 34 Spanish wines.

  13. Experimental determination of the critical welding speed in high speed MAG welding

    Institute of Scientific and Technical Information of China (English)

    Hu Zhikun; Wu Chuansong

    2008-01-01

    In high speed MAG welding process, some weld formation defects may be encountered. To get good weld quality, the critical welding speed beyond which humping or undercutting weld bead can occur must be known for different conditions. In this research, high speed MAG welding tests were carried out to check out the effects of different factors on the critical welding speed. Through observing the weld bead profiles and the macrographs of the transverse sections of MAG welds, the occurrence tendency of humping weld was analyzed, and the values of critical welding speed were determined under different levels of welding current or voltage, and the effect of shielding gas compositions on the critical welding speed was also investigated.

  14. High-temperature Gas Reactor (HTGR)

    Science.gov (United States)

    Abedi, Sajad

    2011-05-01

    General Atomics (GA) has over 35 years experience in prismatic block High-temperature Gas Reactor (HTGR) technology design. During this period, the design has recently involved into a modular have been performed to demonstrate its versatility. This versatility is directly related to refractory TRISO coated - particle fuel that can contain any type of fuel. This paper summarized GA's fuel cycle studies individually and compares each based upon its cycle sustainability, proliferation-resistance capabilities, and other performance data against pressurized water reactor (PWR) fuel cycle data. Fuel cycle studies LEU-NV;commercial HEU-Th;commercial LEU-Th;weapons-grade plutonium consumption; and burning of LWR waste including plutonium and minor actinides in the MHR. results show that all commercial MHR options, with the exception of HEU-TH, are more sustainable than a PWR fuel cycle. With LEU-NV being the most sustainable commercial options. In addition, all commercial MHR options out perform the PWR with regards to its proliferation-resistance, with thorium fuel cycle having the best proliferation-resistance characteristics.

  15. Critical challenges in ERP implementation: A qualitative case study in the Canadian oil and gas industry

    Science.gov (United States)

    Menon, Sreekumar A.

    This exploratory qualitative single-case study examines critical challenges encountered during ERP implementation based on individual perspectives in four project roles: senior leaders, project managers, project team members, and business users, all specifically in Canadian oil and gas industry. Data was collected by interviewing participants belonging to these categories, and by analyzing project documentation about ERP implementation. The organization for the case study was a leading multinational oil and gas company having a substantial presence in the energy sector in Canada. The study results were aligned with the six management questions regarding critical challenges in ERP: (a) circumstances to implement ERP, (b) benefits and process improvements achieved, (c) best practices implemented, (d) critical challenges encountered, (e) strategies and mitigating actions used, and (f) recommendations to improve future ERP implementations. The study results highlight six key findings. First, the study provided valid circumstances for implementing ERP systems. Second, the study underscored the importance of benefits and process improvements in ERP implementation. Third, the study highlighted that adoption of best practices is crucial for ERP Implementation. Fourth, the study found that critical challenges are encountered in ERP Implementation and are significant during ERP implementation. Fifth, the study found that strategies and mitigating actions can overcome challenges in ERP implementation. Finally, the study provided ten major recommendations on how to improve future ERP implementations.

  16. Determination of indices and critical values of gas parameters of the first gas outburst in a coal seam of the Xieqiao Mine

    Institute of Scientific and Technical Information of China (English)

    Ou Jianchun; Liu Mingju; Zhang Chunru; Liu Yanwei; Wei Jianping

    2012-01-01

    Based on the important role in mine safety played by parameters of the first gas outburst,we propose a method of combining historic data,theoretical analysis and experimental research for the purpose of critical values of gas parameters of the first gas outburst in a coal seam of the Xieqiao Mine.According to a characteristic analysis and a summary of the rules ofcoal and gas outbursts in the No.8 coal seam ofa Huainan mine,we have investigated their effect on coal and gas outbursts in terms such as ground stress,gas,and coal structure.We have selected gas parameters and determined the critical values of each of the following indices:gas content as 7.7 m3/t,tectonic coal as 0.8 m thick,the absolute gas emission as 2 m3/min,the rate of change as 0.7 m3/min,the gas desorption index of a drilling chip K1 as 0.26 ml/(g min1/2) and the values of desorption indexes △h2 as 200 Pa.From a verification of the production,the results indicate that application of each index and their critical values significantly improve the level of safety in the production process,relieve the burden upon the mine,save much labor and bring clear economic benefits.

  17. Can we approach the gas-liquid critical point using slab simulations of two coexisting phases?

    Science.gov (United States)

    Goujon, Florent; Ghoufi, Aziz; Malfreyt, Patrice; Tildesley, Dominic J

    2016-09-28

    In this paper, we demonstrate that it is possible to approach the gas-liquid critical point of the Lennard-Jones fluid by performing simulations in a slab geometry using a cut-off potential. In the slab simulation geometry, it is essential to apply an accurate tail correction to the potential energy, applied during the course of the simulation, to study the properties of states close to the critical point. Using the Janeček slab-based method developed for two-phase Monte Carlo simulations [J. Janec̆ek, J. Chem. Phys. 131, 6264 (2006)], the coexisting densities and surface tension in the critical region are reported as a function of the cutoff distance in the intermolecular potential. The results obtained using slab simulations are compared with those obtained using grand canonical Monte Carlo simulations of isotropic systems and the finite-size scaling techniques. There is a good agreement between these two approaches. The two-phase simulations can be used in approaching the critical point for temperatures up to 0.97 TC(∗) (T(∗) = 1.26). The critical-point exponents describing the dependence of the density, surface tension, and interfacial thickness on the temperature are calculated near the critical point.

  18. Can we approach the gas-liquid critical point using slab simulations of two coexisting phases?

    Science.gov (United States)

    Goujon, Florent; Ghoufi, Aziz; Malfreyt, Patrice; Tildesley, Dominic J.

    2016-09-01

    In this paper, we demonstrate that it is possible to approach the gas-liquid critical point of the Lennard-Jones fluid by performing simulations in a slab geometry using a cut-off potential. In the slab simulation geometry, it is essential to apply an accurate tail correction to the potential energy, applied during the course of the simulation, to study the properties of states close to the critical point. Using the Janeček slab-based method developed for two-phase Monte Carlo simulations [J. Janec̆ek, J. Chem. Phys. 131, 6264 (2006)], the coexisting densities and surface tension in the critical region are reported as a function of the cutoff distance in the intermolecular potential. The results obtained using slab simulations are compared with those obtained using grand canonical Monte Carlo simulations of isotropic systems and the finite-size scaling techniques. There is a good agreement between these two approaches. The two-phase simulations can be used in approaching the critical point for temperatures up to 0.97 TC ∗ (T∗ = 1.26). The critical-point exponents describing the dependence of the density, surface tension, and interfacial thickness on the temperature are calculated near the critical point.

  19. Correlation of Venous Blood Gas and Pulse Oximetry With Arterial Blood Gas in the Undifferentiated Critically Ill Patient.

    Science.gov (United States)

    Zeserson, Eli; Goodgame, Ben; Hess, J Daniel; Schultz, Kristine; Hoon, Cynthia; Lamb, Keith; Maheshwari, Vinay; Johnson, Steven; Papas, Mia; Reed, James; Breyer, Michael

    2016-06-09

    Blood gas analysis is often used to assess acid-base, ventilation, and oxygenation status in critically ill patients. Although arterial blood gas (ABG) analysis remains the gold standard, venous blood gas (VBG) analysis has been shown to correlate with ABG analysis and has been proposed as a safer less invasive alternative to ABG analysis. The purpose of this study was to evaluate the correlation of VBG analysis plus pulse oximetry (SpO2) with ABG analysis. We performed a prospective cohort study of patients in the emergency department (ED) and intensive care unit (ICU) at a single academic tertiary referral center. Patients were eligible for enrollment if the treating physician ordered an ABG. Statistical analysis of VBG, SpO2, and ABG data was done using paired t test, Pearson χ(2), and Pearson correlation. There were 156 patients enrolled, and 129 patients completed the study. Of the patients completing the study, 53 (41.1%) were in the ED, 41 (31.8%) were in the medical ICU, and 35 (27.1%) were in the surgical ICU. The mean difference for pH between VBG and ABG was 0.03 (95% confidence interval: 0.03-0.04) with a Pearson correlation of 0.94. The mean difference for pCO2 between VBG and ABG was 4.8 mm Hg (95% confidence interval: 3.7-6.0 mm Hg) with a Pearson correlation of 0.93. The SpO2 correlated well with PaO2 (the partial pressure of oxygen in arterial blood) as predicted by the standard oxygen-hemoglobin dissociation curve. In this population of undifferentiated critically ill patients, pH and pCO2 on VBG analysis correlated with pH and pCO2 on ABG analysis. The SpO2 correlated well with pO2 on ABG analysis. The combination of VBG analysis plus SpO2 provided accurate information on acid-base, ventilation, and oxygenation status for undifferentiated critically ill patients in the ED and ICU. © The Author(s) 2016.

  20. Electrochemical high-temperature gas sensors

    Science.gov (United States)

    Saruhan, B.; Stranzenbach, M.; Yüce, A.; Gönüllü, Y.

    2012-06-01

    Combustion produced common air pollutant, NOx associates with greenhouse effects. Its high temperature detection is essential for protection of nature. Component-integration capable high-temperature sensors enable the control of combustion products. The requirements are quantitative detection of total NOx and high selectivity at temperatures above 500°C. This study reports various approaches to detect NO and NO2 selectively under lean and humid conditions at temperatures from 300°C to 800°C. All tested electrochemical sensors were fabricated in planar design to enable componentintegration. We suggest first an impedance-metric gas sensor for total NOx-detection consisting of NiO- or NiCr2O4-SE and PYSZ-electrolyte. The electrolyte-layer is about 200μm thickness and constructed of quasi-single crystalline columns. The sensing-electrode (SE) is magnetron sputtered thin-layers of NiO or NiCr2O4. Sensor sensitivity for detection of total NOx has been measured by applying impedance analysis. The cross-sensitivity to other emission gases such as CO, CO2, CH4 and oxygen (5 vol.%) has been determined under 0-1000ppm NO. Sensor maintains its high sensitivity at temperatures up to 550°C and 600°C, depending on the sensing-electrode. NiO-SE yields better selectivity to NO in the presence of oxygen and have shorter response times comparing to NiCr2O4-SE. For higher temperature NO2-sensing capability, a resistive DC-sensor having Al-doped TiO2-sensing layers has been employed. Sensor-sensitivity towards NO2 and cross-sensitivity to CO has been determined in the presence of H2O at temperatures 600°C and 800°C. NO2 concentrations varying from 25 to 100ppm and CO concentrations from 25 to 75ppm can be detected. By nano-tubular structuring of TiO2, NO2 sensitivity of the sensor was increased.

  1. Study of the critical behavior of the driven lattice gas model with limited nonequilibrium dynamics

    Science.gov (United States)

    Saracco, Gustavo P.; Rubio Puzzo, M. Leticia; Bab, Marisa A.

    2017-02-01

    In this paper the nonequilibrium critical behavior is investigated using a variant of the well-known two-dimensional driven lattice gas (DLG) model, called modified driven lattice gas (MDLG). In this model, the application of the external field is regulated by a parameter p ɛ [ 0 , 1 ] in such a way that if p = 0, the field is not applied, and it becomes the Ising model, while if p = 1, the DLG model is recovered. The behavior of the model is investigated for several values of p by studying the dynamic evolution of the system within the short-time regime in the neighborhood of a phase transition. It is found that the system experiences second-order phase transitions in all the interval of p for the density of particles ρ = 0.5. The determined critical temperatures Tc(p) are greater than the critical temperature of the Ising model TcI, and increase with p up to the critical temperature of the DLG model in the limit of infinite driving fields. The dependence of Tc(p) on p is compatible with a power-law behavior whose exponent is ψ = 0.27(3) . Furthermore, the complete set of the critical and the anisotropic exponents is estimated. For the smallest value of p, the ​dynamics and β exponents are close to that calculated for the Ising model, and the anisotropic exponent Δ is near zero. As p is increased, the exponents and Δ change, meaning that the anisotropy effects increase. For the largest value investigated, the set of exponents approaches to that reported by the most recent theoretical framework developed for the DLG model.

  2. A Comparison of Critical Regimes in Collapsible Tube, Pipe, Open Channel and Gas-Dynamic Flows

    Science.gov (United States)

    Arun, C. P.

    2003-11-01

    Though of considerable interest to clinical scientists, collapsible tubes are only recently receiving due interest by fluid physicists. The subject of critical phenomena in collapsible tube flow appears not to have been examined critically. For example, it has been proposed in the past that shock waves in physiological tubes are abnormal. We propose a classification of flow through collapsible tubes recognising that compressibility in gas-dynamic and pipe flow (cf.waterhammer) corresponds to distensibility in collapsible tube flow. Thus, opening and closing waves of collapsible tube flow (predistension regime) is subcritical flow and the post-distension regime, supercritical. Physiological tubes are often hyperelastic and contractile and often, when distension is very significant, a hypercritical regime corresponding to hypersonic gas-dynamic flow is admissible. Such a hypercritical regime would allow storage of energy and muscle contraction in the wall of the tube and hence continuance of propulsion in the essentially intermittent flow that is seen in collapsible tubes. Such a mechanism appears to be in operation in the human aorta, bowel and urethra. The present work offers a comparison of critical regimes in various fluid flow situations including collapsible tubes, that is in harmony with known phenomena seen in nature.

  3. Shells, holes, worms, high-velocity gas and the z-distribution of gas in galaxies.

    Science.gov (United States)

    Rand, R. J.

    The author gives an overview of the current observational understanding of vertically extended gas components in spiral galaxies and the various phenomena which come under such names as shells, holes, worms, and high-velocity gas. For the most part, the focus is on recent high-resolution interferometric studies. The author concentrates on cold gas, and briefly on warm ionized gas, in the Milky Way and a few nearby spirals. Along the way, it is seen how phenomena such as worms and shells may be related to the formation and maintenance of the vertically extended components.

  4. The Effect of Inclination Angle on Critical Heat Flux in a Locally Heated Liquid Film Moving Under the Action of Gas Flow in a Mini-Channel

    Directory of Open Access Journals (Sweden)

    Tkachenko Egor M.

    2016-01-01

    Full Text Available Intensively evaporating liquid films moving under the action of the cocurrent gas flow in a microchannel are promising for the use in modern cooling systems of semiconductor devices with high local heat release. This work has studied the dependence of the critical heat flux on the inclination angle of the channel. It has been found that the inclination angle in the plane parallel to the flow has no significant effect on the critical heat flux. Whereas the inclination angle in the plane perpendicular to the flow, on the contrary, significantly changes the value of the critical heat flux. However, for a given flow rate of fluid there is a threshold gas velocity at which the critical heat flux does not differ from the case of zero inclination of the channel. Thus, it can be concluded that the cooling system based on shear-driven liquid films can be potentially used when direction of the gravity changes.

  5. Critical behavior of the ideal-gas Bose-Einstein condensation in the Apollonian network.

    Science.gov (United States)

    de Oliveira, I N; dos Santos, T B; de Moura, F A B F; Lyra, M L; Serva, M

    2013-08-01

    We show that the ideal Boson gas displays a finite-temperature Bose-Einstein condensation transition in the complex Apollonian network exhibiting scale-free, small-world, and hierarchical properties. The single-particle tight-binding Hamiltonian with properly rescaled hopping amplitudes has a fractal-like energy spectrum. The energy spectrum is analytically demonstrated to be generated by a nonlinear mapping transformation. A finite-size scaling analysis over several orders of magnitudes of network sizes is shown to provide precise estimates for the exponents characterizing the condensed fraction, correlation size, and specific heat. The critical exponents, as well as the power-law behavior of the density of states at the bottom of the band, are similar to those of the ideal Boson gas in lattices with spectral dimension d(s)=2ln(3)/ln(9/5)~/=3.74.

  6. High pressure gas vessels for neutron scattering experiments

    CERN Document Server

    Done, R; Evans, B E; Bowden, Z A

    2010-01-01

    The combination of high pressure techniques with neutron scattering proves to be a powerful tool for studying the phase transitions and physical properties of solids in terms of inter-atomic distances. In our report we are going to review a high pressure technique based on a gas medium compression. This technique covers the pressure range up to ~0.7GPa (in special cases 1.4GPa) and typically uses compressed helium gas as the pressure medium. We are going to look briefly at scientific areas where high pressure gas vessels are intensively used in neutron scattering experiments. After that we are going to describe the current situation in high pressure gas technology; specifically looking at materials of construction, designs of seals and pressure vessels and the equipment used for generating high pressure gas.

  7. Clean and highly ordered graphene synthesized in the gas phase.

    Science.gov (United States)

    Dato, Albert; Lee, Zonghoon; Jeon, Ki-Joon; Erni, Rolf; Radmilovic, Velimir; Richardson, Thomas J; Frenklach, Michael

    2009-10-28

    We report that the substrate-free gas-phase graphene synthesis method produces clean and highly ordered graphene sheets that are similar in quality to the graphene obtained through the mechanical exfoliation of highly oriented pyrolytic graphite.

  8. Transport signatures of quantum critically in Cr at high pressure.

    Energy Technology Data Exchange (ETDEWEB)

    Jaramillo, R.; Feng, Y.; Wang, J.; Rosenbaum, T. F. (X-Ray Science Division); ( PSC-USR); (Harvard Univ.); (Univ. of Chicago)

    2010-08-03

    The elemental antiferromagnet Cr at high pressure presents a new type of naked quantum critical point that is free of disorder and symmetry-breaking fields. Here we measure magnetotransport in fine detail around the critical pressure, P{sub c} {approx} 10 GPa, in a diamond anvil cell and reveal the role of quantum critical fluctuations at the phase transition. As the magnetism disappears and T {yields} 0, the magntotransport scaling converges to a non-mean-field form that illustrates the reconstruction of the magnetic Fermi surface, and is distinct from the critical scaling measured in chemically disordered Cr:V under pressure. The breakdown of itinerant antiferromagnetism only comes clearly into view in the clean limit, establishing disorder as a relevant variable at a quantum phase transition.

  9. The impact of high oil prices on natural gas; Hoge olieprijzen maken gas duur

    Energy Technology Data Exchange (ETDEWEB)

    Koevoet, H. (ed.)

    2003-04-01

    The principle of gas-to-oil (oil prices determine the price of natural gas) in the Netherlands and several other developments elsewhere (war in Iraq and a cold winter in the USA) has caused high natural gas prices. The question is whether the liberalization of the energy market can change this principle. [Dutch] De oorlogswolken boven Irak en een koude winter in de USA hebben de prijs van olie fors opgedreven. Daardoor is ook gas erg duur geworden. Kan de liberalisering daar iets aan veranderen?.

  10. Critical Science Education in a Suburban High School Chemistry Class

    Science.gov (United States)

    Ashby, Patrick

    To improve students' scientific literacy and their general perceptions of chemistry, I enacted critical chemistry education (CCE) in two "regular level" chemistry classes with a group of 25 students in a suburban, private high school as part of this study. CCE combined the efforts of critical science educators (Fusco & Calabrese Barton, 2001; Gilbert 2013) with the performance expectations of the Next Generation Science Standards (NGSS) (NGSS Lead States, 2013a) to critically transform the traditional chemistry curriculum at this setting. Essentially, CCE engages students in the critical exploration of socially situated chemistry content knowledge and requires them to demonstrate this knowledge through the practices of science. The purpose of this study was to gauge these students development of chemistry content knowledge, chemistry interest, and critical scientific literacy (CSL) as they engaged in CCE. CSL was a construct developed for this study that necessarily combined the National Research Center's (2012) definition of scientific literacy with a critical component. As such, CSL entailed demonstrating content knowledge through the practices of science as well as the ability to critically analyze the intersections between science content and socially relevant issues. A mixed methods, critical ethnographic approach framed the collection of data from open-ended questionnaires, focus group interviews, Likert surveys, pre- and post unit tests, and student artifacts. These data revealed three main findings: (1) students began to develop CSL in specific, significant ways working through the activities of CCE, (2) student participants of CCE developed a comparable level of chemistry content understanding to students who participated in a traditional chemistry curriculum, and (3) CCE developed a group of students' perceptions of interest in chemistry. In addition to being able to teach students discipline specific content knowledge, the implications of this study are

  11. High critical temperature superconductor Josephson junctions for quantum circuit applications

    Energy Technology Data Exchange (ETDEWEB)

    Bauch, T; Gustafsson, D; Cedergren, K; Nawaz, S; Mumtaz Virk, M; Lombardi, F [Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, Goeteborg (Sweden); Pettersson, H; Olsson, E [Department of Applied Physics, Chalmers University of Technology, Goeteborg (Sweden)], E-mail: bauch@chalmers.se

    2009-12-15

    Recent findings of macroscopic quantum properties in high critical temperature superconductor (HTS) Josephson junctions (JJs) point toward the need to revise the role of zero energy quasi-particles in this novel superconductor. We will discuss the possibility of designing superconducting artificial atoms in a transmon configuration to study the low energy excitation spectra of HTS. We have engineered high quality grain boundary JJs on low dielectric constant substrates. By fabricating submicron junctions, we extract values of capacitance and Josephson critical current densities that satisfy the main transmon design requirements. Moreover, the measured critical current noise power extrapolated at 1 Hz gives a dephasing time of 25 ns, which indicates that the observation of macroscopic quantum coherent effects in HTS JJ is a feasible task.

  12. Fast High Capacity Annular Gas Puff Valve Design Concept

    Science.gov (United States)

    Ruden, Edward

    2000-10-01

    A fast opening gas valve design concept is presented that can theoretically inject a few grams of D2 gas radially outward into a coaxial annular vacuum region with a radius of about 10 cm in less that 100 μ s. The concept employs a single turn 20-30 T pulsed magnetic field coil that axially accelerates an Mg alloy ring, which seals a gas plenum, to high velocity, releasing the gas. Both coil and ring are profiled to minimize stress in the ring. Such a device could be used to supply the initial gas load for a proposed 5 MJ Dense Plasma Focus driven by AFRL's Shiva Star Capacitor bank. The intent here is keep the vacuum current feed insulator under high vacuum during the discharge to avoid surface breakdown. Alternatively, a high energy rep ratable plasma flow opening switch could be supplied with such a valve. This work is funded by the USAF.

  13. Universal Behavior of the BEC Critical Temperature for a Multi-slab Ideal Bose Gas

    Science.gov (United States)

    Rodríguez, O. A.; Solís, M. A.

    2016-05-01

    For an ideal Bose gas within a multi-slab periodic structure, we discuss the effect of the spatial distribution of the gas on its Bose-Einstein condensation critical temperature T_c, as well as on the origin of its dimensional crossover observed in the specific heat. The multi-slabs structure is generated by applying a Kronig-Penney potential to the gas in the perpendicular direction to the slabs of width b and separated by a distance a, and allowing the particles to move freely in the other two directions. We found that T_c decreases continuously as the potential barrier height increases, becoming inversely proportional to the square root of the barrier height when it is large enough. This behavior is universal as it is independent of the width and spacing of the barriers. The specific heat at constant volume shows a crossover from 3D to 2D when the height of the potential or the barrier width increases, in addition to the well-known peak related to the Bose-Einstein condensation. These features are due to the trapping of the bosons by the potential barriers and can be characterized by the energy difference between the energy bands below the potential height.

  14. Analysis of Critical Permeabilty, Capillary Pressure and Electrical Properties for Mesaverde Tight Gas Sandstones from Western U.S. Basins

    Energy Technology Data Exchange (ETDEWEB)

    Alan Byrnes; Robert Cluff; John Webb; John Victorine; Ken Stalder; Daniel Osburn; Andrew Knoderer; Owen Metheny; Troy Hommertzheim; Joshua Byrnes; Daniel Krygowski; Stefani Whittaker

    2008-06-30

    Although prediction of future natural gas supply is complicated by uncertainty in such variables as demand, liquefied natural gas supply price and availability, coalbed methane and gas shale development rate, and pipeline availability, all U.S. Energy Information Administration gas supply estimates to date have predicted that Unconventional gas sources will be the dominant source of U.S. natural gas supply for at least the next two decades (Fig. 1.1; the period of estimation). Among the Unconventional gas supply sources, Tight Gas Sandstones (TGS) will represent 50-70% of the Unconventional gas supply in this time period (Fig. 1.2). Rocky Mountain TGS are estimated to be approximately 70% of the total TGS resource base (USEIA, 2005) and the Mesaverde Group (Mesaverde) sandstones represent the principal gas productive sandstone unit in the largest Western U.S. TGS basins including the basins that are the focus of this study (Washakie, Uinta, Piceance, northern Greater Green River, Wind River, Powder River). Industry assessment of the regional gas resource, projection of future gas supply, and exploration programs require an understanding of reservoir properties and accurate tools for formation evaluation. The goal of this study is to provide petrophysical formation evaluation tools related to relative permeability, capillary pressure, electrical properties and algorithms for wireline log analysis. Detailed and accurate moveable gas-in-place resource assessment is most critical in marginal gas plays and there is need for quantitative tools for definition of limits on gas producibility due to technology and rock physics and for defining water saturation. The results of this study address fundamental questions concerning: (1) gas storage; (2) gas flow; (3) capillary pressure; (4) electrical properties; (5) facies and upscaling issues; (6) wireline log interpretation algorithms; and (7) providing a web-accessible database of advanced rock properties. The following text

  15. Experiment and Simulation Study on the Special Phase Behavior of Huachang Near-Critical Condensate Gas Reservoir Fluid

    Directory of Open Access Journals (Sweden)

    Dali Hou

    2016-01-01

    Full Text Available Due to the special phase behavior of near-critical fluid, the development approaches of near-critical condensate gas and near-critical volatile oil reservoirs differ from conventional oil and gas reservoirs. In the near-critical region, slightly reduced pressure may result in considerable change in gas and liquid composition since a large amount of gas or retrograde condensate liquid is generated. It is of significance to gain insight into the composition variation of near-critical reservoir during the depletion development. In our study, we performed a series of PVT experiments on a real near-critical gas condensate reservoir fluid. In addition to the experimental studies, a commercial simulator combined with the PREOS model was utilized to study retrograde condensate characteristics and reevaporation mechanism of condensate oil with CO2 injection based on vapor-liquid phase equilibrium thermodynamic theory. The research shows that when reservoir pressure drops below a certain pressure, the variation of retrograde condensate liquid saturation of the residual reservoir fluid exhibits the phase behavior of volatile oil.

  16. Thermal Hydraulics of the Very High Temperature Gas Cooled Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Chang Oh; Eung Kim; Richard Schultz; Mike Patterson; Davie Petti

    2009-10-01

    The U.S Department of Energy (DOE) is conducting research on the Very High Temperature Reactor (VHTR) design concept for the Next Generation Nuclear Plant (NGNP) Project. The reactor design will be a graphite moderated, thermal neutron spectrum reactor that will produce electricity and hydrogen in a highly efficient manner. The NGNP reactor core will be either a prismatic graphite block type core or a pebble bed core. The NGNP will use very high-burnup, low-enriched uranium, TRISO-coated fuel, and have a projected plant design service life of 60 years. The VHTR concept is considered to be the nearest-term reactor design that has the capability to efficiently produce hydrogen. The plant size, reactor thermal power, and core configuration will ensure passive decay heat removal without fuel damage or radioactive material releases during reactor core-accidents. The objectives of the NGNP Project are to: Demonstrate a full-scale prototype VHTR that is commercially licensed by the U.S. Nuclear Regulatory Commission, and Demonstrate safe and economical nuclear-assisted production of hydrogen and electricity. The DOE laboratories, led by the INL, perform research and development (R&D) that will be critical to the success of the NGNP, primarily in the areas of: • High temperature gas reactor fuels behavior • High temperature materials qualification • Design methods development and validation • Hydrogen production technologies • Energy conversion. This paper presents current R&D work that addresses fundamental thermal hydraulics issues that are relevant to a variety of possible NGNP designs.

  17. Measurements of the Coexistence Curve near the Liquid-Gas Critical Point

    Science.gov (United States)

    Hahn, Inseob

    2003-01-01

    The shape of the liquid-gas coexistence curve of He-3 very near the critical point (-2x10(exp -6) < t < -5x10(exp -3) was measured using the quasi-static thermogram method. The study was performed in Earth s gravitational field using two different height calorimetry cells, both originally designed for simultaneous measurements of the isochoric heat capacity, isothermal compressibility, and PVT. The heights of two cells were 0.5 mm and 4.8 cm. The uncertainty in measuring the phase transition temperature was typically +/-2 micro-K. The measured coexistence curve near the critical point was strongly affected by the gravitational field. Away from the critical point, the coexistence curve obtained using this technique was also consistent with the earlier work using the local density measurements of Pittman et al. The recent crossover parametric model of the equation-of-state are used to analyze the height-dependent measured coexistence curves. Data analyses have indicated that microgravity will permit measurements within two additional decades in reduced temperatures beyond the best gravity-free data obtained in Earth-bound experiments.

  18. High quality fuel gas from biomass pyrolysis with calcium oxide.

    Science.gov (United States)

    Zhao, Baofeng; Zhang, Xiaodong; Chen, Lei; Sun, Laizhi; Si, Hongyu; Chen, Guanyi

    2014-03-01

    The removal of CO2 and tar in fuel gas produced by biomass thermal conversion has aroused more attention due to their adverse effects on the subsequent fuel gas application. High quality fuel gas production from sawdust pyrolysis with CaO was studied in this paper. The results of pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) experiments indicate that the mass ratio of CaO to sawdust (Ca/S) remarkably affects the behavior of sawdust pyrolysis. On the basis of Py-GC/MS results, one system of a moving bed pyrolyzer coupled with a fluid bed combustor has been developed to produce high quality fuel gas. The lower heating value (LHV) of the fuel gas was above 16MJ/Nm(3) and the content of tar was under 50mg/Nm(3), which is suitable for gas turbine application to generate electricity and heat. Therefore, this technology may be a promising route to achieve high quality fuel gas for biomass utilization.

  19. Microstructures and critical currents in high-{Tc} superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Suenaga, Masaki

    1998-11-01

    Microstructural defects are the primary determining factors for the values of critical-current densities in a high {Tc} superconductor after the electronic anisotropy along the a-b plane and the c-direction. A review is made to assess firstly what would be the maximum achievable critical-current density in YBa{sub 2}Cu{sub 3}O{sub 7} if nearly ideal pinning sites were introduced and secondly what types of pinning defects are currently introduced or exist in YBa{sub 2}Cu{sub 3}O{sub 7} and how effective are these in pinning vortices.

  20. The high pressure gas Cerenkov counter at the Omega Facility.

    CERN Multimedia

    1975-01-01

    The high-pressure gas Cerenkov was used to measure reactions as pion (or kaon)- hydrogen --> forward proton - X. It was built by the Ecole Polytechnique (Palaiseu). Here Peter Sonderegger and Patrick Fleury,

  1. The highly ionized, high-velocity gas in NGC 6231

    Science.gov (United States)

    Massa, Derck

    2017-02-01

    It is well known that clusters of massive stars are influenced by the presence of strong winds, that they are sources of diffuse X-rays from shocked gas, and that this gas can be vented into the surrounding region or the halo through the champagne effect. However, the details of how these different environments interact and evolve are far from complete. This paper attributes the broad C IVλλ1500 absorption features (extending to -1900 km s-1) that are seen in the spectra of main sequence B stars in NGC 6231 to gas in the cluster environment and not the B stars themselves. It is shown that the presence of a WC star, WR 79, in the cluster makes this gas detectable because its wind enriches the cluster gas with carbon. Given the available data, it is not clear whether the absorbing gas is simply the far wind of WR 79 or a collective cluster wind enriched by carbon from the wind of WR 79. If it is simply due to the wind, then this wind must flow, unimpeded for more than 2 pc, suggesting that the inner region of the cluster is nearly devoid of obstructing material. If it is actually a collective wind from the cluster, then we could be witnessing an important stage of galactic feedback. In either case, the observations provide a unique and significant piece to the puzzle of how massive, open clusters evolve.

  2. The highly ionized, high velocity gas in NGC 6231

    CERN Document Server

    Massa, Derck

    2016-01-01

    It is well known that clusters of massive stars are influenced by the presence of strong winds, that they are sources of diffuse X-rays from shocked gas, and that this gas can be vented into the surrounding region or the halo through the champagne effect. However, the details of how these different environments interact and evolve are far from complete. This paper attributes the broad C IV 1500 absorption features (extending to -1900 \\kms) that are seen in the spectra of main sequence B stars in NGC 6231 to gas in the cluster environment and not the B stars themselves. It is shown that the presence of a WC star, WR 79, in the cluster makes this gas detectable because its wind enriches the cluster gas with carbon. Given the available data, it is not clear whether the absorbing gas is simply the far wind of WR 79 or a collective cluster wind enriched by carbon from the wind of WR 79. If it is simply due to the wind, then this wind must flow, unimpeded for more than 2 pc, suggesting that the inner region of the ...

  3. High Power Light Gas Helicon Plasma Source For VASMIR

    Science.gov (United States)

    Squire, J. P.; Chang-Diaz, F. R.; Glover, T. W.; Jacobson, V. T.; McCaskill, G. E.; Winter, D. S.; Baity, F. W.; Carter, M. D.; Goulding, R. H.

    2004-01-01

    The VASIMR space propulsion development effort relies on a high power (greater than 10kW) helicon source to produce a dense flowing plasma (H, D and He) target for ion cyclotron resonance (ICR) acceleration of the ions. Subsequent expansion in an expanding magnetic field (magnetic nozzle) converts ion lunetic energy to directed momentum. This plasma source must have critical features to enable an effective propulsion device. First, it must ionize most of the input neutral flux of gas, thus producing a plasma stream with a high degree of ionization for application of ICR power. This avoids propellant waste and potential power losses due to charge exchange. Next, the plasma stream must flow into a region of high magnetic field (approximately 0.5 T) for efficient ICR acceleration. Third, the ratio of input power to plasma flux must be low, providing an energy per ion-electron pair approaching 100 eV. Lastly, the source must be robust and capable of very long life-times (years). In our helicon experiment (VX-10) we have measured a ratio of input gas to plasma flux near 100%. The plasma flows from the helicon region (B approximately 0.1 T) into a region with a peak magnetic field of 0.8 T. The energy input per ion-electron pair has been measured at 300 plus or minus 100 eV. Recent results at Oak Ridge National Laboratory (ORNL) show an enhanced efficiency mode of operation with a high power density, over 5 kW in a 5 cm diameter tube. Our helicon is presently 9 cm in diameter and operates up to 3.5 kW of input power. An upgrade to a power level of 10 kW is underway. Much of our recent work has been with a Boswell double-saddle antenna design. We are also converting the antenna design to a helical type. With these modifications, we anticipate an improvement in the ionization efficiency. This paper presents the results from scaling the helicon in the VX-10 device from 3.5 to 10 kW. We also compare the operation with a double-saddle to a helical antenna design. Finally, we

  4. High Power Light Gas Helicon Plasma Source For VASMIR

    Science.gov (United States)

    Squire, J. P.; Chang-Diaz, F. R.; Glover, T. W.; Jacobson, V. T.; McCaskill, G. E.; Winter, D. S.; Baity, F. W.; Carter, M. D.; Goulding, R. H.

    2004-01-01

    The VASIMR space propulsion development effort relies on a high power (greater than 10kW) helicon source to produce a dense flowing plasma (H, D and He) target for ion cyclotron resonance (ICR) acceleration of the ions. Subsequent expansion in an expanding magnetic field (magnetic nozzle) converts ion lunetic energy to directed momentum. This plasma source must have critical features to enable an effective propulsion device. First, it must ionize most of the input neutral flux of gas, thus producing a plasma stream with a high degree of ionization for application of ICR power. This avoids propellant waste and potential power losses due to charge exchange. Next, the plasma stream must flow into a region of high magnetic field (approximately 0.5 T) for efficient ICR acceleration. Third, the ratio of input power to plasma flux must be low, providing an energy per ion-electron pair approaching 100 eV. Lastly, the source must be robust and capable of very long life-times (years). In our helicon experiment (VX-10) we have measured a ratio of input gas to plasma flux near 100%. The plasma flows from the helicon region (B approximately 0.1 T) into a region with a peak magnetic field of 0.8 T. The energy input per ion-electron pair has been measured at 300 plus or minus 100 eV. Recent results at Oak Ridge National Laboratory (ORNL) show an enhanced efficiency mode of operation with a high power density, over 5 kW in a 5 cm diameter tube. Our helicon is presently 9 cm in diameter and operates up to 3.5 kW of input power. An upgrade to a power level of 10 kW is underway. Much of our recent work has been with a Boswell double-saddle antenna design. We are also converting the antenna design to a helical type. With these modifications, we anticipate an improvement in the ionization efficiency. This paper presents the results from scaling the helicon in the VX-10 device from 3.5 to 10 kW. We also compare the operation with a double-saddle to a helical antenna design. Finally, we

  5. Gas related effects on multi-gap RPC performance in high luminosity experiments

    Science.gov (United States)

    Lyu, P.; Wang, Y.; Guo, B.; Han, D.; Xie, B.; Li, Y.; Wang, F.

    2016-11-01

    The Multi-gap Resistive Plate Chamber (MRPC) is a new type of gas detector developed in recent years. It has excellent time resolution (better than 100 ps) and high efficiency (higher than 95%). This detector has been used to construct large-area time-of-flight (TOF) system in many nuclear and particle physics experiments. However, as a type of gaseous detector, the aging of the gas mixture under long-time exposure to ionizing radiation cannot be neglected. With the increase of accelerator luminosity, impurities in the gas mixture can be potentially dangerous for long-term operation of the MRPC. This has been observed in some experiments, for example with the RHIC-STAR muon telescope detector. The CBM-TOF, used for hadron identification, is proposed to be assembled with MRPCs. These counters have to stand particle fluxes as high as 25 kHz/cm2, and thus the gas pollution is a critical aspect to be studied. In order to better understand the gas quality's impact on the MRPC performance, a two-dimensional simulation based on the SIMPLE algorithm is carried out to imitate the distribution of impurities in a MRPC gas box. The preliminary results show that gas pollution grows stronger with the increase of the gas-flowing volume. In addition, we conducted a series of experiments with a 50 × 50 cm2, 8-gap MRPC prototype. The results match the simulation quite well. Gas pollution indeed has a severe impact on the MRPC performance, and further study can be very useful to reduce gas aging effects in high-luminosity experiments.

  6. Unexpected inhibition of CO2 gas hydrate formation in dilute TBAB solutions and the critical role of interfacial water structure

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Ngoc N.; Nguyen, Anh V.; Nguyen, Khoi T.; Rintoul, Llew; Dang, Liem X.

    2016-12-01

    Gas hydrates formed under moderated conditions open up novel approaches to tackling issues related to energy supply, gas separation, and CO2 sequestration. Several additives like tetra-n-butylammonium bromide (TBAB) have been empirically developed and used to promote gas hydrate formation. Here we report unexpected experimental results which show that TBAB inhibits CO2 gas hydrate formation when used at minuscule concentration. We also used spectroscopic techniques and molecular dynamics simulation to gain further insights and explain the experimental results. They have revealed the critical role of water alignment at the gas-water interface induced by surface adsorption of tetra-n-butylammonium cation (TBA+) which gives rise to the unexpected inhibition of dilute TBAB solution. The water perturbation by TBA+ in the bulk is attributed to the promotion effect of high TBAB concentration on gas hydrate formation. We explain our finding using the concept of activation energy of gas hydrate formation. Our results provide a step toward to mastering the control of gas hydrate formation.

  7. Determination of Critical Parameters Based on the Intensity of Transmitted Light Around Gas-Liquid Interface: Critical Parameters of CO

    Science.gov (United States)

    Nakayama, Masaki; Katano, Hiroaki; Sato, Haruki

    2014-05-01

    A precise determination of the critical temperature and density for technically important fluids would be possible on the basis of the digital image for the visual observation of the phase boundary in the vicinity of the critical point since the sensitivity and resolution are higher than those of naked eyes. In addition, the digital image can avoid the personal uncertainty of an observer. A strong density gradient occurs in a sample cell at the critical point due to gravity. It was carefully assessed to determine the critical density, where the density profile in the sample cell can be observed from the luminance profile of a digital image. The density-gradient profile becomes symmetric at the critical point. One of the best fluids, whose thermodynamic properties have been measured with the highest reliability among technically important fluids, would be carbon dioxide. In order to confirm the reliability of the proposed method, the critical temperature and density of carbon dioxide were determined using the digital image. The critical temperature and density values of carbon dioxide are ( and ( kg m, respectively. The critical temperature and density values agree with the existing best values within estimated uncertainties. The reliability of the method was confirmed. The critical pressure, 7.3795 MPa, corresponding to the determined critical temperature of 304.143 K is also proposed. A new set of parameters for the vapor-pressure equation is also provided.

  8. Electrochemistry of single nanobubbles. Estimating the critical size of bubble-forming nuclei for gas-evolving electrode reactions.

    Science.gov (United States)

    German, Sean R; Edwards, Martin A; Chen, Qianjin; Liu, Yuwen; Luo, Long; White, Henry S

    2016-12-12

    In this article, we address the fundamental question: "What is the critical size of a single cluster of gas molecules that grows and becomes a stable (or continuously growing) gas bubble during gas evolving reactions?" Electrochemical reactions that produce dissolved gas molecules are ubiquitous in electrochemical technologies, e.g., water electrolysis, photoelectrochemistry, chlorine production, corrosion, and often lead to the formation of gaseous bubbles. Herein, we demonstrate that electrochemical measurements of the dissolved gas concentration, at the instant prior to nucleation of an individual nanobubble of H2, N2, or O2 at a Pt nanodisk electrode, can be analyzed using classical thermodynamic relationships (Henry's law and the Young-Laplace equation - including non-ideal corrections) to provide an estimate of the size of the gas bubble nucleus that grows into a stable bubble. We further demonstrate that this critical nucleus size is independent of the radius of the Pt nanodisk employed (gas. For example, the measured critical surface concentration of H2 of ∼0.23 M at the instant of bubble formation corresponds to a critical H2 nucleus that has a radius of ∼3.6 nm, an internal pressure of ∼350 atm, and contains ∼1700 H2 molecules. The data are consistent with stochastic fluctuations in the density of dissolved gas, at or near the Pt/solution interface, controlling the rate of bubble nucleation. We discuss the growth of the nucleus as a diffusion-limited process and how that process is affected by proximity to an electrode producing ∼10(11) gas molecules per second. Our study demonstrates the advantages of studying a single-entity, i.e., an individual nanobubble, in understanding and quantifying complex physicochemical phenomena.

  9. Dense gas in high-latitude molecular clouds

    Energy Technology Data Exchange (ETDEWEB)

    Reach, W.R.; Pound, M.W.; Wilner, D.J. (Univ. of California, Berkeley (United States)); Lee, Y.

    1992-01-01

    The authors have surveyed high-latitude molecular clouds (MBM 12, 7, 55, 40) in spectral lines that are believed to be dense-gas' tracers due to the high H[sub 2] volume density required for collisional excitation. An extensive CS (2-1) line map of MBM 12 revealed emission that is not confined to clumps. Less than 20% of the integrated line emission from the cloud originates in clearly identified clumps with size between 0.2 pc and 0.02 pc in the integrated line map. The bulk of the emission originates from a relatively smooth horseshoe' structure about 0.1 pc wide and 1 pc long. The CS (2-1) map correlates with the published Bell Labs [sup 13] CO map, with significant [sup 13] CO emission even where the CS emission is undetectable. Within the central core, the C[sup 18]O(1-0) and CS(2-1) lines are positively correlated with significant scatter. There is some indication of higher CS/[sup 13]CO in the cores than the horseshoe'. The observed correlations suggest that both the diffuse CS and [sup 13]CO originate from either numerous, unresolved clumps, or the diffuse parts of the cloud. High-spatial-resolution observations of HCO[sup +] from MBM 12 obtained with the BIMA Hat Creek array demonstrated that the main core emission is primarily on spatial scales greater than 0.004 pc. It appears that the authors have resolved most of the spatial structure of the dense-gas' tracers and have found that the emission is primarily diffuse. To understand the excitation mechanism of the CS rotational levels, a multitransitional study of the 1-0, 2-1, and 3-2 lines is being performed. The CS excitation may be governed by electron collisions in regions with H[sub 2] column densities an order of magnitude lower than the critical density' of [approx gt] 2 [times] 10[sup 4] cm[sup -3]. If electron collisions are populating the CS levels, then the CS and [sup 13]CO lines can both be produced in the outer parts of the cloud, explaining their positive correlation

  10. Approach to Achieve High Availability in Critical Infrastructure

    Science.gov (United States)

    2015-09-01

    Regardless, current technology includes RFID tags for systems, and tablets can be implemented to assist in real-time updates. Current Wi-Fi technology can...APPROACH TO ACHIEVE HIGH AVAILABILITY IN CRITICAL INFRASTRUCTURE Yew Kee Hoo Senior Engineer, Defence Science and Technology Agency, Singapore B.E...Between Failure MTTF Mean Time to Repair NAVFAC Naval Facilities Engineering Command xvi O&M Operations and Maintenance RFID Radio Frequency

  11. CRITICAL ISSUES IN HIGH END COMPUTING - FINAL REPORT

    Energy Technology Data Exchange (ETDEWEB)

    Corones, James [Krell Institute

    2013-09-23

    High-End computing (HEC) has been a driver for advances in science and engineering for the past four decades. Increasingly HEC has become a significant element in the national security, economic vitality, and competitiveness of the United States. Advances in HEC provide results that cut across traditional disciplinary and organizational boundaries. This program provides opportunities to share information about HEC systems and computational techniques across multiple disciplines and organizations through conferences and exhibitions of HEC advances held in Washington DC so that mission agency staff, scientists, and industry can come together with White House, Congressional and Legislative staff in an environment conducive to the sharing of technical information, accomplishments, goals, and plans. A common thread across this series of conferences is the understanding of computational science and applied mathematics techniques across a diverse set of application areas of interest to the Nation. The specific objectives of this program are: Program Objective 1. To provide opportunities to share information about advances in high-end computing systems and computational techniques between mission critical agencies, agency laboratories, academics, and industry. Program Objective 2. To gather pertinent data, address specific topics of wide interest to mission critical agencies. Program Objective 3. To promote a continuing discussion of critical issues in high-end computing. Program Objective 4.To provide a venue where a multidisciplinary scientific audience can discuss the difficulties applying computational science techniques to specific problems and can specify future research that, if successful, will eliminate these problems.

  12. Methods to assess high-resolution subsurface gas concentrations and gas fluxes in wetland ecosystems

    DEFF Research Database (Denmark)

    Elberling, Bo; Kühl, Michael; Glud, Ronnie N.

    2013-01-01

    The need for measurements of soil gas concentrations and surface fluxes of greenhouse gases at high temporal and spatial resolution in wetland ecosystem has lead to the introduction of several new analytical techniques and methods. In addition to the automated flux chamber methodology for high......-resolution estimates of greenhouse gas fluxes across the soil-atmosphere interface, these high-resolution methods include microsensors for quantification of spatiotemporal concentration dynamics in O2 and N2O at micrometer scales, fiber-optic optodes for long-term continuous point measurements of O2 concentrations...... and peat soils are highly heterogeneous, containing a mosaic of dynamic macropore systems created by both macrofauna and flora leading to distinct spatial and temporal variations in gas concentration on a scale of millimeters and minutes. Applications of these new methodologies allow measurements...

  13. Noble Gas Clusters and Nanoplasmas in High Harmonic Generation

    CERN Document Server

    Aladi, M; Rácz, P; Földes, I B

    2015-01-01

    We report a study of high harmonic generation from noble gas clusters of xenon atoms in a gas jet. Harmonic spectra were investigated as a function of backing pressure, showing spectral shifts due to the nanoplasma electrons in the clusters. At certain value of laser intensity this process may oppose the effect of the well-known ionization-induced blueshift. In addition, these cluster-induced harmonic redshifts may give the possibility to estimate cluster density and cluster size in the laser-gas jet interaction range.

  14. High-power FEL design issues - a critical review

    Energy Technology Data Exchange (ETDEWEB)

    Litvinenko, V.N.; Madey, J.M.J.; O`Shea, P.G. [Duke Univ., Durham, NC (United States)

    1995-12-31

    The high-average power capability of FELs has been much advertised but little realized. In this paper we provide a critical analysis of the technological and economic issues associated with high-average power FEL operation from the UV to near IR. The project of IR FEL for the Siberian Center of photochemical researches is described. The distinguished features of this project are the use of the race-track microtron-recuperator and the {open_quotes}electron output of radiation{close_quotes}. The building for the machine is under reconstruction now. About half of hardware has been manufactured. The assembly of installation began.

  15. A Fisher’s Criterion-Based Linear Discriminant Analysis for Predicting the Critical Values of Coal and Gas Outbursts Using the Initial Gas Flow in a Borehole

    Directory of Open Access Journals (Sweden)

    Xiaowei Li

    2017-01-01

    Full Text Available The risk of coal and gas outbursts can be predicted using a method that is linear and continuous and based on the initial gas flow in the borehole (IGFB; this method is significantly superior to the traditional point prediction method. Acquiring accurate critical values is the key to ensuring accurate predictions. Based on ideal rock cross-cut coal uncovering model, the IGFB measurement device was developed. The present study measured the data of the initial gas flow over 3 min in a 1 m long borehole with a diameter of 42 mm in the laboratory. A total of 48 sets of data were obtained. These data were fuzzy and chaotic. Fisher’s discrimination method was able to transform these spatial data, which were multidimensional due to the factors influencing the IGFB, into a one-dimensional function and determine its critical value. Then, by processing the data into a normal distribution, the critical values of the outbursts were analyzed using linear discriminant analysis with Fisher’s criterion. The weak and strong outbursts had critical values of 36.63 L and 80.85 L, respectively, and the accuracy of the back-discriminant analysis for the weak and strong outbursts was 94.74% and 92.86%, respectively. Eight outburst tests were simulated in the laboratory, the reverse verification accuracy was 100%, and the accuracy of the critical value was verified.

  16. Instrument for thermal radiation flux measurement in high temperature gas flow (Cuernavaca instrument)

    Energy Technology Data Exchange (ETDEWEB)

    Afgan, N.H. [Universidade Tecnica, Lisbon (Portugal); Leontiev, A.I. [Moscow State Technical University (Russian Federation)

    1995-05-01

    A new instrument for hemispherical radiation heat flux measurement is proposed. It is based on the theory of blow of the boundary layer, taking into account that at the critical mass flow rate through the porous surface the thermal boundary layer is blown off and only radiation flux from high temperature gases reaches the porous surface. With the measurement of blow of gas flow and the temperature of the porous material, the respective heat flux is obtained. (author)

  17. High-quality Critical Heat Flux in Horizontally Coiled Tubes

    Institute of Scientific and Technical Information of China (English)

    1995-01-01

    An investigation on the high-quality dryout in two electrically heated coiled tubes with horizontally helix axes is reported.The temperature profiles both along the tube and around the circumference are measured.and it is found that the temperature profiles around the circumference are not identical for the corss-sections at different parts of the coil.The “local condition hypothesis” seems applicable under present conditions,and the critical heat flux qcr decreases with increasing critical quality xcr.The CHF increases as mass velocity and ratio of tube diameter to coil diameter(d/D) increases,and it seems not to be affected hby the system pressure.The CHF is larger with coils than that with straight tubes,and the difference increases with increasing mass velocity and d/D.

  18. High critical field NbC superconductor on carbon spheres.

    Science.gov (United States)

    Bhattacharjee, Kaustav; Pati, Satya Prakash; Maity, Arjun

    2016-06-01

    Niobium carbide (NbC) nanoparticles embedded on the surface of carbon spheres (CS) were synthesized at 1350 °C by the carbothermal reduction of niobium oxide precursor in flowing argon (Nbc@CS). The morphology, crystal structure, and magnetic properties of the hybrid nanocomposite were investigated by means of electron microscopy, X-ray diffraction and a superconducting quantum interference device. It was found that the NbC@CS nanocomposites exhibit type-II superconductivity with a critical temperature (Tc) of 8-12 K, typical for stoichiometric NbC. The superconducting hysteresis loop reveals several interesting traits, including strong vortex pinning, the presence of asymmetry and a high penetration field. Moreover, the sample shows much improved irreversible (Hirr), lower (Hc1) and upper (Hc2) critical fields. The coherence length (ξ), penetration depth (λ), and Ginzburg-Landau (κ) parameters for the sample were estimated to be 9.78 nm, 33 nm and 3.39, respectively.

  19. Properties of high-temperature phase diagram and critical point parameters in silica

    CERN Document Server

    Iosilevskiy, Igor; Solov'ev, Alexander

    2013-01-01

    Some uncertainties are discussed on the high-temperature phase boundaries and critical point parameters for gas-liquid phase transition in silica (SiO2). The thermal and caloric phase diagrams are compared and examined as being predicted by various theoretical approaches, such as the quasi-chemical representation, the wide-range semi-empirical equation of state and the ionic model under direct molecular dynamic simulation. The theoretical predictions are confronted with handbook recommendations and scanty experimental data on the equilibrium vapor composition over SiO2 boiling. Validity of conventional semi-empirical rules is tested for the theoretically predicted SiO2-phase diagrams. The non-congruence of gas-liquid phase transition in SiO2 is considered for this matter to be used as a modeling body to study the non-congruent evaporation in uranium dioxide and other uranium-bearing fuels at both existing and perspective nuclear reactors.

  20. Optical depth estimates and effective critical densities of dense gas tracers in the inner parts of nearby galaxy discs

    Science.gov (United States)

    Jiménez-Donaire, M. J.; Bigiel, F.; Leroy, A. K.; Cormier, D.; Gallagher, M.; Usero, A.; Bolatto, A.; Colombo, D.; García-Burillo, S.; Hughes, A.; Kramer, C.; Krumholz, M. R.; Meier, D. S.; Murphy, E.; Pety, J.; Rosolowsky, E.; Schinnerer, E.; Schruba, A.; Tomičić, N.; Zschaechner, L.

    2017-04-01

    High critical density molecular lines like HCN (1-0) or HCO+ (1-0) represent our best tool to study currently star-forming, dense molecular gas at extragalactic distances. The optical depth of these lines is a key ingredient to estimate the effective density required to excite emission. However, constraints on this quantity are even scarcer in the literature than measurements of the high-density tracers themselves. Here, we combine new observations of HCN, HCO+ and HNC (1-0) and their optically thin isotopologues H13CN, H13CO+ and HN13C (1-0) to measure isotopologue line ratios. We use IRAM 30-m observations from the large programme EMPIRE and new Atacama Large Millimetre/submillimetre Array observations, which together target six nearby star-forming galaxies. Using spectral stacking techniques, we calculate or place strong upper limits on the HCN/H13CN, HCO+/H13CO+ and HNC/HN13C line ratios in the inner parts of these galaxies. Under simple assumptions, we use these to estimate the optical depths of HCN (1-0) and HCO+ (1-0) to be τ ∼ 2-11 in the active, inner regions of our targets. The critical densities are consequently lowered to values between 5 and 20 × 105 cm-3, 1 and 3 × 105 cm-3 and 9 × 104 cm-3 for HCN, HCO+ and HNC, respectively. We study the impact of having different beam-filling factors, η, on these estimates and find that the effective critical densities decrease by a factor of η _{12}/η _{13} τ_{12}. A comparison to existing work in NGC 5194 and NGC 253 shows the HCN/H13CN and HCO+/H13CO+ ratios in agreement with our measurements within the uncertainties. The same is true for studies in other environments such as the Galactic Centre or nuclear regions of active galactic nucleus dominated nearby galaxies.

  1. Effect of the Concentration of a Combustible Gas on the Limiting Critical Conditions of Its Catalytic Oxidation

    Science.gov (United States)

    Kalinchak, V. V.; Chernenko, A. S.; Kalugin, V. V.

    2015-05-01

    For the case of the cold, relative to a gas mixture, walls of an apparatus and radiation heat transfer, an investigation is made of the dependence of the limiting minimum gas mixture temperatures above which catalytic self-ignition and firing of a low-concentration combustible gas on a catalyst particle are possible. The proposed method is based on obtaining the desired dependences in a parametric form. An analysis of the degeneration of critical temperatures and of ignition and extinction diameters is carried out.

  2. Compressed gas domestic aerosol valve design using high viscous product

    Directory of Open Access Journals (Sweden)

    A Nourian

    2016-10-01

    Full Text Available Most of the current universal consumer aerosol products using high viscous product such as cooking oil, antiperspirants, hair removal cream are primarily used LPG (Liquefied Petroleum Gas propellant which is unfriendly environmental. The advantages of the new innovative technology described in this paper are: i. No butane or other liquefied hydrocarbon gas is used as a propellant and it replaced with Compressed air, nitrogen or other safe gas propellant. ii. Customer acceptable spray quality and consistency during can lifetime iii. Conventional cans and filling technology There is only a feasible energy source which is inert gas (i.e. compressed air to replace VOCs (Volatile Organic Compounds and greenhouse gases, which must be avoided, to improve atomisation by generating gas bubbles and turbulence inside the atomiser insert and the actuator. This research concentrates on using "bubbly flow" in the valve stem, with injection of compressed gas into the passing flow, thus also generating turbulence. The new valve designed in this investigation using inert gases has advantageous over conventional valve with butane propellant using high viscous product (> 400 Cp because, when the valving arrangement is fully open, there are negligible energy losses as fluid passes through the valve from the interior of the container to the actuator insert. The use of valving arrangement thus permits all pressure drops to be controlled, resulting in improved control of atomising efficiency and flow rate, whereas in conventional valves a significant pressure drops occurs through the valve which has a complex effect on the corresponding spray.

  3. Critical buckling strain in high strength steel pipes using isotropic kinematic hardening

    Energy Technology Data Exchange (ETDEWEB)

    Fathi, A.; Roger Cheng, J. J.; Adeeb, Samer [Department of Civil and Environmental Engineering, University of Alberta (Canada); Zhou, Joe [TransCanada Pipelines Ltd. (Canada)

    2010-07-01

    In the natural gas sector, the use of high strength steel pipelines (HSSP) to transport huge volumes over long distances is increasing as it yields important savings in both capital and operational expenditures. In order to design HSSP, the critical buckling strain as to be taken into consideration but the models so far developed have been for isotropic materials while important material anisotropy is observed on HSSP due to their manufacturing process. The paper presents a model to assess the critical buckling strain of HSSP. An isotropic-kinematic hardening material model was developed and isotropic and anisotropic models were used to simulate pressurized and non-pressurized HSSP and were compared to test results. Results showed that the isotropic model is not suitable for predicting the buckling strain of HSSP but that the isotropic-kinematic hardening material model is. A model to better predict the buckling strain of HSSP was developed and successfully tested herein.

  4. Planet traps and first planets: The critical metallicity for gas giant formation

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, Yasuhiro; Hirashita, Hiroyuki, E-mail: yasu@asiaa.sinica.edu.tw, E-mail: hirashita@asiaa.sinica.edu.tw [Institute of Astronomy and Astrophysics, Academia Sinica (ASIAA), P.O. Box 23-141, Taipei 10617, Taiwan (China)

    2014-06-10

    The ubiquity of planets poses an interesting question: when are first planets formed in galaxies? We investigate this by adopting a theoretical model where planet traps are combined with the standard core accretion scenario in which the efficiency of forming planetary cores directly relates to the metallicity ([Fe/H]) in disks. Three characteristic exoplanetary populations are examined: hot Jupiters, exo-Jupiters around 1 AU, and low-mass planets in tight orbits, such as super-Earths. We statistically compute planet formation frequencies (PFFs), as well as the orbital radius (〈R{sub rapid}〉) within which gas accretion becomes efficient enough to form Jovian planets, as a function of metallicity (–2 ≤ [Fe/H] ≤–0.6). We show that the total PFFs for these three populations increase steadily with metallicity. This is the direct outcome of the core accretion picture. For the metallicity range considered here, the population of low-mass planets dominates Jovian planets. The Jovian planets contribute to the PFFs above [Fe/H] ≅ –1. We find that the hot Jupiters form more efficiently than the exo-Jupiters at [Fe/H] ≲ –0.7. This arises from the slower growth of planetary cores and their more efficient radial inward transport by the host traps in lower metallicity disks. We show that the critical metallicity for forming Jovian planets is [Fe/H] ≅ –1.2 by comparing 〈R{sub rapid}〉 of hot Jupiters and low-mass planets. The comparison intrinsically links to the different gas accretion efficiency between these two types of planets. Therefore, this study implies that important physical processes in planet formation may be tested by exoplanet observations around metal-poor stars.

  5. Granular bed filtration of high temperature biomass gasification gas.

    Science.gov (United States)

    Stanghelle, Daniel; Slungaard, Torbjørn; Sønju, Otto K

    2007-06-18

    High temperature cleaning of producer gas from biomass gasification has been investigated with a granular filter. Field tests were performed for several hours on a single filter element at about 550 degrees C. The results show cake filtration on the granular material and indicate good filtration of the biomass gasification producer gas. The relatively low pressure drop over the filter during filtration is comparable to those of bag filters. The granular filter can operate with high filtration velocities compared to bag filters and maintain high efficiency and a low residual pressure. This work is a part of the BioSOFC-up project that has a goal of utilizing the producer gas from the gasification plant in a solid oxide fuel cell (SOFC). The BioSOFC-up project will continue to the end of 2007.

  6. William Morris and the critical utopia of high fantasy

    Directory of Open Access Journals (Sweden)

    Matic Večko

    2009-12-01

    Full Text Available The novels The Wood Beyond the World (1894 and The Weil at the World's End (1896 by William Morris are considered the formative works of the type of literature which has been labelled high fantasy. The latter is one of the commercially most successful genres of fantasy literature. The two novels are analysed from the perspective of critical utopianism as articulated through a distinc­tive type of aesthetic structure which was established in these works and has become characteristic of the high fantasy literature. The author of the article suggests that it is this complex of aesthetic structiire-aiid ifs iiiherent iitopian lmpulse which may be one of the important faciors-in the perennia popularity of high fantasy.

  7. Constraining cloud parameters using high density gas tracers in galaxies

    CERN Document Server

    Kazandjian, M V; Meijerink, R; Israel, F P; Coppola, C M; Rosenberg, M J F; Spaans, M

    2016-01-01

    Far-infrared molecular emission is an important tool used to understand the excitation mechanisms of the gas in the inter-stellar medium of star-forming galaxies. In the present work, we model the emission from rotational transitions with critical densities n >~ 10^4 cm-3. We include 4-3 ~ 30 in order to obtain significant emission from n > 10^4 cm-3 gas. Such Mach numbers are expected in star-forming galaxies, LIRGS, and ULIRGS. By fitting line ratios of HCN(1-0), HNC(1-0), and HCO+(1-0) for a sample of LIRGS and ULIRGS using mechanically heated PDRs, we constrain the Mach number of these galaxies to 29 < M < 77.

  8. Test of phi(sup 2) model predictions near the (sup 3)He liquid-gas critical point

    Science.gov (United States)

    Barmatz, M.; Zhong, F.; Hahn, I.

    2000-01-01

    NASA is supporting the development of an experiment called MISTE (Microgravity Scaling Theory Experiment) for future International Space Station mission. The main objective of this flight experiment is to perform in-situ PVT, heat capacity at constant volume, C(sub v) and chi(sub tau), measurements in the asymptotic region near the (sup 3)He liquid-gas critical point.

  9. Demystifying the Text: Literary Criticism in the High School Classroom.

    Science.gov (United States)

    Schade, Lisa

    1996-01-01

    Shows how one teacher answered student questions about how a particular piece of literature came to be regarded as worthy of in-depth examination. Proposes that students be taught about various critical approaches, including Jungian/archetypal criticism, formalism, reader-response criticism, socio-historical and biographical criticism, and…

  10. Demystifying the Text: Literary Criticism in the High School Classroom.

    Science.gov (United States)

    Schade, Lisa

    1996-01-01

    Shows how one teacher answered student questions about how a particular piece of literature came to be regarded as worthy of in-depth examination. Proposes that students be taught about various critical approaches, including Jungian/archetypal criticism, formalism, reader-response criticism, socio-historical and biographical criticism, and…

  11. Teaching Critical Thinking through Art History in High School.

    Science.gov (United States)

    Garoian, Charles R.

    1988-01-01

    Explains how the study of art history encourages the development of critical thinking in adolescents by comparing Bloom's Taxonomy of Educational Objectives with Feldman's stages of art criticism. Offers curriculum-based recommendations for using art history and criticism to encourage critical thinking. (LS)

  12. New perspectives in vacuum high voltage insulation. II. Gas desorption

    CERN Document Server

    Diamond, W T

    1998-01-01

    An examination has been made of gas desorption from unbaked electrodes of copper, niobium, aluminum, and titanium subjected to high voltage in vacuum. It has been shown that the gas is composed of water vapor, carbon monoxide, and carbon dioxide, the usual components of vacuum outgassing, plus an increased yield of hydrogen and light hydrocarbons. The gas desorption was driven by anode conditioning as the voltage was increased between the electrodes. The gas is often desorbed as microdischarges-pulses of a few to hundreds of microseconds-and less frequently in a more continuous manner without the obvious pulsed structure characteristic of microdischarge activity. The quantity of gas released was equivalent to many monolayers and consisted mostly of neutral molecules with an ionic component of a few percent. A very significant observation was that the gas desorption was more dependent on the total voltage between the electrodes than on the electric field. It was not triggered by field-emitted electrons but oft...

  13. The Physical Conditions of Atomic Gas at High Redshift

    Science.gov (United States)

    Neeleman, Marcel

    In this thesis we provide insight into the chemical composition, physical conditions and cosmic distribution of atomic gas at high redshift. We study this gas in absorption against bright background quasars in absorption systems known as Damped Ly-alpha Systems (DLAs). These systems contain the bulk of the atomic gas at high redshift and are the likely progenitors of modern-day galaxies. In Chapter 2, we find that the atomic gas in DLAs obeys a mass-metallicity relationship that is similar to the mass-metallicity relationship seen in star-forming galaxies. The evolution of this relationship is linear with redshift, allowing for a planar equation to accurately describe this evolution, which provides a more stringent constraint on simulations modeling DLAs. Furthermore, the concomitant evolution of the mass-metallicity relationship of atomic gas and star-forming galaxies suggests an intimate link between the two. We next use a novel way to measure the physical conditions of the gas by using fine-structure line ratios of singly ionized carbon and silicon. By measuring the density of the upper and lower level states, we are able to determine the temperature, hydrogen density and electron density of the gas. We find that the conditions present in this high redshift gas are consistent with the conditions we see in the local interstellar medium (ISM). A few absorbers have higher than expected pressure, which suggests that they probe the ISM of star-forming galaxies. Finally in Chapter 4, we measure the cosmic neutral hydrogen density at redshifts below 1.6. Below this redshift, the Ly-alpha line of hydrogen is absorbed by the atmosphere, making detection difficult. Using the archive of the Hubble Space Telescope, we compile a comprehensive list of quasars for a search of DLAs at redshift below 1.6. We find that the incidence rate of DLAs and the cosmic neutral hydrogen density is smaller than previously measured, but consistent with the values both locally and at

  14. Very High Gas Fractions and Extended Gas Reservoirs in z=1.5 Disk Galaxies

    CERN Document Server

    Daddi, E; Walter, F; Dannerbauer, H; Carilli, C; Dickinson, M; Elbaz, D; Morrison, G E; Riechers, D; Onodera, M; Salmi, F; Krips, M; Stern, D

    2009-01-01

    We present evidence for very high gas fractions and extended molecular gas reservoirs in normal, near-infrared selected (BzK) galaxies at z~1.5, based on multi-configuration CO[2-1] observations obtained at the IRAM PdBI. Six of the six galaxies observed were securely detected. High resolution observations resolve the CO emission in four of them, implying sizes of order of 6-11 kpc and suggesting the presence of rotation. The UV morphologies are consistent with clumpy, unstable disks, and the UV sizes are consistent with the CO sizes. The star formation efficiencies are homogeneously low and similar to local spirals - the resulting gas depletion times are ~0.5 Gyr, much higher than what is seen in high-z submm galaxies and quasars. The CO luminosities can be predicted to within 0.15 dex from the star formation rates and stellar masses, implying a tight correlation of the gas mass with these quantities. We use dynamical models of clumpy disk galaxies to derive dynamical masses. These models are able to reprodu...

  15. Method of evaluating the impact of ERP implementation critical success factors - a case study in oil and gas industries

    Science.gov (United States)

    Gajic, Gordana; Stankovski, Stevan; Ostojic, Gordana; Tesic, Zdravko; Miladinovic, Ljubomir

    2014-01-01

    The so far implemented enterprise resource planning (ERP) systems have in many cases failed to meet the requirements regarding the business process control, decrease of business costs and increase of company profit margin. Therefore, there is a real need for an evaluation of the influence of ERP on the company's performance indicators. Proposed in this article is an advanced model for the evaluation of the success of ERP implementation on organisational and operational performance indicators in oil-gas companies. The recommended method establishes a correlation between a process-based method, a scorecard model and ERP critical success factors. The method was verified and tested on two case studies in oil-gas companies using the following procedure: the model was developed, tested and implemented in a pilot gas-oil company, while the results were implemented and verified in another gas-oil company.

  16. LOW ENERGY BEAM-GAS SPECTROSCOPY OF HIGHLY IONISED ATOMS

    OpenAIRE

    Desesquelles, J.; DENIS A.; Druetta, M.; Martin, S.

    1989-01-01

    Features of low energy beam-gas spectroscopic source are reviewed and compared to those of other light sources. Measurement techniques are surveyed. They include the study of wavelength of heavy multiply charged ions in visible and u.v. ranges from normal excited states, doubly excited states, high n levels and doubly excited Rydberg levels.

  17. Control rod drive for high temperature gas cooled reactor

    Institute of Scientific and Technical Information of China (English)

    DengJun-Xian; XuJi-Ming; 等

    1998-01-01

    This control rod drive is developed for HTR-10 high temperature gas cooled test reactor.The stepmotor is prefered to improve positioning of the control rod and the scram behavior.The preliminary test in 1600170 ambient temperature shows that the selected stepmotor and transmission system can meet the main operation function requirements of HTR-10.

  18. NOVEL GAS SENSORS FOR HIGH-TEMPERATURE FOSSIL FUEL APPLICATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Palitha Jayaweera

    2004-05-01

    SRI is developing ceramic-based microsensors for detection of exhaust gases such as NO, NO{sub 2}, and CO in advanced combustion and gasification systems. The sensors detect the electrochemical activity of the exhaust gas species on catalytic electrodes and are designed to operate at high temperatures, elevated pressures, and corrosive environments typical of large power generation exhausts. Under this research project we are developing sensors for multiple gas detection in a single package along with data acquisition and control software and hardware. The sensor package can be easily integrated into online monitoring systems for active emission control. This report details the research activities performed from October 2003 to April 2004.

  19. Critical wind velocity for arresting upwind gas and smoke dispersion induced by near-wall fire in a road tunnel.

    Science.gov (United States)

    Hu, L H; Peng, W; Huo, R

    2008-01-15

    In case of a tunnel fire, toxic gas and smoke particles released are the most fatal contaminations. It is important to supply fresh air from the upwind side to provide a clean and safe environment upstream from the fire source for people evacuation. Thus, the critical longitudinal wind velocity for arresting fire induced upwind gas and smoke dispersion is a key criteria for tunnel safety design. Former studies and thus, the models built for estimating the critical wind velocity are all arbitrarily assuming that the fire takes place at the centre of the tunnel. However, in many real cases in road tunnels, the fire originates near the sidewall. The critical velocity of a near-wall fire should be different with that of a free-standing central fire due to their different plume entrainment process. Theoretical analysis and CFD simulation were performed in this paper to estimate the critical velocity for the fire near the sidewall. Results showed that when fire originates near the sidewall, it needs larger critical velocity to arrest the upwind gas and smoke dispersion than when fire at the centre. The ratio of critical velocity of a near-wall fire to that of a central fire was ideally estimated to be 1.26 by theoretical analysis. Results by CFD modelling showed that the ratio decreased with the increase of the fire size till near to unity. The ratio by CFD modelling was about 1.18 for a 500kW small fire, being near to and a bit lower than the theoretically estimated value of 1.26. However, the former models, including those of Thomas (1958, 1968), Dangizer and Kenndey (1982), Oka and Atkinson (1995), Wu and Barker (2000) and Kunsch (1999, 2002), underestimated the critical velocity needed for a fire near the tunnel sidewall.

  20. High temperature gas dynamics an introduction for physicists and engineers

    CERN Document Server

    Bose, Tarit K

    2014-01-01

    High Temperature Gas Dynamics is a primer for scientists, engineers, and students who would like to have a basic understanding of the physics and the behavior of high-temperature gases. It is a valuable tool for astrophysicists as well. The first chapters treat the basic principles of quantum and statistical mechanics and how to derive thermophysical properties from them. Special topics are included that are rarely found in other textbooks, such as the thermophysical and transport properties of multi-temperature gases and a novel method to compute radiative transfer. Furthermore, collision processes between different particles are discussed. Separate chapters deal with the production of high-temperature gases and with electrical emission in plasmas, as well as related diagnostic techniques.This new edition adds over 100 pages and includes the following updates: several sections on radiative properties of high temperature gases and various radiation models, a section on shocks in magneto-gas-dynamics, a sectio...

  1. High resolution 3D gas-jet characterization.

    Science.gov (United States)

    Landgraf, Björn; Schnell, Michael; Sävert, Alexander; Kaluza, Malte C; Spielmann, Christian

    2011-08-01

    We present a tomographic characterization of gas jets employed for high-intensity laser-plasma interaction experiments where the shape can be non-symmetrically. With a Mach-Zehnder interferometer we measured the phase shift for different directions through the neutral density distribution of the gas jet. From the recorded interferograms it is possible to retrieve 3-dimensional neutral density distributions by tomographic reconstruction based on the filtered back projections. We report on criteria for the smallest number of recorded interferograms as well as a comparison with the widely used phase retrieval based on an Abel inversion. As an example for the performance of our approach, we present the characterization of nozzles with rectangular openings or gas jets with shock waves. With our setup we obtained a spatial resolution of less than 60 μm for an Argon density as low as 2 × 10(17) cm(-3).

  2. The formation and physical origin of highly ionized cooling gas

    CERN Document Server

    Bordoloi, Rongmon; Norman, Colin A

    2016-01-01

    We present a physically clear cooling flow theory that explains the origin of warm diffuse gas seen primarily as highly ionized absorption line systems in the spectra of background sources. We predict the observed column densities of several highly ionized transitions such as O VI, O VII, Ne VIII, N V, and Mg X; and present a unified comparison of the model predictions with absorption lines seen in the Milky Way disk, Milky Way halo, starburst galaxies, the circumgalactic medium and the intergalactic medium at low and high redshifts. We show that diffuse gas seen in such diverse environments can be simultaneously explained by a simple model of radiatively cooling gas. We show that most of such absorption line systems are consistent with being collisionally ionized, and estimate the maximum likelihood temperature of the gas in each observation. This model satisfactorily explains why O VI is regularly observed around star-forming low-z L* galaxies, and why N V is rarely seen around the same galaxies. We predict...

  3. The Influence of Mixing in High Temperature Gas Phase Reactions

    DEFF Research Database (Denmark)

    Østberg, Martin

    1996-01-01

    by injection of NH3 with carrier gas into the flue gas. NH3 can react with NO and form N2, but a competing reaction path is the oxidation of NH3 to NO.The SNR process is briefly described and it is shown by chemical kinetic modelling that OH radicals under the present conditions will initiate the reaction...... diffusion. The SNR process is simulated using the mixing model and an empirical kinetic model based on laboratory experiments.A bench scale reactor set-up has been built using a natural gas burner to provide the main reaction gas. The set-up has been used to perform an experimental investigation......The objective of this thesis is to describe the mixing in high temperature gas phase reactions.The Selective Non-Catalytic Reduction of NOx (referred as the SNR process) using NH3 as reductant was chosen as reaction system. This in-furnace denitrification process is made at around 1200 - 1300 K...

  4. Experimental consequences of quantum critical points at high temperatures

    Science.gov (United States)

    Freitas, D. C.; Rodière, P.; Núñez, M.; Garbarino, G.; Sulpice, A.; Marcus, J.; Gay, F.; Continentino, M. A.; Núñez-Regueiro, M.

    2015-11-01

    We study the C r1 -xR ex phase diagram finding that its phase transition temperature towards an antiferromagnetic order TN follows a quantum [(xc-x ) /xc ] ψ law, with ψ =1 /2 , from the quantum critical point (QCP) at xc=0.25 up to TN≈600 K . We compare this system to others in order to understand why this elemental material is affected by the QCP up to such unusually high temperatures. We determine a general criterion for the crossover, as a function of an external parameter such as concentration, from the region controlled solely by thermal fluctuations to that where quantum effects become observable. The properties of materials with low coherence lengths will thus be altered far away from the QCP.

  5. Air impacts of increased natural gas acquisition, processing, and use: a critical review.

    Science.gov (United States)

    Moore, Christopher W; Zielinska, Barbara; Pétron, Gabrielle; Jackson, Robert B

    2014-01-01

    During the past decade, technological advancements in the United States and Canada have led to rapid and intensive development of many unconventional natural gas plays (e.g., shale gas, tight sand gas, coal-bed methane), raising concerns about environmental impacts. Here, we summarize the current understanding of local and regional air quality impacts of natural gas extraction, production, and use. Air emissions from the natural gas life cycle include greenhouse gases, ozone precursors (volatile organic compounds and nitrogen oxides), air toxics, and particulates. National and state regulators primarily use generic emission inventories to assess the climate, air quality, and health impacts of natural gas systems. These inventories rely on limited, incomplete, and sometimes outdated emission factors and activity data, based on few measurements. We discuss case studies for specific air impacts grouped by natural gas life cycle segment, summarize the potential benefits of using natural gas over other fossil fuels, and examine national and state emission regulations pertaining to natural gas systems. Finally, we highlight specific gaps in scientific knowledge and suggest that substantial additional measurements of air emissions from the natural gas life cycle are essential to understanding the impacts and benefits of this resource.

  6. High-speed cinematography of gas-metal atomization

    Energy Technology Data Exchange (ETDEWEB)

    Ting, Jason [ALCOA Specialty Metals Division, 100 Technical Drive, Alcoa Center, PA 15069 (United States)]. E-mail: jason.ting@alcoa.com; Connor, Jeffery [Material Science Engineering Department, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Ridder, Stephen [Metallurgical Processing Group, NIST, 100 Bureau Dr. Stop 8556, Gaithersburg, MD 20899 (United States)

    2005-01-15

    A high-speed cinematographic footage of a 304L stainless steel gas atomization, recorded at the National Institute of Standard and Technology (NIST), was analyzed using a discrete Fourier transform (DFT) algorithm. The analysis showed the gas atomization process possesses two prominent frequency ranges of melt oscillation (pulsation). A low-frequency oscillation in the melt flow occurring between 5.41 and 123 Hz, with a dominant frequency at 9.93 Hz, was seen in the recirculation zone adjacent to the melt orifice. A high-frequency melt oscillation range was observed above 123 Hz, and was more prominent one melt-tip-diameter downstream in the melt atomization image than upstream near the melt tip. This high-frequency range may reflect the melt atomization frequency used to produce finely atomized powder. This range also included a prominent high frequency at 1273 Hz, which dominated in the image further away downstream from the melt tip. This discrete high-frequency oscillation is most probably caused by the aeroacoustic ''screech'' phenomenon, intrasound (<20 kHz), a result of the atomizing gas jets undergoing flow resonance. It is hypothesized that this discrete intrinsic aeroacoustic tone may enhance melt breakup in the atomization process with evidence of this fact in the melt images.

  7. The evaluation study of high performance gas target system

    Energy Technology Data Exchange (ETDEWEB)

    Hur, Min Goo; Yang, Seung Dae; Kim, Sang Wook

    2008-06-15

    The object of this study is a improvement of a gas target and targetry for increasing the radioisotope production yields. The main results are as follows 1. Improvement of beam entrance of the gas target : In this work, deep hole grid was designed for improvement of beam entrance. Using FEM(Finite Elements Method) analysis, it was verified that this design is more effective than the old one. 2. Improvement of target gas loading and withdrawing system : For the targetry, Helium gas and vacuum lines was installed for evaluating the production yields. Using these lines, it was proved that the recovery yields was improved and the residual impurity was reduced. 3. Improvement of target cooling efficiency : In case of the cylindrical target, it is more effective to use short length of target cavity for the high production yields. For improving the cooling efficiency, cooling fin was suggested to the target design. It is more effective to put the cooling fins inside the target cavity for the suppressed target pressure and density reduction effect during the proton beam irradiation. In conclusion, the target with fins inside the target cavity was better for high current irradiation and mass RI production.

  8. Scaling of a driven atomic gas from the weakly-dressed to the quantum critical regime

    CERN Document Server

    Helmrich, S; Whitlock, S

    2016-01-01

    The emergence of correlations in complex many-body systems can be accompanied by unexpectedly simple scaling laws which signal new physical regimes or universal relations between otherwise very different physical systems. We demonstrate that non-equilibrium scaling laws can reveal the different regimes of strongly-interacting quantum systems driven to highly excited states. For weak or far off-resonant driving we find that the dependence of the excitation rate on coupling strength is well described by power laws characteristic of the dissipative or weakly-dressed regimes, while for strong near-resonant driving we observe a crossover to the quantum critical regime. For intermediate detunings we discover superlinear intensity scaling in a new regime, indicative of cooperative excitation processes, which extends the domain where scale-invariant behavior can be found in driven quantum systems.

  9. CO2 , NOx and SOx removal from flue gas via microalgae cultivation: a critical review.

    Science.gov (United States)

    Yen, Hong-Wei; Ho, Shih-Hsin; Chen, Chun-Yen; Chang, Jo-Shu

    2015-06-01

    Flue gas refers to the gas emitting from the combustion processes, and it contains CO2 , NOx , SOx and other potentially hazardous compounds. Due to the increasing concerns of CO2 emissions and environmental pollution, the cleaning process of flue gas has attracted much attention. Using microalgae to clean up flue gas via photosynthesis is considered a promising CO2 mitigation process for flue gas. However, the impurities in the flue gas may inhibit microalgal growth, leading to a lower microalgae-based CO2 fixation rate. The inhibition effects of SOx that contribute to the low pH could be alleviated by maintaining a stable pH level, while NOx can be utilized as a nitrogen source to promote microalgae growth when it dissolves and is oxidized in the culture medium. The yielded microalgal biomass from fixing flue gas CO2 and utilizing NOx and SOx as nutrients would become suitable feedstock to produce biofuels and bio-based chemicals. In addition to the removal of SOx , NOx and CO2 , using microalgae to remove heavy metals from flue gas is also quite attractive. In conclusion, the use of microalgae for simultaneous removal of CO2 , SOx and NOx from flue gas is an environmentally benign process and represents an ideal platform for CO2 reutilization. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Study of high pressure gas filled RF cavities for muon collider

    CERN Document Server

    Yonehara, Katsuya

    2015-01-01

    Muon collider is a considerable candidate of the next-generation high-energy lepton collider machine. Operating an RF cavity in a multi-Tesla magnet is a critical requirement in a muon accelerator and a cooling channel. However, the maximum RF gradient in a vacuum RF cavity is strongly limited by an external magnetic field. Dense hydrogen gas filled RF cavity has been proposed since it is functional of generating a high RF accelerating gradient in a strong magnetic field and making an ionization cooling process at the same time. A critical issue of the cavity is a beam- induced plasma that consumes a considerable amount of RF power. The gas filled RF test cell was made and measured the RF loading due to a beam-induced plasma by using an intense proton beam at Fermilab. By doping an electronegative gas in dense hydrogen, the plasma loading effect is significantly mitigated. The result shows that the cavity is functional with a muon collider beam. Recent progress is shown in this presentation.

  11. High accuracy Primary Reference gas Mixtures for high-impact greenhouse gases

    Science.gov (United States)

    Nieuwenkamp, Gerard; Zalewska, Ewelina; Pearce-Hill, Ruth; Brewer, Paul; Resner, Kate; Mace, Tatiana; Tarhan, Tanil; Zellweger, Christophe; Mohn, Joachim

    2017-04-01

    Climate change, due to increased man-made emissions of greenhouse gases, poses one of the greatest risks to society worldwide. High-impact greenhouse gases (CO2, CH4 and N2O) and indirect drivers for global warming (e.g. CO) are measured by the global monitoring stations for greenhouse gases, operated and organized by the World Meteorological Organization (WMO). Reference gases for the calibration of analyzers have to meet very challenging low level of measurement uncertainty to comply with the Data Quality Objectives (DQOs) set by the WMO. Within the framework of the European Metrology Research Programme (EMRP), a project to improve the metrology for high-impact greenhouse gases was granted (HIGHGAS, June 2014-May 2017). As a result of the HIGHGAS project, primary reference gas mixtures in cylinders for ambient levels of CO2, CH4, N2O and CO in air have been prepared with unprecedented low uncertainties, typically 3-10 times lower than usually previously achieved by the NMIs. To accomplish these low uncertainties in the reference standards, a number of preparation and analysis steps have been studied and improved. The purity analysis of the parent gases had to be performed with lower detection limits than previously achievable. E.g., to achieve an uncertainty of 2•10-9 mol/mol (absolute) on the amount fraction for N2O, the detection limit for the N2O analysis in the parent gases has to be in the sub nmol/mol domain. Results of an OPO-CRDS analyzer set-up in the 5µm wavelength domain, with a 200•10-12 mol/mol detection limit for N2O, will be presented. The adsorption effects of greenhouse gas components at cylinder surfaces are critical, and have been studied for different cylinder passivation techniques. Results of a two-year stability study will be presented. The fit-for-purpose of the reference materials was studied for possible variation on isotopic composition between the reference material and the sample. Measurement results for a suit of CO2 in air

  12. High integrity adaptive SMA components for gas turbine applications

    Science.gov (United States)

    Webster, John

    2006-03-01

    The use of Shape Memory Alloys (SMAs) is growing rapidly. They have been under serious development for aerospace applications for over 15 years, but are still restricted to niche areas and small scale applications. Very few applications have found their way into service. Whilst they have been predominantly aimed at airframe applications, they also offer major advantages for adaptive gas turbine components. The harsh environment within a gas turbine with its high loads, temperatures and vibration excitation provide considerable challenges which must be met whilst still delivering high integrity, light weight, aerodynamic and efficient structures. A novel method has been developed which will deliver high integrity, stiff mechanical components which can provide massive shape change capability without the need for conventional moving parts. The lead application is for a shape changing engine nozzle to provide noise reduction at take off but will withdraw at cruise to remove any performance penalty. The technology also promises to provide significant advantages for applications in a gas turbine such as shape change aerofoils, heat exchanger controls, and intake shapes. The same mechanism should be directly applicable to other areas such as air frames, automotive and civil structures, where similar high integrity requirements exist.

  13. Intrinsically Microporous Polymer Membranes for High Performance Gas Separation

    KAUST Repository

    Swaidan, Raja

    2014-11-01

    This dissertation addresses the rational design of intrinsically microporous solutionprocessable polyimides and ladder polymers for highly permeable and highly selective gas transport in cornerstone applications of membrane-based gas separation – that is, air enrichment, hydrogen recovery and natural gas sweetening. By virtue of rigid and contorted chains that pack inefficiently in the solid state, polymers of intrinsic microporosity (PIMs) have the potential to unite the solution-processability, mechanical flexibility and organic tunability of commercially relevant polymers with the microporosity characteristics of porous crystalline materials. The performance enhancements of PIMs over conventional low-free-volume polymers have been primarily permeability-driven, compromising the selectivity essential to commercial viability. An approach to unite high permeability with high selectivity for performance transcending the state-of-the-art in air and hydrogen separations was demonstrated via a fused-ring integration of a three-dimensional, shape persistent triptycene moiety optimally substituted with short, branched isopropyl chains at the 9,10-bridgeheads into a highly inflexible backbone. The resulting polymers exhibited selectivities (i.e., O2/N2, H2/N2, H2/CH4) similar to or higher than commercial materials matched with permeabilities up to three hundred times higher. However, the intra-chain rigidity central to such conventional PIM-design principles was not a singular solution to suppression of CO2-induced plasticization in CO2/CH4 mixedgas separations. Plasticization diminishes the sieving capacity of the membrane, resulting in costly hydrocarbon losses that have significantly limited the commercialization of new polymers. Unexpectedly, the most permeable and selective PIMs designed for air and hydrogen separations strongly plasticized in 50:50 CO2/CH4 mixtures, enduring up to three-fold increases in mixed-gas CH4 permeability by 30 bar and strong drops in

  14. PROBING THE PHYSICAL CONDITIONS OF ATOMIC GAS AT HIGH REDSHIFT

    Energy Technology Data Exchange (ETDEWEB)

    Neeleman, Marcel; Wolfe, Arthur M. [Department of Physics and Center for Astrophysics and Space Sciences, UCSD, La Jolla, CA 92093 (United States); Prochaska, J. Xavier, E-mail: mneeleman@physics.ucsd.edu [Department of Astronomy and Astrophysics, UCO/Lick Observatory, 1156 High Street, University of California, Santa Cruz, CA 95064 (United States)

    2015-02-10

    A new method is used to measure the physical conditions of the gas in damped Lyα systems (DLAs). Using high-resolution absorption spectra of a sample of 80 DLAs, we are able to measure the ratio of the upper and lower fine-structure levels of the ground state of C{sup +} and Si{sup +}. These ratios are determined solely by the physical conditions of the gas. We explore the allowed physical parameter space using a Monte Carlo Markov chain method to constrain simultaneously the temperature, neutral hydrogen density, and electron density of each DLA. The results indicate that at least 5% of all DLAs have the bulk of their gas in a dense, cold phase with typical densities of ∼100 cm{sup –3} and temperatures below 500 K. We further find that the typical pressure of DLAs in our sample is log (P/k{sub B} ) = 3.4 (K cm{sup –3}), which is comparable to the pressure of the local interstellar medium (ISM), and that the components containing the bulk of the neutral gas can be quite small with absorption sizes as small as a few parsecs. We show that the majority of the systems are consistent with having densities significantly higher than expected for a purely canonical warm neutral medium, indicating that significant quantities of dense gas (i.e., n {sub H} > 0.1 cm{sup –3}) are required to match observations. Finally, we identify eight systems with positive detections of Si II*. These systems have pressures (P/k{sub B} ) in excess of 20,000 K cm{sup –3}, which suggest that these systems tag a highly turbulent ISM in young, star-forming galaxies.

  15. Criticality issues with highly enriched fuels in a repository environment

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, L.L. [Lockheed Martin Idaho Technologies Co., Idaho Falls, ID (United States); Sanchez, L.C.; Rath, J.S. [Sandia National Labs., Albuquerque, NM (United States)

    1998-03-01

    This paper presents preliminary analysis of a volcanic tuff repository containing a combination of low enrichment commercial spent nuclear fuels (SNF) and DOE-owned SNF packages. These SNFs were analyzed with respect to their criticality risks. Disposal of SNF packages containing significant fissile mass within a geologic repository must comply with current regulations relative to criticality safety during transportation and handling within operational facilities. However, once the repository is closed, the double contingency credits for criticality safety are subject to unremediable degradation, (e.g., water intrusion, continued presence of neutron absorbers in proximity to fissile material, and fissile material reconfiguration). The work presented in this paper focused on two attributes of criticality in a volcanic tuff repository for near-field and far-field scenarios: (1) scenario conditions necessary to have a criticality, and (2) consequences of a nuclear excursion that are components of risk. All criticality consequences are dependent upon eventual water intrusion into the repository and subsequent breach of the disposal package. Key criticality parameters necessary for a critical assembly are: (1) adequate thermal fissile mass, (2) adequate concentration of fissile material, (3) separation of neutron poison from fissile materials, and (4) sufficient neutron moderation (expressed in units of moderator to fissile atom ratios). Key results from this study indicated that the total energies released during a single excursion are minimal (comparable to those released in previous solution accidents), and the maximum frequency of occurrence is bounded by the saturation and temperature recycle times, thus resulting in small criticality risks.

  16. High-Temperature Gas-Cooled Test Reactor Point Design

    Energy Technology Data Exchange (ETDEWEB)

    Sterbentz, James William [Idaho National Laboratory; Bayless, Paul David [Idaho National Laboratory; Nelson, Lee Orville [Idaho National Laboratory; Gougar, Hans David [Idaho National Laboratory; Kinsey, James Carl [Idaho National Laboratory; Strydom, Gerhard [Idaho National Laboratory; Kumar, Akansha [Idaho National Laboratory

    2016-04-01

    A point design has been developed for a 200 MW high-temperature gas-cooled test reactor. The point design concept uses standard prismatic blocks and 15.5% enriched UCO fuel. Reactor physics and thermal-hydraulics simulations have been performed to characterize the capabilities of the design. In addition to the technical data, overviews are provided on the technological readiness level, licensing approach and costs.

  17. The Influence of Mixing in High Temperature Gas Phase Reactions

    DEFF Research Database (Denmark)

    Østberg, Martin

    1996-01-01

    of NH3 by formation of NH2 and NH radicals.Mixing in reacting gas phase systems is described by an empirical mixing model (the droplet diffusion model). The mixing process is separated into macro- and micromixing. The macromixing is assumed to be ideal while the micromixing is modelled by molecular......The objective of this thesis is to describe the mixing in high temperature gas phase reactions.The Selective Non-Catalytic Reduction of NOx (referred as the SNR process) using NH3 as reductant was chosen as reaction system. This in-furnace denitrification process is made at around 1200 - 1300 K...... by injection of NH3 with carrier gas into the flue gas. NH3 can react with NO and form N2, but a competing reaction path is the oxidation of NH3 to NO.The SNR process is briefly described and it is shown by chemical kinetic modelling that OH radicals under the present conditions will initiate the reaction...

  18. High-temperature gas effects on aerodynamic characteristics of waverider

    Institute of Scientific and Technical Information of China (English)

    Liu Jun; Li Kai; Liu Weiqiang

    2015-01-01

    This paper focuses on the analysis of high-temperature effect on a conical waverider and it is a typical configuration of near space vehicles. Two different gas models are used in the numerical simulations, namely the thermochemical non-equilibrium and perfect gas models. The non-equilibrium flow simulations are conducted with the usage of the parallel non-equilibrium pro-gram developed by the authors while the perfect gas flow simulations are carried out with the com-mercial software Fluent. The non-equilibrium code is validated with experimental results and grid sensitivity analysis is performed as well. Then, numerical simulations of the flow around the conical waverider with the two gas models are conducted. In the results, differences in the flow structures as well as aerodynamic performances of the conical waverider are compared. It is found that the thermochemical non-equilibrium effect is significant mainly near the windward boundary layer at the tail of the waverider, and the non-equilibrium influence makes the pressure center move forward to about 0.57%of the whole craft’s length at the altitude of 60 km.

  19. Probing the Physical Conditions of Atomic Gas at High Redshift

    CERN Document Server

    Neeleman, Marcel; Wolfe, Arthur M

    2014-01-01

    A new method is used to measure the physical conditions of the gas in damped Lyman-alpha systems (DLAs). Using high resolution absorption spectra of a sample of 80 DLAs, we are able to measure the ratio of the upper to lower fine-structure levels of the ground state of C II and Si II. These ratios are determined solely by the physical conditions of the gas. We explore the allowed physical parameter space using a Monte Carlo Markov Chain method to constrain simultaneously the temperature, neutral hydrogen density, and electron density of each DLA. The results indicate that at least 5 % of all DLAs have the bulk of their gas in a dense, cold phase with typical densities of ~100 cm-3 and temperatures below 500 K. We further find that the typical pressure of DLAs in our sample is log(P/k) = 3.4 [K cm-3], which is comparable to the pressure of the local interstellar medium (ISM), and that the components containing the bulk of the neutral gas can be quite small with absorption sizes as small as a few parsec. We sho...

  20. High-temperature gas effects on aerodynamic characteristics of waverider

    Directory of Open Access Journals (Sweden)

    Liu Jun

    2015-02-01

    Full Text Available This paper focuses on the analysis of high-temperature effect on a conical waverider and it is a typical configuration of near space vehicles. Two different gas models are used in the numerical simulations, namely the thermochemical non-equilibrium and perfect gas models. The non-equilibrium flow simulations are conducted with the usage of the parallel non-equilibrium program developed by the authors while the perfect gas flow simulations are carried out with the commercial software Fluent. The non-equilibrium code is validated with experimental results and grid sensitivity analysis is performed as well. Then, numerical simulations of the flow around the conical waverider with the two gas models are conducted. In the results, differences in the flow structures as well as aerodynamic performances of the conical waverider are compared. It is found that the thermochemical non-equilibrium effect is significant mainly near the windward boundary layer at the tail of the waverider, and the non-equilibrium influence makes the pressure center move forward to about 0.57% of the whole craft’s length at the altitude of 60 km.

  1. Scintillation luminescence for high-pressure xenon gas

    Science.gov (United States)

    Kobayashi, S.; Hasebe, N.; Igarashi, T.; Kobayashi, M.-N.; Miyachi, T.; Miyajima, M.; Okada, H.; Okudaira, O.; Tezuka, C.; Yokoyama, E.; Doke, T.; Shibamura, E.; Dmitrenko, V. V.; Ulin, S. E.; Vlasik, K. F.

    2004-09-01

    Scintillation and ionization yields in xenon gas for 5.49MeV alpha-particles were measured in the range of pressure from 0.35 to 3.7MPa and the electric field strength (E) over the number density of xenon atoms (N), E/N from 0 to 5×10-18Vcm2. When our data are normalized at the data point measured by Saito et al., the number of scintillation photons is 2.3×105 while the number of ionization electrons is 2.0×105 at 2.6MPa and at 3.7×10-18Vcm2. The scintillation and ionization yields of xenon doped with 0.2% hydrogen, High-Pressure Xenon gas[H2-0.2%], at 2.6MPa was also measured. Scintillation yield of the Xe-H2 mixture gas is 80% as high as that of pure xenon. It is found that the scintillation yield is luminous enough to generate a trigger pulse of the high-pressure xenon time projection chamber, which is expected as a promising MeV Compton gamma-ray camera.

  2. Application of High Intensity THz Pulses for Gas High Harmonic Generation

    CERN Document Server

    Balogh, Emeric; Hebling, János; Dombi, Péter; Farkas, Győző; Varjú, Katalin

    2013-01-01

    The main effects of an intense THz pulse on gas high harmonic generation are studied via trajectory analysis on the single atom level. Spectral and temporal modifications to the generated radiation are highlighted.

  3. Development of high temperature coal gas desulfurization systems -- An overview

    Energy Technology Data Exchange (ETDEWEB)

    Abbasian, J.; Slimane, R.B.; Lau, F.S.; Wangergow, J.R.; Zarnegar, M.K. [Inst. of Gas Technology, Des Plaines, IL (United States)

    1997-12-31

    Integrated Gasification Combined-Cycle (IGCC) processes are among the leading contenders for generation of electricity from coal in the 21st century. Coal gas desulfurization to sufficiently low levels at temperatures above 350 C is now recognized as crucial to efficient and economical utilization of coal in advanced IGCC processes. The implementation of hot coal gas desulfurization heavily relies on the development of regenerable sorbent materials that can efficiently remove H{sub 2}S (from several thousand ppmv levels down to a few ppmv) over a very large number of sulfidation/regeneration cycles. Over the last two decades, development of high temperature desulfurization sorbents has been focused on using various combinations of transition metal oxides as regenerable sorbents. The selection of suitable metal oxides is generally based on a number of requirements imposed by the IGCC process, which include favorable thermodynamic equilibria during sulfidation and regeneration, relatively high sulfidation and regeneration reactivities, good mechanical strength and structural stability, and environmental friendliness, all at a reasonably low cost. The desulfurization reactor can have a fixed-bed, a moving-bed, a transport reactor, or a bubbling fluidized-bed reactor design. Depending on process conditions and the application intended, each of these reactor configurations offers advantages, but also has limitations. The parameters guiding the choice of a reactor system include reactivity of the sorbent, crush strength and/or attrition resistance of the sorbent, absorption capacity of the sorbent, temperature distribution inside the reactors, and SO{sub 2} concentration in the regeneration product gas. This paper provides an overview of high temperature fuel gas desulfurization within the context of IGCC processes. The paper focuses on the studies related to the development of regenerable sorbents and addresses thermodynamic considerations, sulfidation kinetics

  4. High-temperature turbine technology program. Turbine subsystem design report: Low-Btu gas

    Energy Technology Data Exchange (ETDEWEB)

    Horner, M.W.

    1980-12-01

    The objective of the US Department of Energy High-Temperature Turbine Technology (DOE-HTTT) program is to bring to technology readiness a high-temperature (2600/sup 0/F to 3000/sup 0/F firing temperature) turbine within a 6- to 10-year duration, Phase II has addressed the performance of component design and technology testing in critical areas to confirm the design concepts identified in the earlier Phase I program. Based on the testing and support studies completed under Phase II, this report describes the updated turbine subsystem design for a coal-derived gas fuel (low-Btu gas) operation at 2600/sup 0/F turbine firing temperature. A commercial IGCC plant configuration would contain four gas turbines. These gas turbines utilize an existing axial flow compressor from the GE product line MS6001 machine. A complete description of the Primary Reference Design-Overall Plant Design Description has been developed and has been documented. Trends in overall plant performance improvement at higher pressure ratio and higher firing temperature are shown. It should be noted that the effect of pressure ratio on efficiency is significally enhanced at higher firing temperatures. It is shown that any improvement in overall plant thermal efficiency reflects about the same level of gain in Cost of Electricity (COE). The IGCC concepts are shown to be competitive in both performance and cost at current and near-term gas turbine firing temperatures of 1985/sup 0/F to 2100/sup 0/F. The savings that can be accumulated over a thirty-year plant life for a water-cooled gas turbine in an IGCC plant as compared to a state-of-the-art coal-fired steam plant are estimated. A total of $500 million over the life of a 1000 MW plant is projected. Also, this IGCC power plant has significant environmental advantages over equivalent coal-fired steam power plants.

  5. The Status of the US High-Temperature Gas Reactors

    OpenAIRE

    2016-01-01

    In 2005, the US passed the Energy Policy Act of 2005 mandating the construction and operation of a high-temperature gas reactor (HTGR) by 2021. This law was passed after a multiyear study by national experts on what future nuclear technologies should be developed. As a result of the Act, the US Congress chose to develop the so-called Next-Generation Nuclear Plant, which was to be an HTGR designed to produce process heat for hydrogen production. Despite high hopes and expectations, the current...

  6. Test Program for High Efficiency Gas Turbine Exhaust Diffuser

    Energy Technology Data Exchange (ETDEWEB)

    Norris, Thomas R.

    2009-12-31

    This research relates to improving the efficiency of flow in a turbine exhaust, and thus, that of the turbine and power plant. The Phase I SBIR project demonstrated the technical viability of “strutlets” to control stalls on a model diffuser strut. Strutlets are a novel flow-improving vane concept intended to improve the efficiency of flow in turbine exhausts. Strutlets can help reduce turbine back pressure, and incrementally improve turbine efficiency, increase power, and reduce greenhouse gas emmission. The long-term goal is a 0.5 percent improvement of each item, averaged over the US gas turbine fleet. The strutlets were tested in a physical scale model of a gas turbine exhaust diffuser. The test flow passage is a straight, annular diffuser with three sets of struts. At the end of Phase 1, the ability of strutlets to keep flow attached to struts was demonstrated, but the strutlet drag was too high for a net efficiency advantage. An independently sponsored followup project did develop a highly-modified low-drag strutlet. In combination with other flow improving vanes, complicance to the stated goals was demonstrated for for simple cycle power plants, and to most of the goals for combined cycle power plants using this particular exhaust geometry. Importantly, low frequency diffuser noise was reduced by 5 dB or more, compared to the baseline. Appolicability to other diffuser geometries is yet to be demonstrated.

  7. Guns and High Gas Output Devices Panel: Introduction

    Science.gov (United States)

    Simmons, Ronald L.; Kaste, Pamela J.

    2000-01-01

    A new panel known as the Guns and High Gas Output Panel was organized in 1999 under the auspices of the JANNAF Propellant and Characterization SubCommittee (PDCS). This is an introduction to our first meeting, purpose of the panel, and the scope of activities to be covered. The primary purpose of the panel is very simple: to provide a single focal point for interfacing Government Laboratories (Department of Defense and Department of Energy) and commercial industry researchers to share R&D activities and findings (i.e. facilitate the exchange of information) specifically aimed at gun-launched propulsion and high-gas output devices (gas generators and air bag inflators). Specific areas of interest included in the Panel's scope (and the Technical Data Base) are the following: (1) new propellant formulations and chemistry, (2) new ingredients, (3) ballistic effects of the new formulations and ingredients, (4) new processing methods unique to gun propellants, (5) thermochemistry of new ingredients, (6) unique physical and mechanical properties, (7) burning rates of new propellants and small scale closed bomb testing, (8) plasma effects on the propellant, and (9) unique safety and insensitive munitions properties.

  8. The phase transition of the first order in the critical region of the gas-liquid system

    Directory of Open Access Journals (Sweden)

    I.R. Yukhnovskii

    2014-12-01

    Full Text Available This is a summarising investigation of the events of the phase transition of the first order that occur in the critical region below the liquid-gas critical point. The grand partition function has been completely integrated in the phase-space of the collective variables. The basic density measure is the quartic one. It has the form of the exponent function with the first, second, third and fourth degree of the collective variables. The problem has been reduced to the Ising model in an external field, the role of which is played by the generalised chemical potential μ*. The line μ*(η =0, where η is the density, is the line of the phase transition. We consider the isothermal compression of the gas till the point where the phase transition on the line μ*(η =0 is reached. When the path of the pressing reaches the line μ* =0 in the gas medium, a droplet of liquid springs up. The work for its formation is obtained, the surface-tension energy is calculated. On the line μ* =0 we have a two-phase system: the gas and the liquid (the droplet one. The equality of the gas and of the liquid chemical potentials is proved. The process of pressing is going on. But the pressure inside the system has stopped, two fixed densities have arisen: one for the gas-phase ηG=ηc(1-d/2 and the other for the liquid-phase ηL=ηc(1+d/2 (symmetrically to the rectlinear diameter, where ηc=0.13044 is the critical density. Starting from that moment the external pressure works as a latent work of pressure. Its value is obtained. As a result, the gas-phase disappears and the whole system turns into liquid. The jump of the density is equal to ηc d, where d=(D/2G1/2 ~ τν/2. D and G are coefficients of the Hamiltonian in the last cell connected with the renormalisation-group symmetry. The equation of state is written.

  9. Electron beam treatment of exhaust gas with high NOx concentration

    Science.gov (United States)

    Licki, Janusz; Chmielewski, Andrzej G.; Pawelec, Andrzej; Zimek, Zbigniew; Witman, Sylwia

    2014-05-01

    Simulated exhaust gases with a high NOx concentration, ranging from 200 to 1700 ppmv, were irradiated by an electron beam from an accelerator. In the first part of this study, only exhaust gases were treated. Low NOx removal efficiencies were obtained for high NOx concentrations, even with high irradiation doses applied. In the second part of study, gaseous ammonia or/and vapor ethanol were added to the exhaust gas before its inlet to the plasma reactor. These additions significantly enhanced the NOx removal efficiency. The synergistic effect of high SO2 concentration on NOx removal was observed. The combination of electron beam treatment with the introduction of the above additions and with the performance of irradiation under optimal parameters ensured high NOx removal efficiency without the application of a solid-state catalyst.

  10. NOVEL GAS SENSORS FOR HIGH-TEMPERATURE FOSSIL FUEL APPLICATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Palitha Jayaweera

    2004-05-01

    SRI is developing ceramic-based microsensors for detection of exhaust gases such as NO, NO{sub 2}, and CO in advanced combustion and gasification systems. The sensors detect the electrochemical activity of the exhaust gas species on catalytic electrodes and are designed to operate at high temperatures, elevated pressures, and corrosive environments typical of large power generation exhausts. Under this research project we are developing sensors for multiple gas detection in a single package along with data acquisition and control software and hardware. The sensor package can be easily integrated into online monitoring systems for active emission control. This report details the research activities performed from May 2004 to October 2004 including testing of catalytic materials, sensor design and fabrication, and software development.

  11. Tunable diameter electrostatically formed nanowire for high sensitivity gas sensing

    Institute of Scientific and Technical Information of China (English)

    Alex Henning; Nandhini Swaminathan; Andrey Godkin; Gil Shalev; Iddo Amit; Yossi Rosenwaks

    2015-01-01

    We report on an electrostatically formed nanowire (EFN)-based sensor with tunable diameters in the range of 16 nm to 46 nm and demonstrate an EFN- based field-effect transistor as a highly sensitive and robust room temperature gas sensor. The device was carefully designed and fabricated using standard integrated processing to achieve the 16 nm EFN that can be used for sensing without any need for surface modification. The effective diameter for the EFN was determined using Kelvin probe force microscopy accompanied by three- dimensional electrostatic simulations. We show that the EFN transistor is capable of detecting 100 parts per million of ethanol gas with bare SiO2.

  12. High Temperature Electron Localization in dense He Gas

    CERN Document Server

    Borghesani, A F

    2002-01-01

    We report new accurate mesasurements of the mobility of excess electrons in high density Helium gas in extended ranges of temperature $[(26\\leq T\\leq 77) K ]$ and density $[ (0.05\\leq N\\leq 12.0) {atoms} \\cdot {nm}^{-3}]$ to ascertain the effect of temperature on the formation and dynamics of localized electron states. The main result of the experiment is that the formation of localized states essentially depends on the relative balance of fluid dilation energy, repulsive electron-atom interaction energy, and thermal energy. As a consequence, the onset of localization depends on the medium disorder through gas temperature and density. It appears that the transition from delocalized to localized states shifts to larger densities as the temperature is increased. This behavior can be understood in terms of a simple model of electron self-trapping in a spherically symmetric square well.

  13. Ferrous alloys cast under high pressure gas atmosphere

    Directory of Open Access Journals (Sweden)

    Pirowski Z.

    2007-01-01

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

  14. Nanostructured Tungsten Oxide Composite for High-Performance Gas Sensors

    Directory of Open Access Journals (Sweden)

    Siyuan Feng Chen

    2015-10-01

    Full Text Available We report the results of composite tungsten oxide nanowires-based gas sensors. The morphologic surface, crystallographic structures, and chemical compositions of the obtained nanowires have been investigated using scanning electron microscopy (SEM, X-ray diffraction (XRD, and Raman scattering, respectively. The experimental measurements reveal that each wire consists of crystalline nanoparticles with an average diameter of less than 250 nm. By using the synthesized nanowires, highly sensitive prototypic gas sensors have been designed and fabricated. The dependence of the sensitivity of tungsten oxide nanowires to the methane and hydrogen gases as a function of time has been obtained. Various sensing parameters such as sensitivity, response time, stability, and repeatability were investigated in order to reveal the sensing ability.

  15. Tuning ionic liquids for high gas solubility and reversible gas sorption

    DEFF Research Database (Denmark)

    Huang, Jun; Riisager, Anders; Berg, Rolf W.

    2008-01-01

    a moderate association between gas and liquid, which also could be confirmed by Raman and UV–vis spectroscopy on the gas-saturated (1 bar) ionic liquids. Knowledge of gas solubilities and the reversible gas absorption capacity of ionic liquids are believed to have importance for their possible application...

  16. Desalination and reuse of high-salinity shale gas produced water: drivers, technologies, and future directions.

    Science.gov (United States)

    Shaffer, Devin L; Arias Chavez, Laura H; Ben-Sasson, Moshe; Romero-Vargas Castrillón, Santiago; Yip, Ngai Yin; Elimelech, Menachem

    2013-09-03

    In the rapidly developing shale gas industry, managing produced water is a major challenge for maintaining the profitability of shale gas extraction while protecting public health and the environment. We review the current state of practice for produced water management across the United States and discuss the interrelated regulatory, infrastructure, and economic drivers for produced water reuse. Within this framework, we examine the Marcellus shale play, a region in the eastern United States where produced water is currently reused without desalination. In the Marcellus region, and in other shale plays worldwide with similar constraints, contraction of current reuse opportunities within the shale gas industry and growing restrictions on produced water disposal will provide strong incentives for produced water desalination for reuse outside the industry. The most challenging scenarios for the selection of desalination for reuse over other management strategies will be those involving high-salinity produced water, which must be desalinated with thermal separation processes. We explore desalination technologies for treatment of high-salinity shale gas produced water, and we critically review mechanical vapor compression (MVC), membrane distillation (MD), and forward osmosis (FO) as the technologies best suited for desalination of high-salinity produced water for reuse outside the shale gas industry. The advantages and challenges of applying MVC, MD, and FO technologies to produced water desalination are discussed, and directions for future research and development are identified. We find that desalination for reuse of produced water is technically feasible and can be economically relevant. However, because produced water management is primarily an economic decision, expanding desalination for reuse is dependent on process and material improvements to reduce capital and operating costs.

  17. The Status of the US High-Temperature Gas Reactors

    Directory of Open Access Journals (Sweden)

    Andrew C. Kadak

    2016-03-01

    Full Text Available In 2005, the US passed the Energy Policy Act of 2005 mandating the construction and operation of a high-temperature gas reactor (HTGR by 2021. This law was passed after a multiyear study by national experts on what future nuclear technologies should be developed. As a result of the Act, the US Congress chose to develop the so-called Next-Generation Nuclear Plant, which was to be an HTGR designed to produce process heat for hydrogen production. Despite high hopes and expectations, the current status is that high temperature reactors have been relegated to completing research programs on advanced fuels, graphite and materials with no plans to build a demonstration plant as required by the US Congress in 2005. There are many reasons behind this diminution of HTGR development, including but not limited to insufficient government funding requirements for research, unrealistically high temperature requirements for the reactor, the delay in the need for a “hydrogen” economy, competition from light water small modular light water reactors, little utility interest in new technologies, very low natural gas prices in the US, and a challenging licensing process in the US for non-water reactors.

  18. Intermediate- and High-Velocity Ionized Gas toward zeta Orionis

    CERN Document Server

    Welty, D E; Raymond, J C; Mallouris, C; York, D G

    2002-01-01

    We combine UV spectra obtained with the HST/GHRS echelle, IMAPS, and Copernicus to study the abundances and physical conditions in the predominantly ionized gas seen at high (-105 to -65 km/s) and intermediate velocities (-60 to -10 km/s) toward zeta Ori. We have high resolution (FWHM ~ 3.3-4.5 km/s) and/or high S/N spectra for at least two significant ions of C, N, Al, Si, S, and Fe -- enabling accurate estimates for both the total N(H II) and the elemental depletions. C, N, and S have essentially solar relative abundances; Al, Si, and Fe appear to be depleted by about 0.8, 0.3-0.4, and 0.95 dex, respectively. While various ion ratios would be consistent with collisional ionization equilibrium (CIE) for T ~ 25,000-80,000 K, the widths of individual high-velocity absorption components indicate that T ~ 9000 K -- so the gas is not in CIE. Analysis of the C II fine-structure excitation equilibrium yields estimated densities (n_e ~ n_H ~ 0.1-0.2 cm^{-3}), thermal pressures (2 n_H T ~ 2000-4000 cm^{-3}K), and thi...

  19. Perfluorocarbon Gas Tracer Studies to Support Risk Assessment Modeling of Critical Infrastructure Subjected to Terrorist Attacks

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, Terry M.; Heiser, John H.; Watson, Tom; Allwine, K Jerry; Flaherty, Julia E.

    2006-05-06

    Development of real-time predictive modeling to identify the dispersion and/or source(s) of airborne weapons of mass destruction including chemical, biological, radiological, and nuclear material in urban environments is needed to improve response to potential releases of these materials via either terrorist or accidental means. These models will also prove useful in defining airborne pollution dispersion in urban environments for pollution management/abatement programs. Predicting gas flow in an urban setting on a scale of less than a few kilometers is a complicated and challenging task due to the irregular flow paths that occur along streets and alleys and around buildings of different sizes and shapes, i.e., “urban canyons”. In addition, air exchange between the outside and buildings and subway areas further complicate the situation. Transport models that are used to predict dispersion of WMD/CBRN materials or to back track the source of the release require high-density data and need defensible parameterizations of urban processes. Errors in the data or any of the parameter inputs or assumptions will lead to misidentification of the airborne spread or source release location(s). The need for these models to provide output in a real-time fashion if they are to be useful for emergency response provides another challenge. To improve the ability of New York City’s (NYC's) emergency management teams and first response personnel to protect the public during releases of hazardous materials, the New York City Urban Dispersion Program (UDP) has been initiated. This is a four year research program being conducted from 2004 through 2007. This paper will discuss ground level and subway Perfluorocarbon tracer (PFT) release studies conducted in New York City. The studies released multiple tracers to study ground level and vertical transport of contaminants. This paper will discuss the results from these tests and how these results can be used for improving

  20. Complete Ionisation of the Neutral Gas in High Redshift Radio Galaxies and Quasars

    CERN Document Server

    Curran, S J

    2012-01-01

    Cool neutral gas provides the raw material for all star formation in the Universe, and yet, from a survey of the hosts of high redshift radio galaxies and quasars, we find a complete dearth of atomic (HI 21-cm) and molecular (OH, CO, HCO+ & HCN) absorption at redshifts z > 3. Upon a thorough analysis of the optical photometry, we find that all of our targets have ionising ultra-violet continuum luminosities of logL > 23 W/Hz. We therefore attribute this deficit to the traditional optical selection of targets biasing surveys towards the most ultra-violet luminous objects, where the intense radiation excites the neutral gas to the point where it cannot engage in star formation. However, this hypothesis does not explain why there is a critical luminosity, rather than a continuum where the detections gradually become fewer and fewer as the harshness of the radiation increases. We show that by placing a quasar within a galaxy of gas there is always a finite ultra-violet luminosity above which all of the gas is...

  1. Arterial blood gas analysers: accuracy in determining haemoglobin, glucose and electrolyte concentrations in critically ill adult patients.

    Science.gov (United States)

    Quinn, L M; Hamnett, N; Wilkin, R; Sheikh, A

    2013-01-01

    Arterial blood gas (ABG) machines are vital tools in the assessment of critically ill patients. Current ABG point-of-care (POC) analysers provide information on concentrations of haemoglobin, glucose and electrolytes in addition to acid-base balance. Awaiting results from venous analysers may present a significant delay in diagnosis and management, thus reliance on arterial blood gas determination of these parameters is increasing. However, published data on the concordance between the two modalities are limited. This study aims to assess the concordance of ABG machines in analysing haemoglobin, glucose and electrolyte concentrations compared to standard venous analysers as the gold standard. Results from 100 patients undergoing ABG analysis and simultaneous venous sampling without therapeutic intervention between sampling were compared. Differences in haemoglobin, glucose, sodium and potassium concentrations were determined and analysed using statistical software (Statview). There was a significant difference (P 5 mmol/L), ABG readings varied significantly (P Arterial blood gas analysers are invaluable for rapid assessment of critically ill patients; however, estimations of haemoglobin, glucose and potassium concentrations (> 5 mmol/L) obtained from such machines should be interpreted with caution and confirmed using standard venous samples.

  2. A critical review of wetland greenhouse gas measurement techniques and scaling considerations

    Science.gov (United States)

    Allen, S. T.; Krauss, K. W.; Stagg, C. L.; Neubauer, S. C.

    2016-12-01

    The role of wetlands in terrestrial greenhouse gas fluxes is disproportionately large compared to the relatively small terrestrial area they encompass. There is an established and growing interest in accurately measuring these fluxes, and extrapolating inferences to larger spatial scales. However, a lack of uniformity in measurement approaches impedes progress because it is a challenge to synthesize data, parameterize models, and develop generalizable concepts from disparate data. Furthermore, pairing different methods can result in double-accounting and other aggregation errors. Our objective is to review gas flux measurement techniques and synthesize concepts, factors, and constraints associated with measuring and scaling greenhouse gas fluxes. This work will contribute to a conceptual framework designed to aid in the collection and use of gas flux data obtained by different methods. This review focuses specifically on wetlands which have both distinct transport processes and a unique biogeochemical environment, causing gas fluxes that are not prominent in other terrestrial or aquatic systems. We review techniques and implications of measuring at different steps along the soil-plant-atmosphere continuum; an emphasis of this work is identifying pathways and transit times for different fluxes in different wetland hydrogeomorphic settings. Measurement location along the path from source to atmosphere connotes the spatial and temporal scales at which a technique is applied, the spatiotemporal representation, and the factors that constrain extrapolation.

  3. Master singular behavior from correlation length measurements for seven one-component fluids near their gas-liquid critical point.

    Science.gov (United States)

    Garrabos, Yves; Palencia, Fabien; Lecoutre, Carole; Erkey, Can; Le Neindre, Bernard

    2006-02-01

    We present the master (i.e., unique) behavior of the correlation length, as a function of the thermal field along the critical isochore, asymptotically close to the gas-liquid critical point of xenon, krypton, argon, helium-3, sulfur hexafluoride, carbon dioxide, and heavy water. It is remarkable that this unicity extends to the correction-to-scaling terms. The critical parameter set, which contains all the needed information to reveal the master behavior, is composed of four thermodynamic coordinates of the critical point and one adjustable parameter which accounts for quantum effects in the helium-3 case. We use a scale dilatation method applied to the relevant physical variables of the one-component fluid subclass, in analogy with the basic hypothesis of the renormalization theory. This master behavior for the correlation length satisfies hyperscaling. We finally estimate the thermal field extent where the critical crossover of the singular thermodynamic and correlation functions deviates from the theoretical crossover function obtained from field theory.

  4. Critical Trajectories for the Human Settlement of the High Frontier

    Science.gov (United States)

    Valentine, Lee S.

    2007-02-01

    If preservation and prosperity of humanity on the Earth and human settlement of space are our goals, we should concentrate on a commercial path to get there. Commercial enterprise has a long history of fortuitously aiding scientific progress. We expect radical changes in the cost of earth to orbit transportation, and in the methods and efficacy of deep space transportation, within the next two decades. A successful space tourism industry, beginning with suborbital tourism, will greatly drive down the cost of access to orbit over the next 15 years. Inexpensive transportation to low Earth orbit is the first requirement for a great future on the High Frontier. Inexpensive means the cost associated with a mature transportation system. A mature system has a cost of three to five times the cost of the propellant. The first cheap, reliable and highly reusable rocket engines are just now appearing in vehicles. With an assured market and high flight rate, the heretofore glacial progress in reducing the cost of space transportation is likely to become rapid. This is the first critical enabling example of synergy between free market economics and scientific and technical progress in space. It will not be the last. New high power switches and ultracapacitors developed for the automotive market make possible cheap, robust and reliable mass driver engines. In space construction, using masses of nonterrestrial materials make the gravity tractor technique much more capable than previous schemes to maneuver asteroids. Ion propulsion will continue to improve and the first solar sails will be flown. Advanced robotics will allow remarkable improvements in productivity. The computing power available to robots began to follow the exponential Moore's law less than decade ago. The first commercial autonomous mobile robots appeared in late summer 2006. Humans, however, will be required for the foreseeable future in repair and supervisory roles, particularly in unstructured settings such as

  5. Evaluating the Hot Corrosion Behavior of High-Temperature Alloys for Gas Turbine Engine Components

    Science.gov (United States)

    Deodeshmukh, V. P.

    2015-11-01

    The hot corrosion behavior of high-temperature alloys is critically important for gas turbine engine components operating near the marine environments. The two test methods—Two-Zone and Burner-Rig—used to evaluate the hot corrosion performance of high-temperature alloys are illustrated by comparing the Type I hot corrosion behavior of selected high-temperature alloys. Although the ranking of the alloys is quite comparable, it is evident that the two-zone hot corrosion test is significantly more aggressive than the burner-rig test. The effect of long-term exposures and the factors that influence the hot corrosion performance of high-temperature alloys are briefly discussed.

  6. Internal hysteresis experienced on a high pressure syn gas compressor

    Science.gov (United States)

    Zeidan, F. Y.

    1984-01-01

    A vibration instability phenomenon experienced in operating high pressure syn gas centrifugal compressors in two ammonia plants is described. The compressors were monitored by orbit and spectrum analysis for changes from baseline readings. It is found that internal hysteresis was the major destabilizing force; however, the problem was further complicated by seal lockup at the suction end of the compressor. A coupling lockup problem and a coupling fit problem, which frettage of the shaft, are also considered as contributors to the self excited vibrations.

  7. Gas and high-performance liquid chromatography of phenols

    Energy Technology Data Exchange (ETDEWEB)

    Tesarova, E.; Pacakova, V.

    1983-05-01

    Gas (GC) and high-performance liquid chromatographic (HPLC) methods in the analysis of phenols are reviewed. Among the great number of phenolic compounds analyzed, alkylphenols, chlorophenols, dihydroxy-and trihydroxy-benzenes and biphenols are chiefly considered. The advantages and drawbacks of the methods are discussed. Relationships between the structural characteristics of phenols, the stationary phase structure, the mobile phase composition and the retention data are treated. Typical examples of the conditions for GC and HPLC analysis are summarized in tables. 276 references

  8. Examination of the relationship between project management critical success factors and project success of oil and gas drilling projects

    Science.gov (United States)

    Alagba, Tonye J.

    Oil and gas drilling projects are the primary means by which oil companies recover large volumes of commercially available hydrocarbons from deep reservoirs. These types of projects are complex in nature, involving management of multiple stakeholder interfaces, multidisciplinary personnel, complex contractor relationships, and turbulent environmental and market conditions, necessitating the application of proven project management best practices and critical success factors (CSFs) to achieve success. Although there is some practitioner oriented literature on project management CSFs for drilling projects, none of these is based on empirical evidence, from research. In addition, the literature has reported alarming rates of oil and gas drilling project failure, which is attributable not to technical factors, but to failure of project management. The aim of this quantitative correlational study therefore, was to discover an empirically verified list of project management CSFs, which consistent application leads to successful implementation of oil and gas drilling projects. The study collected survey data online, from a random sample of 127 oil and gas drilling personnel who were members of LinkedIn's online community "Drilling Supervisors, Managers, and Engineers". The results of the study indicated that 10 project management factors are individually related to project success of oil and gas drilling projects. These 10 CSFs are namely; Project mission, Top management support, Project schedule/plan, Client consultation, Personnel, Technical tasks, Client acceptance, Monitoring and feedback, Communication, and Troubleshooting. In addition, the study found that the relationships between the 10 CSFs and drilling project success is unaffected by participant and project demographics---role of project personnel, and project location. The significance of these findings are both practical, and theoretical. Practically, application of an empirically verified CSFs list to oil

  9. Large turbulent reservoirs of cold molecular gas around high-redshift starburst galaxies

    Science.gov (United States)

    Falgarone, E.; Zwaan, M. A.; Godard, B.; Bergin, E.; Ivison, R. J.; Andreani, P. M.; Bournaud, F.; Bussmann, R. S.; Elbaz, D.; Omont, A.; Oteo, I.; Walter, F.

    2017-08-01

    Starburst galaxies at the peak of cosmic star formation are among the most extreme star-forming engines in the Universe, producing stars over about 100 million years (ref. 2). The star-formation rates of these galaxies, which exceed 100 solar masses per year, require large reservoirs of cold molecular gas to be delivered to their cores, despite strong feedback from stars or active galactic nuclei. Consequently, starburst galaxies are ideal for studying the interplay between this feedback and the growth of a galaxy. The methylidyne cation, CH+, is a most useful molecule for such studies because it cannot form in cold gas without suprathermal energy input, so its presence indicates dissipation of mechanical energy or strong ultraviolet irradiation. Here we report the detection of CH+ (J = 1–0) emission and absorption lines in the spectra of six lensed starburst galaxies at redshifts near 2.5. This line has such a high critical density for excitation that it is emitted only in very dense gas, and is absorbed in low-density gas. We find that the CH+ emission lines, which are broader than 1,000 kilometres per second, originate in dense shock waves powered by hot galactic winds. The CH+ absorption lines reveal highly turbulent reservoirs of cool (about 100 kelvin), low-density gas, extending far (more than 10 kiloparsecs) outside the starburst galaxies (which have radii of less than 1 kiloparsec). We show that the galactic winds sustain turbulence in the 10-kiloparsec-scale environments of the galaxies, processing these environments into multiphase, gravitationally bound reservoirs. However, the mass outflow rates are found to be insufficient to balance the star-formation rates. Another mass input is therefore required for these reservoirs, which could be provided by ongoing mergers or cold-stream accretion. Our results suggest that galactic feedback, coupled jointly to turbulence and gravity, extends the starburst phase of a galaxy instead of quenching it.

  10. Critical Language Pedagogy in an Urban High School English Class

    Science.gov (United States)

    Godley, Amanda J.; Minnici, Angela

    2008-01-01

    The purpose of this study was to examine how classroom conversations about diverse dialects of English can provide a useful foundation for critical language and literacy instruction for students who speak African American Vernacular English (AAVE) and other stigmatized dialects. This article describes a weeklong unit on language variety that…

  11. High-energy gas fracturing in cased and perforated wellbores

    Energy Technology Data Exchange (ETDEWEB)

    Cuderman, J.F.

    1986-06-01

    A propellant-based technology, High-Energy Gas Fracturing (HEGF), has been applied to fracturing through perforations in cased boreholes. HEGF is a tailored-pulse fracturing technique originally developed by Sandia National Laboratories for application in uncased, liquid-free gas wells in Appalachian Devonian shales. Because most oil and gas wells are liquid filled as well as cased and perforated, the potential impact of present research is significantly broader. A number of commercial tailored-pulse fracturing services, using a variety of explosives or propellants, are currently available. Present research provides valuable insight into phenomena that occur in those stimulations. The use of propellants that deflagrate or burn rather than detonate, as do high-order explosives, permits controlled buildup of pressure in the wellbore. The key to successful stimulation in cased and perforated wellbores is to control the pressure buildup of the combustion gases to maximize fracturing without destroying the casing. Eight experiments using cased and perforated wellbore were conducted in a tunnel complex at the Department of Energy's Nevada Test Site, which provides a realistic in situ stress environment (4 to 10 MPa (600 to 1500 psi)) and provides access for mineback to directly observe fracturing obtained. Primary variables in the experiments include propellant burn rate and amount of propellant used, presence or absence of liquid in the wellbore, in situ stress orientation, and perforation diameter, density, and phasing. In general, the presence of liquid in the borehole results in a much faster pressure risetime and a lower peak pressure for the same propellant charge. Fracture surfaces proceed outward along lines of perforations as determined by phasing, then gradually turn toward the hydraulic fracture direction. 8 refs., 23 figs., 3 tabs.

  12. Multiphase forces on bend structures – critical gas fraction for transition single phase gas to multiphase flow behaviour

    NARCIS (Netherlands)

    Belfroid, S.P.C.; Nennie, E.D.; Lewis, M.

    2016-01-01

    Piping structures are generally subjected to high dynamic loading due to multiphase forces. In particular subsea structures are very vulnerable as large flexibility is required to cope for instance with thermal stresses. The forces due to multiphase flow are characterized by a broadband spectrum wit

  13. Multiphase forces on bend structures – critical gas fraction for transition single phase gas to multiphase flow behaviour

    NARCIS (Netherlands)

    Belfroid, S.P.C.; Nennie, E.D.; Lewis, M.

    2016-01-01

    Piping structures are generally subjected to high dynamic loading due to multiphase forces. In particular subsea structures are very vulnerable as large flexibility is required to cope for instance with thermal stresses. The forces due to multiphase flow are characterized by a broadband spectrum wit

  14. PERFLUOROCARBON GAS TRACER STUDIES TO SUPPORT RISK ASSESSMENT MODELING OF CRITICAL INFRASTRUCTURE SUBJECTED TO TERRORIST ATTACKS.

    Energy Technology Data Exchange (ETDEWEB)

    SULLIVAN, T.M.; HEISER, J.; WATSON, T.; ALLWINE, K.J.; FLAHERTY, J.E.

    2006-05-06

    Development of real-time predictive modeling to identify the dispersion and/or source(s) of airborne weapons of mass destruction including chemical, biological, radiological, and nuclear material in urban environments is needed to improve response to potential releases of these materials via either terrorist or accidental means. These models will also prove useful in defining airborne pollution dispersion in urban environments for pollution management/abatement programs. Predicting gas flow in an urban setting on a scale of less than a few kilometers is a complicated and challenging task due to the irregular flow paths that occur along streets and alleys and around buildings of different sizes and shapes, i.e., ''urban canyons''. In addition, air exchange between the outside and buildings and subway areas further complicate the situation. Transport models that are used to predict dispersion of WMD/CBRN materials or to back track the source of the release require high-density data and need defensible parameterizations of urban processes. Errors in the data or any of the parameter inputs or assumptions will lead to misidentification of the airborne spread or source release location(s). The need for these models to provide output in a real-time fashion if they are to be useful for emergency response provides another challenge. To improve the ability of New York City's (NYC's) emergency management teams and first response personnel to protect the public during releases of hazardous materials, the New York City Urban Dispersion Program (UDP) has been initiated. This is a four year research program being conducted from 2004 through 2007. This paper will discuss ground level and subway Perfluorocarbon tracer (PFT) release studies conducted in New York City. The studies released multiple tracers to study ground level and vertical transport of contaminants. This paper will discuss the results from these tests and how these results can be used

  15. High pressure gas flow, storage, and displacement in fractured rock-Experimental setup development and application.

    Science.gov (United States)

    Hadi Mosleh, M; Turner, M; Sedighi, M; Vardon, P J

    2017-01-01

    This paper presents the design, development, and application of a laboratory setup for the experimental investigations of gas flow and reactions in a fractured rock. The laboratory facility comprises (i) a high pressure manometric sorption apparatus, where equilibrium and kinetic phenomena of adsorption and desorption can be examined, (ii) a high pressure triaxial core flooding system where the chemical reactive transport properties or processes can be explored, and (iii) an ancillary system including pure and mixed gas supply and analysis units. Underground conditions, in terms of pore pressure, confining pressure, and temperature, can be replicated using the triaxial core flooding system developed for depths up to 2 km. Core flooding experiments can be conducted under a range of gas injection pressures up to 20 MPa and temperatures up to 338 K. Details of the design considerations and the specification for the critical measuring instruments are described. The newly developed laboratory facility has been applied to study the adsorption of N2, CH4, and CO2 relevant to applications in carbon sequestration in coal and enhanced coalbed methane recovery. Under a wide range of pressures, the flow of helium in a core sample was studied and the evolution of absolute permeability at different effective stress conditions has been investigated. A comprehensive set of high resolution data has been produced on anthracite coal samples from the South Wales coalfield, using the developed apparatus. The results of the applications provide improved insight into the high pressure flow and reaction of various gas species in the coal samples from the South Wales coalfield.

  16. High pressure gas flow, storage, and displacement in fractured rock—Experimental setup development and application

    Science.gov (United States)

    Hadi Mosleh, M.; Turner, M.; Sedighi, M.; Vardon, P. J.

    2017-01-01

    This paper presents the design, development, and application of a laboratory setup for the experimental investigations of gas flow and reactions in a fractured rock. The laboratory facility comprises (i) a high pressure manometric sorption apparatus, where equilibrium and kinetic phenomena of adsorption and desorption can be examined, (ii) a high pressure triaxial core flooding system where the chemical reactive transport properties or processes can be explored, and (iii) an ancillary system including pure and mixed gas supply and analysis units. Underground conditions, in terms of pore pressure, confining pressure, and temperature, can be replicated using the triaxial core flooding system developed for depths up to 2 km. Core flooding experiments can be conducted under a range of gas injection pressures up to 20 MPa and temperatures up to 338 K. Details of the design considerations and the specification for the critical measuring instruments are described. The newly developed laboratory facility has been applied to study the adsorption of N2, CH4, and CO2 relevant to applications in carbon sequestration in coal and enhanced coalbed methane recovery. Under a wide range of pressures, the flow of helium in a core sample was studied and the evolution of absolute permeability at different effective stress conditions has been investigated. A comprehensive set of high resolution data has been produced on anthracite coal samples from the South Wales coalfield, using the developed apparatus. The results of the applications provide improved insight into the high pressure flow and reaction of various gas species in the coal samples from the South Wales coalfield.

  17. High temperature and high pressure gas cell for quantitative spectroscopic measurements

    DEFF Research Database (Denmark)

    Christiansen, Caspar; Stolberg-Rohr, Thomine; Fateev, Alexander

    2016-01-01

    A high temperature and high pressure gas cell (HTPGC) has been manufactured for quantitative spectroscopic measurements in the pressure range 1-200 bar and temperature range 300-1300 K. In the present work the cell was employed at up to 100 bar and 1000 K, and measured absorption coefficients...

  18. High pressure hydrocracking of vacuum gas oil to middle distillates

    Science.gov (United States)

    Lahiri, C. R.; Biswas, Dipa

    1986-05-01

    Hydrocracking of heavier petroleum fractions into lighter ones is of increasing importance today to meet the huge demand, particularly for gasoline and middle distillates. Much work on hydrocracking of a gas oil range feed stock to mainly gasoline using modified zeolite catalyst-base exchanged with metals (namely Ni, Pd, Mo, etc.) has been reported. In India, however, present demand is for a maximum amount of middle distillate. The present investigation was therefore aimed to maximize the yield of middle distillate (140-270°C boiling range) by hydrocracking a vacuum gas oil (365-450°C boiling range) fraction from an Indian Refinery at high hydrogen pressure and temperature. A zeolite catalyst-base exchanged with 4.5% Ni was chosen for the reaction. A high pressure batch reactor with a rocking arrangement was used for the study. No pretreatment of the feed stock for sulphur removal applied as the total sulphur in the feed was less than 2%. The process variables studied for the maximum yield of the middle distillate were temperature 300-450°C, pressure 100-200 bar and residence period 1-3 h at the feed to catalyst ratio of 9.3 (wt/wt). The optimum conditions for the maximum yield of 36% middle distillate of the product were: temperature 400°C, pressure 34.5 bar (initially) and residence period 2 h. A carbon balance of 90-92% was found for each run.

  19. Measurement and interpretation of threshold stress intensity factors for steels in high-pressure hydrogen gas.

    Energy Technology Data Exchange (ETDEWEB)

    Dadfarnia, Mohsen (University of Illinois at Urbana-Champaign, Urbana, IL); Nibur, Kevin A.; San Marchi, Christopher W.; Sofronis, Petros (University of Illinois at Urbana-Champaign, Urbana, IL); Somerday, Brian P.; Foulk, James W., III; Hayden, Gary A. (CP Industries, McKeesport, PA)

    2010-07-01

    Threshold stress intensity factors were measured in high-pressure hydrogen gas for a variety of low alloy ferritic steels using both constant crack opening displacement and rising crack opening displacement procedures. The sustained load cracking procedures are generally consistent with those in ASME Article KD-10 of Section VIII Division 3 of the Boiler and Pressure Vessel Code, which was recently published to guide design of high-pressure hydrogen vessels. Three definitions of threshold were established for the two test methods: K{sub THi}* is the maximum applied stress intensity factor for which no crack extension was observed under constant displacement; K{sub THa} is the stress intensity factor at the arrest position for a crack that extended under constant displacement; and K{sub JH} is the stress intensity factor at the onset of crack extension under rising displacement. The apparent crack initiation threshold under constant displacement, K{sub THi}*, and the crack arrest threshold, K{sub THa}, were both found to be non-conservative due to the hydrogen exposure and crack-tip deformation histories associated with typical procedures for sustained-load cracking tests under constant displacement. In contrast, K{sub JH}, which is measured under concurrent rising displacement and hydrogen gas exposure, provides a more conservative hydrogen-assisted fracture threshold that is relevant to structural components in which sub-critical crack extension is driven by internal hydrogen gas pressure.

  20. Hydrogen gas filling into an actual tank at high pressure and optimization of its thermal characteristics

    Science.gov (United States)

    Khan, Md. Tawhidul Islam; Monde, Masanori; Setoguchi, Toshiaki

    2009-09-01

    Gas with high pressure is widely used at present as fuel storage mode for different hydrogen vehicles. Different types of materials are used for constructing these hydrogen pressure vessels. An aluminum lined vessel and typically carbon fiber reinforced plastic (CFRP) materials are commercially used in hydrogen vessels. An aluminum lined vessel is easy to construct and posses high thermal conductivity compared to other commercially available vessels. However, compared to CFRP lined vessel, it has low strength capacity and safety factors. Therefore, nowadays, CFRP lined vessels are becoming more popular in hydrogen vehicles. Moreover, CFRP lined vessel has an advantage of light weight. CFRP, although, has many desirable properties in reducing the weight and in increasing the strength, it is also necessary to keep the material temperature below 85 °C for maintaining stringent safety requirements. While filling process occurs, the temperature can be exceeded due to the compression works of the gas flow. Therefore, it is very important to optimize the hydrogen filling system to avoid the crossing of the critical limit of the temperature rise. Computer-aided simulation has been conducted to characterize the hydrogen filling to optimize the technique. Three types of hydrogen vessels with different volumes have been analyzed for optimizing the charging characteristics of hydrogen to test vessels. Gas temperatures are measured inside representative vessels in the supply reservoirs (H2 storages) and at the inlet to the test tank during filling.

  1. Low-profile high-voltage compact gas switch

    Energy Technology Data Exchange (ETDEWEB)

    Goerz, D.A.; Wilson, M.J.; Speer, R.D.

    1997-06-30

    This paper discusses the development and testing of a low-profile, high-voltage, spark-gap switch designed to be closely coupled with other components into an integrated high-energy pulsed-power source. The switch is designed to operate at 100 kV using SF6 gas pressurized to less than 0.7 MPa. The volume of the switch cavity region is less than 1.5 cm3, and the field stress along the gas-dielectric interface is as high as 130 kV/cm. The dielectric switch body has a low profile that is only I -cm tall at its greatest extent and nominally 2-mm thick over most of its area. This design achieves a very low inductance of less than 5 nH, but results in field stresses exceeding 500 kV/cm in the dielectric material. Field modeling was done to determine the appropriate shape for the highly stressed insulator and electrodes, and special manufacturing techniques were employed to mitigate the usual mechanisms that induce breakdown and failure in solid dielectrics. Static breakdown tests verified that the switch operates satisfactorily at 100 kV levels. The unit has been characterized with different shaped electrodes having nominal gap spacings of 2.0, 2.5, and 3.0 mm. The relationship between self-break voltage and operating pressure agrees well with published data on gas properties, accounting for the field enhancements of the electrode shapes being used. Capacitor discharge tests in a low inductance test fixture exhibited peak currents up to 25 kA with characteristic frequencies of the ringdown circuit ranging from 10 to 20 MHz. The ringdown waveforms and scaling of measured parameters agree well with circuit modeling of the switch and test fixture. Repetitive operation has been demonstrated at moderate rep-rates up to 15 Hz, limited by the power supply being used. Preliminary tests to evaluate lifetime of the compact switch assembly have been encouraging. In one case, after more than 7,000 high-current ringdown tests with approximately 30 C of total charge transferred, the

  2. A system for incubations at high gas partial pressure.

    Science.gov (United States)

    Sauer, Patrick; Glombitza, Clemens; Kallmeyer, Jens

    2012-01-01

    High-pressure is a key feature of deep subsurface environments. High partial pressure of dissolved gasses plays an important role in microbial metabolism, because thermodynamic feasibility of many reactions depends on the concentration of reactants. For gases, this is controlled by their partial pressure, which can exceed 1 MPa at in situ conditions. Therefore, high hydrostatic pressure alone is not sufficient to recreate true deep subsurface in situ conditions, but the partial pressure of dissolved gasses has to be controlled as well. We developed an incubation system that allows for incubations at hydrostatic pressure up to 60 MPa, temperatures up to 120°C, and at high gas partial pressure. The composition and partial pressure of gasses can be manipulated during the experiment. To keep costs low, the system is mainly made from off-the-shelf components with only very few custom-made parts. A flexible and inert PVDF (polyvinylidene fluoride) incubator sleeve, which is almost impermeable for gases, holds the sample and separates it from the pressure fluid. The flexibility of the incubator sleeve allows for sub-sampling of the medium without loss of pressure. Experiments can be run in both static and flow-through mode. The incubation system described here is usable for versatile purposes, not only the incubation of microorganisms and determination of growth rates, but also for chemical degradation or extraction experiments under high gas saturation, e.g., fluid-gas-rock-interactions in relation to carbon dioxide sequestration. As an application of the system we extracted organic compounds from sub-bituminous coal using H(2)O as well as a H(2)O-CO(2) mixture at elevated temperature (90°C) and pressure (5 MPa). Subsamples were taken at different time points during the incubation and analyzed by ion chromatography. Furthermore we demonstrated the applicability of the system for studies of microbial activity, using samples from the Isis mud volcano. We could

  3. A system for incubations at high gas partial pressure

    Directory of Open Access Journals (Sweden)

    Patrick eSauer

    2012-02-01

    Full Text Available High-pressure is a key feature of deep subsurface environments. High partial pressure of dissolved gasses plays an important role in microbial metabolism, because thermodynamic feasibility of many reactions depends on the concentration of reactants. For gases, this is controlled by their partial pressure, which can exceed one MPa at in-situ conditions. Therefore, high hydrostatic pressure alone is not sufficient to recreate true deep subsurface in-situ conditions, but the partial pressure of dissolved gasses has to be controlled as well.We developed an incubation system that allows for incubations at hydrostatic pressure up to 60 MPa, temperatures up to 120° C and at high gas partial pressure. The composition and partial pressure of gasses can be manipulated during the experiment. The system is mainly made from off-the-shelf components with only very few custom-made parts. A flexible and inert PVDF incubator sleeve, which is almost impermeable for gases, holds the sample and separates it from the pressure fluid. The flexibility of the incubator sleeve allows for sub-sampling of the medium without loss of pressure. Experiments can be run in both static and flow through mode. The incubation system described here is usable for versatile purposes, not only the incubation of microorganisms and determination of growth rates, but also for chemical degradation or extraction experiments under high gas saturation, e.g. fluid-gas-rock-interactions in relation to carbon dioxide sequestration.As an application of the system we extracted organic acids from sub-bituminous coal using H2O as well as a H2O-CO2 mixture at elevated temperature (90°C and pressure (5 MPa. Subsamples were taken during the incubation and analysed by ion chromatography. Furthermore we demonstrated the applicability of the system for studies of microbial activity, using samples from the Isis mud volcano. We could detect an increase in sulphate reduction rate upon the addition of

  4. The Precise Mechanisms of a High-Speed Ultrasound Gas Sensor and Detecting Human-Specific Lung Gas Exchange

    Directory of Open Access Journals (Sweden)

    Hideki Toda

    2012-12-01

    Full Text Available In this paper, we propose and develop a new real-time human respiration process analysis method using a high-time-sampling gas concentration sensor based on ultrasound. A unique point about our proposed gas concentration sensor is its 1 kHz gas concentration sampling speed. This figure could not have been attained by previously proposed gas concentration measurement methods such as InfraRed, semiconductor gas sensors, or GC-MS, because the gas analysis speeds were a maximum of a few hundred milliseconds. First, we describe the proposed new ultrasound sound speed measurement method and the signal processing, and present the measurement circuit diagram. Next, we analyse the human respiration gas variation patterns of five healthy subjects using a newly developed gas-mask-type respiration sensor. This reveals that the rapid gas exchange from H2O to CO2 contains air specific to the human being. In addition, we also measured medical symptoms in subjects suffering from asthma, hyperventilation and bronchial asthma. The millisecond level high-speed analysis of the human respiration process will be useful for the next generation of healthcare, rehabilitation and sports science technology.

  5. Nanomechanical Behavior of High Gas Barrier Multilayer Thin Films.

    Science.gov (United States)

    Humood, Mohammad; Chowdhury, Shahla; Song, Yixuan; Tzeng, Ping; Grunlan, Jaime C; Polycarpou, Andreas A

    2016-05-04

    Nanoindentation and nanoscratch experiments were performed on thin multilayer films manufactured using the layer-by-layer (LbL) assembly technique. These films are known to exhibit high gas barrier, but little is known about their durability, which is an important feature for various packaging applications (e.g., food and electronics). Films were prepared from bilayer and quadlayer sequences, with varying thickness and composition. In an effort to evaluate multilayer thin film surface and mechanical properties, and their resistance to failure and wear, a comprehensive range of experiments were conducted: low and high load indentation, low and high load scratch. Some of the thin films were found to have exceptional mechanical behavior and exhibit excellent scratch resistance. Specifically, nanobrick wall structures, comprising montmorillonite (MMT) clay and polyethylenimine (PEI) bilayers, are the most durable coatings. PEI/MMT films exhibit high hardness, large elastic modulus, high elastic recovery, low friction, low scratch depth, and a smooth surface. When combined with the low oxygen permeability and high optical transmission of these thin films, these excellent mechanical properties make them good candidates for hard coating surface-sensitive substrates, where polymers are required to sustain long-term surface aesthetics and quality.

  6. A Criticism of "Gas Mode" Reinterpretations of the Michelson-Morley and Similar Experiments

    CERN Document Server

    Shanahan, Daniel

    2014-01-01

    It has been argued by R. T. Cahill and others that a Michelson interferometer in "gas mode" - in which the light paths are through an included gaseous medium - are able to detect and have detected an absolute frame of reference. It is shown here that this argument supposes incorrectly that the reduced velocity of light in gas is an observer-independent invariant. This velocity is not invariant, but given in a frame with respect to which the interferometer moves with velocity v by the usual relativistic formula for the addition of velocities, these being in this case the velocity v and the reduced velocity of light in the inertial frame of the interferometer. It is suggested nonetheless that though the absolute frame urged by Cahill may be undetectable, there are persuasive grounds for considering the alternative Lorentzian Relativity that did suppose the existence of such a frame.

  7. Critical appraisal of some factors pertinent to the functional designs of the gas exchangers.

    Science.gov (United States)

    Maina, John N

    2017-03-01

    Respiration acquires O2 from the external fluid milieu and eliminates CO2 back into the same. Gas exchangers evolved under certain immutable physicochemical laws upon which their elemental functional design is hardwired. Adaptive changes have occurred within the constraints set by such laws to satisfy metabolic needs for O2, environmental conditions, respiratory medium utilized, lifestyle pursued and phylogenetic level of development: correlation between structure and function exists. After the inaugural simple cell membrane, as body size and structural complexity increased, respiratory organs formed by evagination or invagination: the gills developed by the former process and the lungs by the latter. Conservation of water on land was the main driver for invagination of the lungs. In gills, respiratory surface area increases by stratified arrangement of the structural components while in lungs it occurs by internal subdivision. The minuscule terminal respiratory units of lungs are stabilized by surfactant. In gas exchangers, respiratory fluid media are transported by convection over long distances, a process that requires energy. However, movement of respiratory gases across tissue barriers occurs by simple passive diffusion. Short distances and large surface areas are needed for diffusion to occur efficiently. Certain properties, e.g., diffusion of gases through the tissue barrier, stabilization of the respiratory units by surfactant and a thin tripartite tissue barrier, have been conserved during the evolution of the gas exchangers. In biology, such rare features are called Bauplans, blueprints or frozen cores. That several of them (Bauplans) exist in gas exchangers almost certainly indicates the importance of respiration to life.

  8. Running on Fumes: A Critical Look at Mexico’s Natural Gas Transportation and Distribution Infrastructure

    Science.gov (United States)

    2011-10-27

    behind existing laws and policies that are hampering growth and development in Mexico’s petrochemical industry. 3 Petroleos Mexicanos ( PEMEX ...is the state-owned company created in 1938 to run the national oil and natural gas monopoly. In the decades that followed, PEMEX often utilized...privatization of PEMEX and its subsidiaries. The PRD has proposed an alternate plan, developed by founding PRD member 4 and adviser to the National

  9. The Critical Flow back Velocity in Hydraulic-Fracturing Shale Gas Wells

    Directory of Open Access Journals (Sweden)

    Zheng Zhang

    2016-02-01

    Full Text Available The loss of prop pant during the flow back process in hydraulic fracturing treatments has been a problem for many years. The effectiveness of the fracture treatment is reduced. A well cleanup is often required to remove the unwanted proppant from the wellbore to re-establish production. Among several techniques available to reduce the prop pant loss, controlling flow back velocity within a critical range is an essential measure. The objective of this study is to determine the critical flow back velocity under different confining pressures in the propped fractures of different thicknesses. This objective is achieved based experimental studies conducted in a specially designed apparatus. For a fracture with a given width, the closure stress helps hold the proppant in place. This is due to the friction force that is proportional to the normal force created by the closure stress. The critical flow back velocity necessary to mobilize the proppant therefore increases with closure stress. However, the stress effect may be influenced by the shape of solid particles and friction coefficient of solid. Under the condition of constant closure stress, a narrow fracture holds proppant better than a wide fracture, resulting in increased critical flow back velocity. This is interpreted to be due to the “tighter” packing of proppant in narrow fractures.

  10. The first low-mass stars: critical metallicity or dust-to-gas ratio?

    CERN Document Server

    Schneider, Raffaella; Bianchi, Simone; Valiante, Rosa

    2011-01-01

    We explore the minimal conditions which enable the formation of metal-enriched solar and sub-solar mass stars. We find that in the absence of dust grains, gas fragmentation occurs at densities nH ~ [10^4-10^5]cm^{-3} when the metallicity exceeds Z ~ 10^{-4} Zsun. The resulting fragmentation masses are > 10 Msun. The inclusion of Fe and Si cooling does not affect the thermal evolution as this is dominated by molecular cooling even for metallicities as large as Z = 10^{-2} Zsun. The presence of dust is the key driver for the formation of low-mass stars. We focus on three representative core-collapse supernova (SN) progenitors, and consider the effects of reverse shocks of increasing strength: these reduce the depletion factors, fdep = Mdust/(Mdust+Mmet), alter the shape of the grain size distribution function and modify the relative abundances of grain species and of metal species in the gas phase. We find that the lowest metallicity at which fragmentation occurs is Z=10^{-6} Zsun for gas pre-enriched by the ex...

  11. Survey of industrial coal conversion equipment capabilities: high-temperature, high-pressure gas purification

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, J. P.; Edwards, M. S.

    1978-06-01

    In order to ensure optimum operating efficiencies for combined-cycle electric generating systems, it is necessary to provide gas treatment equipment capable of operating at high temperatures (>1000/sup 0/F) and high pressure (>10 atmospheres absolute). This equipment, when assembled in a process train, will be required to condition the inlet stream to a gas turbine to suitable levels of gas purity (removal of particulate matter, sulfur, nitrogen, and alkali metal compounds) so that it will be compatible with both environmental and machine constraints. In this work, a survey of the available and developmental equipment for the removal of particulate matter and sulfur compounds has been conducted. In addition, an analysis has been performed to evaluate the performance of a number of alternative process configurations in light of overall system needs. Results from this study indicate that commercially available, reliable, and economically competitive hot-gas cleanup equipment capable of conditioning raw product gas to the levels required for high-temperatue turbine operation will not be available for some time.

  12. Novel Gas Sensors for High-Temperature Fossil Fuel Applications

    Energy Technology Data Exchange (ETDEWEB)

    Palitha Jayaweera; Francis Tanzella

    2005-03-01

    SRI International (SRI) is developing ceramic-based microsensors to detect exhaust gases such as NO, NO{sub 2}, and CO in advanced combustion and gasification systems under this DOE NETL-sponsored research project. The sensors detect the electrochemical activity of the exhaust gas species on catalytic electrodes attached to a solid state electrolyte and are designed to operate at the high temperatures, elevated pressures, and corrosive environments typical of large power generation exhausts. The sensors can be easily integrated into online monitoring systems for active emission control. The ultimate objective is to develop sensors for multiple gas detection in a single package, along with data acquisition and control software and hardware, so that the information can be used for closed-loop control in novel advanced power generation systems. This report details the Phase I Proof-of-Concept, research activities performed from October 2003 to March 2005. SRI's research work includes synthesis of catalytic materials, sensor design and fabrication, software development, and demonstration of pulse voltammetric analysis of NO, NO{sub 2}, and CO gases on catalytic electrodes.

  13. High Altitude Aerial Natural Gas Leak Detection System

    Energy Technology Data Exchange (ETDEWEB)

    Richard T. Wainner; Mickey B. Frish; B. David Green; Matthew C. Laderer; Mark G. Allen; Joseph R. Morency

    2006-12-31

    The objective of this program was to develop and demonstrate a cost-effective and power-efficient advanced standoff sensing technology able to detect and quantify, from a high-altitude (> 10,000 ft) aircraft, natural gas leaking from a high-pressure pipeline. The advanced technology is based on an enhanced version of the Remote Methane Leak Detector (RMLD) platform developed previously by Physical Sciences Inc. (PSI). The RMLD combines a telecommunications-style diode laser, fiber-optic components, and low-cost DSP electronics with the well-understood principles of Wavelength Modulation Spectroscopy (WMS), to indicate the presence of natural gas located between the operator and a topographic target. The transceiver transmits a laser beam onto a topographic target and receives some of the laser light reflected by the target. The controller processes the received light signal to deduce the amount of methane in the laser's path. For use in the airborne platform, we modified three aspects of the RMLD, by: (1) inserting an Erbium-doped optical fiber laser amplifier to increase the transmitted laser power from 10 mW to 5W; (2) increasing the optical receiver diameter from 10 cm to 25 cm; and (3) altering the laser wavelength from 1653 nm to 1618 nm. The modified RMLD system provides a path-integrated methane concentration sensitivity {approx}5000 ppm-m, sufficient to detect the presence of a leak from a high capacity transmission line while discriminating against attenuation by ambient methane. In ground-based simulations of the aerial leak detection scenario, we demonstrated the ability to measure methane leaks within the laser beam path when it illuminates a topographic target 2000 m away. We also demonstrated simulated leak detection from ranges of 200 m using the 25 cm optical receiver without the fiber amplifier.

  14. Study on the Performance Improvement of Ship Propulsion Equipment Directly Driven by High-Pressure Gas

    Science.gov (United States)

    Tsutahara, Michihisa; Ogawa, Kazuhiko; Sakamoto, Masahiko; Matsui, Takahiro; Tajiri, Shinsuke; Tajima, Masakazu; Yokoyama, Hiroki

    The flow inside the two-dimensional semi-open-type nozzle for ship propulsion equipment, directly driven by high-pressure gas was investigated experimentally. The flow was unsteady and the gas and water phases clearly separated. We found that these waves appear on the interface for continuous gas ejection. It was clarified that waves play an important role in the pressure distribution. Intermittent gas ejection was also tried. The thrust itself decreases compared with continuous gas ejection, but propulsion efficiency, considering the gas ejection duration is increased. The flow patterns for intermittent gas ejection were also clarified.

  15. NMR/MRI with hyperpolarized gas and high Tc SQUID

    Science.gov (United States)

    Schlenga, Klaus; de Souza, Ricardo E.; Wong-Foy, Annjoe; Clarke, John; Pines, Alexander

    2000-01-01

    A method and apparatus for the detection of nuclear magnetic resonance (NMR) signals and production of magnetic resonance imaging (MRI) from samples combines the use of hyperpolarized inert gases to enhance the NMR signals from target nuclei in a sample and a high critical temperature (Tc) superconducting quantum interference device (SQUID) to detect the NMR signals. The system operates in static magnetic fields of 3 mT or less (down to 0.1 mT), and at temperatures from liquid nitrogen (77K) to room temperature. Sample size is limited only by the size of the magnetic field coils and not by the detector. The detector is a high Tc SQUID magnetometer designed so that the SQUID detector can be very close to the sample, which can be at room temperature.

  16. Jet fire consequence modeling for high-pressure gas pipelines

    Science.gov (United States)

    Coccorullo, Ivano; Russo, Paola

    2016-12-01

    A simple and reliable approach for sizing the hazard area potentially affected by a jet fire as consequence of the failure of high-pressure pipeline is proposed. A release rate model, taking pipeline operation properties and source release properties into account, is coupled with SLAB dispersion model and point source radiation model to calculate the hazard distance. The hazard distance is set beyond the distance at which a low chance of fatality can occur to people exposed and a wooden structure is not expected to burn due to radiation heat of jet fire. The comparison between three gases with different physico-chemical properties (i.e. natural gas, hydrogen, ethylene) is shown. The influence of pipeline operating parameters, such as: pressure, pipeline diameter and length, hole size, on the hazard area for the three gases is evaluated. Finally, a simple correlation is proposed for calculating the hazard distance as function of these parameters.

  17. High Power Light Gas Helicon Plasma Source for VASIMR

    Science.gov (United States)

    Squire, Jared P.; Chang-Diaz, Franklin R.; Glover, Timothy W.; Jacobson, Verlin T.; Baity, F. Wally; Carter, Mark D.; Goulding, Richard H.

    2004-01-01

    In the Advanced Space Propulsion Laboratory (ASPL) helicon experiment (VX-10) we have measured a plasma flux to input gas rate ratio near 100% for both helium and deuterium at power levels up to 10 kW. Recent results at Oak Ridge National Laboratory (ORNL) show enhanced efficiency operation with a high power density, over 5 kW in a 5 cm diameter tube. Our helicon is presently 9 cm in diameter and operates up to 10 kW of input power. The data here uses a Boswell double-saddle antenna design with a magnetic cusp just upstream of the antenna. Similar to ORNL, for deuterium at near 10 kW, we find an enhanced performance of operation at magnetic fields above the lower hybrid matching condition.

  18. High Power Light Gas Helicon Plasma Source for VASIMR

    Science.gov (United States)

    Squire, Jared P.; Chang-Diaz, Franklin R.; Glover, Timothy W.; Jacobson, Verlin T.; Baity, F. Wally; Carter, Mark D.; Goulding, Richard H.

    2004-01-01

    In the Advanced Space Propulsion Laboratory (ASPL) helicon experiment (VX-10) we have measured a plasma flux to input gas rate ratio near 100% for both helium and deuterium at power levels up to 10 kW. Recent results at Oak Ridge National Laboratory (ORNL) show enhanced efficiency operation with a high power density, over 5 kW in a 5 cm diameter tube. Our helicon is presently 9 cm in diameter and operates up to 10 kW of input power. The data here uses a Boswell double-saddle antenna design with a magnetic cusp just upstream of the antenna. Similar to ORNL, for deuterium at near 10 kW, we find an enhanced performance of operation at magnetic fields above the lower hybrid matching condition.

  19. A High Reliability Gas-driven Helium Cryogenic Centrifugal Compressor

    CERN Document Server

    Bonneton, M; Gistau-Baguer, Guy M; Turcat, F; Viennot, P

    1998-01-01

    A helium cryogenic compressor was developed and tested in real conditions in 1996. The achieved objective was to compress 0.018 kg/s Helium at 4 K @ 1000 Pa (10 mbar) up to 3000 Pa (30 mbar). This project was an opportunity to develop and test an interesting new concept in view of future needs. The main features of this new specific technology are described. Particular attention is paid to the gas bearing supported rotor and to the pneumatic driver. Trade off between existing technologies and the present work are presented with special stress on the bearing system and the driver. The advantages are discussed, essentially focused on life time and high reliability without maintenance as well as non pollution characteristic. Practical operational modes are also described together with the experimental performances of the compressor. The article concludes with a brief outlook of future work.

  20. High-Temperature Water-Gas Shift Membrane Reactor Study

    Energy Technology Data Exchange (ETDEWEB)

    Ciocco, M.V.; Iyoha, O.; Enick, R.M.; Killmeyer, R.P.

    2007-06-01

    NETL’s Office of Research and Development is exploring the integration of membrane reactors into coal gasification plants as a way of increasing efficiency and reducing costs. Water-Gas Shift Reaction experiments were conducted in membrane reactors at conditions similar to those encountered at the outlet of a coal gasifier. The changes in reactant conversion and product selectivity due to the removal of hydrogen via the membrane reactor were quantified. Research was conducted to determine the influence of residence time and H2S on CO conversion in both Pd and Pd80wt%Cu membrane reactors. Effects of the hydrogen sulfide-to-hydrogen ratio on palladium and a palladium-copper alloy at high-temperature were also investigated. These results were compared to thermodynamic calculations for the stability of palladium sulfides.

  1. High-voltage, low-inductance gas switch

    Science.gov (United States)

    Gruner, Frederick R.; Stygar, William A.

    2016-03-22

    A low-inductance, air-insulated gas switch uses a de-enhanced annular trigger ring disposed between two opposing high voltage electrodes. The switch is DC chargeable to 200 kilovolts or more, triggerable, has low jitter (5 ns or less), has pre-fire and no-fire rates of no more than one in 10,000 shots, and has a lifetime of greater than 100,000 shots. Importantly, the switch also has a low inductance (less than 60 nH) and the ability to conduct currents with less than 100 ns rise times. The switch can be used with linear transformer drives or other pulsed-power systems.

  2. The Coulomb gas representation of critical RSOS models on the sphere and the torus

    Energy Technology Data Exchange (ETDEWEB)

    Foda, O. (Rijksuniversiteit Utrecht (Netherlands). Inst. voor Theoretische Fysica); Nienhuis, B. (Rijksuniversiteit Leiden (Netherlands). Inst. Lorentz voor Theoretische Natuurkunde)

    1989-10-02

    We derive the Coulomb gas formulation of the c<1 discrete unitary series, on the sphere and the torus, starting from the corresponding regime-III RSOS models on a square lattice with appropriate topology. We clarify the origin of the background charge, the screening charges, and the choice of operator representations in a correlation function. In the scaling limit, we obtain a bosonic action coupled to the background curvature in addition to topological terms that vanish on the Riemann sphere. Its Virasoro algebra has the central charge expected on the basis of comparing conformal dimensions. As an application, we derive general expressions for the correlation functions on the torus. (orig.).

  3. Survey of processes for high temperature-high pressure gas purification. [52 references

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, J.P.; Edwards, M.S.

    1978-11-01

    In order to ensure the optimum operating efficiency of a combined-cycle electric power generating system, it is necessary to provide gas treatment processes capable of operating at high temperatures (> 1000/sup 0/F) and high pressures (> 10 atm (absolute)). These systems will be required to condition the inlet stream to the gas turbine to suitable levels of gas purity (removal of particulate matter, sulfur, nitrogen, and alkali metal compounds) to be compatible with both environmental and machine constraints. A survey of the available and developmental processes for the removal of these various contaminant materials has been conducted. Based on the data obtained from a variety of sources, an analysis has been performed to evaluate the performance of a number of potential cleanup processes in view of the overall system needs. The results indicate that commercially available, reliable, and economically competitive hot-gas cleanup systems (for the removal of H/sub 2/S, particulate matter, alkali, and nitrogen compounds) capable of conditioning raw product gas to the levels required for turbine use will not be available for some time.

  4. Supersonic beams at high particle densities: model description beyond the ideal gas approximation.

    Science.gov (United States)

    Christen, Wolfgang; Rademann, Klaus; Even, Uzi

    2010-10-28

    Supersonic molecular beams constitute a very powerful technique in modern chemical physics. They offer several unique features such as a directed, collision-free flow of particles, very high luminosity, and an unsurpassed strong adiabatic cooling during the jet expansion. While it is generally recognized that their maximum flow velocity depends on the molecular weight and the temperature of the working fluid in the stagnation reservoir, not a lot is known on the effects of elevated particle densities. Frequently, the characteristics of supersonic beams are treated in diverse approximations of an ideal gas expansion. In these simplified model descriptions, the real gas character of fluid systems is ignored, although particle associations are responsible for fundamental processes such as the formation of clusters, both in the reservoir at increased densities and during the jet expansion. In this contribution, the various assumptions of ideal gas treatments of supersonic beams and their shortcomings are reviewed. It is shown in detail that a straightforward thermodynamic approach considering the initial and final enthalpy is capable of characterizing the terminal mean beam velocity, even at the liquid-vapor phase boundary and the critical point. Fluid properties are obtained using the most accurate equations of state available at present. This procedure provides the opportunity to naturally include the dramatic effects of nonideal gas behavior for a large variety of fluid systems. Besides the prediction of the terminal flow velocity, thermodynamic models of isentropic jet expansions permit an estimate of the upper limit of the beam temperature and the amount of condensation in the beam. These descriptions can even be extended to include spinodal decomposition processes, thus providing a generally applicable tool for investigating the two-phase region of high supersaturations not easily accessible otherwise.

  5. Studying gas emission rhythms based on data of mines with high gas output

    Energy Technology Data Exchange (ETDEWEB)

    Kovacs, F.

    1983-01-01

    Based on data of measuring ventilation of 21 cleaning faces, an analysis was made of the change in gas release in time. During the days of work and interruption in work, the gas output is practically the same. Based on analysis of the weekly rhythm of gas release, one can determine the order for danger in individual days of the week. The gas output essentially is independent of the day of the week. Collapse of the roof causes a spasmodic increase in gas output. Frequency of collapse is in a close relationship to the average rate of advance of the cleaning face. With an increase in the rate of advance of the face, one can decrease the average specific output of gas.

  6. Valuing the greenhouse gas emissions from nuclear power: A critical survey

    Energy Technology Data Exchange (ETDEWEB)

    Sovacool, Benjamin K. [Energy Governance Program, Centre on Asia and Globalisation, Lee Kuan Yew School of Public Policy, National University of Singapore, 469C Bukit Timah Road, Singapore 259772 (Singapore)], E-mail: bsovacool@nus.edu.sg

    2008-08-15

    This article screens 103 lifecycle studies of greenhouse gas-equivalent emissions for nuclear power plants to identify a subset of the most current, original, and transparent studies. It begins by briefly detailing the separate components of the nuclear fuel cycle before explaining the methodology of the survey and exploring the variance of lifecycle estimates. It calculates that while the range of emissions for nuclear energy over the lifetime of a plant, reported from qualified studies examined, is from 1.4 g of carbon dioxide equivalent per kWh (g CO{sub 2}e/kWh) to 288 g CO{sub 2}e/kWh, the mean value is 66 g CO{sub 2}e/kWh. The article then explains some of the factors responsible for the disparity in lifecycle estimates, in particular identifying errors in both the lowest estimates (not comprehensive) and the highest estimates (failure to consider co-products). It should be noted that nuclear power is not directly emitting greenhouse gas emissions, but rather that lifecycle emissions occur through plant construction, operation, uranium mining and milling, and plant decommissioning.

  7. Impact of compression on gas transport in non-woven gas diffusion layers of high temperature polymer electrolyte fuel cells

    Science.gov (United States)

    Froning, Dieter; Yu, Junliang; Gaiselmann, Gerd; Reimer, Uwe; Manke, Ingo; Schmidt, Volker; Lehnert, Werner

    2016-06-01

    Gas transport in non-woven gas diffusion layers of a high-temperature polymer electrolyte fuel cell was calculated with the Lattice Boltzmann method. The underlying micro structure was taken from two sources. A real micro structure was analyzed in the synchrotron under the impact of a compression mask mimicking the channel/rib structure of a flow field. Furthermore a stochastic geometry model based on synchrotron X-ray tomography studies was applied. The effect of compression is included in the stochastic model. Gas transport in these micro structures was simulated and the impact of compression was analyzed. Fiber bundles overlaying the micro structure were identified which affect the homogeneity of the gas flow. There are significant deviations between the impact of compression on effective material properties for this type of gas diffusion layers and the Kozeny-Carman equation.

  8. High-Temperature Gas Sensor Array (Electronic Nose) Demonstrated

    Science.gov (United States)

    Hunter, Gary W.

    2002-01-01

    The ability to measure emissions from aeronautic engines and in commercial applications such as automotive emission control and chemical process monitoring is a necessary first step if one is going to actively control those emissions. One single sensor will not give all the information necessary to determine the chemical composition of a high-temperature, harsh environment. Rather, an array of gas sensor arrays--in effect, a high-temperature electronic "nose"--is necessary to characterize the chemical constituents of a diverse, high-temperature environment, such as an emissions stream. The signals produced by this nose could be analyzed to determine the constituents of the emission stream. Although commercial electronic noses for near-room temperature applications exist, they often depend significantly on lower temperature materials or only one sensor type. A separate development effort necessary for a high-temperature electronic nose is being undertaken by the NASA Glenn Research Center, Case Western Reserve University, Ohio State University, and Makel Engineering, Inc. The sensors are specially designed for hightemperature environments. A first-generation high-temperature electronic nose has been demonstrated on a modified automotive engine. This nose sensor array was composed of sensors designed for hightemperature environments fabricated using microelectromechanical-systems- (MEMS-) based technology. The array included a tin-oxide-based sensor doped for nitrogen oxide (NOx) sensitivity, a SiC-based hydrocarbon (CxHy) sensor, and an oxygen sensor (O2). These sensors operate on different principles--resistor, diode, and electrochemical cell, respectively--and each sensor has very different responses to the individual gases in the environment. A picture showing the sensor head for the array is shown in the photograph on the left and the sensors installed in the engine are shown in the photograph on the right. Electronics are interfaced with the sensors for

  9. High-velocity gas associated ultracompact HII regions

    Institute of Scientific and Technical Information of China (English)

    XU; Ye(徐烨); JIANG; Dongrong(蒋栋荣); YANG; Chuanyi(杨传义); ZHENG; Xingwu(郑兴武); GU; Minfeng(顾敏峰); PEI; Chunchuan(裴春传)

    2002-01-01

    We present the results of a survey for high-velocity 12CO (1-0) emission associated H2O masers and ultracompact (UC) HII regions. The aim is to investigate the relationship between H2O masers, CO high-velocity gas (HVG) and their associated infrared sources. Our sample satisfies Wood & Churchwell criterion. Almost 70 % of the sources have full widths (FWs) greater than 15 km@ s?1 at T*a = 100 mK and 15 % have FWs greater than 30 km@ s?1. In most of our objects there is excess high velocity emission in the beam. There is a clear correlation between CO line FWs and far-infrared luminosities: the FW increases with the FIR luminosity. The relation suggests that more luminous sources are likely to be more energetic and able to inject more energy into their surroundings. As a result, larger FW of the CO line could be produced. In most of our sources, the velocities of peak of the H2O emission are in agreement with those of the CO cloud, but a number of them have a large blueshift with respect to the CO peak. These masers might stem from the amplifications of a background source, which may amplify some unobservable weak masers to an observable level.

  10. A method for critical software event execution reliability in high assurance systems

    Energy Technology Data Exchange (ETDEWEB)

    Kidd, M.E.C.

    1997-03-01

    This paper presents a method for Critical Software Event Execution Reliability (Critical SEER). The Critical SEER method is intended for high assurance software that operates in an environment where transient upsets could occur, causing a disturbance of the critical software event execution order, which could cause safety or security hazards. The method has a finite automata based module that watches (hence SEER) and tracks the critical events and ensures they occur in the proper order or else a fail safe state is forced. This method is applied during the analysis, design and implementation phases of software engineering.

  11. High temperature heat exchanger studies for applications to gas turbines

    Science.gov (United States)

    Min, June Kee; Jeong, Ji Hwan; Ha, Man Yeong; Kim, Kui Soon

    2009-12-01

    Growing demand for environmentally friendly aero gas-turbine engines with lower emissions and improved specific fuel consumption can be met by incorporating heat exchangers into gas turbines. Relevant researches in such areas as the design of a heat exchanger matrix, materials selection, manufacturing technology, and optimization by a variety of researchers have been reviewed in this paper. Based on results reported in previous studies, potential heat exchanger designs for an aero gas turbine recuperator, intercooler, and cooling-air cooler are suggested.

  12. Development and application of an efficient gas extraction model for low-rank high-gas coal beds

    Institute of Scientific and Technical Information of China (English)

    Baiquan Lin; He Li; Desheng Yuan; Ziwen Li

    2015-01-01

    To promote gas extraction in low-rank high-gas coal beds, the pore structure characteristics of the coal and their effect on gas desorption were studied. The results show that micropores are relatively rare in low-rank coal;mesopores are usually semi-open and inkpot-shaped whereas macropores are usually slit-shaped. Gas desorption is relatively easy at high-pressure stages, whereas it is difficult at low-pressure stages because of the‘bottleneck effect’ of the semi-open inkpot-shaped mesopores. A ‘two-three-two’ gas extraction model was established following experimental analysis and engi-neering practice applied in the Binchang mining area. In this model, gas extraction is divided into three periods:a planning period, a transitional period and a production period. In each period, surface extraction and underground extraction are performed simultaneously, and pressure-relief extraction and conventional extraction are coupled to each other. After applying this model, the gas extraction rate rose to 78.8%.

  13. Novel silica membranes for high temperature gas separations

    KAUST Repository

    Bighane, Neha

    2011-04-01

    This article describes fabrication of novel silica membranes derived via controlled oxidative thermolysis of polydimethylsiloxane and their gas separation performance. The optimized protocol for fabrication of the silica membranes is described and pure gas separation performance in the temperature range 35-80°C is presented. It is observed that the membranes exhibit activated transport for small gas penetrants such as He, H 2 and CO 2. The membranes can withstand temperatures up to 350°C in air and may ultimately find use in H 2/CO 2 separations to improve efficiency in the water-gas shift reactor process. © 2011 Elsevier B.V.

  14. Oscillations of a highly discrete breather with a critical regime

    Science.gov (United States)

    Coquet; Remoissenet; Dinda

    2000-10-01

    We analyze carefully the essential features of the dynamics of a stationary discrete breather in the ultimate degree of energy localization in a nonlinear Klein-Gordon lattice with an on-site double-well potential. We demonstrate the existence of three different regimes of oscillatory motion in the breather dynamics, which are closely related to the motion of the central particle in an effective potential having two nondegenerate wells. In given parameter regions, we observe an untrapped regime, in which the central particle executes large-amplitude oscillations from one to the other side of the potential barrier. In other parameter regions, we find the trapped regime, in which the central particle oscillates in one of the two wells of the effective potential. Between these two regimes we find a critical regime in which the central particle undergoes several temporary trappings within an untrapped regime. Importantly, our study reveals that in the presence of purely anharmonic coupling forces, the breather compactifies, i.e., the energy becomes abruptly localized within the breather.

  15. Numerical analyses of high Reynolds number flow of high pressure fuel gas through rough pipes

    Energy Technology Data Exchange (ETDEWEB)

    Cadorin, Margherita; Morini, Mirko; Pinelli, Michele [ENDIF - Engineering Department in Ferrara, University of Ferrara, Via Saragat, 1 - 44122 Ferrara (Italy)

    2010-07-15

    In this paper, a CFD commercial code is used to evaluate the pressure drop through pipes in a stream of high pressure gas. Both hexahedral and tetrahedral grids are considered. Preliminarily, a grid sensitivity analysis is carried out by comparing CFD results with analytical results. Each grid is characterized by a different number and thickness of layers in order to investigate the behavior of the grid with respect to the boundary layer. Then, the model is validated by using a literature test case, in which high pressure gas flow through a rough pipe is experimentally studied. Moreover, various equations of state (i.e., constant properties, Ideal Gas and Redlich-Kwong equations) and boundary conditions (e.g., pressure, mass flow, etc.) are taken into consideration and compared. Finally, the model is used to extrapolate the behavior of gaseous fuels (i.e., natural gas, biogas and hydrogen-methane mixture) flowing at high pressure through pipes of different roughness. The analyses show that the radial depth of the prism layers on pipe wall has to be controlled to allow the correct resolution of the boundary layer. Moreover, the results highlight that the first element height of the prism layer should be high enough to avoid inconsistencies in the rough model application. At the same time, the grid used for calculations does not strongly influence the numerical results and hence tune of the first element height to perfectly fit the roughness is not always justified. The final analysis on the different gaseous fuels put into evidence the capability of the CFD analysis to determine the energy performance of fuel transportation in gas pipeline. (author)

  16. Trapping of xenon gas in closed inner spaces of carbon nanomaterials for stable gas storage under high-vacuum condition

    Science.gov (United States)

    Kobayashi, Keita; Yasuda, Hidehiro

    2017-01-01

    Xe gas can be trapped in the closed inner spaces of glassy carbon derived from C60 fullerene by thermal coalescence of C60 in Xe atmosphere and in cap-opened carbon nanotubes (CNTs) covered with an ionic liquid by soaking Xe-adsorbing CNTs in an ionic liquid. The trapped Xe gas is detected by energy dispersive X-ray spectrometry using a spectrometer mounted on an analytical transmission electron microscope. The closed inner spaces store gas molecules even under high-vacuum condition (˜10-5 Pa).

  17. New progresses in safe, clean and efficient development technologies for high-sulfur gas reservoirs

    Directory of Open Access Journals (Sweden)

    Liming Huang

    2015-10-01

    Full Text Available In China, there are a lot of high-sulfur gas reservoirs with total proved reserves of over 1 trillion m3, most of which were discovered in the Sichuan Basin. Most high-sulfur gas reservoirs in China, distributed in marine carbonate zones, are characterized by great buried depths, complex geologic conditions, high temperatures, high pressures, high H2S and CO2 content, presenting various challenges in gas field development engineering and production safety. Since the development of Sinian high-sulfur gas reservoirs in the Weiyuan area of the Sichuan Basin started in the 1960s, Wolonghe, Zhongba and other medium to small-scale gas reservoirs with medium to low sulfur content have been developed. Ever since 2009, successful production of Longgang and Puguang in the Sichuan Basin, together with some other high-sulfur gas reservoirs highlighted the breakthroughs in development technologies for high-sulfur gas reservoirs in China. This paper reviews the progress made in gas reservoir engineering, drilling and completion engineering, gas production, pipeline transportation, corrosion control, natural gas purification, HSE and other aspects with consideration of specific requirements related to safe, clean and high-efficient development of high-sulfur gas reservoirs since the “12th Five-Year Plan” period. Finally, considering the challenges in the development of high-sulfur gas reservoirs in China, we summarized the trend in future technological development with the following goals of reducing risks, minimizing environmental damages, and enhancing the efficiency of high-sulfur gas reservoir development.

  18. Planet Traps and First Planets: the Critical Metallicity for Gas Giant Formation

    CERN Document Server

    Hasegawa, Yasuhiro

    2014-01-01

    The ubiquity of planets poses an interesting question: when first planets are formed in galaxies. We investigate this problem by adopting a theoretical model developed for understanding the statistical properties of exoplanets. Our model is constructed as the combination of planet traps with the standard core accretion scenario in which the efficiency of forming planetary cores directly relates to the dust density in disks or the metallicity ([Fe/H]). We statistically compute planet formation frequencies (PFFs) as well as the orbital radius ($$) within which gas accretion becomes efficient enough to form Jovian planets. The three characteristic exoplanetary populations are considered: hot Jupiters, exo-Jupiters densely populated around 1 AU, and low-mass planets such as super-Earths. We explore the behavior of the PFFs as well as $$ for the three different populations as a function of metallicity ($-2 \\leq$[Fe/H]$\\leq -0.6$). We show that the total PFFs increase steadily with metallicity, which is the direct ...

  19. Inclusive STEM High School Design: 10 Critical Components

    Science.gov (United States)

    Peters-Burton, Erin E.; Lynch, Sharon J.; Behrend, Tara S.; Means, Barbara B.

    2014-01-01

    Historically, the mission of science, technology, engineering, and mathematics (STEM) schools emphasized providing gifted and talented students with advanced STEM coursework. However, a newer type of STEM school is emerging in the United States: inclusive STEM high schools (ISHSs). ISHSs have open enrollment and are focused on preparing…

  20. Comparative study of high voltage bushing designs suitable for apparatus containing cryogenic helium gas

    Science.gov (United States)

    Rodrigo, H.; Graber, L.; Kwag, D. S.; Crook, D. G.; Trociewitz, B.

    2013-10-01

    The high voltage bushing forms a critical part of any termination on cables, transformers and other power system devices. Cryogenic entities such as superconducting cables or fault current limiters add more complexity to the design of the bushing. Even more complex are bushings designed for superconducting devices which are cooled by high pressure helium gas. When looking for a bushing suitable for dielectric cable tests in a helium gas cryostat no appropriate device could be found that fulfilled the criterion regarding partial discharge inception voltage level. Therefore we decided to design and manufacture a bushing in-house. In the present work we describe the dielectric tests and operational experience on three types of bushings: One was a modified commercially available ceramics feed through which we adopted for our special need. The second bushing was made of an epoxy resin, with an embedded copper squirrel cage arrangement at the flange, extending down about 30 cm into the cold end of the bushing. This feature reduced the electric field on the surface of the bushing to a negligible value. The third bushing was based on a hollow body consisting of glass fiber reinforced polymer and stainless steel filled with liquid nitrogen. The measurements showed that the dielectric quality of all three bushings exceeded the requirements for the intended purpose. The partial discharge (PD) data from these studies will be used for the design and fabrication of a cable termination for a specialized application on board a US Navy ship.

  1. Corrosion of high temperature alloys in the coolant helium of a gas cooled reactor

    Energy Technology Data Exchange (ETDEWEB)

    Cabet, C.; Terlain, A. [Service de la Corrosion et du Comportement des Materiaux dans leur Environnement, DEN/DPC - CEA/Saclay, Gif sur Yvette (France); Monnier, A. [Lab. de Genie Electrique de Paris, Plateau du Moulon, Gif sur Yvette (France)

    2004-07-01

    The corrosion of structural alloys in gas cooled reactor environment appears to be a critical issue. The coolant helium proved to contain impurities mainly H{sub 2}, H{sub 2}O, CO, and CH{sub 4} in the microbar range that interact with metallic materials at high temperature. Surface scale formation, bulk carburisation and/or decarburisation can occur, depending on the gas chemistry, the alloy composition and the temperature. These structural transformations can notably influence the component mechanical properties. A short review of the literature on the topic is first given. Corrosion tests with high chromium alloys and a Mo-based alloy were carried out at 750 C in a purposely-designed facility under simulated GCR helium. The first, rather short term, results showed that the Mo-based alloy was inert while the others alloys oxidised during at least 900 hours. The alloy with the higher Al and Ti contents exhibited poor oxidation resistance impeding its use as structural material without further investigations. (orig.)

  2. Experimental study of water effects on gas desorption during high-pressure water injection

    Institute of Scientific and Technical Information of China (English)

    ZHANG Guo-hua; LIU Xian-xin; BI Ye-wu; PU Wen-long

    2011-01-01

    For the question of applying high-pressure water injection to increase gas extraction efficiency by increasing the permeability of water to drive gas action,an independently designed gas desorption experimental measuring device was used under the condition of external solution invasion.The law of water effect on gas desorption was obtained after water invasion through experiment for the first time.The results show that water's later invasion not only can make the quantity of gas desorption greatly reduced,but also can make gas desorption end early.Therefore,when evaluating the applications of high-pressure water injection to increase gas extraction efficiency,we should take water damaging effects on gas desorption into account.

  3. High Upper Critical Field and Irreversibility Field in MgB2 Coated-Conductor Fibers

    Science.gov (United States)

    2016-06-13

    High upper critical field and irreversibility field in MgB2 coated-conductor fibers V. Ferrando,a P. Orgiani,b A. V. Pogrebnyakov, J. Chen, Qi Li...show a high upper critical field of 55 T at 1.5 K and a high irreversibility field of 40 T at 1.5 K. The result demonstrates great potential of MgB2...using cryocoolers. Unlike high temperature superconductors where critical current den- sity Jc drops sharply across the grain boundary when the grains

  4. A Critical Review of the Impacts of Leaking CO2 Gas and Brine on Groundwater Quality

    Energy Technology Data Exchange (ETDEWEB)

    Qafoku, Nikolla [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Zheng, Liange [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Bacon, Diana H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lawter, Amanda R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Brown, Christopher F. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-09-30

    Geological carbon sequestration (GCS) is a global carbon emission reduction strategy involving the capture of CO2 emitted from fossil fuel burning power plants, as well as the subsequent injection of the captured CO2 gas into deep saline aquifers or depleted oil and gas reservoirs. A critical question that arises from the proposed GCS is the potential impacts of CO2 injection on the quality of drinking-water systems overlying CO2 sequestration storage sites. Although storage reservoirs are evaluated and selected based on their ability to safely and securely store emplaced fluids, leakage of CO2 from storage reservoirs is a primary risk factor and potential barrier to the widespread acceptance of geologic CO2 sequestration (OR Harvey et al. 2013; Y-S Jun et al. 2013; DOE 2007). Therefore, a systematic understanding of how CO2 leakage would affect the geochemistry of potable aquifers, and subsequently control or affect elemental and contaminant release via sequential and/or simultaneous abiotic and biotic processes and reactions is vital.

  5. A critical study of high efficiency deep grinding

    CERN Document Server

    Johnstone, I

    2002-01-01

    The recent years, the aerospace industry in particular has embraced and actively pursued the development of stronger high performance materials, namely nickel based superalloys and hardwearing steels. This has resulted in a need for a more efficient method of machining, and this need was answered with the advent of High Efficiency Deep Grinding (HEDG). This relatively new process using Cubic Boron Nitride (CBN) electroplated grinding wheels has been investigated through experimental and theoretical means applied to two widely used materials, M50 bearing steel and IN718 nickel based superalloy. It has been shown that this grinding method using a stiff grinding centre such as the Edgetek 5-axis machine is a viable process. Using a number of experimental designs, produced results which were analysed using a variety of methods including visual assessment, sub-surface microscopy and surface analysis using a Scanning Electron Microscope (SEM), residual stress measurement using X-Ray Diffraction (XRD) techniques, Ba...

  6. A Critical Analysis and Assessment of High Power Switches

    Science.gov (United States)

    1978-09-01

    Spark Gap Switch Assembly ........ .225 vii List of Figures (cont.) FIGURE PAGE IV-10. Turbulent Flow Switch .... ............ . 227 IV-II. Spark Gap...provide such a low inductance that the current risetime is limited by the load rather than the switch itself. Many spark gaps with liquid or solid...Sympoisum, June, 1978. [4] M. A. Lutz and G. A. Hofmann, "The Gamitron - A High Power Crossed-Field Switch Tube for HVDC Interruption," IEEE Trans. on Plasma

  7. High temperature superconductivity the road to higher critical temperature

    CERN Document Server

    Uchida, Shin-ichi

    2015-01-01

    This book presents an overview of material-specific factors that influence Tc and give rise to diverse Tc values for copper oxides and iron-based high- Tc superconductors on the basis of more than 25 years of experimental data, to most of which the author has made important contributions. The book then explains why both compounds are distinct from others with similar crystal structure and whether or not one can enhance Tc, which in turn gives a hint on the unresolved pairing mechanism. This is an unprecedented new approach to the problem of high-temperature superconductivity and thus will be inspiring to both specialists and non-specialists interested in this field.   Readers will receive in-depth information on the past, present, and future of high-temperature superconductors, along with special, updated information on what the real highest Tc values are and particularly on the possibility of enhancing Tc for each member material, which is important for application. At this time, the highest Tc has not been...

  8. A thermo-acoustic gas sensor array for photochemically critical species in the martian atmosphere

    Science.gov (United States)

    Zent, Aaron P.; Quinn, Richard C.; Madou, Marc

    1998-02-01

    We describe the development of a thermoacoustic oxidant sensor (TAOS) array to quantify gases that play critical roles in the chemical evolution of the martian surface and atmosphere. The sensor combines a chemiresistor with an acoustic wave-plate device, micro-fabricated on thermally isolated hot-plates; their measurement modes are respectively: conductivity changes of chemically sensitive films, and mass changes of the same coatings. Metal Phthalocyanines (MePcs) and other organic semiconductors such as 1,4-polybutadiene are used as chemical coatings because of their chemical stability and the fact that these compounds have been shown to exhibit selectivity to oxidizing gases. The specific target gases of this experiment are H 2O 2, H 2O, O 3 and CO. Identification and quantification of these gases at the martian surface would contribute to both atmospheric and soil chemistry studies. The species H 2O 2 and/or O 3, may be responsible for the unique reactive properties of the martian regolith, as discovered in the Viking biology experiments. In addition, each of the target gases are believed to play a role in the photochemical recycling of CO 2.

  9. Experimental Research On Gas Injection High Temperature Heat Pump With An Economizer

    OpenAIRE

    He, Yongning; Lei JIN; Cao, Feng; Chen, Shengkun

    2014-01-01

    Gas injection technology is often used in cold regions to solve heat pump’s low heating capacity and high discharge temperature at low ambient temperature. Injecting gas into port opened at specific position of compressor could increase mass flow rate of compressor and total heating capacity of heat pump. Gas injection also changes compression ratio of compressor and decreases discharge temperature. An optimal gas injection pressure is got when the coefficient of performance reached to peak v...

  10. A High Efficiency PSOFC/ATS-Gas Turbine Power System

    Energy Technology Data Exchange (ETDEWEB)

    W.L. Lundberg; G.A. Israelson; M.D. Moeckel; S.E. Veyo; R.A. Holmes; P.R. Zafred; J.E. King; R.E. Kothmann

    2001-02-01

    A study is described in which the conceptual design of a hybrid power system integrating a pressurized Siemens Westinghouse solid oxide fuel cell generator and the Mercury{trademark} 50 gas turbine was developed. The Mercury{trademark} 50 was designed by Solar Turbines as part of the US. Department of Energy Advanced Turbine Systems program. The focus of the study was to develop the hybrid power system concept that principally would exhibit an attractively-low cost of electricity (COE). The inherently-high efficiency of the hybrid cycle contributes directly to achieving this objective, and by employing the efficient, power-intensive Mercury{trademark} 50, with its relatively-low installed cost, the higher-cost SOFC generator can be optimally sized such that the minimum-COE objective is achieved. The system cycle is described, major system components are specified, the system installed cost and COE are estimated, and the physical arrangement of the major system components is discussed. Estimates of system power output, efficiency, and emissions at the system design point are also presented. In addition, two bottoming cycle options are described, and estimates of their effects on overall-system performance, cost, and COE are provided.

  11. MELCOR Model Development of High Temperature Gas-cooled Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Changyong; Huh, Changwook [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2013-05-15

    The High Temperature Gas-cooled Reactor is one of the major challenging issues on the development of licensing technology for HTGR. The safety evaluation tools of HTGR can be developed in two ways - development of new HTGR-specific codes or revision of existing codes. The KINS is considering using existing analytic tools to the extent feasible, with appropriate modifications for the intended purpose. The system-level MELCOR code is traditionally used for LWR safety analysis, which is capable of performing thermal-fluid and accident analysis, including fission-product transport and release. Recently, this code is being modified for the NGNP HTGR by the NRC. In this study, the MELCOR input model for HTGR with Reactor Cavity Cooling System (RCCS) was developed and the steady state performance was analyzed to evaluate the applicability in HTGR. HTGR model with design characteristics of GT-MHR was developed using MELCOR 2.1 code to validate the applicability of MELCOR code to HTGR. In addition, the steady state of GT-MHR was analyzed with the developed model. It was evaluated to predict well the design parameters of GT-MHR. The developed model can be used as the basis for accident analysis of HTGR with further update of packages such as Radio Nuclide (RN) package.

  12. Multiphysics methods development for high temperature gas reactor analysis

    Science.gov (United States)

    Seker, Volkan

    Multiphysics computational methods were developed to perform design and safety analysis of the next generation Pebble Bed High Temperature Gas Cooled Reactors. A suite of code modules was developed to solve the coupled thermal-hydraulics and neutronics field equations. The thermal-hydraulics module is based on the three dimensional solution of the mass, momentum and energy equations in cylindrical coordinates within the framework of the porous media method. The neutronics module is a part of the PARCS (Purdue Advanced Reactor Core Simulator) code and provides a fine mesh finite difference solution of the neutron diffusion equation in three dimensional cylindrical coordinates. Coupling of the two modules was performed by mapping the solution variables from one module to the other. Mapping is performed automatically in the code system by the use of a common material mesh in both modules. The standalone validation of the thermal-hydraulics module was performed with several cases of the SANA experiment and the standalone thermal-hydraulics exercise of the PBMR-400 benchmark problem. The standalone neutronics module was validated by performing the relevant exercises of the PBMR-268 and PBMR-400 benchmark problems. Additionally, the validation of the coupled code system was performed by analyzing several steady state and transient cases of the OECD/NEA PBMR-400 benchmark problem.

  13. Criticality Safety Evaluation of Hanford Site High Level Waste Storage Tanks

    Energy Technology Data Exchange (ETDEWEB)

    ROGERS, C.A.

    2000-02-17

    This criticality safety evaluation covers operations for waste in underground storage tanks at the high-level waste tank farms on the Hanford site. This evaluation provides the bases for criticality safety limits and controls to govern receipt, transfer, and long-term storage of tank waste. Justification is provided that a nuclear criticality accident cannot occur for tank farms operations, based on current fissile material and operating conditions.

  14. 中等胶结储层气井出砂临界流量实验测试技术%The Sand Production Critical Flow Test Technology of Gas Well in Moderate Cemented Formation

    Institute of Scientific and Technical Information of China (English)

    邓金根; 王利华; 李萍; 曹砚锋; 冯永存

    2011-01-01

    Sand production is of great harm to the moderate cemented formation in gas reservoir, so it is necessary to determine the sand production critical flow. In order to overcome the shortcomings in traditional sand production critical flow determining methods, such as high cost of field test and low computational accuracy of theoretical calculation, this paper shows that test equipments and test methods determine the sand production critical flow for gas well. The lab simulation test for determining the sand production critical flow in open hole completion is carried out. We measure the gas flow rate and sand production rate under different drawdown pressure. Finally, the sand production critical flow of gas well was determined. The test technology for determining the sand production critical flow of gas well is based on the critical flow rate back stepping strata of back-derive critical sand production drawdown pressure and productivity. This test method has been successfully used in a gas field of South China Sea. The result shows the advancement and reliability of this test method.%中等胶结砂岩气藏储层出砂危害极大,气井的出砂临界流量确定尤为重要.克服了以往确定出砂临界流量的现场试验方法成本高及理论计算精度低等不足,研制了测定气井出砂临界流量的实验装置并制定了测定气井出砂临界流量的实验方法.进行了裸眼完井条件下的室内气井出砂临界流量模拟实验,测定了不同生产压差下的气体流量及出砂量,确定了气井出砂临界流量.并利用临界流量反推地层条件下的出砂临界生产压差及产能,形成中等胶结储层气井出砂临界流量的实验测试技术,在南海某气田进行了成功应用.结果表明:该实验测试技术具有先进性和可靠性.

  15. Deadtime calibration in high-rate microstrip gas counters

    Energy Technology Data Exchange (ETDEWEB)

    Bateman, J.E. [Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX (United Kingdom); Duxbury, D.M., E-mail: dom.duxbury@stfc.ac.u [Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX (United Kingdom)

    2010-09-21

    The advent of the microstrip gas chamber (MSGC) has permitted the development of position-sensitive gas avalanche detectors, which combine sub-millimeter spatial resolution with multi-MHz global rate capabilities not attainable with traditional types of gas counters. Based on massively parallel electronic readout, the need to keep down electronic channel costs imposes a simple front-end design without in-built deadtime compensation. In this report we show that insitu calibration of the deadtime of the detector system is straight-forward and reliable. Methods are described for applications to X-ray and neutron detection.

  16. Critical Test of Some Computational Chemistry Methods for Prediction of Gas-Phase Acidities and Basicities.

    Science.gov (United States)

    Toomsalu, Eve; Koppel, Ilmar A; Burk, Peeter

    2013-09-10

    Gas-phase acidities and basicities were calculated for 64 neutral bases (covering the scale from 139.9 kcal/mol to 251.9 kcal/mol) and 53 neutral acids (covering the scale from 299.5 kcal/mol to 411.7 kcal/mol). The following methods were used: AM1, PM3, PM6, PDDG, G2, G2MP2, G3, G3MP2, G4, G4MP2, CBS-QB3, B1B95, B2PLYP, B2PLYPD, B3LYP, B3PW91, B97D, B98, BLYP, BMK, BP86, CAM-B3LYP, HSEh1PBE, M06, M062X, M06HF, M06L, mPW2PLYP, mPW2PLYPD, O3LYP, OLYP, PBE1PBE, PBEPBE, tHCTHhyb, TPSSh, VSXC, X3LYP. The addition of the Grimmes empirical dispersion correction (D) to B2PLYP and mPW2PLYP was evaluated, and it was found that adding this correction gave more-accurate results when considering acidities. Calculations with B3LYP, B97D, BLYP, B2PLYPD, and PBE1PBE methods were carried out with five basis sets (6-311G**, 6-311+G**, TZVP, cc-pVTZ, and aug-cc-pVTZ) to evaluate the effect of basis sets on the accuracy of calculations. It was found that the best basis sets when considering accuracy of results and needed time were 6-311+G** and TZVP. Among semiempirical methods AM1 had the best ability to reproduce experimental acidities and basicities (the mean absolute error (mae) was 7.3 kcal/mol). Among DFT methods the best method considering accuracy, robustness, and computation time was PBE1PBE/6-311+G** (mae = 2.7 kcal/mol). Four Gaussian-type methods (G2, G2MP2, G4, and G4MP2) gave similar results to each other (mae = 2.3 kcal/mol). Gaussian-type methods are quite accurate, but their downside is the relatively long computational time.

  17. Linear processes in high dimensions: Phase space and critical properties

    Science.gov (United States)

    Mastromatteo, Iacopo; Bacry, Emmanuel; Muzy, Jean-François

    2015-04-01

    In this work we investigate the generic properties of a stochastic linear model in the regime of high dimensionality. We consider in particular the vector autoregressive (VAR) model and the multivariate Hawkes process. We analyze both deterministic and random versions of these models, showing the existence of a stable phase and an unstable phase. We find that along the transition region separating the two regimes the correlations of the process decay slowly, and we characterize the conditions under which these slow correlations are expected to become power laws. We check our findings with numerical simulations showing remarkable agreement with our predictions. We finally argue that real systems with a strong degree of self-interaction are naturally characterized by this type of slow relaxation of the correlations.

  18. Critical Assessment 14: High Entropy Alloys and Their Development as Structural Materials (Postprint)

    Science.gov (United States)

    2015-01-01

    AFRL-RX-WP-JA-2015-0219 CRITICAL ASSESSMENT 14: HIGH ENTROPY ALLOYS AND THEIR DEVELOPMENT AS STRUCTURAL MATERIALS (POSTPRINT) Daniel...December 2014 4. TITLE AND SUBTITLE CRITICAL ASSESSMENT 14: HIGH ENTROPY ALLOYS AND THEIR DEVELOPMENT AS STRUCTURAL MATERIALS (POSTPRINT) 5a...available at DOI 10.1179/1743284714Y.1142 0000000749. 14. ABSTRACT The field of high entropy alloys has exploded in its first 10 years. Vast

  19. High-Temperature Magnetic Bearings for Gas Turbine Engines

    Science.gov (United States)

    1996-01-01

    Magnetic bearings are the subject of a new NASA Lewis Research Center and U.S. Army thrust with significant industry participation, and coordination with other Government agencies. The NASA/Army emphasis is on high-temperature applications for future gas turbine engines. Magnetic bearings could increase the reliability and reduce the weight of these engines by eliminating the lubrication system. They could also increase the DN (diameter of the bearing times rpm) limit on engine speed and allow active vibration cancellation systems to be used--resulting in a more efficient, "more electric" engine. Finally, the Integrated High-Performance Turbine Engine Technology (IHPTET) Program, a joint Department of Defense/industry program, identified a need for a hightemperature (as high as 1200 F) magnetic bearing that could be demonstrated in a phase III engine. This magnetic bearing is similar to an electric motor. It has a laminated rotor and stator made of cobalt steel. Wound around the stator are a series of electrical wire coils that form a series of electric magnets around the circumference. The magnets exert a force on the rotor. A probe senses the position of the rotor, and a feedback controller keeps it in the center of the cavity. The engine rotor, bearings, and case form a flexible structure that contains a large number of modes. The bearing feedback controller, which could cause some of these modes to become unstable, could be adapted to varying flight conditions to minimize seal clearances and monitor the health of the system. Cobalt steel has a curie point greater than 1700 F, and copper wire has a melting point beyond that. Therefore, practical limitations associated with the maximum magnetic field strength in the cobalt steel and the stress in the rotating components limit the temperature to about 1200 F. The objective of this effort is to determine the limits in temperature and speed of a magnetic bearing operating in an engine. Our approach is to use our in

  20. Photonic Crystal Fiber-Based High Sensitivity Gas Sensor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Los Gatos Research, Inc. proposes to develop a lightweight, compact, rugged, near and mid-infrared gas-sensing spectroscopy instrument to accurately measure the...

  1. Photonic Crystal Fiber-Based High Sensitivity Gas Sensor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Los Gatos Research, Inc. proposes to develop a lightweight, compact, rugged, near-infrared gas-sensing spectroscopy instrument to accurately measure the abundance of...

  2. High critical current densities in industrial scale composites made from high homogeneity NB 46. 5 TI

    Energy Technology Data Exchange (ETDEWEB)

    Larbalestier, D.C.; Hemachalam, K.; Lee, P.; McDonald, W.K.; O' Larey, P.; Scanlan, R.; Starch, W.; Taylor, C.; Warnes, W.; West, A.W.; Zeitlin, B.

    1985-03-01

    Recent work in our group on the fabricationmicrostructure-superconducting properties of composites of Nb-Ti has produced much new information about the precipitate morphology and origins of high critical current density (J /SUB c/ ) in these materials./sup 1 -4/ Precipitation of Ti-rich phase is seen to commence as a grain boundary film 2 - 4 nm thick, the film then developing into approximately equiaxed particles of ..cap alpha..-Ti at the boundary triple points. The typical size of such precipitates is 50 - 100 nm. Controlled drawing of such a structure produces an array of locally ordered ribbon precipitates. These precipitates are typically 3 - 5 nm thick by 100 - 300 nm long (when observed in transverse section). Their length in longitudinal section appears to be several hundred nm, indicating great ductility in these small ..cap alpha..-Ti precipitates. The typical separation of the precipitates is 20 - 30 nm. Thus the dimensions of the precipitate array are quite comparable to that of the flux lattice since the fluxoid separation is 22 nm at 5 T and the fluxoid diameter of Nb 46.5 wt% Ti is approximately 10 nm. The flux pinning behavior of these precipitate structures is expected to be complex: /SUP 2.4/ the defect density is very high, the precipitate morphology has a very high aspect ratio and the extreme thinness of the precipitates must permit some superconductivity to be induced in them by the proximity effect./sup 5/

  3. Modeling of neutral gas dynamics in high-density plasmas

    Science.gov (United States)

    Canupp, Patrick Wellington

    This thesis describes a physical model of chemically reactive neutral gas flow and discusses numerical solutions of this model for the flow in an inductively coupled plasma etch reactor. To obtain these solutions, this research develops an efficient, implicit numerical method. As a result of the enhanced numerical stability of the scheme, large time steps advance the solution from initial conditions to a final steady state in fewer iterations and with less computational expense than simpler explicit methods. This method would incorporate suitably as a module in currently existing large scale plasma simulation tools. In order to demonstrate the accuracy of the numerical technique, this thesis presents results from two simulations of flows that possess theoretical solutions. The first case is the inviscid flow of a gas through a converging nozzle. A comparison of the numerical solution to isentropic flow theory shows that the numerical technique capably captures the essential flow features of this environment. The second case is the Couette flow of a gas between two parallel plates. The simulation results compare well with the exact solution for this flow. After establishing the accuracy of the numerical technique, this thesis discusses results for the flow of chemically reactive gases in a chlorine plasma etch reactor. This research examines the influence of the plasma on the neutral gas and the dynamics exhibited by the neutral gas in the reactor. This research finds that the neutral gas temperature strongly depends on the rate at which inelastic, electron-impact dissociation reactions occur and on atomic chlorine wall recombination rates. Additionally, the neutral gas Aow in the reactor includes a significant mass flux of etch product from the wafer surface. Resolution of these effects is useful for neutral gas simulation. Finally, this thesis demonstrates that continuum fluid models provide reasonable accuracy for these low pressure reactor flows due to the fact

  4. A Critical Assessment of Recent Work on the Application of Gas/Particle Partitioning Theories to Cigarette Smoke

    Directory of Open Access Journals (Sweden)

    Lauterbach JH

    2014-12-01

    Full Text Available In the August 1997 issue of Environmental Science&Technology (ES&T, PANKOW and co-workers at the Oregon Graduate Institute reported that the addition of ammonia-containing additives to cigarette tobacco increased the amount of unprotonated nicotine in cigarette mainstream smoke (MSS and thus increased the bioavailability of nicotine to the smoker. Articles about PANKOW's work also appeared in other publications along with allegations that ammonia-containing additives are used to manipulate nicotine deliveries. However, initial review of PANKOW's research and that reported on environmental tobacco smoke (ETS in an earlier paper showed that potentially serious issues existed with PANKOW's experimental data and conclusions. Consequently, a critical assessment of PANKOW's research and the underlying theories of gas/particle partitioning was undertaken. This assessment confirmed that PANKOW and his co-workers made a number of errors not only in their determinations of the gas/particle partitioning coefficients for nicotine in MSS and ETS but also in the interpretations of the data. During the preparation of this assessment, data from other researchers became public. These data showed that there was no correlation between tobacco ammonia (including residual ammonia from the use of ammonia-containing additives and MSS ammonia deliveries and MSS smoke pH, and that the amount of unprotonated nicotine in the undiluted MSS of a full flavor (FF American filter cigarette was less than 0.1%. These new data fully substantiated the findings of this assessment, and it can be safely concluded that the assertions made by PANKOW and his co-workers were incorrect. However, this assessment also showed that there is significant merit in the application of PANKOW's theory of absorptive partitioning for the estimation of the gas/particle partitioning of semivolatile components in MSS and ETS. Application of PANKOW's theory along with data from recent tobacco related

  5. The Relationship between Critical Thinking Abilities and Classroom Management Skills of High School Teachers

    Science.gov (United States)

    Demirdag, Seyithan

    2015-01-01

    High school teachers experience difficulties while providing effective teaching approaches in their classrooms. Some of the difficulties are associated with the lack of classroom management skills and critical thinking abilities. This quantitative study includes non-random selection of the participants and aims to examine critical thinking…

  6. The Relationship between Critical Thinking Abilities and Classroom Management Skills of High School Teachers

    Science.gov (United States)

    Demirdag, Seyithan

    2015-01-01

    High school teachers experience difficulties while providing effective teaching approaches in their classrooms. Some of the difficulties are associated with the lack of classroom management skills and critical thinking abilities. This quantitative study includes non-random selection of the participants and aims to examine critical thinking…

  7. High pressure real gas effects for helium and nitrogen

    Science.gov (United States)

    Johnson, R. C.

    1969-01-01

    Critical flow factor is calculated that permits the isentropic mass-flow rate of the gases through critical flow nozzles to be calculated from plenum conditions. Results include nozzle throat velocity, compressibility factor, entropy, enthalpy, specific heat, and ratios of throat to plenum pressure, density, and temperature.

  8. Gas Electron Multiplier detectors with high reliability and stability

    CERN Document Server

    Ovchinnikov, B M; Ovchinnikov, Yu B

    2010-01-01

    The Gas Electron Multiplier detectors with wire and metallic electrodes, with a gas filling in the gap between them were proposed and tested. The main advantage of these Gas Electron Multipliers compared to standard ones consists in their increased stability and reliability. The experimental results on testing of such detectors with gaps between the electrodes of 1 and 3 mm are reported. It is demonstrated, that the best gas filling for the gas electron multipliers is neon with small admixture of quenching gases (for example, (N2+H2O) at ~100ppm). This filling offers the greatest coefficient of proportional multiplication as compared with other gases, at small electric potential difference between the GEM electrodes, in absence of streamer discharges in the proportional region. The results on operation of the multi-channel gas electron multiplier with wire cathode and continuous anode filled with Ne, Ar, Ar+CH4 and Ar+1%Xe are presented also. Based on the experimental observations, the explanation of the mech...

  9. Vortex-lattice pinning and critical current density in anisotropic high-temperature superconductors

    Science.gov (United States)

    Li, Yingxu; Li, Xiangyu; Kang, Guozheng; Gao, Yuanwen

    2016-10-01

    The anisotropy of critical current density is an impressive manifestation in the physics of high-temperature superconductors. We develop an analytical characterization of anisotropic flux-lattice pinning and critical current density in a system of random point defects. The effect of superconducting anisotropy on the pinning force and critical current density is formulated. The in-plane/out-of-plane anisotropy and microscopic characteristic lengths are incorporated in the field and angular dependence of the critical current density. This is helpful in understanding the physical essence of the scaling behavior in the experiments for critical current anisotropy. We discuss the role of strong and weak point defects in the anisotropic flux-lattice pinning. Relevance of the theory to the critical-state model is dictated as well.

  10. The viscosity and density of sour gas fluids at high temperatures and high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Giri, B.R.; Marriott, R.A.; Blais, P.; Clark, P.D. [Alberta Sulphur Research Ltd., Calgary, AB (Canada); Calgary Univ., AB (Canada). Dept. of Chemistry

    2010-01-15

    This poster session discussed an experiment designed to measure the viscosity and density of sour gas fluids at high temperatures and pressures. An option for disposing acid gases while enhancing the production of oil and gas fields is the re-injection of gases rich in hydrogen sulphide/carbon dioxide (H{sub 2}S/CO{sub 2}) into reservoirs up to very high pressures, but issues with respect to corrosion, compression, pumping, and transport need addressing, and the reliable high-density/high-pressure data needed to arrive at an optimum process concept and the design of pumps, compressors, and transport lines had up to this point been lacking. The experimental set up involved the use of a Vibrating Tube Densimeter and a Cambridge Viscometer. Working with toxic gases at very high pressures and obtaining highly accurate data in a wide range of conditions were two of the challenges faced during the experiment. The experiment resulted in physical property measurement systems being recalibrated and a new daily calibration routine being adopted for accuracy. The densities and viscosities of pure CO{sub 2} and sulphur dioxide (SO{sub 2}) in a wide pressure and temperature range were determined. 1 tab., 9 figs.

  11. Ultra Clean 1.1MW High Efficiency Natural Gas Engine Powered System

    Energy Technology Data Exchange (ETDEWEB)

    Zurlo, James; Lueck, Steve

    2011-08-31

    Dresser, Inc. (GE Energy, Waukesha gas engines) will develop, test, demonstrate, and commercialize a 1.1 Megawatt (MW) natural gas fueled combined heat and power reciprocating engine powered package. This package will feature a total efficiency > 75% and ultra low CARB permitting emissions. Our modular design will cover the 1 – 6 MW size range, and this scalable technology can be used in both smaller and larger engine powered CHP packages. To further advance one of the key advantages of reciprocating engines, the engine, generator and CHP package will be optimized for low initial and operating costs. Dresser, Inc. will leverage the knowledge gained in the DOE - ARES program. Dresser, Inc. will work with commercial, regulatory, and government entities to help break down barriers to wider deployment of CHP. The outcome of this project will be a commercially successful 1.1 MW CHP package with high electrical and total efficiency that will significantly reduce emissions compared to the current central power plant paradigm. Principal objectives by phases for Budget Period 1 include: • Phase 1 – market study to determine optimum system performance, target first cost, lifecycle cost, and creation of a detailed product specification. • Phase 2 – Refinement of the Waukesha CHP system design concepts, identification of critical characteristics, initial evaluation of technical solutions, and risk mitigation plans. Background

  12. Proliferation resistance assessment of high temperature gas reactors

    Energy Technology Data Exchange (ETDEWEB)

    Chikamatsu N, M. A. [Instituto Tecnologico y de Estudios Superiores de Monterrey, Campus Santa Fe, Av. Carlos Lazo No. 100, Santa Fe, 01389 Mexico D. F. (Mexico); Puente E, F., E-mail: midori.chika@gmail.com [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2014-10-15

    The Generation IV International Forum has established different objectives for the new generation of reactors to accomplish. These objectives are focused on sustain ability, safety, economics and proliferation resistance. This paper is focused on how the proliferation resistance of the High Temperature Gas Reactors (HTGR) is assessed and the advantages that these reactors present currently. In this paper, the focus will be on explaining why such reactors, HTGR, can achieve the goals established by the GIF and can present a viable option in terms of proliferation resistance, which is an issue of great importance in the field of nuclear energy generation. The reason why the HTGR are being targeted in this writing is that these reactors are versatile, and present different options from modular reactors to reactors with the same size as the ones that are being operated today. Besides their versatility, the HTGR has designed features that might improve on the overall sustain ability of the nuclear reactors. This is because the type of safety features and materials that are used open up options for industrial processes to be carried out; cogeneration for instance. There is a small section that mentions how HTGR s are being developed in the international sector in order to present the current world view in this type of technology and the further developments that are being sought. For the proliferation resistance section, the focus is on both the intrinsic and the extrinsic features of the nuclear systems. The paper presents a comparison between the features of Light Water Reactors (LWR) and the HTGR in order to be able to properly compare the most used technology today and one that is gaining international interest. (Author)

  13. [Study on high accuracy detection of multi-component gas in oil-immerse power transformer].

    Science.gov (United States)

    Fan, Jie; Chen, Xiao; Huang, Qi-Feng; Zhou, Yu; Chen, Gang

    2013-12-01

    In order to solve the problem of low accuracy and mutual interference in multi-component gas detection, a kind of multi-component gas detection network with high accuracy was designed. A semiconductor laser with narrow bandwidth was utilized as light source and a novel long-path gas cell was also used in this system. By taking the single sine signal to modulate the spectrum of laser and using space division multiplexing (SDM) and time division multiplexing (TDM) technique, the detection of multi-component gas was achieved. The experiments indicate that the linearity relevance coefficient is 0. 99 and the measurement relative error is less than 4%. The system dynamic response time is less than 15 s, by filling a volume of multi-component gas into the gas cell gradually. The system has advantages of high accuracy and quick response, which can be used in the fault gas on-line monitoring for power transformers in real time.

  14. Sputter-ion plating of coatings for protection of gas-turbine blades against high-temperature oxidation and corrosion

    Science.gov (United States)

    Coad, J. P.; Restall, J. E.

    1982-01-01

    Considerable effort is being devoted to the development of overlay coatings for protecting critical components such as turbine blades against high-temperature oxidation, corrosion, and erosion damage in service. The most commercially advanced methods for depositing coatings are electron-beam evaporation and plasma spraying. Sputter-ion plating (SIP) offers a potentially cheaper and simpler alternative method for depositing overlays. Experimental work on SIP of Co-Cr-Al-Y and Ni-Cr-Al-Ti alloy coatings is described. Results are presented of metallographic assessment of these coatings, and of the results obtained from high-velocity testing using a gas-turbine simulator rig.

  15. Theoretical and experimental analysis of a multiphase screw pump, handling gas-liquid mixtures with very high gas volume fractions

    Energy Technology Data Exchange (ETDEWEB)

    Raebiger, K. [LEISTRITZ Pumpen GmbH, Nuremberg (Germany); Faculty of Advanced Technology, University of Glamorgan, Pontypridd, Wales (United Kingdom); Maksoud, T.M.A.; Ward, J. [Faculty of Advanced Technology, University of Glamorgan, Pontypridd, Wales (United Kingdom); Hausmann, G. [Department of Mechanical Engineering and Building Services Engineering, University of Applied Sciences, Nuremberg (Germany)

    2008-09-15

    In the investigation of the pumping behaviour of multiphase screw pumps, handling gas-liquid mixtures with very high gas volume fractions, theoretical and experimental analyses were performed. A new theoretical screw pump model was developed, which calculates the time-dependent conditions inside the several chambers of a screw pump as well as the exchange of mass and energy between these chambers. By means of the performed experimental analysis, the screw pump model was verified, especially at very high gas volume fractions from 90% to 99%. The experiments, which were conducted with the reference fluids water and air, can be divided mainly into the determination of the steady state pumping behaviour on the one hand and into the analysis of selected transient operating conditions on the other hand, whereas the visualisation of the leakage flows through the circumferential gaps was rounded off the experimental analysis. (author)

  16. Optimization of the green gas supply chain. Identification of critical choices in designing an efficient (from an energetic and economic perspective) green gas supply chain.

    NARCIS (Netherlands)

    Grond, Lukas

    2010-01-01

    Summary Global climate change and the need for security of energy supply drive the development of bio-energy production and utilization. Green gas is defined as bio-based gas that has been upgraded to natural gas quality. Amongst other energy carriers, g

  17. Method for critical software event execution reliability in high integrity software

    Energy Technology Data Exchange (ETDEWEB)

    Kidd, M.E. [Sandia National Labs., Albuquerque, NM (United States)

    1997-11-01

    This report contains viewgraphs on a method called SEER, which provides a high level of confidence that critical software driven event execution sequences faithfully exceute in the face of transient computer architecture failures in both normal and abnormal operating environments.

  18. Computations of ideal and real gas high altitude plume flows

    Science.gov (United States)

    Feiereisen, William J.; Venkatapathy, Ethiraj

    1988-01-01

    In the present work, complete flow fields around generic space vehicles in supersonic and hypersonic flight regimes are studied numerically. Numerical simulation is performed with a flux-split, time asymptotic viscous flow solver that incorporates a generalized equilibrium chemistry model. Solutions to generic problems at various altitude and flight conditions show the complexity of the flow, the equilibrium chemical dissociation and its effect on the overall flow field. Viscous ideal gas solutions are compared against equilibrium gas solutions to illustrate the effect of equilibrium chemistry. Improved solution accuracy is achieved through adaptive grid refinement.

  19. Critical point of gas-liquid type phase transition and phase equilibrium functions in developed two-component plasma model

    Energy Technology Data Exchange (ETDEWEB)

    Butlitsky, M. A.; Zelener, B. V. [Joint Institute for High Temperature of Russian Academy of Science, 125412, Russia, Moscow, Izhorskaya str. 13/2 (Russian Federation); Zelener, B. B. [Joint Institute for High Temperature of Russian Academy of Science, 125412, Russia, Moscow, Izhorskaya str. 13/2 (Russian Federation); Moscow Engineering Physics Institute, 115409, Russia, Moscow, Kashirskoe sh. 31 (Russian Federation)

    2014-07-14

    A two-component plasma model, which we called a “shelf Coulomb” model has been developed in this work. A Monte Carlo study has been undertaken to calculate equations of state, pair distribution functions, internal energies, and other thermodynamics properties. A canonical NVT ensemble with periodic boundary conditions was used. The motivation behind the model is also discussed in this work. The “shelf Coulomb” model can be compared to classical two-component (electron-proton) model where charges with zero size interact via a classical Coulomb law. With important difference for interaction of opposite charges: electrons and protons interact via the Coulomb law for large distances between particles, while interaction potential is cut off on small distances. The cut off distance is defined by an arbitrary ε parameter, which depends on system temperature. All the thermodynamics properties of the model depend on dimensionless parameters ε and γ = βe{sup 2}n{sup 1/3} (where β = 1/k{sub B}T, n is the particle's density, k{sub B} is the Boltzmann constant, and T is the temperature) only. In addition, it has been shown that the virial theorem works in this model. All the calculations were carried over a wide range of dimensionless ε and γ parameters in order to find the phase transition region, critical point, spinodal, and binodal lines of a model system. The system is observed to undergo a first order gas-liquid type phase transition with the critical point being in the vicinity of ε{sub crit}≈13(T{sub crit}{sup *}≈0.076),γ{sub crit}≈1.8(v{sub crit}{sup *}≈0.17),P{sub crit}{sup *}≈0.39, where specific volume v* = 1/γ{sup 3} and reduced temperature T{sup *} = ε{sup −1}.

  20. Critical point of gas-liquid type phase transition and phase equilibrium functions in developed two-component plasma model.

    Science.gov (United States)

    Butlitsky, M A; Zelener, B B; Zelener, B V

    2014-07-14

    A two-component plasma model, which we called a "shelf Coulomb" model has been developed in this work. A Monte Carlo study has been undertaken to calculate equations of state, pair distribution functions, internal energies, and other thermodynamics properties. A canonical NVT ensemble with periodic boundary conditions was used. The motivation behind the model is also discussed in this work. The "shelf Coulomb" model can be compared to classical two-component (electron-proton) model where charges with zero size interact via a classical Coulomb law. With important difference for interaction of opposite charges: electrons and protons interact via the Coulomb law for large distances between particles, while interaction potential is cut off on small distances. The cut off distance is defined by an arbitrary ɛ parameter, which depends on system temperature. All the thermodynamics properties of the model depend on dimensionless parameters ɛ and γ = βe(2)n(1/3) (where β = 1/kBT, n is the particle's density, kB is the Boltzmann constant, and T is the temperature) only. In addition, it has been shown that the virial theorem works in this model. All the calculations were carried over a wide range of dimensionless ɛ and γ parameters in order to find the phase transition region, critical point, spinodal, and binodal lines of a model system. The system is observed to undergo a first order gas-liquid type phase transition with the critical point being in the vicinity of ɛ(crit) ≈ 13(T(*)(crit) ≈ 0.076), γ(crit) ≈ 1.8(v(*)(crit) ≈ 0.17), P(*)(crit) ≈ 0.39, where specific volume v* = 1/γ(3) and reduced temperature T(*) = ɛ(-1).

  1. High-field plasma acceleration in a high-ionization-potential gas.

    Science.gov (United States)

    Corde, S; Adli, E; Allen, J M; An, W; Clarke, C I; Clausse, B; Clayton, C E; Delahaye, J P; Frederico, J; Gessner, S; Green, S Z; Hogan, M J; Joshi, C; Litos, M; Lu, W; Marsh, K A; Mori, W B; Vafaei-Najafabadi, N; Walz, D; Yakimenko, V

    2016-06-17

    Plasma accelerators driven by particle beams are a very promising future accelerator technology as they can sustain high accelerating fields over long distances with high energy efficiency. They rely on the excitation of a plasma wave in the wake of a drive beam. To generate the plasma, a neutral gas can be field-ionized by the head of the drive beam, in which case the distance of acceleration and energy gain can be strongly limited by head erosion. Here we overcome this limit and demonstrate that electrons in the tail of a drive beam can be accelerated by up to 27 GeV in a high-ionization-potential gas (argon), boosting their initial 20.35 GeV energy by 130%. Particle-in-cell simulations show that the argon plasma is sustaining very high electric fields, of ∼150 GV m(-1), over ∼20 cm. The results open new possibilities for the design of particle beam drivers and plasma sources.

  2. Water-Stable Anionic Metal-Organic Framework for Highly Selective Separation of Methane from Natural Gas and Pyrolysis Gas.

    Science.gov (United States)

    Li, Lan; Wang, Xusheng; Liang, Jun; Huang, Yuanbiao; Li, Hongfang; Lin, Zujin; Cao, Rong

    2016-04-20

    A 3D water-stable anionic metal-organic framework [Zn4(hpdia)2]·[NH2(CH3)2]·3DMF·4H2O (FJI-C4) was constructed based on an elaborate phosphorus-containing ligand 5,5'-(hydroxyphosphoryl)diisophthalic acid (H5hpdia). FJI-C4 with narrow one-dimensional (1D) pore channels exhibits high selectivity of C3H8/CH4 and C2H2/CH4. It is the first time for the MOF which contains phosphorus for selective separation of methane from natural gas and pyrolysis gas.

  3. Dealing Collectively with Critical Incident Stress Reactions in High Risk Work Environments

    DEFF Research Database (Denmark)

    Müller-Leonhardt, Alice; Strøbæk, Pernille Solveig; Vogt, joachim

    2015-01-01

    aim of this paper is to shift the representation of coping patterns within high risk occupations to an existential part of cultural pattern and social structure, which characterises high reliability organisations. Drawing upon the specific peer model of critical incident stress management (CISM......), in which qualified operational peers support colleagues who experienced critical incident stress, the paper discusses critical incident stress management in air traffic control. Our study revealed coping patterns that co-vary with the culture that the CISM programme fostered within this specific high...... organisations. Indeed, we found that the CISM programme once integrated within the socio-cultural patterns of this specific working environment enhanced not only individual feelings of being supported but also organisational safety culture. Keywords: coping; safety culture; critical incident stress management...

  4. Computer program for high pressure real gas effects

    Science.gov (United States)

    Johnson, R. C.

    1969-01-01

    Computer program obtains the real-gas isentropic flow functions and thermodynamic properties of gases for which the equation of state is known. The program uses FORTRAN 4 subroutines which were designed for calculations of nitrogen and helium. These subroutines are easily modified for calculations of other gases.

  5. High temperature membrane reactor for catalytic gas-solid reactions

    NARCIS (Netherlands)

    Sloot, H.J.; Sloot, H.J.; Smolders, C.A.; Smolders, C.A.; van Swaaij, Willibrordus Petrus Maria; Versteeg, Geert

    1992-01-01

    A mathematical model, based on the dusty-gas model extended with surface diffusion, is presented that describes mass transport owing to molecular diffusion and viscous flow, as well as an instantaneous reversible reaction inside a membrane reactor. The reactants are fed to opposite sides of the

  6. High Temperature Gas-Cooled Test Reactor Options Status Report

    Energy Technology Data Exchange (ETDEWEB)

    Sterbentz, James William [Idaho National Lab. (INL), Idaho Falls, ID (United States); Bayless, Paul David [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-08-01

    Preliminary scoping calculations are being performed for a 100 MWt gas-cooled test reactor. The initial design uses standard prismatic blocks and 15.5% enriched UCO fuel. Reactor physics and thermal-hydraulics simulations have been performed to identify some reactor design features to investigate further. Current status of the effort is described.

  7. High critical current of Ti-sheathed MgB{sub 2} wires for AC and weight-critical applications

    Energy Technology Data Exchange (ETDEWEB)

    Alessandrini, M; Fang, H; Hanna, M; Putman, P; Zhou, Y X; Salama, K [Department of Mechanical Engineering and Texas Center for Superconductivity, University of Houston, Houston, TX 77204-4006 (United States)

    2006-01-15

    The peculiar features of magnesium diboride make it suitable for many potential applications. In the last four years of investigation of MgB{sub 2}, the scientific community's research was mainly motivated by features such as low cost, compatibility with straightforward processing methods, relatively high critical temperature, and absence of weak links between grains. Other applications suggest the accentuation of other MgB{sub 2} properties. In particular its very low mass density makes it attractive for space activities, where the cost per kilogram for orbiting is still a huge obstacle, e.g. the cost of transport to low Earth orbit can reach 15 k$ kg{sup -1}. In order to promote the use of this compound for space activities, we tested titanium as a sheath material. Titanium is non-magnetic and its alloys are almost half the weight of steel but with yield stresses up to three times higher. We fabricated Ti-sheathed MgB{sub 2} through the powder-in-tube process. These wires show similar results to those sheathed with Fe. At 4 K the critical current density J{sub c} is well above 7 x 10{sup 5} A cm{sup -2}. The interface between the superconducting intermetallic compound and the lightweight sheath does not show any evidence of reaction and diffusion up to 900 deg. C. An analysis was carried out using x-ray diffraction, scanning electron microscopy with an energy dispersive spectrometer, and electron microprobe analysis.

  8. TO "LIMITATIONS OF ROI TESTING FOR VENTING DESIGN: DESCRIPTION OF AN ALTERNATIVE APPROACH BASED ON ATTAINMENT OF A CRITICAL PORE-GAS VELOCITY IN CONTAMINATED MEDIA

    Science.gov (United States)

    In this paper, we describe the limitations of radius of influence (ROI) evaluation for venting design in more detail than has been done previously and propose an alternative method based on specification and attainment of critical pore-gas velocities in contaminated subsurface me...

  9. Use of nitrogen gas in high-speed milling of Ti-6Al-4V

    Institute of Scientific and Technical Information of China (English)

    KE Ying-lin; DONG Hui-yue; LIU Gang; ZHANG Ming

    2009-01-01

    To inhibit chips burning in the high-speed cutting of Ti-6Al-4V, nitrogen gas with 0.7 MPa pressure was ejected at the milling zone. The high speed flowing of nitrogen gas speeds up the chips leaving, and prevents the chips from burning at the same time. By this method the cutting force is reduced. Especially, the temperature increment of the finished surface is smaller than 5 ℃. This prevents the increase of hardness, improves the roughness of the finished surface, and reduces the tools wear. Comparing and analyzing the morphology and color of chips, which are obtained from the high-speed machining of Ti-6Al-4V with and without nitrogen gas ejection, show the action mechanism of nitrogen gas during the high-speed machining of titanium alloy, and it is concluded that nitrogen gas can be used to realize the proper high-speed milling of Ti-6Al-4V titanium alloy.

  10. Gas adsorption and desorption effects on high pressure small volume cylinders and their relevance to atmospheric trace gas analysis

    Science.gov (United States)

    Satar, Ece; Nyfeler, Peter; Pascale, Céline; Niederhauser, Bernhard; Leuenberger, Markus

    2017-04-01

    Long term atmospheric monitoring of trace gases requires great attention to precision and accuracy of the measurement setups. For globally integrated and well established greenhouse gas observation networks, the World Meteorological Organization (WMO) has set recommended compatibility goals within the framework of its Global Atmosphere Watch (GAW) Programme [1]. To achieve these challenging limits, the measurement systems are regularly calibrated with standard gases of known composition. Therefore, the stability of the primary and secondary gas standards over time is an essential issue. Past studies have explained the small instabilities in high pressure standard gas cylinders through leakage, diffusion, regulator effects, gravimetric fractionation and surface processes [2, 3]. The latter include adsorption/desorption, which are functions of temperature, pressure and surface properties. For high pressure standard gas mixtures used in atmospheric trace gas analysis, there exists only a limited amount of data and few attempts to quantify the surface processes [4, 5]. Specifically, we have designed a high pressure measurement chamber to investigate trace gases and their affinity for adsorption on different surfaces over various temperature and pressure ranges. Here, we focus on measurements of CO2, CH4 and CO using a cavity ring down spectroscopy analyzer and quantify the concentration changes due to adsorption/desorption. In this study, the first results from these prototype cylinders of steel and aluminum will be presented. References [1] World Meteorological Organization (WMO), Global Atmosphere Watch.(GAW): Report No. 229, 18th WMO/IAEA Meeting on Carbon Dioxide, Other Greenhouse Gases and Related Tracers Measurement Techniques (GGMT-2015), 2016. [2] Keeling, R. F., Manning, A. C., Paplawsky, W. J., and Cox, A. C.: On the long-term stability of reference gases for atmospheric O2 /N2 and CO2 measurements, Tellus B, 59, 10.3402/tellusb.v59i1.16964, 2007. [3

  11. Critical Size for the Particle Burn-out of Solid Carbon and/or Boron as the High-Energy Density Fuel

    OpenAIRE

    2013-01-01

    It is intended to demonstrate an existence of the critical size for the particle burn-out, exposed directly to oxidizers at high temperatures under which oxide vaporization can be facilitated, with the solid carbon taken as an example, under recognition that particles considered are too small to support a gas-phase envelop-flame even at elevated temperatures. After describing the temporal variations of the particle temperature and size, use has been made of the asymptotics to derive the gover...

  12. Graphene based multiple heterojunctions as an effective approach for high-performance gas sensing

    Science.gov (United States)

    Wu, Chia-Lin; Cheng, Ching-Cheng; Sun, Tzu-Min; Haider, Golam; Liou, Yi-Rou; Tan, Wei-Jyun; Chiang, Chia-Wei; Chen, Yang-Fang

    2016-09-01

    We develop graphene-based multiple heterojunctions to realize sensors with a very high sensitivity (current across the heterojunction. The charge induced by the absorbed molecules remains in the graphene layer without transferring into the underlying layer owing to the well-designed band alignment among the constituent materials, which results in ultra-fast and highly sensitive performance. Furthermore, we demonstrate that with different polarities of external bias, the graphene multiple-junction sensors can be used to selectively detect different gases. In addition to the suitable band alignment, the high performance of our device arises from the sandwich structure of top and bottom electrodes, which enables to exponentially enhance the current across the Schottky junction. Moreover, the large shift of the Fermi level of graphene induced by its inherent nature of low density of states also plays an important role. Compared with all published reports, our device possesses a much better performance. Particularly, the response time is three orders of magnitude faster than those of reported values, which can provide a critical step to advance graphene based gas sensors toward real world applications.

  13. Study of a sealed high gas pressure THGEM detector and response of Alpha particle spectra

    CERN Document Server

    Zhang, Yu-Ning; Liu, Hong-Bang; Xie, Yi-Gang; Lyu, Xiao-Rui; Chen, Shi; Huang, Wen-Qian; Hong, Dao-Jin; Zheng, Yang-Heng

    2016-01-01

    A sealed high gas pressure detector working in pure argon is assembled. It consists of a 5 cm $\\times$ 5 cm PCB THGEM (THick Gaseous Electron Multipliers). The detector structure and experimental setup are described. The performances under high pressure of 2 atm mainly consist in selecting optimal voltages for ionization region and induction region. The dependence of the shape of Alpha particle spectra measured with relative gas gain on gas pressure (1.3 $\\sim$ 2.0 atm) has been studied. The 8 groups of relative gas gain versus working voltage of THGEM expressed by weighting filed $E/P$ are normalized, being consistent with theory. The results show that the air tightness of the chamber is good measured by a sensitive barometer and checked with gas gain. The experimental results are compared with Monte Carlo simulation on energy deposition without gas gain involved.

  14. A Highly Stable Microporous Covalent Imine Network Adsorbent for Natural Gas Upgrading and Flue Gas CO2 Capture

    KAUST Repository

    Das, Swapan Kumar

    2016-06-06

    The feasible capture and separation of CO2 and N2 from CH4 is an important task for natural gas upgrading and the control of greenhouse gas emissions. Here, we studied the microporous covalent imine networks (CIN) material prepared through Schiff base condensation and exhibited superior chemical robustness under both acidic and basic conditions and high thermal stability. The material possesses a relatively uniform nanoparticle size of approximately 70 to 100 nm. This network featured permanent porosity with a high surface area (722 m2g-1) and micropores. A single-component gas adsorption study showed enhanced CO2 and CH4 uptakes of 3.32 mmol/g and 1.14 mmol/g, respectively, at 273 K and 1 bar, coupled with high separation selectivities for CO2/CH4, CH4/N2, and CO2/N2 of 23, 11.8 and 211, respectively. The enriched Lewis basicity in the porous skeletons favours the interaction of quadrupolar CO2 and polarizable CH4, resulting in enhanced CH4 and CO2 uptake and high CH4/N2, CO2/CH4 and CO2/N2 selectivities. Breakthrough experiments showed high CO2/CH4, CH4/N2 and CO2/N2 selectivities of 7.29, 40 and 125, respectively, at 298 K and 1 bar. High heats of adsorption for CH4 and CO2 (QstCH4; 32.61 kJ mol-1 and QstCO2; 42.42 kJ mol-1) provide the ultimate validation for the high selectivity. To the best of our knowledge, such a versatile adsorbent material that displays both enhanced uptake and selectivity for a variety of binary gas mixtures, including CO2/ CH4, CO2/N2 and CH4/N2, has not been extensively explored.

  15. Convection in an ideal gas at high Rayleigh numbers.

    Science.gov (United States)

    Tilgner, A

    2011-08-01

    Numerical simulations of convection in a layer filled with ideal gas are presented. The control parameters are chosen such that there is a significant variation of density of the gas in going from the bottom to the top of the layer. The relations between the Rayleigh, Peclet, and Nusselt numbers depend on the density stratification. It is proposed to use a data reduction which accounts for the variable density by introducing into the scaling laws an effective density. The relevant density is the geometric mean of the maximum and minimum densities in the layer. A good fit to the data is then obtained with power laws with the same exponent as for fluids in the Boussinesq limit. Two relations connect the top and bottom boundary layers: The kinetic energy densities computed from free fall velocities are equal at the top and bottom, and the products of free fall velocities and maximum horizontal velocities are equal for both boundaries.

  16. High temperature erosion of coated superalloys for gas turbines

    Energy Technology Data Exchange (ETDEWEB)

    Restall, J.E.; Stephenson, D.J.

    1987-04-01

    Particulate materials ingested with the intake air, together with other solids generated within the gas turbine, are known to have the potential of degrading the hot oxidized or corroded surfaces of static and rotating aerofoil components. The nature of the degradation may be primarily by oxidation, corrosion or erosion or through some form of interaction between these processes. These regimes are illustrated by reference to the metallurgical assessment of components withdrawn from a marine gas turbine and a turbine used for pressurized fluidized-bed combustion trials. The conditions under which surface coatings may be expected to enhance the erosion-corrosion resistance of hot-end turbine components are discussed. From laboratory erosion experiments, particular attention is directed towards the importance of oxide scale plasticity and the ductile-to-brittle transition temperature of the coating under various particle-loading conditions.

  17. High-resolution seafloor features related to potential gas-hydrate formation off SW Taiwan

    Science.gov (United States)

    Hsu, S.; Tsai, C.; Chen, S.; Shih, T.

    2010-12-01

    The area off SW Taiwan is considered as a high potential area for gas-hydrate formation. The gas-hydrate signature is indicated by the abundant presence of BSR (Bottom-Simulating-Reflector). High methane concentration is also shown in the bottom water near the seafloor. To have a better understanding, we have conducted deep-towed survey of side-scan sonar and sub-bottom profiler in several potential areas. Pockmarks are found in several places. Some are related to gas seeping. The gas seeps are especially obvious in high-resolution sub-bottom profilers. The high pore-pressure due to the charging of the gas has clearly uplifted a top layer of sediments. The pockmarks area usually accompany the presence of authigenic carbonate. In the image of side-scan sonar data, the irregular patterns of strong backscatter signal are associated with the gas seeping or pockmark sites. The presence of pockmarks or gas seeps could be related to structural faults. Because the NW convergence of the Philippine Sea plate relative to the Eurasian plate, the area off SW Taiwan in fact is under compression and has caused folds and faults. These structural faults provide efficient conduits for fluid to migrate upward. Thus, the pockmarks frequently appear near faults. In the water depth of about 450m, the upward gas even goes into water column and creates clear gas plume image in EK 500 data. The gas is inferred to be dissociated from gas-hydrate and can get into the atmosphere. The dissociation of gas-hydrate has probably also induced the instability of the seafloor off SW Taiwan and cuased submarine landslides.

  18. Characteristic features of the operation of high-temperature heat pipes with a noncondesable gas

    Science.gov (United States)

    Tolubinskiy, V. I.; Shevchuk, Ye. N.

    1987-01-01

    The principal concepts related to the nature of the processes occurring in high-temperature heat pipes with a noncondensable gas are examined, and guidelines for the development of such heat pipes are presented. The discussion is illustrated by experimental results obtained for a horizontal sodium heat pipe (diameter, 18/1 mm; length, 710 mm). In particular, attention is given to the starting dynamics and mechanisms, the shape of the vapor-gas front, and the vapor-gas front velocity.

  19. Evaluation of the Frequency for Gas Sampling for the High Burnup Confirmatory Data Project

    Energy Technology Data Exchange (ETDEWEB)

    Stockman, Christine T. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Alsaed, Halim A. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Bryan, Charles R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Marschman, Steven C. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Scaglione, John M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-05-01

    This report provides a technically based gas sampling frequency strategy for the High Burnup (HBU) Confirmatory Data Project. The evaluation of: 1) the types and magnitudes of gases that could be present in the project cask and, 2) the degradation mechanisms that could change gas compositions culminates in an adaptive gas sampling frequency strategy. This adaptive strategy is compared against the sampling frequency that has been developed based on operational considerations.

  20. Greenhouse Gas Emissions of Indianapolis using a High-Density Surface Tower Network and an Atmospheric Inversion

    Science.gov (United States)

    Lauvaux, T.; Miles, N. L.; Davis, K. J.; Richardson, S.; Deng, A.; Sarmiento, D. P.; Wu, K.; Sweeney, C.; Karion, A.; Hardesty, R. M.; Brewer, A.; Turnbull, J. C.; Iraci, L. T.; Hillyard, P. W.; Podolske, J. R.; Gurney, K. R.; Patarasuk, R.; Cambaliza, M. O. L.; Shepson, P. B.; Whetstone, J. R.

    2014-12-01

    The Indianapolis Flux Experiment (INFLUX) was designed to develop and evaluate methods of detection and attribution of greenhouse gas fluxes from urban environments. Determination of greenhouse gas fluxes and uncertainty bounds is essential for the evaluation of the effectiveness of mitigation strategies. Indianapolis is intended to serve as a test bed for these methods; the results will inform efforts at measuring emissions from urban centers worldwide, including megacities. The generally accepted method for determining urban greenhouse gas emissions is inventories, which are compiled from records of land use and human activity. Atmospheric methods, in which towers are instrumented with sensors to measure greenhouse gas mole fractions and these data are used in an inversion model, have the potential to provide independent determination of emissions. The current INFLUX observation network includes twelve in-situ tower-based, continuous measurements of CO2. A subset of five towers additionally measure CH4, and a different subset measure CO. The subset measuring CO also include weekly flask samples of a wide variety of trace gases including 14CO2. Here we discuss the observed urban spatial and temporal patterns in greenhouse gas mole fraction in Indianapolis, with the critical result being the detectability of city emissions with this high-density network. We also present the first atmospheric inversion results for both CO2 and CH4, compare these results to inventories, and discuss the effects of critical assumptions in the inversion framework. The construction of unbiased atmospheric modeling systems and well-defined prior errors remains an important step in atmospheric emissions monitoring over urban areas. In order to minimize transport model errors, we developed a WRF-Chem FDDA modeling system ingesting surface and profile measurements of horizontal mean wind, temperature, and moisture. We demonstrate the impact of the meteorological data assimilation system on

  1. High Resolution Molecular Gas Maps of M33

    CERN Document Server

    Rosolowsky, E; Matsushita, S; Willner, S

    2007-01-01

    New observations of CO (J=1->0) line emission from M33, using the 25 element BEARS focal plane array at the Nobeyama Radio Observatory 45-m telescope, in conjunction with existing maps from the BIMA interferometer and the FCRAO 14-m telescope, give the highest resolution (13'') and most sensitive (RMS ~ 60 mK) maps to date of the distribution of molecular gas in the central 5.5 kpc of the galaxy. A new catalog of giant molecular clouds (GMCs) has a completeness limit of 1.3 X 10^5 M_sun. The fraction of molecular gas found in GMCs is a strong function of radius in the galaxy, declining from 60% in the center to 20% at galactocentric radius R_gal ~ 4 kpc. Beyond that radius, GMCs are nearly absent, although molecular gas exists. Most (90%) of the emission from low mass clouds is found within 100 pc projected separation of a GMC. In an annulus 2.1< R_gal <4.1 kpc, GMC masses follow a power law distribution with index -2.1. Inside that radius, the mass distribution is truncated, and clouds more massive tha...

  2. Critical Temperature Characteristics of Layered High-Temperature Superconductor Under Pressure

    Institute of Scientific and Technical Information of China (English)

    LIANG Fang-Ying

    2009-01-01

    We consider a Ginzburg-Landau modified model of layered high-temperature superconductor under pres-sure. We have theoretically studied the relation between the pressure and the temperature of layered high-temperature superconductor. If the pressure is not a constant, we have a relation of quadratic equation between the pressure and the temperature of layered high-temperature superconductor. In a special case, we find the critical temperature decreases with further increasing pressure. In another special case, the critical temperature increases with further increasing pressure.

  3. Development of Assessment Instrument of Critical Thinking in Physics at Senior High School

    Science.gov (United States)

    Sugiarti, T.; Kaniawati, I.; Aviyanti, L.

    2017-02-01

    The result of preliminary study shows that the assessment of physics in school did not train students’ critical thinking skill. The assessment instrument just measured low cognitive aspects. Supposedly, critical thinking skill is trained in the assessment activity. The study aims to determine the characteristics and the quality of critical thinking skill instrument. It employs descriptive-qualitative method with research and development as the research design. The research participants are 35 students involved in the limited trial and 188 students in the wider trial from three public senior high school in Ciamis which in high level school. The data was collected through expert validation, tests and interviews. The results indicate that the characteristics of the assessment instrument of critical thinking skill is open-ended. The instrument fulfills some indicators namely analyzing argument, deduction, induction, and display information in the form of scenario, text, graphic and table. In addition, the data processing through V4 Anates program shows that the instrument reliability achieves 0.67 with high interpretation of 0.67 and the validity is 0.47 with enough interpretation. Thus, the assessment instrument of critical thinking skill in the form of open-ended essay meets the criteria of quality test, so it can use as instrument of assessment critical thinking skill.

  4. Ionization effects in the generation of wake-fields by ultra-high contrast femtosecond laser pulses in argon gas

    Energy Technology Data Exchange (ETDEWEB)

    Makito, K.; Shin, J.-H. [Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita, Osaka (Japan); Zhidkov, A.; Hosokai, T.; Masuda, S. [Photon Pioneers Center, Osaka University, 2-8, Yamadaoka, Suita, Osaka (Japan); Japan Science and Technology Agency (JST), CREST, 2-8 Yamadaoka, Suita, Osaka (Japan); Kodama, R. [Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita, Osaka (Japan); Photon Pioneers Center, Osaka University, 2-8, Yamadaoka, Suita, Osaka (Japan); Japan Science and Technology Agency (JST), CREST, 2-8 Yamadaoka, Suita, Osaka (Japan)

    2012-10-15

    Difference in mechanisms of wake-field generation and electron self-injection by high contrast femtosecond laser pulses in an initially neutral Argon gas and in pre-ionized plasma without ionization is studied via 2D particle-in-cell simulations including optical ionization of the media. For shorter laser pulses, 40 fs, ionization results only in an increase of the charge of accelerated electrons by factor of {approx}3 with qualitatively the same energy distribution. For longer pulses, 80 fs, a more stable wake field structure is observed in the neutral gas with the maximal energy of the accelerated electrons exceeding that in the fixed density plasma. In higher density Argon, an ionizing laser pulse converts itself to a complex system of solitons at a self-induced, critical density ramp.

  5. Ionization effects in the generation of wake-fields by ultra-high contrast femtosecond laser pulses in argon gas

    Science.gov (United States)

    Makito, K.; Zhidkov, A.; Hosokai, T.; Shin, J.-H.; Masuda, S.; Kodama, R.

    2012-10-01

    Difference in mechanisms of wake-field generation and electron self-injection by high contrast femtosecond laser pulses in an initially neutral Argon gas and in pre-ionized plasma without ionization is studied via 2D particle-in-cell simulations including optical ionization of the media. For shorter laser pulses, 40 fs, ionization results only in an increase of the charge of accelerated electrons by factor of ˜3 with qualitatively the same energy distribution. For longer pulses, 80 fs, a more stable wake field structure is observed in the neutral gas with the maximal energy of the accelerated electrons exceeding that in the fixed density plasma. In higher density Argon, an ionizing laser pulse converts itself to a complex system of solitons at a self-induced, critical density ramp.

  6. Investigation of the Critical Current Density of YBaCuO high-temperature Superconductor Ceramic

    OpenAIRE

    METSKHVARISHVILI, I. R.; KEKELIDZE, N. P.; METSKHVARISHVILI, M. R.

    2002-01-01

    The method of high harmonics is used to investigate penetration of low magnetic fields within the Y1Ba2Cu3O7 high-temperature superconductor ceramic. Given experimental results are explained by the modal dependencies between the value of critical current density and the magnetic induction B: jc(B) = jc(0){\\frac{{B02}} {{B02 + B2}}}.

  7. Molecular Gas in the Halo Fuels the Growth of a Massive Cluster Galaxy at High Redshift

    CERN Document Server

    Emonts, B H C; Villar-Martin, M; Norris, R P; Ekers, R D; van Moorsel, G A; Dannerbauer, H; Pentericci, L; Miley, G K; Allison, J R; Sadler, E M; Guillard, P; Carilli, C L; Mao, M Y; Rottgering, H J A; De Breuck, C; Seymour, N; Gullberg, B; Ceverino, D; Jagannathan, P; Vernet, J; Indermuehle, B T

    2016-01-01

    The largest galaxies in the Universe reside in galaxy clusters. Using sensitive observations of carbon-monoxide, we show that the Spiderweb Galaxy -a massive galaxy in a distant protocluster- is forming from a large reservoir of molecular gas. Most of this molecular gas lies between the protocluster galaxies and has low velocity dispersion, indicating that it is part of an enriched inter-galactic medium. This may constitute the reservoir of gas that fuels the widespread star formation seen in earlier ultraviolet observations of the Spiderweb Galaxy. Our results support the notion that giant galaxies in clusters formed from extended regions of recycled gas at high redshift.

  8. Dense gas in high-latitude molecular clouds

    Science.gov (United States)

    Reach, William T.; Pound, Marc W.; Wilner, David J.; Lee, Youngung

    1995-01-01

    The nearby molecular clouds MBM 7, 12, 30, 32, 40, 41, and 55 were surveyed for tracers of dense gas, including the (1-0), (2-1), and (3-2) rotational lines of CS and the (1-0) lines of HCO(+) and HCN. MBM 7 and MBM 12 contain dense cores, while the other clouds contain little or no traces of dense gas. Comparison of the emission from dense gas tracers to that of (13)CO reveals that the former are more compact in angular size as well as line width. An extensive CS(2-1) survey of part of MBM 12 reveals that the emission is characterized by clumps on approximately 3 min scales as well as extended emission. Observations of the CS(1-0) and (3-2) lines using telescopes with matched beam sizes reveal that the volume density must be at least approximately 10(exp 4.5)/cc within the (3-2) emitting regions, which are approximately 0.03 pc in radius. Electron excitation of the CS rotational levels is ruled out (in the cores) by comparing the (3-2)/(1-0) line ratios with models including H2 and electron collisions. The volume density in the cores is substantially larger than in the portions of the cloud traced by CO emission. The density increases into the cores as r(exp -2), suggesting dynamical collapse. The masses of the cores are close to the virial mass, suggesting they are dynamically bound. The cores in MBM 7 and MBM 12 are thus likely to form stars; they are the nearest sites of star formation.

  9. Implementing an Inexpensive and Accurate Introductory Gas Density Activity with High School Students

    Science.gov (United States)

    Cunningham, W. Patrick; Joseph, Christopher; Morey, Samantha; Santos Romo, Ana; Shope, Cullen; Strang, Jonathan; Yang, Kevin

    2015-01-01

    A simplified activity examined gas density while employing cost-efficient syringes in place of traditional glass bulbs. The exercise measured the density of methane, with very good accuracy and precision, in both first-year high school and AP chemistry settings. The participating students were tasked with finding the density of a gas. The…

  10. Analysis of Turkish High School Chemistry Textbooks and Teacher-Generated Questions about Gas Laws

    Science.gov (United States)

    Nakiboglu, Canan; Yildirir, H.

    2011-01-01

    This study presents the results of an analysis of high school chemistry textbooks and teacher-generated questions about gas laws. The materials that were analyzed consisted of 456 questions about gas laws found in seven grade 10 chemistry textbooks and 264 teacher-generated examination questions prepared by seven chemistry teachers from three…

  11. Controlling of the gas emissions at high performance longwalls in the German hard coal mining industry

    Energy Technology Data Exchange (ETDEWEB)

    Brandt, J. [Deutsche Montan Technologie GmbH (Germany)

    2001-07-01

    In order to enhance productivity in German hard coal mining the total number of workings was reduced and at the same time the output per working point was increased considerably. The average output per working point rose to more than 10,000 t/d with top values of 18,000 t/d in single places. This was achieved by increasing the advance rate and lengthening the face to 450 m. At high performance faces, especially in seams with medium and high gas content rates, the gas inflow can easily become a safety risk and an obstacle to productivity. This paper gives an abstract about the tested techniques and introduces new approaches to the control of gas emission at high performance faces. Essential measures in the control of gas emission for high performance faces are: - pre-degasification of the working seam; optimization of conventional gas drainage; drilling of long deflected boreholes in the gas emission zone of workings (being currently tested); application of effective drilling techniques for rapid preparation of gas drainage boreholes (percussion drilling); selection of the optimal ventilation layout and; building a partially permeable roadside pack (gas windows). 8 refs., 13 figs.

  12. High rate tests of microstrip gas chambers for CMS

    CERN Document Server

    Malina, R F; Bell, B; Bellazzini, R; Bozzo, M; Brand, C; Brez, A; Caner, A; Cattai, A; Chorowicz, V; Contardo, D; Latronico, L; Lumb, N; Magazzù, C; Martín, J; Massai, M M; Mirabito, L; Morelli, A; Raffo, R; Rolandi, Luigi; Smadja, G; Spandre, G; Spezziga, M; Tsirou, A L

    1999-01-01

    Microstrip gas chambers (MSGC's) have been proposed for equipping the outer region of the tracker of the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC). The MSGC's have undergone extensive development and tests during the last few years and their performance is well established. An important issue that has to be addressed to date is whether MSGC's can maintain their characteristics after a long exposure to an intense flux of particles, similar to LHC. We report results from the most recent beam test addressing this topic. (9 refs).

  13. Design of a high density cold gas attitude control system

    Science.gov (United States)

    Hall, Sarah E.; Lewis, Mark J.; Akin, David L.

    1993-01-01

    A comparison of the experimental results of a nitrous oxide cold gas thruster with the predicted performance from a numerical simulation of nozzle operations is discussed. Tests were conducted in a vacuum chamber to verify analytical predictions of both nitrogen and nitrous oxide. Preliminary results indicate an Isp for N2O of 61, and an Isp of 69 for N2. Based on the results of this research, parameters are presented for a nitrous oxide-based reaction control system for a small spacecraft currently under development.

  14. Silicon Carbide-Based Hydrogen Gas Sensors for High-Temperature Applications

    OpenAIRE

    Sangchoel Kim; Jehoon Choi; Minsoo Jung; Seongjeen Kim; Sungjae Joo

    2013-01-01

    We investigated SiC-based hydrogen gas sensors with metal-insulator-semiconductor (MIS) structure for high temperature process monitoring and leak detection applications in fields such as the automotive, chemical and petroleum industries. In this work, a thin tantalum oxide (Ta2O5) layer was exploited with the purpose of sensitivity improvement, because tantalum oxide has good stability at high temperature with high permeability for hydrogen gas. Silicon carbide (SiC) was used as a substrate ...

  15. Relaxation and gas drainage boreholes for high performance longwall operations in low permeability coal seams

    Energy Technology Data Exchange (ETDEWEB)

    Imgrund, Thomas [DMT GmbH und Co. KG, Essen (Germany); Bauer, Frank [Hazemag und EPR GmbH, Duelmen (Germany). Mining

    2013-06-15

    With an increasing depth of cover, gas emission control and gas outbursts prevention has become an increasingly important issue in coal mining. Deep multi-seam mining often requires operation in an environment characterised by a high gas content and gas pressure. Control of gas related risks has to be realised during heading and close to the longwall by proper risk assessment and flexible drilling schemes. These cover exploration and relaxation drilling, in-seam drilling for pre-drainage and cross measure drilling for drainage of roof and the floor gas emissions. DMT provides comprehensive solutions based on a scientific background. These solutions are engineered considering their technical feasibility. Hazemag Mining offers a large number of complete machinery including tools systems for the implementation of those solutions. (orig.)

  16. How Deep is the Critical Zone: A Scientific Question with Potential Impact For Decision-makers in Areas of Shale-Gas Development and Hydraulic Fracturing

    Science.gov (United States)

    Brantley, S. L.

    2014-12-01

    Citizens living in areas of shale-gas development such as the Marcellus gas play in Pennsylvania and surrounding states are cognizant of the possibility that drilling and production of natural gas -- including hydraulic fracturing -- may have environmental impacts on their water. The Critical Zone is defined as the zone from vegetation canopy to the lower limits of groundwater. This definition is nebulous in terms of the lower limit, and yet, defining the bottom of the Critical Zone is important if citizens are to embrace shale-gas development. This is because, although no peer-reviewed study has been presented that documents a case where hydraulic fracturing or formation fluids have migrated upwards from fracturing depths to drinking water resources, a few cases of such leakage have been alleged. On the other hand, many cases of methane migration into aquifers have been documented to occur and some have been attributed to shale-gas development. The Critical Zone science community has a role to play in understanding such contamination problems, how they unfold, and how they should be ameliorated. For example, one big effort of the Critical Zone science community is to promote sharing of data describing the environment. This data effort has been extended to provide data for citizens to understand water quality by a team known as the Shale Network. As scientists learn to publish data online, these efforts must also be made accessible to non-scientists. As citizens access the data, the demand for data will grow and all branches of government will eventually respond by providing more accessible data that will help the public and policy-makers make decisions.

  17. High Temperature Gas-cooled Reactor Projected Markets and Scoping Economics

    Energy Technology Data Exchange (ETDEWEB)

    Larry Demick

    2010-08-01

    The NGNP Project has the objective of developing the high temperature gas-cooled reactor (HTGR) technology to supply high temperature process heat to industrial processes as a substitute for burning of fossil fuels, such as natural gas. Applications of the HTGR technology that have been evaluated by the NGNP Project for supply of process heat include supply of electricity, steam and high-temperature gas to a wide range of industrial processes, and production of hydrogen and oxygen for use in petrochemical, refining, coal to liquid fuels, chemical, and fertilizer plants.

  18. Formation Mechanism of the High-quality Upper Paleozoic Natural Gas Reservoirs in the Ordos Basin

    Institute of Scientific and Technical Information of China (English)

    ZHAO Wenzhi; WANG Zecheng; CHEN Menjin; ZHENG Hongju

    2005-01-01

    The upper Paleozoic natural gas reservoirs in the Ordos basin are generally characterized by a large gas-bearing area and low reserve abundance. On such a geological background, there still exist gas-enriched zones, with relatively high outputs, high reserve abundance and stably distributed gas layers. The gas-enriched layers with relatively high permeability (the lower limit permeability is 0.5×l0-3 μm2) are key factors for the enrichment and high output of natural gas. Based on core observation, analytic results of inclusions, and a great deal of drilling data, we proposed the following four mechanisms for the formation of high-quality reservoirs: (1) in the source area the parent rocks are mainly metamorphic rocks and granites, which are favorable to keeping primary porosity; (2) under the condition of low A/S (accommodation/sediment supply) ratios,sandstone complex formed due to multistage fluvial stacking and filling are coarse in grain size with a high degree of sorting,low content of mud and good physical properties; (3) early-stage recharge of hydrocarbons restricted compaction and cementation, and thus are favorable to preservation of primary pores; (4) microfractures caused by the activity of basement faults during the Yanshan Movement stage can not only improve the permeability of tight sandstones, but also afford vertical pathways for hydrocarbon gas migration.

  19. High magnetic-field scales and critical currents in SmFeAs(O, F) crystals

    Science.gov (United States)

    Moll, Philip J. W.; Puzniak, Roman; Balakirev, Fedor; Rogacki, Krzysztof; Karpinski, Janusz; Zhigadlo, Nikolai D.; Batlogg, Bertram

    2010-08-01

    With the discovery of new superconducting materials, such as the iron pnictides, exploring their potential for applications is one of the foremost tasks. Even if the critical temperature Tc is high, intrinsic electronic properties might render applications difficult, particularly if extreme electronic anisotropy prevents effective pinning of vortices and thus severely limits the critical current density, a problem well known for cuprates. Although many questions concerning microscopic electronic properties of the iron pnictides have been successfully addressed and estimates point to a very high upper critical field, their application potential is less clear. Thus, we focus here on the critical currents, their anisotropy and the onset of electrical dissipation in high magnetic fields up to 65T. Our detailed study of the transport properties of SmFeAsO0.7F0.25 single crystals reveals a promising combination of high (>2×106Acm-2) and nearly isotropic critical current densities along all crystal directions. This favourable intragrain current transport in SmFeAs(O, F), which shows the highest Tc of 54K at ambient pressure, is a crucial requirement for possible applications. Essential in these experiments are four-probe measurements on focused-ion-beam-cut single crystals with a sub-square-micrometre cross-section, with current along and perpendicular to the crystallographic c axis.

  20. High Performance Indium-Doped ZnO Gas Sensor

    Directory of Open Access Journals (Sweden)

    Junjie Qi

    2015-01-01

    Full Text Available Gas sensors for ethanol and acetone based on ZnO nanobelts with doping element indium were fabricated. Excellent sensitivity accompanied with short response time (10 s and recovery time (23 s to 150 ppm ethanol is obtained. For In-doped sensors, a minimum concentration of 37.5 ppm at 275°C in acetone was observed with an average sensitivity of 714.4, which is 7 times larger than that of the pure sensors and much larger than that reported response (16 of Co-doped ZnO nanofibers to acetone. These results indicate that doping elements can improve gas sensitivity, which is associated with oxygen space and valence ions. In-doped ZnO nanobelts exhibit higher sensitivity to acetone than that to ethanol. These results indicate that doped ZnO nanobelts can successfully distinguish acetone and ethanol, which can be put into various practical applications.

  1. Study of Solid Particle Behavior in High Temperature Gas Flows

    Science.gov (United States)

    Majid, A.; Bauder, U.; Stindl, T.; Fertig, M.; Herdrich, G.; Röser, H.-P.

    2009-01-01

    The Euler-Lagrangian approach is used for the simulation of solid particles in hypersonic entry flows. For flow field simulation, the program SINA (Sequential Iterative Non-equilibrium Algorithm) developed at the Institut für Raumfahrtsysteme is used. The model for the effect of the carrier gas on a particle includes drag force and particle heating only. Other parameters like lift Magnus force or damping torque are not taken into account so far. The reverse effect of the particle phase on the gaseous phase is currently neglected. Parametric analysis is done regarding the impact of variation in the physical input conditions like position, velocity, size and material of the particle. Convective heat fluxes onto the surface of the particle and its radiative cooling are discussed. The variation of particle temperature under different conditions is presented. The influence of various input conditions on the trajectory is explained. A semi empirical model for the particle wall interaction is also discussed and the influence of the wall on the particle trajectory with different particle conditions is presented. The heat fluxes onto the wall due to impingement of particles are also computed and compared with the heat fluxes from the gas.

  2. Perceived Criticism in the Treatment of a High-Risk Adolescent.

    Science.gov (United States)

    Hooley, Jill M; Miklowitz, David J

    2017-01-23

    Perceived criticism (PC) is a construct that plays a key role in family relationships of persons with psychiatric disorders. It can be assessed in a brief and simple way using the Perceived Criticism Measure. PC ratings made by patients about their caregivers predict adverse clinical outcomes including increases in symptoms and relapse across a broad range of psychiatric diagnoses. Although research supports the concurrent and predictive validity of PC, the measure is not widely used in clinical practice. Here, we describe the construct of PC and review evidence supporting its clinical utility. We then illustrate how criticism and perceptions of criticism can be addressed in a clinical context, describing a family focused treatment approach used with a depressed adolescent at high risk for bipolar disorder.

  3. Silicon carbide-based hydrogen gas sensors for high-temperature applications.

    Science.gov (United States)

    Kim, Seongjeen; Choi, Jehoon; Jung, Minsoo; Joo, Sungjae; Kim, Sangchoel

    2013-10-09

    We investigated SiC-based hydrogen gas sensors with metal-insulator-semiconductor (MIS) structure for high temperature process monitoring and leak detection applications in fields such as the automotive, chemical and petroleum industries. In this work, a thin tantalum oxide (Ta2O5) layer was exploited with the purpose of sensitivity improvement, because tantalum oxide has good stability at high temperature with high permeability for hydrogen gas. Silicon carbide (SiC) was used as a substrate for high-temperature applications. We fabricated Pd/Ta2O5/SiC-based hydrogen gas sensors, and the dependence of their I-V characteristics and capacitance response properties on hydrogen concentrations were analyzed in the temperature range from room temperature to 500 °C. According to the results, our sensor shows promising performance for hydrogen gas detection at high temperatures.

  4. High-temperature high-pressure gas cleanup with ceramic bag filters. Draft final report

    Energy Technology Data Exchange (ETDEWEB)

    Shackleton, M.; Chang, R.; Sawyer, J.; Kuby, W.; Turner-Tamiyasu, E.

    1982-12-06

    Advanced processes designed for the efficient use of coal in the production of energy will benefit from, or even depend upon, highly efficient, economical, high-temperature removal systems for fine particulates. In the case of pressurized fluidized-bed combustion (PFBC), the hot gas cleanup device must operate at approximately 1600/sup 0/F. Existing commercial filter systems are temperature limited due to the filter material, but ceramic fibers intended for refractory insulation offer the promise of a practical high-temperature filter media if they can be incorporated into a design which combines filter performance with acceptable durability. The current work was initiated to further develop and demonstrate on a larger-scale basis, a ceramic fiber filtration system for application to coal-fired PFBC's. The development effort centered around the need to replace the knit metal wire scrim, used in earlier designs as support for the fine fiber ceramic mat filtration medium, with a corrosion-resistant material. This led to the selection of woven ceramic cloth for support of the mat layer. Because of the substantial difference in strength and other material properties between the metal and ceramic cloth, tests were necessary to optimize the filter; pulse parameters such as pulse duration, pulse pressure, and pulse injection orifice size; woven cloth mesh configuration; the technique for clamping the bag to the support; and similar structural, fluid, and control parameters. The demonstration effort included both tests to prove this concept in a real application and a systems analysis to show commercial feasibility of the ceramic filtration approach for hot gas cleanup in PFBC's. 12 references, 57 figures, 23 tables.

  5. Gas-Liquid Mass Transfer in a Slurry Bubble Column Reactor under High Temperature andHigh Pressure

    Institute of Scientific and Technical Information of China (English)

    杨卫国; 王金福; 金涌

    2001-01-01

    The gas-liquid mass transfer of H2 and CO in a high temperature and high-pressure three-phase slurry bubble column reactor is studied. The gas-liquid volumetric mass transfer coefficients kLa are obtained by measuring the dissolution rate of H2 and CO. The influences of the main operation conditions, such as temperature, pressure,superficial gas velocity and solid concentration, are studied systematically. Two empirical correlations are proposed to predict kLa values for H2 and CO in liquid paraffln/solid particles slurry bubble column reactors.

  6. Design of Highly Selective Gas Sensors via Physicochemical Modification of Oxide Nanowires: Overview

    Directory of Open Access Journals (Sweden)

    Hyung-Sik Woo

    2016-09-01

    Full Text Available Strategies for the enhancement of gas sensing properties, and specifically the improvement of gas selectivity of metal oxide semiconductor nanowire (NW networks grown by chemical vapor deposition and thermal evaporation, are reviewed. Highly crystalline NWs grown by vapor-phase routes have various advantages, and thus have been applied in the field of gas sensors over the years. In particular, n-type NWs such as SnO2, ZnO, and In2O3 are widely studied because of their simple synthetic preparation and high gas response. However, due to their usually high responses to C2H5OH and NO2, the selective detection of other harmful and toxic gases using oxide NWs remains a challenging issue. Various strategies—such as doping/loading of noble metals, decorating/doping of catalytic metal oxides, and the formation of core–shell structures—have been explored to enhance gas selectivity and sensitivity, and are discussed herein. Additional methods such as the transformation of n-type into p-type NWs and the formation of catalyst-doped hierarchical structures by branch growth have also proven to be promising for the enhancement of gas selectivity. Accordingly, the physicochemical modification of oxide NWs via various methods provides new strategies to achieve the selective detection of a specific gas, and after further investigations, this approach could pave a new way in the field of NW-based semiconductor-type gas sensors.

  7. Ultrasensitive and highly selective graphene-based single yarn for use in wearable gas sensor.

    Science.gov (United States)

    Yun, Yong Ju; Hong, Won G; Choi, Nak-Jin; Kim, Byung Hoon; Jun, Yongseok; Lee, Hyung-Kun

    2015-06-04

    Electric components based on fibers or textiles have been investigated owing to their potential applications in wearable devices. High performance on response to gas, drape-ability and washing durability are of important for gas sensors based on fiber substrates. In this report, we demonstrate the bendable and washable electronic textile (e-textile) gas sensors composed of reduced graphene oxides (RGOs) using commercially available yarn and molecular glue through an electrostatic self-assembly. The e-textile gas sensor possesses chemical durability to several detergent washing treatments and mechanical stability under 1,000 bending tests at an extreme bending radius of 1 mm as well as a high response to NO2 gas at room temperature with selectivity to other gases such as acetone, ethanol, ethylene, and CO2.

  8. Draft evaluation of the frequency for gas sampling for the high burnup confirmatory data project

    Energy Technology Data Exchange (ETDEWEB)

    Stockman, Christine T. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Alsaed, Halim A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bryan, Charles R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-03-26

    This report fulfills the M3 milestone M3FT-15SN0802041, “Draft Evaluation of the Frequency for Gas Sampling for the High Burn-up Storage Demonstration Project” under Work Package FT-15SN080204, “ST Field Demonstration Support – SNL”. This report provides a technically based gas sampling frequency strategy for the High Burnup (HBU) Confirmatory Data Project. The evaluation of: 1) the types and magnitudes of gases that could be present in the project cask and, 2) the degradation mechanisms that could change gas compositions culminates in an adaptive gas sampling frequency strategy. This adaptive strategy is compared against the sampling frequency that has been developed based on operational considerations. Gas sampling will provide information on the presence of residual water (and byproducts associated with its reactions and decomposition) and breach of cladding, which could inform the decision of when to open the project cask.

  9. Ultrasensitive and Highly Selective Graphene-Based Single Yarn for Use in Wearable Gas Sensor

    Science.gov (United States)

    Ju Yun, Yong; Hong, Won G.; Choi, Nak-Jin; Hoon Kim, Byung; Jun, Yongseok; Lee, Hyung-Kun

    2015-06-01

    Electric components based on fibers or textiles have been investigated owing to their potential applications in wearable devices. High performance on response to gas, drape-ability and washing durability are of important for gas sensors based on fiber substrates. In this report, we demonstrate the bendable and washable electronic textile (e-textile) gas sensors composed of reduced graphene oxides (RGOs) using commercially available yarn and molecular glue through an electrostatic self-assembly. The e-textile gas sensor possesses chemical durability to several detergent washing treatments and mechanical stability under 1,000 bending tests at an extreme bending radius of 1 mm as well as a high response to NO2 gas at room temperature with selectivity to other gases such as acetone, ethanol, ethylene, and CO2.

  10. High-Intensity Femtosecond Laser Interaction with Rare Gas Clusters

    Institute of Scientific and Technical Information of China (English)

    林亚风; 钟钦; 曾淳; 陈哲

    2001-01-01

    With a 45 fs multiterawatt 790 nm laser system and jets of argon and krypton atomic clusters, a study of the interaction of fs intense laser pulses with large size rare gas dusters was conducted. The maximum laser intensity of about 7 × 1016 W/cm2 and dusters composed of thousands of atoms which were determined through Rayleigh scattering measurements were involved inthe experiments. On the one hand, the results indicate that the interaction is strongly cluster size dependent. The stronger the interaction, the larger the clusters are. On the other hand, a saturation followed by a drop of the energy of ions ejected from the interaction will occur when the laser intensity exceeds a definite value for clusters of a certain size.

  11. Gas phase toluene isopropylation over high silica mordenite

    Indian Academy of Sciences (India)

    Sreedevi Upadhyayula

    2010-07-01

    Mordenite (HM) catalysts with three different Si/Al ratios were compared for their activity and selectivities in gas phase toluene isopropylation with isopropanol. Catalyst with Si/Al ratio 44.9 offered better cumene selectivity, hence, it was chosen for detailed kinetic investigations. The influence of various process parameters like temperature, time-on-stream, weight hourly space velocity (WHSV), reactant mole ratio on this catalyst activity are discussed. The cymene selectivity was found to increase with reaction temperature and passed through a maximum at 473 K. The deactivation with time-onstream is almost negligible. Lower isopropyl alcohol concentration in the feed improved cymene selectivity. The conversion and selectivity to cymenes were compared with those of the large pore beta catalyst. The rate constant and activation energy were found to be 7.34 m3/kg h and 41.84 kJ/mol, respectively using homogeneous kinetic model.

  12. Thermal barrier coating on high temperature industrial gas turbine engines

    Science.gov (United States)

    Carlson, N.; Stoner, B. L.

    1977-01-01

    The thermal barrier coating used was a yttria stabilized zirconia material with a NiCrAlY undercoat, and the base engine used to establish improvements was the P&WA FT50A-4 industrial gas turbine engine. The design benefits of thermal barrier coatings include simplified cooling schemes and the use of conventional alloys in the engine hot section. Cooling flow reductions and improved heating rates achieved with thermal barrier coating result in improved performance. Economic benefits include reduced power production costs and reduced fuel consumption. Over the 30,000 hour life of the thermal barrier coated parts, fuel savings equivalent to $5 million are projected and specific power (megawatts/mass of engine airflow) improvements on the order of 13% are estimated.

  13. Flexible High Energy Lidar Transmitter for Remote Gas and Wind Sensing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Fibertek proposes a high energy and flexible operation 1570 nm pulsed lidar transmitter for airborne and space-based remote CO2 gas and doppler wind sensing. The...

  14. Miniaturized MEMS-Based Gas Chromatograph for High Inertial Loads Associated with Planetary Missions Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Thorleaf Research, Inc. proposes to develop a rugged, miniaturized, low power MEMS-based gas chromatograph (GC) capable of handling the high inertial loads...

  15. High performance mini-gas chromatography-flame ionization detector system based on micro gas chromatography column

    Science.gov (United States)

    Zhu, Xiaofeng; Sun, Jianhai; Ning, Zhanwu; Zhang, Yanni; Liu, Jinhua

    2016-04-01

    Monitoring Volatile organic compounds (VOCs) was a very important measure for preventing environmental pollution, therefore, a mini gas chromatography (GC) flame ionization detector (FID) system integrated with a mini H2 generator and a micro GC column was developed for environmental VOC monitoring. In addition, the mini H2 generator was able to make the system explode from far away due to the abandoned use of a high pressure H2 source. The experimental result indicates that the fabricated mini GC FID system demonstrated high repeatability and very good linear response, and was able to rapidly monitor complicated environmental VOC samples.

  16. Long-term outcome of highly myopic foveoschisis treated by vitrectomy with or without gas tamponade.

    Science.gov (United States)

    Yun, Li-Na; Xing, Yi-Qiao

    2017-01-01

    To evaluate the long-term safety and efficacy of vitrectomy and internal limiting membrane (ILM) peeling with or without gas tamponade for highly myopic foveoschisis. We performed an open-label, observer-blinded clinical trial of 85 patients with myopic foveoschisis between 2000 and 2012. Patients were randomly allocated to one of two groups, those who received vitrectomy and ILM peeling without gas tamponade (no-gas group) or those who with gas tamponade (gas group) and follow up at least 5y. Visual acuity of gas group improved from 0.82±0.33 to 0.79±0.73 in 6mo, improved to 0.71±0.67 in 1y and within this range in the following 4y. Visual acuity of no-gas group improved from 0.81±0.46 to 0.78±0.66 in 6mo, improved to 0.70±0.65 in 1y. The finial visual acuity of two groups were significantly increased compared with the baseline (Ptamponade appears to be as effective in the treatment of myopic foveoschisis as vitrectomy and ILM with gas tamponade. However, eyes treated with no-gas tamponade showed more rapid resolution of myopic foveoschisis.

  17. Representative equations for the thermodynamic and transport properties of fluids near the gas-liquid critical point

    Science.gov (United States)

    Sengers, J. V.; Basu, R. S.; Sengers, J. M. H. L.

    1981-01-01

    A survey is presented of representative equations for various thermophysical properties of fluids in the critical region. Representative equations for the transport properties are included. Semi-empirical modifications of the theoretically predicted asymtotic critical behavior that yield simple and practical representations of the fluid properties in the critical region are emphasized.

  18. [High flow nasal cannula in infants: Experience in a critical patient unit].

    Science.gov (United States)

    Wegner A, Adriana; Cespedes F, Pamela; Godoy M, María Loreto; Erices B, Pedro; Urrutia C, Luis; Venthur U, Carina; Labbé C, Marcela; Riquelme M, Hugo; Sanchez J, Cecilia; Vera V, Waldo; Wood V, David; Contreras C, Juan Carlos; Urrutia S, Efren

    2015-01-01

    The high flow nasal cannula (HFNC) is a method of respiratory support that is increasingly being used in paediatrics due to its results and safety. To determine the efficacy of HFNC, as well as to evaluate the factors related to its failure and complications associated with its use in infants. An analysis was performed on the demographic, clinical, blood gas, and radiological data, as well as the complications of patients connected to a HFNC in a critical care unit between June 2012 and September 2014. A comparison was made between the patients who failed and those who responded to HFNC. A failure was considered as the need for further respiratory support during the first 48hours of connection. The Kolmogorov Smirnov, Mann-Whitney U, chi squared and the Exact Fisher test were used, as well as correlations and a binary logistic regression model for P≤.05. The study included 109 patients, with a median age and weight: 1 month (0.2-20 months) and 3.7kg (2-10kg); 95 percentile: 3.7 months and 5.7kg, respectively. The most frequent diagnosis and radiological pattern was bronchiolitis (53.2%) and interstitial infiltration (56%). Around 70.6% responded. There was a significant difference between failure and response in the diagnosis (P=.013), radiography (P=018), connection context (P<.0001), pCO2 (median 40.7mmHg [15.4-67 mmHg] versus 47.3mmHg [28.6-71.3mmHg], P=.004) and hours on HFNC (median 60.75hrs [5-621.5 hrs] versus 10.5hrs [1-29 hrs], P<.0001). The OR of the PCO2 ≥ 55mmHg for failure was 2.97 (95% CI; 1.08-8.17; P=.035). No patient died and no complications were recorded. The percentage success observed was similar to that published. In this sample, the failure of HFNC was only associated with an initial pCO2 ≥ 55mmHg. On there being no complications reported as regards it use, it is considered safe, although a randomised, controlled, multicentre study is required to compare and contrast these results. Copyright © 2015 Sociedad Chilena de Pediatr

  19. Critical currents and superconductivity ferromagnetism coexistence in high-Tc oxides

    CERN Document Server

    Khene, Samir

    2016-01-01

    The book comprises six chapters which deal with the critical currents and the ferromagnetism-superconductivity coexistence in high-Tc oxides. It begins by gathering key data for superconducting state and the fundamental properties of the conventional superconductors, followed by a recap of the basic theories of superconductivity. It then discusses the differences introduced by the structural anisotropy on the Ginzburg-Landau approach and the Lawrence-Doniach model before addressing the dynamics of vortices and the ferromagnetism-superconductivity coexistence in high-Tc oxides, and provides an outline of the pinning phenomena of vortices in these materials, in particular the pinning of vortices by the spins. It elucidates the methods to improve the properties of superconducting materials for industrial applications. This optimization aims at obtaining critical temperatures and densities of critical currents at the maximum level possible. Whereas the primary objective is the basic mechanisms pushing the superco...

  20. Experimental study on hydrodynamic behaviors of high-speed gas jets in still water

    Institute of Scientific and Technical Information of China (English)

    Zhenqing Dai; Boyi Wang; Longxi Qi; Honghui Shi

    2006-01-01

    The present paper describes experimental investigation on the flow pattern and hydrodynamic effect of underwater gas jets from supersonic and sonic nozzles operated in correct- and imperfect expansion conditions. The flow visualizations show that jetting is the flow regime for the submerged gas injection at a high speed in the parameter range under consideration. The obtained results indicate that high-speed gas jets in still water induce large pressure pulsations upstream of the nozzle exit and the presence of shock-cell structure in the over-and under-expanded jets leads to an increase in the intensity of the jet-induced hydrodynamic pressure.

  1. Biological production of methane from coal synthesis gas under high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Ko, C.W.; Vega, J.L.; Barik, S.; Clausen, E.C.; Gaddy, J.L.

    1987-01-01

    Carbon monoxide, hydrogen and carbon dioxide, the major components of coal synthesis gas, may be converted to methane by the action of anaerobic bacteria. Both pure and mixed cultures have been developed to carry out the water-gas shift and methanation reactions. Reaction rates are severely limited by mass-transfer of these gaseous substrates. Research studies show that increased pressure results in a proportionate increase in reaction rate. This paper examines the effects of high pressure on the performance of organisms, such as P. productus and Methanothrix, in converting coal gas into methane. The effects of carbon monoxide inhibition and high pressure are presented and discussed.

  2. Gas-Liquid Mass Transfer in a Slurry Bubble Column Reactor under High Temperature and

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The gas-liquid mass transfer of H2 and CO in a high temperature and high-pressure three-phase slurry bubble column reactor is studied. The gas-liquid volumetric mass transfer coefficients κLα are obtained by measuring the dissolution rate of H2 and CO. The influences of the main operation conditions, such as temperature, pressure, superficial gas velocity and solid concentration, are studied systematically. Two empirical correlations are proposed to predict κLα values for H2 and CO in liquid paraffin/solid particles slurry bubble column reactors.

  3. THE RESEARCH ON HIGH-SPEED GAS JET OF ROCKET NOZZLE UNDERWATER

    Institute of Scientific and Technical Information of China (English)

    XU Xiao-qiang; DENG Jian; REN An-lu; LU Chuan-jing

    2005-01-01

    In this paper, a study of the high-speed gas jet of a rocket nozzle underwater was carried out using commercially available CFD software FLUENT with it's user-defined-function.The volume of fluid technique based on finite volume method was adopted to solve the time-dependent multiphase flow including a compressible phase, and the PISO algorithm was included.The computed results show that this problem was calculated successfully.The gas bubble behind the nozzle, and the wave structure existing in highly compressed gas in water were captured accurately.

  4. Abnormal combustion caused by lubricating oil in high BMEP gas engines

    Energy Technology Data Exchange (ETDEWEB)

    Yasueda, Shinji [Kyushu Univ. (Japan). GDEC Gas and Diesel Engine; Takasaki, Koji; Tajima, Hiroshi [Kyushu Univ. (Japan). Lab. of Engine and Combustion (ECO)

    2013-05-15

    In recent years, abnormal combustion with high peak firing pressure has been experienced on gas engines with high brake mean effective pressures. The abnormality is detected not as pre-ignition but as knocking. Research, including visualisation tests on a single-cylinder engine, has confirmed the phenomenon to be pre-ignition caused by the auto-ignition of in-cylinder lubricant, causing cyclical variations of peak firing pressure on premix combustion gas engines. (orig.)

  5. Ultra-microporous triptycene-based polyimide membranes for high-performance gas separation

    KAUST Repository

    Ghanem, Bader

    2014-03-11

    A highly permeable and highly selective polyimide of intrinsic microporosity is prepared using a 9,10-diisopropyl-triptycene contortion center. The three-dimensionality and shape-persistence of triptycene afford exceptional sieving-based gas separation performance transcending the latest permeability/selectivity trade-offs for industrial gas separations involving oxygen and hydrogen. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Integrated development and industrial application of high sour natural gas purification technology

    Institute of Scientific and Technical Information of China (English)

    Sun Lili

    2013-01-01

    Aiming at acute characteristics of flammability,explosibility,causticity and leakiness of high sour nat-ural gas,giving full consideration to local natural conditions in Sichuan Province and starting with purification pro-cess,the paper analyzed process configurations,energy utilization and conservation,safety and environment pro-tection measures. The integrated technology and engineering scheme for high sour natural gas purification was es-tablished and successfully used in industrial application.

  7. Validation of SCALE for High Temperature Gas-Cooled Reactors Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ilas, Germina [ORNL; Ilas, Dan [ORNL; Kelly, Ryan P [ORNL; Sunny, Eva E [ORNL

    2012-08-01

    This report documents verification and validation studies carried out to assess the performance of the SCALE code system methods and nuclear data for modeling and analysis of High Temperature Gas-Cooled Reactor (HTGR) configurations. Validation data were available from the International Handbook of Evaluated Reactor Physics Benchmark Experiments (IRPhE Handbook), prepared by the International Reactor Physics Experiment Evaluation Project, for two different HTGR designs: prismatic and pebble bed. SCALE models have been developed for HTTR, a prismatic fuel design reactor operated in Japan and HTR-10, a pebble bed reactor operated in China. The models were based on benchmark specifications included in the 2009, 2010, and 2011 releases of the IRPhE Handbook. SCALE models for the HTR-PROTEUS pebble bed configuration at the PROTEUS critical facility in Switzerland have also been developed, based on benchmark specifications included in a 2009 IRPhE draft benchmark. The development of the SCALE models has involved a series of investigations to identify particular issues associated with modeling the physics of HTGRs and to understand and quantify the effect of particular modeling assumptions on calculation-to-experiment comparisons.

  8. Metal based gas diffusion layers for enhanced fuel cell performance at high current densities

    Science.gov (United States)

    Hussain, Nabeel; Van Steen, Eric; Tanaka, Shiro; Levecque, Pieter

    2017-01-01

    The gas diffusion layer strongly influences the performance and durability of polymer electrolyte fuel cells. A major drawback of current carbon fiber based GDLs is the non-controlled variation in porosity resulting in a random micro-structure. Moreover, when subjected to compression these materials show significant reduction in porosity and permeability leading to water management problems and mass transfer losses within the fuel cell. This study investigated the use of uniform perforated metal sheets as GDLs in conjunction with microchannel flowfields. A metal sheet design with a pitch of 110 μm and a hole diameter of 60 μm in combination with an MPL showed superior performance in the high current density region compared to a commercially available carbon paper based GDL in a single cell environment. Fuel cell testing with different oxidants (air, heliox and oxygen) indicate that the metal sheet offers both superior diffusion and reduced flooding in comparison to the carbon based GDL. The presence of the MPL has been found to be critical to the functionality of the metal sheet suggesting that the MPL design may represent an important optimisation parameter for further improvements in performance.

  9. Diffusion of dilute gas in arrays of randomly distributed, vertically aligned, high-aspect-ratio cylinders

    Science.gov (United States)

    Guerra, Carlos

    2017-01-01

    In this work we modelled the diffusive transport of a dilute gas along arrays of randomly distributed, vertically aligned nanocylinders (nanotubes or nanowires) as opposed to gas diffusion in long pores, which is described by the well-known Knudsen theory. Analytical expressions for (i) the gas diffusion coefficient inside such arrays, (ii) the time between collisions of molecules with the nanocylinder walls (mean time of flight), (iii) the surface impingement rate, and (iv) the Knudsen number of such a system were rigidly derived based on a random-walk model of a molecule that undergoes memoryless, diffusive reflections from nanocylinder walls assuming the molecular regime of gas transport. It can be specifically shown that the gas diffusion coefficient inside such arrays is inversely proportional to the areal density of cylinders and their mean diameter. An example calculation of a diffusion coefficient is delivered for a system of titanium isopropoxide molecules diffusing between vertically aligned carbon nanotubes. Our findings are important for the correct modelling and optimisation of gas-based deposition techniques, such as atomic layer deposition or chemical vapour deposition, frequently used for surface functionalisation of high-aspect-ratio nanocylinder arrays in solar cells and energy storage applications. Furthermore, gas sensing devices with high-aspect-ratio nanocylinder arrays and the growth of vertically aligned carbon nanotubes need the fundamental understanding and precise modelling of gas transport to optimise such processes. PMID:28144565

  10. Critical Temperature Associated to Symmetry Breaking of Klein--Gordon fields versus Condensation Temperature in a Weakly interacting Bose--Einstein Gas

    CERN Document Server

    Castellanos, Elias

    2012-01-01

    We deduce the relation between the critical temperature associated to the U(1) symmetry breaking of scalar fields with one--loop correction potential immersed in a thermal bath, and the condensation temperature of the aforementioned system in the thermodynamic limit, within the semiclassical approximation for a weakly interacting bosonic gas with a positive coupling constant. Additionally, we show that the shift in the condensation temperature caused by the coupling constant is independent of the thermal bath.

  11. Critical Race Theory, Hip Hop, and "Huck Finn": Narrative Inquiry in a High School English Classroom

    Science.gov (United States)

    Martin, Jennifer L.

    2014-01-01

    This study explores the impact of reading "Huckleberry Finn" through the lens of critical race theory for both teacher and students in a racially diverse urban high school environment. The teacher/researcher used narrative inquiry and creative non-fiction to examine student language usage, white privilege (including her own), and student…

  12. An Examination of Critical Thinking Skills in High School Choral Rehearsals

    Science.gov (United States)

    Garrett, Matthew L.

    2013-01-01

    The purpose of this study was to examine the relationship between time spent in nonperformance and critical thinking activities in high school choral rehearsals. Eighteen rehearsal observations were collected from public school music programs. Observed rehearsal behaviors were coded into three categories of nonperformance activity: lower-order…

  13. Critical phenomena in ethylbenzene oxidation in acetic acid solution at high cobalt(II) concentrations

    NARCIS (Netherlands)

    Gavrichkov, AA; Zakharov, [No Value

    2005-01-01

    Critical phenomena in ethylbenzene oxidation in an acetic acid solution at high cobalt(ill) concentrations (from 0.01 to 0.2 mol L-1) were studied at 60-90 degrees C by the gasometric (O-2 absorption), spectrophotometric (Co-III accumulation), and chemiluminescence (relative concentration of radical

  14. The Development and Validation of a Mechanical Critical Thinking Scale for High School Students

    Science.gov (United States)

    Yu, Kuang-Chao; Lin, Kuen-Yi; Chang, Shu-Fen

    2017-01-01

    The purpose of this study was to develop a mechanical critical thinking scale for high school students. A stratified random sampling method was used to establish the norms. After pre-tests and item analysis, the scale was determined to have five subtest sections (i.e., recognition of assumptions, induction, deduction, interpretation, and…

  15. Picturing Obama: Race, High School Students and a Critical Methodology of the Visual

    Science.gov (United States)

    Smith, William L.

    2017-01-01

    I draw on methodological findings from a case study on how high school students of color make sense of dominant narratives of race and politics in the Obama American Era. Incorporating literature from critical race theory, visual research methods, and the writings of cultural scholar Stuart Hall, I draw conclusions from this inquiry project as a…

  16. The Development and Validation of a Mechanical Critical Thinking Scale for High School Students

    Science.gov (United States)

    Yu, Kuang-Chao; Lin, Kuen-Yi; Chang, Shu-Fen

    2017-01-01

    The purpose of this study was to develop a mechanical critical thinking scale for high school students. A stratified random sampling method was used to establish the norms. After pre-tests and item analysis, the scale was determined to have five subtest sections (i.e., recognition of assumptions, induction, deduction, interpretation, and…

  17. Assessing Critical Thinking in Middle and High Schools: Meeting the Common Core

    Science.gov (United States)

    Stobaugh, Rebecca

    2013-01-01

    This practical, very effective resource helps middle and high school teachers and curriculum leaders develop the skills to design instructional tasks and assessments that engage students in higher-level critical thinking, as recommended by the Common Core State Standards. Real examples of formative and summative assessments from a variety of…

  18. AC losses in sintered high-temperature superconductors. Dependence on frequency and intergranular lower critical field

    Energy Technology Data Exchange (ETDEWEB)

    Lofland, S.; Huang, M.X.; Bhagat, S.M. (Dept. of Physics and Center for Superconductivity Research, Univ. of Maryland, College Park (United States))

    1992-12-10

    The intergranular AC susceptibility loss peak in high-Tc superconductors is measured as a function of frequency and field amplitude. The variation of peak temperature with frequency is strongly influenced by the grain size. For large grains, the maximum loss increases with field amplitude. This is ascribed to a non-zero intergranular lower critical field H[sub cl]. (orig.).

  19. An Examination of Critical Thinking Skills in High School Choral Rehearsals

    Science.gov (United States)

    Garrett, Matthew L.

    2013-01-01

    The purpose of this study was to examine the relationship between time spent in nonperformance and critical thinking activities in high school choral rehearsals. Eighteen rehearsal observations were collected from public school music programs. Observed rehearsal behaviors were coded into three categories of nonperformance activity: lower-order…

  20. High temperature strain gage technology for gas turbine engines

    Science.gov (United States)

    Fichtel, Edward J.; McDaniel, Amos D.

    1994-08-01

    This report summarizes the results of a six month study that addressed specific issues to transfer the Pd-13Cr static strain sensor to a gas turbine engine environment. The application issues that were addressed include: (1) evaluation of a miniature, variable potentiometer for use as the ballast resistor, in conjunction with a conventional strain gage signal conditioning unit; (2) evaluation of a metal sheathed, platinum conductor leadwire assembly for use with the three-wire sensor; and (3) subjecting the sensor to dynamic strain cyclic testing to determine fatigue characteristics. Results indicate a useful static strain gage system at all temperature levels up to 1350 F. The fatigue characteristics also appear to be very promising, indicating a potential use in dynamic strain measurement applications. The procedure, set-up, and data for all tests are presented in this report. This report also discusses the specific strain gage installation technique for the Pd-13Cr gage because of its potential impact on the quality of the output data.

  1. Metal sorbents for high temperature mercury capture from fuel gas

    Energy Technology Data Exchange (ETDEWEB)

    Stephen Poulston; Evan J. Granite; Henry W. Pennline; Christina R. Myers; Dennis P. Stanko; Hugh Hamilton; Liz Rowsell; Andrew W.J. Smith; Thomas Ilkenhans; Wilson Chu [Johnson Matthey Technology Centre, Reading (United Kingdom)

    2007-07-01

    We have determined the effect of a pre-sulphiding treatment on the Hg removal capacities of Pt and Pd supported on alumina at a range of different metal loadings from 2 to 9wt% using Hg vapour in a simulated fuel gas feed. In the temperature range studied (204-288{sup o}C) Pd proved far superior to Pt for Hg removal and the sulphur pre-treatment led to a considerable increase in the Hg adsorption capacity. The Hg removal capacity for Pd increased with metal loading though decreased with sorbent temperature. A shift in the 2 Theta position of the Pd XRD diffraction peak from 82.1 to 79.5{sup o} after Hg adsorption at 204{sup o}C in the absence of a sulphur pre-treatment was consistent with the formation of a solid solution of Hg in Pd, with the sulphur pre-treatment the Pd related XRD peaks occur at even lower 2 Theta position suggesting a different Pd-Hg phase is formed. 5 refs., 1 tab.

  2. Highly covariant quantum lattice gas model of the Dirac equation

    CERN Document Server

    Yepez, Jeffrey

    2011-01-01

    We revisit the quantum lattice gas model of a spinor quantum field theory-the smallest scale particle dynamics is partitioned into unitary collide and stream operations. The construction is covariant (on all scales down to a small length {\\ell} and small time {\\tau} = c {\\ell}) with respect to Lorentz transformations. The mass m and momentum p of the modeled Dirac particle depend on {\\ell} according to newfound relations m = mo cos (2{\\pi}{\\ell}/{\\lambda}) and p = (h/2{\\pi}{\\ell}) sin(2{\\pi}{\\ell}/{\\lambda}), respectively, where {\\lambda} is the Compton wavelength of the modeled particle. These relations represent departures from a relativistically invariant mass and the de Broglie relation-when taken as quantifying numerical errors the model is physically accurate when {\\ell} {\\ll} {\\lambda}. Calculating the vacuum energy in the special case of a massless spinor field, we find that it vanishes (or can have a small positive value) for a sufficiently large wave number cutoff. This is a marked departure from th...

  3. High power fiber lasers in geothermal, oil and gas

    Science.gov (United States)

    Zediker, Mark S.

    2014-03-01

    The subject of this paper is the requirements, design, fabrication, and testing of a prototype laser rock drilling system capable of penetrating even the hardest rocks found deep in the earth. The Oil and Gas industry still uses many of the technologies that were in use at the turn of the 19th century. The drilling industry started with a great innovation with the introduction of the tri-cone bit by Howard Hughes in 1908. Since then, the industry has modified and optimized drilling systems with incremental advancement in the ability to penetrate hard crystalline rock structures. Most oil producing reservoirs are located in or below relatively soft rock formations, however, with the growing need for energy, oil companies are now attempting to drill through very hard surface rock and deep ocean formations with limited success. This paper will discuss the types of laser suitable for this application, the requirements for putting lasers in the field, the technology needed to support this laser application and the test results of components developed specifically by Foro Energy for the drilling application.

  4. High bias gas flows increase lung injury in the ventilated preterm lamb.

    Directory of Open Access Journals (Sweden)

    Katinka P Bach

    Full Text Available BACKGROUND: Mechanical ventilation of preterm babies increases survival but can also cause ventilator-induced lung injury (VILI, leading to the development of bronchopulmonary dysplasia (BPD. It is not known whether shear stress injury from gases flowing into the preterm lung during ventilation contributes to VILI. METHODS: Preterm lambs of 131 days' gestation (term = 147 d were ventilated for 2 hours with a bias gas flow of 8 L/min (n = 13, 18 L/min (n = 12 or 28 L/min (n = 14. Physiological parameters were measured continuously and lung injury was assessed by measuring mRNA expression of early injury response genes and by histological analysis. Control lung tissue was collected from unventilated age-matched fetuses. Data were analysed by ANOVA with a Tukey post-hoc test when appropriate. RESULTS: High bias gas flows resulted in higher ventilator pressures, shorter inflation times and decreased ventilator efficiency. The rate of rise of inspiratory gas flow was greatest, and pulmonary mRNA levels of the injury markers, EGR1 and CTGF, were highest in lambs ventilated with bias gas flows of 18 L/min. High bias gas flows resulted in increased cellular proliferation and abnormal deposition of elastin, collagen and myofibroblasts in the lung. CONCLUSIONS: High ventilator bias gas flows resulted in increased lung injury, with up-regulation of acute early response genes and increased histological lung injury. Bias gas flows may, therefore, contribute to VILI and BPD.

  5. High Bias Gas Flows Increase Lung Injury in the Ventilated Preterm Lamb

    Science.gov (United States)

    Bach, Katinka P.; Kuschel, Carl A.; Hooper, Stuart B.; Bertram, Jean; McKnight, Sue; Peachey, Shirley E.; Zahra, Valerie A.; Flecknoe, Sharon J.; Oliver, Mark H.; Wallace, Megan J.; Bloomfield, Frank H.

    2012-01-01

    Background Mechanical ventilation of preterm babies increases survival but can also cause ventilator-induced lung injury (VILI), leading to the development of bronchopulmonary dysplasia (BPD). It is not known whether shear stress injury from gases flowing into the preterm lung during ventilation contributes to VILI. Methods Preterm lambs of 131 days’ gestation (term = 147 d) were ventilated for 2 hours with a bias gas flow of 8 L/min (n = 13), 18 L/min (n = 12) or 28 L/min (n = 14). Physiological parameters were measured continuously and lung injury was assessed by measuring mRNA expression of early injury response genes and by histological analysis. Control lung tissue was collected from unventilated age-matched fetuses. Data were analysed by ANOVA with a Tukey post-hoc test when appropriate. Results High bias gas flows resulted in higher ventilator pressures, shorter inflation times and decreased ventilator efficiency. The rate of rise of inspiratory gas flow was greatest, and pulmonary mRNA levels of the injury markers, EGR1 and CTGF, were highest in lambs ventilated with bias gas flows of 18 L/min. High bias gas flows resulted in increased cellular proliferation and abnormal deposition of elastin, collagen and myofibroblasts in the lung. Conclusions High ventilator bias gas flows resulted in increased lung injury, with up-regulation of acute early response genes and increased histological lung injury. Bias gas flows may, therefore, contribute to VILI and BPD. PMID:23056572

  6. Numerical simulation of high pressure release and dispersion of hydrogen into air with real gas model

    Science.gov (United States)

    Khaksarfard, R.; Kameshki, M. R.; Paraschivoiu, M.

    2010-06-01

    Hydrogen is a renewable and clean source of energy, and it is a good replacement for the current fossil fuels. Nevertheless, hydrogen should be stored in high-pressure reservoirs to have sufficient energy. An in-house code is developed to numerically simulate the release of hydrogen from a high-pressure tank into ambient air with more accuracy. Real gas models are used to simulate the flow since high-pressure hydrogen deviates from ideal gas law. Beattie-Bridgeman and Abel Noble equations are applied as real gas equation of state. A transport equation is added to the code to calculate the concentration of the hydrogen-air mixture after release. The uniqueness of the code is to simulate hydrogen in air release with the real gas model. Initial tank pressures of up to 70 MPa are simulated.

  7. Enhanced electron yield from a laser-plasma accelerator using high-Z gas jet targets

    CERN Document Server

    Mirzaie, Mohammad; Li, Song; Sokollik, Thomas; He, Fei; Cheng, Ya; Sheng, Zhengming; Zhang, Jie

    2014-01-01

    An investigation of the multi-hundred MeV electron beam yield (charge) form helium, nitrogen, neon and argon gas jet plasmas in a laser-plasma wakefield acceleration experiment was carried out. The charge measurement has been made via imaging the electron beam intensity profile on a fluorescent screen into a 14-bit charge coupled device (CCD) which was cross-calibrated with nondestructive electronics-based method. Within given laser and plasma parameters, we found that laser-driven low Z- gas jet targets generate high-quality and well-collimated electron beams with reasonable yields at the level of 10-100 pC. On the other hand, filamentary electron beams which were observed from high-Z gas jets at higher densities reached much higher yield. Evidences for cluster formation were clearly observed in high-Z gases, especially in the argon gas jet target where we received the highest yield of ~ 3 nC

  8. Coating synthesis on dielectric substrates assisted by pulsed beams of high-energy gas atoms

    Science.gov (United States)

    Grigoriev, S. N.; Melnik, Yu A.; Metel, A. S.

    2017-05-01

    Titanium nitride and aluminum nitride coatings have been deposited on glass and aluminum oxide substrates in a flow of metal atoms accompanied by high-energy gas atoms. The metal atoms are produced due to sputtering of a flat rectangular magnetron target. The gas atoms with energy up to 25 keV are produced due to charge exchange collisions of ions extracted from the magnetron discharge plasma and accelerated by high-voltage pulses applied to a flat grid parallel to the target. The metal atoms pass through the grid and deposit on the substrate. Conjunction of their trajectories with those of gas atoms bombarding the growing coating enables the coating synthesis on complex-shape dielectric products planetary rotating inside the vacuum chamber. Mixing high-energy gas atoms of the coating and substrate atoms substantially improves the coating adhesion.

  9. Analysis of Highly Wind Power Integrated Power System model performance during Critical Weather conditions

    DEFF Research Database (Denmark)

    Basit, Abdul; Hansen, Anca Daniela; Sørensen, Poul Ejnar

    2014-01-01

    . For this purpose, the power system model has been developed that represents the relevant dynamic features of power plants and compensates for power imbalances caused by the forecasting error during critical weather conditions. The regulating power plan, as an input time series for the developed power system model......Secure power system operation of a highly wind power integrated power system is always at risk during critical weather conditions, e.g. in extreme high winds. The risk is even higher when 50% of the total electricity consumption has to be supplied by wind power, as the case for the future Danish...... power system in 2020. This paper analyses and compares the performance of the future Danish power system during extreme wind speeds, where wind power plants are either controlled through a traditional High Wind Shut Down storm controller or a new High Wind Extended Production storm controller...

  10. Gas Hydrate Stability at Low Temperatures and High Pressures with Applications to Mars and Europa

    Science.gov (United States)

    Marion, G. M.; Kargel, J. S.; Catling, D. C.

    2004-01-01

    Gas hydrates are implicated in the geochemical evolution of both Mars and Europa [1- 3]. Most models developed for gas hydrate chemistry are based on the statistical thermodynamic model of van der Waals and Platteeuw [4] with subsequent modifications [5-8]. None of these models are, however, state-of-the-art with respect to gas hydrate/electrolyte interactions, which is particularly important for planetary applications where solution chemistry may be very different from terrestrial seawater. The objectives of this work were to add gas (carbon dioxide and methane) hydrate chemistries into an electrolyte model parameterized for low temperatures and high pressures (the FREZCHEM model) and use the model to examine controls on gas hydrate chemistries for Mars and Europa.

  11. Catalytic decomposition of ammonia in a fuel gas at high temperature and pressure

    Energy Technology Data Exchange (ETDEWEB)

    Mojtahedi, W.; Abbasian, J. [Enviropower Inc., Espoo (Finland)

    1995-11-01

    In connection with the purification of fuel gas for gas turbines in the IGCC process to meet NO{sub x} standards and maintain the thermal efficiency of the process, tests were carried out with a 7.5 cm pressurized reactor to decompose ammonia at high temperature (700-900{degree}C) and pressure (2 MPa) using Ni-based catalysts. The effects of temperature, pressure, ammonia concentration and gas residence time were determined. The simulated coal gas composition was varied to allow assessment of the effect of contaminants (sulfur compounds and tars) on the ammonia decomposition efficiency of five catalysts under otherwise identical operating conditions. The results show that two of the catalysts tested are capable of efficiently reducing the concentration of ammonia in the gas. 12 refs., 13 figs.

  12. Enhancing gas-phase reaction in a plasma using high intensity and high power ultrasonic acoustic waves

    DEFF Research Database (Denmark)

    2010-01-01

    is absorbed into said plasma (104), and where a sound pressure level of said generated ultrasonic high intensity and high power acoustic waves (102) is at least substantially 140 dB and where an acoustic power of said generated ultrasonic high intensity and high power acoustic waves (102); is at least......This invention relates to enhancing a gas-phase reaction in a plasma comprising: creating plasma (104) by at least one plasma source (106), and wherein that the method further comprises: generating ultrasonic high intensity and high power acoustic waves (102) having a predetermined amount...... of acoustic energy by at least one ultrasonic high intensity and high power gas-jet acoustic wave generator (101), where said ultrasonic high intensity and high power acoustic waves are directed to propagate towards said plasma (104) so that at least a part of said predetermined amount of acoustic energy...

  13. Control of coupling among three major factors for formation of high-efficiency gas reservoir——A case study on the oolitic beach gas reservoir in Feixianguan Formation in the northeast Sichuan Basin

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Through a case study of the high-efficiency gas reservoir in Feixianguan Formation in the northeast Sichuan Basin, quantitative and semi-quantitative analyses of key elements such as hydrocarbon generation, migration and accumulation, and reservoir evolution as well as their interplay in the critical moment of reservoir formation controlled by the energy field were carried out, by means of numerical modeling of the energy field. It was found that the climax time for Permian hydrocarbon generation was Late Triassic-Early Jurassic and accumulation of oil and gas has resulted in large-scale paleoreservoirs in paleostructural traps in Feixianguan Formation, a process facilitated by fractures connecting the sources. The paleoreservoirs have been turned into high-efficiency gas kitchens due to pyrolysis,which resulted from deep burial at a temperature of 170-210℃ as induced by tremendously thick sedimentation in the foreland basin of Daba Mountain in Late Jurassic-Cretaceous period. Meanwhile,abundant acid gas like H2S produced from thermo-chemical sulfate reduction (TSR) at high temperatures leads to extensive dissolution of dolostone in the paleoreservoirs, which may in turn result in modification of the reservoirs and preservation of the reservoir rock porosity. The present distribution of gas reservoirs was ultimately determined in the processes of adjustment, cooling and decompression of the paleoreservoirs resulting from intense deformation in the front of Daba Mountain during the Himalayan orogeny.

  14. Diffraction line-shapes, Fermi surface nesting, and quantum criticality in antiferromagnetic chromium at high pressure.

    Energy Technology Data Exchange (ETDEWEB)

    Jaramillo, R.; Feng, Y.; Rosenbaum, T. F.; Harvard Univ.; Univ. of Chicago

    2010-05-01

    We explore the behavior of the nested bandstructure of chromium as a function of temperature and pressure to the point where magnetism disappears. X-ray diffraction measurements of the charge order parameter suggest that the nesting condition is maintained at high pressure, where the spin density wave ground state is destabilized by a continuous quantum phase transition. By comparing diffraction line-shapes measured throughout the temperature-pressure phase diagram we are able to identify and describe three regimes: thermal near-critical, weak coupling ground state, and quantum critical.

  15. Field-induced quantum critical route to a Fermi liquid in high-temperature superconductors.

    Science.gov (United States)

    Shibauchi, Takasada; Krusin-Elbaum, Lia; Hasegawa, Masashi; Kasahara, Yuichi; Okazaki, Ryuji; Matsuda, Yuji

    2008-05-20

    In high-transition-temperature (T(c)) superconductivity, charge doping is a natural tuning parameter that takes copper oxides from the antiferromagnet to the superconducting region. In the metallic state above T(c), the standard Landau's Fermi-liquid theory of metals as typified by the temperature squared (T(2)) dependence of resistivity appears to break down. Whether the origin of the non-Fermi-liquid behavior is related to physics specific to the cuprates is a fundamental question still under debate. We uncover a transformation from the non-Fermi-liquid state to a standard Fermi-liquid state driven not by doping but by magnetic field in the overdoped high-T(c) superconductor Tl(2)Ba(2)CuO(6+x). From the c-axis resistivity measured up to 45 T, we show that the Fermi-liquid features appear above a sufficiently high field that decreases linearly with temperature and lands at a quantum critical point near the superconductivity's upper critical field-with the Fermi-liquid coefficient of the T(2) dependence showing a power-law diverging behavior on the approach to the critical point. This field-induced quantum criticality bears a striking resemblance to that in quasi-two-dimensional heavy-Fermion superconductors, suggesting a common underlying spin-related physics in these superconductors with strong electron correlations.

  16. Scaling Studies for High Temperature Test Facility and Modular High Temperature Gas-Cooled Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Richard R. Schult; Paul D. Bayless; Richard W. Johnson; James R. Wolf; Brian Woods

    2012-02-01

    The Oregon State University (OSU) High Temperature Test Facility (HTTF) is an integral experimental facility that will be constructed on the OSU campus in Corvallis, Oregon. The HTTF project was initiated, by the U.S. Nuclear Regulatory Commission (NRC), on September 5, 2008 as Task 4 of the 5-year High Temperature Gas Reactor Cooperative Agreement via NRC Contract 04-08-138. Until August, 2010, when a DOE contract was initiated to fund additional capabilities for the HTTF project, all of the funding support for the HTTF was provided by the NRC via their cooperative agreement. The U.S. Department of Energy (DOE) began their involvement with the HTTF project in late 2009 via the Next Generation Nuclear Plant (NGNP) project. Because the NRC's interests in HTTF experiments were only centered on the depressurized conduction cooldown (DCC) scenario, NGNP involvement focused on expanding the experimental envelope of the HTTF to include steady-state operations and also the pressurized conduction cooldown (PCC).

  17. Critical Current and Stability of MgB$_2$ Twisted-Pair DC Cable Assembly Cooled by Helium Gas

    CERN Document Server

    AUTHOR|(CDS)2069632; Ballarino, Amalia; Yang, Yifeng; Young, Edward Andrew; Bailey, Wendell; Beduz, Carlo

    2013-01-01

    Long length superconducting cables/bus-bars cooled by cryogenic gases such as helium operating over a wider temperature range are a challenging but exciting technical development prospects, with applications ranging from super-grid transmission to future accelerator systems. With limited existing knowledge and previous experiences, the cryogenic stability and quench protection of such cables are crucial research areas because the heat transfer is reduced and temperature gradient increased compared to liquid cryogen cooled cables. V-I measurements on gas-cooled cables over a significant length are an essential step towards a fully cryogenic stabilized cable with adequate quench protection. Prototype twisted-pair cables using high-temperature superconductor and MgB2 tapes have been under development at CERN within the FP7 EuCARD project. Experimental studies have been carried out on a 5-m-long multiple MgB$_2$ cable assembly at different temperatures between 20 and 30 K. The subcables of the assembly showed sim...

  18. High-Resolution Seismic Definition of the Distribution of Gas in the West Svalbard Margin

    Science.gov (United States)

    Minshull, T. A.; Westbrook, G. K.; Marin-Moreno, H.; Marsset, B.; Ker, S.; Sarkar, S.; Vardy, M. E.; Henstock, T.

    2014-12-01

    The widespread presence of gas beneath the seabed west of Svalbard is shown by negative-polarity high-amplitude reflectors (nephars), imaged in high-resolution near-surface and deep-towed seismic reflection data. The principal controls on the presence of gas are the gas hydrate stability zone (GHSZ), from which free gas is generally excluded, and stratigraphic control of permeable layers. A widespread bottom-simulating reflector (BSR) beneath the lower-mid continental slope indicates gas at the base of the GHSZ. The depth of the base of the GHSZ predicted by a numerical model that takes in to account variation in ocean temperature over the past two thousand years, is consistent with the depth of the BSR, even at its shallowest depth, where a steady-state model places base of the GHSZ shallower than the BSR. Similarly, farther up slope, where the BSR loses it coherency, the depths of the shallowest nephars are compatible with the predicted depth of the base of the GHSZ from the time-dependent model, but are about three times deeper than the predicted steady-state depth of the BSR. This approach to defining the limits of the GHSZ is not precise, as it depends upon the presence of gas. In the shallow sediment sequence, which has a high proportion of glacigenic sediments, gas is restricted to a smaller number of permeable units than in the contourite-dominated sequence farther down the continental slope. Where the seabed is shallower than the GHSZ, numerous plumes of methane gas ascend from the seabed, and gas, which has migrated up slope through dipping permeable layers, locally ponds beneath a thin veneer of unconformable glacial and post-glacial sediments on the continental shelf.

  19. A High-Speed Continuous Recording High Flow Gas Sampler for Measuring Methane Emissions from Pneumatic Devices at Oil and Natural Gas Production Facilities

    Science.gov (United States)

    Ferrara, T.; Howard, T. M.

    2016-12-01

    Studies attempting to reconcile facility level emission estimates of sources at oil and gas facilities with basin wide methane flux measurements have had limited success. Pneumatic devices are commonly used at oil and gas production facilities for process control or liquid pumping. These devices are powered by pressurized natural gas from the well, so they are known methane sources at these sites. Pneumatic devices are estimated to contribute 14% to 25% of the total greenhouse gas emissions (GHG) from production facilities. Measurements of pneumatic devices have shown that malfunctioning or poorly maintained control systems may be emitting significantly more methane than currently estimated. Emission inventories for these facilities use emission factors from EPA that are based on pneumatic device measurements made in the early 1990's. Recent studies of methane emissions from production facilities have attempted to measure emissions from pneumatic devices by several different methods. These methods have had limitations including alteration of the system being measured, the inability to distinguish between leaks and venting during normal operation, or insufficient response time to account of the time based emission events. We have developed a high speed recording high flow sampler that is capable of measuring the transient emissions from pneumatic devices. This sampler is based on the well-established high flow measurement technique used in oil and gas for quantifying component leak rates. In this paper we present the results of extensive laboratory controlled release testing. Additionally, test data from several field studies where this sampler has been used to measure pneumatic device emissions will be presented.

  20. Consideration of critically when directly disposing highly enriched spent nuclear fuel in unsaturated tuff: Bounding estimates

    Energy Technology Data Exchange (ETDEWEB)

    Rechard, R.P.; Tierney, M.S.; Sanchez, L.C.; Martell, M.-A.

    1996-05-01

    This report presents one of 2 approaches (bounding calculations) which were used in a 1994 study to examine the possibility of a criticality in a repository. Bounding probabilities, although rough, point to the difficulty of creating conditions under which a critical mass could be assembled (container corrosion, separation of neutron absorbers from fissile material, collapse or precipitation of fissile material) and how significant the geochemical and hydrologic phenomena are. The study could not conceive of a mechanism consistent with conditions under which an atomic explosion could occur. Should a criticality occur in or near a container in the future, boundary consequence calculations showed that fissions from one critical event (<10{sup 20} fissions, if similar to aqueous and metal accidents and experiments) are quite small compared to the amount of fissions represented by the spent fuel itself. If it is assumed that the containers necessary to hold the highly enriched spent fuel went critical once per day for 1 million years, creating an energy release of about 10{sup 20} fissions, the number of fissions equals about 10{sup 28}, which corresponds to only 1% of the fission inventory in a repository containing 70,000 metric tons of heavy metal, the expected size for the proposed repository at Yucca Mountain, Nevada.

  1. Reactor Testing and Qualification: Prioritized High-level Criticality Testing Needs

    Energy Technology Data Exchange (ETDEWEB)

    S. Bragg-Sitton; J. Bess; J. Werner; G. Harms; S. Bailey

    2011-09-01

    Researchers at the Idaho National Laboratory (INL) were tasked with reviewing possible criticality testing needs to support development of the fission surface power system reactor design. Reactor physics testing can provide significant information to aid in development of technologies associated with small, fast spectrum reactors that could be applied for non-terrestrial power systems, leading to eventual system qualification. Several studies have been conducted in recent years to assess the data and analyses required to design and build a space fission power system with high confidence that the system will perform as designed [Marcille, 2004a, 2004b; Weaver, 2007; Parry et al., 2008]. This report will provide a summary of previous critical tests and physics measurements that are potentially applicable to the current reactor design (both those that have been benchmarked and those not yet benchmarked), summarize recent studies of potential nuclear testing needs for space reactor development and their applicability to the current baseline fission surface power (FSP) system design, and provide an overview of a suite of tests (separate effects, sub-critical or critical) that could fill in the information database to improve the accuracy of physics modeling efforts as the FSP design is refined. Some recommendations for tasks that could be completed in the near term are also included. Specific recommendations on critical test configurations will be reserved until after the sensitivity analyses being conducted by Los Alamos National Laboratory (LANL) are completed (due August 2011).

  2. Consideration of critically when directly disposing highly enriched spent nuclear fuel in unsaturated tuff: Bounding estimates

    Energy Technology Data Exchange (ETDEWEB)

    Rechard, R.P.; Tierney, M.S.; Sanchez, L.C.; Martell, M.-A.

    1996-05-01

    This report presents one of 2 approaches (bounding calculations) which were used in a 1994 study to examine the possibility of a criticality in a repository. Bounding probabilities, although rough, point to the difficulty of creating conditions under which a critical mass could be assembled (container corrosion, separation of neutron absorbers from fissile material, collapse or precipitation of fissile material) and how significant the geochemical and hydrologic phenomena are. The study could not conceive of a mechanism consistent with conditions under which an atomic explosion could occur. Should a criticality occur in or near a container in the future, boundary consequence calculations showed that fissions from one critical event (<10{sup 20} fissions, if similar to aqueous and metal accidents and experiments) are quite small compared to the amount of fissions represented by the spent fuel itself. If it is assumed that the containers necessary to hold the highly enriched spent fuel went critical once per day for 1 million years, creating an energy release of about 10{sup 20} fissions, the number of fissions equals about 10{sup 28}, which corresponds to only 1% of the fission inventory in a repository containing 70,000 metric tons of heavy metal, the expected size for the proposed repository at Yucca Mountain, Nevada.

  3. A FORMATIVE ASSESSMENT MODEL OF CRITICAL THINKING IN MATHEMATICS LEARNING IN JUNIOR HIGH SCHOOL

    Directory of Open Access Journals (Sweden)

    R. Rosnawati

    2015-12-01

    Full Text Available This study aims to obtain a valid and reliable formative evaluation model of critical thinking. The method used in this research was the research and development by integrating Borg & Gall's model and  Plomp's development model. The ten steps Borg & Gall’s model were modified into five stages as the stages in the Plomp's model. The subjects in this study were 1,446 students of junior high schools in DIY, 14 mathematics teacher, and six experts. The content validity employed was expert judgment, the empirical validity and reliability used were loading factor, item analysis used PCM 1PL, and the relationship between disposition and critical thinking skill used was structural equation modeling (SEM. The developed formative evaluation model is the procedural model. There are five aspects of critical thinking skill: mathematic reasoning, interpretation, analysis, evaluation, and inference, which entirely composed of 42 items. The validity of the critical thinking skill instruments achieves a significance degree as indicated by the lowest and the highest loading factors of 0.38 and 0.74 subsequently, the reliability of every aspect in a good category. The average level of difficulty is 0.00 with the standard deviation of 0.45 which is in a good category. The peer assessment questionnaire of critical thinking disposition consists of seven aspects: truth-seeking, open-minded, analysis, systematic, self-confidence, inquisitiveness, and maturity with 23 items. The critical thinking disposition validity achieves the significance degree as indicated by the lowest and the high factor loading of 0.66 and 0.76 subsequently, and the reliability of every aspect in a good category. Based on the analysis of the structural equation model, the model fits the data.

  4. A system for incubations at high gas partial pressure

    DEFF Research Database (Denmark)

    Sauer, Patrick; Glombitza, Clemens; Kallmeyer, Jens

    2012-01-01

    High-pressure is a key feature of deep subsurface environments. High partial pressure of dissolved gasses plays an important role in microbial metabolism, because thermodynamic feasibility of many reactions depends on the concentration of reactants. For gases, this is controlled by their partial...... pressure, which can exceed 1 MPa at in situ conditions. Therefore, high hydrostatic pressure alone is not sufficient to recreate true deep subsurface in situ conditions, but the partial pressure of dissolved gasses has to be controlled as well. We developed an incubation system that allows for incubations...... and inert PVDF (polyvinylidene fluoride) incubator sleeve, which is almost impermeable for gases, holds the sample and separates it from the pressure fluid. The flexibility of the incubator sleeve allows for sub-sampling of the medium without loss of pressure. Experiments can be run in both static and flow...

  5. Synthesis gas regeneration electrotechnology using volume high-voltage pulsed discharges: corona and barrier ones

    Directory of Open Access Journals (Sweden)

    M.I. Boyko

    2014-09-01

    Full Text Available Factory testing of a created high-voltage complex (plant has been conducted. The complex consists of two pulse generators with the repetition rate of up to 50,000 pulses per second and load reactors with pulsed discharges - corona and barrier ones. Transistor (IGBT keys are used as energy switches. The efficient mode of coke gas methane conversion (steam reforming to syngas has been obtained with application of the complex created. A unidirectional action of the pulsed discharges, the gas mixture temperature, and a nickel catalyst has reduced the specific energy consumption for synthesis gas regeneration during the conversion. A feasible mechanism of this conversion is described.

  6. High-frequency sound wave propagation in binary gas mixtures flowing through microchannels

    Science.gov (United States)

    Bisi, M.; Lorenzani, S.

    2016-05-01

    The propagation of high-frequency sound waves in binary gas mixtures flowing through microchannels is investigated by using the linearized Boltzmann equation based on a Bhatnagar-Gross-Krook (BGK)-type approach and diffuse reflection boundary conditions. The results presented refer to mixtures whose constituents have comparable molecular mass (like Ne-Ar) as well as to disparate-mass gas mixtures (composed of very heavy plus very light molecules, like He-Xe). The sound wave propagation model considered in the present paper allows to analyze the precise nature of the forced-sound modes excited in different gas mixtures.

  7. GAMMA PROPORTIONAL COUNTER CONTAINING HIGH Z GAS AND LOW Z MODERATOR

    Science.gov (United States)

    Fox, R.

    1963-07-23

    A gamma radiation counter employing a gas proportional counter is described. The radiation counter comprises a cylindrical gas proportional counter which contains a high atomic number gas and is surrounded by a low atomic number gamma radiation moderator material. At least one slit is provided in the moderator to allow accident gamma radiation to enter the moderator in the most favorable manner for moderation, and also to allow low energy gamma radiation to enter the counter without the necessity of passing through the moderator. This radiation counter is capable of detecting and measuring gamma radiation in the energy range of 0.5-5 Mev. (AEC)

  8. High rates of glucose utilization in the gas gland of Atlantic cod (Gadus morhua) are supported by GLUT1 and HK1b.

    Science.gov (United States)

    Clow, Kathy A; Short, Connie E; Hall, Jennifer R; Gendron, Robert L; Paradis, Hélène; Ralhan, Ankur; Driedzic, William R

    2016-09-01

    The gas gland of physoclistous fish utilizes glucose to generate lactic acid that leads to the off-loading of oxygen from haemoglobin. This study addresses characteristics of the first two steps in glucose utilization in the gas gland of Atlantic cod (Gadus morhua). Glucose metabolism by isolated gas gland cells was 12- and 170-fold higher, respectively, than that in heart and red blood cells (RBCs) as determined by the production of (3)H2O from [2-(3)H]glucose. In the gas gland, essentially all of the glucose consumed was converted to lactate. Glucose uptake in the gas gland shows a very high dependence upon facilitated transport as evidenced by saturation of uptake of 2-deoxyglucose at a low extracellular concentration and a requirement for high levels of cytochalasin B for uptake inhibition despite the high efficacy of this treatment in heart and RBCs. Glucose transport is via glucose transporter 1 (GLUT1), which is localized to the glandular cells. GLUT1 western blot analysis from whole-tissue lysates displayed a band with a relative molecular mass of 52 kDa, consistent with the deduced amino acid sequence. Levels of 52 kDa GLUT1 in the gas gland were 2.3- and 33-fold higher, respectively, than those in heart and RBCs, respectively. Glucose phosphorylation is catalysed by hexokinase Ib (HKIb), a paralogue that cannot bind to the outer mitochondrial membrane. Transcript levels of HKIb in the gas gland were 52- and 57-fold more abundant, respectively, than those in heart and RBCs. It appears that high levels of GLUT1 protein and an unusual isoform of HKI are both critical for the high rates of glycolysis in gas gland cells. © 2016. Published by The Company of Biologists Ltd.

  9. High burnup fuel behavior related to fission gas effects under reactivity initiated accidents (RIA) conditions

    Science.gov (United States)

    Lemoine, F.

    1997-09-01

    Specific aspects of irradiated fuel result from the increasing retention of gaseous and volatile fission products with burnup, which, under overpower conditions, can lead to solid fuel pressurization and swelling causing severe PCMI (pellet clad mechanical interaction). In order to assess the reliability of high burnup fuel under RIAs, experimental programs have been initiated which have provided important data concerning the transient fission gas behavior and the clad loading mechanisms. The importance of the rim zone is demonstrated based on three experiments resulting in clad failure at low enthalpy, which are explained by energetic considerations. High gas release in non-failure tests with low energy deposition underlines the importance of grain boundary and porosity gas. Measured final releases are strongly correlated to the microstructure evolution, depending on energy deposition, pulse width, initial and refabricated fuel rod design. Observed helium release can also increase internal pressure and gives hints to the gas behavior understanding.

  10. Critical assessment of methods for treating airborne effluents from high-level waste solidification processes

    Energy Technology Data Exchange (ETDEWEB)

    Christian, J.D.; Pence, D.T.

    1977-06-01

    Off-gas treatment systems are reviewed for high-temperature processes which are being developed for the solidification of high-level liquid wastes from nuclear fuel reprocessing plants. A brief description of each of the processes is given and detailed analyses are made of the expected magnitudes of airborne effluent release rates from each system. The estimated release rates of the various processes are compared with present and anticipated regulatory limits. A number of recommendations are made for additional development studies to better understand and control certain airborne effluents from the solidification processes.

  11. Improving the critical speeds of high-speed trains using magnetorheological technology

    Science.gov (United States)

    Sun, Shuaishuai; Deng, Huaxia; Li, Weihua; Du, Haiping; Qing Ni, Yi; Zhang, Jin; Yang, Jian

    2013-11-01

    With the rapid development of high-speed railways, vibration control for maintaining stability, passenger comfort, and safety has become an important area of research. In order to investigate the mechanism of train vibration, the critical speeds of various DOFs with respect to suspension stiffness and damping are first calculated and analyzed based on its dynamic equations. Then, the sensitivity of the critical speed is studied by analyzing the influence of different suspension parameters. On the basis of these analyses, a conclusion is drawn that secondary lateral damping is the most sensitive suspension damper. Subsequently, the secondary lateral dampers are replaced with magnetorheological fluid (MRF) dampers. Finally, a high-speed train model with MRF dampers is simulated by a combined ADAMS and MATLAB simulation and tested in a roller rig test platform to investigate the mechanism of how the MRF damper affects the train’s stability and critical speed. The results show that the semi-active suspension installed with MRF dampers substantially improves the stability and critical speed of the train.

  12. Analysis of the effect of UO{sub 2} high burnup microstructure on fission gas release

    Energy Technology Data Exchange (ETDEWEB)

    Jernkvist, Lars Olof; Massih, Ali [Quantum Technologies AB, Uppsala Science Park (Sweden)

    2002-10-01

    This report deals with high-burnup phenomena with relevance to fission gas release from UO{sub 2} nuclear fuel. In particular, we study how the fission gas release is affected by local buildup of fissile plutonium isotopes and fission products at the fuel pellet periphery, with subsequent formation of a characteristic high-burnup rim zone micro-structure. An important aspect of these high-burnup effects is the degradation of fuel thermal conductivity, for which prevalent models are analysed and compared with respect to their theoretical bases and supporting experimental data. Moreover, the Halden IFA-429/519.9 high-burnup experiment is analysed by use of the FRAPCON3 computer code, into which modified and extended models for fission gas release are introduced. These models account for the change in Xe/Kr-ratio of produced and released fission gas with respect to time and space. In addition, several alternative correlations for fuel thermal conductivity are implemented, and their impact on calculated fission gas release is studied. The calculated fission gas release fraction in IFA-429/519.9 strongly depends on what correlation is used for the fuel thermal conductivity, since thermal release dominates over athermal release in this particular experiment. The conducted calculations show that athermal release processes account for less than 10% of the total gas release. However, athermal release from the fuel pellet rim zone is presumably underestimated by our models. This conclusion is corroborated by comparisons between measured and calculated Xe/Kr-ratios of the released fission gas.

  13. Gas-Phase Molecular Dynamics: High Resolution Spectroscopy and Collision Dynamics of Transient Species

    Energy Technology Data Exchange (ETDEWEB)

    Hall,G.E.; Sears, T.J.

    2009-04-03

    This research is carried out as part of the Gas-Phase Molecular Dynamics program in the Chemistry Department at Brookhaven National Laboratory. High-resolution spectroscopy, augmented by theoretical and computational methods, is used to investigate the structure and collision dynamics of chemical intermediates in the elementary gas-phase reactions involved in combustion chemistry. Applications and methods development are equally important experimental components of this work.

  14. Gas-Phase Molecular Dynamics: High Resolution Spectroscopy and Collision Dynamics of Transient Species

    Energy Technology Data Exchange (ETDEWEB)

    Hall, G.E.

    2011-05-31

    This research is carried out as part of the Gas-Phase Molecular Dynamics program in the Chemistry Department at Brookhaven National Laboratory. Chemical intermediates in the elementary gas-phase reactions involved in combustion chemistry are investigated by high resolution spectroscopic tools. Production, reaction, and energy transfer processes are investigated by transient, double resonance, polarization and saturation spectroscopies, with an emphasis on technique development and connection with theory, as well as specific molecular properties.

  15. Combustion LES Software for Improved Emissions Predictions of High Performance Gas Turbine Combustors

    Science.gov (United States)

    2005-09-01

    94 vii 8503/8 ABSTRACT Low emissions of CO, NO,, and unburned hydrocarbons ( UHC ) are a difficult...NOR, UHC , and smoke, are becoming a requirement for today’s and future military gas turbine engines. Advanced, high performance gas turbines will...range, and operating pressure. 2 850318 1. INTRODUCTION Low emissions of pollutants, including CO, NO,,, UHC , and smoke, are becoming a requirement

  16. Origins of High H2S-bearing Natural Gas in China

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Natural gas containing hydrogen sulphide (H2S) has been found in several petroliferous basins in China, such as the Sichuan Basin, Bohai Bay Basin, Ordos Basin, Tarim Basin, etc. Natural gas with higher H2S contents (H2S >5% mol.) is mostly distributed in both the gas reservoirs of Dukouhe, Luojiazhai, Puguang and Tieshanpo, which belong to the Triassic Feixianguan Formation in the northeastern Sichuan Basin and those of the Kongdian-Shahejie formations in the northeastern Jinxian Sag of the Jizhong Depression, Bohai Bay Basin. In the Sichuan Basin, the H2S contents of natural gas average over 9% and some can be 17 %, while those of the Bohai Bay Basin range from 40 % to 92 %, being then one of the gas reservoirs with the highest H2S contents in the world. Based on detailed observation and sample analysis results of a total 5000 m of core from over 70 wells in the above-mentioned two basins, especially sulfur isotopic analysis of gypsum,brimstone, pyrite and natural gas, also with integrated study of the geochemical characteristics of hydrocarbons, it is thought that the natural gas with high H2S contents resulted from thermochemical sulfate reduction (TSR) reactions.Among them, the natural gas in the Feixianguan Formation resulted from TSR reactions participated by hydrocarbon gas,while that in the Zhaolanzhuang of the Jinxian Sag being the product of TSR participated by crude oil. During the consumption process of hydrocarbons due to TSR, the heavy hydrocarbons were apt to react with sulfate, which accordingly resulted in the dry coefficient of natural gas increasing and the carbon isotopes becoming heavier.

  17. Polyelectrolyte Coacervates Deposited as High Gas Barrier Thin Films.

    Science.gov (United States)

    Haile, Merid; Sarwar, Owais; Henderson, Robert; Smith, Ryan; Grunlan, Jaime C

    2017-01-01

    Multilayer coatings consisting of oppositely charged polyelectrolytes have proven to be extraordinarily effective oxygen barriers but require many processing steps to fabricate. In an effort to prepare high oxygen barrier thin films more quickly, a polyelectrolyte complex coacervate composed of polyethylenimine and polyacrylic acid is prepared. The coacervate fluid is applied as a thin film using a rod coating process. With humidity and thermal post-treatment, a 2 µm thin film reduces the oxygen transmission rate of 0.127 mm poly(ethylene terephthalate) by two orders of magnitude, rivalling conventional oxygen barrier technologies. These films are fabricated in ambient conditions using low-cost, water-based solutions, providing a tremendous opportunity for single-step deposition of polymeric high barrier thin films.

  18. A Critical Review of the Recent Improvements in Minimizing Nuclear Waste by Innovative Gas-Cooled Reactors

    Directory of Open Access Journals (Sweden)

    E. Bomboni

    2008-01-01

    Full Text Available This paper presents a critical review of the recent improvements in minimizing nuclear waste in terms of quantities, long-term activities, and radiotoxicities by innovative GCRs, with particular emphasis to the results obtained at the University of Pisa. Regarding these last items, in the frame of some EU projects (GCFR, PUMA, and RAPHAEL, we analyzed symbiotic fuel cycles coupling current LWRs with HTRs, finally closing the cycle by GCFRs. Particularly, we analyzed fertile-free and Pu-Th-based fuel in HTR: we improved plutonium exploitation also by optimizing Pu/Th ratios in the fuel loaded in an HTR. Then, we chose GCFRs to burn residual MA. We have started the calculations on simplified models, but we ended them using more “realistic” models of the reactors. In addition, we have added the GCFR multiple recycling option using keff calculations for all the reactors. As a conclusion, we can state that, coupling HTR with GCFR, the geological disposal issues concerning high-level radiotoxicity of MA can be considerably reduced.

  19. NEARBY CLUMPY, GAS RICH, STAR-FORMING GALAXIES: LOCAL ANALOGS OF HIGH-REDSHIFT CLUMPY GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Garland, C. A. [Natural Sciences Department, Jeffords Science Center, Castleton State College, Castleton, VT 05735 (United States); Pisano, D. J.; Rabidoux, K. [Department of Physics and Astronomy, West Virginia University, 135 Willey Street, P.O. Box 6315, Morgantown, WV 26506 (United States); Low, M.-M. Mac [Department of Astrophysics, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024 (United States); Kreckel, K. [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Guzmán, R., E-mail: catherine.garland@castleton.edu, E-mail: djpisano@mail.wvu.edu, E-mail: krabidou@mix.wvu.edu, E-mail: mordecai@amnh.org, E-mail: kreckel@mpia.de, E-mail: guzman@astro.ufl.edu [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, P.O. Box 112055, Gainesville, FL 32611 (United States)

    2015-07-10

    Luminous compact blue galaxies (LCBGs) have enhanced star formation rates (SFRs) and compact morphologies. We combine Sloan Digital Sky Survey data with H i data of 29 LCBGs at redshift z ∼ 0 to understand their nature. We find that local LCBGs have high atomic gas fractions (∼50%) and SFRs per stellar mass consistent with some high-redshift star-forming galaxies (SFGs). Many local LCBGs also have clumpy morphologies, with clumps distributed across their disks. Although rare, these galaxies appear to be similar to the clumpy SFGs commonly observed at z ∼ 1–3. Local LCBGs separate into three groups: (1) interacting galaxies (∼20%); (2) clumpy spirals (∼40%); and (3) non-clumpy, non-spirals with regular shapes and smaller effective radii and stellar masses (∼40%). It seems that the method of building up a high gas fraction, which then triggers star formation, is not the same for all local LCBGs. This may lead to a dichotomy in galaxy characteristics. We consider possible gas delivery scenarios and suggest that clumpy spirals, preferentially located in clusters and with companions, are smoothly accreting gas from tidally disrupted companions and/or intracluster gas enriched by stripped satellites. Conversely, as non-clumpy galaxies are preferentially located in the field and tend to be isolated, we suggest clumpy, cold streams, which destroy galaxy disks and prevent clump formation, as a likely gas delivery mechanism for these systems. Other possibilities include smooth cold streams, a series of minor mergers, or major interactions.

  20. Complete elution of vacuum gas oil resins by comprehensive high-temperature two-dimensional gas chromatography.

    Science.gov (United States)

    Boursier, Laure; Souchon, Vincent; Dartiguelongue, Cyril; Ponthus, Jérémie; Courtiade, Marion; Thiébaut, Didier

    2013-03-08

    The development of efficient conversion processes requires extended knowledge on vacuum gas oils (VGOs). Among these processes, hydrocracking is certainly one of the best suited to meet the increasing demand on high quality diesel fuels. Most of refractory and inhibiting compounds towards hydrocracking and especially nitrogen containing compounds are contained in a fraction of the VGO called the resin fraction, which corresponds to the most polar fraction of a VGO obtained by liquid chromatography (LC) fractionation on a silica column. However, the lack of resolution observed through existing analytical methods does not allow a detailed characterization of these fractions. A recent study showed that comprehensive high temperature two-dimensional gas chromatography (HT-GC×GC) methods could be optimized in order to elute heavy compounds. This method was implemented for the analysis of VGO resin fractions and complete elution was reached. Firstly, the method was validated through repeatability, accuracy, linearity and response factors calculations. Four VGO resin fractions were analyzed and their HT-GC×GC simulated distillation curves were compared to their GC simulated distillation (GC-SimDist) curves. This comparison showed that the method allows complete elution of most of the analyzed VGO resin fractions. However, a detailed characterization of these fractions is not yet obtained due to the very large number of heteroatomic and aromatic species that a flame ionization detector can detect. Current work aims at increasing the selectivity of GC×GC by using heteroatom selective detectors in order to improve the characterization of such products.

  1. The fabrication of high sensitivity gold nanorod H2S gas sensors utilizing the highly uniform anodic aluminum oxide template

    Directory of Open Access Journals (Sweden)

    Chien-Yu Li

    2016-12-01

    Full Text Available Gold nanorod were fabricated using anodic alumina oxide template for H2S gas detection. The nanorod gas sensor exhibits high surface density and contact area, which can increase detection sensitivity. The anodic alumina oxide template contains an array of pores, with a width of 70 nm and a length of 27μm. Au nanorod were obtained through electro-deposition under a pulse bias of −1 V. The resistance of the Au nanorod was recorded upon exposure to various concentrations of H2S. The resistance could be attributed to the high electron affinity between sulfide and Au nanorod. Au–sulfide bonds provide strong bonding, which could alter the conductivity of the sensor. The gas sensor exhibits high sensitivity and short response time for H2S detection at room temperature.

  2. The fabrication of high sensitivity gold nanorod H2S gas sensors utilizing the highly uniform anodic aluminum oxide template

    Science.gov (United States)

    Li, Chien-Yu; Li, Ciao-Yu; Wu, You-Lin; Hsu, Chung-Ping; Lee, Ming-Ching; Houng, Mau-Phon

    2016-12-01

    Gold nanorod were fabricated using anodic alumina oxide template for H2S gas detection. The nanorod gas sensor exhibits high surface density and contact area, which can increase detection sensitivity. The anodic alumina oxide template contains an array of pores, with a width of 70 nm and a length of 27 μ m . Au nanorod were obtained through electro-deposition under a pulse bias of -1 V. The resistance of the Au nanorod was recorded upon exposure to various concentrations of H2S. The resistance could be attributed to the high electron affinity between sulfide and Au nanorod. Au-sulfide bonds provide strong bonding, which could alter the conductivity of the sensor. The gas sensor exhibits high sensitivity and short response time for H2S detection at room temperature.

  3. Enzymatically active high-flux selectively gas-permeable membranes

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Ying-Bing; Cecchi, Joseph L.; Rempe, Susan; FU, Yaqin; Brinker, C. Jeffrey

    2016-01-26

    An ultra-thin, catalyzed liquid transport medium-based membrane structure fabricated with a porous supporting substrate may be used for separating an object species such as a carbon dioxide object species. Carbon dioxide flux through this membrane structures may be several orders of magnitude higher than traditional polymer membranes with a high selectivity to carbon dioxide. Other gases such as molecular oxygen, molecular hydrogen, and other species including non-gaseous species, for example ionic materials, may be separated using variations to the membrane discussed.

  4. Application of CFRP with High Hydrogen Gas Barrier Characteristics to Fuel Tanks of Space Transportation System

    Science.gov (United States)

    Yonemoto, Koichi; Yamamoto, Yuta; Okuyama, Keiichi; Ebina, Takeo

    In the future, carbon fiber reinforced plastics (CFRPs) with high hydrogen gas barrier performance will find wide applications in all industrial hydrogen tanks that aim at weight reduction; the use of such materials will be preferred to the use of conventional metallic materials such as stainless steel or aluminum. The hydrogen gas barrier performance of CFRP will become an important issue with the introduction of hydrogen-fuel aircraft. It will also play an important role in realizing fully reusable space transportation system that will have high specific tensile CFRP structures. Such materials are also required for the manufacture of high-pressure hydrogen gas vessels for use in the fuel cell systems of automobiles. This paper introduces a new composite concept that can be used to realize CFRPs with high hydrogen gas barrier performance for applications in the cryogenic tanks of fully reusable space transportation system by the incorporation of a nonmetallic crystal layer, which is actually a dense and highly oriented clay crystal laminate. The preliminary test results show that the hydrogen gas barrier characteristics of this material after cryogenic heat shocks and cyclic loads are still better than those of other polymer materials by approximately two orders of magnitude.

  5. Human respiration at rest in rapid compression and at high pressures and gas densities

    Science.gov (United States)

    Gelfand, R.; Lambertsen, C. J.; Strauss, R.; Clark, J. M.; Puglia, C. D.

    1983-01-01

    The ventilation (V), end-tidal PCO2 (PACO2), and CO2 elimination rate were determined in men at rest breathing CO2-free gas over the pressure range 1-50 ATA and the gas density range 0.4-25 g/l, during slow and rapid compressions, at stable elevated ambient pressures and during slow decompressions. Progressive increase in pulmonary gas flow resistance due to elevation of ambient pressure and inspired gas density to the He-O2 equivalent of 5000 feet of seawater was found to produce a complex pattern of change in PACO2. It was found that as both ambient pressure and pulmonary gas flow resistance were progressively raised, PACO2 at first increased, went through a maximum, and then declined towards values near the 1 ATA level. It is concluded that this pattern of PACO2 change results from the interaction on ventilation of the increase in pulmonary resistance due to the elevation of gas density with the increase in respiratory drive postulated as due to generalized central nervous system excitation associated with exposure to high hydrostatic pressure. It is suggested that a similar interaction exists between increased gas flow resistance and the increase in respiratory drive related to nitrogen partial pressure and the resulting narcosis.

  6. High-performance intrinsically microporous dihydroxyl-functionalized triptycene-based polyimide for natural gas separation

    KAUST Repository

    Alaslai, Nasser Y.

    2016-03-22

    A novel polyimide of intrinsic microporosity (PIM-PI) was synthesized from a 9,10-diisopropyl-triptycene-based dianhydride (TPDA) and dihydroxyl-functionalized 4,6-diaminoresorcinol (DAR). The unfunctionalized TPDA-m-phenylenediamine (mPDA) polyimide derivative was made as a reference material to evaluate the effect of the OH group in TPDA-DAR on its gas transport properties. Pure-gas permeability coefficients of He, H2, N2, O2, CH4, and CO2 were measured at 35 °C and 2 atm. The BET surface area based on nitrogen adsorption of dihydroxyl-functionalized TPDA-DAR (308 m2g-1) was 45% lower than that of TPDA-mPDA (565 m2g-1). TPDA-mPDA had a pure-gas CO2 permeability of 349 Barrer and CO2/CH4 selectivity of 32. The dihydroxyl-functionalized TPDA-DAR polyimide exhibited enhanced pure-gas CO2/CH4 selectivity of 46 with a moderate decrease in CO2 permeability to 215 Barrer. The CO2 permeability of TPDA-DAR was ∼30-fold higher than that of a commercial cellulose triacetate membrane coupled with 39% higher pure-gas CO2/CH4 selectivity. The TPDA-based dihydroxyl-containing polyimide showed good plasticization resistance and maintained high mixed-gas selectivity of 38 when tested at a typical CO2 natural gas wellhead CO2 partial pressure of 10 atm.

  7. In situ gas analysis for high pressure applications using property measurements.

    Science.gov (United States)

    Moeller, J; Span, R; Fieback, T

    2013-10-01

    As the production, distribution, and storage of renewable energy based fuels usually are performed under high pressures and as there is a lack of in situ high pressure gas analysis instruments on the market, the aim of this work was to develop a method for in situ high pressure gas analysis of biogas and hydrogen containing gas mixtures. The analysis is based on in situ measurements of optical, thermo physical, and electromagnetic properties in gas mixtures with newly developed high pressure sensors. This article depicts the calculation of compositions from the measured properties, which is carried out iteratively by using highly accurate equations of state for gas mixtures. The validation of the method consisted of the generation and measurement of several mixtures, of which three are presented herein: a first mixture of 64.9 mol. % methane, 17.1 mol. % carbon dioxide, 9 mol. % helium, and 9 mol. % ethane at 323 K and 423 K in a pressure range from 2.5 MPa to 17 MPa; a second mixture of 93.0 mol. % methane, 4.0 mol. % propane, 2.0 mol. % carbon dioxide, and 1.0 mol. % nitrogen at 303 K, 313 K, and 323 K in a pressure range from 1.2 MPa to 3 MPa; and a third mixture of 64.9 mol. % methane, 30.1 mol. % carbon dioxide, and 5.0 mol. % nitrogen at 303 K, 313 K, and 323 K in a pressure range from 2.5 MPa to 4 MPa. The analysis of the tested gas mixtures showed that with measured density, velocity of sound, and relative permittivity the composition can be determined with deviations below 1.9 mol. %, in most cases even below 1 mol. %. Comparing the calculated compositions with the generated gas mixture, the deviations were in the range of the combined uncertainty of measurement and property models.

  8. Parametric analysis of a high temperature packed bed thermal storage design for a solar gas turbine

    CSIR Research Space (South Africa)

    Klein, P

    2015-08-01

    Full Text Available The development of a high temperature Thermal Energy Storage (TES) system will allow for high solar shares in Solar Gas Turbine (SGT) plants. In this research a pressurised storage solution is proposed that utilises a packed bed of alumina spheres...

  9. High-pressure gas hydrates of argon: compositions and equations of state.

    Science.gov (United States)

    Manakov, Andrey Yu; Ogienko, Andrey G; Tkacz, Marek; Lipkowski, Janusz; Stoporev, Andrey S; Kutaev, Nikolay V

    2011-08-11

    Volume changes corresponding to transitions between different phases of high-pressure argon gas hydrates were studied with a piston-cylinder apparatus at room temperature. Combination of these data with the data taken from the literature allowed us to obtain self-consistent set of data concerning the equations of state and compositions of the high-pressure hydrates of argon.

  10. Characterisation of gas hydrates formation and dissociation using high pressure DSC

    Energy Technology Data Exchange (ETDEWEB)

    Le Parlouer, P. [Thermal Consulting, Caluire (France); Etherington, G. [Setaram Inc., Pennsauken, NJ (United States)

    2008-07-01

    This paper provided details of an innovative methodology that used a high pressure micro-scale differential scanning calorimetry (DSC) method to characterize the thermodynamic properties and kinetics of gas hydrate formation. The calorimeter was based on a symmetrical heat flux design that used a Peltier cooling and heating principle. No refrigerating fluids were required. The method described phase transitions in relation to time, temperature and pressure. The DSC method was designed for use with gas hydrates trapped in marine sediments; hydrate formation in drilling muds and annulars during offshore oil and gas extraction; the storage and transportation of natural gas; and gas hydrate formation and dissociation for cold storage and transportation. Tests demonstrated that the DSC accurately predicted the formation of gas hydrates under high pressure conditions. Experimental studies were conducted to investigate salt solutions under methane pressure; and hydrate dissociation in a sodium chloride (NaC1) and ethyleneglycol solution. Data obtained comparing the method with classical PVT techniques showed that the MicroDSC technique was less time-consuming and required smaller sample volumes. It was concluded that the method is suitable for use with various types of fluids. 13 refs., 7 figs.

  11. The formation mechanism of high-quality dolomite reservoir in the deep of Puguang Gas Field

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The discovery of Puguang Gas Field provides the exploration of China deep marine carbonate rock with important references.In Puguang Gas Field,the dolomite reservoirs discovered in the deep are the best in the present of China,which present big thickness and wide-range distribution,and develop abundant secondary porosity.The researches show that Puguang Gas Field bears the characteristics of early gas-filling time,deep burial,high matured organic matter and long-term interaction of hydrocarbon(oil and gas)-water-rock(carbonate reservoir).The developments of secondary pores in this area are affected by multiple diagenesis and their formation mechanisms are complicated.Through the research on depositional environment,sedimentary facies and reservoir porosity characters of Changxing and Feixianguan Formations,it is thought that high-quality dolomite reservoirs of Puguang Gas Field form on the favorable sedimentary facies belts,which are the integrate result affected by several factors including superficial corrosion,burial corrosion,overpressure and tectonic movement,among which burial corrosion of TSR to reservoir and overpressure formed by thermal evolution of organic matter have great effect on the formation of secondary porosity of Changxing and Feixianguan Formations.

  12. Fluorescence resonance energy transfer of gas-phase ions under ultra high vacuum and ambient conditions.

    Science.gov (United States)

    Frankevich, Vladimir; Chagovets, Vitaliy; Widjaja, Fanny; Barylyuk, Konstantin; Yang, Zhiyi; Zenobi, Renato

    2014-05-21

    We report evidence for fluorescence resonance energy transfer (FRET) of gas-phase ions under ultra high vacuum conditions (10(-9) mbar) inside a mass spectrometer as well as under ambient conditions inside an electrospray plume. Two different FRET pairs based on carboxyrhodamine 6G (donor) and ATTO590 or Bodipy TR (acceptor) dyes were examined and their gas-phase optical properties were studied. Our measurements indicate a different behavior for the two FRET pairs, which can be attributed to their different conformations in the gas phase. Upon desolvation via electrospray ionization, one of the FRET pairs undergoes a conformational change that leads to disappearance of FRET. This study shows the promise of FRET to obtain a direct correlation between solution and gas-phase structures.

  13. High viscosity gas fluidization of fine particles: An extended window of quasihomogeneous flow.

    Science.gov (United States)

    Valverde, Jose Manuel; Castellanos, Antonio

    2006-08-01

    We explore the role of gas viscosity in the behavior of gas-fluidized beds of fine powders by means of experimental measurements using nitrogen and neon as fluidizing gases, and theoretical considerations. The existence of a nonbubbling fluidlike regime has been recently observed in beds of fine powders fluidized with nitrogen. Our experiments with neon reveal a discontinuous transition from heterogeneous fluidization to a highly expanded homogeneous fluidization state. We point out that increasing gas viscosity enhances the coherence of agglomerate swarms, which promotes a local void-splitting mechanism, thus improving the uniformity of fluidization. Our theoretical analysis predicts that further increase of gas viscosity would produce a full suppression of the bubbling regime, i.e., the uniformly fluidized bed would undergo a direct transition to a turbulent regime as seen in beds of nanoparticles fluidized by nitrogen and in liquid-fluidized beds of moderate-density beads.

  14. METAL INERT GAS WELDING OF 2519-T87 HIGH STRENGTH ALUMINUM ALLOY

    Institute of Scientific and Technical Information of China (English)

    XU Lianghong; TIAN Zhiling; ZHANG Xiaomu; PENG Yun

    2007-01-01

    20 mm thick plates of 2519-T87 high strength aluminum alloy have been welded. The effects of the compositions of filier wires, the heat input and the compositions of shielding gas on the mechanical properties and microstructure of the welded joint have been investigated. The results indicate that finer microstructure, better mechanical properties and higher value of hardness of HAZ can be obtained by using lower heat input. The use of Ar/He mixed shielding gas has several advantages over pure Ar shielding gas. With the increase of the proportion of He in the mixed shielding gas, the grain size of the weld metal as well as porosity susceptibility decreases. When the volume ratio of He to Ar reaches 7:3, the porosity and the grain size of weld metal reach the minimum, and the porosity can be further reduced by filling some CO2.

  15. Investigation of high-temperature materials for uranium-fluoride-based gas core reactor systems

    Energy Technology Data Exchange (ETDEWEB)

    Collins, C.; Wang, S.C.P.; Anghaie, S.

    1988-01-01

    The development of the uranium-fluoride-based gas core reactor (GCR) systems will depend on the availability of wall materials that can survive the severe thermal, chemical, and nuclear environments of these systems. In the GCR system, the fuel/working fluid chemical constituents include enriched uranium fluorides UF{sub n} (n = 1 to 4) and fluorides operating at gas pressures of {approx}1 to 100 atm. The peak temperature of the fissioning gas/working fluid in the system can be 4000 K or higher, and the temperatures of the inner surface of the construction wall may exceed 1500 K. Wall materials that can be compatible in this environment must possess high melting points, good resistance to creep and thermal shock, and high resistance to fluorination. Compatible materials that feature high fluorination resistance are those that either do not react with fluorine/fluoride gases or those that can form a protective fluoride scale, which prevents or reduces further attack by the corrosive gas. Because fluorine and fluoride gases are strong oxidizing agents, formation of high melting point protective scales on substrate materials is more likely to be expected. This paper summarizes results of corrosion testing for evaluation of materials compatibility with uranium fluoride. These tests have been carried out by exposing different materials to UF{sub 6} gas in a closed capsule at temperatures up to 1500 K. Past exposure examinations were conducted to determine the morphology and composition of scales that were formed.

  16. Controls on coalbed methane potential and gas sorption characteristics of high-volatile bituminous coals in Indiana

    Science.gov (United States)

    Solano-Acosta, Wilfrido

    The increasing demand for energy and a growing concern for global warming, owing in part to the steep rise in anthropogenic greenhouse gas emissions, have sparked worldwide interest in clean coal technologies. Although the energy potential of coal is large, there are many environmental concerns associated with its large-scale utilization. An alternative solution to increasing demand for energy is the recovery of coalbed methane (CBM), an efficient and clean fossil fuel associated with extensive coal deposits. CBM today represents nearly 10 percent of the energy consumed in the United States. From an environmental perspective, coal beds that are too deep or that contain low-quality coal are being investigated as potential sites for permanently sequestering carbon dioxide emissions (CO2 sequestration). Methane has been documented in coals of various ranks. The occurrence and distribution of economically recoverable quantities of CBM result from the interplay between stratigraphy, tectonics, and hydrology. This study evaluates geologic factors that control the occurrence of CBM in Indiana coals, ranging from large-scale processes (i.e., burial and fracturing) to molecular interactions between CBM and the physical structure of coal (i.e., gas adsorption). This study investigates the role of tectonics and burial in the formation of coal fracture sets (cleats) that are critical for CBM extraction. Based on field data, I investigate the role of fracturing with regard to gas occurrence and CBM producibility. The timing of cleat formation is evaluated via carbon and oxygen isotopic signatures of cleat-filling minerals. In addition to field-scale observations, this study includes an experimental component that, based on a multitude of laboratory data, constrains optimum conditions for coal-sample preservation prior to laboratory analyses for exploration. Chemical analyses, petrography, grain-size distributions, Fourier transform infra-red (FTIR) spectroscopy, pore

  17. Investigation Of The High-Voltage Discharge On The Surface Of Gas-Liquid System

    Science.gov (United States)

    Nguyen-Kuok, Shi; Morgunov, Aleksandr; Malakhov, Yury; Korotkikh, Ivan

    2016-09-01

    This paper describes an experimental setup for study of physical processes in the high-voltage discharge on the surface of gas-liquid system at atmospheric pressure. Measurements of electrical and optical characteristics of the high-voltage discharge in gas, at the surface of the gas-liquid system and in the electrolyte are obtained. The parameters of the high-voltage discharge and the conditions for its stable operation are presented. Investigations with various electrolytes and cathode assemblies of various materials and sizes were carried out. The installation can be used for the processing and recycling of industrial and chemical liquid waste. Professor of Laboratory of Plasma Physics, National Research University MPEI, Krasnokazarmennya Str.14, 111250, Moscow, Russia.

  18. ANALYSIS OF A HIGH TEMPERATURE GAS-COOLED REACTOR POWERED HIGH TEMPERATURE ELECTROLYSIS HYDROGEN PLANT

    Energy Technology Data Exchange (ETDEWEB)

    M. G. McKellar; E. A. Harvego; A. M. Gandrik

    2010-11-01

    An updated reference design for a commercial-scale high-temperature electrolysis (HTE) plant for hydrogen production has been developed. The HTE plant is powered by a high-temperature gas-cooled reactor (HTGR) whose configuration and operating conditions are based on the latest design parameters planned for the Next Generation Nuclear Plant (NGNP). The current HTGR reference design specifies a reactor power of 600 MWt, with a primary system pressure of 7.0 MPa, and reactor inlet and outlet fluid temperatures of 322°C and 750°C, respectively. The reactor heat is used to produce heat and electric power to the HTE plant. A Rankine steam cycle with a power conversion efficiency of 44.4% was used to provide the electric power. The electrolysis unit used to produce hydrogen includes 1.1 million cells with a per-cell active area of 225 cm2. The reference hydrogen production plant operates at a system pressure of 5.0 MPa, and utilizes a steam-sweep system to remove the excess oxygen that is evolved on the anode (oxygen) side of the electrolyzer. The overall system thermal-to-hydrogen production efficiency (based on the higher heating value of the produced hydrogen) is 42.8% at a hydrogen production rate of 1.85 kg/s (66 million SCFD) and an oxygen production rate of 14.6 kg/s (33 million SCFD). An economic analysis of this plant was performed with realistic financial and cost estimating The results of the economic analysis demonstrated that the HTE hydrogen production plant driven by a high-temperature helium-cooled nuclear power plant can deliver hydrogen at a competitive cost. A cost of $3.03/kg of hydrogen was calculated assuming an internal rate of return of 10% and a debt to equity ratio of 80%/20% for a reactor cost of $2000/kWt and $2.41/kg of hydrogen for a reactor cost of $1400/kWt.

  19. Experiences with a pre-series of Micro Strip Gas Counters with Gas Electron Multipliers for high rate applications

    CERN Document Server

    Zander, Anette

    2001-01-01

    Micro strip gas chambers (MSGCs) are promising candidates for large scale applications. They combine a good spatial resolution with high granularity and low cost. As a possible extension of the plain MSGC, a Gas Electron Multiplier (GEM) foil may be implemented into the detector in order to increase the safety of operation. It was planned to equip the outer part of the tracking system of the Compact Muon Solenoid (CMS) experiment at the future Large Hadron Collider (LHC) at the Centre de Recherche Nucleaire (CERN) with MSGCs. In the barrel part of the tracker, plain MSGCs were to be used. For the forward part, the MSGC+GEM technology was envisaged. This thesis describes the assembly and test of a pre-series of 18 fully functional MSGC+GEM forward detector modules to determine their radiation hardness and their readiness for mass production. Five of the modules were built at Aachen, thirteen more at the 'Institut für Experimentelle Kernphysik' in Karlsruhe. For the pre-series, two different types of GEM foils...

  20. High Temperature Gas Reactors: Assessment of Applicable Codes and Standards

    Energy Technology Data Exchange (ETDEWEB)

    McDowell, Bruce K.; Nickolaus, James R.; Mitchell, Mark R.; Swearingen, Gary L.; Pugh, Ray

    2011-10-31

    Current interest expressed by industry in HTGR plants, particularly modular plants with power up to about 600 MW(e) per unit, has prompted NRC to task PNNL with assessing the currently available literature related to codes and standards applicable to HTGR plants, the operating history of past and present HTGR plants, and with evaluating the proposed designs of RPV and associated piping for future plants. Considering these topics in the order they are arranged in the text, first the operational histories of five shut-down and two currently operating HTGR plants are reviewed, leading the authors to conclude that while small, simple prototype HTGR plants operated reliably, some of the larger plants, particularly Fort St. Vrain, had poor availability. Safety and radiological performance of these plants has been considerably better than LWR plants. Petroleum processing plants provide some applicable experience with materials similar to those proposed for HTGR piping and vessels. At least one currently operating plant - HTR-10 - has performed and documented a leak before break analysis that appears to be applicable to proposed future US HTGR designs. Current codes and standards cover some HTGR materials, but not all materials are covered to the high temperatures envisioned for HTGR use. Codes and standards, particularly ASME Codes, are under development for proposed future US HTGR designs. A 'roadmap' document has been prepared for ASME Code development; a new subsection to section III of the ASME Code, ASME BPVC III-5, is scheduled to be published in October 2011. The question of terminology for the cross-duct structure between the RPV and power conversion vessel is discussed, considering the differences in regulatory requirements that apply depending on whether this structure is designated as a 'vessel' or as a 'pipe'. We conclude that designing this component as a 'pipe' is the more appropriate choice, but that the ASME BPVC

  1. High-confidence software for safety-critical process-control systems

    Energy Technology Data Exchange (ETDEWEB)

    Bastani, F.B. [Univ. of Houston, TX (United States)

    1997-12-01

    Software for safety-critical systems, such as nuclear power plant control systems; avionic systems; and medical, defense, and manufacturing systems, must be highly reliable because failures can have catastrophic consequences. While existing methods, such as formal techniques, testing, and fault-tolerant software, can significantly enhance software reliability, they have some limitations in achieving ultrahigh reliability requirements. Formal methods are not able to cope with specification faults, testing is not cost-effective for high-assurance systems, and fault-tolerant software based on diverse designs is susceptible to common-mode failures.

  2. Micro/Nano Gas Sensors: A New Strategy Towards In-Situ Wafer-Level Fabrication of High-Performance Gas Sensing Chips

    Science.gov (United States)

    Xu, Lei; Dai, Zhengfei; Duan, Guotao; Guo, Lianfeng; Wang, Yi; Zhou, Hong; Liu, Yanxiang; Cai, Weiping; Wang, Yuelin; Li, Tie

    2015-01-01

    Nano-structured gas sensing materials, in particular nanoparticles, nanotubes, and nanowires, enable high sensitivity at a ppb level for gas sensors. For practical applications, it is highly desirable to be able to manufacture such gas sensors in batch and at low cost. We present here a strategy of in-situ wafer-level fabrication of the high-performance micro/nano gas sensing chips by naturally integrating microhotplatform (MHP) with nanopore array (NPA). By introducing colloidal crystal template, a wafer-level ordered homogenous SnO2 NPA is synthesized in-situ on a 4-inch MHP wafer, able to produce thousands of gas sensing units in one batch. The integration of micromachining process and nanofabrication process endues micro/nano gas sensing chips at low cost, high throughput, and with high sensitivity (down to ~20 ppb), fast response time (down to ~1 s), and low power consumption (down to ~30 mW). The proposed strategy of integrating MHP with NPA represents a versatile approach for in-situ wafer-level fabrication of high-performance micro/nano gas sensors for real industrial applications. PMID:26001035

  3. A high-temperature gas-and-steam turbine plant operating on combined fuel

    Science.gov (United States)

    Klimenko, A. V.; Milman, O. O.; Shifrin, B. A.

    2015-11-01

    A high-temperature gas-steam turbine plant (GSTP) for ultrasupercritical steam conditions is proposed based on an analysis of prospects for the development of power engineering around the world and in Russia up to 2040. The performance indicators of a GSTP using steam from a coal-fired boiler with a temperature of 560-620°C with its superheating to 1000-1500°C by firing natural gas with oxygen in a mixingtype steam superheater are analyzed. The thermal process circuit and design of a GSTP for a capacity of 25 MW with the high- and intermediate-pressure high-temperature parts with the total efficiency equal to 51.7% and the natural gas utilization efficiency equal to 64-68% are developed. The principles of designing and the design arrangement of a 300 MW GSTP are developed. The effect of economic parameters (the level and ratio of prices for solid fuel and gas, and capital investments) on the net cost of electric energy is determined. The net cost of electric energy produced by the GSTP is lower than that produced by modern combined-cycle power plants in a wide variation range of these parameters. The components of a high-temperature GSTP the development of which determines the main features of such installations are pointed out: a chamber for combusting natural gas and oxygen in a mixture with steam, a vacuum device for condensing steam with a high content of nondensables, and a control system. The possibility of using domestically available gas turbine technologies for developing the GSTP's intermediate-pressure high-temperature part is pointed out. In regard of its environmental characteristics, the GSTP is more advantageous as compared with modern condensing power plants: it allows a flow of concentrated carbon dioxide to be obtained at its outlet, which can be reclaimed; in addition, this plant requires half as much consumption of fresh water.

  4. Numerical simulations of enhanced gas recovery at the Załezcze gas field in Poland confirm high co

    NARCIS (Netherlands)

    Klimkowski, Ł.; Nagy, S.; Papiernik, B.; Orlic, B.; Kempka, T.

    2015-01-01

    Natural gas from the Załęcze gas field located in the Fore-Sudetic Monocline of the Southern Permian Basin has been produced since November 1973, and continuous gas production led to a decrease in the initial reservoir pressure from 151 bar to about 22 bar until 2010. We investigated a prospective

  5. Numerical simulations of enhanced gas recovery at the Załezcze gas field in Poland confirm high co

    NARCIS (Netherlands)

    Klimkowski, Ł.; Nagy, S.; Papiernik, B.; Orlic, B.; Kempka, T.

    2015-01-01

    Natural gas from the Załęcze gas field located in the Fore-Sudetic Monocline of the Southern Permian Basin has been produced since November 1973, and continuous gas production led to a decrease in the initial reservoir pressure from 151 bar to about 22 bar until 2010. We investigated a prospective e

  6. Lupus disks with faint CO isotopologues: low gas/dust or high carbon depletion?

    Science.gov (United States)

    Miotello, A.; van Dishoeck, E. F.; Williams, J. P.; Ansdell, M.; Guidi, G.; Hogerheijde, M.; Manara, C. F.; Tazzari, M.; Testi, L.; van der Marel, N.; van Terwisga, S.

    2017-03-01

    Context. An era has started in which gas and dust can be observed independently in protoplanetary disks, thanks to the recent surveys with the Atacama Large Millimeter/sub-millimeter Array (ALMA). The first near-complete high-resolution disk survey in both dust and gas in a single star-forming region has been carried out in Lupus, finding surprisingly low gas-to-dust ratios. Aims: The goal of this work is to fully exploit CO isotopologue observations in Lupus, comparing them with physical-chemical model results, in order to obtain gas masses for a large number of disks and compare gas and dust properties. Methods: We have employed the grid of physical-chemical models presented previously to analyze continuum and CO isotopologue (13CO J = 3-2 and C18O J = 3-2) observations of Lupus disks, including isotope-selective processes and freeze-out. We also employed the ALMA 13CO-only detections to calculate disk gas masses for a total of 34 sources, which expands the sample of 10 disks reported earlier, where C18O was also detected. Results: We confirm that overall gas-masses are very low, often lower than 1MJ, when volatile carbon is not depleted. Accordingly, global gas-to-dust ratios are much lower than the expected interstellar-medium value of 100, which is predominantly between 1 and 10. Low CO-based gas masses and gas-to-dust ratios may indicate rapid loss of gas, or alternatively chemical evolution, for example, through sequestering of carbon from CO to more complex molecules, or carbon locked up in larger bodies. Conclusions: Current ALMA observations of 13CO and continuum emission cannot distinguish between these two hypotheses. We have simulated both scenarios, but chemical model results do not allow us to rule out one of the two, pointing to the need to calibrate CO-based masses with other tracers. Assuming that all Lupus disks have evolved mainly as a result of viscous processes over the past few Myr, the previously observed correlation between the current mass

  7. Fuel Flexible Combustion Systems for High-Efficiency Utilization of Opportunity Fuels in Gas Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Venkatesan, Krishna

    2011-11-30

    The purpose of this program was to develop low-emissions, efficient fuel-flexible combustion technology which enables operation of a given gas turbine on a wider range of opportunity fuels that lie outside of current natural gas-centered fuel specifications. The program encompasses a selection of important, representative fuels of opportunity for gas turbines with widely varying fundamental properties of combustion. The research program covers conceptual and detailed combustor design, fabrication, and testing of retrofitable and/or novel fuel-flexible gas turbine combustor hardware, specifically advanced fuel nozzle technology, at full-scale gas turbine combustor conditions. This project was performed over the period of October 2008 through September 2011 under Cooperative Agreement DE-FC26-08NT05868 for the U.S. Department of Energy/National Energy Technology Laboratory (USDOE/NETL) entitled "Fuel Flexible Combustion Systems for High-Efficiency Utilization of Opportunity Fuels in Gas Turbines". The overall objective of this program was met with great success. GE was able to successfully demonstrate the operability of two fuel-flexible combustion nozzles over a wide range of opportunity fuels at heavy-duty gas turbine conditions while meeting emissions goals. The GE MS6000B ("6B") gas turbine engine was chosen as the target platform for new fuel-flexible premixer development. Comprehensive conceptual design and analysis of new fuel-flexible premixing nozzles were undertaken. Gas turbine cycle models and detailed flow network models of the combustor provide the premixer conditions (temperature, pressure, pressure drops, velocities, and air flow splits) and illustrate the impact of widely varying fuel flow rates on the combustor. Detailed chemical kinetic mechanisms were employed to compare some fundamental combustion characteristics of the target fuels, including flame speeds and lean blow-out behavior. Perfectly premixed combustion experiments were conducted to

  8. Flexible Furnace Concepts for Vacuum Heat Treatment Combined with High-pressure Gas Quenching

    Institute of Scientific and Technical Information of China (English)

    Karl Ritter; Stefan Wiebach

    2004-01-01

    IN the past five years the process combination of vacuum hardening, respectively vacuum carburizing with high-pressure gas quenching was successfully introduced to the market, especially in the manufacture of gears. In the meantime furnace concepts for various applications are available to the industry. In the following report three plant varieties are introduced, which differ in process flexibility and throughput. This report also explains criteria for the selection of a furnace in view of the existing application requirements. Besides this a short introduction is given into the vacuum carburizing process and the high-pressure gas quenching technology.

  9. [Determination of mono- to tri-chlorinated dibenzo-p-dioxins and dibenzofurans in stack gas using isotope dilution high resolution gas chromatography-high resolution mass spectrometry].

    Science.gov (United States)

    Tang, Chen; Liu, Qipeng; Tian, Zhenyu; Xie, Huiting; Wang, Mengjing; Liu, Wenbin

    2014-09-01

    A method for the determination of mono- to tri-chlorinated dibenzo-p-dioxins and dibenzofurans (mono- to tri-CDD/Fs) in stack gas using isotope dilution high resolution gas chromatography-high resolution mass spectrometry (HRGC-HRMS) was developed. The sam- ples were extracted by Soxhlet extraction, and then the extracts were concentrated and purified using a multilayer silica gel column and a basic alumina column. The analytes were separated by HRGC on a DB-5MS column (30 m x 0.25 mm x 0.25 μm) and determined by HRMS. The identi- fication of mono- to tri-CDD/Fs was based on the retention times of 13C-labelled standard and the abundance ratios of the two exacted mass-to-charge ratios. The quantitative analysis was performed using the ratios of the integrated areas of the 13C-labelled standards. This method had the recoveries ranging from 66.6% to 112.5% and the relative standard deviations (RSD) ranging from 19.9% to 40.5% (n = 5). The limits of detection (LODs) of this method for the mono- to tri-CDD/Fs were ranging from 0.027 to 0.485 μg/L. Three stack gas samples from waste incinerators were measured using this method, with the recoveries ranging from 85.7% to 137.0% and the concentrations ranging from 11.4 to 9,183 pg/Nm3. The results indicated that the method can be applied to the precise determination of mono- to tri-CDD/Fs at trace level in stack gas.

  10. High critical currents in iron-clad superconducting MgB2 wires.

    Science.gov (United States)

    Jin, S; Mavoori, H; Bower, C; van Dover, R B

    2001-05-31

    Technically useful bulk superconductors must have high transport critical current densities, Jc, at operating temperatures. They also require a normal metal cladding to provide parallel electrical conduction, thermal stabilization, and mechanical protection of the generally brittle superconductor cores. The recent discovery of superconductivity at 39 K in magnesium diboride (MgB2) presents a new possibility for significant bulk applications, but many critical issues relevant for practical wires remain unresolved. In particular, MgB2 is mechanically hard and brittle and therefore not amenable to drawing into the desired fine-wire geometry. Even the synthesis of moderately dense, bulk MgB2 attaining 39 K superconductivity is a challenge because of the volatility and reactivity of magnesium. Here we report the successful fabrication of dense, metal-clad superconducting MgB2 wires, and demonstrate a transport Jc in excess of 85,000 A cm-2 at 4.2 K. Our iron-clad fabrication technique takes place at ambient pressure, yet produces dense MgB2 with little loss of stoichiometry. While searching for a suitable cladding material, we found that other materials dramatically reduced the critical current, showing that although MgB2 itself does not show the 'weak-link' effect characteristic of the high-Tc superconductors, contamination does result in weak-link-like behaviour.

  11. High critical currents in iron-clad superconducting MgB2 wires

    Science.gov (United States)

    Jin, S.; Mavoori, H.; Bower, C.; van Dover, R. B.

    2001-05-01

    Technically useful bulk superconductors must have high transport critical current densities, Jc, at operating temperatures. They also require a normal metal cladding to provide parallel electrical conduction, thermal stabilization, and mechanical protection of the generally brittle superconductor cores. The recent discovery of superconductivity at 39K in magnesium diboride (MgB2) presents a new possibility for significant bulk applications, but many critical issues relevant for practical wires remain unresolved. In particular, MgB2 is mechanically hard and brittle and therefore not amenable to drawing into the desired fine-wire geometry. Even the synthesis of moderately dense, bulk MgB2 attaining 39K superconductivity is a challenge because of the volatility and reactivity of magnesium. Here we report the successful fabrication of dense, metal-clad superconducting MgB2 wires, and demonstrate a transport Jc in excess of 85,000Acm-2 at 4.2K. Our iron-clad fabrication technique takes place at ambient pressure, yet produces dense MgB2 with little loss of stoichiometry. While searching for a suitable cladding material, we found that other materials dramatically reduced the critical current, showing that although MgB2 itself does not show the `weak-link' effect characteristic of the high-Tc superconductors, contamination does result in weak-link-like behaviour.

  12. High pressure rheology of gas hydrate formed from multiphase systems using modified Couette rheometer

    Science.gov (United States)

    Pandey, Gaurav; Linga, Praveen; Sangwai, Jitendra S.

    2017-02-01

    Conventional rheometers with concentric cylinder geometries do not enhance mixing in situ and thus are not suitable for rheological studies of multiphase systems under high pressure such as gas hydrates. In this study, we demonstrate the use of modified Couette concentric cylinder geometries for high pressure rheological studies during the formation and dissociation of methane hydrate formed from pure water and water-decane systems. Conventional concentric cylinder Couette geometry did not produce any hydrates in situ and thus failed to measure rheological properties during hydrate formation. The modified Couette geometries proposed in this work observed to provide enhanced mixing in situ, thus forming gas hydrate from the gas-water-decane system. This study also nullifies the use of separate external high pressure cell for such measurements. The modified geometry was observed to measure gas hydrate viscosity from an initial condition of 0.001 Pa s to about 25 Pa s. The proposed geometries also possess the capability to measure dynamic viscoelastic properties of hydrate slurries at the end of experiments. The modified geometries could also capture and mimic the viscosity profile during the hydrate dissociation as reported in the literature. The present study acts as a precursor for enhancing our understanding on the rheology of gas hydrate formed from various systems containing promoters and inhibitors in the context of flow assurance.

  13. Upgrading low-quality natural gas by means of highly performing polymer membranes

    Energy Technology Data Exchange (ETDEWEB)

    Stern, S.A. [Syracuse Univ., NY (United States)

    1995-04-01

    The objective of the present study is to assess the potential usefulness of membrane separation processes for removing acid gases (CO{sub 2} and H{sub 2}S) from low-quality natural gas. Nonporous {open_quotes}dense{close_quotes} (homogeneous) membranes made from new, highly gas-selective polymers are being evaluated for this purpose. The project comprises gas permeability and separation measurements with CH{sub 4}/CO{sub 2} and CH{sub 4}/CO{sub 2}/H{sub 2}S mixtures having compositions in ranges found in low-quality natural gas. Process design studies and economic evaluations are also being made to determine the cost of upgrading low-quality natural gas with the most promising membranes. Until recently, the membranes used in this study were made from new types of polyimides synthesized in our laboratory. The polyimide membranes were found to exhibit a very high CO{sub 2}/CH{sub 4} selectivity but a relatively low H{sub 2}S/CH{sub 4} selectivity. Therefore, different types of polymers that exhibit a high H{sub 2}S/CH{sub 4} selectivity are also being evaluated.

  14. Avoided criticality in near-optimally doped high-temperature superconductors

    Science.gov (United States)

    Haule, Kristjan; Kotliar, Gabriel

    2007-09-01

    We study the crossover from the underdoped to the overdoped regime of the t-J model within a plaquette dynamical mean field approach. We find that the shortest electron lifetime occurs near optimal doping where the superconducting critical temperature is maximal. The mean field theory provides a simple physical picture of this effect. In the underdoped regime, the charge carriers propagate coherently among spin singlets, formed by the superexchange interaction. In the overdoped, large carrier concentration regime, the Kondo effect dominates resulting in spin-charge composite quasiparticles which are also coherent. Separating these two Fermi liquid regimes, there is a critical doping where the superexchange and the Kondo interaction balance each other. At this point, the normal phase is highly incoherent and the optical conductivity exhibits power law behavior at intermediate frequencies. The onset of superconductivity restores coherence, causing the appearance of a resonance in the spin channel.

  15. Onset of quantum criticality in the topological-to-nematic transition in a two-dimensional electron gas at filling factor ν =5 /2

    Science.gov (United States)

    Schreiber, K. A.; Samkharadze, N.; Gardner, G. C.; Biswas, Rudro R.; Manfra, M. J.; Csáthy, G. A.

    2017-07-01

    Under hydrostatic pressure, the ground state of a two-dimensional electron gas at ν =5 /2 changes from a fractional quantum Hall state to the stripe phase. By measuring the energy gap of the fractional quantum Hall state and of the onset temperature of the stripe phase, we mapped out a phase diagram of these competing phases in the pressure-temperature plane. Our data highlight the dichotomy of two descriptions of the half-filled Landau level near the quantum critical point: one based on electrons and another on composite fermions.

  16. Prediction for supersaturated total dissolved gas in high-dam hydropower projects

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The supersaturated total dissolved gas(TDG)generated during high dam spills may cause gas bubble disease for fish and ultimately endanger their existence.As more and more high-dam hydropower projects have been constructed in China,the environmental assessment of the supersaturated TDG is becoming more and more important.It is of great importance for quantitative impact assessment of the supersaturated TDG of high dams and for the construction of ecological friendly high-dam hydropower projects.Based on the conceptual summarization of the TDG production process,the TDG prediction model for high-dam projects,in which the ski-jump energy dissipation is adopted,is developed in the paper.The model is validated by field data and employed in the TDG prediction of a high-dam hydropower project to be built in southwest China.

  17. Effect of Distributor Design on Gas-Liquid Distribution in Monolithic Bed at High Gas/Liquid Ratios

    Institute of Scientific and Technical Information of China (English)

    周媛; AL-DAHHAN Muthanna; DUDUKOVIC Milorad; 刘辉

    2012-01-01

    Experiments were carried out to investigate the liquid flow distribution at high gas/liquid ratios in a cold model monolith bed of a 0.048 m diameter with 62 cells per cm2.Three types of distributor for the liquid distribu-tion were used to evaluate their distribution performance.Local liquid saturation in individual channels was meas-ured using 16 single-point optical fiber probes mounted inside the channels.The results indicate that 1) The optical fiber probe technique can measure phase distribution in the monolith bed;2) Liquid saturation distribution along the radial direction of the monolith bed is not uniform and the extent of non-uniformity depends on the distributor de-sign and phase velocities;and 3) The tube array distributor provides superior liquid distribution performance over the showerhead and nozzle distributors.

  18. Arrays of Ultrathin CdS Nanoflakes with High-Energy Surface for Efficient Gas Detection.

    Science.gov (United States)

    Liu, Xiao-Hua; Yin, Peng-Fei; Kulinich, Sergei A; Zhou, Yu-Zhu; Mao, Jing; Ling, Tao; Du, Xi-Wen

    2017-01-11

    It is fascinating and challenging to endow conventional materials with unprecedented properties. For instance, cadmium sulfide (CdS) is an important semiconductor with excellent light response; however, its potential in gas-sensing was underestimated owing to relatively low chemical activity and poor electrical conductivity. Herein, we demonstrate that an ideal architecture, ultrathin nanoflake arrays (NFAs), can improve significantly gas-sensing properties of CdS material. The CdS NFAs are grown directly on the interdigitated electrode to expose large surface area. Their thickness is reduced below the double Debye length of CdS, permitting to achieve a full depletion of carriers. Particularly, the prepared CdS nanoflakes are enclosed with high-energy {0001} facets exposed, which provides more active sites for gas adsorption. Moreover, the NFAs exhibit the light-trapping effect, which further enhances their gas sensitivity. As a result, the as-prepared CdS NFAs demonstrate excellent gas-sensing and light-response properties, thus being capable of dual gas and light detection.

  19. High Gas Surface Densities yet Low UV Attenuation in z $\\sim$ 1 Disc Galaxies

    CERN Document Server

    Nordon, Raanan

    2016-01-01

    The gas in galaxies is both the fuel for star formation and a medium that attenuates the light of the young stars. We study the relations between UV attenuation, spectral slope, star formation rates, and molecular gas surface densities in a sample of 28 z$\\sim$1 and a reference sample of 32 z$\\sim$0 galaxies that are detected in CO, far-infrared, and rest frame UV. The samples are dominated by disc-like galaxies close to the main SFR--mass relation. We find that the location of the z$\\sim$1 galaxies on the IRX-$\\beta$ plane is correlated with their gas-depletion time-scale $\\tau_{dep}$ and can predict $\\tau_{dep}$ with a standard deviation of 0.16 dex. We use IRX-$\\beta$ to estimate the mean total gas column densities at the locations of star formation in the galaxies, and compare them to the mean molecular gas surface densities as measured from CO. We confirm previous results regarding high $N_H/A_V$ in z$\\sim$1 galaxies. We estimate an increase in the gas filling factor by a factor of 4--6 from z$\\sim$0 to ...

  20. The ⋋ Structure of the Heat Capacity of an Ideal Gas in the Critical Region of Bose-Einstein Condensation for Various Mesoscopic Traps

    Science.gov (United States)

    Tarasov, S. V.

    2016-11-01

    The features of the ⋋ structure of the heat capacity of an ideal gas of Bose atoms, which is confined in arbitrarily shaped and sized mesoscopic traps, are considered on the basis of a general exact description of the Bose-Einstein condensation. The main attention is paid to the boundarycondition role in the critical region, in which the heat capacity is described by a self-similar function that is sensitive to perturbations of the confining potential and the boundary-condition variation. Various traps, which allow one to experimentally study the influence of the boundary conditions on the shape of the ⋋ structure of the heat capacity and observe variations in other thermodynamic parameters due to the corresponding rearrangement of the self-similar structure of the critical region, are considered.

  1. Anisotropy of the critical current in MgB2 tapes made of high energy milled precursor powder

    DEFF Research Database (Denmark)

    Hässler, W.; Kovac, P.; Eisterer, M.;

    2010-01-01

    For applications of MgB2 wires or tapes, high critical currents in high magnetic fields are essential. By using tapes in superconducting coils the anisotropic behaviour of the critical current, i.e. the dependence on the direction of the external field in relation to the tape surface, has...

  2. Is Pulse Oximetry Useful for Screening Neonates for Critical Congenital Heart Disease at High Altitudes?

    Science.gov (United States)

    Hoffman, Julien I E

    2016-06-01

    Now that pulse oximetry is used widely to screen for critical congenital heart disease, it is time to consider whether this screening method is applicable to those who live at high altitudes. Consideration of basic physical principles and reports from the literature indicate that not only is the 95 % cutoff point for arterial oxygen saturation incorrect at high altitudes, but the lower saturations are accompanied by greater variability and therefore there is the possibility of a greater percentage of false-positive screening tests at high altitudes. Because of ethnic differences in response to high altitudes, normative data will have to be collected separately in different countries and perhaps for different ethnic groups.

  3. Engineering study - alternatives for SHMS high temperature/moisture gas sample conditioners for the aging waste facility

    Energy Technology Data Exchange (ETDEWEB)

    THOMPSON, J.F.

    1999-06-02

    The Standard Hydrogen Monitoring Systems have been experiencing high temperature/moisture problems with gas samples from the Aging Waste Tanks. These moist hot gas samples have stopped the operation of the SHMS units on tanks AZ-101, AZ-102, and AY-102. This study looks at alternatives for gas sample conditioners for the Aging Waste Facility.

  4. High effectiveness liquid droplet/gas heat exchanger for space power applications

    Science.gov (United States)

    Bruckner, A. P.; Mattick, A. T.

    A high-effectiveness liquid droplet/gas heat exchanger (LDHX) concept for thermal management in space is described. Heat is transferred by direct contact between fine droplets (≈ 100-300 μm dia.) of a suitable low vapor pressure liquid and an inert working gas. Complete separation of the droplet and gas media in the zero-g environment is accomplished by configuring the LDHX as a vortex chamber. The large heat transfer area presented by the small droplets permits heat exchanger effectiveness of 0.9-0.95 in a compact, lightweight geometry which avoids many of the limitations of conventional plate and fin or tube and shell heat exchangers, such as their tendency toward single point failure. The application of the LDHX in a high temperature Brayton cycle is discussed to illustrate the performance and operational characteristics of this new heat exchanger concept.

  5. High-Density Fiber Optical Sensor and Instrumentation for Gas Turbine Operation Condition Monitoring

    Directory of Open Access Journals (Sweden)

    Hua Xia

    2013-01-01

    Full Text Available Gas turbine operation control is normally based on thermocouple-measured exhaust temperatures. Due to radiation shielding and bulky package, it is difficult to provide high spatial resolution for measuring can-to-can combustion temperature profile at the exhaust duct. This paper has demonstrated that wavelength-division-multiplexing-based fiber Bragg grating sensors could provide high spatial resolution steady and dynamic temperature measurements. A robust sensor package can be designed with either circumferential sensing cable or radial sensing rake for quasi-distributing multiple fiber sensors in the gas turbine environment. The field validations have demonstrated that quasi-distributed fiber sensors have not only demonstrated its temperature measurement accuracy compared to existing thermocouple sensors but also shown its unique dynamic response amplitude and power spectra that could be utilized for gas turbine transient operation condition monitoring and diagnostics.

  6. High-efficiency gas heat pump air-conditioner equipped with absorption refrigerator

    Science.gov (United States)

    Imai, Yosuke; Ohashi, Toshinori; Okamoto, Hiroaki; Hihara, Eiji; Kawakami, Ryuichiro

    On conventional gas heat pump(GHP), waste heat from gas engine that uses as driving source is emitted into outside. So from the standpoint of efficient use of waste heat, it is assumed that waste heat from gas engine is used as driving source of absorption chiller, and high temperature condensate refrigerant in GHP is subcooled to middle temperature by cold source from absorption cycle, and as a result, GHP makes more efficiency. However, in equipping GHP with absorption cycle, downsizing and high-efficiency of absorption cycle is required. In this study, air-cooled subcooled adiabatic absorber is focused and physical phenomenon in it is analyzed, and finally one perception of the optimized designing is shown.

  7. Investigation of arterial gas occlusions. [effect of noncondensable gases on high performance heat pipes

    Science.gov (United States)

    Saaski, E. W.

    1974-01-01

    The effect of noncondensable gases on high-performance arterial heat pipes was investigated both analytically and experimentally. Models have been generated which characterize the dissolution of gases in condensate, and the diffusional loss of dissolved gases from condensate in arterial flow. These processes, and others, were used to postulate stability criteria for arterial heat pipes under isothermal and non-isothermal condensate flow conditions. A rigorous second-order gas-loaded heat pipe model, incorporating axial conduction and one-dimensional vapor transport, was produced and used for thermal and gas studies. A Freon-22 (CHCIF2) heat pipe was used with helium and xenon to validate modeling. With helium, experimental data compared well with theory. Unusual gas-control effects with xenon were attributed to high solubility.

  8. High effectiveness liquid droplet/gas heat exchanger for space power applications

    Science.gov (United States)

    Bruckner, A. P.; Mattick, A. T.

    1983-01-01

    A high-effectiveness liquid droplet/gas heat exchanger (LDHX) concept for thermal management in space is described. Heat is transferred by direct contact between fine droplets (approximately 100-300 microns in diameter) of a suitable low vapor pressure liquid and an inert working gas. Complete separation of the droplet and gas media in the zero-g environment is accomplished by configuring the LDHX as a vortex chamber.The large heat transfer area presented by the small droplets permits heat exchanger effectiveness of 0.9-0.95 in a compact, lightweight geometry which avoids many of the limitations of conventional plate and fin or tube and shell heat exchangers, such as their tendency toward single point failure. The application of the LDHX in a high temperature Brayton cycle is discussed to illustrate the performance and operational characteristics of this new heat exchanger concept.

  9. Self-heated silicon nanowires for high performance hydrogen gas detection

    Science.gov (United States)

    Ahn, Jae-Hyuk; Yun, Jeonghoon; Moon, Dong-Il; Choi, Yang-Kyu; Park, Inkyu

    2015-03-01

    Self-heated silicon nanowire sensors for high-performance, ultralow-power hydrogen detection have been developed. A top-down nanofabrication method based on well-established semiconductor manufacturing technology was utilized to fabricate silicon nanowires in wafer scale with high reproducibility and excellent compatibility with electronic readout circuits. Decoration of palladium nanoparticles onto the silicon nanowires enables sensitive and selective detection of hydrogen gas at room temperature. Self-heating of silicon nanowire sensors allows us to enhance response and recovery performances to hydrogen gas, and to reduce the influence of interfering gases such as water vapor and carbon monoxide. A short-pulsed heating during recovery was found to be effective for additional reduction of operation power as well as recovery characteristics. This self-heated silicon nanowire gas sensor will be suitable for ultralow-power applications such as mobile telecommunication devices and wireless sensing nodes.

  10. A critical comparison of two high-throughput ascorbate analyses methods for plant samples.

    Science.gov (United States)

    Ueda, Yoshiaki; Wu, Linbo; Frei, Michael

    2013-09-01

    Ascorbate (AsA) is an important metabolite involved in stress response and development of plants. Therefore it is necessary to quantify the AsA content in many fields of plant science, including high throughput and critical applications. In this study we compared two different microplate-based AsA assays, which are suitable for high throughput applications: an ascorbate oxidase (AO)-based assay and a dipyridyl (DPD)-based assay. These methods were compared in critical applications, i.e. (i) when AsA concentrations were very low such as in apoplastic extracts, (ii) when plants contained pigments interfering with the spectrometric measurements, and (iii) when plants contained high iron concentration interfering with the color reactions. The precision of measurements was higher with the DPD method, as illustrated by higher recovery rates of internal AsA standards. On the other hand, the AO method was more sensitive to low levels of AsA. This was an advantage in determining apoplastic AsA concentration in rice, which was substantially lower than that of whole tissues. The AO method also had the advantage that plant pigments and high iron concentrations in plants tissues did not interfere with the analysis, as opposed to the DPD assay. In conclusion, both assays had advantages and the choice of a suitable method depends on the specific application.

  11. Facility Configuration Study of the High Temperature Gas-Cooled Reactor Component Test Facility

    Energy Technology Data Exchange (ETDEWEB)

    S. L. Austad; L. E. Guillen; D. S. Ferguson; B. L. Blakely; D. M. Pace; D. Lopez; J. D. Zolynski; B. L. Cowley; V. J. Balls; E.A. Harvego, P.E.; C.W. McKnight, P.E.; R.S. Stewart; B.D. Christensen

    2008-04-01

    A test facility, referred to as the High Temperature Gas-Cooled Reactor Component Test Facility or CTF, will be sited at Idaho National Laboratory for the purposes of supporting development of high temperature gas thermal-hydraulic technologies (helium, helium-Nitrogen, CO2, etc.) as applied in heat transport and heat transfer applications in High Temperature Gas-Cooled Reactors. Such applications include, but are not limited to: primary coolant; secondary coolant; intermediate, secondary, and tertiary heat transfer; and demonstration of processes requiring high temperatures such as hydrogen production. The facility will initially support completion of the Next Generation Nuclear Plant. It will secondarily be open for use by the full range of suppliers, end-users, facilitators, government laboratories, and others in the domestic and international community supporting the development and application of High Temperature Gas-Cooled Reactor technology. This pre-conceptual facility configuration study, which forms the basis for a cost estimate to support CTF scoping and planning, accomplishes the following objectives: • Identifies pre-conceptual design requirements • Develops test loop equipment schematics and layout • Identifies space allocations for each of the facility functions, as required • Develops a pre-conceptual site layout including transportation, parking and support structures, and railway systems • Identifies pre-conceptual utility and support system needs • Establishes pre-conceptual electrical one-line drawings and schedule for development of power needs.

  12. Portable mixed abrasive water jet equipment for rescue in high gas mine shaft

    Institute of Scientific and Technical Information of China (English)

    ZENG Rui; DU Chang-long; XU Rui; ZHAO Jing

    2011-01-01

    In order to rescue a trapped miner and clean out roadways quickly in a high gas mine shaft after a mining mishap, a special portable cold-cutting equipment is needed, the main technology parameters were calculated according to the advanced cold-cutting technology of high pressure abrasive water jet and the portable mixed abrasive water jet equipment (PAWE) was designed to meet the needs of emergency rescue in high gas mine shafts. Tested the PAWE in a high gas environment, and the result shows that the maximum cutting depth of solid iron pipe is 18 mm and the recoilforce of the sprayer is 28.9 N under the conditions that actual cutting pressure is 29 MPa, starting target distance is 10 mm, cutting speed is 180 mm/min and concentration of abrasive is 32%. The course of the experiment in the high gas environment was smooth and continuous, without any explosion. The PAWE is easy to move and operate, but the nozzle which was worn badly in the sprayer should be changed every 8 minutes.

  13. Study of DC Circuit Breaker of H2-N2 Mixture Gas for High Voltage

    Science.gov (United States)

    Shiba, Yuji; Morishita, Yukinaga; Kaneko, Shuhei; Okabe, Shigemitsu; Mizoguchi, Hitoshi; Yanabu, Satoru

    Global warming caused by CO2 etc. is a field where the concern is very high. Especially, automobile emissions are problem for it. Therefore, the hybrid car is widely development and used recently. Hybrid car used electric power and gasoline. So, the car reduces CO2. Hybrid car has engine and motor. To rotate the motor, hybrid car has battery. This battery is large capacity. Therefore, the relay should interrupt high DC current for the switch of the motor and the engine. So, hybrid car used hydrogen gas filling relay We studied interruption test for the research of a basic characteristic of hydrogen gas. DC current has not current zero point. So, it is necessary to make the current zero by high arc voltage and forcible current zero point. The loss coefficient and arc voltage of hydrogen is high. Therefore, we studied interruption test for used high arc voltage. We studied interruption test and dielectric breakdown test of air, pure Hydrogen, and Hydrogen- nitrogen mixture gas. As a result, we realized H2-N2(80%-20%) is the best gas.

  14. Dynamics of pulsed laser ablation plasmas in high-density CO2 near the critical point investigated by time-resolved shadowgraph imaging

    Science.gov (United States)

    Urabe, Keiichiro; Kato, Toru; Himeno, Shohei; Kato, Satoshi; Stauss, Sven; Baba, Motoyoshi; Suemoto, Tohru; Terashima, Kazuo

    2013-09-01

    Pulsed laser ablation (PLA) plasmas generated in high-density gases and liquids are promising for the synthesis of nanomaterials. However, the characteristics of such plasmas are still not well understood. In order to improve the understandings of PLA plasmas in high-density fluids including gases, liquids, and supercritical fluids (SCFs), we have investigated the dynamics of PLA plasmas in high-density carbon dioxide (CO2) . We report on experimental results of time-resolved shadowgraph imaging, from the generation of plasma plume to the extinction of cavitation bubbles. Shadowgraph images revealed that the PLA plasma dynamics showed two distinct behaviors. These are divided by gas-liquid coexistence curve and the so-called Widom line, which separates gas-like and liquid-like SCF domains. Furthermore, cavitation bubble observed in liquid CO2 near the critical point showed peculiar characteristics, the formation of an inner bubble and an outer shell structure, which so far has never been reported. The experiments indicate that thermophysical properties of PLA plasmas can be tuned by controlling solvent temperature and pressure around the critical point, which may be useful for materials processing. This work was supported financially in part by a Grant-in-Aid for Scientific Research on Innovative Areas (No. 21110002) from the Ministry of Education, Culture, Sports, Science, and Technology of Japan.

  15. On the gas dependence of thermal transpiration and a critical appraisal of correction methods for capacitive diaphragm gauges

    CERN Document Server

    Daudé, Barthélémy; Janssen, Christof

    2013-01-01

    Thermal transpiration effects are commonly encountered in low pressure measurements with capacitance diaphragm gauges. They arise from the temperature difference between the measurement volume and the temperature stabilised manometer. Several approaches have been proposed to correct for the pressure difference, but surface and geometric effects usually require that the correction is determined for each gas type and gauge individually. Common (semi) empirical corrections are based on studies of atoms or small molecules. We present a simple calibration method for diaphragm gauges and compare transpiration corrections for argon and styrene at pressures above 1 Pa. We find that characteristic pressures at which the pressure difference reaches half its maximum value, are compatible with the universal scaling p_{1/2} = 2 \\{\\eta} \\cdot \\{v_{th}} / d, thus essentially depending on gas viscosity \\eta, thermal molecular speed v_{th} and gauge tubing diameter d. This contradicts current recommendations based on the Taka...

  16. Development of a resonant laser ionization gas cell for high-energy, short-lived nuclei

    CERN Document Server

    Sonoda, T; Tomita, H; Sakamoto, C; Takatsuka, T; Furukawa, T; Iimura, H; Ito, Y; Kubo, T; Matsuo, Y; Mita, H; Naimi, S; Nakamura, S; Noto, T; Schury, P; Shinozuka, T; Wakui, T; Miyatake, H; Jeong, S; Ishiyama, H; Watanabe, Y X; Hirayama, Y; Okada, K; Takamine, A

    2012-01-01

    A new laser ion source configuration based on resonant photoionization in a gas cell has been developed at RIBF RIKEN. This system is intended for the future PArasitic RI-beam production by Laser Ion-Source (PALIS) project which will be installed at RIKEN's fragment separator, BigRIPS. A novel implementation of differential pumping, in combination with a sextupole ion beam guide (SPIG), has been developed. A few small scroll pumps create a pressure difference from 1000 hPa - 10^-3 Pa within a geometry drastically miniaturized compared to conventional systems. This system can utilize a large exit hole for fast evacuation times, minimizing the decay loss for short-lived nuclei during extraction from a buffer gas cell, while sufficient gas cell pressure is maintained for stopping high energy RI-beams. In spite of the motion in a dense pressure gradient, the photo-ionized ions inside the gas cell are ejected with an assisting force gas jet and successfully transported to a high-vacuum region via SPIG followed by ...

  17. High-intensity femtosecond laser absorption by rare-gas clusters

    Institute of Scientific and Technical Information of China (English)

    李邵辉; 王成; 刘建胜; 王向欣; 朱频频; 李儒新; 倪国权; 徐至展

    2003-01-01

    The energy absorption efficiency of high-intensity (~ 1016W/cm2) femtosecond laser pulses in a dense jet of large rare-gas clusters has been measured. Experimental results show that the energy absorption efficiency is strongly dependent on the cluster size and can be higher than 90%. The measurement of the ion energy indicates that the average ion energies of argon and xenon can be as high as 90 and 100keV, respectively. The dependence of the average energy of the ions on the cluster size is also measured. At comparatively low gas backing pressure, the average ion energies of argon and xenon increase with increasing gas backing pressure. The average ion energy of argon becomes saturated gradually with further increase of the gas backing pressure. For xenon, the average ion energy drops a little after the gas backing pressure exceeds 9 bar (3.2×105 atoms/cluster). The result showing the existence of a maximum average ion energy has been interpreted within the framework of the microplasma sphere model.

  18. Porous nuclear fuel element for high-temperature gas-cooled nuclear reactors

    Science.gov (United States)

    Youchison, Dennis L.; Williams, Brian E.; Benander, Robert E.

    2011-03-01

    Porous nuclear fuel elements for use in advanced high temperature gas-cooled nuclear reactors (HTGR's), and to processes for fabricating them. Advanced uranium bi-carbide, uranium tri-carbide and uranium carbonitride nuclear fuels can be used. These fuels have high melting temperatures, high thermal conductivity, and high resistance to erosion by hot hydrogen gas. Tri-carbide fuels, such as (U,Zr,Nb)C, can be fabricated using chemical vapor infiltration (CVI) to simultaneously deposit each of the three separate carbides, e.g., UC, ZrC, and NbC in a single CVI step. By using CVI, the nuclear fuel may be deposited inside of a highly porous skeletal structure made of, for example, reticulated vitreous carbon foam.

  19. Porous nuclear fuel element with internal skeleton for high-temperature gas-cooled nuclear reactors

    Science.gov (United States)

    Youchison, Dennis L.; Williams, Brian E.; Benander, Robert E.

    2013-09-03

    Porous nuclear fuel elements for use in advanced high temperature gas-cooled nuclear reactors (HTGR's), and to processes for fabricating them. Advanced uranium bi-carbide, uranium tri-carbide and uranium carbonitride nuclear fuels can be used. These fuels have high melting temperatures, high thermal conductivity, and high resistance to erosion by hot hydrogen gas. Tri-carbide fuels, such as (U,Zr,Nb)C, can be fabricated using chemical vapor infiltration (CVI) to simultaneously deposit each of the three separate carbides, e.g., UC, ZrC, and NbC in a single CVI step. By using CVI, the nuclear fuel may be deposited inside of a highly porous skeletal structure made of, for example, reticulated vitreous carbon foam.

  20. High-density carbon ablator ignition path with low-density gas-filled rugby hohlraum

    Science.gov (United States)

    Amendt, Peter; Ho, Darwin D.; Jones, Ogden S.

    2015-04-01

    A recent low gas-fill density (0.6 mg/cc 4He) cylindrical hohlraum experiment on the National Ignition Facility has shown high laser-coupling efficiency (>96%), reduced phenomenological laser drive corrections, and improved high-density carbon capsule implosion symmetry [Jones et al., Bull. Am. Phys. Soc. 59(15), 66 (2014)]. In this Letter, an ignition design using a large rugby-shaped hohlraum [Amendt et al., Phys. Plasmas 21, 112703 (2014)] for high energetics efficiency and symmetry control with the same low gas-fill density (0.6 mg/cc 4He) is developed as a potentially robust platform for demonstrating thermonuclear burn. The companion high-density carbon capsule for this hohlraum design is driven by an adiabat-shaped [Betti et al., Phys. Plasmas 9, 2277 (2002)] 4-shock drive profile for robust high gain (>10) 1-D ignition performance and large margin to 2-D perturbation growth.

  1. High-density carbon ablator ignition path with low-density gas-filled rugby hohlraum

    Energy Technology Data Exchange (ETDEWEB)

    Amendt, Peter; Ho, Darwin D.; Jones, Ogden S. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

    2015-04-15

    A recent low gas-fill density (0.6 mg/cc {sup 4}He) cylindrical hohlraum experiment on the National Ignition Facility has shown high laser-coupling efficiency (>96%), reduced phenomenological laser drive corrections, and improved high-density carbon capsule implosion symmetry [Jones et al., Bull. Am. Phys. Soc. 59(15), 66 (2014)]. In this Letter, an ignition design using a large rugby-shaped hohlraum [Amendt et al., Phys. Plasmas 21, 112703 (2014)] for high energetics efficiency and symmetry control with the same low gas-fill density (0.6 mg/cc {sup 4}He) is developed as a potentially robust platform for demonstrating thermonuclear burn. The companion high-density carbon capsule for this hohlraum design is driven by an adiabat-shaped [Betti et al., Phys. Plasmas 9, 2277 (2002)] 4-shock drive profile for robust high gain (>10) 1-D ignition performance and large margin to 2-D perturbation growth.

  2. Application of high-precision 3D seismic technology to shale gas exploration: A case study of the large Jiaoshiba shale gas field in the Sichuan Basin

    Directory of Open Access Journals (Sweden)

    Zuqing Chen

    2016-03-01

    Full Text Available The accumulation pattern of the marine shale gas in South China is different from that in North America. The former has generally thin reservoirs and complex preservation conditions, so it is difficult to make a fine description of the structural features of shale formations and to reflect accurately the distribution pattern of high-quality shale by using the conventional 2D and 3D seismic exploration technology, which has an adverse effect on the successful deployment of horizontal wells. In view of this, high-precision 3D seismic prospecting focusing on lithological survey was implemented to make an accurate description of the distribution of shale gas sweet spots so that commercial shale gas production can be obtained. Therefore, due to the complex seismic geological condition of Jiaoshiba area in Fuling, SE Sichuan Basin, the observation system of high-precision 3D seismic acquisition should have such features as wide-azimuth angles, small trace intervals, high folds, uniform vertical and horizontal coverage and long spread to meet the needs of the shale gas exploration in terms of structural interpretation, lithological interpretation and fracture prediction. Based on this idea, the first implemented high-precision 3D seismic exploration project in Jiaoshiba area played an important role in the discovery of the large Jiaoshiba shale gas field. Considering that the high-quality marine shale in the Sichuan Basin shows the characteristics of multi-layer development from the Silurian system to the Cambrian system, the strategy of shale gas stereoscopic exploration should be implemented to fully obtain the oil and gas information of the shallow, medium and deep strata from the high-precision 3D seismic data, and ultimately to expand the prospecting achievements in an all-round way to balance the high upstream exploration cost, and to continue to push the efficient shale gas exploration and development process in China.

  3. High-precision percolation thresholds and Potts-model critical manifolds from graph polynomials

    Science.gov (United States)

    >Jesper Lykke Jacobsen,

    2014-04-01

    The critical curves of the q-state Potts model can be determined exactly for regular two-dimensional lattices G that are of the three-terminal type. This comprises the square, triangular, hexagonal and bow-tie lattices. Jacobsen and Scullard have defined a graph polynomial PB(q, v) that gives access to the critical manifold for general lattices. It depends on a finite repeating part of the lattice, called the basis B, and its real roots in the temperature variable v = eK - 1 provide increasingly accurate approximations to the critical manifolds upon increasing the size of B. Using transfer matrix techniques, these authors computed PB(q, v) for large bases (up to 243 edges), obtaining determinations of the ferromagnetic critical point vc > 0 for the (4, 82), kagome, and (3, 122) lattices to a precision (of the order 10-8) slightly superior to that of the best available Monte Carlo simulations. In this paper we describe a more efficient transfer matrix approach to the computation of PB(q, v) that relies on a formulation within the periodic Temperley-Lieb algebra. This makes possible computations for substantially larger bases (up to 882 edges), and the precision on vc is hence taken to the range 10-13. We further show that a large variety of regular lattices can be cast in a form suitable for this approach. This includes all Archimedean lattices, their duals and their medials. For all these lattices we tabulate high-precision estimates of the bond percolation thresholds pc and Potts critical points vc. We also trace and discuss the full Potts critical manifold in the (q, v) plane, paying special attention to the antiferromagnetic region v < 0. Finally, we adapt the technique to site percolation as well, and compute the polynomials PB(p) for certain Archimedean and dual lattices (those having only cubic and quartic vertices), using very large bases (up to 243 vertices). This produces the site percolation thresholds pc to a precision of the order of 10-9.

  4. Adsorption and reaction of trace gas-phase organic compounds on atmospheric water film surfaces: a critical review.

    Science.gov (United States)

    Donaldson, D J; Valsaraj, Kalliat T

    2010-02-01

    The air-water interface in atmospheric water films of aerosols and hydrometeors (fog, mist, ice, rain, and snow) presents an important surface for the adsorption and reaction of many organic trace gases and gaseous reactive oxidants (hydroxyl radical (OH(.)), ozone (O(3)), singlet oxygen (O(2)((1)Delta(g))), nitrate radicals (NO(3)(.)), and peroxy radicals (RO(2)(.)). Knowledge of the air-water interface partition constant of hydrophobic organic species is necessary for elucidating the significance of the interface in atmospheric fate and transport. Various methods of assessing both experimental and theoretical values of the thermodynamic partition constant and adsorption isotherm are described in this review. Further, the reactivity of trace gases with gas-phase oxidants (ozone and singlet oxygen) at the interface is summarized. Oxidation products are likely to be more water-soluble and precursors for secondary organic aerosols in hydrometeors. Estimation of characteristic times shows that heterogeneous photooxidation in water films can compete effectively with homogeneous gas-phase reactions for molecules in the atmosphere. This provides further support to the existing thesis that reactions of organic compounds at the air-water interface should be considered in gas-phase tropospheric chemistry.

  5. Magnetocaloric properties and critical behavior of high relative cooling power FeNiB nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Chaudhary, V. [Interdisciplinary Graduate School, Nanyang Technological University, Singapore 639798 (Singapore); Energy Research Institute @NTU, Nanyang Technological University, Singapore 637553 (Singapore); School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Maheswar Repaka, D. V.; Chaturvedi, A.; Ramanujan, R. V., E-mail: ramanujan@ntu.edu.sg [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Sridhar, I. [School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

    2014-10-28

    Low cost magnetocaloric nanomaterials have attracted considerable attention for energy efficient applications. We report a very high relative cooling power (RCP) in a study of the magnetocaloric effect in quenched FeNiB nanoparticles. RCP increases from 89.8 to 640 J kg{sup −1} for a field change of 1 and 5 T, respectively, these values are the largest for rare earth free iron based magnetocaloric nanomaterials. To investigate the magnetocaloric behavior around the Curie temperature (T{sub C}), the critical behavior of these quenched nanoparticles was studied. Detailed analysis of the magnetic phase transition using the modified Arrott plot, Kouvel-Fisher method, and critical isotherm plots yields critical exponents of β = 0.364, γ = 1.319, δ = 4.623, and α = −0.055, which are close to the theoretical exponents obtained from the 3D-Heisenberg model. Our results indicate that these FeNiB nanoparticles are potential candidates for magnetocaloric fluid based heat pumps and low grade waste heat recovery.

  6. Magnetocaloric properties and critical behavior of high relative cooling power FeNiB nanoparticles

    Science.gov (United States)

    Chaudhary, V.; Maheswar Repaka, D. V.; Chaturvedi, A.; Sridhar, I.; Ramanujan, R. V.

    2014-10-01

    Low cost magnetocaloric nanomaterials have attracted considerable attention for energy efficient applications. We report a very high relative cooling power (RCP) in a study of the magnetocaloric effect in quenched FeNiB nanoparticles. RCP increases from 89.8 to 640 J kg-1 for a field change of 1 and 5 T, respectively, these values are the largest for rare earth free iron based magnetocaloric nanomaterials. To investigate the magnetocaloric behavior around the Curie temperature (TC), the critical behavior of these quenched nanoparticles was studied. Detailed analysis of the magnetic phase transition using the modified Arrott plot, Kouvel-Fisher method, and critical isotherm plots yields critical exponents of β = 0.364, γ = 1.319, δ = 4.623, and α = -0.055, which are close to the theoretical exponents obtained from the 3D-Heisenberg model. Our results indicate that these FeNiB nanoparticles are potential candidates for magnetocaloric fluid based heat pumps and low grade waste heat recovery.

  7. High-power gas-discharge excimer ArF, KrCl, KrF and XeCl lasers utilising two-component gas mixtures without a buffer gas

    Energy Technology Data Exchange (ETDEWEB)

    Razhev, A M; Kargapol' tsev, E S [Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation); Churkin, D S [Novosibirsk State University, Novosibirsk (Russian Federation)

    2016-03-31

    Results of an experimental study of the influence of a gas mixture (laser active medium) composition on an output energy and total efficiency of gas-discharge excimer lasers on ArF* (193 nm), KrCl* (222 nm), KrF* (248 nm) and XeCl* (308 nm) molecules operating without a buffer gas are presented. The optimal ratios of gas components (from the viewpoint of a maximum output energy) of an active medium are found, which provide an efficient operation of laser sources. It is experimentally confirmed that for gas-discharge excimer lasers on halogenides of inert gases the presence of a buffer gas in an active medium is not a necessary condition for efficient operation. For the first time, in two-component gas mixtures of repetitively pulsed gas-discharge excimer lasers on electron transitions of excimer molecules ArF*, KrCl*, KrF* and XeCl*, the pulsed energy of laser radiation obtained under pumping by a transverse volume electric discharge in a low-pressure gas mixture without a buffer gas reached up to 170 mJ and a high pulsed output power (of up to 24 MW) was obtained at a FWHM duration of the KrF-laser pulse of 7 ns. The maximal total efficiency obtained in the experiment with two-component gas mixtures of KrF and XeCl lasers was 0.8%. (lasers)

  8. High-power gas-discharge excimer ArF, KrCl, KrF and XeCl lasers utilising two-component gas mixtures without a buffer gas

    Science.gov (United States)

    Razhev, A. M.; Kargapol'tsev, E. S.; Churkin, D. S.

    2016-03-01

    Results of an experimental study of the influence of a gas mixture (laser active medium) composition on an output energy and total efficiency of gas-discharge excimer lasers on ArF* (193 nm), KrCl* (222 nm), KrF* (248 nm) and XeCl* (308 nm) molecules operating without a buffer gas are presented. The optimal ratios of gas components (from the viewpoint of a maximum output energy) of an active medium are found, which provide an efficient operation of laser sources. It is experimentally confirmed that for gas-discharge excimer lasers on halogenides of inert gases the presence of a buffer gas in an active medium is not a necessary condition for efficient operation. For the first time, in two-component gas mixtures of repetitively pulsed gas-discharge excimer lasers on electron transitions of excimer molecules ArF*, KrCl*, KrF* and XeCl*, the pulsed energy of laser radiation obtained under pumping by a transverse volume electric discharge in a low-pressure gas mixture without a buffer gas reached up to 170 mJ and a high pulsed output power (of up to 24 MW) was obtained at a FWHM duration of the KrF-laser pulse of 7 ns. The maximal total efficiency obtained in the experiment with two-component gas mixtures of KrF and XeCl lasers was 0.8%.

  9. Porous materials as high performance adsorbents for CO2 capture, gas separation and purification

    Science.gov (United States)

    Wang, Jun

    Global warming resulted from greenhouse gases emission has received a widespread attention. Among the greenhouse gases, CO2 contributes more than 60% to global warming due to its huge emission amount. The flue gas contains about 15% CO2 with N2 as the balance. If CO2 can be separated from flue gas, the benefit is not only reducing the global warming effect, but also producing pure CO2 as a very useful industry raw material. Substantial progress is urgent to be achieved in an industrial process. Moreover, energy crisis is one of the biggest challenges for all countries due to the short life of fossil fuels, such as, petroleum will run out in 50 years and coal will run out in 150 years according to today's speed. Moreover, the severe pollution to the environment caused by burning fossil fuels requires us to explore sustainable, environment-friendly, and facile energy sources. Among several alternative energy sources, natural gas is one of the most promising alternative energy sources due to its huge productivity, abundant feed stock, and ease of generation. In order to realize a substantial adsorption process in industry, synthesis of new adsorbents or modification of existing adsorbent with improved properties has become the most critical issue. This dissertation reports systemic characterization and development of five serials of novel adsorbents with advanced adsorption properties. In chapter 2, nitrogen-doped Hypercross-linking Polymers (HCPs) have been synthesized successfully with non-carcinogenic chloromethyl methyl ether (CME) as the cross-linking agent within a single step. Texture properties, surface morphology, CO2/N2 selectivity, and adsorption heat have been presented and demonstrated properly. A comprehensive discussion on factors that affect the CO2 adsorption and CO2/N 2 separation has also been presented. It was found that high micropore proportion and N-content could effectively enhance CO2 uptake and CO2/N2 separation selectivity. In chapter 3, a

  10. Feasibility of high-helium natural gas exploration in the Presinian strata, Sichuan Basin

    Directory of Open Access Journals (Sweden)

    Jian Zhang

    2015-01-01

    Full Text Available Helium in China highly depends on import at present, so the most practical way to change the situation is searching for medium-to-large natural gas fields with high helium content. Therefore, the hydrocarbon accumulation mechanism and the helium origin of the Weiyuan high-helium natural gas reservoir have been analyzed to find out the feasibility of finding natural gas field with high helium content in the Presinian strata of the Sichuan Basin. Based on twelve outcrop sections and drilling data of four wells encountering the Presinian strata, the petrological features, sedimentary facies and source rocks of Presinian strata were systematically analyzed, which shows that the sedimentary formation developed in the Presinian is the Nanhua system, and the stratigraphic sequence revealed by outcrop section in the eastern margin includes the Nantuo, Datangpo, Gucheng and Liantuo Fms, and it is inferred that the same stratigraphic sequence may occur inside the basin. The Nantuo, Gucheng and Liantuo Fms are mainly glacial deposits of glutenite interbedded with mudstone; the Datangpo Fm is interglacial deposits of sandstone and shale, the lower part shale, rich in organic matter, is fairly good source rock. Further study showed that the Nantuo coarse-grained clastic reservoir, Datangpo source rock and the intruded granite “helium source rock” make up a good high-helium gas system. Controlled by the early rift, the thick Presinian sedimentary rocks occur primarily inside the rift. The distribution of sedimentary rocks and granite in the basin was predicted by use of the seismic data, which shows that the feasibility of finding high-helium gas reservoirs in Ziyang area of the Sichuan Basin is great.

  11. High amplitude vortex-induced pulsations in a gas transport system

    NARCIS (Netherlands)

    Kriesels, P.C.; Peters, M.C.A.M.; Hirschberg, A.; Wijnands, A.P.J.; Iafrati, A.; Riccardi, G.; Piva, R.; Bruggeman, J.C.

    1995-01-01

    High Reynolds number, low Mach number gas flows in pipe systems with closed side branches exhibit spectacular low frequency self-sustained pulsations driven by periodic vortex shedding at specific values of the Strouhal number. A detailed study is presented of the behaviour of the flow in a system w

  12. Highly Selective Continuous Gas-Phase Methoxycarbonylation of Ethylene with Supported Ionic Liquid Phase (SILP) Catalysts

    DEFF Research Database (Denmark)

    Khokarale, Santosh Govind; Garcia Suárez, Eduardo José; Fehrmann, Rasmus

    2017-01-01

    Supported ionic liquid phase (SILP) technology was applied for the first time to the Pd-catalyzed continuous, gas-phase methoxycarbonylation of ethylene to selectively produce methyl propanoate (MP) in high yields. The influence of catalyst and reaction parameters such as, for example, ionic liqu...

  13. Gas phase considerations for the growth of device quality nanocrystalline silicon at high rate

    NARCIS (Netherlands)

    Rath, J.K.; Verkerk, A.D.; Liu, Y.; Brinza, M.; Goedheer, W.J.; Schropp, R.E.I.

    2008-01-01

    In order to increase industrial viability and to find niche markets, high deposition rate and low temperature depositions compared to standard deposition conditions are two recent trends in research areas concerning thin film silicon. In situ diagnostic tools to monitor gas phase conditions are usef

  14. Gas phase considerations for the growth of device quality nanocrystalline silicon at high rate

    NARCIS (Netherlands)

    J.K. Rath,; Verkerk, A. D.; Liu, Y.; Brinza, M.; W. J. Goedheer,; Schropp, R. E. I.

    2009-01-01

    In order to increase industrial viability and to find niche markets, high deposition rate and low temperature depositions compared to standard deposition conditions are two recent trends in research areas concerning thin film silicon. In situ diagnostic tools to monitor gas phase conditions are usef

  15. Two-step condensation of the ideal Bose gas in highly anisotropic traps

    NARCIS (Netherlands)

    van Druten, N.J.; Ketterle, W.

    1997-01-01

    The ideal Bose gas in a highly anisotropic harmonic potential is studied. It is found that Bose-Einstein condensation occurs in two distinct steps as the temperature is lowered. In the first step the specific heat shows a sharp feature, but the system still occupies many one-dimensional quantum

  16. High Temperature Flue Gas Desulfurization In Moving Beds With Regenerable Copper Based Sorbents

    Energy Technology Data Exchange (ETDEWEB)

    Cengiz, P.A.; Ho, K.K.; Abbasian, J.; Lau, F.S.

    2002-09-20

    The objective of this study was to develop new and improved regenerable copper based sorbent for high temperature flue gas desulfurization in a moving bed application. The targeted areas of sorbent improvement included higher effective capacity, strength and long-term durability for improved process control and economic utilization of the sorbent.

  17. Modeling and experiments on differential pumping in linear plasma generators operating at high gas flows

    NARCIS (Netherlands)

    van Eck, H. J. N.; Koppers, W. R.; van Rooij, G. J.; W. J. Goedheer,; Engeln, R.; D.C. Schram,; Cardozo, N. J. L.; Kleyn, A. W.

    2009-01-01

    The direct simulation Monte Carlo (DSMC) method was used to investigate the efficiency of differential pumping in linear plasma generators operating at high gas flows. Skimmers are used to separate the neutrals from the plasma beam, which is guided from the source to the target by a strong axial mag

  18. Computer simulation of effect of conditions on discharge-excited high power gas flow CO laser

    Science.gov (United States)

    Ochiai, Ryo; Iyoda, Mitsuhiro; Taniwaki, Manabu; Sato, Shunichi

    2017-01-01

    The authors have developed the computer simulation codes to analyze the effect of conditions on the performances of discharge excited high power gas flow CO laser. The six be analyzed. The simulation code described and executed by Macintosh computers consists of some modules to calculate the kinetic processes. The detailed conditions, kinetic processes, results and discussions are described in this paper below.

  19. Analysis of Trace Hydrogen Isotopes in Fusion Fuel Cycle by High Precision Gas Chromatograph

    Institute of Scientific and Technical Information of China (English)

    YANG; Li-ling; YANG; Hong-guang; ZHAO; Wei-wei; HE; Chang-shui; LIU; Zhen-xing; ZHAN; Qin

    2013-01-01

    It is essential to analysis of hydrogen isotopes in the fuel cycle system of fusion reactors,gas chromatography(GC)was found to be an effectively analytical technique.Compared with conventional GC,the high-precision GC with a cryogenic column could achieve fairly good performance to reduce the retention time.

  20. Microbial Electrolysis Cells for High Yield Hydrogen Gas Production from Organic Matter

    NARCIS (Netherlands)

    Logan, B.E.; Call, D.; Cheng, S.; Hamelers, H.V.M.; Sleutels, T.H.J.A.; Jeremiasse, A.W.; Rozendal, R.A.

    2008-01-01

    The use of electrochemically active bacteria to break down organic matter, combined with the addition of a small voltage (>0.2 V in practice) in specially designed microbial electrolysis cells (MECs), can result in a high yield of hydrogen gas. While microbial electrolysis was invented only a few

  1. Closed-cycle gas flow system for cooling of high Tc d.c. SQUID magnetometers

    NARCIS (Netherlands)

    Bosch, van den P.J.; Holland, H.J.; Brake, ter H.J.M.; Rogalla, H.

    1995-01-01

    A high Tc.d.c SQUID based magnetometer for magnetocardiography is currently under development at the University of Twente. Since such a magnetometer should be simple to use, the cooling of the system can be realized most practically by means of a cryocooler. A closed-cycle gas flow cooling system in

  2. Microbial Electrolysis Cells for High Yield Hydrogen Gas Production from Organic Matter

    NARCIS (Netherlands)

    Logan, B.E.; Call, D.; Cheng, S.; Hamelers, H.V.M.; Sleutels, T.H.J.A.; Jeremiasse, A.W.; Rozendal, R.A.

    2008-01-01

    The use of electrochemically active bacteria to break down organic matter, combined with the addition of a small voltage (>0.2 V in practice) in specially designed microbial electrolysis cells (MECs), can result in a high yield of hydrogen gas. While microbial electrolysis was invented only a few

  3. Impaired High-Density Lipoprotein Anti-Oxidant Function Predicts Poor Outcome in Critically Ill Patients.

    Directory of Open Access Journals (Sweden)

    Lore Schrutka

    Full Text Available Oxidative stress affects clinical outcome in critically ill patients. Although high-density lipoprotein (HDL particles generally possess anti-oxidant capacities, deleterious properties of HDL have been described in acutely ill patients. The impact of anti-oxidant HDL capacities on clinical outcome in critically ill patients is unknown. We therefore analyzed the predictive value of anti-oxidant HDL function on mortality in an unselected cohort of critically ill patients.We prospectively enrolled 270 consecutive patients admitted to a university-affiliated intensive care unit (ICU and determined anti-oxidant HDL function using the HDL oxidant index (HOI. Based on their HOI, the study population was stratified into patients with impaired anti-oxidant HDL function and the residual study population.During a median follow-up time of 9.8 years (IQR: 9.2 to 10.0, 69% of patients died. Cox regression analysis revealed a significant and independent association between impaired anti-oxidant HDL function and short-term mortality with an adjusted HR of 1.65 (95% CI 1.22-2.24; p = 0.001 as well as 10-year mortality with an adj. HR of 1.19 (95% CI 1.02-1.40; p = 0.032 when compared to the residual study population. Anti-oxidant HDL function correlated with the amount of oxidative stress as determined by Cu/Zn superoxide dismutase (r = 0.38; p<0.001.Impaired anti-oxidant HDL function represents a strong and independent predictor of 30-day mortality as well as long-term mortality in critically ill patients.

  4. Requirements for gas quality and gas appliances

    NARCIS (Netherlands)

    Levinsky, Howard; Gersen, Sander; Kiewiet, Bert

    2015-01-01

    Introduction The gas transmission network in the Netherlands transports two different qualities of gas, low-calorific gas known as G-gas or L-gas and, high calorific gas (H-gas). These two gas qualities are transported in separate networks, and are connected by means of five blending and conversion

  5. Lasershot(sm) marking system: high-volume labeling for safety-critical parts

    Energy Technology Data Exchange (ETDEWEB)

    Dane, C B; Hackel, L; Honig, J; Halpin, J; Chen, H-L; Mendieta, F; Harris, F; Lane, L; Daly, J; Harrison, J

    2001-02-16

    The Lasershot Marking System uses laser pulses to safely and permanently impress identification markings on metal components. This process does not remove material or change surface chemistry and actually increases the marked area's resistance to fatigue and corrosion failure. Lasershot marking is ideally suited for marking parts used in situations where safety is critical--from hip-joint replacements to commercial airliner components. The minimum size of the mark is limited only by the resolution of the reading system, allowing manufacturers to mark parts which, up to now, have been too small to label with mechanical peening techniques. The high resolution of the Lasershot marks makes them difficult to reproduce, providing a solution to the ongoing problem of inferior, counterfeited parts. The high marking rate of up to six marks per second makes this system practical and cost-effective for marking high-volume components.

  6. A critical examination of high-fidelity human patient simulation within the context of nursing pedagogy.

    Science.gov (United States)

    Parker, Brian C; Myrick, Florence

    2009-04-01

    The use of high-fidelity human patient simulators (HPS) have been embraced by nursing education programs in the development of immersive clinical simulations despite the lack of research into a pedagogy or educational philosophy appropriate to guide this technology-based learning tool. In this article, we explore this approach to clinical teaching through a critical examination of the application of behaviorist and constructivist pedagogy to high-fidelity scenario-based simulation sessions. Practical guidelines for developing simulation-based learning sessions that reflect both philosophical paradigms are provided. Consideration is also given to societal trends such as the digital revolution and the incoming millennial generation who represent the aptitude of the modern nursing student to utilize high-fidelity realistic and immersive simulation. Depending on the desired goal of simulator utilization, the nurse educator may want to draw on constructivism or behaviorism or a blend of both educational philosophies to best meet the needs of the adult learner.

  7. Critical pathogenic steps to high risk Helicobacter pylori gastritis and gastric carcinogenesis.

    Science.gov (United States)

    Lee, Inchul

    2014-06-07

    Helicobacter pylori (H. pylori) gastritis may progress to high risk gastropathy and cancer. However, the pathological progression has not been characterized in detail. H. pylori induce persistent inflammatory infiltration. Neutrophils are unique in that they directly infiltrate into foveolar epithelium aiming the proliferative zone specifically. Neutrophilic proliferative zone foveolitis is a critical pathogenic step in H. pylori gastritis inducing intensive epithelial damage. Epithelial cells carrying accumulated genomic damage and mutations show the Malgun (clear) cell change, characterized by large clear nucleus and prominent nucleolus. Malgun cells further undergo atypical changes, showing nuclear folding, coarse chromatin, and multiple nucleoli. The atypical Malgun cell (AMC) change is a novel premalignant condition in high risk gastropathy, which may progress and undergo malignant transformation directly. The pathobiological significance of AMC in gastric carcinogenesis is reviewed. A new diagnosis system of gastritis is proposed based on the critical pathologic steps classifying low and high risk gastritis for separate treatment modality. It is suggested that the regulation of H. pylori-induced neutrophilic foveolitis might be a future therapeutic goal replacing bactericidal antibiotics approach.

  8. High critical current density YBCO films and fabrication of dc-SQUIDs

    CERN Document Server

    Kuriki, S; Kawaguchi, Y; Matsuda, M; Otowa, T

    2002-01-01

    In order to improve the sensitivity of SQUID magnetometers made of high-T sub c films, we have studied the conditions of pulsed-laser deposition of YBCO films. Among the different deposition parameters examined, extensive degassing of the vacuum chamber before and precise control of the substrate temperature during the film deposition were found effective for obtaining high critical temperature T sub c and high critical current density J sub c. It was also found that the residual-resistance ratio has a clear correlation with J sub c , indicating that it can be a good, and easy to measure, index of the film quality. Films having T sub c approx 89-90 K and J sub c >= 5x10 sup 6 A cm sup - sup 2 at 77 K were used to fabricate SQUIDs without a pickup loop. Grain-boundary junctions formed on bicrystal substrates with a 30 deg. misorientation angle exhibited I sub c R sub n values of more than 100 mu V at 77 K. The well-known scaling behaviour of the relation I sub c R sub n propor to (J sup G sup B sub c) sup 1 su...

  9. Magnus effects at high angles of attack and critical Reynolds numbers

    Science.gov (United States)

    Seginer, A.; Ringel, M.

    1983-01-01

    The Magnus force and moment experienced by a yawed, spinning cylinder were studied experimentally in low speed and subsonic flows at high angles of attack and critical Reynolds numbers. Flow-field visualization aided in describing a flow model that divides the Magnus phenomenon into a subcritical region, where reverse Magnus loads are experienced, and a supercritical region where these loads are not encountered. The roles of the spin rate, angle of attack, and crossflow Reynolds number in determining the boundaries of the subcritical region and the variations of the Magnus loads were studied.

  10. Examination of charge transfer in Au/YSZ for high-temperature optical gas sensing

    Energy Technology Data Exchange (ETDEWEB)

    Baltrus, John P. [U.S. DOE; Ohodnicki, Paul R. [U.S. DOE

    2014-01-01

    Au-nanoparticle incorporated oxide thin film materials demonstrate significant promise as functionalsensor materials for high temperature optical gas sensing in severe environments relevant for fossil andnuclear based power generation. The Au/yttria-stabilized zirconia (YSZ) system has been extensivelystudied in the literature and serves as a model system for fundamental investigations that seek to betterunderstand the mechanistic origin of the plasmonic gas sensing response. In this work, X-ray photoelec-tron spectroscopy techniques are applied to Au/YSZ films in an attempt to provide further experimentalevidence for a proposed sensing mechanism involving a change in free carrier density of Au nanoparticles due to charge transfer.

  11. Conceptual Design for a High-Temperature Gas Loop Test Facility

    Energy Technology Data Exchange (ETDEWEB)

    James B. Kesseli

    2006-08-01

    This report documents an early-stage conceptual design for a high-temperature gas test loop. The objectives accomplished by the study include, (1) investigation of existing gas test loops to determine ther capabilities and how the proposed system might best complement them, (2) development of a preliminary test plan to help identify the performance characteristics required of the test unit, (3) development of test loop requirements, (4) development of a conceptual design including process flow sheet, mechanical layout, and equipment specifications and costs, and (5) development of a preliminary test loop safety plan.

  12. High-precision gas gain and energy transfer measurements in Ar–CO{sub 2} mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Şahin, Özkan, E-mail: osahin@uludag.edu.tr [Department of Physics, Uludağ University, 16059 Bursa (Turkey); Kowalski, Tadeusz Z. [Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Kraków (Poland); Veenhof, Rob [Department of Physics, Uludağ University, 16059 Bursa (Turkey); RD51 collaboration, CERN, Genève (Switzerland)

    2014-12-21

    Ar–CO{sub 2} is a Penning mixture since a fraction of the energy stored in Ar 3p{sup 5}3d and higher excited states can be transferred to ionize CO{sub 2} molecules. In the present work, concentration and pressure dependence of Penning transfer rate and photon feedback parameter in Ar–CO{sub 2} mixtures have been investigated with recent systematic high-precision gas gain measurements which cover the range 1–50% CO{sub 2} at 400, 800, 1200, 1800 hPa and gas gain from 1 to 5×10{sup 5}.

  13. High-precision gas gain and energy transfer measurements in Ar–CO2 mixtures

    CERN Document Server

    Şahin, Özkan; Veenhof, Rob

    2014-01-01

    Ar–CO2 is a Penning mixture since a fraction of the energy stored in Ar 3p53d3p53d and higher excited states can be transferred to ionize CO2 molecules. In the present work, concentration and pressure dependence of Penning transfer rate and photon feedback parameter in Ar–CO2 mixtures have been investigated with recent systematic high-precision gas gain measurements which cover the range 1–50% CO2 at 400, 800, 1200, 1800 hPa and gas gain from 1 to 5×105.

  14. Evaluation of proposed German safety criteria for high-temperature gas-cooled reactors

    Energy Technology Data Exchange (ETDEWEB)

    Barsell, A.W.

    1980-05-01

    This work reviews proposed safety criteria prepared by the German Bundesministerium des Innern (BMI) for future licensing of gas-cooled high-temperature reactor (HTR) concepts in the Federal Republic of Germany. Comparison is made with US General Design Criteria (GDCs) in 10CFR50 Appendix A and with German light water reactor (LWR) criteria. Implications for the HTR design relative to the US design and safety approach are indicated. Both inherent characteristics and design features of the steam cycle, gas turbine, and process heat concepts are taken into account as well as generic design options such as a pebble bed or prismatic core.

  15. Preparation and characterization of composite membrane for high temperature gas separation

    Energy Technology Data Exchange (ETDEWEB)

    Ilias, S.; King, F.G.; Su, N.

    1994-10-01

    The objective of this project is to develop thin film palladium membranes for separation of hydrogen in high temperature applications. The authors plan to use electroless plating to deposit thin palladium films on microporous ceramic and silver substrates and then characterize the membrane in terms of permeability and selectivity for gas separation. To accomplish the research objective, the project requires three tasks: Development of a process for composite membrane fabrication; Characterization of composite membrane; and Development of theoretical model for hydrogen gas separation. The experimental procedures are described.

  16. Measuring radon-222 in soil gas with high spatial and temporal resolution.

    Science.gov (United States)

    Huxtable, Darren; Read, David; Shaw, George

    2017-02-01

    In order to exploit (222)Rn as a naturally-occurring tracer in soils we need to sample and measure radon isotopes in soil gas with high spatial and temporal resolution, without disturbing in situ activity concentrations and fluxes. Minimisation of sample volume is key to improving the resolution with which soil gas can be sampled; an analytical method is then needed which can measure radon with appropriate detection limits and precision for soil gas tracer studies. We have designed a soil gas probe with minimal internal dead volume to allow us to sample soil gas volumes of 45 cm(3). Radon-222 is extracted from these samples into a mineral oil-based scintillation cocktail before counting on a conventional liquid scintillation counter. A detection limit of 320 Bq m(-3) (in soil gas) is achievable with a 1 h count. This could be further reduced but, in practice, is sufficient for our purpose since (222)Rn in soil gas typically ranges from 2000-50,000 Bq m(-3). The method is simple and provides several advantages over commonly used field-portable instruments, including smaller sample volumes, speed of deployment and reliability under field conditions. The major limitation is the need to count samples in a liquid scintillation counter within 2-3 days of collection, due to the short (3.824 day) radioactive half-life of (222)Rn. The method is not applicable to the very short-lived (55 s half-life) (220)Rn.

  17. Lining for high temperature gas turbines. Auskleidung fuer Hochtemperatur-Gasturbinen

    Energy Technology Data Exchange (ETDEWEB)

    Bechtel, P.; Heckel, J.

    1986-06-26

    A lining is described for high temperature gas turbines, where a thermally insulating layer of a ceramic material is applied on the side of the turbine casing towards the high temperature. In order to insulate the heat which occurs at the very high process temperatures in this gas turbine plant, it is proposed that a first layer of microporous material containing mainly silica should be applied on the inner wall of the casing, that a second layer of ceramic fibres should be applied on this first layer that a binding layer of a fibre mat consisting of Al/sub 2/O/sub 3/ and SiO/sub 2/ and possibly with the addition of Cr/sub 2/O/sub 3/ should be provided between the turbine casing and the first layer and between the first and second layer, and that a lining layer of heat-resistant high quality steel is applied on this second layer.

  18. High precision single-cluster Monte Carlo measurement of the critical exponents of the classical 3D Heisenberg model

    CERN Document Server

    Holm, C

    1992-01-01

    We report measurements of the critical exponents of the classical three-dimensional Heisenberg model on simple cubic lattices of size $L^3$ with $L$ = 12, 16, 20, 24, 32, 40, and 48. The data was obtained from a few long single-cluster Monte Carlo simulations near the phase transition. We compute high precision estimates of the critical coupling $K_c$, Binder's parameter $U^* and the critical exponents $\

  19. Highly sensitive nanostructure SnO2 based gas sensor for environmental pollutants

    Science.gov (United States)

    Korgaokar, Sushil; Moradiya, Meet; Prajapati, Om; Thakkar, Pranav; Pala, Jay; Savaliya, Chirag; Parikh, Sachin; Markna, J. H.

    2017-05-01

    A major quantity of pollutants are produced from industries and vehicles in the form of gas. New approaches are needed to solve well-known environmental pollutants like CO, CO2, NO2, SOx. Therefore detection with effective gas sensors is a vital part of pollution prevention efforts. There is a need to develop fast, rapid, cost-effective, highly sensitive, low power, and non-intrusive rugged sensors that can be easily installed. In the present study, nanostructured SnO2 used as a sensitive material in the devices and synthesized using hydrothermal process. The detailed development of the fabrication of SnO2 nanostructures gas sensor is described, which shows the remarkable change in the sensing properties with varying particle size. Additionally, we have used X-ray diffraction, scanning electron microscopy (SEM) for characterization and carefully examined the relative parameters like response magnitude (sensitivity) and selectivity of SnO2 nano structures with different particle size.

  20. Ionization and scintillation response of high-pressure xenon gas to alpha particles

    CERN Document Server

    Álvarez, V; Cárcel, S; Cebrián, S; Cervera, A; Conde, C A N; Dafni, T; Díaz, J; Egorov, M; Esteve, R; Evtoukhovitch, P; Fernandes, L M P; Ferrario, P; Ferreira, A L; Freitas, E D C; Gehman, V M; Gil, A; Goldschmidt, A; Gómez, H; Gómez-Cadenas, J J; González-Díaz, D; Gutiérrez, R M; Hauptman, J; Morata, J A Hernando; Herrera, D C; Irastorza, I G; Jinete, M A; Labarga, L; Laing, A; Liubarsky, I; Lopes, J A M; Lorca, D; Losada, M; Luzón, G; Marí, A; Martín-Albo, J; Miller, T; Moiseenko, A; Monrabal, F; Monteiro, C M B; Mora, F J; Moutinho, L M; Vidal, J Muñoz; da Luz, H Natal; Navarro, G; Nebot, M; Nygren, D; Oliveira, C A B; Palma, R; Pérez, J; Aparicio, J L Pérez; Renner, J; Ripoll, L; Rodríguez, A; Rodríguez, J; Santos, F P; Santos, J M F dos; Segui, L; Serra, L; Shuman, D; Simón, A; Sofka, C; Sorel, M; Toledo, J F; Tomás, A; Torrent, J; Tsamalaidze, Z; Vázquez, D; Veloso, J F C A; Webb, R; White, J T; Yahlali, N

    2012-01-01

    High-pressure xenon gas is an attractive detection medium for a variety of applications in fundamental and applied physics. In this paper we study the transport properties of ionization electrons, and the mechanism of electron-ion recombination, in xenon gas at 10 bar pressure. For this purpose, we use a source of alpha particles in the NEXT-DEMO time projection chamber, the large scale prototype of the NEXT-100 neutrinoless double beta decay experiment, in three different drift electric field configurations. Our electron drift velocity and longitudinal diffusion results are similar to expectations based on available electron scattering cross sections on pure xenon, favoring low-diffusion models. In addition, two types of measurements addressing the connection between the ionization and scintillation yields were performed. On the one hand we observe, for the first time in xenon gas, large event-by-event correlated fluctuations between the ionization and scintillation signals, similarly to what has already bee...

  1. Trends in high performance compressors for petrochemical and natural gas industry in China

    Science.gov (United States)

    Zhao, Yuanyang; Li, Liansheng

    2015-08-01

    Compressors are the key equipment in the petrochemical and natural gas industry system. The performance and reliability of them are very important for the process system. The application status of petrochemical & natural gas compressors in China is presented in this paper. The present status of design and operating technologies of compressors in China are mentioned in this paper. The turbo, reciprocating and twin screw compressors are discussed. The market demands for different structure compressors in process gas industries are analysed. This paper also introduces the research and developments for high performance compressors in China. The recent research results on efficiency improvement methods, stability improvement, online monitor and fault diagnosis will also be presented in details.

  2. Microbial electrolysis cells for high yield hydrogen gas production from organic matter.

    Science.gov (United States)

    Logan, Bruce E; Call, Douglas; Cheng, Shaoan; Hamelers, Hubertus V M; Sleutels, Tom H J A; Jeremiasse, Adriaan W; Rozendal, René A

    2008-12-01

    The use of electrochemically active bacteria to break down organic matter, combined with the addition of a small voltage (> 0.2 V in practice) in specially designed microbial electrolysis cells (MECs), can result in a high yield of hydrogen gas. While microbial electrolysis was invented only a few years ago, rapid developments have led to hydrogen yields approaching 100%, energy yields based on electrical energy input many times greater than that possible by water electrolysis, and increased gas production rates. MECs used to make hydrogen gas are similar in design to microbial fuel cells (MFCs) that produce electricity, but there are important differences in architecture and analytical methods used to evaluate performance. We review here the materials, architectures, performance, and energy efficiencies of these MEC systems that show promise as a method for renewable and sustainable energy production, and wastewater treatment.

  3. High Angular Momentum Halo Gas: a Feedback and Code-Independent Prediction of LCDM

    CERN Document Server

    Stewart, Kyle; Oñorbe, Jose; Bullock, James; Joung, M Ryan; Devriendt, Julien; Ceverino, Daniel; Kereš, Dušan; Hopkins, Phil; Faucher-Giguère, Claude-André

    2016-01-01

    We investigate angular momentum acquisition in Milky Way sized galaxies by comparing five high resolution zoom-in simulations, each implementing identical cosmological initial conditions, but utilizing different hydrodynamic codes: Enzo, Art, Ramses, Arepo, and Gizmo-PSPH. Each code implements a distinct set of feedback and star formation prescriptions. We find that while many galaxy and halo properties vary between the different codes (and feedback prescriptions), there is qualitative agreement on the process of angular momentum acquisition in the galaxy's halo. In all simulations, cold filamentary gas accretion to the halo results in ~4 times more specific angular momentum in cold halo gas ($\\lambda_{cold} \\simeq 0.15$) than in the dark matter halo. At z>1, this inflow frequently results in the formation of transient cold flow disks---large co-rotating gaseous structures in the halo of the galaxy that are fueled, aligned, and kinematically connected to filamentary gas infall along the cosmic web. Due to the...

  4. Microbial Electrolysis Cells for High Yield Hydrogen Gas Production from Organic Matter

    KAUST Repository

    Logan, Bruce E.

    2008-12-01

    The use of electrochemically active bacteria to break down organic matter, combined with the addition of a small voltage (>0.2 V in practice) in specially designed microbial electrolysis cells (MECs), can result in a high yield of hydrogen gas. While microbial electrolysis was invented only a few years ago, rapid developments have led to hydrogen yields approaching 100%, energy yields based on electrical energy input many times greater than that possible by water electrolysis, and increased gas production rates. MECs used to make hydrogen gas are similar in design to microbial fuel cells (MFCs) that produce electricity, but there are important differences in architecture and analytical methods used to evaluate performance. We review here the materials, architectures, performance, and energy efficiencies of these MEC systems that show promise as a method for renewable and sustainable energy production, and wastewater treatment. © 2008 American Chemical Society.

  5. A New Gas Cell for High-Precision Doppler Measurements in the Near-Infrared

    CERN Document Server

    Valdivielso, L; Martín, E

    2010-01-01

    High-resolution spectroscopy in the near-infrared could become the leading method for discovering extra-solar planets around very low-mass stars and brown dwarfs. To help to achieve an accuracy of ~m/s, we are developing a gas cell which consists of a mixture of gases whose absorption spectral lines span all over the near-infrared region. We present the most promising mixture, made of acetylene, nitrous oxide, ammonia, chloromethans and hydrocarbons. The mixture is contained in a small size 13 cm long gas cell and covers most of the H and K-bands. It also shows small absorptions in the J-band but they are few and not sharp enough for near infrared wavelength calibration. We describe the working method and experiments and compare our results with the state of the art for near infrared gas cells.

  6. Critical properties of the high-energy electron-beam-irradiated superconductor weak links

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sung Hoon; Lee, Soon Gul [Korea University, Sejong (Korea, Republic of)

    2014-11-15

    We have studied the effects of high-energy electron-beam irradiation on the superconducting transition properties of an YBCO bicrystal junction, a focused ion-beam (FIB)-patterned YBCO nanobridge, a MgB{sub 2} intergrain nanobridge, and a BaKFeAs multigrain microbridge. We used one sample for each junction type and repeated the irradiation-and-measurement process at 6 accumulated-dose steps: 0, 3 x 10{sup 14}, 10{sup 15}, 3 x 10{sup 15}, 10{sup 16}, and 10{sup 17} e/cm{sup 2}. A uniform electron beam with a 1-MeV kinetic energy was irradiated indiscrimately over the samples. We measured the resistive transition temperature, the normal-state resistance, and the critical current. The irradiation effect was significant for all the samples except the BaKFeAs microbridge. The critical current data for the YBCO bicrystal junction and the MgB{sub 2} intergrain nanobridge had a maximum at 3 x 10{sup 15} e/cm{sup 2}, and the YBCO nanobridge showed a monotonic decrease. For all the samples, the normal state resistance increased monotonically with increasing dose by up to ∼20% at 10{sup 16} e/cm{sup 2}, and the change in T{sub c} was negligible. The results showed that the YBCO and MgB{sub 2} weak links were susceptive to irradiation, indicating the possibility of controlling the critical current of those junctions by using high-energy electron-beam irradiation.

  7. High static gel strength cement slurries for gas flow-laboratory surveys and case history

    Energy Technology Data Exchange (ETDEWEB)

    Suzart, J. Walter P.; Ribeiro, Danilo [Halliburton Company, Houston, TX (United States); Farias, A.C. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil); Pessoa, Laudemar [University of Adelaide (Australia). Math. Bachelor Master Petroleum Engineer

    2008-07-01

    Gas migration is a phenomenon involving fluid density control, well conditioning, good adherence of the cement slurry to the contacting surfaces, chemical-physical properties, cement hydration mechanisms, and the well's geometry. This problem is evident in several producing wells with a pressurized annulus. Recently, a trend of combining operational techniques with cement slurries capable of developing very high static gel strength (SGS) has developed. Slurry designs intended to confer high SGS almost always have greater rheologies. This can make it difficult to mix the slurry on surfaces or even move the slurry placement through the well, more so because gas-producing wells are typically deep and have complex geometry. This paper evaluates the industry's understanding of this problem. It compares the major solutions with current cement slurry designs and, in addition to the conventional specific gas well parameters, it emphasizes the high SGS and low rheologies on surface conditions. This study also documents the success and efficiency of cementing at a Brazilian sedimentary basin which was completed using designs recommended in this work. This paper does not consider the gas migration occurrence through the cementing matrix. (author)

  8. High gas pressure: an innovative method for the inactivation of dried bacterial spores.

    Science.gov (United States)

    Colas de la Noue, A; Espinasse, V; Perrier-Cornet, J-M; Gervais, P

    2012-08-01

    In this article, an original non-thermal process to inactivate dehydrated bacterial spores is described. The use of gases such as nitrogen or argon as transmission media under high isostatic pressure led to an inactivation of over 2 logs CFU/g of Bacillus subtilis spores at 430 MPa, room temperature, for a 1 min treatment. A major requirement for the effectiveness of the process resided in the highly dehydrated state of the spores. Only a water activity below 0.3 led to substantial inactivation. The solubility of the gas in the lipid components of the spore and its diffusion properties was essential to inactivation. The main phenomenon involved seems to be the sorption of the gas under pressure by the spores' structures such as residual pores and plasma membranes, followed by a sudden drop in pressure. Observation by phase-contrast microscopy suggests that internal structures have been affected by the treatment. Some parallels with polymer permeability to gas and rigidity at various water activities offer a few clues about the behavior of the outer layers of spores in response to this parameter and provide a good explanation for the sensitivity of spores to high gas pressure discharge at low hydration levels. Specificity of microorganisms such as size, organization, and composition could help in understanding the differences between spores and yeast regarding the parameters required for inactivation, such as pressure or maintenance time.

  9. Difference Of Evaporation and Boiling for Heterogeneous Water Droplets in a High-Temperature Gas

    Directory of Open Access Journals (Sweden)

    Legros Jean Claude

    2015-01-01

    Full Text Available Experimental investigation of vapor formation was carried out on water droplets on fixed graphite substrate and heterogeneous droplets (containing solid single inclusions when heating in high-temperature gas. High-speed video shooting (up to 105 frames per second, optical method (Particle Image Velocimetry and TEMA Automotive software were used. We revealed two phase change mechanisms of heterogeneous liquid droplets. Effect of evaporation and boiling on evaporation times of water droplets was determined.

  10. Determination of nitrogen monoxide in high purity nitrogen gas with an atmospheric pressure ionization mass spectrometer

    Science.gov (United States)

    Kato, K.

    1985-01-01

    An atmospheric pressure ionization mass spectrometric (API-MS) method was studied for the determination of residual NO in high purity N2 gas. The API-MS is very sensitive to NO, but the presence of O2 interferes with the NO measurement. Nitrogen gas in cylinders as sample gas was mixed with NO standard gas and/or O2 standard gas, and then introduced into the API-MS. The calibration curves of NO and O2 has linearity in the region of 0 - 2 ppm, but the slopes changed with every cylinder. The effect of O2 on NO+ peak was additive and proportional to O2 concentration in the range of 0 - 0.5 ppm. The increase in NO+ intensity due to O2 was (0.07 - 0.13)%/O2, 1 ppm. Determination of NO and O2 was carried out by the standard addition method to eliminate the influence of variation of slopes. The interference due to O2 was estimated from the product of the O2 concentration and the ratio of slope A to Slope B. Slope A is the change in the NO+ intensity with the O2 concentration. Slope B is the intensity with O2 concentration.

  11. HD and H2 formation in low-metallicity dusty gas clouds at high reshift

    CERN Document Server

    Cazaux, S

    2009-01-01

    Context: The HD and H2 molecules play important roles in the cooling of primordial and very metal-poor gas at high redshift. Aims: Grain surface and gas phase formation of HD and H2 is investigated to assess the importance of trace amounts of dust, 10^{-5}-10^{-3} Zo, in the production of HD and H2. Methods: We consider carbonaceous and silicate grains and include both physisorption and chemisorption, tunneling, and realistic grain surface barriers. We find, for a collapsing gas cloud environment with coupled chemical and thermal balance, that dust abundances as small as 10^{-5} solar lead to a strong boost in the H2 formation rate due to surface reactions. As a result of this enhancement in H2, HD is formed more efficiently in the gas phase through the D+ +H2 reaction. Direct formation of HD on dust grains cannot compete well with this gas phase process for dust temperatures below 150 K. We also derive up-to-date analytic fitting formulae for the grain surface formation of H2 and HD, including the different ...

  12. Gas-Enhanced Ultra-High Shear Mixing: A Concept and Applications

    Science.gov (United States)

    Czerwinski, Frank; Birsan, Gabriel

    2016-12-01

    The processes of mixing, homogenizing, and deagglomeration are of paramount importance in many industries for modifying properties of liquids or liquid-based dispersions at room temperature and treatment of molten or semi-molten alloys at high temperatures, prior to their solidification. To implement treatments, a variety of technologies based on mechanical, electromagnetic, and ultrasonic principles are used commercially or tested at the laboratory scale. In a large number of techniques, especially those tailored toward metallurgical applications, the vital role is played by cavitation, generation of gas bubbles, and their interaction with the melt. This paper describes a novel concept exploring an integration of gas injection into the shear zone with ultra-high shear mixing. As revealed via experiments with a prototype of the cylindrical rotor-stator apparatus and transparent media, gases injected radially through the high-speed rotor generate highly refined bubbles of high concentration directly in the shear zone of the mixer. It is believed that an interaction of large volume of fine gas bubbles with the liquid, superimposed on ultra-high shear, will enhance mixing capabilities and cause superior refining and homogenizing of the liquids or solid-liquid slurries, thus allowing their effective property modification.

  13. Gas-Enhanced Ultra-High Shear Mixing: A Concept and Applications

    Science.gov (United States)

    Czerwinski, Frank; Birsan, Gabriel

    2017-04-01

    The processes of mixing, homogenizing, and deagglomeration are of paramount importance in many industries for modifying properties of liquids or liquid-based dispersions at room temperature and treatment of molten or semi-molten alloys at high temperatures, prior to their solidification. To implement treatments, a variety of technologies based on mechanical, electromagnetic, and ultrasonic principles are used commercially or tested at the laboratory scale. In a large number of techniques, especially those tailored toward metallurgical applications, the vital role is played by cavitation, generation of gas bubbles, and their interaction with the melt. This paper describes a novel concept exploring an integration of gas injection into the shear zone with ultra-high shear mixing. As revealed via experiments with a prototype of the cylindrical rotor-stator apparatus and transparent media, gases injected radially through the high-speed rotor generate highly refined bubbles of high concentration directly in the shear zone of the mixer. It is believed that an interaction of large volume of fine gas bubbles with the liquid, superimposed on ultra-high shear, will enhance mixing capabilities and cause superior refining and homogenizing of the liquids or solid-liquid slurries, thus allowing their effective property modification.

  14. Critical Role of Monoclinic Polarization Rotation in High-Performance Perovskite Piezoelectric Materials

    Science.gov (United States)

    Liu, Hui; Chen, Jun; Fan, Longlong; Ren, Yang; Pan, Zhao; Lalitha, K. V.; Rödel, Jürgen; Xing, Xianran

    2017-07-01

    High-performance piezoelectric materials constantly attract interest for both technological applications and fundamental research. The understanding of the origin of the high-performance piezoelectric property remains a challenge mainly due to the lack of direct experimental evidence. We perform in situ high-energy x-ray diffraction combined with 2D geometry scattering technology to reveal the underlying mechanism for the perovskite-type lead-based high-performance piezoelectric materials. The direct structural evidence reveals that the electric-field-driven continuous polarization rotation within the monoclinic plane plays a critical role to achieve the giant piezoelectric response. An intrinsic relationship between the crystal structure and piezoelectric performance in perovskite ferroelectrics has been established: A strong tendency of electric-field-driven polarization rotation generates peak piezoelectric performance and vice versa. Furthermore, the monoclinic MA structure is the key feature to superior piezoelectric properties as compared to other structures such as monoclinic MB , rhombohedral, and tetragonal. A high piezoelectric response originates from intrinsic lattice strain, but little from extrinsic domain switching. The present results will facilitate designing high-performance perovskite piezoelectric materials by enhancing the intrinsic lattice contribution with easy and continuous polarization rotation.

  15. Impact of high-critical-temperature superconductors on electromagnetic pump applications

    Science.gov (United States)

    Krazinski, J. L.; Holtz, R. E.; Jaross, R. A.

    1990-05-01

    The impact is studied of the development of practical, high critical temperature superconducting materials on applications involving electromagnetic (EM) pumping. Potential improvements in the operating characteristics of EM pumps were examined for current pump technology. In addition, the study addressed whether the development of high (Tc) superconductors could enable the implementation of EM pumps in applications where it has not been previously feasible. This assessment focused on two specific types of EM pumps: helical rotor pumps with rotating field coils and EM thruster pumps for ship propulsion. The design and performance of helical rotor pumps were analyzed for both liquid metals and nonmetallic fluids. For liquid metals, the impact of superconductors on the pump size, mass, and efficiency was examined for EM pumps operating at relatively lower magnetic field strengths. For nonmetallic fluids, the study investigated whether the use of high magnetic field strengths, in conjunction with high (Tc) superconductors, could enable the pumping of these fluids with EM pumps of reasonable size and efficiency. The impact of high (Tc) superconducting materials on the reliability and economics of EM pumps was also examined. In addition, the study assessed the impact of high field strength, superconducting magnets on the feasibility of using EM thrusters for ship propulsion. Parametric studies were conducted on the effects of magnetic field strength, thruster size, vessel speed, and vessel size on the predicted thruster efficiencies. The results were compared with these of earlier studies on electromagnetic propulsion that incorporated both superconducting and nonsuperconducting magnet designs.

  16. The Precise Mechanisms of a High-Speed Ultrasound Gas Sensor and Detecting Human-Specific Lung Gas Exchange

    Directory of Open Access Journals (Sweden)

    Hideki Toda

    2012-12-01

    Full Text Available In this paper, we propose and develop a new real‐time human respiration process analysis method using a high‐time‐sampling gas concentration sensor based on ultrasound. A unique point about our proposed gas concentration sensor is its 1 kHz gas concentration sampling speed. This figure could not have been attained by previously proposed gas concentration measurement methods such as InfraRed, semiconductor gas sensors, or GC‐MS, because the gas analysis speeds were a maximum of a few hundred milliseconds. First, we describe the proposed new ultrasound sound speed measurement method and the signal processing, and present the measurement circuit diagram. Next, we analyse the human respiration gas variation patterns of five healthy subjects using a newly developed gas‐mask‐ type respiration sensor. This reveals that the rapid gas exchange from H2O to CO2 contains air specific to the human being. In addition, we also measured medical symptoms in subjects suffering from asthma, hyperventilation and bronchial asthma. The millisecond level high‐speed analysis of the human respiration process will be useful for the next generation of healthcare, rehabilitation and sports science technology.

  17. On the gas dependence of thermal transpiration and a critical appraisal of correction methods for capacitive diaphragm gauges

    Science.gov (United States)

    Daudé, Barthélémy; Elandaloussi, Hadj; Janssen, Christof

    2014-06-01

    Thermal transpiration effects are commonly encountered in low pressure measurements with capacitance diaphragm gauges. They arise from the temperature difference between the measurement volume and the temperature stabilised manometer. Several approaches have been proposed to correct for the pressure difference, but surface and geometric effects usually require that the correction is determined for each gas type and gauge individually. Common (semi) empirical corrections are based on studies of atoms or small molecules. We present a simple calibration method for diaphragm gauges and compare transpiration corrections for argon and styrene at pressures above 1 Pa. We find that characteristic pressures at which the pressure difference reaches half its maximum value, are compatible with the universal scaling p_{1/2} = 2 \\{\\eta} \\cdot \\{v_{th}} / d, thus essentially depending on gas viscosity \\eta, thermal molecular speed v_{th} and gauge tubing diameter d. This contradicts current recommendations based on the Takaishi and Sensui formula, which show an unphysical scaling with molecular size. Our results support the Miller or \\v{S}etina equations where the pressure dependency is basically determined by the Knudsen number. The use of these two schemes is therefore recommended, especially when thermal transpiration has to be predicted for new molecules. Implications for investigations on large polyatomics are discussed.

  18. A critical review on gas diffusion micro and macroporous layers degradations for improved membrane fuel cell durability

    Science.gov (United States)

    Lapicque, Francois; Belhadj, Mariem; Bonnet, Caroline; Pauchet, Joël; Thomas, Yohann

    2016-12-01

    Formerly considered as a secondary component of fuel cell, gas diffusion layers (GDLs) have been shown to have a key role in gas transport to the catalyst layers and in water management: in particular, the microporous layer (MPL) deposited on the diffusion substrate has an active part in water distribution in the membrane electrode assembly and in its efficient removal from the cell. In addition to its perfect design for the targeted application and in combination with the macroporous substrate (MPS), the MPL structure and physicochemical properties have to contribute to the cell durability, which is still considered as insufficient for larger, massive commercialisation of this energy conversion system. The paper is aimed at reviewing the main knowledge gained on the role of the MPL on GDL operation and durability, with investigation of degradation phenomena of both MPL and MPS, together with the role played by the MPL in mitigating the occurrence of degradation phenomena that can occur in the whole fuel cell. In addition to the reviewing purpose, original data on ex-situ degradation of GDL are presented.

  19. Haematological, blood gas and acid-base effects of central histamine-induced reversal of critical haemorrhagic hypotension in rats.

    Science.gov (United States)

    Jochem, J

    2001-09-01

    In a rat model of volume-controlled irreversible haemorrhagic shock, which results in a severe metabolic acidosis and the death of all control animals within 30 min., intracerebroventricular injection of histamine (100 nmol) produces a prompt and long-lasting increase in mean arterial pressure and heart rate, with a 100% survival of 2 h after treatment. Histamine action is accompanied by a decrease in haematocrit value, haemoglobin concentration, erythrocyte and platelet count, and an increase in residual blood volume at the end of the experiment (2 h). Cardiovascular effects are also associated with a long-lasting rise in respiratory rate and biphasic blood acid-base changes - initial increase of metabolic acidosis with the decrease in arterial and venous pH, bicarbonate concentration and base excess, followed by almost a complete recovery of blood gas and acid-base parameters to the pre-bleeding values, with normalisation of arterial and venous pH, Pco2 bicarbonate concentration and base excess at the end of experiment. It can be concluded that in the late phase of central histamine-induced reversal of haemorrhagic hypotension there is almost a complete restoration of blood gas and acid-base status due to circulatory and respiratory compensations, while accompanying haematological changes are the result of the haemodilution and the increase in residual blood volume.

  20. Development of a Binary Mixture Gas Composition Instrument for Use in a Confined High Temperature Environment

    Science.gov (United States)

    Cadell, Seth R.

    With recent advancements in material science, industrial operations are being conducted at higher and higher temperatures. This is apparent in the nuclear industry where a division of the field is working to develop the High Temperature Gas Reactor and the Very High Temperature Gas Reactor concurrently. Both of these facilities will have outlet gas temperatures that are at significantly higher temperatures than the typical water cooled reactor. These increased temperatures provide improved efficiency for the production of hydrogen, provide direct heating for oil refineries, or more efficient electricity generation. As high temperature operations are being developed, instruments capable of measuring the operating parameters must be developed concurrently. Within the gas reactor community there is a need to measure the impurities within the primary coolant. Current devices will not survive the temperature and radiation environments of a nuclear reactor. An instrument is needed to measure the impurities within the coolant while living inside the reactor, where this instrument would measure the amount of the impurity within the coolant. There are many industrial applications that need to measure the ratio of two components, whether it be the amount of particulate in air that is typical to pneumatic pumping, or the liquid to gas ratio in natural gas as it flows through a pipeline. All of the measurements in these applications can be met using a capacitance sensor. Current capacitance sensors are built to operate at ambient temperatures with only one company producing a product that will handle a temperature of up to 400 °C. This maximum operating temperature is much too low to measure the gas characteristics in the High Temperature Gas Reactor. If this measurement technique were to be improved to operate at the expected temperatures, the coolant within the primary loop could be monitored for water leaks in the steam generator, carbon dust buildup entrained in the flow