Substitutionally doped phosphorene: electronic properties and gas sensing.

Science.gov (United States)

Suvansinpan, Nawat; Hussain, Fayyaz; Zhang, Gang; Chiu, Cheng Hsin; Cai, Yongqing; Zhang, Yong-Wei

2016-02-12

Phosphorene, a new elemental two-dimensional material, has attracted increasing attention owing to its intriguing electronic properties. In particular, pristine phospohorene, due to its ultrahigh surface-volume ratio and high chemical activity, has been shown to be promising for gas sensing (Abbas et al 2015 ACS Nano 9 5618). To further enhance its sensing ability, we perform first-principles calculations based on density functional theory to study substitutionally doped phosphorene with 17 different atoms, focusing on structures, energetics, electronic properties and gas sensing. Our calculations reveal that anionic X (X = O, C and S) dopants have a large binding energy and highly dispersive electronic states, signifying the formation of covalent X-P bonds and thus strong structural stability. Alkali atom (Li and Na) doping is found to donate most of the electrons in the outer s-orbital by forming ionic bonds with P, and the band gap decreases by pushing down the conduction band, suggesting that the optical and electronic properties of the doped phosphorene can be tailored. For doping with VIIIB-group (Fe, Co and Ni) elements, a strong affinity is predicted and the binding energy and charge transfer are correlated strongly with their electronegativity. By examining NO molecule adsorption, we find that these metal doped phosphorenes (MDPs) in general exhibit a significantly enhanced chemical activity compared with pristine phosphorene. Our study suggests that substitutionally doped phosphorene shows many intriguing electronic and optic properties different from pristine phosphorene and MDPs are promising in chemical applications involving molecular adsorption and desorption processes, such as materials growth, catalysis, gas sensing and storage.

Gas Sensing Properties of ZnO-SnO2 Nanostructures.

Science.gov (United States)

Chen, Weigen; Li, Qianzhu; Xu, Lingna; Zeng, Wen

2015-02-01

One-dimensional (1D) semiconductor metal oxide nanostructures have attracted increasing attention in electrochemistry, optics, magnetic, and gas sensing fields for the good properties. N-type low dimensional semiconducting oxides such as SnO2 and ZnO have been known for the detection of inflammable or toxic gases. In this paper, we fabricated the ZnO-SnO2 and SnO2 nanoparticles by hydrothermal synthesis. Microstructure characterization was performed using X-ray diffraction (XRD) and surface morphologies for both the pristine and doped samples were observed using field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). Then we made thin film gas sensor to study the gas sensing properties of ZnO-SnO2 and SnO2 gas sensor to H2 and CO. A systematic comparison study reveals an enhanced gas sensing performance for the sensor made of SnO2 and ZnO toward H2 and CO over that of the commonly applied undecorated SnO2 nanoparticles. The improved gas sensing properties are attributed to the size of grains and pronounced electron transfer between the compound nanostructures and the absorbed oxygen species as well as to the heterojunctions of the ZnO nanoparticles to the SnO2 nanoparticles, which provide additional reaction rooms. The results represent an advance of compound nanostructures in further enhancing the functionality of gas sensors, and this facile method could be applicable to many sensing materials, offering a new avenue and direction to detect gases of interest based on composite tin oxide nanoparticles.

Exploitation of Unique Properties of Zeolites in the Development of Gas Sensors

Directory of Open Access Journals (Sweden)

Prabir K. Dutta

2012-04-01

Full Text Available The unique properties of microporous zeolites, including ion-exchange properties, adsorption, molecular sieving, catalysis, conductivity have been exploited in improving the performance of gas sensors. Zeolites have been employed as physical and chemical filters to improve the sensitivity and selectivity of gas sensors. In addition, direct interaction of gas molecules with the extraframework cations in the nanoconfined space of zeolites has been explored as a basis for developing new impedance-type gas/vapor sensors. In this review, we summarize how these properties of zeolites have been used to develop new sensing paradigms. There is a considerable breadth of transduction processes that have been used for zeolite incorporated sensors, including frequency measurements, optical and the entire gamut of electrochemical measurements. It is clear from the published literature that zeolites provide a route to enhance sensor performance, and it is expected that commercial manifestation of some of the approaches discussed here will take place. The future of zeolite-based sensors will continue to exploit its unique properties and use of other microporous frameworks, including metal organic frameworks. Zeolite composites with electronic materials, including metals will lead to new paradigms in sensing. Use of nano-sized zeolite crystals and zeolite membranes will enhance sensor properties and make possible new routes of miniaturized sensors.

Broadening benefits from natural resource extraction: Housing values and taxation of natural gas wells as property

OpenAIRE

Weber, Jeremy G.; Burnett, J.Wesley; Xiarchos, Irene M.

2016-01-01

We study the effects of the property tax base shock caused by natural gas drilling in the Barnett Shale in Texas–a state that taxes oil and gas wells as property. Over the boom and bust in drilling, housing appreciation closely followed the oil and gas property tax base, which expanded the total tax base by 23 percent at its height. The expansion led to a decline in property tax rates while maintaining or increasing revenues to schools. Overall, each $1 per student increase in the oil and gas...

Methanol Gas-Sensing Properties of SWCNT-MIP Composites

Science.gov (United States)

Zhang, Jin; Zhu, Qin; Zhang, Yumin; Zhu, Zhongqi; Liu, Qingju

2016-11-01

The single-walled carbon nanotube (SWCNT)-molecularly imprinted powder (MIP) composites in this paper were prepared by mixing SWCNTs with MIPs. The structure and micrograph of the as-prepared SWCNTs-MIPs samples were characterized by XRD and TEM. The gas-sensing properties were tested through indirect-heating sensors based on SWCNT-MIP composites fabricating on an alumina tube with Au electrodes and Pt wires. The results showed that the structure of SWCNTs-MIPs is of orthogonal perovskite and the average particle size of the SWCNTs-MIPs was in the range of 10-30 nm. SWCNTs-MIPs exhibit good methanol gas-sensitive properties. At 90 °C, the response to 1 ppm methanol is 19.7, and the response to the interferent is lower than 5 to the other interferent gases (ethanol, formaldehyde, toluene, acetone, ammonia, and gasoline). The response time and recovery time are 50 and 58 s, respectively.

Exploratory investigation of the HIPPO gas-jet target fluid dynamic properties

Energy Technology Data Exchange (ETDEWEB)

Meisel, Zach, E-mail: zmeisel@nd.edu [Department of Physics, Joint Institute for Nuclear Astrophysics, University of Notre Dame, Notre Dame, IN 46556 (United States); Shi, Ke; Jemcov, Aleksandar [Hessert Laboratory for Aerospace Research, Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556 (United States); Couder, Manoel [Department of Physics, Joint Institute for Nuclear Astrophysics, University of Notre Dame, Notre Dame, IN 46556 (United States)

2016-08-21

In order to optimize the performance of gas-jet targets for future nuclear reaction measurements, a detailed understanding of the dependence of the gas-jet properties on experiment design parameters is required. Common methods of gas-jet characterization rely on measuring the effective thickness using nuclear elastic scattering and energy loss techniques; however, these tests are time intensive and limit the range of design modifications which can be explored to improve the properties of the jet as a nuclear reaction target. Thus, a more rapid jet-characterization method is desired. We performed the first steps towards characterizing the gas-jet density distribution of the HIPPO gas-jet target at the University of Notre Dame's Nuclear Science Laboratory by reproducing results from {sup 20}Ne(α,α){sup 20}Ne elastic scattering measurements with computational fluid dynamics (CFD) simulations performed with the state-of-the-art CFD software ANSYS Fluent. We find a strong sensitivity to experimental design parameters of the gas-jet target, such as the jet nozzle geometry and ambient pressure of the target chamber. We argue that improved predictive power will require moving to three-dimensional simulations and additional benchmarking with experimental data.

Effect of ozone gas processing on physical and chemical properties ...

African Journals Online (AJOL)

Purpose: To investigate the effects of ozone treatment on chemical and physical properties of wheat (Triticum aestivum L.) gluten, glutenin and gliadin. Methods: Wheat proteins isolated from wheat flour were treated with ozone gas. The physical and chemical properties of gluten proteins were investigated after treatment ...

Pressureless sintering and gas flux properties of porous ceramic membranes for gas applications

Directory of Open Access Journals (Sweden)

David O. Obada

Full Text Available The preparation and characterization of kaolin based ceramic membranes using styrofoam (STY and sawdust (SD as pore formers have been prepared by mechano-chemical synthesis using pressureless sintering technique with porogen content between (0–20 wt% by die pressing. Pellets were fired at 1150 °C and soaking time of 4 h. The membranes cast as circular disks were subjected to characterization studies to evaluate the effect of the sintering temperature and pore former content on porosity, density, water absorption and mechanical strength. Obtained membranes show effective porosity with maximum at about 43 and 47% respectively for membranes formulated with styrofoam and sawdust porogens but with a slightly low mechanical strength that does not exceed 19 MPa. The resultant ceramic bodies show a fine porous structure which is mainly caused by the volatilization of the porogens. The fabricated membrane exhibited high N2 gas flux, hence, these membranes can be considered as efficient for potential application for gas separation by reason of the results shown in the gas flux tests. Keywords: Porosity, Pore formers, Kaolin, Physico-mechanical properties, Gas separation, Gas flux

Effects of superficial gas velocity and fluid property on the ...

African Journals Online (AJOL)

In the present study, the influence of superficial gas velocity and fluid properties on gas holdup and liquid circulation velocity in a three-phase external loop airlift column using polystyrene (0.0036 m diameter and 1025.55 kg/m3 density) and nylon-6 (0.0035 m diameter and 1084.24 kg/m3 density) particles with aqueous ...

Robust and Elastic Polymer Membranes with Tunable Properties for Gas Separation.

Science.gov (United States)

Cao, Peng-Fei; Li, Bingrui; Hong, Tao; Xing, Kunyue; Voylov, Dmitry N; Cheng, Shiwang; Yin, Panchao; Kisliuk, Alexander; Mahurin, Shannon M; Sokolov, Alexei P; Saito, Tomonori

2017-08-09

Polymer membranes with the capability to process a massive volume of gas are especially attractive for practical applications of gas separation. Although much effort has been devoted to develop novel polymer membranes with increased selectivity, the overall gas-separation performance and lifetime of membrane are still negatively affected by the weak mechanical performance, low plasticization resistance and poor physical aging tolerance. Recently, elastic polymer membranes with tunable mechanical properties have been attracting significant attentions due to their tremendous potential applications. Herein, we report a series of urethane-rich PDMS-based polymer networks (U-PDMS-NW) with improved mechanical performance for gas separation. The cross-link density of U-PDMS-NWs is tailored by varying the molecular weight (M n ) of PDMS. The U-PDMS-NWs show up to 400% elongation and tunable Young's modulus (1.3-122.2 MPa), ultimate tensile strength (1.1-14.3 MPa), and toughness (0.7-24.9 MJ/m 3 ). All of the U-PDMS-NWs exhibit salient gas-separation performance with excellent thermal resistance and aging tolerance, high gas permeability (>100 Barrer), and tunable gas selectivity (up to α[P CO 2 /P N 2 ] ≈ 41 and α[P CO 2 /P CH 4 ] ≈ 16). With well-controlled mechanical properties and gas-separation performance, these U-PDMS-NW can be used as a polymer-membrane platform not only for gas separation but also for other applications such as microfluidic channels and stretchable electronic devices.

Connecting the Interstellar Gas and Dust Properties in Distant Galaxies Using Quasar Absorption Systems

Science.gov (United States)

Aller, Monique C.; Dwek, Eliahu; Kulkarni, Varsha P.; York, Donald G.; Welty, Daniel E.; Vladilo, Giovanni; Som, Debopam; Lackey, Kyle; Dwek, Eli; Beiranvand, Nassim;

Properties of nanoparticles affecting simulation of fibrous gas filter performance

International Nuclear Information System (INIS)

Tronville, Paolo; Rivers, Richard

2015-01-01

Computational Fluid Dynamics (CFD) codes allow detailed simulation of the flow of gases through fibrous filter media. When the pattern of gas flow between fibers has been established, simulated particles of any desired size can be “injected” into the entering gas stream, and their paths under the influence of aerodynamic drag, Brownian motion and electrostatic forces tracked. Particles either collide with a fiber, or pass through the entire filter medium. They may bounce off the fiber surface, or adhere firmly to the surface or to particles previously captured. Simulated injection of many particles at random locations in the entering stream allows the average probability of capture to be calculated. Many particle properties must be available as parameters for the equations defining the forces on particles in the gas stream, at the moment of contact with a fiber, and after contact. Accurate values for all properties are needed, not only for predicting particle capture in actual service, but also to validate models for media geometries and computational procedures used in CFD. We present a survey of existing literature on the properties influencing nanoparticle dynamics and adhesion. (paper)

An assessment of gas impact on geological repository. Methodology and material property of gas migration analysis in engineered barrier system

International Nuclear Information System (INIS)

Yamamoto, Mikihiko; Mihara, Morihiro; Ooi, Takao

2004-01-01

Gas production in a geological repository has potential hazard, as overpressurisation and enhanced release of radionuclides. Amongst data needed for assessment of gas impact, gas migration properties of engineered barriers, focused on clayey and cementitious material, was evaluated in this report. Gas injection experiments of saturated bentonite sand mixture, mortar and cement paste were carried out. In the experiments, gas entry phenomenon and gas outflow rate were observed for these materials. Based on the experimental results, two-phase flow parameters were evaluated quantitatively. A conventional continuum two-phase flow model, which is only practically used multidimensional multi-phase flow model, was applied to fit the experimental results. The simulation results have been in good agreement with the gas entry time and the outflow flux of gas and water observed in the experiments. It was confirmed that application of the continuum two-phase flow model to gas migration in cementitious materials provides sufficient degree of accuracy for assessment of repository performance. But, for sand bentonite mixture, further extension of basic two-phase flow model is needed especially for effect of stress field. Furthermore, gas migration property of other barrier materials, including rocks, but long-term gas injection test, clarification of influence of chemicals environment and large-scale gas injection test is needed for multi-barrier assessment tool development and their verification. (author)

Gas amplification properties of GEM foils

International Nuclear Information System (INIS)

Beck, Jeannine

2009-01-01

In the framework of the detector concept International Linear Detector for the future accelerator project International Linear Collider, in which electrons and positrons at c. m. energies of 500 GeV are brought to collision, a time projection chamber shall be applied as central track detector. By the application of such a chamber as track detector a three-dimensional reconstruction of the track points is possible. If a particle passes the gas volume within the chamber it ionizises single gas atoms and the arising electrons move after the amplification in the GEM arrangement to the anode, so that a two-dimensional projection of the particle track is possible. The third dimension is calculated from the drift time of the electrons. The advances of this readout system consist therein that a better position resolution than by a multiwire proportional chamber is reached and the back-drifting ions can be strongly suppressed. Aim of this thesis are studies for a GEM module, which shall be used in a large TPC prototype. Concerning different requirements it is valid to compare different GEMs in order to can meet an optimal choice. In a small prototype present at DESY measurements for the acquisition of GEM-describing parameters were performed. The taking into operation of the test TPC was part of this thesis. Tracks were generated by a radioactive source, by means of which the gas amplification was determined. With the measurement arrangement gas-amplifier foils of different kind were compared in view of their amplification properties and their energy resolution power and systematically studied. Five different GEM performances were studied in the test TPC. These foils differ in their geometrical classification parameters, the fabrication process, or the materials. The GEMs produced at CERN possess in comparison with GEMs of the Japanese firm SciEnergy and a GEM of the US-American firm Tech-Etch the best amplification and resolution properties. Furthermore a new GEM framing

Chemical and physical properties of gas hydrates; Chemische und physikalische Eigenschaften von Gashydraten

Energy Technology Data Exchange (ETDEWEB)

Meyn, V. [Inst. fuer Erdoel- und Erdgasforschung, Clausthal-Zellerfeld (Germany)

1997-12-31

Numerous properties of gas hydrates can be inferred directly from their phase behaviour. The present contribution gives a short overview of the properties of gas hydrates using pressure-temperature curves to depict their phase behaviour. It also describes the growth kinetics and inhibition of gas hydrates. (MSK) [Deutsch] Eine Vielzahl der Eigenschaften von Gashydraten lassen sich direkt aus ihrem Phasenverhalten herleiten. In kurzer Form wird ein Ueberblick ueber die Eigenschaften der Gashydrate gegeben. Druck-Temperatur-Diagramme erlaeutern des Phasenverhalten. Ebenso wird die Wachstumskinetik und die Inhibierung der Gashydrate beschrieben.

Thermodynamic properties calculation of the flue gas based on its composition estimation for coal-fired power plants

International Nuclear Information System (INIS)

Xu, Liang; Yuan, Jingqi

2015-01-01

Thermodynamic properties of the working fluid and the flue gas play an important role in the thermodynamic calculation for the boiler design and the operational optimization in power plants. In this study, a generic approach to online calculate the thermodynamic properties of the flue gas is proposed based on its composition estimation. It covers the full operation scope of the flue gas, including the two-phase state when the temperature becomes lower than the dew point. The composition of the flue gas is online estimated based on the routinely offline assays of the coal samples and the online measured oxygen mole fraction in the flue gas. The relative error of the proposed approach is found less than 1% when the standard data set of the dry and humid air and the typical flue gas is used for validation. Also, the sensitivity analysis of the individual component and the influence of the measurement error of the oxygen mole fraction on the thermodynamic properties of the flue gas are presented. - Highlights: • Flue gas thermodynamic properties in coal-fired power plants are online calculated. • Flue gas composition is online estimated using the measured oxygen mole fraction. • The proposed approach covers full operation scope, including two-phase flue gas. • Component sensitivity to the thermodynamic properties of flue gas is presented.

Structural properties and gas sensing behavior of sol-gel grown nanostructured zinc oxide

Energy Technology Data Exchange (ETDEWEB)

Rajyaguru, Bhargav; Gadani, Keval; Kansara, S. B.; Pandya, D. D.; Shah, N. A.; Solanki, P. S., E-mail: piyush.physics@gmail.com [Department of Physics, Saurashtra University, Rajkot – 360 005 (India); Rathod, K. N.; Solanki, Sapana [Department of Physics, Saurashtra University, Rajkot – 360 005 (India); V.V.P. Engineering College, Gujarat Technological University, Rajkot – 360 005 (India)

2016-05-06

In this communication, we report the results of the studies on structural properties and gas sensing behavior of nanostructured ZnO grown using acetone precursor based modified sol-gel technique. Final product of ZnO was sintered at different temperatures to vary the crystallite size while their structural properties have been studied using X-ray diffraction (XRD) measurement performed at room temperature. XRD results suggest the single phasic nature of all the samples and crystallite size increases from 11.53 to 20.96 nm with increase in sintering temperature. Gas sensing behavior has been studied for acetone gas which indicates that lower sintered samples are more capable to sense the acetone gas and related mechanism has been discussed in the light of crystallite size, crystal boundary density, defect mechanism and possible chemical reaction between gas traces and various oxygen species.

Ordering phenomena and non-equilibrium properties of lattice gas models

International Nuclear Information System (INIS)

Fiig, T.

1994-03-01

This report falls within the general field of ordering processes and non-equilibrium properties of lattice gas models. The theory of diffuse scattering of lattice gas models originating from a random distribution of clusters is considered. We obtain relations between the diffuse part of the structure factor S dif (q), the correlation function C(r), and the size distribution of clusters D(n). For a number of distributions we calculate S dif (q) exactly in one dimension, and discuss the possibility for a Lorentzian and a Lorentzian square lineshape to arise. We discuss the two- and three-dimensional oxygen ordering processes in the high T c superconductor YBa 2 Cu 3 O 6+x based on a simple anisotropic lattice gas model. We calculate the structural phase diagram by Monte Carlo simulation and compared the results with experimental data. The structure factor of the oxygen ordering properties has been calculated in both two and three dimensions by Monte Carlo simulation. We report on results obtained from large scale computations on the Connection Machine, which are in excellent agreement with recent neutron diffraction data. In addition we consider the effect of the diffusive motion of metal-ion dopants on the oxygen ordering properties on YBa 2 Cu 3 O 6+x . The stationary properties of metastability in long-range interaction models are studied by application of a constrained transfer matrix (CTM) formalism. The model considered, which exhibits several metastable states, is an extension of the Blume Capel model to include weak long-range interactions. We show, that the decay rate of the metastable states is closely related to the imaginary part of the equilibrium free-energy density obtained from the CTM formalism. We discuss a class of lattice gas model for dissipative transport in the framework of a Langevin description, which is capable of producing power law spectra for the density fluctuations. We compare with numerical results obtained from simulations of a

Gas desorption properties of ammonia borane and metal hydride composites

International Nuclear Information System (INIS)

Matin, M.R.

2009-01-01

'Full text': Ammonia borane (NH 3 BH 3 ) has been of great interest owing to its ideal combination of low molecular weight and high H 2 storage capacity of 19.6 mass %, which exceeds the current capacity of gasoline. DOE's year 2015 targets involve gravimetric as well as volumetric energy densities. In this work, we have investigated thermal decomposition of ammonia borane and calcium hydride composites at different molar ratio. The samples were prepared by planetary ball milling under hydrogen gas atmosphere pressure of 1Mpa at room temperature for 2, and 10 hours. The gas desorption properties were examined by thermal desorption mass spectroscopy (TDMS). The identification of phases was carried out by X-ray diffraction. The results obtain were shown in fig (a),(b),and (c). Hydrogen desorption properties were observed at all molar ratios, but the desorption temperature is significantly lower at around 70 o C at molar ratio 1:1 as shown in fig (c), and unwanted gas (ammonia) emissions were remarkably suppressed by mixing with the calcium hydride. (author)

Disk Evolution, Element Abundances and Cloud Properties of Young Gas Giant Planets

NARCIS (Netherlands)

Helling, Christiane; Woitke, Peter; Rimmer, Paul B.; Kamp, Inga; Thi, Wing-Fai; Meijerink, Rowin

We discuss the chemical pre-conditions for planet formation, in terms of gas and ice abundances in a protoplanetary disk, as function of time and position, and the resulting chemical composition and cloud properties in the atmosphere when young gas giant planets form, in particular discussing the

The properties of the wood-polystyrene interphase determined by inverse gas chromatography

Science.gov (United States)

John Simonsen; Zhenqiu Hong; Timothy G. Rials

1997-01-01

The properties of the interphase in wood-polymer composites are important determinants of the properties of the final composite. This study used inverse gas chromatography (IGC) to measure interphasal properties of composites of polystyrene and two types of wood fiber fillers and an inoranic substrate (CW) with varying amounts of surface coverage of polystyrene. Glass...

Gas separation properties of new polyoxadiazole and polytriazole membranes

NARCIS (Netherlands)

Hensema, E.R.; Hensema, E.R.; Borges-Sena, M.E.R.; Mulder, M.H.V.; Smolders, C.A.; Smolders, C.A.

1994-01-01

The gas separation properties of new aromatic poly-1,2,4-triazole and poly-1,3,4-oxadiazole membranes have been systematically investigated. Various functional groups were incorporated as pendent groups onto the polymer backbone of poly-1,2,4-triazoles. A wide permeability/selectivity spectrum was

Properties of super alloys for high temperature gas cooled reactor

International Nuclear Information System (INIS)

Izaki, Takashi; Nakai, Yasuo; Shimizu, Shigeki; Murakami, Takashi

1975-01-01

The existing data on the properties at high temperature in helium gas of iron base super alloys. Incoloy-800, -802 and -807, nickel base super alloys, Hastelloy-X, Inconel-600, -617 and -625, and a casting alloy HK-40 were collectively evaluated from the viewpoint of the selection of material for HTGRs. These properties include corrosion resistance, strength and toughness, weldability, tube making, formability, radioactivation, etc. Creep strength was specially studied, taking into consideration the data on the creep characteristics in the actual helium gas atmosphere. The necessity of further long run creep data is suggested. Hastelloy-X has completely stable corrosion resistance at high temperature in helium gas. Incoloy 800 and 807 and Inconel 617 are not preferable in view of corrosion resistance. The creep strength of Inconel 617 extraporated to 1,000 deg C for 100,000 hours in air was the greatest rupture strength of 0.6 kg/mm 2 in all above alloys. However, its strength in helium gas began to fall during a relatively short time, so that its creep strength must be re-evaluated in the use for long time. The radioactivation and separation of oxide film in primary construction materials came into question, Inconel 617 and Incoloy 807 showed high induced radioactivity intensity. Generally speaking, in case of nickel base alloys such as Hastelloy-X, oxide film is difficult to break away. (Iwakiri, K.)

Characterization of thermal, hydraulic, and gas diffusion properties in variably saturated sand grades

DEFF Research Database (Denmark)

Deepagoda Thuduwe Kankanamge Kelum, Chamindu; Smits, Kathleen; Ramirez, Jamie

2016-01-01

porous media transport properties, key transport parameters such as thermal conductivity and gas diffusivity are particularly important to describe temperature-induced heat transport and diffusion-controlled gas transport processes, respectively. Despite many experimental and numerical studies focusing...... transport models (thermal conductivity, saturated hydraulic conductivity, and gas diffusivity). An existing thermal conductivity model was improved to describe the distinct three-region behavior in observed thermal conductivity–water saturation relations. Applying widely used parametric models for saturated......Detailed characterization of partially saturated porous media is important for understanding and predicting vadose zone transport processes. While basic properties (e.g., particle- and pore-size distributions and soil-water retention) are, in general, essential prerequisites for characterizing most...

Protocol for Measuring the Thermal Properties of a Supercooled Synthetic Sand-water-gas-methane Hydrate Sample.

Science.gov (United States)

Muraoka, Michihiro; Susuki, Naoko; Yamaguchi, Hiroko; Tsuji, Tomoya; Yamamoto, Yoshitaka

2016-03-21

Methane hydrates (MHs) are present in large amounts in the ocean floor and permafrost regions. Methane and hydrogen hydrates are being studied as future energy resources and energy storage media. To develop a method for gas production from natural MH-bearing sediments and hydrate-based technologies, it is imperative to understand the thermal properties of gas hydrates. The thermal properties' measurements of samples comprising sand, water, methane, and MH are difficult because the melting heat of MH may affect the measurements. To solve this problem, we performed thermal properties' measurements at supercooled conditions during MH formation. The measurement protocol, calculation method of the saturation change, and tips for thermal constants' analysis of the sample using transient plane source techniques are described here. The effect of the formation heat of MH on measurement is very small because the gas hydrate formation rate is very slow. This measurement method can be applied to the thermal properties of the gas hydrate-water-guest gas system, which contains hydrogen, CO2, and ozone hydrates, because the characteristic low formation rate of gas hydrate is not unique to MH. The key point of this method is the low rate of phase transition of the target material. Hence, this method may be applied to other materials having low phase-transition rates.

The study of electronic structure and properties of silicene for gas sensor application

Energy Technology Data Exchange (ETDEWEB)

Wella, Sasfan A.; Syaputra, Marhamni; Wungu, Triati D. K., E-mail: triati@fi.itb.ac.id; Suprijadi [Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung Jl. Ganesha 10 Bandung 40132, West Java (Indonesia)

2016-03-11

In this study, we investigated the adsorption of gas molecules (H{sub 2}S, CO) on pristine silicene using first principles calculation. The structure, electronic properties, and adsorption energy of H{sub 2}S,CO/silicene are discussed thoroughly. We found that the pristine silicenewith low buckling structure is the most stable as compared with planar and high buckling structures. Silicene was able to detect a gas molecule which can be observed according tothe density of states analysis. Though a gas molecule adsorbed weakly, the electronic properties of the low buckling pristine silicene changed from semi-metal (zero band gap) to semiconductor. The adsorption energy of H{sub 2}S and CO on silicene is 0.075 eV and 0.06 eV, respectively.

Disk Evolution, Element Abundances and Cloud Properties of Young Gas Giant Planets

Directory of Open Access Journals (Sweden)

Christiane Helling

2014-04-01

Full Text Available We discuss the chemical pre-conditions for planet formation, in terms of gas and ice abundances in a protoplanetary disk, as function of time and position, and the resulting chemical composition and cloud properties in the atmosphere when young gas giant planets form, in particular discussing the effects of unusual, non-solar carbon and oxygen abundances. Large deviations between the abundances of the host star and its gas giants seem likely to occur if the planet formation follows the core-accretion scenario. These deviations stem from the separate evolution of gas and dust in the disk, where the dust forms the planet cores, followed by the final run-away accretion of the left-over gas. This gas will contain only traces of elements like C, N and O, because those elements have frozen out as ices. PRODIMO protoplanetary disk models are used to predict the chemical evolution of gas and ice in the midplane. We find that cosmic rays play a crucial role in slowly un-blocking the CO, where the liberated oxygen forms water, which then freezes out quickly. Therefore, the C/O ratio in the gas phase is found to gradually increase with time, in a region bracketed by the water and CO ice-lines. In this regions, C/O is found to approach unity after about 5 Myrs, scaling with the cosmic ray ionization rate assumed. We then explore how the atmospheric chemistry and cloud properties in young gas giants are affected when the non-solar C/O ratios predicted by the disk models are assumed. The DRIFT cloud formation model is applied to study the formation of atmospheric clouds under the influence of varying premordial element abundances and its feedback onto the local gas. We demonstrate that element depletion by cloud formation plays a crucial role in converting an oxygen-rich atmosphere gas into carbon-rich gas when non-solar, premordial element abundances are considered as suggested by disk models.

Electrical conduction and NO{sub 2} gas sensing properties of ZnO nanorods

Energy Technology Data Exchange (ETDEWEB)

Şahin, Yasin [Council of Forensic Medicine, Bahçelievler, 34196 Istanbul (Turkey); Öztürk, Sadullah, E-mail: sadullahozturk@gyte.edu.tr [Gebze Institute of Technology, Science Faculty, Department of Physics, 41400 Gebze, Kocaeli (Turkey); Kılınç, Necmettin [Gebze Institute of Technology, Science Faculty, Department of Physics, 41400 Gebze, Kocaeli (Turkey); Koc University, Department of Electrical and Electronics Engineering, Sariyer, 34450 Istanbul (Turkey); Kösemen, Arif [Gebze Institute of Technology, Science Faculty, Department of Physics, 41400 Gebze, Kocaeli (Turkey); Mus Alparslan University, Department of Physics, 49100 Mus (Turkey); Erkovan, Mustafa [SAKARYA University, Engineering Faculty, Department of Metallurgical and Materials Engineering, Esentepe Campus, 54187 Sakarya (Turkey); Öztürk, Zafer Ziya [Gebze Institute of Technology, Science Faculty, Department of Physics, 41400 Gebze, Kocaeli (Turkey); TÜBİTAK-Marmara Research Center, Materials Institute, 41470 Gebze, Kocaeli (Turkey)

2014-06-01

Thermally stimulated current (TSC), photoresponse and gas sensing properties of zinc oxide (ZnO) nanorods were investigated depending on heating rates, illumination and dark aging times with using sandwich type electrode system. Vertically aligned ZnO nanorods were grown on indium tin oxide (ITO) coated glass substrate by hydrothermal process. TSC measurements were performed at different heating rates under constant potential. Photoresponse and gas sensing properties were investigated in dry air ambient at 200 °C. For gas sensing measurements, ZnO nanorods were exposed to NO{sub 2} (100 ppb to 1 ppm) in dark and illuminated conditions and the resulting resistance transient was recorded. It was found from dark electrical measurements that the dependence of the dc conductivity on temperature followed Mott's variable range hopping (VRH) model. In addition, response time and recovery times of ZnO nanorods to NO{sub 2} gas decreased by exposing to white light.

A review of the implications of sour gas setbacks on the ability to develop property : public safety and sour gas recommendation 53

International Nuclear Information System (INIS)

2005-09-01

All sour gas facilities in Alberta have a required setback, which is the minimum distance that must be maintained between the energy facility and a dwelling, rural housing development, urban centre or public facility. The size of the setback depends on the classification levels of the sour gas facilities. This paper reviewed the economic implications of sour gas setback restrictions for landowners with reference to Recommendation 53. The methodology of the study included a telephone and electronic mail survey to prequalify municipalities, cities and towns located in the sour gas producing regions of Alberta and the selection of 11 cases for further detailed analysis. The findings of the survey and case studies were then used to examine whether landowners were treated fairly in cases where a setback impact occurred. The frequency of setback incidents was described as common by 13 jurisdictions, occasional by 33 jurisdictions and as emerging by 30 jurisdictions. Results indicated that impacts on property development due to sour gas setbacks were widespread across the province. Observed mitigation measures included the modification of development plans by landowners to avoid setback restrictions; encouraging land development proposals away from areas known to have sour gas activity; and the oil and gas industry working with landowners to locate proposed facilities in order to minimize setback restrictions. Results of the survey suggested that ineffective communication was the predominant factor leading to conflicts, particularly when parties were not familiar with setback requirements or the implications for property development. It was suggested that policy makers should aim to reduce the number of conflicts between sour gas setbacks and property development. Recommendations to improve communication included closing gaps in regulations, processes and practices; and reducing surface and subsurface interface conflicts. 9 refs., 1 tab., 4 figs

The effect of the reference frame on the thermophysical properties of an ideal gas

International Nuclear Information System (INIS)

Speziale, Cg.

1986-01-01

The effect that the frame of reference has on the thermophysical properties of an ideal gas is examined from a fundamental theoretical standpoint based on the Boltzmann equation. In continuum mechanics, the principle of material frame in deference forbids the thermophysical properties of a fluid or solid to depend in any way on the motion of the reference frame. It is demonstrated that the Boltzmann equation is only consistent with material frame-indeffrence in a strong approximate sense provided that the gas is not highly rarefield and, thus, well within the limits of classical continuum mechanics. Estimates of the mean free times for which material frame-indifference can be invoked in the modeling of gas flows are provided from an analysis of the problem of heat conduction in a rigidly rotating gas. Applications of these results in obtaining asymptotic solutions of the Boltzmann equation for the continuum description of an ideal gas are discussed briefly

Improving methane gas sensing properties of multi-walled carbonnanotubes by vanadium oxide filling

CSIR Research Space (South Africa)

Chimowa, George

2017-08-01

Full Text Available Manipulation of electrical properties and hence gas sensing properties of multi-walled carbon nanotubes (MWNTs) by filling the inner wall with vanadium oxide is presented. Using a simple capillary technique, MWNTs are filled with vanadium metal...

Gas Exchange and Mechanical Properties of the Lung in Miners with Severe Concomitant Injury

Directory of Open Access Journals (Sweden)

V. V. Moroz

2007-01-01

Full Text Available Objective: to study the specific features of pulmonary gas exchange and mechanical properties in various manifestations of respiratory failure in miners with severe concomitant injury, who have a service length of 10 years or more, in order to optimize respiratory support.Subjects and methods. Pulmonary gas exchange and mechanical properties were studied over time in the presence of respiratory failure (acute lung injury/acute respiratory distress syndrome in 34 miners and 36 victims (a control group with severe concomitant injury who had no underground service length. Both groups were matched in age, severity and nature of traumatic lesions and surgical interventions. Pulmonary gas exchange and mechanical properties were evaluated by the following indices: oxygen fraction in an inspired gas mixture; hemoglobin saturation and partial arterial blood oxygen and carbon dioxide tension with the alveolar-arterial gradient being calculated by the oxygen level; oxygenation index; intrapulmonary shunting; statistical compliance and airways resistance.Results. The studies demonstrated that the miners, as compared with the controls, had more pronounced gas exchange changes within 5—7 post-traumatic days; later on (days 7—9 the above differences were undetectable. Impaired pulmonary mechanical properties in the miners persisted throughout the study while in the control group, their recovery started just on day 3. The course of respiratory failure in the miners was attributable to the baseline external respiratory function. Their respiratory support was performed during 14.5±1.4 days versus 9.5±1.9 days in the controls. In the miners, the mean bed-days at an intensive care unit were 18.5±2.2 whereas in the controls those were 12.3±2.1.Conclusion. More significant impairments of pulmonary gas exchange and mechanical properties are seen in the miners due to the background changes in external respiratory function in the development of respiratory

Enhancement of Gas Barrier Properties of CFRP Laminates Fabricated Using Thin-Ply Prepregs

Science.gov (United States)

横関, 智弘; 高木, 智宏; 吉村, 彰記; Ogasawara, Toshio; 荻原, 慎二

Composite laminates manufactured using thin-ply prepregs are expected to have superior resistance properties against microcracking compared to those using standard prepregs. In this study, comparative investigations are presented on the microcrack accumulation and gas leakage characteristics of CFRP laminates fabricated using standard and thin-ply prepregs, consisting of high-performance carbon fiber and toughened epoxy, as a fundamental research on the cryogenic composite tanks for future space vehicles. It was shown that laminates using thin-ply prepregs exhibited much higher strain at microcrack initiation compared to those using standard prepregs at room and cryogenic temperatures. In addition, helium gas leak tests using CFRP laminated tubular specimens subjected to quasi-static tension loadings were performed. It was demonstrated that CFRP laminates using thin-ply prepregs have higher gas barrier properties than those using standard prepregs.

Controlled Synthesis of Hierarchically Assembled Porous ZnO Microspheres with Enhanced Gas-Sensing Properties

Directory of Open Access Journals (Sweden)

Shengsheng You

2015-01-01

Full Text Available The ZnO microspheres constructed by porous nanosheets were successfully synthesized by calcinating zinc hydroxide carbonate (ZHC microspheres obtained by a sample hydrothermal method. The samples were characterized in detail with scanning electron microscopy (SEM, transmission electron microscopy (TEM, X-ray diffraction (XRD, and thermogravimetric and differential scanning calorimetry (TG-DSC. The results indicated that the prepared ZnO microspheres were well crystalline with wurtzite hexagonal phase. The effects of reaction time, temperature, the amount of trisodium citrate, and urea on the morphology of ZnO microspheres were studied. The formation mechanism of porous ZnO microspheres was discussed. Furthermore, the gas-sensing properties for detection of organic gas of the prepared porous ZnO microspheres were investigated. The results indicated that the prepared porous ZnO microspheres exhibited high gas-sensing properties for detection of ethanol gas.

How much due diligence is enough? (in oil and gas property transactions)

International Nuclear Information System (INIS)

Edie, D.C.

1999-01-01

The issue of due diligence for oil and gas property transactions was discussed, with particular emphasis on how to find an appropriate balance between cost and protection (risk aversion) within an available time period. The paper focused primarily on oil and gas reserves transactions comprised of petroleum and natural gas rights, leases, operating and title documents, tangibles and the regulatory authorizations needed to acquire, hold and operate these assets. Various concerns related to gas processing plants and pipeline facilities were also treated. Issues of due diligence that should always be raised were emphasized. These are: (1) acceptability of the purchaser to the Alberta Energy and Utilities Board or other regulators as an operator for the purposes of transfer of well and facility licenses, (2) assessment of the purchaser's financial status for environmental liabilities relating to the assets following closing, (3) in an asset swap, property due diligence will be the same for both parties, and (4) where the assets are sold in exchange for stock, the purchaser should at least address concerns about the purchaser's liquidity, the purchaser's underlying asset value, and necessary regulatory authorizations to issue the stock. 10 refs

Measurement of gas transport properties for chemical vapor infiltration

Energy Technology Data Exchange (ETDEWEB)

Starr, T.L.; Hablutzel, N. [Georgia Inst. of Tech., Atlanta, GA (United States). School of Materials Science and Engineering

1996-12-01

In the chemical vapor infiltration (CVI) process for fabricating ceramic matrix composites (CMCs), transport of gas phase reactant into the fiber preform is a critical step. The transport can be driven by pressure or by concentration. This report describes methods for measuring this for CVI preforms and partially infiltrated composites. Results are presented for Nicalon fiber cloth layup preforms and composites, Nextel fiber braid preforms and composites, and a Nicalon fiber 3-D weave composite. The results are consistent with a percolating network model for gas transport in CVI preforms and composites. This model predicts inherent variability in local pore characteristics and transport properties, and therefore, in local densification during processing; this may lead to production of gastight composites.

The effect of the stretching of PLA extruded films on their crystallinity and gas barrier properties

Science.gov (United States)

Guinault, A.; Menary, G. H.; Courgneau, C.; Griffith, D.; Ducruet, V.; Miri, V.; Sollogoub, C.

2011-05-01

Driven by environmental concerns, new polymers based on renewable resources are arriving on the market to replace conventional polymers, obtained from petroleum, for different applications like food packaging. One of the most prominent polymers among these materials is poly(lactic acid) (PLA), a biodegradable, thermoplastic, aliphatic polyester derived from renewable resources, such as corn starch (in the USA) or sugarcanes (in the rest of the world). However this polymer presents different disadvantages and especially low gas barrier properties [1]. Thermal crystallization can be used to increase its gas barrier properties but long times are necessary [2] and are not compatible with an industrial process. Another way to increase the gas barrier properties consists in stretching the film in order to increase its crystallinity and so its diffusion coefficient. We have prepared stretched PLA films with different stretch ratio and we have studied the effect of the stretching parameters on the gas barrier properties of PLA films. Finally we compared this process with the isothermal crystallization process by taking into account the crystallinity degree and the crystalline morphology.

Nuclear Well Log Properties of Natural Gas Hydrate Reservoirs

Science.gov (United States)

Burchwell, A.; Cook, A.

2015-12-01

Characterizing gas hydrate in a reservoir typically involves a full suite of geophysical well logs. The most common method involves using resistivity measurements to quantify the decrease in electrically conductive water when replaced with gas hydrate. Compressional velocity measurements are also used because the gas hydrate significantly strengthens the moduli of the sediment. At many gas hydrate sites, nuclear well logs, which include the photoelectric effect, formation sigma, carbon/oxygen ratio and neutron porosity, are also collected but often not used. In fact, the nuclear response of a gas hydrate reservoir is not known. In this research we will focus on the nuclear log response in gas hydrate reservoirs at the Mallik Field at the Mackenzie Delta, Northwest Territories, Canada, and the Gas Hydrate Joint Industry Project Leg 2 sites in the northern Gulf of Mexico. Nuclear logs may add increased robustness to the investigation into the properties of gas hydrates and some types of logs may offer an opportunity to distinguish between gas hydrate and permafrost. For example, a true formation sigma log measures the thermal neutron capture cross section of a formation and pore constituents; it is especially sensitive to hydrogen and chlorine in the pore space. Chlorine has a high absorption potential, and is used to determine the amount of saline water within pore spaces. Gas hydrate offers a difference in elemental composition compared to water-saturated intervals. Thus, in permafrost areas, the carbon/oxygen ratio may vary between gas hydrate and permafrost, due to the increase of carbon in gas hydrate accumulations. At the Mallik site, we observe a hydrate-bearing sand (1085-1107 m) above a water-bearing sand (1107-1140 m), which was confirmed through core samples and mud gas analysis. We observe a decrease in the photoelectric absorption of ~0.5 barnes/e-, as well as an increase in the formation sigma readings of ~5 capture units in the water-bearing sand as

Research on insulating material affecting the property of gas ionization chamber

International Nuclear Information System (INIS)

Wang Liqiang; Wang Zhentao; Zheng Jian

2014-01-01

The insulating material in ionization chamber affects the internal gas pressure and ionic pulse shape in the research process of the ion drift velocity in high pressure gas ionization chamber. It will affect the ion drift velocity measurement. It is required to isolate by insulating material between electrode to electrode and between electrodes to the shell of gas ionization chamber. Insulating material in gas ionization chamber is indispensable. Therefore it needs to carefully study the insulating material affecting the performance of gas ionization chamber. First of all, it is found that Teflon can slowly adsorb the working gas in ionization chamber, and the gas pressure in it is reduced when we measure the sensitivity of gas ionization chamber over time. It is verified by experiment that insulating materials absorbing and releasing gas is dynamically reversible process. Then the adsorbing gas property of 95% aluminium oxide ceramic and Teflon is studied through experimental comparision. Gas adsorption equilibrium time of ceramic material is faster, generally it is about a few hours, and the gas adsorption capacity is relatively less. Gas adsorption equilibrium time of Teflon is slower, it is about a few days, and the gas adsorption capacity is relatively more. It is found that Teflon will release part of the gas at higher temperature through experimental research on the influence of Teflon adsorbing gas. Finally it is studied that the distribution of insulation in ionization chamber affects the time response speed of ionization chamber by measuring the signal pulse shape of ionization chamber under the pulse X-ray. Through these experimental research, it is presented that it need to pay attention to select insulation material and to design the internal structure and arrangement of insulating material when we design gas ionization chamber. (authors)

Physical properties and rock physics models of sediment containing natural and laboratory-formed methane gas hydrate

Science.gov (United States)

Winters, W.J.; Pecher, I.A.; Waite, W.F.; Mason, D.H.

2004-01-01

This paper presents results of shear strength and acoustic velocity (p-wave) measurements performed on: (1) samples containing natural gas hydrate from the Mallik 2L-38 well, Mackenzie Delta, Northwest Territories; (2) reconstituted Ottawa sand samples containing methane gas hydrate formed in the laboratory; and (3) ice-bearing sands. These measurements show that hydrate increases shear strength and p-wave velocity in natural and reconstituted samples. The proportion of this increase depends on (1) the amount and distribution of hydrate present, (2) differences, in sediment properties, and (3) differences in test conditions. Stress-strain curves from the Mallik samples suggest that natural gas hydrate does not cement sediment grains. However, stress-strain curves from the Ottawa sand (containing laboratory-formed gas hydrate) do imply cementation is present. Acoustically, rock physics modeling shows that gas hydrate does not cement grains of natural Mackenzie Delta sediment. Natural gas hydrates are best modeled as part of the sediment frame. This finding is in contrast with direct observations and results of Ottawa sand containing laboratory-formed hydrate, which was found to cement grains (Waite et al. 2004). It therefore appears that the microscopic distribution of gas hydrates in sediment, and hence the effect of gas hydrate on sediment physical properties, differs between natural deposits and laboratory-formed samples. This difference may possibly be caused by the location of water molecules that are available to form hydrate. Models that use laboratory-derived properties to predict behavior of natural gas hydrate must account for these differences.

Superior Gas Sensing Properties of Monolayer PtSe2

KAUST Repository

Sajjad, Muhammad

2016-12-15

First-principles calculations of the structural and electronic properties of monolayer 1T-PtSe2 with adsorbed (a) NO2, (b) NO, (c) NH3, (d) H2O, (e) CO2, and (f) CO molecules are discussed. The results point to great potential of the material in gas sensor applications. Superior sensitivity is demonstrated by transport calculations using the nonequilibrium Green\\'s function method.

Influence of gas injection on viscous and viscoelastic properties of Xanthan gum.

Science.gov (United States)

Bobade, Veena; Cheetham, Madalyn; Hashim, Jamal; Eshtiaghi, Nicky

2018-05-01

Xanthan gum is widely used as a model fluid for sludge to mimic the rheological behaviour under various conditions including impact of gas injection in sludge. However, there is no study to show the influence of gas injection on rheological properties of xanthan gum specifically at the concentrations at which it is used as a model fluid for sludge with solids concentration above 2%. In this paper, the rheological properties of aqueous xanthan gum solutions at different concentrations were measured over a range of gas injection flow rates. The effect of gas injection on both the flow and viscoelastic behaviour of Xanthan gum (using two different methods - a creep test and a time sweep test) was evaluated. The viscosity curve of different solid concentrations of digested sludge and waste activated sludge were compared with different solid concentrations of Xanthan gum and the results showed that Xanthan gum can mimic the flow behaviour of sludge in flow regime. The results in linear viscoelastic regime showed that increasing gas flow rate increases storage modulus (G'), indicating an increase in the intermolecular associations within the material structure leading to an increase in material strength and solid behaviour. Similarly, in creep test an increase in the gas flow rate decreased strain%, signifying that the material has become more resistant to flow. Both observed behaviour is opposite to what occurs in sludge under similar conditions. The results of both the creep test and the time sweep test indicated that choosing Xanthan gum aqueous solution as a transparent model fluid for sludge in viscoelastic regime under similar conditions involving gas injection in a concentration range studied is not feasible. However Xanthan gum can be used as a model material for sludge in flow regime; because it shows a similar behaviour to sludge. Copyright © 2018 Elsevier Ltd. All rights reserved.

The Effect of Zeolite Composition and Grain Size on Gas Sensing Properties of SnO2/Zeolite Sensor

Directory of Open Access Journals (Sweden)

Yanhui Sun

2018-01-01

Full Text Available In order to improve the sensing properties of tin dioxide gas sensor, four kinds of different SiO2/Al2O3 ratio, different particle size of MFI type zeolites (ZSM-5 were coated on the SnO2 to prepared zeolite modified gas sensors, and the gas sensing properties were tested. The measurement results showed that the response values of ZSM-5 zeolite (SiO2/Al2O3 = 70, grain size 300 nm coated SnO2 gas sensors to formaldehyde vapor were increased, and the response to acetone decreased compared with that of SnO2 gas sensor, indicating an improved selectivity property. The other three ZSM-5 zeolites with SiO2/Al2O3 70, 150 and 470, respectively, and grain sizes all around 1 μm coated SnO2 sensors did not show much difference with SnO2 sensor for the response properties to both formaldehyde and acetone. The sensing mechanism of ZSM-5 modified sensors was briefly analyzed.

Investigations on the properties of gas telescopes with three-piece measuring volume concerning their application for the spectrometry of fast neutrons

International Nuclear Information System (INIS)

Borst, H.

1976-07-01

In this paper, the properties of gas telescopes with three-piece measuring volume are analyzed. First, the principle of measurement on which gas telescopes are based is explained and ranges of application resulting from it as well as principles of possible realizations are discussed. Then a new theory of proportional gas amplification is derived in its application on methane gas, whose results are used in further descriptions. The following section deals with energy-dependent properties of gas telescopes. Here, it is shown that neutron energies above 100 keV can be measured with gas telescopes. In a further section, the prototype is described and its theoretical properties are shown. Finally, alternative possibilties of design are given from which good properties may be expected, even with accompanying gamma rays. (orig./GSC) [de

Properties of samples containing natural gas hydrate from the JAPEX/JNOC/GSC Mallik 2L-38 gas hydrate research well, determined using Gas Hydrate And Sediment Test Laboratory Instrument (GHASTLI)

Science.gov (United States)

Winters, W.J.

1999-01-01

As part of an ongoing laboratory study, preliminary acoustic, strength, and hydraulic conductivity results are presented from a suite of tests conducted on four natural-gas-hydrate-containing samples from the Mackenzie Delta JAPEX/JNOC/GSC Mallik 2L-38 gas hydrate research well. The gas hydrate samples were preserved in pressure vessels during transport from the Northwest Territories to Woods Hole, Massachusetts, where multistep tests were performed using GHASTLI (Gas Hydrate And Sediment Test Laboratory Instrument), which recreates pressure and temperature conditions that are stable for gas hydrate. Properties and changes in sediment behaviour were measured before, during, and after controlled gas hydrate dissociation. Significant amounts of gas hydrate occupied the sample pores and substantially increased acoustic velocity and shear strength.

Hydro-mechanical and gas transport properties of bentonite blocks - role of interfaces

International Nuclear Information System (INIS)

Popp, Till; Roehlke, Christopher; Salzer, Klaus; Gruner, Matthias

2012-01-01

Document available in extended abstract form only. The long-term safety of the disposal of nuclear waste is an important issue in all countries with a significant nuclear programme. Repositories for the disposal of high-level and long-lived radioactive waste generally rely on a multi-barrier system to isolate the waste from the biosphere. The multi-barrier system typically comprises the natural geological barrier provided by the repository host rock and its surroundings and an engineered barrier system (EBS), i.e. the backfilling and sealing of shafts and galleries to block any preferential path for radioactive contaminants. Because gas will be created in a radioactive waste repository performance assessment requires quantification of the relevancy of various potential pathways. Referring to the sealing plugs it is expected that in addition to the matrix properties of the sealing material conductive discrete interfaces inside the sealing elements itself and to the host rock may act not only as mechanical weakness planes but also as preferential gas pathways (Popp, 2009). For instance despite the assumed self sealing capacity of bentonite inherent existing interfaces may be reopened during gas injection. Our lab investigations are aiming on a comprehensive hydro-mechanical characterization of interfaces in bentonite buffers, i.e. (1) between prefabricated bentonite blocks itself and (2) on mechanical contacts of bentonite blocks and concrete to various host rocks, i.e. granite. We used as reference material pre-compacted bentonite blocks consisting of a sand clay-bentonite mixture but the variety of bentonite-based buffer materials has to be taken in mind. The blocks were manufactured in the frame work of the so-called dam - project 'Sondershausen', i.e. a German research project performed between 1997 and 2002. The blocks have a standard size of (250 x 125 x 62.5) mm. Approximately 500 t of such bentonite blocks have been produced and assembled in underground drift

Towards the development of rapid screening techniques for shale gas core properties

Science.gov (United States)

Cave, Mark R.; Vane, Christopher; Kemp, Simon; Harrington, Jon; Cuss, Robert

2013-04-01

Shale gas has been produced for many years in the U.S.A. and forms around 8% of total their natural gas production. Recent testing for gas on the Fylde Coast in Lancashire UK suggests there are potentially large reserves which could be exploited. The increasing significance of shale gas has lead to the need for deeper understanding of shale behaviour. There are many factors which govern whether a particular shale will become a shale gas resource and these include: i) Organic matter abundance, type and thermal maturity; ii) Porosity-permeability relationships and pore size distribution; iii) Brittleness and its relationship to mineralogy and rock fabric. Measurements of these properties require sophisticated and time consuming laboratory techniques (Josh et al 2012), whereas rapid screening techniques could provide timely results which could improve the efficiency and cost effectiveness of exploration. In this study, techniques which are portable and provide rapid on-site measurements (X-ray Fluorescence (XRF) and Infra-red (IR) spectroscopy) have been calibrated against standard laboratory techniques (Rock-Eval 6 analyser-Vinci Technologies) and Powder whole-rock XRD analysis was carried out using a PANalytical X'Pert Pro series diffractometer equipped with a cobalt-target tube, X'Celerator detector and operated at 45kV and 40mA, to predict properties of potential shale gas material from core material from the Bowland shale Roosecote, south Cumbria. Preliminary work showed that, amongst various mineralogical and organic matter properties of the core, regression models could be used so that the total organic carbon content could be predicted from the IR spectra with a 95 percentile confidence prediction error of 0.6% organic carbon, the free hydrocarbons could be predicted with a 95 percentile confidence prediction error of 0.6 mgHC/g rock, the bound hydrocarbons could be predicted with a 95 percentile confidence prediction error of 2.4 mgHC/g rock, mica content

TiO2 Nanotubes: Recent Advances in Synthesis and Gas Sensing Properties

Directory of Open Access Journals (Sweden)

Giorgio Sberveglieri

2013-10-01

Full Text Available Synthesis—particularly by electrochemical anodization-, growth mechanism and chemical sensing properties of pure, doped and mixed titania tubular arrays are reviewed. The first part deals on how anodization parameters affect the size, shape and morphology of titania nanotubes. In the second part fabrication of sensing devices based on titania nanotubes is presented, together with their most notable gas sensing performances. Doping largely improves conductivity and enhances gas sensing performances of TiO2 nanotubes

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

Microstructure and mechanical properties of aluminum 5083 weldments by gas tungsten arc and gas metal arc welding

International Nuclear Information System (INIS)

Liu Yao; Wang Wenjing; Xie Jijia; Sun Shouguang; Wang Liang; Qian Ye; Meng Yuan; Wei Yujie

2012-01-01

Highlights: ► Welding zones by GTAW and GMAW are softer than the parent material Al5083. ► GTAW for Al5083 are mechanically more reliable than that welded by GMAW. ► GTAW welds fail by shear, but GMAW welds show mixed shear and normal failure. - Abstract: The mechanical properties and microstructural features of aluminum 5083 (Al5083) weldments processed by gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) are investigated. Weldments processed by both methods are mechanically softer than the parent material Al5083, and could be potential sites for plastic localization. It is revealed that Al5083 weldments processed by GTAW are mechanical more reliable than those by GMAW. The former bears higher strength, more ductility, and no apparent microstructure defects. Perceivable porosity in weldments by GMAW is found, which could account for the distinct mechanical properties between weldments processed by GTAW and GMAW. It is suggested that caution should be exercised when using GMAW for Al5083 in the high-speed-train industry where such light weight metal is broadly used.

Improving gas sensing properties of graphene by introducing dopants and defects: a first-principles study

International Nuclear Information System (INIS)

Zhang Yonghui; Chen Yabin; Zhou Kaige; Liu Caihong; Zeng Jing; Zhang Haoli; Peng Yong

2009-01-01

The interactions between four different graphenes (including pristine, B- or N-doped and defective graphenes) and small gas molecules (CO, NO, NO 2 and NH 3 ) were investigated by using density functional computations to exploit their potential applications as gas sensors. The structural and electronic properties of the graphene-molecule adsorption adducts are strongly dependent on the graphene structure and the molecular adsorption configuration. All four gas molecules show much stronger adsorption on the doped or defective graphenes than that on the pristine graphene. The defective graphene shows the highest adsorption energy with CO, NO and NO 2 molecules, while the B-doped graphene gives the tightest binding with NH 3 . Meanwhile, the strong interactions between the adsorbed molecules and the modified graphenes induce dramatic changes to graphene's electronic properties. The transport behavior of a gas sensor using B-doped graphene shows a sensitivity two orders of magnitude higher than that of pristine graphene. This work reveals that the sensitivity of graphene-based chemical gas sensors could be drastically improved by introducing the appropriate dopant or defect.

Study of different factors affecting the electrical properties of natural gas reservoir rocks based on digital cores

International Nuclear Information System (INIS)

Jiang, Liming; Sun, Jianmeng; Wang, Haitao; Liu, Xuefeng

2011-01-01

The effects of the wettability and solubility of natural gas in formation water on the electrical properties of natural gas reservoir rocks are studied using the finite element method based on digital cores. The results show that the resistivity index of gas-wet reservoir rocks is significantly higher than that of water-wet reservoir rocks in the entire range of water saturation. The difference between them increases with decreasing water saturation. The resistivity index of natural gas reservoir rocks decreases with increasing additional conduction of water film. The solubility of natural gas in formation water has a dramatic effect on the electrical properties of reservoir rocks. The resistivity index of reservoir rocks increases as the solubility of natural gas increases. The effect of the solubility of natural gas on the resistivity index is very obvious under conditions of low water saturation, and it becomes weaker with increasing water saturation. Therefore, the reservoir wettability and the solubility of natural gas in formation water should be considered in defining the saturation exponent

Relation between gas hydrate and physical properties at the Mallik 2L-38 research well in the Mackenzie delta

Science.gov (United States)

Winters, W.J.; Dallimore, S.R.; Collett, T.S.; Jenner, K.A.; Katsube, J.T.; Cranston, R.E.; Wright, J.F.; Nixon, F.M.; Uchida, T.

2000-01-01

As part of an interdisciplinary field program, a 1150-m deep well was drilled in the Canadian Arctic to determine, among other goals, the location, characteristics, and properties of gas hydrate. Numerous physical properties of the host sediment were measured in the laboratory and are presented in relation to the lithology and quantity of in situ gas hydrate. Profiles of measured and derived properties presented from that investigation include: sediment wet bulk density, water content, porosity, grain density, salinity, gas hydrate content (percent occupancy of non-sediment grain void space), grain size, porosity, and post-recovery core temperature. The greatest concentration of gas hydrate is located within sand and gravel deposits between 897 and 922 m. Silty sediment between 926 and 952 m contained substantially less, or no, gas hydrate perhaps because of smaller pore size.

THE INFLUENCE OF GAS-DENSITY AND LIQUID PROPERTIES ON BUBBLE BREAKUP

NARCIS (Netherlands)

WILKINSON, PM; VANSCHAYK, A; SPRONKEN, JPM; VANDIERENDONCK, LL

On the basis of a literature review of bubble breakup experiments, it is demonstrated that both liquid viscosity and surface tension have an influence on bubble stability and, thus, bubble breakup, for small as well as large bubbles. Possible influences of the gas properties on bubble breakup have

The influence of assist gas on magnetic properties of electrotechnical steel sheets cut with laser

International Nuclear Information System (INIS)

Gaworska-Koniarek, Dominika; Szubzda, Bronislaw; Wilczynski, Wieslaw; Drosik, Jerzy; Karas, Kazimierz

2011-01-01

The paper presents the influence of assist gas (air and nitrogen) during laser cutting on magnetization, magnetic permeability and loss characteristics of non-oriented electrical steels. The research was made on an non-oriented M330-50A grade electrical steels by means of single sheet tester. In order to enhance the effect of cutting and the same degradation zone on magnetic properties, strips with different width were achieved. Measurements results indicate that application of air as assist gas has more destructive effect on magnetic properties of electrical steels than nitrogen one.

The influence of assist gas on magnetic properties of electrotechnical steel sheets cut with laser

Science.gov (United States)

Gaworska-Koniarek, Dominika; Szubzda, Bronisław; Wilczyński, Wiesław; Drosik, Jerzy; Karaś, Kazimierz

2011-07-01

The paper presents the influence of assist gas (air and nitrogen) during laser cutting on magnetization, magnetic permeability and loss characteristics of non-oriented electrical steels. The research was made on an non-oriented M330-50A grade electrical steels by means of single sheet tester. In order to enhance the effect of cutting and the same degradation zone on magnetic properties, strips with different width were achieved. Measurements results indicate that application of air as assist gas has more destructive effect on magnetic properties of electrical steels than nitrogen one.

Efficiently mapping structure-property relationships of gas adsorption in porous materials: application to Xe adsorption.

Science.gov (United States)

Kaija, A R; Wilmer, C E

2017-09-08

Designing better porous materials for gas storage or separations applications frequently leverages known structure-property relationships. Reliable structure-property relationships, however, only reveal themselves when adsorption data on many porous materials are aggregated and compared. Gathering enough data experimentally is prohibitively time consuming, and even approaches based on large-scale computer simulations face challenges. Brute force computational screening approaches that do not efficiently sample the space of porous materials may be ineffective when the number of possible materials is too large. Here we describe a general and efficient computational method for mapping structure-property spaces of porous materials that can be useful for adsorption related applications. We describe an algorithm that generates random porous "pseudomaterials", for which we calculate structural characteristics (e.g., surface area, pore size and void fraction) and also gas adsorption properties via molecular simulations. Here we chose to focus on void fraction and Xe adsorption at 1 bar, 5 bar, and 10 bar. The algorithm then identifies pseudomaterials with rare combinations of void fraction and Xe adsorption and mutates them to generate new pseudomaterials, thereby selectively adding data only to those parts of the structure-property map that are the least explored. Use of this method can help guide the design of new porous materials for gas storage and separations applications in the future.

Reinforcement of the Gas Barrier Properties of Polyethylene and Polyamide Through the Nanocomposite Approach: Key Factors and Limitations

Directory of Open Access Journals (Sweden)

Picard E.

2015-02-01

Full Text Available In this study, polyamide 6 (PA6 and polyethylene (PE nanocomposites were prepared from melt blending and a detailed characterization of the nanocomposite morphology and gas barrier properties was performed. The choice of the organoclay was adapted to each polymer matrix. Exfoliated morphology and improved gas transport properties were obtained by melt mixing the polar PA6 matrix and the organoclay, whereas a microcomposite with poor barrier properties was formed from the binary PE/organomodified clay mixture. Different modified polyethylenes were examined as compatibilizers for the polyethylene/organoclay system. The effect of compatibilizer molar mass, polarity and content was investigated on the clay dispersion and on the gas barrier properties. The optimal compatibilizer to clay weight ratio was found to be equal to 4 whatever the compatibilizer. However, a high degree of clay delamination was obtained with the high molar mass compatibilizer whereas highly swollen clay aggregates resulted from the incorporation of the low molar mass interfacial agents. Contrary to the PA based system, the barrier properties of PE nanocomposites were not directly related to the clay dispersion state but resulted also from the matrix/clay interfacial interactions. Oxidized wax was identified as a very promising interfacial agent and a step by step study was performed to optimize the gas transport properties of the systems based on PE, oxidized wax and organoclay. In particular, an interesting combination of oxidized wax and high molar mass maleic anhydride grafted polyethylene allowing dividing the gas permeability by a factor 2 in comparison with neat PE was proposed.

Properties of potential eco-friendly gas replacements for particle detectors in high-energy physics

Science.gov (United States)

Saviano, G.; Ferrini, M.; Benussi, L.; Bianco, S.; Piccolo, D.; Colafranceschi, S.; KjØlbro, J.; Sharma, A.; Yang, D.; Chen, G.; Ban, Y.; Li, Q.; Grassini, S.; Parvis, M.

2018-03-01

Gas detectors for elementary particles require F-based gases for optimal performance. Recent regulations demand the use of environmentally unfriendly F-based gases to be limited or banned. This work studies properties of potential eco-friendly gas replacements by computing the physical and chemical parameters relevant for use as detector media, and suggests candidates to be considered for experimental investigation.

Novel Fe-based nanocrystalline powder cores with excellent magnetic properties produced using gas-atomized powder

Science.gov (United States)

Chang, Liang; Xie, Lei; Liu, Min; Li, Qiang; Dong, Yaqiang; Chang, Chuntao; Wang, Xin-Min; Inoue, Akihisa

2018-04-01

FeSiBPNbCu nanocrystalline powder cores (NPCs) with excellent magnetic properties were fabricated by cold-compaction of the gas-atomized amorphous powder. Upon annealing at the optimum temperature, the NPCs showed excellent magnetic properties, including high initial permeability of 88, high frequency stability up to 1 MHz with a constant value of 85, low core loss of 265 mW/cm3 at 100 kHz for Bm = 0.05 T, and superior DC-bias permeability of 60% at a bias field of 100 Oe. The excellent magnetic properties of the present NPCs could be attributed to the ultrafine α-Fe(Si) phase precipitated in the amorphous matrix and the use of gas-atomized powder coated with a uniform insulation layer.

Gas-permeation properties of poly(ethylene oxide) poly(butylene terephthalate block copolymers

NARCIS (Netherlands)

Metz, S.J.; Mulder, M.H.V.; Wessling, Matthias

2004-01-01

This paper reports the gas-permeation properties of poly(ethylene oxide) (PEO) poly(butylene terephthalate) (PBT) segmented multiblock copolymers. These block copolymers allow a precise structural modification by the amount of PBT and the PEO segment length, enabling a systematic study of the

Charge-transfer properties in the gas electron multiplier

International Nuclear Information System (INIS)

Han, Sanghyo; Kim, Yongkyun; Cho, Hyosung

2004-01-01

The charge transfer properties of a gas electron multiplier (GEM) were systematically investigated over a broad range of electric field configurations. The electron collection efficiency and the charge sharing were found to depend on the external fields, as well as on the GEM voltage. The electron collection efficiency increased with the collection field up to 90%, but was essentially independent of the drift field strength. A double conical GEM has a 10% gain increase with time due to surface charging by avalanche ions whereas this effect was eliminated with the cylindrical GEM. The positive-ion feedback is also estimated. (author)

Structural, optical and gas sensing properties of screen-printed nanostructured Sr-doped SnO2 thick film sensor

International Nuclear Information System (INIS)

Shaikh, F.I.; Chikhale, L.P.; Patil, J.Y.; Rajgure, A.V.; Suryavanshi, S.S.; Mulla, I.S.

2013-01-01

The nanocrystalline materials of strontium doped tin oxide powders were synthesized by conventional co-precipitation method. Synthesized nanophase SnO 2 powders were used to fabricate thick films of pure and Sr-doped SnO 2 using screen-printing technology and investigated for their gas sensing properties towards LPG, ethanol, ammonia and acetone vapor. The crystal structure and phase of the sintered powders were characterized by X-ray diffractometer (XRD) and microstructure by scanning electron microscopy (SEM). All the doped and undoped SnO 2 compositions revealed single phase and solid solution formation. X-ray diffractometer (XRD) results indicated that well crystallized Sr-doped SnO 2 particles of size about 10 nm were obtained at sintering temperature 700℃. The optical properties viz. UV-Vis, FTIR and Raman were used to characterize various physico-chemical properties of samples. The reduction of grain size in metal oxide is a key factor to enhance the gas sensing properties. The doping of Sr in SnO 2 has reduced the grain size and improved the gas response. The results of gas sensing measurements showed that the thick films deposited on alumina substrates using screen-printing technique exhibited high gas response, quick response time and fast recovery time to acetone gas at a working temperature of 250℃. Further, the selectivity of sensor towards acetone with respect to other reducing gases (LPG, ethanol, ammonia) was studied. (author)

Charge Transfer Properties Through Graphene Layers in Gas Detectors

CERN Document Server

Thuiner, P.; Jackman, R.B.; Müller, H.; Nguyen, T.T.; Oliveri, E.; Pfeiffer, D.; Resnati, F.; Ropelewski, L.; Smith, J.A.; van Stenis, M.; Veenhof, R.

2016-01-01

Graphene is a single layer of carbon atoms arranged in a honeycomb lattice with remarkable mechanical, electrical and optical properties. For the first time graphene layers suspended on copper meshes were installed into a gas detector equipped with a gaseous electron multiplier. Measurements of low energy electron and ion transfer through graphene were conducted. In this paper we describe the sample preparation for suspended graphene layers, the testing procedures and we discuss the preliminary results followed by a prospect of further applications.

Microstructure and mechanical properties of aluminum 5083 weldments by gas tungsten arc and gas metal arc welding

Energy Technology Data Exchange (ETDEWEB)

Liu Yao [State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); Wang Wenjing [School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Xie Jijia [State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); Sun Shouguang [School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Wang Liang [College of Metallurgy and Material Engineering, Chongqing University of Science and Technology, Chongqing 401331 (China); Qian Ye; Meng Yuan [State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); Wei Yujie, E-mail: yujie_wei@lnm.imech.ac.cn [State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China)

2012-07-15

Highlights: Black-Right-Pointing-Pointer Welding zones by GTAW and GMAW are softer than the parent material Al5083. Black-Right-Pointing-Pointer GTAW for Al5083 are mechanically more reliable than that welded by GMAW. Black-Right-Pointing-Pointer GTAW welds fail by shear, but GMAW welds show mixed shear and normal failure. - Abstract: The mechanical properties and microstructural features of aluminum 5083 (Al5083) weldments processed by gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) are investigated. Weldments processed by both methods are mechanically softer than the parent material Al5083, and could be potential sites for plastic localization. It is revealed that Al5083 weldments processed by GTAW are mechanical more reliable than those by GMAW. The former bears higher strength, more ductility, and no apparent microstructure defects. Perceivable porosity in weldments by GMAW is found, which could account for the distinct mechanical properties between weldments processed by GTAW and GMAW. It is suggested that caution should be exercised when using GMAW for Al5083 in the high-speed-train industry where such light weight metal is broadly used.

Mechanical properties of steel for construction of gas transfer pipelines and their modification resulting from expanding of gas pipelines during hydraulic pressure testing

International Nuclear Information System (INIS)

Kopczynski, A.

1997-01-01

There are discussed the mechanical properties of the new generation of steel as per European Standard EN 10208.2: 1996. on the basis of the mechanical parameters of steel the normalized graphs of steel tensioning are presented. Analysis of influence of expanding gas pipelines on changes of steel tensioning graphs were performed. Advantages, resulting from expanding of gas pipelines, were shown. (author)

Gas barrier properties of diamond-like carbon films coated on PTFE

International Nuclear Information System (INIS)

Ozeki, K.; Nagashima, I.; Ohgoe, Y.; Hirakuri, K.K.; Mukaibayashi, H.; Masuzawa, T.

2009-01-01

Diamond-like carbon (DLC) films were deposited on polytetrafluoroethylene (PTFE) using radio frequency (RF) plasma-enhanced chemical vapour deposition (PE-CVD). Before the DLC coating, the PTFE substrate was modified with a N 2 plasma pre-treatment to enhance the adhesive strength of the DLC to the substrate. The influences of the N 2 plasma pre-treatment and process pressure on the gas permeation properties of these DLC-coated PTFE samples were investigated. In the Raman spectra, the G peak position shifted to a lower wave number with increasing process pressure. With scanning electron microscopy (SEM), a network of microcracks was observed on the surface of the DLC film without N 2 plasma pre-treatment. The density of these cracks decreased with increasing process pressure. In the film subjected to a N 2 plasma pre-treatment, no cracks were observed at any process pressure. In the gas barrier test, the gas permeation decreased drastically with increasing film thickness and saturated at a thickness of 0.2 μm. The DLC-coated PTFE with the N 2 plasma pre-treatment exhibited a greater reduction in gas permeation than did the samples without pre-treatment. For both sample types, gas permeation decreased with increasing process pressure.

Effect of gas sparging on flux enhancement and phytochemical properties of clarified pineapple juice by microfiltration

KAUST Repository

Laorko, Aporn

2011-08-01

Membrane fouling is a major obstacle in the application of microfiltration. Several techniques have been proposed to enhance the permeate flux during microfiltration. Gas sparging is a hydrodynamic method for improving the performance of the membrane process. In this study, a 0.2 μm hollow fiber microfiltration membrane was used to study the effect of cross flow velocity (CFV) and gas injection factor () on the critical and limiting flux during microfiltration of pineapple juice. In addition, the phytochemical properties of clarified juice were investigated. In the absence of gas sparging, the critical and limiting flux increased as the CFV or shear stress number increased. The use of gas sparging led to a remarkable improvement in both the critical and limiting flux but it was more effective at the lower CFV (1.5 m s-1), compared to those at higher CFV (2.0 and 2.5 m s-1). When the gas injection factor was applied at 0.15, 0.25 and 0.35 with a CFV of 1.5 m s -1, the enhancement of 55.6%, 75.5% and 128.2% was achieved for critical flux, while 65.8%, 69.7% and 95.2% was achieved for limiting flux, respectively. The results also indicated that the use of gas sparging was an effective method to reduce reversible fouling and external irreversible fouling rather than internal irreversible fouling. In addition, the CFV and gas sparging did not affect pH, total soluble solids, colour, total phenolic content and the antioxidant property of the clarified juice. The l-ascorbic acid and total vitamin C were significantly decreased when the higher CFV and high gas injection factor were applied. The results also indicated that the use of gas sparging with low CFV was beneficial for flux enhancement while most of the phytochemical properties of the clarified juice was preserved. © 2011 Elsevier B.V. All rights reserved.

Experimental investigation of the dynamics in a strongly interacting Fermi gas : collective modes and rotational properties

International Nuclear Information System (INIS)

Riedl, S.

2009-01-01

This thesis explores the dynamics in an ultracold strongly interacting Fermi gas. Therefore we perform measurements on collective excitation modes and rotational properties of the gas. The strongly interacting gas is realized using an optically trapped Fermi gas of 6 Li atoms, where the interactions can be tuned using a broad Feshbach resonance. Our measurements allow to test the equation of state of the gas, study the transition from hydrodynamic to collisionless behavior, reveal almost ideal hydrodynamic behavior in the nonsuperfluid phase, investigate the lifetime of angular momentum, and show superfluidity through the quenching of the moment of inertia. (author)

Physical properties of CO-dark molecular gas with C+ and OH observations

Science.gov (United States)

Tang, Ningyu; Li, Di; Heiles, Carl E.; ISM Group in National Astronomical Observatories, CAS

2017-01-01

The lifecycle of interstellar medium (ISM) is critical for understanding galaxy evolution. The transition between atomic neutral medium and dense molecular gas, however, cannot be traced adequately by either HI or CO emission. Results from dust observations of Planck all-sky mission and gamma-ray observations of Energetic Gamma Ray Experiment Telescope (EGRET) have revealed the existence of “CO dark molecular gas” (DMG) - molecular gas without CO emission. The physical conditions of DMG including density, temperature, and molecular composition are basis of understanding the ISM evolution. We analyzed physical properties of DMG with HI-self absorption and C+ fine line emission at 158 um toward the lines of sight of Galactic Observations of Terahertz C+ (GOTC+). DMG clouds have a median excitation temperature of 56 K and median volume density of 230 cm2, showing intermediate physical properties between atomic and molecular gas. Sixteen DMG clouds with high visual extinction (AV>=2.7 mag) were found. CO abundance compared to H2 in these clouds is two orders magnitude smaller than the cannonical value in the Milky Way and cannot be explained by the chemical evolutionary model. They may be formed through the agglomeration of pre-existing molecular gas in the Milky Way. We have finished a follow up survey of OH 18 cm lines toward 51 sightlines of GOTC+ including sightlines with DMG clouds through Arecibo telescope. DMG may result in the absence of correlation between CO and OH column density. A possible correlation was found between C+ and OH column density in tracing DMG.

Adsorption and gas-chromatographic properties of tungsten selenide

International Nuclear Information System (INIS)

Gavrilova, T.B.; Kiselev, A.V.; Roshchina, T.M.

1988-01-01

Method of gas chromatography was used to investigate the surface properties of a series of tungsten selenide WSe 2 samples as well as to determine the role of geometrical and electronic structure of adsorbate molecules and their orientation with respect to the surface during adsorption on WSe 2 . Thermodynamic characteristics of hydrocarbon C 6 -C 10 adsorption at surface occupation close to the zero one were determined. Correlation of the values of thermodynamic characteristics of saturated and aromatic hydrocarbon adsorption enabled to refer WSe 2 to nonspecific adsorbents. It is noted that the main role during hydrocarbon adsorption on WSe 2 is played by nonpolar basic facets, occupied by selenium atoms

The Effects of Nitrogen Gas on Microstructural and Mechanical Properties of TIG Welded S32205 Duplex Stainless Steel

Directory of Open Access Journals (Sweden)

Aziz Barış Başyiğit

2018-04-01

Full Text Available Duplex stainless steels are gaining greater interest due to their increasing amounts of application fields. Accordingly, there is a need for awareness of problems associated with improper microstructural distributions such as δ-ferrite (delta-ferrite, austenite and other important intermetallic phases that may form in these steel weldments. Since δ-ferrite versus austenite ratio profoundly influences corrosion and mechanical properties, optimum δ-ferrite ratios must be kept approximately within 35–65 vol % and balance austenite to maintain satisfactory corrosion and mechanical properties on welding of these steels. Cooling rates of welds and alloying elements in base metal are the major factors that determine the final microstructure of these steels. In this work, 3 mm thickness of 2205 duplex stainless-steel plates were TIG (Tungsten Inert Gas welded with various amounts of nitrogen gas added to argon shielding gas. Specimens were joined within the same welding parameters and cooling conditions. As nitrogen is a potential austenite stabilizer and an interstitial solid solution hardener, the effects of nitrogen on mechanical properties such as hardness profiles, grain sizes and microstructural modifications are investigated thoroughly by changing the welding shielding gas compositions. Increasing the nitrogen content in argon shielding gas also increases the amount of austenitic phase while δ-ferrite ratios decreases. Nitrogen spherodized the grains of austenitic structure much more than observed in δ-ferrite. The strength values of specimens that welded with the addition of nitrogen gas into the argon shielding gas are increased more in both austenitic and delta-ferritic structure as compared to specimens that welded with plain argon shielding gas. The addition of 1 vol % of nitrogen gas into argon shielding gas provided the optimum phase balance of austenite and δ-ferrite in S32205 duplex stainless-steel TIG-welded specimens.

A model for the impact of the nanostructure size on its gas sensing properties

DEFF Research Database (Denmark)

Alenezi, Mohammad R.; Alzanki, T.H.; Almeshal, A.M.

2015-01-01

The size of a metal oxide nanostructure plays a key role in its performance as a gas sensor. ZnO nanostructures with different morphologies including nanowires at different diameters and nanodisks at different thicknesses were synthesized hydrothermally. Gas sensors based on individual...... of the surface to volume ratio as well as the depletion region of the nanostructure. This work can be simply generalized for other metal oxides to enhance their performance as gas sensors....... nanostructures with different sizes were fabricated and their sensing properties were compared and investigated. Nanowires with smaller diameter size and higher surface to volume ratio showed enhanced gas sensing performance. Also, as the nanodisk thickness gets closer to the thickness of the ZnO depletion layer...

Effects of N2 mixed gas atomization on electrochemical properties of Mm(Ni,Co,Mn,Al)5.0 alloy powder

International Nuclear Information System (INIS)

Yanagimoto, K.; Sunada, S.; Majima, K.; Sawada, T.

2004-01-01

N 2 gas, N 2 -Ar mixed gas and Ar gas atomization followed by acid surface treatment was applied to improve electrochemical properties of AB 5 type hydrogen storage alloy powder. The shape of Ar atomized powder was spherical and it changed to be irregular with increasing N 2 content of mixed gas. Irrespective of gas kinds, electrodes of atomized powder showed the same discharge capacity as cast-pulverized powder under auxiliary electrical conductivity by nickel powder addition. Without nickel powder, however, N 2 atomized powder showed the best electrochemical properties as well as gas activation behavior. By the combination process of N 2 gas atomization and acid surface treatment, it was considered that irregular shape of N 2 atomized powder promoted electrical conductivity of electrodes and catalytic nickel concentrated surface layer was formed to increase the hydrogen storage rapidity

Tuning of Preparational Factors Affecting the Morphological Structure and Gas Separation Property of Asymmetric Polysulfone Membranes

Science.gov (United States)

Yuenyao, C.; Ruangdit, S.; Chittrakarn, T.

2017-09-01

The aim of this work was to study the effect of preparational factors such as solvent type, evaporation time (ET) and non-solvent additive, on the morphological structure, physical and gas separation properties of the prepared membrane samples by tuning of these parameters. Flat sheet asymmetric polysulfone (PSF) membranes were prepared by the dry/wet phase inversion process combined with the double coagulation bath method. The alteration of the prepared membranes were analyzed through scientific techniques such as Scanning Electron Microscope (SEM) and Dynamic Mechanical Thermal Analysis (DMTA). Furthermore, gas separation performance of membrane samples was measured in term of gas permeation and ideal selectivity of CO2/CH4. Experimental results showed that the change of preparational factors affected to the gas permeation of asymmetric PSF membranes. For example, the selective layer thickness increased with increasing of ET. This lead to increase significantly of ideal selectivity of CO2/CH4. The CO2/CH4 ideal selectivity was also increased with increase of ethanol (non-solvent additive) concentration in casting solution. In summary, the tuning of preparational factors affected to morphological structure, physical and gas separation properties of PSF membranes.

Evaluation of gas-sensing properties of ZnO nanostructures electrochemically doped with Au nanophases

Directory of Open Access Journals (Sweden)

Elena Dilonardo

2016-01-01

Full Text Available A one-step electrochemical method based on sacrificial anode electrolysis (SAE was used to deposit stabilized gold nanoparticles (Au NPs directly on the surface of nanostructured ZnO powders, previously synthesized through a sol–gel process. The effect of thermal annealing temperatures (300 and 550 °C on chemical, morphological, and structural properties of pristine and Au-doped ZnO nancomposites (Au@ZnO was investigated. Transmission and scanning electron microscopy (TEM and SEM, as well as X-ray photoelectron spectroscopy (XPS, revealed the successful deposition of nanoscale gold on the surface of spherical and rod-like ZnO nanostructures, obtained after annealing at 300 and 550 °C, respectively. The pristine ZnO and Au@ZnO nanocomposites are proposed as active layer in chemiresistive gas sensors for low-cost processing. Gas-sensing measurements towards NO2 were collected at 300 °C, evaluating not only the Au-doping effect, but also the influence of the different ZnO nanostructures on the gas-sensing properties.

Synthesis and Gas Transport Properties of Hyperbranched Polyimide–Silica Hybrid/Composite Membranes

Directory of Open Access Journals (Sweden)

Masako Miki

2013-12-01

Full Text Available Hyperbranched polyimide–silica hybrids (HBPI–silica HBDs and hyperbranched polyimide–silica composites (HBPI–silica CPTs were prepared, and their general and gas transport properties were investigated to clarify the effect of silica sources and preparation methods. HBPI–silica HBDs and HBPI–silica CPTs were synthesized by two-step polymerization of A2 + B3 monomer system via polyamic acid as precursor, followed by hybridizing or blending silica sources. Silica components were incorporated by the sol-gel reaction with tetramethoxysilane (TMOS or the addition of colloidal silica. In HBPI-silica HBDs, the aggregation of silica components is controlled because of the high affinity of HBPI and silica caused by the formation of covalent bonds between HBPI and silica. Consequently, HBPI-silica HBDs had good film formability, transparency, and mechanical properties compared with HBPI-silica CPTs. HBPI-silica HBD and CPT membranes prepared via the sol-gel reaction with TMOS showed specific gas permeabilities and permselectivities for CO2/CH4 separation, that is, both CO2 permeability and CO2/CH4 selectivity increased with increasing silica content. This result suggests that gas transport can occur through a molecular sieving effect of the porous silica network derived from the sol-gel reaction and/or through the narrow interfacial region between the silica networks and the organic matrix.

Electronic properties and gas adsorption behaviour of pristine, silicon-, and boron-doped (8, 0) single-walled carbon nanotube: A first principles study.

Science.gov (United States)

Azam, Mohd Asyadi; Alias, Farizul Muiz; Tack, Liew Weng; Seman, Raja Noor Amalina Raja; Taib, Mohamad Fariz Mohamad

2017-08-01

Carbon nanotubes (CNTs) have received enormous attention due to their fascinating properties to be used in various applications including electronics, sensing, energy storage and conversion. The first principles calculations within density functional theory (DFT) have been carried out in order to investigate the structural, electronic and optical properties of un-doped and doped CNT nanostructures. O 2 , CO 2 , and CH 3 OH have been chosen as gas molecules to study the adsorption properties based on zigzag (8,0) SWCNTs. The results demonstrate that the adsorption of O 2 , CO 2, and CH 3 OH gas molecules on pristine, Si-doped and B-doped SWCNTs are either physisorption or chemisorption. Moreover, the electronic properties indicating SWCNT shows significant improvement toward gas adsorption which provides the impact of selecting the best gas sensor materials towards detecting gas molecule. Therefore, these pristine, Si-, and B-doped SWCNTs can be considered to be very good potential candidates for sensing application. Copyright © 2017 Elsevier Inc. All rights reserved.

Toward Measuring Galactic Dense Molecular Gas Properties and 3D Distribution with Hi-GAL

Science.gov (United States)

Zetterlund, Erika; Glenn, Jason; Maloney, Phil

2016-01-01

The Herschel Space Observatory's submillimeter dust continuum survey Hi-GAL provides a powerful new dataset for characterizing the structure of the dense interstellar medium of the Milky Way. Hi-GAL observed a 2° wide strip covering the entire 360° of the Galactic plane in broad bands centered at 70, 160, 250, 350, and 500 μm, with angular resolution ranging from 10 to 40 arcseconds. We are adapting a molecular cloud clump-finding algorithm and a distance probability density function distance-determination method developed for the Bolocam Galactic Plane Survey (BGPS) to the Hi-GAL data. Using these methods we expect to generate a database of 105 cloud clumps, derive distance information for roughly half the clumps, and derive precise distances for approximately 20% of them. With five-color photometry and distances, we will measure the cloud clump properties, such as luminosities, physical sizes, and masses, and construct a three-dimensional map of the Milky Way's dense molecular gas distribution.The cloud clump properties and the dense gas distribution will provide critical ground truths for comparison to theoretical models of molecular cloud structure formation and galaxy evolution models that seek to emulate spiral galaxies. For example, such models cannot resolve star formation and use prescriptive recipes, such as converting a fixed fraction of interstellar gas to stars at a specified interstellar medium density threshold. The models should be compared to observed dense molecular gas properties and galactic distributions.As a pilot survey to refine the clump-finding and distance measurement algorithms developed for BGPS, we have identified molecular cloud clumps in six 2° × 2° patches of the Galactic plane, including one in the inner Galaxy along the line of sight through the Molecular Ring and the termination of the Galactic bar and one toward the outer Galaxy. Distances have been derived for the inner Galaxy clumps and compared to Bolocam Galactic Plane

A novel snowflake-like SnO2 hierarchical architecture with superior gas sensing properties

Science.gov (United States)

Li, Yanqiong

2018-02-01

Snowflake-like SnO2 hierarchical architecture has been synthesized via a facile hydrothermal method and followed by calcination. The SnO2 hierarchical structures are assembled with thin nanoflakes blocks, which look like snowflake shape. A possible mechanism for the formation of the SnO2 hierarchical structures is speculated. Moreover, gas sensing tests show that the sensor based on snowflake-like SnO2 architectures exhibited excellent gas sensing properties. The enhancement may be attributed to its unique structures, in which the porous feature on the snowflake surface could further increase the active surface area of the materials and provide facile pathways for the target gas.

The impact of oil and natural gas facilities on rural residential property values

International Nuclear Information System (INIS)

Boxall, P.C.

2005-01-01

This PowerPoint presentation examined challenges in the economic valuation of environmental changes within the context of formal real estate markets. It was proposed that some values that are expressed in markets can be affected by environmental changes and should be used in resource development land assessments. Details of indirect market valuation and revealed preference methods were reviewed. An outline of hedonic pricing was presented. It was noted that hedonic pricing can be used with other market values and prices such as tourism, art prices and hotel prices, where multivariate regression techniques are used and regression coefficients reveal information on the implicit prices of certain characteristics. Property value examples in the environmental economics literature were reviewed. A case study using data from eco-terrorism costs was presented. Issues concerning sour gas facilities were discussed with reference to public anxiety over hydrogen sulfide (H 2 S) toxicity and flares. Concerns over health risks and negative amenity impacts were discussed. The impacts of sour gas facilities on property values of residential acreages in and around Calgary were considered, and a map of the study area was presented. An outline of emergency plan response zones was provided. Price effects of industry facilities were presented, including marginal and cumulative impacts on price. It was concluded that oil and gas activities have significant impacts on rural residential property prices, but that industry members currently report that there is little to no effect. It was suggested that the research presented in this paper could be used to assess levels of compensation. tabs., figs

Comparison of Physical Properties of Marine and Arctic Gas-Hydrate-Bearing Deposits

Science.gov (United States)

Winters, W. J.; Walker, M.; Collett, T. S.; Bryant, S. L.; Novosel, I.; Wilcox-Cline, R.; Bing, J.; Gomes, M. L.

2009-12-01

Gas hydrate (GH) occurs in both marine settings and in arctic environments within a wide variety of sediment types. Grain-size analyses from both environments indicate that intrinsic host-sediment properties have a strong influence on gas-hydrate distribution and morphologic characteristics. Depending on the amount formed or dissociated, gas hydrate can significantly change in situ sediment acoustic, mechanical, and hydraulic properties. The U.S. Geological Survey, in cooperation with the U.S. Dept. of Energy, BP Expl.-Alaska, Nat. GH Prog. of India, Canadian Geological Survey, Int. Ocean Drilling Program, Japan Oil Gas and Metals Nat. Corp., Japan Pet. Expl. Co., Int. Marine Past Global Changes Study (IMAGES) program, and Paleoceanography of the Atlantic and Geochemistry (PAGE) program, determined physical properties from marine and arctic sediments and their relation to the presence of GH. At two arctic sites, the Mount Elbert well on the Alaskan North Slope and the Mallik wells on the Mackenzie Delta, NWT, >10-m thick gas-hydrate-bearing (GHB) sandy deposits are capped by finer-grained sediments that may reduce gas migration. In the Mount Elbert well, average median grain sizes (MGS) for the two thickest GHB deposits are 65 and 60 µm. Finer-grained (average MGS of 9 and 28 µm) sediments have plug permeabilities that are 300 and 14 times smaller than underlying GHB sediment. Average MGS of GHB sediment from the Mallik 2L well is ~ 111 µm, compared to overlying sediment with an average MGS of ~ 32 µm. Gas hydrate morphology in the Gulf of Mexico (GOM) and offshore India is substantially more complex than in the arctic, and is related to pervasive, although not exclusive, finer-grained deposits. Massive, several-cm thick, GH layers were recovered in piston cores in the northern GOM, in sediment with little visible lithologic variability (average MGS ~ 0.8 µm). In wells off the east coast of India, GH was present in sand-rich, fractured clay, and reservoirs

Variations between Dust and Gas in the Diffuse Interstellar Medium. III. Changes in Dust Properties

Science.gov (United States)

Reach, William T.; Bernard, Jean-Philippe; Jarrett, Thomas H.; Heiles, Carl

2017-12-01

We study infrared emission of 17 isolated, diffuse clouds with masses of order {10}2 {M}ȯ to test the hypothesis that grain property variations cause the apparently low gas-to-dust ratios that have been measured in those clouds. Maps of the clouds were constructed from Wide-field Infrared Survey Explorer (WISE) data and directly compared with the maps of dust optical depth from Planck. The mid-infrared emission per unit dust optical depth has a significant trend toward lower values at higher optical depths. The trend can be quantitatively explained by the extinction of starlight within the clouds. The relative amounts of polycyclic aromatic hydrocarbon and very small grains traced by WISE, compared with large grains tracked by Planck, are consistent with being constant. The temperature of the large grains significantly decreases for clouds with larger dust optical depth; this trend is partially due to dust property variations, but is primarily due to extinction of starlight. We updated the prediction for molecular hydrogen column density, taking into account variations in dust properties, and find it can explain the observed dust optical depth per unit gas column density. Thus, the low gas-to-dust ratios in the clouds are most likely due to “dark gas” that is molecular hydrogen.

The practical use of resistance modelling to interpret the gas separation properties of hollow fiber membranes

International Nuclear Information System (INIS)

Ahmad Fauzi Ismail; Shilton, S.J.

2000-01-01

A simple resistance modelling methodology is presented for gas transport through asymmetric polymeric membranes. The methodology allows fine structural properties such as active layer thickness and surface porosity, to be determined from experimental gas permeation data. This paper, which could be regarded as a practical guide, shows that resistance modeling, if accompanied by realistic working assumptions, need not be difficult and can provide a valuable insight into the relationships between the membrane fabrication conditions and performance of gas separation membranes. (Author)

Atomistic simulations of thermodynamic properties of Xe gas bubbles in U10Mo fuels

Energy Technology Data Exchange (ETDEWEB)

Hu, Shenyang, E-mail: shenyang.hu@pnnl.gov; Setyawan, Wahyu; Joshi, Vineet V.; Lavender, Curt A.

2017-07-15

Xe gas bubble superlattice formation is observed in irradiated uranium–10 wt% molybdenum (U10Mo) fuels. However, the thermodynamic properties of the bubbles (the relationship among bubble size, equilibrium Xe concentration, and bubble pressure) and the mechanisms of bubble superlattice formation are not well known. In this work, the molecular dynamics (MD) method is used to study these properties and mechanisms. The results provide important inputs for quantitative mesoscale models of gas bubble evolution and fuel performance. In the MD simulations, the embedded-atom method (EAM) potential of U10Mo-Xe [1] is employed. Initial gas bubbles with a low Xe concentration (underpressured) are generated in a body-centered cubic (bcc) U10Mo single crystal. Then Xe atoms are sequentially added into the bubbles one by one, and the evolution of pressure and dislocation emission around the bubbles is analyzed. The relationship between pressure, equilibrium Xe concentration, and radius of the bubbles is established. It was found that an overpressured gas bubble emits partial dislocations with a Burgers vector along the <111> direction and a slip plane of (11-2). Meanwhile, dislocation loop punch out was not observed. The overpressured bubble also induces an anisotropic stress field. A tensile stress was found along <110> directions around the bubble, favoring the nucleation and formation of a face-centered cubic bubble superlattice in bcc U10Mo fuels.

Atomistic simulations of thermodynamic properties of Xe gas bubbles in U10Mo fuels

Science.gov (United States)

Hu, Shenyang; Setyawan, Wahyu; Joshi, Vineet V.; Lavender, Curt A.

2017-07-01

Xe gas bubble superlattice formation is observed in irradiated uranium-10 wt% molybdenum (U10Mo) fuels. However, the thermodynamic properties of the bubbles (the relationship among bubble size, equilibrium Xe concentration, and bubble pressure) and the mechanisms of bubble superlattice formation are not well known. In this work, the molecular dynamics (MD) method is used to study these properties and mechanisms. The results provide important inputs for quantitative mesoscale models of gas bubble evolution and fuel performance. In the MD simulations, the embedded-atom method (EAM) potential of U10Mo-Xe [1] is employed. Initial gas bubbles with a low Xe concentration (underpressured) are generated in a body-centered cubic (bcc) U10Mo single crystal. Then Xe atoms are sequentially added into the bubbles one by one, and the evolution of pressure and dislocation emission around the bubbles is analyzed. The relationship between pressure, equilibrium Xe concentration, and radius of the bubbles is established. It was found that an overpressured gas bubble emits partial dislocations with a Burgers vector along the direction and a slip plane of (11-2). Meanwhile, dislocation loop punch out was not observed. The overpressured bubble also induces an anisotropic stress field. A tensile stress was found along directions around the bubble, favoring the nucleation and formation of a face-centered cubic bubble superlattice in bcc U10Mo fuels.

Study of functional properties of gas-sensitive cobalt-containing polyacrylonitrile films

Science.gov (United States)

Semenistaya, T. V.; Voronova, A. A.

2017-11-01

The design of the sensor materials with challenging gas-sensitivity can be solved by materials selection and their compatibility with the manufacturing technologies that allows to operate the process of formation of nanocomposite structure and to receive the required material. The polyacrylonitrile (PAN) as the conducting polymer with a highly π-conjugated polymeric chain due to flexibility for tailoring the structure of the final products by the pyrolysis method under the influence of incoherent IR-radiation is chosen. The aim of the work was to study the peculiarities of formation procedure of cobalt-containing PAN films. The gas-sensing Co-containing PAN films have been fabricated. The different temperature and time have been used to form the films. Depending on intensity and exposure time of IR-radiation the thermostructured PAN films with resistance values of · 108 Ω to 1010 Ω have been fabricated. It is shown that the heat-treated PAN is the p-type semiconductor. Irrespective of the level of the modifying additive in film-forming solution and the time-temperature modes little change of film resistance has been found. It has been found that the Co-containing PAN films are gas-sensing films and have high selectivity to Cl2 and NO2. A stationary state gas distribution method was used for testing gas-sensing properties. Obtained the Co-containing PAN films are perspective for low-temperature applications as Cl2 and NO2 sensors.

Highly Enhanced Gas Adsorption Properties in Vertically Aligned MoS2 Layers.

Science.gov (United States)

Cho, Soo-Yeon; Kim, Seon Joon; Lee, Youhan; Kim, Jong-Seon; Jung, Woo-Bin; Yoo, Hae-Wook; Kim, Jihan; Jung, Hee-Tae

2015-09-22

In this work, we demonstrate that gas adsorption is significantly higher in edge sites of vertically aligned MoS2 compared to that of the conventional basal plane exposed MoS2 films. To compare the effect of the alignment of MoS2 on the gas adsorption properties, we synthesized three distinct MoS2 films with different alignment directions ((1) horizontally aligned MoS2 (basal plane exposed), (2) mixture of horizontally aligned MoS2 and vertically aligned layers (basal and edge exposed), and (3) vertically aligned MoS2 (edge exposed)) by using rapid sulfurization method of CVD process. Vertically aligned MoS2 film shows about 5-fold enhanced sensitivity to NO2 gas molecules compared to horizontally aligned MoS2 film. Vertically aligned MoS2 has superior resistance variation compared to horizontally aligned MoS2 even with same surface area exposed to identical concentration of gas molecules. We found that electrical response to target gas molecules correlates directly with the density of the exposed edge sites of MoS2 due to high adsorption of gas molecules onto edge sites of vertically aligned MoS2. Density functional theory (DFT) calculations corroborate the experimental results as stronger NO2 binding energies are computed for multiple configurations near the edge sites of MoS2, which verifies that electrical response to target gas molecules (NO2) correlates directly with the density of the exposed edge sites of MoS2 due to high adsorption of gas molecules onto edge sites of vertically aligned MoS2. We believe that this observation extends to other 2D TMD materials as well as MoS2 and can be applied to significantly enhance the gas sensor performance in these materials.

Synthesis, characterization and liquefied petroleum gas (LPG) sensing properties of WO3 nano-particles

Science.gov (United States)

Singh, Subhash; Majumder, S. B.

2018-05-01

Metal oxide sensors, such as ZnO, SnO2, and WO3 etc. have been utilized for several decades for low-costd etection of combustible and toxic gases. In the present work tungsten oxide (WO3) nanoparticles have been prepared by using an economic wet chemical synthesis route. To understand the phase formation behavior of the synthesized powders, X-ray diffraction analysis has been performed. The microstructure evolution of the synthesized powders was characterized by field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The calcined phase pure WO3 nanoparticles are investigated in terms of LPG gas sensing properties. The gas sensing measurements has been done in two different mode of operation (namely static and dynamic measurements). The degree of oxygen deficiency in the WO3 sensor also affected the sensor properties and the optimum oxygen content of WO3 was necessary to get high sensitivity for LPG. The WO3 sensor shows the excellent sensor properties for LPG at the operating temperature of 250°C.

Simonkolleite nano-platelets: Synthesis and temperature effect on hydrogen gas sensing properties

Energy Technology Data Exchange (ETDEWEB)

Sithole, J. [NANOAFNET, MRD-iThemba LABS, National Research Foundation,1 Old Faure road, Somerset West 7129 (South Africa); Dept. of Physics, University of Western Cape, Private Bag X 17, Belleville (South Africa); Ngom, B.D., E-mail: bdngom@tlabs.ac.za [NANOAFNET, MRD-iThemba LABS, National Research Foundation,1 Old Faure road, Somerset West 7129 (South Africa) and African Laser Centre, CSIR campus, P.O. Box 395, Pretoria (South Africa); Laboratoire de Photonique et de Nano-Fabrication, Groupe de Physique du Solide et Sciences des Materiaux, Departement de Physique Facultes des Sciences et Technique Universite Cheikh Anta Diop de Dakar, Dakar (Senegal); Khamlich, S. [NANOAFNET, MRD-iThemba LABS, National Research Foundation,1 Old Faure road, Somerset West 7129 (South Africa); African Laser Centre, CSIR campus, P.O. Box 395, Pretoria (South Africa); Manikanadan, E. [National Centre for Nano-Structured Materials (NCNSM), Council for Scientific and Industrial Research, Pretoria (South Africa); Manyala, N. [Department of Physics, SARCHI Chair in Carbon Technology and Materials, Institute of Applied Materials, University of Pretoria, Pretoria 0028 (South Africa); Saboungi, M.L. [Centre de Recherche sur la Matiere Divisee, CNRS-Orleans, Orleans (France); Knoessen, D. [Dept. of Physics, University of Western Cape, Private Bag X 17, Belleville (South Africa); Nemutudi, R.; Maaza, M. [NANOAFNET, MRD-iThemba LABS, National Research Foundation,1 Old Faure road, Somerset West 7129 (South Africa)

2012-08-01

In this work, the new refined mineral platelets-like morphology of simonkolleite based particles described by Shemetzer et al. (1985) were synthesized in zinc nitrate aqueous solution by a moderate solution process. The morphological and structural properties of the platelets-like Zn{sub 5}(OH){sub 8}Cl{sub 2}{center_dot}H{sub 2}O were characterized by scanning electron microscope energy dispersed X-ray spectroscopy, transmission electron microscope, powder X-ray diffraction and selected area electron diffraction as well as attenuated total reflection infrared spectroscopy. The morphology as well as the size in both basal and transversal directions of the simonkolleite Zn{sub 5}(OH){sub 8}Cl{sub 2}{center_dot}H{sub 2}O nano/micro crystals was found to be significantly depending on the specific concentration of 0.1 M of Zn{sup 2+}/Cl{sup -} ions in the precursor solution. The simonkolleite Zn{sub 5}(OH){sub 8}Cl{sub 2}{center_dot}H{sub 2}O nano-platelets revealed a significant and singular H{sub 2} gas sensing characteristics. The operating temperature was found to play a key role on the sensing properties of simonkolleite. The effect of temperature on the simonkolleite sample as a hydrogen gas sensor was studied by recording the change in resistivity of the film in presence of the test gas. The results on the sensitivity and response time as per comparison to earlier reported ZnO based sensors are indicated and discussed.

Gas barrier properties of hydrogenated amorphous carbon films coated on polyethylene terephthalate by plasma polymerization in argon/n-hexane gas mixture

Energy Technology Data Exchange (ETDEWEB)

Polonskyi, Oleksandr; Kylián, Ondřej, E-mail: ondrej.kylian@gmail.com; Petr, Martin; Choukourov, Andrei; Hanuš, Jan; Biederman, Hynek

2013-07-01

Hydrogenated amorphous carbon thin films were deposited by RF plasma polymerization in argon/n-hexane gas mixture on polyethylene terephthalate (PET) foils. It was found that such deposited films may significantly improve the barrier properties of PET. It was demonstrated that the principal parameter that influences barrier properties of such deposited films towards oxygen and water vapor is the density of the coatings. Moreover, it was shown that for achieving good barrier properties it is advantageous to deposit coatings with very low thickness. According to the presented results, optimal thickness of the coating should not be higher than several tens of nm. - Highlights: • a-C:H films were prepared by plasma polymerization in Ar/n-hexane atmosphere. • Barrier properties of coatings are dependent on their density and thickness. • Highest barrier properties were observed for films with thickness 15 nm.

Investigation of surface properties of physico-chemically modified natural fibres using inverse gas chromatography

CSIR Research Space (South Africa)

Cordeiro, N

2011-01-01

Full Text Available Inverse gas chromatography (IGC) is a suitable method to determine surface energy of natural fibres when compared to wetting techniques. In the present study, the surface properties of raw and modified lignocellulosic fibres have been investigated...

The studies on gas adsorption properties of MIL-53 series MOFs materials

Directory of Open Access Journals (Sweden)

Yuqiu Jiao

2017-08-01

Full Text Available Molecular dynamics (MD, grand canonical Monte Carlo (GCMC and ideal adsorbed solution theory (IAST were used to study the structures and gas adsorption properties of MIL-53(M[M=Cr, Fe, Sc, Al] metal organic framework (MOF materials. The results show that the volumes of those MOF materials increase significantly at high temperature. By analyzing the adsorption isotherms, we found that the temperature had a paramount effect on the gas adsorption behaviors of these MOF materials. For MIL-53(Cr, the orders of the quantities of adsorbed gases were CH4>N2>CO2>H2S, CH4>H2S>CO2>N2 and CH4>CO2>H2S>N2 at 100K, 293K and 623K, respectively. We also calculated the adsorption of several combinations of two gases by MIL-53(Cr at 293K, the results indicate that the material had selective adsorption of CH4 over CO2, H2S and N2. Our calculations provide microscopic insights into the gas adsorption performances of these MOFs and may further guide the practice of gas separation.

The studies on gas adsorption properties of MIL-53 series MOFs materials

Science.gov (United States)

Jiao, Yuqiu; Li, Zhenyu; Ma, Yue; Zhou, Guanggang; Wang, Shuangxi; Lu, Guiwu

2017-08-01

Molecular dynamics (MD), grand canonical Monte Carlo (GCMC) and ideal adsorbed solution theory (IAST) were used to study the structures and gas adsorption properties of MIL-53(M)[M=Cr, Fe, Sc, Al] metal organic framework (MOF) materials. The results show that the volumes of those MOF materials increase significantly at high temperature. By analyzing the adsorption isotherms, we found that the temperature had a paramount effect on the gas adsorption behaviors of these MOF materials. For MIL-53(Cr), the orders of the quantities of adsorbed gases were CH4>N2>CO2>H2S, CH4>H2S>CO2>N2 and CH4>CO2>H2S>N2 at 100K, 293K and 623K, respectively. We also calculated the adsorption of several combinations of two gases by MIL-53(Cr) at 293K, the results indicate that the material had selective adsorption of CH4 over CO2, H2S and N2. Our calculations provide microscopic insights into the gas adsorption performances of these MOFs and may further guide the practice of gas separation.

Detailed evaluation of gas hydrate reservoir properties using JAPEX/JNOC/GSC Mallik 2L-38 gas hydrate research well downhole well-log displays

Science.gov (United States)

Collett, T.S.

1999-01-01

The JAPEX/JNOC/GSC Mallik 2L-38 gas hydrate research well project was designed to investigate the occurrence of in situ natural gas hydrate in the Mallik area of the Mackenzie Delta of Canada. Because gas hydrate is unstable at surface pressure and temperature conditions, a major emphasis was placed on the downhole logging program to determine the in situ physical properties of the gas-hydrate-bearing sediments. Downhole logging tool strings deployed in the Mallik 2L-38 well included the Schlumberger Platform Express with a high resolution laterolog, Array Induction Imager Tool, Dipole Shear Sonic Imager, and a Fullbore Formation Microlmager. The downhole log data obtained from the log- and core-inferred gas-hydrate-bearing sedimentary interval (897.25-1109.5 m log depth) in the Mallik 2L-38 well is depicted in a series of well displays. Also shown are numerous reservoir parameters, including gas hydrate saturation and sediment porosity log traces, calculated from available downhole well-log and core data. The gas hydrate accumulation delineated by the Mallik 2L-38 well has been determined to contain as much as 4.15109 m3 of gas in the 1 km2 area surrounding the drill site.

Effect of Shielding Gas on the Properties of AW 5083 Aluminum Alloy Laser Weld Joints

Science.gov (United States)

Vyskoč, Maroš; Sahul, Miroslav; Sahul, Martin

2018-04-01

The paper deals with the evaluation of the shielding gas influence on the properties of AW 5083 aluminum alloy weld joints produced with disk laser. Butt weld joints were produced under different shielding gas types, namely Ar, He, Ar + 5 vol.% He, Ar + 30 vol.% He and without shielding weld pool. Light and electron microscopy, computed tomography, microhardness measurements and tensile testing were used for evaluation of weld joint properties. He-shielded weld joints were the narrowest ones. On the other hand, Ar-shielded weld joints exhibited largest weld width. The choice of shielding gas had significant influence on the porosity level of welds. The lowest porosity was observed in weld joint produced in Ar with the addition of 5 vol.% He shielding atmosphere (only 0.03%), while the highest level of porosity was detected in weld joint produced in pure He (0.24%). Except unshielded aluminum alloy weld joint, the lowest tensile strength was recorded in He-shielded weld joints. On the contrary, the highest average microhardness was measured in He-shielded weld joints.

Laser, tungsten inert gas, and metal active gas welding of DP780 steel: Comparison of hardness, tensile properties and fatigue resistance

International Nuclear Information System (INIS)

Lee, Jeong Hun; Park, Sung Hyuk; Kwon, Hyuk Sun; Kim, Gyo Sung; Lee, Chong Soo

2014-01-01

Highlights: • We report the mechanical properties of DP780 steel welded by three methods. • The size of the welded zone increases with heat input (MAG > TIG > laser). • The hardness of the welded zone increases with cooling rate (laser > TIG > MAG). • Tensile and fatigue properties are strongly dependent on welding method. • Crack initiation sites depend on the microstructural features of the welded zone. - Abstract: The microstructural characteristics, tensile properties and low-cycle fatigue properties of a dual-phase steel (DP780) were investigated following its joining by three methods: laser welding, tungsten inert gas (TIG) welding, and metal active gas (MAG) welding. Through this, it was found that the size of the welded zone increases with greater heat input (MAG > TIG > laser), whereas the hardness of the weld metal (WM) and heat-affected zone (HAZ) increases with cooling rate (laser > TIG > MAG). Consequently, laser- and TIG-welded steels exhibit higher yield strength than the base metal due to a substantially harder WM. In contrast, the strength of MAG-welded steel is reduced by a broad and soft WM and HAZ. The fatigue life of laser-and TIG-welded steel was similar, with both being greater than that of MAG-welded steel; however, the fatigue resistance of all welds was inferior to that of the non-welded base metal. Finally, crack initiation sites were found to differ depending on the microstructural characteristics of the welded zone, as well as the tensile and cyclic loading

Effect of protective gas on the properties of the pure support of super-martensitic stainless steel

International Nuclear Information System (INIS)

Zappa, Sebastian; Svoboda, Hernan G; Ramini de Rissone, N.Mabel; Surian, Estela S; De Vedia, Luis A

2006-01-01

This work studied the effect of protective gas on the operability, mechanical properties and microstructure of the super-martensitic stainless pure support metal, deposited with a metal-cored tubular wire, using the semi-automatic welding process under gaseous protection. Three pure support test tubes were welded following ANSI/AWS A5.22-95, with a 1.2 mm diameter tubular wire using three gaseous mixtures as protection: 70 % Ar-30 % He, 98 % Ar-2 % Co 2 and 82 % Ar-18 % Co 2 . The welding position was by hand with an average thermal support of 1.1 kJ/mm. Transverse cuts were extracted from each welded coupon for metallography and chemical composition, 1 'Minitrac' traction test piece and about 20 test pieces for a V-Charpy impact trial. The microstructure was defined with optic and scanning electronic microscopes and with X-ray diffraction. Micro hardness profiles were determined as well as the properties in traction and on impact. With reference to operability, the number of spatters increased noticeably with an increased content of Co 2 in the protective mixture. The content of Mn, Si and Mo dropped after increasing the gas oxidation potential. Regarding the mechanical properties small variations in the flow limit, the resistance to traction and the hardness for the different gaseous mixtures used were observed. A slight drop in the absorbed energy, with an increase in the Co2 content in the protective gas was noted in the V-Charpy impact tests carried out at 20, 0, -20, -40 and -60 o C. Expressions were obtained that correlated the measured properties with the oxidation potential of the gas for these materials. The microstructure consists of martensite, ferrite and retained austenite. Significant variations were not observed in the ferrite and austenite fractions for the different gases that were used (CW)

Ultraviolet/Optical Emission of the Ionized Gas in AGN: Diagnostics of the Ionizing Source and Gas Properties

Energy Technology Data Exchange (ETDEWEB)

Feltre, Anna [Univ Lyon, Univ Lyon1, Ens de Lyon, Centre National de la Recherche Scientifique, Centre de Recherche Astrophysique de Lyon UMR5574, Saint-Genis-Laval (France); Sorbonne Universités, UPMC-Centre National de la Recherche Scientifique, UMR7095, Institut d' Astrophysique de Paris, Paris (France); Charlot, Stephane [Sorbonne Universités, UPMC-Centre National de la Recherche Scientifique, UMR7095, Institut d' Astrophysique de Paris, Paris (France); Mignoli, Marco [INAF-Osservatorio Astronomico di Bologna, Bologna (Italy); Bongiorno, Angela [INAF-Osservatorio Astronomico di Roma, Monteporzio Catone (Italy); Calura, Francesco [INAF-Osservatorio Astronomico di Bologna, Bologna (Italy); Chevallard, Jacopo [Scientific Support Office, Directorate of Science and Robotic Exploration, European Space Research and Technology Centre (ESTEC), European Space Agency (ESA), Noordwijk (Netherlands); Curtis-Lake, Emma [Sorbonne Universités, UPMC-Centre National de la Recherche Scientifique, UMR7095, Institut d' Astrophysique de Paris, Paris (France); Gilli, Roberto [INAF-Osservatorio Astronomico di Bologna, Bologna (Italy); Plat, Adele, E-mail: anna.feltre@univ-lyon1.fr [Sorbonne Universités, UPMC-Centre National de la Recherche Scientifique, UMR7095, Institut d' Astrophysique de Paris, Paris (France)

2017-11-02

Spectroscopic studies of active galactic nuclei (AGN) are powerful means of probing the physical properties of the ionized gas within them. In particular, near future observational facilities, such as the James Webb Space Telescope (JWST), will allow detailed statistical studies of rest-frame ultraviolet and optical spectral features of the very distant AGN with unprecedented accuracy. In this proceedings, we discuss the various ways of exploiting new dedicated photoionization models of the narrow-line emitting regions (NLR) of AGN for the interpretation of forthcoming revolutionary datasets.

Application of conditional simulation of heterogeneous rock properties to seismic scattering and attenuation analysis in gas hydrate reservoirs

Science.gov (United States)

Huang, Jun-Wei; Bellefleur, Gilles; Milkereit, Bernd

2012-02-01

We present a conditional simulation algorithm to parameterize three-dimensional heterogeneities and construct heterogeneous petrophysical reservoir models. The models match the data at borehole locations, simulate heterogeneities at the same resolution as borehole logging data elsewhere in the model space, and simultaneously honor the correlations among multiple rock properties. The model provides a heterogeneous environment in which a variety of geophysical experiments can be simulated. This includes the estimation of petrophysical properties and the study of geophysical response to the heterogeneities. As an example, we model the elastic properties of a gas hydrate accumulation located at Mallik, Northwest Territories, Canada. The modeled properties include compressional and shear-wave velocities that primarily depend on the saturation of hydrate in the pore space of the subsurface lithologies. We introduce the conditional heterogeneous petrophysical models into a finite difference modeling program to study seismic scattering and attenuation due to multi-scale heterogeneity. Similarities between resonance scattering analysis of synthetic and field Vertical Seismic Profile data reveal heterogeneity with a horizontal-scale of approximately 50 m in the shallow part of the gas hydrate interval. A cross-borehole numerical experiment demonstrates that apparent seismic energy loss can occur in a pure elastic medium without any intrinsic attenuation of hydrate-bearing sediments. This apparent attenuation is largely attributed to attenuative leaky mode propagation of seismic waves through large-scale gas hydrate occurrence as well as scattering from patchy distribution of gas hydrate.

The comparison of physical properties derived from gas and dust in a massive star-forming region

Energy Technology Data Exchange (ETDEWEB)

Battersby, Cara; Bally, John; Ginsburg, Adam; Darling, Jeremy [Center for Astrophysics and Space Astronomy, University of Colorado, UCB 389, Boulder, CO 80309 (United States); Dunham, Miranda [Department of Astronomy, Yale University, New Haven, CT 06520 (United States); Longmore, Steve [Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead CH41 1LD (United Kingdom)

2014-05-10

We explore the relationship between gas and dust in a massive star-forming region by comparing the physical properties derived from each. We compare the temperatures and column densities in a massive star-forming Infrared Dark Cloud (G32.02+0.05), which shows a range of evolutionary states, from quiescent to active. The gas properties were derived using radiative transfer modeling of the (1,1), (2,2), and (4,4) transitions of NH{sub 3} on the Karl G. Jansky Very Large Array, while the dust temperatures and column densities were calculated using cirrus-subtracted, modified blackbody fits to Herschel data. We compare the derived column densities to calculate an NH{sub 3} abundance, χ{sub NH{sub 3}} = 4.6 × 10{sup –8}. In the coldest star-forming region, we find that the measured dust temperatures are lower than the measured gas temperatures (mean and standard deviations T {sub dust,} {sub avg} ∼ 11.6 ± 0.2 K versus T {sub gas,} {sub avg} ∼ 15.2 ± 1.5 K), which may indicate that the gas and dust are not well-coupled in the youngest regions (∼0.5 Myr) or that these observations probe a regime where the dust and/or gas temperature measurements are unreliable. Finally, we calculate millimeter fluxes based on the temperatures and column densities derived from NH{sub 3}, which suggest that millimeter dust continuum observations of massive star-forming regions, such as the Bolocam Galactic Plane Survey or ATLASGAL, can probe hot cores, cold cores, and the dense gas lanes from which they form, and are generally not dominated by the hottest core.

The comparison of physical properties derived from gas and dust in a massive star-forming region

International Nuclear Information System (INIS)

Battersby, Cara; Bally, John; Ginsburg, Adam; Darling, Jeremy; Dunham, Miranda; Longmore, Steve

2014-01-01

We explore the relationship between gas and dust in a massive star-forming region by comparing the physical properties derived from each. We compare the temperatures and column densities in a massive star-forming Infrared Dark Cloud (G32.02+0.05), which shows a range of evolutionary states, from quiescent to active. The gas properties were derived using radiative transfer modeling of the (1,1), (2,2), and (4,4) transitions of NH 3 on the Karl G. Jansky Very Large Array, while the dust temperatures and column densities were calculated using cirrus-subtracted, modified blackbody fits to Herschel data. We compare the derived column densities to calculate an NH 3 abundance, χ NH 3 = 4.6 × 10 –8 . In the coldest star-forming region, we find that the measured dust temperatures are lower than the measured gas temperatures (mean and standard deviations T dust, avg ∼ 11.6 ± 0.2 K versus T gas, avg ∼ 15.2 ± 1.5 K), which may indicate that the gas and dust are not well-coupled in the youngest regions (∼0.5 Myr) or that these observations probe a regime where the dust and/or gas temperature measurements are unreliable. Finally, we calculate millimeter fluxes based on the temperatures and column densities derived from NH 3 , which suggest that millimeter dust continuum observations of massive star-forming regions, such as the Bolocam Galactic Plane Survey or ATLASGAL, can probe hot cores, cold cores, and the dense gas lanes from which they form, and are generally not dominated by the hottest core.

Gas-Solid Reaction Properties of Fluorine Compounds and Solid Adsorbents for Off-Gas Treatment from Semiconductor Facility

Directory of Open Access Journals (Sweden)

Shinji Yasui

2012-01-01

Full Text Available We have been developing a new dry-type off-gas treatment system for recycling fluorine from perfluoro compounds present in off-gases from the semiconductor industry. The feature of this system is to adsorb the fluorine compounds in the exhaust gases from the decomposition furnace by using two types of solid adsorbents: the calcium carbonate in the upper layer adsorbs HF and converts it to CaF2, and the sodium bicarbonate in the lower layer adsorbs HF and SiF4 and converts them to Na2SiF6. This paper describes the fluorine compound adsorption properties of both the solid adsorbents—calcium carbonate and the sodium compound—for the optimal design of the fixation furnace. An analysis of the gas-solid reaction rate was performed from the experimental results of the breakthrough curve by using a fixed-bed reaction model, and the reaction rate constants and adsorption capacity were obtained for achieving an optimal process design.

Nanostructured tin oxide films: Physical synthesis, characterization, and gas sensing properties.

Science.gov (United States)

Ingole, S M; Navale, S T; Navale, Y H; Bandgar, D K; Stadler, F J; Mane, R S; Ramgir, N S; Gupta, S K; Aswal, D K; Patil, V B

2017-05-01

Nanostructured tin oxide (SnO 2 ) films are synthesized using physical method i.e. thermal evaporation and are further characterized with X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, and atomic force microscopy measurement techniques for confirming its structure and morphology. The chemiresistive properties of SnO 2 films are studied towards different oxidizing and reducing gases where these films have demonstrated considerable selectivity towards oxidizing nitrogen dioxide (NO 2 ) gas with a maximum response of 403% to 100ppm @200°C, and fast response and recovery times of 4s and 210s, respectively, than other test gases. In addition, SnO 2 films are enabling to detect as low as 1ppm NO 2 gas concentration @200°C with 23% response enhancement. Chemiresistive performances of SnO 2 films are carried out in the range of 1-100ppm and reported. Finally, plausible adsorption and desorption reaction mechanism of NO 2 gas molecules with SnO 2 film surface has been thoroughly discussed by means of an impedance spectroscopy analysis. Copyright © 2017 Elsevier Inc. All rights reserved.

High-resolution well-log derived dielectric properties of gas-hydrate-bearing sediments, Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

Science.gov (United States)

Sun, Y.; Goldberg, D.; Collett, T.; Hunter, R.

2011-01-01

A dielectric logging tool, electromagnetic propagation tool (EPT), was deployed in 2007 in the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well (Mount Elbert Well), North Slope, Alaska. The measured dielectric properties in the Mount Elbert well, combined with density log measurements, result in a vertical high-resolution (cm-scale) estimate of gas hydrate saturation. Two hydrate-bearing sand reservoirs about 20 m thick were identified using the EPT log and exhibited gas-hydrate saturation estimates ranging from 45% to 85%. In hydrate-bearing zones where variation of hole size and oil-based mud invasion are minimal, EPT-based gas hydrate saturation estimates on average agree well with lower vertical resolution estimates from the nuclear magnetic resonance logs; however, saturation and porosity estimates based on EPT logs are not reliable in intervals with substantial variations in borehole diameter and oil-based invasion.EPT log interpretation reveals many thin-bedded layers at various depths, both above and below the thick continuous hydrate occurrences, which range from 30-cm to about 1-m thick. Such thin layers are not indicated in other well logs, or from the visual observation of core, with the exception of the image log recorded by the oil-base microimager. We also observe that EPT dielectric measurements can be used to accurately detect fine-scale changes in lithology and pore fluid properties of hydrate-bearing sediments where variation of hole size is minimal. EPT measurements may thus provide high-resolution in-situ hydrate saturation estimates for comparison and calibration with laboratory analysis. ?? 2010 Elsevier Ltd.

Transparent nanocellulosic multilayer thin films on polylactic acid with tunable gas barrier properties.

Science.gov (United States)

Aulin, Christian; Karabulut, Erdem; Tran, Amy; Wågberg, Lars; Lindström, Tom

2013-08-14

The layer-by-layer (LbL) deposition method was used for the build-up of alternating layers of nanofibrillated cellulose (NFC) or carboxymethyl cellulose (CMC) with a branched, cationic polyelectrolyte, polyethyleneimine (PEI) on flexible poly (lactic acid) (PLA) substrates. With this procedure, optically transparent nanocellulosic films with tunable gas barrier properties were formed. 50 layer pairs of PEI/NFC and PEI/CMC deposited on PLA have oxygen permeabilities of 0.34 and 0.71 cm(3)·μm/m(2)·day·kPa at 23 °C and 50% relative humidity, respectively, which is in the same range as polyvinyl alcohol and ethylene vinyl alcohol. The oxygen permeability of these multilayer nanocomposites outperforms those of pure NFC films prepared by solvent-casting. The nanocellulosic LbL assemblies on PLA substrates was in detailed characterized using a quartz crystal microbalance with dissipation (QCM-D). Atomic force microscopy (AFM) reveals large structural differences between the PEI/NFC and the PEI/CMC assemblies, with the PEI/NFC assembly showing a highly entangled network of nanofibrils, whereas the PEI/CMC surfaces lacked structural features. Scanning electron microscopy images showed a nearly perfect uniformity of the nanocellulosic coatings on PLA, and light transmittance results revealed remarkable transparency of the LbL-coated PLA films. The present work demonstrates the first ever LbL films based on high aspect ratio, water-dispersible nanofibrillated cellulose, and water-soluble carboxymethyl cellulose polymers that can be used as multifunctional films and coatings with tailorable properties, such as gas barriers and transparency. Owing to its flexibility, transparency and high-performance gas barrier properties, these thin film assemblies are promising candidates for several large-scale applications, including flexible electronics and renewable packaging.

Adsorbent filled membranes for gas separation. Part 1. Improvement of the gas separation properties of polymeric membranes by incorporation of microporous adsorbents

NARCIS (Netherlands)

Duval, J.M.; Duval, J.-M.; Folkers, Albertje; Mulder, M.H.V.; Desgrandchamps, G.; Smolders, C.A.; Smolders, C.A.

1993-01-01

The effect of the introduction of specific adsorbents on the gas separation properties of polymeric membranes has been studied. For this purpose both carbon molecular sieves and zeolites are considered. The results show that zeolites such as silicate-1, 13X and KY improve to a large extent the

Physical properties of CO-dark molecular gas traced by C+

Science.gov (United States)

Tang, Ningyu; Li, Di; Heiles, Carl; Wang, Shen; Pan, Zhichen; Wang, Jun-Jie

2016-09-01

Context. Neither Hi nor CO emission can reveal a significant quantity of so-called dark gas in the interstellar medium (ISM). It is considered that CO-dark molecular gas (DMG), the molecular gas with no or weak CO emission, dominates dark gas. Determination of physical properties of DMG is critical for understanding ISM evolution. Previous studies of DMG in the Galactic plane are based on assumptions of excitation temperature and volume density. Independent measurements of temperature and volume density are necessary. Aims: We intend to characterize physical properties of DMG in the Galactic plane based on C+ data from the Herschel open time key program, namely Galactic Observations of Terahertz C+ (GOT C+) and Hi narrow self-absorption (HINSA) data from international Hi 21 cm Galactic plane surveys. Methods: We identified DMG clouds with HINSA features by comparing Hi, C+, and CO spectra. We derived the Hi excitation temperature and Hi column density through spectral analysis of HINSA features. The Hi volume density was determined by utilizing the on-the-sky dimension of the cold foreground Hi cloud under the assumption of axial symmetry. The column and volume density of H2 were derived through excitation analysis of C+ emission. The derived parameters were then compared with a chemical evolutionary model. Results: We identified 36 DMG clouds with HINSA features. Based on uncertainty analysis, optical depth of HiτHi of 1 is a reasonable value for most clouds. With the assumption of τHi = 1, these clouds were characterized by excitation temperatures in a range of 20 K to 92 K with a median value of 55 K and volume densities in the range of 6.2 × 101 cm-3 to 1.2 × 103 cm-3 with a median value of 2.3 × 102 cm-3. The fraction of DMG column density in the cloud (fDMG) decreases with increasing excitation temperature following an empirical relation fDMG =-2.1 × 10-3Tex,(τHi = 1) + 1.0. The relation between fDMG and total hydrogen column density NH is given by f

Gas Permeation Properties of Soluble Aromatic Polyimides Based on 4-Fluoro-4,4'-Diaminotriphenylmethane

Directory of Open Access Journals (Sweden)

Diego Guzmán-Lucero

2015-04-01

Full Text Available A series of new organic polyimides were synthesized from 4-fluoro-4'4"-diaminotriphenylmethane and four different aromatic dianhydrides through a one-step, high-temperature, direct polycondensation in m-cresol at 180–200 °C, resulting in the formation of high-molecular-weight polyimides (inherent viscosities ~ 1.0–1.3 dL/g. All the resulting polyimides exhibited good thermal stability with initial decomposition temperatures above 434 °C, glass-transition temperatures between 285 and 316 °C, and good solubility in polar aprotic solvents. Wide-angle X-ray scattering data indicated that the polyimides were amorphous. Dense membranes were prepared by solution casting and solvent evaporation to evaluate their gas transport properties (permeability, diffusivity, and solubility coefficients toward pure hydrogen, helium, oxygen, nitrogen, methane, and carbon dioxide gases. In general, the gas permeability was increased as both the fractional free volume and d-spacing were also increased. A good combination of permeability and selectivity was promoted efficiently by the bulky hexafluoroisopropylidene and 4-fluoro-phenyl groups introduced into the polyimides. The results indicate that the gas transport properties of these films depend on both the structure of the anhydride moiety, which controls the intrinsic intramolecular rigidity, and the 4-fluoro-phenyl pendant group, which disrupts the intermolecular packing.

A System And Method To Determine Thermophysical Properties Of A Multi-Component Gas At Arbitrary Temperature And Pressure

Science.gov (United States)

Morrow, Thomas E.; Behring, II, Kendricks A.

2004-03-09

A method to determine thermodynamic properties of a natural gas hydrocarbon, when the speed of sound in the gas is known at an arbitrary temperature and pressure. Thus, the known parameters are the sound speed, temperature, pressure, and concentrations of any dilute components of the gas. The method uses a set of reference gases and their calculated density and speed of sound values to estimate the density of the subject gas. Additional calculations can be made to estimate the molecular weight of the subject gas, which can then be used as the basis for mass flow calculations, to determine the speed of sound at standard pressure and temperature, and to determine various thermophysical characteristics of the gas.

Effect of residual gas on structural, electrical and mechanical properties of niobium films deposited by magnetron sputtering deposition

Science.gov (United States)

Wang, Lanruo; Zhong, Yuan; Li, Jinjin; Cao, Wenhui; Zhong, Qing; Wang, Xueshen; Li, Xu

2018-04-01

Magnetron sputtering is an important method in the superconducting thin films deposition. The residual gas inside the vacuum chamber will directly affect the quality of the superconducting films. In this paper, niobium films are deposited by magnetron sputtering under different chamber residual gas conditions. The influence of baking and sputtering process on residual gas are studied as well. Surface morphology, electrical and mechanical properties of the films are analysed. The residual gas analysis result before the sputtering process could be regarded as a reference condition to achieve high quality superconducting thin films.

Ultraviolet/Optical Emission of the Ionized Gas in AGN: Diagnostics of the Ionizing Source and Gas Properties

Directory of Open Access Journals (Sweden)

Anna Feltre

2017-11-01

Full Text Available Spectroscopic studies of active galactic nuclei (AGN are powerful means of probing the physical properties of the ionized gas within them. In particular, near future observational facilities, such as the James Webb Space Telescope (JWST, will allow detailed statistical studies of rest-frame ultraviolet and optical spectral features of the very distant AGN with unprecedented accuracy. In this proceedings, we discuss the various ways of exploiting new dedicated photoionization models of the narrow-line emitting regions (NLR of AGN for the interpretation of forthcoming revolutionary datasets.

Pressure-dependent pure- and mixed-gas permeation properties of Nafion®

KAUST Repository

Mukaddam, Mohsin Ahmed

2016-04-20

The permeation properties of Nafion® at 35 °C are presented for pure gases H2, N2, O2, CH4, CO2, C2H6 and C3H8, as a function of pressure between 2 and 20 atm. The effect of pressure on permeability and selectivity is analyzed to understand two observed phenomena: compression and plasticization. In pure-gas experiments, at increasing feed pressure, compression of the polymer matrix reduced the permeability of low-sorbing penetrants H2, N2, O2, and CH4. In contrast, permeabilities of more soluble penetrants CO2 and C2H6 increased by 18% and 46% respectively, as plasticization effects overcame compression effects. Permeability of C3H8 decreased slightly with increasing pressure up to 4.6 atm as a result of compression, then increased by 3-fold at 9 atm as a result of plasticization associated with high C3H8 solubility. Binary CO2/CH4 (50:50) mixed-gas experiments at total feed pressures up to 36 atm quantified the effect of CO2 plasticization on separation performance. At 10 atm CO2 partial pressure, CH4 permeability increased by 23% relative to its pure-gas value of 0.078 Barrer, while CO2 permeability decreased by 28%. Consequently, CO2/CH4 selectivity decreased to 19, i.e., 42% below its pure-gas value of 32.

Influence of shielding gas on the mechanical and metallurgical properties of DP-GMA-welded 5083-H321 aluminum alloy

Science.gov (United States)

Koushki, Amin Reza; Goodarzi, Massoud; Paidar, Moslem

2016-12-01

In the present research, 6-mm-thick 5083-H321 aluminum alloy was joined by the double-pulsed gas metal arc welding (DP-GMAW) process. The objective was to investigate the influence of the shielding gas composition on the microstructure and properties of GMA welds. A macrostructural study indicated that the addition of nitrogen and oxygen to the argon shielding gas resulted in better weld penetration. Furthermore, the tensile strength and bending strength of the welds were improved when oxygen and nitrogen (at concentrations as high as approximately 0.1vol%) were added to the shielding gas; however, these properties were adversely affected when the oxygen and nitrogen contents were increased further. This behavior was attributed to the formation of excessive brown and black oxide films on the bead surface, the formation of intermetallic compounds in the weld metal, and the formation of thicker oxide layers on the bead surface with increasing nitrogen and oxygen contents in the argon-based shielding gas. Analysis by energy-dispersive X-ray spectroscopy revealed that most of these compounds are nitrides or oxides.

Gas-sensing properties of In{sub 2}O{sub 3} films modified with gold nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Korotcenkov, G., E-mail: ghkoro@yahoo.com [School of Material Science and Engineering, Gwangju Institute of Science and Technology, Gwangju (Korea, Republic of); Brinzari, V. [Department of Theoretical Physics, State University of Moldova, Chisinau, Republic of Moldova (Moldova, Republic of); Han, S.H. [Division of Maritime Transportation System, Mokpo National Maritime University, Mokpo (Korea, Republic of); Cho, B.K., E-mail: chobk@gist.ac.kr [School of Material Science and Engineering, Gwangju Institute of Science and Technology, Gwangju (Korea, Republic of)

2016-06-01

A study of the surface and gas–sensitive properties of In{sub 2}O{sub 3} films modified with gold nanoparticles and synthesized by the successive ionic layer deposition (SILD) method was conducted. In{sub 2}O{sub 3} films were prepared using the spray pyrolysis method. The gas-sensing characteristics were tested using CO, H{sub 2}, and O{sub 3} as target gases. It has been shown that the surface modification with gold nanoparticles gives the opportunity to optimize the response of In{sub 2}O{sub 3}-based gas sensors to both reducing (CO, H{sub 2}) and oxidizing (O{sub 3}) gases. It has been found that the sensitizing effect during ozone detection was significantly higher than the effect during CO and H{sub 2} detection. It has been demonstrated that the sensitizing effect depended on the number of SILD cycles used for gold nanoparticle deposition and was maximal for the In{sub 2}O{sub 3} surface decorated with gold nanoparticles with the smallest size. The mechanism of the gold nanoparticles' influence on the gas-sensing properties of the In{sub 2}O{sub 3} films is also discussed. It is suggested that to explain the observed effects, we have to consider both the “electronic” and “chemical” mechanisms of sensitization. Suggestions for studies to be carried out to further improve both the understanding of the nature of the gas-sensitive effects and the parameters of In{sub 2}O{sub 3}:Au-based gas sensors are also formulated. - Highlights: • In{sub 2}O{sub 3} gas sensors modified with gold nanoparticles using SILD method are studied. • AuNPs exhibit activity during interaction with either reducing or oxidizing gases. • Maximal effect of optimization is observed during ozone detection. • Sensitizing effect depends on the number of SILD cycles. • Proposed mechanisms explain effects observed in the In{sub 2}O{sub 3}:Au based gas sensors.

Study of sensing properties of SnO2 prepared by spray-pyrolysis deposition towards ethanol gas

Science.gov (United States)

Saadaldin, Nasser M.; Hussain, Nabiha; AlZouabi, Abla

2018-05-01

Ethanol is widely used in all kinds of products with direct exposure to the human skin (e.g. medicinal products like hand disinfectants in occupational settings, cosmetics like hairsprays or mouthwashes, in this study, thin films of (SnO2) were deposited by using the thermal spray method (SPD) on quartz at 450°C substrate temperature using tin chloride SnCl2.2H2O, (1.0M). A gas sensor was constructed with the prepared SnO2, used to detect ethanol gas and some other gases. The films were characterized by X-ray diffraction (XRD), and scanning electron microscopy (SEM). The grain size was calculated the results showed nanostructure polycrystalline and crystallize in a tetragonal, S.G:P42/m nm, reaching grain Size approximately 27nm. The sensing properties of the films were studied towards ethanol at different concentrations ranging within (1-200 ppm,) the results showed that the sensitivity of the film increases with the concentration of ethanol, the best operating temperature reached about 300 °C, We studied the sensing properties of the films towards Ethanol alcohol gas, The first and foremost concerns of topical ethanol applications for public health are its carcinogenic effects, high selectivity and sensitivity of the film towards ethanol gas was found compared to other tested toxic gases such as methanol gas, acetone and methylbenzene. Yet an upto-date risk assessment of ethanol application on the skin and inside the oral cavity is currently lacking.

Plasma sprayed thermal barrier coatings for industrial gas turbines: morphology, processing and properties

International Nuclear Information System (INIS)

Gruenling, H.W.; Mannsmann, W.

1993-01-01

Thermal barrier coatings out of fully or partially stabilized zirconia offer a unique chance in gas turbines to increase the gas inlet temperature significantly while keeping the temperature of the structural material of the component within conventional limits. The protection of combustor parts and transition pieces as well as of some stationary gas turbine parts however is state of the art. As a consequence of still insufficient reliability, the application for hot rotating parts is very limited. The introduction as a design element requires safe life within defined time intervals. These depend on the overhaul and repair intervals of the engines. For large land based industrial or utility gas turbines, for example, coating life between 25.000 and 30.000 hrs. is a minimum requirement. Premature failure of a coating by e.g. local spalling causes local overheating of the component with the consequence of its total destruction or even more expensive secondary damages. Life limiting is the corrosion rate at the ceramic-metal interface and the behavior of the coated system under transient operating conditions, where multiaxial strain and stress distributions are generated. Sufficient strain tolerance of the coating both under tensile as well as compressive conditions is required. The properties of thermal barrier coating systems depend strongly on the structure and phase composition of the coating layers and the morphology of and the adhesion at the ceramic-metal interface. They have to be controlled by the process itself, the process parameters and the characteristics of the applied materials (e.g. chemical composition, processing, morphology, particle size and size distribution). It will be reviewed, how properties and structures of coating systems correlate and how structures can be modified by careful control of the process parameters. (orig.)

Analysis Of The Effect Of Fuel Enrichment Error On Neutronic Properties Of The RSG-GAS Core

International Nuclear Information System (INIS)

Saragih, Tukiran; Pinem, Surian

2002-01-01

The analysis of the fuel enrichment error effect on neutronic properties has been carried out. The fuel enrichment could be improperly done because of wrong fabrication. Therefore it is necessary to analyze the fuel enrichment error effect to determine how many percents the fuel enrichment maximum can be accepted in the core. The analysis was done by simulation method The RSG-GAS core was simulated with 5 standard fuels and 1 control element having wrong enrichment when inserted into the core. Fuel enrichment error was then simulated from 20%, 25% and 30% and the simulation was done using WIMSD/4 and Batan-2DIFF codes. The cross section of core material of the RSG-GAS was generated by WIMSD/4 code in 1-D, X-Y geometry and 10 energy neutron group. Two dimensions, diffusion calculation based on finite element method was done by using Batan-2DIFF code. Five fuel elements and one control element changed the enrichment was finally arranged as a new core of the RSG-Gas reactor. The neutronic properties can be seen from eigenvalues (k eff ) as well as from the kinetic properties based on moderator void reactivity coefficient. The calculated results showed that the error are still acceptable by k eff 1,097 even until 25% fuel enrichment but not more than 25,5%

Effect of solution plasma process with bubbling gas on physicochemical properties of chitosan.

Science.gov (United States)

Ma, Fengming; Li, Pu; Zhang, Baiqing; Zhao, Xin; Fu, Qun; Wang, Zhenyu; Gu, Cailian

2017-05-01

In the present work, solution plasma process (SPP) with bubbling gas was used to prepare oligochitosan. The effect of SPP irradiation with bubbling gas on the degradation of chitosan was evaluated by the intrinsic viscosity reduction rate and the degradation kinetic. The formation of OH radical was studied. Changes of the physicochemical properties of chitosan were measured by scanning electron microscopy, X-ray diffraction, and thermogravimetric analysis, as well as ultraviolet-visible, Fourier-transform infrared, and 13 C nuclear magnetic resonance spectroscopy. The results indicated an obvious decrease in the intrinsic viscosity reduction rate after SPP irradiation with bubbling gas, and that the rate with bubbling was higher than that without. The main chemical structure of chitosan remained intact after irradiation, but changes in the morphology, crystallinity, and thermal stability of oligochitosan were observed. In particular, the crystallinity and thermal stability tended to decrease. The present study indicated that SPP can be effectively used for the degradation of chitosan. Copyright © 2017. Published by Elsevier B.V.

Synthesis and properties of ZnO nanorods as ethanol gas sensors

International Nuclear Information System (INIS)

Mirabbaszadeh, K; Mehrabian, M

2012-01-01

Uniform ZnO nanorods were synthesized via the sol-gel process under mild conditions in which different ZnO nanostructures have been prepared by changing the pH of growth solution. It was seen that the optimum nanorods were grown at pH 11.33. The prepared ZnO nanostructures and morphologies were characterized by x-ray diffraction and scanning electron microscopy measurements. The ZnO one-dimensional nanostructures were found to have a wurtzite hexagonal crystalline structure and grow along the [001] direction. The optimum nanorods were about 1 μm in length and less than 100 nm in diameter. The ZnO nanostructures have been tested for different concentrations and different operating temperatures for ethanol vapor in air and the surface resistance of the sensors has been evaluated as a function of different parameters. The gas sensor fabricated from ZnO nanorods grown in solution with a special pH exhibited good performance. The sensor response to 5000 ppm ethanol was up to about 2.5 at the operating temperature of 300 °C. The differences in gas-sensing performance between the sensors were analyzed based on the defects created in the nanorods during their fast growth. The correlations between material structures and the properties of the gas sensors are discussed.

Oil and gas property transfers: Analyzing the environmental risk through the environmental site assessment process

International Nuclear Information System (INIS)

Bratberg, D.; Hocker, S.

1994-01-01

The Superfund Act made anyone buying contaminated real estate liable for cleanup costs whether they know about the contamination or contributed to the contamination. In 1986, SARA amended the Superfund Act to include a provision known as the ''Innocent Landowner Defense.'' This provision created a defense for purchasers of contaminated property who did not contribute to the contamination and had no reason to believe that the property was contaminated at the time of the real estate transfer. SARA allows the purchasers and lenders to perform an environmental assessment using ''due diligence'' to identify contamination problems existing at a site. Since the passing of SARA, the environmental site assessment (ESA) process has become commonplace during the transfer of commercial real estate. Since the introduction of SARA, many professional associations, governmental agencies, and proposed federal legislation have struggled to produce a standard for conducting Phase 1 ESAs. Only recently has a standard been produced. Until recently, the domestic oil and gas industry has been relatively unconcerned about the Superfund liability issues. This approach was created by Congress's decision in 1980 to temporarily exempt the majority of oil and gas exploration and production wastes from federal hazardous waste rulings. However, new stringent rules governing oil and gas waste management practices are being considered by federal and state regulatory agencies. Based upon this knowledge and the awakening of public awareness, the use of ESAs for oil and gas transactions is increasing

Dependence of cycle optimal configuration for closed gas turbines on thermodynamic properties of working fluids

International Nuclear Information System (INIS)

Andryushchenko, A.I.; Dubinin, A.B.; Krylov, E.E.

1988-01-01

The problem of choice of working fluids for NPP closed gas turbines (CGT) is discussed. Thermostable in the working temperature range, chemically inert relatively to structural materials, fire- and explosion - proof substances, radiation-resistant and having satisfactory neutron-physical characteristics are used as the working fluids. Final choice of a gas as a working fluid is exercised based on technical and economic comparison of different variants at optimum thermodynamic cycle and parameters for each gas. The character and degree of the effect of thermodynamic properties of gases on configuration of reference cycles of regenerative CGT are determined. It is established that efficiency and optimum parameters in nodal points of the reference cycle are specified by the degree of removing the compression processes from the critical point. Practical importance of the obtained results presupposes the possibility of rapid estimation of the efficiency of using a gas without multiparametric optimization

Practice points on three aspects of oil and gas property transactions - operatorship, confidentiality and title review

International Nuclear Information System (INIS)

Edwards, P.D.

1999-01-01

Practice points regarding three aspects of oil and gas property transactions were described. The first topic dealt with purchase and sale transactions and how to determine which party is entitled to act as the Operator following the sale of the Operator's interest. The second topic addressed issues of confidentiality in connection with oil and gas transactions. The final point discussed contractual provisions relating to title defects, along with their many variations and legal consequences. All three of these topics present issues which give rise to a surprising number of disputes, but which frequently receive only cursory attention in the negotiation and documentation of oil and gas transactions

Physical properties of sediments from the JAPEX/JNOC/GSC Mallik 2L-38 gas hydrate research well

Science.gov (United States)

Winters, W.J.

1999-01-01

A 1150 m deep gas hydrate research well was drilled in the Canadian Arctic in February and March 1998 to investigate the interaction between the presence of gas hydrate and the natural conditions presented by the host sediments. Profiles of the following measured and derived properties are presented from that investigation: water content, sediment wet bulk density, grain size, porosity, gas hydrate quantity, and salinity. These data indicate that the greatest concentration of gas hydrate is located within sand and gravel deposits between 897 m and 922 m. American Society for Testing and Materials 1997: Standard test method for specific gravity of soil solids by gas pycnometer D 5550-94; in American Society for Testing and Materials, Annual Book of ASTM Standards, v. 04.09, Soil and Rock, West Conshohocken, Pennsylvania, p. 380-383.

Thermostatistic properties of a q-deformed ideal Fermi gas with a general energy spectrum

International Nuclear Information System (INIS)

Cai, Shukuan; Su, Guozhen; Chen, Jincan

2007-01-01

The thermostatistic problems of a q-deformed ideal Fermi gas in any dimensional space and with a general energy spectrum are studied, based on the q-deformed Fermi-Dirac distribution. The effects of the deformation parameter q on the properties of the system are revealed. It is shown that q-deformation results in some novel characteristics different from those of an ordinary system. Besides, it is found that the effects of the q-deformation on the properties of the Fermi systems are very different for different dimensional spaces and different energy spectrums

Effect of permafrost properties on gas hydrate petroleum system in the Qilian Mountains, Qinghai, Northwest China.

Science.gov (United States)

Wang, Pingkang; Zhang, Xuhui; Zhu, Youhai; Li, Bing; Huang, Xia; Pang, Shouji; Zhang, Shuai; Lu, Cheng; Xiao, Rui

2014-12-01

The gas hydrate petroleum system in the permafrost of the Qilian Mountains, which exists as an epigenetic hydrocarbon reservoir above a deep-seated hydrocarbon reservoir, has been dynamic since the end of the Late Pleistocene because of climate change. The permafrost limits the occurrence of gas hydrate reservoirs by changing the pressure-temperature (P-T) conditions, and it affects the migration of the underlying hydrocarbon gas because of its strong sealing ability. In this study, we reconstructed the permafrost structure of the Qilian Mountains using a combination of methods and measured methane permeability in ice-bearing sediment permafrost. A relationship between the ice saturation of permafrost and methane permeability was established, which permitted the quantitative evaluation of the sealing ability of permafrost with regard to methane migration. The test results showed that when ice saturation is >80%, methane gas can be completely sealed within the permafrost. Based on the permafrost properties and genesis of shallow gas, we suggest that a shallow "gas pool" occurred in the gas hydrate petroleum system in the Qilian Mountains. Its formation was related to a metastable gas hydrate reservoir controlled by the P-T conditions, sealing ability of the permafrost, fault system, and climatic warming. From an energy perspective, the increasing volume of the gas pool means that it will likely become a shallow gas resource available for exploitation; however, for the environment, the gas pool is an underground "time bomb" that is a potential source of greenhouse gas.

Ferrite thin films: Synthesis, characterization and gas sensing properties towards LPG

Energy Technology Data Exchange (ETDEWEB)

Rao, Pratibha; Godbole, R.V. [Department of Physics, Abasaheb Garware College, Karve Road, Pune 411 004 (India); Phase, D.M. [UGC-DAE CSR Centre, Indore (India); Chikate, R.C. [Department of Chemistry, Abasaheb Garware College, Karve Road, Pune 411 004 (India); Bhagwat, Sunita, E-mail: smb.agc@gmail.com [Department of Physics, Abasaheb Garware College, Karve Road, Pune 411 004 (India)

2015-01-15

Nanocrystalline (Co, Cu, Ni, Zn) ferrite thin films have been deposited onto the Si (100) and alumina substrates by spray pyrolysis deposition technique. Respective metal chlorides and iron chloride were used as precursors. The structural properties of (Co, Cu, Ni, Zn) ferrite thin films were investigated by X-ray diffraction (XRD) technique which confirms polycrystalline nature and single phase spinel structure. The surface morphology was studied using scanning electron microscopy (SEM) which reveals spherical morphology for these films except NiFe{sub 2}O{sub 4} films that exhibit petal like structure. The optical transmittance and reflectance measurements were recorded using a double beam spectrophotometer. The optical studies reveal that the transition is direct band gap energy. The VSM analyzes reveal the predominant ferrimagnetic nature for CuFe{sub 2}O{sub 4} films. The gas sensing properties towards Liquid Petroleum Gas (LPG) revealed that ZnFe{sub 2}O{sub 4} films are sensitive at lower temperature while NiFe{sub 2}O{sub 4} films show steep rise at higher temperature. - Highlights: • (Co, Cu, Ni, Zn) ferrite thin films are synthesized by simple spray pyrolysis technique. • Homogenization of substituent within ferrite structure. • CuFe{sub 2}O{sub 4} film exhibits predominantly ferrimagnetic nature. • LPG sensing at lower temperature for ZnFe{sub 2}O{sub 4} film. • High sensitivity for NiFe{sub 2}O{sub 4} film at higher temperature due to defects created in the structure.

Some Properties of Polymer Modified Self-Compacting Concrete Exposed to Kerosene and Gas Oil

Directory of Open Access Journals (Sweden)

Nada Mahdi Fawzi

2017-01-01

Full Text Available This thesis aims to study the effect of addition polymer materials on mechanical properties of self-compacting concrete, and also to assess the influence of petroleum products (kerosene and gas oil on mechanical properties of polymer modified self-compacting concrete (PMSCC after different exposure periods of (30 ,60 ,90 ,and 180 days. Two type of curing are used; 28 days in water for SCC and 2 days in water followed 26 days in air for PMSCC. The test results show that the PMSCC (15% P/C ratio which is exposed to oil products recorded a lower deterioration in compressive strength's values than reference concrete. The percentages of reduction in compressive strength values of PMSCC (15% P/C ratio was (6.03% and (9.61% up to 180 days of exposure to kerosene and gas oil respectively, relative to the same mix immersed in water, while the percentages of reduction in compressive strength values of SCC (reference concrete was (21.18% and (25.19% up to 180 days of exposure to kerosene and gas oil respectively, relative to the same mix immersed in water. Flexural strength results present improvement for all ages and for all concrete mixes with all percentages of polymer content The total water absorption values of PMSCC (15% P/C ratio showed a better performance than reference concrete mix when exposed to oil products. It was (1.34, 2.21, 2.17 % up to 180 days with samples immersed in water, kerosene, and gas oil respectively, with percentages of reduction of (23.86%, (33.83%, and (31.33% relative to the SCC (reference concrete.

Effect of gas ratio on tribological properties of sputter deposited TiN coatings

Energy Technology Data Exchange (ETDEWEB)

Chavda, Mahesh R., E-mail: maheshchavda1990@gmail.com [Department of Mechanical Engineering, Dr. Jivraj Mehta Institute of Technology, Mogar-388340 (India); Chauhan, Kamlesh V.; Rawal, Sushant K., E-mail: sushantrawal.me@charusat.ac.in [CHAMOS Matrusanstha Department of Mechanical Engineering, Chandubhai S. Patel Institute of Technology, Charotar University of Science and Technology (CHARUSAT), Changa-388421 (India)

2016-05-06

Titanium nitride (TiN) coatings were deposited on Si, corning glass, pins of mild steel (MS, ϕ3mm), aluminium (Al, ϕ4mm) and brass (ϕ6mm) substratesby DC magnetron sputtering. The argon and nitrogen (Ar:N{sub 2})gas ratio was precisely controlled by Mass Flow Controller (MFC) and was varied systematically at diffract values of 10:10,12:08, 16:04 and 18:02sccm. The structural properties of TiN coatings were characterized by X-ray diffraction (XRD) and its surface topography was studied using field emission scanning electron microscopy (FE-SEM). The tribological properties of TiN coatings were investigated using pin-on-disc tribometer.

Effect of the purging gas on properties of Ti stabilized AISI 321 stainless steel TIG welds

Energy Technology Data Exchange (ETDEWEB)

Taban, Emel; Kaluc, Erdinc; Aykan, T. Serkan [Kocaeli Univ. (Turkey). Dept. of Mechanical Engineering

2014-07-01

Gas purging is necessary to provide a high quality of stainless steel pipe welding in order to prevent oxidation of the weld zone inside the pipe. AISI 321 stabilized austenitic stainless steel pipes commonly preferred in refinery applications have been welded by the TIG welding process both with and without the use of purging gas. As purging gases, Ar, N{sub 2}, Ar + N{sub 2} and N{sub 2} + 10% H{sub 2} were used, respectively. The aim of this investigation is to detect the effect of purging gas on the weld joint properties such as microstructure, corrosion, strength and impact toughness. Macro sections and microstructures of the welds were investigated. Chemical composition analysis to obtain the nitrogen, oxygen and hydrogen content of the weld root was done by Leco analysis. Ferrite content of the beads including root and cap passes were measured by a ferritscope. Vickers hardness (HV10) values were obtained. Intergranular and pitting corrosion tests were applied to determine the corrosion resistance of all welds. Type of the purging gas affected pitting corrosion properties as well as the ferrite content and nitrogen, oxygen and hydrogen contents at the roots of the welds. Any hot cracking problems are not predicted as the weld still solidifies with ferrite in the primary phase as confirmed by microstructural and ferrite content analysis. Mechanical testing showed no significant change according to the purge gas. AISI 321 steel and 347 consumable compositions would permit use of nitrogen rich gases for root shielding without a risk of hot cracking.

Microstructure and magnetic properties of inert gas atomized rare earth permanent magnetic materials

International Nuclear Information System (INIS)

Sellers, C.H.; Hyde, T.A.; Branagan, D.J.; Lewis, L.H.; Panchanathan, V.

1997-01-01

Several permanent magnet alloys based on the ternary Nd 2 Fe 14 B (2-14-1) composition have been prepared by inert gas atomization (IGA). The microstructure and magnetic properties of these alloys have been studied as a function of particle size, both before and after heat treatment. Different particle sizes have characteristic properties due to the differences in cooling rate experienced during solidification from the melt. These properties are also strongly dependent on the alloy composition due to the cooling rate close-quote s effect on the development of the phase structure; the use of rare earth rich compositions appears necessary to compensate for a generally inadequate cooling rate. After atomization, a brief heat treatment is necessary for the development of the optimal microstructure and magnetic properties, as seen from the hysteresis loop shape and improvements in key magnetic parameters (intrinsic coercivity H ci , remanence B r , and maximum energy product BH max ). By adjusting alloy compositions specifically for this process, magnetically isotropic powders with good magnetic properties can be obtained and opportunities for the achievement of better properties appear to be possible. copyright 1997 American Institute of Physics

Acetone gas-sensing properties of multiple-networked Pd-decorated Bi_2O_3 nanorod sensors

International Nuclear Information System (INIS)

Park, Sung Hoon; Kim, Soo Hyun; Lee, Sang Min; Lee, Chong Mu

2015-01-01

This study examined the sensing properties of Bi_2O_3 nanorods decorated with Pd nanoparticles. Pd-decorated β-Bi_2O_3 nanorods were prepared by immersing the Bi_2O_3 nanorods in ethanol/(50 mM)PdCl_2 solution followed by UV irradiation and annealing. The Bi_2O_3 nanorods decorated with Pd nanoparticles showed faster and stronger response to acetone gas than the pristine Bi_2O_3 nanorods. Interestingly, the difference in response time between the Pd-decorated Bi_2O_3 nanorod sensor and pristine Bi_2O_3 nanorod sensor increased with increasing the acetone gas concentration. In contrast, the difference in recovery time between the two nanorod sensors decreased with increasing the acetone gas concentration. This difference can be explained using the chemical mechanism. The underlying mechanism for the enhanced response of the Bi_2O_3 nanorods decorated with Pd nanoparticles to acetone gas is also discussed

Gas flow rate and powder flow rate effect on properties of laser metal deposited Ti6Al4V

CSIR Research Space (South Africa)

Pityana, S

2013-03-01

Full Text Available . The powder flow rate and the gas flow rate were varied to study their effect on the physical, metallurgical and mechanical properties of the deposits. The physical properties studied are: the track width, the track height and the deposit weight...

Coalbed gas development

International Nuclear Information System (INIS)

Anon.

1992-01-01

This book includes: Overview of coalbed gas development; Coalbed gas development in the West Coalbed gas development on Indian lands; Multi-mineral development conflicts; Statutory solutions to ownership disputes; State and local regulation; Environmental regulations; Status of the section 29 tax credit extension; Using the section 29 credit; Leasing coalbed gas prospects; Coalbed gas joint operating agreements and Purchase and sale agreements for coalbed gas properties

Effects of variation of oil and zinc oxide type on the gas barrier and mechanical properties of chlorobutyl rubber/epoxidised natural rubber blends

International Nuclear Information System (INIS)

Li, Lin; Zhang, Jin; Jo, Jae Ok; Datta, Sanjoy; Kim, Jin Kuk

2013-01-01

Highlights: ► A (90:10) blend of CIIR and ENR by weight was used as the base. ► Different process oil and ZnO were used to optimize the gas barrier property. ► The minimum oxygen permeability is obtained using sheet ZnO. - Abstract: In many polymer applications such as inner tire liners and fuel hoses, imparting excellent gas barrier property is of prime importance. Researches in this direction had been done based on a judicious choice of polymer type or a blend thereof and the compounding ingredients. Though butyl rubber has been the polymer of choice because of its excellent gas barrier property, yet researches were targeted to improve the same with further modification in the polymer type and variation in compounding ingredients. In this study, a (90:10) blend of chlorobutyl rubber (CIIR) and Epoxdised Natural Rubber (ENR) by weight was used as the base. Four different types of process oil and three different types of zinc oxide (ZnO) at fixed predetermined concentrations were used to optimize the gas barrier and mechanical properties. In this blend, recycled aromatic oil (RAE) and sheet zinc oxide were effective in imparting the best overall combination of properties. Scanning Electron Microscopic (SEM) studies of ZnO were done to understand the structure property relationship

RELATION BETWEEN MECHANICAL PROPERTIES AND PYROLYSIS TEMPERATURE OF PHENOL FORMALDEHYDE RESIN FOR GAS SEPARATION MEMBRANES

Directory of Open Access Journals (Sweden)

MONIKA ŠUPOVÁ

2012-03-01

Full Text Available The aim of this paper has been to characterize the relation between the pyrolysis temperature of phenol-formaldehyde resin, the development of a porous structure, and the mechanical properties for the application of semipermeable membranes for gas separation. No previous study has dealt with this problem in its entirety. Phenol-formaldehyde resin showed an increasing trend toward micropore porosity in the temperature range from 500 till 1000°C, together with closure of mesopores and macropores. Samples cured and pyrolyzed at 1000°C pronounced hysteresis of desorption branch. The ultimate bending strength was measured using a four-point arrangement that is more suitable for measuring of brittle materials. The chevron notch technique was used for determination the fracture toughness. The results for mechanical properties indicated that phenol-formaldehyde resin pyrolyzates behaved similarly to ceramic materials. The data obtained for the material can be used for calculating the technical design of gas separation membranes.

Buffer gas cooling of ions stored in an R.F. trap: Computed properties of the ionic cloud

International Nuclear Information System (INIS)

Alili, A.; Andre, J.; Vedel, F.

1988-01-01

The spatial and energetic properties of an ion cloud confined in an RF quadrupole trap, together with the lifetimes of the confined ions, have been computed by statistical methods and recently by a simulation method. The influences of different parameters such as ion mass, buffer gas mass, working point in the stability diagram, 'weak' space-charge and shape of the velocity distribution of the cooling buffer gas have been investigated and are described. (orig.)

The properties of the gas around beta Pictoris

Science.gov (United States)

Roberge, A.

2014-09-01

Debris disks are often described as gas-free. Compared to protoplanetary disks, they do in general have low gas abundances, as evidenced by the very few detections of sub-mm CO emission from bona fide debris disks to date. However, some debris disks do contain low levels of detectable gas, typically seen in absorption against the stellar spectrum at UV and optical wavelengths. Of all debris disks, the gas in the Beta Pic disk is the best characterized and understood. Here, I describe those characteristics and explain our current understanding of the nature of the gas. Like the dust, the gas is secondary material coming from planetesimal destruction, and provides opportunities for sensitive probes of the bulk composition of young planetary bodies. The gas can also be a sensitive tracer of disk asymmetries and dynamical interactions, as shown by new ALMA observations of CO emission from Beta Pic (see attached infographic and YouTube video explaining the discovery). Very likely, every debris disk contains its due portion of gas, but how much that is, we do not yet know. We are poised to answer this question with the advent of ALMA. With its unprecedented sensitivity and spatial resolution, ALMA may usher in a golden age for general studies of debris gas.

Effect of Film Thickness and Physical Aging on “Intrinsic” Gas Permeation Properties of Microporous Ethanoanthracene-Based Polyimides

KAUST Repository

Ma, Xiaohua

2018-01-31

Two ethanoanthracene-based dianhydrides, 9,10-dimethylethanoanthracene-2,3,6,7-tetracarboxylic anhydride (EA-DA) and its more flexible dibenzodioxane-containing derivative (EAD-DA), were synthesized from the same starting material, 9,10-dimethyl-ethanoanthracene-2,3,6,7-tetraol, and used for the preparation of bicyclic intrinsically microporous polyimides (PIM-PIs) by one-pot polycondensation reaction with 3,3′-dimethylnaphthidine (DMN). The resulting organosoluble polyimides, EA-DMN and EAD-DMN, were thermally stable up to 300 °C and had good mechanical properties with tensile strength of 55 and 63 MPa and elongation at break of 15 and 30%, respectively. EA-DMN and EAD-DMN polyimides displayed Brunauer–Emmett–Teller (BET) surface areas of 720 and 800 m2 g–1, respectively. Fresh films showed promising gas separation performance with very high gas permeabilities and moderate gas-pair selectivities, which were both strongly dependent on film thickness. The results obtained in this study shed more light on the relative importance of film thickness and physical aging on faster attainment of the “intrinsic” gas transport properties of high free volume PIM-PIs.

Gas Sensing Properties of Ordered Mesoporous SnO2

Directory of Open Access Journals (Sweden)

Michael Tiemann

2006-04-01

Full Text Available We report on the synthesis and CO gas-sensing properties of mesoporoustin(IV oxides (SnO2. For the synthesis cetyltrimethylammonium bromide (CTABr wasused as a structure-directing agent; the resulting SnO2 powders were applied as films tocommercially available sensor substrates by drop coating. Nitrogen physisorption showsspecific surface areas up to 160 m2·g-1 and mean pore diameters of about 4 nm, as verifiedby TEM. The film conductance was measured in dependence on the CO concentration inhumid synthetic air at a constant temperature of 300 °C. The sensors show a high sensitivityat low CO concentrations and turn out to be largely insensitive towards changes in therelative humidity. We compare the materials with commercially available SnO2-basedsensors.

A Review on Graphene-Based Gas/Vapor Sensors with Unique Properties and Potential Applications

Institute of Scientific and Technical Information of China (English)

Tao Wang; Da Huang; Zhi Yang; Shusheng Xu; Guili He; Xiaolin Li; Nantao Hu; Guilin Yin; Dannong He; Liying Zhang

2016-01-01

Graphene-based gas/vapor sensors have attracted much attention in recent years due to their variety of structures, unique sensing performances, room-temperature working conditions, and tremendous application prospects, etc.Herein, we summarize recent advantages in graphene preparation, sensor construction, and sensing properties of various graphene-based gas/vapor sensors, such as NH3, NO2, H2, CO, SO2, H2S, as well as vapor of volatile organic compounds.The detection mechanisms pertaining to various gases are also discussed. In conclusion part, some existing problems which may hinder the sensor applications are presented. Several possible methods to solve these problems are proposed, for example, conceived solutions, hybrid nanostructures, multiple sensor arrays, and new recognition algorithm.

Acetylene Gas-Sensing Properties of Layer-by-Layer Self-Assembled Ag-Decorated Tin Dioxide/Graphene Nanocomposite Film

OpenAIRE

Jiang, Chuanxing; Zhang, Dongzhi; Yin, Nailiang; Yao, Yao; Shaymurat, Talgar; Zhou, Xiaoyan

2017-01-01

This paper demonstrates an acetylene gas sensor based on an Ag-decorated tin dioxide/reduced graphene oxide (Ag–SnO2/rGO) nanocomposite film, prepared by layer-by-layer (LbL) self-assembly technology. The as-prepared Ag–SnO2/rGO nanocomposite was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectrum. The acetylene sensing properties were investigated using different working temperatures and gas concentrations. A...

Room temperature H2S gas sensing property of indium oxide thin films obtained by pulsed D.C. magnetron sputtering

International Nuclear Information System (INIS)

Nisha, R.; Madhusoodanan, K.N.; Karthikeyan, Sreejith; Hill, Arthur E.; Pilkington, Richard D.

2013-01-01

Indium oxide thin films were prepared by pulsed dc magnetron sputtering technique with no substrate heating. X-ray diffraction was used to investigate the structural properties and AFM was used to study the surface morphology gas sensing performance were conducted using a static gas sensing system. Room temperature gas sensing performance was conducted in range of 17 to 286 ppm. The sensitivity, response and recovery time of the sensor was also determined. (author)

Stability and electronic structure of carbon capsules with superior gas storage properties: A theoretical study

International Nuclear Information System (INIS)

Manna, Arun K.; Pati, Swapan K.

2013-01-01

Highlights: • Stability and electronic structure of various carbon capsules are studied. • Effects of capsule’s sizes on electronic and optical properties are explored. • Changes in cohesive and formation energy and electronic gap are discussed. • Capsule’s gas storage propensity is addressed using DFT and ab initio MD. • Capsule’s optical absorptions are discussed with and without stored gas molecules. - Abstract: Structures, electronic and optical properties of carbon nanocapsules of varying sizes (length and diameter) are studied using first-principles density functional theory. Based on calculated cohesive energy, formation energy, electronic gap and extent of orbital delocalization, we examine structural stability and changes in low-energy physics of these carbon capsules. We find that both cohesive and formation energy decrease with increase in capsule’s sizes, indicating their greater structural rigidity and favorable formation feasibility. The electronic gap also decreases with increase in capsule’s sizes due to the larger electronic delocalization. The simulated optical absorption spectra show lowering of low-energy peak positions with increase in the capsule’s dimensions, consistent with the reduction in electronic gap. Additionally, we also provide an estimate of gas storage capacity for the larger carbon capsule (C 460 ) considered. We find 7.69 wt.% and 28.08 wt.% storage propensity for hydrogen and carbon dioxide gases, respectively, which clearly suggests their potential use as light storage materials

Normalization of natural gas composition data measured by gas chromatography

International Nuclear Information System (INIS)

Milton, Martin J T; Harris, Peter M; Brown, Andrew S; Cowper, Chris J

2009-01-01

The composition of natural gas determined by gas chromatography is routinely used as the basis for calculating physico-chemical properties of the gas. Since the data measured by gas chromatography have particular statistical properties, the methods used to determine the composition can make use of a priori assumptions about the statistical model for the data. We discuss a generalized approach to determining the composition, and show that there are particular statistical models for the data for which the generalized approach reduces to the widely used method of post-normalization. We also show that the post-normalization approach provides reasonable estimates of the composition for cases where it cannot be shown to arise rigorously from the statistical structure of the data

Galaxy pairs in the SDSS - XIII. The connection between enhanced star formation and molecular gas properties in galaxy mergers

Science.gov (United States)

Violino, Giulio; Ellison, Sara L.; Sargent, Mark; Coppin, Kristen E. K.; Scudder, Jillian M.; Mendel, Trevor J.; Saintonge, Amelie

2018-05-01

We investigate the connection between star formation and molecular gas properties in galaxy mergers at low redshift (z ≤ 0.06). The study we present is based on IRAM 30-m CO(1-0) observations of 11 galaxies with a close companion selected from the Sloan Digital Sky Survey (SDSS). The pairs have mass ratios ≤4, projected separations rp ≤ 30 kpc and velocity separations ΔV ≤ 300 km s-1, and have been selected to exhibit enhanced specific star formation rates (sSFRs). We calculate molecular gas (H2) masses, assigning to each galaxy a physically motivated conversion factor αCO, and we derive molecular gas fractions and depletion times. We compare these quantities with those of isolated galaxies from the extended CO Legacy Data base for the GALEX Arecibo SDSS Survey sample (xCOLDGASS; Saintonge et al.) with gas quantities computed in an identical way. Ours is the first study which directly compares the gas properties of galaxy pairs and those of a control sample of normal galaxies with rigorous control procedures and for which SFR and H2 masses have been estimated using the same method. We find that the galaxy pairs have shorter depletion times and an average molecular gas fraction enhancement of 0.4 dex compared to the mass matched control sample drawn from xCOLDGASS. However, the gas masses (and fractions) in galaxy pairs and their depletion times are consistent with those of non-mergers whose SFRs are similarly elevated. We conclude that both external interactions and internal processes may lead to molecular gas enhancement and decreased depletion times.

Sensing Properties of Pd-Loaded Co3O4 Film for a ppb-Level NO Gas Sensor

Directory of Open Access Journals (Sweden)

Takafumi Akamatsu

2015-04-01

Full Text Available We prepared 0.1 wt%–30 wt% Pd-loaded Co3O4 by a colloidal mixing method and investigated the sensing properties of a Pd-loaded Co3O4 sensor element, such as the sensor response, 90% response time, 90% recovery time, and signal-to-noise (S/N ratio, toward low nitric oxide (NO gas levels in the range from 50 to 200 parts per billion. The structural properties of the Pd-loaded Co3O4 powder were investigated using X-ray diffraction analysis and transmission electron microscopy. Pd in the powder existed as PdO. The sensor elements with 0.1 wt%–10 wt% Pd content have higher sensor properties than those without any Pd content. The response of the sensor element with a 30 wt% Pd content decreased markedly because of the aggregation and poor dispersibility of the PdO particles. High sensor response and S/N ratio toward the NO gas were achieved when a sensor element with 10 wt% Pd content was used.

The times are a-changin': Online A and D of oil and gas properties finds its niche

International Nuclear Information System (INIS)

Pelczer, S.

2003-01-01

The emerging on-line market place for the buying and selling of oil and gas properties, or 'A and D' (acquisitions and divestitures) as it is known in industry circles is discussed. Online marketing is said to have replaced the large amounts of data that accompanies the sale of properties, such as the engineering reports, seismic studies, and reserve reports, along with the inevitable confidentiality agreements and legal documentation, all consuming a lot space, time and money. ProspectOasis, a global trading platform that showcases marketable oil and gas prospects and production properties to facilitate acquisition and divestiture replaces the traditional physical data room used in the past to store transaction-dependent data with an online Web-enabled data room. ProspectOasis enables the seller to create a virtual data room in cyberspace: by providing access to the same interpretation software and data used to create the original evaluation of the asset data, it saves time by eliminating the need for the purchaser to visit a traditional data room set-up

Zigzag GaN/Ga2O3 heterogeneous nanowires: Synthesis, optical and gas sensing properties

Directory of Open Access Journals (Sweden)

Li-Wei Chang

2011-09-01

Full Text Available Zigzag GaN/Ga2O3 heterogeneous nanowires (NWs were fabricated, and the optical properties and NO gas sensing ability of the NWs were investigated. We find that NWs are most effective at 850 °C at a switching process once every 10 min (on/off = 10 min per each with a mixture flow of NH3 and Ar. The red shift of the optical bandgap (0.66 eV is observed from the UV-vis spectrum as the GaN phase forms. The gas sensing characteristics of the developed sensor are significantly replaced to those of other types of NO sensors reported in literature.

Trends in the analysis of natural gas by capillary gas chromatography

NARCIS (Netherlands)

Cramers, C.A.M.G.; Rossum, van G.J.

1986-01-01

The importance of correct determination of physical and chemical properties of natural gas is evident. The calculation of calorific value or hydrocarbon dew point requires detailed analysis as can be provided by gas chromatography. Analysis by gas chromatography is a necessary complement to direct

Chandra Studies of the X-ray gas properties of fossil systems

International Nuclear Information System (INIS)

Qin, Zhen-Zhen

2016-01-01

We study ten galaxy groups and clusters suggested in the literature to be “fossil systems (FSs)” based on Chandra observations. According to the M 500 − T and L X − T relations, the gas properties of FSs are not physically distinct from ordinary galaxy groups or clusters. We also first study the f gas, 2500 − T relation and find that the FSs exhibit the same trend as ordinary systems. The gas densities of FSs within 0.1r 200 are ∼ 10 −3 cm −3 , which is the same order of magnitude as galaxy clusters. The entropies within 01r 200 (S 0.1r200 ) of FSs are systematically lower than those inordinary galaxy groups, which is consistent with previous reports, but we find their S 0.1r200 − T relation is more similar to galaxy clusters. The derived mass profiles of FSs are consistent with the Navarro, Frenk and White model in (0.1 − 1)r 200 , and the relation between scale radius r s and characteristic mass density δ c indicates self-similarity of dark matter halos of FSs. The ranges of r s and δ c for FSs are also close to those of galaxy clusters. Therefore, FSs share more common characteristics with galaxy clusters. The special birth place of the FS makes it a distinct type of galaxy system. (paper)

Comparison of GERG-2008 and simpler EoS models in calculation of phase equilibrium and physical properties of natural gas related systems

DEFF Research Database (Denmark)

Varzandeh, Farhad; Stenby, Erling Halfdan; Yan, Wei

2017-01-01

Accurate description of thermodynamic properties of natural gas systems is of great significance in the oil and gas industry. For this application, non-cubic equations of state (EoSs) are advantageous due to their better density and compressibility description. Among the non-cubic models, GERG-2008...... is a new wide-range EoS for natural gases and other mixtures of 21 natural gas components. It is considered as a standard reference equation suitable for natural gas applications where highly accurate thermodynamic properties are required. Soave's modification of Benedict-Webb-Rubin (Soave-BWR) Eo......S is another model that despite its empirical nature, provides accurate density description even around the critical point. It is much simpler than GERG-2008 and easier to handle and generalize to reservoir oil fluids. This study presents a comprehensive comparison between GERG-2008 and other cubic (SRK and PR...

Gas response properties of citrate gel synthesized nanocrystalline MgFe2O4: Effect of sintering temperature

International Nuclear Information System (INIS)

Patil, J.Y.; Mulla, I.S.; Suryavanshi, S.S.

2013-01-01

Graphical abstract: Display Omitted Highlights: ► Synthesis of nanocrystalline MgFe 2 O 4 by economical citrate gel combustion method. ► Structural, morphological, and gas response properties of MgFe 2 O 4 . ► Enhancement in selectivity of MgFe 2 O 4 towards LPG with sintering temperature. ► Use of MgFe 2 O 4 to detect different gases at different operating temperatures. -- Abstract: Spinel type MgFe 2 O 4 material was synthesized by citrate gel combustion method. The effect of sintering temperature on structural, morphological, and gas response properties was studied. The powder X-ray diffraction pattern and transmission electron microscope study confirms nanocrystalline spinel structure of the synthesized powder. The material was tested for response properties to various reducing gases like liquid petroleum gas (LPG), acetone, ethanol, and ammonia. The results demonstrated n-type semiconducting behavior of MgFe 2 O 4 material. It was revealed that MgFe 2 O 4 sintered at 973 K was most sensitive to LPG at 648 K and to acetone at 498 K. However MgFe 2 O 4 sintered at 1173 K exhibited higher response and selectivity to LPG with marginal increase in the operating temperature. Furthermore, the sensor exhibited a fast response and a good recovery. It was observed that the particles size, porosity, and surface activity of the sensor material is affected by the sintering temperature.

A Principle Component Analysis of Galaxy Properties from a Large, Gas-Selected Sample

Directory of Open Access Journals (Sweden)

Yu-Yen Chang

2012-01-01

concluded that this is in conflict with the CDM model. Considering the importance of the issue, we reinvestigate the problem using the principal component analysis on a fivefold larger sample and additional near-infrared data. We use databases from the Arecibo Legacy Fast Arecibo L-band Feed Array Survey for the gas properties, the Sloan Digital Sky Survey for the optical properties, and the Two Micron All Sky Survey for the near-infrared properties. We confirm that the parameters are indeed correlated where a single physical parameter can explain 83% of the variations. When color (g-i is included, the first component still dominates but it develops a second principal component. In addition, the near-infrared color (i-J shows an obvious second principal component that might provide evidence of the complex old star formation. Based on our data, we suggest that it is premature to pronounce the failure of the CDM model and it motivates more theoretical work.

Synthesis, Characterization and Gas Sensing Properties of Ag@α-Fe2O3 Core–Shell Nanocomposites

Directory of Open Access Journals (Sweden)

Ali Mirzaei

2015-05-01

Full Text Available Ag@α-Fe2O3 nanocomposite having a core–shell structure was synthesized by a two-step reduction-sol gel approach, including Ag nanoparticles synthesis by sodium borohydride as the reducing agent in a first step and the subsequent mixing with a Fe+3 sol for α-Fe2O3 coating. The synthesized Ag@α-Fe2O3 nanocomposite has been characterized by various techniques, such as SEM, TEM and UV-Vis spectroscopy. The electrical and gas sensing properties of the synthesized composite towards low concentrations of ethanol have been evaluated. The Ag@α-Fe2O3 nanocomposite showed better sensing characteristics than the pure α-Fe2O3. The peculiar hierarchical nano-architecture and the chemical and electronic sensitization effect of Ag nanoparticles in Ag@α-Fe2O3 sensors were postulated to play a key role in modulating gas-sensing properties in comparison to pristine α-Fe2O3 sensors.

THE ROLE OF SHIELDING GAS ON MECHANICAL, METALLURGICAL AND CORROSION PROPERTIES OF CORTEN STEEL WELDED JOINTS OF RAILWAY COACHES USING GMAW

Directory of Open Access Journals (Sweden)

Byju John

2016-12-01

Full Text Available This analysis lays emphasis on finding a suitable combination of shielding gas for welding underframe members such as sole bar of Railway Coaches made of corten steel; for improved mechanical, metallurgical and corrosion properties of welds using copper coated solid MIG/MAG welding filler wire size 1.2 mm conforming to AWS/SFA 5.18 ER 70 S in Semi-automatic GMAW process. Solid filler wire is preferred by welders due to less fumes, practically no slag and easy manipulation of welding torch with smooth wire flow during corrosion repair attention, when compared to Flux cored wire. Three joints using Gas metal arc welding (GMAW with shielding gases viz., Pure CO2, (80% Ar – 20% CO2 and (90% Ar – 10% CO2 were made from test pieces cut from Sole bar material of Railway Coach. Study of Mechanical properties such as tensile strength, hardness and toughness revealed that welded joint made using shielding gas (80% Ar – 20% CO2 has better Mechanical properties compared to the other two shielding gases and comparable to that of Parent metal. Type of Shielding gas used has influence on the chemical composition and macro & micro structures. The Tafel extrapolation study of freshly ground samples in 3.5% NaCl solution revealed that the welded joint made using shielding gas (80% Ar – 20% CO2 has also better corrosion resistance which is comparable to the Parent metal as well as similar commercial steels.

Development of the first coal seam gas exploration program in Indonesia: Reservoir properties of the Muaraenim Formation, south Sumatra

Energy Technology Data Exchange (ETDEWEB)

Sosrowidjojo, I.B. [R and D Centre for Oil and Gas Technology, LEMIGAS, Jakarta (Indonesia); Saghafi, A. [CSIRO Energy Technology, P O Box 330, Newcastle, NSW, 2300 (Australia)

2009-09-01

The Late Miocene Muaraenim Formation in southern Sumatra contains thick coal sequences, mostly of low rank ranging from lignite to sub-bituminous, and it is believed that these thick low rank coals are the most prospective for the production of coal seam gas (CSG), otherwise known as coalbed methane (CBM), in Indonesia. As part of a major CSG exploration project, gas exploration drilling operations are being undertaken in Rambutan Gasfields in the Muaraenim Formation to characterize the CSG potential of the coals. The first stage of the project, which is described here, was designed to examine the gas reservoir properties with a focus on coal gas storage capacity and compositional properties. Some five CSG exploration boreholes were drilled in the Rambutan Gasfield, south of Palembang. The exploration boreholes were drilled to depths of {proportional_to} 1000 m into the Muaraenim Formation. Five major coal seams were intersected by these holes between the depths of 450 and 1000 m. The petrography of coal samples collected from these seams showed that they are vitrinite rich, with vitrinite contents of more than 75% (on a mineral and moisture free basis). Gas contents of up to 5.8 m{sup 3}/t were measured for the coal samples. The gas desorbed from coal samples contain mainly methane (CH{sub 4}) ranging from 80 to 93% and carbon dioxide (CO{sub 2}) ranging from 6 to 19%. The composition of the gas released into the production borehole/well is, however, much richer in CH{sub 4} with about 94 to 98% CH{sub 4} and less than 5% CO{sub 2}. The initial results of drilling and reservoir characterization studies indicate suitable gas recovery parameters for three of the five coal seams with a total thickness of more than 30 m. (author)

Effect of damage on water retention and gas transport properties geo-materials: Application to geological storage of radioactive waste

International Nuclear Information System (INIS)

M'Jahad, S.

2012-01-01

In the context of geological disposal of radioactive waste, this work contributes to the characterization of the effect of diffuse damage on the water retention and gas transfer properties of concrete (CEM I and CEM V) selected by Andra, Callovo-Oxfordian argillite (host rock) and argillite / concrete interfaces. This study provides information on the concrete microstructure from Mercury porosimetry intrusion and water retention curves: each concrete has a distinct microstructure, CEM I concrete is characterized by a significant proportion of capillary pores while CEM V concrete has a large proportion of C-S-H pores. Several protocols have been developed in order to damage concrete. The damage reduces water retention capacity of CEM I concrete and increases its gas permeability. Indeed, gas breakthrough pressure decreases significantly for damaged concrete, and this regardless of the type of concrete. For argillite, the sample mass increases gradually at RH = 100%, which creates and increases damage in the material. This reduces its ability to retain water. Otherwise, water retention and gas transport properties of argillite are highly dependent of its initial water saturation, which is linked to its damage. Finally, we observed a clogging phenomenon at the argillite/concrete interfaces, which is first mechanical and then hydraulic (and probably chemical) after water injection. This reduces the gas breakthrough pressure interfaces. (author)

A first-principles study on gas sensing properties of graphene and Pd-doped graphene

International Nuclear Information System (INIS)

Ma, Ling; Zhang, Jian-Min; Xu, Ke-Wei; Ji, Vincent

2015-01-01

Graphical abstract: - Highlights: • Optimized configurations for CO, NH 3 , O 2 and NO 2 adsorbed on PG ((a)–(d)) and Pd-G ((e)–(h)). The green, red, orange and blue balls represent the carbon, oxygen, nitrogen and palladium atoms, respectively. • Sensitivity of PG and Pd-G toward CO, NH 3 , O 2 and NO 2 has been investigated. • Pd dopants enhance interaction of gas molecules with the Pd-G sheet. • The electrical conductivity of Pd-G dramatically changes after gas adsorption. • Pd-G is more suitable for gas molecules detection compared with PG. - Abstract: Sensitivity of pristine graphene (PG) and Pd-doped graphene (Pd-G) toward a series of small gas molecules (CO, NH 3 , O 2 and NO 2 ) has been investigated by first-principles based on density functional theory (DFT). The most stable adsorption configuration, adsorption energy, charge transfer, density of states and magnetic moment of these molecules on PG and Pd-G are thoroughly discussed. It is found that four gas molecules are weakly adsorbed on PG with low adsorption energy of 0.08–0.24 eV, and the electronic properties of PG are only sensitive to the presence of O 2 and NO 2 molecules. In contrast, doping graphene with Pd dopants significantly enhances the strength of interaction between adsorbed molecules and the modified substrate. The dramatically increased adsorption energy and charge transfer of these systems are expected to induce significant changes in the electrical conductivity of the Pd-G sheet. The results reveals that the sensitivity of graphene-based chemical gas sensors could be drastically improved by introducing the Pd dopants, so Pd-G is more suitable for gas molecules detection compared with PG

A pair of polymorphous metal-organic frameworks based on an angular diisophthalate linker: synthesis, characterization and gas adsorption properties.

Science.gov (United States)

Chen, Fengli; Bai, Dongjie; Wang, Yao; He, Minghui; Gao, Xiaoxia; He, Yabing

2018-01-15

The combination of an angular diisophthalate ligand, 5,5'-(naphthyl-2,7-yl)diisophthalate (H 4 L), and copper ions under different solvothermal conditions afforded two polymorphous metal-organic frameworks (ZJNU-77 and ZJNU-78) with the same framework composition of [Cu 2 (L)(H 2 O) 2 ], providing a platform to investigate the relationship between MOF polymorphism and gas adsorption properties. As determined by single-crystal X-ray diffraction, ZJNU-77 and ZJNU-78 exhibited three-dimensional networks crystallizing in different space groups. Their structural differences were mainly manifested by the ligand's conformation, the level of framework interpenetration and the network's topology. Interestingly, gas adsorption studies showed that the two compounds after desolvation displayed comparable gas adsorption properties with respect to C 2 H 2 , CO 2 and CH 4 , despite their different surface areas and pore volumes. The C 2 H 2 , CO 2 , and CH 4 uptake capacities at 298 K and 1 atm are 120.2, 78.1, and 18.4 cm 3 (STP) g -1 for ZJNU-77, and 122.0, 82.0, and 18.9 cm 3 (STP) g -1 for ZJNU-78, respectively. The IAST adsorption selectivities for the equimolar C 2 H 2 /CH 4 and CO 2 /CH 4 mixtures are 28.6 and 5.7 for ZJNU-77, and 28.4 and 5.9 for ZJNU-78 at 298 K and 1 atm. These results indicate that besides the surface area, the pore size also plays a crucial role in gas adsorption. This work not only represents an intriguing example of MOF polymorphism achieved by controlling solvothermal conditions, but also provides an insight into the correlation between MOF polymorphism and gas adsorption properties.

Finite-Size Scaling in a Two-Temperature Lattice Gas: a Monte Carlo Study of Critical Properties

DEFF Research Database (Denmark)

Larsen, Heine; Præstgaard, Eigil; Zia, R.K.P.

1994-01-01

We present computer studies of the critical properties of an Ising lattice gas driven to a non-equilibrium steady state by coupling to two temperature baths. Anisotropic scaling, a dominant feature near criticality, is used as a tool to extract the values of the critical temperature and some expo...

Simultaneous high-speed gas property measurements at the exhaust gas recirculation cooler exit and at the turbocharger inlet of a multicylinder diesel engine using diode-laser-absorption spectroscopy.

Science.gov (United States)

Jatana, Gurneesh S; Magee, Mark; Fain, David; Naik, Sameer V; Shaver, Gregory M; Lucht, Robert P

2015-02-10

A diode-laser-absorption-spectroscopy-based sensor system was used to perform high-speed (100 Hz to 5 kHz) measurements of gas properties (temperature, pressure, and H(2)O vapor concentration) at the turbocharger inlet and at the exhaust gas recirculation (EGR) cooler exit of a diesel engine. An earlier version of this system was previously used for high-speed measurements of gas temperature and H(2)O vapor concentration in the intake manifold of the diesel engine. A 1387.2 N m tunable distributed feedback diode laser was used to scan across multiple H(2)O absorption transitions, and the direct absorption signal was recorded using a high-speed data acquisition system. Compact optical connectors were designed to conduct simultaneous measurements in the intake manifold, the EGR cooler exit, and the turbocharger inlet of the engine. For measurements at the turbocharger inlet, these custom optical connectors survived gas temperatures as high as 800 K using a simple and passive arrangement in which the temperature-sensitive components were protected from high temperatures using ceramic insulators. This arrangement reduced system cost and complexity by eliminating the need for any active water or oil cooling. Diode-laser measurements performed during steady-state engine operation were within 5% of the thermocouple and pressure sensor measurements, and within 10% of the H(2)O concentration values derived from the CO(2) gas analyzer measurements. Measurements were also performed in the engine during transient events. In one such transient event, where a step change in fueling was introduced, the diode-laser sensor was able to capture the 30 ms change in the gas properties; the thermocouple, on the other hand, required 7.4 s to accurately reflect the change in gas conditions, while the gas analyzer required nearly 600 ms. To the best of our knowledge, this is the first implementation of such a simple and passive arrangement of high-temperature optical connectors as well

Optical properties of wet paper and simulation of the effect of autoprofiling on gas-fired IR drying

Energy Technology Data Exchange (ETDEWEB)

Ojala, K T; Lampinen, M J

1991-01-01

We have developed new models to determine the radiative heat transfer of gas-fired infrared dryers. A computer program based on the mathematical models is developed further. This program is used for studying the autoprofiling effect in gas-fired infrared drying. Optical properties of paper samples of different moisture contents as a function of wavelength are systematically measured by using FT-lR specrometer and integraing sphere techniques. These measurements covered the moisture content range of 6- 150 %. A new wavelength range (1.2- 1.9 mm), not properly covered by our earlier measurements, is measured by using a liquid nitrogen cooled detector. The total measured wavelength range is 1.0-20.0 mm. The moisture dependence of the optical properties of coating are calculated by using a theoretical model developed in State Research Centre of Finland, Laboratory of Optoelectronics. The radiation properties of component surfaces of the IR dryer were either measured or taken from literature. The mathematical models are based on the calculation of radiation energy balance between the main surfaces and layers in the dryer section. The energy efficiency can be calculated, when the temperatures of the radiator and the optical properties of all parts of the dryer are known. A computer program based on the models is developed further. The dryer efficiency as a function of the moisture content of paper is calculated. The extent of the autoprofiling effect in gas-fired IR drying is hereby achieved for light weight coated paper web. If the variation in moisture contents is high, the autoprofiling effect takes place and reduces the moisture variation. However, if the moisture variation is low, it is not a very significant phenomenon. The simulation results are compared to a pilot coater trial made in Cenre Technique du Papier, Grenoble.

Effect of Alternate Supply of Shielding Gases of Tungsten Inert Gas Welding on Mechanical Properties of Austenitic Stainless Steel

Science.gov (United States)

Shinde, Neelam Vilas; Telsang, Martand Tamanacharya

2016-07-01

In the present study, an attempt is made to study the effect of alternate supply of the shielding gas in comparison with the conventional method of TIG welding with pure argon gas. The two sets of combination are used as 10-10 and 40-20 s for alternate supply of the Argon and Helium shielding gas respectively. The effect of alternate supply of shielding gas is studied on the mechanical properties like bend test, tensile test and impact test. The full factorial experimental design is applied for three set of combinations. The ANOVA is used to find significant parameters for the process and regression analysis used to develop the mathematical model. The result shows that the alternate supply of the shielding gas for 10-10 s provides better result for the bend, tensile and impact test as compared with the conventional argon gas and the alternate supply of 40-20 s argon and helium gas respectively. Welding speed can be increased for alternate supply of the shielding gas that can reduce the total welding cost.

Gas Permeation and Physical Aging Properties of Iptycene Diamine-Based Microporous Polyimides

KAUST Repository

Alghunaimi, Fahd

2015-05-12

The synthesis and gas permeation properties of two 6FDA-dianhydride-based polyimides prepared from 2,6-diaminotriptycene (6FDA-DAT1) and its extended iptycene analog (6FDA-DAT2) are reported. The additional benzene ring on the extended triptycene moiety in 6FDA–DAT2 increases the free volume over 6FDA-DAT1 and reduces the chain packing efficiency. The BET surface area based on nitrogen adsorption in 6FDA-DAT2 (450 m2g−1) is ~40% greater than that of 6FDA-DAT1 (320 m2g−1). 6FDA-DAT1 shows a CO2 permeability of 120 Barrer and CO2/CH4 selectivity of 38, whereas 6FDA-DAT2 exhibits a 75% increase in CO2 permeability to 210 Barrer coupled with a moderate decrease in selectivity (CO2/CH4=30). Interestingly, minimal physical aging was observed over 150 days for both polymers and attributed to the high internal free volume of the shape-persistent iptycene geometries. The aged polyimides maintained CO2/CH4 selectivities of 25-35 along with high CO2 permeabilities of 90-120 Barrer up to partial CO2 pressures of 10 bar of an aggressive 50:50 CO2:CH4 mixed-gas feed, suggesting potential application in membranes for natural gas sweetening.

Gas Permeation and Physical Aging Properties of Iptycene Diamine-Based Microporous Polyimides

KAUST Repository

Alghunaimi, Fahd; Ghanem, Bader; Alaslai, Nasser Y.; Swaidan, Raja; Litwiller, Eric; Pinnau, Ingo

2015-01-01

The synthesis and gas permeation properties of two 6FDA-dianhydride-based polyimides prepared from 2,6-diaminotriptycene (6FDA-DAT1) and its extended iptycene analog (6FDA-DAT2) are reported. The additional benzene ring on the extended triptycene moiety in 6FDA–DAT2 increases the free volume over 6FDA-DAT1 and reduces the chain packing efficiency. The BET surface area based on nitrogen adsorption in 6FDA-DAT2 (450 m2g−1) is ~40% greater than that of 6FDA-DAT1 (320 m2g−1). 6FDA-DAT1 shows a CO2 permeability of 120 Barrer and CO2/CH4 selectivity of 38, whereas 6FDA-DAT2 exhibits a 75% increase in CO2 permeability to 210 Barrer coupled with a moderate decrease in selectivity (CO2/CH4=30). Interestingly, minimal physical aging was observed over 150 days for both polymers and attributed to the high internal free volume of the shape-persistent iptycene geometries. The aged polyimides maintained CO2/CH4 selectivities of 25-35 along with high CO2 permeabilities of 90-120 Barrer up to partial CO2 pressures of 10 bar of an aggressive 50:50 CO2:CH4 mixed-gas feed, suggesting potential application in membranes for natural gas sweetening.

Gas-sensing properties of SnO2-TiO2-based sensor for volatile organic compound gas and its sensing mechanism

International Nuclear Information System (INIS)

Zeng Wen; Liu Tianmo

2010-01-01

We report the microstructure and gas-sensing properties of the SnO 2 -TiO 2 composite oxide dope with Ag ion prepared by the sol-gel method. Of all various volatile organic compounds (VOCs) such as ethanol, methanol, acetone and formaldehyde were examined, the sensor exhibits remarkable selectivity to each VOCs at different operating temperature. Further investigations based on quantum chemistry calculation show that difference orbital energy of VOCs molecule may be a qualitative factor to affect the selectivity of the sensor.

Effect of Channel Geometry and Properties of a Vapor-Gas Mixture on Volume Condensation in a Flow through a Nozzle

Science.gov (United States)

Sidorov, A. A.; Yastrebov, A. K.

2018-01-01

A method of direct numerical solution of the kinetic equation for the droplet size distribution function was used for the numerical investigation of volume condensation in a supersonic vapor-gas flow. Distributions of temperature for the gas phase and droplets, degree of supersaturation, pressure, fraction of droplets by weight, the number of droplets per unit mass, and of the nucleation rate along the channel were determined. The influence of nozzle geometry, mixture composition, and temperature dependence of the mixture properties on the investigated process was evaluated. It has been found that the nozzle divergence angle determines the vapor-gas mixture expansion rate: an increase in the divergence angle enhances the temperature decrease rate and the supersaturation degree raise rate. With an increase or decrease in the partial pressure of incondensable gas, the droplet temperature approaches the gas phase temperature or the saturation temperature at the partial gas pressure, respectively. A considerable effect of the temperature dependence of the liquid surface tension and properties on gas phase parameters and the integral characteristics of condensation aerosol was revealed. However, the difference in results obtained with or without considering the temperature dependence of evaporation heat is negligible. The predictions are compared with experimental data of other investigations for two mixtures: a mixture of heavy water vapor with nitrogen (incondensable gas) or n-nonane vapor with nitrogen. The predictions agree quite well qualitatively and quantitatively with the experiment. The comparison of the predictions with numerical results from other publications obtained using the method of moments demonstrates the usefulness of the direct numerical solution method and the method of moments in a wide range of input data.

Synthesis and Transport Properties of Novel MOF/PIM-1/MOF Sandwich Membranes for Gas Separation.

Science.gov (United States)

Fuoco, Alessio; Khdhayyer, Muhanned R; Attfield, Martin P; Esposito, Elisa; Jansen, Johannes C; Budd, Peter M

2017-02-11

Metal-organic frameworks (MOFs) were supported on polymer membrane substrates for the fabrication of composite polymer membranes based on unmodified and modified polymer of intrinsic microporosity (PIM-1). Layers of two different MOFs, zeolitic imidazolate framework-8 (ZIF-8) and Copper benzene tricarboxylate ((HKUST-1), were grown onto neat PIM-1, amide surface-modified PIM-1 and hexamethylenediamine (HMDA) -modified PIM-1. The surface-grown crystalline MOFs were characterized by a combination of several techniques, including powder X-ray diffraction, infrared spectroscopy and scanning electron microscopy to investigate the film morphology on the neat and modified PIM-1 membranes. The pure gas permeabilities of He, H₂, O₂, N₂, CH₄, CO₂ were studied to understand the effect of the surface modification on the basic transport properties and evaluate the potential use of these membranes for industrially relevant gas separations. The pure gas transport was discussed in terms of permeability and selectivity, highlighting the effect of the MOF growth on the diffusion coefficients of the gas in the new composite polymer membranes. The results confirm that the growth of MOFs on polymer membranes can enhance the selectivity of the appropriately functionalized PIM-1, without a dramatic decrease of the permeability.

Liquid and Gas Permeation Studies on the Structure and Properties of Polyamide Thin-Film Composite Membranes

KAUST Repository

Duan, Jintang

2014-11-01

This research was undertaken to improve the understanding of structure-property-performance relationships in crosslinked polyamide (PA) thin-film composite (TFC) membranes as characterized by liquid and gas permeation studies. The ultrathin PA selective layer formed by interfacial polymerization between meta-phenylene diamine and trimesoyl chloride was confirmed to contain dense polymer matrix regions and defective regions in both dry and hydrated states. The first part of this research studied the effect of non-selective convection through defective regions on water flux and solute flux in pressure-assisted forward osmosis (PAFO). Through systematic comparison with cellulose triacetate (CTA) and PEBAX-coated PA-TFC membranes, the existence of defects in pristine, hydrated PA-TFC membranes was verified, and their effects were quantified by experimental and modeling methods. In the membrane orientation of selective layer facing the draw solution, water flux increases of up to 10-fold were observed to result from application of low hydraulic pressure (1.25 bar). Convective water flux through the defects was low (< 1% of total water flux for PA-TFC membranes) and of little consequence in practical FO or reverse osmosis (RO) applications. However, it effectively mitigated the concentration polarization in PAFO and therefore greatly increased the diffusive flux through the dense regions. The second part of this research characterized the structures of the PA material and the PA selective layer by gas adsorption and gas permeation measurements. Gas adsorption isotherms (N2 at 77K, CO2 at 273K) confirmed the microporous nature of PA in comparison with dense CTA and polysulfone materials. Gas permeation through the commercial PA-TFC membranes tested occurred primarily in the defective regions, resulting in Knudsen gas selectivity for various gas pairs. Applying a Nafion coating layer effectively plugged the defects and allowed gas permeation through the dense PA regions

Comprehensive two-dimensional gas chromatography and food sensory properties: potential and challenges.

Science.gov (United States)

Cordero, Chiara; Kiefl, Johannes; Schieberle, Peter; Reichenbach, Stephen E; Bicchi, Carlo

2015-01-01

Modern omics disciplines dealing with food flavor focus the analytical efforts on the elucidation of sensory-active compounds, including all possible stimuli of multimodal perception (aroma, taste, texture, etc.) by means of a comprehensive, integrated treatment of sample constituents, such as physicochemical properties, concentration in the matrix, and sensory properties (odor/taste quality, perception threshold). Such analyses require detailed profiling of known bioactive components as well as advanced fingerprinting techniques to catalog sample constituents comprehensively, quantitatively, and comparably across samples. Multidimensional analytical platforms support comprehensive investigations required for flavor analysis by combining information on analytes' identities, physicochemical behaviors (volatility, polarity, partition coefficient, and solubility), concentration, and odor quality. Unlike other omics, flavor metabolomics and sensomics include the final output of the biological phenomenon (i.e., sensory perceptions) as an additional analytical dimension, which is specifically and exclusively triggered by the chemicals analyzed. However, advanced omics platforms, which are multidimensional by definition, pose challenging issues not only in terms of coupling with detection systems and sample preparation, but also in terms of data elaboration and processing. The large number of variables collected during each analytical run provides a high level of information, but requires appropriate strategies to exploit fully this potential. This review focuses on advances in comprehensive two-dimensional gas chromatography and analytical platforms combining two-dimensional gas chromatography with olfactometry, chemometrics, and quantitative assays for food sensory analysis to assess the quality of a given product. We review instrumental advances and couplings, automation in sample preparation, data elaboration, and a selection of applications.

Single-step gas phase synthesis of stable iron aluminide nanoparticles with soft magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Vernieres, Jerome, E-mail: Jerome.vernieres@oist.jp; Benelmekki, Maria; Kim, Jeong-Hwan; Grammatikopoulos, Panagiotis; Diaz, Rosa E. [Nanoparticles by Design Unit, Okinawa Institute of Science and Technology (OIST) Graduate University, 1919-1 Tancha, Onna Son, Okinawa 904-0495 (Japan); Bobo, Jean-François [Centre d’Elaboration de Materiaux et d’Etudes Structurales (CEMES), 29 rue Jeanne Marvig, 31055 Toulouse Cedex 4 (France); Sowwan, Mukhles, E-mail: Mukhles@oist.jp [Nanoparticles by Design Unit, Okinawa Institute of Science and Technology (OIST) Graduate University, 1919-1 Tancha, Onna Son, Okinawa 904-0495 (Japan); Nanotechnology Research Laboratory, Al-Quds University, P.O. Box 51000, East Jerusalem, Palestine (Country Unknown)

2014-11-01

Soft magnetic alloys at the nanoscale level have long generated a vivid interest as candidate materials for technological and biomedical purposes. Consequently, controlling the structure of bimetallic nanoparticles in order to optimize their magnetic properties, such as high magnetization and low coercivity, can significantly boost their potential for related applications. However, traditional synthesis methods stumble upon the long standing challenge of developing true nanoalloys with effective control over morphology and stability against oxidation. Herein, we report on a single-step approach to the gas phase synthesis of soft magnetic bimetallic iron aluminide nanoparticles, using a versatile co-sputter inert gas condensation technique. This method allowed for precise morphological control of the particles; they consisted of an alloy iron aluminide crystalline core (DO{sub 3} phase) and an alumina shell, which reduced inter-particle interactions and also prevented further oxidation and segregation of the bimetallic core. Remarkably, the as-deposited alloy nanoparticles show interesting soft magnetic properties, in that they combine a high saturation magnetization (170 emu/g) and low coercivity (less than 20 Oe) at room temperature. Additional functionality is tenable by modifying the surface of the particles with a polymer, to ensure their good colloidal dispersion in aqueous environments.

The times are a-changin': Online A and D of oil and gas properties finds its niche

Energy Technology Data Exchange (ETDEWEB)

Pelczer, S.

2003-11-01

The emerging on-line market place for the buying and selling of oil and gas properties, or 'A and D' (acquisitions and divestitures) as it is known in industry circles is discussed. Online marketing is said to have replaced the large amounts of data that accompanies the sale of properties, such as the engineering reports, seismic studies, and reserve reports, along with the inevitable confidentiality agreements and legal documentation, all consuming a lot space, time and money. ProspectOasis, a global trading platform that showcases marketable oil and gas prospects and production properties to facilitate acquisition and divestiture replaces the traditional physical data room used in the past to store transaction-dependent data with an online Web-enabled data room. ProspectOasis enables the seller to create a virtual data room in cyberspace: by providing access to the same interpretation software and data used to create the original evaluation of the asset data, it saves time by eliminating the need for the purchaser to visit a traditional data room set-up.

Fundamental mechanisms in flue gas conditioning

Energy Technology Data Exchange (ETDEWEB)

Snyder, T.R.; Vann Bush, P. [Southern Research Institute, Birmingham, AL (United States)

1995-11-01

The overall goal of this research project has been to formulate a model describing effects of flue gas conditioning on particulate properties. By flue gas conditioning we mean any process by which solids, gases, or liquids are added to the combustor and/or the exhaust stream to the extent that flue gas and particulate properties may be altered. Our modeling efforts, which are included in our Final Report, are based on an understanding of how ash properties, such as cohesivity and resistivity, are changed by conditioning. Flue gas conditioning involves the modification of one or more of the parameters that determine the magnitude of forces acting on the fly ash particles, and can take place through many different methods. Modification of particulate properties can alter ash resistivity or ash cohesivity and result in improved or degraded control device performance. Changes to the flue gas, addition or particulate matter such as flue gas desulfurization (FGD) sorbents, or the addition of reactive gases or liquids can modify these properties. If we can better understand how conditioning agents react with fly ash particles, application of appropriate conditioning agents or processes may result in significantly improved fine particle collection at low capital and operating costs.

Capsule endoscopy for the diagnosis and follow up of crohn’s disease

DEFF Research Database (Denmark)

Jensen, Michael Dam; Brodersen, Jacob; Kjeldsen, Jens

2017-01-01

Capsule endoscopy (CE) has revolutionized the diagnosis and monitoring of small bowel Crohn’s disease (CD). the procedure is patient friendly and noninvasive, and compared to cross-sectional imaging, CE allows a direct and detailed evaluation of the entire small bowel mucosa witha high sensitivit...

Monoterpene oxidation in an oxidative flow reactor: SOA yields and the relationship between bulk gas-phase properties and organic aerosol growth

Science.gov (United States)

Friedman, B.; Link, M.; Farmer, D.

2016-12-01

We use an oxidative flow reactor (OFR) to determine the secondary organic aerosol (SOA) yields of five monoterpenes (alpha-pinene, beta-pinene, limonene, sabinene, and terpinolene) at a range of OH exposures. These OH exposures correspond to aging timescales of a few hours to seven days. We further determine how SOA yields of beta-pinene and alpha-pinene vary as a function of seed particle type (organic vs. inorganic) and seed particle mass concentration. We hypothesize that the monoterpene structure largely accounts for the observed variance in SOA yields for the different monoterpenes. We also use high-resolution time-of-flight chemical ionization mass spectrometry to calculate the bulk gas-phase properties (O:C and H:C) of the monoterpene oxidation systems as a function of oxidant concentrations. Bulk gas-phase properties can be compared to the SOA yields to assess the capability of the precursor gas-phase species to inform the SOA yields of each monoterpene oxidation system. We find that the extent of oxygenated precursor gas-phase species corresponds to SOA yield.

Impact of Argon gas on optical and electrical properties of Carbon thin films

Energy Technology Data Exchange (ETDEWEB)

Usman, Arslan, E-mail: arslan.usman@gmail.com [Department of Physics, COMSATS Institute of Information Technology, Lahore (Pakistan); Rafique, M.S. [Department of Physics, University of Engineering & Technology, Lahore 54890 (Pakistan); Shaukat, S.F. [Department of Physics, COMSATS Institute of Information Technology, Lahore (Pakistan); Siraj, Khurram [Department of Physics, University of Engineering & Technology, Lahore 54890 (Pakistan); Ashfaq, Afshan [Institute of Nuclear Medicine and Oncology Lahore (INMOL), 54000 Pakistan (Pakistan); Anjum, Safia [Department of Physics, Lahore College for Women University (Pakistan); Imran, Muhammad; Sattar, Abdul [Department of Physics, COMSATS Institute of Information Technology, Lahore (Pakistan)

2016-12-15

Nanostructured thin films of carbon were synthesized and investigated for their electrical, optical, structural and surface properties. Pulsed Laser Deposition (PLD) technique was used for the preparation of these films under Argon gas environment. A KrF Laser (λ=248 nm) was used as source of ablation and plasma formation. It was observed that the carbon ions and the background gas environment has deep impact on the morphology as well as on the microstructure of the films. Time of Flight (TOF) method was used to determine the energies of the ablated carbon ions. The morphology of film surfaces deposited at various argon pressure was analysed using an atomic force microscope. The Raman spectroscopic measurement reveal that there is shift in phase from sp{sup 3} to sp{sup 2} and a decrease in FWHM of G band, which is a clear indication of enhanced graphitic clusters. The electrical resistivity was also reduced from 85.3×10{sup −1} to 2.57×10{sup −1} Ω-cm. There is an exponential decrease in band gap E{sub g} of the deposited films from 1.99 to 1.37 eV as a function of argon gas pressure.

Application of near ambient pressure gas-phase X-ray photoelectron spectroscopy to the investigation of catalytic properties of copper in methanol oxidation

Energy Technology Data Exchange (ETDEWEB)

Prosvirin, Igor P., E-mail: prosvirin@catalysis.ru [Boreskov Institute of Catalysis, Lavrentieva ave. 5, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, Pirogova str. 2, 630090 Novosibirsk (Russian Federation); Bukhtiyarov, Andrey V., E-mail: avb@catalysis.ru [Boreskov Institute of Catalysis, Lavrentieva ave. 5, 630090 Novosibirsk (Russian Federation); Research and Educational Center for Energy Efficient Catalysis, Novosibirsk State University, Pirogova str. 2, 630090 Novosibirsk (Russian Federation); Bluhm, Hendrik, E-mail: hbluhm@lbl.gov [Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States); Bukhtiyarov, Valerii I., E-mail: vib@catalysis.ru [Boreskov Institute of Catalysis, Lavrentieva ave. 5, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, Pirogova str. 2, 630090 Novosibirsk (Russian Federation); Research and Educational Center for Energy Efficient Catalysis, Novosibirsk State University, Pirogova str. 2, 630090 Novosibirsk (Russian Federation)

2016-02-15

Graphical abstract: - Highlights: • Selective oxidation of CH{sub 3}OH to CH{sub 2}O over a Cu foil has been studied by in situ gas phase XPS. • C1s and O1s spectra were used for identification of reagents and reaction products in a gas phase. • Catalytic data (conversions and reaction products yields) calculated from XPS spectra are in a good agreement with QMS results. • The possible reasons of the observed variations in reaction mechanism have been discussed. - Abstract: Application of near ambient pressure (NAP) X-ray photoelectron spectroscopy for characterization of catalytic properties of a heterogeneous catalyst through measurement and analysis of the core-level spectra from gas phase constituents, which become measurable in submillibar pressure range, has been demonstrated for the reaction of methanol oxidation over polycrystalline copper foil. To improve the accuracy of quantitative analysis of the gas phase signals for the routine XPS spectrometer with double Al/Mg anode used in these experiments, the sample was removed from XPS analysis zone, but it was still located in high-pressure gas cell. As consequence, only gas phase peaks from reagents and reaction products have been observed in XPS spectra. Quantitative analysis of the spectra has allowed us to calculate conversions of the reagents and yields of the reaction products, or, other words, to characterize the catalytic properties of the catalyst and to track their changes with temperature. Further comparison of the catalytic properties with concentration of the surface species measured by in situ XPS in separate experiments, but under the same conditions, gives a possibility to discuss the reaction mechanisms.

Synthesis, characterization and gas separation properties of novel polyimides containing cardo and tert-butyl-m-terphenyl moieties

Directory of Open Access Journals (Sweden)

L. A. Bermejo

2018-05-01

Full Text Available A series of aromatic polyimides has been obtained by the reaction of two dianhydrides, the commercial 2,2′-bis(3,4-dicarboxyphenylhexafluoropropane dianhydride (6FDA and another having a 5′-tert-butyl-m-terphenyl moiety (BTPDA, with several diamines, including two that have a cardo structure (derived from 9H-fluorene, one of them bearing methyl groups ortho to the amino functionalities (TMeCardo. The solubility, and also the thermal, mechanical, and gas separation properties of the corresponding polyimide membranes were evaluated and compared in order to explore the effect of the different groups in the polyimide backbone. The novel polyimides, which were derived from BTPDA and the cardo diamines, showed high thermal stability, excellent solubility in organic solvents and good gas separation properties, especially the polyimide that bore the ortho methyl substituents. The behavior was especially good for the pair O2/N2, where the TMeCardo polymer overpassed the Robeson upper bound.

LPG ammonia and nitrogen dioxide gas sensing properties of nanostructured polypyrrole thin film

Science.gov (United States)

Bagul, Sagar B.; Upadhye, Deepak S.; Sharma, Ramphal

2016-05-01

Nanostructured Polypyrrole thin film was synthesized by easy and economic chemical oxidative polymerization technique on glass at room temperature. The prepared thin film of Polypyrrole was characterized by optical absorbance study by UV-visible spectroscopy and electrical study by I-V measurement system. The optical absorbance spectrum of Polypyrrole shows two fundamental peaks in region of 420 and 890 nm, which confirms the formation of Polypyrrole on glass substrate. The I-V graph of nanostructured Polypyrrole represents the Ohmic nature. Furthermore, the thin film of Polypyrrole was investigated by Scanning electron microscopy for surface morphology study. The SEM micrograph represents spherical nanostructured morphology of Polypyrrole on glass substrate. In order to investigate gas sensing properties, 100 ppm of LPG, Ammonia and Nitrogen Dioxide were injected in the gas chamber and magnitude of resistance has been recorded as a function of time in second. It was observed that nanostructured Polypyrrole thin film shows good sensing behavior at room temperature.

LPG ammonia and nitrogen dioxide gas sensing properties of nanostructured polypyrrole thin film

Energy Technology Data Exchange (ETDEWEB)

Bagul, Sagar B., E-mail: nano.sbbagul@gmail.com; Upadhye, Deepak S.; Sharma, Ramphal, E-mail: rps.phy@gmail.com [Thin Film and Nanotechnology Laboratory, Department of Nanotechnology, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad (India)

2016-05-06

Nanostructured Polypyrrole thin film was synthesized by easy and economic chemical oxidative polymerization technique on glass at room temperature. The prepared thin film of Polypyrrole was characterized by optical absorbance study by UV-visible spectroscopy and electrical study by I-V measurement system. The optical absorbance spectrum of Polypyrrole shows two fundamental peaks in region of 420 and 890 nm, which confirms the formation of Polypyrrole on glass substrate. The I-V graph of nanostructured Polypyrrole represents the Ohmic nature. Furthermore, the thin film of Polypyrrole was investigated by Scanning electron microscopy for surface morphology study. The SEM micrograph represents spherical nanostructured morphology of Polypyrrole on glass substrate. In order to investigate gas sensing properties, 100 ppm of LPG, Ammonia and Nitrogen Dioxide were injected in the gas chamber and magnitude of resistance has been recorded as a function of time in second. It was observed that nanostructured Polypyrrole thin film shows good sensing behavior at room temperature.

Effects of different petal thickness on gas sensing properties of flower-like WO3·H2O hierarchical architectures

International Nuclear Information System (INIS)

Zeng, Wen; Zhang, He; Wang, Zhongchang

2015-01-01

Graphical abstract: In this work, we prepare four different petal thicknesses of hierarchical WO 3 ·H 2 O architectures via a simple hydrothermal process, and systematically report their formation mechanisms and gas-sensing properties. - Highlights: • Flower-like WO 3 ·H 2 O architectures with different petal thickness were reported. • The WO 3 ·H 2 O sheet-flower sensor shows a significantly enhanced gas response. • A possible growth mechanism for the flower-like architectures is proposed. - Abstract: Hierarchical architectures consisting of two-dimensional (2D) nanostructures are of great interest for potential use in recent year. Here, we report the successful synthesis of four hierarchical tungsten oxide flower-like architectures via a simple yet facile hydrothermal method. The as-prepared WO 3 ·H 2 O hierarchical architectures are in fact assembled with numerous nanosheets or nanoplates. Through a comprehensive characterization of microstructures and morphologies of the as-prepared products, we find that petal thickness is a key factor for affecting gas-sensing performances. We further propose a possible growth mechanism for the four flower-like architectures. Moreover, gas-sensing measurements showed that the well-defined sheet-flower WO 3 ·H 2 O hierarchical architectures exhibited the excellent gas-sensing properties to ethanol owing to their largest amount of thin petal structures and pores

Mechanical properties data of 2-1/4Cr-1Mo steel for the experimental very high temperature gas-cooled reactor

International Nuclear Information System (INIS)

Oku, Tatsuo; Kikuyama, Toshihiko; Fukaya, Kiyoshi; Kodaira, Tsuneo

1978-11-01

This is a collection of mechanical properties data of 2-1/4Cr-1Mo steel necessary for structural design and safety analysis of the pressure vessel of the Experimental Very High Temperature Gas-Cooled Reactor (VHTR). These include physical properties, mechanical properties, temper embrittlement, creep with fatigue, fracture toughness and irradiation effects. A review of the data shows the research areas to be carried out particularly in the future for more data. (author)

Enhanced electronic and magnetic properties by functionalization of monolayer GaS via substitutional doping and adsorption

Science.gov (United States)

Rahman, Altaf Ur; Rahman, Gul; Kratzer, Peter

2018-05-01

The structural, electronic, and magnetic properties of two-dimensional (2D) GaS are investigated using density functional theory (DFT). After confirming that the pristine 2D GaS is a non-magnetic, indirect band gap semiconductor, we consider N and F as substitutional dopants or adsorbed atoms. Except for N substituting for Ga (NGa), all considered cases are found to possess a magnetic moment. Fluorine, both in its atomic and molecular form, undergoes a highly exothermic reaction with GaS. Its site preference (FS or FGa) as substitutional dopant depends on Ga-rich or S-rich conditions. Both for FGa and F adsorption at the Ga site, a strong F–Ga bond is formed, resulting in broken bonds within the GaS monolayer. As a result, FGa induces p-type conductivity in GaS, whereas FS induces a dispersive, partly occupied impurity band about 0.5 e below the conduction band edge of GaS. Substitutional doping with N at both the S and the Ga site is exothermic when using N atoms, whereas only the more favourable site under the prevailing conditions can be accessed by the less reactive N2 molecules. While NGa induces a deep level occupied by one electron at 0.5 eV above the valence band, non-magnetic NS impurities in sufficiently high concentrations modify the band structure such that a direct transition between N-induced states becomes possible. This effect can be exploited to render monolayer GaS a direct-band gap semiconductor for optoelectronic applications. Moreover, functionalization by N or F adsorption on GaS leads to in-gap states with characteristic transition energies that can be used to tune light absorption and emission. These results suggest that GaS is a good candidate for design and construction of 2D optoelectronic and spintronics devices.

Synthesis and Transport Properties of Novel MOF/PIM-1/MOF Sandwich Membranes for Gas Separation

Directory of Open Access Journals (Sweden)

Alessio Fuoco

2017-02-01

Full Text Available Metal-organic frameworks (MOFs were supported on polymer membrane substrates for the fabrication of composite polymer membranes based on unmodified and modified polymer of intrinsic microporosity (PIM-1. Layers of two different MOFs, zeolitic imidazolate framework-8 (ZIF-8 and Copper benzene tricarboxylate ((HKUST-1, were grown onto neat PIM-1, amide surface-modified PIM-1 and hexamethylenediamine (HMDA -modified PIM-1. The surface-grown crystalline MOFs were characterized by a combination of several techniques, including powder X-ray diffraction, infrared spectroscopy and scanning electron microscopy to investigate the film morphology on the neat and modified PIM-1 membranes. The pure gas permeabilities of He, H2, O2, N2, CH4, CO2 were studied to understand the effect of the surface modification on the basic transport properties and evaluate the potential use of these membranes for industrially relevant gas separations. The pure gas transport was discussed in terms of permeability and selectivity, highlighting the effect of the MOF growth on the diffusion coefficients of the gas in the new composite polymer membranes. The results confirm that the growth of MOFs on polymer membranes can enhance the selectivity of the appropriately functionalized PIM-1, without a dramatic decrease of the permeability.

Synthesis and Transport Properties of Novel MOF/PIM-1/MOF Sandwich Membranes for Gas Separation

Science.gov (United States)

Fuoco, Alessio; Khdhayyer, Muhanned R.; Attfield, Martin P.; Esposito, Elisa; Jansen, Johannes C.; Budd, Peter M.

2017-01-01

Metal-organic frameworks (MOFs) were supported on polymer membrane substrates for the fabrication of composite polymer membranes based on unmodified and modified polymer of intrinsic microporosity (PIM-1). Layers of two different MOFs, zeolitic imidazolate framework-8 (ZIF-8) and Copper benzene tricarboxylate ((HKUST-1), were grown onto neat PIM-1, amide surface-modified PIM-1 and hexamethylenediamine (HMDA) -modified PIM-1. The surface-grown crystalline MOFs were characterized by a combination of several techniques, including powder X-ray diffraction, infrared spectroscopy and scanning electron microscopy to investigate the film morphology on the neat and modified PIM-1 membranes. The pure gas permeabilities of He, H2, O2, N2, CH4, CO2 were studied to understand the effect of the surface modification on the basic transport properties and evaluate the potential use of these membranes for industrially relevant gas separations. The pure gas transport was discussed in terms of permeability and selectivity, highlighting the effect of the MOF growth on the diffusion coefficients of the gas in the new composite polymer membranes. The results confirm that the growth of MOFs on polymer membranes can enhance the selectivity of the appropriately functionalized PIM-1, without a dramatic decrease of the permeability. PMID:28208658

A gas radiation property model applicable to general combustion CFD and its demonstration in oxy-fuel combustion simulation

DEFF Research Database (Denmark)

Yin, Chungen; Singh, Shashank; Romero, Sergio Sanchez

2017-01-01

As a good compromise between computational efficiency and accuracy, the weighted-sum-of-gray-gases model (WSGGM) is often used in computational fluid dynamics (CFD) modeling of combustion processes for evaluating gas radiative properties. However, the WSGGMs still have practical limitations (e...

Formation of hot intergalactic gas by gas ejection from a galaxy in an early explosive era

International Nuclear Information System (INIS)

Ikeuchi, Satoru

1977-01-01

Chemical evolution of a galaxy in an early explosive era is studied by means of one zone model. Calculating the thermal properties of interstellar gas and the overlapping factor of expanding supernova-remnant shells, the gas escape conditions from a galaxy are examined. From these, it is shown that the total mass of ejected gas from a galaxy amounts to 10 -- 40% of the initial mass of a galaxy. The ejected gas extends to the intergalactic space and the whole universe. The mass, the heavy-element abundance and other physical properties of thus formed intergalactic gas are investigated for various parameters of galactic evolution. Some other effects of gas release on the evolution of a galaxy and the evolution of the universe are discussed. (auth.)

The influence of noble-gas ion bombardment on the electrical and optical properties of clean silicon surfaces

International Nuclear Information System (INIS)

Martens, J.W.D.

1980-01-01

A study of the effect of argon and helium ion bombardment on the electrical and optical properties of the clean silicon (211) surface is described. The objective of the study was to determine the effect of noble gas ions on the density of surface states at the clean silicon surface. (Auth.)

Effects of hydrogen gas on properties of tin-doped indium oxide films deposited by radio frequency magnetron sputtering method

International Nuclear Information System (INIS)

Kim, Do-Geun; Lee, Sunghun; Lee, Gun-Hwan; Kwon, Sik-Chol

2007-01-01

Tin-doped indium oxide (ITO) films were deposited at ∼ 70 deg. C of substrate temperature by radio frequency magnetron sputtering method using an In 2 O 3 -10% SnO 2 target. The effect of hydrogen gas ratio [H 2 / (H 2 + Ar)] on the electrical, optical and mechanical properties was investigated. With increasing the amount of hydrogen gas, the resistivity of the samples showed the lowest value of 3.5 x 10 -4 Ω.cm at the range of 0.8-1.7% of hydrogen gas ratio, while the resistivity increases over than 2.5% of hydrogen gas ratio. Hall effect measurements explained that carrier concentration and its mobility are strongly related with the resistivity of ITO films. The supplement of hydrogen gas also reduced the residual stress of ITO films up to the stress level of 110 MPa. The surface roughness and the crystallinity of the samples were investigated by using atomic force microscopy and x-ray diffraction, respectively

Preparation and Study the Electrical, Structural and Gas Sensing Properties of ZnO Thick Film Resistor

Directory of Open Access Journals (Sweden)

M. K. DEORE

2010-08-01

Full Text Available Thick films of AR grade ZnO were prepared on glass substrate by screen-printing technique. These films were dried and fired at different temperatures between 550 oC, 600 oC and 650 oC for one hour in air atmosphere. The gas sensing performance of thick films was tested for various gases. ZnO films showed larger response (sensitivity to H2S gas (100 ppm at 250 oC for firing temperature 650 oC. The Morphological, Compositional and Structural properties of the ZnO thick films were performed by Scanning electron microscopy (SEM, Energy dispersive spectroscopy (EDX and XRD technique respectively. Chemical composition of ZnO film samples changes with firing temperature showing non-stoichiometric behaviours. XRD study indicated the formation of polycrystalline ZnO films with hexagonal wurtzite structure. The gas response (sensitivity, selectivity, response and recovery time of the sensor were measured and presented.

Influence of an external gas puff on the RI-mode confinement properties in TEXTOR

International Nuclear Information System (INIS)

Kalupin, D.

2002-06-01

An actual subject of experimental and theoretical studies in present day fusion research is the development of an operational scenario combining simultaneously high confinement, with at least H-mode quality, and high densities, around or above the empirical Greenwald limit. Recently, this subject was studied in TEXTOR radiative improved (RI) mode discharges, in which the seeding of a small amount of impurities is helpful in a transition to the improved confinement stage. It was found that by the careful tailoring of external fuelling and optimisation of the wall conditions it is possible to maintain the H-mode or even higher quality confinement at densities much above Greenwald density limit. However, more intense fuelling, aimed to extend maximal achievable densities, led to the progressive confinement deterioration. The theory explains the transition to the RI-mode as a bifurcation into the stage where the transport governed by the ion temperature gradient (ITG) instability is significantly reduced due to a high density gradient and high value of the effective charge. The numerical studies of an influence of the gas puff intensity on confinement properties of plasma, done with the help of the 1-D transport code RITM, show that the same theory can be used for an explanation of the confinement rollover triggered by a strong gas puff. The code was modified in order to simulate the effect of the gas puff on the confinement properties. The anomalous transport coefficients in the plasma core include contributions from the ITG and dissipative trapped electron (DTE) instabilities. The transport at the plasma edge under RI-mode conditions might be described by the electrostatic turbulence caused by electric currents in the scrape-off layer of the limiter. The present computations show that this assumption for the edge transport does not allow the modeling of an effect of the gas puff intensity on the profiles evolution in agreement with experimental observations. The

The gas-sensing properties of thick film sensors based on nano-ZnFe2O4 prepared by hydrothermal method

International Nuclear Information System (INIS)

Chu Xiangfeng; Jiang Dongli; Zheng Chenmou

2006-01-01

ZnFe 2 O 4 sensors were fabricated from nano-ZnFe 2 O 4 powders prepared by hydrothermal method and their gas-sensing properties were investigated. It was found that the phase composition of the product and the gas-sensing properties greatly depend on the reaction pH value and the reaction temperature. Nano-ZnFe 2 O 4 powders could be obtained at a pH of 8-10 and the sensor based on the nano-ZnFe 2 O 4 powder prepared at 220 deg. C exhibited the best performance, characterized by high sensitivity to low concentrations of C 2 H 5 OH at 180 deg. C, especially, the sensitivity to 100 ppm C 2 H 5 OH was as high as 76

Pure- and mixed-gas propylene/propane permeation properties of spiro- and triptycene-based microporous polyimides

KAUST Repository

Swaidan, Ramy J.; Ghanem, Bader; Swaidan, Raja; Litwiller, Eric; Pinnau, Ingo

2015-01-01

Solution-processable polyimides of intrinsic microporosity (PIM-PIs) comprising relatively inflexible and contorted backbones have demonstrated outstanding molecular-sieving behavior in membrane-based separation of gas/gas pairs. In this work, the effects of systematically increasing intra-chain rigidity on the propylene/propane separation properties were compared for PIM-PIs made from 2,3,5,6-tetramethyl-1,4-phenylene diamine (TMPD) and (i) spiro-centered dianhyride (SPDA-TMPD or PIM-PI-1) and (ii) 9,10-diisopropyltriptycene-based dianhydride (TPDA-TMPD or KAUST PI-1). Pure-gas experiments at 2 bar and 35 oC showed significant increases in C3H6 permeability and C3H6/C3H8 selectivity by transitioning from PIM-PI-1 (P(C3H6)=393 Barrer, α(C3H6/C3H8)=6) to KAUST-PI-1 (P(C3H6)=817 Barrer, α(C3H6/C3H8)=16), positioning KAUST-PI-1 considerably above the experimentally observed pure-gas C3H6/C3H8 polymer upper bound. However, 50:50 C3H6/C3H8 mixed-gas feeds induced significant losses in C3H6 permeability and C3H6/C3H8 selectivity relative to the 2 bar pure-gas data for PIM-PI-1 and KAUST-PI-1 as the C3H6/C3H8 selectivity dropped from 6 to 3 and 16 to 5, respectively, at 2 bar C3H6 partial pressure due to plasticization and competitive sorption.

Pure- and mixed-gas propylene/propane permeation properties of spiro- and triptycene-based microporous polyimides

KAUST Repository

Swaidan, Ramy Jawdat

2015-06-03

Solution-processable polyimides of intrinsic microporosity (PIM-PIs) comprising relatively inflexible and contorted backbones have demonstrated outstanding molecular-sieving behavior in membrane-based separation of gas/gas pairs. In this work, the effects of systematically increasing intra-chain rigidity on the propylene/propane separation properties were compared for PIM-PIs made from 2,3,5,6-tetramethyl-1,4-phenylene diamine (TMPD) and (i) spiro-centered dianhyride (SPDA-TMPD or PIM-PI-1) and (ii) 9,10-diisopropyltriptycene-based dianhydride (TPDA-TMPD or KAUST PI-1). Pure-gas experiments at 2 bar and 35 oC showed significant increases in C3H6 permeability and C3H6/C3H8 selectivity by transitioning from PIM-PI-1 (P(C3H6)=393 Barrer, α(C3H6/C3H8)=6) to KAUST-PI-1 (P(C3H6)=817 Barrer, α(C3H6/C3H8)=16), positioning KAUST-PI-1 considerably above the experimentally observed pure-gas C3H6/C3H8 polymer upper bound. However, 50:50 C3H6/C3H8 mixed-gas feeds induced significant losses in C3H6 permeability and C3H6/C3H8 selectivity relative to the 2 bar pure-gas data for PIM-PI-1 and KAUST-PI-1 as the C3H6/C3H8 selectivity dropped from 6 to 3 and 16 to 5, respectively, at 2 bar C3H6 partial pressure due to plasticization and competitive sorption.

Facilitating Students' Interaction with Real Gas Properties Using a Discovery-Based Approach and Molecular Dynamics Simulations

Science.gov (United States)

Sweet, Chelsea; Akinfenwa, Oyewumi; Foley, Jonathan J., IV

2018-01-01

We present an interactive discovery-based approach to studying the properties of real gases using simple, yet realistic, molecular dynamics software. Use of this approach opens up a variety of opportunities for students to interact with the behaviors and underlying theories of real gases. Students can visualize gas behavior under a variety of…

Facile synthesis of improved room temperature gas sensing properties of TiO2 nanostructures: Effect of acid treatment

CSIR Research Space (South Africa)

Tshabalala, Zamaswazi P

2016-03-01

Full Text Available and Actuators B: Chemical Facile synthesis of improved room temperature gas sensing properties of TiO2 nanostructures: Effect of acid treatment Z.P. Tshabalalaa,b, D.E. Motaunga,∗, G.H. Mhlongoa,∗, O.M. Ntwaeaborwab,∗ a DST/CSIR, National Centre...

Fabrication, characterization and gas sensing properties of gold ...

Indian Academy of Sciences (India)

Calixarenes are a group of materials that are widely used for gas sensing studies because of their simple synthesis, conformational flexibility, binding group tunability, variability in their cavity sizes and improved selectivity to different gas molecules. In recent years it has been shown that incorporation of gold nanoparticles ...

Optical properties of wet paper and simulation of the effect of autoprofiling on gas-fired IR drying

Energy Technology Data Exchange (ETDEWEB)

Ojala, K T; Lampinen, M J [Helsinki University of Technology (FI)

1991-12-01

Mathematical models are developed to determine the radiative heat transfer of gas-fired infrared dryers. These models are based on the calculation of radiation energy balance between the main surfaces and layers in the dryer section. The energy efficiency can be calculated, when the temperatures of the radiator and the optical properties of all parts of the dryer are known. A computer program is used for studying the autoprofiling effect in gas-fired infrared drying. Optical properties of paper samples of different moisture contents as a function of wavelength are systematically measured by using FT-IR spectrometer and integrating sphere techniques. These measurements covered the moisture content range of 6-150%. The total measured wavelength range is 1.0-20.0 {mu}m. The moisture content of paper increases the absorptivity mainly in two wavelength ranges, i.e. 1.4-2.6 {mu}m and 3.75-6.0 {mu}m. In these ranges, the difference between the absorptivity of two sheets (dry weight 41.1 g/m{sup 2}, moisture contents 6.0% and 20.8%) is 5-10%. Outside these ranges, the difference is less than 5%. The radiation properties of component surfaces of the IR dryer were measured or taken from literature. The dryer efficiency as a function of the moisture content of paper is calculated. The extent of the autoprofilling effect in gas-fired IR drying is hereby achieved for light weight coated paper web. In one simulation, before the dryer, the moisture difference between two sheets was 5.0% (=20% - 15%). After the dryer, the moisture difference was reduced to 4.5%. If the variation in moisture contents is high, the autoprofilling effect takes place and reduces the moisture variaton. (AB).

Biomolecule-assisted synthesis and gas-sensing properties of porous nanosheet-based corundum In2O3 microflowers

International Nuclear Information System (INIS)

Zhang Wenhui; Zhang Weide

2012-01-01

Porous nanosheet-based corundum In 2 O 3 microflowers were fabricated by one-pot hydrothermal treatment of D-fructose and In(NO 3 ) 3 mixture using urea as a precipitating agent followed by calcination. The products were characterized by X-ray diffraction, scanning and transmission electron microscopy. The effects of D-fructose and urea on the fabrication of nanosheet-based corundum In 2 O 3 microflowers were investigated and a possible mechanism is proposed to explain the formation of the hierarchical nanostructures. The gas sensor based on the In 2 O 3 microflowers exhibits excellent sensing properties for the detection of formaldehyde. - Graphical abstract: Nanosheets-based corundum In 2 O 3 microflowers were fabricated by one-pot hydrothermal treatment of D-fructose/In(NO 3 ) 3 mixture followed by calcination, which show high performance for formaldehyde sensing. Highlights: ► Preparation of porous nanosheet-based corundum In 2 O 3 microflowers. ► Morphology and phase control of In 2 O 3 . ► Gas sensor based on the In 2 O 3 microflowers exhibits excellent sensing properties for the detection of formaldehyde.

Microstructure and gas sensitive properties of alpha-Fe2O3-MO2 (M: Sn and Ti) materials prepared by ball milling

DEFF Research Database (Denmark)

Jiang, Jianzhong; Lin, R.; Mørup, Steen

1998-01-01

Metastable alpha-Fe2O3-MO2 (M: Sn and Ti) solid solutions can be synthesized by mechanical alloying. The alloy formation, microstructure, and gas sensitive properties of mechanically milled alpha-Fe2O3-SnO2 materials are discussed. Tin ions in alpha-Fe2O3 are found to occupy the empty octahedral...... holes in the alpha-Fe2O3 lattice. This interstitial model can also describe the structure of alpha-Fe2O3-TiO2 solid solutions. Finally, a correlation of gas sensitive properties with microstructure of alpha-Fe2O3-SnO2 materials is presented....

Gas adsorption, energetics and electronic properties of boron- and nitrogen-doped bilayer graphenes

Energy Technology Data Exchange (ETDEWEB)

Fujimoto, Yoshitaka, E-mail: fujimoto@stat.phys.titech.ac.jp [Department of Physics, Tokyo Institute of Technology, Oh-okayama, Meguro-ku, Tokyo 152-8551 (Japan); Saito, Susumu [Department of Physics, Tokyo Institute of Technology, Oh-okayama, Meguro-ku, Tokyo 152-8551 (Japan); International Research Center for Nanoscience and Quantum Physics, Tokyo Institute of Technology, 2-12-1 Oh-okayama, Meguro-ku, Tokyo 152-8551 (Japan); Materials Research Center for Element Strategy, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503 (Japan)

2016-10-20

We study stabilities and electronic properties of several environmental polluting or toxic gas molecules (CO, CO{sub 2}, NO, and NO{sub 2}) adsorbed on B and N atoms in bilayer graphene using first-principles electronic-structure calculations. We find that NO and NO{sub 2} molecules can be bound chemically on B-doped bilayer graphene with large adsorption energies, while CO and CO{sub 2} molecules are not adsorbed chemically on B-doped one. In the case of the N-doped graphene, all four gases do not bind with chemical bonds but adsorb rather physically with small adsorption energies at long distances between gases and graphene. The adsorptions of NO and NO{sub 2} molecules on B-doped bilayer graphene induce the acceptor states above the Fermi energy, and we also find that the charge transfer takes place when the NO and the NO{sub 2} molecules are adsorbed. Thereby, the B-doped bilayer graphene is expected to be useful for NO and NO{sub 2} gas sensor materials.

An Introduction to the Gas Phase

Science.gov (United States)

Vallance, Claire

2017-11-01

'An Introduction to the Gas Phase' is adapted from a set of lecture notes for a core first year lecture course in physical chemistry taught at the University of Oxford. The book is intended to give a relatively concise introduction to the gas phase at a level suitable for any undergraduate scientist. After defining the gas phase, properties of gases such as temperature, pressure, and volume are discussed. The relationships between these properties are explained at a molecular level, and simple models are introduced that allow the various gas laws to be derived from first principles. Finally, the collisional behaviour of gases is used to explain a number of gas-phase phenomena, such as effusion, diffusion, and thermal conductivity.

Geological Factors and Reservoir Properties Affecting the Gas Content of Coal Seams in the Gujiao Area, Northwest Qinshui Basin, China

Directory of Open Access Journals (Sweden)

Zhuo Zou

2018-04-01

Full Text Available Coalbed methane (CBM well drilling and logging data together with geological data were adopted to provide insights into controlling mechanism of gas content in major coal seams and establish gas accumulation models in the Gujiao area, Northwest Qinshui Basin, China. Gas content of targeted coals is various in the Gujiao area with their burial depth ranging from 295 to 859 m. Highly variable gas content of coals should be derived from the differences among tectonism, magmatism, hydrodynamism, and sedimentation. Gas content preserved in the Gujiao area is divided into two parts by the geological structure. Gas tends to accumulate in the groundwater stagnant zone with a total dissolved solids (TDS value of 1300–1700 ppm due to water pressure in the Gujiao area. Reservoir properties including moisture content, minerals, and pore structure also significantly result in gas content variability. Subsequently, the gray correlation statistic method was adopted to determine the most important factors controlling gas content. Coal metamorphism and geological structure had marked control on gas content for the targeted coals. Finally, the favorable CBM exploitation areas were comprehensively evaluated in the Gujiao area. The results showed that the most favorable CBM exploitation areas were in the mid-south part of the Gujiao area (Block I.

Thermodynamic DFT analysis of natural gas.

Science.gov (United States)

Neto, Abel F G; Huda, Muhammad N; Marques, Francisco C; Borges, Rosivaldo S; Neto, Antonio M J C

2017-08-01

Density functional theory was performed for thermodynamic predictions on natural gas, whose B3LYP/6-311++G(d,p), B3LYP/6-31+G(d), CBS-QB3, G3, and G4 methods were applied. Additionally, we carried out thermodynamic predictions using G3/G4 averaged. The calculations were performed for each major component of seven kinds of natural gas and to their respective air + natural gas mixtures at a thermal equilibrium between room temperature and the initial temperature of a combustion chamber during the injection stage. The following thermodynamic properties were obtained: internal energy, enthalpy, Gibbs free energy and entropy, which enabled us to investigate the thermal resistance of fuels. Also, we estimated an important parameter, namely, the specific heat ratio of each natural gas; this allowed us to compare the results with the empirical functions of these parameters, where the B3LYP/6-311++G(d,p) and G3/G4 methods showed better agreements. In addition, relevant information on the thermal and mechanic resistance of natural gases were investigated, as well as the standard thermodynamic properties for the combustion of natural gas. Thus, we show that density functional theory can be useful for predicting the thermodynamic properties of natural gas, enabling the production of more efficient compositions for the investigated fuels. Graphical abstract Investigation of the thermodynamic properties of natural gas through the canonical ensemble model and the density functional theory.

Chandra Studies of the X-ray gas properties of fossil systems

Science.gov (United States)

Qin, Zhen-Zhen

2016-03-01

We study ten galaxy groups and clusters suggested in the literature to be “fossil systems (FSs)” based on Chandra observations. According to the M500 - T and LX - T relations, the gas properties of FSs are not physically distinct from ordinary galaxy groups or clusters. We also first study the fgas, 2500 - T relation and find that the FSs exhibit the same trend as ordinary systems. The gas densities of FSs within 0.1r200 are ˜ 10-3 cm-3, which is the same order of magnitude as galaxy clusters. The entropies within 01r200 (S0.1r200) of FSs are systematically lower than those inordinary galaxy groups, which is consistent with previous reports, but we find their S0.1r200 - T relation is more similar to galaxy clusters. The derived mass profiles of FSs are consistent with the Navarro, Frenk and White model in (0.1 - 1)r200, and the relation between scale radius rs and characteristic mass density δc indicates self-similarity of dark matter halos of FSs. The ranges of rs and δc for FSs are also close to those of galaxy clusters. Therefore, FSs share more common characteristics with galaxy clusters. The special birth place of the FS makes it a distinct type of galaxy system.

Gage for gas flow measurement especially in gas-suction pipes

International Nuclear Information System (INIS)

Renner, K.; Stegmanns, W.

1978-01-01

The gage utilizes the differential pressure given by a differential pressure producer to generate, in a bypass, a partial gas flow measured by means of a direct-reading anemometer of windmill type. The partial gas flow is generated between pressure pick-up openings in the gas-suction pipe in front of a venturi insert and pressure pick-up openings at the bottleneck of the venturi insert. The reading of the anemometer is proportional to the main gas flow and independent of the variables of state and the properties of the gases to be measured. (RW) [de

Geological rock property and production problems of the underground gas storage reservoir of Ketzin

Energy Technology Data Exchange (ETDEWEB)

Lange, W

1966-01-01

The purpose of the program of operation for an industrial injection of gas is briefly reviewed. It is emphasized that the works constitute the final stage of exploration. The decisive economic and extractive aspects are given. Final remarks deal with the methods of floor consolidation and tightness control. In the interest of the perspective exploration of the reservoir it is concluded and must be realized as an operating principle that the main problem, after determining the probable reservoir structure, consists in determining step-by-step (by combined theoretical, technical and economic parameters) the surface equipment needed from the geological and rock property factors, which were determined by suitable methods (hydro-exploration, gas injection). The technique and time-table of the geological exploration, and the design and construction of the installations will depend on the solution of the main problem. At the beginning, partial capacities will be sufficient for the surface installation. (12 refs.)

Gas-Transport-Property Performance of Hybrid Carbon Molecular Sieve−Polymer Materials

KAUST Repository

Das, Mita

2010-10-06

High-performance hybrid materials using carbon molecular sieve materials and 6FDA-6FpDA were produced. A detailed analysis of the effects of casting processes and the annealing temperature is reported. Two existing major obstacles, sieve agglomeration and residual stress, were addressed in this work, and subsequently a new membrane formation technique was developed to produce high-performing membranes. The successfully improved interfacial region of the hybrid membranes allows the sieves to increase the selectivity of the membranes above the neat polymer properties. Furthermore, an additional performance enhancement was seen with increased sieve loading in the hybrid membranes, leading to an actual performance above the upper bound for pure polymer membranes. The membranes were also tested under a mixed-gas environment, which further demonstrated promising results. © 2010 American Chemical Society.

On the dependence of structural and sensing properties of sputtered MoO{sub 3} thin films on argon gas flow

Energy Technology Data Exchange (ETDEWEB)

Khojier, K., E-mail: k_khojier@yahoo.com [Department of Physics, Chalous Branch, Islamic Azad University, Chalous (Iran, Islamic Republic of); Savaloni, H. [Department of Physics, University of Tehran, North Kargar Street, Tehran (Iran, Islamic Republic of); Zolghadr, S. [Department of Physics, Faculty of Science, Central Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)

2014-11-30

Highlights: • MoO{sub 3} thin films are sputter coated and their structure are analyzed. • Effect of argon gas flow on the structural and some properties is studied. • CO sensing ability of MoO{sub 3} increases with argon gas flow. • MoO{sub 3} nano-strain decreases with argon gas flow. - Abstract: Nitrogen and carbon oxides (CO, NO and NO{sub 2}), released from combustion facilities and automobiles, are known to be extremely harmful to the human body and also are the main cause of air pollution. Therefore, effective methods to monitor and suppress the carbon and nitrogen oxides have been highly demanded for atmospheric environmental measurements and controls. It is known that molybdenum oxide (MoO{sub 3}) can be a good semiconductor material for use as a gas sensor in monitoring CO, NO and NO{sub 2}. In this paper we report the structural characteristics and sensing properties of the sputtered MoO{sub 3} thin films as a function of argon gas flow. MoO{sub 3} thin films were deposited by DC reactive magnetron sputtering technique on glass substrates at different argon gas flows in the range of 5–20 sccm. X-ray diffraction (XRD) analysis was used for studying crystallographic structure. XRD results showed that all of our films were of polycrystalline structure and of α-MoO{sub 3} stable orthorhombic phase. Results also showed that crystallite size increases while compressive nano-strain in the structure of the films decreases with increasing the argon gas flow. Atomic force microscope and the field emission scanning electron microscope studies showed granular structures for all samples, which increased in size consistent with the XRD results, with argon gas flow, while the surface roughness of the films also increased with argon gas flow. Chemical composition study showed optimum reaction between oxygen and molybdenum atoms for films produced at 15 sccm flow of argon gas. The electrical response of samples was measured in the vacuum and the CO

Shale-gas wells as virtual storage for supporting intermittent renewables

International Nuclear Information System (INIS)

Knudsen, Brage Rugstad; Foss, Bjarne

2017-01-01

Mature shale-gas wells possess a property that enables cyclic production and shut-in without incurring revenue losses. Based on this property, we suggest that fields with mature shale-gas wells may act as virtual gas storage for supplying fast-ramping gas power plants which balance intermittent renewable generation. By enabling gas supply to power plants to circumvent intermediate third-party storage, we argue that the proposed integration facilitates demand-driven gas production, and discuss how the scheme may support utilization of renewables and reduce supply-related greenhouse-gas emissions in electricity generation. - Highlights: • A novel integration strategy of shale gas and renewable electricity generation. • Mature shale-gas wells enable shut-ins without incurring revenue losses. • This property enables the use mature shale-gas wells as virtual gas storage. • Proposed scheme facilitates demand-driven gas production. • Omitting intermediate gas storage reduces GHG emissions from producer to end-user.

Effects of H2/O2 mixed gas plasma treatment on electrical and optical property of indium tin oxide

International Nuclear Information System (INIS)

Kim, Jun Young; Lee, Dong-Min; Kim, Jae-Kwan; Yang, Su-Hwan; Lee, Ji-Myon

2013-01-01

Highlights: ► The specific resistivity of ITO was enhanced by H 2 + O 2 mixed gas plasma treatment. ► The transmittance was same as that of untreated ITO after plasma treatment. ► The process was carried out at room temperature without any step of post-treatment. - Abstract: This study examined the effects of H 2 and H 2 + O 2 mixed gas plasma treatment on the properties of ITO films. The films were deposited on corning glass by RF magnetron sputtering under Ar and Ar/O 2 mixed gas ambient. After a H 2 plasma treatment, the ITO films showed an improved specific resistance due to the formation of oxygen vacancies acting as shallow donors, but showed quenched transmittance due to the formation of agglomerated metals on the surface. After an H 2 + O 2 mixed gas plasma treatment, the specific resistance of the film was improved without deteriorating transmittance. The enhanced specific resistance by mixed gas plasma treatment was attributed to the formation of free electrons by the incorporation of H in the lattice.

Preparation of Pr-doped SnO{sub 2} hollow nanofibers by electrospinning method and their gas sensing properties

Energy Technology Data Exchange (ETDEWEB)

Li, W.Q.; Ma, S.Y., E-mail: lwq19891013@126.com; Li, Y.F.; Li, X.B.; Wang, C.Y.; Yang, X.H.; Cheng, L.; Mao, Y.Z.; Luo, J.; Gengzang, D.J.; Wan, G.X.; Xu, X.L.

2014-08-25

Highlights: • Pr-doped SnO{sub 2} hollow nanofibers were fabricated by electrospinning. • The crystal structures, surface morphology, chemical state and gas sensing performance were investigated. • The Pr-doped SnO{sub 2} hollow structure exhibited good gas-sensing properties to ethanol at 300 °C. • The relationships between response time (recovery time) and temperature, response time (recovery time) and concentration were investigated. • A sensor mechanism of hollow nanofibers depend on temperature was discussed. - Abstract: Pure and Pr-doped SnO{sub 2} hollow nanofibers were fabricated through a facile single capillary electrospinning and followed by calcination. The properties of as-synthesized nanofibers were characterized by scanning electron microscopy, Brunauer–Emmett–Teller, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Compared with pure fibers, Pr-doped SnO{sub 2} nanofibers exhibited excellent ethanol sensing properties at the optimum temperature of 300 °C. Maximum sensing response to ethanol was received in the fibers with 0.6 wt% Pr. The relationships between response time (recovery time) and temperature, response time (recovery time) and concentration were investigated. The results demonstrated that the high response and relatively short response/recovery time were related to surface area, adsorbed oxygen species and oxygen vacancies.

Pentiptycene-based polyurethane with enhanced mechanical properties and CO2-plasticization resistance for thin film gas separation membranes.

Science.gov (United States)

Pournaghshband Isfahani, Ali; Sadeghi, Morteza; Wakimoto, Kazuki; Shrestha, Binod Babu; Bagheri, Rouhollah; Sivaniah, Easan; Ghalei, Behnam

2018-04-30

Development of thin film composite (TFC) membranes offers an opportunity to achieve the permeability/selectivity requirements for optimum CO2 separation performance. However, the durability and performance of thin film gas separation membranes are mostly challenged by weak mechanical properties and high CO2 plasticization. Here, we designed new polyurethane (PU) structures with bulky aromatic chain extenders that afford preferred mechanical properties for ultra-thin film formation. An improvement of about 1500% in Young's modulus and 600% in hardness was observed for pentiptycene-based PUs compared to typical PU membranes. Single (CO2, H2, CH4, and N2) and mixed (CO2/N2 and CO2/CH4) gas permeability tests were performed on the PU membranes. The resulting TFC membranes showed a high CO2 permeance up to 1400 GPU (10-6 cm3(STP) cm-2s-1 cmHg-1) and the CO2/N2 and CO2/H2 selectivities of about 22 and 2.1, respectively. The enhanced mechanical properties of pentiptycene-based PUs results in high performance thin membranes with the similar selectivity of the bulk polymer. The thin film membranes prepared from pentiptycene-based PUs also showed a two-fold enhanced plasticization resistance compared to non-pentiptycene containing PU membranes.

Effect of post-deposition annealing treatment on the structural, optical and gas sensing properties of TiO/sub 2/ thin films

International Nuclear Information System (INIS)

Haidry, A.A.; Durina, P.; Tomasek, M.; Gregus, J.; Schlosser, P.; Mikula, M.; Truhly, M.; Roch, T.; Plecenik, T.; Pidik, A.; Zahoran, M.; Kus, P.; Plecenik, A.

2011-01-01

One of the potential applications of TiO/sub 2/ is its use in gas sensor technology. The aim of this work was to study the gas sensing properties of TiO/sub 2/ thin films in combination with the effect of post-deposition annealing treatment. Titanium dioxide thin films with thickness 100 nm were prepared by the reactive dc magnetron sputtering. The thin films were deposited on sapphire substrate from a titanium target in an oxygen atmosphere. The samples were then post-annealed in air in the temperature range 600 deg. C 1000 deg. C. Crystal structure, surface topography and absorption edge of the thin films have been studied by X-ray Diffraction technique, Atomic Force Microscopy and UV-VIS Spectroscopy. It was found that the phase gradually changed from anatase to rutile, the grain size and roughness tended to increase with increasing post-annealing temperature. The effect of these factors on gas sensing properties was discussed. For electrical measurements comb-like Pt electrodes were prepared by standard photolithography and the films were exposed to different concentrations of H/sub 2/ gas up to 10000 ppm in synthetic air at various operating temperatures from 200 deg. C to 350 deg. C. (author)

Au@NiO core-shell nanoparticles as a p-type gas sensor: Novel synthesis, characterization, and their gas sensing properties with sensing mechanism

KAUST Repository

Majhi, Sanjit Manohar

2018-04-25

In this work, Au@NiO core-shell nanoparticles (C-S NPs) as a p-type gas sensing material was synthesized by a facile wet-chemical method, and evaluated their gas sensing properties as compared to the pristine NiO NPs gas sensors. Transmission electron microscope (TEM) results exhibited the well-dispersed formation of Au@NiO C-S NPs having the total size of 70–120 nm and NiO shells having 30–50 nm thickness. The C-S morphology as well as the overall particle sizes are unchanged even at 500 °C. The gas sensing result reveals that the response of Au@NiO C-S NPs gas sensor is higher than pristine NiO NPs gas sensor for 100 ppm of ethanol at 200 °C operating temperature. The baseline resistance in the air for Au@NiO C-S NPs sensor is lowered as compared to pristine NiO NPs, which is due to the increased number of holes as charge carriers in Au@NiO C-S NPs. The high response of Au@NiO core-shell NPs as compared to pristine NiO NPs is attributed to electronic and chemical sensitization effects of Au. In Au@NiO C-S structure, the contact between metal (Au) and semiconductor (NiO) formed a Schottky junction since Au metal acted as electron acceptor, a withdrawal of electrons from NiO by Au metal core leaved behind number of holes as charge carriers in Au@NiO C-S NPs. Therefore, the baseline resistance of Au@NiO C-S NPs greatly decreased than pristine NiO NPs, as a result the Au@NiO C-S NPs showed higher response. On the other hand, in chemical sensitization effect, Au NPs catalyzed to dissociate O2 molecules into ionic species. This work will give some clue to the researchers for the further development of p-type based C-S NPs sensors.

Gas response properties of citrate gel synthesized nanocrystalline MgFe{sub 2}O{sub 4}: Effect of sintering temperature

Energy Technology Data Exchange (ETDEWEB)

Patil, J.Y. [School of Physical Sciences, Solapur University Solapur-413255 (India); Mulla, I.S. [Emeritus Scientist (CSIR), Centre for Materials for Electronic Technology(C-MET) Pune-411 008 (India); Suryavanshi, S.S., E-mail: sssuryavanshi@rediffmail.com [School of Physical Sciences, Solapur University Solapur-413255 (India)

2013-02-15

Graphical abstract: Display Omitted Highlights: ► Synthesis of nanocrystalline MgFe{sub 2}O{sub 4} by economical citrate gel combustion method. ► Structural, morphological, and gas response properties of MgFe{sub 2}O{sub 4}. ► Enhancement in selectivity of MgFe{sub 2}O{sub 4} towards LPG with sintering temperature. ► Use of MgFe{sub 2}O{sub 4} to detect different gases at different operating temperatures. -- Abstract: Spinel type MgFe{sub 2}O{sub 4} material was synthesized by citrate gel combustion method. The effect of sintering temperature on structural, morphological, and gas response properties was studied. The powder X-ray diffraction pattern and transmission electron microscope study confirms nanocrystalline spinel structure of the synthesized powder. The material was tested for response properties to various reducing gases like liquid petroleum gas (LPG), acetone, ethanol, and ammonia. The results demonstrated n-type semiconducting behavior of MgFe{sub 2}O{sub 4} material. It was revealed that MgFe{sub 2}O{sub 4} sintered at 973 K was most sensitive to LPG at 648 K and to acetone at 498 K. However MgFe{sub 2}O{sub 4} sintered at 1173 K exhibited higher response and selectivity to LPG with marginal increase in the operating temperature. Furthermore, the sensor exhibited a fast response and a good recovery. It was observed that the particles size, porosity, and surface activity of the sensor material is affected by the sintering temperature.

Compact rock material gas permeability properties

Energy Technology Data Exchange (ETDEWEB)

Wang, Huanling, E-mail: whl_hm@163.com [Key Laboratory of Coastal Disaster and Defence, Ministry of Education, Hohai University, Nanjing 210098 (China); LML, University of Lille, Cite Scientifique, 59655 Villeneuve d’Ascq (France); Xu, Weiya; Zuo, Jing [Institutes of Geotechnical Engineering, Hohai University, Nanjing 210098 (China)

2014-09-15

Natural compact rocks, such as sandstone, granite, and rock salt, are the main materials and geological environment for storing underground oil, gas, CO{sub 2,} shale gas, and radioactive waste because they have extremely low permeabilities and high mechanical strengths. Using the inert gas argon as the fluid medium, the stress-dependent permeability and porosity of monzonitic granite and granite gneiss from an underground oil storage depot were measured using a permeability and porosity measurement system. Based on the test results, models for describing the relationships among the permeability, porosity, and confining pressure of rock specimens were analyzed and are discussed. A power law is suggested to describe the relationship between the stress-dependent porosity and permeability; for the monzonitic granite and granite gneiss (for monzonitic granite (A-2), the initial porosity is approximately 4.05%, and the permeability is approximately 10{sup −19} m{sup 2}; for the granite gneiss (B-2), the initial porosity is approximately 7.09%, the permeability is approximately 10{sup −17} m{sup 2}; and the porosity-sensitivity exponents that link porosity and permeability are 0.98 and 3.11, respectively). Compared with moderate-porosity and high-porosity rocks, for which φ > 15%, low-porosity rock permeability has a relatively lower sensitivity to stress, but the porosity is more sensitive to stress, and different types of rocks show similar trends. From the test results, it can be inferred that the test rock specimens’ permeability evolution is related to the relative particle movements and microcrack closure.

Investigation of Continuous Gas Engine CHP Operation on Biomass Producer Gas

DEFF Research Database (Denmark)

Ahrenfeldt, Jesper; Henriksen, Ulrik Birk; Jensen, Torben Kvist

2005-01-01

More than 2000 hours of gas engine operation with producer gas from biomass as fuel has been conducted on the gasification CHP demonstration and research plant, named “Viking” at the Technical University of Denmark. The gas engine is an integrated part of the entire gasification plant. The excess...... operates with varying excess of air due to variation in gas composition and thus stoichiometry, and a second where the excess of air in the exhaust gas is fixed and the flow rate of produced gas from the gasifier is varying. The interaction between the gas engine and the gasification system has been...... investigated. The engine and the plant are equipped with continuously data acquisition that monitors the operation including the composition of the producer gas and the flow. Producer gas properties and contaminations have been investigated. No detectable tar or particle content was observed...

Gas bubble retention and its effect on waste properties: Retention mechanisms, viscosity, and tensile and shear strengths

International Nuclear Information System (INIS)

Gauglitz, P.A.; Rassat, S.D.; Powell, M.R.

1995-08-01

Several of the underground nuclear storage tanks at Hanford have been placed on a flammable gas watch list, because the waste is either known or suspected to generate, store, and episodically release flammable gases. Because retention and episodic release of flammable gases from these tanks containing radioactive waste slurries are critical safety concerns, Pacific Northwest Laboratory (PNL) is studying physical mechanisms and waste properties that contribute to the episodic gas release from these storage tanks. This study is being conducted for Westinghouse Hanford Company as part of the PNL Flammable Gas project. Previous investigations have concluded that gas bubbles are retained by the slurry or sludge that has settled at the bottom of the tanks; however, the mechanisms responsible for the retention of these bubbles are not well understood. Understanding the rheological behavior of the waste, particularly of the settled sludge, is critical to characterizing the tendency of the waste to retain gas bubbles and the dynamics of how these bubbles are released from the waste. The presence of gas bubbles is expected to affect the rheology of the sludge, specifically its viscosity and tensile and shear strengths, but essentially no literature data are available to assess the effect of bubbles. The objectives of this study were to conduct experiments and develop theories to understand better how bubbles are retained by slurries and sludges, to measure the effect of gas bubbles on the viscosity of simulated slurries, and to measure the effect of gas bubbles on the tensile and shear strengths of simulated slurries and sludges. In addition to accomplishing these objectives, this study developed correlations, based on the new experimental data, that can be used in large-scale computations of waste tank physical phenomena

Gas bubble retention and its effect on waste properties: Retention mechanisms, viscosity, and tensile and shear strengths

Energy Technology Data Exchange (ETDEWEB)

Gauglitz, P.A.; Rassat, S.D.; Powell, M.R. [and others

1995-08-01

Several of the underground nuclear storage tanks at Hanford have been placed on a flammable gas watch list, because the waste is either known or suspected to generate, store, and episodically release flammable gases. Because retention and episodic release of flammable gases from these tanks containing radioactive waste slurries are critical safety concerns, Pacific Northwest Laboratory (PNL) is studying physical mechanisms and waste properties that contribute to the episodic gas release from these storage tanks. This study is being conducted for Westinghouse Hanford Company as part of the PNL Flammable Gas project. Previous investigations have concluded that gas bubbles are retained by the slurry or sludge that has settled at the bottom of the tanks; however, the mechanisms responsible for the retention of these bubbles are not well understood. Understanding the rheological behavior of the waste, particularly of the settled sludge, is critical to characterizing the tendency of the waste to retain gas bubbles and the dynamics of how these bubbles are released from the waste. The presence of gas bubbles is expected to affect the rheology of the sludge, specifically its viscosity and tensile and shear strengths, but essentially no literature data are available to assess the effect of bubbles. The objectives of this study were to conduct experiments and develop theories to understand better how bubbles are retained by slurries and sludges, to measure the effect of gas bubbles on the viscosity of simulated slurries, and to measure the effect of gas bubbles on the tensile and shear strengths of simulated slurries and sludges. In addition to accomplishing these objectives, this study developed correlations, based on the new experimental data, that can be used in large-scale computations of waste tank physical phenomena.

On the ideal gas of tachyons

International Nuclear Information System (INIS)

Mrowczynski, S.

1983-01-01

The properties of the ideal gas of classical (nonquantum) faster than light particles-tachyons have been considered. The basic notions of thermodynamics of tachyons have been introduced. We have found the partition function and other thermodynamical quantities for the ideal tachyon gas. The equation of state which we have found for tachyons is exactly the same as for the ideal gas of partictes slower than light-bradyons. The internal energy and the apecific heat have been discussed at low and at very high temperatures. It has been shown that in high temperature limit the properties of gas of tachyons and gas of bradyons are th'e same. The numerical calculations concerning the internal energy and specific heat at different temperatures were performed and the results have been presented. It has been shown that in full interval of temperature the characteristics of gas of tachyons are similar to those of gas of bradyons

Measurement and calculation of gas compressibility factor for condensate gas and natural gas under pressure up to 116 MPa

International Nuclear Information System (INIS)

Yan, Ke-Le; Liu, Huang; Sun, Chang-Yu; Ma, Qing-Lan; Chen, Guang-Jin; Shen, De-Ji; Xiao, Xiang-Jiao; Wang, Hai-Ying

2013-01-01

Highlights: • Volumetric properties of two reservoir fluid samples were measured with pressure up to 116 MPa. • Dew point pressures at four temperatures for condensate gas sample are obtained. • Correlations and thermodynamic model for describing gas compressibility factor under high pressure were compared. • The thermodynamic model recommended is most suitable for fluids produced from reservoirs with a wide pressure range. -- Abstract: The volumetric properties of two reservoir fluid samples collected from one condensate gas well and one natural gas well were measured under four groups of temperatures, respectively, with pressure up to 116 MPa. For the two samples examined, the experimental results show that the gas compressibility factor increases with the increase of pressure. But the influence of the temperature is related to the range of the experimental pressure. It approximately decreases with the increase of temperature when the pressure is larger than (45 to 50) MPa, while there is the opposite trend when the pressure is lower than (45 to 50) MPa. The dew point pressure was also determined for the condensate gas sample, which decreases with the increase of temperature. The capabilities of four empirical correlations and a thermodynamic model based on equation of state for describing gas compressibility factor of reservoir fluids under high pressure were investigated. The comparison results show that the thermodynamic model recommended is the most suitable for fluids whatever produced from high-pressure reservoirs or conventional mild-pressure reservoirs

Synthesis, magnetic and ethanol gas sensing properties of semiconducting magnetite nanoparticles

Science.gov (United States)

Al-Ghamdi, Ahmed A.; Al-Hazmi, Faten; Al-Tuwirqi, R. M.; Alnowaiser, F.; Al-Hartomy, Omar A.; El-Tantawy, Farid; Yakuphanoglu, F.

2013-05-01

The superparamagnetic magnetite (Fe3O4) nanoparticles with an average size of 7 nm were synthesized using a rapid and facile microwave hydrothermal technique. The structure of the magnetite nanoparticles was characterized by X-ray diffraction (X-ray), field effect scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). The prepared Fe3O4 was shown to have a cubic phase of pure magnetite. Magnetization hysteresis loop shows that the synthesized magnetite exhibits no hysteretic features with a superparamagnetic behavior. The ethanol gas sensing properties of the synthesized magnetite were investigated, and it was found that the responsibility time is less than 10 s with good reproducibility for ethanol sensor. Accordingly, it is evaluated that the magnetite nanoparticles can be effectively used as a solid state ethanol sensor in industrial commercial product applications.

Gas amplification properties of GEM foils; Gasverstaerkungseigenschaften von GEM-Folien

Energy Technology Data Exchange (ETDEWEB)

Beck, Jeannine

2009-01-15

In the framework of the detector concept International Linear Detector for the future accelerator project International Linear Collider, in which electrons and positrons at c. m. energies of 500 GeV are brought to collision, a time projection chamber shall be applied as central track detector. By the application of such a chamber as track detector a three-dimensional reconstruction of the track points is possible. If a particle passes the gas volume within the chamber it ionizises single gas atoms and the arising electrons move after the amplification in the GEM arrangement to the anode, so that a two-dimensional projection of the particle track is possible. The third dimension is calculated from the drift time of the electrons. The advances of this readout system consist therein that a better position resolution than by a multiwire proportional chamber is reached and the back-drifting ions can be strongly suppressed. Aim of this thesis are studies for a GEM module, which shall be used in a large TPC prototype. Concerning different requirements it is valid to compare different GEMs in order to can meet an optimal choice. In a small prototype present at DESY measurements for the acquisition of GEM-describing parameters were performed. The taking into operation of the test TPC was part of this thesis. Tracks were generated by a radioactive source, by means of which the gas amplification was determined. With the measurement arrangement gas-amplifier foils of different kind were compared in view of their amplification properties and their energy resolution power and systematically studied. Five different GEM performances were studied in the test TPC. These foils differ in their geometrical classification parameters, the fabrication process, or the materials. The GEMs produced at CERN possess in comparison with GEMs of the Japanese firm SciEnergy and a GEM of the US-American firm Tech-Etch the best amplification and resolution properties. Furthermore a new GEM framing

What's in the Wind? Determining the Properties of Outflowing Gas in Powerful Broad Absorption Line Quasars

Science.gov (United States)

Leighly, Karen

2017-08-01

A significant fraction of quasars exhibits blueshifted broadabsorption lines (BALs) in their rest-UV spectra, indicating powerfuloutflows emerging from the central engine. These outflows may removeangular momentum to enable black hole growth, enrich the intergalacticmedium with metals, and trigger quenching of star formation ingalaxies. Despite years of study, the physical conditions of theoutflowing gas are poorly understood. The handful of objects that havebeen subjected to detailed analysis are atypical and characterized byrelatively narrow lines where blending is unimportant. However,investigating more powerful BAL quasars will give us better insightinto the types of outflows much more likely to impact galaxyevolution.SimBAL is a novel spectral synthesis fitting method for BAL quasarsthat uses Bayesian model calibration to compare synthetic to observedspectra. With the model inputs of ionization parameter, columndensity, and covering fraction specified, the gas properties givingrise to the BAL features can be determined. We propose to applySimBAL to archival spectra of a sample of 14 luminous BAL quasars to characterize their bulk outflow properties as a function of velocityfor the first time. Our results will show the range of parameterstypical of powerful outflows, an essential step towards constrainingthe physics behind quasar winds and thus their impact on theirenvironments.

The heating of UO_2 kernels in argon gas medium on the physical properties of sintered UO_2 kernels

International Nuclear Information System (INIS)

Damunir; Sri Rinanti Susilowati; Ariyani Kusuma Dewi

2015-01-01

The heating of UO_2 kernels in argon gas medium on the physical properties of sinter UO_2 kernels was conducted. The heated of the UO_2 kernels was conducted in a sinter reactor of a bed type. The sample used was the UO_2 kernels resulted from the reduction results at 800 °C temperature for 3 hours that had the density of 8.13 g/cm"3; porosity of 0.26; O/U ratio of 2.05; diameter of 1146 μm and sphericity of 1.05. The sample was put into a sinter reactor, then it was vacuumed by flowing the argon gas at 180 mmHg pressure to drain the air from the reactor. After that, the cooling water and argon gas were continuously flowed with the pressure of 5 mPa with 1.5 liter/minutes velocity. The reactor temperature was increased and variated at 1200-1500 °C temperature and for 1-4 hours. The sinters UO_2 kernels resulted from the study were analyzed in term of their physical properties including the density, porosity, diameter, sphericity, and specific surface area. The density was analyzed using pycnometer with CCl_4 solution. The porosity was determined using Haynes equation. The diameters and sphericity were showed using the Dino-lite microscope. The specific surface area was determined using surface area meter Nova-1000. The obtained products showed the the heating of UO_2 kernel in argon gas medium were influenced on the physical properties of sinters UO_2 kernel. The condition of best relatively at 1400 °C temperature and 2 hours time. The product resulted from the study was relatively at its best when heating was conducted at 1400 °C temperature and 2 hours time, produced sinters UO_2 kernel with density of 10.14 gr/ml; porosity of 7 %; diameters of 893 μm; sphericity of 1.07 and specific surface area of 4.68 m"2/g with solidify shrinkage of 22 %. (author)

Pure- and mixed-gas CO2/CH4 separation properties of PIM-1 and an amidoxime-functionalized PIM-1

KAUST Repository

Swaidan, Raja

2014-05-01

The prototypical solution-processable polymer of intrinsic microporosity, PIM-1, and derivatives thereof offer combinations of permeability and selectivity that make them potential candidate materials for membrane-based gas separations. Paramount to the design and evaluation of PIMs for economical natural gas sweetening is a high and stable CO2/CH4 selectivity under realistic, mixed-gas conditions. Here, amidoxime-functionalized PIM-1 (AO-PIM-1) was prepared and examined for fundamental structure/property relationships. Qualitative NLDFT pore-size distribution analyses of physisorption isotherms (N2 at -196 oC; CO2 at 0 oC) reveal a tightened microstructure indicating size-sieving ultra-microporosity (<7Å). AO-PIM-1 demonstrated a three-fold increase in αD(CO2/CH4) over PIM-1, surpassing the 2008 upper bound with P(CO2)=1153Barrer and ideal α(CO2/CH4)=34. Under a 50:50 CO2:CH4 mixed-gas feed, AO-PIM-1 showed less selectivity loss than PIM-1, maintaining a mixed-gas α(CO2/CH4) ~21 across a 20bar pressure range. Conversely, PIM-1 endured up to 60% increases in mixed-gas CH4 permeability over pure-gas values concurrent with a selectivity of only ~8 at 20bar. A pervasive intermolecular hydrogen bonding network in AO-PIM-1 predominantly yields a rigidified microstructure that mitigates CO2-induced matrix dilations, reducing detrimental mixed-gas CH4 copermeation. © 2014 Elsevier B.V.

Inverse gas chromatography as a method for determination of surface properties of binding materials

Science.gov (United States)

Yu, Jihai; Lu, Xiaolei; Yang, Chunxia; Du, Baoli; Wang, Shuxian; Ye, Zhengmao

2017-09-01

Inverse gas chromatography (IGC) is a promising measurement technique for investigating the surface properties of binding materials, which are the major influence element for the adsorption performance of superplasticizer. In this work, using the IGC method, blast furnace slag (BFS), sulphoaluminate cement (SAC) and portland cement (P·O) are employed to systematically evaluate the corresponding dispersive component (γsd), specific surface free energy (γsab), and acid-base properties. The obtained results show that γsd contributes to a major section of the surface free energy in the three binding materials, suggesting they are of a relatively low polarity. Compared to the two kinds of cements, the BFS possesses the highest dispersive and specific surface free energies (the values are 45.01 mJ/m2 and 11.68 mJ/m2, respectively), and also exhibits a wider distribution range of γsd, indicating their surfaces are heterogeneous. For acid-base properties, the results indicate the surfaces of three samples are basic in nature. In addition, the adsorption investigation shows that per unit surface of BFS adsorbs the most superplasticizer molecules, which indicates the higher surface free energies is beneficial to the superplasticizer adsorption.

Modelling of Rotor-gas bearings for Feedback Controller Design

DEFF Research Database (Denmark)

Theisen, Lukas Roy Svane; Niemann, Hans Henrik

2014-01-01

Controllable rotor-gas bearings are popular oering adaptability, high speed operation, low friction and clean operation. Rotor-gas bearings are however highly sensitive to disturbances due to the low friction of the injected gas. These undesirable damping properties call for controllers, which ca...... and are shown to accurately describe the dynamical behaviour of the rotor-gas bearing. Design of a controller using the identied models is treated and experiments verify the improvement of the damping properties of the rotor-gas bearing.......Controllable rotor-gas bearings are popular oering adaptability, high speed operation, low friction and clean operation. Rotor-gas bearings are however highly sensitive to disturbances due to the low friction of the injected gas. These undesirable damping properties call for controllers, which can...... be designed from suitable models describing the relation from actuator input to measured shaft position. Current state of the art models of controllable gas bearings however do not provide such relation, which calls for alternative strategies. The present contribution discusses the challenges for feedback...

Zn doped MoO3 nanobelts and the enhanced gas sensing properties to ethanol

Science.gov (United States)

Yang, Shuang; Liu, Yueli; Chen, Tao; Jin, Wei; Yang, Tingqiang; Cao, Minchi; Liu, Shunshun; Zhou, Jing; Zakharova, Galina S.; Chen, Wen

2017-01-01

Zn doped MoO3 nanobelts with the thickness of 120-275 nm, width of 0.3-1.4 μm and length of more than 100 μm are prepared by hydrothermal reaction. The operating temperature of sensors based on Zn doped MoO3 nanobelts is 100-380 °C with a better response to low concentration of ethanol. The highest response value of sensors based on Zn doped MoO3 to 1000 ppm ethanol at 240 °C is 321, which is about 15 times higher than that of pure MoO3 nanobelts. The gas sensors based on Zn doped MoO3 nanobelts possess good selectivity to ethanol compared with methanol, ammonia, acetone and toluene, which implies that it would be a good candidate in the potential application. The improvement of gas sensing properties may be attributed to the increasing absorbed ethanol, the decreasing probability of ethoxy recombination, the promoted dehydrogenation progress at lower temperature, and the narrowed band gap by Zn doping.

Synthesis of Aluminum-Aluminum Nitride Nanocomposites by a Gas-Liquid Reaction II. Microstructure and Mechanical Properties

Science.gov (United States)

Borgonovo, Cecilia; Makhlouf, Makhlouf M.

2016-04-01

In situ fabrication of the reinforcing particles in the metal matrix is an answer to many of the challenges encountered in manufacturing aluminum matrix nanocomposites. In this method, the nanoparticles are formed directly within the melt by means of a chemical reaction between a specially designed aluminum alloy and a gas. In this publication, we describe a process for synthesizing aluminum-aluminum nitride nanocomposites by reacting a nitrogen-containing gas with a molten aluminum-lithium alloy. We quantify the effect of the process parameters on the average particle size and particle distribution, as well as on the tendency of the particles to cluster in the alloy matrix, is quantified. Also in this publication, we present the measured room temperature and elevated temperature tensile properties of the nanocomposite material as well as its measured room temperature impact toughness.

Study on the properties of the fuel compact for High Temperature Gas-cooled Reactor

International Nuclear Information System (INIS)

Lee, Chung-yong; Lee, Sung-yong; Choi, Min-young; Lee, Seung-jae; Jo, Young-ho; Lee, Young-woo; Cho, Moon-sung

2015-01-01

High Temperature Gas-cooled Reactors (HTGR), one of the Gen-IV reactors, have been using the fuel element which is manufactured by the graphite matrix, surrounding Tristructural-isotropic (TRISO)-coated Uranium particles. Factors with these characteristics effecting on the matrix of fuel compact are chosen and their impacts on the properties are studied. The fuel elements are considered with two types of concepts for HTGR, which are the block type reactor and the pebble bed reactor. In this paper, the cylinder-formed fuel element for the block type reactor is focused on, which consists of the large part of graphite matrix. One of the most important properties of the graphite matrix is the mechanical strength with the high reliability because the graphite matrix should be enabled to protect the TRISO particles from the irradiation environment and the impact from the outside. In this study, the three kinds of candidate graphites and the two kinds of candidate binder (Phenol and Polyvinyl butyral) were chosen and mixed with each other, formed and heated to measure mechanical properties. The objective of this research is to optimize the materials and composition of the mixture and the forming process by evaluating the mechanical properties before/after carbonization and heat treatment. From the mechanical test results, the mechanical properties of graphite pellets was related to the various conditions such as the contents and kinds of binder, the kinds of graphite and the heat treatments. In the result of the compressive strength and Vicker's hardness, the 10 wt% phenol binder added R+S graphite pellet was relatively higher mechanical properties than other pellets. The contents of Phenol binder, the kinds of graphite powder and the temperature of carbonization and heat treatment are considered important factors for the properties. To optimize the mechanical properties of fuel elements, the role of binders and the properties of graphites will be investigated as

Environmental site assessments should include radon gas testing

International Nuclear Information System (INIS)

Nardi, M.A.

1991-01-01

There are two emerging influences that will require radon gas testing as part of many property transfers and most site assessments. These requirements come from lending regulators and state legislatures. Fannie Mae and others have developed environmental investigation guidelines for the purchase of environmentally contaminated real estate. These guidelines include radon gas testing for many properties. Several states have enacted laws that require environmental disclosure forms be prepared to ensure that the parties involved in certain real estate transactions are aware of the environmental liabilities that may come with the transfer of property. Indiana has recently enacted legislation that would require the disclosure of the presence of radon gas on many commercial real estate transactions. With more lenders and state governments likely to follow this trend, radon gas testing should be performed during all property transfers and site assessment to protect the parties involved from any legal liabilities

A porous cadmium(II) framework. Synthesis, crystal structure, gas adsorption, and fluorescence sensing properties

Energy Technology Data Exchange (ETDEWEB)

Zhou, Pingping [College of Sciences, Agricultural University of Hebei, Baoding (China)

2017-05-18

The Cd{sup II} compound, namely [Cd(Tppa)(SO{sub 4})(H{sub 2}O)]{sub n} (1) [Tppa = tris(4-(pyridyl)phenyl) amine], was synthesized by the reaction of CdSO{sub 4}.8H{sub 2}O and Tppa under solvothermal conditions. Single crystal X-ray diffraction analysis revealed that compound 1 features a 3D porous framework based on 1D inorganic -[Cd-SO{sub 4}-Cd]{sub n}- chains. Topological analysis reveals that compound 1 represents a trinodal (3,4,6)-connected topological network with the point symbol of {6.7"2}{sub 2}{6"4.7.10}{6"4.7"5.8"4.10"2}. Gas adsorption properties investigations indicate that compound 1 exhibits moderate adsorption capacities for light hydrocarbons at room temperature. Luminescence property studies revealed that this Cd{sup II} compound exhibits high fluorescence sensitivity for sensing of CS{sub 2} molecule. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Study of the Mechanical Properties of Ti-3Al-2.5V after Surface Plasma Gas Treatment with Indirect Plasma Torch

Directory of Open Access Journals (Sweden)

Rosen Vasilev

2015-11-01

Full Text Available Commercial titanium alloy Ti-3Al-2.5V became one of the most widely used titanium alloys after its introduction in the early seventies. It has a very attractive combination of tensile strength, creep strength, toughness and high-temperature stability for long-term applications up to 425ºC. It is used for gas turbine components and in other applications where this good combination of properties is required [1]. At the same time it has poor tribological properties that are typical of most of the titanium alloys. It has low surface hardness and wear resistance. These disadvantages of the material limit its application [1], [2]. Ti-3Al-2.5V was chosen for this experimental work because it showed a good plasma gas nitriding performance in comparison with the other alloys during the tests.

Using a two-layered sphere model to investigate the impact of gas vacuoles on the inherent optical properties of Microcystis aeruginosa

CSIR Research Space (South Africa)

Matthews, MW

2013-01-01

Full Text Available A two-layered sphere model is used to investigate the impact of gas vacuoles on the inherent optical properties (IOPs) of the cyanophyte Microcystis aeruginosa. Enclosing a vacuole-like particle within a chromatoplasm shell layer significantly...

The (gas + liquid) critical properties and phase behaviour of some binary alkanol (C2-C5) + alkane (C5-C12) mixtures

International Nuclear Information System (INIS)

Morton, David W.; Lui, Matthew P.W.; Young, Colin L.

2003-01-01

Previously, the investigation of the (gas + liquid) critical properties of (alkanol + alkane) mixtures has focussed on (primary alkanol + straight chain alkane) mixtures. The experimental data available for (alkanol + alkane) mixtures, which include secondary or tertiary alcohols and/or branched chain alkanes, are extremely limited. This work extends the existing body of data on (alkanol + alkane) mixtures to include mixtures containing these components. Here the (gas + liquid) critical temperatures of 29 {alkanol (C 2 -C 5 ) + alkane (C 5 -C 12 )} mixtures are reported. All the (gas + liquid) critical lines for the binary mixtures studied are continuous, indicating they obey either Type I or Type II phase behaviour

Dense-gas dispersion advection-diffusion model

International Nuclear Information System (INIS)

Ermak, D.L.

1992-07-01

A dense-gas version of the ADPIC particle-in-cell, advection- diffusion model was developed to simulate the atmospheric dispersion of denser-than-air releases. In developing the model, it was assumed that the dense-gas effects could be described in terms of the vertically-averaged thermodynamic properties and the local height of the cloud. The dense-gas effects were treated as a perturbation to the ambient thermodynamic properties (density and temperature), ground level heat flux, turbulence level (diffusivity), and windfield (gravity flow) within the local region of the dense-gas cloud. These perturbations were calculated from conservation of energy and conservation of momentum principles along with the ideal gas law equation of state for a mixture of gases. ADPIC, which is generally run in conjunction with a mass-conserving wind flow model to provide the advection field, contains all the dense-gas modifications within it. This feature provides the versatility of coupling the new dense-gas ADPIC with alternative wind flow models. The new dense-gas ADPIC has been used to simulate the atmospheric dispersion of ground-level, colder-than-ambient, denser-than-air releases and has compared favorably with the results of field-scale experiments

Lithological and petrophysical properties and prospects of oil and gas presence of Kalinsky series in Absheron

International Nuclear Information System (INIS)

Kheirov, M.B; Dilbazi, Z.H; Askerov, F.H; Imanov, A.D.

2002-01-01

Full text:The presentation is is dedicated to summarizing the results of studying lithological and petrographic peculiarities and petrophysical properties of relatively scarcely studied rocks of lower Pliocene Kalinsky Series in Absheron, particularly its lower horizons, as well as to determining the regularities of these properties change about the area, as well as along the geological section. These generalisation cover the areas of Gala, Turkany, Gala-Dubendy, Govsany, Garachukhur, Bina, Zykh, Peschany island, Chilov, Khali, Gryazevaya sopka, Pirallakhy, and they are necessary for determining the direction of exploration and increasing the efficiency of productive horizons development. Kalinsky series is represented mostly by the alternation of siltstones, sandstones and shale and subjected to lithofacial changes along the section and about the area. In the reservoir sections studied Kalinsky series is mostly of polymetallic composition and is represented by badly sorted rocks. The sorting coefficient is within the range 2.5-4.7. Sands and sandstones occur relatively seldom. Thus, Kalinsky series, and its lower horizons in particular are scarcely studied. In some areas these horizons in particular are scarcely studied. In some areas horizons are not exposed. That is why for the purpose of oil and gas presence degree clarification it is necessary to resume exploration in Absheron oil and gas bearing region Kalinsky series, and in particular in its lower horizons

TIG AISI-316 welds using an inert gas welding chamber and different filler metals: Changes in mechanical properties and microstructure

Energy Technology Data Exchange (ETDEWEB)

Pascual, M.; Salas, F.; Carcel, F.J.; Perales, M.; Sanchez, A.

2010-07-01

This report analyses the influence of the use of an inert gas welding chamber with a totally inert atmosphere on the microstructure and mechanical properties of austenitic AISI 316L stainless steel TIG welds, using AISI ER316L, AISI 308L and Inconel 625 as filler metals. When compared with the typical TIG process, the use of the inert gas chamber induced changes in the microstructure, mainly an increase in the presence of vermicular ferrite and ferrite stringers, what resulted in higher yield strengths and lower values of hardness. Its effect on other characteristics of the joins, such as tensile strength, depended on the filler metal. The best combination of mechanical characteristics was obtained when welding in the inert gas chamber using Inconel 625 as filler metal. (Author). 12 refs.

Development of Innovating Materials for Distributing Mixtures of Hydrogen and Natural Gas. Study of the Barrier Properties and Durability of Polymer Pipes

Directory of Open Access Journals (Sweden)

Klopffer Marie-Hélène

2015-02-01

Full Text Available With the growing place taken by hydrogen, a question still remains about its delivery and transport from the production site to the end user by employing the existing extensive natural gas pipelines. Indeed, the key challenge is the significant H2 permeation through polymer infrastructures (PolyEthylene (PE pipes, components such as connecting parts. This high flow rate of H2 through PE has to be taken into account for safety and economic requirements. A 3-year project was launched, the aim of which was to develop and assess material solutions to cope with present problems for hydrogen gas distribution and to sustain higher pressure compared to classical high density polyethylene pipe. This project investigated pure hydrogen gas and mixtures with natural gas (20% of CH4 and 80% of H2 in pipelines with the aim to select engineering polymers which are more innovative than polyethylene and show outstanding properties, in terms of permeation, basic mechanical tests but also more specific characterizations such as long term ageing and behaviour. The adequate benches, equipments and scientific approach for materials testing had been developed and validated. In this context, the paper will focus on the evaluation of the barrier properties of 3 polymers (PE, PA11 and PAHM. Experiments were performed for pure H2 and CH4 and also in the presence of mixtures of hydrogen and natural gas in order to study the possible mixing effects of gases. It will report some round-robin tests that have been carried out. Secondly, by comparing data obtained on film, polymer membrane and on pipe section, the influence of the polymer processing will be studied. Innovative multilayers systems will be proposed and compared on the basis of the results obtained on monolayer systems. Finally, the evolution of the transport properties of the studied polymers with an ageing under representative service conditions will be discussed.

Effects of adatom and gas molecule adsorption on the physical properties of tellurene: a first principles investigation.

Science.gov (United States)

Wang, Xiao Hua; Wang, Da Wei; Yang, Ai Jun; Koratkar, Nikhil; Chu, Ji Feng; Lv, Pin Lei; Rong, Ming Zhe

2018-02-07

Tellurene is a new member of the two-dimensional (2D) materials' family, whose existence has been recently confirmed by first principles calculation and experimental work. Tellurene is also the first 2D mono-elemental material of group-VI predicted by scientists, and investigations of its basic properties are still in their infancy. In this study, we use first principles calculation based on density functional theory to investigate the adsorption of nineteen typical adatoms (Li, Na, K, Ca, Fe, Co, Ni, Cu, Zn, Ag, Au, Pd, Pt, B, N, O, Si, Cl, and Al), and five typical gas molecules (H 2 , O 2 , H 2 O, NO 2 , and NH 3 ) on α-phase as well as β-phase tellurene sheets. Our calculations shows that most adatoms are chemisorbed on tellurene sheets with large adsorption energies. Moreover, some of the adatoms are observed to give rise to distinct structural deformations and even local reconstructions. We report that a variety of electronic states are induced by the adatoms, which implies that different electronic structures can be engineered by the adsorption of adatoms. In fact, n-type doping, p-type doping, half-metal, and spin-gapless semiconductor features can be acquired by doping adatoms on tellurene sheets. Our calculations also show that the five gas molecules are all physisorbed on tellurene sheets, and no splitting behaviors are observed. Therefore, the adsorption of the five gas molecules has a weak effect on the electronic properties of tellurene. To conclude, our results indicate that adatom engineering may be used to greatly expand the potential applications of 2D tellurene.

Determining the hydraulic and fracture properties of the Coal Seam Gas well by numerical modelling and GLUE analysis

Science.gov (United States)

Askarimarnani, Sara; Willgoose, Garry; Fityus, Stephen

2017-04-01

Coal seam gas (CSG) is a form of natural gas that occurs in some coal seams. Coal seams have natural fractures with dual-porosity systems and low permeability. In the CSG industry, hydraulic fracturing is applied to increase the permeability and extract the gas more efficiently from the coal seam. The industry claims that it can design fracking patterns. Whether this is true or not, the public (and regulators) requires assurance that once a well has been fracked that the fracking has occurred according to plan and that the fracked well is safe. Thus defensible post-fracking testing methodologies for gas generating wells are required. In 2009 a fracked well HB02, owned by AGL, near Broke, NSW, Australia was subjected to "traditional" water pump-testing as part of this assurance process. Interpretation with well Type Curves and simple single phase (i.e. only water, no gas) highlighted deficiencies in traditional water well approaches with a systemic deviation from the qualitative characteristic of well drawdown curves (e.g. concavity versus convexity of drawdown with time). Accordingly a multiphase (i.e. water and methane) model of the well was developed and compared with the observed data. This paper will discuss the results of this multiphase testing using the TOUGH2 model and its EOS7C constitutive model. A key objective was to test a methodology, based on GLUE monte-carlo calibration technique, to calibrate the characteristics of the frack using the well test drawdown curve. GLUE involves a sensitivity analysis of how changes in the fracture properties change the well hydraulics through and analysis of the drawdown curve and changes in the cone of depression. This was undertaken by changing the native coal, fracture, and gas parameters to see how changing those parameters changed the match between simulations and the observed well drawdown. Results from the GLUE analysis show how much information is contained in the well drawdown curve for estimating field scale

Computational sensitivity study of spray dispersion and mixing on the fuel properties in a gas turbine combustor

Energy Technology Data Exchange (ETDEWEB)

Grosshans, Holger; Szász, Robert-Zoltán [Division of Fluid Mechanics, Lund University (Sweden); Cao, Le [Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science and Technology, Nanjing (China); Fuchs, Laszlo, E-mail: holger.grosshans@uclouvain.be [Department of Mechanics, KTH, Stockholm (Sweden)

2017-04-15

A swirl stabilized gas turbine burner has been simulated in order to assess the effects of the fuel properties on spray dispersion and fuel–air mixing. The properties under consideration include fuel surface tension, viscosity and density. The turbulence of the gas phase is modeled applying the methodology of large eddy simulation whereas the dispersed liquid phase is described by Lagrangian particle tracking. The exchange of mass, momentum and energy between the two phases is accounted for by two-way coupling. Bag and stripping breakup regimes are considered for secondary droplet breakup, using the Reitz–Diwakar and the Taylor analogy breakup models. Moreover, a model for droplet evaporation is included. The results reveal a high sensitivity of the spray structure to variations of all investigated parameters. In particular, a decrease in the surface tension or the fuel viscosity, or an increase in the fuel density, lead to less stable liquid structures. As a consequence, smaller droplets are generated and the overall spray surface area increases, leading to faster evaporation and mixing. Furthermore, with the trajectories of the small droplets being strongly influenced by aerodynamic forces (and less by their own inertia), the spray is more affected by the turbulent structures of the gaseous phase and the spray dispersion is enhanced. (paper)

Effect of nitrogen gas flow rate on the tribological properties of TiN coated HSS using CAE PVD technique

International Nuclear Information System (INIS)

Mubarak, A.; Hamzah, E.; Toff, M.R.M.

2005-01-01

High-Speed Steel (HSS) is a material that used in various Hi-Tech industries for many reasons. The aim of this study is to investigate the tribological properties of TiN (Titanium Nitride)-coated HSS. Using Physical Vapour Deposition (PVD) Cathodic Arc Evaporation (CAE) technique coated samples. The goal of this work is to determine usefulness of TiN coatings in order to improve tribological properties of HSS, as vastly use in cutting tool industry for various applications. A Pin-on-Disc test showed that the minimum value recorded for friction coefficient was reduced from 0.294 to 0.239 when the nitrogen gas flow rate was increased from 100 sccm to 200 sccm. The decrease in friction coefficient resulted from the reduction in macrodroplets by increasing the nitrogen gas flow rate during deposition. The worn surface morphology of the TiN coated HSS was observed on a Field Emission Scanning Electron Microscope (FE-SEM), and the elemental composition on the wear scar were investigated by means of EDXS. (Author)

Study of effective transport properties of fresh and aged gas diffusion layers

Science.gov (United States)

Bosomoiu, Magdalena; Tsotridis, Georgios; Bednarek, Tomasz

2015-07-01

Gas diffusion layers (GDLs) play an important role in proton exchange membrane fuel cells (PEMFCs) for the diffusion of reactant and the removal of product water. In the current study fresh and aged GDLs (Sigracet® GDL34BC) were investigated by X-ray computed tomography to obtain a representative 3D image of the real GDL structure. The examined GDL samples are taken from areas located under the flow channel and under the land. Additionally, a brand new Sigracet® GDL34BC was taken as a reference sample in order to find out the impact of fuel cell assembly on GDL. The produced 3D image data were used to calculate effective transport properties such as thermal and electrical conductivity, diffusivity, permeability and capillary pressure curves of the dry and partially saturated GDL. The simulation indicates flooding by product water occurs at contact angles lower than 125° depending on sample porosity. In addition, GDL anisotropy significantly affects the permeability as well as thermal and electrical conductivities. The calculated material bulk properties could be next used as input for CFD modelling of PEM fuel cells where GDL is usually assumed layer-like and homogeneous. Tensor material parameters allow to consider GDL anisotropy and lead to more realistic results.

Rio Vista gas leak study: Belleaire Gas Field, California

International Nuclear Information System (INIS)

Wilkey, P.L.

1992-08-01

The Rio Vista gas leak study evaluated methods for remotely sensing gas leaks from buried pipelines and developed methods to elucidate methane transport and microbial oxidation in soils. Remote-sensing methods were evaluated by singing gas leaks along an abandoned Pacific Gas and Electric (PG ampersand E) gas field collection line in northern California and applying surface-based and airborne remote-sensing techniques in the field, including thermal imaging, laser imaging, and multispectral imagery. The remote-sensing techniques exhibited limitations in range and in their ability to correlate with ground truth data. To elucidate methane transport and microbial oxidation in soils, a study of a controlled leak permitted field testing of methods so that such processes could be monitored and evaluated. Monitoring and evaluation techniques included (1) field measurement of soil-gas concentrations, temperatures, and pressures; (2) laboratory measurement of soil physical/chemical properties and activity of methane-oxidizing microorganisms by means of field samples; and (3) development of a preliminary numerical analysis technique for combined soil-gas transport/methane oxidation. Soil-gas concentrations at various depths responded rapidly to the high rate of gas leakage. The number of methane-oxidizing microorganisms in site soils rapidly increased when the gas leak was initiated and decreased after the leak was terminated. The preliminary field, laboratory, and numerical analysis techniques tested for this study of a controlled gas leak could be successfully applied to future studies of gas leaks. Because soil-gas movement is rapid and temporally variable, the use of several complementary techniques that permit generalization of site-specific results is favored

Synthesis of star-shaped lead sulfide (PbS) nanomaterials and theirs gas-sensing properties

Energy Technology Data Exchange (ETDEWEB)

Song, Chengwen; Sun, Menghan; Yin, Yanyan; Xiao, Jingkun; Dong, Wei; Li, Chen; Zhang, Li, E-mail: chengwensong@dlmu.edu.cn [College of Environmental Science and Engineering, Dalian Maritime University, Dalian(China)

2016-11-15

Star-shaped PbS nanomaterials are synthesized by a hydrothermal method. Morphology and structure of the PbS nanomaterials are analyzed by SEM, HRTEM and XRD. Gas-sensing properties of the as-prepared PbS sensor are also systematically investigated. The results show star-shaped PbS nanostructure consists of four symmetric arms in the same plane and demonstrate good crystallinity. With the increase of ethanol concentration, the sensitivity of the PbS sensor significantly increases and demonstrates an almost linear relationship at the optimal operating temperature of 400 deg C. Moreover, the fast response-recovery towards ethanol is also observed, which indicates its great potential on ethanol detection. (author)

Synthesis of star-shaped lead sulfide (PbS) nanomaterials and theirs gas-sensing properties

International Nuclear Information System (INIS)

Song, Chengwen; Sun, Menghan; Yin, Yanyan; Xiao, Jingkun; Dong, Wei; Li, Chen; Zhang, Li

2016-01-01

Star-shaped PbS nanomaterials are synthesized by a hydrothermal method. Morphology and structure of the PbS nanomaterials are analyzed by SEM, HRTEM and XRD. Gas-sensing properties of the as-prepared PbS sensor are also systematically investigated. The results show star-shaped PbS nanostructure consists of four symmetric arms in the same plane and demonstrate good crystallinity. With the increase of ethanol concentration, the sensitivity of the PbS sensor significantly increases and demonstrates an almost linear relationship at the optimal operating temperature of 400 deg C. Moreover, the fast response-recovery towards ethanol is also observed, which indicates its great potential on ethanol detection. (author)

Enhanced visible-light photocatalysis and gas sensor properties of polythiophene supported tin doped titanium nanocomposite

Science.gov (United States)

Chandra, M. Ravi; Siva Prasada Reddy, P.; Rao, T. Siva; Pammi, S. V. N.; Siva Kumar, K.; Vijay Babu, K.; Kiran Kumar, Ch.; Hemalatha, K. P. J.

2017-06-01

The polythiophene supported tin doped titanium nanocomposites (PTh/Sn-TiO2) were synthesized by modified sol-gel process through oxidative polymerization of thiophene. The fourier transform infrared spectroscopy (FT-IR) and UV-Vis diffuse reflectance spectroscopy (UV-DRS) analysis confirms the existence of synergetic interaction between metal oxide and polymer along with extension of absorption edge to visible region. The composites are found to be in spherical form with core-shell structure, which is confirmed by scanning electron spectroscopy (SEM) and transmission electron microscopy (TEM) images, the presence of all respective elements of composite are proven by energy-dispersive X-ray spectroscopy (EDX) analysis. The importance of polythiophene on surface of metal oxide has been were studied as a function of photocatalytic activity for degradation of organic pollutant congo red and gas sensor behavior towards liquid petroleum gas (LPG). All the composites are photocatalytically active and the composite with 1.5 wt% thiophene degrades the pollutant congo red within 120 min when compared to remaining catalysts under visible light irradiation. On the other hand, same composite have shown potential gas sensor properties towards LPG at 300 °C. Considering all the results, it can be noted that polythiophene acts as good sensitizer towards LPG and supporter for the tin doped titania that improve the photocatalytic activity under visible light.

A pore structure model for the gas transport property changes, initial oxidation rates and cumulative weight loss of AGR moderator graphite

International Nuclear Information System (INIS)

Johnson, P.A.V.

1985-09-01

A quantitative model has been developed for the gas transport property variation, cumulative weight loss and initial oxidation rates of AGR moderator graphite. The model utilises the theory of dynamic moments of the pore structure to calculate the changes in physical properties brought about by radiolytic corrosion taking place within the graphite porosity. In order to account for the behaviour of the initial rate curves, and the weight loss data obtained it is necessary to invoke the presence of a group of cylindrical pore and a group of small slab-shaped pores. The latter are methane depleted. This is in addition to the pore group involved in gas transport which is best represented by cylinders of mean radius 2.13 μm. The model satisfactorily predicts the experimental weight loss data obtained from experiments in the DIDO 6V3 and BFB loops. (author)

A study of the cool gas in the Large Magellanic Cloud. I. Properties of the cool atomic phase - a third H i absorption survey

Science.gov (United States)

Marx-Zimmer, M.; Herbstmeier, U.; Dickey, J. M.; Zimmer, F.; Staveley-Smith, L.; Mebold, U.

2000-02-01

The cool atomic interstellar medium of the Large Magellanic Cloud (LMC) seems to be quite different from that in the Milky Way. In a series of three papers we study the properties of the cool atomic hydrogen in the LMC (Paper I), its relation to molecular clouds using SEST-CO-observations (Paper II) and the cooling mechanism of the atomic gas based on ISO-[\\CII]-investigations (Paper III). In this paper we present the results of a third 21 cm absorption line survey toward the LMC carried out with the Australia Telescope Compact Array (ATCA). 20 compact continuum sources, which are mainly in the direction of the supergiant shell LMC 4, toward the surroundings of 30 Doradus and toward the eastern steep \\HI\\ boundary, have been chosen from the 1.4 GHz snapshot continuum survey of Marx et al. We have identified 20 absorption features toward nine of the 20 sources. The properties of the cool \\HI\\ clouds are investigated and are compared for the different regions of the LMC taking the results of Dickey et al. (survey 2) into account. We find that the cool \\HI\\ gas in the LMC is either unusually abundant compared to the cool atomic phase of the Milky Way or the gas is clearly colder (\\Tc\\ ~ 30 K) than that in our Galaxy (\\Tc\\ ~ 60 K). The properties of atomic clouds toward 30 Doradus and LMC 4 suggest a higher cooling rate in these regions compared to other parts of the LMC, probably due to an enhanced pressure near the shock fronts of LMC 4 and 30 Doradus. The detected cool atomic gas toward the eastern steep \\HI\\ boundary might be the result of a high compression of gas at the leading edge. The Australia Telescope is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO.

Nonlinear dynamics of a soliton gas: Modified Korteweg–de Vries equation framework

Energy Technology Data Exchange (ETDEWEB)

Shurgalina, E.G., E-mail: eshurgalina@mail.ru [Department of Nonlinear Geophysical Processes, Institute of Applied Physics of the Russian Academy of Sciences, Nizhny Novgorod (Russian Federation); Pelinovsky, E.N. [Department of Nonlinear Geophysical Processes, Institute of Applied Physics of the Russian Academy of Sciences, Nizhny Novgorod (Russian Federation); Department of Applied Mathematics, Nizhny Novgorod State Technical University, Nizhny Novgorod (Russian Federation)

2016-05-27

Dynamics of random multi-soliton fields within the framework of the modified Korteweg–de Vries equation is considered. Statistical characteristics of a soliton gas (distribution functions and moments) are calculated. It is demonstrated that the results sufficiently depend on the soliton gas properties, i.e., whether it is unipolar or bipolar. It is shown that the properties of a unipolar gas are qualitatively similar to the properties of a KdV gas [Dutykh and Pelinovsky (2014) [1

Effect of helium plasma gas flow rate on the properties of WC-12 wt.%Co coatings sprayed by atmospheric plasma

Directory of Open Access Journals (Sweden)

Mihailo R. Mrdak

2014-06-01

Full Text Available The cermet coatings of WC-12wt.%Co are extensively used to improve the wear resistance of a wide range of technical components. This paper analyses the influence of the plasma gas flow of helium on the microstructure and mechanical properties of WC-12wt.%Co coatings deposited by plasma spraying at atmospheric pressure (APS. In order to obtain homogeneous and denser coatings, three different flows of He ( 8 l/min., 16 l/min. and 32 l/min were used in the research. With the application of He, coatings achieved higher values of hardness due to less degradation of the primary WC carbides. The main goal was to deposit dense and homogeneous layers of WC-12wt.%Co coatings with improved wear resistance for different applications. The test results of the microstructure of the layers were evaluated under a light microscope. The analysis of the microstructure and the mechanical properties of the deposited layers was made in accordance with the standard of Pratt-Whitney. The morphology of the powder particles and the microstructure of the best coating was examined on the SEM (scanning electron microscope. The evaluation of the mechanical properties of the layers was done by applying the HV0.3 method for microhardness testing and by applying tensile testing to test the bond strength. The research has shown that the flow of He plasma gas significantly affects the microstructure, the mechanical properties and the structure of WC-12 wt.%Co coatings.

A novel zinc(II) metal–organic framework with a diamond-like structure: synthesis, study of thermal robustness and gas adsorption properties

Czech Academy of Sciences Publication Activity Database

Almáši, M.; Zeleňák, V.; Zukal, Arnošt; Kuchár, J.; Čejka, Jiří

2016-01-01

Roč. 45, č. 3 (2016), s. 1233-1242 ISSN 1477-9226 R&D Projects: GA ČR GA14-07101S Institutional support: RVO:61388955 Keywords : synthesis * gas adsorption properties * physical chemistry Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.029, year: 2016

Cellular properties of slug flow in vertical co-current gas-liquid flow: slug-churn transition

International Nuclear Information System (INIS)

Lusseyran, Francois

1990-01-01

This research thesis reports the study and description of the structure of a slug flow regime in a co-current vertical cylindrical duct, and the characterization and prediction of its transition towards a slug-churn (de-structured) regime. Flow physical mechanisms highlighted by the measurement of two important dynamics variables (wall friction and thickness of liquid films) are related to hypotheses of cellular models. The author first proposes an overview of slug flow regimes: theoretical steady and one-dimensional analysis, mass assessment equations of cellular models, application to the assessment of the flow rate and of the thickness of the film surrounding the gas slug. In the second part, the author addresses the slug flow regime transition towards the slug-churn regime: assessment of the evolution of flow dynamic properties, use of average wall friction analysis to obtain a relevant transition criterion. The third part presents experimental conditions, and measurement methods: conductometry for thickness measurement, polarography for wall friction measurement, and gas phase detection by using an optic barrier or optic fibres [fr

Investigation of gas molecules adsorption on carbon nano tubes electric properties in tight binding model

International Nuclear Information System (INIS)

Moradian, R.; Mohammadi, Y.

2007-01-01

Based on tight binding model we investigated effects of bi-atomic molecules gas(in the general form denoted by X 2 )on single-walled carbon nano tubes electronic properties. We found for some specified values of hopping integrals and random on-site energies, adsorbed molecules bound states located inside of the (10,0) single-walled carbon nano tubes energy gap, where it is similar to the reported experimental results for O 2 adsorption while for other values there is no bound states inside of energy gap. This is similar to the N 2 adsorption on semiconductor single-walled carbon nano tubes.

Research of Acoustic Properties of Materials with the Purpose of Their Use at Design of Special Noise Protective Clothes for Oil and Gas Industry

Science.gov (United States)

Drofa, E. A.; Lipilina, E. Yu

2018-01-01

The article is devoted to the substantiation of the choice of a rational package of materials, which has the greatest noise-protective properties when designing special clothes with reference to the oil and gas industry. Studies were conducted to assess the factors that have the most significant effect on the noise-protective properties of clothing. Conclusions are made about the possibility of using the developed technique for studying the noise-protective properties of materials in selecting rational packages of materials for the production of special clothes with high noise-protective properties.

Influence of Nitrogen Gas Flow Rate on The Microstructural and Mechanical Properties of Tin Deposited Carbon Steel Synthesized by Cae

Directory of Open Access Journals (Sweden)

A. Mubarak

2017-11-01

Full Text Available This paper reports on the preparation of titanium nitride (TiN thin films on carbon steel plates, using cathodic arc evaporation CAE PVD technique. We studied and discussed the effect of various nitrogen gas flow rates on microstructural and mechanical properties of TiN-coated carbon steel plates. The coating properties investigated in this work included the surface morphology, thickness of deposited coating, adhesion between the coating and substrate, coating composition, coating crystallography, hardness and surface characterization using a field emission scanning electron microscope (FE-SEM with energy dispersive X-ray (EDX, Xray diffraction (XRD with glazing incidence angle (GIA technique, scratch tester, hardness testing machine, surface roughness tester and atomic force microscope (AFM. SEM analyses showed that all the films had columnar and dense structures with clearly defined substrate-film interfacial layers. The hardness of TiN-coated carbon steel was noted six times more than the hardness of uncoated one. An increase in nitrogen gas flow rate showed; decrease in the formation of macro-droplets, average roughness (Ra and root-mean-square (RMS values in CAE PVD technique. During XRD-GIA studies, it was observed that by increasing the nitrogen gas flow rate, the main peak [1,1,1] shifted toward the lower angular position. Microhardness of TiN-coated carbon steel showed about six times increase in hardness than the uncoated one. Scratch tester results showed an average adhesion between the coating material and substrate. Thanks to the high resolution power could be observed that by increasing nitrogen gas flow rate there was percentage increase in the bearing ratio while percentage decrease in histogram.

Fundamentals of gas dynamics

CERN Document Server

Babu, V

2014-01-01

Fundamentals of Gas Dynamics, Second Edition isa comprehensively updated new edition and now includes a chapter on the gas dynamics of steam. It covers the fundamental concepts and governing equations of different flows, and includes end of chapter exercises based on the practical applications. A number of useful tables on the thermodynamic properties of steam are also included.Fundamentals of Gas Dynamics, Second Edition begins with an introduction to compressible and incompressible flows before covering the fundamentals of one dimensional flows and normal shock wav

Research on the separation properties of empty-column gas chromatography (EC-GC) and conditions for simulated distillation (SIMDIS).

Science.gov (United States)

Boczkaj, Grzegorz; Kamiński, Marian

2013-10-01

Previous studies have revealed it is possible to separate a high-boiling mixture by gas chromatography in empty fused-silica capillary tubing rather than in columns coated with stationary phase. Chromatographic separation occurs solely on the basis of the different boiling points of the substances separated. The high similarity of such separations to those in classic distillation seems advantageous when gas chromatography is used for simulated distillation. This paper presents results from further research on the separation properties of empty fused silica tubing. The efficiency of this chromatographic system has been examined. The usefulness of such conditions has been studied for simulated distillation, i.e. to determine the boiling-point distribution of complex mixtures, mainly petroleum fractions and products, on the basis of their retention relative to reference substances. The results obtained by use of empty-column gas chromatography (EC-GC) and by use of classical simulated distillation columns have been compared for solutes of different polarity. Studies revealed boiling points determined by EC-GC were more accurate than those obtained by the standard method of simulated distillation.

Natural gas hydrates. Experimental techniques and their applications

Energy Technology Data Exchange (ETDEWEB)

Ye, Yuguang; Liu, Changling (eds.) [Qingdao Institute of Marine Geology (China). Gas Hydrate Laboratory

2013-07-01

Focuses on gas hydrate experiment in laboratory. Intends to provide practical significant parameters for gas hydrate exploration and exploitation in the oceanic and permafrost environments. Consists of different themes that present up-to-date information on hydrate experiments. ''Natural Gas Hydrates: Experimental Techniques and Their Applications'' attempts to broadly integrate the most recent knowledge in the fields of hydrate experimental techniques in the laboratory. The book examines various experimental techniques in order to provide useful parameters for gas hydrate exploration and exploitation. It provides experimental techniques for gas hydrates, including the detection techniques, the thermo-physical properties, permeability and mechanical properties, geochemical abnormalities, stability and dissociation kinetics, exploitation conditions, as well as modern measurement technologies etc.

Disentangling effects of key coarse woody debris fuel properties on its combustion, consumption and carbon gas emissions during experimental laboratory fire

NARCIS (Netherlands)

Zhao, Weiwei; van Logtestijn, Richard S.P.; van der Werf, Guido R.; van Hal, Jurgen R.; Cornelissen, Johannes H.C.

2018-01-01

Coarse woody debris is a key terrestrial carbon pool, and its turnover through fire plays a fundamental role in global carbon cycling. Coarse dead wood fuel properties, which vary between tree species and wood decay stages, might affect its combustion, consumption and carbon gas emissions during

Analysis of a multicomponent gas absorption system with carrier gas coabsorption

International Nuclear Information System (INIS)

Merriman, J.R.

1975-03-01

Conventional integrated versions of the packed gas absorber design equations do not account for significant coabsorption of the carrier gas along with the dilute transferring species. These equations, as a result, also neglect the relationship between dilute component transfer and carrier gas coabsorption. In the absorption of Kr and Xe from various carrier gases, using CCl 2 F 2 as the process solvent, carrier coabsorption is substantial. Consequently, a design package was developed to deal with multicomponent gas absorption in systems characterized by carrier gas coabsorption. Developed within the general film theory framework, the basic feature of this design approach is a view of dilute component mass-transfer as a conventional diffusive transfer superimposed on a net flux caused by carrier absorption. Other supporting elements of the design package include predictive techniques for various fluid properties, estimating procedures for carrier gas equilibrium constants, and correlations for carrier gas and dilute gas mass-transfer coefficients. When applied to systems using CCl 2 F 2 as the solvent; He, N 2 , air, or Ar as the carrier gas; and Kr or Xe as the dilute gas; the design approach gave good results, even when extended to conditions well beyond those of its development. (U.S.)

Pure- and Mixed-Gas Transport Study of Nafion® and Its Fe3+-Substituted Derivative for Membrane-Based Natural Gas Applications

KAUST Repository

Mukaddam, Mohsin Ahmed

2016-01-01

The focus of this research project was to develop a fundamental understanding of the structure-gas transport property relationship in Nafion® to investigate its potential use as a gas separation membrane material for natural gas (NG) applications

Performance Evaluations and Quality Validation System for Optical Gas Imaging Cameras That Visualize Fugitive Hydrocarbon Gas Emissions

Science.gov (United States)

Optical gas imaging (OGI) cameras have the unique ability to exploit the electromagnetic properties of fugitive chemical vapors to make invisible gases visible. This ability is extremely useful for industrial facilities trying to mitigate product losses from escaping gas and fac...

Argon: Systematic Review on Neuro- and Organoprotective Properties of an “Inert” Gas

Directory of Open Access Journals (Sweden)

Anke Höllig

2014-10-01

Full Text Available Argon belongs to the group of noble gases, which are regarded as chemically inert. Astonishingly some of these gases exert biological properties and during the last decades more and more reports demonstrated neuroprotective and organoprotective effects. Recent studies predominately use in vivo or in vitro models for ischemic pathologies to investigate the effect of argon treatment. Promising data has been published concerning pathologies like cerebral ischemia, traumatic brain injury and hypoxic ischemic encephalopathy. However, models applied and administration of the therapeutic gas vary. Here we provide a systematic review to summarize the available data on argon’s neuro- and organoprotective effects and discuss its possible mechanism of action. We aim to provide a summary to allow further studies with a more homogeneous setting to investigate possible clinical applications of argon.

A review of helium gas turbine technology for high-temperature gas-cooled reactors

International Nuclear Information System (INIS)

No, Hee Cheon; Kim, Ji Hwan; Kim, Hyeun Min

2007-01-01

Current High-Temperature Gas-cooled Reactors (HTGRs) are based on a closed brayton cycle with helium gas as the working fluid. Thermodynamic performance of the axial-flow helium gas turbines is of critical concern as it considerably affects the overall cycle efficiency. Helium gas turbines pose some design challenges compared to steam or air turbomachinery because of the physical properties of helium and the uniqueness of the operating conditions at high pressure with low pressure ratio. This report present a review of the helium Brayton cycle experiences in Germany and in Japan. The design and availability of helium gas turbines for HTGR are also presented in this study. We have developed a new throughflow calculation code to calculate the design-point performance of helium gas turbines. Use of the method has been illustrated by applying it to the GTHTR300 reference

THERMODYNAMIC MODEL OF GAS HYDRATES

OpenAIRE

Недоступ, В. И.; Недоступ, О. В.

2015-01-01

The interest to gas hydrates grows last years. Therefore working out of reliable settlement-theoretical methods of definition of their properties is necessary. The thermodynamic model of gas hydrates in which the central place occupies a behaviour of guest molecule in cell is described. The equations of interaction of molecule hydrate formative gas with cell are received, and also an enthalpy and energy of output of molecule from a cell are determined. The equation for calculation of thermody...

Spatial separation of electrons and holes for enhancing the gas-sensing property of a semiconductor: ZnO/ZnSnO3 nanorod arrays prepared by a hetero-epitaxial growth

Science.gov (United States)

Wang, Ying; Gao, Peng; Sha, Linna; Chi, Qianqian; Yang, Lei; Zhang, Jianjiao; Chen, Yujin; Zhang, Milin

2018-04-01

The construction of semiconductor composites is known as a powerful method used to realize the spatial separation of electrons and the holes in them, which can result in more electrons or holes and increase the dispersion of oxygen ions ({{{{O}}}2}- and O - ) (one of the most critical factors for their gas-sensing properties) on the surface of the semiconductor gas sensor. In this work, using 1D ZnO/ZnSnO3 nanoarrays as an example, which are prepared through a hetero-epitaxial growing process to construct a chemically bonded interface, the above strategy to attain a better semiconductor gas-sensing property has been realized. Compared with single ZnSnO3 nanotubes and no-matching ZnO/ZnSnO3 nanoarrays gas sensors, it has been proven by x-ray photoelectron spectroscopy and photoluminescence spectrum examination that the as-obtained ZnO/ZnSnO3 sensor showed a greatly increased quantity of active surface electrons with exceptional responses to trace target gases and much lower optimum working temperatures (less than about 170 °C). For example, the as-obtained ZnO/ZnSnO3 sensor exhibited an obvious response and short response/recovery time (less than 10 s) towards trace H2S gas (a detection limit down to 700 ppb). The high responses and dynamic repeatability observed in these sensors reveal that the strategy based on the as-presented electron and hole separation is reliable for improving the gas-sensing properties of semiconductors.

Gas Sensors Based on Electrodeposited Polymers

Directory of Open Access Journals (Sweden)

Boris Lakard

2015-07-01

Full Text Available Electrochemically deposited polymers, also called “synthetic metals”, have emerged as potential candidates for chemical sensing due to their interesting and tunable chemical, electrical, and structural properties. In particular, most of these polymers (including polypyrrole, polyaniline, polythiophene and their derivatives can be used as the sensitive layer of conductimetric gas sensors because of their conducting properties. An important advantage of polymer-based gas sensors is their efficiency at room temperature. This characteristic is interesting since most of the commercially-available sensors, usually based on metal oxides, work at high temperatures (300–400 °C. Consequently, polymer-based gas sensors are playing a growing role in the improvement of public health and environment control because they can lead to gas sensors operating with rapid detection, high sensitivity, small size, and specificity in atmospheric conditions. In this review, the recent advances in electrodeposited polymer-based gas sensors are summarized and discussed. It is shown that the sensing characteristics of electrodeposited polymers can be improved by chemical functionalization, nanostructuration, or mixing with other functional materials to form composites or hybrid materials.

Hot Gas Halos in Galaxies

Science.gov (United States)

Mulchaey, John

Most galaxy formation models predict that massive low-redshift disk galaxies are embedded in extended hot halos of externally accreted gas. Such gas appears necessary to maintain ongoing star formation in isolated spirals like the Milky Way. To explain the large population of red galaxies in rich groups and clusters, most galaxy evolution models assume that these hot gas halos are stripped completely when a galaxy enters a denser environment. This simple model has been remarkably successful at reproducing many observed properties of galaxies. Although theoretical arguments suggest hot gas halos are an important component in galaxies, we know very little about this gas from an observational standpoint. In fact, previous observations have failed to detect soft X-ray emission from such halos in disk galaxies. Furthermore, the assumption that hot gas halos are stripped completely when a galaxy enters a group or cluster has not been verified. We propose to combine proprietary and archival XMM-Newton observations of galaxies in the field, groups and clusters to study how hot gas halos are impacted by environment. Our proposed program has three components: 1) The deepest search to date for a hot gas halo in a quiescent spiral galaxy. A detection will confirm a basic tenet of disk galaxy formation models, whereas a non-detection will seriously challenge these models and impose new constraints on the growth mode and feedback history of disk galaxies. 2) A detailed study of the hot gas halos properties of field early-type galaxies. As environmental processes such as stripping are not expected to be important in the field, a study of hot gas halos in this environment will allow us to better understand how feedback and other internal processes impact hot gas halos. 3) A study of hot gas halos in the outskirts of groups and clusters. By comparing observations with our suite of simulations we can begin to understand what role the stripping of hot gas halos plays in galaxy

Magnesium ferrite nanoparticles: a rapid gas sensor for alcohol

Science.gov (United States)

Godbole, Rhushikesh; Rao, Pratibha; Bhagwat, Sunita

2017-02-01

Highly porous spinel MgFe2O4 nanoparticles with a high specific surface area have been successfully synthesized by a sintering free auto-combustion technique and characterized for their structural and surface morphological properties using XRD, BET, TEM and SEM techniques. Their sensing properties to alcohol vapors viz. ethanol and methanol were investigated. The site occupation of metal ions was investigated by VSM. The as-synthesized sample shows the formation of sponge-like porous material which is necessary for gas adsorption. The gas sensing characteristics were obtained by measuring the gas response as a function of operating temperature, concentration of the gas, and the response-recovery time. The response of magnesium ferrite to ethanol and methanol vapors was compared and it was revealed that magnesium ferrite is more sensitive and selective to ethanol vapor. The sensor operates at a substantially low vapor concentration of about 1 ppm of alcohol vapors, exhibits fantastic response reproducibility, long term reliability and a very fast response and recovery property. Thus the present study explored the possibility of making rapidly responding alcohol vapor sensor based on magnesium ferrite. The sensing mechanism has been discussed in co-relation with magnetic and morphological properties. The role of occupancy of Mg2+ ions in magnesium ferrite on its gas sensing properties has also been studied and is found to influence the response of magnesium ferrite ethanol sensor.

Ammonia Gas Sensing Properties of Nanocrystalline Zn1-xCuxFe2O4 Doped with Noble Metal

Directory of Open Access Journals (Sweden)

S. V. JAGTAP

2010-11-01

Full Text Available The sensors are required basically for monitoring of trace gases in environment. In order to detect, measure and control these gases; one should know the amount and type of gases present in the environment. Among the most toxic and hazardous gases, it is necessary to detect and monitor the ammonia gas because this is enhance in the agricultural sector by the addition of large amounts of NH3 to cultivated farmland in the form of fertilizers. Nanocrystalline spinel type Zn1-xCuxFe2O4 (x=0, 0.2, 0.4 0.6 & 0.8 has been synthesized by sol-gel citrate method. The synthesized powders were characterized by XRD and SEM. The results revealed that the particle size is in the range of 40–45 nm for Cu–Zn ferrite with good crystallinity. The gas sensing properties were studied towards reducing gases like CO, LPG, NH3 and H2S and it is observed that Cu–Zn ferrite shows high response to ammonia gas at relatively lower operating temperature. The Zn0.6Cu0.4Fe2O4 nanomaterial shows better sensitivity towards NH3 gas at an operating temperature 300 0C. Incorporation of Pd improved the sensitivity, selectivity, response time and reduced the operating temperature from 300 0C to 250 0C for NH3 sensor.

Simulating the physical properties of dark matter and gas inside the cosmic web

Science.gov (United States)

Dolag, K.; Meneghetti, M.; Moscardini, L.; Rasia, E.; Bonaldi, A.

2006-08-01

Using the results of a high-resolution, cosmological hydrodynamical re-simulation of a supercluster-like region, we investigate the physical properties of the gas located along the filaments and bridges which constitute the so-called cosmic web. First, we analyse the main characteristics of the density, temperature and velocity fields, which have quite different distributions, reflecting the complex dynamics of the structure-formation process. Then we quantify the signals which originate from the matter in the filaments by considering different observables. Inside the cosmic web, we find that the halo density is about 10-14 times larger than cosmic mean; the bremsstrahlung X-ray surface brightness reaches at most 10-16 erg s-1 cm-2 arcmin-2 the Compton-y parameter due to the thermal Sunyaev-Zel'dovich effect is about 10-6 the reduced shear produced by the weak lensing effect is ~0.01-0.02. These results confirm the difficulty of an observational detection of the cosmic web. Finally, we find that projection effects of the filamentary network can affect the estimates of the properties of single clusters, increasing their X-ray luminosity by less than 10 per cent and their central Compton-y parameter by up to 30 per cent.

REVEALING THE PHYSICAL PROPERTIES OF MOLECULAR GAS IN ORION WITH A LARGE-SCALE SURVEY IN J = 2-1 LINES OF {sup 12}CO, {sup 13}CO, AND C{sup 18}O

Energy Technology Data Exchange (ETDEWEB)

Nishimura, Atsushi; Tokuda, Kazuki; Kimura, Kimihiro; Muraoka, Kazuyuki; Maezawa, Hiroyuki; Ogawa, Hideo; Onishi, Toshikazu [Department of Physical Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan); Dobashi, Kazuhito; Shimoikura, Tomomi [Department of Astronomy and Earth Sciences, Tokyo Gakugei University, 4-1-1 Nukuikita-machi, Koganei, Tokyo 184-8501 (Japan); Mizuno, Akira [Solar-terrestrial Environment Laboratory, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601 (Japan); Fukui, Yasuo, E-mail: atsushi.nishimura@nao.ac.jp [Department of Physics and Astrophysics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602 (Japan)

2015-01-01

We present fully sampled ∼3' resolution images of {sup 12}CO(J = 2-1), {sup 13}CO(J = 2-1), and C{sup 18}O(J = 2-1) emission taken with the newly developed 1.85 m millimeter-submillimeter telescope over the entire area of the Orion A and B giant molecular clouds. The data were compared with J = 1-0 of the {sup 12}CO, {sup 13}CO, and C{sup 18}O data taken with the Nagoya 4 m telescope and the NANTEN telescope at the same angular resolution to derive the spatial distributions of the physical properties of the molecular gas. We explore the large velocity gradient formalism to determine the gas density and temperature using line combinations of {sup 12}CO(J = 2-1), {sup 13}CO(J = 2-1), and {sup 13}CO(J = 1-0) assuming a uniform velocity gradient and abundance ratio of CO. The derived gas density is in the range of 500 to 5000 cm{sup –3}, and the derived gas temperature is mostly in the range of 20 to 50 K along the cloud ridge with a temperature gradient depending on the distance from the star forming region. We found that the high-temperature region at the cloud edge faces the H II region, indicating that the molecular gas is interacting with the stellar wind and radiation from the massive stars. In addition, we compared the derived gas properties with the young stellar objects distribution obtained with the Spitzer telescope to investigate the relationship between the gas properties and the star formation activity therein. We found that the gas density and star formation efficiency are positively well correlated, indicating that stars form effectively in the dense gas region.

Tuning Gas Adsorption Properties of Zeolite-like Supramolecular Assemblies with gis Topology via Functionalization of Isoreticular Metal-Organic Squares.

Science.gov (United States)

Wang, Shuang; Belmabkhout, Youssef; Cairns, Amy J; Li, Guanghua; Huo, Qisheng; Liu, Yunling; Eddaoudi, Mohamed

2017-10-04

A strategy based on metal-ligand directed assembly of metal-organic squares (MOSs), built-up from four-membered ring (4MR) secondary building units (SBUs), has been employed for the design and construction of isoreticular zeolite-like supramolecular assemblies (ZSAs). Four porous Co-based ZSAs having the same underlying gis topology, but differing only with respect to the capping and bridging linkers, were successfully isolated and fully characterized. In this series, each MOS in ZSA-3-ZSA-6 possess an ideal square geometry and is connected to four neighboring MOS via a total of 16 hydrogen bonds to give a 3-periodic porous network.To systematically assess the effect of the pore system (size and functionality) on the gas adsorption properties, we evaluated the MOSs for their affinity for different probe molecules such as CO 2 and light hydrocarbons. ZSA-3-ZSA-6 showed high thermal stability (up to 300 °C) and was proven highly porous as evidenced by gas adsorption studies. Notably, alkyl-functionalized MOSs were found to offer potential for selective separation of CO 2 , C 3 H 6 , and C 3 H 8 from CH 4 and H 2 containing gas stream, such as natural gas and refinery-off gases.

Tuning Gas Adsorption Properties of Zeolite-like Supramolecular Assemblies with gis Topology via Functionalization of Isoreticular Metal–Organic Squares

KAUST Repository

Wang, Shuang

2017-07-11

A strategy based on metal-ligand directed assembly of metal-organic squares (MOSs), built-up from four-membered ring (4MR) secondary building units (SBUs), has been employed for the design and construction of isoreticular zeolite-like supramolecular assemblies (ZSAs). Four porous Co-based ZSAs having the same underlying gis topology, but differing only with respect to the capping and bridging linkers, were successfully isolated and fully characterized. In this series, each MOS in ZSA-3-ZSA-6 possess an ideal square geometry and is connected to four neighboring MOS via a total of 16 hydrogen bonds to give a 3-periodic porous network.To systematically assess the effect of the pore system (size and functionality) on the gas adsorption properties, we evaluated the MOSs for their affinity for different probe molecules such as CO2 and light hydrocarbons. ZSA-3-ZSA-6 showed high thermal stability (up to 300 °C) and was proven highly porous as evidenced by gas adsorption studies. Notably, alkyl-functionalized MOSs were found to offer potential for selective separation of CO2, C3H6, and C3H8 from CH4 and H2 containing gas stream, such as natural gas and refinery-off gases.

The Effects of RF Sputtering Power and Gas Pressure on Structural and Electrical Properties of ITiO Thin Film

Directory of Open Access Journals (Sweden)

Accarat Chaoumead

2012-01-01

Full Text Available Transparent conductive titanium-doped indium oxide (ITiO films were deposited on corning glass substrates by RF magnetron sputtering method. The effects of RF sputtering power and Ar gas pressure on the structural and electrical properties of the films were investigated experimentally, using a 2.5 wt% TiO2-doped In2O3 target. The deposition rate was in the range of around 20~60 nm/min under the experimental conditions of 5~20 mTorr of gas pressure and 220~350 W of RF power. The lowest volume resistivity of 1.2×10−4  Ω-cm and the average optical transmittance of 75% were obtained for the ITiO film, prepared at RF power of 300 W and Ar gas pressure of 15 mTorr. This volume resistivity of 1.2×10−4  Ω-cm is low enough as a transparent conducting layer in various electrooptical devices, and it is comparable with that of ITO or ZnO:Al conducting layer.

STRUCTURAL CHARACTERIZATION AND GAS PERMEATION PROPERTIES OF POLYETHERIMIDE (PEI/ZEOLITIC IMIDAZOLATE (ZIF-11 MIXED MATRIX MEMBRANES

Directory of Open Access Journals (Sweden)

Mehtap Şafak Boroğlu

2016-06-01

Full Text Available In this study, the preparation of polyetherimide (PEI-Ultem1000/ZIF-11 mixed matrix membranes was studied in various ZIF-11 nanoparticles loadings (0, 10, 15, 20, and 30 wt.%. The newly synthesized ZIF-11 nanoparticles with an average particle size of ~280 nm were integrated in PEI membranes as novel mixed matrix membranes (MMMs. The effect of ZIF-11 loading was scrutinised for H2, CO2, and CH4 gas separation performance at 35 °C and 4 bar. The incorporation of ZIF-11 nanoparticles improved the gas permeation properties of the MMMs with an increase in ZIF-11 loading. As the ZIF-11 loading increased up to 20 wt.%, the permeability of H2 and CO2 increased to four times higher than that of the pure polymer. Moderate increase of CH4 permeability was also recorded. At higher loadings above 20 wt.%, the permeability decreased for all gases and the CO2/CH4, and H2/CH4 selectivities increased consistent with the ZIF-11 loading.

Black powder in gas pipelines

Energy Technology Data Exchange (ETDEWEB)

Sherik, Abdelmounam [Saudi Aramco, Dhahran (Saudi Arabia)

2009-07-01

Despite its common occurrence in the gas industry, black powder is a problem that is not well understood across the industry, in terms of its chemical and physical properties, source, formation, prevention or management of its impacts. In order to prevent or effectively manage the impacts of black powder, it is essential to have knowledge of its chemical and physical properties, formation mechanisms and sources. The present paper is divided into three parts. The first part of this paper is a synopsis of published literature. The second part reviews the recent laboratory and field work conducted at Saudi Aramco Research and Development Center to determine the compositions, properties, sources and formation mechanisms of black powder in gas transmission systems. Microhardness, nano-indentation, X-ray Diffraction (XRD), X-ray Fluorescence (XRF) and Scanning Electron Microscopy (SEM) techniques were used to analyze a large number of black powder samples collected from the field. Our findings showed that black powder is generated inside pipelines due to internal corrosion and that the composition of black powder is dependent on the composition of transported gas. The final part presents a summary and brief discussion of various black powder management methods. (author)

Nanostructured Gas Sensors for Health Care: An Overview

Science.gov (United States)

Kaushik, Ajeet; Kumar, Rajesh; Jayant, Rahul Dev; Nair, Madhavan

2015-01-01

Nanostructured platforms have been utilized for fabrication of small, sensitive and reliable gas sensing devices owing to high functionality, enhanced charge transport and electro-catalytic property. As a result of globalization, rapid, sensitive and selective detection of gases in environment is essential for health care and security. Nonmaterial such as metal, metal oxides, organic polymers, and organic-inorganic hybrid nanocomposites exhibit interesting optical, electrical, magnetic and molecular properties, and hence are found potential gas sensing materials. Morphological, electrical, and optical properties of such nanostructures can be tailored via controlling the precursor concentration and synthesis conditions resulting to achieve desired sensing. This review presents applications of nano-enabling gas sensors to detect gases for environment monitoring. The recent update, challenges, and future vision for commercial applications of such sensor are also described here. PMID:26491544

Accurate ab initio potential for the krypton dimer and transport properties of the low-density krypton gas.

Science.gov (United States)

Waldrop, Jonathan M; Song, Bo; Patkowski, Konrad; Wang, Xiaopo

2015-05-28

A new highly accurate potential energy curve for the krypton dimer was constructed using coupled-cluster calculations up to the singles, doubles, triples, and perturbative quadruples level, including corrections for core-core and core-valence correlation and for relativistic effects. The ab initio data points were fitted to an analytic potential which was used to compute the most important transport properties of the krypton gas. The viscosity, thermal conductivity, self-diffusion coefficient, and thermal diffusion factor were calculated by the kinetic theory at low density and temperatures from 116 to 5000 K. The comparisons with literature experimental data as well as with values from other pair potentials indicate that our new potential is superior to all previous ones. The transport property values computed in this work are recommended as standard values over the complete temperature range.

Intestinal

International Nuclear Information System (INIS)

Cardenas, Rene; Haro, Elfa

2002-01-01

The paper present the diagnosic sensitivit of gastro esophagic scintigraphy (GCE) in children with suspiction of gastro esophagic reflux (RGE), as well as to evidence bronchial aspiratin in cases with suspected RGE. There was studied two groups of children: group A: Include 73 childs with documented diagnosis of RGE, by meas of cine esophagography. Group B: Include 22 children with symptoms of suspiction of. (The author)

Synthesis, characterization and gas sensing property of ...

Indian Academy of Sciences (India)

Unknown

et al 2000), drug delivery system (Panda et al 2001) and fuel cells (Gross et al 1998a; Verges et al 2000). It has promising application as a chemical gas sensor (Nagai et al .... apatite biomaterial ceramic was compacted into a pellet of 1⋅0 cm diameter having 0⋅15 cm thickness using poly- vinyl alcohol as binder material.

On the asymptotic preserving property of the unified gas kinetic scheme for the diffusion limit of linear kinetic models

International Nuclear Information System (INIS)

Mieussens, Luc

2013-01-01

The unified gas kinetic scheme (UGKS) of K. Xu et al. (2010) [37], originally developed for multiscale gas dynamics problems, is applied in this paper to a linear kinetic model of radiative transfer theory. While such problems exhibit purely diffusive behavior in the optically thick (or small Knudsen) regime, we prove that UGKS is still asymptotic preserving (AP) in this regime, but for the free transport regime as well. Moreover, this scheme is modified to include a time implicit discretization of the limit diffusion equation, and to correctly capture the solution in case of boundary layers. Contrary to many AP schemes, this method is based on a standard finite volume approach, it does neither use any decomposition of the solution, nor staggered grids. Several numerical tests demonstrate the properties of the scheme

Nano-Hydroxyapatite Thick Film Gas Sensors

International Nuclear Information System (INIS)

Khairnar, Rajendra S.; Mene, Ravindra U.; Munde, Shivaji G.; Mahabole, Megha P.

2011-01-01

In the present work pure and metal ions (Co and Fe) doped hydroxyapatite (HAp) thick films have been successfully utilized to improve the structural, morphological and gas sensing properties. Nanocrystalline HAp powder is synthesized by wet chemical precipitation route, and ion exchange process is employed for addition of Co and Fe ions in HAp matrix. Moreover, swift heavy ion irradiation (SHI) technique is used to modify the surface of pure and metal ion exchanged HAp with various ion fluence. The structural investigation of pure and metal ion exchanged HAp thick films are carried out using X-ray diffraction and the presence of functional group is observed by means FTIR spectroscopy. Furthermore, surface morphology is visualized by means of SEM and AFM analysis. CO gas sensing study is carried out for, pure and metal ions doped, HAp thick films with detail investigation on operating temperature, response/recovery time and gas uptake capacity. The surface modifications of sensor matrix by SHI enhance the gas response, response/recovery and gas uptake capacity. The significant observation is here to note that, addition of Co and Fe in HAp matrix and surface modification by SHI improves the sensing properties of HAp films drastically resulting in gas sensing at relatively lower temperatures.

Micro–macro-characterisation and modelling of mechanical properties of gas metal arc welded (GMAW) DP600 steel

Energy Technology Data Exchange (ETDEWEB)

Ramazani, A., E-mail: ali.ramazani@iehk.rwth-aachen.de [Department of Ferrous Metallurgy, RWTH Aachen University, D-52072 Aachen (Germany); Mukherjee, K. [Department of Ferrous Metallurgy, RWTH Aachen University, D-52072 Aachen (Germany); Abdurakhmanov, A. [Welding and Joining Institute, RWTH Aachen University, D-52072 Aachen (Germany); Prahl, U. [Department of Ferrous Metallurgy, RWTH Aachen University, D-52072 Aachen (Germany); Schleser, M.; Reisgen, U. [Welding and Joining Institute, RWTH Aachen University, D-52072 Aachen (Germany); Bleck, W. [Department of Ferrous Metallurgy, RWTH Aachen University, D-52072 Aachen (Germany)

2014-01-01

Dual-phase (DP) steels show combined high strength and adequate formability. However, during welding, their microstructural feature of dispersion of hard martensite islands in the soft ferrite matrix is lost and the properties deteriorate. The current research aims to study the mechanical properties of the welded joint, taking into account the effect of features of all regions, such as microstructure, chemical composition and the area fraction, on the macroscopic mechanical properties of the welded joint. Hot rolled DP 600 steel was gas metal arc welded (GMAW) and tensile specimens were made with a welded joint. In the heat-affected zone (HAZ), the microstructure varied from bainite to coarse grained ferrite and tempered martensite. Chemical composition of every quantified region in the welded specimen was also identified using electron probe microanalysis (EPMA). Macromechanical FE modelling was employed to simulate the mechanical properties of the welded tensile specimen. 2D representative volume elements (RVE) for different parts of the welded region were constructed from real microstructure. 2D simulated flow curves were corrected to 3Ds using a developed correlation factor. Finally, the tensile test of welded material with inhomogeneous morphology was simulated and good agreement between experimental and predicted flow curve was achieved.

Micro–macro-characterisation and modelling of mechanical properties of gas metal arc welded (GMAW) DP600 steel

International Nuclear Information System (INIS)

Ramazani, A.; Mukherjee, K.; Abdurakhmanov, A.; Prahl, U.; Schleser, M.; Reisgen, U.; Bleck, W.

2014-01-01

Dual-phase (DP) steels show combined high strength and adequate formability. However, during welding, their microstructural feature of dispersion of hard martensite islands in the soft ferrite matrix is lost and the properties deteriorate. The current research aims to study the mechanical properties of the welded joint, taking into account the effect of features of all regions, such as microstructure, chemical composition and the area fraction, on the macroscopic mechanical properties of the welded joint. Hot rolled DP 600 steel was gas metal arc welded (GMAW) and tensile specimens were made with a welded joint. In the heat-affected zone (HAZ), the microstructure varied from bainite to coarse grained ferrite and tempered martensite. Chemical composition of every quantified region in the welded specimen was also identified using electron probe microanalysis (EPMA). Macromechanical FE modelling was employed to simulate the mechanical properties of the welded tensile specimen. 2D representative volume elements (RVE) for different parts of the welded region were constructed from real microstructure. 2D simulated flow curves were corrected to 3Ds using a developed correlation factor. Finally, the tensile test of welded material with inhomogeneous morphology was simulated and good agreement between experimental and predicted flow curve was achieved

Competitive adsorption of a two-component gas on a deformable adsorbent

International Nuclear Information System (INIS)

Usenko, A S

2014-01-01

We investigate the competitive adsorption of a two-component gas on the surface of an adsorbent whose adsorption properties vary due to the adsorbent deformation. The essential difference of adsorption isotherms for a deformable adsorbent both from the classical Langmuir adsorption isotherms of a two-component gas and from the adsorption isotherms of a one-component gas is obtained, taking into account variations in the adsorption properties of the adsorbent in adsorption. We establish bistability and tristability of the system caused by variations in adsorption properties of the adsorbent in competitive adsorption of gas particles on it. We derive conditions under which adsorption isotherms of a binary gas mixture have two stable asymptotes. It is shown that the specific features of the behavior of the system under study can be described in terms of a potential of the known explicit form. (paper)

Synthetic CO, H2 and H I surveys of the second galactic quadrant, and the properties of molecular gas

Science.gov (United States)

Duarte-Cabral, A.; Acreman, D. M.; Dobbs, C. L.; Mottram, J. C.; Gibson, S. J.; Brunt, C. M.; Douglas, K. A.

2015-03-01

We present CO, H2, H I and HISA (H I self-absorption) distributions from a set of simulations of grand design spirals including stellar feedback, self-gravity, heating and cooling. We replicate the emission of the second galactic quadrant by placing the observer inside the modelled galaxies and post-process the simulations using a radiative transfer code, so as to create synthetic observations. We compare the synthetic data cubes to observations of the second quadrant of the Milky Way to test the ability of the current models to reproduce the basic chemistry of the Galactic interstellar medium (ISM), as well as to test how sensitive such galaxy models are to different recipes of chemistry and/or feedback. We find that models which include feedback and self-gravity can reproduce the production of CO with respect to H2 as observed in our Galaxy, as well as the distribution of the material perpendicular to the Galactic plane. While changes in the chemistry/feedback recipes do not have a huge impact on the statistical properties of the chemistry in the simulated galaxies, we find that the inclusion of both feedback and self-gravity are crucial ingredients, as our test without feedback failed to reproduce all of the observables. Finally, even though the transition from H2 to CO seems to be robust, we find that all models seem to underproduce molecular gas, and have a lower molecular to atomic gas fraction than is observed. Nevertheless, our fiducial model with feedback and self-gravity has shown to be robust in reproducing the statistical properties of the basic molecular gas components of the ISM in our Galaxy.

Candidate eco-friendly gas mixtures for MPGDs

Science.gov (United States)

Benussi, L.; Bianco, S.; Saviano, G.; Muhammad, S.; Piccolo, D.; Ferrini, M.; Parvis, M.; Grassini, S.; Colafranceschi, S.; Kjølbro, J.; Sharma, A.; Yang, D.; Chen, G.; Ban, Y.; Li, Q.

2018-02-01

Modern gas detectors for detection of particles require F-based gases for optimal performance. Recent regulations demand the use of environmentally unfriendly F-based gases to be limited or banned. This review studies properties of potential eco-friendly gas candidate replacements.

Gas distribution effects on waste properties: Viscosities of bubbly slurries

International Nuclear Information System (INIS)

Gauglitz, P.A.; Shah, R.R.; Davis, R.L.

1994-09-01

The retention and episodic release of flammable gases are critical safety concerns for double-shell tanks that contain waste slurries. The rheological behavior of the waste, particularly of the settled sludge, is critical to characterizing the tendency of the waste to retain gas bubbles. The presence of gas bubbles is expected to affect the rheology of the sludge, but essentially no literature data are available to assess the effect of bubbles. Accordingly, the objectives of this study are to develop models for the effect of gas bubbles on the viscosity of a particulate slurry, develop an experimental method (capillary rheometer), collect data on the viscosity of a bubbly slurry, and develop a theoretical basis for interpreting the experimental data from the capillary rheometer

The gas content in starburst galaxies

International Nuclear Information System (INIS)

Mirabel, I.F.; Sanders, D.B.

1987-01-01

The results from two large and homogeneous surveys, one in HI, the other in CO, are used for a statistical review of the gaseous properties of bright infrared galaxies. A constant ratio between the thermal far-infrared radiation and non-thermal radio emission is a universal property of star formation in spiral galaxies. The current rate of star formation in starburst galaxies is found to be 3-20 times larger than in the Milky Way. Galaxies with the higher far-infrared luminosities and warmer dust, have the larger mass fractions of molecular to atomic interstellar gas, and in some instances, striking deficiencies of neutral hydrogen are found. A statistical blueshift of the optical systemic velocities relative to the radio systemic velocities, may be due to an outward motion of the optical line-emitting gas. From the high rates of star formation, and from the short times required for the depletion of the interstellar gas, we conclude that the most luminous infrared galaxies represent a brief but important phase in the evolution of some galaxies, when two galaxies merge changing substantially their overall properties

CONSTRAINING DUST AND MOLECULAR GAS PROPERTIES IN Lyα BLOBS AT z ∼ 3

International Nuclear Information System (INIS)

Yang Yujin; Decarli, Roberto; Walter, Fabian; Leipski, Christian; Dannerbauer, Helmut; Le Floc'h, Emeric; Weiss, Axel; Menten, Karl M.; Dey, Arjun; Chapman, Scott C.; Prescott, Moire K. M.; Neri, Roberto; Borys, Colin; Matsuda, Yuichi; Yamada, Toru; Hayashino, Tomoki; Tapken, Christian

2012-01-01

In order to constrain the bolometric luminosities, dust properties, and molecular gas content of giant Lyα nebulae, the so-called Lyα blobs, we have carried out a study of dust continuum and CO line emission in two well-studied representatives of this population at z ∼ 3: an Lyα blob discovered by its strong Spitzer Multiband Infrared Photometer 24 μm detection (LABd05) and the Steidel blob 1 (SSA22-LAB01). We find that the spectral energy distribution of LABd05 is well described by an active-galactic-nucleus-starburst composite template with L FIR = (4.0 ± 0.5) × 10 12 L ☉ , comparable to high-z submillimeter galaxies and ultraluminous infrared galaxies. New Large APEX Bolometer Camera 870 μm measurements rule out the reported Submillimeter Common-User Bolometer Array detection of the SSA22-LAB01 (S 850μm = 16.8 mJy) at the >4σ level. Consistent with this, ultradeep Plateau de Bure Interferometer observations with ∼2'' spatial resolution also fail to detect any 1.2 mm continuum source down to ≈0.45 mJy beam –1 (3σ). Combined with the existing (sub)millimeter observations in the literature, we conclude that the FIR luminosity of SSA22-LAB01 remains uncertain. No CO line is detected in either case down to integrated flux limits of S ν ΔV ∼ –1 , indicating a modest molecular gas reservoir, M(H 2 ) 10 M ☉ . The non-detections exclude, with high significance (12σ), the previous tentative detection of a CO J = 4-3 line in the SSA22-LAB01. The increased sensitivity afforded by the Atacama Large Millimeter/submillimeter Array will be critical in studying molecular gas and dust in these interesting systems.

A Fine-Tuned MOF for Gas and Vapor Separation: A Multipurpose Adsorbent for Acid Gas Removal, Dehydration, and BTX Sieving

KAUST Repository

Haja Mohideen, Mohamed Infas; Pillai, Renjith S.; Adil, Karim; Bhatt, Prashant; Belmabkhout, Youssef; Shkurenko, Aleksander; Maurin, Guillaume; Eddaoudi, Mohamed

2017-01-01

Summary The development of highly stable separation agents is recognized as a decisive step toward the successful deployment of energy-efficient and cost-effective separation processes. Here, we report the synthesis and construction of a metal-organic framework (MOF), kag-MOF-1, that has adequate structural and chemical features and affords a stable adsorbent with unique and appropriate adsorption properties for gas processing akin to acid gas removal, dehydration, and benzene-toluene-xylene (BTX) sieving. A combination of X-ray diffraction experiments, adsorption studies, mixed-gas breakthrough adsorption column testing, calorimetric measurements, and molecular simulations corroborated the exceptional separation performance of kag-MOF-1 and its prospective use as a multifunctional adsorbent. The unique adsorption properties of kag-MOF-1, resulting from the contracted pore system with aligned periodic array of exposed functionalities, attest to the prominence of this new generation of ultra-microporous material as a prospective practical adsorbent toward cost-effective and more simplified gas and vapor processing flowcharts for natural gas upgrading and flue gas scrubbing.

A Fine-Tuned MOF for Gas and Vapor Separation: A Multipurpose Adsorbent for Acid Gas Removal, Dehydration, and BTX Sieving

KAUST Repository

Haja Mohideen, Mohamed Infas

2017-10-19

Summary The development of highly stable separation agents is recognized as a decisive step toward the successful deployment of energy-efficient and cost-effective separation processes. Here, we report the synthesis and construction of a metal-organic framework (MOF), kag-MOF-1, that has adequate structural and chemical features and affords a stable adsorbent with unique and appropriate adsorption properties for gas processing akin to acid gas removal, dehydration, and benzene-toluene-xylene (BTX) sieving. A combination of X-ray diffraction experiments, adsorption studies, mixed-gas breakthrough adsorption column testing, calorimetric measurements, and molecular simulations corroborated the exceptional separation performance of kag-MOF-1 and its prospective use as a multifunctional adsorbent. The unique adsorption properties of kag-MOF-1, resulting from the contracted pore system with aligned periodic array of exposed functionalities, attest to the prominence of this new generation of ultra-microporous material as a prospective practical adsorbent toward cost-effective and more simplified gas and vapor processing flowcharts for natural gas upgrading and flue gas scrubbing.

Natural gas; Erdgas

Energy Technology Data Exchange (ETDEWEB)

Graf, Frank [DVGW-Forschungsstelle am KIT, Karlsruhe (Germany); Groeschl, Frank; Wetzel, Uwe [DVGW, Bonn (Germany); Heikrodt, Klaus [Hochschule Ostwestfalen-Lippe, Lemgo (Germany); Krause, Hartmut [DBI Gastechnologisches Institut, An-Institut der TU Bergakademie, Freiberg (Germany); Beestermoeller, Christina; Witschen, Bernhard [Team Consult G.P.E. GmbH, Berlin (Germany); Albus, Rolf; Burmeister, Frank [Gas- und Waerme-Institut Essen e.V., Essen (Germany)

2015-07-01

The reform of the EEG in Germany, a positive global development in natural gas, the decline in oil prices, questions about the security of supply in Europe, and not least the effect of the decision by E.on at the end of 2014 have moved the gas industry. Gas has the lowest CO{sub 2} emissions of fossil fuels. Flexibility, storability, useful for networks and the diversity in the application make it an ideal partner for renewable energy. However, these complementary properties are valued at wind and photovoltaics internationally and nationally different. The situation in the gas power plants remains tense. LNG - liquefied natural gas - is on the rise. [German] Die Reform des EEG in Deutschland, eine positive Entwicklung beim Gas weltweit, der Verfall der Oelpreises, Fragen zur Versorgungssicherheit in Europa und nicht zuletzt die Auswirkung der Entscheidung von E.on Ende 2014 haben die Gaswirtschaft bewegt. Gas weist die geringsten CO{sub 2}-Emissioen der fossilen Energietraeger auf. Flexibilitaet, Speicherbarkeit, Netzdienlichkeit sowie die Vielfalt in der Anwendung machen es zum idealen Partner der erneuerbaren Energien. Allerdings werden diese komplementaeren Eigenschaften zu Wind und Photovoltaik international und national unterschiedlich bewertet. Die Lage bei den Gaskraftwerken bleibt weiter angespannt. LNG - verfluessigtes Erdgas - ist auf dem Vormarsch.

Fabrication and gas sensing properties of vertically aligned Si nanowires

Science.gov (United States)

Mirzaei, Ali; Kang, Sung Yong; Choi, Sun-Woo; Kwon, Yong Jung; Choi, Myung Sik; Bang, Jae Hoon; Kim, Sang Sub; Kim, Hyoun Woo

2018-01-01

In this study, a peculiar configuration for a gas sensor consisting of vertically aligned silicon nanowires (VA-Si NWs) synthesized by metal-assisted chemical etching (MACE) is reported. Si NWs were prepared via a facile MACE method and subsequent thermal annealing. Etching was performed by generation of silver nanoparticles (Ag NPs) and subsequent etching in HF/H2O2 aqueous solution; the growth conditions were optimized by changing the process parameters. Highly vertically oriented arrays of Si NWs with a straight-line morphology were obtained, and a top-top electrode configuration was applied. The VA-Si NW gas sensor showed good sensing performance, and the VA-Si NWs exhibited a remarkable response (Rg/Ra = 11.5 ∼ 17.1) to H2 gas (10-50 ppm) at 100 °C which was the optimal working temperature. The formation mechanism and gas sensing mechanism of VA-Si NWs are described. The obtained results can suggest new approaches to making inexpensive, versatile, and portable sensors based on Si NWs having a novel top-top electrode structure that are fully compatible with well-developed Si technologies.

A multiple-location model for natural gas forward curves

International Nuclear Information System (INIS)

Buffington, J.C.

1999-06-01

This thesis presents an approach for financial modelling of natural gas in which connections between locations are incorporated and the complexities of forward curves in natural gas are considered. Apart from electricity, natural gas is the most volatile commodity traded. Its price is often dependent on the weather and price shocks can be felt across several geographic locations. This modelling approach incorporates multiple risk factors that correspond to various locations. One of the objectives was to determine if the model could be used for closed-form option prices. It was suggested that an adequate model for natural gas must consider 3 statistical properties: volatility term structure, backwardation and contango, and stochastic basis. Data from gas forward prices at Chicago, NYMEX and AECO were empirically tested to better understand these 3 statistical properties at each location and to verify if the proposed model truly incorporates these properties. In addition, this study examined the time series property of the difference of two locations (the basis) and determines that these empirical properties are consistent with the model properties. Closed-form option solutions were also developed for call options of forward contracts and call options on forward basis. The options were calibrated and compared to other models. The proposed model is capable of pricing options, but the prices derived did not pass the test of economic reasonableness. However, the model was able to capture the effect of transportation as well as aspects of seasonality which is a benefit over other existing models. It was determined that modifications will be needed regarding the estimation of the convenience yields. 57 refs., 2 tabs., 7 figs., 1 append

Study on the natural gas utilization in the ceramic industry; Estudo sobre a utilizacao do gas natural na industria ceramica

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-07-01

The production, principal applications, characteristics and properties, advantages of the gas natural is showed. A sectorial overview of the ceramic industry and the utilization of the natural gas in the ceramic industry is presented. The expectations are systematized and the impact of the natural gas utilization in the ceramic industry is evaluated. Some conclusions are withdrawn and recommendations suggested.

Influence of Gas Adsorption and Gold Nanoparticles on the Electrical Properties of CVD-Grown MoS2 Thin Films.

Science.gov (United States)

Cho, Yunae; Sohn, Ahrum; Kim, Sujung; Hahm, Myung Gwan; Kim, Dong-Ho; Cho, Byungjin; Kim, Dong-Wook

2016-08-24

Molybdenum disulfide (MoS2) has increasingly attracted attention from researchers and is now one of the most intensively explored atomic-layered two-dimensional semiconductors. Control of the carrier concentration and doping type of MoS2 is crucial for its application in electronic and optoelectronic devices. Because the MoS2 layers are atomically thin, their transport characteristics may be very sensitive to ambient gas adsorption and the resulting charge transfer. We investigated the influence of the ambient gas (N2, H2/N2, and O2) choice on the resistance (R) and surface work function (WF) of trilayer MoS2 thin films grown via chemical vapor deposition. We also studied the electrical properties of gold (Au)-nanoparticle (NP)-coated MoS2 thin films; their R value was found to be 2 orders of magnitude smaller than that for bare samples. While the WF largely varied for each gas, R was almost invariant for both the bare and Au-NP-coated samples regardless of which gas was used. Temperature-dependent transport suggests that variable range hopping is the dominant mechanism for electrical conduction for bare and Au-NP-coated MoS2 thin films. The charges transferred from the gas adsorbates might be insufficient to induce measurable R change and/or be trapped in the defect states. The smaller WF and larger localization length of the Au-NP-coated sample, compared with the bare sample, suggest that more carriers and less defects enhanced conduction in MoS2.

Cluster properties of the one-dimensional lattice gas: the microscopic meaning of grand potential.

Science.gov (United States)

Fronczak, Agata

2013-02-01

Using a concrete example, we demonstrate how the combinatorial approach to a general system of particles, which was introduced in detail in an earlier paper [Fronczak, Phys. Rev. E 86, 041139 (2012)], works and where this approach provides a genuine extension of results obtained through more traditional methods of statistical mechanics. We study the cluster properties of a one-dimensional lattice gas with nearest-neighbor interactions. Three cases (the infinite temperature limit, the range of finite temperatures, and the zero temperature limit) are discussed separately, yielding interesting results and providing alternative proof of known results. In particular, the closed-form expression for the grand partition function in the zero temperature limit is obtained, which results in the nonanalytic behavior of the grand potential, in accordance with the Yang-Lee theory.

Magnetized pair Bose gas: relativistic superconductor

International Nuclear Information System (INIS)

Daicic, J.; Frankel, N.E.; Kowalenko, V.

1993-01-01

The magnetized Bose gas at temperatures above pair threshold is investigated. New magnetization laws are obtained for a wide range of field strengths, and the gas is shown to exhibit the Meissner effect. Some related results for the Fermi gas, a relativistic paramagnet, are also discussed. It is concluded that the pair gases, through the interplay between pair creation, temperature, field strength, statistics and/in the case of fermions/spin, have remarkable magnetic properties. 14 refs

Thermodynamic properties of acid gases in mixture with natural gas and water

NARCIS (Netherlands)

Tang, X.

2011-01-01

The reliable removal of acid gas components, such as carbon dioxide (CO2) and hydrogen sulfide (H2S) from natural gas is an important technical challenge. Crude oil and hydrocarbon gas streams may contain high levels of CO2 and/or H2S as contaminants. It is desirable to prevent any contaminant to

A Review of Carbon Nanotubes-Based Gas Sensors

Directory of Open Access Journals (Sweden)

Yun Wang

2009-01-01

Full Text Available Gas sensors have attracted intensive research interest due to the demand of sensitive, fast response, and stable sensors for industry, environmental monitoring, biomedicine, and so forth. The development of nanotechnology has created huge potential to build highly sensitive, low cost, portable sensors with low power consumption. The extremely high surface-to-volume ratio and hollow structure of nanomaterials is ideal for the adsorption of gas molecules. Particularly, the advent of carbon nanotubes (CNTs has fuelled the inventions of gas sensors that exploit CNTs' unique geometry, morphology, and material properties. Upon exposure to certain gases, the changes in CNTs' properties can be detected by various methods. Therefore, CNTs-based gas sensors and their mechanisms have been widely studied recently. In this paper, a broad but yet in-depth survey of current CNTs-based gas sensing technology is presented. Both experimental works and theoretical simulations are reviewed. The design, fabrication, and the sensing mechanisms of the CNTs-based gas sensors are discussed. The challenges and perspectives of the research are also addressed in this review.

Electron collisions in gas switches

International Nuclear Information System (INIS)

Christophorou, L.G.

1989-01-01

Many technologies rely on the conduction/insulation properties of gaseous matter for their successful operation. Many others (e.g., pulsed power technologies) rely on the rapid change (switching or modulation) of the properties of gaseous matter from an insulator to a conductor and vice versa. Studies of electron collision processes in gases aided the development of pulsed power gas switches, and in this paper we shall briefly illustrate the kind of knowledge on electron collision processes which is needed to optimize the performance of such switching devices. To this end, we shall refer to three types of gas switches: spark gap closing, self-sustained diffuse discharge closing, and externally-sustained diffuse discharge opening. 24 refs., 15 figs., 2 tabs

Animal models of cerebral arterial gas embolism

NARCIS (Netherlands)

Weenink, Robert P.; Hollmann, Markus W.; van Hulst, Robert A.

2012-01-01

Cerebral arterial gas embolism is a dreaded complication of diving and invasive medical procedures. Many different animal models have been used in research on cerebral arterial gas embolism. This review provides an overview of the most important characteristics of these animal models. The properties

Refined potentials for rare gas atom adsorption on rare gas and alkali-halide surfaces

Science.gov (United States)

Wilson, J. W.; Heinbockel, J. H.; Outlaw, R. A.

1985-01-01

The utilization of models of interatomic potential for physical interaction to estimate the long range attractive potential for rare gases and ions is discussed. The long range attractive force is calculated in terms of the atomic dispersion properties. A data base of atomic dispersion parameters for rare gas atoms, alkali ion, and halogen ions is applied to the study of the repulsive core; the procedure for evaluating the repulsive core of ion interactions is described. The interaction of rare gas atoms on ideal rare gas solid and alkali-halide surfaces is analyzed; zero coverage absorption potentials are derived.

Competitive Adsorption of a Two-Component Gas on a Deformable Adsorbent

OpenAIRE

Usenko, A. S.

2013-01-01

We investigate the competitive adsorption of a two-component gas on the surface of an adsorbent whose adsorption properties vary in adsorption due to the adsorbent deformation. The essential difference of adsorption isotherms for a deformable adsorbent both from the classical Langmuir adsorption isotherms of a two-component gas and from the adsorption isotherms of a one-component gas taking into account variations in adsorption properties of the adsorbent in adsorption is obtained. We establi...

Gas sorption properties of zwitterion-functionalized carbon nanotubes

Czech Academy of Sciences Publication Activity Database

Surapathi, A.; Chen, H.-Y.; Marand, E.; Johnson, J. K.; Sedláková, Zdeňka

2013-01-01

Roč. 429, 15 February (2013), s. 88-94 ISSN 0376-7388 R&D Projects: GA MŠk ME09058 Institutional support: RVO:61389013 Keywords : carbon nanotube * zwitterion functionalized membrane * adsorption of gas es Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.908, year: 2013

Effect of heat input on the microstructure and mechanical properties of gas tungsten arc welded AISI 304 stainless steel joints

International Nuclear Information System (INIS)

Kumar, Subodh; Shahi, A.S.

2011-01-01

Highlights: → Welding procedure is established for welding 6 mm thick AISI 304 using GTAW process. → Mechanical properties of the weld joints are influenced strongly by the heat input. → Highest tensile strength of 657.32 MPa is achieved by joints using low heat input. → Welding parameters affect heat input and hence microstructure of weld joints. → Extent of grain coarsening in the HAZ increases with increase in the heat input. -- Abstract: Influence of heat input on the microstructure and mechanical properties of gas tungsten arc welded 304 stainless steel (SS) joints was studied. Three heat input combinations designated as low heat (2.563 kJ/mm), medium heat (2.784 kJ/mm) and high heat (3.017 kJ/mm) were selected from the operating window of the gas tungsten arc welding process (GTAW) and weld joints made using these combinations were subjected to microstructural evaluations and tensile testing so as to analyze the effect of thermal arc energy on the microstructure and mechanical properties of these joints. The results of this investigation indicate that the joints made using low heat input exhibited higher ultimate tensile strength (UTS) than those welded with medium and high heat input. Significant grain coarsening was observed in the heat affected zone (HAZ) of all the joints and it was found that the extent of grain coarsening in the heat affected zone increased with increase in the heat input. For the joints investigated in this study it was also found that average dendrite length and inter-dendritic spacing in the weld zone increases with increase in the heat input which is the main reason for the observable changes in the tensile properties of the weld joints welded with different arc energy inputs.

Recent Developments in 2D Nanomaterials for Chemiresistive-Type Gas Sensors

Science.gov (United States)

Choi, Seon-Jin; Kim, Il-Doo

2018-03-01

Two-dimensional (2D) nanostructures are gaining tremendous interests due to the fascinating physical, chemical, electrical, and optical properties. Recent advances in 2D nanomaterials synthesis have contributed to optimization of various parameters such as physical dimension and chemical structure for specific applications. In particular, development of high performance gas sensors is gaining vast importance for real-time and on-site environmental monitoring by detection of hazardous chemical species. In this review, we comprehensively report recent achievements of 2D nanostructured materials for chemiresistive-type gas sensors. Firstly, the basic sensing mechanism is described based on charge transfer behavior between gas species and 2D nanomaterials. Secondly, diverse synthesis strategies and characteristic gas sensing properties of 2D nanostructures such as graphene, metal oxides, transition metal dichalcogenides (TMDs), metal organic frameworks (MOFs), phosphorus, and MXenes are presented. In addition, recent trends in synthesis of 2D heterostructures by integrating two different types of 2D nanomaterials and their gas sensing properties are discussed. Finally, this review provides perspectives and future research directions for gas sensor technology using various 2D nanomaterials.

Recent Developments in 2D Nanomaterials for Chemiresistive-Type Gas Sensors

Science.gov (United States)

Choi, Seon-Jin; Kim, Il-Doo

2018-05-01

Two-dimensional (2D) nanostructures are gaining tremendous interests due to the fascinating physical, chemical, electrical, and optical properties. Recent advances in 2D nanomaterials synthesis have contributed to optimization of various parameters such as physical dimension and chemical structure for specific applications. In particular, development of high performance gas sensors is gaining vast importance for real-time and on-site environmental monitoring by detection of hazardous chemical species. In this review, we comprehensively report recent achievements of 2D nanostructured materials for chemiresistive-type gas sensors. Firstly, the basic sensing mechanism is described based on charge transfer behavior between gas species and 2D nanomaterials. Secondly, diverse synthesis strategies and characteristic gas sensing properties of 2D nanostructures such as graphene, metal oxides, transition metal dichalcogenides (TMDs), metal organic frameworks (MOFs), phosphorus, and MXenes are presented. In addition, recent trends in synthesis of 2D heterostructures by integrating two different types of 2D nanomaterials and their gas sensing properties are discussed. Finally, this review provides perspectives and future research directions for gas sensor technology using various 2D nanomaterials.

Enhanced Generic Phase-field Model of Irradiation Materials: Fission Gas Bubble Growth Kinetics in Polycrystalline UO2

Energy Technology Data Exchange (ETDEWEB)

Li, Yulan; Hu, Shenyang Y.; Montgomery, Robert O.; Gao, Fei; Sun, Xin

2012-05-30

Experiments show that inter-granular and intra-granular gas bubbles have different growth kinetics which results in heterogeneous gas bubble microstructures in irradiated nuclear fuels. A science-based model predicting the heterogeneous microstructure evolution kinetics is desired, which enables one to study the effect of thermodynamic and kinetic properties of the system on gas bubble microstructure evolution kinetics and morphology, improve the understanding of the formation mechanisms of heterogeneous gas bubble microstructure, and provide the microstructure to macroscale approaches to study their impact on thermo-mechanical properties such as thermo-conductivity, gas release, volume swelling, and cracking. In our previous report 'Mesoscale Benchmark Demonstration, Problem 1: Mesoscale Simulations of Intra-granular Fission Gas Bubbles in UO2 under Post-irradiation Thermal Annealing', we developed a phase-field model to simulate the intra-granular gas bubble evolution in a single crystal during post-irradiation thermal annealing. In this work, we enhanced the model by incorporating thermodynamic and kinetic properties at grain boundaries, which can be obtained from atomistic simulations, to simulate fission gas bubble growth kinetics in polycrystalline UO2 fuels. The model takes into account of gas atom and vacancy diffusion, vacancy trapping and emission at defects, gas atom absorption and resolution at gas bubbles, internal pressure in gas bubbles, elastic interaction between defects and gas bubbles, and the difference of thermodynamic and kinetic properties in matrix and grain boundaries. We applied the model to simulate gas atom segregation at grain boundaries and the effect of interfacial energy and gas mobility on gas bubble morphology and growth kinetics in a bi-crystal UO2 during post-irradiation thermal annealing. The preliminary results demonstrate that the model can produce the equilibrium thermodynamic properties and the morphology of gas

Mechanical properties of steel for construction of gas transfer pipelines and their modification resulting from expanding of gas pipelines during hydraulic pressure testing; Wlasnosci mechaniczne stali do budowy rurociagow przesylowych gazu i ich modyfikacja w wyniku eksploatowania rurociagow gazu w trakcie hydraulicznej proby cisnieniowej

Energy Technology Data Exchange (ETDEWEB)

Kopczynski, A [Biuro Studiow i Projektow Gornictwa, Gazoprojekt S.A., Wroclaw (Poland)

1997-07-01

There are discussed the mechanical properties of the new generation of steel as per European Standard EN 10208.2: 1996. on the basis of the mechanical parameters of steel the normalized graphs of steel tensioning are presented. Analysis of influence of expanding gas pipelines on changes of steel tensioning graphs were performed. Advantages, resulting from expanding of gas pipelines, were shown. (author)

Direct Monte Carlo simulation of nanoscale mixed gas bearings

Directory of Open Access Journals (Sweden)

Kyaw Sett Myo

2015-06-01

Full Text Available The conception of sealed hard drives with helium gas mixture has been recently suggested over the current hard drives for achieving higher reliability and less position error. Therefore, it is important to understand the effects of different helium gas mixtures on the slider bearing characteristics in the head–disk interface. In this article, the helium/air and helium/argon gas mixtures are applied as the working fluids and their effects on the bearing characteristics are studied using the direct simulation Monte Carlo method. Based on direct simulation Monte Carlo simulations, the physical properties of these gas mixtures such as mean free path and dynamic viscosity are achieved and compared with those obtained from theoretical models. It is observed that both results are comparable. Using these gas mixture properties, the bearing pressure distributions are calculated under different fractions of helium with conventional molecular gas lubrication models. The outcomes reveal that the molecular gas lubrication results could have relatively good agreement with those of direct simulation Monte Carlo simulations, especially for pure air, helium, or argon gas cases. For gas mixtures, the bearing pressures predicted by molecular gas lubrication model are slightly larger than those from direct simulation Monte Carlo simulation.

理論生態学の環境毒性データ解析への応用

OpenAIRE

田中, 嘉成

1998-01-01

Ecological theories relevant to estimate hazard of chemical exposure to populational proliferation are reviewed. The Leslie matrix model describes dynamics of age or stage-structured populations under stochastic environments. If toxicants' effects are different between ages or stages of test organisms, and the chemical exposure to environments is time-dependent, the Leslie matrix model is the most straightforward method to simulate population dynamics and extinction. The life-cycle sensitivit...

It's All About Me: The Role of the Self in Predicting Leadership Perceptions

OpenAIRE

Robson, Victoria Elizabeth

2007-01-01

The present study examined the role of oneâ s own self-perceptions of leadership in predicting both leadership prototypes and leadership perceptions of others. Additionally, this study explored gender differences in leadership prototypes and perceptions of leadership. Participants completed a measure of their own self-perceptions of their leadership traits (i.e., sensitivity, intelligence, dedication, and dynamism) and an instrument that assessed their leadership prototypes (i.e., sensitivit...

An analysis of the falling film gas-liquid reactor

NARCIS (Netherlands)

Davis, E.J.; Ouwerkerk-Dijkers, van M.P.; Venkatesh, S.

1979-01-01

A mathematical model of the falling film reactor is developed to predict the conversion and temperature distribution in the reactor as a function of the gas and liquid flow rates, physical properties, the feed composition of the reactive gas and carrier gas and other parameters of the system.

Antioxidant and Antiangiogenic Properties, and Gas Chromatographic-Time of Flight Analysis of Sonchus arvensis Leaves Extracts

International Nuclear Information System (INIS)

Itam, A.; Shah, A. M.; Majid, A.; Ismail, Z.

2015-01-01

Sonchus arvensis L. (Asteraceae) is one of the medicinal herbs used in traditional medicines, in which the leaf extract was used as a diuretic, lithotriptic and antiurolithiasis agent. The leaves of S. arvensis reported contain several compounds, including a variety of flavonoids, terpenoids and sterol, even this plant also contain silica and potassium. Flavonoids are secondary metabolite compound which have ability as antioxidant. In this study, the aims are to determine of antioxidants and antiangiogenic properties, and phytoconstituents quantitative of aqueous and methanol extracts of S. arvensis leaves. The antioxidant properties were studied using 1,1-Diphenyl-2-picrylhydrazyl (DPPH) free radical, xanthine oxidase and beta-carotene-linoleate models system. Furthermore, the antiangiogenic property was evaluated using ex vivo rat aorta ring assay. Quantitative determination of extracts phytoconstituents were carried out by using Gas Chromatographic-Time of Flight (GC-TOF) mass spectrophotometric methods. The results showed that the aqueous and methanol extracts have ability as antioxidant which is antioxidant activities of aqueous extracts on DPPH radical and inhibition of xanthine oxidase activity are higher than that of methanol extracts. Meanwhile antioxidant activity using beta-carotene-linoleate model system of S. arvensis aqueous extract is lower than that of methanol extracts. Nevertheless, the differences of these antioxidant activities are not significant. Antiangiogenic property of aqueous extract is also higher than that of methanol extract which is measured at 100 meu g mL/sup -1/ of extracts. This indicates that there is correlation between antioxidant activity and antiangigenic property, exhibiting that this plant possesses the potential to prevent or cure the diseases that related to angiogenesis such as cancer. (author)

Mechanical Properties of Advanced Gas-Cooled Reactor Stainless Steel Cladding After Irradiation

Science.gov (United States)

Degueldre, Claude; Fahy, James; Kolosov, Oleg; Wilbraham, Richard J.; Döbeli, Max; Renevier, Nathalie; Ball, Jonathan; Ritter, Stefan

2018-05-01

The production of helium bubbles in advanced gas-cooled reactor (AGR) cladding could represent a significant hazard for both the mechanical stability and long-term storage of such materials. However, the high radioactivity of AGR cladding after operation presents a significant barrier to the scientific study of the mechanical properties of helium incorporation, said cladding typically being analyzed in industrial hot cells. An alternative non-active approach is to implant He2+ into unused AGR cladding material via an accelerator. Here, a feasibility study of such a process, using sequential implantations of helium in AGR cladding steel with decreasing energy is carried out to mimic the buildup of He (e.g., 50 appm) that would occur for in-reactor AGR clad in layers of the order of 10 µm in depth, is described. The implanted sample is subsequently analyzed by scanning electron microscopy, nanoindentation, atomic force and ultrasonic force microscopies. As expected, the irradiated zones were affected by implantation damage (steel cladding is retained despite He2+ implantation.

Well log characterization of natural gas-hydrates

Science.gov (United States)

Collett, Timothy S.; Lee, Myung W.

2012-01-01

In the last 25 years there have been significant advancements in the use of well-logging tools to acquire detailed information on the occurrence of gas hydrates in nature: whereas wireline electrical resistivity and acoustic logs were formerly used to identify gas-hydrate occurrences in wells drilled in Arctic permafrost environments, more advanced wireline and logging-while-drilling (LWD) tools are now routinely used to examine the petrophysical nature of gas-hydrate reservoirs and the distribution and concentration of gas hydrates within various complex reservoir systems. Resistivity- and acoustic-logging tools are the most widely used for estimating the gas-hydrate content (i.e., reservoir saturations) in various sediment types and geologic settings. Recent integrated sediment coring and well-log studies have confirmed that electrical-resistivity and acoustic-velocity data can yield accurate gas-hydrate saturations in sediment grain-supported (isotropic) systems such as sand reservoirs, but more advanced log-analysis models are required to characterize gas hydrate in fractured (anisotropic) reservoir systems. New well-logging tools designed to make directionally oriented acoustic and propagation-resistivity log measurements provide the data needed to analyze the acoustic and electrical anisotropic properties of both highly interbedded and fracture-dominated gas-hydrate reservoirs. Advancements in nuclear magnetic resonance (NMR) logging and wireline formation testing (WFT) also allow for the characterization of gas hydrate at the pore scale. Integrated NMR and formation testing studies from northern Canada and Alaska have yielded valuable insight into how gas hydrates are physically distributed in sediments and the occurrence and nature of pore fluids(i.e., free water along with clay- and capillary-bound water) in gas-hydrate-bearing reservoirs. Information on the distribution of gas hydrate at the pore scale has provided invaluable insight on the mechanisms

Ethylene Gas Sensing Properties of Tin Oxide Nanowires Synthesized via CVD Method

Science.gov (United States)

Akhir, Maisara A. M.; Mohamed, Khairudin; Rezan, Sheikh A.; Arafat, M. M.; Haseeb, A. S. M. A.; Uda, M. N. A.; Nuradibah, M. A.

2018-03-01

This paper studies ethylene gas sensing performance of tin oxide (SnO2) nanowires (NWs) as sensing material synthesized using chemical vapor deposition (CVD) technique. The effect of NWs diameter on ethylene gas sensing characteristics were investigated. SnO2 NWs with diameter of ∼40 and ∼240 nm were deposited onto the alumina substrate with printed gold electrodes and tested for sensing characteristic toward ethylene gas. From the finding, the smallest diameter of NWs (42 nm) exhibit fast response and recovery time and higher sensitivity compared to largest diameter of NWs (∼240 nm). Both sensor show good reversibility features for ethylene gas sensor.

Buying and selling oil and gas properties in Saskatchewan

International Nuclear Information System (INIS)

Lothian, E.C.

1997-01-01

During the last five years, Saskatchewan has experienced its highest level of activity in the oil and gas industry, in terms of drilling and land acquisition. This study reviewed the unique concerns and issues affecting the acquisition or disposition of oil and gas assets in Saskatchewan. The two separate and distinct land registry systems regarding mines and mineral interests in Saskatchewan, due diligence issues, title and leasehold opinions and their limitations and environmental liabilities issues management were described. Some basic principles of contract law such as registration issues with respect to GOR's, and builder's lien pitfalls, as well as legal issues created by horizontal drilling, and legal issues associated with a Right of First Refusal, were also explained

Direct and inverse neural networks modelling applied to study the influence of the gas diffusion layer properties on PBI-based PEM fuel cells

Energy Technology Data Exchange (ETDEWEB)

Lobato, Justo; Canizares, Pablo; Rodrigo, Manuel A.; Linares, Jose J. [Chemical Engineering Department, University of Castilla-La Mancha, Campus Universitario s/n, 13004 Ciudad Real (Spain); Piuleac, Ciprian-George; Curteanu, Silvia [Faculty of Chemical Engineering and Environmental Protection, Department of Chemical Engineering, ' ' Gh. Asachi' ' Technical University Iasi Bd. D. Mangeron, No. 71A, 700050 IASI (Romania)

2010-08-15

This article shows the application of a very useful mathematical tool, artificial neural networks, to predict the fuel cells results (the value of the tortuosity and the cell voltage, at a given current density, and therefore, the power) on the basis of several properties that define a Gas Diffusion Layer: Teflon content, air permeability, porosity, mean pore size, hydrophobia level. Four neural networks types (multilayer perceptron, generalized feedforward network, modular neural network, and Jordan-Elman neural network) have been applied, with a good fitting between the predicted and the experimental values in the polarization curves. A simple feedforward neural network with one hidden layer proved to be an accurate model with good generalization capability (error about 1% in the validation phase). A procedure based on inverse neural network modelling was able to determine, with small errors, the initial conditions leading to imposed values for characteristics of the fuel cell. In addition, the use of this tool has been proved to be very attractive in order to predict the cell performance, and more interestingly, the influence of the properties of the gas diffusion layer on the cell performance, allowing possible enhancements of this material by changing some of its properties. (author)

Gas-partitioning tracer test to qualify trapped gas during recharge

Science.gov (United States)

Heilweil, Victor M.; Kip, Solomon D.; Perkins, Kim S.; Ellett, Kevin M.

2004-01-01

Dissolved helium and bromide tracers were used to evaluate trapped gas during an infiltration pond experiment. Dissolved helium preferentially partitioned into trapped gas bubbles, or other pore air, because of its low solubility in water. This produced observed helium retardation factors of as much as 12 relative to bromide. Numerical simulations of helium breakthrough with both equilibrium and kinetically limited advection/dispersion/retardation did not match observed helium concentrations. However, better fits were obtained by including a decay term representing the diffusive loss of helium through interconnected, gas-filled pores. Calculations indicate that 7% to more than 26% of the porosity beneath the pond was filled with gas. Measurements of laboratory hydraulic properties indicate that a 10% decrease in saturation would reduce the hydraulic conductivity by at least one order of magnitude in the well-sorted sandstone, but less in the overlying soils. This is consistent with in situ measurements during the experiment, which show steeper hydraulic gradients in sandstone than in soil. Intrinsic permeability of the soil doubled during the first six months of the experiment, likely caused by a combination of dissolution and thermal contraction of trapped gas. Managers of artificial recharge basins may consider minimizing the amount of trapped gas by using wet, rather than dry, tilling to optimize infiltration rates, particularly in well-sorted porous media in which reintroduced trapped gas may cause substantial reductions in permeability. Trapped gas may also inhibit the amount of focused infiltration that occurs naturally during ephemeral flood events along washes and playas.

Gas-partitioning tracer test to quantify trapped gas during recharge

Science.gov (United States)

Heilweil, V.M.; Solomon, D.K.; Perkins, K.S.; Ellett, K.M.

2004-01-01

Dissolved helium and bromide tracers were used to evaluate trapped gas during an infiltration pond experiment. Dissolved helium preferentially partitioned into trapped gas bubbles, or other pore air, because of its low solubility in water. This produced observed helium retardation factors of as much as 12 relative to bromide. Numerical simulations of helium breakthrough with both equilibrium and kinetically limited advection/dispersion/retardation did not match observed helium concentrations. However, better fits were obtained by including a decay term representing the diffusive loss of helium through interconnected, gas-filled pores. Calculations indicate that 7% to more than 26% of the porosity beneath the pond was filled with gas. Measurements of laboratory hydraulic properties indicate that a 10% decrease in saturation would reduce the hydraulic conductivity by at least one order of magnitude in the well-sorted sandstone, but less in the overlying soils. This is consistent with in situ measurements during the experiment, which show steeper hydraulic gradients in sandstone than in soil. Intrinsic permeability of the soil doubled during the first six months of the experiment, likely caused by a combination of dissolution and thermal contraction of trapped gas. Managers of artificial recharge basins may consider minimizing the amount of trapped gas by using wet, rather than dry, tilling to optimize infiltration rates, particularly in well-sorted porous media in which reintroduced trapped gas may cause substantial reductions in permeability. Trapped gas may also inhibit the amount of focused infiltration that occurs naturally during ephemeral flood events along washes and playas.

Interaction of a H2O/Ar Plasma Jet with Nitrogen Atmosphere: Effect of the Method for Calculating Thermophysical Properties of the Gas Mixture on the flow field

Czech Academy of Sciences Publication Activity Database

Agon, N.; Vierendeels, J.; Hrabovský, Milan; Murphy, A.B.; Van Oost, G.

2015-01-01

Roč. 35, č. 2 (2015), s. 365-386 ISSN 0272-4324 R&D Projects: GA ČR(CZ) GA15-19444S Institutional support: RVO:61389021 Keywords : Thermal plasma * Computational fluid dynamics * Thermophysical properties * Mixing rules * Ionized gas mixtures Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.811, year: 2015 http://link.springer.com/article/10.1007%2Fs11090-014-9605-6

Studies of matrix diffusion in gas phase

International Nuclear Information System (INIS)

Hartikainen, K.; Timonen, J.; Vaeaetaeinen, K.; Pietarila, H.

1994-03-01

The diffusion of solutes from fractures into rock matrix is an important factor in the safety analysis of disposal of radioactive waste. Laboratory measurements are needed to complement field investigations for a reliable determination of the necessary transport parameters. Measurements of diffusion coefficients in tight rock samples are usually time consuming because the diffusion processes are slow. On the other hand it is well known that diffusion coefficients in the gas phase are roughly four orders of magnitude larger than those in the liquid phase. Therefore, for samples whose structures do not change much upon drying, it is possible to estimate the diffusion properties of the liquid phase when the properties of the gas phase are known. Advantages of the gas method are quick and easy measurements. In the measurements nitrogen was used as the carrier gas and helium as the tracer gas, and standard techniques have been used for helium detection. Techniques have been developed for both channel flow and through-diffusion measurements. The breakthrough curves have been measured in every experiment and all measurements have been modelled by using appropriate analytical models. As a result matrix porosities and effective diffusion coefficients in the gas phase have been determined. (12 refs., 21 figs., 6 tabs.)

Effect of post-weld aging treatment on mechanical properties of Tungsten Inert Gas welded low thickness 7075 aluminium alloy joints

International Nuclear Information System (INIS)

Temmar, M.; Hadji, M.; Sahraoui, T.

2011-01-01

Highlights: → The effects of post-weld aging treatment on the properties of joints is studied. → The post-weld aging treatment increases the tensile strength of TIG welded joints. → The strengthening is due to a balance of dissolution, reversion and precipitation. → Simple post-weld aging at 140 o C enhances the properties of the welded joints. -- Abstract: This paper reports the influence of post-weld aging treatment on the microstructure, tensile strength, hardness and Charpy impact energy of weld joints low thickness 7075 T6 aluminium alloy welded by Tungsten Inert Gas (TIG). Hot cracking occurs in aluminium welds when high levels of thermal stress and solidification shrinkage are present while the weld is undergoing various degrees of solidification. Weld fusion zones typically exhibit microstructure modifications because of the thermal conditions during weld metal solidification. This often results in low weld mechanical properties and low resistance to hot cracking. It has been observed that the mechanical properties are very sensitive to microstructure of weld metal. Simple post-weld aging treatment at 140 o C applied to the joints is found to be beneficial to enhance the mechanical properties of the welded joints. Correlations between microstructures and mechanical properties were discussed.

An electron conductive polymer, poly-aniline, in gas separation: optimisation of transport properties by alternated acid-base treatment

International Nuclear Information System (INIS)

Rebattet, Laurence

1994-01-01

The objective of this research thesis is to study the variation of gas permeation properties of poly-aniline during a doping/de-doping/re-doping cycle, and to study the evolution of the separation power of this polymer. Scanning electronic microscopy is used to study the microstructure and more particularly how the doping agent is distributed within the polymer. Permeabilities, diffusion coefficients, sorption solubilities and interaction energies are measured by using coupled permeation and micro-gravimetry-calorimetry methods. A range of gases (H 2 , O 2 , CO 2 , N 2 , CH 4 ) is analysed [fr

The results of investigation and the analysis of the mechanical properties of L485MB steel used for gas-pipelines construction

International Nuclear Information System (INIS)

Wasiak, J.; Szteke, W.; Bilous, W.; Hajewska, E.; Wagner, T.; Przyborska, M.

2001-01-01

In the paper results of mechanical properties investigation carried out on two sectors of the tube made of L485MB steel cutting out from the gas pipeline after stress test are described. The calculation of the critical dimensions of cracks in examined material is given. The diagnostic programme SACC serving to the evaluation of the exploitation safety of elements with cracks was applied. (author)

Short-term natural gas consumption forecasting

International Nuclear Information System (INIS)

Potocnik, P.; Govekar, E.; Grabec, I.

2007-01-01

Energy forecasting requirements for Slovenia's natural gas market were investigated along with the cycles of natural gas consumption. This paper presented a short-term natural gas forecasting approach where the daily, weekly and yearly gas consumption were analyzed and the information obtained was incorporated into the forecasting model for hourly forecasting for the next day. The natural gas market depends on forecasting in order to optimize the leasing of storage capacities. As such, natural gas distribution companies have an economic incentive to accurately forecast their future gas consumption. The authors proposed a forecasting model with the following properties: two submodels for the winter and summer seasons; input variables including past consumption data, weather data, weather forecasts and basic cycle indexes; and, a hierarchical forecasting structure in which a daily model was used as the basis, with the hourly forecast obtained by modeling the relative daily profile. This proposed method was illustrated by a forecasting example for Slovenia's natural gas market. 11 refs., 11 figs

Recent progress on gas tungsten arc welding of vanadium alloys

Energy Technology Data Exchange (ETDEWEB)

Grossbeck, M.L.; King, J.F.; Alexander, D.J. [Oak Ridge National Lab., TN (United States)] [and others

1997-08-01

Emphasis has been placed on welding 6.4 mm plate, primarily by gas tungsten arc (GTA) welding. The weld properties were tested using blunt notch Charpy testing to determine the ductile to brittle transition temperature (DBTT). Erratic results were attributed to hydrogen and oxygen contamination of the welds. An improved gas clean-up system was installed on the welding glove box and the resulting high purity welds had Charpy impact properties similar to those of electron beam welds with similar grain size. A post-weld heat treatment (PWHT) of 950{degrees}C for two hours did not improve the properties of the weld in cases where low concentrations of impurities were attained. Further improvements in the gas clean-up system are needed to control hydrogen contamination.

Numerical Method based on SIMPLE Algorithm for a Two-Phase Flow with Non-condensable Gas

International Nuclear Information System (INIS)

Kim, Jong Tae

2009-08-01

In this study, a numerical method based on SIMPLE algorithm for a two-phase flow with non-condensable gas has been developed in order to simulate thermal hydraulics in a containment of a nuclear power plant. As governing equations, it adopts a two-fluid three-field model for the two-phase flows. The three fields include gas, drops, and continuous liquid. The gas field can contains vapor and non-condensable gases such as air and hydrogen. In order to resolve mixing phenomena of gas species, gas transport equations for each species base on the gas mass fractions are solved with gas phase governing equations such as mass, momentum and energy equations. Methods to evaluate the properties of the gas species were implemented in the code. They are constant or polynomial function based a user input and a property library from Chemkin and JANAF table for gas specific heat. Properties for the gas mixture which are dependent on mole fractions of the gas species were evaluated by a mix rule

Quantitative estimation of massive gas hydrate in gas chimney structures, the eastern margin of Japan Sea, from the physical property anomalies obtained by LWD.

Science.gov (United States)

Tanahashi, M.; Morita, S.; Matsumoto, R.

2017-12-01

Two dedicated LWD (Logging While Drilling) cruises, GR14 and HR15, were conducted in summers of 2014 and 2015, respectively, by Meiji University and Geological Survey of Japan, AIST to explore the gas chimney structures, which are characterized by the columnar acoustic blanking below the topographic mound and/or pockmarks in eastern margin of Japan Sea. Shallow (33 to 172m-bsf, average 136m-bsf) 33 LWD drillings were carried out generally in and around gas chimney structures which are in Oki Trough, Off-Joetsu, and Mogami Trough areas, eastern margin of Japan Sea, during two cruises. Schlumberger LWD tools, GeoVISION (resistivity), TeleScope, ProVISION (NMR) and SonicVISION (sonic) were applied during GR14. NeoScope (neutron) was added and SonicScope was replaced for SonicVISION during HR15. The presence of thick highly-anomalous intervals within the LWD data at site J24L suggests the development of massive gas hydrate within Off-Joetsu, by very high resistivity ( 10,000 Ωm), high Vp ( 3,700 m/s) and Vs (370-1,839 m/s), high neutron porosity ( 1.2), low natural gamma ray intensity ( 0 API), low neutron gamma density ( 0.8 g/cm3), low NMR porosity ( 0.0), low permeability (10-2-10-4 mD), low formation neutron sigma (26-28). The extreme physical properties intervals suggest the development of the almost pure hydrate. Because of the clear contrast between pure hydrate and seawater saturated fine sediments, the hydrate amount can be estimated quantitatively based on the assumptions as the two component system of pure hydrate and the monotonous seawater saturated fine sediments. This study was conducted as a part of the methane hydrate research project funded by METI (the Ministry of Economy, Trade and Industry, Japan).

United Rayore Gas Ltd. annual report, 1993

International Nuclear Information System (INIS)

1993-01-01

United Rayore Gas, a Calgary-based oil and gas company, had land holdings of 31,500 net production held acres and 20,000 net undeveloped acres as of March 31, 1993. The company's gross land holdings are concentrated in southeast Saskatchewan and cover over 80,000 acres. Production in 1993 averaged 1,941 barrels of oil equivalent (BOE) per day, of which 96% was oil and 4% was gas. About 35% of the company's production in 1993 was from horizontal wells. Total proven reserves in which the company has a working interest are 15.5 million bbl oil and 10.5 billion ft 3 of natural gas. Principal producing properties are located at Parkman, Glen Ewen, and Workman in southeast Saskatchewan. Oil and gas sales for the fiscal year were $14.4 million, compared to $5.7 million a year earlier. The increased revenue is due to increased production and acquisition of producing properties. Net 1993 earnings amounted to $1.3 million. A review of the company's operations for the year, management discussion and analysis of results, and financial statements are presented. 25 figs., 13 tabs

Synthesis and characterization of porous silicon gas sensors

Science.gov (United States)

abbas, Roaa A.; Alwan, Alwan M.; Abdulhamied, Zainab T.

2018-05-01

In this work, photo-electrochemical etching process of n-type Silicon of resistivity(10 Ω.cm) and (100) orientation, using two illumination sources IR and violet wavelength in HF acid have been used to produce PSi gas detection device. The fabrication process was carried out at a fixed etching current density of 25mA/cm2 and at different etching time (5, 10, 15 and 20) min and (8, 16, 24, and 30) min. Two configurations of gas sensor configuration planer and sandwich have been made and investigated. The morphological properties have been studied using SEM,the FTIR measurement show that the (Si-Hx) and (Si-O-Si) absorption peak were increases with increasing etching time,and Photoluminescence properties of PSi layer show decrease in the peak of PL peak toward the violet shift. The gas detection process is made on the CO2 gas at different operating temperature and fixed gas concentration. In the planner structure, the gas sensing was measured through, the change in the resistance readout as a function to the exposure time, while for sandwich structure J-V characteristic have been made to determine the sensitivity.

State and trends of ionization gas analysis. 3

International Nuclear Information System (INIS)

Leonhardt, J.W.; Grosse, H.J.; Popp, P.

1980-01-01

Theory, properties, and main fields of application of noble gas detectors are discussed. The theory and design of the indirect electron mobility detector is presented. Conclusions are drawn with regard to possibilities of further development of detectors for the ionization gas analysis

Characterization of Gas Transport Properties of Fractured Rocks By Borehole and Chamber Tests.

Science.gov (United States)

Shimo, M.; Shimaya, S.; Maejima, T.

2014-12-01

Gas transport characteristics of fractured rocks is a great concern to variety of engineering applications such as underground storage of LPG, nuclear waste disposal, CCS and gas flooding in the oil field. Besides absolute permeability, relative permeability and capillary pressure as a function of water saturation have direct influences to the results of two phase flow simulation. However, number of the reported gas flow tests for fractured rocks are limited, therefore, the applicability of the conventional two-phase flow functions used for porous media, such as Mualem-van Genuchten model, to prediction of the gas transport in the fractured rock mass are not well understood. The authors conducted the two types of in-situ tests, with different scales, a borehole gas-injection test and a chamber gas-injection test in fractured granitic rock. These tests were conducted in the Cretaceous granitic rocks at the Namikata underground LPG storage cavern construction site in Ehime Prefecture in Japan, preceding to the cavern scale gas-tightness test. A borehole injection test was conducted using vertical and sub-vertical boreholes drilled from the water injection tunnel nearly at the depth of the top of the cavern, EL-150m. A new type downhole gas injection equipment that is capable to create a small 'cavern' within a borehole was developed. After performing a series of preliminary tests to investigate the hydraulic conductivity and gas-tightness, i.e. threshold pressure, gas injection tests were conducted under different gas pressure. Fig.1 shows an example of the test results From a chamber test using a air pressurizing chamber with volume of approximately166m3, the gas-tightness was confirmed within the uncertainty of 22Pa under the storage pressure of 0.7MPa, however, significant air leakage occurred possibly through an open fracture intersecting the chamber just after cavern pressure exceeds the initial hydrostatic pressure at the ceiling level of the chamber. Anomalies

FORTRAN program for calculating liquid-phase and gas-phase thermal diffusion column coefficients

International Nuclear Information System (INIS)

Rutherford, W.M.

1980-01-01

A computer program (COLCO) was developed for calculating thermal diffusion column coefficients from theory. The program, which is written in FORTRAN IV, can be used for both liquid-phase and gas-phase thermal diffusion columns. Column coefficients for the gas phase can be based on gas properties calculated from kinetic theory using tables of omega integrals or on tables of compiled physical properties as functions of temperature. Column coefficients for the liquid phase can be based on compiled physical property tables. Program listings, test data, sample output, and users manual are supplied for appendices

TIG AISI-316 welds using an inert gas welding chamber and different filler metals: Changes in mechanical properties and microstructure

Directory of Open Access Journals (Sweden)

Sánchez, A.

2010-12-01

Full Text Available This report analyses the influence of the use of an inert gas welding chamber with a totally inert atmosphere on the microstructure and mechanical properties of austenitic AISI 316L stainless steel TIG welds, using AISI ER316L, AISI 308L and Inconel 625 as filler metals. When compared with the typical TIG process, the use of the inert gas chamber induced changes in the microstructure, mainly an increase in the presence of vermicular ferrite and ferrite stringers, what resulted in higher yield strengths and lower values of hardness. Its effect on other characteristics of the joins, such as tensile strength, depended on the filler metal. The best combination of mechanical characteristics was obtained when welding in the inert gas chamber using Inconel 625 as filler metal.

En este estudio se analiza la influencia que el uso de una cámara de soldadura de gas inerte tiene sobre la microestructura y las propiedades mecánicas de las soldaduras TIG en el acero inoxidable austenítico AISI-316L cuando se emplean AISI ER316L, AISI 308L e Inconel 625 como materiales de aporte. Cuando se compara con el típico proceso de TIG, el uso de una cámara de gas inerte induce cambios en la microestructura, incrementando la presencia de ferrita vermicular y de laminillas de ferrita, resultando en un aumento del límite elástico y una pérdida de dureza. Su influencia sobre otras características de las soldaduras como la carga de rotura depende de la composición del material de aporte. La mejor combinación de propiedades mecánicas se obtuvo usando el Inconel 625 como material de aporte y soldando en la cámara de gas inerte.

Thermodynamic and transport properties of air and its products of combustion with ASTMA-A-1 fuel and natural gas at 20, 30, and 40 atmospheres

Science.gov (United States)

Poferl, D. J.; Svehla, R. A.

1973-01-01

The isentropic exponent, molecular weight, viscosity, specific heat at constant pressure, thermal conductivity, Prandtl number, and enthalpy were calculated for air, the combustion products of ASTM-A-1 jet fuel and air, and the combustion products of natural gas and air. The properties were calculated over a temperature range from 300 to 2800 K in 100 K increments and for pressures of 20, 30 and 40 atmospheres. The data for natural gas and ASTM-A-1 were calculated for fuel-air ratios from zero to stoichiometric in 0.01 increments.

Polyaniline/polybenzimidazole blends: characterisation of its physico-chemical properties and gas separation behaviour

Czech Academy of Sciences Publication Activity Database

Giel, Verena; Kredatusová, Jana; Trchová, Miroslava; Brus, Jiří; Žitka, Jan; Peter, Jakub

2016-01-01

Roč. 77, April (2016), s. 98-113 ISSN 0014-3057 R&D Projects: GA ČR(CZ) GPP106/12/P643 Institutional support: RVO:61389013 Keywords : gas separation * gas sorption * gas permeation Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.531, year: 2016

Thermodynamic properties of indan: Experimental and computational results

International Nuclear Information System (INIS)

Chirico, Robert D.; Steele, William V.; Kazakov, Andrei F.

2016-01-01

Highlights: • Heat capacities were measured for the temperature range (5 to 445) K. • Vapor pressures were measured for the temperature range (338 to 495) K. • Densities at saturation pressure were measured from T = (323 to 523) K. • Computed and experimentally derived properties for ideal gas entropies are in excellent accord. • Thermodynamic consistency analysis revealed anomalous literature data. - Abstract: Measurements leading to the calculation of thermodynamic properties in the ideal-gas state for indan (Chemical Abstracts registry number [496-11-7], 2,3-dihydro-1H-indene) are reported. Experimental methods were adiabatic heat-capacity calorimetry, differential scanning calorimetry, comparative ebulliometry, and vibrating-tube densitometry. Molar thermodynamic functions (enthalpies, entropies, and Gibbs energies) for the condensed and ideal-gas states were derived from the experimental studies at selected temperatures. Statistical calculations were performed based on molecular geometry optimization and vibrational frequencies calculated at the B3LYP/6-31+G(d, p) level of theory. Computed ideal-gas properties derived with the rigid-rotor harmonic-oscillator approximation are shown to be in excellent accord with ideal-gas entropies derived from thermophysical property measurements of this research, as well as with experimental heat capacities for the ideal-gas state reported in the literature. Literature spectroscopic studies and ab initio calculations report a range of values for the barrier to ring puckering. Results of the present work are consistent with a large barrier that allows use of the rigid-rotor harmonic-oscillator approximation for ideal-gas entropy and heat-capacity calculations, even with the stringent uncertainty requirements imposed by the calorimetric and physical property measurements reported here. All experimental results are compared with property values reported in the literature.

CONSTRAINING DUST AND MOLECULAR GAS PROPERTIES IN Ly{alpha} BLOBS AT z {approx} 3

Energy Technology Data Exchange (ETDEWEB)

Yang Yujin; Decarli, Roberto; Walter, Fabian; Leipski, Christian [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, Heidelberg (Germany); Dannerbauer, Helmut; Le Floc' h, Emeric [Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, Irfu/Service d' Astrophysique, CEA-Saclay, Orme des Merisiers, 91191 Gif-sur-Yvette Cedex (France); Weiss, Axel; Menten, Karl M. [Max-Planck-Insitut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany); Dey, Arjun [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Chapman, Scott C. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Prescott, Moire K. M. [Department of Physics, Broida Hall, Mail Code 9530, University of California, Santa Barbara, CA 93106 (United States); Neri, Roberto [IRAM-Institut de Radio Astronomie Millimetrique, 300 rue de la Piscine, 38406 Saint-Martin d' Heres (France); Borys, Colin [IPAC, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Matsuda, Yuichi [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Yamada, Toru [Astronomical Institute, Tohoku University, Aramaki, Aoba-ku, Sendai, Miyagi 980-8578 (Japan); Hayashino, Tomoki [Research Center for Neutrino Science, Graduate School of Science, Tohoku University, Sendai 980-8578 (Japan); Tapken, Christian [Leibnitz-Institut fuer Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam (Germany)

2012-01-10

In order to constrain the bolometric luminosities, dust properties, and molecular gas content of giant Ly{alpha} nebulae, the so-called Ly{alpha} blobs, we have carried out a study of dust continuum and CO line emission in two well-studied representatives of this population at z {approx} 3: an Ly{alpha} blob discovered by its strong Spitzer Multiband Infrared Photometer 24 {mu}m detection (LABd05) and the Steidel blob 1 (SSA22-LAB01). We find that the spectral energy distribution of LABd05 is well described by an active-galactic-nucleus-starburst composite template with L{sub FIR} = (4.0 {+-} 0.5) Multiplication-Sign 10{sup 12} L{sub Sun }, comparable to high-z submillimeter galaxies and ultraluminous infrared galaxies. New Large APEX Bolometer Camera 870 {mu}m measurements rule out the reported Submillimeter Common-User Bolometer Array detection of the SSA22-LAB01 (S{sub 850{mu}m} = 16.8 mJy) at the >4{sigma} level. Consistent with this, ultradeep Plateau de Bure Interferometer observations with {approx}2'' spatial resolution also fail to detect any 1.2 mm continuum source down to Almost-Equal-To 0.45 mJy beam{sup -1} (3{sigma}). Combined with the existing (sub)millimeter observations in the literature, we conclude that the FIR luminosity of SSA22-LAB01 remains uncertain. No CO line is detected in either case down to integrated flux limits of S{sub {nu}}{Delta}V {approx}< 0.25-1.0 Jy km s{sup -1}, indicating a modest molecular gas reservoir, M(H{sub 2}) < (1-3) Multiplication-Sign 10{sup 10} M{sub Sun }. The non-detections exclude, with high significance (12{sigma}), the previous tentative detection of a CO J = 4-3 line in the SSA22-LAB01. The increased sensitivity afforded by the Atacama Large Millimeter/submillimeter Array will be critical in studying molecular gas and dust in these interesting systems.

Dissociation heat of mixed-gas hydrate composed of methane and ethane

Energy Technology Data Exchange (ETDEWEB)

Hachikubo, A.; Nakagawa, R.; Kubota, D.; Sakagami, H.; Takahashi, N.; Shoji, H. [Kitami Inst. of Technology, Kitami (Japan)

2008-07-01

Formation and dissociation processes of natural gas hydrates in permafrost, marine and lake sediments are highly controlled by their thermal properties. Dissociation heat of gas hydrates can be estimated from phase equilibrium data using the Clausius-Clapeyron equation. However, this method is applicable for pure gas hydrate and at a temperature of 0 degrees Celsius. Direct calorimetric measurements on gas hydrates using a calorimeter have been developed to obtain thermal properties of gas hydrates, including dissociation heat and heat capacity. Studies have shown that a structure 2 gas hydrate appears in appropriate gas composition of methane and ethane. This paper investigated the effect of ethane concentration on dissociation heat of mixed-gas (methane and ethane) hydrate. Raman spectroscopy was used to confirm the appearance of a structure 2 gas hydrate. The paper identified the experimental procedure and discussed sample preparation, Raman spectroscopy, and calorimetric measurements. A schematic diagram of the calorimeter was also presented. It was concluded that in most cases, two stages of dissociation were found at the dissociation process. 15 refs., 6 figs.

Computer simulations of a single-laser double-gas-jet wakefield accelerator concept

Directory of Open Access Journals (Sweden)

R. G. Hemker

2002-04-01

Full Text Available We report in this paper on full scale 2D particle-in-cell simulations investigating laser wakefield acceleration. First we describe our findings of electron beam generation by a laser propagating through a single gas jet. Using realistic parameters which are relevant for the experimental setup in our laboratory we find that the electron beam resulting after the propagation of a 0.8 μm, 50 fs laser through a 1.5 mm gas jet has properties that would make it useful for further acceleration. Our simulations show that the electron beam is generated when the laser exits the gas jet, and the properties of the generated beam, especially its energy, depend only weakly on most properties of the gas jet. We therefore propose to use the first gas jet as a plasma cathode and then use a second gas jet placed immediately behind the first to provide additional acceleration. Our simulations of this proposed setup indicate the feasibility of this idea and also suggest ways to optimize the quality of the resulting beam.

Properties of self-quenching streamer (SQS) tubes

International Nuclear Information System (INIS)

Koori, N.; Nohtomi, A.; Hashimoto, M.; Yoshioka, K.; Kumabe, I.

1989-01-01

The self-quenching streamer (SQS) mode of gas counters have been widely used for measuring high energy particles. The authors have very recently found that all the rare gas (He, Ne, Ar and Xe) mixtures with quenching gas of CH 4 , C 2 H 6 , C 3 H 8 , iso-C 4 H 10 or CO 2 can be used as gas mixtures for the SQS mode except Ne- and He-mixtures with CH 4 or CO 2 . Further studies on the properties of this mode are needed for its application to monitoring devices. Properties of a self-quenching tube are discussed here from this point of view. Gas multiplication properties, pulse shape of current signals, and dead zone are measured under several gas pressures equal to or less than one atomospheric pressure. Either the SQS or GM mode can be obtained by changing the gas pressure with a cylindrical gas counter. The operation mode of the counter may be correctly determined from the dead zone measurement. The measurements show that the SQS and GM modes are exclusive, even though SQS's can be simultaneously formed with a GM discharge. The counting rate capability of the SQS mode is higher than that of the GM mode by about one order of magnitude. Thus, SQS tubes are suitable for use in high flux radiation fields. (N.K.)

Prediction of air-fuel and oxy-fuel combustion through a generic gas radiation property model

International Nuclear Information System (INIS)

Yin, Chungen

2017-01-01

Highlights: • A gas radiation model for general combustion CFD presented, programmed & verified. • Its general applicability/practical accuracy demonstrated in air-fuel and oxy-fuel. • Useful guidelines for air-fuel and oxy-fuel combustion CFD suggested. • Important to include the impact of CO in gas radiation for oxy-fuel combustion CFD. - Abstract: Thermal radiation plays an important role in heat transfer in combustion furnaces. The weighted-sum-of-gray-gases model (WSGGM), representing a good compromise between computational efficiency and accuracy, is commonly used in computational fluid dynamics (CFD) modeling of combustion processes for evaluating gaseous radiative properties. However, the WSGGMs still have some limitations in practical use, e.g., unable to naturally accommodate different combustion environments, difficult to accurately address the variations in species concentrations in a flame, and inconvenient to account for the impacts of participating species other than H_2O and CO_2. As a result, WSGGMs with different coefficients have been published for specific applications. In this paper, a reliable generic model for gaseous radiation property calculation, which is a computationally efficient exponential wide band model (E-EWBM) applicable to combustion CFD and able to naturally solve all the practical limitations of the WSGGMs, is presented, programmed and verified. The model is then implemented to CFD simulation of a 300 kW air-fuel and a 0.8 MW oxy-fuel combustion furnace, respectively, to demonstrate its computational applicability to general combustion CFD and its capability in producing reliable CFD results for different combustion environments. It is found that the usefulness of the WSGGMs in oxy-fuel combustion CFD is compromised if the important impacts of high levels of CO under oxy-fuel combustion cannot be accounted for. The E-EWBM that appropriately takes the impacts of H_2O, CO_2, CO and CH_4 into account is a good replacement

The interaction between the gas sensing and surface morphology properties of LB thin films of porphyrins in terms of the adsorption kinetics

International Nuclear Information System (INIS)

Capan, İ.; Erdoğan, M.; Stanciu, G.A.; Stanciu, S.G.; Hristu, R.; Göktepe, M.

2012-01-01

In this work we investigate the adsorption characteristics due to exposure to benzene, toluene and chloroform vapor of 2,3,7,8,12,13,17,18-Octaethyl-21H,23H-porphine metal free thin films fabricated by using the Langmuir–Blodgett (LB) thin film technique and its derivatives containing iron chloride, cobalt and magnesium. By using the surface pressure–surface area (Π–A) isotherm graphs the optimum conditions for the thin film deposition and mean molecular area values of each porphyrin have been determined. Quartz Crystal Microbalance (QCM) system was employed to investigate the gas sensing performances of thin films during the exposure to Volatile Organic Compounds (VOCs). The surface properties have been investigated by using Atomic Force Microscopy (AFM) and analyzed together with the QCM results to understand the adsorption kinetics of the gas sensing mechanism. The rate constants, k a for each thin film interacting with the saturated concentration of vapors have been calculated. The gas sensing interaction has been considered in terms of rate constants in each case. The highest value for k a has been observed for benzene exposure. -- Highlights: ► We model an adsorption behavior for gas sensing porphyrin LB thin films. ► Adsorption coefficients are consistent with the gas experiments. ► The higher rate constant values point out the faster response.

[Prospects for Application of Gases and Gas Hydrates to Cryopreservation].

Science.gov (United States)

Shishova, N V; Fesenko, E E

2015-01-01

In the present review, we tried to evaluate the known properties of gas hydrates and gases participating in the formation of gas hydrates from the point of view of the mechanisms of cryoinjury and cryoprotection, to consider the papers on freezing biological materials in the presence of inert gases, and to analyze the perspectives for the development of this direction. For the purpose, we searched for the information on the physical properties of gases and gas hydrates, compared processes occured during the formation of gas hydrates and water ice, analyzed the influence of the formation and growth of gas hydrates on the structure of biological objects. We prepared a short review on the biological effects of xenon, krypton, argon, carbon dioxide, hydrogen sulfide, and carbon monoxide especially on hypothermal conditions and probable application of these properties in cryopreservation technologies. The description of the existing experiments on cryopreservation of biological objects with the use of gases was analyzed. On the basis of the information we found, the most perspective directions of work in the field of cryopreservation of biological objects with the use of gases were outlined. An attempt was made to forecast the potential problems in this field.

Gas separation techniques in nuclear facilities

International Nuclear Information System (INIS)

Hioki, Hideaki; Morisue, Tetsuo; Ohno, Masayoshi

1983-01-01

The literatures concerning the gas separation techniques which are applied to the waste gases generated from nuclear power plants and nuclear fuel reprocessing plants, uranium enrichment and the instrumentation of nuclear facilities are reviewed. The gas permeability and gas separation performance of membranes are discussed in terms of rare gas separation. The investigation into the change of the gas permeability and mechanical properties of membranes with exposure to radiation is reported. The theoretical investigation of the separating cells used for the separation of rare gas and the development of various separating cells are described, and the theoretical and experimental investigations concerning rare gas separation using cascades are described. The application of membrane method to nuclear facilities is explained showing the examples of uranium enrichment, the treatment of waste gases from nuclear reactor buildings and nuclear fuel reprocessing plants, the monitoring of low level β-emitters in stacks, the detection of failed fuels and the detection of water leak in fast breeder reactors. (Yoshitake, I.)

Influence of spray parameters on the microstructure and mechanical properties of gas-tunnel plasma sprayed hydroxyapatite coatings

International Nuclear Information System (INIS)

Morks, M.F.; Kobayashi, Akira

2007-01-01

For biomedical applications, hydroxyapatite (HA) coatings were deposited on 304 stainless steel substrate by using a gas tunnel type plasma spraying process. The influences of spraying distances and plasma arc currents on the microstructure, hardness and adhesion properties of HA coatings were investigated. Microstructure observation by SEM showed that HA coatings sprayed at low plasma power have a porous structure and poor hardness. HA coatings sprayed at high plasma power and short spraying distance are characterized by good adhesion and low porosity with dense structure. Hardness increased for HA coatings sprayed at shorter spraying distance and higher plasma power, mainly due to the formation of dense coatings

The synthesis of porous Co3O4 micro cuboid structures by solvothermal approach and investigation of its gas sensing properties and catalytic activity

International Nuclear Information System (INIS)

Jamil, Saba; Jing, Xiaoyan; Wang, Jun; Li, Songnan; Liu, Jingyuan; Zhang, Milin

2013-01-01

Graphical abstract: - Highlights: • Micro cuboid Co 3 O 4 particle prepared by solvothermal method. • Study of morphology of synthesized cuboids before and after calcinations. • Investigation of formation mechanism of porous Co 3 O 4 from cuboid CoCO 3 . • Investigation of gas sensing properties of porous Co 3 O 4 . • Study of catalytic activity of product. - Abstract: The cobalt carbonate cuboids are prepared by adopting a simple solvothermal approach by using diethylene glycol and water in specific ratio as solvent. The prepared cobalt carbonate is subjected to different instrumentation to investigate its morphology and other properties. It is clear from the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) that the product is distinct cuboid in shape with a size of approximately 3 μm from each face of the cube. Each particle of cuboid cobalt carbonate seems to comprise of layer by layer assembly of unit cells that consequently leads to a cuboid geometry. The cuboid cobalt carbonate was calcined at 700 °C in a furnace under argon atmosphere that decompose cobalt carbonate into porous Co 3 O 4 with the loosely packed arrangement of nano architectures. The gas sensing properties and catalytic activity of porous cuboids Co 3 O 4 are also investigated

Tungsten sulfide nanoflakes. Synthesis by electrospinning and their gas sensing properties

Energy Technology Data Exchange (ETDEWEB)

Wang, Ke; Qin, Xiang; Deng, Da-Shen; Feng, Xu; Zhang, Chao [Chongqing Univ. of Technology, Chongqing (China). Dept. of Physics and Energy; Feng, Wen-Lin [Chongqing Univ. of Technology, Chongqing (China). Dept. of Physics and Energy; Chongqing Key Laboratory of Modern Photoelectric Detection Technology and Instrument, Chongqing (China).

2017-07-01

Tungsten sulfide (WS{sub 2}) nanoflakes were successfully prepared via electrospinning with polyvinylpyrrolidone (PVP) as organic solvent. In addition, Ag-deposited WS{sub 2} (Ag-WS{sub 2}) was obtained by chemical blending/calcination method. The structure and morphology of as-prepared materials were characterised by powder X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. The XRD result shows that the prepared WS{sub 2} has a graphene-like structure with P{sub 63/mmc} space group symmetry. The SEM illuminates that the sensing samples have nanoflake appearance. Furthermore, heater-type gas sensors were fabricated based on WS{sub 2} and Ag-WS{sub 2} nanomaterials. The sensing responses of WS{sub 2} and Ag-WS{sub 2} on the ammonia (NH{sub 3}), ethanol (C{sub 2}H{sub 5}OH), and acetone (C{sub 3}H{sub 6}O) were investigated at about 220 C. The results indicate that gas sensor based on WS{sub 2} and Ag-WS{sub 2} nanoflakes has 60 ppm sensing threshold value for ammonia. One possible gas sensing mechanism of WS{sub 2} and Ag-WS{sub 2} gas sensors is surface control via charge transfer.

Influences of oxygen gas flow rate on electrical properties of Ga-doped ZnO thin films deposited on glass and sapphire substrates

International Nuclear Information System (INIS)

Makino, Hisao; Song, Huaping; Yamamoto, Tetsuya

2014-01-01

The Ga-doped ZnO (GZO) films deposited on glass and c-plane sapphire substrates have been comparatively studied in order to explore the role of grain boundaries in electrical properties. The influences of oxygen gas flow rates (OFRs) during the deposition by ion-plating were examined. The dependences of carrier concentration, lattice parameters, and characteristic of thermal desorption of Zn on the OFR showed common features between glass and sapphire substrates, however, the Hall mobility showed different behavior. The Hall mobility of GZO films on glass increased with increasing OFR of up to 15 sccm, and decreased with further increasing OFR. On the other hand, the Hall mobility of GZO films on c-sapphire increased for up to 25 sccm. The role of grain boundary in polycrystalline GZO films has been discussed. - Highlights: • Ga-doped ZnO films were deposited on glass and c-sapphire by ion-plating. • The epitaxial growth on c-sapphire was confirmed by X-ray diffraction. • Dependence of Hall mobility showed different tendency between glass and sapphire. • Grain boundaries influence transport properties at high O 2 gas flow rate

Statistical estimation of loads from gas explosions

Energy Technology Data Exchange (ETDEWEB)

Hoeiset, Stian

1998-12-31

In the design of structures in the offshore and process industries, the possibility of a gas explosion must always be considered. The main uncertainties in computerized simulation of gas explosions are the assumptions of the gas cloud, the location of the ignition point and the properties of the simulator itself. This thesis quantifies the levels of these uncertainties by performing a large number of simulations on three offshore modules and one onshore plant. It is found that (1) there is an approximate linear relation between pressure and gas volume, (2) it may be possible to find a linear relation between pressure and impulse, (3) there is an inverse relation between pressure and duration, (4) the response of offshore structures exposed to gas explosions are rarely in the impulsive regime, (5) loading rates vary widely in magnitude, (6) an assumption of a triangular explosion pulse is often correct, (7) louvres increase pressure, impulse and duration of an explosion. The effect of ignition point location is studied in detail. It is possible to derive an ignition point uncertainty load factor that shows predictable behaviour by generalizing the non-parametric properties of the explosion pressure. A model for taking into account the uncertainties regarding gas volume, ignition point location and simulator imperfectness is proposed. The model is intended to produce a characteristic load for structural design. 68 refs., 51 figs., 36 tabs.

Optical Absorption Spectroscopy for Gas Analysis in Biomass Gasification

DEFF Research Database (Denmark)

Grosch, Helge

important gas species of the low-temperature circulating fluidized bed gasifier. At first, a special gas cell,the hot gas flow cell (HGC), was build up and veried. In this custom-made gas cell, the optical properties, the so-called absorption cross-sections, of the most important sulfur and aromatic...... compounds were determined in laboratory experiments. By means of the laboratory results and spectroscopic databases,the concentrations of the major gas species and the aromatic compounds phenol and naphthalene were determined in extraction and in-situ measurements....

The study of thermodynamic properties and transport properties of multicomponent systems with chemical reactions

Directory of Open Access Journals (Sweden)

Samujlov E.

2013-04-01

Full Text Available In case of system with chemical reaction the most important properties are heat conductivity and heat capacity. In this work we have considered the equation for estimate the component of these properties caused by chemical reaction and ionization processes. We have evaluated the contribution of this part in heat conductivity and heat capacity too. At the high temperatures contribution in heat conductivity from ionization begins to play an important role. We have created a model, which describe partial and full ionization of gases and gas mixtures. In addition, in this work we present the comparison of our result with experimental data and data from numerical simulation. We was used the data about transport properties of middle composition of Russian coals and the data of thermophysical properties of natural gas for comparison.

Gas Content and Kinematics in Clumpy, Turbulent Star-forming Disks

International Nuclear Information System (INIS)

White, Heidi A.; Abraham, Roberto G.; Fisher, David B.; Glazebrook, Karl; Murray, Norman; Bolatto, Alberto D.; Green, Andrew W.; Mentuch Cooper, Erin; Obreschkow, Danail

2017-01-01

We present molecular gas-mass estimates for a sample of 13 local galaxies whose kinematic and star-forming properties closely resemble those observed in z ≈ 1.5 main-sequence galaxies. Plateau de Bure observations of the CO[1-0] emission line and Herschel Space Observatory observations of the dust emission both suggest molecular gas-mass fractions of ∼20%. Moreover, dust emission modeling finds T dust < 30 K, suggesting a cold dust distribution compared to their high infrared luminosity. The gas-mass estimates argue that z ∼ 0.1 DYNAMO galaxies not only share similar kinematic properties with high- z disks, but they are also similarly rich in molecular material. Pairing the gas-mass fractions with existing kinematics reveals a linear relationship between f gas and σ / v c , consistent with predictions from stability theory of a self-gravitating disk. It thus follows that high gas-velocity dispersions are a natural consequence of large gas fractions. We also find that the systems with the lowest t dep (∼0.5 Gyr) have the highest ratios of σ / v c and more pronounced clumps, even at the same high molecular gas fraction.

Gas Content and Kinematics in Clumpy, Turbulent Star-forming Disks

Energy Technology Data Exchange (ETDEWEB)

White, Heidi A.; Abraham, Roberto G. [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON, M5S 3H8 (Canada); Fisher, David B.; Glazebrook, Karl [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, P.O. Box 218, Hawthorn, VIC 3122 (Australia); Murray, Norman [Canadian Institute for Theoretical Astrophysics, 60 St. George Street, University of Toronto, Toronto ON M5S 3H8 (Canada); Bolatto, Alberto D. [Department of Astronomy and Joint Space Institute, University of Maryland, College Park, MD 20642 (United States); Green, Andrew W. [Australian Astronomical Observatory, P.O. Box 970, North Ryde, NSW 1670 (Australia); Mentuch Cooper, Erin [Astronomy Department, University of Texas at Austin, Austin, TX 78712 (United States); Obreschkow, Danail [International Centre for Radio Astronomy Research (ICRAR), University of Western Australia, M468, Crawley, WA 6009 (Australia)

2017-09-01

We present molecular gas-mass estimates for a sample of 13 local galaxies whose kinematic and star-forming properties closely resemble those observed in z ≈ 1.5 main-sequence galaxies. Plateau de Bure observations of the CO[1-0] emission line and Herschel Space Observatory observations of the dust emission both suggest molecular gas-mass fractions of ∼20%. Moreover, dust emission modeling finds T {sub dust} < 30 K, suggesting a cold dust distribution compared to their high infrared luminosity. The gas-mass estimates argue that z ∼ 0.1 DYNAMO galaxies not only share similar kinematic properties with high- z disks, but they are also similarly rich in molecular material. Pairing the gas-mass fractions with existing kinematics reveals a linear relationship between f {sub gas} and σ / v {sub c}, consistent with predictions from stability theory of a self-gravitating disk. It thus follows that high gas-velocity dispersions are a natural consequence of large gas fractions. We also find that the systems with the lowest t {sub dep} (∼0.5 Gyr) have the highest ratios of σ / v{sub c} and more pronounced clumps, even at the same high molecular gas fraction.

Ultrathin SnO2 nanorods: template- and surfactant-free solution phase synthesis, growth mechanism, optical, gas-sensing, and surface adsorption properties.

Science.gov (United States)

Xi, Guangcheng; Ye, Jinhua

2010-03-01

A novel template- and surfactant-free low temperature solution-phase method has been successfully developed for the controlled synthesis of ultrathin SnO(2) single-crystalline nanorods for the first time. The ultrathin SnO(2) single-crystalline nanorods are 2.0 +/- 0.5 nm in diameter, which is smaller than its exciton Bohr radius. The ultrathin SnO(2) nanorods show a high specific area (191.5 m(2) g(-1)). Such a thin SnO(2) single-crystalline nanorod is new in the family of SnO(2) nanostrucures and presents a strong quantum confinement effect. Its formation depends on the reaction temperature as well as on the concentration of the urea solution. A nonclassical crystallization process, Ostwald ripening process followed by an oriented attachment mechanism, is proposed based on the detailed observations from a time-dependent crystal evolution process. Importantly, such structured SnO(2) has shown a strong structure-induced enhancement of gas-sensing properties and has exhibited greatly enhanced gas-sensing property for the detection of ethanol than that of other structured SnO(2), such as the powders of nanobelts and microrods. Moreover, these ultrathin SnO(2) nanorods exhibit excellent ability to remove organic pollutant in wastewater by enormous surface adsorption. These properties are mainly attributed to its higher surface-to-volume ratio and ultrathin diameter. This work provides a novel low temperature, green, and inexpensive pathway to the synthesis of ultrathin nanorods, offering a new material form for sensors, solar cells, catalysts, water treatments, and other applications.

Investigations into surfactant/gas hydrate relationship

Energy Technology Data Exchange (ETDEWEB)

Rogers, Rudy; Zhang, Guochang; Dearman, Jennifer; Woods, Charles [Swalm School of Chemical Engineering, Mississippi State University, Mississippi State, MS 39762 (United States)

2007-03-15

Gas hydrates have unique physical properties portending useful industrial applications of gas storage, gas separation, or water desalination. When gas hydrates were found in the early 1990s to occur naturally and abundantly in seafloors, three other primary interests and concerns emerged: potential new energy source, climate threat from their greenhouse gases, and seafloor instabilities. This paper presents research showing how anionic synthetic surfactants helped develop an industrial gas hydrate storage process for natural gas and how naturally-occurring in-situ anionic biosurfactants influence the formation and placement of gas hydrates in ocean sediments. The catalytic effects, mechanisms, and surface specificities imparted by synthetic surfactants in the gas storage process and imparted by biosurfactants in porous media are discussed. The Bacillus subtilis bacterium that is indigenous to gas hydrate mounds in the Gulf of Mexico was cultured in the laboratory. Its biosurfactant was separated and found to catalyze gas hydrates in porous media. The experiments indicate that seafloor-biosurfactants can be produced rapidly in-situ to achieve threshold concentrations whereby hydrates are promoted. The biosurfactants accumulate and promote hydrate formation on specific mineral surfaces such as sodium montmorillonite. (author)

Off-gas control project

International Nuclear Information System (INIS)

Torgerson, D.F.; Smith, I.M.

1978-06-01

A program to develop and study off-gas abatement techniques has recently been initiated at Whiteshell Nuclear Research Establishment (WNRE). This report provides information on the properties and expected behaviour of reprocessing plant off-gases, and outlines the experimental program to be undertaken. (author)

Acetylene Gas-Sensing Properties of Layer-by-Layer Self-Assembled Ag-Decorated Tin Dioxide/Graphene Nanocomposite Film

Directory of Open Access Journals (Sweden)

Chuanxing Jiang

2017-09-01

Full Text Available This paper demonstrates an acetylene gas sensor based on an Ag-decorated tin dioxide/reduced graphene oxide (Ag–SnO2/rGO nanocomposite film, prepared by layer-by-layer (LbL self-assembly technology. The as-prepared Ag–SnO2/rGO nanocomposite was characterized by scanning electron microscopy (SEM, transmission electron microscopy (TEM, X-ray diffraction (XRD and Raman spectrum. The acetylene sensing properties were investigated using different working temperatures and gas concentrations. An optimal temperature of 90 °C was determined, and the Ag–SnO2/rGO nanocomposite sensor exhibited excellent sensing behaviors towards acetylene, in terms of response, repeatability, stability and response/recovery characteristics, which were superior to the pure SnO2 and SnO2/rGO film sensors. The sensing mechanism of the Ag–SnO2/rGO sensor was attributed to the synergistic effect of the ternary nanomaterials, and the heterojunctions created at the interfaces between SnO2 and rGO. This work indicates that the Ag–SnO2/rGO nanocomposite is a good candidate for constructing a low-temperature acetylene sensor.

Acetylene Gas-Sensing Properties of Layer-by-Layer Self-Assembled Ag-Decorated Tin Dioxide/Graphene Nanocomposite Film

Science.gov (United States)

Jiang, Chuanxing; Yin, Nailiang; Yao, Yao; Shaymurat, Talgar; Zhou, Xiaoyan

2017-01-01

This paper demonstrates an acetylene gas sensor based on an Ag-decorated tin dioxide/reduced graphene oxide (Ag–SnO2/rGO) nanocomposite film, prepared by layer-by-layer (LbL) self-assembly technology. The as-prepared Ag–SnO2/rGO nanocomposite was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectrum. The acetylene sensing properties were investigated using different working temperatures and gas concentrations. An optimal temperature of 90 °C was determined, and the Ag–SnO2/rGO nanocomposite sensor exhibited excellent sensing behaviors towards acetylene, in terms of response, repeatability, stability and response/recovery characteristics, which were superior to the pure SnO2 and SnO2/rGO film sensors. The sensing mechanism of the Ag–SnO2/rGO sensor was attributed to the synergistic effect of the ternary nanomaterials, and the heterojunctions created at the interfaces between SnO2 and rGO. This work indicates that the Ag–SnO2/rGO nanocomposite is a good candidate for constructing a low-temperature acetylene sensor. PMID:28927021

Gas Bubble Migration and Trapping in Porous Media: Pore-Scale Simulation

Science.gov (United States)

Mahabadi, Nariman; Zheng, Xianglei; Yun, Tae Sup; van Paassen, Leon; Jang, Jaewon

2018-02-01

Gas bubbles can be naturally generated or intentionally introduced in sediments. Gas bubble migration and trapping affect the rate of gas emission into the atmosphere or modify the sediment properties such as hydraulic and mechanical properties. In this study, the migration and trapping of gas bubbles are simulated using the pore-network model extracted from the 3D X-ray image of in situ sediment. Two types of bubble size distribution (mono-sized and distributed-sized cases) are used in the simulation. The spatial and statistical bubble size distribution, residual gas saturation, and hydraulic conductivity reduction due to the bubble trapping are investigated. The results show that the bubble size distribution becomes wider during the gas bubble migration due to bubble coalescence for both mono-sized and distributed-sized cases. And the trapped bubble fraction and the residual gas saturation increase as the bubble size increases. The hydraulic conductivity is reduced as a result of the gas bubble trapping. The reduction in hydraulic conductivity is apparently observed as bubble size and the number of nucleation points increase.

Detection of gas hydrate with downhole logs and assessment of gas hydrate concentrations (saturations) and gas volumes on the Blake Ridge with electrical resistivity log data

Science.gov (United States)

Collett, T.S.; Ladd, J.

2000-01-01

Let 164 of the Ocean Drilling Program was designed to investigate the occurrence of gas hydrate in the sedimentary section beneath the Blake Ridge on the southeastern continental margin of North America. Site 994, and 997 were drilled on the Blake Ridge to refine our understanding of the in situ characteristics of natural gas hydrate. Because gas hydrate is unstable at surface pressure and temperature conditions, a major emphasis was placed on the downhole logging program to determine the in situ physical properties of the gas hydrate-bearing sediments. Downhole logging tool strings deployed on Leg 164 included the Schlumberger quad-combination tool (NGT, LSS/SDT, DIT, CNT-G, HLDT), the Formation MicroScanner (FMS), and the Geochemical Combination Tool (GST). Electrical resistivity (DIT) and acoustic transit-time (LSS/SDT) downhole logs from Sites 994, 995, and 997 indicate the presence of gas hydrate in the depth interval between 185 and 450 mbsf on the Blake Ridge. Electrical resistivity log calculations suggest that the gas hydrate-bearing sedimentary section on the Blake Ridge may contain between 2 and 11 percent bulk volume (vol%) gas hydrate. We have determined that the log-inferred gas hydrates and underlying free-gas accumulations on the Blake Ridge may contain as much as 57 trillion m3 of gas.

Thermodynamic properties of hyperbranched polymer, Boltorn U3000, using inverse gas chromatography.

Science.gov (United States)

Domańska, Urszula; Zołek-Tryznowska, Zuzanna

2009-11-19

Mass-fraction activity coefficients at infinite dilution (Omega13(infinity)) of alkanes (C5-C10), cycloalkanes (C5-C8), alkenes (C5-C8), alkynes (C5-C8), aromatic hydrocarbons (benzene, toluene, ethylbenzene, o-, m-, p-xylene, thiophene), alcohols (C1-C5), water, ethers (tetrahydrofuran (THF), methyl-tert-butylether (MTBE), diethyl-, di-n-propyl-, di-n-butyl ether), and ketones (propanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, cyclopentanone) in the hyperbranched polymer, Boltorn U3000 (B-U3000), have been determined by inverse gas chromatography (IGC) using the polymer as the stationary phase. The measurements were carried out at different temperatures between 308.15 and 348.15 K. The density and thermophysical properties of polymer were described. The specific retention volume (V(g)), the Flory-Huggins interaction parameter (chi13(infinity)), the molar enthalpy of sorption (the partial molar enthalpies of solute dissolution) (Delta(s)H), the partial molar excess enthalpy at infinite dilution of the solute and polymer (DeltaH1(E,infinity)), the partial molar Gibbs excess energy at infinite dilution (DeltaG1(E,infinity)), and the solubility parameter (delta3) were calculated.

Voltage- and Light-Controlled Spin Properties of a Two-Dimensional Hole Gas in p-Type GaAs/AlAs Resonant Tunneling Diodes

Science.gov (United States)

Galeti, H. V. A.; Galvão Gobato, Y.; Brasil, M. J. S. P.; Taylor, D.; Henini, M.

2018-03-01

We have investigated the spin properties of a two-dimensional hole gas (2DHG) formed at the contact layer of a p-type GaAs/AlAs resonant tunneling diode (RTD). We have measured the polarized-resolved photoluminescence of the RTD as a function of bias voltage, laser intensity and external magnetic field up to 15T. By tuning the voltage and the laser intensity, we are able to change the spin-splitting from the 2DHG from almost 0 meV to 5 meV and its polarization degree from - 40% to + 50% at 15T. These results are attributed to changes of the local electric field applied to the two-dimensional gas which affects the valence band and the hole Rashba spin-orbit effect.

Study of the MWPC gas gain behaviour as a function of the gas pressure and temperature

CERN Document Server

Pinci, D

2005-01-01

The Muon System of the LHCb experiment is composed of five detection stations (M1-M5) equipped with 1368 Multi-Wire Proportional Chambers (MWPC) and 24 Triple-GEM detectors. The Multi Wire Proportional Chamber (MWPC) performances (detection efficiency, time resolution, pad-cluster size and ageing properties) are heavily dependent on the gas gain. The chamber gain depends on the gas density and therefore on the gas temperature and pressure. The impact of the environmental parameters on the MWPC gain has been studied in detail. The results, togheter with a simple method proposed to account for the gain variations, are reported in this note. The absolute gas gain at the testing voltage of 2750 V was also measured to be (1.2 +- 0.1)*10^5.

Market for oil and gas assets defined in survey

International Nuclear Information System (INIS)

Taggart, L.; Murry, D.A.

1991-01-01

This paper reports that hundreds of companies are currently active in the oil and gas acquisition and disposition marketplace, but unfortunately, the entire sale process within the industry continues to operate inefficiently. The mechanism for selling oil and gas properties in this secondary market - as used here, a term that excludes initial investments in oil and gas assets and sales of drilling program shares - is sort of catch-as-catch- can. Identifying who is seeking what type of property at any time is difficult, bordering on guesswork. A recent survey of 186 company representatives and individuals, who declared themselves as in the market, disclosed some of this information at a point in time

D-Dimensional ideal gas in parastatistics.: thermodynamic properties

International Nuclear Information System (INIS)

Sousa Vieira, M. C. de; Tsallis, C.

1986-01-01

A parastatistics ideal gas with energy spectrum ε is proportional to |k| → sup (α) (α>0) or even more general in a d-dimensional box with volume V (periodic boundary conditions), the number N of the gas particles being well determined (real particles) or not (quasi particles), is considered. The main thermodynamic quantities (chemical potential, internal energy, specific heat C, equation of state, latent heat, average numbers of particles) for arbitrary d,α, T (temperature) and p (maximal number of particles per state allowed in the parastatistics), are calculated. The main asymptotic regimes are worked out explicitly. In particular, the Bose-Einstein condensation for fixed density, N/V appears as a non uniform convergence in the p→ ∞ limit, in complete analogy with the standard critical phenomena which appear in interacting systems in the N →∞ limit. The system behaves essentially like a Fermi-Dirac one for all finite values of p, and reveals a Bose-Einstein behavior only in the p → ∞ limit. For instance, at low temperatures C ∝ T if p d/α if p → ∞. Finally the Sommerfeld integral and its expansion are generalized to an arbitrary finite p. (author) [pt

Soil properties, greenhouse gas emissions and crop yield under compost, biochar and co-composted biochar in two tropical agronomic systems

Energy Technology Data Exchange (ETDEWEB)

Bass, Adrian M., E-mail: adrian.bass@glasgow.ac.uk [Centre for Tropical Environmental and Sustainability Science, College of Science, Technology and Engineering, James Cook University, Cairns, Queensland 4870 (Australia); Bird, Michael I. [Centre for Tropical Environmental and Sustainability Science, College of Science, Technology and Engineering, James Cook University, Cairns, Queensland 4870 (Australia); Kay, Gavin [Terrain Natural Resource Management, 2 Stitt Street, Innisfail, Queensland 4860 (Australia); Muirhead, Brian [Northern Gulf Resource Management Group, 317 Byrnes Street, Mareeba, Queensland 4880 (Australia)

2016-04-15

ABSTRACT: The addition of organic amendments to agricultural soils has the potential to increase crop yields, reduce dependence on inorganic fertilizers and improve soil condition and resilience. We evaluated the effect of biochar (B), compost (C) and co-composted biochar (COMBI) on the soil properties, crop yield and greenhouse gas emissions from a banana and a papaya plantation in tropical Australia in the first harvest cycle. Biochar, compost and COMBI organic amendments improved soil properties, including significant increases in soil water content, CEC, K, Ca, NO{sub 3}, NH{sub 4} and soil carbon content. However, increases in soil nutrient content and improvements in physical properties did not translate to improved fruit yield. Counter to our expectations, banana crop yield (weight per bunch) was reduced by 18%, 12% and 24% by B, C and COMBI additions respectively, and no significant effect was observed on the papaya crop yield. Soil efflux of CO{sub 2} was elevated by addition of C and COMBI amendments, likely due to an increase in labile carbon for microbial processing. Our data indicate a reduction in N{sub 2}O flux in treatments containing biochar. The application of B, C and COMBI amendments had a generally positive effect on soil properties, but this did not translate into a crop productivity increase in this study. The benefits to soil nutrient content, soil carbon storage and N{sub 2}O emission reduction need to be carefully weighed against potentially deleterious effects on crop yield, at least in the short-term. - Highlights: • Biochar and compost amendment has potential to improve tropical agriculture. • We monitored soil health, gas fluxes and crop yield under biochar and compost. • Biochar improved soil nutrient content, water retention and reduced N{sub 2}O emissions. • Biochar significantly reduced banana yield performance and did not affect papaya yield. • Organic amendment is not an ‘always win’ scenario for tropical

Soil properties, greenhouse gas emissions and crop yield under compost, biochar and co-composted biochar in two tropical agronomic systems

International Nuclear Information System (INIS)

Bass, Adrian M.; Bird, Michael I.; Kay, Gavin; Muirhead, Brian

2016-01-01

ABSTRACT: The addition of organic amendments to agricultural soils has the potential to increase crop yields, reduce dependence on inorganic fertilizers and improve soil condition and resilience. We evaluated the effect of biochar (B), compost (C) and co-composted biochar (COMBI) on the soil properties, crop yield and greenhouse gas emissions from a banana and a papaya plantation in tropical Australia in the first harvest cycle. Biochar, compost and COMBI organic amendments improved soil properties, including significant increases in soil water content, CEC, K, Ca, NO_3, NH_4 and soil carbon content. However, increases in soil nutrient content and improvements in physical properties did not translate to improved fruit yield. Counter to our expectations, banana crop yield (weight per bunch) was reduced by 18%, 12% and 24% by B, C and COMBI additions respectively, and no significant effect was observed on the papaya crop yield. Soil efflux of CO_2 was elevated by addition of C and COMBI amendments, likely due to an increase in labile carbon for microbial processing. Our data indicate a reduction in N_2O flux in treatments containing biochar. The application of B, C and COMBI amendments had a generally positive effect on soil properties, but this did not translate into a crop productivity increase in this study. The benefits to soil nutrient content, soil carbon storage and N_2O emission reduction need to be carefully weighed against potentially deleterious effects on crop yield, at least in the short-term. - Highlights: • Biochar and compost amendment has potential to improve tropical agriculture. • We monitored soil health, gas fluxes and crop yield under biochar and compost. • Biochar improved soil nutrient content, water retention and reduced N_2O emissions. • Biochar significantly reduced banana yield performance and did not affect papaya yield. • Organic amendment is not an ‘always win’ scenario for tropical agriculture.

arXiv Candidate eco-friendly gas mixtures for MPGDs

CERN Document Server

Benussi, L.; Saviano, G.; Muhammad, S.; Ferrini, M.; Primavera, F.; Parvis, M.; Grassing, S.; Colafranceschi, S.; Kjøbro, J.; Sharma, A.; Yang, D.; Chen, G.; Ban, Y.; Li, Q.

2018-01-01

Modern gas detectors for detection of particles require F-based gases for optimal performance. Recent regulations demand the use of environmentally unfriendly F-based gases to be limited or banned. This review studies properties of potential eco-friendly gas candidate replacements.

Synthesis, Crystal Structure, Gas Absorption, and Separation Properties of a Novel Complex Based on Pr and a Three-Connected Ligand

Directory of Open Access Journals (Sweden)

Jie Sun

2017-12-01

Full Text Available A novel Pr complex, constructed from a rigid three-connected H3TMTA and praseodymium(III ion, has been synthesized in a mixed solvent system and characterized by X-ray single crystal diffraction, infrared spectroscopy, a thermogravimetric analysis, an element analysis, and powder X-ray diffraction, which reveals that complex 1 crystallizes in a three-dimensional porous framework. Moreover, the thermal stabilities and the fluorescent and gas adsorption and separation properties of complex 1 were investigated systematically.

Flow regimes in vertical gas-solid contact systems

Energy Technology Data Exchange (ETDEWEB)

Yerushalmi, J.; Cankurt, N. T.; Geldart, D.; Liss, B.

1976-01-01

The flow characteristics in fluidized beds, i.e., gas-solid systems, was studied to determine the flow regimes, the interaction of gas and solid in the various flow regimes and the dependence of this interaction and of transition between flow regimes on the properties of the gas and solid, on the gas and solid flow rates, and on the containing vessel. Fluidized beds with both coarse and fine particles are considered. Test results using high speed photography to view the operation of a 2-dimensional bed are discussed. (LCL)

Properties of high pressure nitrogen-argon and nitrogen-xenon gas scintillators

International Nuclear Information System (INIS)

Tornow, W.; Huck, H.; Koeber, H.J.; Mertens, G.

1976-01-01

Investigations of scintillation light output and energy resolution have been made at pressures up to 90 atm in gaseous mixtures of nitrogen with both argon and xenon by stopping of 210 Po-alpha particles. In the absence of a wavelength shifter, the N 2 -Ar mixtures gave a maximum pulse height at a ratio of nitrogen to argon partial pressures rsub(N 2 /Ar) approximately =0.2. However, when using the wavelength shifter diphenyl stilbene (DPS), the measured light output was much larger at lower values of rsub(N 2 /Ar), whereas for rsub(N 2 /Ar)>0.2 pulse height and energy resolution of the studied N 2 -Ar mixtures were roughly indentical with and without DPS. The N 2 -Xe gas mixtures exhibited a similar dependence of pulse height and energy resolution to that of the N 2 -Ar mixtures employing DPS, but the pulse height was larger by a factor of about 7. A 40 atm 50% N 2 -50% Xe gas scintillator showed an energy resolution ΔE/E=0.25, while an 80 atm 75% N 2 -25% Xe scintillator gave ΔE/E=0.6. The pulse height from the 80 atm N 2 -Xe scintillator was smaller by a factor of about 240 than the pulse height from a 20 atm pure Xe gas scintillator, but larger by a factor of about 20 than the pulse height from a 75 atm pure N 2 gas scintillator. The N 2 -Xe mixtures showed a remarkable increase of light output as the temperature of the gas was descreased. (Auth.)

Improvement in ferroelectric properties of Pt/PZT/Pt capacitors etched as a function of Ar/O2 gas mixing ratio into Cl2/CF4 plasma

International Nuclear Information System (INIS)

Lim, Kyu-Tae; Koo, Seong-Mo; Kim, Kyoung-Tae; Kim, Dong-Pyo; Kim, Chang-Il

2004-01-01

In this work, to investigate improvement of the damage using oxygen containing plasma, we etched PZT films as a function of Ar (x%)/O 2 (y%) gas mixing ratio in Cl 2 (56%)/CF 4 (14%) plasma (where the sum of x and y is 30). The maximum etch rate of the PZT thin films was 146 nm/min for Ar (30%)/O 2 (0%) added into the Cl 2 /CF 4 plasma. After the etching, the plasma-induced damages were characterized in terms of hysteresis curves, leakage current, switching polarization and retention capacity as a function of the gas mixing ratio. When the ferroelectric properties of PZT films were etched as a function of O 2 and Ar and the gas mixing ratios were compared, the value of remnant polarization in O 2 (30%) added Cl 2 /CF 4 plasma is higher than that in Ar (30%). The results showed that after the etching the charges accumulated by oxygen vacancies prevented further domain switching at the top electrode-ferroelectric interface and created leakage current because of modification of the interfacial Schottky barrier during the etching process. The physical damage to the near surface and the crystal structure of the etched PZT thin films was evaluated by using X-ray diffraction (XRD). The remnant polarization, leakage current, retention and fatigue properties are improved with increasing O 2 content. From XRD results, the improvement in the ferroelectric properties of PZT capacitors etched in O 2 containing plasma was consistent with the increased intensities of the (100) and (200) peaks

Cross sections and transport properties for Na+ in (DXE gas

Directory of Open Access Journals (Sweden)

Nikitović Željka D.

2016-01-01

Full Text Available In this work we select most probable reactions of alkali metal ion Na+ with dimethoxyethane (DXE molecule. Appropriate gas phase enthalpies of formation for the products were used to calculate scattering cross section as a function of kinetic energy with Denpoh-Nanbu theory. Calculated cross sections were compared with existing experimental results obtained by guided ion beam tandem mass spectrometry. Three body association reactions of ions with DXE is studied and compared to experimental results. Calculated cross sections were used to obtain transport parameters for alkali metal ion in DXE gas. [Projekat Ministarstva nauke Republike Srbije, br. ON 171037 i br. III 410011

Real-gas effects 1: Simulation of ideal gas flow by cryogenic nitrogen and other selected gases

Science.gov (United States)

Hall, R. M.

1980-01-01

The thermodynamic properties of nitrogen gas do not thermodynamically approximate an ideal, diatomic gas at cryogenic temperatures. Choice of a suitable equation of state to model its behavior is discussed and the equation of Beattie and Bridgeman is selected as best meeting the needs for cryogenic wind tunnel use. The real gas behavior of nitrogen gas is compared to an ideal, diatomic gas for the following flow processes: isentropic expansion; normal shocks; boundary layers; and shock wave boundary layer interactions. The only differences in predicted pressure ratio between nitrogen and an ideal gas that may limit the minimum operating temperatures of transonic cryogenic wind tunnels seem to occur at total pressures approaching 9atmospheres and total temperatures 10 K below the corresponding saturation temperature, where the differences approach 1 percent for both isentropic expansions and normal shocks. Several alternative cryogenic test gases - air, helium, and hydrogen - are also analyzed. Differences in air from an ideal, diatomic gas are similar in magnitude to those of nitrogen. Differences for helium and hydrogen are over an order of magnitude greater than those for nitrogen or air. Helium and hydrogen do not approximate the compressible flow of an ideal, diatomic gas.

Effect of electronegative additives on physical properties and chemical activity of gas discharge plasma

Science.gov (United States)

Kuznetsov, D. L.; Filatov, I. E.; Uvarin, V. V.

2018-01-01

Effect of electronegative additives (oxygen O2, sulfur dioxide SO2, carbon disulfide CS2, and carbon tetrachloride CCl4) on physical properties and chemical activity of plasma formed by pulsed corona discharge and by non-self-sustained discharge supported by pulsed electron beam in atmospheric pressure gas mixtures was investigated. It is shown that a decrease in discharge current depends on a sort of the additive and on its concentration. The reason is the difference in rate constants of electron attachment processes for the above molecules. In experiments on volatile organic compounds (VOCs) conversion in air by streamer corona it is obtained that an addition of CCl4 both decreases the discharge current amplitude and increases the VOCs conversion degree. An installation for investigation of electron attachment processes and for study of toxic impurities conversion in plasma formed by non-self-sustained discharge initiated by pulsed nanosecond electron beam is created.

Possibility of gas sensor based on C_2_0 molecular devices

International Nuclear Information System (INIS)

Zhao, Wenkai; Yang, Chuanlu; Zou, Dongqing; Sun, Zhaopeng; Ji, Guomin

2017-01-01

We theoretically investigate the possibility of diatomic gas detection (NO, CO, O_2) by making use of the transport properties of the C_2_0 molecular junctions. The calculations are performed by using nonequilibrium Green's function (NEGF) formalism in combination with density functional theory (DFT). In this work, we systematically study the most stable adsorption structural configurations, adsorption energy, and the transport properties on C_2_0 molecular junctions with these diatomic gas molecules. It is found that NO and O_2 gas molecule can be detected selectively. We suggest its possibility of nanosensors for highly sensitive and selective based on C_2_0 molecular junction systems. - Highlights: • The most favorable adsorption site is investigated. • The mechanism of gas sensors is revealed. • NO and O_2 gas molecules can be detected by C_2_0 selectively.

Gas Sensing Properties of Pure and Cr Activated WO3 Thick Film Resistors

Directory of Open Access Journals (Sweden)

V. B. GAIKWAD

2010-09-01

Full Text Available Thick films of WO3 (Tungsten Oxide were prepared by screen-printing techniques. The surfaces of the films were modified by dipping them into an aqueous solution of Chromium Oxide (CrO3 for different intervals of time, followed by firing at 550 oC for 30 min. The gas sensing performance of the pure and Cr2O3-modified films was tested for various gases at different temperatures. The unmodified films showed response to H2S, ethanol and cigar smoke. However Cr2O3- modified films suppresses gas sensing response to all gases except H2S. The surface modification, using dipping process, altered the adsorbate-adsorbent interactions, which gave the specific selectivity and enhanced sensitivity to H2S gas. The gas response, selectivity, thermal stability and recovery time of the sensor were measured and presented. The role played by surface chromium species to improve gas sensing performance is discussed.

Effect of coagulant bath on the gas permeation properties of cellulose acetate asymmetric membrane

Science.gov (United States)

Mohamed, F.; Hasbullah, H.; Jami'an, W. N. R.; Salleh, W. N. H. W.; Ibrahim, N.; Ali, R. R.

2016-06-01

Membrane based gas separation process technology has been recognized as one of the most efficient and advanced unit operation for gas separation. One of the problems in membrane gas separation is membrane performance. This paper explores the application of cellulose acetate (CA) membrane for natural gas purification and separation by improving its permeability and selectivity. The main interest in this research is to study the effect of quench medium on the gas separation performance towards its physical characteristics and gas separation performance of CA membrane. Cellulose acetate polymer was dissolved in n- methyl-2-pyrrolidone solvent and casted onto a glass plate using a pneumatically controlled casting system with fixed shear rate and solvent evaporation times. The parameter varied was the non-solvent used as quench medium during membrane post treatment that were methanol and n-hexane. The different quench media as post treatment affected the O2 and N2 gas permeation and O2/N2 selectivity as well as the tensile strength of the flat sheet asymmetric membrane. Combination of methanol and n-hexane as quench media gave the best result than the other steps. This solvent exchange step influenced the morphology by producing thin skin layer and thus gives better gas separation performance than other steps

Detection of a gas flaring signature in the AERONET optical properties of aerosols at a tropical station in West Africa

Science.gov (United States)

Fawole, Olusegun G.; Cai, Xiaoming; Levine, James G.; Pinker, Rachel T.; MacKenzie, A. R.

2016-12-01

The West African region, with its peculiar climate and atmospheric dynamics, is a prominent source of aerosols. Reliable and long-term in situ measurements of aerosol properties are not readily available across the region. In this study, Version 2 Level 1.5 Aerosol Robotic Network (AERONET) data were used to study the absorption and size distribution properties of aerosols from dominant sources identified by trajectory analysis. The trajectory analysis was used to define four sources of aerosols over a 10 year period. Sorting the AERONET aerosol retrievals by these putative sources, the hypothesis that there exists an optically distinct gas flaring signal was tested. Dominance of each source cluster varies with season: desert-dust (DD) and biomass burning (BB) aerosols are dominant in months prior to the West African Monsoon (WAM); urban (UB) and gas flaring (GF) aerosol are dominant during the WAM months. BB aerosol, with single scattering albedo (SSA) at 675 nm value of 0.86 ± 0.03 and GF aerosol with SSA (675 nm) value of 0.9 ± 0.07, is the most absorbing of the aerosol categories. The range of Absorption Angstr&öm Exponent (AAE) for DD, BB, UB and GF classes are 1.99 ± 0.35, 1.45 ± 0.26, 1.21 ± 0.38 and 0.98 ± 0.25, respectively, indicating different aerosol composition for each source. The AAE (440-870 nm) and Angstr&öm Exponent (AE) (440-870 nm) relationships further show the spread and overlap of the variation of these optical and microphysical properties, presumably due in part to similarity in the sources of aerosols and in part, due to mixing of air parcels from different sources en route to the measurement site.

Gas sensing in 2D materials

Science.gov (United States)

Yang, Shengxue; Jiang, Chengbao; Wei, Su-huai

2017-06-01

Two-dimensional (2D) layered inorganic nanomaterials have attracted huge attention due to their unique electronic structures, as well as extraordinary physical and chemical properties for use in electronics, optoelectronics, spintronics, catalysts, energy generation and storage, and chemical sensors. Graphene and related layered inorganic analogues have shown great potential for gas-sensing applications because of their large specific surface areas and strong surface activities. This review aims to discuss the latest advancements in the 2D layered inorganic materials for gas sensors. We first elaborate the gas-sensing mechanisms and introduce various types of gas-sensing devices. Then, we describe the basic parameters and influence factors of the gas sensors to further enhance their performance. Moreover, we systematically present the current gas-sensing applications based on graphene, graphene oxide (GO), reduced graphene oxide (rGO), functionalized GO or rGO, transition metal dichalcogenides, layered III-VI semiconductors, layered metal oxides, phosphorene, hexagonal boron nitride, etc. Finally, we conclude the future prospects of these layered inorganic materials in gas-sensing applications.

State and trends of ionization gas analysis. 1

International Nuclear Information System (INIS)

Leonhardt, J.W.; Grosse, H.J.; Popp, P.

1980-01-01

The ionization gas analysis makes use of the fact that the ionization-induced conductivity of gases and gas mixtures changes with the composition of such mixtures. A general description is given of ionization detectors based on this principle and theory, properties, and main fields of application of electron capture detectors are discussed

Poiseuille, thermal transpiration and Couette flows of a rarefied gas between plane parallel walls with nonuniform surface properties in the transverse direction and their reciprocity relations

Science.gov (United States)

Doi, Toshiyuki

2018-04-01

Slow flows of a rarefied gas between two plane parallel walls with nonuniform surface properties are studied based on kinetic theory. It is assumed that one wall is a diffuse reflection boundary and the other wall is a Maxwell-type boundary whose accommodation coefficient varies periodically in the direction perpendicular to the flow. The time-independent Poiseuille, thermal transpiration and Couette flows are considered. The flow behavior is numerically studied based on the linearized Bhatnagar-Gross-Krook-Welander model of the Boltzmann equation. The flow field, the mass and heat flow rates in the gas, and the tangential force acting on the wall surface are studied over a wide range of the gas rarefaction degree and the parameters characterizing the distribution of the accommodation coefficient. The locally convex velocity distribution is observed in Couette flow of a highly rarefied gas, similarly to Poiseuille flow and thermal transpiration. The reciprocity relations are numerically confirmed over a wide range of the flow parameters.

Determination of dynamic variations in the optical properties of graphene oxide in response to gas exposure based on thin-film interference.

Science.gov (United States)

Tabassum, Shawana; Dong, Liang; Kumar, Ratnesh

2018-03-05

We present an effective yet simple approach to study the dynamic variations in optical properties (such as the refractive index (RI)) of graphene oxide (GO) when exposed to gases in the visible spectral region, using the thin-film interference method. The dynamic variations in the complex refractive index of GO in response to exposure to a gas is an important factor affecting the performance of GO-based gas sensors. In contrast to the conventional ellipsometry, this method alleviates the need of selecting a dispersion model from among a list of model choices, which is limiting if an applicable model is not known a priori. In addition, the method used is computationally simpler, and does not need to employ any functional approximations. Further advantage over ellipsometry is that no bulky optics is required, and as a result it can be easily integrated into the sensing system, thereby allowing the reliable, simple, and dynamic evaluation of the optical performance of any GO-based gas sensor. In addition, the derived values of the dynamically changing RI values of the GO layer obtained from the method we have employed are corroborated by comparing with the values obtained from ellipsometry.

Carbon nanomaterials for gas adsorption

CERN Document Server

Terranova, Maria Letizia

2012-01-01

Research in adsorption of gases by carbon nanomaterials has experienced considerable growth in recent years, with increasing interest for practical applications. Many research groups are now producing or using such materials for gas adsorption, storage, purification, and sensing. This book provides a selected overview of some of the most interesting scientific results regarding the outstanding properties of carbon nanomaterials for gas adsorption and of interest both for basic research and technological applications. Topics receiving special attention in this book include storage of H, purific

Sol-Gel Thin Films for Plasmonic Gas Sensors

Science.gov (United States)

Della Gaspera, Enrico; Martucci, Alessandro

2015-01-01

Plasmonic gas sensors are optical sensors that use localized surface plasmons or extended surface plasmons as transducing platform. Surface plasmons are very sensitive to dielectric variations of the environment or to electron exchange, and these effects have been exploited for the realization of sensitive gas sensors. In this paper, we review our research work of the last few years on the synthesis and the gas sensing properties of sol-gel based nanomaterials for plasmonic sensors. PMID:26184216

18 CFR 367.58 - Property record system required for service company property.

Science.gov (United States)

2010-04-01

... to show the nature of each addition to or retirement of service company property, the related total... required for service company property. 367.58 Section 367.58 Conservation of Power and Water Resources... COMPANY ACT OF 2005, FEDERAL POWER ACT AND NATURAL GAS ACT UNIFORM SYSTEM OF ACCOUNTS FOR CENTRALIZED...

First Fifty Years of Chemoresistive Gas Sensors

Directory of Open Access Journals (Sweden)

Giovanni Neri

2015-01-01

Full Text Available The first fifty years of chemoresistive sensors for gas detection are here reviewed, focusing on the main scientific and technological innovations that have occurred in the field over the course of these years. A look at advances made in fundamental and applied research and leading to the development of actual high performance chemoresistive devices is presented. The approaches devoted to the synthesis of novel semiconducting materials with unprecedented nanostructure and gas-sensing properties have been also presented. Perspectives on new technologies and future applications of chemoresistive gas sensors have also been highlighted.

Quick pace of property acquisitions requires two-stage evaluations

International Nuclear Information System (INIS)

Hollo, R.; Lockwood, S.

1994-01-01

The traditional method of evaluating oil and gas reserves may be too cumbersome for the quick pace of oil and gas property acquisition. An acquisition evaluator must decide quickly if a property meets basic purchase criteria. The current business climate requires a two-stage approach. First, the evaluator makes a quick assessment of the property and submits a bid. If the bid is accepted then the evaluator goes on with a detailed analysis, which represents the second stage. Acquisition of producing properties has become an important activity for many independent oil and gas producers, who must be able to evaluate reserves quickly enough to make effective business decisions yet accurately enough to avoid costly mistakes. Independent thus must be familiar with how transactions usually progress as well as with the basic methods of property evaluation. The paper discusses acquisition activity, the initial offer, the final offer, property evaluation, and fair market value

Effect of long time service exposure on microstructure and mechanical properties of gas turbine vanes made of IN939 alloy

International Nuclear Information System (INIS)

Jahangiri, M.R.; Abedini, M.

2014-01-01

Highlights: • Microstructure of service-exposed turbine vanes made of IN939 was investigated. • Mechanical properties of service-exposed alloy were also investigated. • Formation of M 23 C 6 films on GBs and degeneration of MCs are microstructural changes. • Despite its thermodynamic favorability, σ phase is not observed in microstructure. • Microstructural changes lead to a loss in tensile ductility and creep life. - Abstract: In the present study, the effects of long-term service exposure have been investigated on microstructure and mechanical properties of gas turbine vanes made of IN939 superalloy. The major microstructural changes for the investigated service-exposed vanes include the formation of continuous grain boundary carbides and the transformation (degeneration) of MC carbides located at the grain boundaries. The brittle σ phase, which is predicted to be stable on the basis of thermodynamic calculations, is not observed in the microstructure of service-exposed vanes. The microstructural changes during service lead to a loss in room temperature ductility as well as in creep properties of the alloy

Fundamental thermochemical properties of amino acids: gas-phase and aqueous acidities and gas-phase heats of formation.

Science.gov (United States)

Stover, Michele L; Jackson, Virgil E; Matus, Myrna H; Adams, Margaret A; Cassady, Carolyn J; Dixon, David A

2012-03-08

The gas-phase acidities of the 20 L-amino acids have been predicted at the composite G3(MP2) level. A broad range of structures of the neutral and anion were studied to determine the lowest energy conformer. Excellent agreement is found with the available experimental gas-phase deprotonation enthalpies, and the calculated values are within experimental error. We predict that tyrosine is deprotonated at the CO(2)H site. Cysteine is predicted to be deprotonated at the SH but the proton on the CO(2)H is shared with the S(-) site. Self-consistent reaction field (SCRF) calculations with the COSMO parametrization were used to predict the pK(a)'s of the non-zwitterion form in aqueous solution. The differences in the non-zwitterion pK(a) values were used to estimate the free energy difference between the zwitterion and nonzwitterion forms in solution. The heats of formation of the neutral compounds were calculated from atomization energies and isodesmic reactions to provide the first reliable set of these values in the gas phase. Further calculations were performed on five rare amino acids to predict their heats of formation, acidities, and pK(a) values.

Fluctuation theory for transport properties in multicomponent mixtures: thermodiffusion and heat conductivity

DEFF Research Database (Denmark)

Shapiro, Alexander

2004-01-01

The theory of transport properties in multicomponent gas and liquid mixtures, which was previously developed for diffusion coefficients, is extended onto thermodiffusion coefficients and heat conductivities. The derivation of the expressions for transport properties is based on the general statis...... of the heat conductivity coefficient for ideal gas. (C) 2003 Elsevier B.V. All rights reserved.......The theory of transport properties in multicomponent gas and liquid mixtures, which was previously developed for diffusion coefficients, is extended onto thermodiffusion coefficients and heat conductivities. The derivation of the expressions for transport properties is based on the general...

Electronic and gas sensing properties of soluble phthalocyanines

Czech Academy of Sciences Publication Activity Database

Pochekaylov, Sergey; Rais, David; Nešpůrek, Stanislav; Rakušan, J.; Karásková, M.

2009-01-01

Roč. 27, č. 3 (2009), s. 781-795 ISSN 0137-1339. [International Conference on Electtrical and Related Properties of Organic Solids /11./. Wroclaw, 13.07.2008-17.07.2008] R&D Projects: GA AV ČR KAN400720701 Institutional research plan: CEZ:AV0Z40500505 Keywords : substituted phthalocyanine * nitrogen dioxide sensor * optical properties Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.384, year: 2009

Gas Mixtures for Welding with Micro-Jet Cooling