Journal articles: 'Gas barrier model'

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MAYDANYUK, SERGEI P. "A FULLY QUANTUM METHOD OF DETERMINATION OF PENETRABILITY AND REFLECTION COEFFICIENTS IN QUANTUM FRW MODEL WITH RADIATION." International Journal of Modern Physics D 19, no. 04 (April 2010): 395–435. http://dx.doi.org/10.1142/s0218271810016464.

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In the paper the closed Friedmann–Robertson–Walker model with quantization in the presence of the positive cosmological constant and radiation is studied. For analysis of tunneling probability for birth of an asymptotically de Sitter, inflationary universe as a function of the radiation energy, a new definition of a "free" wave propagating inside strong fields is proposed. On such a basis, tunneling boundary condition is corrected, penetrability and reflection relative to the barrier are calculated in fully quantum stationary approach. For the first time nonzero interference between the incident and reflected waves has been taken into account which turns out to play important role inside cosmological potentials and could be explained by non-locality of barriers in quantum mechanics. Inside the whole region of radiation energy the tunneling probability for the birth of the inflationary universe is found to be close to its value obtained in the semiclassical approach. The reflection from the barrier is determined for the first time (which differs essentially on 1 at the energy of radiation close to the barrier height). The proposed method could be easily generalized on the cosmological models with barriers of arbitrary shape, as demonstrated for the FRW model with included Chaplygin gas. The result is stable for variations of the studied barriers, accuracy is found to be 11–18 digits for all coefficients and energies below the barrier height.

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Wu, Haoyu, Maryam Zamanian, Boguslaw Kruczek, and Jules Thibault. "Gas Permeation Model of Mixed-Matrix Membranes with Embedded Impermeable Cuboid Nanoparticles." Membranes 10, no. 12 (December 15, 2020): 422. http://dx.doi.org/10.3390/membranes10120422.

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In the packaging industry, the barrier property of packaging materials is of paramount importance. The enhancement of barrier properties of materials can be achieved by adding impermeable nanoparticles into thin polymeric films, known as mixed-matrix membranes (MMMs). Three-dimensional numerical simulations were performed to study the barrier property of these MMMs and to estimate the effective membrane gas permeability. Results show that horizontally-aligned thin cuboid nanoparticles offer far superior barrier properties than spherical nanoparticles for an identical solid volume fraction. Maxwell’s model predicts very well the relative permeability of spherical and cubic nanoparticles over a wide range of the solid volume fraction. However, Maxwell’s model shows an increasingly poor prediction of the relative permeability of MMM as the aspect ratio of cuboid nanoparticles tends to zero or infinity. An artificial neural network (ANN) model was developed successfully to predict the relative permeability of MMMs as a function of the relative thickness and the relative projected area of the embedded nanoparticles. However, since an ANN model does not provide an explicit form of the relation of the relative permeability with the physical characteristics of the MMM, a new model based on multivariable regression analysis is introduced to represent the relative permeability in a MMM with impermeable cuboid nanoparticles. The new model possesses a simple explicit form and can predict, very well, the relative permeability over an extensive range of the solid volume fraction and aspect ratio, compared with many existing models.

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Miller, R. A. "Life Modeling of Thermal Barrier Coatings for Aircraft Gas Turbine Engines." Journal of Engineering for Gas Turbines and Power 111, no. 2 (April 1, 1989): 301–5. http://dx.doi.org/10.1115/1.3240251.

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Thermal barrier coating life models developed under the NASA Lewis Research Center’s Hot Section Technology (HOST) program are summarized. An initial laboratory model and three design-capable models are discussed. Current understanding of coating failure mechanisms is also summarized.

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Jiang, Peng, and Cheng Ye. "Recession of Environmental Barrier Coatings under High-Temperature Water Vapour Conditions: A Theoretical Model." Materials 13, no. 20 (October 10, 2020): 4494. http://dx.doi.org/10.3390/ma13204494.

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Rare-earth disilicates are the major material used on the top layer of environmental barrier coating (EBC) systems. Although rare-earth disilicates are highly resistant to water vapour, corrosion due to water vapour at high temperature is still one of the main reasons of failure of EBC systems. In this study, a corrosion model of ytterbium disilicates in water vapour at high temperature was derived, based on the gas diffusion theory. Using this theoretical model, we studied the evolution rule of the corroded area on the top layer of the EBC under gas flow at high temperature. The influence of the various parameters of the external gas on the corrosion process and the corrosion kinetics curve were also discussed. The theoretical model shows that the increase in gas temperature, gas flow velocity, water partial pressure, and total gas pressure accelerate coating corrosion. Among these factors, the influence of total gas pressure on the corrosion process is relatively weak, and the effect of the continuous increase of the gas velocity on the corrosion process is limited. The shape of the corrosion kinetics curve is either a straight or parabolic, and it was determined by a combination of external gas parameters.

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Vangpaisal, Thaveesak. "Simulation of Final Cover Systems in Mitigating Landfill Gas Migration." Applied Mechanics and Materials 587-589 (July 2014): 886–91. http://dx.doi.org/10.4028/www.scientific.net/amm.587-589.886.

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Landfill cover systems have to serve as a hydraulic barrier as well as a gas barrier. The ability of multilayered cover systems to mitigate landfill gas migration was assessed. A finite element model, SEEP/W®, was used to simulate the landfill cover system. It was found that gas advective flux through the single GCL barrier was highly dependent on the differential gas pressure across the cover system and the conditions of soils above the barrier layer. The change from wet to dry condition resulted in the increase of gas flux up to 3000 times. Gas flux variations were much lower for the case of a single CCL. The use of a geomembrane on top of a CCL or a GCL significantly increased the effectiveness of the barrier layer in mitigating gas migration, particularly in a dry climatic condition. Furthermore, the change of the cover conditions had less effect on gas flux through a composite cover system than gas flux through a single barrier cover system. For the effective control of landfill gas migration, the cover system must be maintained at the high moisture content conditions.

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Al-Abduljabbar, A. "Modeling Gas Barrier Property Improvements in Polymer-Clay Nano-Composites." Journal of Nano Research 29 (December 2014): 75–84. http://dx.doi.org/10.4028/www.scientific.net/jnanor.29.75.

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Polymer-clay nanocomposites (PCNC) offer better properties at very low volume fraction of the nanofiller compared to conventional polymer composites, thus minimizing the effect on other favored properties of the polymer. The mechanism by which clay platelets, which have thicknesses of a few nanometers in size compared with several hundred nanometers in the other two dimensions, introduce mechanical and other properties improvement can be attributed to their high efficiency in introducing a discontinuity to flows through the bulk matrix polymer material. The extent of this improvement depends on the success of intercalation or separation of the clay platelets through the bulk matrix. This paper contains a general overview of polymer-clay nanocomposites in terms of properties and processing. The improvements in gas barrier properties are discussed in detail; and a model to represent the effect of introduction of nanofillers on the permeability is proposed. The model builds on previous models to explain the improvements in the gas barrier properties due to the presence of clay nanoparticles and by assuming a proper distribution of these particles.

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Miller, R. A. "Progress Toward Life Modeling of Thermal Barrier Coatings for Aircraft Gas Turbine Engines." Journal of Engineering for Gas Turbines and Power 109, no. 4 (October 1, 1987): 448–51. http://dx.doi.org/10.1115/1.3240062.

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Progress toward developing life models for simulating the behavior of thermal barrier coatings in aircraft gas turbine engines is discussed. A preliminary laboratory model is described as are current efforts to develop engine-capable models. Current understanding into failure mechanisms is also summarized.

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Malagù, C., M. C. Carotta, G. Martinelli, M. A. Ponce, M. S. Castro, and C. M. Aldao. "Field-Assisted and Thermionic Contributions to Conductance in Thick-Films." Journal of Sensors 2009 (2009): 1–5. http://dx.doi.org/10.1155/2009/402527.

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A deep analysis of conductance in nanostructured thick films has been performed. A model for field-assisted thermionic barrier crossing is being proposed to explain the film conductivity. The model has been applied to explain the behavior of resistance in vacuum of two sets of nanostructured thick-films with grains having two well-distinct characteristic radii ( nm and nm). In the first case the grain radius is shorter than the depletion region width, a limit at which overlapping of barriers takes place, and in the second case it is longer. The behavior of resistance in the presence of dry air has been explained through the mechanism of barrier modulation through gas chemisorption.

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Wang, Hong Xun, Wei Fang Zhang, and Tian Jiao Liu. "Progress in Thermal Barrier Coatings for Gas Turbine Engines." Advanced Materials Research 941-944 (June 2014): 1625–28. http://dx.doi.org/10.4028/www.scientific.net/amr.941-944.1625.

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In recent years, the key research on thermal barrier coatings (TBCs) lies in the performance improvement of materials as well as structure and process improvement, and achieves new progresses. The difficulty is application of reliability in TBCs. Researchers are exploring that employing non-destructive testing (NDT) and life prediction model on TBCs to conduct a comprehensive and real-time detection and predict the life, so as to improve the safety of TBCs in service process.

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Černušák, Ivan, and Miroslav Urban. "Effect of electron correlation on SN2 activation barriers. Fourth-order MBPT calculations." Collection of Czechoslovak Chemical Communications 53, no. 10 (1988): 2239–49. http://dx.doi.org/10.1135/cccc19882239.

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The activation barriers for a series of model gas-phase nucleophilic displacement reactions have been calculated at the MBPT(4)/DZ + P + D level. Electron correlation significantly reduces the barrier height, in most cases by about 50%. The role of individual contributions up to the fourth order MBPT is analyzed in detail showing the vital importance of single and triple excitations.

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Ilin, A. S., V. M. Gololobov, E. A. Forsh, P. A. Forsh, and P. K. Kashkarov. "Calculation of the grain potential barrier in the poly− and nanocrystalline semiconductors." Izvestiya Vysshikh Uchebnykh Zavedenii. Materialy Elektronnoi Tekhniki = Materials of Electronics Engineering 20, no. 2 (June 17, 2019): 122–28. http://dx.doi.org/10.17073/1609-3577-2017-2-122-128.

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The distribution of potential and parameters of potential barrier in semiconductor crystallite was calculated numerically. The calculation was carried out in spherical crystallite with evenly distributed donors and surface states. The calculation assumed that the surface charge is screened by both ionized donors and free electrons, the contribution of which cannot be neglected in semiconductors with high concentration of free electrons. The height of potential barrier is shown to nonmonotonically depend on the concentration of donors. The dependence of height of potential barrier on the concentration of donors may be divided into two part. One part of dependence describes the fully depleted crystallite and the second part describes the party depleted crystallite. On the first part the height of potential barrier increases with the donor concentration but on the second part the height of potential barrier decreases. The height of the potential barrier increases with increasing of concentration of surface states. The possibility of existing of potential barriers is estimated in nano− and polycrystalline metal oxide semiconductors used as sensitive layers of gas sensors. It is concluded that if the radius of crystal grains in metal oxide semiconductors does not exceed 10 nm, the explanation of the sensitivity of the sensor to gas by using a commonly barrier model seems unlikely. It is demonstrated that shape of crystallite and the contribution of free electrons to screening of surface charge have to be taken into account to calculation of width of potential barrier.

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Ganiyu, Amuda-Yusuf, Raheem Wasiu Mayowa, Adebiyi Ranti Taibat, Abdulraheem Maimunat Orire, Idris Soliu, and Stephen Eyinaya Eluwa. "Barrier Factors Affecting Adoption of Green Building Technologies in Nigeria." Built Environment Journal 17, no. 2 (July 15, 2020): 37. http://dx.doi.org/10.24191/bej.v17i2.8860.

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Greenhouse gas emission from activities in the built environment is increasing exponentially due to increase in building operations. This study aims at determining factors that affect adoption of Green Building Technologies that normally reduce greenhouse gas emissions. To elicit relevant information, online structured questionnaire forms were administered on practitioners who have been involved in green building development in Nigeria. Mean score ranking was adopted in ranking the barriers to green building technologies, while discriminant analysis was performed to examine how organizations groups (client, consulting, contracting, academia) were distinguished on the barrier factors identified. Findings revealed that, out of the 23 barrier factors considered in this research, lack of institutions to formulate policies and set guidelines (mean score - 4.5) ranked 1st as barrier to adoption of green building technologies in Nigeria. This is closely followed by lack of information about green products (4.0), low level of awareness about sustainability issues (4.0), human resource and client knowledge, lack of knowledge about green building technologies, high cost of green products, while unavailability of sustainable materials and products ranked the lowest (2.7). Only nine factors at 0.05 level of significance entered the discriminant analysis model and emerged as variables with the most significant power in differentiating the organization groupings on the basis of perceived barriers to adoption of green building technologies. The study recommends that there should be strong political will from government, to establish institutions that formulate policies on green building technologies.Keywords: Barriers, Green Building, Green Building Technologies.

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Kuznetsov, Eduard, Volodymyr Nahornyi, and Tibor Krenický. "Gas Flow Simulation in the Working Gap of Impulse Gas-Barrier Face Seal." Management Systems in Production Engineering 28, no. 4 (December 1, 2020): 298–303. http://dx.doi.org/10.2478/mspe-2020-0042.

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AbstractNumerical simulation method of the working process of a centrifugal unit contactless face impulse seal is proposed. A seal functioning physical model was created. Its operation key aspects that are not taken into account in the traditional methods of calculating contactless impulse seals are identified. A numerical simulation of seal working process based on the Reynolds equation solution for the medium vortex-free motion in the gap between moving surfaces is proposed. Hypothesis that simplify the equation’s numerical solution for the face impulse seal is formulated. The numerical solution is obtained using the boundary element method. Based on the obtained numerical solution, the distribution of the working medium pressure field in the seal gap is simulated.

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Machado, Paulo César Miranda, Francisco A. P. Osório, and A. Newton Borges. "Potential Barrier Height Effects on the Intrasubband and Intersubband Quasi-One-Dimensional Plasmons." Modern Physics Letters B 11, no. 09n10 (April 30, 1997): 441–51. http://dx.doi.org/10.1142/s0217984997000542.

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The effects of the potential barrier height on the collective excitations of a electron gas confined in a GaAs-AlxGa1-xAs quantum wire of rectangular cross-section are investigated theoretically. For several potential barrier heights, we calculated the plasmon energy, structure factor and pair-correlation function, within the Random-Phase Approximation regime, considering a three-subband model with only the lowest subband populated by electrons. We verified that the intersubband plasmon is more sensitive to the potential barrier height variation than the intrasubband plasmon. We also observed that the confining potential effect decreases with the increasing of the wire-width.

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Meier, S. M., and D. K. Gupta. "The Evolution of Thermal Barrier Coatings in Gas Turbine Engine Applications." Journal of Engineering for Gas Turbines and Power 116, no. 1 (January 1, 1994): 250–57. http://dx.doi.org/10.1115/1.2906801.

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Thermal barrier coatings (TBCs) have been used for almost three decades to extend the life of combustors and augmentors and, more recently, stationary turbine components. Plasma-sprayed yttria-stabilized zirconia TBC currently is bill-of-material on many commercial jet engine parts. A more durable electron beam-physical vapor deposited (EB-PVD) ceramic coating recently has been developed for more demanding rotating as well as stationary turbine components. This ceramic EB-PVD is bill-of-material on turbine blades and vanes in current high thrust engine models and is being considered for newer developmental engines as well. To take maximum advantage of potential TBC benefits, the thermal effect of the TBC ceramic layer must become an integral element of the hot section component design system. To do this with acceptable reliability requires a suitable analytical life prediction model calibrated to engine experience. The latest efforts in thermal barrier coatings are directed toward correlating such models to measured engine performance.

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Guerra-Garcia, C., and M. Martinez-Sanchez. "Gas-confined barrier discharges: a simplified model for plasma dynamics in flame environments." Journal of Physics D: Applied Physics 46, no. 34 (August 12, 2013): 345204. http://dx.doi.org/10.1088/0022-3727/46/34/345204.

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Eriksson, Robert, Kang Yuan, Sten Johansson, and Ru Lin Peng. "Microstructure-Based Life Prediction of Thermal Barrier Coatings." Key Engineering Materials 592-593 (November 2013): 413–16. http://dx.doi.org/10.4028/www.scientific.net/kem.592-593.413.

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The widespread use of thermal barrier coatings (TBC) in gas turbines stresses the importance of accurate life prediction models for TBCs. During service, the TBC may fail due to thermal fatigue or through the formation of thermally grown oxides (TGOs). The current paper presents a Thermo-Calc/Dictra-based approach to life prediction of isothermally oxidised atmospheric plasma sprayed (APS) TBCs. The β-phase depletion of the coating was predicted and compared to life prediction criteria based on TGO thickness and Al content in the coating. All tried life models underestimated the life of the coating where the β-depletion-based model was the most conservative.

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Tamagnini, Claudio, Cristina Jommi, and Fabio Cattaneo. "A model for coupled electro-hydro-mechanical processes in fine grained soils accounting for gas generation and transport." Anais da Academia Brasileira de Ciências 82, no. 1 (March 2010): 169–93. http://dx.doi.org/10.1590/s0001-37652010000100014.

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A theoretical and numerical model is developed for the quantitative analysis of coupled processes taking place in active waste containment systems, such as electrokinetic barriers or fences, in which alow intensity DC current is circulated across the clay barrier to move polar and non-polar contaminants. A novel feature of the proposed approach is the allowance for the presence of air in the pore space. Under unsaturated conditions, all transport coefficients involved in the electrokinetic process are strongly dependent on the degree of saturation of pore liquid. In order to assess the predictive capability of the proposed theory and to appreciate the impact of gas production at the electrodes, a series of numerical simulations of simple onedimensional electrokinetic tests have been performed. The results of the simulations compare reasonably well with data obtained from laboratory experiments performed on an illitic clayey silt. The numerical results indicate that the impact of gas production at the electrodes can be significant, even in low-intensity and short-duration treatments.

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Amjad, M., Z. Salam, and K. Ishaque. "A Model Parameter Extraction Method for Dielectric Barrier Discharge Ozone Chamber using Differential Evolution." Measurement Science Review 14, no. 2 (April 1, 2014): 78–86. http://dx.doi.org/10.2478/msr-2014-0011.

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Abstract In order to design an efficient resonant power supply for ozone gas generator, it is necessary to accurately determine the parameters of the ozone chamber. In the conventional method, the information from Lissajous plot is used to estimate the values of these parameters. However, the experimental setup for this purpose can only predict the parameters at one operating frequency and there is no guarantee that it results in the highest ozone gas yield. This paper proposes a new approach to determine the parameters using a search and optimization technique known as Differential Evolution (DE). The desired objective function of DE is set at the resonance condition and the chamber parameter values can be searched regardless of experimental constraints. The chamber parameters obtained from the DE technique are validated by experiment.

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Halauddin, Halauddin, Suhendra Suhendra, and Muhammad Isa. "Lattice Gas Automata Applications to Estimate Effective Porosity and Permeability Barrier Model of the Triangle with a Height Variation." Journal of Aceh Physics Society 9, no. 2 (May 1, 2020): 48–54. http://dx.doi.org/10.24815/jacps.v9i2.16056.

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Penelitian ini bertujuan untuk menghitung porositas efektif (фeff) dan permeabilitas (k) menggunakan model segitiga dengan variasi tinggi yaitu 3, 4, 5, 6 dan 7 cm. Perhitungan porositas dan permeabilitas yang efektif dilakukan dengan menggunakan model Lattice Gas Automata (LGA), yang diimplementasikan dengan bahasa pemrograman Delphi 7.0. Untuk model segitiga penghalang dengan tinggi 3, 4, 5, 6 dan 7 cm, nilai porositas efektif dan permeabilitas, masing-masing: фeff (T1) = 0,1690, k (T1) = 0 , 001339 pixel2; фeff (T2) = 0,1841, k (T2) = 0,001904 pixel2; фeff (T3) = 0,1885, k (T3) = 0,001904 pixel2; фeff (T4) = 0,1938, k (T4) = 0001925 pixel2; dan фeff (T5) = 0,2053, k (T5) = 0,002400 pixel2. Dari hasil simulasi, diperoleh tinggi segitiga akan berpengaruh signifikan terhadap nilai porositas efektif dan permeabilitas. Pada segitiga lebih tinggi, menyebabkan tabrakan model aliran fluida LGA mengalami lebih banyak hambatan untuk penghalang, sehingga porositas efektif dan permeabilitas menurun. Sebaliknya, jika segitiga lebih rendah, menyebabkan tabrakan model aliran fluida LGA mengalami lebih sedikit hambatan untuk penghalang, sehingga porositas efektif dan permeabilitas meningkat.This research purposed to calculate the effective porosity (feff) and permeability (k) using the barrier model of the triangle with a high varying are 3, 4, 5, 6 and 7 cm. Effective porosity and permeability calculations performed using the model Lattice Gas Automata (LGA), which is implemented with Delphi 7.0 programming language. For model the barrier triangle with a high of 3, 4, 5, 6 and 7 cm, the value of effective porosity and permeability, respectively: feff(T1)=0,1690, k(T1)=0,001339 pixel2; feff(T2)=0,1841, k(T2)=0,001904 pixel2; feff(T3)=0,1885, k(T3)=0,001904 pixel2; feff(T4)=0,1938, k(T4)= 0001925 pixel2; and feff(T5)=0,2053, k(T5)=0,002400 pixel2. From the simulation results, obtained by the high of the triangle will be a significant effect on the value of effective porosity and permeability. If the triangle highest, causing the collision of fluid flow models LGA experience more obstacles to the barrier, so that the effective porosity and permeability decrease. Conversely, if the triangle lower, causing the collision of fluid flow models LGA experience less obstacles to the barrier, so that the effective porosity and permeability increases.Keywords: Effective porosity, permeability, model triangle, model LGA

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Yamada, Toshishige. "Equivalent circuit model for carbon nanotube Schottky barrier: Influence of neutral polarized gas molecules." Applied Physics Letters 88, no. 8 (February 20, 2006): 083106. http://dx.doi.org/10.1063/1.2177356.

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Shabani, Mohsen, Majid Monajjemi, and Hossein Aghai. "Solvent Effects on the Internal Rotation Barrier around the C–N Bond and 14N NMR Shielding of 2-Amino-3-Mercapto Propionamide: Continuous Set of Gauge Transformation Calculations using a Polarisable Continuum Model." Journal of Chemical Research 2003, no. 5 (May 2003): 249–51. http://dx.doi.org/10.3184/030823403103173840.

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Solvent effects on rotational barriers of 2-amino-3-mercapto-propionamide, an amide derived from cysteine, have been investigated at HF and MP2 levels of theory using a polarisable continuum model (PCM) of solvent. The predicted barrier in the gas phase increases by increasing the polarity of solvents. It was shown that the observed solvent-induced shielding variation is more strongly related to the intensity of the solvent reaction field rather than to the change of molecular geometry induced by the solvent.

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Rajapakse, Manthila, George Anderson, Congyan Zhang, Rajib Musa, Jackson Walter, Ming Yu, Gamini Sumanasekera, and Jacek B. Jasinski. "Gas adsorption and light interaction mechanism in phosphorene-based field-effect transistors." Physical Chemistry Chemical Physics 22, no. 10 (2020): 5949–58. http://dx.doi.org/10.1039/c9cp06547d.

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Phosphorene-based field effect transistors are fabricated and are shown to be highly sensitive gas and photodetectors. The sensing mechanism is explained using a Schottky barrier model at the phosphorene/metal contact interface.

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Zhang, Shen, Zhenli Chen, Binqian Zhang, and Yingchun Chen. "Numerical Investigation on the Effects of Dielectric Barrier on a Nanosecond Pulsed Surface Dielectric Barrier Discharge." Molecules 24, no. 21 (October 31, 2019): 3933. http://dx.doi.org/10.3390/molecules24213933.

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In order to understand the impacts of dielectric barrier on the discharge characteristics of a nanosecond pulsed surface dielectric barrier discharge (NS-DBD), the effects of dielectric constant and dielectric barrier thickness are numerically investigated by using a three-equation drift–diffusion model with a 4-species 4-reaction air chemistry. When the dielectric constant increases, while the dielectric barrier thickness is fixed, the streamer propagation speed (V), the maximum streamer length (L), the discharge energy ( Q D _ e i ), and the gas heating ( Q G H ) of a pulse increase, but the plasma sheath thickness (h), the fast gas heating efficiency η , and the charge densities on the wall surface decrease. When the dielectric barrier thickness increases, while the dielectric constant is fixed, V, L, Q D _ e i , and Q G H of a pulse decrease, but h, η , and the charge densities on the wall surface increase. It can be concluded that the increase of the dielectric constant or the decrease of the dielectric barrier thickness results in the increase of the capacitance of the dielectric barrier, which enhances the discharge intensity. Increasing the dielectric constant and thinning the dielectric barrier layer improve the performance of the NS-DBD actuators.

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Simončič, M., D. Semenov, S. Krasnokutski, Th Henning, and C. Jäger. "Sensitivity of gas-grain chemical models to surface reaction barriers." Astronomy & Astrophysics 637 (May 2020): A72. http://dx.doi.org/10.1051/0004-6361/202037648.

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Context. The feasibility of contemporary gas-grain astrochemical models depends on the availability of accurate kinetics data, in particular, for surface processes. Aims. We study the sensitivity of gas-grain chemical models to the energy barrier Ea of the important surface reaction between some of the most abundant species: C and H2 (surface C + surface H2 → surface CH2). Methods. We used the gas-grain code ALCHEMIC to model the time-dependent chemical evolution over a 2D grid of densities (nH ∈ 103, 1012 cm−3) and temperatures (T ∈ 10, 300 K), assuming UV-dark (AV = 20 mag) and partly UV-irradiated (AV = 3 mag) conditions that are typical of the dense interstellar medium. We considered two values for the energy barrier of the surface reaction, Ea = 2500 K (as originally implemented in the networks) and Ea = 0 K (as measured in the laboratory and computed by quantum chemistry simulations). Results. We find that if the C + H2 → CH2 surface reaction is barrierless, a more rapid conversion of the surface carbon atoms into methane ice occurs. Overproduction of the CHn hydrocarbon ices affects the surface formation of more complex hydrocarbons, cyanides and nitriles, and CS-bearing species at low temperatures ≲10−15 K. The surface hydrogenation of CO and hence the synthesis of complex (organic) molecules become affected as well. As a result, important species whose abundances may change by more than a factor of two at 1 Myr include atomic carbon, small mono-carbonic (C1) and di-carbonic (C2) hydrocarbons, CO2, CN, HCN, HNC, HNCO, CS, H2CO, H2CS, CH2CO, and CH3OH (in either gas and/or ice). The abundances of key species, CO, H2O, and N2 as well as O, HCO+, N2H+, NH3, NO, and most of the S-bearing molecules, remain almost unaffected. Conclusions. Further accurate laboratory measurements and quantum chemical calculations of the surface reaction barriers will be crucial to improve the accuracy of astrochemical models.

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Moraci, Nicola, Domenico Ielo, Stefania Bilardi, and Paolo S. Calabrò. "Modelling long-term hydraulic conductivity behaviour of zero valent iron column tests for permeable reactive barrier design." Canadian Geotechnical Journal 53, no. 6 (June 2016): 946–61. http://dx.doi.org/10.1139/cgj-2015-0453.

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In this paper, a numerical model to simulate the hydraulic conductivity reduction observed during long-term laboratory column tests is proposed. The column tests are carried out to study dissolved heavy metals removal by using granular zero valent iron (ZVI). The proposed model is also used to analyse the main causes of hydraulic conductivity reduction observed during laboratory column tests. Expansive iron corrosion, precipitation of reaction products, and gas formation are the processes considered in the proposed model. Numerical simulation results show that to reproduce hydraulic behaviour of the experimental systems, the change of pores geometry due to expansive iron corrosion and precipitation of reaction products, which determines a possible stoppage of gas bubbles, should be considered. Furthermore, model results show that only a small percentage of the iron available is corroded during the tests (from 0.4% to 1.9%). According to the model, the average diameter of gas bubbles that better fit the experimental results varies between 0.16 and 0.19 mm. While assuming gas absence (or its possible escape), higher values of iron corrosion rate should be considered to fit the experimental results.

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Bussière, Bruno, Michel Aubertin, and Robert P. Chapuis. "The behavior of inclined covers used as oxygen barriers." Canadian Geotechnical Journal 40, no. 3 (June 1, 2003): 512–35. http://dx.doi.org/10.1139/t03-001.

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Covers with capillary barrier effects (CCBE) have been recently proposed as a viable option for gas migration barriers. However, the effect of geometry on CCBE performance has not been clearly demonstrated. In this paper, the results of a laboratory study performed with an original apparatus called the inclined box are presented. The results obtained show that the hydraulic behavior of layered covers is influenced by the inclination of the slope. Generally, the upper part of the slope contains less water than the lower part. This means that the upper part is less efficient than the lower part for limiting gas migration. The authors have also studied an existing site where a CCBE was built on a sloping surface. After validation of the numerical model with in situ measured data, the model was used to perform a parametric study to quantify the influence of the main CCBE parameters on its performance. The results obtained confirm those measured in the lab and clearly show how geometry influences the performance of the CCBE. Based on these results, a simple relationship is proposed for a preliminary estimation of sloping covers performance to limit oxygen migration by diffusion.Key words: cover with capillary barrier effects, acid mine drainage, slope effects, laboratory investigation, in situ measurements, design criteria.

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Zheng, Wei Qiang, Wen Jun Wei, and Ping Yi Liu. "The Study of Sand-blocking Characteristic and Flow Field Simulation Analysis of the Ring-shaped Sand-barrier." E3S Web of Conferences 38 (2018): 01044. http://dx.doi.org/10.1051/e3sconf/20183801044.

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Aiming at the complexity of wind direction and irregular sand flow in a desert area, a combinatorial ring-shaped sand barrier is used. Stokes law of inertia force and centrifugal force and gravity sedimentation are used. With CFD fluid software Fluent, laminar flow model Equation and κ-ε turbulence model, the wind speed of the sand in the sand-gas-solid two-phase flow passing through the circular sand barrier is studied at different distances and different altitudes after the sand barrier, the wind speeds before and after the sand barrier are compared and analyzed . The mean minimum wind speed behind the single sand barrier was reduced by 32.5% -49.4% compared with that before the sand barrier. The wind speed at different height of the composite sand barrier was reduced by 30% -58.3% compared with the inlet wind speed, which solved the problem of irregular wind and sand control in the desert wind direction.

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Lopes, Juliana F., Juliana C. M. Silva, Maurício T. M. Cruz, José Walkimar de M. Carneiro, and Wagner B. De Almeida. "DFT study of ethanol dehydration catalysed by hematite." RSC Advances 6, no. 46 (2016): 40408–17. http://dx.doi.org/10.1039/c6ra08509a.

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Arai, Masayuki, and Daigo Hara. "Damage Model for Degradation Induced by Volcanic Ash Deposition on Thermal Barrier Coatings." Key Engineering Materials 665 (September 2015): 237–40. http://dx.doi.org/10.4028/www.scientific.net/kem.665.237.

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The importance of a land-based gas turbine has been increased in order to maintain energy security in Japan. Since our country has been always exposed to a natural disaster, it is necessary to consider about influence of air intake of volcanic ash spouted from a volcanic explosion on high-temperature components in gas turbine as well as vibration by an earthquake event. In this study, a high-temperature exposure tests were conducted for 8YZ/CoNiCrAlY/IN-738LC sample on which volcanic ash was deposited. Here, we selected the natural ash picked up from Shin-moe mountain where had been exploded in 2011. As a result, it was found that the top coating was peeled completely off at the exposure condition 1273 K for 100 hours, which means that volcanic ash deposition brings about some acceleration for the delamination life of TBC. The microstructure observation after the exposure tests revealed that Si and Ca contents involved in the volcanic ash was detected inside open-pores. Thus, it was identified that those ashes infiltrated into open pores along splat boundaries under a high-temperature exposure environment. The damage model for explaining degradation induced by volcanic ash deposition was developed based upon micromechanics. The formulae for constitutive equation of TBC was done by considering about influence of both crystal distortion by tetragonal to monoclinic phase transformation and thermal shrinking by temperature drop in the heat exposure treatment. Residual stress and interfacial energy were evaluated using the proposed constitutive equation in order to clarify degradation mechanisms for ash attack to TBC.

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Feng, Shi-Jin, Zhang-Wen Zhu, Zhang-Long Chen, and Hong-Xin Chen. "Analytical Model for Multicomponent Landfill Gas Migration through Four-Layer Landfill Biocover with Capillary Barrier." International Journal of Geomechanics 20, no. 3 (March 2020): 04020001. http://dx.doi.org/10.1061/(asce)gm.1943-5622.0001598.

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Tarau, Calin, Volkan Ötügen, Valery Sheverev, George Vradis, and Ganesh Raman. "The Effect of Thermal Barriers on Sound Wave Propagation." International Journal of Aeroacoustics 6, no. 3 (September 2007): 287–308. http://dx.doi.org/10.1260/147547207782419543.

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Sound propagation through regions of non-uniform temperature distribution in a gas is studied numerically. The main objective of this study is to determine the impact of temperature gradients on the sound wave parameters and to evaluate the effectiveness of using regions of hot gas as sound barrier. Such regions of hot gas (low acoustic impedance) can be generated by remotely depositing energy into a selected volume of gas, for example, by means of electrical discharge. Sound attenuation through the hot gas region is studied systematically for a range of sound wave and thermal field parameters by solving the two-dimensional unsteady compressible Euler's equations along with the ideal gas state equation using a finite volume scheme. Particular attention is given to the practical case when sound wavelength is comparable to the thickness of the thermal barrier. The present two-dimensional model indicates that considerable sound attenuation can be achieved at large incidence angles and a critical angle for total internal reflection is possible.

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BORGES, ANTÔNIO NEWTON, FRANCISCO A. P. OSÓRIO, PAULO CÉSAR MIRANDA MACHADO, and OSCAR HIPÓLITO. "SHORT-RANGE CORRELATION EFFECTS IN A POLARON GAS IN GaAs–AlGaAs QUANTUM WELL WIRES." Modern Physics Letters B 13, no. 22n23 (October 10, 1999): 819–27. http://dx.doi.org/10.1142/s0217984999001019.

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We investigate the short-range correlation effects of plasmon–phonon collective excitations in a quantum well wire by using the self-consistent field approximation theory proposed by Singwi, Tosi, Land and Sjolander [Phys. Rev.176, 589 (1968)]. In our calculation model, we consider a three-subband model with only one populated, for a rectangular cross-section quantum well wire with infinite height for the potential barrier. We have verified that by decreasing the wire width (and/or decreasing the electronic density), the local field correction effects are increased. We compare the present results with those obtained within the Random Phase Approximation throughout the paper and found that the differences between the two calculation methods are more significant for the intrasubband plasmon.

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Hoppe, C. M., L. Hoffmann, P. Konopka, J. U. Grooß, F. Ploeger, G. Günther, P. Jöckel, and R. Müller. "The implementation of the CLaMS Lagrangian transport core into the chemistry climate model EMAC 2.40.1: application on age of air and transport of long-lived trace species." Geoscientific Model Development 7, no. 6 (November 11, 2014): 2639–51. http://dx.doi.org/10.5194/gmd-7-2639-2014.

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Abstract. Lagrangian transport schemes have proven to be useful tools for modelling stratospheric trace gas transport since they are less diffusive than classical Eulerian schemes and therefore especially well suited for maintaining steep tracer gradients. Here, we present the implementation of the full-Lagrangian transport core of the Chemical Lagrangian Model of the Stratosphere (CLaMS) into the ECHAM/MESSy Atmospheric Chemistry model (EMAC). We performed a 10-year time-slice simulation to evaluate the coupled model system EMAC/CLaMS. Simulated zonal mean age of air distributions are compared to age of air derived from airborne measurements, showing a good overall representation of the stratospheric circulation. Results from the new Lagrangian transport scheme are compared to tracer distributions calculated with the standard flux-form semi-Lagrangian (FFSL) transport scheme in EMAC. The differences in the resulting tracer distributions are most pronounced in the regions of strong transport barriers. The polar vortices are presented as an example for isolated air masses which are surrounded by a strong transport barrier and simulated trace gas distributions are compared to satellite measurements. The analysis of CFC-11, N2O, CH4, and age of air in the polar vortex regions shows that the CLaMS Lagrangian transport scheme produces a stronger, more realistic transport barrier at the edge of the polar vortex than the FFSL transport scheme of EMAC. Differences in simulated age of air range up to 1 year in the Arctic polar vortex in late winter/early spring. The new coupled model system EMAC/CLaMS thus constitutes a suitable tool for future model studies of stratospheric tracer transport.

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Amuedo, K. C., B. R. Williams, J. D. Flood, and A. L. Johns. "STOVL Hot Gas Ingestion Control Technology." Journal of Engineering for Gas Turbines and Power 113, no. 1 (January 1, 1991): 68–74. http://dx.doi.org/10.1115/1.2906532.

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A comprehensive wind tunnel test program was conducted to evaluate control of Hot Gas Ingestion (HGI) on a 9.2 percent scale model of the McDonnell Aircraft Company model 279-3C advanced Short Takeoff and Vertical Landing (STOVL) configuration. The test was conducted in the NASA-Lewis Research Center 9 ft by 15 ft Low Speed Wind Tunnel during the summer of 1987. Initial tests defined baseline HGI levels as determined by engine face temperature rise and temperature distortion. Subsequent testing was conducted to evaluate HGI control parametrically using Lift Improvement Devices (LIDs), forward nozzle splay angle, a combination of LIDs and forward nozzle splay angle, and main inlet blocking. The results from this test program demonstrate that HGI can be effectively controlled and that HGI is not a barrier to STOVL aircraft development.

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Tenango-Pirin, Oscar, Elva Reynoso-Jardón, Juan Carlos García, Yahir Mariaca, Yuri Sara Hernández, Raúl Ñeco, and Omar Dávalos. "Effect of Thermal Barrier Coating on the Thermal Stress of Gas Microturbine Blades and Nozzles." Strojniški vestnik – Journal of Mechanical Engineering 66, no. 10 (October 15, 2020): 581–90. http://dx.doi.org/10.5545/sv-jme.2020.6883.

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Thermal barrier coatings play a key role in the operational life of microturbines because they reduce thermal stress in the turbine components. In this work, numerical computations were carried out to assess new materials developed to be used as a thermal barrier coating for gas turbine blades. The performance of the microturbine components protection is also evaluated. The new materials were 8YSZ, Mg2SiO4, Y3Ce7Ta2O23.5, and Yb3Ce7Ta2O23.5. For testing the materials, a 3D gas microturbine model is developed, in which the fluid-structure interaction is solved using CFD and FEM. Temperature fields and stress magnitudes are calculated on the nozzle and blade, and then these are compared with a case in which no thermal barrier is used. Based on these results, the non-uniform temperature distributions are used to compute the stress levels in nozzles and blades. Higher temperature gradients are observed on the nozzle; the maximum temperature magnitudes are observed in the blades. However, it is found that Mg2SiO4 and Y3Ce7Ta2O23.5 provided better thermal insulation for the turbine components compared with the other evaluated materials. Mg2SiO4 and Y3Ce7Ta2O23.5 presented the best performance regarding stress and thermal insulation for the microturbine components. Keywords: thermal barrier coating, gas microturbine, turbine blade, thermal stress

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Xue, Yi, Faning Dang, Fang Shi, Rongjian Li, and Zhengzheng Cao. "Evaluation of Gas Migration and Rock Damage Characteristics for Underground Nuclear Waste Storage Based on a Coupled Model." Science and Technology of Nuclear Installations 2018 (June 27, 2018): 1–10. http://dx.doi.org/10.1155/2018/2973279.

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In the deep geological repository of nuclear waste, the corrosion of waste generates gas, which increases the storage pressure, changes the properties of the rock strata, and affects the stability of nuclear waste repository. Therefore, it is of great importance to understand the gas migration in the engineering barrier and the potential impact on its integrity for the safety assessment of nuclear waste repository. A hydro-mechanical-damage model for analyzing gas migration in sedimentary rocks is established in this paper. On the basis of which, a set of coupled formulas for the coupling of gas migration in rock mass is established. The model considers the characteristics of gas migration in sedimentary rock, especially the microcracks caused by the degradation of elastic modulus and damage, and the coupling between the rock deformation and failure of fractures. The numerical simulation of gas injection test is beneficial to understand the mechanism of gas migration process in sedimentary rock.

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de Araujo Oliveira, Alan Leone, Luiz Guilherme Machado de Macedo, Yuri Alves de Oliveira Só, João Batista Lopes Martins, Fernando Pirani, and Ricardo Gargano. "Nature and role of the weak intermolecular bond in enantiomeric conformations of H2O2–noble gas adducts: a chiral prototypical model." New Journal of Chemistry 45, no. 18 (2021): 8240–47. http://dx.doi.org/10.1039/d0nj06135b.

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The role and nature of the weak intermolecular bond in the H₂O₂–noble gas enantiomeric conformations are presented. Charge transfer associated with the formation of a weak intermolecular hydrogen bond tends to stabilize the cis-barrier conformation.

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Li, Zhi Jun, Ji Qiang Li, and Wen De Yan. "Numerical Simulation Study on the Key Influencing Factors of Water-Invasion Performance for the Gas Wells with Bottom-Water." Advanced Materials Research 884-885 (January 2014): 104–7. http://dx.doi.org/10.4028/www.scientific.net/amr.884-885.104.

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For the water-sweeping gas reservoir, especially when the water-body is active, water invasion can play positive roles in maintaining formation pressure and keeping the gas well production. But when the water-cone break through and towards the well bottom, suffers from the influencing of gas-water two phase flows, permeability of gas phase decrease sharply and will have a serious impact on the production performance of the gas well. Moreover, the time when the water-cone breakthrough will directly affect the final recovery of the gas wells, therefore, the numerical simulation method is used to conduct the research on the key influencing factors of water-invasion performance for the gas wells with bottom-water, which is the basis of the mechanical model for the typical gas wells with bottom-water. It indicate that as followings: (1) the key influencing factors of water-invasion performance for the gas wells with bottom-water are those, such as the open degree of the gas beds, well gas production and the amount of Kv/Kh value; and (2) the barrier will be in charge of great significance on the water-controlling for the bottom water gas wells, and its radius is the key factor to affect water-invasion performance for the bottom water gas wells where the barriers exist nearby.

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Ohashi, Hidenori, and Takeo Yamaguchi. "Design of Gas Barrier Membrane / Vapor Permeation Membrane - Approach from Diffusivity Prediction Model in Polymer Matrices -." MEMBRANE 36, no. 2 (2011): 71–78. http://dx.doi.org/10.5360/membrane.36.71.

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Aydin, Orhan, Misao Iwata, Noroi Arai, and Wen-Jei Yang. "Theoretical Analysis of Heat Transfer Through an Idealized Gas Turbine Blade Model with Thermal Barrier Coating." International Journal of Rotating Machinery 8, no. 2 (2002): 81–86. http://dx.doi.org/10.1155/s1023621x02000088.

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42

Aydin, Orhan, Misao Iwata, Noroi Arai, and Wen-Jei Yang. "Theoretical Analysis of Heat Transfer Through an Idealized Gas Turbine Blade Model with Thermal Barrier Coating." International Journal of Rotating Machinery 8, no. 2 (March 1, 2002): 81–86. http://dx.doi.org/10.1080/10236210211863.

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Wang, Bojie, and Peter R. Ogilby. "Activation barriers for oxygen diffusion in polystyrene and polycarbonate glasses: effects of codissolved argon, helium, and nitrogen." Canadian Journal of Chemistry 73, no. 11 (November 1, 1995): 1831–40. http://dx.doi.org/10.1139/v95-226.

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A recently developed spectroscopic technique was used to determine oxygen diffusion coefficients as a function of temperature for polystyrene and polycarbonate films. Data were recorded at total pressures <300 Torr over the temperature range 5–45 °C under conditions in which argon, helium, and nitrogen, respectively, were copenetrants. In all cases, the presence of the additional gas caused an increase in the oxygen diffusion coefficient. Arrhenius plots of the data yield (a) a diffusion activation barrier, Eact, and (b) a diffusion coefficient, D0, that represents the condition of "barrier-free" gas transport for the temperature domain over which the Arrhenius plot is linear. For all cases examined in both polystyrene and polycarbonate, D0 increased with an increase in the partial pressure of added gas. In polystyrene, the presence of an additional gas did not change Eact. In polycarbonate, Eact obtained in the presence of helium and argon likewise did not differ from that obtained in the absence of the copenetrant. When nitrogen was the added gas, however, a larger value of Eact was obtained. This latter observation is interpreted to reflect the plasticization of polycarbonate by nitrogen. Eact and D0 data are discussed within the context of a model that distinguishes between dynamic and static elements of free volume in the polymer matrix. Keywords: oxygen diffusion, polystyrene, polycarbonate, activation barrier.

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44

Zhang, L. M., and Y. Q. Ke. "Combinations of soil materials for granular capillary barriers for minimizing rainfall infiltration and gas emission." Canadian Geotechnical Journal 54, no. 11 (November 2017): 1580–91. http://dx.doi.org/10.1139/cgj-2016-0334.

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This paper presents a coupled air–water flow analysis to evaluate the performance of a three-layer capillary barrier for controlling water infiltration into and gas emission from a waste containment system in a high precipitation environment, and to optimize combinations of local soil layers for barrier construction. A multi-phase flow model is proposed considering the movements of the gas and water phases simultaneously. The governing partial differential equations are solved in COMSOL Multiphysics software. Several combinations of lean clay with sand (CL), clayey sand with gravel (SC), silty sand with gravel (SM), sandy silt (ML), and well-graded gravel with silt (GW–GM) are examined. The rates of percolation water and gas emission are used as indicators to compare the performance of different combinations. A fine-grained surface soil layer reduces both water infiltration and gas emission due to its low desaturation rate and high water-retention capacity. The coarse middle layer plays a critical role, promoting capillary effects and hindering water infiltration during rainfall as well as draining any infiltrated water or percolated gas.

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Raut, Rakesh, Balkrishna Eknath Narkhede, Bhaskar B. Gardas, and Huynh Trung Luong. "An ISM approach for the barrier analysis in implementing sustainable practices." Benchmarking: An International Journal 25, no. 4 (May 8, 2018): 1245–71. http://dx.doi.org/10.1108/bij-05-2016-0073.

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Purpose The purpose of this paper is to identify and model critical barriers to sustainable practices implementation in Indian oil and gas sectors by the interpretive structural modeling (ISM) approach. Design/methodology/approach In this paper, through exhaustive literature survey and experts opinions, 14 critical barriers were identified, and the ISM tool, which is a multi-criteria decision-making approach, was used to establish interrelationship among the identified barriers and to determine the key barriers having high driving power. Findings After analyzing, it was found that six barriers, namely, market competition and uncertainty (B7), shortage of resources (B8), governmental rules and regulations (B1), knowledge and training (B2), financial implications (B3), and management commitment and leadership (B5) were found to have high influencing power. These barriers need the maximum attention and organizations need to overcome these hindrances for the effective implementation of sustainable practices. From the driving and dependence power diagram, two barriers, namely, management commitment and leadership (B5) and knowledge and training (B2) were found to have the highest driving power and two barriers, namely, lack of green initiatives (B9) and lack of corporate social responsibility (B14) were found to have highest dependence power. Research limitations/implications The presently developed model is based on the experts’ opinions, which may be biased, influencing the final output of the structural model. The research implications of the developed model are to help managers of the organization in understanding significance of the barriers, to prioritize or eliminate the same for the practical implementation of sustainability. Originality/value This is for the first time an attempt has been made to apply the ISM methodology to explore the interdependencies among the critical barriers for Indian oil and gas industries. This paper will guide the managers at various levels of an organization for effective implementation of the sustainable practices.

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Sharbati, Samaneh, Iman Gharibshahian, Thomas Ebel, Ali A. Orouji, and Wulf-Toke Franke. "Analytical Model for Two-Dimensional Electron Gas Charge Density in Recessed-Gate GaN High-Electron-Mobility Transistors." Journal of Electronic Materials 50, no. 7 (April 20, 2021): 3923–29. http://dx.doi.org/10.1007/s11664-021-08842-7.

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AbstractA physics-based analytical model for GaN high-electron-mobility transistors (HEMTs) with non-recessed- and recessed-gate structure is presented. Based on this model, the two-dimensional electron gas density (2DEG) and thereby the on-state resistance and breakdown voltage can be controlled by varying the barrier layer thickness and Al mole fraction in non-recessed depletion-mode GaN HEMTs. The analytical model indicates that the 2DEG charge density in the channel increases from 2.4 × 1012 cm−2 to 1.8 × 1013 cm−2 when increasing the Al mole fraction from x = 0.1 to 0.4 for an experimental non-recessed-gate GaN HEMT. In the recessed-gate GaN HEMT, in addition to these parameters, the recess height can also control the 2DEG to achieve high-performance power electronic devices. The model also calculates the critical recess height for which a normally-ON GaN switch becomes normally-OFF. This model shows good agreement with reported experimental results and promises to become a useful tool for advanced design of GaN HEMTS.

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Buffin, A. J. "WAARRE SANDSTONE DEVELOPMENT WITHIN THE PORT CAMPBELL EMBAYMENT." APPEA Journal 29, no. 1 (1989): 299. http://dx.doi.org/10.1071/aj88026.

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The Late Cretaceous Waarre Formation is recognised as the principal reservoir unit throughout the Port Campbell Embayment, where a number of small gas fields were discovered and developed in the late 1970s and the early and mid- 1980s.The Waarre Formation can be subdivided into four units, identified as Unit A, a basal fining upward sequence; Unit B, a medial siltstone with interbedded calcareous sandstones; Unit C, a coarse- grained porous sandstone (the primary gas reservoir); Unit D, a ferruginous siltstone/sandstone sequence.The Upper Waarre, Units C and D, represents a variety of environments unique to a beach barrier- system, including back- water lagoons, swamps, tidal channels, tidal deltas, and beach sands. The development of an Upper Waarre sandstone- beach- barrier model, the identification of various facies, and the construction of regional palaeogeography leads to an understanding of sedimentary deposition during Waarre times.Recent drilling has shown the Upper Waarre to extend laterally in an easterly direction and, as proposed by the depositional model, development of the prospective Waarre Unit C gas sands in a restricted linear east- west zone.By combining the complex structural history of the Port Campbell Embayment and the resultant structures developed with the depositional model of the Waarre Formation, major migration pathways, and thick (>50 m) overlying seals, exploration throughout the embayment can be directed towards prospective gas reservoirs within the Waarre, Unit C, sandstone bodies.

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Pazdniakou, Aliaksei, and Magdalena Dymitrowska. "Migration of Gas in Water Saturated Clays by Coupled Hydraulic-Mechanical Model." Geofluids 2018 (2018): 1–25. http://dx.doi.org/10.1155/2018/6873298.

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Understanding the gas migration in highly water saturated sedimentary rock formations is of great importance for safety of radioactive waste repositories which may use these host rocks as barrier. Recent experiments on drainage in argillite samples have demonstrated that they cannot be represented in terms of standard two-phase flow Darcy model. It has been suggested that gas flows along highly localized dilatant pathways. Due to very small pore size and the opacity of the material, it is not possible to observe this two-phase flow directly. In order to better understand the gas transport, a numerical coupled hydraulic-mechanical model at the pore scale is proposed. The model is formulated in terms of Smoothed Particle Hydrodynamics (SPH) and is applied to simulate drainage within a sample reconstructed from the Focused Ion Beam (FIB) images of Callovo-Oxfordian claystone. A damage model is incorporated to take into account the degradation of elastic solid properties due to local conditions, which may lead to formation of new pathways and thus to modifications of fluid transport. The influence of the damage model as well as the possible importance of rigid inclusions is demonstrated and discussed.

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Wu, H., M. Tan, W. Zhu, and Z. S. Ma. "The Interaction between Erosion Particle and Gas Stream in High Temperature Gas Burner Rig for Thermal Barrier Coatings." High Temperature Materials and Processes 38, no. 2019 (February 25, 2019): 125–34. http://dx.doi.org/10.1515/htmp-2017-0172.

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AbstractThermal barrier coatings (TBCs) as a kind of temperature-resistance materials have been widely applied in super high temperature components in aircraft engines. However, TBCs are subjected to harsh service environment such as high temperature oxidation and erosion, which lead to the coating failure. It is important to investigate the effect of fire temperature, angle and velocity of particle on erosion to understand the failure mechanism. In this paper, the temperature and velocity distributions of erosion particles in high temperature gas burner rig are investigated by using the fluid–solid coupling method with the discrete random walk model. The results show that a non-uniform distribution of temperature appears in different positions of the central axis, and the temperature of particle is affected obviously by the gas stream and particle size. The trajectory of particles and velocity diagrams under different particle size are determined by coupling the continuous phase with the erosion particles.

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Bolotnova, R. Kh, and E. F. Gainullina. "Investigation of axisymmetric wave flows under interaction of a spherical impact pulse with a barrier of aqueous foam." Proceedings of the Mavlyutov Institute of Mechanics 12, no. 2 (2017): 238–43. http://dx.doi.org/10.21662/uim2017.2.036.

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The problem of spherical explosion in the gas region with a protective foam layer is solved in a two-dimensional axisymmetric formulation using a two-phase model of a gas-liquid mixture that includes the laws of conservation of mass, momentum and energy of the mixture and the equation for the dynamics of the volume content of phases. The numerical implementation of the model was carried out by modifying the standard solver of the compressibleMultiphaseInterFoam of the open package OpenFOAM. The results of computer modeling are visualized using the ParaView graphical platform.

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Journal articles on the topic 'Gas barrier model'

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