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Sample records for gri tight gas

  1. Hydraulic fracture model and diagnostics verification at GRI/DOE multi-site projects and tight gas sand program support. Final report, July 28, 1993--February 28, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, J.E.

    1997-12-31

    The Mesaverde Group of the Piceance Basin in western Colorado has been a pilot study area for government-sponsored tight gas sand research for over twenty years. Early production experiments included nuclear stimulations and massive hydraulic fracture treatments. This work culminated in the US Department of Energy (DOE)`s Multiwell Experiment (MWX), a field laboratory designed to study the reservoir and production characteristics of low permeability sands. A key feature of MWX was an infrastructure which included several closely spaced wells that allowed detailed characterization of the reservoir through log and core analysis, and well testing. Interference and tracer tests, as well as the use of fracture diagnostics gave further information on stimulation and production characteristics. Thus, the Multiwell Experiment provided a unique opportunity for identifying the factors affecting production from tight gas sand reservoirs. The purpose of this operation was to support the gathering of field data that may be used to resolve the number of unknowns associated with measuring and modeling the dimensions of hydraulic fractures. Using the close-well infrastructure at the Multiwell Site near Rifle, Colorado, this operation focused primarily on the field design and execution of experiments. The data derived from the experiments were gathered and analyzed by DOE team contractors.

  2. Carbon and greenhouse gas balance of the FR-GRI crop site from 2005 to 2014

    Science.gov (United States)

    Loubet, Benjamin; Chammakhi, Manel; Mascher, Nicolas; Durand, Brigitte; Gueudet, Jean-Christophe; Decuq, Céline; Lecuyer, Vanessa; Laville, Patricia; Buysse, Pauline; Cellier, Pierre

    2017-04-01

    The carbon and greenhouse gas balance of the ICOS FR-GRI site from 2005 to 2014 is presented. The site is a wheat-barley-maize rotation with the introduction of oil-seed rape in 2012. The site receives large amounts of organic fertilization, but is shown to be a strong source of carbon to the atmosphere, especially due to the increase in the exportations of residues during the period. The exportations have increased from around 4 to around 8 t C ha-1 year-1 over the period on average except for maize for which it remained constant. In the meantime the carbon importations have increased from around 1 to around 2 t C ha-1 year-1 during the same period. Overall the field was losing around 2 t C ha-1 year-1 over the whole period but largely driven by last years (2012-2014). This would represent 17% loss of the soil carbon content in the 0-60 cm in the 2005-2014 period. The discussion focuses on explanations of these losses and possible drawbacks in the methodology. The effect of the winter intermediate crops on the carbon balance is also discussed.

  3. Well testing of tight gas reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Jahanbani, A.; Aguilera, R. [Calgary Univ., AB (Canada)

    2008-07-01

    This paper discussed methods of evaluating tight gas sand reservoirs. Conventional well testing is not used in tight gas reservoirs due to their low permeability. Tight gas well testing techniques include pressure-dependent permeability testing; the estimation of pseudo--time at the average pressure of the region of influence; and supercharge effect testing. Pre-frac test analysis techniques were also discussed. Pressure-transient test designs were reviewed along with instantaneous source response methods for calculating influence functions. Impulse-fracture tests were discussed, as well as perforation inflow diagnostic testing. Perforation inflow tests provided reasonable estimates of reservoir parameters. Methods of determining pressure-dependent permeability data were discussed. After closure analysis (ACA) was used to analyze formation permeability. It was concluded that ACA can be coupled with pre-closure analysis to optimize fracture stimulation plans. The 22 refs., 17 figs.

  4. Analysis of the use of Essential GRI (G3 Indicators in the Reports of Companies in the Sectors of Oil, Gas, And Biofuels; And Public Utilities In Brazil

    Directory of Open Access Journals (Sweden)

    Silvana karina de Melo Travassos

    2014-08-01

    Full Text Available The objective of this article is to verify the degree of full adhesion and Effective Disclosure for business sectors in Brazil for oil, gas, and biofuel; and utilities, through sustainability reports prepared by the G3 version of the GRI Guidelines. The report of the Global Reporting Initiative (GRI is constituted by a set of principles and indicators of economic, social, and environmental concerns with emphasis on transparency, quality, and reliability. This paper develops a multi-case methodology using a qualitative approach and has an exploratory purpose concerning the compliance of the reports of Brazilian companies to the parameters of the GRI. We opted for the use of a non-probabilistic sample of Brazilian companies in two Brazilian sectors, namely oil, gas, and biofuel; and utilities. Then we obtained sustainability reports which provided the summary index of the indicators from the institutional page of each company on the internet. From these observations we found that some Brazilian companies are adhering to the use of indicators of Sustainability Reports proposed by GRI. Furthermore, we found that the fact that companies are part of the same economic sector implies they are at a similar level of adherence to the indicators. Also, we observed that despite the effort postulated by GRI to develop a quality model more consistent and complete for sustainability reports, its applicability in the Brazilian oil, gas, and biofuel; and utility industries still needs to be improved.

  5. Naturally fractured tight gas reservoir detection optimization

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-06-01

    Building upon the partitioning of the Greater Green River Basin (GGRB) that was conducted last quarter, the goal of the work this quarter has been to conclude evaluation of the Stratos well and the prototypical Green River Deep partition, and perform the fill resource evaluation of the Upper Cretaceous tight gas play, with the goal of defining target areas of enhanced natural fracturing. The work plan for the quarter of November 1-December 31, 1998 comprised four tasks: (1) Evaluation of the Green River Deep partition and the Stratos well and examination of potential opportunity for expanding the use of E and P technology to low permeability, naturally fractured gas reservoirs, (2) Gas field studies, and (3) Resource analysis of the balance of the partitions.

  6. Naturally fractured tight gas reservoir detection optimization

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-11-30

    The work plan for October 1, 1997 to September 30, 1998 consisted of investigation of a number of topical areas. These topical areas were reported in four quarterly status reports, which were submitted to DOE earlier. These topical areas are reviewed in this volume. The topical areas covered during the year were: (1) Development of preliminary tests of a production method for determining areas of natural fracturing. Advanced Resources has demonstrated that such a relationship exists in the southern Piceance basin tight gas play. Natural fracture clusters are genetically related to stress concentrations (also called stress perturbations) associated with local deformation such a faulting. The mechanical explanation of this phenomenon is that deformation generally initiates at regions where the local stress field is elevated beyond the regional. (2) Regional structural and geologic analysis of the Greater Green River Basin (GGRB). Application of techniques developed and demonstrated during earlier phases of the project for sweet-spot delineation were demonstrated in a relatively new and underexplored play: tight gas from continuous-typeUpper Cretaceous reservoirs of the Greater Green River Basin (GGRB). The effort included data acquisition/processing, base map generation, geophysical and remote sensing analysis and the integration of these data and analyses. (3) Examination of the Table Rock field area in the northern Washakie Basin of the Greater Green River Basin. This effort was performed in support of Union Pacific Resources- and DOE-planned horizontal drilling efforts. The effort comprised acquisition of necessary seismic data and depth-conversion, mapping of major fault geometry, and analysis of displacement vectors, and the development of the natural fracture prediction. (4) Greater Green River Basin Partitioning. Building on fundamental fracture characterization work and prior work performed under this contract, namely structural analysis using satellite and

  7. US production of natural gas from tight reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    1993-10-18

    For the purposes of this report, tight gas reservoirs are defined as those that meet the Federal Energy Regulatory Commission`s (FERC) definition of tight. They are generally characterized by an average reservoir rock permeability to gas of 0.1 millidarcy or less and, absent artificial stimulation of production, by production rates that do not exceed 5 barrels of oil per day and certain specified daily volumes of gas which increase with the depth of the reservoir. All of the statistics presented in this report pertain to wells that have been classified, from 1978 through 1991, as tight according to the FERC; i.e., they are ``legally tight`` reservoirs. Additional production from ``geologically tight`` reservoirs that have not been classified tight according to the FERC rules has been excluded. This category includes all producing wells drilled into legally designated tight gas reservoirs prior to 1978 and all producing wells drilled into physically tight gas reservoirs that have not been designated legally tight. Therefore, all gas production referenced herein is eligible for the Section 29 tax credit. Although the qualification period for the credit expired at the end of 1992, wells that were spudded (began to be drilled) between 1978 and May 1988, and from November 5, 1990, through year end 1992, are eligible for the tax credit for a subsequent period of 10 years. This report updates the EIA`s tight gas production information through 1991 and considers further the history and effect on tight gas production of the Federal Government`s regulatory and tax policy actions. It also provides some high points of the geologic background needed to understand the nature and location of low-permeability reservoirs.

  8. 2016 GRI Index

    OpenAIRE

    World Bank

    2016-01-01

    This 2016 World Bank Global Reporting Initiative (GRI) Index provides an overview of sustainability considerations within the World Bank’s lending and analytical services as well as its corporate activities. This index of sustainability indicators has been prepared in accordance with the internationally recognized standard for sustainability reporting GRI guidelines (https://www.globalrepo...

  9. Western tight gas sands advanced logging workshop proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Jennings, J B; Carroll, Jr, H B [eds.

    1982-04-01

    An advanced logging research program is one major aspect of the Western Tight Sands Program. Purpose of this workshop is to help BETC define critical logging needs for tight gas sands and to allow free interchange of ideas on all aspects of the current logging research program. Sixteen papers and abstracts are included together with discussions. Separate abstracts have been prepared for the 12 papers. (DLC)

  10. Advanced Hydraulic Fracturing Technology for Unconventional Tight Gas Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Stephen Holditch; A. Daniel Hill; D. Zhu

    2007-06-19

    The objectives of this project are to develop and test new techniques for creating extensive, conductive hydraulic fractures in unconventional tight gas reservoirs by statistically assessing the productivity achieved in hundreds of field treatments with a variety of current fracturing practices ranging from 'water fracs' to conventional gel fracture treatments; by laboratory measurements of the conductivity created with high rate proppant fracturing using an entirely new conductivity test - the 'dynamic fracture conductivity test'; and by developing design models to implement the optimal fracture treatments determined from the field assessment and the laboratory measurements. One of the tasks of this project is to create an 'advisor' or expert system for completion, production and stimulation of tight gas reservoirs. A central part of this study is an extensive survey of the productivity of hundreds of tight gas wells that have been hydraulically fractured. We have been doing an extensive literature search of the SPE eLibrary, DOE, Gas Technology Institute (GTI), Bureau of Economic Geology and IHS Energy, for publicly available technical reports about procedures of drilling, completion and production of the tight gas wells. We have downloaded numerous papers and read and summarized the information to build a database that will contain field treatment data, organized by geographic location, and hydraulic fracture treatment design data, organized by the treatment type. We have conducted experimental study on 'dynamic fracture conductivity' created when proppant slurries are pumped into hydraulic fractures in tight gas sands. Unlike conventional fracture conductivity tests in which proppant is loaded into the fracture artificially; we pump proppant/frac fluid slurries into a fracture cell, dynamically placing the proppant just as it occurs in the field. From such tests, we expect to gain new insights into some of the critical

  11. Gas-Water Flow Behavior in Water-Bearing Tight Gas Reservoirs

    Directory of Open Access Journals (Sweden)

    Renyi Cao

    2017-01-01

    Full Text Available Some tight sandstone gas reservoirs contain mobile water, and the mobile water generally has a significant impact on the gas flowing in tight pores. The flow behavior of gas and water in tight pores is different than in conventional formations, yet there is a lack of adequate models to predict the gas production and describe the gas-water flow behaviors in water-bearing tight gas reservoirs. Based on the experimental results, this paper presents mathematical models to describe flow behaviors of gas and water in tight gas formations; the threshold pressure gradient, stress sensitivity, and relative permeability are all considered in our models. A numerical simulator using these models has been developed to improve the flow simulation accuracy for water-bearing tight gas reservoirs. The results show that the effect of stress sensitivity becomes larger as water saturation increases, leading to a fast decline of gas production; in addition, the nonlinear flow of gas phase is aggravated with the increase of water saturation and the decrease of permeability. The gas recovery decreases when the threshold pressure gradient (TPG and stress sensitivity are taken into account. Therefore, a reasonable drawdown pressure should be set to minimize the damage of nonlinear factors to gas recovery.

  12. Gas transport in tight porous media Gas kinetic approach

    DEFF Research Database (Denmark)

    Shapiro, Alexander; Wesselingh, Johannes

    2008-01-01

    We describe the flow of gas in a porous medium in the kinetic regime, where the viscous flow structure is not formed in separate pores. Special attention is paid to the dense kinetic regime, where the interactions within the gas are as important as the interaction with the porous medium....... The transport law for this regime is derived by means of the gas kinetic theory, in the framework of the model of "heavy gas in light one". The computations of the gas kinetic theory are confirmed by the dimension analysis and a simplified derivation revealing the considerations behind the kinetic derivation...

  13. Gas transport in tight porous media Gas kinetic approach

    NARCIS (Netherlands)

    Shapiro, A. A.; Wesselingh, Johannes

    2008-01-01

    We describe the flow of gas in a porous medium in the kinetic regime, where the viscous flow structure is not formed in separate pores. Special attention is paid to the dense kinetic regime, where the interactions within the gas are as important as the interaction with the porous medium. The

  14. Engineering support services for the DOE/GRI coal-gasification research program. Technical and economical comparisons of the Westinghouse and I. G. T. U-Gas coal-gasification processes

    Energy Technology Data Exchange (ETDEWEB)

    Bostwick, L.E.; Hubbard, D.A.; Laramore, R.W.; Koneru, P.B.

    1981-07-01

    Kellogg was requested by DOE/GRI to prepare technical and economic assessments of the Westinghouse and IGT U-Gas processes such that comparison of the two would be on a consistent basis. Kellogg carried out this task in essentially two phases: (a) preparation of consistent designs of coal-to-SNG plants using the two processes, and (b) evaluation of the design bases in light of research data. Comparable designs and economics were prepared for grass-roots facilities to produce SNG equivalent to 250 billion Btu/day from Pittsburgh No. 8 coal, using the Westinghouse and U-Gas gasifiers. The C.F. Braun Guidelines were followed. The capital and operating costs are almost identical for the two processes. In Kellogg's view, the economics as developed during this study do not show cause to favor either process over the other. The small differences in costs are well within the accuracies of the estimates and should be considered insignificant. Nine differences between the Westinghouse and U-Gas processes are listed which could possibly provide an advantage to one or to the other. Opportunities exist for both processes to enhance efficiencies and/or to reduce costs by optimization of the gas treating and byproduct recovery areas. Kellogg observes that both Westinghouse and U-Gas appear to be very competitive (in economics as developed during this study) with other coal gasification processes evaluated under the Joint DOE/GRI Program.

  15. Imaging pore space in tight gas sandstone reservoir: insights from broad ion beam cross-sectioning

    OpenAIRE

    Konstanty J.; Kukla P.A.; Urai J.L.; Baerle C.; Enzmann F.; Desbois G.

    2010-01-01

    Monetization of tight gas reservoirs, which contain significant gas reserves world-wide, represents a challenge for the entire oil and gas industry. The development of new technologies to enhance tight gas reservoir productivity is strongly dependent on an improved understanding of the rock properties and especially the pore framework. Numerous methods are now available to characterize sandstone cores. However, the pore space characterization at pore scale remains difficult due to the f...

  16. Assessment of tight-gas resources in Canyon sandstones of the Val Verde Basin, Texas, 2016

    Science.gov (United States)

    Schenk, Christopher J.; Tennyson, Marilyn E.; Klett, Timothy R.; Mercier, Tracey J.; Brownfield, Michael E.; Gaswirth, Stephanie B.; Hawkins, Sarah J.; Leathers-Miller, Heidi M.; Marra, Kristen R.; Finn, Thomas M.; Pitman, Janet K.

    2016-07-08

    Using a geology-based assessment methodology, the U.S. Geological Survey assessed mean resources of 5 trillion cubic feet of gas and 187 million barrels of natural gas liquids in tight-gas assessment units in the Canyon sandstones of the Val Verde Basin, Texas.

  17. Structurally controlled and aligned tight gas reservoir compartmentalization in the San Juan and Piceance Basins

    Energy Technology Data Exchange (ETDEWEB)

    Decker, A.D.; Kuuskraa, V.A.; Klawitter, A.L.

    1995-10-01

    Recurrent basement faulting is the primary controlling mechanism for aligning and compartmentalizing upper Cretaceous aged tight gas reservoirs of the San Juan and Piceance Basins. Northwest trending structural lineaments that formed in conjunction with the Uncompahgre Highlands have profoundly influenced sedimentation trends and created boundaries for gas migration; sealing and compartmentalizing sedimentary packages in both basins. Fractures which formed over the structural lineaments provide permeability pathways which allowing gas recovery from otherwise tight gas reservoirs. Structural alignments and associated reservoir compartments have been accurately targeted by integrating advanced remote sensing imagery, high resolution aeromagnetics, seismic interpretation, stratigraphic mapping and dynamic structural modelling. This unifying methodology is a powerful tool for exploration geologists and is also a systematic approach to tight gas resource assessment in frontier basins.

  18. Leak testing of bubble-tight dampers using tracer gas techniques

    Energy Technology Data Exchange (ETDEWEB)

    Lagus, P.L. [Lagus Applied Technology, Inc., San Diego, CA (United States); DuBois, L.J. [Commonwealth Edison, Zion, IL (United States); Fleming, K.M. [NCS Corporation, Columbus, OH (United States)] [and others

    1995-02-01

    Recently tracer gas techniques have been applied to the problem of measuring the leakage across an installed bubble-tight damper. A significant advantage of using a tracer gas technique is that quantitative leakage data are obtained under actual operating differential pressure conditions. Another advantage is that leakage data can be obtained using relatively simple test setups that utilize inexpensive materials without the need to tear ducts apart, fabricate expensive blank-off plates, and install test connections. Also, a tracer gas technique can be used to provide an accurate field evaluation of the performance of installed bubble-tight dampers on a periodic basis. Actual leakage flowrates were obtained at Zion Generating Station on four installed bubble-tight dampers using a tracer gas technique. Measured leakage rates ranged from 0.01 CFM to 21 CFM. After adjustment and subsequent retesting, the 21 CFM damper leakage was reduced to a leakage of 3.8 CFM. In light of the current regulatory climate and the interest in Control Room Habitability issues, imprecise estimates of critical air boundary leakage rates--such as through bubble-tight dampers--are not acceptable. These imprecise estimates can skew radioactive dose assessments as well as chemical contaminant exposure calculations. Using a tracer gas technique, the actual leakage rate can be determined. This knowledge eliminates a significant source of uncertainty in both radioactive dose and/or chemical exposure assessments.

  19. Sonic and electrical properties of partially saturated tight-gas sands. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Nur, A.

    1983-03-01

    This study was aimed at relating the seismic and the electrical properties of tight-gas rocks to their pore-space geometry, permeability, and level of water saturation. Here we report results of a laboratory experimental study of wave propagation in Cotton Valley and Spirit River Sandstones as a function of partial water saturation (SW) and wave frequency. We find that wave velocities and the velocity ratio are sensitive to the presence of gas. Furthermore, wave attenuation is sensitive to the amount of gas in the pore space. Ultrasonic measurements in tight-gas sands tend to yield higher velocity values, due to the inability of the pore fluid pressure to homogenize during the passage of waves. Laboratory measurements were made also of the complex electrical response of selected tight rocks, and compared with normal permeability Berea Sandstone. The results show that the dielectric property of tight-gas sands is very sensitive to partial water saturation, and may give not only insight into the nature of the pore space, but also provide a practical measure of S/sub w/ in situ. 35 figures, 2 tables.

  20. Production of Natural Gas and Fluid Flow in Tight Sand Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Maria Cecilia Bravo

    2006-06-30

    This document reports progress of this research effort in identifying relationships and defining dependencies between macroscopic reservoir parameters strongly affected by microscopic flow dynamics and production well performance in tight gas sand reservoirs. These dependencies are investigated by identifying the main transport mechanisms at the pore scale that should affect fluids flow at the reservoir scale. A critical review of commercial reservoir simulators, used to predict tight sand gas reservoir, revealed that many are poor when used to model fluid flow through tight reservoirs. Conventional simulators ignore altogether or model incorrectly certain phenomena such as, Knudsen diffusion, electro-kinetic effects, ordinary diffusion mechanisms and water vaporization. We studied the effect of Knudsen's number in Klinkenberg's equation and evaluated the effect of different flow regimes on Klinkenberg's parameter b. We developed a model capable of explaining the pressure dependence of this parameter that has been experimentally observed, but not explained in the conventional formalisms. We demonstrated the relevance of this, so far ignored effect, in tight sands reservoir modeling. A 2-D numerical simulator based on equations that capture the above mentioned phenomena was developed. Dynamic implications of new equations are comprehensively discussed in our work and their relative contribution to the flow rate is evaluated. We performed several simulation sensitivity studies that evidenced that, in general terms, our formalism should be implemented in order to get more reliable tight sands gas reservoirs' predictions.

  1. Naturally fractured tight gas: Gas reservoir detection optimization. Quarterly report, January 1--March 31, 1997

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    Economically viable natural gas production from the low permeability Mesaverde Formation in the Piceance Basin, Colorado requires the presence of an intense set of open natural fractures. Establishing the regional presence and specific location of such natural fractures is the highest priority exploration goal in the Piceance and other western US tight, gas-centered basins. Recently, Advanced Resources International, Inc. (ARI) completed a field program at Rulison Field, Piceance Basin, to test and demonstrate the use of advanced seismic methods to locate and characterize natural fractures. This project began with a comprehensive review of the tectonic history, state of stress and fracture genesis of the basin. A high resolution aeromagnetic survey, interpreted satellite and SLAR imagery, and 400 line miles of 2-D seismic provided the foundation for the structural interpretation. The central feature of the program was the 4.5 square mile multi-azimuth 3-D seismic P-wave survey to locate natural fracture anomalies. The interpreted seismic attributes are being tested against a control data set of 27 wells. Additional wells are currently being drilled at Rulison, on close 40 acre spacings, to establish the productivity from the seismically observed fracture anomalies. A similar regional prospecting and seismic program is being considered for another part of the basin. The preliminary results indicate that detailed mapping of fault geometries and use of azimuthally defined seismic attributes exhibit close correlation with high productivity gas wells. The performance of the ten new wells, being drilled in the seismic grid in late 1996 and early 1997, will help demonstrate the reliability of this natural fracture detection and mapping technology.

  2. Assessment of Permian tight oil and gas resources in the Junggar basin of China, 2016

    Science.gov (United States)

    Potter, Christopher J.; Schenk, Christopher J.; Tennyson, Marilyn E.; Klett, Timothy R.; Gaswirth, Stephanie B.; Leathers-Miller, Heidi M.; Finn, Thomas M.; Brownfield, Michael E.; Pitman, Janet K.; Mercier, Tracey J.; Le, Phuong A.; Drake, Ronald M.

    2017-04-05

    Using a geology-based assessment methodology, the U.S. Geological Survey estimated undiscovered, technically recoverable mean resources of 764 million barrels of oil and 3.5 trillion cubic feet of gas in tight reservoirs in the Permian Lucaogou Formation in the Junggar basin of northwestern China.

  3. Naturally fractured tight gas reservoir detection optimization. Quarterly report, January 1, 1997--March 31, 1997

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-04-01

    This document contains the quarterly report dated January 1-March 31, 1997 for the Naturally Fractured Tight Gas Reservoir Detection Optimization project. Topics covered in this report include AVOA modeling using paraxial ray tracing, AVOA modeling for gas- and water-filled fractures, 3-D and 3-C processing, and technology transfer material. Several presentations from a Geophysical Applications Workshop workbook, workshop schedule, and list of workshop attendees are also included.

  4. OPTIMIZATION OF INFILL DRILLING IN NATURALLY-FRACTURED TIGHT-GAS RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence W. Teufel; Her-Yuan Chen; Thomas W. Engler; Bruce Hart

    2004-05-01

    A major goal of industry and the U.S. Department of Energy (DOE) fossil energy program is to increase gas reserves in tight-gas reservoirs. Infill drilling and hydraulic fracture stimulation in these reservoirs are important reservoir management strategies to increase production and reserves. Phase II of this DOE/cooperative industry project focused on optimization of infill drilling and evaluation of hydraulic fracturing in naturally-fractured tight-gas reservoirs. The cooperative project involved multidisciplinary reservoir characterization and simulation studies to determine infill well potential in the Mesaverde and Dakota sandstone formations at selected areas in the San Juan Basin of northwestern New Mexico. This work used the methodology and approach developed in Phase I. Integrated reservoir description and hydraulic fracture treatment analyses were also conducted in the Pecos Slope Abo tight-gas reservoir in southeastern New Mexico and the Lewis Shale in the San Juan Basin. This study has demonstrated a methodology to (1) describe reservoir heterogeneities and natural fracture systems, (2) determine reservoir permeability and permeability anisotropy, (3) define the elliptical drainage area and recoverable gas for existing wells, (4) determine the optimal location and number of new in-fill wells to maximize economic recovery, (5) forecast the increase in total cumulative gas production from infill drilling, and (6) evaluate hydraulic fracture simulation treatments and their impact on well drainage area and infill well potential. Industry partners during the course of this five-year project included BP, Burlington Resources, ConocoPhillips, and Williams.

  5. Reducing Mechanical Formation Damage by Minimizing Interfacial Tension and Capillary Pressure in Tight Gas

    Science.gov (United States)

    Ahmed, Arshad; Talib Shuker, Muhannad; Rehman, Khalil; Bahrami, Hassan; Memon, Muhammad Khan

    2013-12-01

    Tight gas reservoirs incur problems and significant damage caused by low permeability during drilling, completion, stimulation and production. They require advanced improvement techniques to achieve flow gas at optimum rates. Water blocking damage (phase Trapping/retention of fluids) is a form of mechanical formation damage mechanism, which is caused by filtrate invasion in drilling operations mostly in fracturing. Water blocking has a noticeable impact on formation damage in gas reservoirs which tends to decrease relative permeability near the wellbore. Proper evaluation of damage and the factors which influence its severity is essential to optimize well productivity. Reliable data regarding interfacial tension between gas and water is required in order to minimize mechanical formation damage potential and to optimize gas production. This study was based on the laboratory experiments of interfacial tension by rising drop method between gas-brine, gas-condensate and gas-brine. The results showed gas condensate has low interfacial tension value 6 - 11 dynes/cm when compared to gas-brine and gas- diesel which were 44 - 58 dynes/cm and 14 - 19 dynes/cm respectively. In this way, the capillary pressure of brine-gas system was estimated as 0.488 psi, therefore diesel-gas system was noticed about 0.164 psi and 0.098 psi for condensate-gas system. A forecast model was used by using IFT values to predict the phase trapping which shows less severe phase trapping damage in case of condensate than diesel and brine. A reservoir simulation study was also carried out in order to better understand the effect of hysteresis on well productivity and flow efficiency affected due to water blocking damage in tight gas reservoirs.

  6. A new method of evaluating tight gas sands pore structure from nuclear magnetic resonance (NMR) logs

    Science.gov (United States)

    Xiao, Liang; Mao, Zhi-qiang; Xie, Xiu-hong

    2016-04-01

    Tight gas sands always display such characteristics of ultra-low porosity, permeability, high irreducible water, low resistivity contrast, complicated pore structure and strong heterogeneity, these make that the conventional methods are invalid. Many effective gas bearing formations are considered as dry zones or water saturated layers, and cannot be identified and exploited. To improve tight gas sands evaluation, the best method is quantitative characterizing rock pore structure. The mercury injection capillary pressure (MICP) curves are advantageous in predicting formation pore structure. However, the MICP experimental measurements are limited due to the environment and economy factors, this leads formation pore structure cannot be consecutively evaluated. Nuclear magnetic resonance (NMR) logs are considered to be promising in evaluating rock pore structure. Generally, to consecutively quantitatively evaluate tight gas sands pore structure, the best method is constructing pseudo Pc curves from NMR logs. In this paper, based on the analysis of lab experimental results for 20 core samples, which were drilled from tight gas sandstone reservoirs of Sichuan basin, and simultaneously applied for lab MICP and NMR measurements, the relationships of piecewise power function between nuclear magnetic resonance (NMR) transverse relaxation T2 time and pore-throat radius Rc are established. A novel method, which is used to transform NMR reverse cumulative curve as pseudo capillary pressure (Pc) curve is proposed, and the corresponding model is established based on formation classification. By using this model, formation pseudo Pc curves can be consecutively synthesized. The pore throat radius distribution, and pore structure evaluation parameters, such as the average pore throat radius (Rm), the threshold pressure (Pd), the maximum pore throat radius (Rmax) and so on, can also be precisely extracted. After this method is extended into field applications, several tight gas

  7. Characterizing tight-gas systems with production data: Wyoming, Utah, and Colorado

    Science.gov (United States)

    Nelson, Philip H.; Santus, Stephen L.; Baez, Luis; Beeney, Ken; Sonnenberg, Steve

    2013-01-01

    The study of produced fluids allows comparisons among tight-gas systems. This paper examines gas, oil, and water production data from vertical wells in 23 fields in five Rocky Mountain basins of the United States, mostly from wells completed before the year 2000. Average daily rates of gas, oil, and water production are determined two years and seven years after production begins in order to represent the interval in which gas production declines exponentially. In addition to the daily rates, results are also presented in terms of oil-to-gas and water-to-gas ratios, and in terms of the five-year decline in gas production rates and water-to-gas ratios. No attempt has been made to estimate the ultimate productivity of wells or fields. The ratio of gas production rates after seven years to gas production rates at two years is about one-half, with median ratios falling within a range of 0.4 to 0.6 in 16 fields. Oil-gas ratios show substantial variation among fields, ranging from dry gas (no oil) to wet gas to retrograde conditions. Among wells within fields, the oil-gas ratios vary by a factor of three to thirty, with the exception of the Lance Formation in Jonah and Pinedale fields, where the oil-gas ratios vary by less than a factor of two. One field produces water-free gas and a large fraction of wells in two other fields produce water-free gas, but most fields have water-gas ratios greater than 1 bbl/mmcf—greater than can be attributed to water dissolved in gas in the reservoir— and as high as 100 bbl/mmcf. The median water-gas ratio for fields increases moderately with time, but in individual wells water influx relative to gas is erratic, increasing greatly with time in many wells while remaining constant or decreasing in others.

  8. Production of Natural Gas and Fluid Flow in Tight Sand Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Maria Cecilia Bravo; Mariano Gurfinkel

    2005-06-30

    This document reports progress of this research effort in identifying possible relationships and defining dependencies between macroscopic reservoir parameters strongly affected by microscopic flow dynamics and production well performance in tight gas sand reservoirs. Based on a critical review of the available literature, a better understanding of the main weaknesses of the current state of the art of modeling and simulation for tight sand reservoirs has been reached. Progress has been made in the development and implementation of a simple reservoir simulator that is still able to overcome some of the deficiencies detected. The simulator will be used to quantify the impact of microscopic phenomena in the macroscopic behavior of tight sand gas reservoirs. Phenomena such as, Knudsen diffusion, electro-kinetic effects, ordinary diffusion mechanisms and water vaporization are being considered as part of this study. To date, the adequate modeling of gas slippage in porous media has been determined to be of great relevance in order to explain unexpected fluid flow behavior in tight sand reservoirs.

  9. Analytical modeling of gas production rate in tight channel sand formation and optimization of artificial fracture.

    Science.gov (United States)

    Wang, Ruifei; Song, Hongqing; Tang, Hewei; Wang, Yuhe; Killough, John; Huang, Gang

    2016-01-01

    Permeability variation in tight channel sand formation makes an important role in gas production. Based on the features of channel sand formation, a mathematical model has been established considering anisotropy of permeability. The analytical solutions were derived for productivity of both vertical wells and vertically fractured wells. Simulation results show that, gas production rate of anisotropic channel sand formation is less than that of isotropic formation. For vertically fractured well, artificial fracture direction, drainage radius, permeability ratio and fracture half-length have considerable influence on production rate. The optimum fracture direction should be deviated less than π/8 from the maximum permeability direction (or the channel direction). In addition, the analytical model was verified by in situ measured data. The research provides theoretical basis for the development of tight channel sand gas reservoirs.

  10. Imaging pore space in tight gas sandstone reservoir: insights from broad ion beam cross-sectioning

    Science.gov (United States)

    Desbois, G.; Enzmann, F.; Urai, J. L.; Baerle, C.; Kukla, P. A.; Konstanty, J.

    2010-06-01

    Monetization of tight gas reservoirs, which contain significant gas reserves world-wide, represents a challenge for the entire oil and gas industry. The development of new technologies to enhance tight gas reservoir productivity is strongly dependent on an improved understanding of the rock properties and especially the pore framework. Numerous methods are now available to characterize sandstone cores. However, the pore space characterization at pore scale remains difficult due to the fine pore size and delicate sample preparation, and has thus been mostly indirectly inferred until now. Here we propose a new method of ultra high-resolution petrography combining high resolution SEM and argon ion beam cross sectioning (BIB, Broad Ion Beam) which prepares smooth and damage free surfaces. We demonstrate this method using the example of Permian (Rotliegend) age tight gas sandstone core samples. The combination of Ar-beam cross-sectioning facility and high-resolution SEM imaging has the potential to result in a step change in the understanding of pore geometries, in terms of its morphology, spatial distribution and evolution based on the generation of unprecedented image quality and resolution enhancing the predictive reliability of image analysis.

  11. Imaging pore space in tight gas sandstone reservoir: insights from broad ion beam cross-sectioning

    Directory of Open Access Journals (Sweden)

    Konstanty J.

    2010-06-01

    Full Text Available Monetization of tight gas reservoirs, which contain significant gas reserves world-wide, represents a challenge for the entire oil and gas industry. The development of new technologies to enhance tight gas reservoir productivity is strongly dependent on an improved understanding of the rock properties and especially the pore framework. Numerous methods are now available to characterize sandstone cores. However, the pore space characterization at pore scale remains difficult due to the fine pore size and delicate sample preparation, and has thus been mostly indirectly inferred until now. Here we propose a new method of ultra high-resolution petrography combining high resolution SEM and argon ion beam cross sectioning (BIB, Broad Ion Beam which prepares smooth and damage free surfaces. We demonstrate this method using the example of Permian (Rotliegend age tight gas sandstone core samples. The combination of Ar-beam cross-sectioning facility and high-resolution SEM imaging has the potential to result in a step change in the understanding of pore geometries, in terms of its morphology, spatial distribution and evolution based on the generation of unprecedented image quality and resolution enhancing the predictive reliability of image analysis.

  12. Economic evaluation on tight sandstone gas development projects in China and recommendation on fiscal and taxation support policies

    Directory of Open Access Journals (Sweden)

    Zhen Yang

    2016-11-01

    Full Text Available China is rich in tight sandstone gas resources (“tight gas” for short. For example, the Sulige Gasfield in the Ordos Basin and the Upper Triassic Xujiahe Fm gas reservoir in the Sichuan Basin are typical tight gas reservoirs. In the past decade, tight gas reserve and production both have increased rapidly in China, but tight gas reservoirs are always managed as conventional gas reservoirs without effective fiscal, taxation and policy supports. The potential of sustainable tight gas production increase is obviously restricted. The tight gas development projects represented by the Sulige Gasfield have failed to make profit for a long period, and especially tight gas production has presented a slight decline since 2015. In this paper, a new economic evaluation method was proposed for tight gas development projects. The new method was designed to verify the key parameters (e.g. production decline rate and single-well economic service life depending on tight gas development and production characteristics, and perform the depreciation by using the production method. Furthermore, the possibility that the operation cost may rise due to pressure-boosting production and intermittent opening of gas wells is considered. The method was used for the tight gas development project of Sulige Gasfield, showing that its profit level is much lower than the enterprise's cost level of capital. In order to support a sustainable development of tight gas industry in China, it is recommended that relevant authorities issue value-added tax (VAT refund policy as soon as possible. It is necessary to restore the non-resident gas gate price of the provinces where tight gas is produced to the fair and reasonable level in addition to the fiscal subsidy of CNY0.24/m3, or offer the fiscal subsidy of CNY0.32/m3 directly based on the on-going gate price. With these support policies, tax income is expected to rise directly, fiscal expenditure will not increase, and gas

  13. Shale Gas and Tight Oil: A Panacea for the Energy Woes of America?

    Science.gov (United States)

    Hughes, J. D.

    2012-12-01

    Shale gas has been heralded as a "game changer" in the struggle to meet America's demand for energy. The "Pickens Plan" of Texas oil and gas pioneer T.Boone Pickens suggests that gas can replace coal for much of U.S. electricity generation, and oil for, at least, truck transportation1. Industry lobby groups such as ANGA declare "that the dream of clean, abundant, home grown energy is now reality"2. In Canada, politicians in British Columbia are racing to export the virtual bounty of shale gas via LNG to Asia (despite the fact that Canadian gas production is down 16 percent from its 2001 peak). And the EIA has forecast that the U.S. will become a net exporter of gas by 20213. Similarly, recent reports from Citigroup and Harvard suggest that an oil glut is on the horizon thanks in part to the application of fracking technology to formerly inaccessible low permeability tight oil plays. The fundamentals of well costs and declines belie this optimism. Shale gas is expensive gas. In the early days it was declared that "continuous plays" like shale gas were "manufacturing operations", and that geology didn't matter. One could drill a well anywhere, it was suggested, and expect consistent production. Unfortunately, Mother Nature always has the last word, and inevitably the vast expanses of purported potential shale gas resources contracted to "core" areas, where geological conditions were optimal. The cost to produce shale gas ranges from 4.00 per thousand cubic feet (mcf) to 10.00, depending on the play. Natural gas production is a story about declines which now amount to 32% per year in the U.S. So 22 billion cubic feet per day of production now has to be replaced each year to keep overall production flat. At current prices of 2.50/mcf, industry is short about 50 billion per year in cash flow to make this happen4. As a result I expect falling production and rising prices in the near to medium term. Similarly, tight oil plays in North Dakota and Texas have been heralded

  14. Study of Gas Flow Characteristics in Tight Porous Media with a Microscale Lattice Boltzmann Model

    Science.gov (United States)

    Zhao, Jianlin; Yao, Jun; Zhang, Min; Zhang, Lei; Yang, Yongfei; Sun, Hai; An, Senyou; Li, Aifen

    2016-01-01

    To investigate the gas flow characteristics in tight porous media, a microscale lattice Boltzmann (LB) model with the regularization procedure is firstly adopted to simulate gas flow in three-dimensional (3D) digital rocks. A shale digital rock and a sandstone digital rock are reconstructed to study the effects of pressure, temperature and pore size on microscale gas flow. The simulation results show that because of the microscale effect in tight porous media, the apparent permeability is always higher than the intrinsic permeability, and with the decrease of pressure or pore size, or with the increase of temperature, the difference between apparent permeability and intrinsic permeability increases. In addition, the Knudsen numbers under different conditions are calculated and the results show that gas flow characteristics in the digital rocks under different Knudsen numbers are quite different. With the increase of Knudsen number, gas flow in the digital rocks becomes more uniform and the effect of heterogeneity of the porous media on gas flow decreases. Finally, two commonly used apparent permeability calculation models are evaluated by the simulation results and the Klinkenberg model shows better accuracy. In addition, a better proportionality factor in Klinkenberg model is proposed according to the simulation results. PMID:27587293

  15. Study of Gas Flow Characteristics in Tight Porous Media with a Microscale Lattice Boltzmann Model

    Science.gov (United States)

    Zhao, Jianlin; Yao, Jun; Zhang, Min; Zhang, Lei; Yang, Yongfei; Sun, Hai; An, Senyou; Li, Aifen

    2016-09-01

    To investigate the gas flow characteristics in tight porous media, a microscale lattice Boltzmann (LB) model with the regularization procedure is firstly adopted to simulate gas flow in three-dimensional (3D) digital rocks. A shale digital rock and a sandstone digital rock are reconstructed to study the effects of pressure, temperature and pore size on microscale gas flow. The simulation results show that because of the microscale effect in tight porous media, the apparent permeability is always higher than the intrinsic permeability, and with the decrease of pressure or pore size, or with the increase of temperature, the difference between apparent permeability and intrinsic permeability increases. In addition, the Knudsen numbers under different conditions are calculated and the results show that gas flow characteristics in the digital rocks under different Knudsen numbers are quite different. With the increase of Knudsen number, gas flow in the digital rocks becomes more uniform and the effect of heterogeneity of the porous media on gas flow decreases. Finally, two commonly used apparent permeability calculation models are evaluated by the simulation results and the Klinkenberg model shows better accuracy. In addition, a better proportionality factor in Klinkenberg model is proposed according to the simulation results.

  16. Stability of Fluorosurfactant Adsorption on Mineral Surface for Water Removal in Tight Gas Reservoirs

    OpenAIRE

    Lijun You; Wanchun Zhang; Yili Kang; Zhangxin Chen; Xuefen Liu

    2015-01-01

    Long-term effectiveness of rock wettability alteration for water removal during gas production from tight reservoir depends on the surfactant adsorption on the pore surface of a reservoir. This paper selected typical cationic fluorosurfactant FW-134 as an example and took advantage of Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and atomic force microscope (AFM) to investigate its adsorption stability on the rock mineral surface under the oscillation...

  17. Life cycle greenhouse gas emissions and freshwater consumption associated with Bakken tight oil.

    Science.gov (United States)

    Laurenzi, Ian J; Bergerson, Joule A; Motazedi, Kavan

    2016-11-29

    In recent years, hydraulic fracturing and horizontal drilling have been applied to extract crude oil from tight reservoirs, including the Bakken formation. There is growing interest in understanding the greenhouse gas (GHG) emissions associated with the development of tight oil. We conducted a life cycle assessment of Bakken crude using data from operations throughout the supply chain, including drilling and completion, refining, and use of refined products. If associated gas is gathered throughout the Bakken well life cycle, then the well to wheel GHG emissions are estimated to be 89 g CO2eq/MJ (80% CI, 87-94) of Bakken-derived gasoline and 90 g CO2eq/MJ (80% CI, 88-94) of diesel. If associated gas is flared for the first 12 mo of production, then life cycle GHG emissions increase by 5% on average. Regardless of the level of flaring, the Bakken life cycle GHG emissions are comparable to those of other crudes refined in the United States because flaring GHG emissions are largely offset at the refinery due to the physical properties of this tight oil. We also assessed the life cycle freshwater consumptions of Bakken-derived gasoline and diesel to be 1.14 (80% CI, 0.67-2.15) and 1.22 barrel/barrel (80% CI, 0.71-2.29), respectively, 13% of which is associated with hydraulic fracturing.

  18. Enhanced recovery of unconventional gas. Volume II. The program. [Tight gas basins; Devonian shale; coal seams; geopressured aquifers

    Energy Technology Data Exchange (ETDEWEB)

    Kuuskraa, V.A.; Brashear, J.P.; Doscher, T.M.; Elkins, L.E.

    1978-10-01

    This study was conducted to assist public decision-makers in selecting among many choices to obtain new gas supplies by addressing 2 questions: 1) how severe is the need for additional future supplies of natural gas, and what is the economic potential of providing part of future supply through enhanced recovery from unconventional natural gas resources. The study also serves to assist the DOE in designing a cost-effective R and D program to stimulate industry to recover this unconventional gas and to produce it sooner. Tight gas basins, Devonian shale, methane from coal seams, and methane from geopressured aquifers are considered. It is concluded that unconventional sources, already providing about 1 Tcf per year, could provide from 3 to 4 Tcf in 1985 and from 6 to 8 Tcf in 1990 (at $1.75 and $3.00 per Mcf, respectively). However, even with these additions to supply, gas supply is projected to remain below 1977 usage levels. (DLC)

  19. GRI methane chemistry program review meeting

    Energy Technology Data Exchange (ETDEWEB)

    Dignon, J.; Grant, K.; Grossman, A.; Wuebles, D.; Brasseur, G.; Madronich, S.; Huang, T.; Chang, J.; Lott, B.

    1997-02-01

    Methane is an important greenhouse gas which affects the atmosphere directly by the absorption and re-emission of infrared radiation as well as indirectly, through chemical interactions. Emissions of several important greenhouse gases (GHGS) including methane are increasing, mainly due to human activity. Higher concentrations of these gases in the atmosphere are projected to cause a decrease in the amount of infrared radiation escaping to space, and a subsequent warming of global climate. It is therefore vital to understand not only the causes of increased production of methane and other GHGS, but the effect of higher GHG concentrations on climate, and the possibilities for reductions of these emissions. In GRI-UIUC methane project, the role of methane in climate change and greenhouse gas abatement strategies is being studied using several distinct approaches. First, a detailed treatment of the mechanisms controlling each important methane source and sink, and hence the atmospheric concentration of methane, is being developed for use with the UIUC Integrated Science Assessment Model. The focus of this study is to resolve the factors which determine methane emissions and removal, including human population, land use, energy demand, global temperature, and regional concentrations of the hydroxyl radical, carbon monoxide, nitrous oxides, non-methane hydrocarbons, water vapor, tropospheric and stratospheric ozone.

  20. Pore-scale mechanisms of gas flow in tight sand reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Silin, D.; Kneafsey, T.J.; Ajo-Franklin, J.B.; Nico, P.

    2010-11-30

    Tight gas sands are unconventional hydrocarbon energy resource storing large volume of natural gas. Microscopy and 3D imaging of reservoir samples at different scales and resolutions provide insights into the coaredo not significantly smaller in size than conventional sandstones, the extremely dense grain packing makes the pore space tortuous, and the porosity is small. In some cases the inter-granular void space is presented by micron-scale slits, whose geometry requires imaging at submicron resolutions. Maximal Inscribed Spheres computations simulate different scenarios of capillary-equilibrium two-phase fluid displacement. For tight sands, the simulations predict an unusually low wetting fluid saturation threshold, at which the non-wetting phase becomes disconnected. Flow simulations in combination with Maximal Inscribed Spheres computations evaluate relative permeability curves. The computations show that at the threshold saturation, when the nonwetting fluid becomes disconnected, the flow of both fluids is practically blocked. The nonwetting phase is immobile due to the disconnectedness, while the permeability to the wetting phase remains essentially equal to zero due to the pore space geometry. This observation explains the Permeability Jail, which was defined earlier by others. The gas is trapped by capillarity, and the brine is immobile due to the dynamic effects. At the same time, in drainage, simulations predict that the mobility of at least one of the fluids is greater than zero at all saturations. A pore-scale model of gas condensate dropout predicts the rate to be proportional to the scalar product of the fluid velocity and pressure gradient. The narrowest constriction in the flow path is subject to the highest rate of condensation. The pore-scale model naturally upscales to the Panfilov's Darcy-scale model, which implies that the condensate dropout rate is proportional to the pressure gradient squared. Pressure gradient is the greatest near the

  1. The experimental modeling of gas percolation mechanisms in a coal-measure tight sandstone reservoir: A case study on the coal-measure tight sandstone gas in the Upper Triassic Xujiahe Formation, Sichuan Basin, China

    Directory of Open Access Journals (Sweden)

    Shizhen Tao

    2016-12-01

    Full Text Available Tight sandstone gas from coal-measure source rock is widespread in China, and it is represented by the Xujiahe Formation of the Sichuan Basin and the Upper Paleozoic of the Ordos Basin. It is affected by planar evaporative hydrocarbon expulsion of coal-measure source rock and the gentle structural background; hydrodynamics and buoyancy play a limited role in the gas migration-accumulation in tight sandstone. Under the conditions of low permeability and speed, non-Darcy flow is quite apparent, it gives rise to gas-water mixed gas zone. In the gas displacing water experiment, the shape of percolation flow curve is mainly influenced by core permeability. The lower the permeability, the higher the starting pressure gradient as well as the more evident the non-Darcy phenomenon will be. In the gas displacing water experiment of tight sandstone, the maximum gas saturation of the core is generally less than 50% (ranging from 30% to 40% and averaging at 38%; it is similar to the actual gas saturation of the gas zone in the subsurface core. The gas saturation and permeability of the core have a logarithm correlation with a correlation coefficient of 0.8915. In the single-phase flow of tight sandstone gas, low-velocity non-Darcy percolation is apparent; the initial flow velocity (Vd exists due to the slippage effect of gas flow. The shape of percolation flow curve of a single-phase gas is primarily controlled by core permeability and confining pressure; the lower the permeability or the higher the confining pressure, the higher the starting pressure (0.02–0.08 MPa/cm, whereas, the higher the quasi-initial flow speed, the longer the nonlinear section and the more obvious the non-Darcy flow will be. The tight sandstone gas seepage mechanism study shows that the lower the reservoir permeability, the higher the starting pressure and the slower the flow velocity will be, this results in the low efficiency of natural gas migration and accumulation as well as

  2. ADVANCED FRACTURING TECHNOLOGY FOR TIGHT GAS: AN EAST TEXAS FIELD DEMONSTRATION

    Energy Technology Data Exchange (ETDEWEB)

    Mukul M. Sharma

    2005-03-01

    The primary objective of this research was to improve completion and fracturing practices in gas reservoirs in marginal plays in the continental United States. The Bossier Play in East Texas, a very active tight gas play, was chosen as the site to develop and test the new strategies for completion and fracturing. Figure 1 provides a general location map for the Dowdy Ranch Field, where the wells involved in this study are located. The Bossier and other tight gas formations in the continental Unites States are marginal plays in that they become uneconomical at gas prices below $2.00 MCF. It was, therefore, imperative that completion and fracturing practices be optimized so that these gas wells remain economically attractive. The economic viability of this play is strongly dependent on the cost and effectiveness of the hydraulic fracturing used in its well completions. Water-fracs consisting of proppant pumped with un-gelled fluid is the type of stimulation used in many low permeability reservoirs in East Texas and throughout the United States. The use of low viscosity Newtonian fluids allows the creation of long narrow fractures in the reservoir, without the excessive height growth that is often seen with cross-linked fluids. These low viscosity fluids have poor proppant transport properties. Pressure transient tests run on several wells that have been water-fractured indicate a long effective fracture length with very low fracture conductivity even when large amounts of proppant are placed in the formation. A modification to the water-frac stimulation design was needed to transport proppant farther out into the fracture. This requires suspending the proppant until the fracture closes without generating excessive fracture height. A review of fracture diagnostic data collected from various wells in different areas (for conventional gel and water-fracs) suggests that effective propped lengths for the fracture treatments are sometimes significantly shorter than those

  3. Anoxic incubation of sediment in gas-tight plastic bags: a method for biogeochemical process studies

    DEFF Research Database (Denmark)

    Hansen, JW; Thamdrup, B.; Jørgensen, BB

    2000-01-01

    Incubation of sediment in gas-tight plastic bags is described as a method for experimental studies of biogeochemical processes. Sediment incubation in these bags allows time-course experiments to be conducted on homogenised sediment without dilution, continuous stirring, or gaseous head......-space. Consequently, bag incubations of sediment combine the advantage of low heterogeneity in slurry incubations with the more natural conditions in jar and whole-core incubations. The bag material is a transparent laminated plastic comprised of Nylon, ethylenevinyl alcohol, and polyethylene with a low permeability...... for the studied gases: O-2, CO2, H2S, CH4, N-2, H-2, and He. Estimated fluxes of biologically active gases through the plastic bag during sediment incubation were insignificant compared to rates of microbial processes and to gas concentrations in coastal sediments. An exception was CH4, for which process...

  4. Design of the ATLAS New Small Wheel Gas Leak Tightness Station for the Micromegas Detector Modules

    CERN Document Server

    Gazis, Evangelos; The ATLAS collaboration

    2017-01-01

    In this work we describe advanced data processing and analysis techniques intended to be used in the gas tightness station at CERN for Quality Assurance and Quality Control of the New Small Wheel Micromegas Quadruplets. We combine two methods: a conventional one based on the Pressure Decay Rate and an alternative-novel one, based on the Flow Rate Loss. A prototype setup has been developed based on a Lock-in Amplifier device and should be operated in conjunction with the gas leak test via the Flow Rate Loss. Both methods have been tested by using emulated leak branches based on specific thin medical needles. The semi-automatic data acquisition, monitoring and processing system is presented also in this work while a more sophisticated environment based on the WinCC-OA SCADA is under development.

  5. Pressure Transient Analysis of Multi-Fractured Horizontal Well in Tight Gas Reservoirs

    Directory of Open Access Journals (Sweden)

    Zhao Ermeng

    2016-01-01

    Full Text Available Multi-fractured horizontal well is applied in tight gas reservoirs due to the low permeability. A new pressure transient model of multi-fractured horizontal well based on discrete-fracture model in which the hydraulic fractures are discretized as 2D entities is built in this paper, The model is divided into hydraulic fracture region and formation region. The model can be solved using the Galerkin finite element method, then the pressure transient type curves are plotted by computer programming. The results show that there are five different flow regimes observed in type curves including early linear flow, early radial flow, elliptical flow, later pseudo-radial flow and boundary response regime. A sensitivity analysis is conducted to study impacts of hydraulic fracture number, hydraulic fracture half-length, hydraulic fracture spacing, and hydraulic fracture conductivity on pressure transient type curves. The new model and obtained results in this paper not only enrich the well testing models, but also play a guiding role in analyzing pressure transient response of multi-fractured horizontal well in tight gas reservoirs.

  6. Estimation of Permeability from NMR Logs Based on Formation Classification Method in Tight Gas Sands

    Directory of Open Access Journals (Sweden)

    Wei Deng-Feng

    2015-10-01

    Full Text Available The Schlumberger Doll Research (SDR model and cross plot of porosity versus permeability cannot be directly used in tight gas sands. In this study, the HFU approach is introduced to classify rocks, and determine the involved parameters in the SDR model. Based on the difference of FZI, 87 core samples, drilled from tight gas sandstones reservoirs of E basin in northwest China and applied for laboratory NMR measurements, were classified into three types, and the involved parameters in the SDR model are calibrated separately. Meanwhile, relationships of porosity versus permeability are also established. The statistical model is used to calculate consecutive FZI from conventional logs. Field examples illustrate that the calibrated SDR models are applicable in permeability estimation; models established from routine core analyzed results are effective in reservoirs with permeability lower than 0.3 mD, while the unified SDR model is only valid in reservoirs with permeability ranges from 0.1 to 0.3 mD.

  7. Dynamic gas slippage: A unique dual-mechanism approach to the flow of gas in tight formations

    Energy Technology Data Exchange (ETDEWEB)

    Ertekin; King, G.R.; Schwerer, F.C.

    1983-10-01

    A mathematical formulation, applicable to both numerical simulation and transient well analysis, describing the flow of gas in very tight (k < 0.1 md) porous media has been developed. Unique to this formulation is the dual-mechanism transport of gas. In this formulation gas is assumed to be traveling under the influence of two fields: a concentration field and a pressure field. Transport through the concentration field is a Knudsen flow process and is modeled with Fick's Law of diffusion. Transport through the pressure field is a laminar process and is modeled with Darcy's law (inertial-turbulent effects are ignored). The combination of these two flow mechanisms rigorously yields a composition, pressure and saturation dependent slippage factor. The pressure dependence arises from treating the gas as a real gas. The dynamic slippage derived from this formulation is found to be most applicable in reservoirs with permeabilities less than or equal to 0.01 md. The results from this study indicate that in reservoirs of this type, differences between recoveries after ten years of production using the dynamic slip described in this paper and constant slip approaches were as great as 10% depending on the initial gas saturation. If an economic production rate is considered, differences as great as 30 can be expected.

  8. Shaly sand formation evaluation in tight gas sands using electrochemical potential measurements

    Science.gov (United States)

    Sharma, M. M.; Jin, M.

    1991-08-01

    Equations are developed that directly relate the shaly conductivity to the electrochemical (membrane) potential (EP). The model is applied to both fully and partially saturated sands. The relationship between the resistivity index and the water saturation is also expressed in terms of a single membrane potential measurement. The Ep measured at different salinities are compared with model prediction using a single membrane potential measurement. Sigma (sub 0) versus Sigma (sub w) curves are then generated using the model equations and compared with measured curves. Experimental results are presented for electrochemical potential measurement made in the lab on 50 tight gs sand samples. It is shown that the measurements can be correlated with CEC although the CEC measured by grinding up the samples was always higher than that estimated from Ep measurements. The Ep measurements are combined with the equations for partial saturation developed in the report to obtain water saturations in a tight gas sand well. Through the example it is shown that it is possible to determine the water saturation in Shaly sands from one membrane potential measurement at a known salinity together with a set of resistivity logs. The results clearly demonstrate the applicability of the method as a practical procedure for Shaly sand information evaluation.

  9. Design and Implementation of Energized Fracture Treatment in Tight Gas Sands

    Energy Technology Data Exchange (ETDEWEB)

    Mukul Sharma; Kyle Friehauf

    2009-12-31

    , the minimum CO{sub 2} gas quality (volume % of gas) recommended is 30% for moderate differences between fracture and reservoir pressures (2900 psi reservoir, 5300 psi fracture). The minimum quality is reduced to 20% when the difference between pressures is larger, resulting in additional gas expansion in the invaded zone. Inlet fluid temperature, flow rate, and base viscosity did not have a large impact on fracture production. Finally, every stage of the fracturing treatment should be energized with a gas component to ensure high gas saturation in the invaded zone. A second, more general, sensitivity study was conducted. Simulations show that CO{sub 2} outperforms N{sub 2} as a fluid component because it has higher solubility in water at fracturing temperatures and pressures. In fact, all gas components with higher solubility in water will increase the fluid's ability to reduce damage in the invaded zone. Adding methanol to the fracturing solution can increase the solubility of CO{sub 2}. N{sub 2} should only be used if the gas leaks-off either during the creation of the fracture or during closure, resulting in gas going into the invaded zone. Experimental data is needed to determine if the gas phase leaks-off during the creation of the fracture. Simulations show that the bubbles in a fluid traveling across the face of a porous medium are not likely to attach to the surface of the rock, the filter cake, or penetrate far into the porous medium. In summary, this research has created the first compositional fracturing simulator, a useful tool to aid in energized fracture design. We have made several important and original conclusions about the best practices when using energized fluids in tight gas sands. The models and tools presented here may be used in the future to predict behavior of any multi-phase or multi-component fracturing fluid system.

  10. GRI: focusing on the evolving violent universe

    DEFF Research Database (Denmark)

    Knodlseder, J.; von Ballmoos, P.; Frontera, F.;

    2009-01-01

    The gamma-ray imager (GRI) is a novel mission concept that will provide an unprecedented sensitivity leap in the soft gamma-ray domain by using for the first time a focusing lens built of Laue diffracting crystals. The lens will cover an energy band from 200-1,300 keV with an effective area reach...... processes in the universe....

  11. Structural diagenesis in Upper Carboniferous tight gas sandstones. Lessons learned from the Piesberg analog study

    Energy Technology Data Exchange (ETDEWEB)

    Steindorf, P.; Hoehne, M.; Becker, S.; Hilgers, C. [RWTH Aachen Univ. (Germany). Energy and Mineral Resources Group (EMR); Koehrer, B. [Wintershall Holding GmbH, Barnstorf (Germany)

    2013-08-01

    Upper Carboniferous tight gas sandstone reservoirs in NW-Germany consist of thick successions of cyclothems. Our focus is the Westphalian D of the Piesberg quarry near Osnabrueck, which exposes cemented, faulted and jointed third-order coarse- to fine-grained sandstone cycles separated by anthracite coal seams. We characterize the rocks and the lateral variation of rock properties such as porosity to better constrain input data for reservoir modelling. Three cycles are exposed, each approximately 50 m thick. Rock types can be clearly distinguished by spectral gamma ray in the quarry. Sandstones are intensely compacted and cemented with quartz and generally characterized by low porosities < 8 % (Hepycnometry on plugs and cuttings). Porosities are secondary and mainly related to detrital carbonate dissolution. Around faults dissolution is higher and the porosities can increase to up to 25%. The normal faults show different throws in the quarry and bands of shale and coal have smeared into the fault at juxtaposed beds, which may result in compartments. They dominantly strike W-E and NNW-SSE, but subordinate NE-SW striking fault patterns are also present. Joints were analyzed in a 50 x 50 m section of the quarry wall using Lidar (Light detection and ranging) laser scanning, which allows the characterization of the lithology and quantitative measurement of bedding and fracture orientation data in inaccessible areas. NNE-SSW and W-E joint sets are accompanied by northeasterly and northwesterly striking sets. Around faults, fault planes and fractures are cemented with quartz veins, showing localized mass transport. Due to the intense cementation, the sandstones can reach uniaxial strengths of more than 100 MPa normal to bedding, and approximately 50 MPa parallel to bedding. Sandstone beds within and close to faults are leached by fluids, and their uniaxial strength is reduced by a factor of more than two. Our high resolution field data enables a better understanding of

  12. Characterization of an upper Permian tight gas reservoir. A multidisciplinary, multiscale analysis from the rotliegend, northern Germany

    Energy Technology Data Exchange (ETDEWEB)

    Antrett, Philipp [RWTH Aachen Univ. (Germany). Energy and Mineral Resources Group

    2013-06-01

    Outstanding Ph.D. thesis nominated for a Springer Theses Prize by the RWTH Aachen University, Germany. Uses various approaches and covers a broad range of disciplines. Integrated study, carried out on multiple scales with state of the art technical equipment, that only few laboratories can offer worldwide. ''The thesis of Philipp Antrett is focused on reservoir properties, petrography, lithofacies and sedimentology, core analysis and nanoporosity studies. It will be of major interest for colleagues involved in the exploration and production of tight gas reservoirs in Northern Europe and elsewhere.'' - Francois Roure, August 2012 This thesis describes a multidisciplinary, multiscale approach to the analysis of tight gas reservoirs. It focused initially on the facies architecture of a Permian tight gas field in the Southern Permian Basin (SPB), East Frisia, northern Germany. To improve field development, 3D seismic data, wireline and core data were compared to a reservoir analogue in the Panamint Valley, California, United States. In addition to the large scale approach, a work flow that investigates microporosity by combining Scanning Electron Microscopy-Broad Ion Beam (SEM-BIB) and optical microscopy was developed. For a better understanding of the depositional environment and reservoir rock distribution in the SPB, a sedimentary facies analysis of four cores from the tight gas field in East Frisia was compared to a second study area in northern central Germany. This study demonstrates that tight gas exploration and production requires multidisciplinary, multiscale approaches beyond standard seismic interpretation work flows to better understand the temporal and spatial evolution of these complex reservoirs.

  13. Stability of Fluorosurfactant Adsorption on Mineral Surface for Water Removal in Tight Gas Reservoirs

    Directory of Open Access Journals (Sweden)

    Lijun You

    2015-01-01

    Full Text Available Long-term effectiveness of rock wettability alteration for water removal during gas production from tight reservoir depends on the surfactant adsorption on the pore surface of a reservoir. This paper selected typical cationic fluorosurfactant FW-134 as an example and took advantage of Fourier transform infrared spectroscopy (FTIR, X-ray photoelectron spectroscopy (XPS, and atomic force microscope (AFM to investigate its adsorption stability on the rock mineral surface under the oscillation condition at high temperature for a long time. The experimental results indicate that the F element content on the sample surface increases obviously, the surface structure of fluorine-carbonization also undergoes a significant change, and the fluorine surfactant exhibits a good interfacial modification and wettability alteration ability due to its adsorption on the pore surface transforming the chemical structure of the original surface. The adsorption increases indistinctly with the concentration of over 0.05% due to a single layer adsorption structure and is mainly electrostatic adsorption because the chemical bonding between the fluorosurfactant and the rock mineral surface, the hydrogen bonding, is weak and inconspicuous.

  14. Study of the sealing performance of tubing adapters in gas-tight deep-sea water sampler

    Directory of Open Access Journals (Sweden)

    Haocai Huang

    2014-09-01

    Full Text Available Tubing adapter is a key connection device in Gas-Tight Deep-Sea Water Sampler (GTWS. The sealing performance of the tubing adapter directly affects the GTWS's overall gas tightness. Tubing adapters with good sealing performance can ensure the transmission of seawater samples without gas leakage and can be repeatedly used. However, the sealing performance of tubing adapters made of different materials was not studied sufficiently. With the research discussed in this paper, the materials match schemes of the tubing adapters were proposed. With non-linear finite element contact analysis and sea trials in the South China Sea, it is expected that the recommended materials match schemes not only meet the requirements of tubing adapters’ sealing performance but also provide the feasible options for the following research on tubing adapters in GTWS.

  15. GRI: focusing on the evolving violent Universe

    CERN Document Server

    Knödlseder, Jürgen; Frontera, Filippo; Bazzano, Angela; Christensen, Finn E; Hernanz, Margarida; Wunderer, Cornelia

    2007-01-01

    The Gamma-Ray Imager (GRI) is a novel mission concept that will provide an unprecedented sensitivity leap in the soft gamma-ray domain by using for the first time a focusing lens built of Laue diffracting crystals. The lens will cover an energy band from 200 - 1300 keV with an effective area reaching 600 cm2. It will be complemented by a single reflection multilayer coated mirror, extending the GRI energy band into the hard X-ray regime, down to ~10 keV. The concentrated photons will be collected by a position sensitive pixelised CZT stack detector. We estimate continuum sensitivities of better than 10^-7 ph/cm2/s/keV for a 100 ks exposure; the narrow line sensitivity will be better than 3 x 10^-6 ph/cm2/s for the same integration time. As focusing instrument, GRI will have an angular resolution of better than 30 arcsec within a field of view of roughly 5 arcmin - an unprecedented achievement in the gamma-ray domain. Owing to the large focal length of 100 m of the lens and the mirror, the optics and detector ...

  16. Petrophysical Analysis and Geographic Information System for San Juan Basin Tight Gas Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Martha Cather; Robert Lee; Robert Balch; Tom Engler; Roger Ruan; Shaojie Ma

    2008-10-01

    The primary goal of this project is to increase the availability and ease of access to critical data on the Mesaverde and Dakota tight gas reservoirs of the San Juan Basin. Secondary goals include tuning well log interpretations through integration of core, water chemistry and production analysis data to help identify bypassed pay zones; increased knowledge of permeability ratios and how they affect well drainage and thus infill drilling plans; improved time-depth correlations through regional mapping of sonic logs; and improved understanding of the variability of formation waters within the basin through spatial analysis of water chemistry data. The project will collect, integrate, and analyze a variety of petrophysical and well data concerning the Mesaverde and Dakota reservoirs of the San Juan Basin, with particular emphasis on data available in the areas defined as tight gas areas for purpose of FERC. A relational, geo-referenced database (a geographic information system, or GIS) will be created to archive this data. The information will be analyzed using neural networks, kriging, and other statistical interpolation/extrapolation techniques to fine-tune regional well log interpretations, improve pay zone recognition from old logs or cased-hole logs, determine permeability ratios, and also to analyze water chemistries and compatibilities within the study area. This single-phase project will be accomplished through four major tasks: Data Collection, Data Integration, Data Analysis, and User Interface Design. Data will be extracted from existing databases as well as paper records, then cleaned and integrated into a single GIS database. Once the data warehouse is built, several methods of data analysis will be used both to improve pay zone recognition in single wells, and to extrapolate a variety of petrophysical properties on a regional basis. A user interface will provide tools to make the data and results of the study accessible and useful. The final deliverable

  17. Tectonic Fractures in Tight Gas Sandstones of the Upper Triassic Xujiahe Formation in the Western Sichuan Basin,China

    Institute of Scientific and Technical Information of China (English)

    ZENG Lianbo; LI Yuegang

    2010-01-01

    The western Sichuan Basin,which is located at the front of the Longmen Mountains in the west of Sichuan Province,China,is a foreland basin formed in the Late Triassic.The Upper Triassic Xujiahe Formation is a tight gas sandstone reservoir with low porosity and ultra-low permeability,whose gas accumulation and production are controlled by well-developed fracture zones.There are mainly three types of fractures developed in the Upper Triassic tight gas sandstones,namely tectonic fractures,diagenetic fractures and overpressure-related fractures,of which high-angle tectonic fractures are the most important.The tectonic fractures can be classified into four sets,i.e.,N-S-,NE-,E-W-and NW-striking fractures.In addition,there are a number of approximately horizontal shear fractures in some of the medium-grained sandstones and grit stones nearby the thrusts or slip layers.Tectonic fractures were mainly formed at the end of the Triassic,the end of the Cretaceous and the end of the Neogene-Early Pleistocene.The development degree of tectonic fractures was controlled by lithology,thickness,structure,stress and fluid pressure.Overpressure makes not only the rock shear strength decrease,but also the stress state change from compression to tension.Thus,tensional fractures can be formed in fold-thrust belts.Tectonic fractures are mainly developed along the NE-and N-S-striking structural belts,and are the important storage space and the principal flow channels in the tight gas sandstone.The porosity of fractures here is 28.4% of the gross reservoir porosity,and the permeability of fractures being two or three grades higher than that of the matrix pores.Four sets of high-angle tectonic fractures and horizontal shear fractures formed a good network system and controlled the distribution and production of gas in the tight sandstones.

  18. 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

  19. Tight gas reservoir simulation: Modeling discrete irregular strata-bound fracture network flow, including dynamic recharge from the matrix

    Energy Technology Data Exchange (ETDEWEB)

    McKoy, M.L., Sams, W.N.

    1997-10-01

    The US Department of Energy, Federal Energy Technology Center, has sponsored a project to simulate the behavior of tight, fractured, strata-bound gas reservoirs that arise from irregular discontinuous, or clustered networks of fractures. New FORTRAN codes have been developed to generate fracture networks, or simulate reservoir drainage/recharge, and to plot the fracture networks and reservoirs pressures. Ancillary codes assist with raw data analysis.

  20. Preparation of gas-tight strontium-doped lanthanum cobaltate by an aqueous sol-gel process

    NARCIS (Netherlands)

    Chen, C.H.; Kruidhof, H.; Bouwmeester, H.J.M.; Burggraaf, A.J.

    1996-01-01

    Gas-tight dense membranes of highly Sr-doped LaCoO3 (such as the composition La0.3Sr0.7CoO3 chosen in this study) are difficult to prepare using usual synthesis processes. This report presents an aqueous sol-gel route using metal acetates as precursors to achieve this goal. Hydrogen peroxide and amm

  1. A fast simulation tool for evaluation of novel well stimulation techniques for tight gas reservoirs

    NARCIS (Netherlands)

    Egberts, P.J.P.; Peters, E.

    2015-01-01

    For stimulation of tight fields, alternatives to hydraulic fracturing based on hydraulic jetting are becoming available. With hydraulic jetting many (10 to 20) laterals can be created in a (sub-) vertical well. The laterals are 100 to 200 m long, typically 4 laterals are applied with a small

  2. Numerical simulation of the environmental impact of hydraulic fracturing of tight/shale gas reservoirs on near-surface ground water: background, base cases, shallow reservoirs, short-term gas and water transport

    Science.gov (United States)

    Researchers examined gas and water transport between a deep tight shale gas reservoir and a shallow overlying aquifer in the two years following hydraulic fracturing, assuming a pre-existing connecting pathway.

  3. Development of a data-driven forecasting tool for hydraulically fractured, horizontal wells in tight-gas sands

    Science.gov (United States)

    Kulga, B.; Artun, E.; Ertekin, T.

    2017-06-01

    Tight-gas sand reservoirs are considered to be one of the major unconventional resources. Due to the strong heterogeneity and very low permeability of the formation, and the complexity of well trajectories with multiple hydraulic fractures; there are challenges associated with performance forecasting and optimum exploitation of these resources using conventional modeling approaches. In this study, it is aimed to develop a data-driven forecasting tool for tight-gas sands, which are based on artificial neural networks that can complement the physics-driven modeling approach, namely numerical-simulation models. The tool is designed to predict the horizontal-well performance as a proxy to the numerical model, once the initial conditions, operational parameters, reservoir/hydraulic-fracture characteristics are provided. The data-driven model, that the forecasting tool is based on, is validated with blind cases by estimating the cumulative gas production after 10 years with an average error of 3.2%. A graphical-user-interface application is developed that allows the practicing engineer to use the developed tool in a practical manner by visualizing estimated performance for a given reservoir within a fraction of a second. Practicality of the tool is demonstrated with a case study for the Williams Fork Formation by assessing the performance of various well designs and by incorporating known uncertainties through Monte Carlo simulation. P10, P50 and P90 estimates of the horizontal-well performance are quickly obtained within acceptable accuracy levels.

  4. Diagenetic fluids evolution and genetic mechanism of tight sandstone gas reservoirs in Upper Triassic Xujiahe Formation in Sichuan Basin, China

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The reservoirs of the Upper Triassic Xujiahe Formation in Sichuan Basin have the characteristics of low compositional maturity, low contents of cements and medium textural maturity. The general physical properties of the reservoirs are poor, with low porosity and low permeability, and there are only a few reservoirs with medium porosity and low permeability in local areas. Based on the diagenetic mineral association, a diagenetic sequence of cements is established: early calcites (or micrite siderites) →first quartz overgrowth→chlorite coatings→dissolution of feldspars and debris→chlorite linings→ second quartz overgrowth (quartz widen or filled in remain intergranular pores and solution pores)→dissolution→third quartz overgrowth (quartz filled in intergranular and intragranular solution pores)→intergrowth (ferro) calcites→dolomites→ferro (calcites) dolomites→later dissolution→veins of quartz and calcites formation. Mechanical compaction is the main factor in making the reservoirs tight in the basin, followed by the second and third quartz overgrowth. In a long-term closed system, only feld-spars and some lithic fragments are dissolved by diagenetic fluids, while intergranular cements such as quartz and calcit are not dissolved and thus have little influence on the porosity of the Xujiahe Formation. This is the third factor that may have kept the sandstones of Xujiahe Formation tight finally. The hydrocarbon was extensively generated from organic materials after the second quartz overgrowth, and selectively entered favorable reservoirs to form tight sandstone gas reservoirs.

  5. Diagenetic fluids evolution and genetic mechanism of tight sandstone gas reservoirs in Upper Triassic Xujiahe Formation in Sichuan Basin, China

    Institute of Scientific and Technical Information of China (English)

    ZHU RuKai; ZOU CaiNeng; ZHANG Nai; WANG XueSong; CHENG Rong; LIU LiuHong; ZHOU ChuanMin; SONG LiHong

    2008-01-01

    The reservoirs of the Upper Triassic Xujiahe Formation in Sichuan Basin have the characteristics of low compositional maturity, low contents of cements and medium textural maturity.The general physical properties of the reservoirs are poor, with low porosity and low permeability, and there are only a few reservoirs with medium porosity and low permeability in local areas.Based on the diagenetic mineral association, a diagenetic sequence of cements is established: early calcites (or micrite siderites)→ first quartz overgrowth→chlorite coatings→dissolution of feldspars and debris→chlorite linings→ second quartz overgrowth (quartz widen or filled in remain intergranular pores and solution pores→ dissolution→third quartz overgrowth (quartz filled in intergranular and intragranular solution pores)→ intergrowth (ferro) calcites→dolomites→ferro (calcites) dolomites→later dissolution→veins of quartz and calcites formation.Mechanical compaction is the main factor in making the reservoirs tight in the basin, followed by the second and third quartz overgrowth.In a long-term closed system, only feldspars and some lithic fragments are dissolved by diagenetic fluids, while intergranular cements such as quartz and calcit are not dissolved and thus have little influence on the porosity of the Xujiahe Formation.This is the third factor that may have kept the sandstones of Xujiahe Formation tight finally.The hydrocarbon was extensively generated from organic materials after the second quartz overgrowth, and selectively entered favorable reservoirs to form tight sandstone gas reservoirs.

  6. Energy Return on Energy Invested for Tight Gas Wells in the Appalachian Basin, United States of America

    Directory of Open Access Journals (Sweden)

    Bryan Sell

    2011-10-01

    Full Text Available The energy cost of drilling a natural gas well has never been publicly addressed in terms of the actual fuels and energy required to generate the physical materials consumed in construction. Part of the reason for this is that drilling practices are typically regarded as proprietary; hence the required information is difficult to obtain. We propose that conventional tight gas wells that have marginal production characteristics provide a baseline for energy return on energy invested (EROI analyses. To develop an understanding of baseline energy requirements for natural gas extraction, we examined production from a mature shallow gas field composed of vertical wells in Pennsylvania and materials used in the drilling and completion of individual wells. The data were derived from state maintained databases and reports, personal experience as a production geologist, personal interviews with industry representatives, and literature sources. We examined only the “upstream” energy cost of providing gas and provide a minimal estimate of energy cost because of uncertainty about some inputs. Of the materials examined, steel and diesel fuel accounted for more than two-thirds of the energy cost for well construction. Average energy cost per foot for a tight gas well in Indiana County is 0.59 GJ per foot. Available production data for this natural gas play was used to calculate energy return on energy invested ratios (EROI between 67:1 and 120:1, which depends mostly on the amount of materials consumed, drilling time, and highly variable production. Accounting for such inputs as chemicals used in well treatment, materials used to construct drill bits and drill pipe, post-gathering pipeline construction, and well completion maintenance would decrease EROI by an unknown amount. This study provides energy constraints at the single-well scale for the energy requirements for drilling in geologically simple systems. The energy and monetary costs of wells from

  7. 低渗致密气藏、凝析气藏开发难点与对策%Difficulties and Measures for Development of Low Permeability Tight Gas Reservoirs and Condensate Gas Reservoirs

    Institute of Scientific and Technical Information of China (English)

    李士伦; 孙雷; 杜建芬

    2004-01-01

    Low permeability tight gas reservoirs and condensate gas reservoirs account for a rather high proportion ofdomestic gas reserves, but many of them have low productivity. So it is significant to develop these reservoirs effi-ciently for continuous and stable development of China′s petroleum industry. Around the problems of the developmentof deep low permeability tight gas reservoirs and condensate gas reservoirs, this paper makes an analysis on the geo-logic and development characteristics of these reservoirs and presents ten proper technologies. Finally, five technicalmeasures for the development of such gas reservoirs are proposed in detail. These are deep fracturing technology,treatment technology of accumulated liquids in condensate gas well and near well bore, gas injection technology whenthe formation pressure is lower than the maximum condensate pressure, phase behavior analysis technology in porousmedia of low permeability tight condensate gas reservoir and other gas reservoir engineering technologies.

  8. Advancing New 3D Seismic Interpretation Methods for Exploration and Development of Fractured Tight Gas Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    James Reeves

    2005-01-31

    In a study funded by the U.S. Department of Energy and GeoSpectrum, Inc., new P-wave 3D seismic interpretation methods to characterize fractured gas reservoirs are developed. A data driven exploratory approach is used to determine empirical relationships for reservoir properties. Fractures are predicted using seismic lineament mapping through a series of horizon and time slices in the reservoir zone. A seismic lineament is a linear feature seen in a slice through the seismic volume that has negligible vertical offset. We interpret that in regions of high seismic lineament density there is a greater likelihood of fractured reservoir. Seismic AVO attributes are developed to map brittle reservoir rock (low clay) and gas content. Brittle rocks are interpreted to be more fractured when seismic lineaments are present. The most important attribute developed in this study is the gas sensitive phase gradient (a new AVO attribute), as reservoir fractures may provide a plumbing system for both water and gas. Success is obtained when economic gas and oil discoveries are found. In a gas field previously plagued with poor drilling results, four new wells were spotted using the new methodology and recently drilled. The wells have estimated best of 12-months production indicators of 2106, 1652, 941, and 227 MCFGPD. The latter well was drilled in a region of swarming seismic lineaments but has poor gas sensitive phase gradient (AVO) and clay volume attributes. GeoSpectrum advised the unit operators that this location did not appear to have significant Lower Dakota gas before the well was drilled. The other three wells are considered good wells in this part of the basin and among the best wells in the area. These new drilling results have nearly doubled the gas production and the value of the field. The interpretation method is ready for commercialization and gas exploration and development. The new technology is adaptable to conventional lower cost 3D seismic surveys.

  9. Relations between seismic signals and reservoir properties of tight gas reservoirs in North Germany (Permian Rotliegend sandstones)

    Energy Technology Data Exchange (ETDEWEB)

    Abram, P.; Gaupp, R. [Friedrich-Schiller-Univ., Inst. of Geosciences, Jena (Germany)

    2006-07-01

    Tight gas reservoirs in North Germany consist of sandstones of eolian, fluvial and lacustrine origin in 3,5-5 km (11500-16500 ft) depth. Different mechanical compaction, mineral authigenesis and cement dissolution resulted in proximate zones with good and poor reservoir qualities. Some regions with moderate porosities provide very low permeabilities whereas regions with low porosities can offer profitable permeabilities within comparable depositional lithologies. Therefore deep gas exploration is very dependent on predictive reservoir information from 3D seismic signals due to the locally varying reservoir qualities. A recent study succeeded in subdividing a tight gas reservoir into parts with good, moderate and poor qualities and to predict reservoir properties for parts without well information. For this purpose 3D seismic signals had been classified with Neural Network techniques based on amplitude, shape and lateral coherency of seismic traces. The unsupervised classification (Kohonen map) with a single layer of neurons generated classes, which are representative for seismic wave and rock properties at the reservoir level. The geographical distribution of these seismic facies classes correlates to locations of wells with either good or poor reservoir qualities and to zones of specific petrophysical, petrological and sedimentological data. Wells with mean permeabilities between 9-50 mD are located within the red areas (seismic classes 6 and 7), while wells with mean permeabilities below 0,5 mD are all found in blue and green areas (seismic classes 1 till 4). Furthermore, the red zone in the East corresponds to the eastern part of a production field of high transmissivity. The main reason for the strong reduction in mean permeability was found to be a specific morphotype of authigenic illite which occurs almost only in the blue and green zones. This paper outlines SOME theories and results of the doctoral thesis.

  10. Assessment of potential shale oil and tight sandstone gas resources of the Assam, Bombay, Cauvery, and Krishna-Godavari Provinces, India, 2013

    Science.gov (United States)

    Klett, Timothy R.; Schenk, Christopher J.; Wandrey, Craig J.; Brownfield, Michael E.; Charpentier, Ronald R.; Tennyson, Marilyn E.; Gautier, Donald L.

    2014-01-01

    Using a well performance-based geologic assessment methodology, the U.S. Geological Survey estimated a technically recoverable mean volume of 62 million barrels of oil in shale oil reservoirs, and more than 3,700 billion cubic feet of gas in tight sandstone gas reservoirs in the Bombay and Krishna-Godavari Provinces of India. The term “provinces” refer to geologically defined units assessed by the USGS for the purposes of this report and carries no political or diplomatic connotation. Shale oil and tight sandstone gas reservoirs were evaluated in the Assam and Cauvery Provinces, but these reservoirs were not quantitatively assessed.

  11. Utilization of substrates in biogas plants with and without a gas-tight fermentation remainder deposit; Substratausnutzung in Biogasanlagen mit und ohne gasdichtem Gaerrestbehaelter

    Energy Technology Data Exchange (ETDEWEB)

    Engler, Nils [Rostock Univ. (Germany). Agrar- und Umweltwissenschaftliche Fakultaet; Weissbach, Friedrich; Wesseling, Stefanie

    2011-07-01

    In the case of an incomplete utilization of substrates in the biogas production, the greenhouse gas methane can be released into the atmosphere during the subsequent storage of the digestate. Recent legal restrictions require a gas-tight coverage of the entire fermentation remainder deposit. Under this aspect, the authors of the contribution under consideration investigate the utilization of the substrate in two identical 500 kW biogas plants with and without a gas-tight fermentation remainder deposit using a mixture of maize silage and cow manure. Due to the use of the gas-tight fermentation remainder deposit, this substrate mixture can be exploited better by about 3 %. This additional yield is applied to unheated fermentation remainder deposit for the summer. The amount of methane which thereby is not released into the environment is significantly lower.

  12. Engineering-support services for the DOE/GRI coal-gasification research program. Monthly technical progress report, 27 February-26 March 1982

    Energy Technology Data Exchange (ETDEWEB)

    Bostwick, L.E.; Ethridge, T.R.; Starr, D.W.; Hubbard, D.A.; Koneru, P.B.; Smith, M.R.; Ward, W.E.; Wong, E.W.; Zeis, L.A.

    1982-04-01

    During March, Kellogg continued to monitor operations at BI-GAS, Westinghouse and IGT Peatgas. Test runs monitored and reported were: BI-Gas tests G-18A and G-18B; Westinghouse PDU test: TP-032-1, and CFSF test TP-M003; Peatgas pilot plant test No. 5 at IGT. Kellog personnel briefed the Gas Research Institute (GRI) Project Advisors in regard to recent tasks and attended the Westinghouse briefing for GRI. Meetings of the DOE/GRI Joint Operating Committee were attended to discuss the Data Base Evaluation of Single-Stage Peat Gasification and the Joint Program Brochure. Kellogg proceeded to finalize the data base evaluation report and to institute necessary changes in the brochure.

  13. Sedimentary facies reconstruction and kinematic restoration of tight gas fields. Studies from the Upper Permian in Northwestern Germany

    Energy Technology Data Exchange (ETDEWEB)

    Vackiner, Anna Alexandra [RWTH Aachen Univ. (Germany). Energy and Mineral Resources Group

    2013-11-01

    Outstanding Ph.D. thesis nominated for a Springer Theses Prize by the RWTH Aachen University, Germany. A multi-disciplinary study with application in the oil and gas industry. Approx. 60 color figures. The thesis of Anna Alexandra Vackiner focuses on the geometric architecture and tectonic evolution of the Permian series, combining seismic interpretation (3D block), field studies in an analogue basin (Panamint Valley in California), as well as 2D restoration of representative cross sections through time in order to illustrate the complex interaction between multiphase extension, inversion and salt diapirism. It will be of major interest for exploration geologists involved in tectonically complex areas. - Francois Roure, August 2012 This thesis improves the understanding and localization of the Upper Rotliegend II tight gas reservoir rock facies. It provides insights into the detailed Upper Rotliegend II palaeo-topography and local tectonically induced sediment thickness changes prior to a multi-phase tectonic overprinting. The research presented in this study further focuses on the tectonically induced synsedimentary facies distribution in transtensional continental settings on the basis of a comparison with a modern field analogue, which enables a detailed analysis of the reservoir rock's distribution and its properties. The study is rounded off with an analysis of the influence of the multiphase tectonic overprinting on the mature Upper Rotliegend II reservoir rocks.

  14. Naturally fractured tight gas reservoir detection optimization. Annual report, September 1993--September 1994

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-10-01

    This report is an annual summarization of an ongoing research in the field of modeling and detecting naturally fractured gas reservoirs. The current research is in the Piceance basin of Western Colorado. The aim is to use existing information to determine the most optimal zone or area of fracturing using a unique reaction-transport-mechanical (RTM) numerical basin model. The RTM model will then subsequently help map subsurface lateral and vertical fracture geometries. The base collection techniques include in-situ fracture data, remote sensing, aeromagnetics, 2-D seismic, and regional geologic interpretations. Once identified, high resolution airborne and spaceborne imagery will be used to verify the RTM model by comparing surficial fractures. If this imagery agrees with the model data, then a further investigation using a three-dimensional seismic survey component will be added. This report presents an overview of the Piceance Creek basin and then reviews work in the Parachute and Rulison fields and the results of the RTM models in these fields.

  15. Sedimentary Characterization of the Upper Paleozoic Coal-Bearing Tight Sand Strata, Daniudi Gas Field, Ordos Basin, China

    Institute of Scientific and Technical Information of China (English)

    Wei Du; Zaixing Jiang; Qing Li; Ying Zhang

    2016-01-01

    The coal-bearing strata of the Upper Paleozoic (from the Taiyuan Formation to the low-er member of the Shanxi Formation) are the most important units that have high gas production in the Daniudi gas field, which is a typical tight-sandstone reservoir with high heterogeneity in the Ordos Ba-sin, China. Based on an integrated investigation of well logs, cores, SEM and 3-D seismic data, we de-lineated the sedimentary facies of the coal-bearing strata and divided the succession into sequenced stratigraphic units of different depositional systems. A sedimentary hiatus was documented for the first time in the study area and forms the sequence boundary between the Lower Pennsylvanian Car-boniferous Taiyuan Formation (Ct1) and the Upper Pennsylvanian Carboniferous Taiyuan Formation (Ct2). The coal-bearing strata in Ct1 are indicative of a barrier coastal deposition system. Tidal chan-nels are identified by their fine-grained, cross-stratified character. The sands in the tidal channels are well sorted, and the quartz content is above 95%. The coalbed located beside the sandstone is thought to be a lagoon. Gas-bearing, coarse-grained sandstone in the coal-bearing strata spanning from the Ct2 to the lower members of the Shanxi Formation (P1s) is interpreted as a fluvial-dominated braided del-ta that is divided into four third-order sequences. The coal-bearing strata are composed of sandstone, mudstone and coalbed from base to top in each sequence. Braided-river deposits form the lowstand system tract (LST) within each sequence. A shelf and lake depositional environment containing dark gray mudstone forms the transgressive systems tract (TST). The highstand systems tract (HST) depo-sits form the swamp coalbed in each sequence.

  16. The RealGas and RealGasH2O Options of the TOUGH+ Code for the Simulation of Coupled Fluid and Heat Flow in Tight/Shale Gas Systems

    Energy Technology Data Exchange (ETDEWEB)

    Moridis, George; Freeman, Craig

    2013-09-30

    We developed two new EOS additions to the TOUGH+ family of codes, the RealGasH2O and RealGas . The RealGasH2O EOS option describes the non-isothermal two-phase flow of water and a real gas mixture in gas reservoirs, with a particular focus in ultra-tight (such as tight-sand and shale gas) reservoirs. The gas mixture is treated as either a single-pseudo-component having a fixed composition, or as a multicomponent system composed of up to 9 individual real gases. The RealGas option has the same general capabilities, but does not include water, thus describing a single-phase, dry-gas system. In addition to the standard capabilities of all members of the TOUGH+ family of codes (fully-implicit, compositional simulators using both structured and unstructured grids), the capabilities of the two codes include: coupled flow and thermal effects in porous and/or fractured media, real gas behavior, inertial (Klinkenberg) effects, full micro-flow treatment, Darcy and non-Darcy flow through the matrix and fractures of fractured media, single- and multi-component gas sorption onto the grains of the porous media following several isotherm options, discrete and fracture representation, complex matrix-fracture relationships, and porosity-permeability dependence on pressure changes. The two options allow the study of flow and transport of fluids and heat over a wide range of time frames and spatial scales not only in gas reservoirs, but also in problems of geologic storage of greenhouse gas mixtures, and of geothermal reservoirs with multi-component condensable (H2O and CH4) and non-condensable gas mixtures. The codes are verified against available analytical and semi-analytical solutions. Their capabilities are demonstrated in a series of problems of increasing complexity, ranging from isothermal flow in simpler 1D and 2D conventional gas reservoirs, to non-isothermal gas flow in 3D fractured shale gas reservoirs involving 4 types of fractures, micro-flow, non-Darcy flow and gas

  17. Improving the Availability and Delivery of Critical Information for Tight Gas Resource Development in the Appalachian Basin

    Energy Technology Data Exchange (ETDEWEB)

    Mary Behling; Susan Pool; Douglas Patchen; John Harper

    2008-12-31

    To encourage, facilitate and accelerate the development of tight gas reservoirs in the Appalachian basin, the geological surveys in Pennsylvania and West Virginia collected widely dispersed data on five gas plays and formatted these data into a large database that can be accessed by individual well or by play. The database and delivery system that were developed can be applied to any of the 30 gas plays that have been defined in the basin, but for this project, data compilation was restricted to the following: the Mississippian-Devonian Berea/Murrysville sandstone play and the Upper Devonian Venango, Bradford and Elk sandstone plays in Pennsylvania and West Virginia; and the 'Clinton'/Medina sandstone play in northwestern Pennsylvania. In addition, some data were collected on the Tuscarora Sandstone play in West Virginia, which is the lateral equivalent of the Medina Sandstone in Pennsylvania. Modern geophysical logs are the most common and cost-effective tools for evaluating reservoirs. Therefore, all of the well logs in the libraries of the two surveys from wells that had penetrated the key plays were scanned, generating nearly 75,000 scanned e-log files from more than 40,000 wells. A standard file-naming convention for scanned logs was developed, which includes the well API number, log curve type(s) scanned, and the availability of log analyses or half-scale logs. In addition to well logs, other types of documents were scanned, including core data (descriptions, analyses, porosity-permeability cross-plots), figures from relevant chapters of the Atlas of Major Appalachian Gas Plays, selected figures from survey publications, and information from unpublished reports and student theses and dissertations. Monthly and annual production data from 1979 to 2007 for West Virginia wells in these plays are available as well. The final database also includes digitized logs from more than 800 wells, sample descriptions from more than 550 wells, more than 600

  18. Integrated techniques for rapid and highly-efficient development and production of ultra-deep tight sand gas reservoirs of Keshen 8 Block in the Tarim Basin

    Directory of Open Access Journals (Sweden)

    Tongwen Jiang

    2017-01-01

    Full Text Available The unusually ultra-deep and ultra-high-pressure gas reservoirs in the Keshen 8 Block on the Kelasu structural belt of the Tarim Basin are also featured by high temperature, well-developed fault fissures, huge thickness, tight matrix, complex oil–water distribution, etc., which brings about great difficulties to reserves evaluation and further development. In view of this, an overall study was made on the fine description of reservoir fractures and their seepage mechanism, technical problems were being tackled on seismic data processing and interpretation of complex and high & steep structural zones, optimal development design, safe & rapid drilling and completion wells, reservoir stimulation, dynamic monitoring, etc. to promote the development level of such ultra-deep tight gas reservoirs, and 22 complete sets of specific techniques were formulated in the fields of high-efficiency well spacing, safe and fast drilling, recovery enhancement by well completion transformation, efficient development of optimization design, and so on. Through the technical progress and innovative management of integrated exploration & development, reserves evaluation and productivity construction have been completed on the Keshen 8 Block in the last three years of the 12th Five-Year Plan period (2011–2015, as a result, rapid and high-efficiency productivity construction is realized, and a new area is explored in the development of ultra-deep and ultra-high-pressure fractured tight sand gas reservoirs. This study is of great reference to the development of similar gas reservoirs at home and abroad.

  19. Evidence for very tight sequestration of BTEX compounds in manufactured gas plant soils based on selective supercritical fluid extraction and soil/water partitioning.

    Science.gov (United States)

    Hawthorne, Steven B; Miller, David J

    2003-08-15

    Benzene, toluene, ethylbenzene, o-, m-, and p-xylenes (BTEX), and polycyclic aromatic hydrocarbons (PAHs) were extracted from eight manufactured gas plant (MGP) soils from sites that had been abandoned for several decades. Supercritical fluid extraction (SFE) with pure carbon dioxide demonstrated the presence of BTEX compounds that were highly sequestered in both coal gas and oil gas MGP soils and soots. Benzene was generally the slowest compound to extract from all samples and was even more difficult to extract than most two- to five-ring PAHs found on the same samples. Since the solubility of benzene in carbon dioxide is 2-5 orders of magnitude higher than the solubilities of PAHs, these results demonstrate that benzene was more tightly sequestered than toluene, ethylbenzene, xylenes, or the multi-ring PAHs. Additional evidence for very tight binding was based on the fact that BTEX concentrations determined using either SFE or with methylene chloride sonication were much higher than those obtained by the U.S. EPA purge-and-trap method, especially for benzene (whose concentration was underestimated by as much as 1000-fold by the EPA method). However, soil/water desorption showed little benzene mobility, and Kd values for benzene were 1-2 orders of magnitude higher than those calculated based on literature sorption K(OC) values. These results indicate that environmentally relevant concentrations of benzene may be better represented by mild extraction methods than by methods capable of extracting tightly bound benzene.

  20. Research on Pressure Tight Sampling Technique of Deep-Sea Shallow Sediment——A New Approach to Gas Hydrate Investigation

    Institute of Scientific and Technical Information of China (English)

    CHEN Ying; QIN Hua-wei; LI Shi-lun; GU Lin-yi; PAN Hua-chen

    2006-01-01

    Analyzed and calculated are pressure changes and body deformation of the sample inside of the corer in the process of sampling of deep-sea shallow sediment with a non-piston corer for gas hydrate investigation. Two conclusions are drawn: (1) the stress increments associated with the corer through the sampling process do not affect the stabilization of the gas hydrate; (2) the body deformation of the sample is serious and the "incremental filling ratio" (IFR) is less than unit. For taking samples with in-situ pressure and structure, combining with the design theories of the pressure tight corer, we have designed a kind of piston corer, named the gas hydrate pressure tight piston corer. Several tests on the sea have been conducted. Test results indicate that the piston corer has a good ability of taking sediment samples on the seafloor and maintaining their original in-situ pressure, meeting the requirement of exploration of gas hydrate in deep-sea shallow sediment layers.

  1. Analysis on the Compliance with GRI Guidelines and the Information Disclosed by Japanese Companies

    OpenAIRE

    Kawahara, Naoko; Irie, Noriko

    2015-01-01

    [Abstract] Japanese companies do not comply with the Global Reporting Initiatives (GRI)'s Sustainability Guidelines as much as other developed countries, and their compliance levels are lower among developed countries. This study overviewed the characteristics of Japanese GRI compliance and analysed 15 Japanese listed companies on the information of their corporate sustainability reports in which they comply with the GRI version 3.1 Guidelines. The possible correlation between GRI compliance ...

  2. Using a CAI Network for Statewide Remediation: GRI in South Carolina.

    Science.gov (United States)

    Rumford, John

    1988-01-01

    Describes South Carolina's Governor's Remediation Initiative (GRI), an instructional management system that links diagnostic tests and teaching modules for use by high school mathematics and reading laboratories. (TW)

  3. Hydraulic fracturing research in east Texas; Third GRI staged field experiment

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, B.M. (S.A. Holditch and Associates, Inc. (US))

    1992-01-01

    This paper presents results from results from research conducted on the third Gas Research inst. (GRI) staged field experiment (SFE) well. Research well SFE No. 3 was drilled as part of a field-based research program conducted in east Texas during the past 7 years. Most of the work before SFE No. 3 involved the Travis Peak formation; however, the Cotton Valley sandstone was the primary research target for this well. SFE no. 3 is the last in a series of research wells planned for east Texas. A fourth SFE is being conducted in the Frontier formation of southwestern Wyoming. Data on SFE wells are collected from whole cores, openhole geophysical logs, in-situ stress measurements, production and pressure-transient tests, fracture stimulation treatments, fracture-diagnostic measurements, and postfracture performance tests. Test data then are analyzed by research scientists, geologists, and engineers to describe the reservoir and hydraulic fracture fully.

  4. Reeling of tight fit pipe

    NARCIS (Netherlands)

    Focke, E.S.

    2007-01-01

    If it would be possible to install Tight Fit Pipe by means of reeling, it would be an attractive new option for the exploitation of offshore oil and gas fields containing corrosive hydrocarbons. Tight Fit Pipe is a mechanically bonded double walled pipe where a corrosion resistant alloy liner pipe

  5. Research on the Stress Sensitivity of Tight Gas Reservoir%致密气藏应力敏感性研究

    Institute of Scientific and Technical Information of China (English)

    袁浩伟; 陈昉; 刘梦云

    2016-01-01

    Stress sensitivity phenomenon is the key factor to restrict the exploitation of tight gas currently, so, combined the current research result on stress sensitivity with analysis of affecting factors, an experimental mode for studying the influ-ence of stress sensitivity on permeability and porosity has been established. Results showed that the affecting factors of stress sensitivity are divided into internal and external factors, but the internal factors include rock component, compres-sion coefficient of rock, water saturation, natural fracture, start-up pressure and reservoir temperature, etc; external fac-tors include the working fluid invision, repeated pressure, pressure time and so on. The experimental method, keeping the external pressure constant and the internal pressure changed to evalute the stress sensitivity of tight gas, showed that no strong stress sensitivity in tight gas reservoir, the permeability and porosity are decreased with the drop of pore fluid pres-sure in the reservoir, and the loss of permeability and porosity can not be fully recovered. The lower the permeability of tight gas reservoir, the weaker the sensitivity of permeability. Porosity sensitivity is generally weak, and basically can be ignored. Take the Sulige gas field as an example, the effect of stress sensitivity on the productivity prediction of tight gas reservoir has been studied, the results indicated that the influlence of stress sensitivity on gas well productivity when relea-sing pressure is much greater than that of pressure controlled production.%应力敏感现象是目前制约致密气开采的关键因素,结合目前应力敏感研究的前沿结果,分析应力敏感的影响因素,建立实验模型,并研究应力敏感对渗透率和孔隙度的影响结果。结果表明,应力敏感性的影响因素分为内因和外因,内因包括岩石组分、岩石压缩系数、含水饱和度、天然裂缝、启动压力和储层温度等;外因包括

  6. Investigation on the permeability characteristics of bedded salt rocks and the tightness of natural gas caverns in such formations

    NARCIS (Netherlands)

    Liu, Wei; Muhammad, N.; Chen, Jie; Spiers, C.J.; Peach, C.J.; Deyi, Jiang; Li, Yinping

    In China, the salt formations close to the lower reaches of the large natural gas routes and the main gas consuming regions are all bedded structures. The presences of non-halite or low-halite mudstone interlayers and interfaces (salt-interlayer) in these bedded salt formations increase the concern

  7. A realistic transport model with pressure dependent parameters for gas flow in tight porous media with application to determining shale rock properties

    CERN Document Server

    Ali, Iftikhar

    2016-01-01

    Shale gas recovery has seen a major boom in recent years due to the increasing global energy demands; but the extraction technologies are very expensive. It is therefore important to develop realistic transport modelling and simulation methods, for porous rocks and porous media, that can compliment the field work. Here, a new nonlinear transport model for single phase gas flow in tight porous media is derived, incorporating many important physical processes that occur in such porous systems: continuous flow, transition flow, slip flow, Knudsen diffusion, adsorption and desorption in to and out of the rock material, and a correction for high flow rates (turbulence). This produces a nonlinear advection-diffusion type of partial differential equation (PDE) with pressure dependent model parameters and associated compressibility coefficients, and highly nonlinear apparent convective flux (velocity) and apparent diffusivity. An important application is to the determination of shale rock properties, such as porosity...

  8. The characteristics of gravity and magnetic fields and the distribution of tight sandstone gas in the eastern Ordos Basin, China

    Science.gov (United States)

    Yuan, Bingqiang; Zhang, Huaan; Zhang, Chunguan; Xu, Haihong; Yan, Yunkui

    2016-04-01

    In order to perform gas exploration and determine the distribution pattern of gas in the Yanchang Oil Field in the eastern part of the North Shaanxi Slope, Ordos Basin, China, gravity and magnetic survey data were systemically collated, processed and interpreted in combination with the drilling data and recent seismic data. The genesis of gravity and magnetic anomalies and the relationship between the characteristics of the gravity and magnetic fields and known gas distribution were explored in order to predict the favourable exploration targets for gas. Gravity anomalies resulted both from the lateral variation in density of the basement rock and lateral lithologic transformation in the sedimentary cover. The regional magnetic anomalies were mainly caused by the basement metamorphic rocks and the residual magnetic anomalies may reflect the amount and general location of the volcanic materials in the overlying strata. The residual gravity and magnetic anomalies generated by high-density sandstone and high content of volcanics in the gas reservoir of the upper Paleozoic distorted and deformed the anomaly curves when they were stacked onto the primary background anomaly. The gas wells were generally found to be located in the anomaly gradient zones, or the distorted part of contour lines, and the flanks of high and low anomalies, or the transitional zones between anomaly highs and lows. The characteristics of gravity and magnetic fields provide significant information that can be used for guidance when exploring the distribution of gas. Based on these characteristics, five favourable areas for gas exploration were identified; these are quasi-equally spaced like a strip extending from the southeast to the northwest.

  9. Can there be additional rocky planets in the Habitable Zone of tight binary stars with a known gas giant?

    CERN Document Server

    Funk, Barbara; Eggl, Siegfried

    2015-01-01

    Locating planets in HabitableZones (HZs) around other stars is a growing field in contemporary astronomy. Since a large percentage of all G-M stars in the solar neighbourhood are expected to be part of binary or multiple stellar systems, investigations of whether habitable planets are likely to be discovered in such environments are of prime interest to the scientific community. As current exoplanet statistics predicts that the chances are higher to find new worlds in systems that are already known to have planets, we examine four known extrasolar planetary systems in tight binaries in order to determine their capacity to host additional habitable terrestrial planets. Those systems are Gliese 86, gamma Cephei, HD 41004 and HD 196885. In the case of gamma Cephei, our results suggest that only the M dwarf companion could host additional potentially habitable worlds. Neither could we identify stable, potentially habitable regions around HD 196885 A. HD 196885 B can be considered a slightly more promising target ...

  10. Tight turns

    CERN Multimedia

    Anaïs Schaeffer

    2012-01-01

    The Italian National Institute for Nuclear Physics (INFN) has successfully tested the first model of a new fast-ramping curved dipole magnet. This is great news for CERN, which sees the advance as holding potential for the future of the SPS.   The first model of a new fast-ramping curved dipole magnet being prepared for cryogenic testing at the LASA laboratory (INFN Milano, Italy). On 16 July INFN introduced an innovative dipole magnet. With a length of some 4 metres, it can produce a 4.5 Tesla magnetic field and achieve a tighter bend than ever before (the bending radius has been squeezed to a remarkable 66.7 metres). This new magnet was designed in the first instance for GSI’s SIS300 synchrotron (in Germany), which will require 60 dipoles of this type. "Achieving such a tight bend demanded a major R&D effort," stressed Pasquale Fabbricatore, the spokesman of the INFN collaboration responsible for the magnet’s development. "We had to not o...

  11. EVALUACIÓN DE SOSTENIBILIDAD CON METODOLOGÍA GRI // EVALUATION OF SUSTAINABILITY USING GRI METHODOLOGY // AVALIAÇÃO DA SUSTENTABILIDADE COM METODOLOGIA GRI

    Directory of Open Access Journals (Sweden)

    Luisa Cecilia Rodríguez-Guerra

    2016-06-01

    Full Text Available Este artículo es el resultado de  investigación realizada a 87 empresas que reportaron bajo la metodología Global Reporting Initiative (GRI G4, capítulo Colombia, entre el 01 de enero y 31 de diciembre del año 2015 con el objetivo de describir el nivel de sostenibilidad social, económica y ambiental, teniendo en cuenta el concepto definido por ellas mismas.  Para lograr obtener los resultados esperados, se elaboró una escala de medición, la cual cataloga a la organización de acuerdo a su desempeño en Madura, En Desarrollo e Incipiente, independientemente del tamaño o sector económico al cual pertenezca.  Las conclusiones y la discusión pretenden explicar porque el nivel En Desarrollo es el predominante en entorno empresarial Colombiano.  De igual manera, se sugiere una implementación organizacional para que la mayor cantidad de empresas posibles, logren la Sostenibilidad Organizacional por medio de un agente externo que así lo determine, después de realizar el respectivo análisis de la información

  12. Engineering support services for the DOE/GRI coal gasification research program. Quarterly technical progress report, January-March 1982

    Energy Technology Data Exchange (ETDEWEB)

    Bostwick, L.E.; Ethridge, T.R.; Starr, D.W.; Koneru, P.B.; Hubbard, D.A.; Shah, K.V.; Smith, M.R.; Ward, W.E.; Wong, E.W.

    1982-05-01

    Kellogg continued to actively monitor operations at BI-GAS, Westinghouse and IGT (for peat gasification). Pilot plant/PDU test runs which were monitored and reported included BI-GAS Tests G-18, G-18A and G-18B; Westinghouse PDU Test TP-032-1 and CFSF Test TP-M003; and Peatgas Pilot Plant Test No. 5. Kellogg also monitored winterization/maintenance activities at BI-GAS and Westinghouse and precommissioning of the IGT Wet Carbonization PDU. The final report on the Hygas Data Base Evaluation was issued, while final revisions were completed for the reports concerning PDU data base evaluations of Peatgas and single-stage peat gasification. Efforts toward completion of the brochure describing the DOE/GRI Joint Program proceeded. Normal MPC activities continued. Several technical progress reports were issued during this quarter.

  13. Engineering support services for the DOE/GRI coal-gasification research program. Quarterly technical progress report, October-December 1981

    Energy Technology Data Exchange (ETDEWEB)

    Bostwick, L.E.; Ethridge, T.R.; Starr, D.W.; Shah, K.V.; Hubbard, D.A.; Koneru, P.B.; Smith, M.R.; Ward, W.E.; Wong, E.W.; Zeis, L.A.

    1982-02-01

    Kellogg continued to actively monitor operations at BI-GAS Westinghouse and IGT (for peat gasification). Pilot plant/PDU testing which was monitored and reported includes Westinghouse PDU tests TP-030-3 and TP-031-3 and CFSF test TP-M003-1; Peatgas Pilot Plant test No. 4; and single-stage peat gasification PDU tests BF-22 and BF-23. Kellogg personnel briefed the GRI Project Advisors on current tasks and a DOE representative on peat-related work. The report on the Hygas Data Base Evaluation was approved for issue. Progress was made toward finalizing the report on the Peatgas Data Base Evaluation and the Descriptive Brochure for the DOE/GRI Joint Program. Work on the evaluation of the data base for single-stage peat gasification continued. Review of the Hygas final report was completed.

  14. Hydrocarbon accumulation patterns of large tight oil and gas fields%论致密大油气田成藏模式

    Institute of Scientific and Technical Information of China (English)

    赵靖舟; 李军; 曹青; 白玉彬; 耳闯; 王晓梅; 肖晖; 吴伟涛

    2013-01-01

    根据对国内外致密油气聚集成藏特征的分析,提出致密大油气田存在3种成藏模式,即连续型(深盆气型)、准连续型和不连续型(常规圈闭型)。与连续型油气藏相似,准连续型油气聚集也表现为:油气分布面积较大,无明确边界,也无边底水;源、储邻近,广覆式分布;油气运移主要为非浮力驱动,运移动力主要为异常压力、扩散作用力和毛细管压力,浮力作用受限;运移的方式主要为非达西流,以涌流和扩散流为主。所不同的是:准连续型油气聚集由多个彼此相邻的中小型油气藏组成,油气呈准连续分布;油、气、水分布比较复杂,无显著油、气、水倒置;油气充注以大面积弥漫式垂向排驱为主,初次运移直接成藏或短距离二次运移成藏;储层先致密后成藏或边致密边成藏,且非均质性较强;圈闭对油气聚集成藏具有一定控制作用。研究认为,以深盆气或盆地中心气为代表的连续型油气藏与典型的不连续型常规圈闭油气藏,分别代表了复杂地质环境中致密油气藏形成序列中的两种端元类型,二者之间应存在不同的过渡类型。准连续型油气藏就是这样一种过渡类型的致密油气聚集,并且可能是致密储层中大油气田形成的主要方式。事实上,典型的连续型油气聚集应是那些形成于烃源岩内的油气聚集(如页岩气和煤层气),典型的不连续型油气聚集则是那些形成于烃源岩外近源-远源的常规储层中、受常规圈闭严格控制并且具有边底水的油气聚集;而形成于烃源岩外并且近源的致密油气藏则主要为准连续型油气聚集,其次为非典型的不连续型(常规圈闭型)油气聚集,而像盆地中心气或深盆气那样的连续型聚集则较为少见。%Three patterns of hydrocarbon accumulation in large tight oil /gas fields are

  15. REPORTING CORPORATE SOCIAL RESPONSIBILITY ACCORDING TO GRI STANDARDS

    Directory of Open Access Journals (Sweden)

    Berinde Mihai

    2015-07-01

    Full Text Available Corporate social responsibility is no longer considered an optional activity by companies. The changes that take place worldwide have determined an increasing number of companies to elaborate instruments of implementing CSR principles into their business strategy. A CSR policy adapted to the specifics of the company’s field of activity and to the community in which it is present will bring advantages for both parties. The way through which a company makes their CSR activity results public is by writing a sustainability report which corresponds to international practices in the field. In recent years, an increasing number of companies publish their yearly CSR reports. This reporting originated in the USA, but in the last decade, the number of reports from Europe is increasing. In order to answer to the needs of reporting of the companies, a series of nongovernmental organisms have involved in trying to find the most accessible way that would correspond to the needs of the companies and of the stakeholders. Global Reporting Initiative is a platform that came to the aid of the companies by creating reporting standards which to guide companies through the process of creating the sustainability report. In this paper, we have analysed the evolution in the number of CSR reports worldwide, having then analysed their distribution on continents. We have given attention to the situation in Romania, which in the past ten years, due to multinational companies coming in the market. The presence of multinational companies has helped develop this concept. In the past five years, Romanian companies have submitted CSR reports according to GRI standards. Although the percent of companies of Romanian companies that submit reports according to the GRI standards is small (0.0017%, we believe that it will grow in following years, due to companies realizing the role they have in the society and because the European Commission’s 2014/95/EU Directive will enter into

  16. Arabidopsis GRI is involved in the regulation of cell death induced by extracellular ROS.

    Science.gov (United States)

    Wrzaczek, Michael; Brosché, Mikael; Kollist, Hannes; Kangasjärvi, Jaakko

    2009-03-31

    Reactive oxygen species (ROS) have important functions in plant stress responses and development. In plants, ozone and pathogen infection induce an extracellular oxidative burst that is involved in the regulation of cell death. However, very little is known about how plants can perceive ROS and regulate the initiation and the containment of cell death. We have identified an Arabidopsis thaliana protein, GRIM REAPER (GRI), that is involved in the regulation of cell death induced by extracellular ROS. Plants with an insertion in GRI display an ozone-sensitive phenotype. GRI is an Arabidopsis ortholog of the tobacco flower-specific Stig1 gene. The GRI protein appears to be processed in leaves with a release of an N-terminal fragment of the protein. Infiltration of the N-terminal fragment of the GRI protein into leaves caused cell death in a superoxide- and salicylic acid-dependent manner. Analysis of the extracellular GRI protein yields information on how plants can initiate ROS-induced cell death during stress response and development.

  17. 天然气调节球阀阀体半自动气压试验装置设计%Semi-automatic Gas-tightness Test Equipment Design of Natural Gas Ball Valvee

    Institute of Scientific and Technical Information of China (English)

    刘功祥

    2015-01-01

    In order to ensure the quality of ball valve, three kinds of testes must be carried out. Firstly, valve hydraulic test;secondly, valve pneumatic test;thirdly, valve gas-tightness test. Wherein, valve pneumatic test mainly detects gas-tightness under a certain pressure, so that it can be safe and effective running to achieve its normal regulating function. Pneumatic test equipment can provide high-efficiency and high-quality test platform for the performance testing of ball valve, and improve the efficiency of ball valve testing.%为保证球阀的质量,必须进行三个方面的试验。一是阀体水压试验,二是阀体气压试验,三是球阀密闭性试验。其中,阀体气压试验主要是在一定压力下检测其密闭性,以使其能够安全有效地运行,正常地实现其调节功能。气压试验装置可为球阀的性能测试提供高效高质量的测试平台,提高球阀阀体气压试验的效率。

  18. 建111井致密砂岩气显示录测井解释研究%On Study of Logging Interpretation of Tight Sandstone Gas Show in Jian Well 111

    Institute of Scientific and Technical Information of China (English)

    张琼; 张伟; 夏敬民; 李光华

    2012-01-01

    致密砂岩气属于非常规天然气资源家族的一员,其储层孔隙度低、渗透率低、随钻录井气测显示弱、气水关系复杂。这些特征,给录测井解释评价带来诸多需要攻关与认识的技术难题。在建南地区首口致密砂岩气勘探开发试验井—建111井,江汉录测井人员于须家河组须六段致密砂岩储层发现并解释典型致密砂岩气层1层厚9.0m,完井测试,日产天然气3 000m3。须六段致密砂岩气的成功解释评价,丰富和验证了现有的录测井致密砂岩气解释评价方法,为下步该地区致密砂岩气开发录测井解释评价积累一定的实践经验。%Tight sandstone gas belongs to an unconventional gas resource.Its reservoir has a low void ratio and permeability.The show effect for gas survey in well drilling and logging is weak and gas-water relation is complicated.All this has brought problems technologically to logging interpretation and evaluation which need to be understood and solved.In the process of exploring and developing the first test well(Jian Well 111) with tight sandstone gas in Jiannan area,Jianghan well logging staff have discovered and interpreted typical tight sandstone gas reservoir of 9.0 m thickness per layer in tight sandstone reservoir of Member Xu 6 in Xujiahe Formation.Output of natural gas a day reaches 3000m3 during well completing test.Success in interpreting and evaluating tight sandstone gas of Member Xu 6 has enriched and checked existing evaluation method,and accumulated some practical experience for well logging interpretation and evaluation in the next development of tight sandstone gas in Jiannan area.

  19. A gas-tight Cu K alpha x-ray transparent reaction chamber for high-temperature x-ray diffraction analyses of halide gas/solid reactions.

    Science.gov (United States)

    Shian, Samuel; Sandhage, Kenneth H

    2009-11-01

    An externally heated, x-ray transparent reaction chamber has been developed to enable the dynamic high temperature x-ray diffraction (HTXRD) analysis of a gas/solid [TiF(4)(g)/SiO(2)(s)] reaction involving a halide gas reactant formed at elevated temperatures (up to 350 degrees C) from a condensed source (TiF(4) powder) sealed within the chamber. The reaction chamber possessed x-ray transparent windows comprised of a thin (13 microm) internal layer of Al foil and a thicker (125 microm) external Kapton film. After sealing the SiO(2) specimens (diatom frustules or Stober spheres) above TiF(4) powder within the reaction chamber, the chamber was heated to a temperature in the range of 160-350 degrees C to allow for internal generation of TiF(4)(g). The TiF(4)(g) underwent a metathetic reaction with the SiO(2) specimen to yield a TiOF(2)(s) product. HTXRD analysis, using Cu K alpha x rays passed through the Kapton/Al windows of the chamber, was used to track the extent of SiO(2) consumption and/or TiOF(2) formation with time. The Al foil inner layer of the windows protected the Kapton film from chemical attack by TiF(4)(g), whereas the thicker, more transparent Kapton film provided the mechanical strength needed to contain this gas. By selecting an appropriate combination of x-ray transparent materials to endow such composite windows with the required thermal, chemical, and mechanical performance, this inexpensive reaction chamber design may be applied to the HTXRD analyses of a variety of gas/solid reactions.

  20. Effect of weave tightness and structure on the in-plane and through-plane air permeability of woven carbon fibers for gas diffusion layers

    Energy Technology Data Exchange (ETDEWEB)

    Caston, Terry B.; Murphy, Andrew R.; Harris, Tequila A.L. [Department of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA (United States)

    2011-01-15

    In this study, woven gas diffusion layers (GDLs) with varying weave type and tightness are investigated. Plain and twill weave patterns were manufactured in-house. The in-plane and through-plane air permeability of the woven samples were tested, and mercury intrusion porosimetry (MIP) tests were performed to study the pore structure. It was found that the twill weave has a higher permeability than the plain weave, which is consistent with literature. Like non-woven carbon papers, woven GDLs have higher in-plane permeability than through-plane permeability; however it has been shown that it is possible to manufacture a GDL with higher through-plane permeability than in-plane permeability. It was also concluded that the percentage of macropores in the weave is the driving factor in determining the through-plane air permeability. This work lays the groundwork for future studies to attempt to characterize the relationship between the weave structure and the air permeability in woven GDLs. (author)

  1. A-Factor and Phosphate Depletion Signals Are Transmitted to the Grixazone Biosynthesis Genes via the Pathway-Specific Transcriptional Activator GriR▿ †

    OpenAIRE

    Higashi, Tatsuichiro; Iwasaki, Yuko; Ohnishi, Yasuo; Horinouchi, Sueharu

    2007-01-01

    Grixazone (GX), which is a diffusible yellow pigment containing a phenoxazinone chromophore, is one of the secondary metabolites under the control of A-factor (2-isocapryloyl-3R-hydroxymethyl-γ-butyrolactone) in Streptomyces griseus. GX production is also induced by phosphate starvation. The whole biosynthesis gene cluster for GX was cloned and characterized. The gene cluster consisting of 13 genes contained six transcriptional units, griT, griSR, griR, griAB, griCDEFG, and griJIH. During cul...

  2. Progress of research on hydrocarbon accumulation of tight sand gas and several issues for concerns%致密砂岩气成藏研究进展及值得关注的几个问题

    Institute of Scientific and Technical Information of China (English)

    郭迎春; 庞雄奇; 陈冬霞; 姜福杰; 汤国民

    2013-01-01

    Continuous tight sand gas is a significant unconventional resource for natural gas .To understand the progress of geological research on this kind of gas reservoir ,this paper summarized the criteria for identification of tight sand reser-voirs,their classification ,geological characteristics ,elements of hydrocarbon accumulation ,and trapping mechanisms .The current criteria for identivation of continuous tight sand gas reservoirs does not take accumulation conditions into conside -ration.The real critical conditions of tight sand gas change along with hydrocarbon accumulation conditions .The key ele-ments of hydrocarbon accumulation in tight gas reservoir involve hydrocarbon source rock ,tight sandstone close to source rock and stable tectonic environment .It should be noted that the nature of tight sandstone is nano-micro scale pore throat and the percentage of pore throats is about the same as that of pores ,and that abnormal pressure is not an essential differ-ence between tight sand gas reservoir and conventional gas reservoir .Several key issues concerning continuous tight sand gas accumulation are presented .The first is study on dynamic trapping mechanism for tight sand gas reservoir ,i.e.the force balance between driving force(gas pressure)and resistance(capillary force,viscous force and formation water pres-sure) at the interface of gas water inversion .The quantitative description and simulation of evolution of these forces are particularly important .The second is the research on the mechanism and process of adjustment of tight sand gas reservoir as well as restoration of the original tight sand gas reservoir .The restoration of the original reservoir can be realized by means of force balance relation at the interface of gas water inversion .All of the late adjustment and modification were realized through changing the critical conditions of gas water inversion .The third is study of the control of sandbodies with relatively high porosity and

  3. Gri Suyun Arıtımı ve Yeniden Kullanımı

    OpenAIRE

    ÜSTÜN, Gökhan Ekrem; TIRPANCI, Ayşenur

    2015-01-01

    Çalışmanın amacı, gri su arıtımının ve yeniden kullanılması konusunun incelenmesidir. Bu amaç için daha önce yapılmış literatür çalışmaları araştırılıp, yorumlanmıştır. Çalışmanın ilk aşamasında gri suyun tanımlanması ile fiziksel, kimyasal ve biyolojik karakteristiği açıklanmıştır. İkinci kısmında, gri suyun arıtım yöntemleri ve yeniden kullanımı incelenmiştir. Üçüncü kısımda gri suların arıtımında kullanılan teknolojiler tek tek açıklanmıştır. Son olarak gri su arıtımı ve yeniden kullanımı ...

  4. 塔里木盆地库车坳陷致密砂岩气藏成因类型%Genetic Types of the Tight Sandstone Gas Reservoirs in the Kuqa Depression, Tarim Basin, NW China

    Institute of Scientific and Technical Information of China (English)

    李卓; 姜振学; 庞雄奇; 李峰; 张宝收

    2013-01-01

    To further understand the genetic types of the tight sandstone gas reservoirs in Kuqa depression, the core from tight sandstone gas reservoirs is sampled to carry out the analysis on hydrocarbon charge history and porosity evolutioa The hydrocarbon charge history is investigated by analyzing the fluid inclusion petrography, and microther mometry and the porosity evolution is restored by using the model of deposition-structure -diagenesis. Combining with gas-water relationship and distribution of tight sandstone gas reservoirs. There are two charge events in the YN2 Jurassic tight sandstone reservoir, with the one of oil charge during 23-12 Ma, and the other gas charge during 5-0 Ma. The reservoir porosity dropped to less than 12% and became tight during the period of 12-8 Ma Two charge events have been recorded in the DN2 Paleogene tight sandstone reservoir; the former is oil charge during 23-12 Ma, and the latter is the gas charge during 5 - 0 Ma. The reservoir porosity dropped to less than 12% during the period of 2-0 Ma and became tight later. Two genetic types of tight sandstone gas reservoirs have been confirmed. The YN2 Jurassic tight sandstone reservoir is of the genetic type of "tight deep basin gas reservoir" with the accumulation process of gas charge after the reservoir tightened and the DN2 Paleogene tight sandstone reservoir is defined as "tight conventional gas reservoir" with the accumulation process of gas charge before the reservoir tightened. This study is of significance for further exploration and exploitation of tight sandstone gas in Kuqa depressioa.%为深化对库车坳陷致密砂岩气藏成因类型的认识,采集致密砂岩储层岩样,开展了油气充注史和孔隙度演化史研究.通过流体包裹体岩相学和显微测温厘定了油气充注史,利用沉积-构造-成岩一体化模型恢复了储层孔隙度演化史,根据两者的先后关系,划分了致密砂岩气藏的成因类型.结果表明,依南2侏罗系气藏

  5. Prime tight frames

    DEFF Research Database (Denmark)

    Lemvig, Jakob; Miller, Christopher; Okoudjou, Kasso A.

    2014-01-01

    to suggest effective analysis and synthesis computation strategies for such frames. Finally, we describe all prime frames constructed from the spectral tetris method, and, as a byproduct, we obtain a characterization of when the spectral tetris construction works for redundancies below two.......We introduce a class of finite tight frames called prime tight frames and prove some of their elementary properties. In particular, we show that any finite tight frame can be written as a union of prime tight frames. We then characterize all prime harmonic tight frames and use thischaracterization...

  6. Avances en la exposición contable de CoPs y memorias GRI = Advances in CoPs and GRI reports as accounting statements

    Directory of Open Access Journals (Sweden)

    Liliana Fernández Lorenzo

    2012-07-01

    Full Text Available Actualmente para lograr un desarrollo sustentable, la sociedad requiere que las organizaciones asuman su responsabilidad socio-ambiental y emitan información acerca de los impactos que su actividad genera en el medioambiente.Dicha información mayormente se presenta a través de las denominadas Memorias o Reportes de Sostenibilidad, que responden a distintas formas y contenidos. Cada vez son más los informes que se elaboran siguiendo los lineamientos del Pacto Mundial (PM y del Global Reporting Initiative (GRI.Consideramos que la información sobre la responsabilidad socio-ambiental debería reunir los requisitos que hacen a toda buena información contable, para incrementar su utilidad.Para comprobarlo, se realiza un estudio de casos a los fines de determinar las características generales de estos informes elaborados bajo pautas del PM y del GRI conjuntamente, concluyendo que la información presentada en las memorias analizadas no reúne los requisitos de una buena información contable.A fin de que la exposición de las CoPs y memorias de sostenibilidad GRI, pueda calificarse de contable, se expresan sintéticamente los indicadores analizados agregando su relación porcentual y se incorporan al Estado Contable Socio-ambiental realizado de acuerdo al modelo base de la FCE-UNLP, considerado como un estado contable (Fernández Lorenzo y Geba, 2008.Nowadays in order to achieve sustainable development, organizations are required to take on their social and environmental responsibility and give information about the impact of their activities in the environment.This information is usually presented through sustainability reports, which widely differ in content and layout. Many organizations worldwide have assumed their responsibility by implementing Global Reporting Initiative (GRI and United Nations Global Compact (GC guidelines.We consider that the information regarding socio-environmental responsibility, should meet the characteristics of the

  7. 苏里格大型致密砂岩气田开发井型井网技术%Well type and pattern optimization technology for large scale tight sand gas,Sulige gas field

    Institute of Scientific and Technical Information of China (English)

    何东博; 贾爱林; 冀光; 位云生; 唐海发

    2013-01-01

    Sulige gas field is a typical tight sand gas field in China. Well type and pattern optimization is the key technology to improve single well estimated reserves and recovery factor and to achieve effective field development. In view of the large area, low abundance and high heterogeneity of Sulige gas field, a series of techniques have been developed including hierarchical description for the reservoir architecture of large composite sand bodies and well spacing optimization, well pattern optimization, design and optimization for horizontal trajectory and deliverability evaluation for different types of gas wells. These technologies provide most important technical supports for the increases of class ⅠandⅡ wells proportion to 75%-80% with recovery factor enhanced by more than 35% and for the industrial application of horizontal drilling. To further improve individual well production and recovery factor, attempts and pilot tests in various well types including side tracking of deficient wells, multilateral horizontal wells, and directional wells, and horizontal well pattern and combined well pattern of various well types should be carried out throughout the development.%苏里格气田是中国致密砂岩气田的典型代表,井型井网技术是其提高单井控制储量和采收率、实现气田规模有效开发的关键技术.针对苏里格气田大面积、低丰度、强非均质性的特征,形成了大型复合砂体分级构型描述与优化布井技术、井型井网优化技术、水平井优化设计技术和不同类型井产能评价技术,为苏里格气田产能建设Ⅰ +Ⅱ类井比例达到75%~80%、预期采收率提高到35%以上以及水平井的规模化应用发挥了重要的技术支撑作用.为进一步提高苏里格气田单井产量和采收率,应继续开展低效井侧钻、多分支水平井、多井底定向井等不同井型,以及水平井井网、多井型组合井网的探索和开发试验.

  8. Geological characteristics of the Triassic tight sandstone oil and gas reservoirs in Luoyang-Yichuan area%洛阳-伊川地区三叠系致密砂岩油气藏地质特征

    Institute of Scientific and Technical Information of China (English)

    杜建波; 田景春; 胡俊卿; 曹建康

    2013-01-01

    Research of the petroleum geological conditions indicates that Luoyang-Yichuan area is located in the same large depressed lacustrine basin with Ordos Basin in the Triassic.They have similar source-reservoir-caprock associations,thick and extensive source rocks,tight reservoir and active hydrocarbon shows in the Triassic.Therefore,the Luoyang-Yichuan area has the geological conditions for accumulation of tight sand oil/gas.In combination with the analysis of industrial gas flow from the Upper Triassic Chunshuyao Formation in Well Tun 1,we believe that the Triassic reservoirs of the Luoyang-Yichuan area are pre-existing tight sandstone oil/gas reservoirs with low permeability,abnormal pressure,inverted oil-gas contact with oil in the upper and gas in the lower.The Triassic tight sandstone reservoirs are the main targets of petroleum exploration in Luoyang-Yichuan area in the future.%通过对洛阳-伊川地区三叠系基本石油地质条件的分析,认为三叠纪洛阳-伊川地区与鄂尔多斯盆地处于同一大型坳陷型湖盆,生储盖架构相似,烃源岩发育、厚度大、横向展布稳定、储层致密,且三叠系油气显示丰富,具致密砂岩油气藏形成的地质条件.结合对屯l井上三叠统椿树腰组工业天然气流分析,进一步明确了洛阳-伊川地区三叠系油气藏为具有低孔渗性、地层压力异常、油气呈“上油下气”倒置关系等特征的先成型致密砂岩油气藏,从而指出三叠系为洛阳-伊川地区下一步油气勘探的主攻层系,致密砂岩油气藏是该区勘探的主要方向.

  9. Briefly Discuss on Tightness Test and Maintenance of Gas Fire Extinguishing System’s Start Pipeline%浅谈气体灭火系统启动管道的气密性试验和维护保养

    Institute of Scientific and Technical Information of China (English)

    刘富标

    2014-01-01

    气体灭火系统用于重要设备房内,如设备房内发生火灾系统将自动喷气进行灭火。气体灭火系统的启动管道是喷气式,用于输送启动瓶的氮气打开选择阀和灭火剂存储钢瓶瓶头阀,而启动管道满足气密性要求是保证气体灭火剂正常喷发的先决条件,因而必须在施工验收期间进行启动管道气密性试验并在日常维护中重点关注其气密性是否满足要求。仅就气体灭火系统启动管道气密性试验的必要性、具体方法及其维护保养提出一些看法,供气体灭火系统相关单位进行施工验收和维护保养时参考。%Gas extinguishing systems is used in important equipment room,when the fire broke out it will release extinguishing agent to put out the fire. When releasing extinguishing agent, the start pipeline of gas fire extinguishing system is used to transfer the nitrogen of starting receiver to open selector valve and extinguishing agent storage steel cylinder’s bottle valve. The tightness of start pipeline is the precondition for gas releasing. So it’ s important to do tightness test when it’ s under construction and acceptance, it’ s also very important to pay close attention to the tightness of start pipeline in daily maintain. This article will discuss the importance of start pipeline’ s tightness test,and how to do tightness test and maintenance method,to provide a reference to those who need.

  10. Fault features and enrichment laws of narrow-channel distal tight sandstone gas reservoirs: A case study of the Jurassic Shaximiao Fm gas reservoir in the Zhongjiang Gas Field, Sichuan Basin

    Directory of Open Access Journals (Sweden)

    Zhongping Li

    2016-11-01

    Full Text Available The Jurassic Shaximiao Fm gas reservoir in the Zhongjiang Gas Field, Sichuan Basin, is the main base of Sinopec Southwest Oil & Gas Company for gas reserves and production increase during the 12th Five-Year Plan. However, its natural gas exploration and development process was restricted severely, since the exploration wells cannot be deployed effectively in this area based on the previous gas accumulation and enrichment pattern of “hydrocarbon source fault + channel sand body + local structure”. In this paper, the regional fault features and the gas accumulation and enrichment laws were discussed by analyzing the factors like fault evolution, fault elements, fault-sand body configuration (the configuration relationship between hydrocarbon source faults and channel sand bodies, trap types, and reservoir anatomy. It is concluded that the accumulation and enrichment of the Shaximiao Fm gas reservoir in this area is controlled by three factors, i.e., hydrocarbon source, sedimentary facies and structural position. It follows the accumulation laws of source controlling region, facies controlling zone and position controlling reservoir, which means deep source and shallow accumulation, fault-sand body conductivity, multiphase channel, differential accumulation, adjusted enrichment and gas enrichment at sweet spots. A good configuration relationship between hydrocarbon source faults and channel sand bodies is the basic condition for the formation of gas reservoirs. Natural gas accumulated preferentially in the structures or positions with good fault-sand body configuration. Gas reservoirs can also be formed in the monoclinal structures which were formed after the late structural adjustment. In the zones supported by multiple faults or near the crush zones, no gas accumulation occurs, but water is dominantly produced. The gas-bearing potential is low in the area with undeveloped faults or being 30 km away from the hydrocarbon source faults. So

  11. Types, characteristics, genesis and prospects of conventional and unconventional hydrocarbon accumulations:taking tight oil and tight gas in China as an instance%常规与非常规油气聚集类型、特征、机理及展望——以中国致密油和致密气为例

    Institute of Scientific and Technical Information of China (English)

    邹才能; 李登华; 白斌; 王岚; 朱如凯; 吴松涛; 杨智; 陶士振; 袁选俊; 侯连华; 杨华; 徐春春

    2012-01-01

    accumulation mechanism, and the key answer is whether the trap contains petroleum, otherwise, unconventional petroleum focuses on the reservoir space, and the key answer is how much the reservoirs capture petroleum. Unconventional hydrocarbon resources are mainly characterized by continuous distribution and no natural oil and gas production from per well. Currently, unconventional problems occur in the exploration and development of conventional hydrocarbon resources, thus it is necessary to transform unconventional hydrocarbon resources into new "conventional" hydrocarbon resources. With technology development, unconventional hydrocarbons can be transformed into conventional ones. Generally, conventional hydrocarbon deposits consist of structural and litho-stra-tigraphic hydrocarbon reservoirs, where oil and gas are distributed in an isolated structure or a larger structure group with clear trap boundaries and pore-throat systems in millimeter-micrometer scale. Oil and gas in this case accumulate by buoyancy to form hydrocarbon pools. However, unconventional hydrocarbon accumulations, including tight sandstone oil and gas, tight carbonate oil and gas, shale oil and gas, coal-bed methane, oil shale, oil sand, hydrate, etc. , are distributed continuously or quasi-continuously in basin's slopes or centers. Commonly, they are characterized by source-reservoir paragenesis and have no distinct trap boundaries. Pore-throat systems in nanometer scale are well-developed in unconventional reservoir rocks, and related hydrocarbons are mainly detained in situ or migrate fora short distance into reservoirs that are close to source rocks because buoyancy is limited. The present paper systematically analyzed geological characteristics and exploration potential of tight hydrocarbons in some typical basins of China, where pores in nanometer scale with partial micrometer-millimeter pores dominate the reservoir space of unconventional hydrocarbons, the diameter of reservoir pores is 5~200 nm in

  12. 3 x Griškovets ehk avanemine kildude kaudu / Ireene Viktor

    Index Scriptorium Estoniae

    Viktor, Ireene

    2009-01-01

    Jevgeni Griškovetsi teksti põhjal valminud lavastustest: "Samal ajal", tõlkinud, lavastanud ja mängib Priit Ruttas, esietendus Tartu Athena keskuses 30. juunil 2008. "Linn", lavastaja Lembit Peterson, esietendus Theatrumi saalis 7. juunil 2008. "Vene rännumehe ülestähendused", lavastajad ja kunstnikud Ott Aardam ja Mart Aas, Tartu Uue Teatri esietendus 9. augustil Genialistide klubis

  13. Controlled Owicki-Gries Concurrency: Reasoning about the Preemptible eChronos Embedded Operating System

    OpenAIRE

    2015-01-01

    We introduce a controlled concurrency framework, derived from the Owicki-Gries method, for describing a hardware interface in detail sufficient to support the modelling and verification of small, embedded operating systems (OS's) whose run-time responsiveness is paramount. Such real-time systems run with interrupts mostly enabled, including during scheduling. That differs from many other successfully modelled and verified OS's that typically reduce the complexity of concurrency by running on ...

  14. Applying & Publishing GRI framework in Transport Companies Rethink. Redesign. Rebuild. CSR Reporting and Climate Change

    Directory of Open Access Journals (Sweden)

    Lilian Soares Outtes Wanderley

    2010-08-01

    Full Text Available Corporations with systematic relationships to tourism are developing activities and publishing CSR reports applying the GRI framework (GRI, 2009. The contribution of tourism to climate change is estimated at between 5% and 12% and by 2050 the amount spent on the tourism sector will consume the entire carbon budget required to avoid dangerous climate change (Scott et al. 2009, UNWTO-UNEP-WMO 2008. This study defines the TC-8 group, a group of transport in tourism related companies, in order to answer the main questions:To what extent is climate change addressed in the CSR reports of transport companies? Climate change is mentioned and receives attention in all of the company reports analysed, however,overall the transport sector shows that in comparison to the GRI/KPMG (2007 survey, it under-performs. Are the companies just reporting direct emissions from production or also broader emissions from the use of the products? Half of these companies report emissions; some include direct and indirect emissions. Further actions can be mentioned such as, companies participating in forums discussing solutions to climate change, assuming shared responsibilities and employing measures such as reducing energy consumption by runningtheir own photovoltaic power unit or planning for a CO2 neutral operation by 2012.

  15. Application of Effective Porosity Model to Tight Gas Sands in Ordos Basin%等效孔隙结构模型在鄂尔多斯致密含气砂岩中的应用

    Institute of Scientific and Technical Information of China (English)

    周枫; 徐鸣洁; 马中高

    2013-01-01

    Core samples from a well in Ordos basin are used to study the elastic properties of tight gas sands in lower Shihezi Formation. Elastic parameters are measured at in-situ physical conditions. The total pore space is divided into three space types based on the microscopic analyses. Soft porosity model (SPM) is modified to construct a new model which could represent the tight gas sands reservoir. A modeling example using the well-log data from Daniudi gas field is completed using self-consistent theory. Model predicted results include Vp, Vs, Poisson’s ratio, acoustic impedance of P wave and acoustic impedance of S wave. Comparison of those elastic properties derived from the model, well-log, and core sample measurement is conducted to evaluate the new model. Predicted Vp, Vs are overall in agreement with well-log data. The same agreement also appears in Poisson’ s ratio curve. But the model predicts a slightly different behavior of rocks from the core samples in the impedance of P wave (AIp) and acoustic impedance of S wave (AIs). Predicted AIp and AIs are slightly higher than those of core samples. Pressure may be the main factor responsible for the difference between the model and core samples. The AIp and AIs are calculated from velocity and density, which are derived from the well-log data. The density in-situ condition is higher than what is measured in laboratory because of the pressure produced by upper strata. So the predicted AIp and AIs show a slight rise in comparison to the core samples. This article provides a good example of applying SPM to tight gas sands of Ordos, and show that the model will be very helpful to predict elastic properties of tight gas reservoirs.%该文作者采集了鄂尔多斯大牛地气田二叠系下石盒子组钻井岩芯,在60 Mpa围压和50℃温度下进行了岩芯弹性参数测试。通过岩石薄片分析孔隙结构特征,按照孔隙的纵横比值(0.9)将孔隙划分为三类,进而对柔性孔隙模

  16. 生物再生生命保障地基实验系统气密性评价%Evaluation on Gas Tightness of Ground-based Experimental Bioregenerative Life Support System

    Institute of Scientific and Technical Information of China (English)

    胡大伟; 付玉明; 杜小杰; 张金晖; 刘红

    2016-01-01

    The gas tightness or leakage rate is an important technical parameter for the ground-based experimental Bioregenerative Life Support System (BLSS), because it directly determines the closure degree of the system and the accuracy of data from human-rated experiments .In this research , the mechanism of gas ( O2 and CO2 ) transient response to leakage rates in Lunar Palace 1, a prototype of BLSS in China , was investigated with mathematical model developed by gas equation , experimen-tal data and system dynamics , simulation model established by S-function on the platform of Matlab/Simulink , and theory of stochastic process .The gas tightness tests showed that the actual leakage rate of the Lunar Palace 1 cabin was 0.043%· d-1 which was almost a completely closed level via simulation and calculation .The gas steady-state response characteristics were also analyzed elabo-rately by stochastic process method to verify that the gas concentrations were robustly stable during the 105-day human-rated experiment in the Lunar Palace 1, and the actual leakage rate of cabin did not adversely affect experimental results , namely the gas tightness ensured the accuracy and reliabil-ity of data obtained from the human-rated experiment .This research may provide a theoretical and methodological basis for the design and building of BLSS in China .%针对直接影响生物再生生命保障系统地基实验系统有人密闭系统实验数据准确性的气密性或泄露率问题,以月宫一号大型地基实验系统为例,采用经典气体方程和系统动力学原理建立了影响其舱内气体动态的主要速率方程,并把泄露率作为其中的可调节参数,运用Mat-lab/Simulink中的S函数建立气体浓度对泄露率变化的瞬态响应特征模型.通过数值仿真实验研究,分析了在假设的不同泄露率下,月宫一号系统内O2和CO2气体浓度的动态变化规律.经气密性检验实验测定,月宫一号系统的舱体实际泄漏率为0

  17. Hållbarhetsredovisning i svenska börsbolag : En studie utifrån GRI:s riktlinjer

    OpenAIRE

    Nyberg, Niklas; Moberg, Sofia

    2008-01-01

    Sammanfattning Titel: ”Hållbarhetsredovisning i svenska börsbolag – En studie utifrån GRI:s riktlinjer” Seminariedatum: Måndagen 25 Februari 2008 Ämne/kurs: Företagsekonomi C-uppsats, 15 p Författare: Niklas Nyberg, Sofia Moberg Handledare: Margareta Paulsson Nyckelord: GRI, Hållbarhetsredovisning, redovisning, svenska företag Bakgrund: De senaste åren har kraven på svenska företag ökat, och intressenter efterfrågar nu information angående produktion, underleverantörer m.m. Att visa att de ta...

  18. 低渗透致密砂岩气层产能预测方法研究%Capacity Prediction Methods of Tight Gas Sandstone Reservoir with Low permeability

    Institute of Scientific and Technical Information of China (English)

    范宜仁; 宋岩; 张海涛; 张鹏; 李思

    2016-01-01

    T he gas reservoir property is poor and the percolation mechanism is complex in the eastern part of Upper Paleozoic in the Ordos Basin . It is difficult to determine the gas productivity index . And the relationship between gas abundance and porosity‐permeability is ambiguity . T herefore conventional productivity prediction method is not effective . Based on petrophysical experiments and wireline log data ,analyzed are the differences of different fluids in acoustic and elastic parameters .Then the sensitive parameters of the gas reservoir is optimized and gets the parameters with the Xu‐White model and Gassmann function .Lastly the prediction model is established on the basis of sensitive parameters . T he research concludes that bulk modulus is highly sensitive to the capacity of gas reservoir .And obtaining elastic parameters does not rely on the physical properties of gas reservoir .This method facilitates the capacity prediction of tight gas sandstone reservoir .%鄂尔多斯盆地东部上古生界含气储层物性差,渗流规律复杂,孔隙流体对测井响应特征贡献小,储层参数计算精度低,导致产能预测困难。针对这一问题,在对不同孔隙结构储层进行分类后,研究了常规产能预测方法,在此基础上从岩石物理实验出发,结合Biot‐Gassmann理论和Xu‐White模型,分析储层含气性与声学特征的关系,提取产能敏感因子,建立基于阵列声波测井的产能预测模型。研究表明,体积模量对储层含气性较为敏感,据此建立的气层产能预测模型克服了储层物性参数计算精度低的问题,与基于常规测井资料的产能预测模型相比,在致密砂岩气层具有更好的应用效果。

  19. Exploring Environmental Disclosure in SelectedAustralian Multinationals under the GRI Guidelines

    Directory of Open Access Journals (Sweden)

    Omar Al Farooque

    2014-09-01

    Full Text Available This paper explores changes in environmental reporting among Australian MNEs between 2004 and 2007, using the GRI guidelines, and explains how GRI transformation (from G2 to G3 leads to changes in environmental disclosure aspects along with their association with company size, profitability, industry sector. Applying Wilcoxon matched pair signed ranked and Spearman rank correlation tests, twenty companies from the Australian SAM Sustainability Index (AuSSI are examined to identify the extent of changes on specific aspects of environmental disclosure. The findings of the paper document a significant increase in environmental reporting in Australian companies. In particular, reporting has increased for energy, emissions and environmental management followed by water, overall, materials, transport and product/services aspects. However, a shift in emphasis from compliance and biodiversity aspects associated with climate changes and resource preservation is also evident. Again, the majority of changes occurred in companies operating in environmentally sensitive industries with industry sector having significant relationship with a few environmental disclosure aspects, the study shows no significant effect of company size and profitability on different environmental disclosure aspects. These evidences indicate that external forces (such as, legislation, industry sensitiveness to environment, and stakeholder awareness and pressure rather than internal factors are more effective to influence and determine environmental disclosure in Australian companies.

  20. Controlled Owicki-Gries Concurrency: Reasoning about the Preemptible eChronos Embedded Operating System

    Directory of Open Access Journals (Sweden)

    June Andronick

    2015-11-01

    Full Text Available We introduce a controlled concurrency framework, derived from the Owicki-Gries method, for describing a hardware interface in detail sufficient to support the modelling and verification of small, embedded operating systems (OS's whose run-time responsiveness is paramount. Such real-time systems run with interrupts mostly enabled, including during scheduling. That differs from many other successfully modelled and verified OS's that typically reduce the complexity of concurrency by running on uniprocessor platforms and by switching interrupts off as much as possible. Our framework builds on the traditional Owicki-Gries method, for its fine-grained concurrency is needed for high-performance system code. We adapt it to support explicit concurrency control, by providing a simple, faithful representation of the hardware interface that allows software to control the degree of interleaving between user code, OS code, interrupt handlers and a scheduler that controls context switching. We then apply this framework to model the interleaving behavior of the eChronos OS, a preemptible real-time OS for embedded micro-controllers. We discuss the accuracy and usability of our approach when instantiated to model the eChronos OS. Both our framework and the eChronos model are formalised in the Isabelle/HOL theorem prover, taking advantage of the high level of automation in modern reasoning tools.

  1. GriF: an infrared 3D spectroscopic mode for KIR/PUEO

    Science.gov (United States)

    Clenet, Yann; Arsenault, Robin; Beuzit, Jean-Luc; Chalabaev, Almas; Delage, Claude; Joncas, Gilles; Lacombe, Francois; Lai, Olivier; Le Coarer, Etienne; Le Mignant, David; Pau, Sylvain; Rabou, Patrick; Rouan, Daniel

    2000-07-01

    When combined with Adaptive Optics, integral field spectroscopy, i.e. observation of a sky field simultaneously in a number of spectral passbands, is the most efficient way to perform spectro-imaging at high angular resolution. GriF will provide the CFHT community with such a capability in the near infrared K-band. This extension will be completed by means of two simple optical devices to be installed in the KIR cryostat (the infrared camera of PUEO): a cooled grism in the filter-wheel and a cold aperture on an entrance focal plane wheel. They will be completed by a room-temperature Fabry- Perot (FP) interferometer in front of KIR. The FP selects narrow bandpass images while the grism spatially separates them, giving a 3-D spectroscopic capacity within a compact and light design. At each exposure, several (up to 9) monochromatic images of a rectangular field of about 36 arcseconds X 4 arc-seconds will be simultaneously acquired, allowing a precise subtraction of continuum and background. The cooled grism will guarantee a low background environment, thus a good sensitivity at K. The medium spectral resolution (about 2600) will fit to a number of programs and will represent a considerable improvement on imaging with narrow- band filters. Thus, combining high angular resolution with the spectroscopic diagnosis, GriF will allow the study of a large class of compact objects or structures, especially in the extragalactic domain where its sensitivity should be unique.

  2.  Bank sustainability reporting within GRI-G4 Framework

    Directory of Open Access Journals (Sweden)

    Ana Kundid Novokmet

    2016-09-01

    Full Text Available Sustainability accounting, with its final output – sustainability reporting, is a new field of accounting focused on evaluating and following up activities regarding a firm’s governance, environmental issues and social inclusion and interaction. Among several standardized frameworks, companies worldwide often choose the Global Reporting Initiative (GRI Sustainability Reporting Guidelines. Since the year 2000, GRI Guidelines have evolved and currently the fourth generation is in use. The aim of this study is to assess the latest form of sustainability reporting within an integrated report in the banking industry using the UniCredit Group, which operates in 15 countries, as an example. Sustainability reporting will soon become mandatory in the European Union (EU for large companies, listed companies and publicinterest entities (e.g. banks with an average of at least 500 employees, starting from the year 2018 (for activities in 2017. This paper is focused on a content analysis of the recent bank sustainability reporting with a critical review on this matter.

  3. 致密砂岩气藏润湿性对液相圈闭损害的影响%Effect of tight sandstone gas reservoir wettability on liquid traps damage

    Institute of Scientific and Technical Information of China (English)

    蒋官澄; 张弘; 吴晓波; 李颖颖; 张志行

    2014-01-01

    致密砂岩储层易因外来工作液入侵造成严重的液相圈闭损害,岩石表面润湿性对于液相圈闭损害程度具有重要影响。使用氟碳表面活性剂Zonyl8740处理岩心,降低岩心表面能,制得不同润湿程度的岩心。通过岩心驱替和毛管自发渗吸实验分别研究了气湿岩心和液湿岩心的束缚水饱和度、自吸油水动态;建立初始含水饱和度岩心流动实验,对比了钻井液加入气湿反转剂前后液相圈闭损害率。实验表明,致密砂岩表面由液湿反转为优先气湿可大幅度减弱毛管自吸效应、降低自吸液量和最终滞留饱和度。气湿反转剂可有效减少钻井液对储层液相圈闭损害。对预防致密砂岩储层液相圈闭损害具有一定指导意义。%In tight sandstone reservoirs, the liquid traps may be readily damaged by invasion of external work lfuid. The wettabiity of rock surface has a signiifcant impact on the damage degree to liquid traps. The lfuorocarbon surfactant Zonyl8740 was used to treat the cores, reduce the surface energy of the cores and obtain cores with different wetting degree. Through experiment on core displacement and capillary spontaneous imbibition, the irreducible water saturation and spontaneous imbibition oil/water dynamic of gas wet cores and liquid wet cores were studied respectively. The core lfow test with initial water saturation was built, and the damage degrees to liquid trap were compared, before and after gas-wet reversing agent was added to the drilling lfuid. Experiments show that inversion of liquid wetting on tight sandstone surface to preferential gas wetting can signiifcantly weaken the spontaneous imbibition effective of capillary, and reduce the spontaneous imbibition amount and the ifnal retained saturation. Gas wet reverse agent can effectively reduce the damage to liquid traps by drilling lfuid and has a guiding signiifcance to preventing damage to liquid traps in tight

  4. Opportunities and risks of hydraulic fraction treatment of tight gas-carrying rocks in redbeds; Chancen und Risiken hydraulischer Fracbehandlungen von dichten Erdgasspeichergesteinen im Rotliegenden

    Energy Technology Data Exchange (ETDEWEB)

    Buhrow, C. [BEB Erdgas und Erdoel GmbH, Hannover (Germany)

    1998-12-31

    In the last 20 years more and more hydraulic fraction treatments have been carried out in natural gas-carrying strata of the redbed. By pumping high-viscosity liquids into the rocks one attempts to control the fraction. Towards the end of the treatment the fraction is filled with a proppant in order to create a flow path with high permeability to the borehole after the pressure of the liquid drops. The trend moves from large-volume single fractures - more than 2000 cubic m of liquid as several tons of proppant were used in some cases -. to smaller fraction treatments consisting of a minimum of two fractures: the first one, which usually employs small amounts of liquid and proppant, serves to gain information on the deposit and its suitability for fraction treatment. The one or several fractures that follow serve to increase production or enlarge the drainage area. Ground pressure measurements can provide important information about the development of the fracture before, during and after fracturing. (orig.) [Deutsch] Seit ca. 20 Jahren werden vermehrt hydraulische Fracbehandlungen in den Erdgasspeichergesteinen des Rotliegenden durchgefuehrt. Durch Verpumpen von Fluessigkeiten hoher Viskositaet soll kontrolliert ein Riss `Frac` genannt, im Gebirge geschaffen werden. Dieser wird gegen Ende der Behandlung mit Stuetzmittel angefuellt, um nach Abfall des Fluessigkeitsdrucks einen bleibenden Fliessweg hoher Permeabilitaet zum Bohrloch zu schaffen. Dabei hat es eine Entwicklung von grossvolumigen Einzelfracs - in Einzelfaellen wurden mehr als 2.000 m{sup 3} Fluessigkeit und mehrere hundert Tonnen Stuetzmittel verpumpt - hin zu kleineren Fracbehandlungen aus zumindest zwei Fracs gegeben: Ziel des ersten, zumeist nur geringe Fluessigkeitsvolumina und Stuetzmittelmengen enthaltenen Fracs ist es, Informationen ueber die Lagerstaette und deren Fracbehandelbarkeit zu erlangen. Der oder die nachfolgenden Fracs dienen dann dem eigentlichen Ziel, der Produktionssteigerung und der

  5. Continuous Shearlet Tight Frames

    KAUST Repository

    Grohs, Philipp

    2010-10-22

    Based on the shearlet transform we present a general construction of continuous tight frames for L2(ℝ2) from any sufficiently smooth function with anisotropic moments. This includes for example compactly supported systems, piecewise polynomial systems, or both. From our earlier results in Grohs (Technical report, KAUST, 2009) it follows that these systems enjoy the same desirable approximation properties for directional data as the previous bandlimited and very specific constructions due to Kutyniok and Labate (Trans. Am. Math. Soc. 361:2719-2754, 2009). We also show that the representation formulas we derive are in a sense optimal for the shearlet transform. © 2010 Springer Science+Business Media, LLC.

  6. La nueva generación de GRI: Implicaciones para pequeñas y medianas empresas

    OpenAIRE

    Dante Pesce

    2006-01-01

    Presentación que ofrece información acerca de Global Reporting Initiative y el Reporte GRI. Da a conocer los principios de contenido, de calidad, así como los indicadores económicos, ambientales, sociales, suplementos sectoriales y mineros.

  7. GriFT: A device for quantifying physiological and pathological mirror movements in children.

    Science.gov (United States)

    Jaspers, E; Klingels, K; Simon-Martinez, C; Feys, H; Woolley, D G; Wenderoth, N

    2017-07-05

    Mirror movements (MM) typically occur during unilateral actions and manifest as involuntary muscle activity of the passive limb, which "mirror" voluntary actions executed by the contralateral homologous body part. They are a normal motor feature in young children and gradually disappear during the first decade of life. In children suffering from neurological disorders, e.g. due to an early brain lesion as in unilateral cerebral palsy, the amplitude and occurrence of MM has been proposed to yield relevant information for diagnosis and therapy. However, in clinical practice MM are typically assessed using an ordinal rating scale, which provides mainly qualitative information. In contrast, there is no validated procedure that allows a quantitative assessment that might offer more objective and detailed information regarding the occurrence and amount of MM. Here we introduce the Grip Force Tracking Device (GriFT Device), a portable system to quantitatively assess MM during repetitive unimanual squeezing whilst playing a computer game. The GriFT Device consists of two identical equally sized handles equipped with two compressive force sensors (range 0-23kg, Fz 1000Hz). Children had to complete three trials of unimanual squeezing, whereby the visual display on the screen determined the rhythm of squeezing (0.67Hz at 15% maximum voluntary contraction, force level adjusted per hand). MM were characterized based on their frequency, strength, and temporal features (synchronization and time lag). These MM characteristics differed significantly between children with different clinical MM scores, and MM frequency and strength were most discriminative. Further categorization of physiological MM based on their frequency and strength proved highly sensitive (89-97%). We demonstrated feasibility and validity of the GriFT Device in a large cohort of typically developing children aged 5 to 15 years, as well as its clinical applicability in children with unilateral cerebral palsy with

  8. Drenov Grič black limestone as a heritage stone from Slovenia

    Science.gov (United States)

    Kramar, Sabina; Rožič, Boštjan; Žbona, Nina; Bedjanič, Mojca; Mladenović, Ana

    2016-04-01

    The limestone known as Drenov Grič black limestone is considered one of the most beautiful Slovenian natural stones due to its homogenous black colour interwoven with white veins. Over the centuries it has been exploited from three major quarries west of Ljubljana, with the main quarry at Drenov Grič playing the primary role in supplying building material for the central parts of Slovenia. All the quarries are currently not active. In the area of Drenov grič, one locality of black limestone is protected - Kuclerjev kamnolom quarry. It has the status of 'valuable natural feature of national importance' and is protected as a natural monument. This well-stratified micritic limestone of Triassic (Carnian) age occurs in 10-80 cm thick beds, with thin marl interlayers. The stone contains abundant fossil bivalves and ostracods. Apart from calcite as the main component, dolomite, quartz, illite/muscovite and pyrite are also present. The limestone is relatively rich in carbonaceous and bituminous organic matter, which is responsible for the black colour of the stone. This component does not have any adverse effect on mechanical and physical characteristics. As the lime¬stone is dense, thus facilitating a good polish, it has been commercially considered as marble. The stone has been widely used in Slovenian monuments, not only in Ljubljana but also in other regions of Slovenia. Many inner and outdoor architectural elements were made of this limestone, particularly in the baroque period, which was known for the extensive use of black limestones also in other European countries. The most significant use of this limestone has been recorded in sculptured portals and altars. Some of the important buildings decorated utilising this stone, are the Ljubljana Cathedral, the St. James's Parish Church, and the Franciscan Church of the Annunciation, all of which are located in Ljubljana, some of them having been declared as cultural monuments of local or national importance. When

  9. Performance Analysis of a network using GriFT Monitoring Technique

    Directory of Open Access Journals (Sweden)

    Priya Kundal

    2012-08-01

    Full Text Available Fault tolerance is an influential field of concern while working in a grid. Sharing as its primary goal of evolvement, a Grid includes hardware, software, and heterogeneous resources from different organizations spread over large geographical area which would make it a complex behaviour system. With this composite nature grid systems are hard to manage and will result in a faulty system. To over-come this breach of failure a monitoring technique is required that could observe and analyze the performance of the environment and report the existence of faults. This paper presents the design, implementation and evaluation of the monitoring technique called GriFT which is developed using the concept of Grid Monitoring Architecture (GMA. The analysis is done by deploying it in a real laboratory set-up.

  10. Naturally fractured tight gas reservoirs detection optimization

    Energy Technology Data Exchange (ETDEWEB)

    Hoekstra, P. [Coleman Research Corp., Orlando, FL (United States)

    1995-04-01

    This contract is a joint project between METC and Louisiana Land and Exploration, planned to extend for 3 years. Substantial help and key information has been provided at the field by the owner/operator. All their well logs, cores, production data, geologic data, and geophysical data are available for study in this project. Their commitment in this technology development is demonstrated by their proposed contribution in the form of cost sharing: (1) obtaining the P-Wave (compressional wave) 3-D survey, (2) furnishing a borehole in which to acquire the 9-C vertical seismic profile (VSP), and (3) drilling and completing a test well for verification of the seismic anomaly. Also of significance is the direct involvement and participation of their professional staff. This staff has been responsible for generating and maintaining the database at the field and will form part of the team which evaluates the seismic data`s findings.

  11. Exploring ISO 26000 and Global Reporting Initiatives (GRI: a neo-institutional analysis of two CSR institutions

    Directory of Open Access Journals (Sweden)

    Reevany Bustami

    2013-01-01

    Full Text Available In the last decade or so, organizations have witnessed corporate social responsibility (CSR increasingly becoming part of the mainstream business practice and expectation. CSR has, in many ways been institutionalized as a standard practice for mainly large companies, especially MNCs. At various levels, ranging from individual company level to international level, a wide range of institutional arrangements and structures of CSR have been established, maintained and diffused in order to provide “a logic of appropriateness” and “give the expression and direction” (Campbell, 2006, p. 926 of CSR. However, in the context of institutionalization, these institutional arrangements of CSR have not been examined systematically. In particular, little attention has been given to the comparative analysis of two leading institutions of CSR: ISO 26000 and Global Reporting Initiatives (GRI. Adopting an analytical framework based on neo-institutional theory, this article explores and analyses both GRI and ISO 26000.

  12. Gry w podmiot. Szkic o (wczesnej twórczości Mladena Stilinovicia

    Directory of Open Access Journals (Sweden)

    Magdalena Bogusławska

    2016-10-01

    Full Text Available Games of a subject: A sketch of the (early works of Mladen Stilinović The article concerns the conceptualization of the subject in the works of the contemporary Croatian visual artist Mladen Stilinović. The object of analysis are most of all works (collages, texts from the 1970s and early 1980s, when the artist formulated the basis for his creative philosophy and at the same time determined the directions of their research. His system of reference were the socialist state order and the traditionalist, academic system of artistic practice, which he criticized from the perspectives of Diogenes, philosophical Cynicism and constructive anarchism. Until this day, the attitude of resistance is the main creative principle for Stilinović’s art. He sets strong, conscious and autonomous creator’s “I” against symbolic violence of different systems (political, ideological, educational, etc.. This “I” is not so much the material and object of expression as a space of play based on concpetualism and self-irony.   Gry w podmiot. Szkic o (wczesnej twórczości Mladena Stilinovicia Artykuł dotyczy konceptualizacji podmiotu w twórczości współczesnego chorwackiego artysty wizualnego – Mladena Stilinovicia. Przedmiotem analizy są przede wszystkim prace (kolaże, teksty z lat 70. i początku 80. XX wieku, kiedy to artysta formułował podstawy filozofii twórczej i określał kierunki swych poszukiwań. Układem odniesienia były dla niego wówczas socjalistyczny porządek państwa i tradycjonalistyczny, akademicki system praktyki artystycz­nej, które poddawał konsekwentnej krytyce z pozycji rozumnego, diogenesowskiego cynizmu i konstruktywnego anarchizmu. Do dziś postawa oporu jest dla Stilinovicia podstawową zasadą twórczą. Przemocy symbolicznej wszelkich systemów (politycznych, ideologicznych, edukacyjnych itp. przeciwstawia mocne, świadome i niezależne „ja” twórcy. Jest tu ono nie tyle tworzywem i przedmiotem ekspresji

  13. 连续型致密砂岩气近源累计聚集的特征及成因机制%Characteristics and Genetic Mechanism of Near-Source Accumulated Accumulation for Continuous-Type Tight-Sand Gas

    Institute of Scientific and Technical Information of China (English)

    郭迎春; 宋岩; 庞雄奇; 姜振学; 付金华; 杜建军

    2016-01-01

    Among the unconventional gas supply sources,tight-sand gas constitutes a significant percentage,which is the most available part under current technology.It can be divided into two types,continuous-type and trap-type.Geological and geo-chemical differences in characteristics on migration,accumulation,and distribution between trap-type and continuous-type tight-sand gas were compared systematically.Through physical simulation experiments,the dynamic genetic mechanism of near-source accumulation of continuous-type tight-sand gas was revealed.Trap-type tight-sand gas is the result of natural gas accumulation for a long migration distance with a good conducting system,causing an obvious fractionation on gas composition and carbon isotope and resulting in the following characteristics-“convergence in conventional traps,with edge and bottom wa-ter,high-quality sealing”.Continuous-type tight-sand gas is the result of near-source cumulative accumulation.Consequently, the gas composition and carbon isotope fractionation effect is unconspicuous,and discreteness exists among carbon isotopes in the same area.Different from trap-type,the continuous-type tight-sand gas exhibits the following characteristics such as “con-tinuous distribution,near-source aggregation,complex or inverted gas/water distribution”.The near-source accumulation of continuous-type tight-sand gas is consequence of counterbalance between force and resistance when gas migrates in nanoscale pore-throats developed in tight sandstone reservoirs.Before the natural gas migrates to the critical gas-water interface,it is separated into gas system and water system by the inversed gas-water interface.The gas migration force is abnormal gas pres-sure,while the need to generate buoyancy cannot be met.The gas migration resistances include overburden formation water pressure and capillary pressure.The magic trap of continuous-type tight-sand gas can be considered unconventional dynamic trap which core contents

  14. Study on gas accumulation modes of Xujiahe Formation tight sand gas reservoirs,in the middle of Western Sichuan De-pression,China%川西坳陷中段须家河组致密砂岩气藏成藏模式探讨

    Institute of Scientific and Technical Information of China (English)

    尚长健; 朱振宏; 欧光习; 王君; 楼章华

    2016-01-01

    通过分析流体包裹体均一温度和砂岩碳酸盐胶结物氧同位素数据,并结合沉积‐埋藏史,研究须家河组流体活动特征,进行储层致密化分析。在此基础上,结合烃源岩演化、储层致密化、流体活动等研究,探讨川西坳陷须家河组致密砂岩气藏成藏模式。认为:须家河组具有形成“连续型”气藏的地质条件,砂岩持续致密化,自烃源岩沉积后持续生烃,流体包裹体的显微观测也表明油气充注在持续进行。据此认为,须家河组气藏成藏模式是“前期边致密边成藏,后期裂缝发育成藏”。%Combined with the burial and thermal history of Western Sichuan Depression ,homogenization temperature of geofluid inclusion and oxygen isotope of carbonate cement are used to study the geofluid activity of Xujiahe For‐mation .And then sandstone densification is analyzed .A study on gas accumulation modes of tight sand gas reser‐voirs of Xujiahe Formation in the Western Sichuan Depression is conducted based on evolution of hydrocarbon source rocks ,sandstone densification and geofluid activities ,and so on .It concludes that (i) the Xujiahe Formation of Western Sichuan Depression meets all the factors of continuous tight sand gas reservoir ,(ii) the sandstone of Xujia‐he Formation continues to be identified ,(iii)source rocks of the Xujiahe Formation can continuously produce hydro‐carbon since their deposition ,and (iv)the microscopic observation of geofluid inclusion shows that hydrocarbon con‐tinuously charges .Based on the above results ,a model of the Xujiahe Formation gas accumulation is presented , namely gas accumulation is synchronization with sandstone densification in the earlier stage and gas accumulation re‐starts after cracks formed in the later stage .

  15. GRiP - A flexible approach for calculating risk as a function of consequence, vulnerability, and threat.

    Energy Technology Data Exchange (ETDEWEB)

    Whitfield, R. G.; Buehring, W. A.; Bassett, G. W. (Decision and Information Sciences)

    2011-04-08

    Get a GRiP (Gravitational Risk Procedure) on risk by using an approach inspired by the physics of gravitational forces between body masses! In April 2010, U.S. Department of Homeland Security Special Events staff (Protective Security Advisors [PSAs]) expressed concern about how to calculate risk given measures of consequence, vulnerability, and threat. The PSAs believed that it is not 'right' to assign zero risk, as a multiplicative formula would imply, to cases in which the threat is reported to be extremely small, and perhaps could even be assigned a value of zero, but for which consequences and vulnerability are potentially high. They needed a different way to aggregate the components into an overall measure of risk. To address these concerns, GRiP was proposed and developed. The inspiration for GRiP is Sir Isaac Newton's Universal Law of Gravitation: the attractive force between two bodies is directly proportional to the product of their masses and inversely proportional to the squares of the distance between them. The total force on one body is the sum of the forces from 'other bodies' that influence that body. In the case of risk, the 'other bodies' are the components of risk (R): consequence, vulnerability, and threat (which we denote as C, V, and T, respectively). GRiP treats risk as if it were a body within a cube. Each vertex (corner) of the cube represents one of the eight combinations of minimum and maximum 'values' for consequence, vulnerability, and threat. The risk at each of the vertices is a variable that can be set. Naturally, maximum risk occurs when consequence, vulnerability, and threat are at their maximum values; minimum risk occurs when they are at their minimum values. Analogous to gravitational forces among body masses, the GRiP formula for risk states that the risk at any interior point of the box depends on the squares of the distances from that point to each of the eight vertices. The risk

  16. GRiP: a computational tool to simulate transcription factor binding in prokaryotes.

    Science.gov (United States)

    Zabet, Nicolae Radu; Adryan, Boris

    2012-05-01

    Transcription factors (TFs) are proteins that regulate gene activity by binding to specific sites on the DNA. Understanding the way these molecules locate their target site is of great importance in understanding gene regulation. We developed a comprehensive computational model of this process and estimated the model parameters in (N.R.Zabet and B.Adryan, submitted for publication). GRiP (gene regulation in prokaryotes) is a highly versatile implementation of this model and simulates the search process in a computationally efficient way. This program aims to provide researchers in the field with a flexible and highly customizable simulation framework. Its features include representation of DNA sequence, TFs and the interaction between TFs and the DNA (facilitated diffusion mechanism), or between various TFs (cooperative behaviour). The software will record both information on the dynamics associated with the search process (locations of molecules) and also steady-state results (affinity landscape, occupancy-bias and collision hotspots). http://logic.sysbiol.cam.ac.uk/grip, program and source code

  17. Transferable Tight-Binding Potential for Hydrocarbons

    CERN Document Server

    Wang, Y; Wang, Yang

    1994-01-01

    A transferable tight-binding potential has been constructed for heteroatomic systems containing carbon and hydrogen. The electronic degree of freedom is treated explicitly in this potential using a small set of transferable parameters which has been fitted to small hydrocarbons and radicals. Transferability to other higher hydrocarbons were tested by comparison with ab initio calculations and experimental data. The potential can correctly reproduce changes in the electronic configuration as a function of the local bonding geometry around each carbon atom. This type of potential is well suited for computer simulations of covalently bonded systems in both gas-phase and condensed-phase systems.

  18. GRiP - A flexible approach for calculating risk as a function of consequence, vulnerability, and threat.

    Energy Technology Data Exchange (ETDEWEB)

    Whitfield, R. G.; Buehring, W. A.; Bassett, G. W. (Decision and Information Sciences)

    2011-04-08

    Get a GRiP (Gravitational Risk Procedure) on risk by using an approach inspired by the physics of gravitational forces between body masses! In April 2010, U.S. Department of Homeland Security Special Events staff (Protective Security Advisors [PSAs]) expressed concern about how to calculate risk given measures of consequence, vulnerability, and threat. The PSAs believed that it is not 'right' to assign zero risk, as a multiplicative formula would imply, to cases in which the threat is reported to be extremely small, and perhaps could even be assigned a value of zero, but for which consequences and vulnerability are potentially high. They needed a different way to aggregate the components into an overall measure of risk. To address these concerns, GRiP was proposed and developed. The inspiration for GRiP is Sir Isaac Newton's Universal Law of Gravitation: the attractive force between two bodies is directly proportional to the product of their masses and inversely proportional to the squares of the distance between them. The total force on one body is the sum of the forces from 'other bodies' that influence that body. In the case of risk, the 'other bodies' are the components of risk (R): consequence, vulnerability, and threat (which we denote as C, V, and T, respectively). GRiP treats risk as if it were a body within a cube. Each vertex (corner) of the cube represents one of the eight combinations of minimum and maximum 'values' for consequence, vulnerability, and threat. The risk at each of the vertices is a variable that can be set. Naturally, maximum risk occurs when consequence, vulnerability, and threat are at their maximum values; minimum risk occurs when they are at their minimum values. Analogous to gravitational forces among body masses, the GRiP formula for risk states that the risk at any interior point of the box depends on the squares of the distances from that point to each of the eight vertices. The risk

  19. Incidencia de la GRI-2002 en las emisiones de memorias sostenibles de empresas españolas

    OpenAIRE

    Alvarez Etxeberria, Igor; Garayar Erro, Ainoha

    2008-01-01

    Se aborda el caso de las memorias de sostenibilidad, se hace una revisión sobre los diferentes enfoques adoptados por organismos internacionales, públicos y privados y una incidencia del GRI a la hora de publicar memorias de sostenibilidad a nivel mundial, con especial hincapié en el caso español. Fil: Alvarez Etxeberria, Igor. Universidad Politécnica de Valencia. España Fil: Garayar Erro, Ainoha. Universidad del Pais Vasco/Euskal Erico Unibertsitatea. España

  20. THE IMPACT OF THE BUSINESS AND ORGANIZATIONAL SIZE OF A COMPANY ALONG WITH GRI AND CSR ADOPTION ON INTEGRATING SUSTAINABILITY REPORTING PRACTICES

    Directory of Open Access Journals (Sweden)

    Tiron-Tudor Adriana

    2012-07-01

    Full Text Available This paper intends to investigate the correlation between the business and organizational size of companies as well as GRI and CSR practices adoption, and the level of sustainability disclosure. The correlation is highlighted through SPSS statistic analysis and determination of an econometric model between a dependent variable - sustainability information disclosure - and five independent ones- sales, number of employees, GRI and CSR policies and ultimately reporting period/year -. We use the Deloitte Sustainability Scorecard for measuring the sustainability reporting practices. Our sample comprises companies that adopted integrated reporting for the period 2009-2010. Sample selection was made on the basis that sustainability reports are incorporated within the integrated reports. We assume to obtain a high correlation between the business and organizational size of companies, GRI and/or CSR polities and the level of sustainability information disclosed in our integrated reports.

  1. DETERMINANTES DA DIVULGAÇÃO DOS INDICADORES DE DESEMPENHO DA GRI NAS EMPRESAS DO BRASIL E DA ESPANHA

    Directory of Open Access Journals (Sweden)

    Alan Diógenes Góis

    2015-01-01

    Full Text Available O estudo tem por objetivo investigar os fatores determinantes da divulgação dos indicadores de desempenho de sustentabilidade da GRI nas empresas listadas nas bolsas do Brasil e da Espanha. Para tanto, foram analisados os dados de 94 empresas de capital aberto dos dois países que publicaram relatórios anuais e/ou de sustentabilidade, referentes a 2011, no padrão GRI-G3. A pesquisa é descritiva, com abordagem quantitativa dos dados, utilizando-se a Regressão Linear Múltipla para quatro modelos de disclosure (econômico, ambiental, social e de sustentabilidade. Os resultados mostram que as empresas da Espanha apresentam um nível de disclosure de sustentabilidade mais elevado, e que o nível de evidenciação geral, considerando o conjunto das dimensões da sustentabilidade (econômica, social e ambiental, corresponde a 72,7%. Quanto ao resultado dos modelos de regressão, observa-se que as variáveis independentes (Tamanho, Rentabilidade, Endividamento, Auditoria, Setor de Impacto Ambiental e Idade não explicam o disclosure econômico; porém, quanto aos disclosures ambiental, social e de sustentabilidade, as variáveis Tamanho e Idade são fatores determinantes.

  2. Carnian bauxite horizon on the Kopitov grič near Borovnica (Slovenia – is there a »forgotten« stratigraphic gap in its footwall?

    Directory of Open Access Journals (Sweden)

    Bogomir Celarc

    2008-12-01

    Full Text Available Beds underlying the Carnian bauxite on the Kopitov gri~ (Slovenia are by the author’s opinion not Carnian (Cordevolian, but Ladinian age. The considerable stratigraphical gap is presented between Carnian clastic rocks and underlying limestones and dolomites. Bauxite is result of the weathering during the emersion.

  3. 42 CFR 84.1142 - Isoamyl acetate tightness test; respirators designed for respiratory protection against dusts...

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Isoamyl acetate tightness test; respirators... Mist; Pesticide; Paint Spray; Powered Air-Purifying High Efficiency Respirators and Combination Gas Masks § 84.1142 Isoamyl acetate tightness test; respirators designed for respiratory protection...

  4. Micro pore and throat characteristics and moveable fluid variation of tight sandstone in 4th member of Xujiahe Formation, Xinchang Gas Field, western Sichuan Basin%川西新场须四段致密砂岩储层微观孔喉与可动流体变化特征

    Institute of Scientific and Technical Information of China (English)

    肖开华; 冯动军; 李秀鹏

    2014-01-01

    In order to evaluate the tight sandstone reservoirs in the 4th member of the Xujiahe Formation in the Xinchang area of the western Sichuan Basin, nuclear magnetic resonance and constant-rate mercury intrusion ex-periments have been carried out to quantitatively analyze micro pore and throat and moveable fluid variation char-acteristics. Studies have indicated that the moveable fluid parameters, throat parameters and pore parameters of tight sandstones vary largely. In micro-fractured tight sandstones, pores have an advantage over throats affecting the moveable fluid parameters, and the moveable fluid parameters are mainly controlled by pores. Low moveable fluid content and low producing degree of tight sandstones are mainly caused by the relatively long radius and wide distribution of pores and throats. In micro-fractured tight sandstones, the mercury saturation in throats is higher than that in pores, indicating that the dominant type of reservoir space is pore-fracture type in the 4th member of the Xujiahe Formation, the Xinchang Gas Field.%为了评价川西新场须四段致密砂岩储层,应用恒速压汞及核磁共振实验方法对储层微观孔喉与可动流体变化特征进行定量分析。结果表明,须四段致密砂岩储层可动流体参数、喉道特征参数及孔隙参数变化幅度大。微裂隙发育的致密砂岩储层孔隙对可动流体参数的影响较喉道要更大一些,在微观上可动流体参数主要受孔隙控制。孔喉半径比较大、分布范围宽是致密砂岩储层可动流体含量低、可动用程度差的主要原因之一。微裂隙发育的致密砂岩储层具有喉道进汞饱和度较孔隙进汞饱和度高的特点,说明新场须四段致密砂岩储层的储集空间类型主要为孔隙-裂缝型。

  5. Weakly tight functions and their decomposition

    Directory of Open Access Journals (Sweden)

    Mona Khare

    2005-01-01

    Full Text Available The present paper deals with the study of a weakly tight function and its relation to tight functions. We obtain a Jordan-decomposition-type theorem for a locally bounded weakly tight real-valued function defined on a sublattice of IX, followed by the notion of a total variation.

  6. Thermal Hydraulic Performance of Tight Lattice Bundle

    Science.gov (United States)

    Yamamoto, Yasushi; Akiba, Miyuki; Morooka, Shinichi; Shirakawa, Kenetsu; Abe, Nobuaki

    Recently, the reduced moderation spectrum BWR has been studied. The fast neutron spectrum is obtained through triangular tight lattice fuel. However, there are few thermal hydraulic test data and thermal hydraulic correlation applicable to critical power prediction in such a tight lattice bundle. This study aims to enhance the database of the thermal hydraulic performance of the tight lattice bundle whose rod gap is about 1mm. Therefore, thermal hydraulic performance measurement tests of tight lattice bundles for the critical power, the pressure drop and the counter current flow limiting were performed. Moreover, the correlations to evaluate the thermal-hydraulic performance of the tight lattice bundle were developed.

  7. Why tight-binding theory?

    Science.gov (United States)

    Harrison, Walter A.

    2002-12-01

    In the context of computational physics other methods are more accurate, but tight-binding theory allows very direct physical interpretation and is simple enough to allow much more realistic treatments beyond the local density approximation. We address several important questions of this last category: How does the gap enhancement from Coulomb correlations vary from material to material? Should the enhanced gap be used for calculating the dielectric constant? For calculating the effective mass in k-dot-p theory? How valid is the scissors approximation? How does one line up bands at an interface? How should we match the envelope function at interfaces in effective-mass theory? Why can the resulting quantum-well states seem to violate the uncertainty principle? How should f-shell electrons be treated when they are intermediate between band-like and core-like? The answers to all of these questions are given and discussed.

  8. Diagnosing the tight building syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, S.A.

    1987-12-01

    Formaldehyde is but one of many chemicals capable of causing the tight building syndrome or environmentally induced illness (EI). The spectrum of symptoms it may induce includes attacks of headache, flushing, laryngitis, dizziness, nausea, extreme weakness, arthralgia, unwarranted depression, dysphonia, exhaustion, inability to think clearly, arrhythmia or muscle spasms. The nonspecificity of such symptoms can baffle physicians from many specialties. Presented herein is a simple office method for demonstrating that formaldehyde is among the etiologic agents triggering these symptoms. The very symptoms that patients complain of can be provoked within minutes, and subsequently abolished, with an intradermal injection of the appropriate strength of formaldehyde. This injection aids in convincing the patient of the cause of the symptoms so he can initiate measure to bring his disease under control.

  9. Invasive tightly coupled processor arrays

    CERN Document Server

    LARI, VAHID

    2016-01-01

    This book introduces new massively parallel computer (MPSoC) architectures called invasive tightly coupled processor arrays. It proposes strategies, architecture designs, and programming interfaces for invasive TCPAs that allow invading and subsequently executing loop programs with strict requirements or guarantees of non-functional execution qualities such as performance, power consumption, and reliability. For the first time, such a configurable processor array architecture consisting of locally interconnected VLIW processing elements can be claimed by programs, either in full or in part, using the principle of invasive computing. Invasive TCPAs provide unprecedented energy efficiency for the parallel execution of nested loop programs by avoiding any global memory access such as GPUs and may even support loops with complex dependencies such as loop-carried dependencies that are not amenable to parallel execution on GPUs. For this purpose, the book proposes different invasion strategies for claiming a desire...

  10. Fingerprinting with Equiangular Tight Frames

    CERN Document Server

    Mixon, Dustin G; Kiyavash, Negar; Fickus, Matthew

    2011-01-01

    Digital fingerprinting is a framework for marking media files, such as images, music, or movies, with user-specific signatures to deter illegal distribution. Multiple users can collude to produce a forgery that can potentially overcome a fingerprinting system. This paper proposes an equiangular tight frame fingerprint design which is robust to such collusion attacks. We motivate this design by considering digital fingerprinting in terms of compressed sensing. The attack is modeled as linear averaging of multiple marked copies before adding a Gaussian noise vector. The content owner can then determine guilt by exploiting correlation between each user's fingerprint and the forged copy. The worst-case error probability of this detection scheme is analyzed and bounded. Simulation results demonstrate the average-case performance is similar to the performance of orthogonal and simplex fingerprint designs, while accommodating several times as many users.

  11. GLOBAL REPORTING INITIATIVE (GRI - UM ESTUDO EXPLORATÓRIO DA PRÁTICA DE EVIDENCIAÇÃO EM SUSTENTABILIDADE EMPRESARIAL NA AMÉRICA LATINA

    Directory of Open Access Journals (Sweden)

    Simone Freire Silva

    2012-12-01

    Full Text Available This paper proposes an exploratory study on the practice of disclosure on corporate sustainability (CS in companies from Brazil and other Latin American countries, taking as parameter the corporate sustainability report called Global Reporting Initiative (GRI. From the theoretical assumptions of the theory of voluntary disclosure and the theory of legitimacy, establishing reflections about their adherence to the communication process of companies in corporate sustainability. The study of the historical series from 1999 to 2010 identifies as Brazilian companies account for over 50% of corporate sustainability reports and Latin America as an area in which it consolidates the use of the GRI reporting in the world. Indicates assumptions in the development of new research that contributes to the development of methodologies of analysis, evaluation and interpretation of corporate sustainability performance of companies and to study the phenomena of disclosure, contributing to the strengthening of the variables of performance in corporate sustainability in the context stakeholder decision making.

  12. Establishment of action levels for quality control of IMRT flat panel: experience with the algorithm iGRiMLO; Establecimiento de niveles de accion para el control de calidad de IMRT con panel plano: experiencia con el algoritmo iGRiMLO

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, V.; Dolores, VV. de los; Pastor, V.; Martinez, J.; Gimeno, J.; Guardino, C.; Crispin, V.

    2011-07-01

    Algorithm has been used at our institution iGRiMLO scheduled for individual verification of treatment plans for intensity modulated radiotherapy (IMRT) step and shoot through portal dosimetry pretreatment of non-transmission, triggering the plan directly to a portal imaging device (EPID) of an amorphous silicon flat panel.

  13. Sea urchin Amblypygus dilatatus from Lower Eocene limestone in the Griža quarry in the Rižana river valley, Western Slovenia

    Directory of Open Access Journals (Sweden)

    Vasja Mikuž

    2004-06-01

    Full Text Available In paper irregular sea urchins of species Amblypygus dilatatus Agassiz & Desor, 1847 and accompaying foraminifer remains are considered. All of them were found in Lower Eocene – Cuisian limestones in the Griža quarry in the Rižana river valley. This is the first find of this species of sea urchins in Slovenia. The age of limestone was determined with nummulitinas.

  14. Tight Junctions in Salivary Epithelium

    Directory of Open Access Journals (Sweden)

    Olga J. Baker

    2010-01-01

    Full Text Available Epithelial cell tight junctions (TJs consist of a narrow belt-like structure in the apical region of the lateral plasma membrane that circumferentially binds each cell to its neighbor. TJs are found in tissues that are involved in polarized secretions, absorption functions, and maintaining barriers between blood and interstitial fluids. The morphology, permeability, and ion selectivity of TJ vary among different types of tissues and species. TJs are very dynamic structures that assemble, grow, reorganize, and disassemble during physiological or pathological events. Several studies have indicated the active role of TJ in intestinal, renal, and airway epithelial function; however, the functional significance of TJ in salivary gland epithelium is poorly understood. Interactions between different combinations of the TJ family (each with their own unique regulatory proteins define tissue specificity and functions during physiopathological processes; however, these interaction patterns have not been studied in salivary glands. The purpose of this review is to analyze some of the current data regarding the regulatory components of the TJ that could potentially affect cellular functions of the salivary epithelium.

  15. Gas utilization technologies

    Energy Technology Data Exchange (ETDEWEB)

    Biljetina, R.

    1994-09-01

    One of the constant challenges facing the research community is the identification of technology needs 5 to 15 years from now. A look back into history indicates that the forces driving natural gas research have changed from decade to decade. In the 1970s research was driven by concerns for adequate supply; in the 1980s research was aimed at creating new markets for natural gas. What then are the driving forces for the 1990s? Recent reports from the natural gas industry have helped define a new direction driven primarily by market demand for natural gas. A study prepared by the Interstate Natural Gas Association of America Foundation entitled ``Survey of Natural Research, Development, and Demonstration RD&D Priorities`` indicated that in the 1990s the highest research priority should be for natural gas utilization and that technology development efforts should not only address efficiency and cost, but environmental and regulatory issues as well. This study and others, such as the report by the American Gas Association (A.G.A.) entitled ``Strategic Vision for Natural Gas Through the Year 2000,`` clearly identify the market sectors driving today`s technology development needs. The biggest driver is the power generation market followed by the industrial, transportation, appliance, and gas cooling markets. This is best illustrated by the GRI 1994 Baseline Projection on market growth in various sectors between the year 1992 and 2010. This paper highlights some of the recent technology developments in each one of these sectors.

  16. Inventory non-conventional gas

    Energy Technology Data Exchange (ETDEWEB)

    Muntendam-Bos, A.G.; Wassing, B.B.T.; Ter Heege, J.H.; Van Bergen, F.; Schavemaker, Y.A.; Van Gessel, S.F.; De Jong, M.L.; Nelskamp, S.; Van Thienen-Visser, K.; Guasti, E.; Van den Belt; Marges, V.C. [TNO Built Environment and Geosciences, Utrecht (Netherlands)

    2009-10-15

    This report describes the results of the inventory for each non-conventional gas resource expected to be present in the Netherlands, which are: Tight Gas, Shallow gas, Coal bed Methane (CBM), Shale gas, Basin Centered Gas, Aquifer Gas and Stratigraphic traps.

  17. Bit Selection of Tight Gravel-bearing Sandstone Formation in Dongsheng Gas Field%东胜气田致密含砾砂岩地层钻头选型∗

    Institute of Scientific and Technical Information of China (English)

    陈晓华; 王翔; 杨大足; 张永清

    2016-01-01

    东胜气田整体岩性致密坚硬,研磨性强,钻头磨损严重,机械钻速低。为此,根据声波时差与地层岩石力学特性参数关系及岩石可钻性与声波时差的相关性,建立了东胜气田岩石可钻性级值计算模型,确定了岩石可钻性规律,并结合钻头磨损情况,进行钻头选型及设计优化,同时对优化后的钻头进行了现场应用。研究结果表明,东胜气田地层可钻性级值4~8,属中⁃硬地层,地层研磨性强;优化后的钻头可使全井机械钻速提高84%以上,单井使用钻头减少9只,节约成本63万元,收到了较好的效果。%Due to high density, hardness and abrasiveness of rocks in Dongsheng Gas Field, the bit is worn out and the rate of penetration is low�In order to solve this problem, a rock drillability value calculation model is built based on the relation between acoustic time and formation rock mechanics characteristic parameter and correla⁃tion between rock drillability and acoustic time, thereby the rock drillability pattern is determined, and bit selec⁃tion and design optimization are conducted based on bit wear and the optimized bit is applied on the site�Analysis results show that, formation rock drillability of Dongsheng Gas Field is 4 to 8, indicating the formation is a medi⁃um⁃hard formation with high abrasiveness; the optimized bit can improve the rate of penetration by more than 84%and less bits are used in each well to reduce the cost of RMB 630, 000 Yuan, achieving better results.

  18. Pore evolution and gas accumulation in tight sandstone reservoir of Member 2 of Xujiahe Formation in Yuanba area of Sichuan, China%四川元坝地区须二段致密砂岩储层孔隙演化与天然气成藏

    Institute of Scientific and Technical Information of China (English)

    王威

    2012-01-01

    Based on the quantitative statistics of the clasties and matrixes in the reservoir and quantitative evolutional analysis of pores, and according to the homogeneous temperature of inclusions and buried history of the reservoir, this paper makes an approach to the pore evolution and the natural gas accumulation in the tight sandstone reservoir of Member 2 of Xujiahe Formation (T3x2) of Upper Triassic in the Yuanba area of Sichuan Basin. The dynamic recovery of the compacted history of the reservoir is achieved. In the early diagenetic stage, the porosity of the reservoir declined to 8. 7%, meanwhile, the tight reservoir formed. Following this? A scries of cementations made the primary pores decreasing. The anisotropy is heightened, too. It can be known that the gas filling time of T3x2 in the Yuanba area is in the middle diagenetic stage A when the reservoir was tightened. Totally, "first is the compaction of reservoirs, and second is natural gas accumulation". The gas moves by "piston type advancing" in the reservoir. So the gas concentration is controlled by hydrocarbon-generating intensity and high quality reservoirs. Therefore, the depressed area in the eastern of Yuanba can be regarded as a favorable area for gas exploration.%利用储层中不同碎屑颗粒、填隙物的定量统计和孔隙在压实作用下的定量演化分析以及储层中包裹体均一温度,结合储层埋藏史分析等方法,探讨了四川盆地元坝地区上三叠统须二段致密砂岩储层孔隙演化与天然气成藏的关系.早成岩阶段结束时,储层的孔隙度已经降至8.7%,致密储层业已形成,此后一系列的胶结作用导致原生孔隙进一步减少,非均质性强.而元坝地区须二段天然气大规模充注时间为中成岩A期,此时储层巳经致密,总体反映出“储层先致密,天然气后成藏”的特点,天然气在储层中以“活塞式推进”方式运移,气藏富集主要受源岩的生烃强度

  19. Indicadores de Sustentabilidade como Instrumentos de Gestão: Uma Análise da GRI, Ethos E ISE

    Directory of Open Access Journals (Sweden)

    Eduardo Augusto da Silva

    2014-08-01

    Full Text Available A diversidade de indicadores que versam sobre assuntos próximos à sustentabilidade – a maioria deles foi desenvolvida por razões específicas: ambientais, econômicas, sociais e outros escopos, de forma que não podem ser considerados indicadores de sustentabilidade em si – é o reflexo de que o conceito ainda não atingiu um consenso universalmente aceito. O objetivo deste trabalho é analisar se os principais modelos e guias de avaliação das ações corporativas podem ser seguramente utilizados como critérios efetivos de certificação nos âmbitos da responsabilidade social corporativa (RSC e da sustentabilidade, sem configurar estratégias reducionistas de promoção da imagem institucional e mercadológica. A metodologia de pesquisa utilizada neste trabalho foi pesquisa bibliográfica, coleta de dados secundários em compêndios digitais e análise dos relatórios dos modelos de avaliação de RSC e de sustentabilidade, tanto da experiência internacional quanto os que dizem respeito à perspectiva brasileira. Foram analisados os indicadores GRI, Ethos e ISE. Os resultados principais da análise indicam que, na determinação de políticas de gestão organizacional, deve-se tomar o cuidado de envolver toda a organização no sentido de cumprir as prerrogativas dos modelos de avaliação de RSC e de sustentabilidade, pois, além do alto custo que isso pode gerar e dos esforços físicos, estruturais e pessoais de toda a organização, não significa a efetiva convergência de empresa responsável ou (equivocadamente sustentável.

  20. Improvement of methyl orange dye biotreatment by a novel isolated strain, Aeromonas veronii GRI, by SPB1 biosurfactant addition.

    Science.gov (United States)

    Mnif, Inès; Maktouf, Sameh; Fendri, Raouia; Kriaa, Mouna; Ellouze, Semia; Ghribi, Dhouha

    2016-01-01

    Aeromonas veronii GRI (KF964486), isolated from acclimated textile effluent after selective enrichment on azo dye, was assessed for methyl orange biodegradation potency. Results suggested the potential of this bacterium for use in effective treatment of azo-dye-contaminated wastewaters under static conditions at neutral and alkaline pH value, characteristic of typical textile effluents. The strain could tolerate higher doses of dyes as it was able to decolorize up to 1000 mg/l. When used as microbial surfactant to enhance methyl orange biodecolorization, Bacillus subtilis SPB1-derived lipopeptide accelerated the decolorization rate and maximized slightly the decolorization efficiency at an optimal concentration of about 0.025%. In order to enhance the process efficiency, a Taguchi design was conducted. Phytotoxicity bioassay using sesame and radish seeds were carried out to assess the biotreatment effectiveness. The bacterium was able to effectively decolorize the azo dye when inoculated with an initial optical density of about 0.5 with 0.25% sucrose, 0.125% yeast extract, 0.01% SPB1 biosurfactant, and when conducting an agitation phase of about 24 h after static incubation. Germination potency showed an increase toward the nonoptimized conditions indicating an improvement of the biotreatment. When comparing with synthetic surfactants, a drastic decrease and an inhibition of orange methyl decolorization were observed in the presence of CTAB and SDS. The nonionic surfactant Tween 80 had a positive effect on methyl orange biodecolorization. Also, studies ensured that methyl orange removal by this strain could be due to endocellular enzymatic activities. To conclude, the addition of SPB1 bioemulsifier reduced energy costs by reducing effective decolorization period, biosurfactant stimulated bacterial decolorization method may provide highly efficient, inexpensive, and time-saving procedure in treatment of textile effluents.

  1. Lifting scheme of symmetric tight wavelets frames

    Institute of Scientific and Technical Information of China (English)

    ZHUANG BoJin; YUAN WeiTao; PENG LiZhong

    2008-01-01

    This paper proposes a method to realize the lifting scheme of tight frame wavelet filters. As for 4-channel tight frame wavelet filter, the tight frame transforms' ma-trix is 2×4, but the lifting scheme transforms' matrix must be 4×4. And in the case of 3-channel tight frame wavelet filter, the transforms' matrix is 2×3, but the lifting scheme transforms' matrix must be 3×3. In order to solve this problem, we intro-duce two concepts: transferred polyphase matrix for 4-channel filters and trans-ferred unitary matrix for 3-channel filters. The transferred polyphase matrix is sym-metric/antisymmetric. Thus, we use this advantage to realize the lifting scheme.

  2. Trees, Tight-Spans and Point Configuration

    CERN Document Server

    Herrmann, Sven

    2011-01-01

    Tight-spans of metrics were first introduced by Isbell in 1964 and rediscovered and studied by others, most notably by Dress who gave them this name. Subsequently, it was found that tight-spans could be defined for more general maps, such as directed metrics and distances, and more recently for diversities. In this paper, we show that all of these tight-spans can be defined in terms of point configurations. This provides a useful way in which to study these objects in a unified and systematic way. We also show that by using point configurations we can recover results concerning one-dimensional tight-spans for all of the maps we consider, as well as extend these and other results to more general maps such as symmetric and unsymmetric maps.

  3. Expansion of Frames to Tight Frames

    Institute of Scientific and Technical Information of China (English)

    Deng Feng LI; Wen Chang SUN

    2009-01-01

    We show that every Bessel sequence (and therefore every frame) in a separable Hilbert space can be expanded to a tight frame by adding some elements. The proof is based on a recent generalization of the frame concept, the g-frame, which illustrates that g-frames could be useful in the study of frame theory. As an application, we prove that any Gabor frame can be expanded to a tight frame by adding one window function.

  4. Engineering support services for the DOE/GRI coal-gasification research program. Quarterly technical progress report, July-September 1982

    Energy Technology Data Exchange (ETDEWEB)

    Bostwick, L.E.; Ethridge, T.R.; Starr, D.W.; Koneru, P.B.; Hubbard, D.A.; Shah, K.V.; Smith, M.R.; Ward, W.E.; Wong, E.W.

    1982-01-01

    Pilot Plant and Process Development Unit Monitoring continued through August 1982; thereafter, such activities (and also MPC participation) were terminated in accordance with contract modifications. Testing monitored included PDU test run IP-033-1 and CFSF Tests TP-M005 and TP-M007-1 at Westinghouse, and wet carbonization PDU Test PB-5 at IGY. A draft report of the Westinghouse CFSF was issued for approval. Work on the descriptive brochure of the DOE/GRI Joint Program is nearly complete.

  5. Identificación y clasificación de los stakeholders en el marco GRI G3: aplicación metodológica

    OpenAIRE

    Palacios, Clide; Mendez, Silvana; Centro de Investigaciones en Auditoría y Responsabilidad Social

    2011-01-01

    Según el Marco de la Guía para la elaboración de Memorias de Sostenbilidad, GRI G3, el proceso de elaboración del balance social se puede describir en cinco fases: preparar, contactar, definir, supervisar y comunicar. Referido a la fase "contactar"; se realizó para el caso de una institución educativa una propuesta de aplicación de la metodología para identificar y clasificar a los grupos de interés según los criterios de: responsabilidad, influencia, cercanía, dependencia y representación me...

  6. Potential technical solutions to recover tight oil: Literature and simulation study of tight oil development

    OpenAIRE

    Zhang, Kai

    2014-01-01

    Over past decades, technology innovation drove unconventional resourcesbecome conventional. Incorporating the technologies applied in shale gasdevelopment, exploiting tight oil comes into stage recently. Advanced technology such as long horizontal wells combined with massivelyhydraulic fracturing was established as necessity to exploit tight oil reserve, however,primary recovery remains as low as 5.0-10.0% of original oil in place in tight oilreservoir with these technologies applied.[1] ...

  7. Androgen-Dependent Sertoli Cell Tight Junction Remodeling Is Mediated by Multiple Tight Junction Components

    National Research Council Canada - National Science Library

    Chakraborty, Papia; William Buaas, F; Sharma, Manju; Smith, Benjamin E; Greenlee, Anne R; Eacker, Stephen M; Braun, Robert E

    2014-01-01

    Sertoli cell tight junctions (SCTJs) of the seminiferous epithelium create a specialized microenvironment in the testis to aid differentiation of spermatocytes and spermatids from spermatogonial stem cells...

  8. Microscale Gas Chemistry

    Science.gov (United States)

    Mattson, Bruce; Anderson, Michael P.

    2011-01-01

    The development of syringes having free movement while remaining gas-tight enabled methods in chemistry to be changed. Successfully containing and measuring volumes of gas without the need to trap them using liquids made it possible to work with smaller quantities. The invention of the LuerLok syringe cap also allowed the gas to be stored for a…

  9. Boundary effect on liquid invasion in tight gas reservoirs

    Directory of Open Access Journals (Sweden)

    Li Gao

    2015-01-01

    Full Text Available Liquid invasion is an important transport phenomenon in many geophysical and environmental applications. A new capillary model considering boundary effect is proposed to reveal its mechanism. The boundary fluid layer not only reduces the effective flow radius, but also changes the viscosity of fluid. Thus the capillary force and viscosity resistance increases, however, the increase of capillary force is faster than that of viscosity resistance, therefore the invasion front arrives at the critical distance earlier.

  10. 适用于致密气藏钻完井的新型超级13Cr油钻杆管材性能测试%Performance test of a new super 13Cr oil drill pipe used for tight gas reservoir drilling and complication

    Institute of Scientific and Technical Information of China (English)

    曾德智; 田刚; 施太和; 侯铎; 贾华明; 卢强; 赵鹏

    2014-01-01

    A new high strength super 13Cr oil drill pipe was developed for tight gas reservoir exploitation in Tarim oilfield .This paper studies the tensile property and impact property of S135 dirll pipe and new super 13Cr oil drill pipe by a material tensile testing machine and a instrumen-ted impact testing machine respectively .Their corrosion resistance to CO2 is also studied through high temperature and high pressure autoclave test .The results show that the ultimate strength of the new super 13Cr steel reaches 976 MPa ,with the yielding strength 937 MPa and elongation 19 .0% .Its impact energy reaches 162 .82 J .Compared with S135 steel ,the new super 13Cr steel has similar strength property and better impact property .Under the test condition ,the corrosion rate of the super 13Cr steel is 0 .003 6 mm/a in gas phase and 0 .039 4 mm/a in liquid phase . Therefore ,the new super 13Cr oil drill pipe can meet the requirement of drilling and well compli-cation .The new oil drill pipe could provide support for tight gas reservoir nitrogen drilling and well complication .%为满足塔里木致密气藏氮气钻完井需求,研制了一种新型高强度超级13Cr油钻杆。采用M TS试验机对新型超级13Cr油钻杆和S135钻杆的强度性能进行了对比测试;采用示波冲击试验机对新型超级13Cr油钻杆和S135钻杆的冲击性能进行了对比测试;采用高温高压釜对新型超级13Cr油钻杆和S135钻杆的耐CO2腐蚀性能进行了对比测试。结果表明:新型超级13Cr油钻杆具有良好力学性能和耐腐蚀性能,其屈服强度937 M Pa、抗拉强度976 M Pa、延伸率为21.5%、室温冲击功162.82 J。其拉伸性能与S135接近,冲击性能明显优于S135;模拟工况下,新型超级13C r油钻杆气相腐蚀速率0.0036 m m/a、液相腐蚀速率0.0394 m m/a。因此,新型超级13C r油钻杆既能满足钻井的需要又能满足完井开采的要求,可为含C O 2致密砂岩气田氮气钻完井作业提供支持。

  11. Fabrication and Characterisation of the Graphene Ring Micro Electrode (GRiME with an Integrated, Concentric Ag/AgCl Reference Electrode

    Directory of Open Access Journals (Sweden)

    Colin Boxall

    2013-03-01

    Full Text Available Abstract: We report the fabrication and characterisation of the first graphene ring micro electrodes with the addition of a miniature concentric Ag/AgCl reference electrode. The graphene ring electrode is formed by dip coating fibre optics with graphene produced by a modified Hummers method. The reference electrode is formed using an established photocatalytically initiated electroless deposition (PIED plating method. The performance of the so-formed graphene ring micro electrodes (GRiMEs and associated reference electrode is studied using the probe redox system ferricyanide and electrode thicknesses assessed using established electrochemical methods. Using 220 µm diameter fibre optics, a ~15 nm thick graphene ring electrode is obtained corresponding to an inner to outer radius ratio of >0.999, so allowing for use of extant analytical descriptions of very thin ring microelectrodes in data analysis. GRiMEs are highly reliable (current response invariant over >3,000 scans, with the concentric reference electrode showing comparable stability (current response invariant over >300 scans. Furthermore the micro-ring design allows for efficient use of electrochemically active graphene edge sites and the associated nA scale currents obtained neatly obviate issues relating to the high resistivity of undoped graphene. Thus, the use of graphene in ring microelectrodes improves the reliability of existing micro-electrode designs and expands the range of use of graphene-based electrochemical devices.

  12. Nível de Adesão das Empresas atuantes no Mercado Capixaba ao Modelo de Relatório de Sustentabilidade GRI

    Directory of Open Access Journals (Sweden)

    Juliana Lobato Demonier

    2015-12-01

    Full Text Available Esta pesquisa tem como objetivo principal investigar qual o nível de adesão às diretrizes do modelo GRI G3 das cinco maiores empresas atuantes no mercado capixaba que adotaram esse modelo para elaboração do relatório de sustentabilidade no ano exercício de 2012. Para isso, foram selecionadas as maiores empresas que atuam nesse mercado, através do anuário do Instituto Euvaldo Lodi (IEL de 2012, tendo como critério o tamanho de sua receita. Para alcançar o objetivo proposto, utilizou-se o método análise de conteúdo dos relatórios. Os resultados evidenciaram que, mesmo com sete anos de existência desse modelo, as empresas ainda não aderiram plenamente ao modelo GRI G3. Através da análise das respostas aos índices dos relatórios, verificou-se que aproximadamente 65% dos indicadores foram atendidos de acordo com requisitos mínimos solicitados pelo modelo, o que aponta que essas empresas ainda têm muito a aperfeiçoar, a fim de transmitir aos usuários maior transparência em seus relatórios.

  13. Characteristics and Mechanism of Permian Shanxi Tight Reservoir of Changbei Gas Field,Ordos Basin%鄂尔多斯盆地长北气田山西组二段低孔低渗储层特征及形成机理

    Institute of Scientific and Technical Information of China (English)

    孙海涛; 钟大康; 张湘宁; 柳慧林

    2011-01-01

    Changbei gas field is located in Yishan Slope of the northern center of the Ordos Basin,China.The main pay zone reservoir is Upper Paleozoic Lower Permian Shanxi P1S2 quartz arenite,which deposited in distributary channel of delta plain.The reservoir is low porosity low permeability tight reservoir with average porosity of 5.2% and average permeability of 0.7×10-3 μm2 in a current depth of 2 700~2 950 m.Integrated study on depositional environment,lithology,diagenesis and tectonic background has been conducted.The reasons cause this low porosity low permeability tight reservoir features are considered as the following two factors.(1) On one hand,the reservoir was deposited in a coaly bearing acid environment of deltaic distributary channel,the original pore water is acid water with non saturated calcium carbonate,which can not form earlier cementation within the sandstone reservoir.However,compaction has significantly reduce the original pore and pore volume.On the other hand,this acid diagenesis environment cause large amounts of secondary quartz cementation fill the pores left out during compaction of sandstone reservoir.This is the main reasons cause the low porosity low permeability tight reservoir features in the region.Observation from thin section indicate that calcium carbonate cementation is not developed in the pore of sandstone reservoir especially in the earlier stage,the average component of calcium carbonate cementation is 1%~3%,authigenic kaolinite cementation is well developed with an average component of 7%~10%,illite segmentation is also less developed 3%,secondary quartz cementation well develop,mostly reach Ⅱ—Ⅲ level with an average component of 5%~10%,some layer can reach 10%~18% and maximum is 23%,this phenomenon indicated the acid diagenesis environment of P1S2 quartz arenite reservoir in Changbei gas field.(2) Tectonic study indicated that Changbei gas field is located in Ordos Basin tectonically stable at the time

  14. Opportunities to reduce methane emissions in the natural gas industry

    Energy Technology Data Exchange (ETDEWEB)

    Cowgill, R.M. [Radian Corporation, Austin, TX (United States)

    1995-12-31

    The U.S. Environmental Protection Agency (EPA) and the Gas Research Institute (GRI) cofunded a project to quantify methane (CH{sub 4}) emissions from the U.S. natural gas industry. Methane, the major constituent of natural gas, is a potent greenhouse gas that is believed to increase the effect of global warming when released to the atmosphere. Reducing emissions from natural gas systems would lessen the greenhouse gas effect attributable to atmospheric CH{sub 4}. Further, mitigation methods to reduce emissions of natural gas, a marketable resource, could save money and increase energy efficiency. This presentation summarizes the major sources and quantity of methane being emitted to the atmosphere for all segments of the U.S. gas industry: production; processing; storage; transmission; and distribution. A description of how those emissions were determined is included here, as well as a discussion of which sources are potential candidates for reducing emissions. (author)

  15. Topological games and productively countably tight spaces

    OpenAIRE

    2013-01-01

    The two main results of this work are the following: if a space $X$ is such that player II has a winning strategy in the game $\\gone(\\Omega_x, \\Omega_x)$ for every $x \\in X$, then $X$ is productively countably tight. On the other hand, if a space is productively countably tight, then $\\sone(\\Omega_x, \\Omega_x)$ holds for every $x \\in X$. With these results, several other results follow, using some characterizations made by Uspenskii and Scheepers.

  16. Classifying tight Weyl-Heisenberg frames

    DEFF Research Database (Denmark)

    Cazsazza, P.; Janssen, A. J. E. M.; Christensen, Ole

    1999-01-01

    A Weyl-Heisenberg frame for L^2(R) is a frame consisting of translates and modulates of a fixed function. In this paper we give necessary and sufficient conditions for this family to form a tight WH-frame. This allows us to write down explicitly all functions g for which all translates and modula......A Weyl-Heisenberg frame for L^2(R) is a frame consisting of translates and modulates of a fixed function. In this paper we give necessary and sufficient conditions for this family to form a tight WH-frame. This allows us to write down explicitly all functions g for which all translates...

  17. Tight Focusing of Partially Coherent Vortex Beams

    Directory of Open Access Journals (Sweden)

    Rakesh Kumar Singh

    2012-01-01

    Full Text Available Tight focusing of partially polarized vortex beams has been studied. Compact form of the coherence matrix has been derived for polarized vortex beams. Effects of topological charge and polarization distribution of the incident beam on intensity distribution, degree of polarization, and coherence have been investigated.

  18. Tight adversary bounds for composite functions

    NARCIS (Netherlands)

    Hoyer, P.; Spalek, R.

    2005-01-01

    The quantum adversary method is a very versatile method for proving lower bounds on quantum algorithms. It has many equivalent formulations, yields tight bounds for many computational problems, and has natural connections to classical lower bounds. One of its formulations is in terms of the spectral

  19. A Tight Bound for the Lamplighter Problem

    OpenAIRE

    Ganapathy, Murali K.; Tetali, Prasad

    2006-01-01

    We settle an open problem, raised by Y. Peres and D. Revelle, concerning the $L^2$ mixing time of the random walk on the lamplighter graph. We also provide general bounds relating the entropy decay of a Markov chain to the separation distance of the chain, and show that the lamplighter graphs once again provide examples of tightness of our results.

  20. An Objective Measure of Noseband Tightness and Its Measurement Using a Novel Digital Tightness Gauge

    Science.gov (United States)

    Casey, Vincent

    2017-01-01

    Noseband tightness is difficult to assess in horses participating in equestrian sports such as dressage, show jumping and three-day-eventing. There is growing concern that nosebands are commonly tightened to such an extent as to restrict normal equine behaviour and possibly cause injury. In the absence of a clear agreed definition of noseband tightness, a simple model of the equine nose-noseband interface environment was developed in order to guide further studies in this area. The normal force component of the noseband tensile force was identified as the key contributor to sub-noseband tissue compression. The model was used to inform the design of a digital tightness gauge which could reliably measure the normal force component of the noseband tensile force. A digital tightness gauge was developed to measure this parameter under nosebands fitted to bridled horses. Results are presented for field tests using two prototype designs. Prototype version three was used in field trial 1 (n = 15, frontal nasal plane sub-noseband site). Results of this trial were used to develop an ergonomically designed prototype, version 4, which was tested in a second field trial (n = 12, frontal nasal plane and lateral sub-noseband site). Nosebands were set to three tightness settings in each trial as judged by a single rater using an International Society for Equitation Science (ISES) taper gauge. Normal forces in the range 7–95 N were recorded at the frontal nasal plane while a lower range 1–28 N was found at the lateral site for the taper gauge range used in the trials. The digital tightness gauge was found to be simple to use, reliable, and safe and its use did not agitate the animals in any discernable way. A simple six point tightness scale is suggested to aid regulation implementation and the control of noseband tightness using normal force measurement as the objective tightness discriminant. PMID:28045955

  1. Urbanistid ja keskkonnaeksperdid: iga muudatuse eest Reidi tee projektis oleme pidanud võitlema / Helen Sooväli-Sepping, Kristi Grišakov, Mari Jüssi ; intervjueerinud Mari Peegel ; kommenteerinud Taavi Aas

    Index Scriptorium Estoniae

    Sooväli-Sepping, Helen, 1974-

    2016-01-01

    TLÜ keskkonnakorralduse professor ja linnakorralduse õppekava juht Helen Sooväli-Sepping, TTÜ maastikuarhitektuuri õppekava juht ja linnaplaneerija-urbanist Kristi Grišakov ning Stockholmi keskkonnainstituudi Tallinna keskuse liikuvus- ja keskkonnaekspert Mari Jüssi kinnitavad, et Reidi tee projekt ei ole endiselt inimsõbralik

  2. Urbanistid ja keskkonnaeksperdid: iga muudatuse eest Reidi tee projektis oleme pidanud võitlema / Helen Sooväli-Sepping, Kristi Grišakov, Mari Jüssi ; intervjueerinud Mari Peegel ; kommenteerinud Taavi Aas

    Index Scriptorium Estoniae

    Sooväli-Sepping, Helen, 1974-

    2016-01-01

    TLÜ keskkonnakorralduse professor ja linnakorralduse õppekava juht Helen Sooväli-Sepping, TTÜ maastikuarhitektuuri õppekava juht ja linnaplaneerija-urbanist Kristi Grišakov ning Stockholmi keskkonnainstituudi Tallinna keskuse liikuvus- ja keskkonnaekspert Mari Jüssi kinnitavad, et Reidi tee projekt ei ole endiselt inimsõbralik

  3. 致密砂岩气藏可动流体赋存特征的微观地质因素:以苏里格气田东部盒8段储层为例%Microscopic Geological Factors of Movable Fluid Distribution in the Tight Sandstone Gas Reservoir:Taking the He 8 Reservoir in the East of Sulige Gas Field as An Example

    Institute of Scientific and Technical Information of China (English)

    任大忠; 孙卫; 卢涛; 李跃刚; 张茜; 周楷

    2015-01-01

    Taking the He 8 tight sandstone gas reservoir in the east of Sulige gas field as an example,the authors conducted a series of experiments including nuclear magnetic resonance,constant-speed mercury injection, casting thin slice,reservoir property,X-ray and so on.With all these techniques,we discussed the microscop-ic geological factors which affect the distribution of movable fluid.The researches show that:the saturation of movable fluid in He 8 reservoir was low while the distribution of T2 spectrum was bimodal pattern with high left side and low right side.The filling of clay mineral and pore types were the key factors that resulted in complicat-ed pore structures.Pore structure had great impact on the saturation of movable fluid.Facial porosity,throat ra-dius,the rate of pore radius and throat radius were the key factors which affected the saturation of movable flu-id.The effective pore volume and sorting coefficients affected the saturation of movable fluid obviously,while the physical properties of reservoir,clay mineral,effective throat volume and pore radius had moderate effect on the saturation of movable fluid.%以苏里格气田东部盒8段典型的致密砂岩气藏为例,运用核磁共振、恒速压汞、铸体薄片、物性、X -衍射等实验资料,探讨了影响可动流体赋存差异的微观地质因素。结果表明,盒8段储层可动流体饱和度低,T2谱分布均为左高峰右低峰的双峰态;黏土矿物的充填与孔隙类型是孔隙结构复杂的重要因素,孔隙结构是影响可动流体赋存特征的关键;面孔率、喉道半径、孔喉半径比是影响可动流体饱和度的主要因素,有效孔隙体积、分选系数对可动流体饱和度影响明显,储层物性、黏土矿物、有效喉道体积、孔隙半径对可动流体饱和度影响较弱。

  4. Terrestrial tight oil reservoir characteristics and Graded Resource Assessment in China

    Science.gov (United States)

    Wang, Shejiao; Wu, Xiaozhi; Guo, Giulin

    2016-04-01

    China. The porosity is 2-14%(average 5-10%)and the permeability is less than 1mD. The laboratory test and exploration practice confirmed that the oil content was positively related to physical property. The higher the porosity, the better the oil content will have. (3) Source rock and reservoir are superimposed. From the contact relationship of source rock and reservoir, the reservoir developed in the source rock has the advantage of capturing oil and gas, so the oil saturation can be as high as 70-80%. (4) The increased pressure caused by hydrocarbon generation and the connected fracture are the key factors for tight oil accumulation. The Fuyu tight oil formed underling source rock in Songliao Basin is a good example. The fracture system is the key factor for tight oil accumulation. Considering the strong heterogeneity of terrestrial tight oil reservoir in china, we create hierarchical resource abundance analogy, EUR analogy, cell element volumetric methods to evaluate tight oil resource potential. In order to find exploration "sweet spots", establishing tight oil resource classification evaluation standards are key steps to objectively evaluate tight oil resource distribution. The resource classification evaluation standards are established by the relationship analysis between reservoir properties and oil properties, and the correlation analysis between production, resource abundance, and reservoir thickness. The first-grade tight oil resource, which is recently available and can easily be developed, has following main parameters: the porosity is greater than 8%, thickness is over 10m, resource abundance is above 150,000 tons / km2, and pressure coefficient is greater than 1.3; The second-grade tight oil resource is currently unavailable, but with advanced technology can expected to be developed. The main parameters are as following: the porosity is 5% -8%, thickness is less than 5-10m, resource abundance is 50000-150000 tons / km2, the pressure coefficient is 1.0 to

  5. GLOBAL REPORTING INITIATIVE (GRI - UM ESTUDO EXPLORATÓRIO DA PRÁTICA DE EVIDENCIAÇÃO EM SUSTENTABILIDADE EMPRESARIAL NA AMÉRICA LATINA

    Directory of Open Access Journals (Sweden)

    Sérgio Henrique Conceição

    2012-12-01

    Full Text Available O presente trabalho propõe um estudo exploratório sobre a prática de evidenciação em sustentabilidade empresarial (SE em companhias do Brasil e demais países da América Latina, tomando como parâmetro o relatório de sustentabilidade empresarial denominado Global Reporting Initiative (GRI. A partir dos pressupostos teóricos da teoria da divulgação voluntária e da teoria de legitimidade, estabelece reflexões acerca da sua aderência ao processo de comunicação em sustentabilidade empresarial das companhias. O estudo da série histórica a partir de 1999 até 2010 identifica as companhias brasileiras como responsáveis por mais de 50% dos informes de sustentabilidade empresarial e a América Latina enquanto espaço em que se consolida a utilização do relatório GRI no mundo. Indica pressupostos no desenvolvimento de novas pesquisas que contribuam para a concepção de metodologias de análise, avaliação e interpretação do desempenho em sustentabilidade empresarial das companhias e para o estudo dos fenômenos de sua divulgação, contribuindo para o fortalecimento das variáveis do desempenho em sustentabilidade empresarial no contexto decisório dos stakeholders.

  6. Tight-binding treatment of conjugated polymers

    DEFF Research Database (Denmark)

    Lynge, Thomas Bastholm

    This PhD thesis concerns conjugated polymers which constitute a constantly growing research area. Today, among other things, conjugated polymers play a role in plastic based solar cells, photodetectors and light emitting diodes, and even today such plastic-based components constitute an alternative...... of tomorrow. This thesis specifically treats the three conjugated polymers trans-polyacetylene (tPA), poly(para-phenylene) (PPP) and poly(para-phe\\-nylene vinylene) (PPV). The present results, which are derived within the tight-binding model, are divided into two parts. In one part, analytic results...... are derived for the optical properties of the polymers expressed in terms of the optical susceptibility both in the presence and in the absence of a static electric field. In the other part, the cumputationally efficient Density Functional-based Tight-Binding (DFTB) model is applied to the description...

  7. Discussions on the gas source of the Triassic Xujiahe Formation tight sandstone gas reservoirs in Yuanba and Tongnanba, Sichuan Basin:An answer to Yinfeng et al.%四川盆地元坝和通南巴地区须家河组致密砂岩气藏气源探讨--兼答印峰等

    Institute of Scientific and Technical Information of China (English)

    戴金星; 廖凤蓉; 倪云燕

    2013-01-01

    Gas-source correlation is generally focused on the genetic type of the main gas components, dominantly oil-associated gas or coal-derived gas. Gases from the Yuanba and Tongnanba gas reservoirs are dominated by methane with an average content of 95.36%. The average contents of ethane, propane, butane are 1.60%, 0.29%and 0.09%, respectively. In general, for the Yuanba and Tongnanba gas reservoirs, alkane gas has an average content of 97.34%, and CO2 has an average content of 0.63%, which only accounts for 6.5‰of the methane. According to the discrimination criteria thatδ13C2 value is greater than–28‰for coal-derived gas and lower than–28.5‰for the oil-associated gas, Yin et al. suggested that the gases from the Yuanba gas reservoir be a mixture of coal-derived and oil-associated gases, and the gases from the Tongnanba gas reservoir be oil-associated gas. However, the discrimination criteria of δ13C2 for coal-derived and oil-associated gases are only valid when the alkane gases have not undergone secondary alteration and have positive carbon isotopic series among C1-C4 alkanes. Hence, it is concluded that gases from the Yuanba and Tongnanba gas reservoirs are coal-derived gases due to their high content and heavy carbon isotopic values of methane (–31.3‰), which is typical for high mature coal-derived gases in the world. Though Yin et al. suggested that abiogenic CO2 of these two reservoirs is originated from metamorphism or hydrolysis of deep carbonate rocks, we proposed that these CO2 gases be self-generated and self-accumulated under the corrosion of calcarenaceous sandstone of the Triassic Xujiahe Formation.%  气藏的气源系指其中主要组分气的成因类型,通常为油型气或煤成气.元坝和通南巴气藏主要组分甲烷平均含量为95.36%,乙烷、丙烷和丁烷平均含量分别为1.60%、0.29%和0.09%,烷烃气总平均含量为97.34%,而 CO2平均含量仅0.63%,为甲烷的6.5‰.印峰等文中仅应用δ13

  8. Evaluation of reduced chemical kinetic mechanisms used for modeling mild combustion for natural gas

    Directory of Open Access Journals (Sweden)

    Hamdi Mohamed

    2009-01-01

    Full Text Available A numerical and parametric study was performed to evaluate the potential of reduced chemistry mechanisms to model natural gas chemistry including NOx chemistry under mild combustion mode. Two reduced mechanisms, 5-step and 9-step, were tested against the GRI-Mech3.0 by comparing key species, such as NOx, CO2 and CO, and gas temperature predictions in idealized reactors codes under mild combustion conditions. It is thus concluded that the 9-step mechanism appears to be a promising reduced mechanism that can be used in multi-dimensional codes for modeling mild combustion of natural gas.

  9. Laboratory Measurement and Interpretation of the Changes of Physical Properties after Heat Treatment in Tight Porous Media

    Directory of Open Access Journals (Sweden)

    Yili Kang

    2015-01-01

    Full Text Available Prevention of water blocking and optimization of multiscale flow channels will increase gas production of tight reservoirs. Physical properties of samples from representative tight gas reservoirs were measured before and after high temperature treatment. Results show that, with the increase of treatment temperature, mass decreases, acoustic transit time increases, and permeability and porosity increase. Permeability begins to increase dramatically if treatment temperature exceeds the threshold value of thermal fracturing, which is 600~700°C, 500~600°C, 300~500°C, and 300~400°C for shale, mudstone, tight sandstone, and tight carbonate rock, respectively. Comprehensive analyses indicate that the mechanisms of heat treatment on tight porous media include evaporation and dehydration of water, change of mineral structure, generation of microfracture, and network connectivity. Meanwhile, field implementation is reviewed and prospected. Interpretations indicate that, according to the characteristics of multiscale mass transfer in tight gas formation, combining heat treatment with conventional stimulation methods can achieve the best stimulation result.

  10. Atom laser dynamics in a tight waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Campo, A del; Lizuain, I; Muga, J G [Departamento de Quimica-Fisica, UPV-EHU, Apartado. 644, Bilbao (Spain); Pons, M [Departamento de Fisica Aplicada I, E.U.I.T. de Minas y Obras Publicas, UPV-EHU, 48901 Barakaldo (Spain); Moshinsky, M [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20-364, 01000 Mexico D.F. (Mexico)], E-mail: adolfo.delcampo@ehu.es

    2008-02-15

    We study the transient dynamics that arise during the formation of an atom laser beam in a tight waveguide. The time dependent density profile develops a series of wiggles which are related to the diffraction in time phenomenon. The apodization of matter waves, which relies on the use of smooth aperture functions, allows to suppress such oscillations in a time interval, after which there is a revival of the diffraction in time. The revival time scale is directly related to the inverse of the harmonic trap frequency for the atom reservoir.

  11. Inward Leakage in Tight-Fitting PAPRs

    Directory of Open Access Journals (Sweden)

    Frank C. Koh

    2011-01-01

    Full Text Available A combination of local flow measurement techniques and fog flow visualization was used to determine the inward leakage for two tight-fitting powered air-purifying respirators (PAPRs, the 3M Breathe-Easy PAPR and the SE 400 breathing demand PAPR. The PAPRs were mounted on a breathing machine head form, and flows were measured from the blower and into the breathing machine. Both respirators leaked a little at the beginning of inhalation, probably through their exhalation valves. In both cases, the leakage was not enough for fog to appear at the mouth of the head form.

  12. TIGHT-BINDING DESCRIPTION OF TICx

    Directory of Open Access Journals (Sweden)

    V.I.Ivashchenko

    2004-01-01

    Full Text Available A parametrized non-orthogonal tight-binding (TB method combined with the coherent-potential-approximation is applied to the study of the electronic structure of disordered off-stoichiometric TiCx, the lattice relaxation and the electronic spectra of the TiC (001 surface, the local relaxation and energetic states of TiC structures with one or two vacancies in both the non-metal and metal sublattices. The calculated results are in good agreement with available experimental and theoretical data. The importance of the overlap matrix elements of the TB Hamiltonian in describing the electronic structure of this class of compounds is emphasized.

  13. Tight Reference Frame–Independent Quantum Teleportation

    Directory of Open Access Journals (Sweden)

    Dominic Verdon

    2017-01-01

    Full Text Available We give a tight scheme for teleporting a quantum state between two parties whose reference frames are misaligned by an action of a finite symmetry group. Unlike previously proposed schemes, ours requires no additional tokens or data to be passed between the participants; the same amount of classical information is transferred as for ordinary quantum teleportation, and the Hilbert space of the entangled resource is of the same size. In the terminology of Peres and Scudo, our protocol relies on classical communication of unspeakable information.

  14. An Integrated Rock Typing Approach for Unraveling the Reservoir Heterogeneity of Tight Sands in the Whicher Range Field of Perth Basin, Western Australia

    DEFF Research Database (Denmark)

    Ilkhchi, Rahim Kadkhodaie; Rezaee, Reza; Harami, Reza Moussavi;

    2014-01-01

    Tight gas sands in Whicher Range Field of Perth Basin show large heterogeneity in reservoir characteristics and production behavior related to depositional and diagenetic features. Diagenetic events (compaction and cementation) have severely affected the pore system. In order to investigate...

  15. Potential evaluation of CO2 storage and enhanced oil recovery of tight oil reservoir in the Ordos Basin, China.

    Science.gov (United States)

    Tian, Xiaofeng; Cheng, Linsong; Cao, Renyi; Zhang, Miaoyi; Guo, Qiang; Wang, Yimin; Zhang, Jian; Cui, Yu

    2015-07-01

    Carbon -di-oxide (CO2) is regarded as the most important greenhouse gas to accelerate climate change and ocean acidification. The Chinese government is seeking methods to reduce anthropogenic CO2 gas emission. CO2 capture and geological storage is one of the main methods. In addition, injecting CO2 is also an effective method to replenish formation energy in developing tight oil reservoirs. However, exiting methods to estimate CO2 storage capacity are all based on the material balance theory. This was absolutely correct for normal reservoirs. However, as natural fractures widely exist in tight oil reservoirs and majority of them are vertical ones, tight oil reservoirs are not close. Therefore, material balance theory is not adaptive. In the present study, a new method to calculate CO2 storage capacity is presented. The CO2 effective storage capacity, in this new method, consisted of free CO2, CO2 dissolved in oil and CO2 dissolved in water. Case studies of tight oil reservoir from Ordos Basin was conducted and it was found that due to far lower viscosity of CO2 and larger solubility in oil, CO2 could flow in tight oil reservoirs more easily. As a result, injecting CO2 in tight oil reservoirs could obviously enhance sweep efficiency by 24.5% and oil recovery efficiency by 7.5%. CO2 effective storage capacity of Chang 7 tight oil reservoir in Longdong area was 1.88 x 10(7) t. The Chang 7 tight oil reservoir in Ordos Basin was estimated to be 6.38 x 10(11) t. As tight oil reservoirs were widely distributed in Songliao Basin, Sichuan Basin and so on, geological storage capacity of CO2 in China is potential.

  16. Bioabsorbable thread for tight tying of bones.

    Science.gov (United States)

    Hattori, K; Tomita, N; Tamai, S; Ikada, Y

    2000-01-01

    The purpose of this research was to develop a bioabsorbable thread for tight fixation of fractured bones and to examine its mechanical performance in an in-vitro simulation study. The thread is a blend of bioabsorbable poly(L-lactic acid); (PLLA) and poly(epsilon-caprolactone); (PCL) fibers and can be tightly connected by fusion welding of the PCL fibers. The tying strength of the PLLA-PCL blend thread was 39.7 N, which was comparable to that of stainless steel wire. A testing machine was fabricated to measure the fatigue strength of the tying by simulating bone fixation. The results showed that metal wires always failed because of breakage within 25,000 loading cycles, whereas the blend threads did not fail until 50,000 loading cycles. The looseness of tying for simulated bone fixation by the blend thread was within 1mm even after 50 000 loading cycles. In-vivo testing using rats revealed that the blend thread did not cause any severe inflammatory reaction.

  17. Global Reporting Initiative (GRI: uma análise da adesão as diretrizes pelas empresas listadas no novo mercado sob a perspectiva das teorias institucional e da legitimidade

    Directory of Open Access Journals (Sweden)

    Gabriela Dias da Silva

    2015-05-01

    Full Text Available O estudo se propõe analisar, sob a perspectiva das Teorias Institucional e da Legitimidade, quais companhias do Novo Mercado da BM&FBovespa aderiram às diretrizes da Global Reporting Initiative (GRI e identificar qual a versão das diretrizes GRI adotadas. O estudo é descritivo, qualitativo e documental. Os dados foram analisados por meio da técnica de análise de conteúdo e se referem ao período de 2011 a 2013. Percebe-se que, das 133 companhias da amostra, 67 não possuem ou não foram encontrados os relatórios de sustentabilidade no período analisado. Das 66 empresas que publicaram o relatório de sustentabilidade no período de 2011 a 2013, somente 17 empresas não divulgaram as informações socioambientais conforme as diretrizes da GRI. Os resultados revelam que as empresas divulgam práticas de sustentabilidade nos relatórios para reafirmar sua legitimidade perante a sociedade. Além disso, utilizam práticas de divulgação com base em outras empresas modelos, como é o caso da adesão às diretrizes da GRI, o que se pode relacionar com a Teoria Institucional com base no isomorfismo mimético. Sobre as práticas socioambientais, essas são institucionalizadas nas empresas, e a mudança de versão da G3 para G4 possibilita a ampliação do disclosure pelos indicadores propostos.

  18. The Cost Implications of Less Tight Versus Tight Control of Hypertension in Pregnancy (CHIPS Trial)

    Science.gov (United States)

    Ahmed, Rashid J.; Gafni, Amiram; Hu, Zheng Jing; Pullenayegum, Eleanor; von Dadelszen, Peter; Rey, Evelyne; Ross, Susan; Asztalos, Elizabeth; Murphy, Kellie E.; Menzies, Jennifer; Sanchez, J. Johanna; Ganzevoort, Wessel; Helewa, Michael; Lee, Shoo K.; Lee, Terry; Logan, Alexander G.; Moutquin, Jean-Marie; Singer, Joel; Thornton, Jim G.; Welch, Ross; Magee, Laura A.

    2016-01-01

    The CHIPS randomized controlled trial (Control of Hypertension in Pregnancy Study) found no difference in the primary perinatal or secondary maternal outcomes between planned “less tight” (target diastolic 100 mm Hg) and “tight” (target diastolic 85 mm Hg) blood pressure management strategies among women with chronic or gestational hypertension. This study examined which of these management strategies is more or less costly from a third-party payer perspective. A total of 981 women with singleton pregnancies and nonsevere, nonproteinuric chronic or gestational hypertension were randomized at 14 to 33 weeks to less tight or tight control. Resources used were collected from 94 centers in 15 countries and costed as if the trial took place in each of 3 Canadian provinces as a cost-sensitivity analysis. Eleven hospital ward and 24 health service costs were obtained from a similar trial and provincial government health insurance schedules of medical benefits. The mean total cost per woman–infant dyad was higher in less tight versus tight control, but the difference in mean total cost (DM) was not statistically significant in any province: Ontario ($30 191.62 versus $24 469.06; DM $5723, 95% confidence interval, −$296 to $12 272; P=0.0725); British Columbia ($30 593.69 versus $24 776.51; DM $5817; 95% confidence interval, −$385 to $12 349; P=0.0725); or Alberta ($31 510.72 versus $25 510.49; DM $6000.23; 95% confidence interval, −$154 to $12 781; P=0.0637). Tight control may benefit women without increasing risk to neonates (as shown in the main CHIPS trial), without additional (and possibly lower) cost to the healthcare system. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT01192412. PMID:27550914

  19. An Important Member of Tight Junctions: Claudins

    Directory of Open Access Journals (Sweden)

    Ozlem Demirpence

    2016-01-01

    Full Text Available The tight junction (TJs, the most apically located of the intercellular junctional complexes, inhibits solute and water flow through the paracellular space, termed the %u201Cbarrier%u201D function. TJs participate in signal transduction mechanisms that regulate epithelial cell proliferation, gene expression, differentiation and morphogenesis. The claudin family of transmembrane proteins localized to the TJ. Loss of expression of Claudin causes of suppression TJs function. Recent studies have shown that altered levels of the different claudins may be related to invasion and progression of carcinoma cells in several primary neoplasms. A better knowledge of the mechanisms underlying carcinogenesis will likely result in the development of novel approaches for the diagnosis and therapy.

  20. On the Countable Tightness of Product Spaces

    Institute of Scientific and Technical Information of China (English)

    Chuan LIU; Shou LIN

    2005-01-01

    In this paper, we discuss the countable tightness of products of spaces which are quotient simages of locally separable metric spaces, or k-spaces with a star-countable k-network. The main result is that the following conditions are equivalent: (1) b = ω1; (2) t(Sω× Sω1 ) >ω; (3) For any pair (X, Y),which are k-spaces with a point-countable k-network consisting of cosmic subspaces, t(X × Y) ≤ωif and only if one of X, Y is first countable or both X, Y are locally cosmic spaces. Many results on the k-space property of products of spaces with certain k-networks could be deduced from the above theorem.

  1. Group A Streptococcus exploits human plasminogen for bacterial translocation across epithelial barrier via tricellular tight junctions

    Science.gov (United States)

    Sumitomo, Tomoko; Nakata, Masanobu; Higashino, Miharu; Yamaguchi, Masaya; Kawabata, Shigetada

    2016-01-01

    Group A Streptococcus (GAS) is a human-specific pathogen responsible for local suppurative and life-threatening invasive systemic diseases. Interaction of GAS with human plasminogen (PLG) is a salient characteristic for promoting their systemic dissemination. In the present study, a serotype M28 strain was found predominantly localized in tricellular tight junctions of epithelial cells cultured in the presence of PLG. Several lines of evidence indicated that interaction of PLG with tricellulin, a major component of tricellular tight junctions, is crucial for bacterial localization. A site-directed mutagenesis approach revealed that lysine residues at positions 217 and 252 within the extracellular loop of tricellulin play important roles in PLG-binding activity. Additionally, we demonstrated that PLG functions as a molecular bridge between tricellulin and streptococcal surface enolase (SEN). The wild type strain efficiently translocated across the epithelial monolayer, accompanied by cleavage of transmembrane junctional proteins. In contrast, amino acid substitutions in the PLG-binding motif of SEN markedly compromised those activities. Notably, the interaction of PLG with SEN was dependent on PLG species specificity, which influenced the efficiency of bacterial penetration. Our findings provide insight into the mechanism by which GAS exploits host PLG for acceleration of bacterial invasion into deeper tissues via tricellular tight junctions. PMID:26822058

  2. Research activities in the United States on energy conservation in the gas inndustry

    Energy Technology Data Exchange (ETDEWEB)

    Huebler, J.; Macriss, R.A. (eds.)

    1979-01-01

    The paper describes the content and progress of the Space Heating Equipment Improvement Program, which seeks to define those areas where efficiency improvement can most readily be attained. The goals of the newly formed Gas Research Institute (GRI) are listed. GRI has supplanted the former American Gas Association research program. In improvement of residential and commmercial space heating equipment, three specific programs are described: (1) developing a furnace employing a pulse-combustion burner system (currently being tested); (2) determining heat losses from duct systems, which have shown that these losses contribute to an important and avoidable loss in efficiency; (3) measuring heat losses in a large number of installed furnaces, which are under way to verify (and modify if required) IGT's model of flue heat losses. Two appliance improvement programs are described in which a new concept for a water heater and an intermittent ignition device are being developed. In the area of heat-actuated heat pumps, the paper describes programs to bring one or more of the available devices to the marketplace. These developments involve the free-piston Stirling engine, the gas turbine (Brayton cycle), an absorption machine, and reversible vapor-compression-cycle heat pump. Technologies that are of great interest for future application are represented by development of fuel-cell systems and gas-augmented, solar devices. Some technology needed to achieve greater conservation in industry is considered. Examples of cogeneration in a glass-melting furnace and flue-gas pressurization to recover heat in metal-treating furnaces are used. The rapidly growing efforts supported by DOE and GRI in the industrial area are described.

  3. Indigenous lactobacilli strains of food and human sources reverse enteropathogenic E. coli O26:H11-induced damage in intestinal epithelial cell lines: effect on redistribution of tight junction proteins.

    Science.gov (United States)

    Jariwala, Ruchi; Mandal, Hemanti; Bagchi, Tamishraha

    2017-09-01

    The aim of the study was to investigate the neutralizing effect of lactobacilli isolated from indigenous food and human sources on enteropathogenic Escherichia coli (EPEC) O26 : H11-induced epithelial barrier dysfunction in vitro. This was assessed by transepithelial electrical resistance (TEER) and permeability assays using intestinal cell lines, HT-29 and Caco-2. Furthermore, the expression and distribution of tight junction (TJ) proteins were analysed by qRT-PCR and immunofluorescence assay, respectively. The nine strains used in the study were from different species viz. Lactobacillus fermentum, Lactobacillushelveticus, Lactobacillus salivarius and Lactobacillus plantarum. All strains were able to reverse the decrease in TEER and corresponding increase in permeability across E. coli-infected monolayers. Maximum reversal was observed after 18 h [up to 93.8±2.0 % by L. rhamnosus GG followed by L. fermentum IIs11.2 (92.6±2.2 %) and L. plantarum GRI-2 (91.9±0.9 %)] of lactobacilli exposure following EPEC O26 : H11 infection. All strains were able to redistribute the TJ proteins to the cell periphery either partially or completely. Moreover, L. helveticus FA-7 was also able to significantly increase the mRNA expression of ZO-1 and claudin-1 (2.5-fold and 3.0-fold, respectively; PGRI-2 were good in all the aspects studied, and the other strains were good in some aspects. L. helveticus FA-7, L. fermentum FA-1 and L. plantarum GRI-2 can therefore be used for potential therapeutic purpose against intestinal epithelial dysfunction.

  4. Dewatering Techniques for Gas Recovery in Sichuan Gas Fields

    Institute of Scientific and Technical Information of China (English)

    Xu Kefang

    1996-01-01

    @@ Through several years' study for geology and development behavior of the gas fields, we realized that the water-bearing gas pools in Sichuan gas fields almost belong to enclosed weak elastic water drive gas pools, whether edge water gas pools or bottom water gas pools. According to the verification of drilling and production behavior data, in the periphery of Sichuan water-bearing gas pools, a screen is formed by gypsum salt, mudstone, or tight bed rock, with very low permeability, which blocks water percolation.

  5. Myelin architecture: zippering membranes tightly together.

    Science.gov (United States)

    Bakhti, Mostafa; Aggarwal, Shweta; Simons, Mikael

    2014-04-01

    Rapid nerve conduction requires the coating of axons by a tightly packed multilayered myelin membrane. In the central nervous system, myelin is formed from cellular processes that extend from oligodendrocytes and wrap in a spiral fashion around an axon, resulting in the close apposition of adjacent myelin membrane bilayers. In this review, we discuss the physical principles underlying the zippering of the plasma membrane of oligodendrocytes at the cytoplasmic and extracellular leaflet. We propose that the interaction of the myelin basic protein with the cytoplasmic leaflet of the myelin bilayer triggers its polymerization into a fibrous network that drives membrane zippering and protein extrusion. In contrast, the adhesion of the extracellular surfaces of myelin requires the down-regulation of repulsive components of the glycocalyx, in order to uncover weak and unspecific attractive forces that bring the extracellular surfaces into close contact. Unveiling the mechanisms of myelin membrane assembly at the cytoplasmic and extracelluar sites may help to understand how the myelin bilayers are disrupted and destabilized in the different demyelinating diseases.

  6. Stochastic homothetically revealed preference for tight stochastic demand functions

    OpenAIRE

    Jan Heufer

    2009-01-01

    This paper strengthens the framework of stochastic revealed preferences introduced by Bandyopadhyay et al. (1999, 2004) for stochastic homothetically revealed preferences for tight stochastic demand functions.

  7. Diagnosing the tight building syndrome or diagnosing chemical hypersensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, S.A. (Northeast Center for Environmental Medicine, Syracuse, NY (USA))

    1989-01-01

    The abrupt exposure to urea foam formaldehyde insulation served as an alert to its spectrum of symptoms, including attacks of headache, flushing, laryngitis, dizziness, nausea, extreme weakness or exhaustion, arthralgia, an inability to concentrate, unwarranted depression, arrhythmia, or muscle spasms, and baffled physicians from many specialties. Later it was learned that toluene, xylene, benzene, natural gas, trichloroethylene, and many other chemicals were also capable of triggering chemical hypersensitivity. Other names for this condition include Environmentally Induced Illness (EI), the Tight Building Syndrome (TBS), the Sick Building Syndrome, and Building-Related Illness. The very symptoms patients complain of can be provoked within minutes and then subsequently alleviated with an intradermal injection of the appropriate strength of the triggering chemical. This technique aids in convincing the patient of the EI or TBS triggers so that the patient can begin to relate symptoms to environmental exposures and initiate measure to bring the disease under control. The key to safer buildings is increased ventilation, increased filtration of air, and decreased use of off-gassing synthetic materials.

  8. 42 CFR 84.1141 - Isoamyl acetate tightness test; dust, fume, and mist respirators designed for respiratory...

    Science.gov (United States)

    2010-10-01

    ... mist respirators designed for respiratory protection against fumes of various metals having an air...; Pesticide; Paint Spray; Powered Air-Purifying High Efficiency Respirators and Combination Gas Masks § 84.1141 Isoamyl acetate tightness test; dust, fume, and mist respirators designed for...

  9. DEVELOPMENT OF A LOW-COST INFERENTIAL NATURAL GAS ENERGY FLOW RATE PROTOTYPE RETROFIT MODULE

    Energy Technology Data Exchange (ETDEWEB)

    E. Kelner; T.E. Owen; D.L. George; A. Minachi; M.G. Nored; C.J. Schwartz

    2004-03-01

    In 1998, Southwest Research Institute{reg_sign} began a multi-year project co-funded by the Gas Research Institute (GRI) and the U.S. Department of Energy. The project goal is to develop a working prototype instrument module for natural gas energy measurement. The module will be used to retrofit a natural gas custody transfer flow meter for energy measurement, at a cost an order of magnitude lower than a gas chromatograph. Development and evaluation of the prototype retrofit natural gas energy flow meter in 2000-2001 included: (1) evaluation of the inferential gas energy analysis algorithm using supplemental gas databases and anticipated worst-case gas mixtures; (2) identification and feasibility review of potential sensing technologies for nitrogen diluent content; (3) experimental performance evaluation of infrared absorption sensors for carbon dioxide diluent content; and (4) procurement of a custom ultrasonic transducer and redesign of the ultrasonic pulse reflection correlation sensor for precision speed-of-sound measurements. A prototype energy meter module containing improved carbon dioxide and speed-of-sound sensors was constructed and tested in the GRI Metering Research Facility at SwRI. Performance of this module using transmission-quality natural gas and gas containing supplemental carbon dioxide up to 9 mol% resulted in gas energy determinations well within the inferential algorithm worst-case tolerance of {+-}2.4 Btu/scf (nitrogen diluent gas measured by gas chromatograph). A two-week field test was performed at a gas-fired power plant to evaluate the inferential algorithm and the data acquisition requirements needed to adapt the prototype energy meter module to practical field site conditions.

  10. Digital Rock Studies of Tight Porous Media

    Energy Technology Data Exchange (ETDEWEB)

    Silin, Dmitriy [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2012-08-07

    This technical report summarizes some recently developed approaches to studies of rock properties at a pore scale. Digital rock approach is complementary to laboratory and field studies. It can be especially helpful in situations where experimental data are uncertain, or are difficult or impossible to obtain. Digitized binary images of the pore geometries of natural rocks obtained by different imaging techniques are the input data. Computer-generated models of natural rocks can be used instead of images in a case where microtomography data are unavailable, or the resolution of the tools is insufficient to adequately characterize the features of interest. Simulations of creeping viscous flow in pores produce estimates of Darcy permeability. Maximal Inscribed Spheres calculations estimate two-phase fluid distribution in capillary equilibrium. A combination of both produce relative permeability curves. Computer-generated rock models were employed to study two-phase properties of fractured rocks, or tight sands with slit-like pores, too narrow to be characterized with micro-tomography. Various scenarios can simulate different fluid displacement mechanisms, from piston-like drainage to liquid dropout at the dew point. A finite differences discretization of Stokes equation is developed to simulate flow in the pore space of natural rocks. The numerical schemes are capable to handle both no-slip and slippage flows. An upscaling procedure estimates the permeability by subsampling a large data set. Capillary equilibrium and capillary pressure curves are efficiently estimated with the method of maximal inscribed spheres both an arbitrary contact angle. The algorithms can handle gigobytes of data on a desktop workstation. Customized QuickHull algorithms model natural rocks. Capillary pressure curves evaluated from computer-generated images mimic those obtained for microtomography data.

  11. Assessment of future natural gas vehicle concepts

    Science.gov (United States)

    Groten, B.; Arrigotti, S.

    1992-10-01

    The development of Natural Gas Vehicles is progressing rapidly under the stimulus of recent vehicle emission regulations. The development is following what can be viewed as a three step progression. In the first step, contemporary gasoline or diesel fueled automobiles are retrofitted with equipment enabling the vehicle to operate on either natural gas or standard liquid fuels. The second step is the development of vehicles which utilize traditional internal combustion engines that have been modified to operate exclusively on natural gas. These dedicated natural gas vehicles operate more efficiently and have lower emissions than the dual fueled vehicles. The third step is the redesigning, from the ground up, of a vehicle aimed at exploiting the advantages of natural gas as an automotive fuel while minimizing its disadvantages. The current report is aimed at identifying the R&D needs in various fuel storage and engine combinations which have potential for providing increased efficiency, reduced emissions, and reductions in vehicle weight and size. Fuel suppliers, automobile and engine manufacturers, many segments of the natural gas and other industries, and regulatory authorities will influence or be affected by the development of such a third generation vehicle, and it is recommended that GRI act to bring these groups together in the near future to begin, developing the focus on a 'designed-for-natural-gas' vehicle.

  12. Homology modeling and metabolism prediction of human carboxylesterase-2 using docking analyses by GriDock: a parallelized tool based on AutoDock 4.0.

    Science.gov (United States)

    Vistoli, Giulio; Pedretti, Alessandro; Mazzolari, Angelica; Testa, Bernard

    2010-09-01

    Metabolic problems lead to numerous failures during clinical trials, and much effort is now devoted to developing in silico models predicting metabolic stability and metabolites. Such models are well known for cytochromes P450 and some transferases, whereas less has been done to predict the activity of human hydrolases. The present study was undertaken to develop a computational approach able to predict the hydrolysis of novel esters by human carboxylesterase hCES2. The study involved first a homology modeling of the hCES2 protein based on the model of hCES1 since the two proteins share a high degree of homology (congruent with 73%). A set of 40 known substrates of hCES2 was taken from the literature; the ligands were docked in both their neutral and ionized forms using GriDock, a parallel tool based on the AutoDock4.0 engine which can perform efficient and easy virtual screening analyses of large molecular databases exploiting multi-core architectures. Useful statistical models (e.g., r (2) = 0.91 for substrates in their unprotonated state) were calculated by correlating experimental pK(m) values with distance between the carbon atom of the substrate's ester group and the hydroxy function of Ser228. Additional parameters in the equations accounted for hydrophobic and electrostatic interactions between substrates and contributing residues. The negatively charged residues in the hCES2 cavity explained the preference of the enzyme for neutral substrates and, more generally, suggested that ligands which interact too strongly by ionic bonds (e.g., ACE inhibitors) cannot be good CES2 substrates because they are trapped in the cavity in unproductive modes and behave as inhibitors. The effects of protonation on substrate recognition and the contrasting behavior of substrates and products were finally investigated by MD simulations of some CES2 complexes.

  13. CUSTOS SOCIAIS E AMBIENTAIS E GRI: UMA ANÁLISE DAS EMPRESAS INTEGRANTES DO ÍNDICE DE SUSTENTABILIDADE EMPRESARIAL (ISE

    Directory of Open Access Journals (Sweden)

    Cecília Maria Medeiros Dantas de Melo

    2016-12-01

    Full Text Available A busca por políticas e metodologias eficientes do ponto de vista econômico e social faz parte da nova realidade das empresas, as quais têm procurado cada vez mais alinhar sua realidade produtiva às normas sociais e ambientais. O objetivo da pesquisa é analisar a evidenciação dos custos ambientais e sociais, à luz das diretrizes do GRI, pelos relatórios de sustentabilidade das empresas do ISE. Trata-se de uma pesquisa descritiva, de método dedutivo, documental e qualitativa, que utiliza a análise de conteúdo como método de análise dos dados. Os resultados apontam que a maioria das empresas estudadas apenas descrevem os riscos de suas atividades, sem informar os custos para mitigá-los. Verificou-se também que a redução de energia, a reutilização de água e a redução das emissões de gases de efeito estufa são melhorias na qualidade do desempenho ambiental decorrentes dos investimentos nessa área que propiciam a redução dos custos, associando-se, assim, à ecoeficiência. Através da análise dos indicadores LA2, LA6 e LA9, observou-se que grande parte das empresas investe em seus empregados, bem como controlam os acidentes ocorridos com esses. No que se refere aos impactos provocados na comunidade, algumas empresas afirmaram não possuir mecanismos para mensurá-los.

  14. Graphene as Gas Sensors

    Institute of Scientific and Technical Information of China (English)

    Hamze Mousavi

    2011-01-01

    The triatomic and tetratomic gas molecule adsorption effects on the electrical conductivity of graphene are investigated by the tight-binding model, Green's function method, and coherent potential approximation. We find that the electrical conductivity of graphene sheet is sensitive to the adsorption of these gases.

  15. Construction of Multivariate Tight Framelet Packets Associated with Dilation Matrix

    Institute of Scientific and Technical Information of China (English)

    Firdous A Shah; Abdullah

    2015-01-01

    In this paper, we present a method for constructing multivariate tight framelet packets associated with an arbitrary dilation matrix using unitary extension principles.We also prove how to construct various tight frames for L2(Rd) by replac-ing some mother framelets.

  16. Localization of Tight Closure in Two-Dimensional Rings

    Indian Academy of Sciences (India)

    Kamran Divaani-Aazar; Massoud Tousi

    2005-02-01

    It is shown that tight closure commutes with localization in any two-dimensional ring of prime characteristic if either is a Nagata ring or possesses a weak test element. Moreover, it is proved that tight closure commutes with localization at height one prime ideals in any ring of prime characteristic.

  17. Random non-Hermitian tight-binding models

    Science.gov (United States)

    Marinello, G.; Pato, M. P.

    2016-08-01

    For a one dimensional system tight binding models are described by sparse tridiagonal matrices which describe interactions between nearest neighbors. In this report, we construct open and closed random tight-binding models based in the tridiagonal matrices of the so-called,β-ensembles of random matrix theory.

  18. The Elastic Continuum Limit of the Tight Binding Model

    Institute of Scientific and Technical Information of China (English)

    Weinan E; Jianfeng LU

    2007-01-01

    The authors consider the simplest quantum mechanics model of solids, the tight binding model, and prove that in the continuum limit, the energy of tight binding model converges to that of the continuum elasticity model obtained using Cauchy-Born rule. Thet echnique in this paper is based mainly on spectral perturbation theory for large matrices.

  19. Differences between tight and loose cultures : A 33-nation study

    NARCIS (Netherlands)

    Gelfand, M.J.; Raver, R.L.; Nishii, L.; Leslie, L.M.; Lun, J.; Lim, B.C.; Van de Vliert, E.

    2011-01-01

    With data from 33 nations, we illustrate the differences between cultures that are tight (have many strong norms and a low tolerance of deviant behavior) versus loose (have weak social norms and a high tolerance of deviant behavior). Tightness-looseness is part of a complex, loosely integrated multi

  20. Transcriptional mechanisms coordinating tight junction assembly during epithelial differentiation.

    Science.gov (United States)

    Boivin, Felix J; Schmidt-Ott, Kai M

    2017-06-01

    Epithelial tissues form a selective barrier via direct cell-cell interactions to separate and establish concentration gradients between the different compartments of the body. Proper function and formation of this barrier rely on the establishment of distinct intercellular junction complexes. These complexes include tight junctions, adherens junctions, desmosomes, and gap junctions. The tight junction is by far the most diverse junctional complex in the epithelial barrier. Its composition varies greatly across different epithelial tissues to confer various barrier properties. Thus, epithelial cells rely on tightly regulated transcriptional mechanisms to ensure proper formation of the epithelial barrier and to achieve tight junction diversity. Here, we review different transcriptional mechanisms utilized during embryogenesis and disease development to promote tight junction assembly and maintenance of intercellular barrier integrity. We focus particularly on the Grainyhead-like transcription factors and ligand-activated nuclear hormone receptors, two central families of proteins in epithelialization. © 2017 New York Academy of Sciences.

  1. A two scale analysis of tight sandstones

    Science.gov (United States)

    Adler, P. M.; Davy, C. A.; Song, Y.; Troadec, D.; Hauss, G.; Skoczylas, F.

    2015-12-01

    Tight sandstones have a low porosity and a very small permeability K. Available models for K do not compare well with measurements. These sandstones are made of SiO_2 grains, with a typical size of several hundreds of micron. These grains are separated by a network of micro-cracks, with sizes ranging between microns down to tens of nm. Therefore, the structure can be schematized by Voronoi polyhedra separated by plane and permeable polygonal micro-cracks. Our goal is to estimate K based on a two scale analysis and to compare the results to measurements. For a particular sample [2], local measurements on several scales include FIB/SEM [3], CMT and 2D SEM. FIB/SEM is selected because the peak pore size given by Mercury Intrusion Porosimetry is of 350nm. FIB/SEM imaging (with 50 nm voxel size) identifies an individual crack of 180nm average opening, whereas CMT provides a connected porosity (individual crack) for 60 nm voxel size, of 4 micron average opening. Numerical modelling is performed by combining the micro-crack network scale (given by 2D SEM) and the 3D micro-crack scale (given by either FIB/SEM or CMT). Estimates of the micro-crack density are derived from 2D SEM trace maps by counting the intersections with scanlines, the surface density of traces, and the number of fracture intersections. K is deduced by using a semi empirical formula valid for identical, isotropic and uniformly distributed fractures [1]. This value is proportional to the micro-crack transmissivity sigma. Sigma is determined by solving the Stokes equation in the micro-cracks measured by FIB/SEM or CMT. K is obtained by combining the two previous results. Good correlation with measured values on centimetric plugs is found when using sigma from CMT data. The results are discussed and further research is proposed. [1] Adler et al, Fractured porous media, Oxford Univ. Press, 2012. [2] Duan et al, Int. J. Rock Mech. Mining Sci., 65, p75, 2014. [3] Song et al, Marine and Petroleum Eng., 65, p63

  2. 30 CFR 206.157 - Determination of transportation allowances.

    Science.gov (United States)

    2010-07-01

    ... a series of outgoing pipelines; (5) Gas Research Institute (GRI) fees. The GRI conducts research... industry and gas customers. GRI fees are allowable provided such fees are mandatory in FERC-approved...

  3. Comparison analysis of fractal characteristics for tight sandstones using different calculation methods

    Science.gov (United States)

    Zhang, Xiaoyang; Wu, Caifang; Li, Teng

    2017-02-01

    The micropore structure of a tight sandstone is the decisive factor in determining its reserve and seepage characteristics. An accurate description of the pore structures and a complete characterization of the gas-water permeability are critical when exploring for tight sandstone gas. One simple and effective way to quantitatively characterize the heterogeneity and complexity of the pore structures in a low permeability reservoir is the fractal dimension. In this study, three different methods, each utilizing mercury intrusion porosimetry (MIP) data, were adopted to analyze the fractal dimensions and the fractal curves of sandstones from the no. 8 layer of the Xiashihezi Formation (He 8 member) in the Linxing block, dated from the Middle Permian. The morphological features of the fractal curves, the characteristics of the fractal dimensions and the theoretical differences between these three methods were also discussed. The results show that the fractal dimensions obtained by method I reflect the characteristics of the remaining pores that are not intruded by mercury, and they show that the involved pore scales are more comprehensive. While in methods II and III, both obtain the fractal dimensions of the pores intruded by mercury, the difference between them is in the selection of a simplified pore shape model, which results in the fractal dimensions differing by a value of 1 between them. No matter which method is adopted, the pore structures of tight sandstone reservoirs in the Linxing block exhibit fractal characteristics. However, the fractal dimensions obtained by method I are more suitable for describing the complexity and petrophysical properties of the tight sandstone pores in the He 8 member of the Linxing block. The fractal curves obtained by different methods are consistent to a certain extent in terms of morphological changes. Small pores (fractal characteristics, while large pores (>r max-point) are the critical factor affecting the seepage

  4. 致密储层形成机理综述%A Review on the Forming Mechanisms of tight reservoir

    Institute of Scientific and Technical Information of China (English)

    肖鹏

    2014-01-01

    With the progress of theory and technology and the growth of demand for the gas and oil resources, tight reservoir is becoming the important substitute area for exploration of the oil and gas basins. This thesis systematically summarizes the latest research progress and examples in the tight reservoir. It expounds the key scientific issues of formation of tight reservoir. Tight reservoir formation mechanism of oil and gas exploration will be of great significance.%随着勘探理论、技术进步和对油气资源增长的需求,致密储层的研究逐渐成为油气资源发展的重要新领域。通过对国内外大量研究成果的分析,较系统地阐述了致密储层的形成机理,这将对对今后的油气勘探具有重要意义。

  5. Diagenesis and porosity evolution of tight sand reservoirs in Carboniferous Benxi Formation, Southeast Ordos Basin

    Science.gov (United States)

    Hu, Peng; Yu, Xinghe; Shan, Xin; Su, Dongxu; Wang, Jiao; Li, Yalong; Shi, Xin; Xu, Liqiang

    2016-04-01

    The Ordos Basin, situated in west-central China, is one of the oldest and most important fossil-fuel energy base, which contains large reserves of coal, oil and natural gas. The Upper Palaeozoic strata are widely distributed with rich gas-bearing and large natural gas resources, whose potential is tremendous. Recent years have witnessed a great tight gas exploration improvement of the Upper Paleozoic in Southeastern Ordos basin. The Carboniferous Benxi Formation, mainly buried more than 2,500m, is the key target strata for hydrocarbon exploration, which was deposited in a barrier island and tidal flat environment. The sandy bars and flats are the favorable sedimentary microfacies. With an integrated approach of thin-section petrophysics, constant velocity mercury injection test, scanning electron microscopy and X-ray diffractometry, diagenesis and porosity evolution of tight sand reservoirs of Benxi Formation were analyzed in detail. The result shows that the main lithology of sandstone in this area is dominated by moderately to well sorted quartz sandstone. The average porosity and permeability is 4.72% and 1.22mD. The reservoirs of Benxi Formation holds a variety of pore types and the pore throats, with obvious heterogeneity and poor connection. Based on the capillary pressure curve morphological characteristics and parameters, combined with thin section and phycical property data, the reservoir pore structure of Benxi Formation can be divided into 4 types, including mid pore mid throat type(I), mid pore fine throat type(II), small pore fine throat type(III) and micro pro micro throat type(Ⅳ). The reservoirs primarily fall in B-subsate of middle diagenesis and late diagenesis, which mainly undergo compaction, cmentation, dissolution and fracturing process. Employing the empirical formula of different sorting for unconsolideated sandstone porosity, the initial sandstone porosity is 38.32% on average. Quantitative evaluation of the increase and decrease of

  6. Fracking in Tight Shales: What Is It, What Does It Accomplish, and What Are Its Consequences?

    Science.gov (United States)

    Norris, J. Quinn; Turcotte, Donald L.; Moores, Eldridge M.; Brodsky, Emily E.; Rundle, John B.

    2016-06-01

    Fracking is a popular term referring to hydraulic fracturing when it is used to extract hydrocarbons. We distinguish between low-volume traditional fracking and the high-volume modern fracking used to recover large volumes of hydrocarbons from shales. Shales are fine-grained rocks with low granular permeabilities. During the formation of oil and gas, large fluid pressures are generated. These pressures result in natural fracking, and the resulting fracture permeability allows oil and gas to escape, reducing the fluid pressures. These fractures may subsequently be sealed by mineral deposition, resulting in tight shale formations. The objective of modern fracking is to reopen these fractures and/or create new fractures on a wide range of scales. Modern fracking has had a major impact on the availability of oil and gas globally; however, there are serious environmental objections to modern fracking, which should be weighed carefully against its benefits.

  7. Geologic and production characteristics of the Tight Mesaverde Group: Piceance Basin, Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Myal, F.R.; Price, E.H.; Hill, R.E.; Kukal, G.C.; Abadie, P.A.; Riecken, C.C.

    1989-07-01

    The Mesaverde Group of the Piceance Basin in western Colorado has been a pilot study area for government-sponsored tight gas sand research for over 20 years. This study provides a critical comparison of the geologic, production and reservoir characteristics of existing Mesaverde gas producing areas within the basin to those same characteristics at the MWX site near Rifle, Colorado. As will be discussed, the basin has been partitioned into three areas having similar geologic and production characteristics. Stimulation techniques have been reviewed for each partitioned area to determine the most effective stimulation technique currently used in the Mesaverde. This study emphasizes predominantly the southern Piceance Basin because of the much greater production and geologic data there. There may be Mesaverde gas production in northern areas but because of the lack of production and relatively few penetrations, the northern Piceance Basin was not included in the detailed parts of this study. 54 refs., 31 figs., 7 tabs.

  8. Three-dimensional measurement of a tightly focused laser beam

    Directory of Open Access Journals (Sweden)

    Xiangsheng Xie

    2013-02-01

    Full Text Available The spatial structure of a tightly focused light field is measured with a double knife-edge scanning method. The measurement method is based on the use of a high-quality double knife-edge fabricated from a right-angled silicon fragment mounted on a photodetector. The reconstruction of the three-dimensional structures of tightly focused spots is carried out with both uniform and partially obstructed linearly polarized incident light beams. The optical field distribution is found to deviate substantially from the input beam profile in the tightly focused region, which is in good agreement with the results of numerical simulations.

  9. Independents add gas reserves, forego romance

    Energy Technology Data Exchange (ETDEWEB)

    Gill, D.

    1981-08-01

    Incentive pricing for low-permeability reservoirs and tax advantages for drilling them are 2 big reasons why more independents may start making a special effort to add gas reserves to their inventories. If so, it will be a change from past practices, which saw independents build up big gas positions by circumstance rather than by intention. There are always major refiners ready and willing to buy whole crude oil reservoirs from small producers, but purchasers willing to take gas fields in a single investment are few and far between. Lower-than-normal return on equity during the first 20 years, plus the heavy front-end cost of a frac necessary to produce the tight gas might dissuade independents from drilling tight gas sands, but those liabilities are offset by the higher price tight gas gets and the peculiar tax advantages of exploring for it that make a nice fit with the small operator's way of doing business.

  10. Paracellular drug absorption enhancement through tight junction modulation

    OpenAIRE

    Lemmer, Hendrik Jacobus Righard; Josias H. Hamman

    2013-01-01

    Introduction: Inclusion of absorption-enhancing agents in dosage forms is one approach to improve the bioavailability of active pharmaceutical ingredients with low membrane permeability. Tight junctions are dynamic protein structures that form a regulated barrier for movement of molecules through the intercellular spaces across the intestinal epithelium. Some drug absorption enhancers are capable of loosening tight junctions and thereby facilitate paracellular absorption of drug molecules. ...

  11. The Problem of Partisanship in American Foreign Policy Book Review: Gries P.H. The Politics of American Foreign Policy: How Ideology Divides Liberals and Conservatives over Foreign Affairs Stanford, California: Stanford University press, 2014. 367 p.

    Directory of Open Access Journals (Sweden)

    Il'ya Anatol'evich Sokov

    2015-12-01

    Full Text Available This publication is the review on the book of Peter Hays Gries “The Politics of American Foreign Policy: How Ideology Divides Liberals and Conservatives over Foreign Affairs”. The book consists of Preface, Introduction, the Text from two parts: Part I “Concepts” includes 5 chapters, Part II “Cases” also includes 5 chapters and four of them description the relations of the USA with the world regions: Latin America, Europe, the Middle East, the South Asia and the last chapter - relations with the international organizations. The end of the text is the Conclusion. Besides the text of book consists of 100 illustrations and 2 charts. The Preface was written by David Lyle Boren, the President of Oklahoma University and the US Ex-Senator (1979-1994, where he was at the head of Senate Select Committee on Intelligence and he knows the topic which the author of monograph studies. The problems is studied by P.H. Gries are interested by the native specialists, who studies the international relations. This book is recommended to students, post-graduate students, scientists and all of them who are interested by the problems of international relations.

  12. 20-25 Yaş Arası Sağlıklı Gençlerde Gri ve Beyaz Cevher Hacimlerinin İncelenmesi: Planimetrik Çalışma

    OpenAIRE

    ÇAMURDANOĞLU, Niyazi ACER - Tolga ERTEKİN - Ayşegül KÜ

    2008-01-01

    Amaç: İnsan beyninde cinsiyete ilişkin varyasyonlar birçok araştırıcı tarafından incelenmiştir. Bu çalışmaların çoğunda erkek beyin hacminin bayanlardan daha büyük olduğu bildirilmektedir. Bu çalışmanın amacı MR görüntüleri üzerinde beyaz ve gri cevher ölçümleri planimterik yöntem ile değerlendirmektir. Gereç ve Yöntemler: Bu çalışmada beyaz ve gri cevher hacimleri 20-25 yaş arası sağlıklı gençlerde incelenmiştir. T2 ağırlıklı MR görüntüleri 12 kişi üzerinde elde edilmiş, kadın ve erkeklerde ...

  13. Regulation of Tight Junctions in Upper Airway Epithelium

    Directory of Open Access Journals (Sweden)

    Takashi Kojima

    2013-01-01

    Full Text Available The mucosal barrier of the upper respiratory tract including the nasal cavity, which is the first site of exposure to inhaled antigens, plays an important role in host defense in terms of innate immunity and is regulated in large part by tight junctions of epithelial cells. Tight junction molecules are expressed in both M cells and dendritic cells as well as epithelial cells of upper airway. Various antigens are sampled, transported, and released to lymphocytes through the cells in nasal mucosa while they maintain the integrity of the barrier. Expression of tight junction molecules and the barrier function in normal human nasal epithelial cells (HNECs are affected by various stimuli including growth factor, TLR ligand, and cytokine. In addition, epithelial-derived thymic stromal lymphopoietin (TSLP, which is a master switch for allergic inflammatory diseases including allergic rhinitis, enhances the barrier function together with an increase of tight junction molecules in HNECs. Furthermore, respiratory syncytial virus infection in HNECs in vitro induces expression of tight junction molecules and the barrier function together with proinflammatory cytokine release. This paper summarizes the recent progress in our understanding of the regulation of tight junctions in the upper airway epithelium under normal, allergic, and RSV-infected conditions.

  14. Key Elements Controlling Oil Accumulation within the Tight Sandstones

    Institute of Scientific and Technical Information of China (English)

    Haiyan Hu; Zhiping Zeng; Jianzhang Liu

    2015-01-01

    Tight oil sandstone reservoirs with low porosity and permeability, which are an uncon-ventional petroleum resource, have been discovered in the Jurassic intervals of the central Junggar Ba-sin, the northwestern China. To reveal the accumulation mechanism, a relatively comprehensive re-search was conducted, including oil-source correlation, porosity evolution, and hydrocarbon charging history. The results show that crude oil of these tight sandstone reservoirs were mainly from Permian source rocks with some contribution from Jurassic source rocks. The reservoirs were buried at shallow depth (5%). In contrast, the sandstone reservoir had already become tight and did not provide available space to ac-cumulate oil due to severe compaction and cementation when hydrocarbon from Jurassic source rock filled, evidenced by low GOI values (<5%). Therefore, reservoir porosity controls the oil accumulation within tight sandstone. Whether tight sandstone reservoirs accumulate oil depends on the reservoir quality when hydrocarbons charge. Before the exploration of tight oil sandstone reservoirs, it should be required to investigate the relationship between oil charging history and porosity evolution to reduce the exploration risk and figure out the available targets.

  15. Tightness-looseness across the 50 united states.

    Science.gov (United States)

    Harrington, Jesse R; Gelfand, Michele J

    2014-06-01

    This research demonstrates wide variation in tightness-looseness (the strength of punishment and degree of latitude/permissiveness) at the state level in the United States, as well as its association with a variety of ecological and historical factors, psychological characteristics, and state-level outcomes. Consistent with theory and past research, ecological and man-made threats--such as a higher incidence of natural disasters, greater disease prevalence, fewer natural resources, and greater degree of external threat--predicted increased tightness at the state level. Tightness is also associated with higher trait conscientiousness and lower trait openness, as well as a wide array of outcomes at the state level. Compared with loose states, tight states have higher levels of social stability, including lowered drug and alcohol use, lower rates of homelessness, and lower social disorganization. However, tight states also have higher incarceration rates, greater discrimination and inequality, lower creativity, and lower happiness relative to loose states. In all, tightness-looseness provides a parsimonious explanation of the wide variation we see across the 50 states of the United States of America.

  16. Natural Gas Monthly, October 1993

    Energy Technology Data Exchange (ETDEWEB)

    1993-11-10

    The (NGM) Natural Gas Monthly highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information. This month`s feature articles are: US Production of Natural Gas from Tight Reservoirs: and Expanding Rule of Underground Storage.

  17. The media of sociology: tight or loose translations?

    Science.gov (United States)

    Guggenheim, Michael

    2015-06-01

    Sociologists have increasingly come to recognize that the discipline has unduly privileged textual representations, but efforts to incorporate visual and other media are still only in their beginning. This paper develops an analysis of the ways objects of knowledge are translated into other media, in order to understand the visual practices of sociology and to point out unused possibilities. I argue that the discourse on visual sociology, by assuming that photographs are less objective than text, is based on an asymmetric media-determinism and on a misleading notion of objectivity. Instead, I suggest to analyse media with the concept of translations. I introduce several kinds of translations, most centrally the distinction between tight and loose ones. I show that many sciences, such as biology, focus on tight translations, using a variety of media and manipulating both research objects and representations. Sociology, in contrast, uses both tight and loose translations, but uses the latter only for texts. For visuals, sociology restricts itself to what I call 'the documentary': focusing on mechanical recording technologies without manipulating either the object of research or the representation. I conclude by discussing three rare examples of what is largely excluded in sociology: visual loose translations, visual tight translations based on non-mechanical recording technologies, and visual tight translations based on mechanical recording technologies that include the manipulation of both object and representation. © London School of Economics and Political Science 2015.

  18. Testosterone regulates tight junction proteins and influences prostatic autoimmune responses.

    Science.gov (United States)

    Meng, Jing; Mostaghel, Elahe A; Vakar-Lopez, Funda; Montgomery, Bruce; True, Larry; Nelson, Peter S

    2011-06-01

    Testosterone and inflammation have been linked to the development of common age-associated diseases affecting the prostate gland including prostate cancer, prostatitis, and benign prostatic hypertrophy. We hypothesized that testosterone regulates components of prostate tight junctions which serve as a barrier to inflammation, thus providing a connection between age- and treatment-associated testosterone declines and prostatic pathology. We examined the expression and distribution of tight junction proteins in prostate biospecimens from mouse models and a clinical study of chemical castration, using transcript profiling, immunohistochemistry, and electron microscopy. We determined that low serum testosterone is associated with reduced transcript and protein levels of Claudin 4 and Claudin 8, resulting in defective tight junction ultrastructure in benign prostate glands. Expression of Claudin 4 and Claudin 8 was negatively correlated with the mononuclear inflammatory infiltrate caused by testosterone deprivation. Testosterone suppression also induced an autoimmune humoral response directed toward prostatic proteins. Testosterone supplementation in castrate mice resulted in re-expression of tight junction components in prostate epithelium and significantly reduced prostate inflammatory cell numbers. These data demonstrate that tight junction architecture in the prostate is related to changes in serum testosterone levels, and identify an androgen-regulated mechanism that potentially contributes to the development of prostate inflammation and consequent pathology.

  19. Undersampled MR Image Reconstruction with Data-Driven Tight Frame

    Directory of Open Access Journals (Sweden)

    Jianbo Liu

    2015-01-01

    Full Text Available Undersampled magnetic resonance image reconstruction employing sparsity regularization has fascinated many researchers in recent years under the support of compressed sensing theory. Nevertheless, most existing sparsity-regularized reconstruction methods either lack adaptability to capture the structure information or suffer from high computational load. With the aim of further improving image reconstruction accuracy without introducing too much computation, this paper proposes a data-driven tight frame magnetic image reconstruction (DDTF-MRI method. By taking advantage of the efficiency and effectiveness of data-driven tight frame, DDTF-MRI trains an adaptive tight frame to sparsify the to-be-reconstructed MR image. Furthermore, a two-level Bregman iteration algorithm has been developed to solve the proposed model. The proposed method has been compared to two state-of-the-art methods on four datasets and encouraging performances have been achieved by DDTF-MRI.

  20. Undersampled MR Image Reconstruction with Data-Driven Tight Frame.

    Science.gov (United States)

    Liu, Jianbo; Wang, Shanshan; Peng, Xi; Liang, Dong

    2015-01-01

    Undersampled magnetic resonance image reconstruction employing sparsity regularization has fascinated many researchers in recent years under the support of compressed sensing theory. Nevertheless, most existing sparsity-regularized reconstruction methods either lack adaptability to capture the structure information or suffer from high computational load. With the aim of further improving image reconstruction accuracy without introducing too much computation, this paper proposes a data-driven tight frame magnetic image reconstruction (DDTF-MRI) method. By taking advantage of the efficiency and effectiveness of data-driven tight frame, DDTF-MRI trains an adaptive tight frame to sparsify the to-be-reconstructed MR image. Furthermore, a two-level Bregman iteration algorithm has been developed to solve the proposed model. The proposed method has been compared to two state-of-the-art methods on four datasets and encouraging performances have been achieved by DDTF-MRI.

  1. Packing tight Hamilton cycles in 3-uniform hypergraphs

    CERN Document Server

    Frieze, Alan; Loh, Po-Shen

    2010-01-01

    Let H be a 3-uniform hypergraph with N vertices. A tight Hamilton cycle C \\subset H is a collection of N edges for which there is an ordering of the vertices v_1, ..., v_N such that every triple of consecutive vertices {v_i, v_{i+1}, v_{i+2}} is an edge of C (indices are considered modulo N). We develop new techniques which enable us to prove that under certain natural pseudo-random conditions, almost all edges of H can be covered by edge-disjoint tight Hamilton cycles, for N divisible by 4. Consequently, we derive the corollary that random 3-uniform hypergraphs can be almost completely packed with tight Hamilton cycles w.h.p., for N divisible by 4 and P not too small. Along the way, we develop a similar result for packing Hamilton cycles in pseudo-random digraphs with even numbers of vertices.

  2. Tight Sample Complexity of Large-Margin Learning

    CERN Document Server

    Sabato, Sivan; Tishby, Naftali

    2010-01-01

    We obtain a tight distribution-specific characterization of the sample complexity of large-margin classification with L_2 regularization: We introduce the \\gamma-adapted-dimension, which is a simple function of the spectrum of a distribution's covariance matrix, and show distribution-specific upper and lower bounds on the sample complexity, both governed by the \\gamma-adapted-dimension of the source distribution. We conclude that this new quantity tightly characterizes the true sample complexity of large-margin classification. The bounds hold for a rich family of sub-Gaussian distributions.

  3. Methane Emissions from Leak and Loss Audits of Natural Gas Compressor Stations and Storage Facilities.

    Science.gov (United States)

    Johnson, Derek R; Covington, April N; Clark, Nigel N

    2015-07-07

    As part of the Environmental Defense Fund's Barnett Coordinated Campaign, researchers completed leak and loss audits for methane emissions at three natural gas compressor stations and two natural gas storage facilities. Researchers employed microdilution high-volume sampling systems in conjunction with in situ methane analyzers, bag samples, and Fourier transform infrared analyzers for emissions rate quantification. All sites had a combined total methane emissions rate of 94.2 kg/h, yet only 12% of the emissions total resulted from leaks. Methane slip from exhausts represented 44% of the total emissions. Remaining methane emissions were attributed to losses from pneumatic actuators and controls, engine crankcases, compressor packing vents, wet seal vents, and slop tanks. Measured values were compared with those reported in literature. Exhaust methane emissions were lower than emissions factor estimates for engine exhausts, but when combined with crankcase emissions, measured values were 11.4% lower than predicted by AP-42 as applicable to emissions factors for four-stroke, lean-burn engines. Average measured wet seal emissions were 3.5 times higher than GRI values but 14 times lower than those reported by Allen et al. Reciprocating compressor packing vent emissions were 39 times higher than values reported by GRI, but about half of values reported by Allen et al. Though the data set was small, researchers have suggested a method to estimate site-wide emissions factors for those powered by four-stroke, lean-burn engines based on fuel consumption and site throughput.

  4. Si Tight-Binding Parameters from Genetic Algorithm Fitting

    Science.gov (United States)

    Klimeck, G.; Bowen, R.; Boykin, T.; Salazar-Lazaro, C.; Cwik, T.; Stoica, A.

    1999-01-01

    Quantum mechanical simulations of carrier transport in Si require an accurate model of the complicated Si bandstructure. Tight-binding models are an attractive method of choice since they bear the full electronic structure symmetry in them and they can discretize a realistic device on an atomic scale.

  5. The tight pants syndrome--a sporting variant.

    OpenAIRE

    Jowett, N I; Robinson, C G

    1996-01-01

    Tight neoprene 'warm pants' are increasingly utilised by sportsmen to prevent muscular injury. However, they may impede venous flow from the legs. We describe a case of extensive proximal deep vein thrombosis with subsequent pulmonary embolism in a fit young man with previous hip trauma.

  6. Practical aspects of implementing tight glucose control in the ICU

    NARCIS (Netherlands)

    Vogelzang, Mathijs; Ligtenberg, Jack J. M.

    2007-01-01

    Purpose of review The outcomes of intervention studies implementing intensive insulin therapy aimed at tight glucose control (TGC) are yet not conclusive. There is concern about an increasing incidence of hypoglycemic episodes. Normoglycemia is not easy to obtain in a 'real-life' ICU setting. To fac

  7. Proceedings of the flexible, midsize gas turbine program planning workshop

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    The US Department of Energy (DOE) and the California Energy Commission (CEC) held a program planning workshop on March 4--5, 1997 in Sacramento, California on the subject of a flexible, midsize gas turbine (FMGT). The workshop was also co-sponsored by the Electric Power Research Institute (EPRI), the Gas Research Institute (GRI), the Gas Turbine Association (GTA), and the Collaborative Advanced Gas Turbine Program (CAGT). The purpose of the workshop was to bring together a broad cross section of knowledgeable people to discuss the potential benefits, markets, technical attributes, development costs, and development funding approaches associated with making this new technology available in the commercial marketplace. The participants in the workshop included representatives from the sponsoring organizations, electric utilities, gas utilities, independent power producers, gas turbine manufacturers, gas turbine packagers, and consultants knowledgeable in the power generation field. Thirteen presentations were given on the technical and commercial aspects of the subject, followed by informal breakout sessions that dealt with sets of questions on markets, technology requirements, funding sources and cost sharing, and links to other programs.

  8. Enhanced recovery of unconventional gas. The methodology--Volume III (of 3 volumes)

    Energy Technology Data Exchange (ETDEWEB)

    Kuuskraa, V. A.; Brashear, J. P.; Doscher, T. M.; Elkins, L. E.

    1979-02-01

    The methodology is described in chapters on the analytic approach, estimated natural gas production, recovery from tight gas sands, recovery from Devonian shales, recovery from coal seams, and recovery from geopressured aquifers. (JRD)

  9. Development of a compositional model fully coupled with geomechanics and its application to tight oil reservoir simulation

    Science.gov (United States)

    Xiong, Yi

    solutions and results of a commercial simulator before conducting numerical studies. The numerical studies demonstrate the effect of capillary pressure on VLE, and further on production performance. The significant effect of capillary pressure on VLE leads to the suppression of bubble-point pressure and more light components dissolved in the oil phase. Consequently it is observed that there is smaller gas saturation, larger mole fractions of light components, and faster pressure decreasing at reservoir conditions; meanwhile less gas and more oil are produced at surface. The substantial decrease in reservoir pore pressure results in a large increase of effective stress, which induces the changes of rock properties and influences the production performance. The stress-induced degradation of permeability undermines the production performance, and the geomechanical effect on the permeability of natural fractures is mainly responsible for the undermined production performance. The reduction of pore size due to the geomechanical effect could increase the capillary pressure, which enlarges the influence of capillarity on VLE and further suppresses bubble-point pressure. On the other hand, the effect of capillary pressure on VLE influences the fluid flow and therefore influences the effective stress through the flow-stress coupling process. Thus the interaction between pore confinement and rock compaction can be modeled with MSFLOW_COM, and illustrated through numerical studies. This research provides a three-dimensional numerical tool for accurately modeling porous and fractured tight oil reservoirs. The developed simulator is able to assist scientists and engineers to study and understand the complex multiphase, multi-component fluid flow behaviors in tight oil reservoirs.

  10. A method for determining transverse permeability of tight reservoir cores by radial pressure pulse decay measurement

    Science.gov (United States)

    Yang, Zehao; Dong, Mingzhe; Zhang, Shaojie; Gong, Houjian; Li, Yajun; Long, Feifei

    2016-10-01

    A transverse pressure pulse decay (TPPD) method is presented to measure transverse permeability of tight reservoir cores in a cell with finite volume. Given appropriate assumptions, a mathematical model based on the specially designed experiment is formulated, and its general solution is proposed. Early-time and late-time techniques are further presented for convenient postprocessing applications of experimental data. Meanwhile, sensitivity analysis of TPPD method is given. It is found that a good TPPD experimental principle can be obtained by adjusting test gas, experimental pressure, dimension of core sample, and volume ratio (λ). The volume ratio error (λerror) analysis reveals the following: (1) a larger λerror results in increased transverse permeability error (kerror); (2) the volume ratio (λ) is better not very close to 0.754; (3) when λ is equal to or greater than 1, the kerror resulting from λerror is monotonic decreasing as the volume ratio increases. In practice, λ is usually equal to or greater than 1 due to the very small pore volume of a tight core. But this does not mean that the volume ratio should be as large as possible. The reason for this is that a pressure transducer with higher resolution is needed to record pressure change. That means experimental apparatus is much more costly. And such a TPPD experiment requires a much longer time to attain the late-time straight line behavior. The best choice is to find an optimal balance point among experimental cost, time, and accuracy.

  11. Helium-tight Laser Beam Welding of Aluminum with Brillant Laser Beam Radiation

    Science.gov (United States)

    Heinen, Paul; Wu, Hao; Olowinsky, Alexander; Gillner, Arnold

    The substitution of steel as base metal for casings and packaging applications has increased during the last years. Especially aluminum with advantages in weight and machining effort has become a versatile solution for applications in fine mechanics (e.g. sensor housings) and automotive applications. Joining of aluminum components is more critical due to possible crack formation in the joining seam and uneven seam geometry. With the high intensity of brillant laser beam sources the specific challenges of aluminum welding can be overcome. Due to its hydrogen affinity and high degree of reflection for laser radiation at a wavelength of 1 μm (95%) aluminum needs to be welded with proper shielding gas support and high beam quality in order to avoid seam defects. Cracks and pores can lead to non-sufficient tightness for sensor applications and early failure. Housing components have been joined to form a functioning unit in order to seal electrical or measuring components, which are helium-tight for these applications.

  12. Tight reservoir bag: the bag itself may be the culprit.

    Science.gov (United States)

    Umesh, Goneppanavar; Jasvinder, Kaur

    2010-06-01

    Numerous possibilities exist which may cause obstruction to ventilation under anesthesia resulting in a tight reservoir bag with low compliance. We report an interesting case where a reservoir bag twisted around its own neck and resulted in a tight bag situation. The neck portion of the reservoir bag would be hidden from the view of anesthesiologists in head and neck surgery and hence it is easier to miss early recognition of the twist. We caution all anesthesiologists using the disposable modified Jackson-Rees breathing system to be aware of such an eventuality. We also urge the manufacturer to consider strengthening the neck of the reservoir bag by improving the quality of the material used for its construction.

  13. Preconditioning Filter Bank Decomposition Using Structured Normalized Tight Frames

    Directory of Open Access Journals (Sweden)

    Martin Ehler

    2015-01-01

    Full Text Available We turn a given filter bank into a filtering scheme that provides perfect reconstruction, synthesis is the adjoint of the analysis part (so-called unitary filter banks, all filters have equal norm, and the essential features of the original filter bank are preserved. Unitary filter banks providing perfect reconstruction are induced by tight generalized frames, which enable signal decomposition using a set of linear operators. If, in addition, frame elements have equal norm, then the signal energy is spread through the various filter bank channels in some uniform fashion, which is often more suitable for further signal processing. We start with a given generalized frame whose elements allow for fast matrix vector multiplication, as, for instance, convolution operators, and compute a normalized tight frame, for which signal analysis and synthesis still preserve those fast algorithmic schemes.

  14. Maximally Localized Radial Profiles for Tight Steerable Wavelet Frames.

    Science.gov (United States)

    Pad, Pedram; Uhlmann, Virginie; Unser, Michael

    2016-05-01

    A crucial component of steerable wavelets is the radial profile of the generating function in the frequency domain. In this paper, we present an infinite-dimensional optimization scheme that helps us find the optimal profile for a given criterion over the space of tight frames. We consider two classes of criteria that measure the localization of the wavelet. The first class specifies the spatial localization of the wavelet profile, and the second that of the resulting wavelet coefficients. From these metrics and the proposed algorithm, we construct tight wavelet frames that are optimally localized and provide their analytical expression. In particular, one of the considered criterion helps us finding back the popular Simoncelli wavelet profile. Finally, the investigation of local orientation estimation, image reconstruction from detected contours in the wavelet domain, and denoising indicate that optimizing wavelet localization improves the performance of steerable wavelets, since our new wavelets outperform the traditional ones.

  15. Differences between tight and loose cultures: a 33-nation study.

    Science.gov (United States)

    Gelfand, Michele J; Raver, Jana L; Nishii, Lisa; Leslie, Lisa M; Lun, Janetta; Lim, Beng Chong; Duan, Lili; Almaliach, Assaf; Ang, Soon; Arnadottir, Jakobina; Aycan, Zeynep; Boehnke, Klaus; Boski, Pawel; Cabecinhas, Rosa; Chan, Darius; Chhokar, Jagdeep; D'Amato, Alessia; Ferrer, Montse; Fischlmayr, Iris C; Fischer, Ronald; Fülöp, Marta; Georgas, James; Kashima, Emiko S; Kashima, Yoshishima; Kim, Kibum; Lempereur, Alain; Marquez, Patricia; Othman, Rozhan; Overlaet, Bert; Panagiotopoulou, Penny; Peltzer, Karl; Perez-Florizno, Lorena R; Ponomarenko, Larisa; Realo, Anu; Schei, Vidar; Schmitt, Manfred; Smith, Peter B; Soomro, Nazar; Szabo, Erna; Taveesin, Nalinee; Toyama, Midori; Van de Vliert, Evert; Vohra, Naharika; Ward, Colleen; Yamaguchi, Susumu

    2011-05-27

    With data from 33 nations, we illustrate the differences between cultures that are tight (have many strong norms and a low tolerance of deviant behavior) versus loose (have weak social norms and a high tolerance of deviant behavior). Tightness-looseness is part of a complex, loosely integrated multilevel system that comprises distal ecological and historical threats (e.g., high population density, resource scarcity, a history of territorial conflict, and disease and environmental threats), broad versus narrow socialization in societal institutions (e.g., autocracy, media regulations), the strength of everyday recurring situations, and micro-level psychological affordances (e.g., prevention self-guides, high regulatory strength, need for structure). This research advances knowledge that can foster cross-cultural understanding in a world of increasing global interdependence and has implications for modeling cultural change.

  16. Tight inequalities for qutrit state-independent contextuality

    CERN Document Server

    Cabello, Adan; Gühne, Otfried; Kleinmann, Matthias; Larsson, Jan-Ake

    2012-01-01

    Recently, Yu and Oh have proposed a noncontextuality inequality [Phys. Rev. Lett. 108, 030402 (2012)] which involves the simplest and hence most fundamental scenario for state-independent quantum contextuality. As we show, Yu and Oh's inequality is neither tight (i.e., it does not belong to the minimal set which completely separates contextual and noncontextual correlations) nor optimal (i.e., its quantum violation is not maximal). Moreover, we provide a method for obtaining state-independent noncontextuality inequalities with the maximal violation and, using it, we identify two essentially different state-independent tight inequalities with maximal quantum violation for Yu and Oh's scenario. These inequalities allow for an easier and more significant experimental test of qutrit state-independent quantum contextuality.

  17. Automatic generation of matrix element derivatives for tight binding models

    Science.gov (United States)

    Elena, Alin M.; Meister, Matthias

    2005-10-01

    Tight binding (TB) models are one approach to the quantum mechanical many-particle problem. An important role in TB models is played by hopping and overlap matrix elements between the orbitals on two atoms, which of course depend on the relative positions of the atoms involved. This dependence can be expressed with the help of Slater-Koster parameters, which are usually taken from tables. Recently, a way to generate these tables automatically was published. If TB approaches are applied to simulations of the dynamics of a system, also derivatives of matrix elements can appear. In this work we give general expressions for first and second derivatives of such matrix elements. Implemented in a tight binding computer program, like, for instance, DINAMO, they obviate the need to type all the required derivatives of all occurring matrix elements by hand.

  18. Ab initio calculation of tight-binding parameters

    Energy Technology Data Exchange (ETDEWEB)

    McMahan, A.K.; Klepeis, J.E.

    1997-12-01

    We calculate ab initio values of tight-binding parameters for the f- electron metal Ce and various phases of Si, from local-density functional one-electron Hamiltonian and overlap matrix elements. Our approach allows us to unambiguously test the validity of the common minimal basis and two-center approximations as well as to determine the degree of transferability of both nonorthogonal and orthogonal hopping parameters in the cases considered.

  19. Tightly Coupling GPS with Lane Markings for Autonomous Vehicle Navigation

    OpenAIRE

    2014-01-01

    International audience; Tightly coupling GPS pseudorange and Doppler measurements with other sensors is a way to increase accuracy and integrity of the positioning information particularly when it is computed autonomously. Highly accurate digital maps are also more and more key components for autonomous vehicle navigation and can enhance the localization system. In this paper, a video camera is used to get relative information with respect to lane markings and dead-reckoning sensors are also ...

  20. Tightness for Maxima of Generalized Branching Random Walks

    CERN Document Server

    Fang, Ming

    2010-01-01

    We study generalized branching random walks, which allow time dependence and local dependence between siblings. Under appropriate tail assumptions, we prove the tightness of $F_n(\\cdot-Med(F_n))$, where $F_n(\\cdot)$ is the maxima distribution at time $n$ and $Med(F_n)$ is the median of $F_n(\\cdot)$. The main component in the argument is a proof of exponential decay of the right tail $1-F_n(\\cdot-Med(F_n))$.

  1. Implementing tight glucose control after coronary artery bypass surgery.

    Science.gov (United States)

    Carr, Justine M; Sellke, Frank W; Fey, Michelle; Doyle, Mathew J; Krempin, Judy A; de la Torre, Ralph; Liddicoat, John R

    2005-09-01

    The clinical benefit of tight glucose control has been demonstrated in diabetic patients. In adopting an approach of tight glucose control for all cardiac surgery patients at Beth Israel Deaconess Medical Center, we encountered several challenges, including defining good glucose control, meaningfully measuring control, and assessing the impact of variables that may affect control. An interdisciplinary team used an insulin protocol to achieve tight glucose control of cardiac surgery patients in the operating room and intensive care unit as part of an effort to reduce sternal wound infections. Good control was defined as glucose less than 130 mg/dL for more than 50% of measured time. Eight hundred eighteen patients underwent coronary artery bypass grafting between November 2002 and August 2004. Seven hundred thirty-seven (90%) received insulin. Fifty-seven percent did not have a preoperative diagnosis of diabetes. The trigger for insulin initiation was decreased sequentially from 150 mg/dL to 110 mg/dL, but the measure of good control remained the same: glucose less than 130 mg/dL. The factor most highly predictive of glucose being well controlled was the protocol with the 110 mg/dL trigger for insulin (p < 0.001). Patient factors such as age, ejection fraction, preoperative angiotensin-converting enzyme inhibitor or beta-blocker use, or time on cardiopulmonary bypass were not significantly associated with glucose control. During the course of the protocols, the rate of mediastinitis decreased from 1.6% to 0%. Key elements to implementing tight glucose control include having a standard protocol and metrics to track protocol performance. This practice improved control and was associated with a marked reduction in mediastinitis.

  2. Symmetry-Based Tight Binding Modeling of Halide Perovskite Semiconductors

    OpenAIRE

    Boyer-Richard, Soline; Katan, Claudine; Traoré, Boubacar; Scholz, Reinhard; Jancu, Jean-Marc; Even, Jacky

    2016-01-01

    International audience; On the basis of a general symmetry analysis, this paper presents an empirical tight-binding (TB) model for the reference Pm-3m perovskite cubic phase of halide perovskites of general formula ABX3. The TB electronic band diagram, with and without spin orbit coupling effect of MAPbI3 has been determined based on state of the art density functional theory results including many body corrections (DFT+GW). It affords access to various properties, including distorted structu...

  3. Hepatic tight junctions:From viral entry to cancer metastasis

    Institute of Scientific and Technical Information of China (English)

    Nikki; P; Lee; John; M; Luk

    2010-01-01

    The tight junction (TJ) is a critical cellular component for maintenance of tissue integrity, cellular interactions and cell-cell communications, and physiologically functions as the "great wall" against external agents and the surrounding hostile environment. During the host-pathogen evolution, viruses somehow found the key to unlock the gate for their entry into cells and to exploit and exhaust the host cells. In the liver, an array of TJ molecules is localized along the bile canaliculi forming the blood-...

  4. Hydrogen bonding in the protic ionic liquid triethylammonium nitrate explored by density functional tight binding simulations

    Science.gov (United States)

    Zentel, Tobias; Kühn, Oliver

    2016-12-01

    The applicability of the density functional based tight binding (DFTB) method to the description of hydrogen bond dynamics and infrared (IR) spectroscopy is addressed for the exemplary protic ionic liquid triethylammonium nitrate. Potential energy curves for proton transfer in gas and liquid phases are shown to be comparable to the high level coupled cluster theory in the thermally accessible range of bond lengths. Geometric correlations in the hydrogen bond dynamics are analyzed for a cluster of six ion pairs. Comparing DFTB and DFT data lends further support for the reliability of the DFTB method. Therefore, DFTB bulk simulations are performed to quantify the extent of geometric correlations in terms of Pauling's bond order model. Further, IR absorption spectra are obtained using DFTB and analyzed putting emphasis on the signatures of hydrogen bonding in the NH-stretching and far IR hydrogen bond range.

  5. Hydrogen bonding in the protic ionic liquid triethylammonium nitrate explored by density functional tight binding simulations

    CERN Document Server

    Zentel, Tobias

    2016-01-01

    The applicability of the density functional based tight binding (DFTB) method to the description of hydrogen bond dynamics and infrared spectroscopy is addressed for the exemplary protic ionic liquid triethylammonium nitrate. Potential energy curves for proton transfer in gas and liquid phase are shown to be comparable to high level coupled cluster theory in the thermally accessible range of bond lengths. Geometric correlations in the hydrogen bond dynamics are analyzed for a cluster of six ion pairs. Comparing DFTB and regular DFT data lends further support for the reliability of the DFTB method. Therefore, DFTB bulk simulations are performed to quantify the extent of geometric correlations in terms of Pauling's bond order model. Further, infrared (IR) absorption spectra are obtained and analyzed putting emphasis on the signatures of hydrogen bonding in the NH-stretching and far IR hydrogen bond range.

  6. Accurate Modeling of Organic Molecular Crystals by Dispersion-Corrected Density Functional Tight Binding (DFTB).

    Science.gov (United States)

    Brandenburg, Jan Gerit; Grimme, Stefan

    2014-06-05

    The ambitious goal of organic crystal structure prediction challenges theoretical methods regarding their accuracy and efficiency. Dispersion-corrected density functional theory (DFT-D) in principle is applicable, but the computational demands, for example, to compute a huge number of polymorphs, are too high. Here, we demonstrate that this task can be carried out by a dispersion-corrected density functional tight binding (DFTB) method. The semiempirical Hamiltonian with the D3 correction can accurately and efficiently model both solid- and gas-phase inter- and intramolecular interactions at a speed up of 2 orders of magnitude compared to DFT-D. The mean absolute deviations for interaction (lattice) energies for various databases are typically 2-3 kcal/mol (10-20%), that is, only about two times larger than those for DFT-D. For zero-point phonon energies, small deviations of <0.5 kcal/mol compared to DFT-D are obtained.

  7. Polynomial fitting of tight-binding method in carbon

    Science.gov (United States)

    Haa, Wai Kang; Yeak, Su Hoe

    2017-04-01

    Carbon is very unique in among the elements and its ability to form strong chemical bonds with a variety number such as two carbons (graphene) and four carbons (diamond). This combination of strong bonds with tight mass and high melting point makes them technologically and scientifically important in nanoscience development. Tight-binding model (TB) is one of the semi-empirical approximations used in quantum mechanical world which is restricted to the Linear Combinations of Localized Atomic Orbitals (LCAO). Currently, there are many approaches in tight-binding calculation. In this paper, we have reproduced a polynomial scaling function by fitting to the TB model. The model is then applied into carbon molecules and obtained the energy bands of the system. The elements of the overlap Hamiltonian matrix in the model will be depending on the parameter of the polynomials. Our purpose is to find out a set of parameters in the polynomial which were commonly fit to an independently calculated band structure. We used minimization approach to calculate the polynomial coefficients which involves differentiation of eigenvalues in the eigensystem. The algorithm of fitting the parameters is carried out in FORTRAN.

  8. Tight junction regulates epidermal calcium ion gradient and differentiation

    Energy Technology Data Exchange (ETDEWEB)

    Kurasawa, Masumi; Maeda, Tetsuo; Oba, Ai; Yamamoto, Takuya [Pola Chemical Industries Inc., 560 Kashio-cho, Totsuka-ku, Yokohama 244-0812 (Japan); Sasaki, Hiroyuki, E-mail: sasakih@jikei.ac.jp [Division of Fine Morphology, Core Research Facilities, The Jikei University School of Medicine, Minato-ku, Tokyo 105-8461 (Japan); The Center for Advanced Medical Engineering and Infomatics, Osaka University, Osaka 565-0871 (Japan)

    2011-03-25

    Research highlights: {yields} We disrupted epidermal tight junction barrier in reconstructed epidermis. {yields} It altered Ca{sup 2+} distribution and consequentially differentiation state as well. {yields} Tight junction should affect epidermal homeostasis by maintaining Ca{sup 2+} gradient. -- Abstract: It is well known that calcium ions (Ca{sup 2+}) induce keratinocyte differentiation. Ca{sup 2+} distributes to form a vertical gradient that peaks at the stratum granulosum. It is thought that the stratum corneum (SC) forms the Ca{sup 2+} gradient since it is considered the only permeability barrier in the skin. However, the epidermal tight junction (TJ) in the granulosum has recently been suggested to restrict molecular movement to assist the SC as a secondary barrier. The objective of this study was to clarify the contribution of the TJ to Ca{sup 2+} gradient and epidermal differentiation in reconstructed human epidermis. When the epidermal TJ barrier was disrupted by sodium caprate treatment, Ca{sup 2+} flux increased and the gradient changed in ion-capture cytochemistry images. Alterations of ultrastructures and proliferation/differentiation markers revealed that both hyperproliferation and precocious differentiation occurred regionally in the epidermis. These results suggest that the TJ plays a crucial role in maintaining epidermal homeostasis by controlling the Ca{sup 2+} gradient.

  9. Root canal hydrophobization by dentinal silanization: improvement of silicon-based endodontic treatment tightness.

    Science.gov (United States)

    Collart Dutilleul, Pierre-Yves; Fonseca, Cesar Gaitán; Zimányi, László; Romieu, Olivier; Pozos-Guillén, Amaury J; Semetey, Vincent; Cuisinier, Frédéric; Pérez, Elías; Levallois, Bernard

    2013-07-01

    A new strategy to improve silicon-based endodontic treatment tightness by dentine hydrophobization is presented in this work: root dentine was silanized to obtain a hydrophobic dentine-sealer interface that limits fluid penetration. This strategy was based on the grafting of aliphatic carbon chains on the dentine through a silanization with the silane end groups [octadecyltrichlorosilane (OTS) and octadecyltriethoxysilane]. Dentine surface was previously pretreated, applying ethylenediaminetetraacetic acid and sodium hypochlorite, to expose hydroxyl groups of collagen for the silane grafting. Collagen fibers exposure after pretreatment was visible with scanning electron microscopy, and Fourier transform infrared (FTIR) spectroscopy showed their correct exposition for the silanization (amide I and II, with 1630, 1580, and 1538 cm⁻¹ peaks corresponding to the vibration of C=O and C--N bonds). The grafting of aliphatic carbon chains was confirmed by FTIR (peaks at 2952 and 2923 cm⁻¹ corresponding to the stretching of C--H bonds) and by the increasing of the water contact angle. The most efficient hydrophobization was obtained with OTS in ethyl acetate, with a water contact angle turning from 51° to 109°. Gas and liquid permeability tests showed an increased seal tightness after silanization: the mean gas and water flows dropped from 2.02 × 10⁻⁸ to 1.62 × 10⁻⁸ mol s⁻¹ and from 10.8 × 10⁻³ to 5.4 × 10⁻³ µL min⁻¹, respectively. These results show clear evidences to turn hydrophilic dentine surface into a hydrophobic surface that may improve endodontic sealing.

  10. The Role of the Rock on Hydraulic Fracturing of Tight Shales

    Science.gov (United States)

    Suarez-Rivera, R.; Green, S.; Stanchits, S.; Yang, Y.

    2011-12-01

    Successful economic production of oil and gas from nano-darcy-range permeability, tight shale reservoirs, is achieved via massive hydraulic fracturing. This is so despite their limited hydrocarbon in place, on per unit rock volume basis. As a reference, consider a typical average porosity of 6% and an average hydrocarbon saturation of 50% to 75%. The importance of tight shales results from their large areal extent and vertical thickness. For example, the areal extent of the Anwar field in Saudi Arabia of 3230 square miles (and 300 ft thick), while the Marcellus shale alone is over 100,000 square miles (and 70 to 150 ft thick). The low permeability of the rock matrix, the predominantly mineralized rock fabric, and the high capillary forces to both brines and hydrocarbons, restrict the mobility of pore fluids in these reservoirs. Thus, one anticipates that fluids do not move very far within tight shales. Successful production, therefore results from maximizing the surface area of contact with the reservoir by massive hydraulic fracturing from horizontal bore holes. This was the conceptual breakthrough of the previous decade and the one that triggered the emergence of gas shales, and recently oily shales, as important economic sources of energy. It is now understood that the process can be made substantially more efficient, more sustainable, and more cost effective by understanding the rock. This will be the breakthrough of this decade. Microseismic monitoring, mass balance calculations, and laboratory experiments of hydraulic fracturing on tight shales indicate the development of fracture complexity and fracture propagation that can not be explained in detail in this layered heterogeneous media. It is now clear that in tight shales the large-scale formation fabric is responsible for fracture complexity. For example, the presence and pervasiveness of mineralized fractures, bed interfaces, lithologic contacts, and other types of discontinuities, and their orientation

  11. Diagenesis of low-permeability and tight sandstone gas reservoir and its effect on reservoir quality: taking the eighth member of Shihezi formation in Su 48 block, Sulige gas field, as an example%低渗透致密气藏成岩作用及对储层物性的影响——以苏里格气田苏48区块盒8段储层为例

    Institute of Scientific and Technical Information of China (English)

    庞振宇; 孙卫; 赵春龙; 马永平

    2012-01-01

    利用普通薄片、铸体薄片、X射线衍射、扫描电镜等资料,分析苏里格气田苏48区块盒8段低渗透储层岩石学特征、成岩作用和孔隙演化过程.研究表明:储集层砂岩类型以岩屑石英砂岩和石英砂岩为主,颗粒分选性中等-好,磨圆度较差,胶结类型以次生加大-孔隙式为主,少量孔隙式胶结.在成岩过程中,强烈的压实作用造成了初始孔隙度的大量丧失,损失率为69.09%,其次为胶结作用,损失率为25.16%.溶蚀作用则形成大量次生孔隙,增加了5.82%的孔隙度,大大改善了储层物性,为该区气藏的聚集提供了主要储集空间.%The characteristics of petrology, the diagenesis and porosity evolution in the eighth member of Shihezi formation in Su 48 block in Sulige gasfield were analyzed, using thin-sections, casting thin-sections, X-ray diffractions, scanning electron micrograph observations, etc. The results showed that both lithic quartz-sandstone and quartz sandstone are the essential components of reservoir sandstones. The sandstone is lithic quartz with middle to perfect sorting and poor psephicity. Cementation is mainly of secondary enlargement-pore and a less proportion of pore cementation. The impact of strong compaction during the early diagenesis was greatest and its porosity loss-rate was 69.09%, and the porosity loss-rate of of cementation was 25.16%. The dissolution of the reservoir sandstone improved the porosity by about 5.82%, which provided the main space for the accumulation of gas reservoirs.

  12. Computational fluid dynamics analysis of a synthesis gas turbulent combustion in a round jet burner

    Science.gov (United States)

    Mansourian, Mohammad; Kamali, Reza

    2017-05-01

    In this study, the RNG-Large Eddy Simulation (RNG-LES) methodology of a synthesis gas turbulent combustion in a round jet burner is investigated, using OpenFoam package. In this regard, the extended EDC extinction model of Aminian et al. for coupling the reaction and turbulent flow along with various reaction kinetics mechanisms such as Skeletal and GRI-MECH 3.0 have been utilized. To estimate precision and error accumulation, we used the Smirinov's method and the results are compared with the available experimental data under the same conditions. As a result, it was found that the GRI-3.0 reaction mechanism has the least computational error and therefore, was considered as a reference reaction mechanism. Afterwards, we investigated the influence of various working parameters including the inlet flow temperature and inlet velocity on the behavior of combustion. The results show that the maximum burner temperature and pollutant emission are affected by changing the inlet flow temperature and velocity.

  13. Natural gas; Gas Natural

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, Carlos A.; Moraes, Claudia C.D. [Eletricidade de Sao Paulo S.A. (ELETROPAULO), Sao Paulo, SP (Brazil); Fonseca, Carlos H.F. [Centrais Eletricas de Santa Catarina S.A., Florianopolis, SC (Brazil); Silva, Clecio Fabricio da; Alves, Ricardo P. [Companhia Paranaense de Energia (COPEL), Curitiba, PR (Brazil); Sposito, Edivaldo Soares; Hulle, Lutero [Espirito Santo Centrais Eletricas S.A. (ESCELSA), Vitoria, ES (Brazil); S. Martins, Icaro da [Centrais Eletricas do Norte do Brasil S.A. (ELETRONORTE), Belem, PA (Brazil); Vilhena, Joao Luiz S. de [Companhia Energetica de Minas Gerais (CEMIG), Belo Horizonte, MG (Brazil); Fagundes, Zaluar Aquino [Companhia Estadual de Energia Eletrica do Estado do Rio Grande do Sul, Porto Alegre, RS (Brazil)

    1996-12-31

    An increase in the consumption of natural gas in Brazil is an expected fact in what concerns energetic planning. This work presents the existing situation in what concerns natural gas utilization in the main world economies, as well as an analysis of the participation of this fuel among the energy final consumption per sources. The Brazilian consumption of natural gas is also analysed as well as the international agreement between Brazil and Bolivia for natural gas commercialization. Some legal, institutional and political aspects related to natural gas commercialization are also discussed. Finally, several benefits to be brought by the utilization of natural gas are presented 10 refs., 3 tabs.

  14. Proceedings of the natural gas research and development contractors review meeting

    Energy Technology Data Exchange (ETDEWEB)

    Malone, R.D.; Shoemaker, H.D.; Byrer, C.W. (eds.)

    1990-11-01

    The purpose of this meeting was to present results of the research in the DOE-sponsored Natural Gas Program, and simultaneously to provide a forum for real-time technology transfer, to the active research community, to the interested public, and to the natural gas industry, who are the primary users of this technology. The current research focus is to expand the base of near-term and mid-term economic gas resources through research activities in Eastern Tight Gas, Western Tight Gas, Secondary Gas Recovery (increased recovery of gas from mature fields); to enhance utilization, particularly of remote gas resources through research in Natural Gas to Liquids Conversion; and to develop additional, long term, potential gas resources through research in Gas Hydrates and Deep Gas. With the increased national emphasis on the use of natural gas, this forum has been expanded to include summaries of DOE-sponsored research in energy-related programs and perspectives on the importance of gas to future world energy. Thirty-two papers and fourteen poster presentations were given in seven formal, and one informal, sessions: Three general sessions (4 papers); Western Tight Gas (6 papers); Eastern Tight Gas (8 papers); Conventional/Speculative Resources (8 papers); and Gas to Liquids (6 papers). Individual reports are processed separately on the data bases.

  15. Assessment of existing H2/O2 chemical reaction mechanisms at reheat gas turbine conditions

    CERN Document Server

    Weydahl, Torleif; Seljeskog, Morten; Haugen, Nils Erland L

    2011-01-01

    This paper provides detailed comparisons of chemical reaction mechanisms of H2 applicable at high preheat temperatures and pressures relevant to gas turbine and particularly Alstom's reheat gas turbine conditions. It is shown that the available reaction mechanisms exhibit large differences in several important elementary reaction coefficients. The reaction mechanisms are assessed by comparing ignition delay and laminar flame speed results obtained from CHEMKIN with available data, however, the amount of data at these conditions is scarce and a recommended candidate among the mechanisms can presently not be selected. Generally, the results with the GRI-Mech and Leeds mechanisms deviate from the Davis, Li, O'Conaire, Konnov and San Diego mechanisms, but there are also significant deviations between the latter five mechanisms that altogether are better adapted to hydrogen. The differences in ignition delay times between the dedicated hydrogen mechanisms (O'Conaire, Li and Konnov) range from approximately a maxim...

  16. Particle dynamics and pair production in tightly focused standing wave

    Science.gov (United States)

    Jirka, M.; Klimo, O.; Vranić, M.; Weber, S.; Korn, G.

    2017-05-01

    With the advent of 10 PW laser facilities, new regimes of laser-matter interaction are opening since effects of quantum electrodynamics, such as electron-positron pair production and cascade development, start to be important. The dynamics of light charged particles, such as electrons and positrons, is affected by the radiation reaction force. This effect can strongly influence the interaction of intense laser pulses with matter since it lowers the energy of emitting particles and transforms their energy to the gamma radiation. Consequently, electron-positron pairs can be generated via Breit-Wheeler process. To study this new regime of interaction, numerical simulations are required. With their help it is possible to predict and study quantum effects which may occur in future experiments at modern laser facilities. In this work we present results of electron interaction with an intense standing wave formed by two colliding laser pulses. Due to the necessity to achieve ultra intense laser field, the laser beam has to be focused to a μm-diameter spot. Since the paraxial approximation is not valid for tight focusing, the appropriate model describing the tightly focused laser beam has to be employed. In tightly focused laser beam the longitudinal component of the electromagnetic field becomes significant and together with the ponderomotive force they affect the dynamics of interacting electrons and also newly generated Breit-Wheeler electron-positron pairs. Using the Particle-In-Cell code we study electron dynamics, gamma radiation and pair production in such a configuration for linear polarization and different types of targets.

  17. Tight glycemic control in the ICU - is the earth flat?

    Science.gov (United States)

    Steil, Garry M; Agus, Michael S D

    2014-06-27

    Tight glycemic control in the ICU has been shown to reduce mortality in some but not all prospective randomized control trials. Confounding the interpretation of these studies are differences in how the control was achieved and underlying incidence of hypoglycemia, which can be expected to be affected by the introduction of continuous glucose monitoring (CGM). In this issue of Critical Care, a consensus panel provides a list of the research priorities they believe are needed for CGM to become routine practice in the ICU. We reflect on these recommendations and consider the implications for using CGM today.

  18. Effects of gastrocnemius tightness on forefoot during gait.

    Science.gov (United States)

    Cazeau, Cyrille; Stiglitz, Yves

    2014-12-01

    The gastrocnemius is the main muscle of the posterior compartment of the leg. As a biarticular muscle it has specific biomechanical propertiess. This article discusses these properties combining the major biomechanical topics of anatomy, dynamics, kinetics, and electromyography. This muscle is remarkable in that it has very low energy consumption and very high mechanical efficacy. In addition to the biomechanical features, the consequences of its tightness are discussed. The dysfunction also appears in all the biomechanical topics and clarifies the reasons of the location of symptoms in the midfoot and on the plantar aspect of the forefoot.

  19. Effective-medium tight-binding model for silicon

    DEFF Research Database (Denmark)

    Stokbro, Kurt; Chetty, N.; Jacobsen, Karsten Wedel

    1994-01-01

    A method for calculating the total energy of Si systems, which is based on the effective-medium-theory concept of a reference system, is presented. Instead of calculating the energy of an atom in the system of interest, a reference system is introduced where the local surroundings are similar. Th...... and detailed description of the method is given together with test calculations of the energies of phonons, elastic constants, different structures, surfaces, and surface reconstructions. We compare the results to calculations using an empirical tight-binding scheme....

  20. A characterization of tight and dual generalized translation invariant frames

    DEFF Research Database (Denmark)

    Jakobsen, Mads Sielemann; Lemvig, Jakob

    2015-01-01

    We present results concerning generalized translation invariant (GTI) systems on a second countable locally compact abelian group G. These are systems with a family of generators {gj, P}jεJ, pεPJ ⊂ L2(G), where J is a countable index set, and Pj, j ε J are certain measure spaces. Furthermore, for...... such systems form tight frames, and when two GTI Bessel systems form dual frames for L2(G). In particular, this offers a unified approach to the theory of discrete and continuous frames and, e.g., yields well known results for discrete and continuous Gabor and wavelet systems....

  1. Relativistic tight-binding model: Application to Pt surfaces

    Science.gov (United States)

    Tchernatinsky, A.; Halley, J. W.

    2011-05-01

    We report a parametrization of a previous self-consistent tight-binding model, suitable for metals with a high atomic number in which nonscalar-relativistic effects are significant in the electron physics of condensed phases. The method is applied to platinum. The model is fitted to density functional theory band structures and cohesive energies and spectroscopic data on platinum atoms in five oxidation states, and is then shown without further parametrization to correctly reproduce several low index surface structures. We also predict reconstructions of some vicinal surfaces.

  2. Scattering matrix of arbitrary tight-binding Hamiltonians

    Science.gov (United States)

    Ramírez, C.; Medina-Amayo, L. A.

    2017-03-01

    A novel efficient method to calculate the scattering matrix (SM) of arbitrary tight-binding Hamiltonians is proposed, including cases with multiterminal structures. In particular, the SM of two kinds of fundamental structures is given, which can be used to obtain the SM of bigger systems iteratively. Also, a procedure to obtain the SM of layer-composed periodic leads is described. This method allows renormalization approaches, which permits computations over macroscopic length systems without introducing additional approximations. Finally, the transmission coefficient of a ring-shaped multiterminal system and the transmission function of a square-lattice nanoribbon with a reduced width region are calculated.

  3. Materials processing with a tightly focused femtosecond laser vortex pulse.

    Science.gov (United States)

    Hnatovsky, Cyril; Shvedov, Vladlen G; Krolikowski, Wieslaw; Rode, Andrei V

    2010-10-15

    In this Letter we present the first (to our knowledge) demonstration of material modification using tightly focused single femtosecond laser vortex pulses. Double-charge femtosecond vortices were synthesized with a polarization-singularity beam converter based on light propagation in a uniaxial anisotropic medium and then focused using moderate- and high-NA optics (viz., NA=0.45 and 0.9) to ablate fused silica and soda-lime glass. By controlling the pulse energy, we consistently machine micrometer-size ring-shaped structures with <100nm uniform groove thickness.

  4. Air tightness measurements in older Danish single-family houses

    DEFF Research Database (Denmark)

    Mortensen, Lone Hedegaard; Bergsøe, Niels Christian

    2017-01-01

    presents the results of measurements in 16 single-family houses built between 1880 and 2007. The air tightness of the building envelope was measured according to EN ISO 9972 using the blower-door technique. The results are compared with measurement results of the average air-change rate in the same houses....... In addition, leaks are observed around older windows and doors and in connection with wooden ceilings and attic hatches. The findings should be taken into account when renovating older single-family houses....

  5. Tight Lower Bounds on Envy-Free Makespan Approximation

    CERN Document Server

    Fiat, Amos

    2012-01-01

    In this work we give a tight lower bound on makespan approximations for envy-free allocation mechanism dedicated to scheduling tasks on unrelated machines. Specifically, we show that no mechanism exists that can guarantee an envy-free allocation of jobs to $m$ machines with a makespan of less than a factor of $O(\\log m)$ of the minimal makespan. Combined with previous results, this paper definitively proves that the optimal algorithm for obtaining a minimal makespan for any envy-free division can at best approximate the makespan to a factor of $O(\\log m)$.

  6. Engineering support services for the DOE/GRI coal-gasification research program. Monthly technical progress report, 22 August - 25 September, 1981

    Energy Technology Data Exchange (ETDEWEB)

    Bostwick, L.E.; Ethridge, T.R.; Starr, D.W.; Hubbard, D.A.; Koneru, P.B.; Smith, M.R.; Ward, W.E.; Wong, E.W.

    1982-01-01

    The objective of this contract is to provide engineering support services to the Department of Energy/Gas Research Institute in the high Btu coal gasification research program. The gasification research program is to determine the specific process and/or combination of component processing steps that offer the greatest economic potential for commercial application. During September, Kellogg continued active monitoring of operations at Westinghouse, IGT, Peatgas, and BI-GAS. Efforts relative to Hygas, Rockwell, Exxon and Bell were minimal. Test runs monitored and reported here are BI-GAS tests 17E and 17F, Westinghouse PDU test TP-028-3, and IGT Peatgas test 3. Kellog attended meetings on 1 and 22 September to discuss the review of the Hygas final report. Comments on Kellogg's draft report on the Hygas data base evaluation were received. Kellogg's evaluations of PDU operating data from Westinghouse and Exxon continues. The Kellogg report on Peatgas PDU data base evaluation was issued in draft form. At DOE's request, Kellogg began work on an evaluation of the existing data base (by IGT) for single-stage gasification of peat. Work on the descriptive brochure continued, aimed toward issue of a draft in the near future. Kellogg also provided input regarding Westinghouse test runs to a DOE consultant.

  7. Numerical investigation and optimization of multiple fractures in tight gas reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Hou, M.Z. [Technische Univ. Clausthal, Clausthal-Zellerfeld (Germany). ITE; Energie-Forschungszentrum Niedersachsen, Goslar (Germany); Zhou, L. [Energie-Forschungszentrum Niedersachsen, Goslar (Germany)

    2013-08-01

    The main objective of the project DGMK-680 in phase 2 was to investigate the influence of fractures on each other in a multi-fracture system including their space optimization by using the numerical program FLAC3D with our own developments, which treats all fractures in one 3D geometric model under 3D stress state with fully hydro-mechanical coupling effect. The case study was conducted on a horizontal wellbore at location A, which was stimulated hydraulically with a total of eight transverse fractures in summer 2009. Transverse multiple fractures were simulated using the modified continuum method. In the simulation all fractures were generated in one single model, comprising 22 different rock layers. Each layer was assumed to be homogeneous with regard to its rock and hydromechanical parameters. Thus the influence of the individual fractures on each other can be investigated. The simulation procedure applied, which is a consecutive execution ofa hydraulic and a mechanical computation, is the same for all fractures. The only differences are the primary in-situ stresses, the initial pore pressure, the injection parameters (location, rate, volume, duration), which lead to different patterns of fracture propagations. But there are still some common points, such as irregular patterns of the fracture front, which represents the heterogeneity of the model. All fractures (1 to 8) have their fracture average half-length between 70 m to 115 m, height between 93 m to 114 m and average width between 18 mm to 31 mm. The percentage difference of fracture height for individual fractures is obviously smaller than that of the fracture half-lengths, because the fracture barriers at bottom and top limit the fracture propagation in z-direction. Incomparison with the analytical simulator (FracPro) most results match well. Simulation of multiple fractures at location A, with the newly developed algorithms, shows that individual transverse multiple fractures at distances between 100 -150 m will certain influence on each other in terms of the stress change, but not pore pressure. Generally, this influence as simulated at this location has a positive effect on the fracture geometry as well, and may lead to a bigger half-length and a smaller width of the fracture. In order to maximize the production rate in this specific site, transverse multiple fractures with an optimal fracture distance of ca. 57 m should be implemented. This optimal fracture spacing is derived from the counter of 5 direction change of the primary maximum horizontal stress, to ensure that only transverse fractures are generated in this location. However, the influence on longitudinal multiple fractures is very obvious, as observed from the numerical simulations of longitudinal multiple fractures at U2. Under the circumstances, it is recommended that the boreholes should not be drilled exactly in the direction of maximal horizontal stress ({+-}15 ), in order to avoid the overlapping of fractures. (orig.)

  8. Naturally fractured tight gas reservoir detection optimization. Quarterly report, April 1--June 30, 1995

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-07-31

    This progress report discusses in details the geologic assessment of the Piceance Creek Basin. Analysis of the high resolution aeromagnetic survey concentrated on the high-resolution aeromagnetic data acquired by World Geoscience, but the interpretation was supplemented by examination of regional published gravity and magnetic data, as well as surface geology and subsurface geology.

  9. Natural gas accumulations in low-permeability Tertiary, and Cretaceous (Campanian and Maastrichtian) rock, Uinta Basin, Utah. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Fouch, T.D.; Wandrey, C.J.; Pitman, J.K.; Nuccio, V.F.; Schmoker, J.W.; Rice, D.D.; Johnson, R.C.; Dolton, G.L.

    1992-02-01

    This report characterizes Upper Cretaceous Campanian and Maastrichtian, and lower Tertiary gas-bearing rocks in the Uinta Basin with special emphasis on those units that contain gas in reservoirs that have been described as being tight. The report was prepared for the USDOE whose Western Tight Gas Sandstone Program cofunded much of this research in conjunction with the US Geological Survey`s Evolution of Sedimentary Basins, and Onshore Oil and Gas Programs. (VC)

  10. Natural gas accumulations in low-permeability Tertiary, and Cretaceous (Campanian and Maastrichtian) rock, Uinta Basin, Utah

    Energy Technology Data Exchange (ETDEWEB)

    Fouch, T.D.; Wandrey, C.J.; Pitman, J.K.; Nuccio, V.F.; Schmoker, J.W.; Rice, D.D.; Johnson, R.C.; Dolton, G.L.

    1992-02-01

    This report characterizes Upper Cretaceous Campanian and Maastrichtian, and lower Tertiary gas-bearing rocks in the Uinta Basin with special emphasis on those units that contain gas in reservoirs that have been described as being tight. The report was prepared for the USDOE whose Western Tight Gas Sandstone Program cofunded much of this research in conjunction with the US Geological Survey's Evolution of Sedimentary Basins, and Onshore Oil and Gas Programs. (VC)

  11. Editorial: 3Rs tightly intertwined to maintain genome stability

    DEFF Research Database (Denmark)

    2017-01-01

    DNA recombination, repair and replication are three large and vibrant research fields where each ‘R’ could deserve a series of reviews in its own right. However, as the 3Rs are tightly interwoven processes, one R can often not be fully understood without including the others. For example, replica......DNA recombination, repair and replication are three large and vibrant research fields where each ‘R’ could deserve a series of reviews in its own right. However, as the 3Rs are tightly interwoven processes, one R can often not be fully understood without including the others. For example......, replication of damaged DNA results in stalled replication forks that await DNA damage repair before replication can be resumed. In turn, the repair of most lesions depends on processes involving DNA synthesis. At the same time, the stalled forks may engage in recombination, either as part of a controlled...... repair process or by accident, just because it can, with the risk of producing genome rearrangements and loss of heterozygosity. The set of reviews presented in this thematic issue (https://academic-oup-com.proxy.findit.dtu.dk/femsyr/pages/replication_recombination_and_repair) of FEMSYR has been selected...

  12. Adaptive wavelet tight frame construction for accelerating MRI reconstruction

    Directory of Open Access Journals (Sweden)

    Genjiao Zhou

    2017-09-01

    Full Text Available The sparsity regularization approach, which assumes that the image of interest is likely to have sparse representation in some transform domain, has been an active research area in image processing and medical image reconstruction. Although various sparsifying transforms have been used in medical image reconstruction such as wavelet, contourlet, and total variation (TV etc., the efficiency of these transforms typically rely on the special structure of the underlying image. A better way to address this issue is to develop an overcomplete dictionary from the input data in order to get a better sparsifying transform for the underlying image. However, the general overcomplete dictionaries do not satisfy the so-called perfect reconstruction property which ensures that the given signal can be perfectly represented by its canonical coefficients in a manner similar to orthonormal bases, resulting in time consuming in the iterative image reconstruction. This work is to develop an adaptive wavelet tight frame method for magnetic resonance image reconstruction. The proposed scheme incorporates the adaptive wavelet tight frame approach into the magnetic resonance image reconstruction by solving a l0-regularized minimization problem. Numerical results show that the proposed approach provides significant time savings as compared to the over-complete dictionary based methods with comparable performance in terms of both peak signal-to-noise ratio and subjective visual quality.

  13. A tightly coupled non-equilibrium model for inductively coupled radio-frequency plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Munafò, A., E-mail: munafo@illinois.edu; Alfuhaid, S. A., E-mail: alfuhai2@illinois.edu; Panesi, M., E-mail: mpanesi@illinois.edu [Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, Talbot Laboratory, 104 S. Wright St., Urbana, Illinois 61801 (United States); Cambier, J.-L., E-mail: jean-luc.cambier@us.af.mil [Edwards Air Force Base Research Laboratory, 10 E. Saturn Blvd., Edwards AFB, California 93524 (United States)

    2015-10-07

    The objective of the present work is the development of a tightly coupled magneto-hydrodynamic model for inductively coupled radio-frequency plasmas. Non Local Thermodynamic Equilibrium (NLTE) effects are described based on a hybrid State-to-State approach. A multi-temperature formulation is used to account for thermal non-equilibrium between translation of heavy-particles and vibration of molecules. Excited electronic states of atoms are instead treated as separate pseudo-species, allowing for non-Boltzmann distributions of their populations. Free-electrons are assumed Maxwellian at their own temperature. The governing equations for the electro-magnetic field and the gas properties (e.g., chemical composition and temperatures) are written as a coupled system of time-dependent conservation laws. Steady-state solutions are obtained by means of an implicit Finite Volume method. The results obtained in both LTE and NLTE conditions over a broad spectrum of operating conditions demonstrate the robustness of the proposed coupled numerical method. The analysis of chemical composition and temperature distributions along the torch radius shows that: (i) the use of the LTE assumption may lead to an inaccurate prediction of the thermo-chemical state of the gas, and (ii) non-equilibrium phenomena play a significant role close the walls, due to the combined effects of Ohmic heating and macroscopic gradients.

  14. MAMA: An Algebraic Map for the Secular Dynamics of Planetesimals in Tight Binary Systems

    CERN Document Server

    Leiva, A M; Beaugé, C

    2013-01-01

    We present an algebraic map (MAMA) for the dynamical and collisional evolution of a planetesimal swarm orbiting the main star of a tight binary system (TBS). The orbital evolution of each planetesimal is dictated by the secular perturbations of the secondary star and gas drag due to interactions with a protoplanetary disk. The gas disk is assumed eccentric with a constant precession rate. Gravitational interactions between the planetesimals are ignored. All bodies are assumed coplanar. A comparison with full N-body simulations shows that the map is of the order of 100 times faster, while preserving all the main characteristics of the full system. In a second part of the work, we apply MAMA to the \\gamma-Cephei, searching for friendly scenarios that may explain the formation of the giant planet detected in this system. For low-mass protoplanetary disks, we find that a low-eccentricity static disk aligned with the binary yields impact velocities between planetesimals below the disruption threshold. All other sc...

  15. Pore structure characterization of Chang-7 tight sandstone using MICP combined with N2GA techniques and its geological control factors

    Science.gov (United States)

    Cao, Zhe; Liu, Guangdi; Zhan, Hongbin; Li, Chaozheng; You, Yuan; Yang, Chengyu; Jiang, Hang

    2016-11-01

    Understanding the pore networks of unconventional tight reservoirs such as tight sandstones and shales is crucial for extracting oil/gas from such reservoirs. Mercury injection capillary pressure (MICP) and N2 gas adsorption (N2GA) are performed to evaluate pore structure of Chang-7 tight sandstone. Thin section observation, scanning electron microscope, grain size analysis, mineral composition analysis, and porosity measurement are applied to investigate geological control factors of pore structure. Grain size is positively correlated with detrital mineral content and grain size standard deviation while negatively related to clay content. Detrital mineral content and grain size are positively correlated with porosity, pore throat radius and withdrawal efficiency and negatively related to capillary pressure and pore-to-throat size ratio; while interstitial material is negatively correlated with above mentioned factors. Well sorted sediments with high debris usually possess strong compaction resistance to preserve original pores. Although many inter-crystalline pores are produced in clay minerals, this type of pores is not the most important contributor to porosity. Besides this, pore shape determined by N2GA hysteresis loop is consistent with SEM observation on clay inter-crystalline pores while BJH pore volume is positively related with clay content, suggesting N2GA is suitable for describing clay inter-crystalline pores in tight sandstones.

  16. Importância da sustentabilidade para as empresas do setor de energia elétrica: utilização de relatório de sustentabilidade com base no GRI

    Directory of Open Access Journals (Sweden)

    Leonardo Fabris Lugoboni

    2015-08-01

    Full Text Available The Sustainability Report is a tool that aims to give greater transparency to the business activities and increase dialogue with the organization of society, keeping in mind the need that businesses and organizations need to communicate the success and challenges of their social and environmental strategies and ethical coherence of its operations. The demonstration is used by companies to promote and highlight their sustainable practices. This research sought to understand how companies in the electric energy sector, listed on the BM&FBOVESPA as Novo Mercado (the higher level of Corporate Governance and Level 1 Corporate Governance disseminate to stakeholders their sustainability reports. Documentary analysis was performed through the sustainability reports of electric companies: CEEE, Cemig, CESP, Copel, CPFL, CTEEP, EDP, Eletrobrás, Equatorial Light, MPX (lacks any base of reports and Tractebel. We conducted research reports of companies mentioned 2010 , 2011 e 2012, which was seen a great evolution in the dissemination of the indicators of GRI - Global Reporting Initiative, since they are recognized internationally, which gives companies greater reliability and transparency in its information.

  17. Porównywalność w czasie informacji o wynikach działalności społecznie odpowiedzialnej firm raportujących według zasad GRI

    Directory of Open Access Journals (Sweden)

    Halina Waniak-Michalak

    2017-06-01

    Full Text Available Porównywalność w czasie informacji o wynikach działalności społecznie odpowiedzialnej firm raportujących według zasad GRI The involvement of corporations in corporate social responsibility (CSR activities with respect for work- ers' rights and ethical principles brings tangible benefits to the enterprise. CSR activities can therefore be considered as an investment, the effects of which should be measured. CSR benefits derive from im- proved assessment of the corporation by the stakeholders and increased social trust. However, in order to achieve the desired results of CSR activities, it is necessary to provide adequate information to customers, employees and owners. Moreover, the measurement of CSR results is necessary to determine the effec- tiveness of the actions taken. The aim of the article was to answer the question if companies present the same measures in successive CSR reports and whether it is possible to compare the CSR activity results for successive years. Examination of 31 CSR reports for two consecutive editions of the reporting showed that companies change the number and type of disclosed measures.

  18. MANAGING TIGHT BINDING RECEPTORS FOR NEW SPEARATIONS TECHNOLOGIES

    Energy Technology Data Exchange (ETDEWEB)

    DARYLE H BUSCH RICHARD S GIVENS

    2004-12-10

    Much of the earth's pollution involves compounds of the metallic elements, including actinides, strontium, cesium, technetium, and RCRA metals. Metal ions bind to molecules called ligands, which are the molecular tools that can manipulate the metal ions under most conditions. This DOE-EMSP sponsored program strives (1) to provide the foundations for using the most powerful ligands in transformational separations technologies and (2) to produce seminal examples of their applications to separations appropriate to the DOE EM mission. These ultra tight-binding ligands can capture metal ions in the most competitive of circumstances (from mineralized sites, lesser ligands, and even extremely dilute solutions), but they react so slowly that they are useless in traditional separations methodologies. Two attacks on this problem are underway. The first accommodates to the challenging molecular lethargy by developing a seminal slow separations methodology termed the soil poultice. The second designs ligands that are only tight-binding while wrapped around the targeted metal ion, but can be put in place by switch-binding and removed by switch-release. We envision a kind of molecular switching process to accelerate the union between metal ion and tight-binding ligand. Molecular switching processes are suggested for overcoming the slow natural equilibration rate with which ultra tight-binding ligands combine with metal ions. Ligands that bind relatively weakly combine with metal ions rapidly, so the trick is to convert a ligand from a weak, rapidly binding species to a powerful, slow releasing ligand--during the binding of the ligand to the metal ion. Such switch-binding ligands must react with themselves, and the reaction must take place under the influence of the metal ion. For example, our generation 1 ligands showed that a well-designed linear ligand with ends that readily combine, forms a cyclic molecule when it wraps around a metal ion. Our generation 2 ligands are

  19. Upper Paleozoic coal measures and unconventional natural gas systems of the Ordos Basin, China

    Directory of Open Access Journals (Sweden)

    Xuan Tang

    2012-11-01

    Full Text Available Upper Paleozoic coal measures in the Ordos Basin consist of dark mudstone and coal beds and are important source rocks for gas generation. Gas accumulations include coal-bed methane (CBM, tight gas and conventional gas in different structural areas. CBM accumulations are mainly distributed in the marginal area of the Ordos Basin, and are estimated at 3.5 × 1012 m3. Tight gas accumulations exist in the middle part of the Yishan Slope area, previously regarded as the basin-centered gas system and now considered as stratigraphic lithologic gas reservoirs. This paper reviews the characteristics of tight gas accumulations: poor physical properties (porosity < 8%, permeability < 0.85 × 10−3 μm2, abnormal pressure and the absence of well-defined gas water contacts. CBM is a self-generation and self-reservoir, while gas derived from coal measures migrates only for a short distance to accumulate in a tight reservoir and is termed near-generation and near-reservoir. Both CBM and tight gas systems require source rocks with a strong gas generation ability that extends together over wide area. However, the producing area of the two systems may be significantly different.

  20. Ischemic preconditioning enhances integrity of coronary endothelial tight junctions

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhao [Department of Pharmaceutical Sciences, College of Pharmacy, South Dakota State University, Brookings, SD 57007 (United States); Jin, Zhu-Qiu, E-mail: zhu-qiu.jin@sdstate.edu [Department of Pharmaceutical Sciences, College of Pharmacy, South Dakota State University, Brookings, SD 57007 (United States)

    2012-08-31

    Highlights: Black-Right-Pointing-Pointer Cardiac tight junctions are present between coronary endothelial cells. Black-Right-Pointing-Pointer Ischemic preconditioning preserves the structural and functional integrity of tight junctions. Black-Right-Pointing-Pointer Myocardial edema is prevented in hearts subjected to ischemic preconditioning. Black-Right-Pointing-Pointer Ischemic preconditioning enhances translocation of ZO-2 from cytosol to cytoskeleton. -- Abstract: Ischemic preconditioning (IPC) is one of the most effective procedures known to protect hearts against ischemia/reperfusion (IR) injury. Tight junction (TJ) barriers occur between coronary endothelial cells. TJs provide barrier function to maintain the homeostasis of the inner environment of tissues. However, the effect of IPC on the structure and function of cardiac TJs remains unknown. We tested the hypothesis that myocardial IR injury ruptures the structure of TJs and impairs endothelial permeability whereas IPC preserves the structural and functional integrity of TJs in the blood-heart barrier. Langendorff hearts from C57BL/6J mice were prepared and perfused with Krebs-Henseleit buffer. Cardiac function, creatine kinase release, and myocardial edema were measured. Cardiac TJ function was evaluated by measuring Evans blue-conjugated albumin (EBA) content in the extravascular compartment of hearts. Expression and translocation of zonula occludens (ZO)-2 in IR and IPC hearts were detected with Western blot. A subset of hearts was processed for the observation of ultra-structure of cardiac TJs with transmission electron microscopy. There were clear TJs between coronary endothelial cells of mouse hearts. IR caused the collapse of TJs whereas IPC sustained the structure of TJs. IR increased extravascular EBA content in the heart and myocardial edema but decreased the expression of ZO-2 in the cytoskeleton. IPC maintained the structure of TJs. Cardiac EBA content and edema were reduced in IPC hearts. IPC

  1. Revenue Risk of U.S. Tight-Oil Firms

    Directory of Open Access Journals (Sweden)

    Luis Mª Abadie

    2016-10-01

    Full Text Available American U.S. crude oil prices have dropped significantly of late down to a low of less than $30 a barrel in early 2016. At the same time price volatility has increased and crude in storage has reached record amounts in the U.S. America. Low oil prices in particular pose quite a challenge for the survival of U.S. America’s tight-oil industry. In this paper we assess the current profitability and future prospects of this industry. The question could be broadly stated as: should producers stop operation immediately or continue in the hope that prices will rise in the medium term? Our assessment is based on a stochastic volatility model with three risk factors, namely the oil spot price, the long-term oil price, and the spot price volatility; we allow for these sources of risk to be correlated and display mean reversion. We then use information from spot and futures West Texas Intermediate (WTI oil prices to estimate this model. Our aim is to show how the development of the oil price in the future may affect the prospective revenues of firms and hence their operation decisions at present. With the numerical estimates of the model’s parameters we can compute the value of an operating tight-oil field over a certain time horizon. Thus, the present value (PV of the prospective revenues up to ten years from now is $37.07/bbl in the base case. Consequently, provided that the cost of producing a barrel of oil is less than $37.07 production from an operating field would make economic sense. Obviously this is just a point estimate. We further perform a Monte Carlo (MC simulation to derive the risk profile of this activity and calculate two standard measures of risk, namely the value at risk (VaR and the expected shortfall (ES (for a given confidence level. In this sense, the PV of the prospective revenues will fall below $22.22/bbl in the worst 5% of the cases; and the average value across these worst scenarios is $19.77/bbl. Last we undertake two

  2. Tight focusing of femtosecond elliptically polarised vortex light pulses

    Institute of Scientific and Technical Information of China (English)

    Hua Li-Min; Chen Bao-Suan; Chen Zi-Yang; Pu Ji-Xiong

    2011-01-01

    This paper studies the tight focusing properties of femtosecond elliptically polarised vortex light pulses. Based on Richards-Wolf vectorial diffraction integral, the expressions for the electric field, the velocity of the femtosecond light pulse and the total angular momentum of focused pluses are derived. The numerical calculations are also given to illustrate the intensity distribution, phase contour, the group velocity variation and the total angular momentum near the focus. It finds that near the focus the femtosecond elliptically polarised vortex light pulse can travel at various group speeds, that is, slower or faster than light speed in vacuum, depending on the numerical aperture of the focusing objective system. Moreover, it also studies the influence of the numerical aperture of the focusing objective and the time duration of the elliptically polarised vortex light pulse on the total angular momentum distribution in the focused field.

  3. Endocytosis and Recycling of Tight Junction Proteins in Inflammation

    Directory of Open Access Journals (Sweden)

    Markus Utech

    2010-01-01

    Full Text Available A critical function of the epithelial lining is to form a barrier that separates luminal contents from the underlying interstitium. This barrier function is primarily regulated by the apical junctional complex (AJC consisting of tight junctions (TJs and adherens junctions (AJs and is compromised under inflammatory conditions. In intestinal epithelial cells, proinflammatory cytokines, for example, interferon-gamma (IFN-γ, induce internalization of TJ proteins by endocytosis. Endocytosed TJ proteins are passed into early and recycling endosomes, suggesting the involvement of recycling of internalized TJ proteins. This review summarizes mechanisms by which TJ proteins under inflammatory conditions are internalized in intestinal epithelial cells and point out comparable mechanism in nonintestinal epithelial cells.

  4. Some Bivariate Smooth Compactly Supported Tight Framelets with Three Generators

    Directory of Open Access Journals (Sweden)

    A. San Antolín

    2013-01-01

    Full Text Available For any dilation matrix with integer entries and , we construct a family of smooth compactly supported tight wavelet frames with three generators in . Our construction involves some compactly supported refinable functions, the oblique extension principle, and a slight generalization of a theorem of Lai and Stöckler. Estimates for the degrees of smoothness are given. With the exception of a polynomial whose coefficients must in general be computed by spectral factorization, the framelets are expressed in closed form in the frequency domain, in terms of elementary transcendental functions. By means of two examples we also show that for low degrees of smoothness the use of spectral factorization may be avoided.

  5. S0 Tight Loop Studies on ICHIRO 9-Cell Cavities

    Energy Technology Data Exchange (ETDEWEB)

    Furuta, Fumio [KEK; Konomi, T. [KEK; Saito, Kenji [KEK; Bice, Damon [Fermilab; Crawford, Anthony C. [JLAB; Geng, Rongli [JLAB

    2009-11-01

    We have continued high gradient R&D of ICHIRO 9-cell cavities at KEK. ICHIRO 9-cell cavity #5 (I9#5) that has no end groups on beam tube to focus on high gradient sent to Jlab as S0 tight loop study. Surface treatments and vertical test were repeated 3 times at Jlab, and then I9#5 sent back to KEK. We also repeated surface treatments and test at KEK. Maximum gradients were 36.5MV/m at Jlab, and 33.7MV/m at KEK so far. Now we are struggling with the puzzle why the results of singles do not work well on 9-cell cavities.

  6. Propagation equation for tight-focusing by a parabolic mirror.

    Science.gov (United States)

    Couairon, A; Kosareva, O G; Panov, N A; Shipilo, D E; Andreeva, V A; Jukna, V; Nesa, F

    2015-11-30

    Part of the chain in petawatt laser systems may involve extreme focusing conditions for which nonparaxial and vectorial effects have high impact on the propagation of radiation. We investigate the possibility of using propagation equations to simulate numerically the focal spot under these conditions. We derive a unidirectional propagation equation for the Hertz vector, describing linear and nonlinear propagation under situations where nonparaxial diffraction and vectorial effects become significant. By comparing our simulations to the results of vector diffraction integrals in the case of linear tight-focusing by a parabolic mirror, we establish a practical criterion for the critical f -number below which initializing a propagation equation with a parabolic input phase becomes inaccurate. We propose a method to find suitable input conditions for propagation equations beyond this limit. Extreme focusing conditions are shown to be modeled accurately by means of numerical simulations of the unidirectional Hertz-vector propagation equation initialized with suitable input conditions.

  7. An efficient LDA+U based tight binding approach.

    Science.gov (United States)

    Sanna, Simone; Hourahine, B; Gallauner, Th; Frauenheim, Th

    2007-07-01

    The functionals usually applied in DFT calculations have deficiencies in describing systems with strongly localized electrons such as transition metals or rare earth (RE) compounds. In this work, we present the self-consistent charge density based functional tight binding (SCC-DFTB) calculation scheme including LDA+U like potentials and apply it for the simulation of RE-doped GaN. DFTB parameters for the simulation of GaN and a selection of rare earth ions, where the f electrons were explicitly included in the valence, have been created. The results of the simulations were tested against experimental data (where present) and against various more sophisticated but computationally more costly DFT calculations. Our approach is found to correctly reproduce the geometry and the energetic of the studied systems.

  8. Experiments on Exhaust Noise of Tightly Integrated Propulsion Systems

    Science.gov (United States)

    Bridges, James E.; Brown, Clifford A.; Bozak, Richard F.

    2014-01-01

    A wide-ranging series of tests have been completed that seek to map the effects of installation, including jet by jet interaction effects, on exhaust noise from various nozzles in forward flight. The primary data was far-field acoustic spectral directivity. The goals of the test series were (i) to generate enough data for empirical models of the different effects, and (ii) to provide data for advanced computational noise predictions methods applied to simplified yet realistic configurations. Data is presented that demonstrate several checks on data quality and that provide an overview of trends observed to date. Among the findings presented here: (i) Data was repeatable between jet rigs for single nozzles with and without surfaces to within +/- 0.5 dB. (ii) The presence of a second jet caused a strong reduction of the summed noise in the plane of the two plumes and an increase over the expected source doubling in most other azimuthal planes. (iii) The impact of the second jet was reduced when the jets were unheated. (iv) The impact of adding a second isolated rectangular jet was relatively independent of the nozzle aspect ratio up to aspect ratio 8:1. (v) Forward flight had similar impact on a high aspect ratio (8:1) jet as on an axisymmetric jet, except at the peak noise angle where the impact was less. (vi) The effect of adding a second round jet to a tightly integrated nozzle where the nozzle lip was less than a diameter from the surface was very dependent upon the length of the surface downstream of the nozzle. (vii) When the nozzles were rectangular and tightly integrated with the airframe surface the impact of a second jet was very dependent upon how close together the two jets were. This paper serves as an overview of the test; other papers presented in the same conference will give more detailed analysis of the results.

  9. Experimental and simulation determination of minimum miscibility pressure for a Bakken tight oil and different injection gases

    Directory of Open Access Journals (Sweden)

    Sheng Li

    2017-03-01

    Full Text Available The effective development of unconventional tight oil formations, such as Bakken, could include CO2 enhanced oil recovery (EOR technologies with associated benefits of capturing and storing large quantities of CO2. It is important to conduct the gas injection at miscible condition so as to reach maximum recovery efficiency. Therefore, determination of the minimum miscibility pressure (MMP of reservoir live oil–injection gas system is critical in a miscible gas flooding project design. In this work, five candidate injection gases, namely CO2, CO2-enriched flue gas, natural gas, nitrogen, and CO2-enriched natural gas, were selected and their MMPs with a Bakken live oil were determined experimentally and numerically. At first, phase behaviour tests were conducted for the reconstituted Bakken live oil and the gases. CO2 outperformed other gases in terms of viscosity reduction and oil swelling. Rising bubble apparatus (RBA determined live oil–CO2 MMP as 11.9 MPa and all other gases higher than 30 MPa. The measured phase behaviour data were used to build and tune an equation-of-state (EOS model, which calculated the MMPs for different live oil-gas systems. The EOS-based calculations indicated that CO2 had the lowest MMP with live oil among the five gases in the study. At last, the commonly-accepted Alston et al. equation was used to calculate live oil–pure CO2 MMP and effect of impurities in the gas phase on MMP change. The Bakken oil–CO2 had a calculated MMP of 10.3 MPa from the Alston equation, and sensitivity analysis showed that slight addition of volatile impurities, particularly N2, can increase MMP significantly.

  10. Daya Bay Antineutrino Detector Gas System

    CERN Document Server

    Band, H R; Chu, M-C; Heeger, K M; Kwok, M W; Shih, K; Wise, T; Xiao, Q

    2012-01-01

    The Daya Bay Antineutrino Detector gas system is designed to protect the liquid scintillator targets of the antineutrino detectors against degradation and contamination from exposure to ambient laboratory air. The gas system is also used to monitor the leak tightness of the antineutrino detector assembly. The cover gas system constantly flushes the gas volumes above the liquid scintillator with dry nitrogen to minimize oxidation of the scintillator over the five year lifetime of the experiment. This constant flush also prevents the infiltration of radon or other contaminants into these detecting liquids keeping the internal backgrounds low. Since the Daya Bay antineutrino detectors are immersed in the large water pools of the muon veto system, other gas volumes are needed to protect vital detector cables or gas lines. These volumes are also purged with dry gas. Return gas is monitored for oxygen content and humidity to provide early warning of potentially damaging leaks. The design and performance of the Daya...

  11. Obstacle detection for guided directional drilling for gas distribution applications; Detection d'obstacles pour le forage directionnel guide en vue des applications de distribution de gaz

    Energy Technology Data Exchange (ETDEWEB)

    Norman, R.S. [GRI, Chicago, Illinois (United States)

    2000-07-01

    GRI began the development of guided horizontal drilling concepts for the natural gas industry in 1984. At that time, very little technology was available for small, shallow depth horizontal directional drilling. Over the years in the US, a number of horizontal, directional drilling systems has been developed by several highly qualified manufacturers. Consequently, in the late 1990's horizontal directional drilling became a very efficient and cost effective method for piping, cable, and conduit installations in the US. In the gas industry approximately 10% of the service installations are made with horizontal directional drilling equipment. With greater use of this trench-less technology came the potential problem of striking other underground objects or linear systems. In 1997, GRI began a comprehensive program to study the possibility of using sensors with these horizontal directional drilling systems to detect underground obstacles in the path of trench-less drilling tools. This paper reviews the progress to date on these basic research and development studies. (author)

  12. Preliminary results of cooperative research efforts with Phillips Petroleum Company and Amax Oil and Gas Inc. , San Juan Basin

    Energy Technology Data Exchange (ETDEWEB)

    Logan, T.L. (Resource Enterprises Inc., Salt Lake City, UT (United States))

    1994-04-01

    Gas production rates from Fruitland open-hole coalbed wells often are greater than those from offset hydraulic fracture-stimulated wells in similar geologic environments by a factor of three or more. GRI and Resource Enterprises Inc, entered into cooperative research agreements with Phillips Petroleum Company and Amax Oil and Gas Inc. to evaluate the effectiveness of recompletion techniques, compare hydraulically fractured and cavity-completed wells, and measure at various locations in the basin the critical reservoir characteristics that influence completion technique selection. The Phillips' wells that were studied are located in Rio Arriba County, New Mexico, southeast of the productive Northeast Blanco Unit. Amax's cooperative research project is situated outside the fairway along the Northwestern basin boundary in La Plata County, Colorado, where Fruitland coals are relatively shallow. 9 refs., 7 figs., 1 tab.

  13. Relatórios de sustentabilidade segundo a Global Reporting Initiative (GRI: uma análise de correspondências entre os setores econômicos brasileiros

    Directory of Open Access Journals (Sweden)

    Murilo de Alencar Souza Oliveira

    2014-06-01

    Full Text Available O presente artigo tem por objetivo principal apresentar o nível de adesão e o volume de publicações dos relatórios de sustentabilidade das empresas brasileiras conforme as diretrizes da Global Reporting Initiative (GRI entre 2000 e 2008. Para a análise, foram definidas 5 variáveis de estudo: i Setor econômico de atuação das empresas; ii Ano de adesão às diretrizes; iii Nível de aplicação das diretrizes; iv Existência de ações negociadas em segmentos da BM&FBOVESPA; e v Participação na composição do índice de sustentabilidade empresarial (ISE da BM&FBOVESPA. Quanto aos procedimentos metodológicos, foram aplicadas análises por correspondências simples e múltipla entre os setores de atuação econômica das empresas publicantes e as 5 variáveis de estudos definidas. Os resultados mostram que o universo de organizações que publicaram relatórios socioambientais até 2008 ainda é reduzido. Contudo, observa-se crescente adesão, demonstrada pelo número de publicações, sobretudo na Europa. As empresas brasileiras responderam por metade do volume de publicações em 2008 na América Latina e o setor de energia liderou esse processo no país com 35% da amostra.

  14. The effects of different quantum feedback types on the tightness of the variance-based uncertainty

    Science.gov (United States)

    Zheng, Xiao; Zhang, Guo-Feng

    2017-03-01

    The effect of the quantum feedback on the tightness of the variance-based uncertainty, the possibility of using quantum feedback to prepare the state with a better tightness, and the relationship between the tightness of the uncertainty and the mixedness of the system are studied. It is found that the tightness of Schrodinger-Robertson uncertainty (SUR) relation has a strict liner relationship with the mixedness of the system. As for the Robertson uncertainty relation (RUR), we find that the tightness can be enhanced by tuning the feedback at the beginning of the evolution. In addition, we deduce that the tightness of RUR has an inverse relationship with the mixedness and the relationship turns into a strict linear one when the system reach the steady state.

  15. Gas turbine

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ok Ryong

    2004-01-15

    This book introduces gas turbine cycle explaining general thing of gas turbine, full gas turbine cycle, Ericson cycle and Brayton cycle, practical gas turbine cycle without pressure loss, multiaxial type gas turbine cycle and special gas turbine cycle, application of basic theory on a study on suction-cooling gas turbine cycle with turbo-refrigerating machine using the bleed air, and general performance characteristics of the suction-cooling gas turbine cycle combined with absorption-type refrigerating machine.

  16. Intestinal epithelial barrier function and tight junction proteins with heat and exercise

    DEFF Research Database (Denmark)

    Dokladny, Karol; Zuhl, Micah N; Moseley, Pope L

    2016-01-01

    (passive hyperthermia) heat stress on tight junction barrier function in in vitro and in vivo (animals and humans) models. Our secondary focus is to review changes in tight junction proteins in response to exercise or hyperthermic conditions. Finally, we discuss some pharmacological or nutritional...... interventions that may affect the cellular mechanisms involved in maintaining homeostasis of the intestinal epithelial tight junction barrier during heat stress or exercise....

  17. Geology and assessment of unconventional oil and gas resources of northeastern Mexico

    Science.gov (United States)

    ,

    2015-01-01

    The U.S. Geological Survey, in cooperation with the U.S. Department of State, quantitatively assessed the potential for unconventional oil and gas resources within the onshore portions of the Tampico-Misantla Basin, Burgos Basin, and Sabinas Basin provinces of northeastern Mexico. Unconventional resources of the Veracruz Basin were not quantitatively assessed because of a current lack of required geological information. Unconventional resources include shale gas, shale oil, tight gas, tight oil, and coalbed gas. Undiscovered conventional oil and gas resources were assessed in Mexico in 2012.

  18. Symmetry-Based Tight Binding Modeling of Halide Perovskite Semiconductors.

    Science.gov (United States)

    Boyer-Richard, Soline; Katan, Claudine; Traoré, Boubacar; Scholz, Reinhard; Jancu, Jean-Marc; Even, Jacky

    2016-10-06

    On the basis of a general symmetry analysis, this paper presents an empirical tight-binding (TB) model for the reference Pm-3m perovskite cubic phase of halide perovskites of general formula ABX3. The TB electronic band diagram, with and without spin orbit coupling effect of MAPbI3 has been determined based on state of the art density functional theory results including many body corrections (DFT+GW). It affords access to various properties, including distorted structures, at a significantly reduced computational cost. This is illustrated with the calculation of the band-to-band absorption spectrum, the variation of the band gap under volumetric strain, as well as the Rashba effect for a uniaxial symmetry breaking. Compared to DFT approaches, this empirical model will help to tackle larger issues, such as the electronic band structure of large nanostructures, including many-body effects, or heterostructures relevant to perovskite device modeling suited to the description of atomic-scale features.

  19. Paroxysmal dystonic choreoathetosis: Tight linkage to chromosome 2q

    Energy Technology Data Exchange (ETDEWEB)

    Fink, J.K.; Rainier, S.; Wilkowski, J.; Jones, S.M. [Univ. of Michigan, Ann Arbor, MI (United States)] [and others

    1996-07-01

    Paroxysmal dystonic choreoathetosis (PDC) is characterized by attacks of involuntary movements that last up to several hours and occur at rest both spontaneously and following caffeine or alcohol consumption. We analyzed a Polish-American kindred with autosomal dominant PDC and identified tight linkage between the disorder and microsatellite markers on chromosome 2q (maximum two-point LOD score 4.77; recombination fraction 0). Our results clearly establish the existence of a locus for autosomal dominant PDC on distal chromosome 2q. The fact that three other paroxysmal neurological disorders (periodic ataxia with myokymia and hypo- and hyperkalemic periodic paralysis) are due to mutation in ion-channel genes raises the possibility that PDC is also due to an ion-channel gene mutation. It is noteworthy that a cluster of sodium-channel genes is located on distal chromosome 2q, near the PDC locus. Identifying the PDC locus on chromosome 2q will facilitate discovery whether PDC is genetically homogeneous and whether other paroxysmal movement disorders are also genetically linked to the PDC locus. 28 refs., 2 figs., 1 tab.

  20. Claudin-21 Has a Paracellular Channel Role at Tight Junctions

    KAUST Repository

    Tanaka, Hiroo

    2016-01-05

    Claudin protein family members, of which there are at least 27 in humans and mice, polymerize to form tight junctions (TJs) between epithelial cells, in a tissue- and developmental stage-specific manner. Claudins have a paracellular barrier function. In addition, certain claudins function as paracellular channels for small ions and/or solutes by forming selective pores at the TJs, although the specific claudins involved and their functional mechanisms are still in question. Here we show for the first time that claudin-21, which is more highly expressed in the embryonic than the postnatal stages, acts as a paracellular channel for small cations, such as Na+, similar to the typical channel-type claudins claudin-2 and -15. Claudin-21 also allows the paracellular passage of larger solutes. Our findings suggest that claudin-21-based TJs allow the passage of small and larger solutes by both paracellular channel-based and some additional mechanisms. © 2016, American Society for Microbiology. All Rights Reserved.

  1. The role of tight junctions in mammary gland function.

    Science.gov (United States)

    Stelwagen, Kerst; Singh, Kuljeet

    2014-03-01

    Tight junctions (TJ) are cellular structures that facilitate cell-cell communication and are important in maintaining the three-dimensional structure of epithelia. It is only during the last two decades that the molecular make-up of TJ is becoming unravelled, with two major transmembrane-spanning structural protein families, called occludin and claudins, being the true constituents of the TJ. These TJ proteins are linked via specific scaffolding proteins to the cell's cytoskeleton. In the mammary gland TJ between adjacent secretory epithelial cells are formed during lactogenesis and are instrumental in establishing and maintaining milk synthesis and secretion, whereas TJ integrity is compromised during mammary involution and also as result of mastitis and periods of mammary inflamation (including mastitis). They prevent the paracellular transport of ions and small molecules between the blood and milk compartments. Formation of intact TJ at the start of lactation is important for the establishment of the lactation. Conversely, loss of TJ integrity has been linked to reduced milk secretion and mammary function and increased paracellular transport of blood components into the milk and vice versa. In addition to acting as a paracellular barrier, the TJ is increasingly linked to playing an active role in intracellular signalling. This review focusses on the role of TJ in mammary function of the normal, non-malignant mammary gland, predominantly in ruminants, the major dairy producing species.

  2. Experimental verification on tightly focused radially polarized vortex beams

    Institute of Scientific and Technical Information of China (English)

    Du Fu-Rong; Zhou Zhe-Hai; Tan Qiao-Feng; Yang Chang-Xi; Zhang Xiao-Qing; Zhu Lian-Qing

    2013-01-01

    The theoretical and experimental results of tightly focused radially polarized vortex beams are demonstrated.An auto-focus technology is introduced into the measurement system in order to enhance the measurement precision,and the radially polarized vortex beams are generated by a liquid-crystal polarization converter and a vortex phase plate.The focused fields of radially polarized vortex beams with different topological charges at numerical apertures (NAs) of 0.65 and 0.85 are measured respectively,and the results indicate that the total intensity distribution at focus is dependent not only on the NA of the focusing objective lens and polarization pattem of the beam but also on the topological charge l of the beam.Some unique focusing properties of radially polarized vortex beams with fractional topological charges are presented based on numerical calculations.The experimental verification paves the way for some practical applications of radially polarized vortex beams,such as in optical trapping,near-field microscopy,and material processing.

  3. Tight-binding model for materials at mesoscale

    Energy Technology Data Exchange (ETDEWEB)

    2016-12-21

    TBM3 is an open source package for computational simulations of quantum materials at multiple scales in length and time. The project originated to investigate the multiferroic behavior in transition-metal oxide heterostructures. The framework has also been designed to study emergent phemona in other quantum materials like 2-dimensional transition-metal dichalcogenides, graphene, topological insulators, and skyrmion in materials, etc. In the long term, we will enable the package for transport and time-resolved phenomena. TBM3 is currently a C++ based numerical tool package and framework for the design and construction of any kind of lattice structures with multi-orbital and spin degrees of freedom. The fortran based portion of the package will be added in the near future. The design of TBM3 is in a highly flexible and reusable framework and the tight-binding parameters can be modeled or informed by DFT calculations. It is currently GPU enabled and feature of CPU enabled MPI will be added in the future.

  4. Self consistent tight binding model for dissociable water

    Science.gov (United States)

    Lin, You; Wynveen, Aaron; Halley, J. W.; Curtiss, L. A.; Redfern, P. C.

    2012-05-01

    We report results of development of a self consistent tight binding model for water. The model explicitly describes the electrons of the liquid self consistently, allows dissociation of the water and permits fast direct dynamics molecular dynamics calculations of the fluid properties. It is parameterized by fitting to first principles calculations on water monomers, dimers, and trimers. We report calculated radial distribution functions of the bulk liquid, a phase diagram and structure of solvated protons within the model as well as ac conductivity of a system of 96 water molecules of which one is dissociated. Structural properties and the phase diagram are in good agreement with experiment and first principles calculations. The estimated DC conductivity of a computational sample containing a dissociated water molecule was an order of magnitude larger than that reported from experiment though the calculated ratio of proton to hydroxyl contributions to the conductivity is very close to the experimental value. The conductivity results suggest a Grotthuss-like mechanism for the proton component of the conductivity.

  5. End-of-fill study on collimator tight settings

    CERN Document Server

    Assmann, R; Burkart, F; Cauchi, M; Deboy, D; Redaelli, S; Rossi, A; Schmidt, R; Valentino, G; Wollmann, D

    2012-01-01

    In 2010 and 2011 the collimation system has been operated with relaxed settings, i.e. with retractions between different collimator families larger than the nominal settings that provide optimum cleaning. This configuration ensured a sufficient cleaning performance at 3.5 TeV while allowing larger tolerances on orbit control. Tighter collimator settings were proposed to push the cleaning performance and to allow larger orbit margins between TCDQ dump protection and tertiary collimators, which opens the possibility to push further the LHC β* reach. After having verified with beam that the cleaning is improved as expected, the feasibility of tighter collimator settings must be addressed with high stored intensity. For this purpose, an end-of-fill study was proposed after a standard physics fill with 1380 bunches nominal bunches at 3.5 TeV, for a total stored energy of 95 MJ. During this test, primary and secondary collimators were moved to that tight settings after about 8 hours of stable physics conditions in...

  6. Electron tunneling in the tight-binding approximation

    Science.gov (United States)

    Mackey, Frederick Douglas

    In this thesis, we treat tunneling similar to a scattering problem in which an incident wave on a barrier is partially transmitted and partially reflected. The transmission probability will be related to the conductance using a model due to Landauer. Previously tunneling has been treated using a simple barrier model, which assumes the electron dispersion is that of free electrons. In this model it is not possible to investigate tunneling in the gap between a valence band and a conduction band. We shall remedy this limitation by using the tight-binding model to generate a barrier with a gap separating a valence band and a conduction band. To do this, we constructed a model consisting of semi-infinite chains of A atoms on either side of a semi-infinite chain of B-C molecules. The B-C chain has a gap extending between the onsite energy for the B atom and the onsite energy for the C atom. Tunneling through the gap has been calculated and plotted. We present exact closed form solutions for the following tunneling systems: (i) A-B interface, (ii) A-(B-C) interface, (iii) A-B-A tunnel barrier, (iv) A-(B-C) interface with the orbitals on B having s-symmetry and those on C having p-symmetry, (v) A-(B-C)-A tunnel barrier.

  7. Nanoscale capacitance: A quantum tight-binding model

    Science.gov (United States)

    Zhai, Feng; Wu, Jian; Li, Yang; Lu, Jun-Qiang

    2017-01-01

    Landauer-Buttiker formalism with the assumption of semi-infinite electrodes as reservoirs has been the standard approach in modeling steady electron transport through nanoscale devices. However, modeling dynamic electron transport properties, especially nanoscale capacitance, is a challenging problem because of dynamic contributions from electrodes, which is neglectable in modeling macroscopic capacitance and mesoscopic conductance. We implement a self-consistent quantum tight-binding model to calculate capacitance of a nano-gap system consisting of an electrode capacitance C‧ and an effective capacitance Cd of the middle device. From the calculations on a nano-gap made of carbon nanotube with a buckyball therein, we show that when the electrode length increases, the electrode capacitance C‧ moves up while the effective capacitance Cd converges to a value which is much smaller than the electrode capacitance C‧. Our results reveal the importance of electrodes in modeling nanoscale ac circuits, and indicate that the concepts of semi-infinite electrodes and reservoirs well-accepted in the steady electron transport theory may be not applicable in modeling dynamic transport properties.

  8. Mechanical properties of metallic nanowires using tight-binding model

    Science.gov (United States)

    Aish, Mohammed; Starostenkov, Mikhail

    2016-01-01

    The mechanical properties of Nickel nanowires have been studied at different temperatures using molecular dynamics simulations. Molecular Dynamics (MD) simulations have been carried out on pure Nickel (Ni) crystal with face-centered cubic (FCC) lattice upon application of uniaxial tension at nanolevel with a speed of 20 m/s. The deformation corresponds to the direction . To the calculated block of crystal, free boundary conditions are applied in the directions , . A many body interatomic potential for Ni within the second moment approximation of the tight binding model (the Cleri-Rosato potentials) was employed to carry out three dimensional molecular dynamics simulations. MD simulation used to investigate the effect of temperature of Ni nanowire on the nature of deformation and fracture. Temperature effect on the extension property of metal nanowire is discussed in detail. The mechanical strengths and the mechanical strain of the nanowires decrease linearly with the increasing temperature. The feature of deformation energy can be divided into four regions: quasi-elastic, plastic, flow and failure. Experiments have shown that when the temperature increases the yielding stress decreases, the first stage of deformation was narrowed, and the second stage was widened. The results showed that breaking position depended on temperature.

  9. A tight-binding study of single-atom transistors.

    Science.gov (United States)

    Ryu, Hoon; Lee, Sunhee; Fuechsle, Martin; Miwa, Jill A; Mahapatra, Suddhasatta; Hollenberg, Lloyd C L; Simmons, Michelle Y; Klimeck, Gerhard

    2015-01-21

    A detailed theoretical study of the electronic and transport properties of a single atom transistor, where a single phosphorus atom is embedded within a single crystal transistor architecture, is presented. Using a recently reported deterministic single-atom transistor as a reference, the electronic structure of the device is represented atomistically with a tight-binding model, and the channel modulation is simulated self-consistently with a Thomas-Fermi method. The multi-scale modeling approach used allows confirmation of the charging energy of the one-electron donor charge state and explains how the electrostatic environments of the device electrodes affects the donor confinement potential and hence extent in gate voltage of the two-electron charge state. Importantly, whilst devices are relatively insensitive to dopant ordering in the highly doped leads, a ∼1% variation of the charging energy is observed when a dopant is moved just one lattice spacing within the device. The multi-scale modeling method presented here lays a strong foundation for the understanding of single-atom device structures: essential for both classical and quantum information processing.

  10. A tight quantitative version of Arrow's impossibility theorem

    CERN Document Server

    Keller, Nathan

    2010-01-01

    The well-known Impossibility Theorem of Arrow asserts that any Generalized Social Welfare Function (GSWF) with at least three alternatives, which satisfies Independence of Irrelevant Alternatives (IIA) and Unanimity and is not a dictatorship, is necessarily non-transitive. In 2002, Kalai asked whether one can obtain the following quantitative version of the theorem: For any $\\epsilon>0$, there exists $\\delta=\\delta(\\epsilon)$ such that if a GSWF on three alternatives satisfies the IIA condition and its probability of non-transitive outcome is at most $\\delta$, then the GSWF is at most $\\epsilon$-far from being a dictatorship or from breaching the Unanimity condition. In 2009, Mossel proved such quantitative version, with $\\delta(\\epsilon)=\\exp(-C/\\epsilon^{21})$, and generalized it to GSWFs with $k$ alternatives, for all $k \\geq 3$. In this paper we show that the quantitative version holds with $\\delta(\\epsilon)=C \\cdot \\epsilon^3$, and that this result is tight up to logarithmic factors. Furthermore, our res...

  11. Water management technologies used by Marcellus Shale Gas Producers.

    Energy Technology Data Exchange (ETDEWEB)

    Veil, J. A.; Environmental Science Division

    2010-07-30

    Natural gas represents an important energy source for the United States. According to the U.S. Department of Energy's (DOE's) Energy Information Administration (EIA), about 22% of the country's energy needs are provided by natural gas. Historically, natural gas was produced from conventional vertical wells drilled into porous hydrocarbon-containing formations. During the past decade, operators have increasingly looked to other unconventional sources of natural gas, such as coal bed methane, tight gas sands, and gas shales.

  12. Tightness of M-estimators for multiple linear regression in time series

    DEFF Research Database (Denmark)

    Johansen, Søren; Nielsen, Bent

    We show tightness of a general M-estimator for multiple linear regression in time series. The positive criterion function for the M-estimator is assumed lower semi-continuous and sufficiently large for large argument: Particular cases are the Huber-skip and quantile regression. Tightness requires...

  13. Exploring a Transformative Orientation to Sustainability in Universities: A Question of Loose and Tight Framings

    Science.gov (United States)

    Scott, William A. H.

    2015-01-01

    This review essay examines three new books on higher education and sustainability. It explores a number of the issues raised in the books, in particular, the meaning of a transformative orientation towards sustainability. The idea of loose and tight conceptual framings of sustainability is employed. A tight framing is where an institution embodies…

  14. Tightness of the thermal envelope of office and educational buildings; Klimaskaermens taethed i kontor- og undervisningsbygninger

    Energy Technology Data Exchange (ETDEWEB)

    Bergsoee, N.C. (SBi, Aalborg (Denmark)); Radisch, N.H.; Nickel, J.; Treldal, J. (Ramboell Danmark A/S, Koebenhavn (Denmark)); Bundesen, E.W.; Nielsen, Carsten (DanEjendomme, Hellerup (Denmark))

    2011-07-01

    In 2006 tightening of the energy regulations in the Danish Building Regulations were introduced including requirements regarding the tightness of the building envelope. The requirements are, with minor changes, continued in the current Building Regulations, BR10. During the past few years experience has been gained regarding both the actual execution of air tightness measurements and solutions that will lead to more air tight building envelopes. Experiences, however, are primarily related to single family houses. The report presents results of measurements in large buildings and discusses reasons for lack of knowledge and experience on the tightness of the building envelope in large buildings. Apparently, there is a need for dissemination of knowledge on the importance of a tight building envelope both in terms of energy consumption and indoor climate and in terms of the difficulties and costs associated with repairing leaks in a completed envelope. Air tightness must be brought into focus at an early stage in the planning process, and during the construction phase air tightness measurements should be performed, e.g. on facade sections or in parts of the building. The project team has attended a number of measurements in large buildings and further gained access to results of a large number of measurements. In summary, the results show that it is possible to achieve the required tightness, and in most buildings the results are better than the requirement of a maximum of 1.5 l/s per m{sub 2}. (Author)

  15. Theoretical Analysis of the Mechanism of Fracture Network Propagation with Stimulated Reservoir Volume (SRV Fracturing in Tight Oil Reservoirs.

    Directory of Open Access Journals (Sweden)

    Yuliang Su

    Full Text Available Stimulated reservoir volume (SRV fracturing in tight oil reservoirs often induces complex fracture-network growth, which has a fundamentally different formation mechanism from traditional planar bi-winged fracturing. To reveal the mechanism of fracture network propagation, this paper employs a modified displacement discontinuity method (DDM, mechanical mechanism analysis and initiation and propagation criteria for the theoretical model of fracture network propagation and its derivation. A reasonable solution of the theoretical model for a tight oil reservoir is obtained and verified by a numerical discrete method. Through theoretical calculation and computer programming, the variation rules of formation stress fields, hydraulic fracture propagation patterns (FPP and branch fracture propagation angles and pressures are analyzed. The results show that during the process of fracture propagation, the initial orientation of the principal stress deflects, and the stress fields at the fracture tips change dramatically in the region surrounding the fracture. Whether the ideal fracture network can be produced depends on the geological conditions and on the engineering treatments. This study has both theoretical significance and practical application value by contributing to a better understanding of fracture network propagation mechanisms in unconventional oil/gas reservoirs and to the improvement of the science and design efficiency of reservoir fracturing.

  16. Theoretical Analysis of the Mechanism of Fracture Network Propagation with Stimulated Reservoir Volume (SRV) Fracturing in Tight Oil Reservoirs.

    Science.gov (United States)

    Su, Yuliang; Ren, Long; Meng, Fankun; Xu, Chen; Wang, Wendong

    2015-01-01

    Stimulated reservoir volume (SRV) fracturing in tight oil reservoirs often induces complex fracture-network growth, which has a fundamentally different formation mechanism from traditional planar bi-winged fracturing. To reveal the mechanism of fracture network propagation, this paper employs a modified displacement discontinuity method (DDM), mechanical mechanism analysis and initiation and propagation criteria for the theoretical model of fracture network propagation and its derivation. A reasonable solution of the theoretical model for a tight oil reservoir is obtained and verified by a numerical discrete method. Through theoretical calculation and computer programming, the variation rules of formation stress fields, hydraulic fracture propagation patterns (FPP) and branch fracture propagation angles and pressures are analyzed. The results show that during the process of fracture propagation, the initial orientation of the principal stress deflects, and the stress fields at the fracture tips change dramatically in the region surrounding the fracture. Whether the ideal fracture network can be produced depends on the geological conditions and on the engineering treatments. This study has both theoretical significance and practical application value by contributing to a better understanding of fracture network propagation mechanisms in unconventional oil/gas reservoirs and to the improvement of the science and design efficiency of reservoir fracturing.

  17. Across-Time Change and Variation in Cultural Tightness-Looseness.

    Science.gov (United States)

    Mandel, Anne; Realo, Anu

    2015-01-01

    Cultural tightness-looseness, a dimension which describes the strength, multitude, and clarity of social norms in a culture, has proved significant in explaining differences between cultures. Although several studies have compared different cultures on this domain, this study is the first that targets both within-country differences and across-time variation in tightness-looseness. Using data from two nationally representative samples of Estonians, we found that the general tightness level had changed over a period of 10 years but the effect size of the change was small. A significant within country variance in 2002 had disappeared by 2012. Our results suggest that tightness-looseness, similarly to cultural value orientations, is a relatively stable and robust characteristic of culture-that is, change indeed takes place, but slowly. Future studies about across-time change and within-country variance in tightness-looseness should target more culturally diverse and socially divided societies.

  18. Across-Time Change and Variation in Cultural Tightness-Looseness.

    Directory of Open Access Journals (Sweden)

    Anne Mandel

    Full Text Available Cultural tightness-looseness, a dimension which describes the strength, multitude, and clarity of social norms in a culture, has proved significant in explaining differences between cultures. Although several studies have compared different cultures on this domain, this study is the first that targets both within-country differences and across-time variation in tightness-looseness. Using data from two nationally representative samples of Estonians, we found that the general tightness level had changed over a period of 10 years but the effect size of the change was small. A significant within country variance in 2002 had disappeared by 2012. Our results suggest that tightness-looseness, similarly to cultural value orientations, is a relatively stable and robust characteristic of culture-that is, change indeed takes place, but slowly. Future studies about across-time change and within-country variance in tightness-looseness should target more culturally diverse and socially divided societies.

  19. Strategies to diagnose and control microbial souring in natural gas storage reservoirs and produced water systems

    Energy Technology Data Exchange (ETDEWEB)

    Morris, E.A.; Derr, R.M.; Pope, D.H.

    1995-12-31

    Hydrogen sulfide production (souring) in natural gas storage reservoirs and produced water systems is a safety and environmental problem that can lead to operational shutdown when local hydrogen sulfide standards are exceeded. Systems affected by microbial souring have historically been treated using biocides that target the general microbial community. However, requirements for more environmentally friendly solutions have led to treatment strategies in which sulfide production can be controlled with minimal impact to the system and environment. Some of these strategies are based on microbial and/or nutritional augmentation of the sour environment. Through research sponsored by the Gas Research Institute (GRI) in Chicago, Illinois, methods have been developed for early detection of microbial souring in natural gas storage reservoirs, and a variety of mitigation strategies have been evaluated. The effectiveness of traditional biocide treatment in gas storage reservoirs was shown to depend heavily on the methods by which the chemical is applied. An innovative strategy using nitrate was tested and proved ideal for produced water and wastewater systems. Another strategy using elemental iodine was effective for sulfide control in evaporation ponds and is currently being tested in microbially sour natural gas storage wells.

  20. Gas and Gas Pains

    Science.gov (United States)

    ... problems with gas if you: Are lactose or gluten intolerant Eat a diet rich in fruits, vegetables, whole grains and legumes Drink carbonated beverages Have a chronic intestinal condition, such as irritable bowel syndrome or inflammatory bowel disease Neither age nor sex ...

  1. Impact of Air Tightness on the Evaluation of Building Energy Performance in Lithuania

    Directory of Open Access Journals (Sweden)

    Jolanta Šadauskienė

    2014-08-01

    Full Text Available In order to fulfil the European Energy Performance of Buildings Directive (EPBD requirements for the reduction of energy consumption, European national requirements have been created for building envelope thermal properties and calculation methodology to determine if building energy efficiency is created. This is however not true in all methodologies. The necessity of building air tightness appears only for new A class buildings, and there are no requirements for air tightness for other building classes. Therefore, the aim of this work is to improve the methodology for the calculation of energy efficiency of buildings, while taking into account the air tightness of the buildings. In order to achieve this aim, the sum energy consumption of investigated buildings was calculated, energy efficiency classes were determined, air tightness of the buildings was measured, and reasons for insufficient air tightness were analyzed. Investigation results show that the average value of air tightness of A energy efficiency class buildings is 0.6 h−1. The results of other investigated buildings, corresponding to B and C energy efficiency classes, show insufficient air tightness (the average n50 value is 6 h−1; herewith, energy consumption for heating is higher than calculated, according to the energy efficiency methodology. This paper provides an energy performance evaluation scheme, under which performed evaluation of energy performance of buildings ensures high quality construction work, building durability, and the reliability of heat-loss calculations.

  2. Installation of the light tight cover for the SSD modules (the modules are behind the aluminium plate). The silicon sensors are sensitive to light tight, so ambient light will increase the noise and may even damage them.

    CERN Multimedia

    Nooren, G.

    2004-01-01

    Installation of the light tight cover for the SSD modules (the modules are behind the aluminium plate). The silicon sensors are sensitive to light tight , so ambient light will increase the noise and may even damage them.

  3. Proteomic and bioinformatic analysis of epithelial tight junction reveals an unexpected cluster of synaptic molecules

    Directory of Open Access Journals (Sweden)

    Tang Vivian W

    2006-12-01

    Full Text Available Abstract Background Zonula occludens, also known as the tight junction, is a specialized cell-cell interaction characterized by membrane "kisses" between epithelial cells. A cytoplasmic plaque of ~100 nm corresponding to a meshwork of densely packed proteins underlies the tight junction membrane domain. Due to its enormous size and difficulties in obtaining a biochemically pure fraction, the molecular composition of the tight junction remains largely unknown. Results A novel biochemical purification protocol has been developed to isolate tight junction protein complexes from cultured human epithelial cells. After identification of proteins by mass spectroscopy and fingerprint analysis, candidate proteins are scored and assessed individually. A simple algorithm has been devised to incorporate transmembrane domains and protein modification sites for scoring membrane proteins. Using this new scoring system, a total of 912 proteins have been identified. These 912 hits are analyzed using a bioinformatics approach to bin the hits in 4 categories: configuration, molecular function, cellular function, and specialized process. Prominent clusters of proteins related to the cytoskeleton, cell adhesion, and vesicular traffic have been identified. Weaker clusters of proteins associated with cell growth, cell migration, translation, and transcription are also found. However, the strongest clusters belong to synaptic proteins and signaling molecules. Localization studies of key components of synaptic transmission have confirmed the presence of both presynaptic and postsynaptic proteins at the tight junction domain. To correlate proteomics data with structure, the tight junction has been examined using electron microscopy. This has revealed many novel structures including end-on cytoskeletal attachments, vesicles fusing/budding at the tight junction membrane domain, secreted substances encased between the tight junction kisses, endocytosis of tight junction

  4. Comparison and Parametric Study of Flameless Oxidation in a Gas Turbine Using Two Kinetics Mechanisms

    Directory of Open Access Journals (Sweden)

    Mohamed Hamdi

    2008-01-01

    Full Text Available The so-called “Flameless Oxidation” is a novel combustion mode, in which combustion products are re-circulated and mixed into the fresh incoming fuel and air streams. This reduces the concentration of the reactants and thereby reducing the reaction rate through avoiding the formation of sharp high temperature zones in the combustion chamber. Flameless combustion has been acknowledged as one of the most interesting combustion technologies to meet both the targets of high energy efficiency and low pollutant emissions. This technology has already been successfully applied and exploited in industrial burners. The present investigation is concerned with the application of the flameless combustion mode to an adiabatic combustor, typically used in gas turbine engines. Detailed chemical kinetics calculations, by means of a specific zero-dimensional loop reactor model, have been performed to analyze its chemical aspects. The model simulates the combustor by a number of reactors that represent different zones in the combustion chamber. The main objective of this study is to increase the understanding of NOx formation from flameless mode, where currently very few experimental data are available. The investigation is focused on a comparison of the influence of pressure, residence time and temperature on the NOx and CO emissions, using two reaction mechanisms of the C/H/O/N system: the Miller-Bowman mechanism and the GRI_MECH3.0 mechanism. Simulation results clearly illustrate that even at high operating temperatures and pressures, NOx emissions could be reduced by flameless combustion to very low levels. A comparison between the predictions obtained by using the two chemical kinetics mechanisms is presented and discussed. It is shown that the predictions of the Miller-Bowman mechanism deviate from the predictions of the GRI3.0 mechanism in many aspects, especially as related to NOx emission results.

  5. Gas centrifuge purge method

    Science.gov (United States)

    Theurich, Gordon R.

    1976-01-01

    1. In a method of separating isotopes in a high speed gas centrifuge wherein a vertically oriented cylindrical rotor bowl is adapted to rotate about its axis within an evacuated chamber, and wherein an annular molecular pump having an intake end and a discharge end encircles the uppermost portion of said rotor bowl, said molecular pump being attached along its periphery in a leak-tight manner to said evacuated chamber, and wherein end cap closure means are affixed to the upper end of said rotor bowl, and a process gas withdrawal and insertion system enters said bowl through said end cap closure means, said evacuated chamber, molecular pump and end cap defining an upper zone at the discharge end of said molecular pump, said evacuated chamber, molecular pump and rotor bowl defining a lower annular zone at the intake end of said molecular pump, a method for removing gases from said upper and lower zones during centrifuge operation with a minimum loss of process gas from said rotor bowl, comprising, in combination: continuously measuring the pressure in said upper zone, pumping gas from said lower zone from the time the pressure in said upper zone equals a first preselected value until the pressure in said upper zone is equal to a second preselected value, said first preselected value being greater than said second preselected value, and continuously pumping gas from said upper zone from the time the pressure in said upper zone equals a third preselected value until the pressure in said upper zone is equal to a fourth preselected value, said third preselected value being greater than said first, second and fourth preselected values.

  6. Gas Sensor

    KAUST Repository

    Luebke, Ryan

    2015-01-22

    A gas sensor using a metal organic framework material can be fully integrated with related circuitry on a single substrate. In an on-chip application, the gas sensor can result in an area-efficient fully integrated gas sensor solution. In one aspect, a gas sensor can include a first gas sensing region including a first pair of electrodes, and a first gas sensitive material proximate to the first pair of electrodes, wherein the first gas sensitive material includes a first metal organic framework material.

  7. Empirical tight-binding modeling of ordered and disordered semiconductor structures; Empirische Tight-Binding-Modellierung geordneter und ungeordneter Halbleiterstrukturen

    Energy Technology Data Exchange (ETDEWEB)

    Mourad, Daniel

    2010-11-30

    In this thesis, we investigate the electronic and optical properties of pure as well as of substitutionally alloyed II-VI and III-V bulk semiconductors and corresponding semiconductor quantum dots by means of an empirical tight-binding (TB) model. In the case of the alloyed systems of the type A{sub x}B{sub 1-x}, where A and B are the pure compound semiconductor materials, we study the influence of the disorder by means of several extensions of the TB model with different levels of sophistication. Our methods range from rather simple mean-field approaches (virtual crystal approximation, VCA) over a dynamical mean-field approach (coherent potential approximation, CPA) up to calculations where substitutional disorder is incorporated on a finite ensemble of microscopically distinct configurations. In the first part of this thesis, we cover the necessary fundamentals in order to properly introduce the TB model of our choice, the effective bond-orbital model (EBOM). In this model, one s- and three p-orbitals per spin direction are localized on the sites of the underlying Bravais lattice. The matrix elements between these orbitals are treated as free parameters in order to reproduce the properties of one conduction and three valence bands per spin direction and can then be used in supercell calculations in order to model mixed bulk materials or pure as well as mixed quantum dots. Part II of this thesis deals with unalloyed systems. Here, we use the EBOM in combination with configuration interaction calculations for the investigation of the electronic and optical properties of truncated pyramidal GaN quantum dots embedded in AlN with an underlying zincblende structure. Furthermore, we develop a parametrization of the EBOM for materials with a wurtzite structure, which allows for a fit of one conduction and three valence bands per spin direction throughout the whole Brillouin zone of the hexagonal system. In Part III, we focus on the influence of alloying on the electronic

  8. ACUTE EFFECTS OF DRY NEEDLING ON POSTERIOR SHOULDER TIGHTNESS. A CASE REPORT

    National Research Council Canada - National Science Library

    Passigli, Samuele; Plebani, Giuseppe; Poser, Antonio

    2016-01-01

    .... Methods to increase posterior shoulder mobility may be beneficial. The purpose of this case report is to report the outcomes of a subject with posterior shoulder tightness treated with dry needling as a primary intervention strategy...

  9. Paracellin-1, a renal tight junction protein required for paracellular Mg2+ resorption

    NARCIS (Netherlands)

    Simon, DB; Lu, Y; Choate, KA; Velazquez, H; Al-Sabban, E; Praga, M; Casari, C; Bettinelli, A; Colussi, C; Rodriguez-Soriano, J; McCredie, D; Milford, D; Sanjad, S; Lifton, RP

    1999-01-01

    Epithelia permit selective and regulated flux from apical to basolateral surfaces by transcellular passage through cells or paracellular flux between cells. Tight junctions constitute the barrier to paracellular conductance; however, Little is known about the specific molecules that mediate paracell

  10. Bending the Rules of Transcriptional Repression: Tightly Looped DNA Directly Represses T7 RNA Polymerase

    OpenAIRE

    Lionberger, Troy A.; Meyhöfer, Edgar

    2010-01-01

    From supercoiled DNA to the tight loops of DNA formed by some gene repressors, DNA in cells is often highly bent. Despite evidence that transcription by RNA polymerase (RNAP) is affected in systems where DNA is deformed significantly, the mechanistic details underlying the relationship between polymerase function and mechanically stressed DNA remain unclear. Seeking to gain additional insight into the regulatory consequences of highly bent DNA, we hypothesize that tightly looping DNA is alone...

  11. A Tight Lower Bound to the Outage Probability of Discrete-Input Block-Fading Channels

    CERN Document Server

    Nguyen, Khoa D; Rasmussen, Lars K

    2007-01-01

    In this correspondence, we propose a tight lower bound to the outage probability of discrete-input Nakagami-m block-fading channels. The approach permits an efficient method for numerical evaluation of the bound, providing an additional tool for system design. The optimal rate-diversity trade-off for the Nakagami-m block-fading channel is also derived and a tight upper bound is obtained for the optimal coding gain constant.

  12. Discrete Sliding Mode control of small UAS in tight formation flight under information constraints

    OpenAIRE

    Bolting , Jan; Fergani, Soheib; Biannic, Jean-Marc; Defay, François; Stolle, Martin

    2016-01-01

    This paper is concerned with a new control strategy based on discrete sliding mode control of small Unmanned Aerial Systems (UAS) in tight formation flight under information constraints. Tight formation flight enables, among other advantages, significant performance benefits due to wake vortex interactions. A discrete robust control strategy based on the sliding mode approach and a leader-follower scheme is proposed to achieve the desired flight performances while assuming realistic informati...

  13. Tight junction disruption: Helicobacter pylori and dysregulation of the gastric mucosal barrier.

    Science.gov (United States)

    Caron, Tyler J; Scott, Kathleen E; Fox, James G; Hagen, Susan J

    2015-10-28

    Long-term chronic infection with Helicobacter pylori (H. pylori) is a risk factor for gastric cancer development. In the multi-step process that leads to gastric cancer, tight junction dysfunction is thought to occur and serve as a risk factor by permitting the permeation of luminal contents across an otherwise tight mucosa. Mechanisms that regulate tight junction function and structure in the normal stomach, or dysfunction in the infected stomach, however, are largely unknown. Although conventional tight junction components are expressed in gastric epithelial cells, claudins regulate paracellular permeability and are likely the target of inflammation or H. pylori itself. There are 27 different claudin molecules, each with unique properties that render the mucosa an intact barrier that is permselective in a way that is consistent with cell physiology. Understanding the architecture of tight junctions in the normal stomach and then changes that occur during infection is important but challenging, because most of the reports that catalog claudin expression in gastric cancer pathogenesis are contradictory. Furthermore, the role of H. pylori virulence factors, such as cytotoxin-associated gene A and vacoulating cytotoxin, in regulating tight junction dysfunction during infection is inconsistent in different gastric cell lines and in vivo, likely because non-gastric epithelial cell cultures were initially used to unravel the details of their effects on the stomach. Hampering further study, as well, is the relative lack of cultured cell models that have tight junction claudins that are consistent with native tissues. This summary will review the current state of knowledge about gastric tight junctions, normally and in H. pylori infection, and make predictions about the consequences of claudin reorganization during H. pylori infection.

  14. Measurement and Visualization of Tight Rock Exposed to CO2 Using NMR Relaxometry and MRI

    Science.gov (United States)

    Wang, Haitao; Lun, Zengmin; Lv, Chengyuan; Lang, Dongjiang; Ji, Bingyu; Luo, Ming; Pan, Weiyi; Wang, Rui; Gong, Kai

    2017-03-01

    Understanding mechanisms of oil mobilization of tight matrix during CO2 injection is crucial for CO2 enhanced oil recovery (EOR) and sequestration engineering design. In this study exposure behavior between CO2 and tight rock of the Ordos Basin has been studied experimentally by using nuclear magnetic resonance transverse relaxation time (NMR T2) spectrum and magnetic resonance imaging (MRI) under the reservoir pressure and temperature. Quantitative analysis of recovery at the pore scale and visualization of oil mobilization are achieved. Effects of CO2 injection, exposure times and pressure on recovery performance have been investigated. The experimental results indicate that oil in all pores can be gradually mobilized to the surface of rock by CO2 injection. Oil mobilization in tight rock is time-consuming while oil on the surface of tight rock can be mobilized easily. CO2 injection can effectively mobilize oil in all pores of tight rock, especially big size pores. This understanding of process of matrix exposed to CO2 could support the CO2 EOR in tight reservoirs.

  15. Posterior shoulder tightness and rotator cuff strength assessments in painful shoulders of amateur tennis players

    Directory of Open Access Journals (Sweden)

    Freddy B. Marcondes

    2013-04-01

    Full Text Available BACKGROUND: Previous studies have shown a relationship between shoulder posterior capsule tightness and shoulder pain in overhead athletes. However, this relationship has not been studied in tennis players. OBJECTIVES: Assessment of the shoulder range of motion (ROM, strength and posterior capsule tightness of skilled amateur tennis players who had complaints of dominant shoulder pain in comparison with tennis players without pain. METHOD: Forty-nine skilled amateur tennis players were distributed in 2 groups: Control Group (n=22 and Painful Group (n=27. The first group was composed of asymptomatic subjects, and the second was composed of subjects with shoulder pain on the dominant side. These groups were evaluated to determine the dominant and non-dominant shoulder ROM (internal and external rotation, isometric shoulder strength (internal and external rotation and posterior shoulder tightness by blind evaluators. RESULTS: The ANOVA results indicated significant differences between the groups in the dominant shoulder ROM, posterior capsule tightness, external rotation strength and strength ratio (p<0.05. The intragroup analysis (dominant versus non-dominant in the Painful Group displayed a significant difference for ROM, posterior capsule tightness and external rotation strength (p<0.05. CONCLUSIONS: The tennis players with pain in the dominant shoulder presented greater posterior capsule tightness, internal rotation deficit (ROM, external rotation gain (ROM and deficits in external rotation strength than the tennis players without pain.

  16. Performance Improvement of Receivers Based on Ultra-Tight Integration in GNSS-Challenged Environments

    Directory of Open Access Journals (Sweden)

    Feng Qin

    2013-12-01

    Full Text Available Ultra-tight integration was first proposed by Abbott in 2003 with the purpose of integrating a global navigation satellite system (GNSS and an inertial navigation system (INS. This technology can improve the tracking performances of a receiver by reconfiguring the tracking loops in GNSS-challenged environments. In this paper, the models of all error sources known to date in the phase lock loops (PLLs of a standard receiver and an ultra-tightly integrated GNSS/INS receiver are built, respectively. Based on these models, the tracking performances of the two receivers are compared to verify the improvement due to the ultra-tight integration. Meanwhile, the PLL error distributions of the two receivers are also depicted to analyze the error changes of the tracking loops. These results show that the tracking error is significantly reduced in the ultra-tightly integrated GNSS/INS receiver since the receiver’s dynamics are estimated and compensated by an INS. Moreover, the mathematical relationship between the tracking performances of the ultra-tightly integrated GNSS/INS receiver and the quality of the selected inertial measurement unit (IMU is derived from the error models and proved by the error comparisons of four ultra-tightly integrated GNSS/INS receivers aided by different grade IMUs.

  17. Injuries and disorders among young ice skaters: relationship with generalized joint laxity and tightness

    Directory of Open Access Journals (Sweden)

    Okamura S

    2014-08-01

    Full Text Available Shinobu Okamura,1 Naoki Wada,1 Masayuki Tazawa,1 Makoto Sohmiya,1 Yoko Ibe,1 Toru Shimizu,1 Shigeru Usuda,2 Kenji Shirakura1 1Department of Rehabilitation Medicine, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan; 2Department of Physical Therapy, Gunma University School of Health Science, Maebashi, Gunma, Japan Abstract: This study retrospectively investigated 192 teenage speed and figure skaters with prior injuries documented by an athletes’ questionnaire, who underwent a physical examination to assess their muscle tightness and generalized joint laxity. In all athletes, the degree of muscle tightness and joint laxity were measured by a standardized physical examination. A descriptive report of the types of injuries showed a predominance of fractures, ligament injuries, enthesitis, and lower back pain. Approximately 5% of all skaters tested positive for tightness, while 25.8% of figure skaters and 15.2% of speed skaters had generalized ligamentous laxity. Statistical testing showed an association between ankle sprains and muscle tightness, and an association between knee enthesitis and muscle tightness in skating athletes. There was also an association between lower back pain and generalized joint laxity, which held true only for the male skaters. Keywords: sports injury, skating, junior athlete, tightness, joint laxity, medical checkup

  18. An exploration of relationship between TCM syndrome and biomarkers for acute ischemical stroke based on GRI and C&RT algorifhm%缺血性中风急性期证候特征与生物学指标的关系

    Institute of Scientific and Technical Information of China (English)

    刘璐; 高颖; 马斌

    2011-01-01

    Objective: To explore relationship between TCM syndrome and biomarkers for acute ischemical stroke.Methods: Serum samples from 175 patients after the onset of 72 hours, 7days and 14 days were tested by ELISA in order to detect the expression of HSP70, ICAM-1 and MMP9. Dynamic clinical data were collected aiming to determine TCM Syndrome Factors.Decision Tree Learners (C&RT) and a method for mining association rules (GRI algorithm) were used. Results: GRI algorithm:A list of association rules between Blood stasis syndrome and biomarkers after the onset of 72 hours, 7days andl4 days was obtained. C&RT algorithm: HSP70 was main factor that affected qi deficiency syndrome. Conclusion: These results indicated that HSP70, ICAM-1, MMP9 might be microscopic indices of Blood stasis syndrome and HSP70 might be microscopic index of qi deficiency syndrome for acute ischemic stroke%目的:探讨缺血性中风急性期证候与相关生物学指标的关系,从微观辨证的角度阐明证候与疾病的关系.方法:用ELISA法测定175例急性期缺血性中风病患者起病后72h内、第7、14d热休克蛋白70(HSP70)、细胞间黏附分子1(ICAM-1)及金属基质蛋白酶9(MMP9)表达水平的变化,并动态采集四诊信息判断其证候要素.应用广义规则归纳(GRI)和分类回归树(C&RT)对其数据进行挖掘分析.结果:应用GRI发现血瘀证在3个时间点均与缺血性中风急性期相关生物学指标存在密切关联.应用C&RT发现HSP70表达水平是影响气虚证最重要的因素.结论:研究提示HSP70、ICAM-1、MMP9可能是缺血性中风急性期血瘀证的微观指标,提示HSP70可能为气虚证的微观指标.

  19. Sparsity-aware tight frame learning with adaptive subspace recognition for multiple fault diagnosis

    Science.gov (United States)

    Zhang, Han; Chen, Xuefeng; Du, Zhaohui; Yang, Boyuan

    2017-09-01

    It is a challenging problem to design excellent dictionaries to sparsely represent diverse fault information and simultaneously discriminate different fault sources. Therefore, this paper describes and analyzes a novel multiple feature recognition framework which incorporates the tight frame learning technique with an adaptive subspace recognition strategy. The proposed framework consists of four stages. Firstly, by introducing the tight frame constraint into the popular dictionary learning model, the proposed tight frame learning model could be formulated as a nonconvex optimization problem which can be solved by alternatively implementing hard thresholding operation and singular value decomposition. Secondly, the noises are effectively eliminated through transform sparse coding techniques. Thirdly, the denoised signal is decoupled into discriminative feature subspaces by each tight frame filter. Finally, in guidance of elaborately designed fault related sensitive indexes, latent fault feature subspaces can be adaptively recognized and multiple faults are diagnosed simultaneously. Extensive numerical experiments are sequently implemented to investigate the sparsifying capability of the learned tight frame as well as its comprehensive denoising performance. Most importantly, the feasibility and superiority of the proposed framework is verified through performing multiple fault diagnosis of motor bearings. Compared with the state-of-the-art fault detection techniques, some important advantages have been observed: firstly, the proposed framework incorporates the physical prior with the data-driven strategy and naturally multiple fault feature with similar oscillation morphology can be adaptively decoupled. Secondly, the tight frame dictionary directly learned from the noisy observation can significantly promote the sparsity of fault features compared to analytical tight frames. Thirdly, a satisfactory complete signal space description property is guaranteed and thus

  20. Effects and predictors of shoulder muscle massage for patients with posterior shoulder tightness

    Directory of Open Access Journals (Sweden)

    Yang Jing-lan

    2012-03-01

    Full Text Available Abstract Background Clinical approaches like mobilization, stretching, and/or massage may decrease shoulder tightness and improve symptoms in subjects with stiff shoulders. We investigated the effect and predictors of effectiveness of massage in the treatment of patients with posterior shoulder tightness. Methods A randomized controlled trial was conducted in a hospital-based outpatient practice (orthopedic and rehabilitation. Forty-three women and 17 men (mean age = 54 years, range 43-73 years with posterior shoulder tightness participated and were randomized into massage and control groups (n = 30 per group. A physical therapist provided the massage on the posterior deltoid, infraspinatus, and teres minor of the involved shoulder for 18 minutes [about 6 minutes for each muscle] two times a week for 4 weeks. For the control group, one therapist applied light hand touch on the muscles 10 minutes two times a week for 4 weeks. Glenohumeral internal rotation ROM, functional status, and muscle tightness were the main outcomes. Additionally, the potential factors on the effectiveness of massage were analyzed by multivariate logistic regression. For this analysis, patients with functional score improvement at least 20% after massage were considered responsive, and the others were considered nonresponsive. Results Fifty-two patients completed the study (29 for the massage and 23 for the control. The overall mean internal rotation ROM increased significantly in the massage group compared to the control (54.9° v.s. 34.9°; P ≤ 0.001. There were 21 patients in the responsive group and 8 in the nonresponsive group. Among the factors, duration of symptoms, functional score, and posterior deltoid tightness were significant predictors of effectiveness of massage. Conclusions Massage was an effective treatment for patients with posterior shoulder tightness, but was less effective in patients with longer duration of symptoms, higher functional limitation

  1. Unconventional Gas, Status and Perspectives for Its Exploration in Cuba

    Directory of Open Access Journals (Sweden)

    Orelvis Delgado López

    2013-06-01

    Full Text Available The purposes of this paper, is to define the unconventional gas types that can be found in Cuba andelaborate premises of perspectives areas for its exploration in Cuba. For this reason, a bibliographicrevision was done over the internet, because of the absent of textbooks and experiences of this topicin Cuba. For the enunciation of perspectives areas for unconventional gas exploration in Cuba, bothgas exploration reports in national territory and theoretical aspects elucidated over the internet wereused. Through this method of research it was possible to understand the theoretical aspect ofunconventional gas, the definition of the unconventional gas types that can be present in Cuba andthe most perspectives areas in order to begin its exploration. From these results it is possible toconclude that: The term unconventional gas is used because of the unconventional technical used formake the production of natural gas profitable from low quality reservoirs, and not because it is ahydrocarbon with different characteristics. The main unconventional gas types, which are beingdeveloped nowadays worldwide, are: Tight gas, shale gas y coal bed methane. Preliminarily, in Cubaonly exist conditions for tight and shale gas development.

  2. Assessment of undiscovered continuous gas resources of the Ordos Basin Province, China, 2015

    Science.gov (United States)

    Charpentier, Ronald R.; Klett, Timothy R.; Schenk, Christopher J.; Brownfield, Michael E.; Gaswirth, Stephanie B.; Le, Phuong A.; Leathers-Miller, Heidi M.; Marra, Kristen R.; Mercier, Tracey J.

    2016-01-11

    Using a geology-based assessment methodology, the U.S. Geological Survey estimated mean resources of 28 trillion cubic feet of tight gas and 5.6 trillion cubic feet of coalbed gas in upper Paleozoic rocks in the Ordos Basin Province, China.

  3. Brittleness index and seismic rock physics model for anisotropic tight-oil sandstone reservoirs

    Institute of Scientific and Technical Information of China (English)

    Huang Xin-Rui; Huang Jian-Ping; Li Zhen-Chun; Yang Qin-Yong; Sun Qi-Xing; Cui Wei

    2015-01-01

    Brittleness analysis becomes important when looking for sweet spots in tight-oil sandstone reservoirs. Hence, appropriate indices are required as accurate brittleness evaluation criteria. We construct a seismic rock physics model for tight-oil sandstone reservoirs with vertical fractures. Because of the complexities in lithology and pore structure and the anisotropic characteristics of tight-oil sandstone reservoirs, the proposed model is based on the solid components, pore connectivity, pore type, and fractures to better describe the sandstone reservoir microstructure. Using the model, we analyze the brittleness sensitivity of the elastic parameters in an anisotropic medium and establish a new brittleness index. We show the applicability of the proposed brittleness index for tight-oil sandstone reservoirs by considering the brittleness sensitivity, the rock physics response characteristics, and cross-plots. Compared with conventional brittleness indexes, the new brittleness index has high brittleness sensitivity and it is the highest in oil-bearing brittle zones with relatively high porosity. The results also suggest that the new brittleness index is much more sensitive to elastic properties variations, and thus can presumably better predict the brittleness characteristics of sweet spots in tight-oil sandstone reservoirs.

  4. A 'select and swap' strategy for the isolation of clones with tightly regulated transgenes.

    Science.gov (United States)

    Sullivan, M J; Carpenter, A J; Porter, A C

    2001-03-01

    Increasing numbers of biological problems are being addressed by genetic approaches that rely on inducible expression of transgenes. It is desirable that expression of such a transgene is tightly regulated, from close to zero expression in the 'off' state, to appreciable (at least physiological) expression in the 'on' state. Although there are many examples where tight regulation has been achieved, certain factors, including chromosomal position effects due to random integration of the transgene, often cause suboptimal inducibility and make the isolation of tightly regulated clones difficult and/or laborious. Here we describe a 'select and swap' strategy for the isolation, from a population of stable transfectants, of clones with tightly regulated transgenes. In this approach, a positively and negatively selectable, inducible marker gene is used to select for clones with optimal transgene regulation. After isolation of such clones, the marker gene is swapped with a linked gene of interest by the use of site-specific recombination. To test this strategy we introduced into human cells a plasmid with a tetracycline-inducible bacterial gpt gene linked to a promoterless luciferase gene, isolated clones with tight gpt expression and used the Cre/loxP site-specific recombination system to swap the gpt gene with the luciferase gene. We discuss ways for refining and developing the system and widening its applicability.

  5. Tight junction-associated MARVEL proteins marveld3, tricellulin, and occludin have distinct but overlapping functions.

    Science.gov (United States)

    Raleigh, David R; Marchiando, Amanda M; Zhang, Yong; Shen, Le; Sasaki, Hiroyuki; Wang, Yingmin; Long, Manyuan; Turner, Jerrold R

    2010-04-01

    In vitro studies have demonstrated that occludin and tricellulin are important for tight junction barrier function, but in vivo data suggest that loss of these proteins can be overcome. The presence of a heretofore unknown, yet related, protein could explain these observations. Here, we report marvelD3, a novel tight junction protein that, like occludin and tricellulin, contains a conserved four-transmembrane MARVEL (MAL and related proteins for vesicle trafficking and membrane link) domain. Phylogenetic tree reconstruction; analysis of RNA and protein tissue distribution; immunofluorescent and electron microscopic examination of subcellular localization; characterization of intracellular trafficking, protein interactions, dynamic behavior, and siRNA knockdown effects; and description of remodeling after in vivo immune activation show that marvelD3, occludin, and tricellulin have distinct but overlapping functions at the tight junction. Although marvelD3 is able to partially compensate for occludin or tricellulin loss, it cannot fully restore function. We conclude that marvelD3, occludin, and tricellulin define the tight junction-associated MARVEL protein family. The data further suggest that these proteins are best considered as a group with both redundant and unique contributions to epithelial function and tight junction regulation.

  6. H gas turbine combined cycle

    Energy Technology Data Exchange (ETDEWEB)

    Corman, J. [General Electric Co., Schenectady, NY (United States)

    1995-10-01

    A major step has been taken in the development of the Next Power Generation System - {open_quotes}H{close_quotes} Technology Combined Cycle. This new gas turbine combined-cycle system increases thermal performance to the 60% level by increasing gas turbine operating temperature to 1430 C (2600 F) at a pressure ratio of 23 to 1. Although this represents a significant increase in operating temperature for the gas turbine, the potential for single digit NOx levels (based upon 15% O{sub 2}, in the exhaust) has been retained. The combined effect of performance increase and environmental control is achieved by an innovative closed loop steam cooling system which tightly integrates the gas turbine and steam turbine cycles. The {open_quotes}H{close_quotes} Gas Turbine Combined Cycle System meets the goals and objectives of the DOE Advanced Turbine System Program. The development and demonstration of this new system is being carried out as part of the Industrial/Government cooperative agreement under the ATS Program. This program will achieve first commercial operation of this new system before the end of the century.

  7. 49 CFR 192.927 - What are the requirements for using Internal Corrosion Direct Assessment (ICDA)?

    Science.gov (United States)

    2010-10-01

    ... must use the model in GRI 02-0057, “Internal Corrosion Direct Assessment of Gas Transmission Pipelines... demonstrates it is equivalent to the one shown in GRI 02-0057. A model must consider changes in pipe diameter...

  8. ISO/TR 22302《天然气-甲烷值计算》的解读%A brief understanding on the ISO/TR 22302 Natural Gas-calculation of Methane Number

    Institute of Scientific and Technical Information of China (English)

    唐蒙; 蔡黎

    2015-01-01

    This article introduced the main contents of ISO/TR 22302 :2014 ,including the defini‐tion of methane number ,two calculation methods of methane number developed by Gas Research In‐stitute (GRI) ,listed the limitation of two methods and calculated the methane numbers of 36 gas mixtures from European and 30 gas mixtures from China and Thailand .It discussed that if the differ‐ence between two GRI methods is more than 6 ,the composition of natural gas should not be in ac‐cordance with the limitation of the calculation method .ISO/TR 22302 :2014 gives the technical sup‐ports for application of methane number .%介绍了IS O/T R 22302:2014的主要内容,包括甲烷值的定义,美国气体研究院的两种甲烷值计算方法,给出了方法的限定范围,给出了36个欧洲、30个中国和泰国的天然气组成计算的甲烷值。讨论了同一天然气组成采用美国气体研究院两种方法计算甲烷值时,如果甲烷值之间的差值超过6个点,那么应该是该天然气的组成不符合计算方法的限定范围。IS O/T R 22302:2014为甲烷值的应用提供了有利的技术支持。

  9. ARTHROSCOPIC TREATMENT OF ACROMIOCLAVICULAR JOINT DISLOCATION BY TIGHT ROPE TECHNIQUE (ARTHREX®)

    Science.gov (United States)

    GÓmez Vieira, Luis Alfredo; Visco, Adalberto; Daneu Fernandes, Luis Filipe; GÓmez Cordero, Nicolas Gerardo

    2015-01-01

    Presenting the arthroscopic treatment by Tight Rope - Arthrex® system for acute acromioclavicular dislocation and to evaluate results obtained with this procedure. Methods: Between August 2006 and May 2007, 10 shoulders of 10 patients with acute acromioclavicular dislocation were submitted to arthroscopic repair using the Tight Rope - Arthrex® system. Minimum follow-up was 12 months, with a mean of 15 months. Age ranged from 26 to 42, mean 34 years. All patients were male. Radiology evaluation was made by trauma series x-ray. The patients were assisted in the first month weekly and after three months after the procedure. Clinical evaluation was based on the University of California at Los Angeles (UCLA) criteria. Results: All patients were satisfied after the arthroscopic procedure and the mean UCLA score was 32,5. Conclusion: The arthroscopic treatment by Tight Rope – Arthrex® system for acute acromioclavicular dislocation showed to be an efficient technique. PMID:26998453

  10. Loose and Tight GNSS/INS Integrations: Comparison of Performance Assessed in Real Urban Scenarios.

    Science.gov (United States)

    Falco, Gianluca; Pini, Marco; Marucco, Gianluca

    2017-01-29

    Global Navigation Satellite Systems (GNSSs) remain the principal mean of positioning in many applications and systems, but in several types of environment, the performance of standalone receivers is degraded. Although many works show the benefits of the integration between GNSS and Inertial Navigation Systems (INSs), tightly-coupled architectures are mainly implemented in professional devices and are based on high-grade Inertial Measurement Units (IMUs). This paper investigates the performance improvements enabled by the tight integration, using low-cost sensors and a mass-market GNSS receiver. Performance is assessed through a series of tests carried out in real urban scenarios and is compared against commercial modules, operating in standalone mode or featuring loosely-coupled integrations. The paper describes the developed tight-integration algorithms with a terse mathematical model and assesses their efficacy from a practical perspective.

  11. Microwave emulations and tight-binding calculations of transport in polyacetylene

    Science.gov (United States)

    Stegmann, Thomas; Franco-Villafañe, John A.; Ortiz, Yenni P.; Kuhl, Ulrich; Mortessagne, Fabrice; Seligman, Thomas H.

    2017-01-01

    A novel approach to investigate the electron transport of cis- and trans-polyacetylene chains in the single-electron approximation is presented by using microwave emulation measurements and tight-binding calculations. In the emulation we take into account the different electronic couplings due to the double bonds leading to coupled dimer chains. The relative coupling constants are adjusted by DFT calculations. For sufficiently long chains a transport band gap is observed if the double bonds are present, whereas for identical couplings no band gap opens. The band gap can be observed also in relatively short chains, if additional edge atoms are absent, which cause strong resonance peaks within the band gap. The experimental results are in agreement with our tight-binding calculations using the nonequilibrium Green's function method. The tight-binding calculations show that it is crucial to include third nearest neighbor couplings to obtain the gap in the cis-polyacetylene.

  12. Vessel Segmentation in Medical Imaging Using a Tight-Frame Based Algorithm

    CERN Document Server

    Cai, Xiaohao; Morigi, Serena; Sgallari, Fiorella

    2011-01-01

    Tight-frame, a generalization of orthogonal wavelets, has been used successfully in various problems in image processing, including inpainting, impulse noise removal, super-resolution image restoration, etc. Segmentation is the process of identifying object outlines within images. There are quite a few efficient algorithms for segmentation that depend on the variational approach and the partial differential equation (PDE) modeling. In this paper, we propose to apply the tight-frame approach to automatically identify tube-like structures such as blood vessels in Magnetic Resonance Angiography (MRA) images. Our method iteratively refines a region that encloses the possible boundary or surface of the vessels. In each iteration, we apply the tight-frame algorithm to denoise and smooth the possible boundary and sharpen the region. We prove the convergence of our algorithm. Numerical experiments on real 2D/3D MRA images demonstrate that our method is very efficient with convergence usually within a few iterations, ...

  13. Optimally fast incremental Manhattan plane embedding and planar tight span construction

    Directory of Open Access Journals (Sweden)

    David Eppstein

    2011-10-01

    Full Text Available We describe a data structure, a rectangular complex, that can be used represent hyperconvex metric spaces that have the same topology (although not necessarily the same distance function as subsets of the plane. We show how to use this data structure to construct the tight span of a metric space given as an n×n distance matrix, when the tight span is homeomorphic to a subset of the plane, in time O(n2, and to add a single point to a planar tight span in timeO(n. As an application of this construction, we show how to test whether a given finite metric space embeds isometrically into the Manhattan plane in time O(n2, and add a single point to the space and re-test whether it has such an embedding in time O(n.

  14. Rapid method of quantification of tight-junction organization using image analysis.

    Science.gov (United States)

    Terryn, Christine; Sellami, Mehdi; Fichel, Caroline; Diebold, Marie-Danielle; Gangloff, Sophie; Le Naour, Richard; Polette, Myriam; Zahm, Jean-Marie

    2013-02-01

    The spatial organization of proteins in a cell population or in tissues is an important parameter to study the functionality of biological specimens. In this article, we have focused on tight junctions which form network-like features in immunofluorescence microscopy images. Usually, the organization or disorganization of tight junctions is noticed qualitatively. The aim of this article is to present a simple method to quantify the organization level of tight junction network using image analysis with a dedicated macro developed with Image J software. The method has been validated with simulated images displaying regular decrease of network organization. Then, the macro has been applied to immunofluorescence microscopy images of cells in culture and of tissue sections.

  15. Modulation of Tight Junction Structure and Function by Kinases and Phosphatases Targeting Occludin

    Directory of Open Access Journals (Sweden)

    Max Johannes Dörfel

    2012-01-01

    Full Text Available Tight junctions (TJs typically represent the most apical contacts in epithelial and endothelial cell layers where they play an essential role in the separation of extracellular or luminal spaces from underlying tissues in the body. Depending on the protein composition, TJs define the barrier characteristics and in addition maintain cell polarity. Two major families of integral membrane proteins form the typical TJ strand network, the tight junction-associated MARVEL protein (TAMP family members occludin, tricellulin, and MarvelD3 as well as a specific set of claudins. Occludin was the first identified member of these tetraspanins and is now widely accepted as a regulator of TJ assembly and function. Therefore, occludin itself has to be tightly regulated. Phosphorylation of occludin appears to be of central importance in this context. Here we want to summarize current knowledge on the kinases and phosphatases directly modifying occludin, and their role in the regulation of TJ structure, function, and dynamics.

  16. CT Image Reconstruction by Spatial-Radon Domain Data-Driven Tight Frame Regularization

    CERN Document Server

    Zhan, Ruohan

    2016-01-01

    This paper proposes a spatial-Radon domain CT image reconstruction model based on data-driven tight frames (SRD-DDTF). The proposed SRD-DDTF model combines the idea of joint image and Radon domain inpainting model of \\cite{Dong2013X} and that of the data-driven tight frames for image denoising \\cite{cai2014data}. It is different from existing models in that both CT image and its corresponding high quality projection image are reconstructed simultaneously using sparsity priors by tight frames that are adaptively learned from the data to provide optimal sparse approximations. An alternative minimization algorithm is designed to solve the proposed model which is nonsmooth and nonconvex. Convergence analysis of the algorithm is provided. Numerical experiments showed that the SRD-DDTF model is superior to the model by \\cite{Dong2013X} especially in recovering some subtle structures in the images.

  17. An efficient magnetic tight-binding method for transition metals and alloys

    DEFF Research Database (Denmark)

    Barreteau, Cyrille; Spanjaard, Daniel; Desjonquères, Marie-Catherine

    2016-01-01

    An efficient parameterized self-consistent tight-binding model for transition metals using s, p and d valence atomic orbitals as a basis set is presented. The parameters of our tight-binding model for pure elements are determined from a fit to bulk ab-initio calculations. A very simple procedure...... that does not necessitate any further fitting is proposed to deal with systems made of several chemical elements. This model is extended to spin (and orbital) polarized materials by adding Stoner-like and spin–orbit interactions. Collinear and non-collinear magnetism as well as spin-spirals are considered...

  18. Statistics of Eigenfunctions in 1D Tight Binding Model: Distribution of Riccati Variable

    Institute of Scientific and Technical Information of China (English)

    WANG Wen-Ge

    2001-01-01

    For energy eigenfunctions in 1D tight binding model, the distribution of ratios of the nearest components (Riccati variable), denoted by f(p), gives information on their fluctuation properties. The shape of f(p) is studied numerically for three versions of the 1D tight binding model. It is shown that when perturbation is strong the shape of f(p) is usually quite close to that of the Lorentzian distribution and in the case of weak perturbation the shape of the central part of f(p) is model-dependent while the shape of tails are still close to the Lorentzian form.``

  19. Requirements for gas quality and gas appliances

    NARCIS (Netherlands)

    Levinsky, Howard; Gersen, Sander; Kiewiet, Bert

    2015-01-01

    Introduction The gas transmission network in the Netherlands transports two different qualities of gas, low-calorific gas known as G-gas or L-gas and, high calorific gas (H-gas). These two gas qualities are transported in separate networks, and are connected by means of five blending and conversion

  20. Targeted technology applications for infield reserve growth: A synopsis of the Secondary Natural Gas Recovery project, Gulf Coast Basin. Topical report, September 1988--April 1993

    Energy Technology Data Exchange (ETDEWEB)

    Levey, R.A.; Finley, R.J.; Hardage, B.A.

    1994-06-01

    The Secondary Natural Gas Recovery (SGR): Targeted Technology Applications for Infield Reserve Growth is a joint venture research project sponsored by the Gas Research Institute (GRI), the US Department of Energy (DOE), the State of Texas through the Bureau of Economic Geology at The University of Texas at Austin, with the cofunding and cooperation of the natural gas industry. The SGR project is a field-based program using an integrated multidisciplinary approach that integrates geology, geophysics, engineering, and petrophysics. A major objective of this research project is to develop, test, and verify those technologies and methodologies that have near- to mid-term potential for maximizing recovery of gas from conventional reservoirs in known fields. Natural gas reservoirs in the Gulf Coast Basin are targeted as data-rich, field-based models for evaluating infield development. The SGR research program focuses on sandstone-dominated reservoirs in fluvial-deltaic plays within the onshore Gulf Coast Basin of Texas. The primary project research objectives are: To establish how depositional and diagenetic heterogeneities cause, even in reservoirs of conventional permeability, reservoir compartmentalization and hence incomplete recovery of natural gas. To document examples of reserve growth occurrence and potential from fluvial and deltaic sandstones of the Texas Gulf Coast Basin as a natural laboratory for developing concepts and testing applications. To demonstrate how the integration of geology, reservoir engineering, geophysics, and well log analysis/petrophysics leads to strategic recompletion and well placement opportunities for reserve growth in mature fields.

  1. Gas magnetometer

    Science.gov (United States)

    Walker, Thad Gilbert; Lancor, Brian Robert; Wyllie, Robert

    2016-05-03

    Measurement of a precessional rate of a gas, such as an alkali gas, in a magnetic field is made by promoting a non-uniform precession of the gas in which substantially no net magnetic field affects the gas during a majority of the precession cycle. This allows sensitive gases that would be subject to spin-exchange collision de-phasing to be effectively used for extremely sensitive measurements in the presence of an environmental magnetic field such as the Earth's magnetic field.

  2. Gas magnetometer

    Energy Technology Data Exchange (ETDEWEB)

    Walker, Thad Gilbert; Lancor, Brian Robert; Wyllie, Robert

    2016-05-03

    Measurement of a precessional rate of a gas, such as an alkali gas, in a magnetic field is made by promoting a non-uniform precession of the gas in which substantially no net magnetic field affects the gas during a majority of the precession cycle. This allows sensitive gases that would be subject to spin-exchange collision de-phasing to be effectively used for extremely sensitive measurements in the presence of an environmental magnetic field such as the Earth's magnetic field.

  3. Gas chromatography

    Science.gov (United States)

    Guiochon, Georges; Guillemin, Claude L.

    1990-11-01

    Gas chromatography is a powerful separation technique for gas and vapor mixtures. Combining separation and on-line detection permits accurate quantitative analysis of complex mixtures, including traces of compounds down to parts per trillions in some particular cases. The importance of gas chromatography in quality control and process control in the chemical and drug industry, in environmental pollution investigations and in clinical analysis is critical. The principles of the technique are discussed, the main components of a gas chromatograph are described and some idea of the importance of the applications is given.

  4. Geologic Characteristics of Gas Reservoirs in West Sichuan Foreland Basin

    Institute of Scientific and Technical Information of China (English)

    YANG Keming

    2008-01-01

    The foreland basin in West Sichuan is a tectonic unit that has undergone multi-periods tectonic movements of Indosinian-Yanshanian-Himalayan. Since late Triassic, it has been in a passive subsidence environment controlled by basin margin mountain systems and by the compression with abundant sediment sources. With the complex geologic setting, the main geologic characteristics of natural gas reservoir are listed as following:(1)Source rocks are coal-bearing mud and shale series with high to over maturity, and long and progressive hydrocarbon generation-displacement period. The key accumulation period is middle-late Yanshanian epoch.(2)There are three gas-bearing systems vertically, each of which has different reservoir mechanism, main-controlled factors and distribution law, so the exploration thoughts and techniques are also different.(3)Undergoing multi-period generation-migration-accumulation, oil and gas have encountered multi-period modification or destruction, and gas accumulation overpass multiple tectonic periods. So the trap type is complicated and dominated by combination traps. Because the main accumulation period of natural gas is early and the reservoir encountered the modification of strong Himalayan movement, there is great difference in the fullness degree of gas reservoirs and complicated gas-water relation. (4) Reservoir is tight to very tight, but reservoirs of relatively high quality developed under the super tight setting. (5) The key techniques for oil and gas exploration in west Sichuan foreland basin are the prediction of relatively favorable reservoirs, fractures and gas bearing; and the key techniques for oil and gas development are how to improve the penetration rate, reservoir protection and modification.

  5. Tight Turns

    Directory of Open Access Journals (Sweden)

    Jenifer Sutherland

    2013-01-01

    Full Text Available The plain text was task-oriented in a roundabout way, providing detailed instructions for how NOT to build an elaborate sequence of bridges, each one bound to produce, according to chapters one through twenty-three, disastrous results. Graphic novels disguised as illuminated letters twisted the tent-dwelling decipherer into painful self-recognition. The flashlight followed the phases of the moon. Meanwhile one strand of marginalia, written in anxious back-slant, pleaded for some kind of adjustable form for managing the confluence, especially during flood season. I like what we came up with. 'We' is a little big word. In fact the tent turns out to be one of those Borgesian core-tech structures allowing for astonishing internal expansion. There's not much we didn't get in there and not much in there that didn't get us. So I suppose that's it. This tent. This confluence. These children who found me here, turned text into life and made life home.

  6. Tight junction changes in epithelial cells by Campylobacter jejuni and non-jejuni Campylobacter species

    DEFF Research Database (Denmark)

    Bücker, Roland; Nielsen, Hans Linde; Krüg, S

    in Ussing chambers. Tight junction (TJ) protein expression was determined by Western blotting, and subcellular TJ distribution was analyzed by confocal laser-scanning microscopy. Apoptosis induction was examined by TUNEL-staining and Western blot of caspase-3 activation. All strains invaded confluent HT-29...

  7. Kiwifruit cysteine protease actinidin compromises the intestinal barrier by disrupting tight junctions

    NARCIS (Netherlands)

    Grozdanovic, Milica M; Čavić, Milena; Nešić, Andrijana; Andjelković, Uroš; Akbari, Peyman; Smit, Joost J; Gavrović-Jankulović, Marija

    2016-01-01

    BACKGROUND: The intestinal epithelium forms a barrier that food allergens must cross in order to induce sensitization. The aim of this study was to evaluate the impact of the plant-derived food cysteine protease--actinidin (Act d1) on the integrity of intestinal epithelium tight junctions (TJs). MET

  8. TIGHT-BINDING MOLECULAR DYNAMICS STUDY OF C60-GRAPHITE COLLISIONS

    Institute of Scientific and Technical Information of China (English)

    Fang Yun-tuan; Luo Cheng-lin

    2000-01-01

    We report the tight-binding molecular dynamics simulations of C60 impacting on a graphite (0001) surface with different incident energy. The simulations provide detailed characterizations of the microscopic processes occurring during the collisions and show insight into the deposition mechanisms of C60 on semiconductor substrate.

  9. Influence of composite resin consistency and placement technique on proximal contact tightness of Class II restorations.

    NARCIS (Netherlands)

    Loomans, B.A.C.; Opdam, N.J.M.; Roeters, F.J.M.; Bronkhorst, E.M.; Plasschaert, A.J.M.

    2006-01-01

    PURPOSE: To investigate the influence of composite resin consistency and placement technique on proximal contact tightness of Class II composite resin restorations. MATERIALS AND METHODS: A manikin model (KaVo Dental) was used with an artificial first molar in which a standardized MO preparation was

  10. Tight complexity bounds for FPT subgraph problems parameterized by clique-width

    NARCIS (Netherlands)

    Broersma, Hajo; Golovach, Petr A.; Patel, Viresh; Marx, D.; Rossmanith, P.

    2012-01-01

    We give tight algorithmic lower and upper bounds for some double-parameterized subgraph problems when the clique-width of the input graph is one of the parameters. Let G be an arbitrary input graph on n vertices with clique-width at most w. We prove the following results. The Dense (Sparse) k -Subgr

  11. AUV Positioning Method Based on Tightly Coupled SINS/LBL for Underwater Acoustic Multipath Propagation

    Directory of Open Access Journals (Sweden)

    Tao Zhang

    2016-03-01

    Full Text Available This paper researches an AUV (Autonomous Underwater Vehicle positioning method based on SINS (Strapdown Inertial Navigation System/LBL (Long Base Line tightly coupled algorithm. This algorithm mainly includes SINS-assisted searching method of optimum slant-range of underwater acoustic propagation multipath, SINS/LBL tightly coupled model and multi-sensor information fusion algorithm. Fuzzy correlation peak problem of underwater LBL acoustic propagation multipath could be solved based on SINS positional information, thus improving LBL positional accuracy. Moreover, introduction of SINS-centered LBL locating information could compensate accumulative AUV position error effectively and regularly. Compared to loosely coupled algorithm, this tightly coupled algorithm can still provide accurate location information when there are fewer than four available hydrophones (or within the signal receiving range. Therefore, effective positional calibration area of tightly coupled system based on LBL array is wider and has higher reliability and fault tolerance than loosely coupled. It is more applicable to AUV positioning based on SINS/LBL.

  12. AUV Positioning Method Based on Tightly Coupled SINS/LBL for Underwater Acoustic Multipath Propagation.

    Science.gov (United States)

    Zhang, Tao; Shi, Hongfei; Chen, Liping; Li, Yao; Tong, Jinwu

    2016-03-11

    This paper researches an AUV (Autonomous Underwater Vehicle) positioning method based on SINS (Strapdown Inertial Navigation System)/LBL (Long Base Line) tightly coupled algorithm. This algorithm mainly includes SINS-assisted searching method of optimum slant-range of underwater acoustic propagation multipath, SINS/LBL tightly coupled model and multi-sensor information fusion algorithm. Fuzzy correlation peak problem of underwater LBL acoustic propagation multipath could be solved based on SINS positional information, thus improving LBL positional accuracy. Moreover, introduction of SINS-centered LBL locating information could compensate accumulative AUV position error effectively and regularly. Compared to loosely coupled algorithm, this tightly coupled algorithm can still provide accurate location information when there are fewer than four available hydrophones (or within the signal receiving range). Therefore, effective positional calibration area of tightly coupled system based on LBL array is wider and has higher reliability and fault tolerance than loosely coupled. It is more applicable to AUV positioning based on SINS/LBL.

  13. Microlensing discovery of a population of very tight, very low mass binary brown dwarfs

    DEFF Research Database (Denmark)

    Choi, J.-Y.; Han, C.; Udalski, A.

    2013-01-01

    the discovery via gravitational microlensing of two very low mass, very tight binary systems. These binaries have directly and precisely measured total system masses of 0.025 M ☉ and 0.034 M ☉, and projected separations of 0.31 AU and 0.19 AU, making them the lowest-mass and tightest field BD binaries known...

  14. Normalization and perturbation theory for tightly bound states of the spinor Bethe-Salpeter equation

    NARCIS (Netherlands)

    L.G. Suttorp

    1976-01-01

    The normalisation integrals for the tightly-bound-state solutions of the spinor Bethe-Salpeter equation that have been derived recently are evaluated. Ghost states are found to appear when the continuous parameters characterising the type of fermion-boson interaction reach a critical value. Perturba

  15. Side-stream smoking reduces intestinal inflammation and increases expression of tight junction proteins

    Institute of Scientific and Technical Information of China (English)

    Hui Wang; Jun-Xing Zhao; Nan Hu; Jun Ren; Min Du; Mei-Jun Zhu

    2012-01-01

    AIM:To investigate the effect of side-stream smoking on gut microflora composition,intestinal inflammation and expression of tight junction proteins.METHODS:C57BL/6 mice were exposed to side-stream cigarette smoking for one hour daily over eight weeks.Cecal contents were collected for microbial composition analysis.Large intestine was collected for immunoblotting and quantitative reverse transcriptase polymerase chain reaction analyses of the inflammatory pathway and tight junction proteins.RESULTS:Side-stream smoking induced significant changes in the gut microbiota with increased mouse intestinal bacteria,Clostridium but decreased Fermicutes (Lactoccoci and Ruminococcus),Enterobacteriaceae family and Segmented filamentous baceteria compared to the control mice.Meanwhile,side-stream smoking inhibited the nuclear factor-κB pathway with reduced phosphorylation of p65 and IκBα,accompanied with unchanged mRNA expression of tumor necrosis factor-α or interleukin-6.The contents of tight junction proteins,claudin3 and ZO2 were up-regulated in the large intestine of mice exposed side-stream smoking.In addition,side-stream smoking increased c-Jun N-terminal kinase and p38 MAPK kinase signaling,while inhibiting AMP-activated protein kinase in the large intestine.CONCLUSION:Side-stream smoking altered gut microflora composition and reduced the inflammatory response,which was associated with increased expression of tight junction proteins.

  16. The Passions of Learning in Tight Circumstances: Toward a Political Economy of the Mind

    Science.gov (United States)

    McDermott, Ray

    2010-01-01

    Economies make their demands, and by necessity, people adjust, learn, and survive. People adjust to tight circumstances with passion and ingenuity. Necessity and its passions are the stuff of reality and generally more than schools or educational research can handle. Mainstream theories of learning have captured economic constraints only…

  17. Self consistent tight binding molecular dynamics study of Ti02 nanoclusters in water.

    Energy Technology Data Exchange (ETDEWEB)

    Erdin, S.; Lin, Y.; Halley, J. W.; Zapol, P.; Redfern, P.; Curtiss, L.; Northern Illinois Univ.; Univ. of Minnesota

    2007-09-01

    Self-consistent tight binding molecular dynamics studies of TiO{sub 2}2 anatase and rutile nanoclusters in dissociable water are reported. It is found that the structure of the particle expands as a result of interaction between the particle's surface and water. Water molecules dissociate at the nanoparticle surface during simulation.

  18. Self-consistent tight-binding model of B and N doping in graphene

    DEFF Research Database (Denmark)

    Pedersen, Thomas Garm; Pedersen, Jesper Goor

    2013-01-01

    Boron and nitrogen substitutional impurities in graphene are analyzed using a self-consistent tight-binding approach. An analytical result for the impurity Green's function is derived taking broken electron-hole symmetry into account and validated by comparison to numerical diagonalization...

  19. Results from Tight and Loose Coupled Multiphysics in Nuclear Fuels Performance Simulations using BISON

    Energy Technology Data Exchange (ETDEWEB)

    S. R. Novascone; B. W. Spencer; D. Andrs; R. L. Williamson; J. D. Hales; D. M. Perez

    2013-05-01

    The behavior of nuclear fuel in the reactor environment is affected by multiple physics, most notably heat conduction and solid mechanics, which can have a strong influence on each other. To provide credible solutions, a fuel performance simulation code must have the ability to obtain solutions for each of the physics, including coupling between them. Solution strategies for solving systems of coupled equations can be categorized as loosely-coupled, where the individual physics are solved separately, keeping the solutions for the other physics fixed at each iteration, or tightly coupled, where the nonlinear solver simultaneously drives down the residual for each physics, taking into account the coupling between the physics in each nonlinear iteration. In this paper, we compare the performance of loosely and tightly coupled solution algorithms for thermomechanical problems involving coupled thermal and mechanical contact, which is a primary source of interdependence between thermal and mechanical solutions in fuel performance models. The results indicate that loosely-coupled simulations require significantly more nonlinear iterations, and may lead to convergence trouble when the thermal conductivity of the gap is too small. We also apply the tightly coupled solution strategy to a nuclear fuel simulation of an experiment in a test reactor. Studying the results from these simulations indicates that perhaps convergence for either approach may be problem dependent, i.e., there may be problems for which a loose coupled approach converges, where tightly coupled won’t converge and vice versa.

  20. Electron-hole correlations in semiconductor quantum dots with tight-binding wave fuctions

    Science.gov (United States)

    Seungwon, L.; Jonsson, L.; Wilkins, J.; Bryant, G.; Klimeck, G.

    2001-01-01

    The electron-hole states of semiconductor quantum dots are investigated within the framework of empirical tight-binding descriptions for Si, as an example of an indirect-gap material, and InAs and CdSe as examples of typical III-V and II-VI direct-gap materials.

  1. Normalization and perturbation theory for tightly bound states of the spinor Bethe-Salpeter equation

    NARCIS (Netherlands)

    Suttorp, L.G.

    1976-01-01

    The normalisation integrals for the tightly-bound-state solutions of the spinor Bethe-Salpeter equation that have been derived recently are evaluated. Ghost states are found to appear when the continuous parameters characterising the type of fermion-boson interaction reach a critical value. Perturba

  2. Exact solutions of the spinor Bethe-Salpeter equation for tightly bound states

    NARCIS (Netherlands)

    Suttorp, L.G.

    1975-01-01

    Exact solutions are obtained for the spinor Bethe-Salpeter equation that describes tightly bound states of spin-/sup 1///sub 2/ fermions with massless-boson exchange. The corresponding coupling constants form a discrete spectrum that depends continuously on the parameters characterizing the type of

  3. MRI tight posterior fossa sign for prenatal diagnosis of Chiari type II malformation

    Energy Technology Data Exchange (ETDEWEB)

    Ando, Kumiko; Ishikura, Reiichi; Ogawa, Masayo; Takada, Yoshihiro; Yamamoto, Satoshi; Fujiwara, Masayuki; Hirota, Shozo [Hyogo College of Medicine, Department of Radiology, Nishinomiya, Hyogo (Japan); Shakudo, Miyuki [Osaka City General Hospital, Department of Radiology, Osaka (Japan); Tanaka, Hiroyuki [Hyogo College of Medicine, Department of Gynecology, Nishinomiya (Japan); Minagawa, Kyoko [Hyogo College of Medicine, Department of Pediatrics, Nishinomiya (Japan)

    2007-12-15

    Chiari type II malformation (CMII) is one of three hindbrain malformations that display hydrocephalus. We have observed that cerebrospinal fluid (CSF) signal in the posterior fossa, which is always apparent on normal fetal MR images, is not visible in a fetus with CMII. We use the term 'tight posterior fossa' for this MR imaging finding, and evaluate the diagnostic value of this finding on fetal MR images. Included in the study were 21 fetuses which underwent brain MR imaging at 1.5 T using two-dimensional balanced turbo-field-echo (2-D balanced-TFE) in the axial and sagittal planes. Postnatal diagnoses were CMII (n=5), CNS abnormalities other than CMII (n=8), and no abnormality (n=8). A tight posterior fossa was defined as an absent or slit-like water signal space around the hindbrain in the posterior fossa on both sagittal and axial MR images. All CMII fetuses displayed a tight posterior fossa on MR images. Hydrocephalus was visualized in all CMII fetuses and myelomeningocele in four fetuses, but hindbrain herniation was visualized only in two of five fetuses. The CSF signal surrounding the hindbrain was clearly visible in all the other 16 fetuses, including five with hydrocephalus not associated with CMII, although it was slightly narrower in a fetus with a cloverleaf skull than in the normal fetuses. Tight posterior fossa in the presence of hydrocephalus is a useful and characteristic finding of CMII on fetal MRI. (orig.)

  4. Regulation of Tight Junction Permeability by Intestinal Bacteria and Dietary Components

    NARCIS (Netherlands)

    Ulluwishewa, D.; Anderson, R.C.; McNabb, W.C.; Moughan, P.J.; Wells, J.; Roy, N.C.

    2011-01-01

    The human intestinal epithelium is formed by a single layer of epithelial cells that separates the intestinal lumen from the underlying lamina propria. The space between these cells is sealed by tight junctions (TJ), which regulate the permeability of the intestinal barrier. TJ are complex protein s

  5. Exact solutions of the spinor Bethe-Salpeter equation for tightly bound states

    NARCIS (Netherlands)

    Suttorp, L.G.

    1975-01-01

    Exact solutions are obtained for the spinor Bethe-Salpeter equation that describes tightly bound states of spin-/sup 1///sub 2/ fermions with massless-boson exchange. The corresponding coupling constants form a discrete spectrum that depends continuously on the parameters characterizing the type of

  6. Regulation of Tight Junction Permeability by Intestinal Bacteria and Dietary Components

    NARCIS (Netherlands)

    Ulluwishewa, D.; Anderson, R.C.; McNabb, W.C.; Moughan, P.J.; Wells, J.; Roy, N.C.

    2011-01-01

    The human intestinal epithelium is formed by a single layer of epithelial cells that separates the intestinal lumen from the underlying lamina propria. The space between these cells is sealed by tight junctions (TJ), which regulate the permeability of the intestinal barrier. TJ are complex protein

  7. Microwave emulations and tight-binding calculations of transport in polyacetylene

    Energy Technology Data Exchange (ETDEWEB)

    Stegmann, Thomas, E-mail: stegmann@icf.unam.mx [Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Avenida Universidad s/n, 62210 Cuernavaca (Mexico); Franco-Villafañe, John A., E-mail: jofravil@fis.unam.mx [Instituto de Física, Benemérita Universidad Autónoma de Puebla, Apartado Postal J-48, 72570 Puebla (Mexico); Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Avenida Universidad s/n, 62210 Cuernavaca (Mexico); Ortiz, Yenni P. [Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Avenida Universidad s/n, 62210 Cuernavaca (Mexico); Kuhl, Ulrich [Université de Nice – Sophia Antipolis, Laboratoire de la Physique de la Matière Condensée, CNRS, Parc Valrose, 06108 Nice (France); Mortessagne, Fabrice, E-mail: fabrice.mortessagne@unice.fr [Université de Nice – Sophia Antipolis, Laboratoire de la Physique de la Matière Condensée, CNRS, Parc Valrose, 06108 Nice (France); Seligman, Thomas H. [Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Avenida Universidad s/n, 62210 Cuernavaca (Mexico); Centro Internacional de Ciencias, 62210 Cuernavaca (Mexico)

    2017-01-05

    A novel approach to investigate the electron transport of cis- and trans-polyacetylene chains in the single-electron approximation is presented by using microwave emulation measurements and tight-binding calculations. In the emulation we take into account the different electronic couplings due to the double bonds leading to coupled dimer chains. The relative coupling constants are adjusted by DFT calculations. For sufficiently long chains a transport band gap is observed if the double bonds are present, whereas for identical couplings no band gap opens. The band gap can be observed also in relatively short chains, if additional edge atoms are absent, which cause strong resonance peaks within the band gap. The experimental results are in agreement with our tight-binding calculations using the nonequilibrium Green's function method. The tight-binding calculations show that it is crucial to include third nearest neighbor couplings to obtain the gap in the cis-polyacetylene. - Highlights: • Electronic transport in individual polyacetylene chains is studied. • Microwave emulation experiments and tight-binding calculations agree well. • In long chains a band-gap opens due the dimerization of the chain. • In short chains edge atoms cause strong resonance peaks in the center of the band-gap.

  8. Quantum confined Stark effect in Gaussian quantum wells: A tight-binding study

    Energy Technology Data Exchange (ETDEWEB)

    Ramírez-Morales, A.; Martínez-Orozco, J. C.; Rodríguez-Vargas, I. [Unidad Académica de Física, Universidad Autónoma de Zacatecas, Calzada Solidaridad Esquina Con Paseo La Bufa S/N, 98060 Zacatecas, Zac. (Mexico)

    2014-05-15

    The main characteristics of the quantum confined Stark effect (QCSE) are studied theoretically in quantum wells of Gaussian profile. The semi-empirical tight-binding model and the Green function formalism are applied in the numerical calculations. A comparison of the QCSE in quantum wells with different kinds of confining potential is presented.

  9. Evaluation of arthroscopic stabilization of acute acromioclavicular joint dislocation using the TightRope system.

    Science.gov (United States)

    El Sallakh, Sameh A

    2012-01-16

    The purpose of this study was to evaluate the results of the arthroscopic treatment of acute acromioclavicular dislocation using the TightRope system (Arthrex, Naples, Florida). Between January 2006 and May 2007, ten shoulders in 10 patients with acute acromioclavicular joint dislocation (Rockwood types IV and V) underwent arthroscopic acromioclavicular joint stabilization using the TightRope. Average patient age was 30 years (range, 22-42 years), and mean follow-up was 24 months (range, 18-30 months). Follow-up occurred at 2 and 6 weeks, 3 months, and then every 6 months postoperatively. The shoulders were evaluated radiologically by comparing the acromioclavicular joint with the normal side and clinically by assessing the pain, function, and range of joint motion using the Constant score.Ten patients returned to work without pain 10 to 12 weeks postoperatively. Average Constant score was 96.3 (range, 94-99) at last follow-up. Because of technical error, 1 patient experienced TightRope fixation failure on the coracoid side, and the acromioclavicular joint was redislocated, which was treated by an open technique. The 10 patients were satisfied with their functional results and cosmetic appearance.The arthroscopic treatment of acute acromioclavicular dislocation using the TightRope is a minimally invasive surgical technique that has been proven effective for the treatment of these lesions. It is characterized by less morbidity, less hospitalization, excellent cosmoses, and early rehabilitation. Copyright 2012, SLACK Incorporated.

  10. West Nile virus infection causes endocytosis of a specific subset of tight junction membrane proteins.

    Directory of Open Access Journals (Sweden)

    Zaikun Xu

    Full Text Available West Nile virus (WNV is a blood-borne pathogen that causes systemic infections and serious neurological disease in human and animals. The most common route of infection is mosquito bites and therefore, the virus must cross a number of polarized cell layers to gain access to organ tissue and the central nervous system. Resistance to trans-cellular movement of macromolecules between epithelial and endothelial cells is mediated by tight junction complexes. While a number of recent studies have documented that WNV infection negatively impacts the barrier function of tight junctions, the intracellular mechanism by which this occurs is poorly understood. In the present study, we report that endocytosis of a subset of tight junction membrane proteins including claudin-1 and JAM-1 occurs in WNV infected epithelial and endothelial cells. This process, which ultimately results in lysosomal degradation of the proteins, is dependent on the GTPase dynamin and microtubule-based transport. Finally, infection of polarized cells with the related flavivirus, Dengue virus-2, did not result in significant loss of tight junction membrane proteins. These results suggest that neurotropic flaviviruses such as WNV modulate the host cell environment differently than hemorrhagic flaviviruses and thus may have implications for understanding the molecular basis for neuroinvasion.

  11. Intracellular pH is a tightly controlled signal in yeast

    NARCIS (Netherlands)

    Orij, R.; Brul, S.; Smits, G.J.

    2011-01-01

    Background: Nearly all processes in living cells are pH dependent, which is why intracellular pH (pHi) is a tightly regulated physiological parameter in all cellular systems. However, in microbes such as yeast, pHi responds to extracellular conditions such as the availability of nutrients. This rais

  12. Effect of Extracorporeal Shock Wave Therapy on Hamstring Tightness in Healthy Subjects: A Pilot Study.

    Science.gov (United States)

    Kim, Yong Wook; Chang, Won Hyuk; Kim, Na Young; Kwon, Jun Beom; Lee, Sang Chul

    2017-05-01

    To assess the effect of extracorporeal shock wave therapy (ESWT) for healthy participants with hamstring tightness. This study was performed at a university rehabilitation hospital. Twenty nine healthy adults with hamstring tightness were enrolled and randomly allocated into four groups (ESWT, stretching exercise, ESWT with stretching exercise, and control). The effects of individual treatments were compared by the finger-to-floor test and popliteal angle. The ESWT group, stretching exercise group and ESWT with stretching exercise group had decreased finger-to-floor distances and right popliteal angles immediately after intervention, compared with the control group (p<0.05). At 4 weeks after completion of the interventions, finger-to-floor distances and the right popliteal angle in only the ESWT with stretching exercise group showed a significant improvement, compared with the control group (p=0.008 and 0.023). While ESWT and stretching both reduced hamstring tightness immediately after interventions, only ESWT with stretching exercise maintained the significantly improved relief of hamstring tightness significantly after 4 weeks.

  13. Field evaluation of gas well stimulation methods, Sutton County, Texas

    Energy Technology Data Exchange (ETDEWEB)

    Smith, C.F.; Murphy, D.L.

    1974-01-01

    Attempts to stimulate marginal gas producers in Sutton County, Texas, has provided an opportunity to evaluate several types of stimulation fluids on a comparative basis. The fluids used included water-base, oil-base, and acid-base fluids. A thorough study of the production history of wells following treatment demonstrates the effectiveness of the different fluids on a long term basis. Conclusions drawn from this study provide a guide to selection of fracture fluids for tight gas sands. Cost-performance factors are explored as they apply to stimulation of marginal gas production and further conclusions are drawn concerning the importance of formation damage as a function of formation petrophysical properties. Examples are shown to indicate formation damage is a factor to consider in fracturing tight sands but performance comprises may be made in the choice of fluid to obtain maximum frac penetration.

  14. Landfill gas

    Energy Technology Data Exchange (ETDEWEB)

    Willumsen, H. (Crone and Koch, Viborg (Denmark))

    1990-08-01

    In most landfills, the refuse deposit usually has a high content of organic matter consisting of a mixture of household, industrial and garden waste. Immediately after the refuse has been placed in the landfill, aerobic decomposition of the organic waste begins. Once the oxygen has been exhausted, anaerobic decomposition begins. 'Biogas' is produced which has a methane content of approximately 50% and can be used as a fuel. The exploitation of landfill gas for energy purposes was initiated in the USA around 1975 and later in Europe. A landfill gas plant consists of a recovery system and a production system. A recovery system can consist of vertical perforated pipe wells, horizontal perforated pipes or ditches, or membrane covers to collect the generated gas. Under normal conditions it will not be necessary to process the gas except for the removal of water and other impurities (e.g. solid particles) if the gas is to be used in a boiler or engine. In the USA most often only power is produced, whereas in Europe the waste heat is normally exploited, making the plant function as a combined power and heating plant. It is also possible to upgrade the landfill gas to a methane content of nearly 100, after which it can be distributed with natural gas. There are several such plants in the USA. 8 refs., 6 figs., 6 tabs.

  15. Gas turbines

    Energy Technology Data Exchange (ETDEWEB)

    Farahan, E.; Eudaly, J.P.

    1978-10-01

    This evaluation provides performance and cost data for commercially available simple- and regenerative-cycle gas turbines. Intercooled, reheat, and compound cycles are discussed from theoretical basis only, because actual units are not currently available, except on a special-order basis. Performance characteristics investigated include unit efficiency at full-load and off-design conditions, and at rated capacity. Costs are tabulated for both simple- and regenerative-cycle gas turbines. The output capacity of the gas turbines investigated ranges from 80 to 134,000 hp for simple units and from 12,000 to 50,000 hp for regenerative units.

  16. Gas hydrates

    Digital Repository Service at National Institute of Oceanography (India)

    Ramprasad, T.

    and the role it plays in the global climate and the future of fuels. Russia, Japan, Nigeria, Peru, Chile, Pakistan, Indonesia, Korea, etc are various countries who are perusing the gas hydrates studies as a future resource for fuel. Indian Initiative..., 1993, Free gas at the base of the gas hydrate zone in the vicinity of the Chile Triple junction: Geology, v. 21, pp. 905-908. Borowski, W.S., C.K. Paull, and U. William, III, 1999, Global and local variations of interstitial sulfate gradients...

  17. Western Gas Sands Project: stratigrapy of the Piceance Basin

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, S. (comp.)

    1980-08-01

    The Western Gas Sands Project Core Program was initiated by US DOE to investigate various low permeability, gas bearing sandstones. Research to gain a better geological understanding of these sandstones and improve evaluation and stimulation techniques is being conducted. Tight gas sands are located in several mid-continent and western basins. This report deals with the Piceance Basin in northwestern Colorado. This discussion is an attempt to provide a general overview of the Piceance Basin stratigraphy and to be a useful reference of stratigraphic units and accompanying descriptions.

  18. Gas gangrene

    Science.gov (United States)

    ... also can be caused by group A streptococcus, Staphylococcus aureus, and Vibrio vulnificus . Clostridium is found nearly everywhere. As the bacteria grow inside the body, it makes gas and harmful substances (toxins) that can damage body tissues, cells, and blood ...

  19. "Tight" and "Loose" Are Not Created Equal: An Asymmetry Underlying the Representation of "Fit" in English- and Korean-Speakers

    Science.gov (United States)

    Norbury, Heather M.; Waxman, Sandra R.; Song, Hyun-Joo

    2008-01-01

    Research concerning the spatial dimension "fit" ("tight" versus "loose") has been based on a tacit but untested assumption that the dimension "fit" is symmetrical, with tight- and loose-fitting relations highlighting the dimension "fit" with equal force. We propose a reformulation, documenting that adult speakers of English (Experiment 1) and…

  20. Development of a Simulation Framework for Analyzing Security of Supply in Integrated Gas and Electric Power Systems

    NARCIS (Netherlands)

    Pambour, Kwabena Addo; Erdener, Burcin Cakir; Bolado-Lavin, Ricardo; Dijkema, Gerhard

    2017-01-01

    Gas and power networks are tightly coupled and interact with each other due to physically interconnected facilities. In an integrated gas and power network, a contingency observed in one system may cause iterative cascading failures, resulting in network wide disruptions. Therefore, understanding th

  1. The Noble Gas Fingerprint in a UK Unconventional Gas Reservoir

    Science.gov (United States)

    McKavney, Rory; Gilfillan, Stuart; Györe, Domokos; Stuart, Fin

    2016-04-01

    In the last decade, there has been an unprecedented expansion in the development of unconventional hydrocarbon resources. Concerns have arisen about the effect of this new industry on groundwater quality, particularly focussing on hydraulic fracturing, the technique used to increase the permeability of the targeted tight shale formations. Methane contamination of groundwater has been documented in areas of gas production1 but conclusively linking this to fugitive emissions from unconventional hydrocarbon production has been controversial2. A lack of baseline measurements taken before drilling, and the equivocal interpretation of geochemical data hamper the determination of possible contamination. Common techniques for "fingerprinting" gas from discrete sources rely on gas composition and isotopic ratios of elements within hydrocarbons (e.g. δ13CCH4), but the original signatures can be masked by biological and gas transport processes. The noble gases (He, Ne, Ar, Kr, Xe) are inert and controlled only by their physical properties. They exist in trace quantities in natural gases and are sourced from 3 isotopically distinct environments (atmosphere, crust and mantle)3. They are decoupled from the biosphere, and provide a separate toolbox to investigate the numerous sources and migration pathways of natural gases, and have found recent utility in the CCS4 and unconventional gas5 industries. Here we present a brief overview of noble gas data obtained from a new coal bed methane (CBM) field, Central Scotland. We show that the high concentration of helium is an ideal fingerprint for tracing fugitive gas migration to a shallow groundwater. The wells show variation in the noble gas signatures that can be attributed to differences in formation water pumping from the coal seams as the field has been explored for future commercial development. Dewatering the seams alters the gas/water ratio and the degree to which noble gases degas from the formation water. Additionally the

  2. Field monitoring and evaluation of a residential gas-engine-driven heat pump: Volume 2, Heating season

    Energy Technology Data Exchange (ETDEWEB)

    Miller, J.D.

    1995-11-01

    The Federal Government is the largest single energy consumer in the United States; consumption approaches 1.5 quads/year of energy (1 quad = 10{sup 15} Btu) at a cost valued at nearly $10 billion annually. The US Department of Energy (DOE) Federal Energy Management Program (FEMP) supports efforts to reduce energy use and associated expenses in the Federal sector. One such effort, the New Technology Demonstration Program (NTDP), seeks to evaluate new energy-saving US technologies and secure their more timely adoption by the US Government. Pacific Northwest Laboratory (PNL) is one of four DOE national multiprogram laboratories that participate in the NTDP by providing technical expertise and equipment to evaluate new, energy-saving technologies being studied and evaluated under that program. This two-volume report describes a field evaluation that PNL conducted for DOE/FEMP and the US Department of Defense (DoD) Strategic Environmental Research and Development Program (SERDP) to examine the performance of a candidate energy-saving technology -- a gas-engine-driven heat pump. The unit was installed at a single residence at Fort Sam Houston, a US Army base in San Antonio, Texas, and the performance was monitored under the NTDP. Participating in this effort under a Cooperative Research and Development Agreement (CRADA) were York International, the heat pump manufacturer; Gas Research Institute (GRI), the technology developer; City Public Service of San Antonio, the local utility; American Gas Cooling Center (AGCC); Fort Sam Houston; and PNL.

  3. Field monitoring and evaluation of a residential gas-engine-driven heat pump: Volume 1, Cooling season

    Energy Technology Data Exchange (ETDEWEB)

    Miller, J.D.

    1995-09-01

    The Federal government is the largest single energy consumer in the United States; consumption approaches 1.5 quads/year of energy (1 quad = 10{sup 15} Btu) at a cost valued at nearly $10 billion annually. The US Department of Energy (DOE) Federal Energy Management Program (FEMP) supports efforts to reduce energy use and associated expenses in the Federal sector. One such effort, the New Technology Demonstration Program (NTDP), seeks to evaluate new energy-saving US technologies and secure their more timely adoption by the US government. Pacific Northwest Laboratory (PNL)is one of four DOE national multiprogram laboratories that participate in the NTDP by providing technical expertise and equipment to evaluate new, energy-saving technologies being studied and evaluated under that program. This two-volume report describes a field evaluation that PNL conducted for DOE/FEMP and the US Department of Defense (DoD) Strategic Environmental Research and Development Program (SERDP) to examine the performance of a candidate energy-saving technology -- a gas-engine-driven heat pump. The unit was installed at a single residence at Fort Sam Houston, a US Army base in San Antonio, Texas, and the performance was monitored under the NTDP. Participating in this effort under a Cooperative Research and Development Agreement (CRADA) were York International, the heat pump manufacturer, Gas Research Institute (GRI), the technology developer; City Public Service of San Antonio, the local utility; American Gas Cooling Center (AGCC); Fort Sam Houston; and PNL.

  4. 40 CFR 63.1282 - Test methods, compliance procedures, and compliance demonstrations.

    Science.gov (United States)

    2010-07-01

    ... average benzene emissions using the model GRI-GLYCalcTM, Version 3.0 or higher, and the procedures presented in the associated GRI-GLYCalcTM Technical Reference Manual. Inputs to the model shall be... procedures documented in the Gas Research Institute (GRI) report entitled “Atmospheric Rich/Lean Method for...

  5. Assessment of Undiscovered Natural Gas Resources of the Arkoma Basin Province and Geologically Related Areas

    Science.gov (United States)

    Houseknecht, David W.; Coleman, James L.; Milici, Robert C.; Garrity, Christopher P.; Rouse, William A.; Fulk, Bryant R.; Paxton, Stanley T.; Abbott, Marvin M.; Mars, John L.; Cook, Troy A.; Schenk, Christopher J.; Charpentier, Ronald R.; Klett, Timothy R.; Pollastro, Richard M.; Ellis, Geoffrey S.

    2010-01-01

    Using a geology-based assessment methodology, the U.S. Geological Survey estimated mean volumes of 38 trillion cubic feet (TCF) of undiscovered natural gas, 159 million barrels of natural gas liquid (MMBNGL), and no oil in accumulations of 0.5 million barrels (MMBO) or larger in the Arkoma Basin Province and related areas. More than 97 percent of the undiscovered gas occurs in continuous accumulations-70 percent in shale gas formations, 18 percent in a basin-centered accumulation with tight sandstone reservoirs, and 9 percent in coal beds. Less than 3 percent of the natural gas occurs in conventional accumulations.

  6. Enteropathogenic E. coli: breaking the intestinal tight junction barrier [version 2; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Anand Prakash Singh

    2016-05-01

    Full Text Available Enteropathogenic E. coli (EPEC causes acute intestinal infections in infants in the developing world. Infection typically spreads through contaminated food and water and leads to severe, watery diarrhea. EPEC attaches to the intestinal epithelial cells and directly injects virulence factors which modulate multiple signaling pathways leading to host cell dysfunction. However, the molecular mechanisms that regulate the onset of diarrhea are poorly defined. A major target of EPEC is the host cell tight junction complex which acts as a barrier and regulates the passage of water and solutes through the paracellular space. In this review, we focus on the EPEC effectors that target the epithelial barrier, alter its functions and contribute to leakage through the tight junctions.

  7. Compactly supported tight wavelet frames and orthonormal wavelets of exponential decay with a general dilation matrix

    Science.gov (United States)

    Han, Bin

    2003-06-01

    Tight wavelet frames and orthonormal wavelet bases with a general dilation matrix have applications in many areas. In this paper, for any d×d dilation matrix M, we demonstrate in a constructive way that we can construct compactly supported tight M-wavelet frames and orthonormal M-wavelet bases in of exponential decay, which are derived from compactly supported M-refinable functions, such that they can have both arbitrarily high smoothness and any preassigned order of vanishing moments. This paper improves several results in Battle (Comm. Math. Phys. 110 (1987) 601), Bownik (J. Fourier Anal. Appl. 7(2001) 489), Gröchenig and Ron (Proc. Amer. Math. Soc. 126 (1998) 1101), Lemarie (J. Math. Pures Appl. 67 (1988) 227), and Strichartz (Constr. Approx. 9 (1993) 327).

  8. Nanoscale rotary apparatus formed from tight-fitting 3D DNA components

    Science.gov (United States)

    Ketterer, Philip; Willner, Elena M.; Dietz, Hendrik

    2016-01-01

    We report a nanoscale rotary mechanism that reproduces some of the dynamic properties of biological rotary motors in the absence of an energy source, such as random walks on a circle with dwells at docking sites. Our mechanism is built modularly from tight-fitting components that were self-assembled using multilayer DNA origami. The apparatus has greater structural complexity than previous mechanically interlocked objects and features a well-defined angular degree of freedom without restricting the range of rotation. We studied the dynamics of our mechanism using single-particle experiments analogous to those performed previously with actin-labeled adenosine triphosphate synthases. In our mechanism, rotor mobility, the number of docking sites, and the dwell times at these sites may be controlled through rational design. Our prototype thus realizes a working platform toward creating synthetic nanoscale rotary motors. Our methods will support creating other complex nanoscale mechanisms based on tightly fitting, sterically constrained, but mobile, DNA components. PMID:26989778

  9. Fluid identification in tight sandstone reservoirs based on a new rock physics model

    Science.gov (United States)

    Sun, Jianmeng; Wei, Xiaohan; Chen, Xuelian

    2016-08-01

    To identify pore fluids, we establish a new rock physics model named the tight sandstone dual-porosity model based on the Voigt-Reuss-Hill model, approximation for the Xu-White model and Gassmann’s equation to predict elastic wave velocities. The modeling test shows that predicted sonic velocities derived from this rock physics model match well with measured ones from logging data. In this context, elastic moduli can be derived from the model. By numerical study and characteristic analyzation of different elastic properties, a qualitative fluid identification method based on Poisson’s ratio and the S-L dual-factor method based on synthetic moduli is proposed. Case studies of these two new methods show the applicability in distinguishing among different fluids and different layers in tight sandstone reservoirs.

  10. Meralgia paresthetica: a result of tight new trendy low cut trousers ('taille basse').

    Science.gov (United States)

    Moucharafieh, Ramzi; Wehbe, Joseph; Maalouf, Ghassan

    2008-04-01

    Meralgia paresthetica is an entrapment neuropathy involving the lateral femoral cutaneous nerve of the thigh. Patients complain of a persistent burning sensation, tingling and aching pain, and hypersensitivity or hyposensitivity in the anterolateral aspect of the thigh. Numerous direct and indirect causes for the disease have been suggested in the literature. We present 12 cases that were diagnosed to have meralgia paresthetica due to tight new fashion low cut trousers ('taille basse'). The diagnosis was confirmed by injecting a small amount of a short acting local anesthetic around the lateral femoral cutaneous nerve which alleviated the symptoms for several hours. Electrophysiologic studies were sensitive in 83.3% of the cases. All cases were treated successfully using conservative methods, namely avoiding tight trousers, local steroid infiltration and weight reduction.

  11. Empirical tight-binding force model for molecular-dynamics simulation of Si

    Science.gov (United States)

    Wang, C. Z.; Chan, C. T.; Ho, K. M.

    1989-04-01

    A scheme of molecular-dynamics simulation using the empirical tight-binding force model is proposed. The scheme allows the interatomic interactions involved in the molecular dynamics to be determined by first-principles total-energy and electronic-structure calculations without resorting to fitting experimental data. For a first application of the scheme we show that a very simple nearest-neighbor two-center empirical tight-binding force model is able to stabilize the diamond structure of Si within a reasonable temperature range. We also show that the scheme makes possible the quantitative calculation of the temperature dependence of various anharmonic effects such as lattice thermal expansion, temperature-dependent phonon linewidths, and phonon frequency shifts.

  12. Experimental research on the longitudinal field generated by a tightly focused beam

    Institute of Scientific and Technical Information of China (English)

    Zhang Ming-Qian; Wang Jia; Tian Qian

    2013-01-01

    The longitudinal optical field is a peculiar physical phenomenon that is always involved with the domain of near-field optics.Due to its extraordinary properties,it has recently attracted increasing attention in research and application.In this1 work,the longitudinal fields generated by the evanescent illumination of tightly focused,different polarized hollow beams are investigated.The focused light fields are numerically simulated according to vector diffraction theory,and their vector analysis is also carried out.The longitudinal fields on the focal plane are demonstrated experimentally using tip-enhanced scanning near-field microscopy.The simulation and experimental results show that the tightly focused radially polarized beam is suited to generating a stronger and purer longitudinal optical field at the focus.

  13. LIQUIDITY ADJUSTED VALUE AT RISK: INTEGRATING THE UNCERTAINTY IN DEPTH AND TIGHTNESS

    Directory of Open Access Journals (Sweden)

    Levent C. Uslu

    2017-02-01

    Full Text Available Efficient market risk management should also focus on the market liquidity risk, which is generally ignored by the conventional Value at Risk Metrics. We propose two alternative parametric methods to existing studies for the estimation of Liquidity Adjusted Value at Risk (LVaR. The first model is based on the volatility dynamics of VNET (Engle and Lange, 2001 whereas the second model also incorporates the first two moments of the tightness dimension to the latter, as measured by relative weighted bid-ask spreads. Considering a portfolio with different underlying volatility assumptions (EWMA, GARCH-CCC, GARCH-DCC, validation results indicate that both parametric LVaR approaches are strong alternatives to tightness based LVaR models and strictly superior to conventional VaR models, with respect to performance related to regulatory compliance, statistical coverage and overall relative cost of liquidity vs. loss size on violation days.

  14. Efficient collisional blockade loading of single atom into a tight microtrap

    CERN Document Server

    Fung, Y H

    2015-01-01

    We show that controlled inelastic collisions can improve the single atom loading efficiency in the collisional blockade regime of optical microtraps. A collisional loss process where only one of the colliding atoms are lost, implemented during loading, enables us to kick out one of the atoms as soon as a second atom enters the optical microtrap. When this happens faster than the pair loss, which has limited the loading efficiency of previous experiments to about 50%, we experimentally observe an enhancement to 80%. A simple analytical theory predicts the loading dynamics. Our results opens up an efficient and fast route for loading individual atoms into optical tweezers and arrays of microtraps that are too tight for easy implementation of the method reported in [1,2]. The loading of tight traps with single atoms is a requirement for their applications in future experiments in quantum information processing and few-body physics.

  15. Autosomal dominant familial spastic paraplegia: Tight linkage to chromosome 15q

    Energy Technology Data Exchange (ETDEWEB)

    Fink, J.K.; Wu, C.B.; Jones, S.M.; Lesicki, A.; Reinglass, T. [Univ. of Michigan, Ann Arbor, MI (United States); Sharp, G.B.; Lange, B.M. [Arkansas Children`s Hospital, Little Rock, AR (United States); Varvil, T.; Otterud, B.; Leppert, M. [Univ. of Utah, Salt Lake City, UT (United States)

    1995-01-01

    Autosomal dominant, uncomplicated familial spastic paraplegia (FSP) is a genetically heterogeneous disorder characterized by insidiously progressive lower-extremity spasticity. Recently, a locus on chromosome 14q was shown to be tightly linked with the disorder in one of three families. We performed linkage analysis in a kindred with autosomal dominant uncomplicated FSP. After excluding the chromosome 14q locus, we observed tight linkage of the disorder to a group of markers on chromosome 15q (maximum two-point lod score 9.70; {theta} = .05). Our results clearly establish the existence of a locus for autosomal dominant FSP in the centromeric region of chromosome 15q. Comparing clinical and genetic features in FSP families linked to chromosome 14q with those linked to chromosome 15q may provide insight into the pathophysiology of this disorder. 34 refs., 1 fig., 1 tab.

  16. Relaxing Tight Frame Condition in Parallel Proximal Methods for Signal Restoration

    CERN Document Server

    Pustelnik, Nelly; Chaux, Caroline

    2011-01-01

    A fruitful approach for solving signal deconvolution problems consists of resorting to a frame-based convex variational formulation. In this context, parallel proximal algorithms and related alternating direction methods of multipliers have become popular optimization techniques to approximate iteratively the desired solution. Until now, in most of these methods, either Lipschitz differentiability properties or tight frame representations were assumed. In this paper, it is shown that it is possible to relax these assumptions by considering a class of non necessarily tight frame representations, thus offering the possibility of addressing a broader class of signal restoration problems. In particular, it is possible to use non necessarily maximally decimated filter banks with perfect reconstruction, which are common tools in digital signal processing. The proposed approach allows us to solve both frame analysis and frame synthesis problems for various noise distributions. In our simulations, it is applied to th...

  17. Spontaneous resolution of syringomyelia in an adult patient with tight cisterna magna.

    Science.gov (United States)

    Perrini, Paolo

    2012-12-01

    Spontaneous resolution of syringomyelia in adult patients with Chiari malformation is exceptionally rare, with only 10 cases having been reported. A 21-year-old man working as a carpenter presented with a 1-year history of paresthesias in his right arm. A magnetic resonance imaging scan disclosed a cervicothoracic syrinx associated with tight tonsillar impaction of the cisterna magna without herniation. The patient left the carpentry job and underwent close monitoring with serial clinical and neuroradiological controls. The patient's symptoms gradually disappeared and magnetic resonance imaging studies revealed progressive shrinkage of the syrinx despite persistence of crowding of posterior fossa structures at the level of the foramen magnum. This case suggests that spontaneous resolution of syringomyelia can occasionally be triggered by the cessation of daily physical strain in patients with tight cisterna magna. Health care professionals should be aware that strenuous physical activities could affect the natural history of syringomyelia.

  18. Second harmonic generation polarization microscopy with tightly focused linearly and radially polarized beams

    Science.gov (United States)

    Yew, E. Y. S.; Sheppard, C. J. R.

    2007-07-01

    Second harmonic generation microscopy was conducted on rat-tail tendons with linearly and radially polarized beams. Transverse and axial field components were generated in the focal region through tight focusing of linearly and radially polarized. It was found that the generated SHG signals could not be qualitatively explained with a scalar approximation to the electric field at the focus. Only by accounting for the interactions of the axial and transverse components of the electric field interacting through the nonlinear susceptibility χ(2) tensor could the SHG images be explained. For the case of collagen we find that the SHG signal varies as a function of the analyzer angle with a cos2 or sin2 dependency for linearly polarized beams. For tightly focused radially polarized beams we find that the output SHG is radially polarized after collimation and is independent of the analyzer angle.

  19. Sodium caprate transiently opens claudin-5-containing barriers at tight junctions of epithelial and endothelial cells

    DEFF Research Database (Denmark)

    Del Vecchio, Giovanna; Tscheik, Christian; Tenz, Kareen

    2012-01-01

    Claudin-5 is a tight junction (TJ) protein which limits the diffusion of small hydrophilic molecules. Thus, it represents a potential pharmacological target to improve drug delivery to the tissues protected by claudin-5-dependent barriers. Sodium caprate is known as an absorption enhancer which...... opens the paracellular space acting on TJ proteins and actin cytoskeleton. Its action on claudin-5 is not understood so far. Epithelial and endothelial systems were used to evaluate the effect of caprate on claudin-5 in TJ-free cells and on claudin-5 fully integrated in TJ. To this aim, confocal...... of endothelial and epithelial cells. In conclusion, the study further elucidates the cellular effects of caprate at the tight junctions....

  20. Shale Gas and Oil in Germany - Resources and Environmental Impacts

    Science.gov (United States)

    Ladage, Stefan; Blumenberg, Martin; Houben, Georg; Pfunt, Helena; Gestermann, Nicolai; Franke, Dieter; Erbacher, Jochen

    2017-04-01

    In light of the controversial debate on "unconventional" oil and gas resources and the environmental impacts of "fracking", the Federal Institute for Geosciences and Natural Resources (BGR) conducted a comprehensive resource assessment of shale gas and light tight oil in Germany and studied the potential environmental impacts of shale gas development and hydraulic fracturing from a geoscientific perspective. Here, we present our final results (BGR 2016), incorporating the majority of potential shale source rock formations in Germany. Besides shale gas, light tight oil has been assessed. According to our set of criteria - i.e. thermal maturity 0.6-1.2 %vitrinite reflectance (VR; oil) and >1.2 % VR (gas) respectively, organic carbon content > 2%, depth between 500/1000 m and 5000 m as well as a net thickness >20 m - seven potentially generative shale formations were indentified, the most important of them being the Lower Jurassic (Toarcian) Posidonia shale with both shale gas and tight oil potential. The North German basin is by far the most prolific basin. The resource assessment was carried out using a volumetric in-place approach. Variability inherent in the input parameters was accounted for using Monte-Carlo simulations. Technically recoverable resources (TRR) were estimated using recent, production-based recovery factors of North American shale plays and also employing Monte-Carlo simulations. In total, shale gas TRR range between 320 and 2030 bcm and tight oil TRR between 13 and 164 Mio. t in Germany. Tight oil potential is therefore considered minor, whereas the shale gas potential exceeds that of conventional resources by far. Furthermore an overview of numerical transport modelling approaches concerning environmental impacts of the hydraulic fracturing is given. These simulations are based on a representative lithostratigraphy model of the North-German basin, where major shale plays can be expected. Numerical hydrogeological modelling of frac fluid

  1. A new method for constructing infinite families of k-tight optimal double loop networks

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The double loop network (DLN) is a circulant digraph with n nodes and outdegree 2. DLN has been widely used in the designing of local area networks and distributed systems. In this paper, a new method for constructing infinite families of k-tight optimal DLN is presented.method, where the number nk(t,a) of their nodes is a polynomial of degree 2 in t and contains a parameter a. And a conjecture is proposed.

  2. EXPERIMENTAL DESIGN APPLIED TO MODELING OF THE AIR-TIGHTNESS OF A BUILDING

    OpenAIRE

    2015-01-01

    The paper presents experimental designs that can be used in modeling of the air-tightness of buildings as second-order functions using response surface method and corresponding experiment designs. The factors supposed to be significant for a model of building air-tightness—and thus those used in experiment designs—are the heat transfer coefficient for external walls, the heat transfer coefficient of the windows, and the position of the housing units with respect to the building envelope. We c...

  3. Numerical simulation of multi-dimensional NMR response in tight sandstone

    Science.gov (United States)

    Guo, Jiangfeng; Xie, Ranhong; Zou, Youlong; Ding, Yejiao

    2016-06-01

    Conventional logging methods have limitations in the evaluation of tight sandstone reservoirs. The multi-dimensional nuclear magnetic resonance (NMR) logging method has the advantage that it can simultaneously measure transverse relaxation time (T 2), longitudinal relaxation time (T 1) and diffusion coefficient (D). In this paper, we simulate NMR measurements of tight sandstone with different wettability and saturations by the random walk method and obtain the magnetization decays of Carr-Purcell-Meiboom-Gill pulse sequences with different wait times (TW) and echo spacings (TE) under a magnetic field gradient, resulting in D-T 2-T 1 maps by the multiple echo trains joint inversion method. We also study the effects of wettability, saturation, signal-to-noise ratio (SNR) of data and restricted diffusion on the D-T 2-T 1 maps in tight sandstone. The results show that with decreasing wetting fluid saturation, the surface relaxation rate of the wetting fluid gradually increases and the restricted diffusion phenomenon becomes more and more obvious, which leads to the wetting fluid signal moving along the direction of short relaxation and the direction of the diffusion coefficient decreasing in D-T 2-T 1 maps. Meanwhile, the non-wetting fluid position in D-T 2-T 1 maps does not change with saturation variation. With decreasing SNR, the ability to identify water and oil signals based on NMR maps gradually decreases. The wetting fluid D-T 1 and D-T 2 correlations in NMR diffusion-relaxation maps of tight sandstone are obtained through expanding the wetting fluid restricted diffusion models, and are further applied to recognize the wetting fluid in simulated D-T 2 maps and D-T 1 maps.

  4. Tight bounds for the space complexity of nonregular language recognition by real-time machines

    CERN Document Server

    Yakaryilmaz, Abuzer

    2011-01-01

    We examine the minimum amounts of useful memory for real-time, as opposed to one-way, computation using several different machine models. In most cases, we are able to show that the lower bounds established using arguments about one-way machines remain tight in the real-time case. It is shown that increasing the number of stacks of real-time pushdown automata can result in exponential improvement in the total amount of space usage for nonregular language recognition.

  5. Optimal injection scheme for electron acceleration by a tightly focused laser beam

    Institute of Scientific and Technical Information of China (English)

    Chen Min; Sheng Zheng-Ming; Zhang Jie

    2005-01-01

    Electron dynamics and energy gain in a tightly focused laser beam in vacuum are investigated by numerical simulations. There exist two acceleration mechanisms, i.e. acceleration by the longitudinal field or by the transverse field, which corresponds to two different trajectories. The relationship between the energy gain and the injection parameters of electrons, including the injection angle and momentum, is shown. For given laser parameters, the optimum injection parameters can be obtained.

  6. IMMUNE GENETIC ALGORITHM FOR THE PATH PLANNING OF TIGHTLY COORDINATED TWO-ROBOT MANIPULATORS

    Institute of Scientific and Technical Information of China (English)

    Gao Sheng; Zhao Jie; Cai Hegao

    2004-01-01

    A novel algorithm, the immune genetic algorithm based on multi-agent, is proposed for the path planning of tightly coordinated two-robot manipulators, which constructs mainly immune operators accomplished by three steps: defining strategies and methods of multi-agent, calculating virtual forces acting on an agent, and constructing immune operators and performing immunization during the evolutionary process. It is illustrated to be able to restrain the degenerate phenomenon effectively and improve the searching ability with high converging speed.

  7. Outer Membrane Components of the Tad (Tight Adherence) Secreton of Aggregatibacter actinomycetemcomitans▿ †

    OpenAIRE

    Clock, Sarah A.; Paul J Planet; Perez, Brenda A.; Figurski, David H.

    2007-01-01

    Prokaryotic secretion relies on proteins that are widely conserved, including NTPases and secretins, and on proteins that are system specific. The Tad secretion system in Aggregatibacter actinomycetemcomitans is dedicated to the assembly and export of Flp pili, which are needed for tight adherence. Consistent with predictions that RcpA forms the multimeric outer membrane secretion channel (secretin) of the Flp pilus biogenesis apparatus, we observed the RcpA protein in multimers that were sta...

  8. Air tightness of new houses in the U.S.: A preliminary report

    Energy Technology Data Exchange (ETDEWEB)

    Sherman, Max H.; Matson, Nance E.

    2002-03-01

    Most dwellings in the United States are ventilated primarily through leaks in the building shell (i.e., infiltration) rather than by whole-house mechanical ventilation systems. Consequently, quantification of envelope air-tightness is critical to determining how much energy is being lost through infiltration and how much infiltration is contributing toward ventilation requirements. Envelope air tightness and air leakage can be determined from fan pressurization measurements with a blower door. Tens of thousands of unique fan pressurization measurements have been made of U.S. dwellings over the past decades. LBNL has collected the available data on residential infiltration into its Residential Diagnostics Database, with support from the U.S. Department of Energy. This report documents the envelope air leakage section of the LBNL database, with particular emphasis on new construction. The work reported here is an update of similar efforts carried out a decade ago, which used available data largely focused on the housing stock, rather than on new construction. The current effort emphasizes shell tightness measurements made on houses soon after they are built. These newer data come from over two dozen datasets, including over 73,000 measurements spread throughout a majority of the U.S. Roughly one-third of the measurements are for houses identified as energy-efficient through participation in a government or utility program. As a result, the characteristics reported here provide a quantitative estimate of the impact that energy-efficiency programs have on envelope tightness in the US, as well as on trends in construction.

  9. A Tightly Coupled Particle-Fluid Model for DNA-Laden Flows in Complex Microscale Geometries

    Energy Technology Data Exchange (ETDEWEB)

    Trebotich, D; Miller, G H; Colella, P; Graves, D T; Martin, D F; Schwartz, P O

    2004-11-18

    We present a stable and convergent method for the computation of flows of DNA-laden fluids in microchannels with complex geometry. The numerical strategy combines a ball-rod model representation for polymers tightly coupled with a projection method for incompressible viscous flow. We use Cartesian grid embedded boundary methods to discretize the fluid equations in the presence of complex domain boundaries. A sample calculation is presented showing flow through a packed array microchannel in 2D.

  10. Tightly Focusing of Circularly Polarized Vortex Beams through a Uniaxial Birefringent Crystal

    Institute of Scientific and Technical Information of China (English)

    RAO Lian-Zhou; WANG Zong-Chi; ZHENG Xiao-Xia

    2008-01-01

    Under the approximation of small birefringence, the properties of circalarly polarized vortex beams tightly focused through a uniaxial birefringent crystal are studied. With the proper combination of the topological charge and the birefringence, the small focus, the small bottle beam and the inverse c-shaped intensity profile can be obtained.The effects of the focal shift and the Strehl ratio on the birefringence are analysed. A relation between angular momentum (included spin and orbital) and topological Pancharatnam charge is also presented.

  11. S-matrix theory for transmission through billiards in tight-binding approach

    Energy Technology Data Exchange (ETDEWEB)

    Sadreev, Almas F [Kirensky Institute of Physics, 660036, Krasnoyarsk (Russian Federation); Department of Physics and Measurement Technology, Linkoeping University, S-581 83 Linkoeping (Sweden); Rotter, Ingrid [Max-Planck-Institut fuer Physik Komplexer Systeme, D-01187 Dresden (Germany)

    2003-11-14

    In the tight-binding approximation we consider multi-channel transmission through a billiard coupled to leads. Following Dittes we derive the coupling matrix, the scattering matrix and the effective Hamiltonian, but take into account the energy restriction of the conductance band. The complex eigenvalues of the effective Hamiltonian define the poles of the scattering matrix. For some simple cases, we present exact values for the poles. We derive also the condition for the appearance of double poles.

  12. A Tight Linearization Strategy for Zero-One Quadratic Programming Problems

    CERN Document Server

    gharibi, Wajeb

    2012-01-01

    In this paper, we present a new approach to linearizing zero-one quadratic minimization problem which has many applications in computer science and communications. Our algorithm is based on the observation that the quadratic term of zero-one variables has two equivalent piece-wise formulations, convex and concave cases. The convex piece-wise objective function and/or constraints play a great role in deducing small linearization. Further tight strategies are also discussed.

  13. Novel Algorithms in Synchronized Quad-Antenna GNSS and INS Tightly-Coupled Combination

    Science.gov (United States)

    Yu, Chao; Chen, Wen; Dong, Danan; Cao, Jie; Cai, Miaomiao; Wang, Zhiren

    2017-04-01

    In this contribution, several novel algorithms in synchronized quad-antenna GNSS and INS tightly-coupled combination was researched and simulated for high precision positioning and attitude determination. For the sake of improving the performance of positioning and attitude determination in urban canyon, a tightly-coupled combination of synchronized quad-antenna GNSS and INS model is established. The traditional double difference (DD) carrier phase observation model can be substituted by single difference (SD) model. As synchronized quad-antenna means four receiving antennas using a common clock, single difference carrier phase observations are no longer contain receiver clock error, and have better performance than the double difference model in view of observation noise, redundancy and parameter correlations. In the SD model, a novel carrier phase ambiguity resolution algorithm named as ambiguity Substitution Approach (ASA) is proposed. It can reduce the ambiguity search range, and enhance the integer ambiguity fixing efficiency. Due to the advantages of synchronized quad-antenna, the real-time multi-baseline adjustment algorithm for attitude determination is researched. In order to realize the high precision positioning and attitude determination using tightly-coupled combination of quad-antenna synchronized GNSS and INS, a modified adaptive Kalman filter (AKF) with fading factor algorithm is developed to merge the GNSS observables and inertial measurements, and the corresponding filter process is described simultaneously. In the end, a MATLAB simulated application is developed to carry out high precision positioning and attitude determination algorithms using quad-antenna synchronized GNSS/INS combination. The experimental results show that decimeter-level positioning and 0.1 degree per 2 meters baseline attitude determination accuracy can be achieved. Keywords: Synchronized, Quad-antenna, GNSS, INS, Tightly-coupled, Combination, Kalman filter, Adaptive

  14. Evolution of permeability and microstructure of tight carbonates due to numerical simulation of calcite dissolution

    Science.gov (United States)

    Miller, Kevin; Vanorio, Tiziana; Keehm, Youngseuk

    2017-06-01

    The current study concerns fundamental controls on fluid flow in tight carbonate rocks undergoing CO2 injection. Tight carbonates exposed to weak carbonic acid exhibit order of magnitude changes in permeability while maintaining a nearly constant porosity with respect to the porosity of the unreacted sample. This study aims to determine—if not porosity—what are the microstructural changes that control permeability evolution in these rocks? Given the pore-scale nature of chemical reactions, we took a digital rock physics approach. Tight carbonate mudstone was imaged using X-ray microcomputed tomography. We simulated calcite dissolution using a phenomenological numerical model that stands from experimental and microstructural observations under transport-limited reaction conditions. Fluid flow was simulated using the lattice-Boltzmann method, and the pore wall was adaptively eroded at a rate determined by the local surface area and velocity magnitude, which we use in place of solvent flux. We identified preexisting, high-conductivity fluid pathways imprinted in the initial microstructure. Though these pathways comprise a subset of the total connected porosity, they accommodated 80 to 99% of the volumetric flux through the digital sample and localized dissolution. Porosity-permeability evolution exhibited two stages: selective widening of narrow pore throats that comprised preferential pathways and development and widening of channels. We quantitatively monitored attributes of the pore geometry, namely, porosity, specific surface area, tortuosity, and average hydraulic diameter, which we qualitatively linked to permeability. This study gives a pore-scale perspective on the microstructural origins of laboratory permeability-porosity trends of tight carbonates undergoing transport-limited reaction with CO2-rich fluid.

  15. Electrical conductance in a single wall carbon nanotube (SWCNT: tight binding model

    Directory of Open Access Journals (Sweden)

    T Mardaani

    2010-03-01

    Full Text Available In this study, we derive analytically Green’s function (GF formalism to calculate the electrical conductance for an armchair SWCNT in the ballistic regime. We obtain an exact analytical formula for the conductance of the SWCNT, in the tight-binding approach and assuming nearest-neighbor interaction by recursion process in the GF formalism. We show that in the presence of uniform external potential, the number of conductance channels and resonance energy range of the system decrease.

  16. The next big thing : unconventional gas explorers lay technical foundations for shale gas development across Canada

    Energy Technology Data Exchange (ETDEWEB)

    Stonehouse, D.

    2007-12-15

    Canadian exploration companies have successfully developed strategies for economically extracting gas from coal seams and unconventional tight reservoirs. According to Talisman Energy Inc., the next step is to tap into Canada's shale gas resource. In contrast to conventional gas targets, shale gas acts both as a source rock and reservoir rock with the natural gas contained within shale sequences. The gas is stored as adsorbed gas attached to kerogen in the shale, or exists as free gas in pores and fractures. The 2 main types of shale reservoirs include those where the gas was produced thermogenically through high temperatures and those where the gas was produced biogenically through bacterial breakdown. Innovative drilling and stimulation technologies are needed to extract sufficient volumes of gas and to commercially produce either type of shale play. Western Canada is the primary focus for shale gas exploration, mostly in deeper thermogenic shales in northern Alberta and British Columbia. Industry experts are comparing a play in the Fort Nelson area to the prolific Barnett Shale in Texas. Directional drilling and measurement while drilling technology has allowed shale developers in the United States to more accurately hit target prospects and to intersect more of the prospective pay zone. Improved fracturing technology has also allowed developers to improve the permeability of shale reservoirs. This experience will be helpful in Canada, although much experimenting is still required, including microseismic mapping that provides images of the fractures created by hydraulic fracturing. The area for biogenic shale exploration in Canada is in the Colorado Cretaceous Group of shales stretching across central Alberta and Saskatchewan. Stealth Ventures Ltd. and PanTerra Resource Corp. have been testing several technologies to make the shale play economic. Developing the plays will require the appropriate drilling and completion technologies to assess the plays. It

  17. Iliotibial band tightness and patellofemoral pain syndrome: a case-control study.

    Science.gov (United States)

    Hudson, Zoe; Darthuy, Emma

    2009-04-01

    Tight lateral structures have been implicated in subjects presenting with patellofemoral pain syndrome (PFPS). It has been proposed that a tight iliotibial band (ITB) through its attachment of the lateral retinaculum into the patella could cause lateral patella tracking, patella tilt and compression. Twelve subjects presenting with PFPS were compared with 12 matched control subjects. Hip adduction was measured using the Ober test in each subject as an indirect measure of ITB length. The mean values for hip adduction in the control group were 21.4 (+/-4.9) and 20.3 (+/-3.8) degrees in the left and right legs, respectively, and in the PFPS group, 17.3 (+/-6.1) and 14.9 (+/-4.2) degrees in the non-painful leg and painful leg, respectively. One way analysis of variance (ANOVA) revealed a highly significant difference between groups (F=4.485, p=0.008) and post-hoc analysis showed a significant difference between the painful leg in the PFPS group and the left and right legs in the control group, p=0.002 and 0.009, respectively. The results from this study show that subjects presenting with PFPS do have a tighter ITB. Future work should investigate this observation prospectively in order to determine whether a tight ITB is the cause or effect of PFPS.

  18. Tight coupling UFMArcGIS for simulating inundation depth in densely area

    Science.gov (United States)

    Kang, S. H.

    2010-07-01

    The integration of hydrological models and Geographical Information Systems (GIS) usually takes two approaches: loose coupling and tight coupling. This paper presents a tight coupling approach within a GIS environment that is achieved by integrating the urban flood model with the macro language of GIS. Such an approach affords an uncomplicated way to capitalize on the GIS visualization and spatial analysis functions, thereby significantly supporting the dynamic simulation process of hydrological modeling. The tight coupling approach is illustrated by UFMArcGIS (Urban Flood Model with ArcGIS), which is a realization of an urban flood model integrated with the VBA (visual basic of application) language of ArcGIS. Within this model, major stages of model structures are created from the initial parameter input and transformation of datasets, intermediate maps are then visualized, and the results are finally presented in various graphical formats in their geographic context. This approach provides a convenient and single environment in which users can visually interact with the model, e.g. by adjusting parameters while simultaneously observing the corresponding results. This significantly facilitates users in the exploratory data analysis and decision-making stages in terms of the model applications.

  19. Experimental Air-Tightness Analysis in Mediterranean Buildings after Windows Retrofit

    Directory of Open Access Journals (Sweden)

    Francesca Romana d’Ambrosio Alfano

    2016-09-01

    Full Text Available Energy saving and Indoor Air Quality (IAQ in buildings are strongly affected by air leakages. Several studies reveal that the energy loss owing to leaky windows can account for up to 40% of the total building energy demand. Furthermore, at the design stage, the possible infiltration of outdoor air through windows is not taken into account when determining the nominal outdoor airflow rate of the ventilation system. This practice may result in an oversizing of the ventilation system and consequent energy waste. Thus, the air-tightness class of a wall assembly should be assessed for each window component considering the type of material, the presence of the seal, the type of closure, the sealing and the maintenance condition. In this paper, the authors present the experimental results of air-tightness measurements carried out using the fan pressurization method in three residential buildings located in the Mediterranean region before and after a window retrofit. Two different window retrofits were investigated: the application of rubber seals on window frames and the substitution of existing windows with new certified high performance windows. The effectiveness of such retrofits was estimated also in terms of energy saving. Test results demonstrated a high variability of the building air tightness after window retrofits, despite the fact that air tight–certified windows were used.

  20. ACUTE EFFECTS OF DRY NEEDLING ON POSTERIOR SHOULDER TIGHTNESS. A CASE REPORT.

    Science.gov (United States)

    Passigli, Samuele; Plebani, Giuseppe; Poser, Antonio

    2016-04-01

    Posterior shoulder tightness has been associated with numerous shoulder disorders. Methods to increase posterior shoulder mobility may be beneficial. The purpose of this case report is to report the outcomes of a subject with posterior shoulder tightness treated with dry needling as a primary intervention strategy. The subject was a 46-year-old man who was referred to physical therapy with primary symptoms of shoulder pain and loss of motion consistent with subacromial impingement syndrome. Clinical findings upon examination revealed glenohumeral internal rotation and horizontal adduction losses of motion and reproduction of pain symptoms upon palpation of the infraspinatus, teres minor, and posterior deltoid. A single treatment of trigger point dry needling was used to decrease pain and improve range of motion. Following the intervention, clinically meaningful improvements were seen in pain and shoulder range of motion. This case report describes the use of trigger point dry needling in the treatment of a subject with posterior shoulder tightness. The immediate improvement seen in this subject following the dry needling to the infraspinatus, teres minor, and posterior deltoid muscles suggests that muscles may be a significant source of pain and range of motion limitation in this condition. Level 4.

  1. Simulations and measurements of adiabatic annular flows in triangular, tight lattice nuclear fuel bundle model

    Energy Technology Data Exchange (ETDEWEB)

    Saxena, Abhishek, E-mail: asaxena@lke.mavt.ethz.ch [ETH Zurich, Laboratory for Nuclear Energy Systems, Department of Mechanical and Process Engineering, Sonneggstrasse 3, 8092 Zürich (Switzerland); Zboray, Robert [Laboratory for Thermal-hydraulics, Nuclear Energy and Safety Department, Paul Scherrer Institute, 5232 Villigen PSI (Switzerland); Prasser, Horst-Michael [ETH Zurich, Laboratory for Nuclear Energy Systems, Department of Mechanical and Process Engineering, Sonneggstrasse 3, 8092 Zürich (Switzerland); Laboratory for Thermal-hydraulics, Nuclear Energy and Safety Department, Paul Scherrer Institute, 5232 Villigen PSI (Switzerland)

    2016-04-01

    High conversion light water reactors (HCLWR) having triangular, tight-lattice fuels bundles could enable improved fuel utilization compared to present day LWRs. However, the efficient cooling of a tight lattice bundle has to be still proven. Major concern is the avoidance of high-quality boiling crisis (film dry-out) by the use of efficient functional spacers. For this reason, we have carried out experiments on adiabatic, air-water annular two-phase flows in a tight-lattice, triangular fuel bundle model using generic spacers. A high-spatial-resolution, non-intrusive measurement technology, cold neutron tomography, has been utilized to resolve the distribution of the liquid film thickness on the virtual fuel pin surfaces. Unsteady CFD simulations have also been performed to replicate and compare with the experiments using the commercial code STAR-CCM+. Large eddies have been resolved on the grid level to capture the dominant unsteady flow features expected to drive the liquid film thickness distribution downstream of a spacer while the subgrid scales have been modeled using the Wall Adapting Local Eddy (WALE) subgrid model. A Volume of Fluid (VOF) method, which directly tracks the interface and does away with closure relationship models for interfacial exchange terms, has also been employed. The present paper shows first comparison of the measurement with the simulation results.

  2. FY16/Q2 status report on initial dispersion calculations for tight crude oils project

    Energy Technology Data Exchange (ETDEWEB)

    Luketa, Anay [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Rudeen, David Keith [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-04-01

    The objective of this work is to assess dispersion distances of a vapor mixture of species released from a railcar containing a tight crude oil. Tight crude oils can have higher levels of light ends as compared to conventional crude oils [1], which if released and dispersed could pose a potential hazard with regards to a flash fire, explosion, and/or asphyxiation. A historical accident involving rail transport in Viareggio, Italy illustrates how the spillage of LPG can lead to severe damage as a result of a propagating vapor cloud [2]. One of 14 railcars was punctured after derailment, releasing about 110 m3 of LPG into a densely populated area (2000 persons/km2 ). The resulting vapor cloud propagated and infiltrated nearby buildings and houses which were an average of 10 m in height. Ignition of the cloud occurred approximately 100 to 300 seconds after the start of the spill. A flash fire and explosions resulted, killing 31 people. Evidence suggests that most deaths occurred due to the asphyxiation and thermal hazards from the flash fire. Thus, the motivation for this work is to assess if significant vapors can develop from a railcar carrying a tight crude oil and if this cloud could disperse potentially to nearby populations.

  3. Incoherent Dictionary Learning Method Based on Unit Norm Tight Frame and Manifold Optimization for Sparse Representation

    Directory of Open Access Journals (Sweden)

    HongZhong Tang

    2016-01-01

    Full Text Available Optimizing the mutual coherence of a learned dictionary plays an important role in sparse representation and compressed sensing. In this paper, a efficient framework is developed to learn an incoherent dictionary for sparse representation. In particular, the coherence of a previous dictionary (or Gram matrix is reduced sequentially by finding a new dictionary (or Gram matrix, which is closest to the reference unit norm tight frame of the previous dictionary (or Gram matrix. The optimization problem can be solved by restricting the tightness and coherence alternately at each iteration of the algorithm. The significant and different aspect of our proposed framework is that the learned dictionary can approximate an equiangular tight frame. Furthermore, manifold optimization is used to avoid the degeneracy of sparse representation while only reducing the coherence of the learned dictionary. This can be performed after the dictionary update process rather than during the dictionary update process. Experiments on synthetic and real audio data show that our proposed methods give notable improvements in lower coherence, have faster running times, and are extremely robust compared to several existing methods.

  4. GPS/UWB/MEMS-IMU tightly coupled navigation with improved robust Kalman filter

    Science.gov (United States)

    Li, Zengke; Chang, Guobin; Gao, Jingxiang; Wang, Jian; Hernandez, Alberto

    2016-12-01

    The integration of Global Positioning System (GPS) with Inertial Navigation System (INS) has been very intensively developed and widely applied in multiple areas. To further enhance the reliability and availability of GPS/INS integrated navigation in GPS challenging environment, range observation through ultra-wideband (UWB) is introduced in GPS/INS tightly coupled navigation. An improved robust Kalman filter is proposed and used to resist the influence of gross error from UWB observation in GPS/UWB/IMU tightly coupled navigation. The variance of the squared Mahalanobis distance in moving window is calculated, which brings as new judgement factor for gross errors in order to decrease the rate of false outlier identification. A simulation analysis shows that the improved robust Kalman filter is able to correctly identify gross errors and the rate of false judgment as zero. In order to validate the new robust filter, a real experiment is conducted. The results indicate that the improved robust Kalman filter used in GPS/UWB/INS tightly coupled navigation is able to remove the harmful effect of gross error in UWB observation. It clearly illustrates that the improved robust Kalman filter is very effective, and all the simulated small and large gross errors added to UWB distance observation are successfully identified.

  5. Two-Layer Tight Frame Sparsifying Model for Compressed Sensing Magnetic Resonance Imaging

    Science.gov (United States)

    Peng, Xi; Dong, Pei

    2016-01-01

    Compressed sensing magnetic resonance imaging (CSMRI) employs image sparsity to reconstruct MR images from incoherently undersampled K-space data. Existing CSMRI approaches have exploited analysis transform, synthesis dictionary, and their variants to trigger image sparsity. Nevertheless, the accuracy, efficiency, or acceleration rate of existing CSMRI methods can still be improved due to either lack of adaptability, high complexity of the training, or insufficient sparsity promotion. To properly balance the three factors, this paper proposes a two-layer tight frame sparsifying (TRIMS) model for CSMRI by sparsifying the image with a product of a fixed tight frame and an adaptively learned tight frame. The two-layer sparsifying and adaptive learning nature of TRIMS has enabled accurate MR reconstruction from highly undersampled data with efficiency. To solve the reconstruction problem, a three-level Bregman numerical algorithm is developed. The proposed approach has been compared to three state-of-the-art methods over scanned physical phantom and in vivo MR datasets and encouraging performances have been achieved. PMID:27747226

  6. First-order strong-field QED processes in a tightly focused laser beam

    Science.gov (United States)

    Di Piazza, A.

    2017-03-01

    In a previous article [Phys. Rev. Lett. 117, 213201 (2016), 10.1103/PhysRevLett.117.213201] we have determined the angular resolved and the total energy spectrum of a positron produced via nonlinear Breit-Wheeler pair production by a high-energy photon counterpropagating with respect to a tightly focused laser beam. Here, we first generalize the results in that article by including the possibility that the incoming photon is not exactly counterpropagating with respect to the laser field. As main focus of the present paper, we determine the photon angular resolved and total energy spectrum for the related process of nonlinear Compton scattering by an electron impinging into a tightly focused laser beam. Analytical integral expressions are obtained under the realistic assumption that the energy of the incoming electron is the largest dynamical energy of the problem and that the electron is initially almost counterpropagating with respect to the laser field. The crossing symmetry relation between the two processes in a tightly focused laser beam is also elucidated.

  7. The cultural dimension of tightness-looseness: An analysis of situational constraint in Estonia and Greece.

    Science.gov (United States)

    Realo, Anu; Linnamägi, Karmen; Gelfand, Michele J

    2015-06-01

    The importance of tightness-looseness as a dimension that explains a considerable amount of variance between cultures was demonstrated by Gelfand et al. (2011). Tight nations have many strong norms and a low tolerance of deviant behaviour, whereas loose nations have weak social norms and a high tolerance of deviant behaviour. The main aim of the current studies was to examine situational constraint in Estonia and Greece: that is, how the cultural dimension of tightness-looseness is manifested in everyday situations in those two countries. The findings of a questionnaire study (Study 1) suggested that, in general, there is higher constraint across everyday situations in Greece than in Estonia, but situational constraint in Greece is especially strong in school and organisational settings where people have hierarchically structured roles. The results of an observational study (Study 2) revealed a relatively high agreement between appropriateness of certain behaviours as judged by the respondents in Study 1 and the frequencies of observed behaviours in the two countries. Our findings suggest that the strength of situations may substantially vary both within and across cultures, and that the attitudes of the members about situational strength in their respective cultures are in concordance with observations of situations by neutral observers in how people in general behave in their culture. © 2014 International Union of Psychological Science.

  8. 国外致密油勘探开发新进展及其对中国的启示%Advancements in global tight oil exploration and exploitation and the implications for China

    Institute of Scientific and Technical Information of China (English)

    孙张涛; 田黔宁; 吴西顺; 邵明娟

    2015-01-01

    致密油已成为全球非常规油气勘探开发的重要领域之一,正逐渐影响着世界能源供需格局,许多国家都加快了对其勘探开发的进程。本文通过调研世界主要国家致密油勘探开发的最新进展,对全球致密油资源量概况、主要国家致密油勘探开发利用现状、技术研发新进展以及国外致密油开发的相关政策进行了介绍,美国和加拿大是全球主要的致密油生产国,俄罗斯也开始了致密油的商业化生产。这些国家不仅在致密油开发关键技术方面遥遥领先,而且逐步形成了一系列有利于致密油等非常规能源开发的相关政策。鉴于致密油开发对我国的重要战略意义,本文提出了一些思考和建议,以期为中国的致密油勘探开发给予参考。%Tight oil has become one of the significant areas of global unconventional oil and gas exploration and exploitation.Many countries have speeded up the exploration and exploitation of tight oil, since it has gradually affected the energy supply and demand pattern worldwide.Based on investigation and research on the latest developments of tight oil in major countries in the world,this paper presents an overview of the world’s tight oil resources,current exploration and exploitation and progress in technology of major countries,as well as the related policies.The U.S.,Canada and Russia,which are not only in the leading position in technologies innovation but also set up a series of policies on unconventional energy development,have realized the commercial production of tight oil.In view of the strategic significance of tight oil for China,this paper comes up with some suggestions with the aim of giving some reference for tight oil exploration and exploitation in China.

  9. Changes in intestinal tight junction permeability associated with industrial food additives explain the rising incidence of autoimmune disease.

    Science.gov (United States)

    Lerner, Aaron; Matthias, Torsten

    2015-06-01

    The incidence of autoimmune diseases is increasing along with the expansion of industrial food processing and food additive consumption. The intestinal epithelial barrier, with its intercellular tight junction, controls the equilibrium between tolerance and immunity to non-self-antigens. As a result, particular attention is being placed on the role of tight junction dysfunction in the pathogenesis of AD. Tight junction leakage is enhanced by many luminal components, commonly used industrial food additives being some of them. Glucose, salt, emulsifiers, organic solvents, gluten, microbial transglutaminase, and nanoparticles are extensively and increasingly used by the food industry, claim the manufacturers, to improve the qualities of food. However, all of the aforementioned additives increase intestinal permeability by breaching the integrity of tight junction paracellular transfer. In fact, tight junction dysfunction is common in multiple autoimmune diseases and the central part played by the tight junction in autoimmune diseases pathogenesis is extensively described. It is hypothesized that commonly used industrial food additives abrogate human epithelial barrier function, thus, increasing intestinal permeability through the opened tight junction, resulting in entry of foreign immunogenic antigens and activation of the autoimmune cascade. Future research on food additives exposure-intestinal permeability-autoimmunity interplay will enhance our knowledge of the common mechanisms associated with autoimmune progression.

  10. Dėl keleto retų vietovardžių kilmės (Greikónys, Grìkapėdis, Plasapnỹkai, Pušė́nai, Silgiónys, Tauliùkai, Vaĩsodžiai

    Directory of Open Access Journals (Sweden)

    Jonas Palionis

    2011-12-01

    Full Text Available ZUR ENSTEHUNG EINIGER SELTENER ORTSNAMEN (Greikónys, Grìkapėdis, Plasapnỹkai, Pušė́nai, Silgiónys, Tauliùkai, VaĩsodžiaiZusammenfassungIm vorliegenden Artikel werden sieben seltene Dorfnamen aus dem südlitauischen Gebiet behandelt. Die Analyse der Entstehung dieser Ortsnamen stützt sich vorwiegend auf das handschriftliche Material der Tauf- und Trauungsurkunden der zweiten Hälfte des 17. und der ersten Hälfte des 18. Jhs der Gemeinde Punià, die gegenwärtig dem Bezirks Alytùs angehört.Greikónys, die ältere Form ist bereits 1659 in einer Taufurkunde verzeichnet (de Gireykancow; das scheint eine Ableitung von dem Familiennamen *Gireika zu sein. Dieser Name läßt sich mit dem Verb gìrti ‘rühmen, loben’ in Verbindung setzen: *gireika- einer, der eine besondere Neigung sich zu rühmen aufweist, Prahlhans ist.Grìkapėdis ist, ohne Zweifel, ebenfalls anthroponymischen Ursprungs, da der Familienname Grìkpėdis im nordwestlichen Teil von Žemaitija vorkommt. Die Bedeutung der Komponenten dieses zusammengesetzten Familiennamens (grìkas ‘Buchweizen’ + pė́das ‘die Getreidegarbe’ zeigt eine metaphorische Basis der Entstehung des Kompositums. Die gegenwärtige Singularform ist wahrscheinlich eine spätere Bildung: in den Taufurkunden der zweiten Hälfte des 17. Jhs findet man Pluralformen (de Grikopedziow, de Grikiepedzow.Plasapnỹkai, änlich wie Greikonys und Grikapėdis, läßt ebenfalls einen anthroponymischen Ursprung vermuten, obwohl dies nicht so augenscheinlich ist. Dieser Ortsname konnte vom Familiennamen *Plasapnỹkas entstanden sein: *Plasapnỹkas < *plasa +  *upinykas, d. h. ‘ein an dem Fluß Plasãupė Wohnender’. Das erste Glied dieser kontrahierter Zusammensetzung könnte man auf eine Form des Verbs plàsti ‘breiter werden’ zurückführen.Pušė́nai kommt in der zweiten Hälfte des 17. und der ersten Hälfte des 18. Jhs als Puišėnai (de Puyszany vor. Diese ältere Form weist

  11. Identification of MarvelD3 as a tight junction-associated transmembrane protein of the occludin family

    Directory of Open Access Journals (Sweden)

    Balda Maria S

    2009-12-01

    Full Text Available Abstract Background Tight junctions are an intercellular adhesion complex of epithelial and endothelial cells, and form a paracellular barrier that restricts the diffusion of solutes on the basis of size and charge. Tight junctions are formed by multiprotein complexes containing cytosolic and transmembrane proteins. How these components work together to form functional tight junctions is still not well understood and will require a complete understanding of the molecular composition of the junction. Results Here we identify a new transmembrane component of tight junctions: MarvelD3, a four-span transmembrane protein. Its predicted transmembrane helices form a Marvel (MAL and related proteins for vesicle traffic and membrane link domain, a structural motif originally discovered in proteins involved in membrane apposition and fusion events, such as the tight junction proteins occludin and tricellulin. In mammals, MarvelD3 is expressed as two alternatively spliced isoforms. Both isoforms exhibit a broad tissue distribution and are expressed by different types of epithelial as well as endothelial cells. MarvelD3 co-localises with occludin at tight junctions in intestinal and corneal epithelial cells. RNA interference experiments in Caco-2 cells indicate that normal MarvelD3 expression is not required for the formation of functional tight junctions but depletion results in monolayers with increased transepithelial electrical resistance. Conclusions Our data indicate that MarvelD3 is a third member of the tight junction-associated occludin family of transmembrane proteins. Similar to occludin, normal expression of MarvelD3 is not essential for the formation of functional tight junctions. However, MarvelD3 functions as a determinant of epithelial paracellular permeability properties.

  12. Effect of retrograde gas condensate in low permeability natural gas reservoir; Efeito da condensacao retrograda em reservatorios de gas natural com baixa permeabilidade

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Paulo Lee K.C. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Faculdade de Engenharia Mecanica; Ligero, Eliana L.; Schiozer, Denis J. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Faculdade de Engenharia Mecanica. Dept. de Engenharia de Petroleo

    2008-07-01

    Most of Brazilian gas fields are low-permeability or tight sandstone reservoirs and some of them should be gas condensate reservoir. In this type of natural gas reservoir, part of the gaseous hydrocarbon mixture is condensate and the liquid hydrocarbon accumulates near the well bore that causes the loss of productivity. The liquid hydrocarbon formation inside the reservoir should be well understood such as the knowledge of the variables that causes the condensate formation and its importance in the natural gas production. This work had as goal to better understanding the effect of condensate accumulation near a producer well. The influence of the porosity and the absolute permeability in the gas production was studied in three distinct gas reservoirs: a dry gas reservoir and two gas condensate reservoirs. The refinement of the simulation grid near the producer well was also investigated. The choice of simulation model was shown to be very important in the simulation of gas condensate reservoirs. The porosity was the little relevance in the gas production and in the liquid hydrocarbon formation; otherwise the permeability was very relevant. (author)

  13. Gas sensor

    Science.gov (United States)

    Schmid, Andreas K.; Mascaraque, Arantzazu; Santos, Benito; de la Figuera, Juan

    2014-09-09

    A gas sensor is described which incorporates a sensor stack comprising a first film layer of a ferromagnetic material, a spacer layer, and a second film layer of the ferromagnetic material. The first film layer is fabricated so that it exhibits a dependence of its magnetic anisotropy direction on the presence of a gas, That is, the orientation of the easy axis of magnetization will flip from out-of-plane to in-plane when the gas to be detected is present in sufficient concentration. By monitoring the change in resistance of the sensor stack when the orientation of the first layer's magnetization changes, and correlating that change with temperature one can determine both the identity and relative concentration of the detected gas. In one embodiment the stack sensor comprises a top ferromagnetic layer two mono layers thick of cobalt deposited upon a spacer layer of ruthenium, which in turn has a second layer of cobalt disposed on its other side, this second cobalt layer in contact with a programmable heater chip.

  14. Effect of chemistry and turbulence on NO formation in oxygen-natural gas flames

    Science.gov (United States)

    Samaniego, J. -M.; Egolfopoulos, F. N.; Bowman, C. T.

    1996-01-01

    The effects of chemistry and turbulence on NO formation in oxygen-natural turbulent diffusion flames gas flames have been investigated. The chemistry of nitric oxides has been studied numerically in the counterflow configuration. Systematic calculations with the GRI 2.11 mechanism for combustion of methane and NO chemistry were conducted to provide a base case. It was shown that the 'simple' Zeldovich mechanism accounts for more than 75% of N2 consumption in the flame in a range of strain-rates varying between 10 and 1000 s-l. The main shortcomings of this mechanism are: 1) overestimation (15%) of the NO production rate at low strain-rates because it does not capture the reburn due to the hydrocarbon chemistry, and 2) underestimation (25%) of the NO production rate at high strainrates because it ignores NO production through the prompt mechanism. Reburn through the Zeldovich mechanism alone proves to be significant at low strain-rates. A one-step model based on the Zeldovich mechanism and including reburn has been developed. It shows good agreement with the GRI mechanism at low strain-rates but underestimates significantly N2 consumption (about 50%) at high strain-rates. The role of turbulence has been assessed by using an existing 3-D DNS data base of a diffusion flame in decaying turbulence. Two PDF closure models used in practical industrial codes for turbulent NO formation have been tested. A simpler version of the global one-step chemical scheme for NO compared to that developed in this study was used to test the closure assumptions of the PDF models, because the data base could not provide all the necessary ingredients. Despite this simplification, it was possible to demonstrate that the current PDF models for NO overestimate significantly the NO production rate due to the fact that they neglect the correlations between the fluctuations in oxygen concentration and temperature. A single scalar PDF model for temperature that accounts for such correlations based

  15. Hydraulic fracturing to enhance geothermal energy recovery in deep and tight formations. Modell approach in petrothermy research project OPTIRISS

    Energy Technology Data Exchange (ETDEWEB)

    Rafiee, M.M.; Schmitz, S.; Barsch, M. [DBI - Gastechnologisches Institut gGmbH, Freiberg (Germany)

    2013-08-01

    In Germany numerous projects were successfully conducted in developments of geothermal energy which applied so far mostly for the hydrothermal deposit type. In Thuringia and Saxony there are currently project developments of geothermal resource taking into account for deep, tight formations in petrothermy and Enhanced geothermal system, (EGS). One of the potential tasks in generating these petrothermal producers and in the design of the underground power plant appears to be hydraulic fracturing with multi frac method. This is to create the heat exchanger surfaces in the rock and ensure maximum volumetric flow through it. Therefore it is very important for a sustainable heat production. However the promise of its adequate conductivity in the deep formation is one of the dominant contests in geothermal energy industry. In a multi frac method, two wells (normally horizontal wellbores at different depths) are drilled in direction of minimum horizontal stress of the formation rock. By multiple frac operation in separate sections, flow paths are generated between the wells through which it is possible to extract the heat from the rock. The numerical simulation of hydraulic fracture propagation processes in the rock is mainly from the research in the area of oil and gas industry. These techniques are mainly used for very low permeable formations in petroleum engineering (e.g. Shale gas). The development is at the beginning for EGS (e.g. granites). In this work single and multi fracking propagation processes in a synthetic example of deep hard formation are investigated. The numerical simulation is carried out to design and characterize frac processes and frac dimensions. Sensitivities to various rock parameters and different process designs are examined and optimum criteria are concluded. This shows that the minimum stress profile has the most effective role and should be modelled properly. The analysis indicates the optimum fracture length and height for adequate thermal

  16. Laser spectroscopy of gas confined in nanoporous materials

    CERN Document Server

    Svensson, Tomas

    2009-01-01

    We show that high-resolution laser spectroscopy can probe surface interactions of gas confined in nano-cavities of porous materials. We report on strong line broadening and unfamiliar lineshapes due to tight confinement, as well as signal enhancement due to multiple photon scattering. This new domain of laser spectroscopy constitute a challenge for the theory of collisions and spectroscopic lineshapes, and open for new ways of analyzing porous materials and processes taking place therein.

  17. Vacuum Tight Threaded Junctions (VTTJ): A new solution for reliable heterogeneous junctions in ITER

    Energy Technology Data Exchange (ETDEWEB)

    Agostinetti, P., E-mail: piero.agostinetti@igi.cnr.it; Palma, M. Dalla; Agostini, F. Degli; Marcuzzi, D.; Rizzolo, A.; Rossetto, F.; Sonato, P.; Zaccaria, P.

    2015-10-15

    Highlights: • Heterogeneous junctions represent a critical issue in Nuclear Fusion experiments. • We have developed a new technique for heterogeneous junctions, called VTTJ, whose main advantages are low cost, high reliability and easiness of construction. • The VTTJ junctions have passed all the tests required by ITER for the heterogeneous junctions of the divertor. • Further tests have demonstrated wide margins for operation (up to 700 °C and 500 bar). - Abstract: A new technique, called Vacuum Tight Threaded Junction (VTTJ), has been developed and patented by Consorzio RFX, permitting to obtain low-cost and reliable non-welded junctions, able to maintain vacuum tightness also in heavy loading conditions (high temperature and high mechanical loads). The technique can be applied also if the materials to be joint are not weldable and for heterogeneous junctions (for example, between steel and copper) and has been tested up to 500 bar internal pressure and up to 700 °C, showing excellent leak tightness in vacuum conditions and high mechanical resistance. The main advantages with respect to existing technologies (for example, friction welding and electron beam welding) are an easy construction, a low cost, a precise positioning of the junction and a high repeatability of the process. Due to these advantages, the new technique has been adopted for several components of the SPIDER experiment and it is proposed for ITER, in particular for the ITER Heat and Current Drive Neutral Beam Injector and for its prototype, the MITICA experiment, to be tested at Consorzio RFX. This paper gives a detailed description of the VTTJ technique, of the samples manufactured and of the qualification tests that have been carried out so far.

  18. Universal tight binding model for chemical reactions in solution and at surfaces. I. Organic molecules

    Science.gov (United States)

    Sheppard, T. J.; Lozovoi, A. Y.; Pashov, D. L.; Kohanoff, J. J.; Paxton, A. T.

    2014-07-01

    As is now well established, a first order expansion of the Hohenberg-Kohn total energy density functional about a trial input density, namely, the Harris-Foulkes functional, can be used to rationalize a non self consistent tight binding model. If the expansion is taken to second order then the energy and electron density matrix need to be calculated self consistently and from this functional one can derive a charge self consistent tight binding theory. In this paper we have used this to describe a polarizable ion tight binding model which has the benefit of treating charge transfer in point multipoles. This admits a ready description of ionic polarizability and crystal field splitting. It is necessary in constructing such a model to find a number of parameters that mimic their more exact counterparts in the density functional theory. We describe in detail how this is done using a combination of intuition, exact analytical fitting, and a genetic optimization algorithm. Having obtained model parameters we show that this constitutes a transferable scheme that can be applied rather universally to small and medium sized organic molecules. We have shown that the model gives a good account of static structural and dynamic vibrational properties of a library of molecules, and finally we demonstrate the model's capability by showing a real time simulation of an enolization reaction in aqueous solution. In two subsequent papers, we show that the model is a great deal more general in that it will describe solvents and solid substrates and that therefore we have created a self consistent quantum mechanical scheme that may be applied to simulations in heterogeneous catalysis.

  19. Universal tight binding model for chemical reactions in solution and at surfaces. I. Organic molecules

    Energy Technology Data Exchange (ETDEWEB)

    Sheppard, T. J.; Lozovoi, A. Y.; Kohanoff, J. J. [Atomistic Simulation Centre, School of Mathematics and Physics, Queen' s University Belfast, Belfast BT7 1NN, Northern Ireland (United Kingdom); Pashov, D. L.; Paxton, A. T., E-mail: Tony.Paxton@KCL.ac.uk [Department of Physics, King' s College London, Strand, London WC2R 2LS (United Kingdom)

    2014-07-28

    As is now well established, a first order expansion of the Hohenberg–Kohn total energy density functional about a trial input density, namely, the Harris–Foulkes functional, can be used to rationalize a non self consistent tight binding model. If the expansion is taken to second order then the energy and electron density matrix need to be calculated self consistently and from this functional one can derive a charge self consistent tight binding theory. In this paper we have used this to describe a polarizable ion tight binding model which has the benefit of treating charge transfer in point multipoles. This admits a ready description of ionic polarizability and crystal field splitting. It is necessary in constructing such a model to find a number of parameters that mimic their more exact counterparts in the density functional theory. We describe in detail how this is done using a combination of intuition, exact analytical fitting, and a genetic optimization algorithm. Having obtained model parameters we show that this constitutes a transferable scheme that can be applied rather universally to small and medium sized organic molecules. We have shown that the model gives a good account of static structural and dynamic vibrational properties of a library of molecules, and finally we demonstrate the model's capability by showing a real time simulation of an enolization reaction in aqueous solution. In two subsequent papers, we show that the model is a great deal more general in that it will describe solvents and solid substrates and that therefore we have created a self consistent quantum mechanical scheme that may be applied to simulations in heterogeneous catalysis.

  20. Differences in regulation of tight junctions and cell morphology between VHL mutations from disease subtypes

    Directory of Open Access Journals (Sweden)

    Isanova Bella

    2009-07-01

    Full Text Available Abstract Background In von Hippel-Lindau (VHL disease, germline mutations in the VHL tumor suppressor gene cause clear cell renal carcinomas, hemangioblastomas, and pheochromocytomas. The VHL gene product is part of an ubiquitin E3 ligase complex and hypoxia-inducible factor alpha (HIF-α is a key substrate, although additional VHL functions have been described. A genotype-phenotype relationship exists in VHL disease such that specific VHL mutations elicit certain subsets of these tumors. Here, we examine VHL genotype-phenotype correlations at the cellular level, focusing on the regulation of tight junctions and cell morphology. Methods Wild-type and various mutant VHL proteins representing VHL disease subtypes were stably expressed in 3 VHL-negative renal carcinoma cell lines. Using these cell lines, the roles of various VHL-associated cellular functions in regulation of cell morphology were investigated. Results As a whole, type 1 mutants varied greatly from type 2 mutants, demonstrating high levels of HIF-2α, cyclin D1 and α5 integrin, lower p27 levels, and a spindly, fibroblastic cellular appearance. Type 2 mutations demonstrated an epithelial morphology similar to wild-type VHL in the majority of the renal cell lines used. Knockdown of p27 in cells with wild-type VHL led to perturbations of both epithelial morphology and ZO-1 localization to tight junctions. ZO-1 localization correlated well with VHL disease subtypes, with greater mislocalization observed for genotypes associated with a higher risk of renal carcinoma. HIF-2α knockdown in 786-O partially restored ZO-1 localization, but did not restore an epithelial morphology. Conclusion VHL has both HIF-α dependent and HIF-α independent functions in regulating tight junctions and cell morphology that likely impact the clinical phenotypes seen in VHL disease.

  1. Effect of splinting and interproximal contact tightness on load transfer by implant restorations.

    Science.gov (United States)

    Guichet, David L; Yoshinobu, Diane; Caputo, Angelo A

    2002-05-01

    To circumvent the difficulty of achieving a passive framework fit, some authors have suggested that multiple adjacent implants be restored individually. This protocol requires that each unit be able to withstand mastication forces. Non-splinted restorations have numerous interproximal contacts that require adjustments prior to placement, with an unknown outcome relative to load transfer. This in vitro simulation study examined the effect of splinting and interproximal contact tightness on passivity of fit and the load transfer characteristics of implant restorations. A photoelastic model of a human partially edentulous left mandible with 3 screw-type implants (3.75 x 10 mm) was fabricated. For non-splinted restorations, individual crowns were fabricated on 3 custom-milled titanium abutments. After the units were cemented, 5 levels of interproximal contact tightness were evaluated: open, ideal (8 microm shim stock drags without tearing), light (ideal +10 microm), medium (ideal + 50 microm), and heavy (ideal + 90 microm). For splinted restorations, five 3-unit fixed partial dentures were fabricated, internally adjusted with silicone disclosing material, and cemented to the model. Changes in stress distribution under simulated non-loaded and loaded conditions (6.8 kg) were analyzed with a polariscope. In the simulated alveolar structures, non-splinted restorations with heavier interproximal contacts were associated with increased tensile stresses between implants; occlusal loads tended to concentrate around the specific loaded implant. Splinted restorations shared the occlusal loads and distributed the stresses more evenly between the implants when force was applied. The load-sharing effect was most evident on the center implant but also was seen on the terminal abutments of the splinted restorations. The results of this in vitro study suggest that excessive contact tightness between individual crowns can lead to a non-passive situation. In this experiment, splinted

  2. From deep basin gas to diagenetic trap-An example from the Yulin Gas Field in the Ordos Basin

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In the updip portion of the Yulin Gas Field in the Ordos Basin, there are no any structural, stratigraphic and sedimentary lithologic seals. Using thin-section petrography, ultraviolet fluorescence microscopy, micro-thermometry and Raman microspectrometry, this paper finds out the diagenetic trap and studies the diagenetic history of this field. It was revealed that three phases of diagenesis and hydrocarbon charging happened in late Triassic, late Jurassic and the end of early Cretaceous respectively. In the first two phases, acid geofluid entered the reservoir and caused dissolution and cementation. Although the porosities had been increased, further compaction accompanying re-subsidence resulted in tight sandstone and conglomerates. Till the end of the early Cretaceous, bulk of gas migrated into the tight reservoir. Cementation, however, kept on in the updip portion of this field due to low gas saturation and formed the diagenetic trap. The mechanism for gas accumulation was changed from deep basin gas to diagenetic trap, which offers a sealing condition that can retain gas for much longer time.

  3. Is Alberta`s gas running out?

    Energy Technology Data Exchange (ETDEWEB)

    Koch, G.

    1995-09-18

    The state of Alberta`s natural gas resources were reviewed and according to certain groups of experts reserves and resources were found to be less plentiful than generally believed. The Canadian Association of Petroleum Producers (CAPP) also reported that gas reserves in non-frontier areas declined by 1.8% lat year, to 67.4 trillion cubic feet. It was estimated that this supply would last for 13 years. The National Energy Board (NEB) indicated that thousands of Alberta`s unconnected pools may not be economical to develop. The CAPP annual reserves report also indicated that average gas pools found in recent times were only one quarter of the size of gas pools found before 1980. It was argued by this same group of experts that low gas prices, particularly for Alberta exports, have made drilling uneconomical, while others maintained that price fluctuations must be accepted as part of selling a commodity that is marketed world-wide. Ed Wolf, an independent geologist, estimated that gas prices,factoring in environmental costs, should be increased to $4 per mcf to justify exporting Canadian natural gas. However, others have argued that reserve figures have been underestimated. As proof of that they point to the fact that there is no shortage of investment capital; exploration and production activities, funded by investment, would not continue if natural gas production were not cost-effective. The Ziff Energy Group estimated that discovered and frontier reserves total 426 tcf, or 65 years` supply, excluding tight gas from low porosity formations which have been estimated to provide up to 300 years of supply at current levels of demand. As well, new technologies have improved the industry`s ability to find new reserves. The debate between economic nationalists and free marketeers continues.

  4. Natural Gas Transport

    OpenAIRE

    Tomás Correa; Nelson Osorio

    2009-01-01

    This paper reviews the present and future on natural gas transportation options, from oil and gas fields to markets, including liquefied natural gas, gas pipeline, compressed natural gas, natural gas hydrates, and gas to liquids and the perspectives of using them in Colombia, since this is the main fuel alternative to supply the world in at least the next 50 years.

  5. Natural Gas Transport

    Directory of Open Access Journals (Sweden)

    Tomás Correa

    2009-06-01

    Full Text Available This paper reviews the present and future on natural gas transportation options, from oil and gas fields to markets, including liquefied natural gas, gas pipeline, compressed natural gas, natural gas hydrates, and gas to liquids and the perspectives of using them in Colombia, since this is the main fuel alternative to supply the world in at least the next 50 years.

  6. OVERCOMING THE METER BARRIER AND THE FORMATION OF SYSTEMS WITH TIGHTLY PACKED INNER PLANETS (STIPs)

    Energy Technology Data Exchange (ETDEWEB)

    Boley, A. C. [Department of Physics and Astronomy, The University of British Columbia, 6224 Agricultural Road, Vancouver, B.C. V6T 1Z1 (Canada); Morris, M. A. [Center for Meteorite Studies, Arizona State University, P.O. Box 876004, Tempe, AZ 88287-6004 (United States); Ford, E. B. [Center for Exoplanets and Habitable Worlds, The Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States)

    2014-09-10

    We present a solution to the long outstanding meter barrier problem in planet formation theory. As solids spiral inward due to aerodynamic drag, they will enter disk regions that are characterized by high temperatures, densities, and pressures. High partial pressures of rock vapor can suppress solid evaporation, and promote collisions between partially molten solids, allowing rapid growth. This process should be ubiquitous in planet-forming disks, which may be evidenced by the abundant class of Systems with Tightly packed Inner Planets discovered by the NASA Kepler Mission.

  7. Quantum confinement in perovskite oxide heterostructures: Tight binding instead of a nearly free electron picture

    OpenAIRE

    Zhong, Zhicheng; Zhang, Qinfang; Held, Karsten

    2013-01-01

    Most recently, orbital-selective quantum well states of $d$ electrons have been experimentally observed in SrVO$_3$ ultrathin films [K. Yoshimatsu et. al., Science 333, 319 (2011)] and SrTiO$_3$ surfaces [A. F. Santander-Syro et. al., Nature 469, 189 (2011)]. Hitherto, one tries to explain these experiments by a nearly free electron (NFE) model, an approach widely used for delocalized electrons in semiconductor heterostructures and simple metal films. We show that a tight binding (TB) model i...

  8. Very Tight Coupling between LTE and WiFi: a Practical Analysis

    OpenAIRE

    KHADRAOUI, Younes; Lagrange, Xavier; Gravey, Annie

    2016-01-01

    International audience; The use of the large number of deployed WiFi access points is an interesting solution to offload LTE networks. In the perspective of convergence between fixed and mobile access, it is possible to connect WiFi access points to eNodeBs. With very tight coupling, WiFi and LTE flows are merged just below the IP layer. The objective is to accelerate the process of attachment to a WiFi Access Point and to allow dual WiFi/LTE transmission while providing a seamless experience...

  9. Molecular definition of red cell Rh haplotypes by tightly linked SphI RFLPs.

    OpenAIRE

    Huang, C. H.; Reid, M.E.; Chen, Y.; Coghlan, G.; Okubo, Y

    1996-01-01

    The Rh blood group system of human red cells contains five major antigens D, C/c, and E/e (the latter four designated "non-D") that are specified by eight gene complexes known as Rh haplotypes. In this paper, we report on the mapping of RH locus and identification of a set of SphI RFLPs that are tightly linked with the Rh structural genes. Using exon-specific probes, we have localized the SphI cleavage sites resulting in these DNA markers and derived a comprehensive map for the RH locus. It w...

  10. Scattering of a Tightly Focused Beam by an Optically Trapped Particle

    Science.gov (United States)

    Lock, James A.; Wrbanek, Susan Y.; Weiland, Kenneth E.

    2006-01-01

    Near-forward scattering of an optically trapped 5 m radius polystyrene latex sphere by the trapping beam was examined both theoretically and experimentally. Since the trapping beam is tightly focused, the beam fields superpose and interfere with the scattered fields in the forward hemisphere. The observed light intensity consists of a series of concentric bright and dark fringes centered about the forward scattering direction. Both the number of fringes and their contrast depend on the position of the trapping beam focal waist with respect to the sphere. The fringes are caused by diffraction due to the truncation of the tail of the trapping beam as the beam is transmitted through the sphere.

  11. A Poincar\\'e-Birkhoff theorem for tight Reeb flows on $S^3$

    CERN Document Server

    Hryniewicz, Umberto; Salomão, Pedro A S

    2011-01-01

    We consider Reeb flows on the tight 3-sphere admitting a pair of closed orbits forming a Hopf link. If the rotation numbers of the transverse linearized dynamics at these orbits fail to satisfy a certain resonance condition then there exist infinitely many periodic trajectories distinguished by their linking numbers with the components of the link. This result admits a natural comparison to the Poincar\\'e-Birkhoff theorem on area-preserving annulus homeomorphisms. An analogous theorem holds on SO(3) and applies to geodesic flows of Finsler metrics on $S^2$.

  12. Vibrationally resolved UV/Vis spectroscopy with time-dependent density functional based tight binding

    CERN Document Server

    Rüger, Robert; van Lenthe, Erik; Heine, Thomas; Visscher, Lucas

    2016-01-01

    We report a time-dependent density functional based tight-binding (TD-DFTB) scheme for the calculation of UV/Vis spectra, explicitly taking into account the excitation of nuclear vibrations via the harmonic approximation. The theory of vibrationally resolved UV/Vis spectroscopy is first summarized from the viewpoint of TD-DFTB. The method is benchmarked against time-dependent density functional theory (TD-DFT) calculations for strongly dipole allowed excitations in various aromatic and polar molecules. Using the recent 3ob:freq parameter set of Elstner's group, excellent agreement with TD-DFT calculations using local functionals was achieved.

  13. Tight Bounds for Beacon-Based Coverage in Simple Rectilinear Polygons

    KAUST Repository

    Bae, Sang Won

    2016-03-21

    We establish tight bounds for beacon-based coverage problems. In particular, we show that $$\\\\lfloor \\\\frac{n}{6} \\ floor $$⌊n6⌋ beacons are always sufficient and sometimes necessary to cover a simple rectilinear polygon P with n vertices. When P is monotone and rectilinear, we prove that this bound becomes $$\\\\lfloor \\\\frac{n+4}{8} \\ floor $$⌊n+48⌋. We also present an optimal linear-time algorithm for computing the beacon kernel of P.

  14. Tight bound on coherent-state-based entanglement generation over lossy channels

    CERN Document Server

    Azuma, Koji; Koashi, Masato; Imoto, Nobuyuki

    2009-01-01

    The first stage of the hybrid quantum repeaters is entanglement generation based on transmission of pulses in coherent states over a lossy channel. Protocols to make entanglement with only one type of error are favorable for rendering subsequent entanglement distillation efficient. Here we provide the tight upper bound on performances of these protocols that is determined only by the channel loss. In addition, we show that this bound is achievable by utilizing a proposed protocol [arXiv:0811.3100] composed of a simple combination of linear optical elements and photon-number-resolving detectors.

  15. Costa Rica During the Global Recession: Fiscal Stimulus with Tight Monetary Policy

    OpenAIRE

    Jose Antonio Cordero

    2009-01-01

    This paper shows that, in spite of a reasonably sized fiscal stimulus package, Costa Rica’s economy continues on a downward path, partly because fiscal policy is being offset by a tightening of monetary policy. The paper notes that the International Monetary Fund has insisted that Costa Rica’s monetary policy remain tight due to worries over inflation targets and a perceived risk of a balance of payments crisis. However, the author notes that the IMF could help prevent a balance of payments c...

  16. Tight Results on Multiregister Fourier Sampling: Quantum Measurements for Graph Isomorphism Require Entanglement

    CERN Document Server

    Moore, Cristopher; Moore, Cristopher; Russell, Alexander

    2005-01-01

    We establish a general method for proving bounds on the information that can be extracted via arbitrary entangled measurements on tensor products of hidden subgroup coset states. When applied to the symmetric group, the method yields an Omega(n log n) lower bound on the number of coset states over which we must perform an entangled measurement in order to obtain non-negligible information about a hidden involution. These results are tight to within a multiplicative constant and apply, in particular, to the case relevant for the Graph Isomorphism problem. Part of our proof was obtained after learning from Hallgren, Roetteler, and Sen that they had obtained similar results.

  17. Plasmonic resonance scattering from silver nanowire illuminated by tightly focused singular beam.

    Science.gov (United States)

    Normatov, Alexander; Spektor, Boris; Leviatan, Yehuda; Shamir, Joseph

    2010-08-15

    We investigate scattering features of tightly focused singular beams by placing a cylindrical nanowire in the vicinity of a line phase singularity. Applying an illumination wavelength corresponding to silver cylinder plasmonic resonance, we compare the scattering response with that of a perfect conductor. The rigorous modeling employs a 2D version of the Richards-Wolf focusing method and the source model technique. It is found that a cylinder with a plasmonic resonance produces a strong scattering response by deflecting the power flow toward the optical singularity region, where otherwise the power approaches zero.

  18. Primordial magnetic fields from second-order cosmological perturbations:Tight coupling approximation

    CERN Document Server

    Maeda, Satoshi; Kobayashi, Tsutomu; Shiromizu, Tetsuya

    2008-01-01

    We explore the possibility of generating large-scale magnetic fields from second-order cosmological perturbations during the pre-recombination era. The key process for this is Thomson scattering between the photons and the charged particles within the cosmic plasma. To tame the multi-component interacting fluid system, we employ the tight coupling approximation. It is shown that the source term for the magnetic field is given by the product of the first order perturbations and so the intrinsically second-order quantities do not contribute to magnetogenesis. The magnetic fields generated by this process are estimated to be \\sim 10^{-26},Gauss on the horizon scale.

  19. Physics counterpart of the PT non-hermitian tight-binding chain

    CERN Document Server

    Jin, L

    2010-01-01

    We explore an alternative way of finding the link between a PT non-Hermitian Hamiltonian and a Hermitian one. Based on the analysis of the scattering problem for an imaginary potential and its time reversal process, it is shown that any real-energy eigenstate of a PT tight-binding lattice with on-site imaginary potentials shares the same wave function with a resonant transmission state of the corresponding Hermitian lattice embedded in a chain. It indicates that the PT eigenstate of a PT non-Hermitian Hamiltonian has connection to the resonance transmission state of the extended Hermitian Hamiltonian.

  20. Tightness of the recentered maximum of the two-dimensional discrete Gaussian Free Field

    CERN Document Server

    Bramson, Maury

    2010-01-01

    We consider the maximum of the discrete two dimensional Gaussian free field (GFF) in a box, and prove that its maximum, centered at its mean, is tight, settling a long-standing conjecture. The proof combines a recent observation of Bolthausen, Deuschel and Zeitouni with elements from (Bramson 1978) and comparison theorems for Gaussian fields. An essential part of the argument is the precise evaluation, up to an error of order 1, of the expected value of the maximum of the GFF in a box. Related Gaussian fields, such as the GFF on a two-dimensional torus, are also discussed.