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Sample records for ultra-low permeability reservoir

  1. Environmental response nanosilica for reducing the pressure of water injection in ultra-low permeability reservoirs

    Science.gov (United States)

    Liu, Peisong; Niu, Liyong; Li, Xiaohong; Zhang, Zhijun

    2017-12-01

    The super-hydrophobic silica nanoparticles are applied to alter the wettability of rock surface from water-wet to oil-wet. The aim of this is to reduce injection pressure so as to enhance water injection efficiency in low permeability reservoirs. Therefore, a new type of environmentally responsive nanosilica (denote as ERS) is modified with organic compound containing hydrophobic groups and "pinning" groups by covalent bond and then covered with a layer of hydrophilic organic compound by chemical adsorption to achieve excellent water dispersibility. Resultant ERS is homogeneously dispersed in water with a size of about 4-8 nm like a micro-emulsion system and can be easily injected into the macro or nano channels of ultra-low permeability reservoirs. The hydrophobic nanosilica core can be released from the aqueous delivery system owing to its strong dependence on the environmental variation from normal condition to injection wells (such as pH and salinity). Then the exposed silica nanoparticles form a thin layer on the surface of narrow pore throat, leading to the wettability from water-wet to oil-wet. More importantly, the two rock cores with different permeability were surface treated with ERS dispersion with a concentration of 2 g/L, exhibit great reduce of water injection pressure by 57.4 and 39.6%, respectively, which shows great potential for exploitation of crude oil from ultra-low permeability reservoirs during water flooding. [Figure not available: see fulltext.

  2. Influence of Fracture Width on Sealability in High-Strength and Ultra-Low-Permeability Concrete in Seawater

    OpenAIRE

    Fukuda, Daisuke; Nara, Yoshitaka; Hayashi, Daisuke; Ogawa, Hideo; Kaneko, Katsuhiko

    2013-01-01

    For cementitious composites and materials, the sealing of fractures can occur in water by the precipitation of calcium compounds. In this study, the sealing behavior in a macro-fractured high-strength and ultra-low-permeability concrete (HSULPC) specimen was investigated in simulated seawater using micro-focus X-ray computed tomography (CT). In particular, the influence of fracture width (0.10 and 0.25 mm) on fracture sealing was investigated. Precipitation occurred mainly at the outermost pa...

  3. Influence of Fracture Width on Sealability in High-Strength and Ultra-Low-Permeability Concrete in Seawater

    Directory of Open Access Journals (Sweden)

    Katsuhiko Kaneko

    2013-06-01

    Full Text Available For cementitious composites and materials, the sealing of fractures can occur in water by the precipitation of calcium compounds. In this study, the sealing behavior in a macro-fractured high-strength and ultra-low-permeability concrete (HSULPC specimen was investigated in simulated seawater using micro-focus X-ray computed tomography (CT. In particular, the influence of fracture width (0.10 and 0.25 mm on fracture sealing was investigated. Precipitation occurred mainly at the outermost parts of the fractured surface of the specimen for both fracture widths. While significant sealing was observed for the fracture width of 0.10 mm, sealing was not attained for the fracture width of 0.25 mm within the observation period (49 days. Examination of the sealed regions on the macro-fracture was performed using a three-dimensional image registration technique and applying image subtraction between the CT images of the HSULPC specimen before and after maintaining the specimen in simulated seawater. The temporal change of the sealing deposits for the fracture width of 0.10 mm was much larger than that for the fracture width of 0.25 mm. Therefore, it is concluded that the sealability of the fracture in the HSULPC is affected by the fracture width.

  4. Influence of Fracture Width on Sealability in High-Strength and Ultra-Low-Permeability Concrete in Seawater.

    Science.gov (United States)

    Fukuda, Daisuke; Nara, Yoshitaka; Hayashi, Daisuke; Ogawa, Hideo; Kaneko, Katsuhiko

    2013-06-25

    For cementitious composites and materials, the sealing of fractures can occur in water by the precipitation of calcium compounds. In this study, the sealing behavior in a macro-fractured high-strength and ultra-low-permeability concrete (HSULPC) specimen was investigated in simulated seawater using micro-focus X-ray computed tomography (CT). In particular, the influence of fracture width (0.10 and 0.25 mm) on fracture sealing was investigated. Precipitation occurred mainly at the outermost parts of the fractured surface of the specimen for both fracture widths. While significant sealing was observed for the fracture width of 0.10 mm, sealing was not attained for the fracture width of 0.25 mm within the observation period (49 days). Examination of the sealed regions on the macro-fracture was performed using a three-dimensional image registration technique and applying image subtraction between the CT images of the HSULPC specimen before and after maintaining the specimen in simulated seawater. The temporal change of the sealing deposits for the fracture width of 0.10 mm was much larger than that for the fracture width of 0.25 mm. Therefore, it is concluded that the sealability of the fracture in the HSULPC is affected by the fracture width.

  5. Advantageous Reservoir Characterization Technology in Extra Low Permeability Oil Reservoirs

    Directory of Open Access Journals (Sweden)

    Yutian Luo

    2017-01-01

    Full Text Available This paper took extra low permeability reservoirs in Dagang Liujianfang Oilfield as an example and analyzed different types of microscopic pore structures by SEM, casting thin sections fluorescence microscope, and so on. With adoption of rate-controlled mercury penetration, NMR, and some other advanced techniques, based on evaluation parameters, namely, throat radius, volume percentage of mobile fluid, start-up pressure gradient, and clay content, the classification and assessment method of extra low permeability reservoirs was improved and the parameter boundaries of the advantageous reservoirs were established. The physical properties of reservoirs with different depth are different. Clay mineral variation range is 7.0%, and throat radius variation range is 1.81 μm, and start pressure gradient range is 0.23 MPa/m, and movable fluid percentage change range is 17.4%. The class IV reservoirs account for 9.56%, class II reservoirs account for 12.16%, and class III reservoirs account for 78.29%. According to the comparison of different development methods, class II reservoir is most suitable for waterflooding development, and class IV reservoir is most suitable for gas injection development. Taking into account the gas injection in the upper section of the reservoir, the next section of water injection development will achieve the best results.

  6. Diagenetic effect on permeabilities of geothermal sandstone reservoirs

    DEFF Research Database (Denmark)

    Weibel, Rikke; Olivarius, Mette; Kristensen, Lars

    The Danish subsurface contains abundant sedimentary deposits, which can be utilized for geothermal heating. The Upper Triassic – Lower Jurassic continental-marine sandstones of the Gassum Formation has been utilised as a geothermal reservoir for the Thisted Geothermal Plant since 1984 extracting...... and permeability is caused by increased diagenetic changes of the sandstones due to increased burial depth and temperatures. Therefore, the highest water temperatures typically correspond with the lowest porosities and permeabilities. Especially the permeability is crucial for the performance of the geothermal......-line fractures. Continuous thin chlorite coatings results in less porosity- and permeability-reduction with burial than the general reduction with burial, unless carbonate cemented. Therefore, localities of sandstones characterized by these continuous chlorite coatings may represent fine geothermal reservoirs...

  7. Upscaling verticle permeability within a fluvio-aeolian reservoir

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, S.D.; Corbett, P.W.M.; Jensen, J.L. [Heriot-Watt Univ., Edinburgh (United Kingdom)

    1997-08-01

    Vertical permeability (k{sub v}) is a crucial factor in many reservoir engineering issues. To date there has been little work undertaken to understand the wide variation of k{sub v} values measured at different scales in the reservoir. This paper presents the results of a study in which we have modelled the results of a downhole well tester using a statistical model and high resolution permeability data. The work has demonstrates and quantifies a wide variation in k{sub v} at smaller, near wellbore scales and has implications for k{sub v} modelling at larger scales.

  8. Prediction of Hydrocarbon Reservoirs Permeability Using Support Vector Machine

    Directory of Open Access Journals (Sweden)

    R. Gholami

    2012-01-01

    Full Text Available Permeability is a key parameter associated with the characterization of any hydrocarbon reservoir. In fact, it is not possible to have accurate solutions to many petroleum engineering problems without having accurate permeability value. The conventional methods for permeability determination are core analysis and well test techniques. These methods are very expensive and time consuming. Therefore, attempts have usually been carried out to use artificial neural network for identification of the relationship between the well log data and core permeability. In this way, recent works on artificial intelligence techniques have led to introduce a robust machine learning methodology called support vector machine. This paper aims to utilize the SVM for predicting the permeability of three gas wells in the Southern Pars field. Obtained results of SVM showed that the correlation coefficient between core and predicted permeability is 0.97 for testing dataset. Comparing the result of SVM with that of a general regression neural network (GRNN revealed that the SVM approach is faster and more accurate than the GRNN in prediction of hydrocarbon reservoirs permeability.

  9. Thermoporoelastic effects during heat extraction from low-permeability reservoirs

    DEFF Research Database (Denmark)

    Salimzadeh, Saeed; Nick, Hamidreza M.; Zimmerman, R. W.

    2018-01-01

    Thermoporoelastic effects during heat extraction from low permeability geothermal reservoirs are investigated numerically, based on the model of a horizontal penny-shaped fracture intersected by an injection well and a production well. A coupled formulation for thermo-hydraulic (TH) processes...... in EGS projects. Therefore, using the undrained thermal expansion coefficient for the matrix may overestimate the volumetric strain of the rock in low-permeability enhanced geothermal systems, whereas using a drained thermal expansion coefficient for the matrix may underestimate the volumetric strain...

  10. The Researches on Reasonable Well Spacing of Gas Wells in Deep and low Permeability Gas Reservoirs

    Science.gov (United States)

    Bei, Yu Bei; Hui, Li; Lin, Li Dong

    2018-06-01

    This Gs64 gas reservoir is a condensate gas reservoir which is relatively integrated with low porosity and low permeability found in Dagang Oilfield in recent years. The condensate content is as high as 610g/m3. At present, there are few reports about the well spacing of similar gas reservoirs at home and abroad. Therefore, determining the reasonable well spacing of the gas reservoir is important for ensuring the optimal development effect and economic benefit of the gas field development. This paper discusses the reasonable well spacing of the deep and low permeability gas reservoir from the aspects of percolation mechanics, gas reservoir engineering and numerical simulation. considering there exist the start-up pressure gradient in percolation process of low permeability gas reservoir, this paper combined with productivity equation under starting pressure gradient, established the formula of gas well spacing with the formation pressure and start-up pressure gradient. The calculation formula of starting pressure gradient and well spacing of gas wells. Adopting various methods to calculate values of gas reservoir spacing are close to well testing' radius, so the calculation method is reliable, which is very important for the determination of reasonable well spacing in low permeability gas reservoirs.

  11. Compositional simulations of producing oil-gas ratio behaviour in low permeable gas condensate reservoir

    OpenAIRE

    Gundersen, Pål Lee

    2013-01-01

    Master's thesis in Petroleum engineering Gas condensate flow behaviour below the dew point in low permeable formations can make accurate fluid sampling a difficult challenge. The objective of this study was to investigate the producing oil-gas ratio behaviour in the infinite-acting period for a low permeable gas condensate reservoir. Compositional isothermal flow simulations were performed using a single-layer, radial and two-dimensional, gas condensate reservoir model with low permeabili...

  12. Ultra Low Concentration Adsorption Equilibria

    National Research Council Canada - National Science Library

    Mahle, John J; Buettner, Leonard C; LeVan, M. D; Schindler, Bryan J

    2006-01-01

    .... Specifically this work focuses on novel experimental and modeling methods to characterize and predict at ultra-low chemical vapor concentrations the protection afforded by adsorption-based vapor filtration systems...

  13. Reservoir rock permeability prediction using support vector regression in an Iranian oil field

    International Nuclear Information System (INIS)

    Saffarzadeh, Sadegh; Shadizadeh, Seyed Reza

    2012-01-01

    Reservoir permeability is a critical parameter for the evaluation of hydrocarbon reservoirs. It is often measured in the laboratory from reservoir core samples or evaluated from well test data. The prediction of reservoir rock permeability utilizing well log data is important because the core analysis and well test data are usually only available from a few wells in a field and have high coring and laboratory analysis costs. Since most wells are logged, the common practice is to estimate permeability from logs using correlation equations developed from limited core data; however, these correlation formulae are not universally applicable. Recently, support vector machines (SVMs) have been proposed as a new intelligence technique for both regression and classification tasks. The theory has a strong mathematical foundation for dependence estimation and predictive learning from finite data sets. The ultimate test for any technique that bears the claim of permeability prediction from well log data is the accurate and verifiable prediction of permeability for wells where only the well log data are available. The main goal of this paper is to develop the SVM method to obtain reservoir rock permeability based on well log data. (paper)

  14. Xenon NMR measurements of permeability and tortuosity in reservoir rocks.

    Science.gov (United States)

    Wang, Ruopeng; Pavlin, Tina; Rosen, Matthew Scott; Mair, Ross William; Cory, David G; Walsworth, Ronald Lee

    2005-02-01

    In this work we present measurements of permeability, effective porosity and tortuosity on a variety of rock samples using NMR/MRI of thermal and laser-polarized gas. Permeability and effective porosity are measured simultaneously using MRI to monitor the inflow of laser-polarized xenon into the rock core. Tortuosity is determined from measurements of the time-dependent diffusion coefficient using thermal xenon in sealed samples. The initial results from a limited number of rocks indicate inverse correlations between tortuosity and both effective porosity and permeability. Further studies to widen the number of types of rocks studied may eventually aid in explaining the poorly understood connection between permeability and tortuosity of rock cores.

  15. Forecast on Water Locking Damage of Low Permeable Reservoir with Quantum Neural Network

    Science.gov (United States)

    Zhao, Jingyuan; Sun, Yuxue; Feng, Fuping; Zhao, Fulei; Sui, Dianjie; Xu, Jianjun

    2018-01-01

    It is of great importance in oil-gas reservoir protection to timely and correctly forecast the water locking damage, the greatest damage for low permeable reservoir. An analysis is conducted on the production mechanism and various influence factors of water locking damage, based on which a quantum neuron is constructed based on the information processing manner of a biological neuron and the principle of quantum neural algorithm, besides, the quantum neural network model forecasting the water locking of the reservoir is established and related software is also made to forecast the water locking damage of the gas reservoir. This method has overcome the defects of grey correlation analysis that requires evaluation matrix analysis and complicated operation. According to the practice in Longxi Area of Daqing Oilfield, this method is characterized by fast operation, few system parameters and high accuracy rate (the general incidence rate may reach 90%), which can provide reliable support for the protection technique of low permeable reservoir.

  16. Integrated petrophysical and reservoir characterization workflow to enhance permeability and water saturation prediction

    Science.gov (United States)

    Al-Amri, Meshal; Mahmoud, Mohamed; Elkatatny, Salaheldin; Al-Yousef, Hasan; Al-Ghamdi, Tariq

    2017-07-01

    Accurate estimation of permeability is essential in reservoir characterization and in determining fluid flow in porous media which greatly assists optimize the production of a field. Some of the permeability prediction techniques such as Porosity-Permeability transforms and recently artificial intelligence and neural networks are encouraging but still show moderate to good match to core data. This could be due to limitation to homogenous media while the knowledge about geology and heterogeneity is indirectly related or absent. The use of geological information from core description as in Lithofacies which includes digenetic information show a link to permeability when categorized into rock types exposed to similar depositional environment. The objective of this paper is to develop a robust combined workflow integrating geology and petrophysics and wireline logs in an extremely heterogeneous carbonate reservoir to accurately predict permeability. Permeability prediction is carried out using pattern recognition algorithm called multi-resolution graph-based clustering (MRGC). We will bench mark the prediction results with hard data from core and well test analysis. As a result, we showed how much better improvements are achieved in the permeability prediction when geology is integrated within the analysis. Finally, we use the predicted permeability as an input parameter in J-function and correct for uncertainties in saturation calculation produced by wireline logs using the classical Archie equation. Eventually, high level of confidence in hydrocarbon volumes estimation is reached when robust permeability and saturation height functions are estimated in presence of important geological details that are petrophysically meaningful.

  17. Modeling Permeability Alteration in Diatomite Reservoirs During Steam Drive, SUPRI TR-113

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, Suniti Kumar; Kovscek, Anthony R.

    1999-08-09

    There is an estimated 10 billion barrels of original oil in place (OOIP) in diatomaceous reservoirs in Kern County, California. These reservoirs have low permeability ranging from 0.1 to 10 mD. Injection pressure controlled steam drive has been found to be an effective way to recover oil from these reservoir. However, steam drive in these reservoirs has its own complications. The rock matrix is primarily silica (SiO2). It is a known fact that silica is soluble in hot water and its solubility varies with temperature and pH. Due to this fact, the rock matrix in diatomite may dissolve into the aqueous phase as the temperature at a location increases or it may precipitate from the aqueous phase onto the rock grains as the temperature decreases. Thus, during steam drive silica redistribution will occur in the reservoir along with oil recovery. This silica redistribution causes the permeability and porosity of the reservoir to change. Understanding and quantifying these silica redistribution effects on the reservoir permeability might prove to be a key aspect of designing a steam drive project in these formations.

  18. Permeability Estimation of Rock Reservoir Based on PCA and Elman Neural Networks

    Science.gov (United States)

    Shi, Ying; Jian, Shaoyong

    2018-03-01

    an intelligent method which based on fuzzy neural networks with PCA algorithm, is proposed to estimate the permeability of rock reservoir. First, the dimensionality reduction process is utilized for these parameters by principal component analysis method. Further, the mapping relationship between rock slice characteristic parameters and permeability had been found through fuzzy neural networks. The estimation validity and reliability for this method were tested with practical data from Yan’an region in Ordos Basin. The result showed that the average relative errors of permeability estimation for this method is 6.25%, and this method had the better convergence speed and more accuracy than other. Therefore, by using the cheap rock slice related information, the permeability of rock reservoir can be estimated efficiently and accurately, and it is of high reliability, practicability and application prospect.

  19. Upscaling of permeability heterogeneities in reservoir rocks; an integrated approach

    NARCIS (Netherlands)

    Mikes, D.

    2002-01-01

    This thesis presents a hierarchical and geologically constrained deterministic approach to incorporate small-scale heterogeneities into reservoir flow simulators. We use a hierarchical structure to encompass all scales from laminae to an entire depositional system. For the geological models under

  20. Low permeability Neogene lithofacies in Northern Croatia as potential unconventional hydrocarbon reservoirs

    Science.gov (United States)

    Malvić, Tomislav; Sučić, Antonija; Cvetković, Marko; Resanović, Filip; Velić, Josipa

    2014-06-01

    We present two examples of describing low permeability Neogene clastic lithofacies to outline unconventional hydrocarbon lithofacies. Both examples were selected from the Drava Depression, the largest macrostructure of the Pannonian Basin System located in Croatia. The first example is the Beničanci Field, the largest Croatian hydrocarbon reservoir discovered in Badenian coarse-grained clastics that consists mostly of breccia. The definition of low permeability lithofacies is related to the margins of the existing reservoir, where the reservoir lithology changed into a transitional one, which is mainly depicted by the marlitic sandstones. However, calculation of the POS (probability of success of new hydrocarbons) shows critical geological categories where probabilities are lower than those in the viable reservoir with proven reserves. Potential new hydrocarbon volumes are located in the structural margins, along the oil-water contact, with a POS of 9.375%. These potential reserves in those areas can be classified as probable. A second example was the Cremušina Structure, where a hydrocarbon reservoir was not proven, but where the entire structure has been transferred onto regional migration pathways. The Lower Pontian lithology is described from well logs as fine-grained sandstones with large sections of silty or marly clastics. As a result, the average porosity is low for conventional reservoir classification (10.57%). However, it is still an interesting case for consideration as a potentially unconventional reservoir, such as the "tight" sandstones.

  1. Permeability estimation from NMR diffusion measurements in reservoir rocks.

    Science.gov (United States)

    Balzarini, M; Brancolini, A; Gossenberg, P

    1998-01-01

    It is well known that in restricted geometries, such as in porous media, the apparent diffusion coefficient (D) of the fluid depends on the observation time. From the time dependence of D, interesting information can be derived to characterise geometrical features of the porous media that are relevant in oil industry applications. In particular, the permeability can be related to the surface-to-volume ratio (S/V), estimated from the short time behaviour of D(t), and to the connectivity of the pore space, which is probed by the long time behaviour of D(t). The stimulated spin-echo pulse sequence, with pulsed magnetic field gradients, has been used to measure the diffusion coefficients on various homogeneous and heterogeneous sandstone samples. It is shown that the petrophysical parameters obtained by our measurements are in good agreement with those yielded by conventional laboratory techniques (gas permeability and electrical conductivity). Although the diffusing time is limited by T1, eventually preventing an observation of the real asymptotic behaviour, and the surface-to-volume ratio measured by nuclear magnetic resonance is different from the value obtained by BET because of the different length scales probed, the measurement remains reliable and low-time consuming.

  2. New well pattern optimization methodology in mature low-permeability anisotropic reservoirs

    Science.gov (United States)

    Qin, Jiazheng; Liu, Yuetian; Feng, Yueli; Ding, Yao; Liu, Liu; He, Youwei

    2018-02-01

    In China, lots of well patterns were designed before people knew the principal permeability direction in low-permeability anisotropic reservoirs. After several years’ production, it turns out that well line direction is unparallel with principal permeability direction. However, traditional well location optimization methods (in terms of the objective function such as net present value and/or ultimate recovery) are inapplicable, since wells are not free to move around in a mature oilfield. Thus, the well pattern optimization (WPO) of mature low-permeability anisotropic reservoirs is a significant but challenging task, since the original well pattern (WP) will be distorted and reconstructed due to permeability anisotropy. In this paper, we investigate the destruction and reconstruction of WP when the principal permeability direction and well line direction are unparallel. A new methodology was developed to quantitatively optimize the well locations of mature large-scale WP through a WPO algorithm on the basis of coordinate transformation (i.e. rotating and stretching). For a mature oilfield, large-scale WP has settled, so it is not economically viable to carry out further infill drilling. This paper circumvents this difficulty by combining the WPO algorithm with the well status (open or shut-in) and schedule adjustment. Finally, this methodology is applied to an example. Cumulative oil production rates of the optimized WP are higher, and water-cut is lower, which highlights the potential of the WPO methodology application in mature large-scale field development projects.

  3. Oil recovery enhancement from fractured, low permeability reservoirs. [Carbonated Water

    Energy Technology Data Exchange (ETDEWEB)

    Poston, S.W.

    1991-01-01

    The results of the investigative efforts for this jointly funded DOE-State of Texas research project achieved during the 1990-1991 year may be summarized as follows: Geological Characterization - Detailed maps of the development and hierarchical nature the fracture system exhibited by Austin Chalk outcrops were prepared. The results of these efforts were directly applied to the development of production decline type curves applicable to a dual-fracture-matrix flow system. Analysis of production records obtained from Austin Chalk operators illustrated the utility of these type curves to determine relative fracture/matrix contributions and extent. Well-log response in Austin Chalk wells has been shown to be a reliable indicator of organic maturity. Shear-wave splitting concepts were used to estimate fracture orientations from Vertical Seismic Profile, VSP data. Several programs were written to facilitate analysis of the data. The results of these efforts indicated fractures could be detected with VSP seismic methods.Development of the EOR Imbibition Process - Laboratory displacement as well as Magnetic Resonance Imaging, MRI and Computed Tomography, CT imaging studies have shown the carbonated water-imbibition displacement process significantly accelerates and increases recovery from oil saturated, low permeability rocks.Field Tests - Two operators amenable to conducting a carbonated water flood test on an Austin Chalk well have been identified. Feasibility studies are presently underway.

  4. Oil Recovery Enhancement from Fractured, Low Permeability Reservoirs. [Carbonated Water

    Science.gov (United States)

    Poston, S. W.

    1991-01-01

    The results of the investigative efforts for this jointly funded DOE-State of Texas research project achieved during the 1990-1991 year may be summarized as follows: Geological Characterization - Detailed maps of the development and hierarchical nature the fracture system exhibited by Austin Chalk outcrops were prepared. The results of these efforts were directly applied to the development of production decline type curves applicable to a dual-fracture-matrix flow system. Analysis of production records obtained from Austin Chalk operators illustrated the utility of these type curves to determine relative fracture/matrix contributions and extent. Well-log response in Austin Chalk wells has been shown to be a reliable indicator of organic maturity. Shear-wave splitting concepts were used to estimate fracture orientations from Vertical Seismic Profile, VSP data. Several programs were written to facilitate analysis of the data. The results of these efforts indicated fractures could be detected with VSP seismic methods. Development of the EOR Imbibition Process - Laboratory displacement as well as Magnetic Resonance Imaging, MRI and Computed Tomography, CT imaging studies have shown the carbonated water-imbibition displacement process significantly accelerates and increases recovery from oil saturated, low permeability rocks. Field Tests - Two operators amenable to conducting a carbonated water flood test on an Austin Chalk well have been identified. Feasibility studies are presently underway.

  5. An improved method for permeability estimation of the bioclastic limestone reservoir based on NMR data.

    Science.gov (United States)

    Ge, Xinmin; Fan, Yiren; Liu, Jianyu; Zhang, Li; Han, Yujiao; Xing, Donghui

    2017-10-01

    Permeability is an important parameter in formation evaluation since it controls the fluid transportation of porous rocks. However, it is challengeable to compute the permeability of bioclastic limestone reservoirs by conventional methods linking petrophysical and geophysical data, due to the complex pore distributions. A new method is presented to estimate the permeability based on laboratory and downhole nuclear magnetic resonance (NMR) measurements. We divide the pore space into four intervals by the inflection points between the pore radius and the transversal relaxation time. Relationships between permeability and percentages of different pore intervals are investigated to investigate influential factors on the fluid transportation. Furthermore, an empirical model, which takes into account of the pore size distributions, is presented to compute the permeability. 212 core samples in our case show that the accuracy of permeability calculation is improved from 0.542 (SDR model), 0.507 (TIM model), 0.455 (conventional porosity-permeability regressions) to 0.803. To enhance the precision of downhole application of the new model, we developed a fluid correction algorithm to construct the water spectrum of in-situ NMR data, aiming to eliminate the influence of oil on the magnetization. The result reveals that permeability is positively correlated with percentages of mega-pores and macro-pores, but negatively correlated with the percentage of micro-pores. Poor correlation is observed between permeability and the percentage of meso-pores. NMR magnetizations and T 2 spectrums after the fluid correction agree well with laboratory results for samples saturated with water. Field application indicates that the improved method provides better performance than conventional models such as Schlumberger-Doll Research equation, Timur-Coates equation, and porosity-permeability regressions. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. An improved method for permeability estimation of the bioclastic limestone reservoir based on NMR data

    Science.gov (United States)

    Ge, Xinmin; Fan, Yiren; Liu, Jianyu; Zhang, Li; Han, Yujiao; Xing, Donghui

    2017-10-01

    Permeability is an important parameter in formation evaluation since it controls the fluid transportation of porous rocks. However, it is challengeable to compute the permeability of bioclastic limestone reservoirs by conventional methods linking petrophysical and geophysical data, due to the complex pore distributions. A new method is presented to estimate the permeability based on laboratory and downhole nuclear magnetic resonance (NMR) measurements. We divide the pore space into four intervals by the inflection points between the pore radius and the transversal relaxation time. Relationships between permeability and percentages of different pore intervals are investigated to investigate influential factors on the fluid transportation. Furthermore, an empirical model, which takes into account of the pore size distributions, is presented to compute the permeability. 212 core samples in our case show that the accuracy of permeability calculation is improved from 0.542 (SDR model), 0.507 (TIM model), 0.455 (conventional porosity-permeability regressions) to 0.803. To enhance the precision of downhole application of the new model, we developed a fluid correction algorithm to construct the water spectrum of in-situ NMR data, aiming to eliminate the influence of oil on the magnetization. The result reveals that permeability is positively correlated with percentages of mega-pores and macro-pores, but negatively correlated with the percentage of micro-pores. Poor correlation is observed between permeability and the percentage of meso-pores. NMR magnetizations and T2 spectrums after the fluid correction agree well with laboratory results for samples saturated with water. Field application indicates that the improved method provides better performance than conventional models such as Schlumberger-Doll Research equation, Timur-Coates equation, and porosity-permeability regressions.

  7. The Hybrid of Classification Tree and Extreme Learning Machine for Permeability Prediction in Oil Reservoir

    KAUST Repository

    Prasetyo Utomo, Chandra

    2011-06-01

    Permeability is an important parameter connected with oil reservoir. Predicting the permeability could save millions of dollars. Unfortunately, petroleum engineers have faced numerous challenges arriving at cost-efficient predictions. Much work has been carried out to solve this problem. The main challenge is to handle the high range of permeability in each reservoir. For about a hundred year, mathematicians and engineers have tried to deliver best prediction models. However, none of them have produced satisfying results. In the last two decades, artificial intelligence models have been used. The current best prediction model in permeability prediction is extreme learning machine (ELM). It produces fairly good results but a clear explanation of the model is hard to come by because it is so complex. The aim of this research is to propose a way out of this complexity through the design of a hybrid intelligent model. In this proposal, the system combines classification and regression models to predict the permeability value. These are based on the well logs data. In order to handle the high range of the permeability value, a classification tree is utilized. A benefit of this innovation is that the tree represents knowledge in a clear and succinct fashion and thereby avoids the complexity of all previous models. Finally, it is important to note that the ELM is used as a final predictor. Results demonstrate that this proposed hybrid model performs better when compared with support vector machines (SVM) and ELM in term of correlation coefficient. Moreover, the classification tree model potentially leads to better communication among petroleum engineers concerning this important process and has wider implications for oil reservoir management efficiency.

  8. Mapping the Fluid Pathways and Permeability Barriers of a Large Gas Hydrate Reservoir

    Science.gov (United States)

    Campbell, A.; Zhang, Y. L.; Sun, L. F.; Saleh, R.; Pun, W.; Bellefleur, G.; Milkereit, B.

    2012-12-01

    An understanding of the relationship between the physical properties of gas hydrate saturated sedimentary basins aids in the detection, exploration and monitoring one of the world's upcoming energy resources. A large gas hydrate reservoir is located in the MacKenzie Delta of the Canadian Arctic and geophysical logs from the Mallik test site are available for the gas hydrate stability zone (GHSZ) between depths of approximately 850 m to 1100 m. The geophysical data sets from two neighboring boreholes at the Mallik test site are analyzed. Commonly used porosity logs, as well as nuclear magnetic resonance, compressional and Stoneley wave velocity dispersion logs are used to map zones of elevated and severely reduced porosity and permeability respectively. The lateral continuity of horizontal permeability barriers can be further understood with the aid of surface seismic modeling studies. In this integrated study, the behavior of compressional and Stoneley wave velocity dispersion and surface seismic modeling studies are used to identify the fluid pathways and permeability barriers of the gas hydrate reservoir. The results are compared with known nuclear magnetic resonance-derived permeability values. The aim of investigating this heterogeneous medium is to map the fluid pathways and the associated permeability barriers throughout the gas hydrate stability zone. This provides a framework for an understanding of the long-term dissociation of gas hydrates along vertical and horizontal pathways, and will improve the knowledge pertaining to the production of such a promising energy source.

  9. Mixed Finite Element Simulation with Stability Analysis for Gas Transport in Low-Permeability Reservoirs

    Directory of Open Access Journals (Sweden)

    Mohamed F. El-Amin

    2018-01-01

    Full Text Available Natural gas exists in considerable quantities in tight reservoirs. Tight formations are rocks with very tiny or poorly connected pors that make flow through them very difficult, i.e., the permeability is very low. The mixed finite element method (MFEM, which is locally conservative, is suitable to simulate the flow in porous media. This paper is devoted to developing a mixed finite element (MFE technique to simulate the gas transport in low permeability reservoirs. The mathematical model, which describes gas transport in low permeability formations, contains slippage effect, as well as adsorption and diffusion mechanisms. The apparent permeability is employed to represent the slippage effect in low-permeability formations. The gas adsorption on the pore surface has been described by Langmuir isotherm model, while the Peng-Robinson equation of state is used in the thermodynamic calculations. Important compatibility conditions must hold to guarantee the stability of the mixed method by adding additional constraints to the numerical discretization. The stability conditions of the MFE scheme has been provided. A theorem and three lemmas on the stability analysis of the mixed finite element method (MFEM have been established and proven. A semi-implicit scheme is developed to solve the governing equations. Numerical experiments are carried out under various values of the physical parameters.

  10. Validating predictions of evolving porosity and permeability in carbonate reservoir rocks exposed to CO2-brine

    Science.gov (United States)

    Smith, M. M.; Hao, Y.; Carroll, S.

    2017-12-01

    Improving our ability to better forecast the extent and impact of changes in porosity and permeability due to CO2-brine-carbonate reservoir interactions should lower uncertainty in long-term geologic CO2 storage capacity estimates. We have developed a continuum-scale reactive transport model that simulates spatial and temporal changes to porosity, permeability, mineralogy, and fluid composition within carbonate rocks exposed to CO2 and brine at storage reservoir conditions. The model relies on two primary parameters to simulate brine-CO2-carbonate mineral reaction: kinetic rate constant(s), kmineral, for carbonate dissolution; and an exponential parameter, n, relating porosity change to resulting permeability. Experimental data collected from fifteen core-flooding experiments conducted on samples from the Weyburn (Saskatchewan, Canada) and Arbuckle (Kansas, USA) carbonate reservoirs were used to calibrate the reactive-transport model and constrain the useful range of k and n values. Here we present the results of our current efforts to validate this model and the use of these parameter values, by comparing predictions of extent and location of dissolution and the evolution of fluid permeability against our results from new core-flood experiments conducted on samples from the Duperow Formation (Montana, USA). Agreement between model predictions and experimental data increase our confidence that these parameter ranges need not be considered site-specific but may be applied (within reason) at various locations and reservoirs. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  11. Microbial mineral illization of montmorillonite in low-permeability oil reservoirs for microbial enhanced oil recovery.

    Science.gov (United States)

    Cui, Kai; Sun, Shanshan; Xiao, Meng; Liu, Tongjing; Xu, Quanshu; Dong, Honghong; Wang, Di; Gong, Yejing; Sha, Te; Hou, Jirui; Zhang, Zhongzhi; Fu, Pengcheng

    2018-05-11

    Microbial mineral illization has been investigated for its role in the extraction and recovery of metals from ores. Here we report our application of mineral bioillization for the microbial enhanced oil recovery in low-permeability oil reservoirs. It aimed to reveal the etching mechanism of the four Fe (III)-reducing microbial strains under anaerobic growth conditions on the Ca-montmorillonite. The mineralogical characterization of the Ca-montmorillonite was performed by Fourier transform infrared spectroscopy, X-ray powder diffraction, scanning electron microscopy and energy dispersive spectrometer. Results showed that the microbial strains could efficiently reduce Fe (III) at an optimal rate of 71 %, and alter the crystal lattice structure of the lamella to promote the interlayer cation exchange, and to efficiently inhibit the Ca-montmorillonite swelling at an inhibitory rate of 48.9 %. Importance Microbial mineral illization is ubiquitous in the natural environment. Microbes in low-permeability reservoirs are able to enable the alteration of the structure and phase of the Fe-poor minerals by reducing Fe (III) and inhibiting clay swelling which is still poorly studied. This study aimed to reveal the interaction mechanism between Fe (III)-reducing bacterial strains and Ca-montmorillonite under anaerobic atmosphere, and to investigate the extent and rates of Fe (III) reduction and phase changes with their activities. Application of Fe (III)-reducing bacteria will provide a new way to inhibit clay swelling, to elevate reservoir permeability, and to reduce pore throat resistance after water flooding for enhanced oil recovery in low-permeability reservoirs. Copyright © 2018 American Society for Microbiology.

  12. The coupling of dynamics and permeability in the hydrocarbon accumulation period controls the oil-bearing potential of low permeability reservoirs: a case study of the low permeability turbidite reservoirs in the middle part of the third member of Shahejie Formation in Dongying Sag

    DEFF Research Database (Denmark)

    Yang, Tian; Cao, Ying-Chang; Wang, Yan-Zhong

    2016-01-01

    The relationships between permeability and dynamics in hydrocarbon accumulation determine oilbearing potential (the potential oil charge) of low permeability reservoirs. The evolution of porosity and permeability of low permeability turbidite reservoirs of the middle part of the third member...... facies A and diagenetic facies B do not develop accumulation conditions with low accumulation dynamics in the late accumulation period for very low permeability. At more than 3000 m burial depth, a larger proportion of turbidite reservoirs are oil charged due to the proximity to the source rock. Also...

  13. Permeability model of tight reservoir sandstones combining core-plug and miniperm analysis of drillcore; longyearbyen co2lab, Svalbard

    NARCIS (Netherlands)

    Magnabosco, Cara; Braathen, Alvar; Ogata, Kei

    2014-01-01

    Permeability measurements in Mesozoic, low-permeability sandstone units within the strata cored in seven drillholes near Longyearbyen, Svalbard, have been analysed to assess the presence of aquifers and their potentials as reservoirs for the storage of carbon dioxide. These targeted sandstones are

  14. Porosity, permeability and 3D fracture network characterisation of dolomite reservoir rock samples.

    Science.gov (United States)

    Voorn, Maarten; Exner, Ulrike; Barnhoorn, Auke; Baud, Patrick; Reuschlé, Thierry

    2015-03-01

    With fractured rocks making up an important part of hydrocarbon reservoirs worldwide, detailed analysis of fractures and fracture networks is essential. However, common analyses on drill core and plug samples taken from such reservoirs (including hand specimen analysis, thin section analysis and laboratory porosity and permeability determination) however suffer from various problems, such as having a limited resolution, providing only 2D and no internal structure information, being destructive on the samples and/or not being representative for full fracture networks. In this paper, we therefore explore the use of an additional method - non-destructive 3D X-ray micro-Computed Tomography (μCT) - to obtain more information on such fractured samples. Seven plug-sized samples were selected from narrowly fractured rocks of the Hauptdolomit formation, taken from wellbores in the Vienna basin, Austria. These samples span a range of different fault rocks in a fault zone interpretation, from damage zone to fault core. We process the 3D μCT data in this study by a Hessian-based fracture filtering routine and can successfully extract porosity, fracture aperture, fracture density and fracture orientations - in bulk as well as locally. Additionally, thin sections made from selected plug samples provide 2D information with a much higher detail than the μCT data. Finally, gas- and water permeability measurements under confining pressure provide an important link (at least in order of magnitude) towards more realistic reservoir conditions. This study shows that 3D μCT can be applied efficiently on plug-sized samples of naturally fractured rocks, and that although there are limitations, several important parameters can be extracted. μCT can therefore be a useful addition to studies on such reservoir rocks, and provide valuable input for modelling and simulations. Also permeability experiments under confining pressure provide important additional insights. Combining these and

  15. Triple-porosity/permeability flow in faulted geothermal reservoirs: Two-dimensional effects

    Energy Technology Data Exchange (ETDEWEB)

    Cesar Suarez Arriaga, M. [Michoacan Univ. & CFE, Mich. (Mexico); Samaniego Verduzco, F. [National Autonomous Univ. of Mexico, Coyoacan (Mexico)

    1995-03-01

    An essential characteristic of some fractured geothermal reservoirs is noticeable when the drilled wells intersect an open fault or macrofracture. Several evidences observed, suggest that the fluid transport into this type of systems, occurs at least in three stages: flow between rock matrix and microfractures, flow between fractures and faults and flow between faults and wells. This pattern flow could define, by analogy to the classical double-porosity model, a triple-porosity, triple-permeability concept. From a mathematical modeling point of view, the non-linearity of the heterogeneous transport processes, occurring with abrupt changes on the petrophysical properties of the rock, makes impossible their exact or analytic solution. To simulate this phenomenon, a detailed two-dimensional geometric model was developed representing the matrix-fracture-fault system. The model was solved numerically using MULKOM with a H{sub 2}O=CO{sub 2} equation of state module. This approach helps to understand some real processes involved. Results obtained from this study, exhibit the importance of considering the triple porosity/permeability concept as a dominant mechanism producing, for example, strong pressure gradients between the reservoir and the bottom hole of some wells.

  16. Transport of Gas Phase Radionuclides in a Fractured, Low-Permeability Reservoir

    Science.gov (United States)

    Cooper, C. A.; Chapman, J.

    2001-12-01

    The U.S. Atomic Energy Commission (predecessor to the Department of Energy, DOE) oversaw a joint program between industry and government in the 1960s and 1970s to develop technology to enhance production from low-permeability gas reservoirs using nuclear stimulation rather than conventional means (e.g., hydraulic and/or acid fracturing). Project Rio Blanco, located in the Piceance Basin, Colorado, was the third experiment under the program. Three 30-kiloton nuclear explosives were placed in a 2134 m deep well at 1780, 1899, and 2039 m below the land surface and detonated in May 1973. Although the reservoir was extensively fractured, complications such as radionuclide contamination of the gas prevented production and subsequent development of the technology. Two-dimensional numerical simulations were conducted to identify the main transport processes that have occurred and are currently occurring in relation to the detonations, and to estimate the extent of contamination in the reservoir. Minor modifications were made to TOUGH2, the multiphase, multicomponent reservoir simulator developed at Lawrence Berkeley National Laboratories. The simulator allows the explicit incorporation of fractures, as well as heat transport, phase change, and first order radionuclide decay. For a fractured two-phase (liquid and gas) reservoir, the largest velocities are of gases through the fractures. In the gas phase, tritium and one isotope of krypton are the principle radionuclides of concern. However, in addition to existing as a fast pathway, fractures also permit matrix diffusion as a retardation mechanism. Another retardation mechanism is radionuclide decay. Simulations show that incorporation of fractures can significantly alter transport rates, and that radionuclides in the gas phase can preferentially migrate upward due to the downward gravity drainage of liquid water in the pores. This project was funded by the National Nuclear Security Administration, Nevada Operations Office

  17. The Tianjin geothermal field (north-eastern China): Water chemistry and possible reservoir permeability reduction phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Minissale, Angelo; Montegrossi, Giordano; Orlando, Andrea [Institute of Geosciences and Earth Resources, National Research Council of Italy (CNR), Via G. La Pira 4, 50121 Florence (Italy); Borrini, Daniele; Tassi, Franco [Department of Earth Sciences, University of Florence, Via G. La Pira 4, 50121 Florence (Italy); Vaselli, Orlando [Institute of Geosciences and Earth Resources, National Research Council of Italy (CNR), Via G. La Pira 4, 50121 Florence (Italy); Department of Earth Sciences, University of Florence, Via G. La Pira 4, 50121 Florence (Italy); Huertas, Antonio Delgado [Estacion Experimental de Zaidin (CSIC), Prof. Albareda 1, 18008 Granada (Spain); Yang, Jincheng; Cheng, Wanquing [Aode Renewable Energy Research Institute, 90 Weijin South Road, Nankai District, 300381 Tianjin (China); Tedesco, Dario [Department of Environmental Sciences, Second University of Naples, Via Vivaldi 43, Caserta 81100 (Italy); Institute of Environmental Geology and Geo Engineering (CNR), Piazzale A. Moro 5, Roma 00100 (Italy); Poreda, Robert [Department of Earth and Environmental Sciences, University of Rochester, 227 Hutchison Hall, Rochester, NY 14627 (United States)

    2008-08-15

    Injection of spent (cooled) thermal fluids began in the Tianjin geothermal district, north-eastern China, at the end of the 1990s. Well injectivities declined after 3-4 years because of self-sealing processes that reduced reservoir permeability. The study focuses on the factors that may have caused the observed decrease in permeability, using chemical and isotopic data on fluids (water and gas) and mineral phases collected from production and injection wells. The results of data processing and interpretation indicate that (1) it is very unlikely that calcite and silica precipitation is taking place in the reservoir; (2) the Fe- and Zn-rich mineral phases (e.g. sulfides, hydroxides and silicates) show positive saturation indexes; (3) SEM and XRD analyses of filtered material reveal that the latter mineral phases are common; (4) visual observation of casings and surface installations, and of corrosion products, suggests that a poor quality steel was used in their manufacture; (5) significant quantities of solids (e.g. quartz and feldspar crystals) are carried by the geothermal fluid; (6) seasonal changes in fluid composition lead to a reduction in casing corrosion during the summer. It was concluded that the decrease in injectivity in the Tianjin wells is caused only in part by the oxidation of casings, downhole pumps, and surface installations, triggered by free oxygen in the injected fluids; the utilization of better quality steels should drastically reduce this type of corrosion. Self-sealing of pores and fractures by reservoir formation solids and by the Fe-corrosion products suspended in the injected fluids seems to be a more important phenomenon, whose effect could be greatly reduced by installing filtering devices at all sites. (author)

  18. The Role of Horizontal Wells when Developing Low-Permeable, Heterogeneous Reservoirs

    Directory of Open Access Journals (Sweden)

    M.P. Yurova

    2017-09-01

    Full Text Available The widespread use of horizontal drilling in recent years has shown that horizontal wells can be successfully used both at the initial and late stages of development. This is due to the fact that horizontal wells, in contrast to vertical wells, contact a larger area of ​​the productive formation, while the surface of drainage of the oil-saturated layer, productivity of the wells due to the formation of cracks, and also the influence on thin layers increases. One of the methods of impact on the reservoir is the steam-thermal method. The main advantage of the use of the heat wave method in horizontal wells is a significant increase in the well production rate, a decrease in the water cut of the reservoir, a decrease in the oil viscosity, an increase in the injectivity of the injection well, and an increase in the inflow in producing wells. As a result of the total effect, a significant increase in production is obtained throughout the entire deposit. Enhanced oil recovery from the injection of steam is achieved by reducing the viscosity of oil, covering the reservoir with steam, distilling oil and extracting with a solvent. All this increases the displacement coefficient. One of the most effective ways to increase oil recovery at a late stage of field operation is sidetracking in emergency, highly watered and low-productive wells. This leads to the development of residual reserves in weakly drained zones of reservoirs with a substantial increase in well productivity in low-permeable reservoirs. This approach assumes that the initial drilling of wells is a ‘pilot’ stage, which precedes the development of oil reserves in the late stages of deposit development. In the fields of Western Siberia, multiple hydraulic fracturing of the reservoir has been improved due to a special stinger in the liner hanger of multi-packer installation, which excludes the influence of high pressures on the production column under the multiple hydraulic fracturing

  19. Oil recovery enhancement from fractured, low permeability reservoirs. Annual report 1990--1991, Part 1

    Energy Technology Data Exchange (ETDEWEB)

    Poston, S.W.

    1991-12-31

    Joint funding by the Department of Energy and the State of Texas has Permitted a three year, multi-disciplinary investigation to enhance oil recovery from a dual porosity, fractured, low matrix permeability oil reservoir to be initiated. The Austin Chalk producing horizon trending thru the median of Texas has been identified as the candidate for analysis. Ultimate primary recovery of oil from the Austin Chalk is very low because of two major technological problems. The commercial oil producing rate is based on the wellbore encountering a significant number of natural fractures. The prediction of the location and frequency of natural fractures at any particular region in the subsurface is problematical at this time, unless extensive and expensive seismic work is conducted. A major portion of the oil remains in the low permeability matrix blocks after depletion because there are no methods currently available to the industry to mobilize this bypassed oil. The following multi-faceted study is aimed to develop new methods to increase oil and gas recovery from the Austin Chalk producing trend. These methods may involve new geological and geophysical interpretation methods, improved ways to study production decline curves or the application of a new enhanced oil recovery technique. The efforts for the second year may be summarized as one of coalescing the initial concepts developed during the initial phase to more in depth analyses. Accomplishments are predicting natural fractures; relating recovery to well-log signatures; development of the EOR imbibition process; mathematical modeling; and field test.

  20. Hydrocarbon Potential in Sandstone Reservoir Isolated inside Low Permeability Shale Rock (Case Study: Beruk Field, Central Sumatra Basin)

    Science.gov (United States)

    Diria, Shidqi A.; Musu, Junita T.; Hasan, Meutia F.; Permono, Widyo; Anwari, Jakson; Purba, Humbang; Rahmi, Shafa; Sadjati, Ory; Sopandi, Iyep; Ruzi, Fadli

    2018-03-01

    Upper Red Bed, Menggala Formation, Bangko Formation, Bekasap Formation and Duri Formationare considered as the major reservoirs in Central Sumatra Basin (CSB). However, Telisa Formation which is well-known as seal within CSB also has potential as reservoir rock. Field study discovered that lenses and layers which has low to high permeability sandstone enclosed inside low permeability shale of Telisa Formation. This matter is very distinctive and giving a new perspective and information related to the invention of hydrocarbon potential in reservoir sandstone that isolated inside low permeability shale. This study has been conducted by integrating seismic data, well logs, and petrophysical data throughly. Facies and static model are constructed to estimate hydrocarbon potential resource. Facies model shows that Telisa Formation was deposited in deltaic system while the potential reservoir was deposited in distributary mouth bar sandstone but would be discontinued bedding among shale mud-flat. Besides, well log data shows crossover between RHOB and NPHI, indicated that distributary mouth bar sandstone is potentially saturated by hydrocarbon. Target area has permeability ranging from 0.01-1000 mD, whereas porosity varies from 1-30% and water saturation varies from 30-70%. The hydrocarbon resource calculation approximates 36.723 MSTB.

  1. Estimating reservoir permeability from gravity current modeling of CO2 flow at Sleipner storage project, North Sea

    Science.gov (United States)

    Cowton, L. R.; Neufeld, J. A.; Bickle, M.; White, N.; White, J.; Chadwick, A.

    2017-12-01

    Vertically-integrated gravity current models enable computationally efficient simulations of CO2 flow in sub-surface reservoirs. These simulations can be used to investigate the properties of reservoirs by minimizing differences between observed and modeled CO2 distributions. At the Sleipner project, about 1 Mt yr-1 of supercritical CO2 is injected at a depth of 1 km into a pristine saline aquifer with a thick shale caprock. Analysis of time-lapse seismic reflection surveys shows that CO2 is distributed within 9 discrete layers. The trapping mechanism comprises a stacked series of 1 m thick, impermeable shale horizons that are spaced at 30 m intervals through the reservoir. Within the stratigraphically highest reservoir layer, Layer 9, a submarine channel deposit has been mapped on the pre-injection seismic survey. Detailed measurements of the three-dimensional CO2 distribution within Layer 9 have been made using seven time-lapse surveys, providing a useful benchmark against which numerical flow simulations can be tested. Previous simulations have, in general, been largely unsuccessful in matching the migration rate of CO2 in this layer. Here, CO2 flow within Layer 9 is modeled as a vertically-integrated gravity current that spreads beneath a structurally complex caprock using a two-dimensional grid, considerably increasing computational efficiency compared to conventional three-dimensional simulators. This flow model is inverted to find the optimal reservoir permeability in Layer 9 by minimizing the difference between observed and predicted distributions of CO2 as a function of space and time. A three parameter inverse model, comprising reservoir permeability, channel permeability and channel width, is investigated by grid search. The best-fitting reservoir permeability is 3 Darcys, which is consistent with measurements made on core material from the reservoir. Best-fitting channel permeability is 26 Darcys. Finally, the ability of this simplified numerical model

  2. Capacity expansion analysis of UGSs rebuilt from low-permeability fractured gas reservoirs with CO2 as cushion gas

    Directory of Open Access Journals (Sweden)

    Yufei Tan

    2016-11-01

    Full Text Available The techniques of pressurized mining and hydraulic fracturing are often used to improve gas well productivity at the later development stage of low-permeability carbonate gas reservoirs, but reservoirs are watered out and a great number of micro fractures are produced. Therefore, one of the key factors for underground gas storages (UGS rebuilt from low-permeability fractured gas reservoirs with CO2 as the cushion gas is how to expand storage capacity effectively by injecting CO2 to displace water and to develop control strategies for the stable migration of gas–water interface. In this paper, a mathematical model was established to simulate the gas–water flow when CO2 was injected into dual porosity reservoirs to displace water. Then, the gas–water interface migration rules while CO2 was injected in the peripheral gas wells for water displacement were analyzed with one domestic UGS rebuilt from fractured gas reservoirs as the research object. And finally, discussion was made on how CO2 dissolution, bottom hole flowing pressure (BHFP, CO2 injection rate and micro fracture parameters affect the stability of gas–water interface in the process of storage capacity expansion. It is shown that the speed of capacity expansion reaches the maximum value at the fifth cycle and then decreases gradually when UGS capacity is expanded in the pattern of more injection and less withdrawal. Gas–water interface during UGS capacity expansion is made stable due to that the solubility of CO2 in water varies with the reservoir pressure. When the UGS capacity is expanded at constant BHFP and the flow rate, the expansion speed can be increased effectively by increasing the BHFP and the injection flow rate of gas wells in the central areas appropriately. In the reservoir areas with high permeability and fracture-matrix permeability ratio, the injection flow rate should be reduced properly to prevent gas–water interface fingering caused by a high-speed flow

  3. Predicting permeability of low enthalpy geothermal reservoirs: A case study from the Upper Triassic − Lower Jurassic Gassum Formation, Norwegian–Danish Basin

    DEFF Research Database (Denmark)

    Weibel, Rikke; Olivarius, Mette; Kristensen, Lars

    2017-01-01

    This paper aims at improving the predictability of permeability in low enthalpy geothermal reser-voirs by investigating the effect of diagenesis on sandstone permeability. Applying the best fittedporosity–permeability trend lines, obtained from conventional core analysis, to log-interpreted poros...

  4. The chemistry of ultra-low concentrations

    International Nuclear Information System (INIS)

    Vertes, Attila; Kiss, Istvan

    1987-01-01

    Methods for the separation and enrichment of radionuclides in the ultra-low concentration range (coprecipitation, adsorption of radioactive substances on crystals) are disscussed in this chapter of the textbook. The properties and behaviour of ultra-dilute solutions, radiocolloids and the electrochemistry of ultra-dilute solution are also overviewed

  5. Prediction of Geomechanical Properties from Thermal Conductivity of Low-Permeable Reservoirs

    Science.gov (United States)

    Chekhonin, Evgeny; Popov, Evgeny; Popov, Yury; Spasennykh, Mikhail; Ovcharenko, Yury; Zhukov, Vladislav; Martemyanov, Andrey

    2016-04-01

    A key to assessing a sedimentary basin's hydrocarbon prospect is correct reconstruction of thermal and structural evolution. It is impossible without adequate theory and reliable input data including among other factors thermal and geomechanical rock properties. Both these factors are also important in geothermal reservoirs evaluation and carbon sequestration problem. Geomechanical parameters are usually estimated from sonic logging and rare laboratory measurements, but sometimes it is not possible technically (low quality of the acoustic signal, inappropriate borehole and mud conditions, low core quality). No wonder that there are attempts to correlate the thermal and geomechanical properties of rock, but no one before did it with large amount of high quality thermal conductivity data. Coupling results of sonic logging and non-destructive non-contact thermal core logging opens wide perspectives for studying a relationship between the thermal and geomechanical properties. More than 150 m of full size cores have been measured at core storage with optical scanning technique. Along with results of sonic logging performed with Sonic Scanner in different wells drilled in low permeable formations in West Siberia (Russia) it provided us with unique data set. It was established a strong correlation between components of thermal conductivity (measured perpendicular and parallel to bedding) and compressional and shear acoustic velocities in Bazhen formation. As a result, prediction of geomechanical properties via thermal conductivity data becomes possible, corresponding results was demonstrated. The work was supported by the Russian Ministry of Education and Science, project No. RFMEFI58114X0008.

  6. Ultra low bit-rate speech coding

    CERN Document Server

    Ramasubramanian, V

    2015-01-01

    "Ultra Low Bit-Rate Speech Coding" focuses on the specialized topic of speech coding at very low bit-rates of 1 Kbits/sec and less, particularly at the lower ends of this range, down to 100 bps. The authors set forth the fundamental results and trends that form the basis for such ultra low bit-rates to be viable and provide a comprehensive overview of various techniques and systems in literature to date, with particular attention to their work in the paradigm of unit-selection based segment quantization. The book is for research students, academic faculty and researchers, and industry practitioners in the areas of speech processing and speech coding.

  7. Physics with ultra-low energy antiprotons

    International Nuclear Information System (INIS)

    Holtkamp, D.B.; Holzscheiter, M.H.; Hughes, R.J.

    1989-01-01

    The experimental observation that all forms of matter experience the same gravitational acceleration is embodied in the weak equivalence principle of gravitational physics. However no experiment has tested this principle for particles of antimatter such as the antiproton or the antihydrogen atom. Clearly the question of whether antimatter is in compliance with weak equivalence is a fundamental experimental issue, which can best be addressed at an ultra-low energy antiproton facility. This paper addresses the issue. 20 refs

  8. Ultra low power full adder topologies

    DEFF Research Database (Denmark)

    Moradi, Farshad; Wisland, Dag T.; Mahmoodi, Hamid

    In this paper several low power full adder topologies are presented. The main idea of these circuits is based on the sense energy recovery full adder (SERF) design and the GDI (gate diffusion input) technique. These subthreshold circuits are employed for ultra low power applications. While the pr...... the proposed circuits have some area overhead that is negligible, they have at least 62% less power dissipation when compared with existing designs. In this paper, 65 nm standard models are used for simulations....

  9. PHYSICS WITH ULTRA-LOW ENERGY ANTIPROTONS

    Energy Technology Data Exchange (ETDEWEB)

    M. HOLZSCHEITER

    2001-02-01

    In this report the author describes the current status of the antiproton deceleration (AD) facility at CERN, and highlights the physics program with ultra-low energy antiproton at this installation. He also comments on future possibilities provided higher intensity antiproton beams become available at Fermilab, and review possibilities for initial experiments using direct degrading of high energy antiprotons in material has been developed and proven at CERN.

  10. CHARACTERIZATION OF IN-SITU STRESS AND PERMEABILITY IN FRACTURED RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    Daniel R. Burns; M. Nafi Toksoz

    2004-07-19

    Expanded details and additional results are presented on two methods for estimating fracture orientation and density in subsurface reservoirs from scattered seismic wavefield signals. In the first, fracture density is estimated from the wavenumber spectra of the integrated amplitudes of the scattered waves as a function of offset in pre-stack data. Spectral peaks correctly identified the 50m, 35m, and 25m fracture spacings from numerical model data using a 40Hz source wavelet. The second method, referred to as the Transfer Function-Scattering Index Method, is based upon observations from 3D finite difference modeling that regularly spaced, discrete vertical fractures impart a ringing coda-type signature to any seismic energy that is transmitted through or reflected off of them. This coda energy is greatest when the acquisition direction is parallel to the fractures, the seismic wavelengths are tuned to the fracture spacing, and when the fractures have low stiffness. The method uses surface seismic reflection traces to derive a transfer function, which quantifies the change in an apparent source wavelet propagating through a fractured interval. The transfer function for an interval with low scattering will be more spike-like and temporally compact. The transfer function for an interval with high scattering will ring and be less temporally compact. A Scattering Index is developed based on a time lag weighting of the transfer function. When a 3D survey is acquired with a full range of azimuths, the Scattering Index allows the identification of subsurface areas with high fracturing and the orientation (or strike) of those fractures. The method was calibrated with model data and then applied to field data from a fractured reservoir giving results that agree with known field measurements. As an aid to understanding the scattered wavefield seen in finite difference models, a series of simple point scatterers was used to create synthetic seismic shot records collected over

  11. Digital Rock Physics Aplications: Visualisation Complex Pore and Porosity-Permeability Estimations of the Porous Sandstone Reservoir

    Science.gov (United States)

    Handoyo; Fatkhan; Del, Fourier

    2018-03-01

    Reservoir rock containing oil and gas generally has high porosity and permeability. High porosity is expected to accommodate hydrocarbon fluid in large quantities and high permeability is associated with the rock’s ability to let hydrocarbon fluid flow optimally. Porosity and permeability measurement of a rock sample is usually performed in the laboratory. We estimate the porosity and permeability of sandstones digitally by using digital images from μCT-Scan. Advantages of the method are non-destructive and can be applied for small rock pieces also easily to construct the model. The porosity values are calculated by comparing the digital image of the pore volume to the total volume of the sandstones; while the permeability values are calculated using the Lattice Boltzmann calculations utilizing the nature of the law of conservation of mass and conservation of momentum of a particle. To determine variations of the porosity and permeability, the main sandstone samples with a dimension of 300 × 300 × 300 pixels are made into eight sub-cubes with a size of 150 × 150 × 150 pixels. Results of digital image modeling fluid flow velocity are visualized as normal velocity (streamline). Variations in value sandstone porosity vary between 0.30 to 0.38 and permeability variations in the range of 4000 mD to 6200 mD. The results of calculations show that the sandstone sample in this research is highly porous and permeable. The method combined with rock physics can be powerful tools for determining rock properties from small rock fragments.

  12. Elastic-Brittle-Plastic Behaviour of Shale Reservoirs and Its Implications on Fracture Permeability Variation: An Analytical Approach

    Science.gov (United States)

    Masoudian, Mohsen S.; Hashemi, Mir Amid; Tasalloti, Ali; Marshall, Alec M.

    2018-05-01

    Shale gas has recently gained significant attention as one of the most important unconventional gas resources. Shales are fine-grained rocks formed from the compaction of silt- and clay-sized particles and are characterised by their fissured texture and very low permeability. Gas exists in an adsorbed state on the surface of the organic content of the rock and is freely available within the primary and secondary porosity. Geomechanical studies have indicated that, depending on the clay content of the rock, shales can exhibit a brittle failure mechanism. Brittle failure leads to the reduced strength of the plastic zone around a wellbore, which can potentially result in wellbore instability problems. Desorption of gas during production can cause shrinkage of the organic content of the rock. This becomes more important when considering the use of shales for CO2 sequestration purposes, where CO2 adsorption-induced swelling can play an important role. These phenomena lead to changes in the stress state within the rock mass, which then influence the permeability of the reservoir. Thus, rigorous simulation of material failure within coupled hydro-mechanical analyses is needed to achieve a more systematic and accurate representation of the wellbore. Despite numerous modelling efforts related to permeability, an adequate representation of the geomechanical behaviour of shale and its impact on permeability and gas production has not been achieved. In order to achieve this aim, novel coupled poro-elastoplastic analytical solutions are developed in this paper which take into account the sorption-induced swelling and the brittle failure mechanism. These models employ linear elasticity and a Mohr-Coulomb failure criterion in a plane-strain condition with boundary conditions corresponding to both open-hole and cased-hole completions. The post-failure brittle behaviour of the rock is defined using residual strength parameters and a non-associated flow rule. Swelling and shrinkage

  13. Ultra-Low-Dropout Linear Regulator

    Science.gov (United States)

    Thornton, Trevor; Lepkowski, William; Wilk, Seth

    2011-01-01

    A radiation-tolerant, ultra-low-dropout linear regulator can operate between -150 and 150 C. Prototype components were demonstrated to be performing well after a total ionizing dose of 1 Mrad (Si). Unlike existing components, the linear regulator developed during this activity is unconditionally stable over all operating regimes without the need for an external compensation capacitor. The absence of an external capacitor reduces overall system mass/volume, increases reliability, and lowers cost. Linear regulators generate a precisely controlled voltage for electronic circuits regardless of fluctuations in the load current that the circuit draws from the regulator.

  14. The Hybrid of Classification Tree and Extreme Learning Machine for Permeability Prediction in Oil Reservoir

    KAUST Repository

    Prasetyo Utomo, Chandra

    2011-01-01

    the permeability value. These are based on the well logs data. In order to handle the high range of the permeability value, a classification tree is utilized. A benefit of this innovation is that the tree represents knowledge in a clear and succinct fashion

  15. Architecture and reservoir quality of low-permeable Eocene lacustrine turbidite sandstone from the Dongying Depression, East China

    Science.gov (United States)

    Munawar, Muhammad Jawad; Lin, Chengyan; Chunmei, Dong; Zhang, Xianguo; Zhao, Haiyan; Xiao, Shuming; Azeem, Tahir; Zahid, Muhammad Aleem; Ma, Cunfei

    2018-05-01

    The architecture and quality of lacustrine turbidites that act as petroleum reservoirs are less well documented. Reservoir architecture and multiscale heterogeneity in turbidites represent serious challenges to production performance. Additionally, establishing a hierarchy profile to delineate heterogeneity is a challenging task in lacustrine turbidite deposits. Here, we report on the turbidites in the middle third member of the Eocene Shahejie Formation (Es3), which was deposited during extensive Middle to Late Eocene rifting in the Dongying Depression. Seismic records, wireline log responses, and core observations were integrated to describe the reservoir heterogeneity by delineating the architectural elements, sequence stratigraphic framework and lithofacies assemblage. A petrographic approach was adopted to constrain microscopic heterogeneity using an optical microscope, routine core analyses and X-ray diffraction (XRD) analyses. The Es3m member is interpreted as a sequence set composed of four composite sequences: CS1, CS2, CS3 and CS4. A total of forty-five sequences were identified within these four composite sequences. Sand bodies were mainly deposited as channels, levees, overbank splays, lobes and lobe fringes. The combination of fining-upward and coarsening-upward lithofacies patterns in the architectural elements produces highly complex composite flow units. Microscopic heterogeneity is produced by diagenetic alteration processes (i.e., feldspar dissolution, authigenic clay formation and quartz cementation). The widespread kaolinization of feldspar and mobilization of materials enhanced the quality of the reservoir by producing secondary enlarged pores. In contrast, the formation of pore-filling authigenic illite and illite/smectite clays reduced its permeability. Recovery rates are higher in the axial areas and smaller in the marginal areas of architectural elements. This study represents a significant insight into the reservoir architecture and

  16. Research and application of multi-hydrogen acidizing technology of low-permeability reservoirs for increasing water injection

    Science.gov (United States)

    Ning, Mengmeng; Che, Hang; Kong, Weizhong; Wang, Peng; Liu, Bingxiao; Xu, Zhengdong; Wang, Xiaochao; Long, Changjun; Zhang, Bin; Wu, Youmei

    2017-12-01

    The physical characteristics of Xiliu 10 Block reservoir is poor, it has strong reservoir inhomogeneity between layers and high kaolinite content of the reservoir, the scaling trend of fluid is serious, causing high block injection well pressure and difficulty in achieving injection requirements. In the past acidizing process, the reaction speed with mineral is fast, the effective distance is shorter and It is also easier to lead to secondary sedimentation in conventional mud acid system. On this point, we raised multi-hydrogen acid technology, multi-hydrogen acid release hydrogen ions by multistage ionization which could react with pore blockage, fillings and skeletal effects with less secondary pollution. Multi-hydrogen acid system has advantages as moderate speed, deep penetration, clay low corrosion rate, wet water and restrains precipitation, etc. It can reach the goal of plug removal in deep stratum. The field application result shows that multi-hydrogen acid plug removal method has good effects on application in low permeability reservoir in Block Xiliu 10.

  17. 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)

  18. Bacterial community diversity in a low-permeability oil reservoir and its potential for enhancing oil recovery.

    Science.gov (United States)

    Xiao, Meng; Zhang, Zhong-Zhi; Wang, Jing-Xiu; Zhang, Guang-Qing; Luo, Yi-Jing; Song, Zhao-Zheng; Zhang, Ji-Yuan

    2013-11-01

    The diversity of indigenous bacterial community and the functional species in the water samples from three production wells of a low permeability oil reservoir was investigated by high-throughput sequencing technology. The potential of application of indigenous bacteria for enhancing oil recovery was evaluated by examination of the effect of bacterial stimulation on the formation water-oil-rock surface interactions and micromodel test. The results showed that production well 88-122 had the most diverse bacterial community and functional species. The broth of indigenous bacteria stimulated by an organic nutrient activator at aerobic condition changed the wettability of the rock surface from oil-wet to water-wet. Micromodel test results showed that flooding using stimulated indigenous bacteria following water flooding improved oil recovery by 6.9% and 7.7% in fractured and unfractured micromodels, respectively. Therefore, the zone of low permeability reservoir has a great potential for indigenous microbial enhanced oil recovery. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Numerical Modeling of Permeability Enhancement by Hydroshearing: the Case of Phase I Reservoir Creation at Fenton Hill

    Science.gov (United States)

    Rutqvist, J.; Rinaldi, A. P.

    2017-12-01

    The exploitation of a geothermal system is one of the most promising clean and almost inexhaustible forms of energy production. However, the exploitation of hot dry rock (HDR) reservoirs at depth requires circulation of a large amount of fluids. Indeed, the conceptual model of an Enhanced Geothermal System (EGS) requires that the circulation is enhanced by fluid injection. The pioneering experiments at Fenton Hill demonstrated the feasibility of EGS by producing the world's first HDR reservoirs. Such pioneering project demonstrated that the fluid circulation can be effectively enhanced by stimulating a preexisting fracture zone. The so-called "hydroshearing" involving shear activation of preexisting fractures is recognized as one of the main processes effectively enhancing permeability. The goal of this work is to quantify the effect of shear reactivation on permeability by proposing a model that accounts for fracture opening and shearing. We develop a case base on a pressure stimulation experiment at Fenton Hill, in which observation suggest that a fracture was jacked open by pressure increase. The proposed model can successfully reproduce such a behavior, and we compare the base case of pure elastic opening with the hydroshearing model to demonstrate that this latter could have occurred at the field, although no "felt" seismicity was observed. Then we investigate on the sensitivity of the proposed model by varying some of the critical parameters such as the maximum aperture, the dilation angle, as well as the fracture density.

  20. Porosity and permeability evolution of vesicular basalt reservoirs with increasing depth: constraints from the Big Island of Hawai'i

    Science.gov (United States)

    Millett, John; Haskins, Eric; Thomas, Donald; Jerram, Dougal; Planke, Sverre; Healy, Dave; Kück, Jochem; Rossetti, Lucas; Farrell, Natalie; Pierdominici, Simona

    2017-04-01

    Volcanic reservoirs are becoming increasingly important in the targeting of petroleum, geothermal and water resources globally. However, key areas of uncertainty in relation to volcanic reservoir properties during burial in different settings remain. In this contribution, we present results from borehole logging and sampling operations within two fully cored c. 1.5 km deep boreholes, PTA2 and KMA1, from the Humúula saddle region on the Big Island of Hawai'i. The boreholes were drilled as part of the Humu'ula Groundwater Research Project (HGRP) between 2013-2016 and provide unique insights into the evolution of pore structure with increasing burial in a basaltic dominated lava sequence. The boreholes encounter mixed sequences of 'a'ā, pāhoehoe and transitional lava flows along with subsidiary intrusions and sediments from the shield to post-shield phases of Mauna Kea. Borehole wireline data including sonic, spectral gamma and Televiewer imagery were collected along with density, porosity, permeability and ultrasonic velocity laboratory measurements from core samples. A range of intra-facies were sampled for analysis from various depths within the two boreholes. By comparison with core data, the potential for high resolution Televiewer imaging to reveal spectacular intra-facies features including individual vesicles, vesicle segregations, 'a'ā rubble zones, intrusive contacts, and intricate pāhoehoe lava flow lobe morphologies is demonstrated. High quality core data enables the calibration of Televiewer facies enabling improved interpretation of volcanic reservoir features in the more common exploration scenario where core is absent. Laboratory results record the ability of natural vesicular basalt samples to host very high porosity (>50%) and permeability (>10 darcies) within lava flow top facies which we demonstrate are associated with vesicle coalescence and not micro-fractures. These properties may be maintained to depths of c. 1.5 km in regions of limited

  1. Endometrial safety of ultra-low-dose estradiol vaginal tablets

    DEFF Research Database (Denmark)

    Simon, James; Nachtigall, Lila; Ulrich, Lian G

    2010-01-01

    To evaluate the endometrial hyperplasia and carcinoma rate after 52-week treatment with ultra-low-dose 10-microgram 17ß-estradiol vaginal tablets in postmenopausal women with vaginal atrophy.......To evaluate the endometrial hyperplasia and carcinoma rate after 52-week treatment with ultra-low-dose 10-microgram 17ß-estradiol vaginal tablets in postmenopausal women with vaginal atrophy....

  2. Endometrial safety of ultra-low-dose estradiol vaginal tablets

    DEFF Research Database (Denmark)

    Simon, James; Nachtigall, Lila; Ulrich, Lian G

    2010-01-01

    To evaluate the endometrial hyperplasia and carcinoma rate after 52-week treatment with ultra-low-dose 10-microgram 17β-estradiol vaginal tablets in postmenopausal women with vaginal atrophy.......To evaluate the endometrial hyperplasia and carcinoma rate after 52-week treatment with ultra-low-dose 10-microgram 17β-estradiol vaginal tablets in postmenopausal women with vaginal atrophy....

  3. CHARACTERIZATION OF IN-SITU STRESS AND PERMEABILITY IN FRACTURED RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    Daniel R. Burns; M. Nafi Toksoz

    2005-02-04

    Numerical modeling and field data tests are presented on the Transfer Function/Scattering Index Method for estimating fracture orientation and density in subsurface reservoirs from the ''coda'' or scattered energy in the seismic trace. Azimuthal stacks indicate that scattered energy is enhanced along the fracture strike direction. A transfer function method is used to more effectively indicate fracture orientation. The transfer function method, which involves a comparison of the seismic signature above and below a reservoir interval, effectively eliminates overburden effects and acquisition imprints in the analysis. The transfer function signature is simplified into a scattering index attribute value that gives fracture orientation and spatial variations of the fracture density within a field. The method is applied to two field data sets, a 3-D Ocean Bottom Cable (OBC) seismic data set from an offshore fractured carbonate reservoir in the Adriatic Sea and a 3-D seismic data set from an onshore fractured carbonate field in the Middle East. Scattering index values are computed in both fields at the reservoir level, and the results are compared to borehole breakout data and Formation MicroImager (FMI) logs in nearby wells. In both cases the scattering index results are in very good agreement with the well data. Field data tests and well validation will continue. In the area of technology transfer, we have made presentations of our results to industry groups at MIT technical review meetings, international technical conferences, industry workshops, and numerous exploration and production company visits.

  4. Characterization of fracture reservoirs using static and dynamic data: From sonic and 3D seismic to permeability distribution. Annual report, March 1, 1996--February 28, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Parra, J.O.; Collier, H.A.; Owen, T.E. [and others

    1997-06-01

    In low porosity, low permeability zones, natural fractures are the primary source of permeability which affect both production and injection of fluids. The open fractures do not contribute much to porosity, but they provide an increased drainage network to any porosity. They also may connect the borehole to remote zones of better reservoir characteristics. An important approach to characterizing the fracture orientation and fracture permeability of reservoir formations is one based on the effects of such conditions on the propagation of acoustic and seismic waves in the rock. The project is a study directed toward the evaluation of acoustic logging and 3D-seismic measurement techniques as well as fluid flow and transport methods for mapping permeability anisotropy and other petrophysical parameters for the understanding of the reservoir fracture systems and associated fluid dynamics. The principal application of these measurement techniques and methods is to identify and investigate the propagation characteristics of acoustic and seismic waves in the Twin Creek hydrocarbon reservoir owned by Union Pacific Resources (UPR) and to characterize the fracture permeability distribution using production data. This site is located in the overthrust area of Utah and Wyoming. UPR drilled six horizontal wells, and presently UPR has two rigs running with many established drill hole locations. In addition, there are numerous vertical wells that exist in the area as well as 3D seismic surveys. Each horizontal well contains full FMS logs and MWD logs, gamma logs, etc.

  5. Investigating Multiphase Flow Phenomena in Fine-Grained Reservoir Rocks: Insights from Using Ethane Permeability Measurements over a Range of Pore Pressures

    Directory of Open Access Journals (Sweden)

    Eric Aidan Letham

    2018-01-01

    Full Text Available The ability to quantify effective permeability at the various fluid saturations and stress states experienced during production from shale oil and shale gas reservoirs is required for efficient exploitation of the resources, but to date experimental challenges prevent measurement of the effective permeability of these materials over a range of fluid saturations. To work towards overcoming these challenges, we measured effective permeability of a suite of gas shales to gaseous ethane over a range of pore pressures up to the saturated vapour pressure. Liquid/semiliquid ethane saturation increases due to adsorption and capillary condensation with increasing pore pressure resulting in decreasing effective permeability to ethane gas. By how much effective permeability to ethane gas decreases with adsorption and capillary condensation depends on the pore size distribution of each sample and the stress state that effective permeability is measured at. Effective permeability decreases more at higher stress states because the pores are smaller at higher stress states. The largest effective permeability drops occur in samples with dominant pore sizes in the mesopore range. These pores are completely blocked due to capillary condensation at pore pressures near the saturated vapour pressure of ethane. Blockage of these pores cuts off the main fluid flow pathways in the rock, thereby drastically decreasing effective permeability to ethane gas.

  6. Molded ultra-low density microcellular foams

    International Nuclear Information System (INIS)

    Rand, P.B.; Montoya, O.J.

    1986-07-01

    Ultra-low density (< 0.01 g/cc) microcellular foams were required for the NARYA pulsed-power-driven x-ray laser development program. Because of their extreme fragility, molded pieces would be necessary to successfully field these foams in the pulsed power accelerator. All of the foams evaluated were made by the thermally induced phase separation technique from solutions of water soluble polymers. The process involved rapidly freezing the solution to induce the phase separation, and then freeze drying to remove the water without destroying the foam's structure. More than sixty water soluble polymers were evaluated by attempting to make their solutions into foams. The foams were evaluated for shrinkage, density, and microstructure to determine their suitability for molding and meeting the required density and cell size requirements of 5.0 mg/cc and less than twenty μmeters. Several promising water soluble polymers were identified including the polyactylic acids, guar gums, polyactylamide, and polyethylene oxide. Because of thier purity, structure, and low shrinkage, the polyacrylic acids were chosen to develop molding processes. The initial requirements were for 2.0 cm. long molded rods with diameters of 1.0, 2.0. and 3.0 mm. These rods were made by freezing the solution in thin walled silicon rubber molds, extracting the frozen preform from the mold, and then freeze drying. Requirements for half rods and half annuli necessitated using aluminum molds. Again we successfully molded these shapes. Our best efforts to date involve molding annuli with 3.0 mm outside diameters and 2.0 mm inside diameters

  7. Spectral SP: A New Approach to Mapping Reservoir Flow and Permeability

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Donald M. [Univ. of Hawaii, Honolulu, HI (United States). Hawaii Inst. of Geophysics; Lienert, Barry R. [Univ. of Hawaii, Honolulu, HI (United States). Hawaii Inst. of Geophysics; Wallin, Erin L. [Univ. of Hawaii, Honolulu, HI (United States); Gasperikova, Erika [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2014-05-27

    Our objectives for the current project were to develop an innovative inversion and analysis procedure for magnetotelluric field data and time variable self-potentials that will enable us to map not only the subsurface resistivity structure of a geothermal prospect but to also delineate the permeability distribution within the field. Hence, the ultimate objective were to provide better targeting information for exploratory and development drilling of a geothermal prospect. Field data were collected and analyzed from the Kilauea Summit, Kilauea East Rift Zone, and the Humuula Saddle between Mauna Loa and Mauna Kea volcanoes. All of these areas were known or suspected to have geothermal activity of varying intensities. Our results provided evidence for significant long-term coordinated changes in spontaneous potential that could be associated with subsurface flows, significant interferences were encountered that arose from surface environmental changes (rainfall, temperature) that rendered it nearly impossible to unequivocally distinguish between deep fluid flow changes and environmental effects. Further, the analysis of the inferred spontaneous potential changes in the context of depth of the signals, and hence, permeability horizons, were unable to be completed in the time available.

  8. Investigating the effects of rock porosity and permeability on the performance of nitrogen injection into a southern Iranian oil reservoirs through neural network

    Science.gov (United States)

    Gheshmi, M. S.; Fatahiyan, S. M.; Khanesary, N. T.; Sia, C. W.; Momeni, M. S.

    2018-03-01

    In this work, a comprehensive model for Nitrogen injection into an oil reservoir (southern Iranian oil fields) was developed and used to investigate the effects of rock porosity and permeability on the oil production rate and the reservoir pressure decline. The model was simulated and developed by using ECLIPSE300 software, which involved two scenarios as porosity change and permeability changes in the horizontal direction. We found that the maximum pressure loss occurs at a porosity value of 0.07, which later on, goes to pressure buildup due to reservoir saturation with the gas. Also we found that minimum pressure loss is encountered at porosity 0.46. Increases in both pressure and permeability in the horizontal direction result in corresponding increase in the production rate, and the pressure drop speeds up at the beginning of production as it increases. However, afterwards, this pressure drop results in an increase in pressure because of reservoir saturation. Besides, we determined the regression values, R, for the correlation between pressure and total production, as well as for the correlation between permeability and the total production, using neural network discipline.

  9. CHARACTERIZATION OF IN-SITU STRESS AND PERMEABILITY IN FRACTURED RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    Daniel R. Burns; M. Nafi Toksoz

    2002-12-31

    We have extended a three-dimensional finite difference elastic wave propagation model previously developed at the Massachusetts Institute of Technology (MIT) Earth Resources Laboratory (ERL) for modeling and analyzing the effect of fractures on seismic waves. The code has been translated into C language and parallelized [using message passing interface (MPI)] to allow for larger models to be run on Linux PC computer clusters. We have also obtained another 3-D code from Lawrence Berkeley Laboratory, which we will use for verification of our ERL code results and also to run discrete fracture models. Testing of both codes is underway. We are working on a new finite difference model of borehole wave propagation for stressed formations. This code includes coordinate stretching to provide stable, variable grid sizes that will allow us to model the thin fluid annulus layers in borehole problems, especially for acoustic logging while drilling (LWD) applications. We are also extending our analysis routines for the inversion of flexural wave dispersion measurements for in situ stress estimates. Initial results on synthetic and limited field data are promising for a method to invert cross dipole data for the rotation angle and stress state simultaneously. A meeting is being scheduled between MIT and Shell Oil Company scientists to look at data from a fractured carbonate reservoir that may be made available to the project. The Focus/Disco seismic processing system from Paradigm Geophysical has been installed at ERL for field data analysis and as a platform for new analysis modules. We have begun to evaluate the flow properties of discrete fracture distributions through a simple 2D numerical model. Initial results illustrate how fluid flow pathways are very sensitive to variations in the geometry and apertures of fracture network.

  10. Radionuclide Migration at the Rio Blanco Site, A Nuclear-stimulated Low-permeability Natural Gas Reservoir

    Energy Technology Data Exchange (ETDEWEB)

    Clay A. Cooper; Ming Ye; Jenny Chapman; Craig Shirley

    2005-10-01

    The U.S. Department of Energy and its predecessor agencies conducted a program in the 1960s and 1970s that evaluated technology for the nuclear stimulation of low-permeability gas reservoirs. The third and final project in the program, Project Rio Blanco, was conducted in Rio Blanco County, in northwestern Colorado. In this experiment, three 33-kiloton nuclear explosives were simultaneously detonated in a single emplacement well in the Mesaverde Group and Fort Union Formation, at depths of 1,780, 1,899, and 2,039 m below land surface on May 17, 1973. The objective of this work is to estimate lateral distances that tritium released from the detonations may have traveled in the subsurface and evaluate the possible effect of postulated natural-gas development on radionuclide migration. Other radionuclides were considered in the analysis, but the majority occur in relatively immobile forms (such as nuclear melt glass). Of the radionuclides present in the gas phase, tritium dominates in terms of quantity of radioactivity in the long term and contribution to possible whole body exposure. One simulation is performed for {sup 85}Kr, the second most abundant gaseous radionuclide produced after tritium.

  11. Biodiesel as a lubricity additive for ultra low sulfur diesel

    Directory of Open Access Journals (Sweden)

    Subongkoj Topaiboul1 and 2,*

    2010-05-01

    Full Text Available With the worldwide trend to reduce emission from diesel engines, ultra low sulfur diesel has been introduced with thesulfur concentration of less than 10 ppm. Unfortunately, the desulfurization process inevitably reduces the lubricity of dieselfuel significantly. Alternatively, biodiesel, with almost zero sulfur content, has been added to enhance lubricity in an ultralow sulfur diesel. This work has evaluated the effectiveness of the biodiesel amount, sourced from palm and jatropha oil,and origin in ultra low sulfur diesel locally available in the market. Wear scar from a high-frequency reciprocating rig isbenchmarked to the standard value (460 m of diesel fuel lubricity. It was found that very small amount (less than 1% ofbiodiesel from either source significantly improves the lubricity in ultra low sulfur diesel, and the biodiesel from jatropha oilis a superior lubricity enhancer.

  12. Encoded low swing for ultra low power interconnect

    NARCIS (Netherlands)

    Krishnan, R.; Pineda de Gyvez, J.

    2003-01-01

    We present a novel encoded-low swing technique for ultra low power interconnect. Using this technique and an efficient circuit implementation, we achieve an average of 45.7% improvement in the power-delay product over the schemes utilizing low swing techniques alone, for random bit streams. Also, we

  13. Ultra-low-angle boundary networks within recrystallizing grains

    DEFF Research Database (Denmark)

    Ahl, Sonja Rosenlund; Simons, Hugh; Zhang, Yubin

    2017-01-01

    We present direct evidence of a network of well-defined ultra-low-angle boundaries in bulk recrystallizing grains of 99.5% pure aluminium (AA1050) by means of a new, three-dimensional X-ray mapping technique; dark-field X-ray microscopy. These boundaries separate lattice orientation differences o...

  14. FORMULATING ULTRA-LOW-VOC WOOD FURNITURE COATINGS

    Science.gov (United States)

    The article discusses the formulation of ultra-low volatile organic compound (VOC) wood furniture coatings. The annual U.S. market for wood coatings is about 240, 000 cu m (63 million gal). In this basis, between 57 and 91 million kg (125 and 200 million lb) of VOCs are emitted i...

  15. Ultra low and negative expansion glass–ceramic materials ...

    Indian Academy of Sciences (India)

    Ultra low and negative expansion glass–ceramic materials have been obtained from pyrophyllite and blast furnace slag. The batch composition was modified with the addition of lithium carbonate, hydrated alumina, boric acid and nucleating agent (titania). The batch was melted at 1400°C followed by casting in the form of ...

  16. Reaching ultra low phosphorus concentrations by filtration techniques

    NARCIS (Netherlands)

    Scherrenberg, S.M.

    2011-01-01

    This research deals with tertiary treatment techniques used for the removal of phosphorus from wastewater treatment plant (WWTP) effluent. The main objective of this research is to obtain ultra low total phosphorus (<0.15 mg total phosphorus/L) concentrations by coagulation, flocculation and

  17. Mechanism for calcite dissolution and its contribution to development of reservoir porosity and permeability in the Kela 2 gas field,Tarim Basin,China

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    This study is undertaken to understand how calcite precipitation and dissolution contributes to depth-related changes in porosity and permeability of gas-bearing sandstone reservoirs in the Kela 2 gas field of the Tarim Basin, Northwestern China. Sandstone samples and pore water samples are col-lected from well KL201 in the Tarim Basin. Vertical profiles of porosity, permeability, pore water chem-istry, and the relative volume abundance of calcite/dolomite are constructed from 3600 to 4000 m below the ground surface within major oil and gas reservoir rocks. Porosity and permeability values are in-versely correlated with the calcite abundance, indicating that calcite dissolution and precipitation may be controlling porosity and permeability of the reservoir rocks. Pore water chemistry exhibits a sys-tematic variation from the Na2SO4 type at the shallow depth (3600-3630 m), to the NaHCO3 type at the intermediate depth (3630―3695 m),and to the CaCl2 type at the greater depth (3728―3938 m). The geochemical factors that control the calcite solubility include pH, temperature, pressure, Ca2+ concen-tration, the total inorganic carbon concentration (ΣCO2), and the type of pore water. Thermodynamic phase equilibrium and mass conservation laws are applied to calculate the calcite saturation state as a function of a few key parameters. The model calculation illustrates that the calcite solubility is strongly dependent on the chemical composition of pore water, mainly the concentration difference between the total dissolved inorganic carbon and dissolved calcium concentration (i.e., [ΣCO2] -[Ca2+]). In the Na2SO4 water at the shallow depth, this index is close to 0, pore water is near the calcite solubility. Calcite does not dissolve or precipitate in significant quantities. In the NaHCO3 water at the intermedi-ate depth, this index is greater than 0, and pore water is supersaturated with respect to calcite. Massive calcite precipitation was observed at this depth

  18. Oxidation of ultra low carbon and silicon bearing steels

    Energy Technology Data Exchange (ETDEWEB)

    Suarez, Lucia [CTM - Technologic Centre, Materials Technology Area, Manresa, Barcelona (Spain)], E-mail: lucia.suarez@ctm.com.es; Rodriguez-Calvillo, Pablo [CTM - Technologic Centre, Materials Technology Area, Manresa, Barcelona (Spain)], E-mail: pablo.rodriguez@ctm.com.es; Houbaert, Yvan [Department of Materials Science and Engineering, University of Ghent (Belgium)], E-mail: Yvan.Houbaert@UGent.be; Colas, Rafael [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon (Mexico)], E-mail: rcolas@mail.uanl.mx

    2010-06-15

    Oxidation tests were carried out in samples from an ultra low carbon and two silicon bearing steels to determine the distribution and morphology of the oxide species present. The ultra low carbon steel was oxidized for short periods of time within a chamber designed to obtain thin oxide layers by controlling the atmosphere, and for longer times in an electric furnace; the silicon steels were reheated only in the electric furnace. The chamber was constructed to study the behaviour encountered during the short period of time between descaling and rolling in modern continuous mills. It was found that the oxide layers formed on the samples reheated in the electric furnace were made of different oxide species. The specimens treated in the chamber had layers made almost exclusively of wustite. Selected oxide samples were studied by scanning electron microscopy to obtain electron backscattered diffraction patterns, which were used to identify the oxide species in the layer.

  19. Design of ultra-low power impulse radios

    CERN Document Server

    Apsel, Alyssa; Dokania, Rajeev

    2014-01-01

    This book covers the fundamental principles behind the design of ultra-low power radios and how they can form networks to facilitate a variety of applications within healthcare and environmental monitoring, since they may operate for years off a small battery or even harvest energy from the environment. These radios are distinct from conventional radios in that they must operate with very constrained resources and low overhead.  This book provides a thorough discussion of the challenges associated with designing radios with such constrained resources, as well as fundamental design concepts and practical approaches to implementing working designs.  Coverage includes integrated circuit design, timing and control considerations, fundamental theory behind low power and time domain operation, and network/communication protocol considerations.   • Enables detailed understanding of the design space for ultra-low power radio; • Provides detailed discussion and examples of the design of a practical low power ...

  20. Ultra-Low Voltage Class AB Switched Current Memory Cell

    DEFF Research Database (Denmark)

    Igor, Mucha

    1996-01-01

    This paper presents the theoretical basis for the design of class AB switched current memory cells employing floating-gate MOS transistors, suitable for ultra-low-voltage applications. To support the theoretical assumptions circuits based on these cells were designed using a CMOS process with thr......This paper presents the theoretical basis for the design of class AB switched current memory cells employing floating-gate MOS transistors, suitable for ultra-low-voltage applications. To support the theoretical assumptions circuits based on these cells were designed using a CMOS process...... with threshold voltages of 0.9V. Both hand calculations and PSPICE simulations showed that the cells designed allowed a maximum signal range better than +/-13 micoamp, with a supply voltage down to 1V and a quiescent bias current of 1 microamp, resulting in a very high current efficiency and effective power...

  1. Ultra-low-power and ultra-low-cost short-range wireless receivers in nanoscale CMOS

    CERN Document Server

    Lin, Zhicheng; Martins, Rui Paulo

    2016-01-01

    This book provides readers with a description of state-of-the-art techniques to be used for ultra-low-power (ULP) and ultra-low-cost (ULC), short-range wireless receivers. Readers will learn what is required to deploy these receivers in short-range wireless sensor networks, which are proliferating widely to serve the internet of things (IoT) for “smart cities.” The authors address key challenges involved with the technology and the typical tradeoffs between ULP and ULC. Three design examples with advanced circuit techniques are described in order to address these trade-offs, which specially focus on cost minimization. These three techniques enable respectively, cascading of radio frequency (RF) and baseband (BB) circuits under an ultra-low-voltage (ULV) supply, cascoding of RF and BB circuits in current domain for current reuse, and a novel function-reuse receiver architecture, suitable for ULV and multi-band ULP applications such as the sub-GHz ZigBee. ·         Summarizes the state-of-the-art i...

  2. 3D seismic modeling in geothermal reservoirs with a distribution of steam patch sizes, permeabilities and saturations, including ductility of the rock frame

    Science.gov (United States)

    Carcione, José M.; Poletto, Flavio; Farina, Biancamaria; Bellezza, Cinzia

    2018-06-01

    Seismic propagation in the upper part of the crust, where geothermal reservoirs are located, shows generally strong velocity dispersion and attenuation due to varying permeability and saturation conditions and is affected by the brittleness and/or ductility of the rocks, including zones of partial melting. From the elastic-plastic aspect, the seismic properties (seismic velocity, quality factor and density) depend on effective pressure and temperature. We describe the related effects with a Burgers mechanical element for the shear modulus of the dry-rock frame. The Arrhenius equation combined to the octahedral stress criterion define the Burgers viscosity responsible of the brittle-ductile behaviour. The effects of permeability, partial saturation, varying porosity and mineral composition on the seismic properties is described by a generalization of the White mesoscopic-loss model to the case of a distribution of heterogeneities of those properties. White model involves the wave-induced fluid flow attenuation mechanism, by which seismic waves propagating through small-scale heterogeneities, induce pressure gradients between regions of dissimilar properties, where part of the energy of the fast P-wave is converted to slow P (Biot)-wave. We consider a range of variations of the radius and size of the patches and thin layers whose probability density function is defined by different distributions. The White models used here are that of spherical patches (for partial saturation) and thin layers (for permeability heterogeneities). The complex bulk modulus of the composite medium is obtained with the Voigt-Reuss-Hill average. Effective pressure effects are taken into account by using exponential functions. We then solve the 3D equation of motion in the space-time domain, by approximating the White complex bulk modulus with that of a set of Zener elements connected in series. The Burgers and generalized Zener models allows us to solve the equations with a direct grid

  3. Effect of exogenous inoculants on enhancing oil recovery and indigenous bacterial community dynamics in long-term field pilot of low permeability reservoir.

    Science.gov (United States)

    Li, Jing; Xue, Shuwen; He, Chunqiu; Qi, Huixia; Chen, Fulin; Ma, Yanling

    2018-03-20

    Pseudomonas aeruginosa DN1 strain and Bacillus subtilis QHQ110 strain were chosen as rhamnolipid and lipopeptide producer respectively, to evaluate the efficiency of exogenous inoculants on enhancing oil recovery (EOR) and to explore the relationship between injected bacteria and indigenous bacterial community dynamics in long-term filed pilot of Hujianshan low permeability water-flooded reservoir for 26 months. Core-flooding tests showed that the oil displacement efficiency increased by 18.46% with addition of exogenous consortia. Bacterial community dynamics using quantitative PCR and high-throughput sequencing revealed that the exogenous inoculants survived and could live together with indigenous bacterial populations. They gradually became the dominant community after the initial activation, while their comparative advantage weakened continually after 3 months of the first injection. The bacterial populations did not exert an observable change in the process of the second injection of exogenous inoculants. On account of facilitating oil emulsification and accelerating bacterial growth with oil as the carbon source by the injection of exogenous consortia, γ-proteobacteria was finally the prominent bacterial community at class level varying from 25.55 to 32.67%, and the dominant bacterial populations were increased by 2-3 orders of magnitude during the whole processes. The content of organic acids and rhamnolipids in reservoir were promoted with the change of bacterial community diversity, respectively. Cumulative oil increments reached 26,190 barrels for 13 months after the first injection, and 55,947 barrels of oil had been accumulated in all of A20 wells block through two rounds of bacterial consortia injection. The performance of EOR has a cumulative improvement by the injection of exogenous inoculants without observable inhibitory effect on the indigenous bacterial populations, demonstrating the application potential in low permeability water

  4. Effect of Flow Direction on Relative Permeability Curves in Water/Gas Reservoir System: Implications in Geological CO2 Sequestration

    Directory of Open Access Journals (Sweden)

    Abdulrauf Rasheed Adebayo

    2017-01-01

    Full Text Available The effect of gravity on vertical flow and fluids saturation, especially when flow is against gravity, is not often a subject of interest to researchers. This is because of the notion that flow in subsurface formations is usually in horizontal direction and that vertical flow is impossible or marginal because of the impermeable shales or silts overlying them. The density difference between two fluids (usually oil and water flowing in the porous media is also normally negligible; hence gravity influence is neglected. Capillarity is also often avoided in relative permeability measurements in order to satisfy some flow equations. These notions have guided most laboratory core flooding experiments to be conducted in horizontal flow orientation, and the data obtained are as good as what the experiments tend to mimic. However, gravity effect plays a major role in gas liquid systems such as CO2 sequestration and some types of enhanced oil recovery techniques, particularly those involving gases, where large density difference exists between the fluid pair. In such cases, laboratory experiments conducted to derive relative permeability curves should take into consideration gravity effects and capillarity. Previous studies attribute directional dependence of relative permeability and residual saturations to rock anisotropy. It is shown in this study that rock permeability, residual saturation, and relative permeability depend on the interplay between gravity, capillarity, and viscous forces and also the direction of fluid flow even when the rock is isotropic. Rock samples representing different lithology and wide range of permeabilities were investigated through unsteady-state experiments covering drainage and imbibition in both vertical and horizontal flow directions. The experiments were performed at very low flow rates to capture capillarity. The results obtained showed that, for each homogeneous rock and for the same flow path along the core length

  5. Aerosol nucleation in an ultra-low ion density environment

    DEFF Research Database (Denmark)

    Pedersen, Jens Olaf Pepke; Enghoff, Martin Andreas Bødker; Paling, Sean M.

    2012-01-01

    Ion-induced nucleation has been studied in a deep underground ultra-low background radiation environment where the role of ions can be distinguished from alternative neutral aerosol nucleation mechanisms. Our results demonstrate that ions have a significant effect on the production of small...... sulfuric acid–water clusters over a range of sulfuric acid concentrations although neutral nucleation mechanisms remain evident at low ionization levels. The effect of ions is found both to enhance the nucleation rate of stable clusters and the initial growth rate. The effects of possible contaminations...

  6. Ultra-low-power short-range radios

    CERN Document Server

    Chandrakasan, Anantha

    2015-01-01

    This book explores the design of ultra-low-power radio-frequency integrated circuits (RFICs), with communication distances ranging from a few centimeters to a few meters. Such radios have unique challenges compared to longer-range, higher-powered systems. As a result, many different applications are covered, ranging from body-area networks to transcutaneous implant communications and Internet-of-Things devices. A mix of introductory and cutting-edge design techniques and architectures which facilitate each of these applications are discussed in detail. Specifically, this book covers:.

  7. A programmable ultra-low noise X-band exciter.

    Science.gov (United States)

    MacMullen, A; Hoover, L R; Justice, R D; Callahan, B S

    2001-07-01

    A programmable ultra-low noise X-band exciter has been developed using commercial off-the-shelf components. Its phase noise is more than 10 dB below the best available microwave synthesizers. It covers a 7% frequency band with 0.1-Hz resolution. The X-band output at +23 dBm is a combination of signals from an X-band sapphire-loaded cavity oscillator (SLCO), a low noise UHF frequency synthesizer, and special-purpose frequency translation and up-conversion circuitry.

  8. Note: Ultra-low birefringence dodecagonal vacuum glass cell

    Energy Technology Data Exchange (ETDEWEB)

    Brakhane, Stefan, E-mail: brakhane@iap.uni-bonn.de; Alt, Wolfgang; Meschede, Dieter; Robens, Carsten; Moon, Geol; Alberti, Andrea [Institut für Angewandte Physik, Universität Bonn, Wegelerstr. 8, D-53115 Bonn (Germany)

    2015-12-15

    We report on an ultra-low birefringence dodecagonal glass cell for ultra-high vacuum applications. The epoxy-bonded trapezoidal windows of the cell are made of SF57 glass, which exhibits a very low stress-induced birefringence. We characterize the birefringence Δn of each window with the cell under vacuum conditions, obtaining values around 10{sup −8}. After baking the cell at 150 °C, we reach a pressure below 10{sup −10} mbar. In addition, each window is antireflection coated on both sides, which is highly desirable for quantum optics experiments and precision measurements.

  9. GRABGAM Analysis of Ultra-Low-Level HPGe Gamma Spectra

    International Nuclear Information System (INIS)

    Winn, W.G.

    1999-01-01

    The GRABGAM code has been used successfully for ultra-low level HPGe gamma spectrometry analysis since its development in 1985 at Savannah River Technology Center (SRTC). Although numerous gamma analysis codes existed at that time, reviews of institutional and commercial codes indicated that none addressed all features that were desired by SRTC. Furthermore, it was recognized that development of an in-house code would better facilitate future evolution of the code to address SRTC needs based on experience with low-level spectra. GRABGAM derives its name from Gamma Ray Analysis BASIC Generated At MCA/PC

  10. Ultra-low-energy wide electron exposure unit

    International Nuclear Information System (INIS)

    Yonago, Akinobu; Oono, Yukihiko; Tokunaga, Kazutoshi; Kishimoto, Junichi; Wakamoto, Ikuo

    2001-01-01

    Heat and ultraviolet ray processes are used in surface dryness of paint, surface treatment of construction materials and surface sterilization of food containers. A process using a low-energy wide-area electron beam (EB) has been developed that features high speed and low drive cost. EB processing is not widespread in general industry, however, due to high equipment cost and difficult maintenance. We developed an ultra-low-energy wide-area electron beam exposure unit, the Mitsubishi Wide Electron Exposure Unit (MIWEL) to solve these problems. (author)

  11. GRABGAM Analysis of Ultra-Low-Level HPGe Gamma Spectra

    Energy Technology Data Exchange (ETDEWEB)

    Winn, W.G.

    1999-07-28

    The GRABGAM code has been used successfully for ultra-low level HPGe gamma spectrometry analysis since its development in 1985 at Savannah River Technology Center (SRTC). Although numerous gamma analysis codes existed at that time, reviews of institutional and commercial codes indicated that none addressed all features that were desired by SRTC. Furthermore, it was recognized that development of an in-house code would better facilitate future evolution of the code to address SRTC needs based on experience with low-level spectra. GRABGAM derives its name from Gamma Ray Analysis BASIC Generated At MCA/PC.

  12. Dielectric response of KCN crystals at ultra-low frequencies

    OpenAIRE

    Ziemath, Ervino C.; Aegerter, Michel A.; Slaets, J.

    1987-01-01

    We describe an ultra low frequency equipment employing programmable digital technique. The system is used to measure the dielectric parameters et, en and tg d or pure KCN crystals as a function of temperature in the frequency range 10-2 Hz to 40 Hz. The relaxation time of the Cn dipoles presents a classical temperature activated reorientation behaviour characterized by an Arrhenius law t=to exp (U/kT) with t0=7,26 x 10-15 s and U = 0,147 eV.

  13. Well Test Analysis of Naturally Fractured Vuggy Reservoirs with an Analytical Triple Porosity – Double Permeability Model and a Global Optimization Method

    Directory of Open Access Journals (Sweden)

    Gómez Susana

    2014-07-01

    Full Text Available The aim of this work is to study the automatic characterization of Naturally Fractured Vuggy Reservoirs via well test analysis, using a triple porosity-dual permeability model. The inter-porosity flow parameters, the storativity ratios, as well as the permeability ratio, the wellbore storage effect, the skin and the total permeability will be identified as parameters of the model. In this work, we will perform the well test interpretation in Laplace space, using numerical algorithms to transfer the discrete real data given in fully dimensional time to Laplace space. The well test interpretation problem in Laplace space has been posed as a nonlinear least squares optimization problem with box constraints and a linear inequality constraint, which is usually solved using local Newton type methods with a trust region. However, local methods as the one used in our work called TRON or the well-known Levenberg-Marquardt method, are often not able to find an optimal solution with a good fit of the data. Also well test analysis with the triple porosity-double permeability model, like most inverse problems, can yield multiple solutions with good match to the data. To deal with these specific characteristics, we will use a global optimization algorithm called the Tunneling Method (TM. In the design of the algorithm, we take into account issues of the problem like the fact that the parameter estimation has to be done with high precision, the presence of noise in the measurements and the need to solve the problem computationally fast. We demonstrate that the use of the TM in this study, showed to be an efficient and robust alternative to solve the well test characterization, as several optimal solutions, with very good match to the data were obtained.

  14. Ultra-low energy storage ring at FLAIR

    International Nuclear Information System (INIS)

    Welsch, Carsten P.; Papash, A. I.; Gorda, O.; Harasimowicz, J.; Karamyshev, O.; Karamysheva, G.; Newton, D.; Panniello, M.; Putignano, M.; Siggel-King, M. R. F.; Smirnov, A.

    2012-01-01

    The Ultra-low energy electrostatic Storage Ring (USR) at the future Facility for Low-energy Antiproton and Ion Research (FLAIR) will provide cooled beams of antiprotons in the energy range between 300 keV down to 20 keV and possibly less. The USR has been completely redesigned over the past three years. The ring structure is based on a “split achromat” lattice that allows in-ring experiments with internal gas jet target. Beam parameters might be adjusted in a wide range: from very short pulses in the nanosecond regime to a Coasting beam. In addition, a combined fast and slow extraction scheme was developed that allows for providing external experiments with cooled beams of different time structure. Detailed investigations of the USR, including studies into the ring’s long term beam dynamics, life time, equilibrium momentum spread and equilibrium lateral spread during collisions with an internal target were carried out. New tools and beam handling techniques for diagnostics of ultra-low energy ions at beam intensities less than 10 6 were developed by the QUASAR Group. In this paper, progress on the USR project will be presented with an emphasis on the expected beam parameters available to the experiments at FLAIR.

  15. Well pattern optimization in a low permeability sandstone reservoir: a case study from Erlian Basin in China

    Science.gov (United States)

    Wang, Xia; Fu, Lixia; Yan, Aihua; Guo, Fajun; Wu, Cong; Chen, Hong; Wang, Xinying; Lu, Ming

    2018-02-01

    Study on optimization of development well patterns is the core content of oilfield development and is a prerequisite for rational and effective development of oilfield. The study on well pattern optimization mainly includes types of well patterns and density of well patterns. This paper takes the Aer-3 fault block as an example. Firstly, models were built for diamond-shaped inverted 9-spot patterns, rectangular 5-spot patterns, square inverted 9-spot patterns and inverted 7-spot patterns under the same well pattern density to correlate the effect of different well patterns on development; secondly, comprehensive analysis was conducted to well pattern density in terms of economy and technology using such methods as oil reservoir engineering, numerical simulation, economic limits and economic rationality. Finally, the development mode of vertical well + horizontal well was presented according to the characteristics of oil reservoirs in some well blocks, which has realized efficient development of this fault block.

  16. Influence of clay and silica on permeability and capillary entry pressure of chalk reservoirs in the North Sea

    DEFF Research Database (Denmark)

    Røgen, Birte; Fabricius, Ida Lykke

    2002-01-01

    specific surface area. Fifty-nine Tor and Ekofisk Formation chalk samples from five North Sea chalk reservoirs were investigated. All contain quartz and clay minerals, most commonly kaolinite and smectite, with trace amounts of illite. The contents of calcite and quartz are inversely correlated and both......)): calcite between 0.5 and 3.5, quartz about 5, kaolinite about 15, and smectite about 60....

  17. Overview of naturally permeable fractured reservoirs in the central and southern Upper Rhine Graben: Insights from geothermal wells

    OpenAIRE

    Vidal , Jeanne; Genter , Albert

    2018-01-01

    International audience; Since the 1980′s, more than 15 geothermal wells have been drilled in the Upper Rhine Graben (URG), representing more than 60 km of drill length. Although some early concepts were related to purely matrix-porosity reservoirs or Hot Dry Rock systems, most projects in the URG are currently exploiting the geothermal resources that are trapped in fracture networks at the base of the sedimentary cover and in the granitic basement. Lessons-learnt from the European EGS referen...

  18. Chromatic dispersion effects in ultra-low coherence interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Lychagov, V V; Ryabukho, V P [N.G.Chernyshevsky Saratov State University (Russian Federation)

    2015-06-30

    We consider the properties of an interference signal shift from zero-path-difference position in the presence of an uncompensated dispersive layer in one of the interferometer arms. It is experimentally shown that in using an ultra-low coherence light source, the formation of the interference signal is also determined by the group velocity dispersion, which results in a nonlinear dependence of the position of the interference signal on the geometrical thickness of the dispersive layer. The discrepancy in the dispersive layer and compensator refractive indices in the third decimal place is experimentally shown to lead to an interference signal shift that is an order of magnitude greater than the pulse width. (interferometry)

  19. Ultra-low-head hydroelectric technology: A review

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Daqing; Deng, Zhiqun (Daniel)

    2017-10-01

    In recent years, distributed renewable energy-generation technologies, such as wind and solar, have developed rapidly. Nevertheless, the utilization of ultra-low-head (ULH) water energy (i.e., situations where the hydraulic head is less than 3 m or the water flow is more than 0.5 m/s with zero head) has received little attention. We believe that, through technological innovations and cost reductions, ULH hydropower has the potential to become an attractive, renewable, and sustainable resource. This paper investigates potential sites for ULH energy resources, the selection of relevant turbines and generators, simplification of civil works, and project costs. This review introduces the current achievements on ULH hydroelectric technology to stimulate discussions and participation of stakeholders to develop related technologies for further expanding its utilization as an important form of renewable energy.

  20. Ultra-low dispersion spectroscopy of stars and galaxies

    International Nuclear Information System (INIS)

    Bappu, M.K.V.; Parthasarathy, M.

    1977-01-01

    Application of ultra-low dispersion spectroscopy 10,000 A mm - 1 , is described to study the nuclei of elliptical galaxies, the quasi-stellar objects and for the discovery of faint OB stars, reddened stars and red stars. The instrument used is an f/2 slitless spectrograph with a three degree quartz prism at the Cassegrain focus of the 102-cm Ritchey-Chratien reflector at Kavalur. The spectra cover a field of 40 minutes of arc and the dispersion is 10,000 A mm - 1 . Ultra-low dispersion spectra (microspectra) were obtained for fifteen elliptical and three SO galaxies from the list of Ekers and Ekers (1973) who classified them as compact and extended sources from the observations of radio emission at 6 cms. From an analysis of micro-spectra and from direct photographs with graded exposure times, it is found that all compact radio galaxies in the Ekers list also have optically compact nuclei. Some of these elliptical galaxies with compact nuclei show enhancement of intensity in the blue violet region. From an examination of microspectra of forty-three of the known quasi-stellar objects of different redshifts it is found that the most striking characteristic of the spectra is their flat appearance. This characteristic flatness is also noticed in the microspectrum of the large redshift quasi-stellar objects like OH 471 and OQ 172 which do not have UV excess. Because of this characteristic difference in the appearance of the microspectra of the quasi-stellar objects and stellar objects, it is possible to detect new OSO's with this technique. An application of this technique to detect red stars in our galaxy and in the Large Magellanic cloud is discussed. (author)

  1. Ultra-low pollutant emission combustion method and apparatus

    International Nuclear Information System (INIS)

    Khinkis, M.J.

    1992-01-01

    This patent describes a method for ultra-low pollutant emission combustion of fossil fuel. It comprises: introducing into a primary combustion chamber a first fuel portion of about 1 percent to about 20 percent of a total fuel to be combusted; introducing primary combustion air into the primary combustion chamber; introducing a first portion of water into the primary combustion chamber, having a first water heat capacity equivalent to a primary combustion air heat capacity of one of a primary combustion air amount of about 10 percent to about 60 percent of the first stoichiometirc requirement for complete combustion of the first fuel portion and an excess primary combustion air amount of about 20 percent to about 150 percent of the first stoichiometric requirement for complete combustion of the first fuel portion; burning the first fuel portion with the primary combustion air in the primary combustion chamber at a temperature abut 2000 degrees F to about 2700 degrees F producing initial combustion products; passing the initial combustion products into a secondary combustion chamber; introducing into the secondary combustion chamber a second fuel portion of about 80 percent to about 99 percent of the total fuel to be combusted; introducing secondary combustion air into the secondary combustion chamber in an amount of about 105 percent to about 130 percent of a second stoichiometric requirement for complete combustion of the second fuel portion; introducing a second portion of water into the secondary combustion chamber; burning the second fuel portion and any remaining fuel in the initial combustion products; passing the final combustion products into a dilution chamber; introducing dilution air into the dilution chamber; discharging the ultra-low pollutant emission vitiated air form the dilution chamber

  2. Advanced Durable Flexible Ultra Low Outgassing Thermal Control Coatings for NASA Science Missions, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This Phase I program proposes to synthesize novel nanoengineered ultra low out gassing elastomers and formulate high temperature capable flexible thermal control...

  3. Ultra-low power integrated circuit design circuits, systems, and applications

    CERN Document Server

    Li, Dongmei; Wang, Zhihua

    2014-01-01

    This book describes the design of CMOS circuits for ultra-low power consumption including analog, radio frequency (RF), and digital signal processing circuits (DSP). The book addresses issues from circuit and system design to production design, and applies the ultra-low power circuits described to systems for digital hearing aids and capsule endoscope devices. Provides a valuable introduction to ultra-low power circuit design, aimed at practicing design engineers; Describes all key building blocks of ultra-low power circuits, from a systems perspective; Applies circuits and systems described to real product examples such as hearing aids and capsule endoscopes.

  4. Ultra Low Air and H2 Permeability Cryogenic Bladder Materials for Inflatable Habitats, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — NanoSonic has recently developed a hydrogen (H2) dispenser hose to realize H2 as a safe, reliable, and cost competitive replacement for gasoline. NanoSonic's...

  5. Oil recovery enhancement from fractured, low permeability reservoirs. Annual report, October 1, 1990--September 31, 1991, Annex 4

    Energy Technology Data Exchange (ETDEWEB)

    Poston, S.W.

    1991-01-01

    The results of the investigative efforts for this jointly funded DOE-State of Texas research project achieved during the 1990-1991 year may be summarized as follows: Geological Characterization - Detailed maps of the development and hierarchical nature the fracture system exhibited by Austin Chalk outcrops were prepared. The results of these efforts were directly applied to the development of production decline type curves applicable to a dual-fracture-matrix flow system. Analysis of production records obtained from Austin Chalk operators illustrated the utility of these type curves to determine relative fracture/matrix contributions and extent. Well-log response in Austin Chalk wells has been shown to be a reliable indicator of organic maturity. Shear-wave splitting concepts were used to estimate fracture orientations from Vertical Seismic Profile, VSP data. Several programs were written to facilitate analysis of the data. The results of these efforts indicated fractures could be detected with VSP seismic methods.Development of the EOR Imbibition Process - Laboratory displacement as well as Magnetic Resonance Imaging, MRI and Computed Tomography, CT imaging studies have shown the carbonated water-imbibition displacement process significantly accelerates and increases recovery from oil saturated, low permeability rocks.Field Tests - Two operators amenable to conducting a carbonated water flood test on an Austin Chalk well have been identified. Feasibility studies are presently underway.

  6. Experiments on Quantum Hall Topological Phases in Ultra Low Temperatures

    International Nuclear Information System (INIS)

    Du, Rui-Rui

    2015-01-01

    This project is to cool electrons in semiconductors to extremely low temperatures and to study new states of matter formed by low-dimensional electrons (or holes). At such low temperatures (and with an intense magnetic field), electronic behavior differs completely from ordinary ones observed at room temperatures or regular low temperature. Studies of electrons at such low temperatures would open the door for fundamental discoveries in condensed matter physics. Present studies have been focused on topological phases in the fractional quantum Hall effect in GaAs/AlGaAs semiconductor heterostructures, and the newly discovered (by this group) quantum spin Hall effect in InAs/GaSb materials. This project consists of the following components: 1) Development of efficient sample cooling techniques and electron thermometry: Our goal is to reach 1 mK electron temperature and reasonable determination of electron temperature; 2) Experiments at ultra-low temperatures: Our goal is to understand the energy scale of competing quantum phases, by measuring the temperature-dependence of transport features. Focus will be placed on such issues as the energy gap of the 5/2 state, and those of 12/5 (and possible 13/5); resistive signature of instability near 1/2 at ultra-low temperatures; 3) Measurement of the 5/2 gaps in the limit of small or large Zeeman energies: Our goal is to gain physics insight of 5/2 state at limiting experimental parameters, especially those properties concerning the spin polarization; 4) Experiments on tuning the electron-electron interaction in a screened quantum Hall system: Our goal is to gain understanding of the formation of paired fractional quantum Hall state as the interaction pseudo-potential is being modified by a nearby screening electron layer; 5) Experiments on the quantized helical edge states under a strong magnetic field and ultralow temperatures: our goal is to investigate both the bulk and edge states in a quantum spin Hall insulator under

  7. Optimization of ultra-low-power CMOS transistors

    International Nuclear Information System (INIS)

    Stockinger, M.

    2000-01-01

    Ultra-low-power CMOS integrated circuits have constantly gained importance due to the fast growing portable electronics market. High-performance applications like mobile telephones ask for high-speed computations and low stand-by power consumption to increase the actual operating time. This means that transistors with low leakage currents and high drive currents have to be provided. Common fabrication methods will soon reach their limits if the on-chip feature size of CMOS technology continues to shrink at this very fast rate. New device architectures will help to keep track with the roadmap of the semiconductor industry. Especially doping profiles offer much freedom for performance improvements as they determine the 'inner functioning' of a transistor. In this work automated doping profile optimization is performed on MOS transistors within the TCAD framework SIESTA. The doping between and under the source/drain wells is discretized on an orthogonal optimization grid facilitating almost arbitrary two-dimensional shapes. A linear optimizer issued to find the optimum doping profile by variation of the doping parameters utilizing numerical device simulations with MINIMOS-NT. Gaussian functions are used in further optimization runs to make the doping profiles smooth. Two device generations are considered, one with 0.25 μm, the other with 0.1 μm gate length. The device geometries and source/drain doping profiles are kept fixed during optimization and supply voltages are chosen suitable for ultra-low-power purposes. In a first optimization study the drive current of NMOS transistors is maximized while keeping the leakage current below a limit of 1 pA/μm. This results in peaking channel doping devices (PCD) with narrow doping peaks placed asymmetrically in the channel. Drive current improvements of 45 % and 71 % for the 0.25 μm and 0.1 μm devices, respectively, are achieved compared to uniformly doped devices. The PCD device is studied in detail and explanations for

  8. The Multi-Porosity Multi-Permeability and Electrokinetic Natures of Shales and Their Effects in Hydraulic Fracturing of Unconventional Shale Reservoirs

    Science.gov (United States)

    Liu, C.; Hoang, S. K.; Tran, M. H.; Abousleiman, Y. N.

    2013-12-01

    Imaging studies of unconventional shale reservoir rocks have recently revealed the multi-porosity multi-permeability nature of these intricate formations. In particular, the porosity spectrum of shale reservoir rocks often comprises of the nano-porosity in the organic matters, the inter-particle micro-porosity, and the macroscopic porosity of the natural fracture network. Shale is also well-known for its chemically active behaviors, especially shrinking and swelling when exposed to aqueous solutions, as the results of pore fluid exchange with external environment due to the difference in electro-chemical potentials. In this work, the effects of natural fractures and electrokinetic nature of shale on the formation responses during hydraulic fracturing are examined using the dual-poro-chemo-electro-elasticity approach which is a generalization of the classical Biot's poroelastic formulation. The analyses show that the presence of natural fractures can substantially increase the leak-off rate of fracturing fluid into the formation and create a larger region of high pore pressure near the fracture face as shown in Fig.1a. Due to the additional fluid invasion, the naturally fractured shale swells up more and the fracture aperture closes faster compared to an intrinsically low permeability non-fractured shale formation as shown in Fig.1b. Since naturally fractured zones are commonly targeted as pay zones, it is important to account for the faster fracture closing rate in fractured shales in hydraulic fracturing design. Our results also show that the presence of negative fixed charges on the surface of clay minerals creates an osmotic pressure at the interface of the shale and the external fluid as shown in Fig.1c. This additional Donnan-induced pore pressure can result in significant tensile effective stresses and tensile damage in the shale as shown in Fig.1d. The induced tensile damage can exacerbate the problem of proppant embedment resulting in more fracture closure

  9. Ultra low-power integrated circuit design for wireless neural interfaces

    CERN Document Server

    Holleman, Jeremy; Otis, Brian

    2014-01-01

    Presenting results from real prototype systems, this volume provides an overview of ultra low-power integrated circuits and systems for neural signal processing and wireless communication. Topics include analog, radio, and signal processing theory and design for ultra low-power circuits.

  10. Oil recovery enhancement from fractured, low permeability reservoirs. Part 2, Annual report, October 1, 1990--September 31, 1991

    Energy Technology Data Exchange (ETDEWEB)

    Poston, S.W.

    1991-12-31

    The results of the investigative efforts for this jointly funded DOE-State of Texas research project achieved during the 1990--1991 year may be summarized as follows: Geological Characterization -- Detailed maps of the development and hierarchical nature the fracture system exhibited by Austin Chalk outcrops were prepared. These results of these efforts were directly applied to the development of production decline type curves applicable to a dual fracture-matrix flow system. Analysis of production records obtained from Austin Chalk operators illustrated the utility of these type curves to determine relative fracture/matrix contributions and extent. Well-log response in Austin Chalk wells has been shown to be a reliable indicator of organic maturity. (VSP) Vertical-Seismic Profile data was used to use shear-wave splitting concepts to estimate fracture orientations. Several programs were to be written to facilitate analysis of the data. The results of these efforts indicated fractures could be detected with VSP seismic methods. Development of the (EOR) Enhanced Oil Recovery Imbibition Process -- Laboratory displacement as well as MRI and CT imaging studies have shown the carbonated water-imbibition displacement process significantly accelerates and increases recovery of an oil saturated, low permeability core material, when compared to that of a normal brine imbibition displacement process. A study of oil recovery by the application of a cyclic carbonated water imbibition process, followed by reducing the pressure below the bubble point of the CO{sub 2}-water solution, indicated the possibility of alternate and new enhanced recovery method. The installation of an artificial solution gas drive significantly increased oil recovery. The extent and arrangement of micro-fractures in Austin Chalk horizontal cores was mapped with CT scanning techniques. The degree of interconnection of the micro-fractures was easily visualized.

  11. Morphology of Burned Ultra-low Density Fiberboards

    Directory of Open Access Journals (Sweden)

    Min Niu

    2015-09-01

    Full Text Available The synergistic effect of two fire retardants, a Si-Al compound and chlorinated paraffin, was tested on ultra-low density fiberboards (ULDFs. To further understand the mechanism of fire retardancy, morphologies of unburned and burned ULDFs were studied using a scanning electron microscope with energy dispersive spectroscopy. It was found that as the volume of the burned ULDFs shrank, some crevices appeared. In addition, less fly ash formed on the top of specimens, and more bottom ashes remained in the original framework, with a clear network of structure built by the fibers. Carbon was almost absent in the fly ash; however, the weight ratio of C in the bottom ashes reached the maximum (> 43% of the composition. Oxygen, Al, and Si appeared to have varying weight ratios for different ashes. Oxygen content increased with increasing Si and Al contents. Furthermore, Cl sharply decreased to less than 1% after combustion. Therefore, upon combustion, it was found that almost all of the substances in ULDFs, except for the Si-Al compound, were pyrolyzed to volatile carbon oxides and Cl compounds, especially the fly ash and lightweight C compounds.

  12. Ultra low power signal oriented approach for wireless health monitoring.

    Science.gov (United States)

    Marinkovic, Stevan; Popovici, Emanuel

    2012-01-01

    In recent years there is growing pressure on the medical sector to reduce costs while maintaining or even improving the quality of care. A potential solution to this problem is real time and/or remote patient monitoring by using mobile devices. To achieve this, medical sensors with wireless communication, computational and energy harvesting capabilities are networked on, or in, the human body forming what is commonly called a Wireless Body Area Network (WBAN). We present the implementation of a novel Wake Up Receiver (WUR) in the context of standardised wireless protocols, in a signal-oriented WBAN environment and present a novel protocol intended for wireless health monitoring (WhMAC). WhMAC is a TDMA-based protocol with very low power consumption. It utilises WBAN-specific features and a novel ultra low power wake up receiver technology, to achieve flexible and at the same time very low power wireless data transfer of physiological signals. As the main application is in the medical domain, or personal health monitoring, the protocol caters for different types of medical sensors. We define four sensor modes, in which the sensors can transmit data, depending on the sensor type and emergency level. A full power dissipation model is provided for the protocol, with individual hardware and application parameters. Finally, an example application shows the reduction in the power consumption for different data monitoring scenarios.

  13. Assembly techniques for ultra-low mass drift chambers

    International Nuclear Information System (INIS)

    Assiro, R.; Cascella, M.; Grancagnolo, F.; L'Erario, A.; Miccoli, A.; Rella, S.; Spedicato, M.; Tassielli, G.

    2014-01-01

    We presents a novel technique for the fast assembly of next generation ultra low mass drift chambers offering space point resolution of the order of 100 μm and high tolerance to pile-up. The chamber design has been developed keeping in mind the requirements for the search of rare processes: high resolutions (order of 100–200 KeV/c) for particles momenta in a range (50–100 MeV/c) totally dominated by the multiple scattering contribution (e.g., muon and kaon decay experiment such as MEG at PSI and Mu2e and ORKA at Fermilab). We describe a novel wiring strategy enabling the semiautomatic wiring of a complete layer with a high degree of control over wire tension and position. We also present feed-through-less wire anchoring system. These techniques have been already implemented at INFN-Lecce in the construction of a prototype drift chamber to be soon tested with cosmic rays and particle beams

  14. Assembly techniques for ultra-low mass drift chambers

    Science.gov (United States)

    Assiro, R.; Cascella, M.; Grancagnolo, F.; L'Erario, A.; Miccoli, A.; Rella, S.; Spedicato, M.; Tassielli, G.

    2014-03-01

    We presents a novel technique for the fast assembly of next generation ultra low mass drift chambers offering space point resolution of the order of 100 μm and high tolerance to pile-up. The chamber design has been developed keeping in mind the requirements for the search of rare processes: high resolutions (order of 100-200 KeV/c) for particles momenta in a range (50-100 MeV/c) totally dominated by the multiple scattering contribution (e.g., muon and kaon decay experiment such as MEG at PSI and Mu2e and ORKA at Fermilab). We describe a novel wiring strategy enabling the semiautomatic wiring of a complete layer with a high degree of control over wire tension and position. We also present feed-through-less wire anchoring system. These techniques have been already implemented at INFN-Lecce in the construction of a prototype drift chamber to be soon tested with cosmic rays and particle beams.

  15. Ultra Low Friction of DLC Coating with Lubricant

    International Nuclear Information System (INIS)

    Kano, M; Yoshida, K

    2010-01-01

    The objective of this study was to find a trigger to make clear a mechanism of the ultra low friction by evaluating the friction property of DLC-DLC combination under lubrication with the simple fluid. The Pin-on-disc reciprocating and rotating sliding tests were conducted to evaluate the friction property. The super low friction property of pure sliding with the ta-C(T) pair coated by the filtered arc deposition process under oleic acid lubrication was found at the mixed lubrication condition. It was thought that the low share strength tribofilm composed of water and acid seemed to be formed on ta-C sliding interface. Additionally, the smooth sliding surface formed on ta-C(T) was seemed to be required to keep this tribofilm. Then, the super low friction was thought to be obtained by this superlubrication condition. Although the accurate and direct experimental data must be required to make clear this super low friction mechanism, the advanced effect obtained by the simple material combination is expected to be applied on the large industrial fields in near future.

  16. Ultra-low noise miniaturized neural amplifier with hardware averaging.

    Science.gov (United States)

    Dweiri, Yazan M; Eggers, Thomas; McCallum, Grant; Durand, Dominique M

    2015-08-01

    Peripheral nerves carry neural signals that could be used to control hybrid bionic systems. Cuff electrodes provide a robust and stable interface but the recorded signal amplitude is small (concept of hardware averaging to nerve recordings obtained with cuff electrodes. An optimization procedure is developed to minimize noise and power simultaneously. The novel design was based on existing neural amplifiers (Intan Technologies, LLC) and is validated with signals obtained from the FINE in chronic dog experiments. We showed that hardware averaging leads to a reduction in the total recording noise by a factor of 1/√N or less depending on the source resistance. Chronic recording of physiological activity with FINE using the presented design showed significant improvement on the recorded baseline noise with at least two parallel operation transconductance amplifiers leading to a 46.1% reduction at N = 8. The functionality of these recordings was quantified by the SNR improvement and shown to be significant for N = 3 or more. The present design was shown to be capable of generating hardware averaging on noise improvement for neural recording with cuff electrodes, and can accommodate the presence of high source impedances that are associated with the miniaturized contacts and the high channel count in electrode arrays. This technique can be adopted for other applications where miniaturized and implantable multichannel acquisition systems with ultra-low noise and low power are required.

  17. Correlated electron phenomena in ultra-low disorder quantum wires

    International Nuclear Information System (INIS)

    Reilly, D.J.; Facer, G.R.; Dzurak, A.S.; Kane, B.E.; Clark, R.G.; Lumpkin, N.E.

    1999-01-01

    Full text: Quantum point contacts in the lowest disorder HEMTs display structure at 0.7 x 2e 2 /h, which cannot be interpreted within a single particle Landauer model. This structure has been attributed to a spontaneous spin polarisation at zero B field. We have developed novel GaAs/AlGaAs enhancement mode FETs, which avoid the random impurity potential present in conventional MODFET devices by using epitaxially grown gates to produce ultra-low-disorder QPCs and quantum wires using electron beam lithography. The ballistic mean free path within these devices exceeds 160 μm 2 . Quantum wires of 5 μm in length show up to 15 conductance plateaux, indicating that these may be the lowest-disorder quantum wires fabricated using conventional surface patterning techniques. These structures are ideal for the study of correlation effects in QPCs and quantum wires as a function of electron density. Our data provides strong evidence that correlation effects are enhanced as the length of the 1D region is increased and also that additional structure moves close to 0.5 x 2e 2 /h, the value expected for an ideal spin-split 1D level

  18. Investigating Ultra-low Velocity Zones beneath the Southwestern Pacific

    Science.gov (United States)

    Carson, S. E.; Hansen, S. E.; Garnero, E.

    2017-12-01

    The core mantle boundary (CMB), where the solid silicate mantle meets the liquid iron-nickel outer core, represents the largest density contrast on our planet, and it has long been recognized that the CMB is associated with significant structural heterogeneities. One CMB structure of particular interest are ultra low-velocity zones (ULVZs), laterally-varying, 5-50 km thick isolated patches seen in some locations just above the CMB that are associated with increased density and reduced seismic wave velocities. These variable characteristics have led to many questions regarding ULVZ origins, but less than 40% of the CMB has been surveyed for the presence of ULVZs given limited seismic coverage of the lowermost mantle. Therefore, investigations that sample the CMB with new geometries are critical to further our understanding of ULVZs and their potential connection to other deep Earth processes. The Transantarctic Mountains Northern Network (TAMNNET), a 15-station seismic array that was recently deployed in Antarctica, provides a unique dataset to further study ULVZ structure with new and unique path geometry. Core-reflected ScP and PcP phases from the TAMNNET dataset particularly well sample the CMB in the vicinity of New Zealand in the southwestern Pacific, providing coverage between an area to the north where ULVZ structure has been previously identified and another region to the south, which shows no ULVZ evidence. By identifying and modeling pre- and post-cursor ScP and PcP energy, we are exploring a new portion of the CMB with a goal of better understanding potential ULVZ origins. Our study area also crosses the southern boundary of the Pacific Large Low Shear Velocity Province (LLSVP); therefore, our investigations may allow us to examine the possible relationship between LLSVPs and ULVZs.

  19. Ultra-low field MRI food inspection system prototype

    Energy Technology Data Exchange (ETDEWEB)

    Kawagoe, Satoshi, E-mail: s133413@edu.tut.ac.jp; Toyota, Hirotomo; Hatta, Junichi; Ariyoshi, Seiichiro; Tanaka, Saburo, E-mail: tanakas@ens.tut.ac.jp

    2016-11-15

    Highlights: • We have developed a ULF-MRI system using HTS-SQUID for food inspection. • We developed a compact magnetically shielded box to attenuate environmental noise. • The 2D-MR image was reconstructed from the grid processing data using 2D-FFT method. • The 2D-MR images of a disk-shaped and a multiple cell water sample were obtained. • The results showed the possibility of applying the ULF-MRI system to food inspection. - Abstract: We develop an ultra-low field (ULF) magnetic resonance imaging (MRI) system using a high-temperature superconducting quantum interference device (HTS-SQUID) for food inspection. A two-dimensional (2D)-MR image is reconstructed from the grid processing raw data using the 2D fast Fourier transform method. In a previous study, we combined an LC resonator with the ULF-MRI system to improve the detection area of the HTS-SQUID. The sensitivity was improved, but since the experiments were performed in a semi-open magnetically shielded room (MSR), external noise was a problem. In this study, we develop a compact magnetically shielded box (CMSB), which has a small open window for transfer of a pre-polarized sample. Experiments were performed in the CMSB and 2D-MR images were compared with images taken in the semi-open MSR. A clear image of a disk-shaped water sample is obtained, with an outer dimension closer to that of the real sample than in the image taken in the semi-open MSR. Furthermore, the 2D-MR image of a multiple cell water sample is clearly reconstructed. These results show the applicability of the ULF-MRI system in food inspection.

  20. Ultra low carbon bainitic (ULCB) steels after quenching and tempering

    International Nuclear Information System (INIS)

    Lis, A.K.; Lis, J.; Kolan, C.; Jeziorski, L.

    1998-01-01

    The mechanical and Charpy V impact strength properties of new advanced ultra low carbon bainitic (ULBC) steels after water quenching and tempering (WQT) have been investigated. Their chemical compositions are given. The nine continuous cooling transformation diagrams (CCT) of the new ULCB steel grades have been established. The CCT diagrams for ULCB N i steels containing 9% Ni - grade 10N9 and 5% Ni - grade HN5MVNb are given. The comparison between CCT diagrams of 3.5%Ni + 1.5%Cu containing steels grade HSLA 100 and HN3MCu is shown. The effect of the increase in carbon and titanium contents in the chemical composition of ULCB M n steels 04G3Ti, 06G3Ti and 09G3Ti on the kinetics of phase transformations during continuous cooling is presented by the shifting CCT diagrams. The Charpy V impact strength and brittle fracture occurence curves are shown. The effect of tempering temperature on tensile properties of WQT HN3MCu steel is shown and Charpy V impact strength curves after different tempering conditions are shown. The optimum tempering temperatures region of HN3MCu steel for high Charpy V impact toughness at law temperatures - 80 o C(193 K) and -120 o C(153 K) is estimated. The effect of tempering temperature on mechanical properties of HN5MVNb steel is given. The low temperature impact Charpy V toughness of HN5MVNb steel is shown. The optimum range of tempering temperature during 1 hour for high toughness of WQT HN5MVNb steel is given. HN3MCu and HN5MVNb steels after WQT have high yield strength YS≥690 MPa and high Charpy V impact toughness KV≥80 J at -100 o C (173K) and KCV≥50 J/cm 2 at - 120 o C (153K) so they may be used for cryogenic applications

  1. Ultra Low Sulfur Home Heating Oil Demonstration Project

    Energy Technology Data Exchange (ETDEWEB)

    Batey, John E. [Energy Research Center, Inc., Easton, CT (United States); McDonald, Roger [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-09-30

    This Ultra Low Sulfur (ULS) Home Heating Oil Demonstration Project was funded by the New York State Energy Research and Development Authority (NYSERDA) and has successfully quantified the environmental and economic benefits of switching to ULS (15 PPM sulfur) heating oil. It advances a prior field study of Low Sulfur (500 ppm sulfur) heating oil funded by NYSERDA and laboratory research conducted by Brookhaven National Laboratory (BNL) and Canadian researchers. The sulfur oxide and particulate matter (PM) emissions are greatly reduced as are boiler cleaning costs through extending cleaning intervals. Both the sulfur oxide and PM emission rates are directly related to the fuel oil sulfur content. The sulfur oxide and PM emission rates approach near-zero levels by switching heating equipment to ULS fuel oil, and these emissions become comparable to heating equipment fired by natural gas. This demonstration project included an in-depth review and analysis of service records for both the ULS and control groups to determine any difference in the service needs for the two groups. The detailed service records for both groups were collected and analyzed and the results were entered into two spreadsheets that enabled a quantitative side-by-side comparison of equipment service for the entire duration of the ULS test project. The service frequency for the ULS and control group were very similar and did indicate increased service frequency for the ULS group. In fact, the service frequency with the ULS group was slightly less (7.5 percent) than the control group. The only exception was that three burner fuel pump required replacement for the ULS group and none were required for the control group.

  2. System and method for magnetic current density imaging at ultra low magnetic fields

    Science.gov (United States)

    Espy, Michelle A.; George, John Stevens; Kraus, Robert Henry; Magnelind, Per; Matlashov, Andrei Nikolaevich; Tucker, Don; Turovets, Sergei; Volegov, Petr Lvovich

    2016-02-09

    Preferred systems can include an electrical impedance tomography apparatus electrically connectable to an object; an ultra low field magnetic resonance imaging apparatus including a plurality of field directions and disposable about the object; a controller connected to the ultra low field magnetic resonance imaging apparatus and configured to implement a sequencing of one or more ultra low magnetic fields substantially along one or more of the plurality of field directions; and a display connected to the controller, and wherein the controller is further configured to reconstruct a displayable image of an electrical current density in the object. Preferred methods, apparatuses, and computer program products are also disclosed.

  3. An experimental study of relative permeability hysteresis, capillary trapping characteristics, and capillary pressure of CO2/brine systems at reservoir conditions

    Science.gov (United States)

    Akbarabadi, Morteza

    We present the results of an extensive experimental study on the effects of hysteresis on permanent capillary trapping and relative permeability of CO2/brine and supercritical (sc)CO2+SO2/brine systems. We performed numerous unsteady- and steady-state drainage and imbibition full-recirculation flow experiments in three different sandstone rock samples, i.e., low and high-permeability Berea, Nugget sandstones, and Madison limestone carbonate rock sample. A state-of-the-art reservoir conditions core-flooding system was used to perform the tests. The core-flooding apparatus included a medical CT scanner to measure in-situ saturations. The scanner was rotated to the horizontal orientation allowing flow tests through vertically-placed core samples with about 3.8 cm diameter and 15 cm length. Both scCO2 /brine and gaseous CO2 (gCO2)/brine fluid systems were studied. The gaseous and supercritical CO2/brine experiments were carried out at 3.46 and 11 MPa back pressures and 20 and 55°C temperatures, respectively. Under the above-mentioned conditions, the gCO2 and scCO2 have 0.081 and 0.393 gr/cm3 densities, respectively. During unsteady-state tests, the samples were first saturated with brine and then flooded with CO2 (drainage) at different maximum flow rates. The drainage process was then followed by a low flow rate (0.375 cm 3/min) imbibition until residual CO2 saturation was achieved. Wide flow rate ranges of 0.25 to 20 cm3/min for scCO2 and 0.125 to 120 cm3min for gCO2 were used to investigate the variation of initial brine saturation (Swi) with maximum CO2 flow rate and variation of trapped CO2 saturation (SCO2r) with Swi. For a given Swi, the trapped scCO2 saturation was less than that of gCO2 in the same sample. This was attributed to brine being less wetting in the presence of scCO2 than in the presence of gCO 2. During the steady-state experiments, after providing of fully-brine saturated core, scCO2 was injected along with brine to find the drainage curve and as

  4. Experiences of ultra-low-crud high-nickel control in Onagawa nuclear power station

    International Nuclear Information System (INIS)

    Saito, M.; Goto, Y.; Shinomiya, T.; Sato, M.; Yamazaki, K.; Hirasawa, H.; Yotsuyanagi, T.

    2002-01-01

    We have adopted various countermeasures for worker dose reduction to plants in Onagawa Nuclear Power Station. ''Ni/Fe ratio control'' has been adopted to Unit 1, and ''ultra-low-crud high-nickel control'' has been adopted to Unit 2 and 3, along with other countermeasures like wide utilization of low Co materials, for the purpose of dose rate reduction of primary recirculation piping which is thought to be one of the main exposure sources. In this paper, we describe, first, the reason and background that ultra-low-crud high-nickel control has been adopted to Unit 2, and, second, water chemistry of Unit 2 up to the 5. cycle under ultra-low-crud high-nickel control compared to that of Unit 1 under Ni/Fe ratio control. Following those, we show brief analysis of the fuel crud of Unit 2 and water chemistry of Unit 3 only at the startup stage. (authors)

  5. Ultra-low loss nano-taper coupler for Silicon-on-Insulator ridge waveguide

    DEFF Research Database (Denmark)

    Pu, Minhao; Liu, Liu; Ou, Haiyan

    2010-01-01

    A nano-taper coupler is optimized specially for the transverse-magnetic mode for interfacing light between a silicon-on-insulator ridge waveguide and a single-mode fiber. An ultra-low coupling loss of ~0.36dB is achieved for the nano-taper coupler.......A nano-taper coupler is optimized specially for the transverse-magnetic mode for interfacing light between a silicon-on-insulator ridge waveguide and a single-mode fiber. An ultra-low coupling loss of ~0.36dB is achieved for the nano-taper coupler....

  6. An ultra-low-power CMOS temperature sensor for RFID applications

    International Nuclear Information System (INIS)

    Xu Conghui; Gao Peijun; Che Wenyi; Tan Xi; Yan Na; Min Hao

    2009-01-01

    An ultra-low-power CMOS temperature sensor with analog-to-digital readout circuitry for RFID applications was implemented in a 0.18-μm CMOS process. To achieve ultra-low power consumption, an error model is proposed and the corresponding novel temperature sensor front-end with a new double-measure method is presented. Analog-to-digital conversion is accomplished by a sigma-delta converter. The complete system consumes only 26 μA and 1.8 V for continuous operation and achieves an accuracy of ±0.65 deg. C from -20 to 120 deg. C after calibration at one temperature.

  7. Ultra-low coupling loss fully-etched apodized grating coupler with bonded metal mirror

    DEFF Research Database (Denmark)

    Ding, Yunhong; Peucheret, Christophe; Ou, Haiyan

    2014-01-01

    A fully etched apodized grating coupler with bonded metal mirror is designed and demonstrated on the silicon-on-insulator platform, showing an ultra-low coupling loss of only 1.25 dB with 3 dB bandwidth of 69 nm.......A fully etched apodized grating coupler with bonded metal mirror is designed and demonstrated on the silicon-on-insulator platform, showing an ultra-low coupling loss of only 1.25 dB with 3 dB bandwidth of 69 nm....

  8. Advanced Technology for Ultra-Low Power System-on-Chip (SoC)

    Science.gov (United States)

    2017-06-01

    was proposed for lower power applications with Ioff=10pA/μm and VDD=0.5V. In this project, the optimized structure shows great potential in both Lg...AFRL-RY-WP-TR-2017-0115 ADVANCED TECHNOLOGY FOR ULTRA-LOW POWER SYSTEM-ON-CHIP (SoC) Jason Woo, Weicong Li, and Peng Lu University of California...September 2015 – 31 March 2017 4. TITLE AND SUBTITLE ADVANCED TECHNOLOGY FOR ULTRA-LOW POWER SYSTEM-ON- CHIP (SoC) 5a. CONTRACT NUMBER FA8650-15-1-7574 5b

  9. An ultra-low-power CMOS temperature sensor for RFID applications

    Energy Technology Data Exchange (ETDEWEB)

    Xu Conghui; Gao Peijun; Che Wenyi; Tan Xi; Yan Na; Min Hao, E-mail: yanna@fudan.edu.c [State Key Laboratory of ASIC and System, Fudan University, Shanghai 201203 (China)

    2009-04-15

    An ultra-low-power CMOS temperature sensor with analog-to-digital readout circuitry for RFID applications was implemented in a 0.18-mum CMOS process. To achieve ultra-low power consumption, an error model is proposed and the corresponding novel temperature sensor front-end with a new double-measure method is presented. Analog-to-digital conversion is accomplished by a sigma-delta converter. The complete system consumes only 26 muA and 1.8 V for continuous operation and achieves an accuracy of +-0.65 deg. C from -20 to 120 deg. C after calibration at one temperature.

  10. Stimulatory and protective effects of alkylating agents applied in ultra-low concentrations.

    Science.gov (United States)

    Pukhalsky, A L; Shmarina, G V

    2001-01-01

    Alkylating drugs belonging to the nitrogen mustard family are known as cytostatic and immunosuppressive agents. Ultra-low doses of these drugs may demonstrate pharmacological effects unlike this category of drugs. In the case of a gradual dose decrease, the number of targets for alkylation is also reduced and the drug switches from cytostatic to cell growth modifier. We postulate that application of ultra-low doses of alkylating drugs may result in a beneficial effect in the therapy of diseases associated with chronic inflammation of the mucosa, especially with the signs of epithelial atrophy. Copyright 2001 S. Karger AG, Basel

  11. Drag reduction in reservoir rock surface: Hydrophobic modification by SiO{sub 2} nanofluids

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Yong-Li, E-mail: yylhill@163.com [College of Chemistry & Chemical Engineering, Xi’an Shiyou University, Xi’an 710065 (China); Cui, Ming-Yue; Jiang, Wei-Dong; He, An-Le; Liang, Chong [Langfang Branch of Research Institute of Petroleum Exploration & Development, Langfang 065007 (China)

    2017-02-28

    Graphical abstract: The micro-nanoscale hierarchical structures at the sandstone core surface are constructed by adsorption of the modified silica nanoparticles, which leads to the effect of drag reduction to improve the low injection rate in ultra-low permeability reservoirs. - Highlights: • A micro-nanoscale hierarchical structure is formed at the reservoir rock surface. • An inversion has happened from hydrophilic into hydrophobic modified by nanofluids. • The effect of drag reduction to improve the low injection rate is realized. • The mechanism of drag reduction induced from the modified core surface was unclosed. - Abstract: Based on the adsorption behavior of modified silica nanoparticles in the sandstone core surface, the hydrophobic surface was constructed, which consists of micro-nanoscale hierarchical structure. This modified core surface presents a property of drag reduction and meets the challenge of high injection pressure and low injection rate in low or ultra-low permeability reservoir. The modification effects on the surface of silica nanoparticles and reservoir cores, mainly concerning hydrophobicity and fine structure, were determined by measurements of contact angle and scanning electron microscopy. Experimental results indicate that after successful modification, the contact angle of silica nanoparticles varies from 19.5° to 141.7°, exhibiting remarkable hydrophobic properties. These modified hydrophobic silica nanoparticles display a good adsorption behavior at the core surface to form micro-nanobinary structure. As for the wettability of these modified core surfaces, a reversal has happened from hydrophilic into hydrophobic and its contact angle increases from 59.1° to 105.9°. The core displacement experiments show that the relative permeability for water has significantly increased by an average of 40.3% via core surface modification, with the effects of reducing injection pressure and improving injection performance of water

  12. Drag reduction in reservoir rock surface: Hydrophobic modification by SiO_2 nanofluids

    International Nuclear Information System (INIS)

    Yan, Yong-Li; Cui, Ming-Yue; Jiang, Wei-Dong; He, An-Le; Liang, Chong

    2017-01-01

    Graphical abstract: The micro-nanoscale hierarchical structures at the sandstone core surface are constructed by adsorption of the modified silica nanoparticles, which leads to the effect of drag reduction to improve the low injection rate in ultra-low permeability reservoirs. - Highlights: • A micro-nanoscale hierarchical structure is formed at the reservoir rock surface. • An inversion has happened from hydrophilic into hydrophobic modified by nanofluids. • The effect of drag reduction to improve the low injection rate is realized. • The mechanism of drag reduction induced from the modified core surface was unclosed. - Abstract: Based on the adsorption behavior of modified silica nanoparticles in the sandstone core surface, the hydrophobic surface was constructed, which consists of micro-nanoscale hierarchical structure. This modified core surface presents a property of drag reduction and meets the challenge of high injection pressure and low injection rate in low or ultra-low permeability reservoir. The modification effects on the surface of silica nanoparticles and reservoir cores, mainly concerning hydrophobicity and fine structure, were determined by measurements of contact angle and scanning electron microscopy. Experimental results indicate that after successful modification, the contact angle of silica nanoparticles varies from 19.5° to 141.7°, exhibiting remarkable hydrophobic properties. These modified hydrophobic silica nanoparticles display a good adsorption behavior at the core surface to form micro-nanobinary structure. As for the wettability of these modified core surfaces, a reversal has happened from hydrophilic into hydrophobic and its contact angle increases from 59.1° to 105.9°. The core displacement experiments show that the relative permeability for water has significantly increased by an average of 40.3% via core surface modification, with the effects of reducing injection pressure and improving injection performance of water

  13. Optimizing Parameters of Axial Pressure-Compounded Ultra-Low Power Impulse Turbines at Preliminary Design

    Science.gov (United States)

    Kalabukhov, D. S.; Radko, V. M.; Grigoriev, V. A.

    2018-01-01

    Ultra-low power turbine drives are used as energy sources in auxiliary power systems, energy units, terrestrial, marine, air and space transport within the confines of shaft power N td = 0.01…10 kW. In this paper we propose a new approach to the development of surrogate models for evaluating the integrated efficiency of multistage ultra-low power impulse turbine with pressure stages. This method is based on the use of existing mathematical models of ultra-low power turbine stage efficiency and mass. It has been used in a method for selecting the rational parameters of two-stage axial ultra-low power turbine. The article describes the basic features of an algorithm for two-stage turbine parameters optimization and for efficiency criteria evaluating. Pledged mathematical models are intended for use at the preliminary design of turbine drive. The optimization method was tested at preliminary design of an air starter turbine. Validation was carried out by comparing the results of optimization calculations and numerical gas-dynamic simulation in the Ansys CFX package. The results indicate a sufficient accuracy of used surrogate models for axial two-stage turbine parameters selection

  14. Specific gravity and API gravity of biodiesel and ultra-low sulfur diesel (ULSD) blends

    Science.gov (United States)

    Biodiesel is an alternative fuel made from vegetable oils and animal fats. In 2006, the U. S. Environmental Protection Agency mandated a maximum sulfur content of 15 ppm in on-road diesel fuels. Processing to produce the new ultra-low sulfur petrodiesel (ULSD) alters specific gravity (SG) and othe...

  15. An Ultra-Low-Latency Geo-Routing Scheme for Team-Based Unmanned Vehicular Applications

    KAUST Repository

    Bader, Ahmed; Alouini, Mohamed-Slim

    2016-01-01

    Results and lessons learned from the implementation of a novel ultra low-latency geo-routing scheme are presented in this paper. The geo-routing scheme is intended for team-based mobile systems whereby a cluster of unmanned autonomous vehicles

  16. Channel coding study for ultra-low power wireless design of autonomous sensor works

    NARCIS (Netherlands)

    Zhang, P.; Huang, Li; Willems, F.M.J.

    2011-01-01

    Ultra-low power wireless design is highly demanded for building up autonomous wireless sensor networks (WSNs) for many application areas. To keep certain quality of service with limited power budget, channel coding techniques can be applied to maintain the robustness and reliability of WSNs. In this

  17. Ultra-low temperature curable nano-silver conductive adhesive for piezoelectric composite material

    Science.gov (United States)

    Yan, Chao; Liao, Qingwei; Zhou, Xingli; Wang, Likun; Zhong, Chao; Zhang, Di

    2018-01-01

    Limited by the low thermal resistance of composite material, ultra-low temperature curable conductive silver adhesive with curing temperature less than 100 °C needed urgently for the surface conduction treatment of piezoelectric composite material. An ultra-low temperature curable nano-silver conductive adhesive with high adhesion strength for the applications of piezoelectric composite material was investigated. The crystal structure of cured adhesive, SEM/EDS analysis, thermal analysis, adhesive properties and conductive properties of different content of nano-silver filler or micron-silver doping samples were studied. The results show that with 60 wt.% nano-silver filler the ultra-low temperature curable conductive silver adhesive had the relatively good conductivity as volume resistivity of 2.37 × 10-4 Ω cm, and good adhesion strength of 5.13 MPa. Minor micron-doping (below 15 wt.%) could improve conductivity, but would decrease other properties. The ultra-low temperature curable nano-silver conductive adhesive could successfully applied to piezoelectric composite material.

  18. The PS 200 catching trap: A new tool for ultra-low energy antiproton physics

    International Nuclear Information System (INIS)

    Holzscheiter, M.H.; Dyer, P.L.; King, N.S.P.; Lizon, D.C.; Morgan, G.L.; Schauer, M.M.; Schecker, J.A.; Hoibraten, S.; Lewis, R.A.; Otto, T.

    1994-01-01

    Approximately one million antiprotons have been trapped and electron cooled in the PS200 catching trap from a single fast extracted pulse from LEAR. The system is described in detail, different extraction schemes are discussed, and possible applications of this instrument to ultra-low energy atomic and nuclear physics with antiprotons are mentioned

  19. Convolutional auto-encoder for image denoising of ultra-low-dose CT

    Directory of Open Access Journals (Sweden)

    Mizuho Nishio

    2017-08-01

    Conclusion: Neural network with convolutional auto-encoder could be trained using pairs of standard-dose and ultra-low-dose CT image patches. According to the visual assessment by radiologists and technologists, the performance of our proposed method was superior to that of large-scale nonlocal mean and block-matching and 3D filtering.

  20. Ultra-low friction and excellent elastic recovery of fullerene-like ...

    Indian Academy of Sciences (India)

    2017-08-24

    Aug 24, 2017 ... a high elastic recovery (∼90%), ultra-low friction coefficient (∼0.019) and low wear rate ... Y Meng et al .... [3] Liu D G, Tu J P, Gu C D, Hong C F, Chen R and Yang W S ... [7] Cumings J and Zettl A 2000 Science 289 602.

  1. The impact of in-situ stress and outcrop-based fracture geometry on hydraulic aperture and upscaled permeability in fractured reservoirs

    DEFF Research Database (Denmark)

    Bisdom, Kevin; Bertotti, Giovanni; Nick, Hamid

    2016-01-01

    explicitly, we quantify equivalent permeability, i.e. combined matrix and stress-dependent fracture flow. Fracture networks extracted from a large outcropping pavement form the basis of these models. The results show that the angle between fracture strike and σ 1 has a controlling impact on aperture...

  2. Geothermal Permeability Enhancement - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Joe Beall; Mark Walters

    2009-06-30

    The overall objective is to apply known permeability enhancement techniques to reduce the number of wells needed and demonstrate the applicability of the techniques to other undeveloped or under-developed fields. The Enhanced Geothermal System (EGS) concept presented in this project enhances energy extraction from reduced permeability zones in the super-heated, vapor-dominated Aidlin Field of the The Geysers geothermal reservoir. Numerous geothermal reservoirs worldwide, over a wide temperature range, contain zones of low permeability which limit the development potential and the efficient recovery of heat from these reservoirs. Low permeability results from poorly connected fractures or the lack of fractures. The Enhanced Geothermal System concept presented here expands these technologies by applying and evaluating them in a systematic, integrated program.

  3. An Integrated Capillary, Buoyancy, and Viscous-Driven Model for Brine/CO2Relative Permeability in a Compositional and Parallel Reservoir Simulator

    KAUST Repository

    Kong, X.; Delshad, M.; Wheeler, M. F.

    2012-01-01

    The effectiveness of CO2 storage in the saline aquifers is governed by the interplay of capillary, viscous, and buoyancy forces. Recent experimental study reveals the impact of pressure, temperature, and salinity on interfacial tension (IFT) between CO2 and brine. The dependence of CO2-brine relative permeability and capillary pressure on pressure (IFT) is also clearly evident in published experimental results. Improved understanding of the mechanisms that control the migration and trapping of CO2 in subsurface is crucial to design future storage projects that warrant long-term and safe containment. Simulation studies ignoring the buoyancy and also variation in interfacial tension and the effect on the petrophysical properties such as trapped CO2 saturations, relative permeability, and capillary pressure have a poor chance of making accurate predictions of CO2 injectivity and plume migration. We have developed and implemented a general relative permeability model that combines effects of pressure gradient, buoyancy, and IFT in an equation of state (EOS) compositional and parallel simulator. The significance of IFT variations on CO2 migration and trapping is assessed.

  4. An Integrated Capillary, Buoyancy, and Viscous-Driven Model for Brine/CO2Relative Permeability in a Compositional and Parallel Reservoir Simulator

    KAUST Repository

    Kong, X.

    2012-11-03

    The effectiveness of CO2 storage in the saline aquifers is governed by the interplay of capillary, viscous, and buoyancy forces. Recent experimental study reveals the impact of pressure, temperature, and salinity on interfacial tension (IFT) between CO2 and brine. The dependence of CO2-brine relative permeability and capillary pressure on pressure (IFT) is also clearly evident in published experimental results. Improved understanding of the mechanisms that control the migration and trapping of CO2 in subsurface is crucial to design future storage projects that warrant long-term and safe containment. Simulation studies ignoring the buoyancy and also variation in interfacial tension and the effect on the petrophysical properties such as trapped CO2 saturations, relative permeability, and capillary pressure have a poor chance of making accurate predictions of CO2 injectivity and plume migration. We have developed and implemented a general relative permeability model that combines effects of pressure gradient, buoyancy, and IFT in an equation of state (EOS) compositional and parallel simulator. The significance of IFT variations on CO2 migration and trapping is assessed.

  5. An Ultra-low Frequency Modal Testing Suspension System for High Precision Air Pressure Control

    Directory of Open Access Journals (Sweden)

    Qiaoling YUAN

    2014-05-01

    Full Text Available As a resolution for air pressure control challenges in ultra-low frequency modal testing suspension systems, an incremental PID control algorithm with dead band is applied to achieve high-precision pressure control. We also develop a set of independent hardware and software systems for high-precision pressure control solutions. Taking control system versatility, scalability, reliability, and other aspects into considerations, a two-level communication employing Ethernet and CAN bus, is adopted to complete such tasks as data exchange between the IPC, the main board and the control board ,and the pressure control. Furthermore, we build a single set of ultra-low frequency modal testing suspension system and complete pressure control experiments, which achieve the desired results and thus confirm that the high-precision pressure control subsystem is reasonable and reliable.

  6. Ultra-low-dose continuous combined estradiol and norethisterone acetate: improved bleeding profile in postmenopausal women

    DEFF Research Database (Denmark)

    Sturdee, D.W.; Archer, D.F.; Rakov, V.

    2008-01-01

    OBJECTIVE: To evaluate the effect of two ultra-low-dose hormone treatments containing estradiol (E2) 0.5 mg and norethisterone acetate (NETA) 0.1 or 0.25 mg on the endometrium and bleeding. METHODS: A prospective, randomized, placebo-controlled trial of 6 months. Local Ethics Committee approval...... and informed consent were obtained prior to initiation and enrollment. Out of 577 postmenopausal women randomized, 575 took E2/NETA 0.1 (n = 194), or E2/NETA 0.25 (n = 181) or placebo (n = 200). Endometrial bleeding was monitored by daily diary cards and endometrial thickness by transvaginal ultrasound......: The ultra-low-dose combination of E2/NETA 0.1 or E2/NETA 0.25 resulted in a high incidence of amenorrhea and no bleeding in postmenopausal women, and a corresponding high level of compliance. Overall, there was no significant change in mean endometrial thickness during 6 months of active treatment...

  7. Ultra-low Temperature Curable Conductive Silver Adhesive with different Resin Matrix

    Science.gov (United States)

    Zhou, Xingli; Wang, Likun; Liao, Qingwei; Yan, Chao; Li, Xing; Qin, Lei

    2018-03-01

    The ultra-low temperature curable conductive silver adhesive with curing temperature less than 100 °C needed urgently for the surface conductive treatment of piezoelectric composite material due to the low thermal resistance of composite material and low adhesion strength of adhesive. An ultra-low temperature curable conductive adhesive with high adhesion strength was obtained for the applications of piezoelectric composite material. The microstructure, conductive properties and adhesive properties with different resin matrix were investigated. The conductive adhesive with AG-80 as the resin matrix has the shorter curing time (20min), lower curing temperature (90°C) and higher adhesion strength (7.6MPa). The resistivity of AG-80 sample has the lower value (2.13 × 10-4Ω·cm) than the 618 sample (4.44 × 10-4Ω·cm).

  8. Effect of Diluent on Ultra-low Temperature Curable Conductive Silver Adhesive

    Science.gov (United States)

    Zhou, Xingli; Wang, Likun; Liao, Qingwei; Yan, Chao; Du, Haibo; Qin, Lei

    2018-03-01

    The ultra-low temperature curable conductive silver adhesive needed urgently for the surface conductive treatment of piezoelectric composite material. The effect of diluent acetone on ultra-low temperature curable conductive silver adhesive were investigated for surface conductive treatment of piezoelectric composite material. In order to improve the operability and extend the life of the conductive adhesive, the diluent was added to dissolve and disperse conductive adhesive. With the increase of the content of diluent, the volume resistivity of conductive adhesive decreased at first and then increased, and the shear strength increased at first and then decreased. When the acetone content is 10%, the silver flaky bonded together, arranged the neatest, the smallest gap, the most closely connected, the surface can form a complete conductive network, and the volume resistivity is 2.37 × 10-4Ω · cm, the shear strength is 5.13MPa.

  9. Ultra low-cost, portable smartphone optosensors for mobile point-of-care diagnostics

    Science.gov (United States)

    Wang, Li-Ju; Chang, Yu-Chung; Sun, Rongrong; Li, Lei

    2018-02-01

    Smartphone optosensors with integrated optical components make mobile point-of-care (MPoC) diagnostics be done near patients' side. It'll especially have a significant impact on healthcare delivery in rural or remote areas. Current FDA-approved PoC devices achieving clinical level are still at high cost and not affordable in rural hospitals. We present a series of ultra low-cost smartphone optical sensing devices for mobile point-of-care diagnosis. Aiming different targeting analytes and sensing mechanisms, we developed custom required optical components for each smartphone optosensros. These optical devices include spectrum readers, colorimetric readers for microplate, lateral flow device readers, and chemiluminescence readers. By integrating our unique designed optical components into smartphone optosening platform, the anlaytes can be precisely detected. Clinical testing results show the clinical usability of our smartphone optosensors. Ultra low-cost portable smartphone optosensors are affordable for rural/remote doctors.

  10. Security Implications for Ultra-Low Power Configurable SoC FPAA Embedded Systems

    Directory of Open Access Journals (Sweden)

    Jennifer Hasler

    2018-06-01

    Full Text Available We discuss the impact of physical computing techniques to classifying network security issues for ultra-low power networked IoT devices. Physical computing approaches enable at least a factor of 1000 improvement in computational energy efficiency empowering a new generation of local computational structures for embedded IoT devices. These techniques offer computational capability to address network security concerns. This paper begins the discussion of security opportunities for, and issues using, FPAA devices for small embedded IoT platforms. These FPAAs enable devices often utilized for low-power context aware computation. Embedded FPAA devices have both positive Security attributes, as well as potential vulnerabilities. FPAA devices can be part of the resulting secure computation, such as implementing unique functions. FPAA devices can be used investigate security of analog/mixed signal capabilities. The paper concludes with summarizing key improvements for secure ultra-low power embedded FPAA devices.

  11. Ultra-low-frequency dust-electromagnetic modes in self-gravitating magnetized dusty plasmas

    International Nuclear Information System (INIS)

    Banerjee, A.K.; Alam, M.N.; Mamun, A.A.

    2001-01-01

    Obliquely propagating ultra-low-frequency dust-electromagnetic waves in a self-gravitating, warm, magnetized, two fluid dusty plasma system have been investigated. Two special cases, namely, dust-Alfven mode propagating parallel to the external magnetic field and dust- magnetosonic mode propagating perpendicular to the external magnetic field have also been considered. It has been shown that effects of self-gravitational field, dust fluid temperature, and obliqueness significantly modify the dispersion properties of these ultra-low-frequency dust-electromagnetic modes. It is also found that in parallel propagating dust-Alfven mode these effects play no role, but in obliquely propagating dust-Alfven mode or perpendicular propagating dust-magnetosonic mode the effect of self-gravitational field plays destabilizing role whereas the effect of dust/ion fluid temperature plays stabilizing role. (author)

  12. Ultra Low Energy Binary Decision Diagram Circuits Using Few Electron Transistors

    Science.gov (United States)

    Saripalli, Vinay; Narayanan, Vijay; Datta, Suman

    Novel medical applications involving embedded sensors, require ultra low energy dissipation with low-to-moderate performance (10kHz-100MHz) driving the conventional MOSFETs into sub-threshold operation regime. In this paper, we present an alternate ultra-low power computing architecture using Binary Decision Diagram based logic circuits implemented using Single Electron Transistors (SETs) operating in the Coulomb blockade regime with very low supply voltages. We evaluate the energy - performance tradeoff metrics of such BDD circuits using time domain Monte Carlo simulations and compare them with the energy-optimized CMOS logic circuits. Simulation results show that the proposed approach achieves better energy-delay characteristics than CMOS realizations.

  13. Ultra-low-frequency dust-electromagnetic modes in self-gravitating magnetized dusty plasmas

    International Nuclear Information System (INIS)

    Mamun, A.A.

    1999-07-01

    Obliquely propagating ultra-low-frequency dust-electromagnetic waves in a self-gravitating, warm, magnetized two fluid dusty plasma system have been investigated. Two special cases, namely, dust-Alfven mode propagating parallel to the external magnetic field and dust-magnetosonic mode propagating perpendicular to the external magnetic field have also been considered. It has been shown that effects of self-gravitational field, dust fluid temperature, and obliqueness significantly modify the dispersion properties of these ultra-low-frequency dust-electromagnetic modes. It is also found that these effects of self-gravitational field and dust/ion fluid temperature play no role in parallel propagating dust-Alfven mode, but in obliquely propagating dust-Alfven mode or perpendicular propagating dust-magnetosonic mode the effect of self-gravitational field plays a destabilizing role whereas the effect of dust/ion fluid temperature plays a stabilizing role. (author)

  14. CMOS circuits for electromagnetic vibration transducers interfaces for ultra-low voltage energy harvesting

    CERN Document Server

    Maurath, Dominic

    2015-01-01

    Chip-integrated power management solutions are a must for ultra-low power systems. This enables not only the optimization of innovative sensor applications. It is also essential for integration and miniaturization of energy harvesting supply strategies of portable and autonomous monitoring systems. The book particularly addresses interfaces for energy harvesting, which are the key element to connect micro transducers to energy storage elements. Main features of the book are: - A comprehensive technology and application review, basics on transducer mechanics, fundamental circuit and control design, prototyping and testing, up to sensor system supply and applications. - Novel interfacing concepts - including active rectifiers, MPPT methods for efficient tracking of DC as well as AC sources, and a fully-integrated charge pump for efficient maximum AC power tracking at sub-100µW ultra-low power levels. The chips achieve one of widest presented operational voltage range in standard CMOS technology: 0.44V to over...

  15. Remote Sensing Extraction of Stopes and Tailings Ponds in AN Ultra-Low Iron Mining Area

    Science.gov (United States)

    Ma, B.; Chen, Y.; Li, X.; Wu, L.

    2018-04-01

    With the development of economy, global demand for steel has accelerated since 2000, and thus mining activities of iron ore have become intensive accordingly. An ultra-low-grade iron has been extracted by open-pit mining and processed massively since 2001 in Kuancheng County, Hebei Province. There are large-scale stopes and tailings ponds in this area. It is important to extract their spatial distribution information for environmental protection and disaster prevention. A remote sensing method of extracting stopes and tailings ponds is studied based on spectral characteristics by use of Landsat 8 OLI imagery and ground spectral data. The overall accuracy of extraction is 95.06 %. In addition, tailings ponds are distinguished from stopes based on thermal characteristics by use of temperature image. The results could provide decision support for environmental protection, disaster prevention, and ecological restoration in the ultra-low-grade iron ore mining area.

  16. Ultra-low energy electrons from fast heavy-ion helium collisions: the `target Cusp`

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, W. [Freiburg Univ. (Germany)]|[Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Moshammer, R.; Kollmus, H.; Ullrich, J. [Freiburg Univ. (Germany); O`Rourke, F.S.C. [Queen`s Univ., Belfast, Northern Ireland (United Kingdom); Sarkadi, L. [Magyar Tudomanyos Akademia, Debrecen (Hungary). Atommag Kutato Intezete; Mann, R. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Hagmann, S. [Kansas State Univ., Manhattan, KS (United States). J.R. MacDonald Lab.; Olson, R.E. [Missouri Univ., Rolla, MO (United States). Dept. of Physics

    1998-09-01

    Doubly differential cross sections d{sup 2}{sigma}/dv {sub parallel} dv {sub perpendicular} {sub to} have been obtained by mapping the 3-dimensional velocity space of ultra-low and low-energy electrons (1.5 meV{<=} E{sub e}{<=}100 eV) emitted in singly ionizing 3.6 MeV/u Au{sup 53+} on helium collisions. A sharp ({Delta}E{sub e} {sub perpendicular} {sub to} {sup FWHM} {<=} 22 meV) asymmetric peak centered at vertical stroke anti {nu} vertical stroke =0 is observed to emerge at ultra-low energies from the strongly forward shifted low-energy electron velocity distribution. The shape of this ``target cusp``, which is very sensitive on the details of the two-center potential, is in excellent accord with theoretical CTMC and CDW-EIS predictions. (orig.)

  17. Ultra-low magnetic damping in metallic and half-metallic systems

    Science.gov (United States)

    Shaw, Justin

    The phenomenology of magnetic damping is of critical importance to devices which seek to exploit the electronic spin degree of freedom since damping strongly affects the energy required and speed at which a device can operate. However, theory has struggled to quantitatively predict the damping, even in common ferromagnetic materials. This presents a challenge for a broad range of applications in magnonics, spintronics and spin-orbitronics that depend on the ability to precisely control the damping of a material. I will discuss our recent work to precisely measure the intrinsic damping in several metallic and half-metallic material systems and compare experiment with several theoretical models. This investigation uncovered a metallic material composed of Co and Fe that exhibit ultra-low values of damping that approach values found in thin film YIG. Such ultra-low damping is unexpected in a metal since magnon-electron scattering dominates the damping in conductors. However, this system possesses a distinctive feature in the bandstructure that minimizes the density of states at the Fermi energy n(EF). These findings provide the theoretical framework by which such ultra-low damping can be achieved in metallic ferromagnets and may enable a new class of experiments where ultra-low damping can be combined with a charge current. Half-metallic Heusler compounds by definition have a bandgap in one of the spin channels at the Fermi energy. This feature can also lead to exceptionally low values of the damping parameter. Our results show a strong correlation of the damping with the order parameter in Co2MnGe. Finally, I will provide an overview of the recent advances in achieving low damping in thin film Heusler compounds.

  18. Silicon for ultra-low-level detectors and sup 32 Si

    Energy Technology Data Exchange (ETDEWEB)

    Plaga, R. (Max Planck Inst. fuer Kernphysik, Heidelberg (Germany))

    1991-11-15

    A recent dark matter experiment using a silicon diode detector confirms that the decay of {sup 32}Si is a dangerous background in ultra-low-level experiments using silicon as detector material or shielding. In this Letter we study the mechanism of how {sup 32}Si enters commercially available silicon. Ways to avoid this contamination are pointed out. Limits on the {sup 32}Si content of silicon from measurements with miniaturized low-level proportional counters are also given. (orig.).

  19. Ultra-low thermal expansion realized in giant negative thermal expansion materials through self-compensation

    OpenAIRE

    Fei-Ran Shen; Hao Kuang; Feng-Xia Hu; Hui Wu; Qing-Zhen Huang; Fei-Xiang Liang; Kai-Ming Qiao; Jia Li; Jing Wang; Yao Liu; Lei Zhang; Min He; Ying Zhang; Wen-Liang Zuo; Ji-Rong Sun

    2017-01-01

    Materials with zero thermal expansion (ZTE) or precisely tailored thermal expansion are in urgent demand of modern industries. However, the overwhelming majority of materials show positive thermal expansion. To develop ZTE or negative thermal expansion (NTE) materials as compensators has become an important challenge. Here, we present the evidence for the realization of ultra-low thermal expansion in Mn–Co–Ge–In particles. The bulk with the Ni2In-type hexagonal structure undergoes giant NTE o...

  20. Study of multi-layered graphene by ultra-low energy SEM/STEM

    Czech Academy of Sciences Publication Activity Database

    Mikmeková, Eliška; Frank, Luděk; Müllerová, Ilona; Li, B. W.; Ruoff, R. S.; Lejeune, M.

    2016-01-01

    Roč. 63, March 2016 (2016), s. 136-142 ISSN 0925-9635 R&D Projects: GA TA ČR(CZ) TE01020118; GA MŠk(CZ) LO1212 EU Projects: European Commission(XE) 606988 - SIMDALEE2 Institutional support: RVO:68081731 Keywords : scanning ultra low energy electron microscopy * graphene * contamination * CVD Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 2.561, year: 2016

  1. Component Development to Accelerate Commercial Implementation of Ultra-Low Emissions Catalytic Combustion

    Energy Technology Data Exchange (ETDEWEB)

    McCarty, Jon; Berry, Brian; Lundberg, Kare; Anson, Orris

    2003-03-31

    This final report describes a 2000-2003 program for the development of components and processes to enhance the commercialization of ultra-low emissions catalytic combustion in industrial gas turbines. The range of project tasks includes: development of more durable, lower-cost catalysts and catalytic combustor components; development and design of a catalytic pre-burner and a catalytic pilot burner for gas turbines, and on-site fuel conversion processing for utilization of liquid fuel.

  2. The development of an ultra-low-emission gas-fired combustor for space heaters

    International Nuclear Information System (INIS)

    Xiong, Tian-yu; Khinkis, M.J.; Coppin, W.P.

    1991-01-01

    An ultra-low-emission as-fired combustor has been developed for relatively low-temperature direct-air heating applications. High-lean premixed cyclonic combustion with a flame stabilizer is employed to achieve ultra-low emissions and high turndown operation. On the basis of analytical studies and cold modeling a 350-kW test combustor was designed and successfully tested. Experimental results obtained using natural gas and ambient air demonstrated that the test combustor can operate steadily at high excess air up to 80% to 100% over a large turndown range up to 40:1. At design operating conditions, NO x emissions as low as 0.6 vppm and CO and total hydrocarbon (THC) emissions below 3 vppm were achieved. Over the full operating range, NO x emissions from 0.3 to 1.0 vppm and CO and THC emissions below 4 vppm were demonstrated. In all tests, concentrations of NO 2 were less than 40% of the total NO 2 emissions from combustion processes required for good indoor air quality (0.5 vppm). This paper presents the concept of high-lean premixed ultra-low-emission cyclonic combustion, design specifications for the combustion system, and the major experimental results, including flame stability, emissions, and turndown performance. 15 refs., 10 figs., 1 tab

  3. The development of an ultra-low-emission gas-fired cyclonic combustor

    International Nuclear Information System (INIS)

    Xiong, Tian-yu; Khinkis, M.J.; Coppin, W.P.

    1991-01-01

    A gas-fired cyclonic combustor has been developed for relatively low-temperature direct-air heating applications that require ultra-low pollutant emissions. High-lean premixed combustion with a flame stabilizer is adopted to achieve ultra-low emissions and high turndown operation. On the basis of analytical studies and cold modeling, a 350-kW test combustor was designed and successfully tested. Experimental results obtained using natural gas and ambient air demonstrated that the test combustor can operate steadily at high excess air up to 80% to 100% over a large turndown range up to 40:1. At design operating conditions, NO x emissions as low as 0.6 vppm and CO and total hydrocarbon (THC) emissions below 3 vppm were achieved. Over the full operating range, NO x emissions from 0.3 to 1.0 vppm and CO and THC emissions below 4 vppm were demonstrated. In all tests, concentrations of NO 2 were less than 40% of the total NO x emissions -- lower than the level of NO 2 emissions from combustion processes required for good indoor air quality (0.5 vppm). This paper presents the concept of high-lean premixed ultra-low-emission cyclonic combustion, design specifications for the combustion system, and the major experimental results, including flame stability, emissions, and turndown performance. 13 refs., 12 figs., 1 tab

  4. Ultra-low-energy (<10 eV/u) ion beam bombardment effect on naked DNA

    Energy Technology Data Exchange (ETDEWEB)

    Thopan, P. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thongkumkoon, P. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Prakrajang, K. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Faculty of Science, Maejo University, Chiang Mai 50290 (Thailand); Suwannakachorn, D. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Yu, L.D., E-mail: yuld@thep-center.org [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand)

    2014-05-01

    Highlights: • Decelerated ultra-low energy ion beam bombarded naked DNA. • DNA form change induced by ion bombardment was investigated. • N-ion bombardment at 32 eV induced DNA single and double strand breaks. • Ar-ion bombardment at a-few-hundreds eV induced DNA single strand break. - Abstract: Since ion energy deposition in the ion-bombarded materials dominantly occurs in the low-energy range, it is very interesting to know effects from ultra-low-energy ion interaction with DNA for understanding ion-beam-induced genetic mutation. Tens-keV Ar- and N-ion beams were decelerated to ultra-low energy ranging from 20 to 100 eV, or only a few to 10 eV/u, to bombard naked plasmid DNA. The bombarded DNA was analyzed using gel electrophoresis for DNA form changes. The original DNA supercoiled form was found to change to relaxed and linear forms, indicating single or double strand breaks after bombarded by tens-eV ion beam. N-ion beam was found more effective in inducing DNA change and mutation than Ar-ion beam. The study demonstrated that the ion bombardment with energy as low as several-tens eV was able to break DNA strands and thus potentially to cause genetic modification of biological cells. The experimental results were discussed in terms of direct atomic collision between the ions and DNA atoms.

  5. Ultra-low-energy (<10 eV/u) ion beam bombardment effect on naked DNA

    International Nuclear Information System (INIS)

    Thopan, P.; Thongkumkoon, P.; Prakrajang, K.; Suwannakachorn, D.; Yu, L.D.

    2014-01-01

    Highlights: • Decelerated ultra-low energy ion beam bombarded naked DNA. • DNA form change induced by ion bombardment was investigated. • N-ion bombardment at 32 eV induced DNA single and double strand breaks. • Ar-ion bombardment at a-few-hundreds eV induced DNA single strand break. - Abstract: Since ion energy deposition in the ion-bombarded materials dominantly occurs in the low-energy range, it is very interesting to know effects from ultra-low-energy ion interaction with DNA for understanding ion-beam-induced genetic mutation. Tens-keV Ar- and N-ion beams were decelerated to ultra-low energy ranging from 20 to 100 eV, or only a few to 10 eV/u, to bombard naked plasmid DNA. The bombarded DNA was analyzed using gel electrophoresis for DNA form changes. The original DNA supercoiled form was found to change to relaxed and linear forms, indicating single or double strand breaks after bombarded by tens-eV ion beam. N-ion beam was found more effective in inducing DNA change and mutation than Ar-ion beam. The study demonstrated that the ion bombardment with energy as low as several-tens eV was able to break DNA strands and thus potentially to cause genetic modification of biological cells. The experimental results were discussed in terms of direct atomic collision between the ions and DNA atoms

  6. Dynamical cancellation of pulse-induced transients in a metallic shielded room for ultra-low-field magnetic resonance imaging

    International Nuclear Information System (INIS)

    Zevenhoven, Koos C. J.; Ilmoniemi, Risto J.; Dong, Hui; Clarke, John

    2015-01-01

    Pulse-induced transients such as eddy currents can cause problems in measurement techniques where a signal is acquired after an applied preparatory pulse. In ultra-low-field magnetic resonance imaging, performed in magnetic fields typically of the order of 100 μT, the signal-to-noise ratio is enhanced in part by prepolarizing the proton spins with a pulse of much larger magnetic field and in part by detecting the signal with a Superconducting QUantum Interference Device (SQUID). The pulse turn-off, however, can induce large eddy currents in the shielded room, producing an inhomogeneous magnetic-field transient that both seriously distorts the spin dynamics and exceeds the range of the SQUID readout. It is essential to reduce this transient substantially before image acquisition. We introduce dynamical cancellation (DynaCan), a technique in which a precisely designed current waveform is applied to a separate coil during the later part and turn off of the polarizing pulse. This waveform, which bears no resemblance to the polarizing pulse, is designed to drive the eddy currents to zero at the precise moment that the polarizing field becomes zero. We present the theory used to optimize the waveform using a detailed computational model with corrections from measured magnetic-field transients. SQUID-based measurements with DynaCan demonstrate a cancellation of 99%. Dynamical cancellation has the great advantage that, for a given system, the cancellation accuracy can be optimized in software. This technique can be applied to both metal and high-permeability alloy shielded rooms, and even to transients other than eddy currents

  7. Permeability enhancement by shock cooling

    Science.gov (United States)

    Griffiths, Luke; Heap, Michael; Reuschlé, Thierry; Baud, Patrick; Schmittbuhl, Jean

    2015-04-01

    The permeability of an efficient reservoir, e.g. a geothermal reservoir, should be sufficient to permit the circulation of fluids. Generally speaking, permeability decreases over the life cycle of the geothermal system. As a result, is usually necessary to artificially maintain and enhance the natural permeability of these systems. One of the methods of enhancement -- studied here -- is thermal stimulation (injecting cold water at low pressure). This goal of this method is to encourage new thermal cracks within the reservoir host rocks, thereby increasing reservoir permeability. To investigate the development of thermal microcracking in the laboratory we selected two granites: a fine-grained (Garibaldi Grey granite, grain size = 0.5 mm) and a course-grained granite (Lanhelin granite, grain size = 2 mm). Both granites have an initial porosity of about 1%. Our samples were heated to a range of temperatures (100-1000 °C) and were either cooled slowly (1 °C/min) or shock cooled (100 °C/s). A systematic microstructural (2D crack area density, using standard stereological techniques, and 3D BET specific surface area measurements) and rock physical property (porosity, P-wave velocity, uniaxial compressive strength, and permeability) analysis was undertaken to understand the influence of slow and shock cooling on our reservoir granites. Microstructurally, we observe that the 2D crack surface area per unit volume and the specific surface area increase as a result of thermal stressing, and, for the same maximum temperature, crack surface area is higher in the shock cooled samples. This observation is echoed by our rock physical property measurements: we see greater changes for the shock cooled samples. We can conclude that shock cooling is an extremely efficient method of generating thermal microcracks and modifying rock physical properties. Our study highlights that thermal treatments are likely to be an efficient method for the "matrix" permeability enhancement of

  8. Ultra-low background and environmental measurements at Laboratorio Subterráneo de Canfranc (LSC).

    Science.gov (United States)

    Bandac, I; Borjabad, S; Ianni, A; Nuñez-Lagos, R; Pérez, C; Rodríguez, S; Villar, J A

    2017-08-01

    To support the construction of experiments at the Laboratorio Subterráneo de Canfranc (LSC) in Spain, an Ultra-Low Background Service (ULBS) and a Copper Electroforming Service (CES) were created. The measurement technique employed at the ULBS is gamma spectroscopy with high purity germanium (HPGe) detectors. A new anti-radon system is being implemented. The main goal of CES is to obtain high-purity copper pieces. A new electroforming set-up inside LSC underground clean room is planned. Radon and environmental measurements at the LSC are presented. The ULBS and CES are reviewed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. An Ultra-Low-Latency Geo-Routing Scheme for Team-Based Unmanned Vehicular Applications

    KAUST Repository

    Bader, Ahmed

    2016-02-26

    Results and lessons learned from the implementation of a novel ultra low-latency geo-routing scheme are presented in this paper. The geo-routing scheme is intended for team-based mobile systems whereby a cluster of unmanned autonomous vehicles are deployed to accomplish a critical mission under human supervision. The contention-free nature of the developed scheme lends itself to jointly achieve lower latency and higher throughput. Implementation challenges are presented and corresponding resolutions are discussed herewith. © 2015 IEEE.

  10. Ultra-low field nuclear magnetic resonance and magnetic resonance imaging to discriminate and identify materials

    Science.gov (United States)

    Matlashov, Andrei Nikolaevich; Urbaitis, Algis V.; Savukov, Igor Mykhaylovich; Espy, Michelle A.; Volegov, Petr Lvovich; Kraus, Jr., Robert Henry

    2013-03-05

    Method comprising obtaining an NMR measurement from a sample wherein an ultra-low field NMR system probes the sample and produces the NMR measurement and wherein a sampling temperature, prepolarizing field, and measurement field are known; detecting the NMR measurement by means of inductive coils; analyzing the NMR measurement to obtain at least one measurement feature wherein the measurement feature comprises T1, T2, T1.rho., or the frequency dependence thereof; and, searching for the at least one measurement feature within a database comprising NMR reference data for at least one material to determine if the sample comprises a material of interest.

  11. The MAJORANA experiment: an ultra-low background search for neutrinoless double-beta decay

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, D.; Aguayo Navarrete, Estanislao; Avignone, Frank T.; Back, Henning O.; Barabash, Alexander S.; Bergevin, M.; Bertrand, F.; Boswell, M.; Brudanin, V.; Busch, Matthew; Chan, Yuen-Dat; Christofferson, Cabot-Ann; Collar, J. I.; Combs, Dustin C.; Cooper, R. J.; Detwiler, Jason A.; Doe, Peter J.; Efremenko, Yuri; Egorov, Viatcheslav; Ejiri, H.; Elliott, Steven R.; Esterline, James H.; Fast, James E.; Fields, N.; Finnerty, P.; Fraenkle, Florian; Gehman, Victor; Giovanetti, G. K.; Green, Matthew P.; Guiseppe, Vincente; Gusey, K.; Hallin, A. L.; Hazama, R.; Henning, Reyco; Hime, Andrew; Hoppe, Eric W.; Horton, Mark; Howard, Stanley; Howe, M. A.; Johnson, R. A.; Keeter, K.; Keller, C.; Kidd, Mary; Knecht, A.; Kochetov, Oleg; Konovalov, S.; Kouzes, Richard T.; LaFerriere, Brian D.; LaRoque, B. H.; Leon, Jonathan D.; Leviner, L.; Loach, J. C.; MacMullin, S.; Marino, Michael G.; Martin, R. D.; Mei, Dong-Ming; Merriman, Jason H.; Miller, M. L.; Mizouni, Leila; Nomachi, Masaharu; Orrell, John L.; Overman, Nicole R.; Poon, Alan; Perumpilly, Gopakumar; Prior, Gersende; Radford, D. C.; Rielage, Keith; Robertson, R. G. H.; Ronquest, M. C.; Schubert, Alexis G.; Shima, T.; Shirchenko, M.; Snavely, Kyle J.; Steele, David; Strain, J.; Thomas, K.; Timkin, V.; Tornow, W.; Vanyushin, I.; Varner, R. L.; Vetter, Kai; Vorren, Kris R.; Wilkerson, J. F.; Wolfe, B. A.; Yakushev, E.; Young, A.; Yu, Chang-Hong; Yumatov, Vladimir; Zhang, C.

    2012-12-01

    The observation of neutrinoless double-beta decay would resolve the Majorana nature of the neutrino and could provide information on the absolute scale of the neutrino mass. The initial phase of the Majorana Experiment, known as the Demonstrator, will house 40 kg of Ge in an ultra-low background shielded environment at the 4850' level of the Sanford Underground Laboratory in Lead, SD. The objective of the Demonstrator is to validate whether a future 1-tonne experiment can achieve a background goal of one count per tonne-year in a narrow region of interest around the 76Ge neutrinoless double-beta decay peak.

  12. Ultra-low-frequency electromagnetic waves in the Earth's crust and magnetosphere

    International Nuclear Information System (INIS)

    Guglielmi, A V

    2007-01-01

    Research on natural intra- and extraterrestrially produced electromagnetic waves with periods ranging from 0.2 to 600 s is reviewed. The way in which the energy of rock movements transforms into the energy of an alternating magnetic field is analyzed. Methods for detecting seismomagnetic signals against a strong background are described. In discussing the physics of ultra-low-frequency waves in the magnetosphere, the 11-year activity modulation of 1-Hz waves and ponderomotive forces affecting plasma distribution are emphasized. (reviews of topical problems)

  13. Analysis of recrystallization and grain growth in ultra low carbon steels using EBSD

    International Nuclear Information System (INIS)

    Novillo, E.; Petite, M. M.; Bocos, J. L.; Gutierrez, I.

    2004-01-01

    This work is focused on the study of recrystallization texture and micro texture in a cold rolled ultra low carbon steel and its relationship with the global texture. Aspects like nucleation, evolution of the volume fraction and grain size were considered. An important grain selection associated with a significant size and number advantages of the recrystallized grains is observed. This grain selection gives rise to the development, at the latest stages of recrystallization, of a strong γ-fibre associated to good drawing properties. (Author) 24 refs

  14. Simultaneous measurement of tritium and radiocarbon by ultra-low-background proportional counting.

    Science.gov (United States)

    Mace, Emily; Aalseth, Craig; Alexander, Tom; Back, Henning; Day, Anthony; Hoppe, Eric; Keillor, Martin; Moran, Jim; Overman, Cory; Panisko, Mark; Seifert, Allen

    2017-08-01

    Use of ultra-low-background capabilities at Pacific Northwest National Laboratory provide enhanced sensitivity for measurement of low-activity sources of tritium and radiocarbon using proportional counters. Tritium levels are nearly back to pre-nuclear test backgrounds (~2-8 TU in rainwater), which can complicate their dual measurement with radiocarbon due to overlap in the beta decay spectra. We present results of single-isotope proportional counter measurements used to analyze a dual-isotope methane sample synthesized from ~120mg of H 2 O and present sensitivity results. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Ultrastructural Study on Ultra-Low Frequency Electromagnetic Fields and Transfer Factor Effects on Skin Ulcers

    International Nuclear Information System (INIS)

    Cadena, M. S. Reyes; Chapul, L. Sanchez; Perez, Javier; Garcia, M. N. Jimenez; Lopez, M. A. Jimenez; Espindola, M. E. Sanchez; Perez, R. Paniagua; Hernandez, N. A.; Paniagua, G.; Uribe, F.; Nava, J. J. Godina; Segura, M. A. Rodriguez

    2008-01-01

    We determined the effect of 120Hz ultra low frequency electromagnetic field (ELF) on the healing process of skin in 20 Wistar rats distributed in four groups in which chronic dermal ulcers had been produced. The first two groups received a dose of the transfer factor and interferon-beta (IFN-β) every 24 h during 12 days. The third group (positive control) received only electromagnetic field (ELF) sessions, and in the fourth group (negative control), no treatment was applied. The electromagnetic field was applied through a Helmholtz coils; 30 Gauss of intensity. Results shown histological changes that improve the healing process in animals subjected to ELF together with the transfer factor

  16. 65NM sub-threshold 11T-SRAM for ultra low voltage applications

    DEFF Research Database (Denmark)

    Moradi, Farshad; Wisland, Dag T.; Aunet, Snorre

    In this paper a new ultra low power SRAM cell is proposed. In the proposed SRAM topology, additional circuitry has been added to a standard 6T-SRAM cell to improve the static noise margin (SNM) and the performance. Foundry models for a 65 nm standard CMOS process were used for obtaining reliable...... simulated results. The circuit was simulated for supply voltages from 0.2 V to 0.35 V verifying the robustness of the proposed circuit for different supply voltages. The simulations show a significant improvement in SNM and a 4X improvement in read speed still maintaining a satisfactory write noise margin...

  17. Design Margin Elimination Through Robust Timing Error Detection at Ultra-Low Voltage

    OpenAIRE

    Reyserhove, Hans; Dehaene, Wim

    2017-01-01

    This paper discusses a timing error masking-aware ARM Cortex M0 microcontroller system. Through in-path timing error detection, operation at the point-of-first-failure is possi- ble without corrupting the pipeline state, effectively eliminat- ing traditional timing margins. Error events are flagged and gathered to allow dynamic voltage scaling. The error-aware microcontroller was implemented in a 40nm CMOS process and realizes ultra-low voltage operation down to 0.29V at 5MHz consuming 12.90p...

  18. Jump chaotic behaviour of ultra low loss bulk acoustic wave cavities

    Energy Technology Data Exchange (ETDEWEB)

    Goryachev, Maxim, E-mail: maxim.goryachev@uwa.edu.au; Farr, Warrick G.; Tobar, Michael E. [ARC Centre of Excellence for Engineered Quantum Systems, University of Western Australia, 35 Stirling Highway, Crawley WA 6009 (Australia); Galliou, Serge [Department of Time and Frequency, FEMTO-ST Institute, ENSMM, 26 Chemin de l' Épitaphe 25000 Besançon (France)

    2014-08-11

    We demonstrate a previously unobserved nonlinear phenomenon in an ultra-low loss quartz bulk acoustic wave cavity (Q>3>10{sup 9}), which only occurs below 20 mK in temperature and under relatively weak pumping. The phenomenon reveals the emergence of several stable equilibria (at least two foci and two nodes) and jumps between these quasi states at random times. The degree of this randomness as well as separations between levels can be controlled by the frequency of the incident carrier signal. It is demonstrated that the nature of the effect lies beyond the standard Duffing model.

  19. Capacitively coupled EMG detection via ultra-low-power microcontroller STFT.

    Science.gov (United States)

    Roland, Theresa; Baumgartner, Werner; Amsuess, Sebastian; Russold, Michael F

    2017-07-01

    As motion artefacts are a major problem with electromyography sensors, a new algorithm is developed to differentiate artefacts to contraction EMG. The performance of myoelectric prosthesis is increased with this algorithm. The implementation is done for an ultra-low-power microcontroller with limited calculation resources and memory. Short Time Fourier Transformation is used to enable real-time application. The sum of the differences (SOD) of the currently measured EMG to a reference contraction EMG is calculated. The SOD is a new parameter introduced for EMG classification. The satisfactory error rates are determined by measurements done with the capacitively coupling EMG prototype, recently developed by the research group.

  20. Know thy reservoir : multi-disciplinary shale gas solution integrates cased hole evaluation interpretation and stimulation

    Energy Technology Data Exchange (ETDEWEB)

    Smith, M.

    2009-11-15

    This article discussed Schlumberger's efforts in making shale gas a priority. Shale gas plays require maximum reservoir exposure to be economic. The exploitation of shale gas has been solved through the use of long horizontal wells that are fractured in multiple zones along their length. Companies have invested heavily into research to find increasingly novel ways to reduce costs and extract more molecules of gas from the ultra-low permeability rock. The tools and techniques that Schlumberger has developed for well stimulation and completion were described. Schlumberger was extremely focused on improving its ability to understand the Horn River reservoir and improve completion practices. Openhole logging was discussed as an option. Schlumberger in conjunction with its in-house data and consulting services group, also devised a method to log a lateral well after it had been cased, cemented, and the rig had been released. It was concluded that using such instruments as spectroscopy logging, epithermal neutron porosity logging and multidimensional shear sonic logging tools, Schlumberger could provide all the necessary measurements post-casing. 2 refs., 3 figs.

  1. Crustal permeability

    Science.gov (United States)

    Gleeson, Tom; Ingebritsen, Steven E.

    2016-01-01

    Permeability is the primary control on fluid flow in the Earth’s crust and is key to a surprisingly wide range of geological processes, because it controls the advection of heat and solutes and the generation of anomalous pore pressures.  The practical importance of permeability – and the potential for large, dynamic changes in permeability – is highlighted by ongoing issues associated with hydraulic fracturing for hydrocarbon production (“fracking”), enhanced geothermal systems, and geologic carbon sequestration.  Although there are thousands of research papers on crustal permeability, this is the first book-length treatment.  This book bridges the historical dichotomy between the hydrogeologic perspective of permeability as a static material property and the perspective of other Earth scientists who have long recognized permeability as a dynamic parameter that changes in response to tectonism, fluid production, and geochemical reactions. 

  2. Ultra-low-pressure sputtering to improve exchange bias and tune linear ranges in spin valves

    Energy Technology Data Exchange (ETDEWEB)

    Tang, XiaoLi, E-mail: tangtang1227@163.com; Yu, You; Liu, Ru; Su, Hua; Zhang, HuaiWu; Zhong, ZhiYong; Jing, YuLan

    2017-05-01

    A series of CoFe/IrMn exchange bilayers was grown by DC-sputtering at different ultra-low argon pressures ranging from 0.008 to 0.1 Pa. This pressure range was one to two orders lower than the normal sputtering pressure. Results revealed that the exchange bias increased from 140 to 250 Oe in CoFe(10 nm)/IrMn (15 nm) bilayers of fixed thickness because of the improved crystalline structure and morphological uniformity of films. Since ferromagnetic /antiferromagnetic (FM/AF) bilayers are always used in linear magnetic sensors as detection layers, the varying exchange bias can successfully achieve tunable linear range in a crossed pinning spin valve. The linear range could be adjustable from −80 Oe – +80 Oe to −150 Oe – +150 Oe on the basis of giant magnetoresistance responses. Therefore, this method provides a simple method to tune the operating range of magnetic field sensors. - Highlights: • Increasing exchange bias was achieved in bilayer at ultra-low-pressure sputtering. • The low void density and smooth surface were achieved in low pressure. • Varying exchange bias achieved tunable linear range in spin valve.

  3. Ultra low nanowear in novel chromium/amorphous chromium carbide nanocomposite films

    Science.gov (United States)

    Yate, Luis; Martínez-de-Olcoz, Leyre; Esteve, Joan; Lousa, Arturo

    2017-10-01

    In this work, we report the first observation of novel nanocomposite thin films consisting of nanocrystalline chromium embedded in an amorphous chromium carbide matrix (nc-Cr/a-CrC) with relatively high hardness (∼22,3 GPa) and ultra low nanowear. The films were deposited onto silicon substrates using a magnetic filtered cathodic arc deposition system at various negative bias voltages, from 50 to 450 V. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) suggested the co-existence of chromium and chromium carbide phases, while high resolution transmission electron microscopy (HRTEM) confirmed the presence of the nc-Cr/a-CrC structure. The friction coefficient measured with the ball-on disk technique and the nanowear results showed a strong correlation between the macro and nano-tribological properties of the samples. These novel nanocomposite films show promising properties as solid lubricant and wear resistant coatings with relatively high hardness, low friction coefficient and ultra low nanowear.

  4. Operator dependency of the radiation exposure in cardiac interventions: feasibility of ultra low dose levels

    International Nuclear Information System (INIS)

    Emre Ozpelit, Mehmet; Ercan, Ertugrul; Pekel, Nihat; Tengiz, Istemihan; Yilmaz, Akar; Ozpelit, Ebru; Ozyurtlu, Ferhat

    2017-01-01

    Introduction: Mean radiation exposure in invasive cardiology varies greatly between different centres and interventionists. The International Commission on Radiological Protection and the EURATOM Council stipulate that, despite reference values, 'All medical exposure for radiodiagnostic purposes shall be kept as low as reasonably achievable' (ALARA). The purpose of this study is to establish the effects of the routine application of ALARA principles and to determine operator and procedure impact on radiation exposure in interventional cardiology. Materials and methods: A total of 240 consecutive cardiac interventional procedures were analysed. Five operators performed the procedures, two of whom were working in accordance with ALARA principles (Group 1 operators) with the remaining three working in a standard manner (Group 2 operators). Radiation exposure levels of these two groups were compared. Results: Total fluoroscopy time and the number of radiographic runs were similar between groups. However, dose area product and cumulative dose were significantly lower in Group 1 when compared with Group 2. Radiation levels of Group 1 were far below even the reference levels in the literature, thus representing an ultra-low-dose radiation exposure in interventional cardiology. Conclusion: By use of simple radiation reducing techniques, ultra-low-dose radiation exposure is feasible in interventional cardiology. Achievability of such levels depends greatly on operator awareness, desire, knowledge and experience of radiation protection. (authors)

  5. Controlling low-rate signal path microdischarge for an ultra-low-background proportional counter

    International Nuclear Information System (INIS)

    Mace, E.K.; Aalseth, C.E.; Bonicalzi, R.M.; Day, A.R.; Hoppe, E.W.; Keillor, M.E.; Myers, A.W.; Overman, C.T.; Seifert, A.

    2013-01-01

    Pacific Northwest National Laboratory (PNNL) has developed an ultra-low-background proportional counter (ULBPC) made of high purity copper. These detectors are part of an ultra-low-background counting system (ULBCS) in the newly constructed shallow underground laboratory at PNNL (at a depth of ∼30 m water-equivalent). To control backgrounds, the current preamplifier electronics are located outside the ULBCS shielding. Thus the signal from the detector travels through ∼1 m of cable and is potentially susceptible to high voltage microdischarge and other sources of electronic noise. Based on initial successful tests, commercial cables and connectors were used for this critical signal path. Subsequent testing across different batches of commercial cables and connectors, however, showed unwanted (but still low) rates of microdischarge noise. To control this noise source, two approaches were pursued: first, to carefully validate cables, connectors, and other commercial components in this critical signal path, making modifications where necessary; second, to develop a custom low-noise, low-background preamplifier that can be integrated with the ULBPC and thus remove most commercial components from the critical signal path. This integrated preamplifier approach is based on the Amptek A250 low-noise charge-integrating preamplifier module. The initial microdischarge signals observed are presented and characterized according to the suspected source. Each of the approaches for mitigation is described, and the results from both are compared with each other and with the original performance seen with commercial cables and connectors. (author)

  6. Note: Expanding the bandwidth of the ultra-low current amplifier using an artificial negative capacitor.

    Science.gov (United States)

    Xie, Kai; Liu, Yan; Li, XiaoPing; Guo, Lixin; Zhang, Hanlu

    2016-04-01

    The bandwidth and low noise characteristics are often contradictory in ultra-low current amplifier, because an inevitable parasitic capacitance is paralleled with the high value feedback resistor. In order to expand the amplifier's bandwidth, a novel approach was proposed by introducing an artificial negative capacitor to cancel the parasitic capacitance. The theory of the negative capacitance and the performance of the improved amplifier circuit with the negative capacitor are presented in this manuscript. The test was conducted by modifying an ultra-low current amplifier with a trans-impedance gain of 50 GΩ. The results show that the maximum bandwidth was expanded from 18.7 Hz to 3.3 kHz with more than 150 times of increase when the parasitic capacitance (∼0.17 pF) was cancelled. Meanwhile, the rise time decreased from 18.7 ms to 0.26 ms with no overshot. Any desired bandwidth or rise time within these ranges can be obtained by adjusting the ratio of cancellation of the parasitic and negative capacitance. This approach is especially suitable for the demand of rapid response to weak current, such as transient ion-beam detector, mass spectrometry analysis, and fast scanning microscope.

  7. Ultra-low current biosensor output detection using portable electronic reader

    Science.gov (United States)

    Yahaya, N. A. N.; Rajapaksha, R. D. A. A.; Uda, M. N. Afnan; Hashim, U.

    2017-09-01

    Generally, the electrical biosensor usually shows extremely low current signal output around pico ampere to microampere range. In this research, electronic reader with amplifier has been demonstrated to detect ultra low current via the biosensor. The operational amplifier Burr-Brown OPA 128 and Arduino Uno board were used to construct the portable electronic reader. There are two cascaded inverting amplifier were used to detect ultra low current through the biosensor from pico amperes (pA) to nano amperes ranges (nA). A small known input current was form by applying variable voltage between 0.1V to 5.0V across a 5GΩ high resistor to check the amplifier circuit. The amplifier operation was measured with the high impedance current source and has been compared with the theoretical measurement. The Arduino Uno was used to convert the analog signal to digital signal and process the data to display on reader screen. In this project, Proteus software was used to design and test the circuit. Then it was implemented together with Arduino Uno board. Arduino board was programmed using C programming language to make whole circuit communicate each order. The current was measured then it shows a small difference values compared to theoretical values, which is approximately 14pA.

  8. Ultra-low thermal expansion realized in giant negative thermal expansion materials through self-compensation

    Science.gov (United States)

    Shen, Fei-Ran; Kuang, Hao; Hu, Feng-Xia; Wu, Hui; Huang, Qing-Zhen; Liang, Fei-Xiang; Qiao, Kai-Ming; Li, Jia; Wang, Jing; Liu, Yao; Zhang, Lei; He, Min; Zhang, Ying; Zuo, Wen-Liang; Sun, Ji-Rong; Shen, Bao-Gen

    2017-10-01

    Materials with zero thermal expansion (ZTE) or precisely tailored thermal expansion are in urgent demand of modern industries. However, the overwhelming majority of materials show positive thermal expansion. To develop ZTE or negative thermal expansion (NTE) materials as compensators has become an important challenge. Here, we present the evidence for the realization of ultra-low thermal expansion in Mn-Co-Ge-In particles. The bulk with the Ni2In-type hexagonal structure undergoes giant NTE owing to a martensitic magnetostructural transition. The major finding is that the thermal expansion behavior can be totally controlled by modulating the crystallinity degree and phase transition from atomic scale. Self-compensation effect leads to ultra-low thermal expansion with a linear expansion coefficient as small as +0.68 × 10-6/K over a wide temperature range around room temperature. The present study opens an avenue to reach ZTE particularly from the large class of giant NTE materials based on phase transition.

  9. Ultra-low thermal expansion realized in giant negative thermal expansion materials through self-compensation

    Directory of Open Access Journals (Sweden)

    Fei-Ran Shen

    2017-10-01

    Full Text Available Materials with zero thermal expansion (ZTE or precisely tailored thermal expansion are in urgent demand of modern industries. However, the overwhelming majority of materials show positive thermal expansion. To develop ZTE or negative thermal expansion (NTE materials as compensators has become an important challenge. Here, we present the evidence for the realization of ultra-low thermal expansion in Mn–Co–Ge–In particles. The bulk with the Ni2In-type hexagonal structure undergoes giant NTE owing to a martensitic magnetostructural transition. The major finding is that the thermal expansion behavior can be totally controlled by modulating the crystallinity degree and phase transition from atomic scale. Self-compensation effect leads to ultra-low thermal expansion with a linear expansion coefficient as small as +0.68 × 10−6/K over a wide temperature range around room temperature. The present study opens an avenue to reach ZTE particularly from the large class of giant NTE materials based on phase transition.

  10. Note: Expanding the bandwidth of the ultra-low current amplifier using an artificial negative capacitor

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Kai, E-mail: kaixie@mail.xidian.edu.cn; Liu, Yan; Li, XiaoPing [School of Aerospace Science and Technology, Xidian University, Xi’an 710071 (China); Guo, Lixin [School of Physics and Optoelectronic Engineering, Xidian University, Xi’an 710071 (China); Zhang, Hanlu [School of Communication & Information Engineering, Xi’an University of Posts & Telecommunication, Xi’an 710121 (China)

    2016-04-15

    The bandwidth and low noise characteristics are often contradictory in ultra-low current amplifier, because an inevitable parasitic capacitance is paralleled with the high value feedback resistor. In order to expand the amplifier’s bandwidth, a novel approach was proposed by introducing an artificial negative capacitor to cancel the parasitic capacitance. The theory of the negative capacitance and the performance of the improved amplifier circuit with the negative capacitor are presented in this manuscript. The test was conducted by modifying an ultra-low current amplifier with a trans-impedance gain of 50 GΩ. The results show that the maximum bandwidth was expanded from 18.7 Hz to 3.3 kHz with more than 150 times of increase when the parasitic capacitance (∼0.17 pF) was cancelled. Meanwhile, the rise time decreased from 18.7 ms to 0.26 ms with no overshot. Any desired bandwidth or rise time within these ranges can be obtained by adjusting the ratio of cancellation of the parasitic and negative capacitance. This approach is especially suitable for the demand of rapid response to weak current, such as transient ion-beam detector, mass spectrometry analysis, and fast scanning microscope.

  11. Effect of weld metal toughness on fracture behavior under ultra-low cycle fatigue loading (earthquake)

    Energy Technology Data Exchange (ETDEWEB)

    Kermajani, M. [School of Materials Engineering, College of Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Ghaini, F. Malek, E-mail: Fmalek@modares.ac.ir [School of Materials Engineering, College of Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Miresmaeili, R. [School of Materials Engineering, College of Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Aghakouchak, A.A. [School of Civil Engineering, College of Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Shadmand, M. [Department of Research and Development, MAPNA Electric and Control (MECO) Company, Karaj (Iran, Islamic Republic of)

    2016-06-21

    Results from 12 ultra-low cycle fatigue tests performed on the weld metals of both toughness and non-toughness rated grades are presented. Fracture resistance under these loadings seemed to be dependent on materials' toughness, displacement amplitude, and stress state triaxiality, while the toughness effect was more highlighted at high stress levels and concentrations. To study the effect of microstructures on these failures, supporting ancillary tests including all-weld tension coupons, Charpy V-notched impact tests, and optical and scanning electron microscope analyses were performed. The favored microstructures appeared to be those which absorbed energy by plastic deformation and, hence, hindered void formation and/or could avoid crack propagation by deflection. Considering the response of the tested materials to cyclic loadings and the requirements of the materials specified in AISC341 Provisions could question the adequacy of these requirements for weld metals. However, the role of microstructural features like inclusions would be the same in both the Charpy impact tests and ultra-low cycle loadings.

  12. Calibration of an ultra-low-background proportional counter for measuring 37Ar

    International Nuclear Information System (INIS)

    Seifert, A.; Aalseth, C. E.; Bonicalzi, R. M.; Bowyer, T. W.; Day, A. R.; Fuller, E. S.; Haas, D. A.; Hayes, J. C.; Hoppe, E. W.; Humble, P. H.; Keillor, M. E.; LaFerriere, B. D.; Mace, E. K.; McIntyre, J. I.; Merriman, J. H.; Miley, H. S.; Myers, A. W.; Orrell, J. L.; Overman, C. T.; Panisko, M. E.

    2013-01-01

    An ultra-low-background proportional counter design has been developed at Pacific Northwest National Laboratory (PNNL) using clean materials, primarily electro-chemically-purified copper. This detector, along with an ultra-low-background counting system (ULBCS), was developed to complement a new shallow underground laboratory (30 meters water-equivalent) at PNNL. The ULBCS design includes passive neutron and gamma shielding, along with an active cosmic-veto system. This system provides a capability for making ultra-sensitive measurements to support applications like age-dating soil hydrocarbons with 14 C/ 3 H, age-dating of groundwater with 39 Ar, and soil-gas assay for 37 Ar to support On-Site Inspection (OSI). On-Site Inspection is a key component of the verification regime for the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Measurements of radionuclides created by an underground nuclear explosion are valuable signatures of a Treaty violation. For OSI, the 35-day half-life of 37 Ar, produced from neutron interactions with calcium in soil, provides both high specific activity and sufficient time for inspection before decay limits sensitivity. This work describes the calibration techniques and analysis methods developed to enable quantitative measurements of 37 Ar samples over a broad range of proportional counter operating pressures. These efforts, along with parallel work in progress on gas chemistry separation, are expected to provide a significant new capability for 37 Ar soil gas background studies

  13. Molybdenum disulfide for ultra-low detection of free radicals: electrochemical response and molecular modeling

    Science.gov (United States)

    Gupta, Ankur; Rawal, Takat B.; Neal, Craig J.; Das, Soumen; Rahman, Talat S.; Seal, Sudipta

    2017-06-01

    Two-dimensional (2D) molybdenum disulfide (MoS2) offers attractive properties due to its band gap modulation and has led to significant research-oriented applications (i.e. DNA and protein detection, cell imaging (fluorescent label) etc.). In biology, detection of free radicals (i.e. reactive oxygen species and reactive nitrogen (NO*) species are very important for early discovery and treatment of diseases. Herein, for the first time, we demonstrate the ultra-low (pico-molar) detection of pharmaceutically relevant free radicals using MoS2 for electrochemical sensing. We present pico- to nano- molar level sensitivity in smaller MoS2 with S-deficiency as revealed by x-ray photoelectron spectroscopy. Furthermore, the detection mechanism and size-dependent sensitivity have been investigated by density functional theory (DFT) showing the change in electronic density of states of Mo atoms at edges which lead to the preferred adsorption of H2O2 on Mo edges. The DFT analysis signifies the role of size and S-deficiency in the higher catalytic activity of smaller MoS2 particles and, thus, ultra-low detection.

  14. Investigation of ultra low-dose scans in the context of quantum-counting clinical CT

    Science.gov (United States)

    Weidinger, T.; Buzug, T. M.; Flohr, T.; Fung, G. S. K.; Kappler, S.; Stierstorfer, K.; Tsui, B. M. W.

    2012-03-01

    In clinical computed tomography (CT), images from patient examinations taken with conventional scanners exhibit noise characteristics governed by electronics noise, when scanning strongly attenuating obese patients or with an ultra-low X-ray dose. Unlike CT systems based on energy integrating detectors, a system with a quantum counting detector does not suffer from this drawback. Instead, the noise from the electronics mainly affects the spectral resolution of these detectors. Therefore, it does not contribute to the image noise in spectrally non-resolved CT images. This promises improved image quality due to image noise reduction in scans obtained from clinical CT examinations with lowest X-ray tube currents or obese patients. To quantify the benefits of quantum counting detectors in clinical CT we have carried out an extensive simulation study of the complete scanning and reconstruction process for both kinds of detectors. The simulation chain encompasses modeling of the X-ray source, beam attenuation in the patient, and calculation of the detector response. Moreover, in each case the subsequent image preprocessing and reconstruction is modeled as well. The simulation-based, theoretical evaluation is validated by experiments with a novel prototype quantum counting system and a Siemens Definition Flash scanner with a conventional energy integrating CT detector. We demonstrate and quantify the improvement from image noise reduction achievable with quantum counting techniques in CT examinations with ultra-low X-ray dose and strong attenuation.

  15. Using MOF-74 for Hg{sup 2+} removal from ultra-low concentration aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Yang Yang; Li, Jian Qiang; Gong, Le Le; Feng, Xue Feng; Meng, Li Na; Zhang, Le; Meng, Pan Pan; Luo, Ming Biao; Luo, Feng, E-mail: ecitluofeng@163.com

    2017-02-15

    Mercury (Hg{sup 2+}) ions have very high toxicity and widely spread as environmental pollutants. At present, many efforts have been taken to remove the hazardous materials of mercury(II) by adsorption, and it is highly desirable to develop a novel adsorbent with high adsorptive capacities. However it is still a big challenge to remove the ultra-low-concentration mercury ions from water. In this paper, MOF-74-Zn is explored for such function, showing high removal rate of Hg(II) from water without any pretreatment, especially for the ultra-trace Hg(II) ions in the ppb magnitude with the removal rate reaching to 54.48%, 69.71%, 72.26% when the initial concentration of Hg(II) is 20ppb, 40ppb, 50ppb, respectively. - Graphical abstract: The absorption of mercury ions on MOF-74-Zn is due to somewhat weak interactions between MOF skeleton that is composed of carboxylate and hydroxy group and Hg2+ ions. - Highlights: • MOF-74-Zn shows high removal rate of Hg(II) from water without any pretreatment. • The MOF-74-Zn has a notable performance at ultra-low concentration of Hg(II). • MOF-74-Zn shows the potential for Hg(II) removal from industrial waste water.

  16. A University Consortium on Low Temperature Combustion for High Efficiency, Ultra-Low Emission Engines

    Energy Technology Data Exchange (ETDEWEB)

    Assanis, Dennis N. [Univ. of Michigan, Ann Arbor, MI (United States); Atreya, Arvind [Univ. of Michigan, Ann Arbor, MI (United States); Chen, Jyh-Yuan [Univ. of California, Berkeley, CA (United States); Cheng, Wai K. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Dibble, Robert W. [Univ. of California, Berkeley, CA (United States); Edwards, Chris [Stanford Univ., CA (United States); Filipi, Zoran S. [Univ. of Michigan, Ann Arbor, MI (United States); Gerdes, Christian [Stanford Univ., CA (United States); Im, Hong [Univ. of Michigan, Ann Arbor, MI (United States); Lavoie, George A. [Univ. of Michigan, Ann Arbor, MI (United States); Wooldridge, Margaret S. [Univ. of Michigan, Ann Arbor, MI (United States)

    2009-12-31

    The objective of the University consortium was to investigate the fundamental processes that determine the practical boundaries of Low Temperature Combustion (LTC) engines and develop methods to extend those boundaries to improve the fuel economy of these engines, while operating with ultra low emissions. This work involved studies of thermal effects, thermal transients and engine management, internal mixing and stratification, and direct injection strategies for affecting combustion stability. This work also examined spark-assisted Homogenous Charge Compression Ignition (HCCI) and exhaust after-treatment so as to extend the range and maximize the benefit of Homogenous Charge Compression Ignition (HCCI)/ Partially Premixed Compression Ignition (PPCI) operation. In summary the overall goals were; Investigate the fundamental processes that determine the practical boundaries of Low Temperature Combustion (LTC) engines; Develop methods to extend LTC boundaries to improve the fuel economy of HCCI engines fueled on gasoline and alternative blends, while operating with ultra low emissions; and Investigate alternate fuels, ignition and after-treatment for LTC and Partially Premixed compression Ignition (PPCI) engines.

  17. Perineal pseudocontinent colostomy for ultra-low rectal adenocarcinoma: the muscular graft as a pseudosphincter.

    Science.gov (United States)

    Souadka, Amine; Majbar, Mohammed Anass; Amrani, Laila; Souadka, Abdelilah

    2016-10-01

    The aim of this study was to analyze objectively the role of the muscular graft in the continence using manometric study in the patients who underwent pseudocontinent perineal colostomy after abdominoperineal resection for rectal adenocarcinoma. This was a retrospective study including all the patients from January 2002 to December 2009 who underwent an abdominoperineal resection followed by perineal pseudocontinent colostomy for ultra-low rectal adenocarcinoma and agreed to perform the manometric evaluation of the muscular graft. Fifteen patients were included, six males and nine females, with a mean age of 50 years. According to Kirwan's classification, 2 (13.3%) patients had normal continence (Stage A) had 10 (66.6%) no soiling (stage B) and 3 (20%) patients had minimal soiling (Stage C). The manometric evaluation was performed after a median period of 12 months post-surgery. The mean maximal resting and squeeze pressures were respectively 41 cmH2O and 59 cmH2O and the mean colonic sensory volume was 12 ml. This study showed that the musculae graft of Pseudocontinent Perineal colostomy acted as a hypotonic sphincter that pressure can increase during the voluntary squeeze. These data may help to clarify the functional outcomes of this technique after APR for ultra-low rectal adenocarcinoma.

  18. Using MOF-74 for Hg2+ removal from ultra-low concentration aqueous solution

    International Nuclear Information System (INIS)

    Xiong, Yang Yang; Li, Jian Qiang; Gong, Le Le; Feng, Xue Feng; Meng, Li Na; Zhang, Le; Meng, Pan Pan; Luo, Ming Biao; Luo, Feng

    2017-01-01

    Mercury (Hg 2+ ) ions have very high toxicity and widely spread as environmental pollutants. At present, many efforts have been taken to remove the hazardous materials of mercury(II) by adsorption, and it is highly desirable to develop a novel adsorbent with high adsorptive capacities. However it is still a big challenge to remove the ultra-low-concentration mercury ions from water. In this paper, MOF-74-Zn is explored for such function, showing high removal rate of Hg(II) from water without any pretreatment, especially for the ultra-trace Hg(II) ions in the ppb magnitude with the removal rate reaching to 54.48%, 69.71%, 72.26% when the initial concentration of Hg(II) is 20ppb, 40ppb, 50ppb, respectively. - Graphical abstract: The absorption of mercury ions on MOF-74-Zn is due to somewhat weak interactions between MOF skeleton that is composed of carboxylate and hydroxy group and Hg2+ ions. - Highlights: • MOF-74-Zn shows high removal rate of Hg(II) from water without any pretreatment. • The MOF-74-Zn has a notable performance at ultra-low concentration of Hg(II). • MOF-74-Zn shows the potential for Hg(II) removal from industrial waste water.

  19. Ultra-Low Noise Germanium Neutrino Detection system (ULGeN).

    Energy Technology Data Exchange (ETDEWEB)

    Cabrera-Palmer, Belkis [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Barton, Paul [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2017-07-01

    Monitoring nuclear power plant operation by measuring the antineutrino flux has become an active research field for safeguards and non-proliferation. We describe various efforts to demonstrate the feasibility of reactor monitoring based on the detection of the Coherent Neutrino Nucleus Scattering (CNNS) process with High Purity Germanium (HPGe) technology. CNNS detection for reactor antineutrino energies requires lowering the electronic noise in low-capacitance kg-scale HPGe detectors below 100 eV as well as stringent reduction in other particle backgrounds. Existing state- of-the-art detectors are limited to an electronic noise of 95 eV-FWHM. In this work, we employed an ultra-low capacitance point-contact detector with a commercial integrated circuit preamplifier- on-a-chip in an ultra-low vibration mechanically cooled cryostat to achieve an electronic noise of 39 eV-FWHM at 43 K. We also present the results of a background measurement campaign at the Spallation Neutron Source to select the area with sufficient low background to allow a successful first-time measurement of the CNNS process.

  20. Development of an underground HPGe array facility for ultra low radioactivity measurements

    Energy Technology Data Exchange (ETDEWEB)

    Sala, E.; Kang, W. G.; Kim, Y. D.; Lee, M. H.; Leonard, D. S. [Center for Underground Physics - Institute for Basic Science, Daejeon (Korea, Republic of); Hahn, I. S.; Kim, G. W.; Park, S. Y. [Ewha Womans University, Physics Department, Seoul (Korea, Republic of)

    2015-08-17

    Low Level Counting techniques using low background facilities are continuously under development to increase the possible sensitivity needed for rare physics events experiments. The CUP (Center for Underground Physics) group of IBS is developing, in collaboration with Canberra, a ultra low background instrument composed of two arrays facing each other with 7 HPGe detectors each. The low radioactive background of each detector has been evaluated and improved by the material selection of the detector components. Samples of all the building materials have been provided by the manufacturer and the contaminations had been measured using an optimized low background 100% HPGe with a dedicated shielding. The evaluation of the intrinsic background has been performed using MonteCarlo simulations and considering the contribution of each material with the measured contamination. To further reduce the background, the instrument will be placed in the new underground laboratory at YangYang exploiting the 700m mountain coverage and radon-free air supplying system. The array has been designed to perform various Ultra Low background measurements; the sensitivity we are expecting will allow not only low level measurements of Ra and Th contaminations in Copper or other usually pure materials, but also the search for rare decays. In particular some possible candidates and configurations to detect the 0νECEC (for example {sup 106}Cd and {sup 156}Dy) and rare β decays ({sup 96}Zr, {sup 180m}Ta , etc ) are under study.

  1. Measurement of ultra-low ion energy of decelerated ion beam using a deflecting electric field

    Energy Technology Data Exchange (ETDEWEB)

    Thopan, P.; Suwannakachorn, D.; Tippawan, U. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Yu, L.D., E-mail: yuld@thep-center.org [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand)

    2015-12-15

    In investigation on ultra-low-energy ion bombardment effect on DNA, an ion beam deceleration lens was developed for high-quality ultra-low-energy ion beam. Measurement of the ion energy after deceleration was necessary to confirm the ion beam really decelerated as theoretically predicted. In contrast to conventional methods, this work used a simple deflecting electrostatic field after the deceleration lens to bend the ion beam. The beam bending distance depended on the ion energy and was described and simulated. A system for the measurement of the ion beam energy was constructed. It consisted of a pair of parallel electrode plates to generate the deflecting electrical field, a copper rod measurement piece to detect ion beam current, a vernier caliper to mark the beam position, a stepping motor to translate the measurement rod, and a webcam-camera to read the beam bending distance. The entire system was installed after the ion-beam deceleration lens inside the large chamber of the bioengineering vertical ion beam line. Moving the measurement rod across the decelerated ion beam enabled to obtain beam profiles, from which the beam bending distance could be known and the ion beam energy could be calculated. The measurement results were in good agreement with theoretical and simulated results.

  2. Ultra-Low Power Sensor System for Disaster Event Detection in Metro Tunnel Systems

    Directory of Open Access Journals (Sweden)

    Jonah VINCKE

    2017-05-01

    Full Text Available In this extended paper, the concept for an ultra-low power wireless sensor network (WSN for underground tunnel systems is presented highlighting the chosen sensors. Its objectives are the detection of emergency events either from natural disasters, such as flooding or fire, or from terrorist attacks using explosives. Earlier works have demonstrated that the power consumption for the communication can be reduced such that the data acquisition (i.e. sensor sub-system becomes the most significant energy consumer. By using ultra-low power components for the smoke detector, a hydrostatic pressure sensor for water ingress detection and a passive acoustic emission sensor for explosion detection, all considered threats are covered while the energy consumption can be kept very low in relation to the data acquisition. In addition to 1 the sensor system is integrated into a sensor board. The total average power consumption for operating the sensor sub-system is measured to be 35.9 µW for lower and 7.8 µW for upper nodes.

  3. Continuous operation of an ultra-low-power microcontroller using glucose as the sole energy source.

    Science.gov (United States)

    Lee, Inyoung; Sode, Takashi; Loew, Noya; Tsugawa, Wakako; Lowe, Christopher Robin; Sode, Koji

    2017-07-15

    An ultimate goal for those engaged in research to develop implantable medical devices is to develop mechatronic implantable artificial organs such as artificial pancreas. Such devices would comprise at least a sensor module, an actuator module, and a controller module. For the development of optimal mechatronic implantable artificial organs, these modules should be self-powered and autonomously operated. In this study, we aimed to develop a microcontroller using the BioCapacitor principle. A direct electron transfer type glucose dehydrogenase was immobilized onto mesoporous carbon, and then deposited on the surface of a miniaturized Au electrode (7mm 2 ) to prepare a miniaturized enzyme anode. The enzyme fuel cell was connected with a 100 μF capacitor and a power boost converter as a charge pump. The voltage of the enzyme fuel cell was increased in a stepwise manner by the charge pump from 330mV to 3.1V, and the generated electricity was charged into a 100μF capacitor. The charge pump circuit was connected to an ultra-low-power microcontroller. Thus prepared BioCapacitor based circuit was able to operate an ultra-low-power microcontroller continuously, by running a program for 17h that turned on an LED every 60s. Our success in operating a microcontroller using glucose as the sole energy source indicated the probability of realizing implantable self-powered autonomously operated artificial organs, such as artificial pancreas. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Development of ultra-low pressure reverse osmosis membranes; Choteiatsu gyakushintomaku no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Hirose, M.; Ito, H.; Ohara, T. [Nitto Denko Corp., Osaka (Japan)

    1998-06-05

    Described herein is development of ultra-low pressure reverse osmosis (RO) membranes. The composite RO membrane, which is now widely used, has a cross-sectional structure consisting of an ultrafilter membrane as the support and a very thin skin layer responsible for filtration. It is confirmed that the skin layer is of a pleated structure. Growing this structure can greatly accelerate permeation of water without damaging arresting and durability characteristics of the membrane, and hence is a desired approach. Utilization of molecular structure simulation of the skin layer materials is investigated by the molecular dynamics. The results show that the stable structure of the material for the skin layer in the RO membrane is a network structure with regularly arranged honeycombs, when it should arrest at least 99% of salt. These techniques serve as the bases for development of the ultra-low pressure RO membranes (ES Series), where the skin layer is made of cross-linked, totally aromatic polyamide. The membrane passes twice as large a quantity of water as the conventional one, is highly resistant to chemicals, and arrests 99.7% of salt. 3 refs., 4 figs.

  5. Ultra-low-volume space sprays in mosquito control: a critical review.

    Science.gov (United States)

    Bonds, J A S

    2012-06-01

    The availability of tools to control mosquito (Diptera:Culicidae) vectors that transmit disease is often limited by a variety of economic, environmental and social issues. In emergency conditions (epidemics, hurricanes, floods etc.), the application of pesticides as space sprays (either by ground or air) is the common method of choice in order to rapidly limit adult local mosquito production in the affected area. Space spray application now employs ultra-low-volume technology for the control of adult mosquitoes. However, the use of space sprays often raises social and environmental concerns by the general public that is served. This review will define and illustrate modern ultra-low-volume technology for the purpose of application as a space spray, as well as describing the engineering controls that have been developed to minimize the environmental impact. The primary social concern is validity and efficacy of application. To address this point, the review will attempt to synthesize the global literature to address the effectiveness of space sprays to significantly impact mosquito vectors in relation to human disease. © 2012 The Author. Medical and Veterinary Entomology © 2012 The Royal Entomological Society.

  6. Ultra-Low Noise Germanium Neutrino Detection system (ULGeN)

    International Nuclear Information System (INIS)

    Cabrera-Palmer, Belkis; Barton, Paul

    2017-01-01

    Monitoring nuclear power plant operation by measuring the antineutrino flux has become an active research field for safeguards and non-proliferation. We describe various efforts to demonstrate the feasibility of reactor monitoring based on the detection of the Coherent Neutrino Nucleus Scattering (CNNS) process with High Purity Germanium (HPGe) technology. CNNS detection for reactor antineutrino energies requires lowering the electronic noise in low-capacitance kg-scale HPGe detectors below 100 eV as well as stringent reduction in other particle backgrounds. Existing state- of-the-art detectors are limited to an electronic noise of 95 eV-FWHM. In this work, we employed an ultra-low capacitance point-contact detector with a commercial integrated circuit preamplifier- on-a-chip in an ultra-low vibration mechanically cooled cryostat to achieve an electronic noise of 39 eV-FWHM at 43 K. We also present the results of a background measurement campaign at the Spallation Neutron Source to select the area with sufficient low background to allow a successful first-time measurement of the CNNS process.

  7. Electrokinetic effects and fluid permeability

    International Nuclear Information System (INIS)

    Berryman, J.G.

    2003-01-01

    Fluid permeability of porous media depends mainly on connectivity of the pore space and two physical parameters: porosity and a pertinent length-scale parameter. Electrical imaging methods typically establish connectivity and directly measure electrical conductivity, which can then often be related to porosity by Archie's law. When electrical phase measurements are made in addition to the amplitude measurements, information about the pertinent length scale can then be obtained. Since fluid permeability controls the ability to flush unwanted fluid contaminants from the subsurface, inexpensive maps of permeability could improve planning strategies for remediation efforts. Detailed knowledge of fluid permeability is also important for oil field exploitation, where knowledge of permeability distribution in three dimensions is a common requirement for petroleum reservoir simulation and analysis, as well as for estimates on the economics of recovery

  8. Notional Permeability

    NARCIS (Netherlands)

    Kik, R.; Van den Bos, J.P.; Maertens, J.; Verhagen, H.J.; Van der Meer, J.W.

    2012-01-01

    Different layer design of a rock slope and under layers has a large effect on the strengths on the rock slope itself. In the stability formula developed of VAN DER MEER [1988] this effect is represented by the term Notional Permeability with symbol P. A more open, or permeable, structure underneath

  9. COST-EFFECTIVE CONTROL OF NOx WITH INTEGRATED ULTRA LOW-NOx BURNERS AND SNCR

    International Nuclear Information System (INIS)

    Hamid Farzan

    2001-01-01

    Coal-fired electric utilities are facing a serious challenge with regards to curbing their NO(sub x) emissions. At issue are the NO(sub x) contributions to the acid rain, ground level ozone, and particulate matter formation. Substantial NO(sub x) control requirements could be imposed under the proposed Ozone Transport Rule, National Ambient Air Quality Standards, and New Source Performance Standards. McDermott Technology, Inc. (MTI), Babcock and Wilcox (B and W), and Fuel Tech are teaming to provide an integrated solution for NO(sub x) control. The system will be comprised of an ultra low-NO(sub x) pulverized coal (PC) burner technology plus a urea-based, selective non-catalytic reduction (SNCR) system. This system will be capable of meeting a target emission limit of 0.15 lb NO(sub x)/10(sup 6) Btu and target ammonia (NH3) slip level targeted below 5 ppmV for commercial units. Our approach combines the best available combustion and post-combustion NO(sub x) control technologies. More specifically, B and W's DRB-4Z TM ultra low-NO(sub x) PC burner technology will be combined with Fuel Tech's NO(sub x)OUT (SNCR) and NO(sub x)OUT Cascade (SNCR/SCR hybrid) systems and jointly evaluated and optimized in a state-of-the-art test facility at MTI. Although the NO(sub x)OUT Cascade (SNCR/SCR hybrid) system will not be tested directly in this program, its potential application for situations that require greater NO(sub x) reductions will be inferred from other measurements (i.e., SNCR NO(sub x) removal efficiency plus projected NO(sub x) reduction by the catalyst based on controlled ammonia slip). Our analysis shows that the integrated ultra low-NO(sub x) burner and SNCR system has the lowest cost when the burner emissions are 0.25 lb NO(sub x)/10(sup 6) Btu or less. At burner NO(sub x) emission level of 0.20 lb NO(sub x)/10(sup 6) Btu, the levelized cost per ton of NO(sub x) removed is 52% lower than the SCR cost

  10. [Electric traction magnetic fields of ultra-low frequency as an occupational risk factor of ischemic heart disease].

    Science.gov (United States)

    Ptitsyna, N G; Kudrin, V A; Villorezi, D; Kopytenko, Iu A; Tiasto, M I; Kopytenko, E A; Bochko, V A; Iuchchi, N

    1996-01-01

    The study was inspired by earlier results that displayed influence of variable natural geomagnetic field (0.005-10 Hz range-ultra-low frequencies) on circulatory system, indicated possible correlation between industrial ultra-low frequency fields and prevalence of myocardial infarction. The authors conducted unique measurements of ultra-low frequency fields produced by electric engines. The results were compared with data on morbidity among railway transport workers. The findings are that level of magnetic variations in electric locomotive cabin can exceed 280 micro Tesla, whereas that in car sections reaches 50 micro Tesla. Occurrence of coronary heart disease among the locomotive operators appeared to be 2.0 + 0.2 times higher than that among the car section operators. Higher risk of coronary heart disease in the locomotive operators is associated with their increased occupational magnetic load.

  11. Robust and Energy-Efficient Ultra-Low-Voltage Circuit Design under Timing Constraints in 65/45 nm CMOS

    Directory of Open Access Journals (Sweden)

    David Bol

    2011-01-01

    Full Text Available Ultra-low-voltage operation improves energy efficiency of logic circuits by a factor of 10×, at the expense of speed, which is acceptable for applications with low-to-medium performance requirements such as RFID, biomedical devices and wireless sensors. However, in 65/45 nm CMOS, variability and short-channel effects significantly harm robustness and timing closure of ultra-low-voltage circuits by reducing noise margins and jeopardizing gate delays. The consequent guardband on the supply voltage to meet a reasonable manufacturing yield potentially ruins energy efficiency. Moreover, high leakage currents in these technologies degrade energy efficiency in case of long stand-by periods. In this paper, we review recently published techniques to design robust and energy-efficient ultra-low-voltage circuits in 65/45 nm CMOS under relaxed yet strict timing constraints.

  12. Evaluations of different domestic hot water preparing methods with ultra-low-temperature district heating

    DEFF Research Database (Denmark)

    Yang, Xiaochen; Li, Hongwei; Svendsen, Svend

    2016-01-01

    of Legionella in the DHW (domestic hot water) and assure the comfortable temperature, all substations were installed with supplementary heating devices. Detailed measurements were taken in the substations, including the electricity demand of the supplementary heating devices. To compare the energy and economic......This study investigated the performances of five different substation configurations in single-family houses supplied with ULTDH (ultra-low-temperature district heating). The temperature at the heat plant is 46 degrees C and around 40 degrees C at the substations. To avoid the proliferation...... performance of the substations, separate models were built based on standard assumptions. The relative heat and electricity delivered for preparing DHW were calculated. The results showed that substations with storage tanks and heat pumps have high relative electricity demand, which leads to higher integrated...

  13. TEMPERATURE ANISOTROPY IN THE PRESENCE OF ULTRA LOW FREQUENCY WAVES IN THE TERRESTRIAL FORESHOCK

    International Nuclear Information System (INIS)

    Selzer, L. A.; Hnat, B.; Osman, K. T.; Nakariakov, V. M.; Eastwood, J. P.; Burgess, D.

    2014-01-01

    We report the first study of the correlation between elevated solar wind core plasma temperatures and temperature anisotropy in the terrestrial foreshock. Plasma temperature is enhanced near the fire hose marginal stability threshold in the presence of ultra low frequency (ULF) large amplitude magnetic perturbations, which are intrinsically right-hand circularly polarized. Direct comparison of contemporaneous anisotropic temperatures in the upstream solar wind and the foreshock suggests that the net heating of plasma is mediated via increase of the parallel temperature in the foreshock region where the ULF waves are present. We consider the possibility that a mechanism based on Landau damping, where solar wind plasma temperature parallel to the background magnetic field is increased by interaction with oblique compressible fast magneto-acoustic ULF waves, influences temperature anisotropy

  14. TEMPERATURE ANISOTROPY IN THE PRESENCE OF ULTRA LOW FREQUENCY WAVES IN THE TERRESTRIAL FORESHOCK

    Energy Technology Data Exchange (ETDEWEB)

    Selzer, L. A.; Hnat, B.; Osman, K. T.; Nakariakov, V. M. [Centre for Fusion, Space and Astrophysics, University of Warwick, Coventry CV4 7AL (United Kingdom); Eastwood, J. P. [Space and Atmospheric Physics, The Blackett Laboratory, Imperial College London, London (United Kingdom); Burgess, D., E-mail: L.A.Selzer@warwick.ac.uk [School of Physics and Astronomy, Queen Mary University of London (United Kingdom)

    2014-06-10

    We report the first study of the correlation between elevated solar wind core plasma temperatures and temperature anisotropy in the terrestrial foreshock. Plasma temperature is enhanced near the fire hose marginal stability threshold in the presence of ultra low frequency (ULF) large amplitude magnetic perturbations, which are intrinsically right-hand circularly polarized. Direct comparison of contemporaneous anisotropic temperatures in the upstream solar wind and the foreshock suggests that the net heating of plasma is mediated via increase of the parallel temperature in the foreshock region where the ULF waves are present. We consider the possibility that a mechanism based on Landau damping, where solar wind plasma temperature parallel to the background magnetic field is increased by interaction with oblique compressible fast magneto-acoustic ULF waves, influences temperature anisotropy.

  15. Ultra-low-loss inverted taper coupler for silicon-on-insulator ridge waveguide

    DEFF Research Database (Denmark)

    Pu, Minhao; Liu, Liu; Ou, Haiyan

    2010-01-01

    An ultra-low-loss coupler for interfacing a silicon-on-insulator ridge waveguide and a single-mode fiber in both polarizations is presented. The inverted taper coupler, embedded in a polymer waveguide, is optimized for both the transverse-magnetic and transverse-electric modes through tapering...... the width of the silicon-on-insulator waveguide from 450 nm down to less than 15 nm applying a thermal oxidation process. Two inverted taper couplers are integrated with a 3-mm long silicon-on-insulator ridge waveguide in the fabricated sample. The measured coupling losses of the inverted taper coupler...... for transverse-magnetic and transverse-electric modes are ~0.36 dB and ~0.66 dB per connection, respectively....

  16. Ultra low density biodegradable shape memory polymer foams with tunable physical properties

    Science.gov (United States)

    Singhal, Pooja; Wilson, Thomas S.; Cosgriff-Hernandez, Elizabeth; Maitland, Duncan J.

    2017-12-12

    Compositions and/or structures of degradable shape memory polymers (SMPs) ranging in form from neat/unfoamed to ultra low density materials of down to 0.005 g/cc density. These materials show controllable degradation rate, actuation temperature and breadth of transitions along with high modulus and excellent shape memory behavior. A method of m ly low density foams (up to 0.005 g/cc) via use of combined chemical and physical aking extreme blowing agents, where the physical blowing agents may be a single compound or mixtures of two or more compounds, and other related methods, including of using multiple co-blowing agents of successively higher boiling points in order to achieve a large range of densities for a fixed net chemical composition. Methods of optimization of the physical properties of the foams such as porosity, cell size and distribution, cell openness etc. of these materials, to further expand their uses and improve their performance.

  17. Ultra low-noise differential ac-coupled photodetector for sensitive pulse detection applications

    International Nuclear Information System (INIS)

    Windpassinger, Patrick J; Boisen, Axel; Kjærgaard, Niels; Polzik, Eugene S; Müller, Jörg Helge; Kubasik, Marcin; Koschorreck, Marco

    2009-01-01

    We report on the performance of ultra low-noise differential photodetectors especially designed for probing of atomic ensembles with weak light pulses. The working principle of the detectors is described together with the analysis procedures employed to extract the photon shot noise of light pulses with ∼1 μs duration. As opposed to frequency response peaked detectors, our approach allows for broadband quantum noise measurements. The equivalent noise charge (ENC) for two different hardware approaches is evaluated to 280 and 340 electrons per pulse, respectively, which corresponds to a dark noise equivalent photon number of n 3dB = 0.8 × 10 5 and n 3dB = 1.2 × 10 5 in the two approaches. Finally, we discuss the possibility of removing classical correlations in the output signal caused by detector imperfection by using double-correlated sampling methods

  18. Development of contaminant detection system based on ultra-low field SQUID-NMR/MRI

    International Nuclear Information System (INIS)

    Tsunaki, S; Yamamoto, M; Hatta, J; Hatsukade, Y; Tanaka, S

    2014-01-01

    We have developed an ultra-low field (ULF) NMR/MRI system using an HTS-rf-SQUID and evaluated performance of the system as a contaminant detection system for foods and drinks. In this work, we measured 1D MRIs from water samples with or without various contaminants, such as aluminum and glass balls using the system. In the 1D MRIs, changes of the MRI spectra were detected, corresponding to positions of the contaminants. We measured 2D MRIs from food samples with and without a hole. In the 2D MRIs, the hole position in the sample was well visualized. These results show that the feasibility of the system to detect and localize contaminants in foods and drinks.

  19. Theory and experiment research for ultra-low frequency maglev vibration sensor

    International Nuclear Information System (INIS)

    Zheng, Dezhi; Liu, Yixuan; Guo, Zhanshe; Fan, Shangchun; Zhao, Xiaomeng

    2015-01-01

    A new maglev sensor is proposed to measure ultra-low frequency (ULF) vibration, which uses hybrid-magnet levitation structure with electromagnets and permanent magnets as the supporting component, rather than the conventional spring structure of magnetoelectric vibration sensor. Since the lower measurement limit needs to be reduced, the equivalent bearing stiffness coefficient and the equivalent damping coefficient are adjusted by the sensitivity unit structure of the sensor and the closed-loop control system, which realizes both the closed-loop control and the solving algorithms. A simple sensor experimental platform is then assembled based on a digital hardware system, and experimental results demonstrate that the lower measurement limit of the sensor is increased to 0.2 Hz under these experimental conditions, indicating promising results of the maglev sensor for ULF vibration measurements

  20. Ultra-low-temperature neutron diffraction. Final report, July 1, 1983-June 30, 1985. Final report

    International Nuclear Information System (INIS)

    Halperin, W.P.; Ketterson, J.B.

    1985-07-01

    An ultra-low-temperature neutron diffraction facility has been constructed at Argonne National Laboratory. The initial and primary purpose of this facility is to study nuclear magnetic ordering phenomenon. Magnetic structure information is commonly recognized as being fundamental to the progress in theoretical and experimental efforts in the field of magnetism. We have initiated study of the nuclear spin in solid 3 He and in metals. In 3 He the nuclear spins order at 1.1 mK. Structure information for neutron diffraction would contribute significantly to this problem of nuclear magnetism. Despite substantial experimental difficulties, careful evaluation suggests that examination of the nuclear structure in this unique quantum crystal is indeed feasible by neutron diffraction. Substantial progress has been made in growing single crystals of 3 He and establishing its temperature in the presence of a neutron flux. We have also initiated investigation of nuclear ordering in copper and PrCu 6

  1. Ultra-low field NMR for detection and characterization of 235 UF6

    Energy Technology Data Exchange (ETDEWEB)

    Espy, Michelle A [Los Alamos National Laboratory; Magnelind, Per E [Los Alamos National Laboratory; Matlashov, Andrei N [Los Alamos National Laboratory; Urbaitis, Algis V [Los Alamos National Laboratory; Volegov, Petr L [Los Alamos National Laboratory

    2009-01-01

    We have demonstrated the first ultra-low field (ULF) nuclear magnetic resonance measurements of uranium hexafluoride (UF{sub 6}), both depleted and 70% enriched, which is used in the uranium enrichment process. A sensitive non-invasive detection system would have an important role in non-proliferation surveillance. A two-frequency technique was employed to remove the transients induced by rapidly switching off the 50 mT pre-polarization field. A mean transverse relaxation time T{sub 2} of 24 ms was estimated for the un-enriched UF{sub 6} sample measured at a mean temperature of 80 C. Nuclear magnetic resonance at ULF has several advantages including the ability to measure through metal, such as pipes, and simple magnetic field generation hardware. We present here recent data and discuss the potential for non-proliferation monitoring of enrichment and flow velocity.

  2. Ultra-Low-Power Design and Hardware Security Using Emerging Technologies for Internet of Things

    Directory of Open Access Journals (Sweden)

    Jiann-Shiun Yuan

    2017-09-01

    Full Text Available In this review article for Internet of Things (IoT applications, important low-power design techniques for digital and mixed-signal analog–digital converter (ADC circuits are presented. Emerging low voltage logic devices and non-volatile memories (NVMs beyond CMOS are illustrated. In addition, energy-constrained hardware security issues are reviewed. Specifically, light-weight encryption-based correlational power analysis, successive approximation register (SAR ADC security using tunnel field effect transistors (FETs, logic obfuscation using silicon nanowire FETs, and all-spin logic devices are highlighted. Furthermore, a novel ultra-low power design using bio-inspired neuromorphic computing and spiking neural network security are discussed.

  3. Detection of ultra-low oxygen concentration based on the fluorescence blinking dynamics of single molecules

    Science.gov (United States)

    Wu, Ruixiang; Chen, Ruiyun; Zhou, Haitao; Qin, Yaqiang; Zhang, Guofeng; Qin, Chengbing; Gao, Yan; Gao, Yajun; Xiao, Liantuan; Jia, Suotang

    2018-01-01

    We present a sensitive method for detection of ultra-low oxygen concentrations based on the fluorescence blinking dynamics of single molecules. The relationship between the oxygen concentration and the fraction of time spent in the off-state, stemming from the population and depopulation of triplet states and radical cationic states, can be fitted with a two-site quenching model in the Stern-Volmer plot. The oxygen sensitivity is up to 43.42 kPa-1 in the oxygen partial pressure region as low as 0.01-0.25 kPa, which is seven times higher than that of the fluorescence intensity indicator. This method avoids the limitation of the sharp and non-ignorable fluctuations that occur during the measurement of fluorescence intensity, providing potential applications in the field of low oxygen-concentration monitoring in life science and industry.

  4. Design of an ultra-low-power digital processor for passive UHF RFID tags

    Energy Technology Data Exchange (ETDEWEB)

    Shi Wanggen; Zhuang Yiqi; Li Xiaoming; Wang Xianghua; Jin Zhao; Wang Dan, E-mail: wanggen_shi@163.co [Key Laboratory of the Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices, Institute of Microelectronics, Xidian University, Xi' an 710071 (China)

    2009-04-15

    A new architecture of digital processors for passive UHF radio-frequency identification tags is proposed. This architecture is based on ISO/IEC 18000-6C and targeted at ultra-low power consumption. By applying methods like system-level power management, global clock gating and low voltage implementation, the total power of the design is reduced to a few microwatts. In addition, an innovative way for the design of a true RNG is presented, which contributes to both low power and secure data transaction. The digital processor is verified by an integrated FPGA platform and implemented by the Synopsys design kit for ASIC flows. The design fits different CMOS technologies and has been taped out using the 2P4M 0.35 mum process of Chartered Semiconductor.

  5. Theory and experiment research for ultra-low frequency maglev vibration sensor

    Science.gov (United States)

    Zheng, Dezhi; Liu, Yixuan; Guo, Zhanshe; Zhao, Xiaomeng; Fan, Shangchun

    2015-10-01

    A new maglev sensor is proposed to measure ultra-low frequency (ULF) vibration, which uses hybrid-magnet levitation structure with electromagnets and permanent magnets as the supporting component, rather than the conventional spring structure of magnetoelectric vibration sensor. Since the lower measurement limit needs to be reduced, the equivalent bearing stiffness coefficient and the equivalent damping coefficient are adjusted by the sensitivity unit structure of the sensor and the closed-loop control system, which realizes both the closed-loop control and the solving algorithms. A simple sensor experimental platform is then assembled based on a digital hardware system, and experimental results demonstrate that the lower measurement limit of the sensor is increased to 0.2 Hz under these experimental conditions, indicating promising results of the maglev sensor for ULF vibration measurements.

  6. 39Ar/Ar measurements using ultra-low background proportional counters

    International Nuclear Information System (INIS)

    Hall, Jeter; Aalseth, Craig E.; Bonicalzi, Ricco M.; Brandenberger, Jill M.; Day, Anthony R.; Humble, Paul H.; Mace, Emily K.; Panisko, Mark E.; Seifert, Allen

    2016-01-01

    Age-dating groundwater and seawater using the 39 Ar/Ar ratio is an important tool to understand water mass-flow rates and mean residence time. Low-background proportional counters developed at Pacific Northwest National Laboratory use mixtures of argon and methane as counting gas. We demonstrate sensitivity to 39 Ar by comparing geological (ancient) argon recovered from a carbon dioxide gas well and commercial argon. The demonstrated sensitivity to the 39 Ar/Ar ratio is sufficient to date water masses as old as 1000 years. - Highlights: • 39 Ar/Ar age dating is important for understanding environmental water migration. • Ultra low background proportional counters have been developed. • 39 Ar is detected in atmospheric argon at a rate of 70.3 counts per day. The demonstrated background is 166 counts per day. • Age dating is possible for water with underground residence time of up to 1000 years.

  7. Formation mechanism of spheroidal carbide in ultra-low carbon ductile cast iron

    Directory of Open Access Journals (Sweden)

    Bin-guo Fu

    2016-09-01

    Full Text Available The formation mechanism of the spheroidal carbide in the ultra-low carbon ductile cast iron fabricated by the metal mold casting technique was systematically investigated. The results demonstrated that the spheroidal carbide belonged to eutectic carbide and crystallized in the isolated eutectic liquid phase area. The formation process of the spheroidal carbide was related to the contact and the intersection between the primary dendrite and the secondary dendrite of austenite. The oxides of magnesium, rare earths and other elements can act as heterogeneous nucleation sites for the spheroidal carbide. It was also found that the amount of the spheroidal carbide would increase with an increase in carbon content. The cooling rate has an important influence on the spheroidal carbide under the same chemical composition condition.

  8. Direct imaging of neural currents using ultra-low field magnetic resonance techniques

    Science.gov (United States)

    Volegov, Petr L [Los Alamos, NM; Matlashov, Andrei N [Los Alamos, NM; Mosher, John C [Los Alamos, NM; Espy, Michelle A [Los Alamos, NM; Kraus, Jr., Robert H.

    2009-08-11

    Using resonant interactions to directly and tomographically image neural activity in the human brain using magnetic resonance imaging (MRI) techniques at ultra-low field (ULF), the present inventors have established an approach that is sensitive to magnetic field distributions local to the spin population in cortex at the Larmor frequency of the measurement field. Because the Larmor frequency can be readily manipulated (through varying B.sub.m), one can also envision using ULF-DNI to image the frequency distribution of the local fields in cortex. Such information, taken together with simultaneous acquisition of MEG and ULF-NMR signals, enables non-invasive exploration of the correlation between local fields induced by neural activity in cortex and more `distant` measures of brain activity such as MEG and EEG.

  9. Electrical activation and spin coherence of ultra low doseantimony implants in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Schenkel, T.; Tyryshkin, A.M.; de Sousa, R.; Whaley, K.B.; Bokor,J.; Liddle, J.A.; Persaud, A.; Shangkuan, J.; Chakarov, I.; Lyon, S.A.

    2005-07-13

    We implanted ultra low doses (0.2 to 2 x 10{sup 11} cm{sup -2}) of Sb ions into isotopically enriched {sup 28}Si, and probed electrical activation and electron spin relaxation after rapid thermal annealing. Strong segregation of dopants towards both Si{sub 3}N{sub 4} and SiO{sub 2} interfaces limits electrical activation. Pulsed Electron Spin Resonance shows that spin echo decay is sensitive to the dopant profiles, and the interface quality. A spin decoherence time, T{sub 2}, of 1.5 ms is found for profiles peaking 25 nm below a Si/SiO{sub 2} interface, increasing to 2.1 ms when the surface is passivated with hydrogen. These measurements provide benchmark data for the development of devices in which quantum information is encoded in donor electron spins.

  10. Ultra-Low Power Consuming Direct Radiation Sensors Based on Floating Gate Structures

    Directory of Open Access Journals (Sweden)

    Evgeny Pikhay

    2017-07-01

    Full Text Available In this paper, we report on ultra-low power consuming single poly floating gate direct radiation sensors. The developed devices are intended for total ionizing dose (TID measurements and fabricated in a standard CMOS process flow. Sensor design and operation is discussed in detail. Original array sensors were suggested and fabricated that allowed high statistical significance of the radiation measurements and radiation imaging functions. Single sensors and array sensors were analyzed in combination with the specially developed test structures. This allowed insight into the physics of sensor operations and exclusion of the phenomena related to material degradation under irradiation in the interpretation of the measurement results. Response of the developed sensors to various sources of ionizing radiation (Gamma, X-ray, UV, energetic ions was investigated. The optimal design of sensor for implementation in dosimetry systems was suggested. The roadmap for future improvement of sensor performance is suggested.

  11. Ultra-low noise TES bolometer arrays for SAFARI instrument on SPICA

    Science.gov (United States)

    Khosropanah, P.; Suzuki, T.; Ridder, M. L.; Hijmering, R. A.; Akamatsu, H.; Gottardi, L.; van der Kuur, J.; Gao, J. R.; Jackson, B. D.

    2016-07-01

    SRON is developing ultra-low noise Transition Edge Sensors (TESs) based on a superconducting Ti/Au bilayer on a suspended SiN island with SiN legs for the SAFARI instrument aboard the SPICA mission. We successfully fabricated TESs with very narrow (0.5-0.7 μm) and thin (0.25 μm) SiN legs on different sizes of SiN islands using deep reactiveion etching process. The pixel size is 840x840 μm2 and there are variety of designs with and without optical absorbers. For TESs without absorbers, we measured electrical NEPs as low as <1x10-19 W/√Hz with response time of 0.3 ms and reached the phonon noise limit. Using TESs with absorbers, we quantified the darkness of our setup and confirmed a photon noise level of 2x10-19 W/√Hz.

  12. Ultra low field MR imaging of cervical spine involvement in rheumatoid arthritis

    Energy Technology Data Exchange (ETDEWEB)

    Fagerlund, M.; Bjoernebrink, J.; Ekelund, L.; Toolanen, G. (Umeaa Univ. Hospital (Sweden). Depts. of Diagnostic Radiology and Orthopedic Surgery)

    1992-03-01

    In a study of 30 patients with longstanding rheumatoid arthritis the diagnostic usefulness of ultra low field MR equipment was analyzed in assessing lesions of the craniocervical junction. It was found that at 0.04 T all the examinations were diagnostic and that in combination with plain radiography the diagnostic information obtained was valuable in further planning of the treatment strategies. The neurologic findings were related to the degree and severity of atlantoaxial luxation, either horizontal or vertical, and to the periodontoid pannus formation. The correlation between the degree of cord compression shown with MR imaging and the clinical symptoms, especially long tract symptoms, was poor. The only correlating factor was the duration of the disease. (orig.).

  13. Theory and experiment research for ultra-low frequency maglev vibration sensor

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Dezhi; Liu, Yixuan, E-mail: xuan61x@163.com; Guo, Zhanshe; Fan, Shangchun [School of Instrument Science and Opto-electronics Engineering, Beihang University, Beijing 100191 (China); Zhao, Xiaomeng [Laser Medicine Laboratory, Institute of Biomedical Engineering, Chinese Academy of medical Sciences and Peking Union Medical College, Tianjin 300192 (China)

    2015-10-15

    A new maglev sensor is proposed to measure ultra-low frequency (ULF) vibration, which uses hybrid-magnet levitation structure with electromagnets and permanent magnets as the supporting component, rather than the conventional spring structure of magnetoelectric vibration sensor. Since the lower measurement limit needs to be reduced, the equivalent bearing stiffness coefficient and the equivalent damping coefficient are adjusted by the sensitivity unit structure of the sensor and the closed-loop control system, which realizes both the closed-loop control and the solving algorithms. A simple sensor experimental platform is then assembled based on a digital hardware system, and experimental results demonstrate that the lower measurement limit of the sensor is increased to 0.2 Hz under these experimental conditions, indicating promising results of the maglev sensor for ULF vibration measurements.

  14. Ultra Low Voltage Class AB Switched Current Memory Cells Based on Floating Gate Transistors

    DEFF Research Database (Denmark)

    Mucha, Igor

    1999-01-01

    current memory cells were designed using a CMOS process with threshold voltages V-T0n = \\V-T0p\\ = 0.9 V for the n- and p-channel devices. Both hand calculations and PSPICE simulations showed that the designed example switched current memory cell allowed a maximum signal range better than +/-18 mu......A proposal for a class AB switched current memory cell, suitable for ultra-low-voltage applications is presented. The proposal employs transistors with floating gates, allowing to build analog building blocks for ultralow supply voltage operation also in CMOS processes with high threshold voltages....... This paper presents the theoretical basis for the design of "floating-gate'' switched current memory cells by giving a detailed description and analysis of the most important impacts degrading the performance of the cells. To support the theoretical assumptions circuits based on "floating-gate'' switched...

  15. Performance of ultra low temperature district heating systems with utility plant and booster heat pumps

    DEFF Research Database (Denmark)

    Ommen, Torben Schmidt; Thorsen, Jan Eric; Markussen, Wiebke Brix

    2017-01-01

    The optimal integration of booster heat pumps in ultra low temperature district heating (ULTDH) was investigated and compared to the performance of low temperature district heating. Two possible heat production technologies for the DH networks were analysed, namely extraction combined heat...... temperature and the heat consumption profile. For reference conditions, the optimal return of ULTDH varies between 21 °C and 27 °C. When using a central HP to supply the DH system, the resulting coefficient of system performance (COSP) was in the range of 3.9 (-) to 4.7 (-) for equipment with realistic...... component efficiencies and effectiveness, when including the relevant parameters such as DH system pressure and heat losses. By using ULTDH with booster HPs, performance improvements of 12% for the reference calculations case were found, if the system was supplied by central HPs. Opposite results were found...

  16. Seventy kilovolt ultra-low dose CT of the paranasal sinus: first clinical results

    International Nuclear Information System (INIS)

    Bodelle, B.; Wichmann, J.L.; Klotz, N.; Lehnert, T.; Vogl, T.J.; Luboldt, W.; Schulz, B.

    2015-01-01

    Aim: To evaluate the diagnostic image quality and radiation dose of low-dose 70 kV computed tomography (CT) of the paranasal sinus in comparison to 100 and 120 kV CT. Materials and methods: CT of the paranasal sinus was performed in 127 patients divided into three groups using different tube voltages and currents (70 kV/75 mAs, ultra-low dose protocol, n = 44; 100 kV/40 mAs, standard low-dose protocol, n = 42; 120 kV/40 mAs, standard protocol, n = 41). CT dose index (CTDIvol), dose–length product (DLP), attenuation, image noise and signal-to-noise ratio (SNR) were compared between the groups using Wilcoxon–Mann–Whitney U-test. Subjective diagnostic image quality was compared by using a five-point scale (1 = non-diagnostic, 5 = excellent, read by two readers in consensus) and Cohen's weighted kappa analysis for interobserver agreement. Results: Radiation dose was significantly lower with 70 kV acquisition than 100 and 120 kV (DLP: 31 versus 52 versus 82 mGy·cm; CTDI 2.33 versus 3.95 versus 6.31 mGy, all p < 0.05). Mean SNR (70 kV: 0.37; 100 kV: 0.21; 120 kV: 0.13; p < 0.05) and organ attenuation increased significantly with lower voltages. All examinations showed diagnostic image quality. Subjective diagnostic image quality was higher with standard protocols than the 70 kV protocol (120 kV: 5.0; 100 kV: 4.5; 70 kV: 3.5, p < 0.05) without significant differences with substantial interobserver agreement (κ > 0.59). Conclusion: The ultra-low dose (70 kV) CT imaging of the paranasal sinus allowed for significant dose reduction by 61% and an increased attenuation of organ structures in comparison to standard acquisition while maintaining diagnostic image quality with a slight reduction in subjective image quality. -- Highlights: •Image quality and radiation dose of 70 kV ultra-low dose CT of the paranasal sinus. •70 kV ultra-low dose CT of the paranasal sinus allows for dose reduction by 61%. •70 kV CT of the

  17. Design of an ultra-low-power digital processor for passive UHF RFID tags

    International Nuclear Information System (INIS)

    Shi Wanggen; Zhuang Yiqi; Li Xiaoming; Wang Xianghua; Jin Zhao; Wang Dan

    2009-01-01

    A new architecture of digital processors for passive UHF radio-frequency identification tags is proposed. This architecture is based on ISO/IEC 18000-6C and targeted at ultra-low power consumption. By applying methods like system-level power management, global clock gating and low voltage implementation, the total power of the design is reduced to a few microwatts. In addition, an innovative way for the design of a true RNG is presented, which contributes to both low power and secure data transaction. The digital processor is verified by an integrated FPGA platform and implemented by the Synopsys design kit for ASIC flows. The design fits different CMOS technologies and has been taped out using the 2P4M 0.35 μm process of Chartered Semiconductor.

  18. Development of Ultra-Low Power Metal Oxide Sensors and Arrays for Embedded Applications

    Science.gov (United States)

    Lutz, Brent; Wind, Rikard; Kostelecky, Clayton; Routkevitch, Dmitri; Deininger, Debra

    2011-09-01

    Metal oxide semiconductor sensors are widely used as individual sensors and in arrays, and a variety of designs for low power microhotplates have been demonstrated.1 Synkera Technologies has developed an embeddable chemical microsensor platform, based on a unique ceramic MEMS technology, for practical implementation in cell phones and other mobile electronic devices. Key features of this microsensor platform are (1) small size, (2) ultra-low power consumption, (3) high chemical sensitivity, (4) accurate response to a wide-range of threats, and (5) low cost. The sensor platform is enabled by a combination of advances in ceramic micromachining, and precision deposition of sensing films inside the high aspect ratio pores of anodic aluminum oxide (AAO).

  19. Ultra low-K shrinkage behavior when under electron beam in a scanning electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Lorut, F.; Imbert, G. [ST Microelectronics, 850 rue Jean Monnet, 38926 Crolles Cedex (France); Roggero, A. [Centre National d' Etudes Spatiales, 18 Avenue Edouard Belin, 31400 Toulouse (France)

    2013-08-28

    In this paper, we investigate the tendency of porous low-K dielectrics (also named Ultra Low-K, ULK) behavior to shrink when exposed to the electron beam of a scanning electron microscope. Various experimental electron beam conditions have been used for irradiating ULK thin films, and the resulting shrinkage has been measured through use of an atomic force microscope tool. We report the shrinkage to be a fast, cumulative, and dose dependent effect. Correlation of the shrinkage with incident electron beam energy loss has also been evidenced. The chemical modification of the ULK films within the interaction volume has been demonstrated, with a densification of the layer and a loss of carbon and hydrogen elements being observed.

  20. Effect of ultra-low dose whole-body-irradiation on severe patients with myasthenia gravis

    International Nuclear Information System (INIS)

    Arimori, Shigeru; Koriyama, Kenji

    1982-01-01

    An ultra-low dose whole body irradiation therapy was given to 5 patients with intractable bulbar syndrome, in a dose of 10 rad/fraction, 2 times a week for 5 weeks, with a total of 100 rad; and effects of this therapy on their clinical symptoms and immunological ability were discussed. In 3 of them, bulbar syndrome was improved, and the other one, the first irradiation was effective. The peripheral leukocyte count and lymphocyte count became lowest immediately after completion of the irradiation, and returned to the normal level within 1 to 2 months. The function of T-cells, especially suppressive T-cells, was recovered; and decrease in B-cells, resulted in a decrease in the AChR antibody titer. (Ueda, J.)

  1. Effect of ultra-low dose whole-body-irradiation on patients with severe myasthenia gravis

    Energy Technology Data Exchange (ETDEWEB)

    Arimori, Shigeru; Koriyama, Kenji (Tokai Univ., Isehara, Kanagawa (Japan). School of Medicine)

    1982-12-01

    An ultra-low dose whole body irradiation therapy was given to 5 patients with intractable bulbar syndrome, in a dose of 10 rad/fraction, 2 times a week for 5 weeks, with a total of 100 rad; and effects of this therapy on their clinical symptoms and immunological ability were discussed. In 3 of them, bulbar syndrome was improved, and the other one, the first irradiation was effective. The peripheral leukocyte count and lymphocyte count became lowest immediately after completion of the irradiation, and returned to the normal level within 1 to 2 months. The function of T-cells, especially suppressive T-cells, was recovered; and decrease in B-cells, resulted in a decrease in the AChR antibody titer.

  2. Nonlinear propagation of ultra-low-frequency electronic modes in a magnetized dusty plasma

    International Nuclear Information System (INIS)

    Mamun, A.A.

    1999-07-01

    A theoretical investigation has been made of nonlinear propagation of ultra-low-frequency electromagnetic waves in a magnetized two fluid (negatively charged dust and positively charged ion fluids) dusty plasma. These are modified Alfven waves for small value of θ and are modified magnetosonic waves for large θ, where θ is the angle between the directions of the external magnetic field and the wave propagation. A nonlinear evolution equation for the wave magnetic field, which is known as Korteweg de Vries (K-dV) equation and which admits a stationary solitary wave solution, is derived by the reductive perturbation method. The effects of external magnetic field and dust characteristics on the amplitude and the width of these solitary structures are examined. The implications of these results to some space and astrophysical plasma systems, especially to planetary ring-systems, are briefly mentioned. (author)

  3. GRABGAM: A Gamma Analysis Code for Ultra-Low-Level HPGe SPECTRA

    Energy Technology Data Exchange (ETDEWEB)

    Winn, W.G.

    1999-07-28

    The GRABGAM code has been developed for analysis of ultra-low-level HPGe gamma spectra. The code employs three different size filters for the peak search, where the largest filter provides best sensitivity for identifying low-level peaks and the smallest filter has the best resolution for distinguishing peaks within a multiplet. GRABGAM basically generates an integral probability F-function for each singlet or multiplet peak analysis, bypassing the usual peak fitting analysis for a differential f-function probability model. Because F is defined by the peak data, statistical limitations for peak fitting are avoided; however, the F-function does provide generic values for peak centroid, full width at half maximum, and tail that are consistent with a Gaussian formalism. GRABGAM has successfully analyzed over 10,000 customer samples, and it interfaces with a variety of supplementary codes for deriving detector efficiencies, backgrounds, and quality checks.

  4. Development of a dedicated ethanol ultra-low-emissions vehicle (ULEV): Phase 3 report

    Energy Technology Data Exchange (ETDEWEB)

    Dodge, L; Callahan, T; Leone, D; Naegeli, D; Shouse, K; Smith, L; Whitney, K [Southwest Research Inst., San Antonio, TX (United States)

    1998-04-01

    The objective of the 3.5 year project discussed in this report was to develop a commercially competitive vehicle powered by ethanol (or an ethanol blend) that can meet California`s Ultra Low Emissions Vehicle (ULEV) standards and equivalent Corporate Average Fuel Economy (CAFE) energy efficiency for a light duty passenger car application. This particular report summarizes the third phase of the project, which lasted 12 months. Emissions tests were conducted with advanced after-treatment devices on one of the two, almost identical, test vehicles, a 1993 Ford Taurus flexible fuel vehicle. The report also covers tests on the engine removed from the second Taurus vehicle. This engine was modified for an increased compression ratio, fitted with air assist injectors, and included an advanced engine control system with model-based control.

  5. Achieving low return temperature for domestic hot water preparation by ultra-low-temperature district heating

    DEFF Research Database (Denmark)

    Yang, Xiaochen; Svendsen, Svend

    2017-01-01

    District heating (DH) is a cost-effective method of heat supply, especially to area with high heat density. Ultra-low-temperature district heating (ULTDH) is defined with supply temperature at 35-45 degrees C. It aims at making utmost use of the available low-temperature energy sources. In order...... to achieve high efficiency of the ULTDH system, the return temperature should be as low as possible. For the energy-efficient buildings in the future, it is feasible to use ULTDH to cover the space heating demand. However, considering the comfort and hygiene requirements of domestic hot water (DHW...... lower return temperature and higher efficiency for DHW supply, an innovative substation was devised, which replaced the bypass with an instantaneous heat exchanger and a micro electric storage tank. The energy performance of the proposed substation and the resulting benefits for the DH system...

  6. Ultra Low-Power Acoustic Detector Applicable in Ambient Assistance Living Systems

    Directory of Open Access Journals (Sweden)

    Iliev I.

    2009-12-01

    Full Text Available Ambient Assisted Living (AAL includes methods, concepts, systems, devices as well as services, which provide unobtrusive support for daily life based on the context and situation of the assisted person. The technologies applied for AAL are user-centric, i.e. oriented towards the needs and capabilities of the particular user. They are also integrated into the immediate personal environment of the user. As a consequence, the technology is adapting to the user rather than the other way around. The in-house monitoring of elderly or disabled people (hard of hearing, deaf, with limited movement ability, using intelligent sensors is a very desirable service that may potentially increase the user's autonomy and independence while minimizing the risks of living alone. The described ultra low-power acoustic detector allows upgrade of the presented warning systems. It features long-term autonomy and possibility to use it as an element of the wireless personal area network (WPAN.

  7. Simultaneous measurement of tritium and radiocarbon by ultra-low-background proportional counting

    Energy Technology Data Exchange (ETDEWEB)

    Mace, Emily; Aalseth, Craig; Alexander, Tom; Back, Henning; Day, Anthony; Hoppe, Eric; Keillor, Martin; Moran, Jim; Overman, Cory; Panisko, Mark; Seifert, Allen

    2017-08-01

    Use of ultra-low-background capabilities at Pacific Northwest National Laboratory provide enhanced sensitivity for measurement of low-activity sources of tritium and radiocarbon using proportional counters. Tritium levels are nearly back to pre-nuclear test backgrounds (~2-8 TU in rainwater), which can complicate their dual measurement with radiocarbon due to overlap in the isotope’s respective energy spectra. This activity makes direct dual-isotope measurements challenging without additional chemistry to concentrate the tritium in a sample. We present results of single-isotope proportional counter measurements used to analyze a dual-isotope methane sample synthesized from ~120 mg of H2O and present sensitivity results.

  8. Localization of Ultra-Low Frequency Waves in Multi-Ion Plasmas of the Planetary Magnetosphere

    Directory of Open Access Journals (Sweden)

    Eun-Hwa Kim

    2015-12-01

    Full Text Available By adopting a 2D time-dependent wave code, we investigate how mode-converted waves at the Ion-Ion Hybrid (IIH resonance and compressional waves propagate in 2D density structures with a wide range of field-aligned wavenumbers to background magnetic fields. The simulation results show that the mode-converted waves have continuous bands across the field line consistent with previous numerical studies. These waves also have harmonic structures in frequency domain and are localized in the field-aligned heavy ion density well. Our results thus emphasize the importance of a field-aligned heavy ion density structure for ultra-low frequency wave propagation, and suggest that IIH waves can be localized in different locations along the field line.

  9. Ultra-low damping in lift-off structured yttrium iron garnet thin films

    Science.gov (United States)

    Krysztofik, A.; Coy, L. E.; Kuświk, P.; Załeski, K.; Głowiński, H.; Dubowik, J.

    2017-11-01

    We show that using maskless photolithography and the lift-off technique, patterned yttrium iron garnet thin films possessing ultra-low Gilbert damping can be accomplished. The films of 70 nm thickness were grown on (001)-oriented gadolinium gallium garnet by means of pulsed laser deposition, and they exhibit high crystalline quality, low surface roughness, and the effective magnetization of 127 emu/cm3. The Gilbert damping parameter is as low as 5 ×10-4. The obtained structures have well-defined sharp edges which along with good structural and magnetic film properties pave a path in the fabrication of high-quality magnonic circuits and oxide-based spintronic devices.

  10. Ultra Low Level Tritium Analysis Method Using a Liquid Scintillation Counter

    Energy Technology Data Exchange (ETDEWEB)

    Noh, S. J.; Kim, H. J.; Kim, H.; Lim, H. J.; Lee, M. W.; Jeong, D. H.; Kim, J. K.; Kang, Y. R. [Dongnam Institute of Radiological and Medical Sciences, Busan (Korea, Republic of); Nam, S. H. [Inje University, Gimhae, (Korea, Republic of)

    2015-05-15

    To evaluate {sup 3}H concentration in the atmosphere more accurately compared to the conventional methods, the author of this paper intended to suggest more improved analytical methods and derived the elements which might occur during analysis or required improvements. The method suggested in this study is able to reduce the uncertainty and errors which may be existent in evaluating the {sup 3}H concentration of environmental sample s and thus will serve as the best solution in the technical and economic point of view. Liquid Scintillation Counter is the most widely used to analyze ultra-low level {sup 3}H by using CPM / DPM Counting Mode using external radiation source and Spectrum Plot Mode using internal radiation source. In CPM / DPM Counting Mode, multiple samples can be measured by single calibration despite its rather higher background whereas Spectrum Plot Mode requires more time and cost to analyze multiple samples despite its reliability to reduce the contribution of other radionuclides.

  11. Ultra-low energy Ar+ beam applied for SIMS depth profile analysis of layered nanostructures

    International Nuclear Information System (INIS)

    Konarski, P.; Mierzejewska, A.; Iwanejko, I.

    2001-01-01

    Secondary ion mass spectrometry (SIMS) depth profile analyses of flat layered nanostructures: 10 nm Ta 2 O 3 /Ta and 20 nm (10 x B 4 C/Mo)/Si as well as microparticles of core (illite) - shell (rutile) structure, performed with the use of ultra-low energy ion beam (180-880 eV, Ar + ), are presented. The profiles were obtained using 'mesa' scanning technique and also sample rotation. Depth profile resolution below 1 nanometer was obtained for flat nanostructures. Presented experimental results are compared with Monte Carlo sputtering simulations of analysed structures. A method of finding beam energy, optimal for the best resolution SIMS depth profile analysis, is suggested. (author)

  12. Ultra Low Density Shape Memory Polymer Foams With Tunable Physicochemical Properties for Treatment of intracranial Aneurysms

    Energy Technology Data Exchange (ETDEWEB)

    Singhal, Pooja [Texas A & M Univ., College Station, TX (United States)

    2013-12-01

    Shape memory polymers (SMPs) are a rapidly emerging class of smart materials that can be stored in a deformed temporary shape, and can actively return to their original shape upon application of an external stimulus such as heat, pH or light. This behavior is particularly advantageous for minimally invasive biomedical applications comprising embolic/regenerative scaffolds, as it enables a transcatheter delivery of the device to the target site. The focus of this work was to exploit this shape memory behavior of polyurethanes, and develop an efficient embolic SMP foam device for the treatment of intracranial aneurysms.In summary, this work reports a novel family of ultra low density polymer foams which can be delivered via a minimally invasive surgery to the aneurysm site, actuated in a controlled manner to efficiently embolize the aneurysm while promoting physiological fluid/blood flow through the reticulated/open porous structure, and eventually biodegrade leading to complete healing of the vasculature.

  13. Many-body spin related phenomena in ultra-low-disorder quantum wires

    International Nuclear Information System (INIS)

    Reilly, D.J.; Facer, G.R.; Dzurak, A.S.; Kane, B.E.; Clark, R.G.; Stiles, P.J.; O'Brien, J.L.; Lumpkin, N.E.

    2000-01-01

    Full text: Zero length quantum wires (or point contacts) exhibit unexplained conductance structure close to 0.7 x 2e 2 /h in the absence of an applied magnetic field. We have studied the density- and temperature-dependent conductance of ultra-low-disorder GaAs AlGaAs quantum wires with nominal lengths l=0 and 2μm, fabricated from structures free of the disorder associated with modulation doping. In a direct comparison we observe structure near 0.7 x 2e 2 /h for l=0 whereas the l = 2μm wires show structure evolving with increasing density to 0.5 x 2e 2 /h in zero magnetic field, the value expected for an ideal spin split sub-band. Our results suggest the dominant mechanism through which electrons interact can be strongly affected by the length of the 1D region

  14. Ultra-low Pt decorated PdFe Alloy Nanoparticles for Formic Acid Electro-oxidation

    International Nuclear Information System (INIS)

    Zhou, Yawei; Du, Chunyu; Han, Guokang; Gao, Yunzhi; Yin, Geping

    2016-01-01

    Highlights: • A cost-efficient way is used to prepare transition-noble metal alloy nanoparticles. • The Pd 50 Fe 50 /C catalyst shows excellent activity for formic acid oxidation (FAO). • Much activity enhancement of FAO is acquired by ultra-low Pt decorated Pd 50 Fe 50 . • A synergistic mechanism between Pt clusters and PdFe is proposed during the FAO. - Abstract: Palladium (Pd), has demonstrated promising electro-catalytic activity for formic acid oxidation, but suffers from extremely low abundance. Recently alloying with a transition metal has been considered as an effective approach to reducing the loading of Pd and enhancing the activity of Pd-based catalysts simultaneously. Herein, carbon supported PdFe nanoparticles (NPs) are synthesized at room temperature by using sodium borohydride as reducing agent and potassium ferrocyanide as Fe precursor. The Pd 50 Fe 50 alloy sample annealed at 900 °C for 1 h shows the best catalytic activity among Pd x Fe 1-x (x = 0.2, 0.4, 0.5, 0.6, and 0.8) towards formic acid oxidation. To further improve both catalytic activity and stability, the ultra-low Pt (0.09 wt %) decorated Pd 50 Fe 50 NPs (PtPd/PdFe) are prepared via the galvanic replacement reaction. Compared with Pd 50 Fe 50 /C, the PtPd/PdFe/C Exhibits 1.52 times higher catalytic activity and lower onset potential (−0.12 V). The significant enhancements of formic acid oxidation can be attributed to the accelerated dehydrogenation reaction of formic acid by Pt atomic clusters. Moreover, the PtPd/PdFe/C also demonstrates better tolerance to poisons during formic acid oxidation.

  15. Evaluations of different domestic hot water preparing methods with ultra-low-temperature district heating

    International Nuclear Information System (INIS)

    Yang, Xiaochen; Li, Hongwei; Svendsen, Svend

    2016-01-01

    This study investigated the performances of five different substation configurations in single-family houses supplied with ULTDH (ultra-low-temperature district heating). The temperature at the heat plant is 46 °C and around 40 °C at the substations. To avoid the proliferation of Legionella in the DHW (domestic hot water) and assure the comfortable temperature, all substations were installed with supplementary heating devices. Detailed measurements were taken in the substations, including the electricity demand of the supplementary heating devices. To compare the energy and economic performance of the substations, separate models were built based on standard assumptions. The relative heat and electricity delivered for preparing DHW were calculated. The results showed that substations with storage tanks and heat pumps have high relative electricity demand, which leads to higher integrated costs considering both heat and electricity for DHW preparation. The substations with in-line electric heaters have low relative electricity usage because very little heat is lost due to the instantaneous DHW preparation. Accordingly, the substations with in-line electric heaters would have the lowest energy cost for DHW preparation. To achieve optimal design and operation for the ULTDH substation, the electricity peak loads of the in-line electric heaters were analysed according to different DHW-heating strategies. - Highlights: • Five different substations supplied with ultra-low-temperature district heating were measured. • The relative heat and electricity delivered for DHW preparation were modelled for different substations. • The levelized cost of the five substations in respect of DHW preparation was calculated. • The feasibility of applying instantaneous electric heater with normal power supply was tested.

  16. An ultra-low-power RF transceiver for WBANs in medical applications

    International Nuclear Information System (INIS)

    Zhang Qi; Wu Nanjian; Kuang Xiaofei

    2011-01-01

    A 2.4 GHz ultra-low-power RF transceiver with a 900 MHz auxiliary wake-up link for wireless body area networks (WBANs) in medical applications is presented. The RF transceiver with an asymmetric architecture is proposed to achieve high energy efficiency according to the asymmetric communication in WBANs. The transceiver consists of a main receiver (RX) with an ultra-low-power free-running ring oscillator and a high speed main transmitter (TX) with fast lock-in PLL. A passive wake-up receiver (WuRx) for wake-up function with a high power conversion efficiency (PCE) CMOS rectifier is designed to offer the sensor node the capability of work-on-demand with zero standby power. The chip is implemented in a 0.18 μm CMOS process. Its core area is 1.6 mm 2 . The main RX achieves a sensitivity of -55 dBm at a 100 kbps OOK data rate while consuming just 210 μA current from the 1 V power supply. The main TX achieves +3 dBm output power with a 4 Mbps/500 kbps/200 kbps data rate for OOK/4 FSK/2 FSK modulation and dissipates 3.25 mA/6.5 mA/6.5 mA current from a 1.8 V power supply. The minimum detectable RF input energy for the wake-up RX is -15 dBm and the PCE is more than 25%. (semiconductor integrated circuits)

  17. An ultra-low-power RF transceiver for WBANs in medical applications

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Qi; Wu Nanjian [State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China); Kuang Xiaofei, E-mail: nanjian@semi.ac.cn [College of Electronic Information, Hangzhou Dianzi University, Hangzhou 310018 (China)

    2011-06-15

    A 2.4 GHz ultra-low-power RF transceiver with a 900 MHz auxiliary wake-up link for wireless body area networks (WBANs) in medical applications is presented. The RF transceiver with an asymmetric architecture is proposed to achieve high energy efficiency according to the asymmetric communication in WBANs. The transceiver consists of a main receiver (RX) with an ultra-low-power free-running ring oscillator and a high speed main transmitter (TX) with fast lock-in PLL. A passive wake-up receiver (WuRx) for wake-up function with a high power conversion efficiency (PCE) CMOS rectifier is designed to offer the sensor node the capability of work-on-demand with zero standby power. The chip is implemented in a 0.18 {mu}m CMOS process. Its core area is 1.6 mm{sup 2}. The main RX achieves a sensitivity of -55 dBm at a 100 kbps OOK data rate while consuming just 210 {mu}A current from the 1 V power supply. The main TX achieves +3 dBm output power with a 4 Mbps/500 kbps/200 kbps data rate for OOK/4 FSK/2 FSK modulation and dissipates 3.25 mA/6.5 mA/6.5 mA current from a 1.8 V power supply. The minimum detectable RF input energy for the wake-up RX is -15 dBm and the PCE is more than 25%. (semiconductor integrated circuits)

  18. Ultra-low fertility in South Korea: The role of the tempo effect

    Directory of Open Access Journals (Sweden)

    Sam Hyun Yoo

    2018-02-01

    Full Text Available Background: The total fertility rate (TFR in South Korea has fallen below 1.3 since 2001. The role of the rapid shift toward a late-childbearing pattern in driving Korean fertility decline to this ultra-low level has been little explored until now. Objective: We provide an in-depth analysis of period fertility trends by birth order in South Korea from 1981 to 2015, when the period TFR fell from 2.57 to extremely low levels. Methods: We combine census and birth registration data to estimate period and cohort fertility indicators by birth order. We compare changes in conventional TFR with tempo- and parity-adjusted total fertility rate (TFRp* and their birth-order-specific components. Results: The tempo effect linked to the shift toward delayed childbearing has had a strong and persistent negative influence on period TFRs in South Korea since the early 1980s. Without the shift to later childbearing, period fertility rates in South Korea would consistently stay higher and decline more gradually, reaching a threshold of very low fertility, 1.5, only in 2014. The postponement of childbearing and the resulting tempo effect were strongest in the early 2000s, when Korean TFR reached the lowest levels. More recently, Korean fertility has been characterized by a diminishing tempo effect and falling first and second birth rates. This trend marks a break with the previous pattern of almost universal fertility and a strong two-child family model. Contribution: Our study demonstrates the importance of the tempo effect in explaining the shift to ultra-low fertility in South Korea and in East Asia

  19. Combustion Dynamics and Control for Ultra Low Emissions in Aircraft Gas-Turbine Engines

    Science.gov (United States)

    DeLaat, John C.

    2011-01-01

    Future aircraft engines must provide ultra-low emissions and high efficiency at low cost while maintaining the reliability and operability of present day engines. The demands for increased performance and decreased emissions have resulted in advanced combustor designs that are critically dependent on efficient fuel/air mixing and lean operation. However, all combustors, but most notably lean-burning low-emissions combustors, are susceptible to combustion instabilities. These instabilities are typically caused by the interaction of the fluctuating heat release of the combustion process with naturally occurring acoustic resonances. These interactions can produce large pressure oscillations within the combustor and can reduce component life and potentially lead to premature mechanical failures. Active Combustion Control which consists of feedback-based control of the fuel-air mixing process can provide an approach to achieving acceptable combustor dynamic behavior while minimizing emissions, and thus can provide flexibility during the combustor design process. The NASA Glenn Active Combustion Control Technology activity aims to demonstrate active control in a realistic environment relevant to aircraft engines by providing experiments tied to aircraft gas turbine combustors. The intent is to allow the technology maturity of active combustion control to advance to eventual demonstration in an engine environment. Work at NASA Glenn has shown that active combustion control, utilizing advanced algorithms working through high frequency fuel actuation, can effectively suppress instabilities in a combustor which emulates the instabilities found in an aircraft gas turbine engine. Current efforts are aimed at extending these active control technologies to advanced ultra-low-emissions combustors such as those employing multi-point lean direct injection.

  20. Usefulness of intraoperative ultra low-field magnetic resonance imaging in glioma surgery.

    Science.gov (United States)

    Senft, Christian; Seifert, Volker; Hermann, Elvis; Franz, Kea; Gasser, Thomas

    2008-10-01

    The aim of this study was to demonstrate the usefulness of a mobile, intraoperative 0.15-T magnetic resonance imaging (MRI) scanner in glioma surgery. We analyzed our prospectively collected database of patients with glial tumors who underwent tumor resection with the use of an intraoperative ultra low-field MRI scanner (PoleStar N-20; Odin Medical Technologies, Yokneam, Israel/Medtronic, Louisville, CO). Sixty-three patients with World Health Organization Grade II to IV tumors were included in the study. All patients were subjected to postoperative 1.5-T imaging to confirm the extent of resection. Intraoperative image quality was sufficient for navigation and resection control in both high- and low-grade tumors. Primarily enhancing tumors were best detected on T1-weighted imaging, whereas fluid-attenuated inversion recovery sequences proved best for nonenhancing tumors. Intraoperative resection control led to further tumor resection in 12 (28.6%) of 42 patients with contrast-enhancing tumors and in 10 (47.6%) of 21 patients with noncontrast-enhancing tumors. In contrast-enhancing tumors, further resection led to an increased rate of complete tumor resection (71.2 versus 52.4%), and the surgical goal of gross total removal or subtotal resection was achieved in all cases (100.0%). In patients with noncontrast-enhancing tumors, the surgical goal was achieved in 19 (90.5%) of 21 cases, as intraoperative MRI findings were inconsistent with postoperative high-field imaging in 2 cases. The use of the PoleStar N-20 intraoperative ultra low-field MRI scanner helps to evaluate the extent of resection in glioma surgery. Further tumor resection after intraoperative scanning leads to an increased rate of complete tumor resection, especially in patients with contrast-enhancing tumors. However, in noncontrast- enhancing tumors, the intraoperative visualization of a complete resection seems less specific, when compared with postoperative 1.5-T MRI.

  1. An ultra low-power off-line APDM-based switchmode power supply with very high conversion efficiency

    DEFF Research Database (Denmark)

    Nielsen, Nils

    2001-01-01

    This article describes the results from the research work on design of a ultra low power off-line power supply with very high conversion efficiency. The input voltage is 230 VAC nominal and output voltage is 5 VDC. By ultra low power levels, an output power level in the area ranging from 50 m......W and up to 1000 mW is meant. The small power supply is intended for use as a standby power supply in mains operated equipment, which requires a small amount of power in standby mode....

  2. Application of Integrated Reservoir Management and Reservoir Characterization to Optimize Infill Drilling

    Energy Technology Data Exchange (ETDEWEB)

    P. K. Pande

    1998-10-29

    Initial drilling of wells on a uniform spacing, without regard to reservoir performance and characterization, must become a process of the past. Such efforts do not optimize reservoir development as they fail to account for the complex nature of reservoir heterogeneities present in many low permeability reservoirs, and carbonate reservoirs in particular. These reservoirs are typically characterized by: o Large, discontinuous pay intervals o Vertical and lateral changes in reservoir properties o Low reservoir energy o High residual oil saturation o Low recovery efficiency

  3. Field evaluation of indoor thermal fog and ultra-low volume applications for control of Aedes aegypti, in Thailand

    Science.gov (United States)

    Efficacies of a hand-held thermal fogger (PatriotTM) and hand-held Ultra-low volume (ULV) sprayer (TwisterTM) with combinations of two different adulticides and an insect growth regulator (pyriproxyfen) were field assessed and compared for their impact on reducing dengue vector populations in Thaila...

  4. A NEW ANIMAL-MODEL FOR HUMAN PREECLAMPSIA - ULTRA-LOW-DOSE ENDOTOXIN INFUSION IN PREGNANT RATS

    NARCIS (Netherlands)

    FAAS, MM; SCHUILING, GA; BALLER, JFW; VISSCHER, CA; BAKKER, WW

    OBJECTIVE: An animal model for preeclampsia was developed by means of an ultra-low-dose endotoxin infusion protocol in conscious pregnant rats. STUDY DESIGN: Rats received a permanent jugular vein cannula on day 0 of pregnancy, through which endotoxin (1.0 mu/kg body weight) (n = 10) or saline

  5. Virtual Colonoscopy Screening With Ultra Low-Dose CT and Less-Stressful Bowel Preparation: A Computer Simulation Study

    Science.gov (United States)

    Wang, Jing; Wang, Su; Li, Lihong; Fan, Yi; Lu, Hongbing; Liang, Zhengrong

    2008-10-01

    Computed tomography colonography (CTC) or CT-based virtual colonoscopy (VC) is an emerging tool for detection of colonic polyps. Compared to the conventional fiber-optic colonoscopy, VC has demonstrated the potential to become a mass screening modality in terms of safety, cost, and patient compliance. However, current CTC delivers excessive X-ray radiation to the patient during data acquisition. The radiation is a major concern for screening application of CTC. In this work, we performed a simulation study to demonstrate a possible ultra low-dose CT technique for VC. The ultra low-dose abdominal CT images were simulated by adding noise to the sinograms of the patient CTC images acquired with normal dose scans at 100 mA s levels. The simulated noisy sinogram or projection data were first processed by a Karhunen-Loeve domain penalized weighted least-squares (KL-PWLS) restoration method and then reconstructed by a filtered backprojection algorithm for the ultra low-dose CT images. The patient-specific virtual colon lumen was constructed and navigated by a VC system after electronic colon cleansing of the orally-tagged residue stool and fluid. By the KL-PWLS noise reduction, the colon lumen can successfully be constructed and the colonic polyp can be detected in an ultra low-dose level below 50 mA s. Polyp detection can be found more easily by the KL-PWLS noise reduction compared to the results using the conventional noise filters, such as Hanning filter. These promising results indicate the feasibility of an ultra low-dose CTC pipeline for colon screening with less-stressful bowel preparation by fecal tagging with oral contrast.

  6. Intraarterial CT Angiography Using Ultra Low Volume of Iodine Contrast – Own Experiences

    International Nuclear Information System (INIS)

    Garcarek, Jerzy; Kurcz, Jacek; Guziński, Maciej; Banasik, Mirosław; Miś, Marcin; Gołębiowski, Tomasz

    2015-01-01

    High volume of intravenous contrast in CT-angiography may result in contrast-induced nephropathy. Intraarterial ultra-low volume of contrast medium results in its satisfactory blood concentration with potentially good image quality. The first main purpose was to assess the influence of the method on function of transplanted kidney in patients with impaired graft function. The second main purpose of the study was to evaluate the usefulness of this method for detection of gastrointestinal and head-and-neck haemorrhages. Between 2010 and 2013 intraarterial CT-angiography was performed in 56 patients, including 28 with chronic kidney disease (CKD). There were three main subgroups: 18 patients after kidney transplantation, 10 patients with gastrointestinal hemorrhage, 8 patients with head-and-neck hemorrhage. Contralateral or ipsilateral inguinal arterial approach was performed. The 4-French vascular sheaths and 4F-catheters were introduced under fluoroscopy. Intraarterial CT was performed using 64-slice scanner. The scanning protocol was as follows: slice thickness 0.625 mm, pitch 1.3, gantry rotation 0.6 sec., scanning delay 1–2 sec. The extent of the study was established on the basis of scout image. In patients with CKD 6–8 mL of Iodixanol (320 mg/mL) diluted with saline to 18–24 mL was administered at a speed of 4–5 mL/s. Vasculature was properly visualized in all patients. In patients with impaired renal function creatinine/eGFR levels remained stable in all but one case. Traditional arteriography failed and CT-angiography demonstrated the site of bleeding in 3 of 10 patients with symptoms of gastrointestinal bleeding (30%). In 8 patients with head-and-neck bleeding CT-angiography did not prove beneficial when compared to traditional arteriography. 1. Ultra-low contrast intraarterial CT-angiography does not deteriorate the function of transplanted kidneys in patients with impaired graft function. 2. 3D reconstructions allow for excellent visualization of

  7. DEVELOPMENT AND DEMONSTRATION OF AN ULTRA LOW NOx COMBUSTOR FOR GAS TURBINES

    Energy Technology Data Exchange (ETDEWEB)

    NEIL K. MCDOUGALD

    2005-04-30

    Alzeta Corporation has developed surface-stabilized fuel injectors for use with lean premixed combustors which provide extended turndown and ultra-low NOX emission performance. These injectors use a patented technique to form interacting radiant and blue-flame zones immediately above a selectively-perforated porous metal surface. This allows stable operation at low reaction temperatures. This technology is being commercialized under the product name nanoSTAR. Initial tests demonstrated low NOX emissions but, were limited by flashback failure of the injectors. The weld seams required to form cylindrical injectors from flat sheet material were identified as the cause of the failures. The approach for this project was to first develop new fabrication methods to produce injectors without weld seams, verify similar emissions performance to the original flat sheet material and then develop products for microturbines and small gas turbines along parallel development paths. A 37 month project was completed to develop and test a surface stabilized combustion system for gas turbine applications. New fabrication techniques developed removed a technological barrier to the success of the product by elimination of conductive weld seams from the injector surface. The injectors demonstrated ultra low emissions in rig tests conducted under gas turbine operating conditions. The ability for injectors to share a common combustion chamber allowing for deployment in annular combustion liner was also demonstrated. Some further development is required to resolve integration issues related to specific engine constraints, but the nanoSTAR technology has clearly demonstrated its low emissions potential. The overall project conclusions can be summarized: (1) A wet-laid casting method successfully eliminated weld seams from the injector surface without degrading performance. (2) Gas turbine cycle analysis identified several injector designs and control schemes to start and load engines using

  8. Ultra-Low-Noise Sub-mm/Far-IR Detectors for Space-Based Telescopes

    Science.gov (United States)

    Rostem, Karwan

    The sub-mm and Far-IR spectrum is rich with information from a wide range of astrophysical sources, including exoplanet atmospheres and galaxies at the peak star formation. In the 10-400 μm range, the spectral lines of important chemical species such H2O, HD, and [OI] can be used to map the formation and evolution of planetary systems. Dust emission in this spectral range is also an important tool for characterizing the morphology of debris disks and interstellar magnetic fields. At larger scales, accessing the formation and distribution of luminous Far-IR and sub-mm galaxies is essential to understanding star formation triggers, as well as the last stages of reionization at z 6. Detector technology is essential to realizing the full science potential of a next-generation Far-IR space telescope (Far-IR Surveyor). The technology gap in large-format, low-noise and ultra-low-noise Far-IR direct detectors is specifically highlighted by NASA's Cosmic Origins Program, and prioritized for development now to enable a flagship mission such as the Far-IR Surveyor that will address the key Cosmic Origins science questions of the next two decades. The detector requirements for a mid-resolution spectrometer are as follows: (1) Highly sensitive detectors with performance approaching 10^-19 - 10^-20 WHz 1/2 for background- limited operation in telescopes with cold optics. (2) Detector time constant in the sub- millisecond range. (3) Scalable architecture to a kilo pixel array with uniform detector characteristics. (4) Compatibility with space operation in the presence of particle radiation. We propose phononic crystals to meet the requirements of ultra-low-noise thermal detectors. By design, a phononic crystal exhibits phonon bandgaps where heat transport is forbidden. The size and location of the bandgaps depend on the elastic properties of the dielectric and the geometry of the phononic unit cell. A wide-bandwidth low-pass thermal filter with a cut-off frequency of 1.5 GHz and

  9. Terrestrial gamma radiation baseline mapping using ultra low density sampling methods

    International Nuclear Information System (INIS)

    Kleinschmidt, R.; Watson, D.

    2016-01-01

    Baseline terrestrial gamma radiation maps are indispensable for providing basic reference information that may be used in assessing the impact of a radiation related incident, performing epidemiological studies, remediating land contaminated with radioactive materials, assessment of land use applications and resource prospectivity. For a large land mass, such as Queensland, Australia (over 1.7 million km 2 ), it is prohibitively expensive and practically difficult to undertake detailed in-situ radiometric surveys of this scale. It is proposed that an existing, ultra-low density sampling program already undertaken for the purpose of a nationwide soil survey project be utilised to develop a baseline terrestrial gamma radiation map. Geoelement data derived from the National Geochemistry Survey of Australia (NGSA) was used to construct a baseline terrestrial gamma air kerma rate map, delineated by major drainage catchments, for Queensland. Three drainage catchments (sampled at the catchment outlet) spanning low, medium and high radioelement concentrations were selected for validation of the methodology using radiometric techniques including in-situ measurements and soil sampling for high resolution gamma spectrometry, and comparative non-radiometric analysis. A Queensland mean terrestrial air kerma rate, as calculated from the NGSA outlet sediment uranium, thorium and potassium concentrations, of 49 ± 69 nGy h −1 (n = 311, 3σ 99% confidence level) is proposed as being suitable for use as a generic terrestrial air kerma rate background range. Validation results indicate that catchment outlet measurements are representative of the range of results obtained across the catchment and that the NGSA geoelement data is suitable for calculation and mapping of terrestrial air kerma rate. - Highlights: • A baseline terrestrial air kerma map of Queensland, Australia was developed using geochemical data from a major drainage catchment ultra-low density sampling program

  10. APPLICATION OF INTEGRATED RESERVOIR MANAGEMENT AND RESERVOIR CHARACTERIZATION

    Energy Technology Data Exchange (ETDEWEB)

    Jack Bergeron; Tom Blasingame; Louis Doublet; Mohan Kelkar; George Freeman; Jeff Callard; David Moore; David Davies; Richard Vessell; Brian Pregger; Bill Dixon; Bryce Bezant

    2000-03-01

    Reservoir performance and characterization are vital parameters during the development phase of a project. Infill drilling of wells on a uniform spacing, without regard to characterization does not optimize development because it fails to account for the complex nature of reservoir heterogeneities present in many low permeability reservoirs, especially carbonate reservoirs. These reservoirs are typically characterized by: (1) large, discontinuous pay intervals; (2) vertical and lateral changes in reservoir properties; (3) low reservoir energy; (4) high residual oil saturation; and (5) low recovery efficiency. The operational problems they encounter in these types of reservoirs include: (1) poor or inadequate completions and stimulations; (2) early water breakthrough; (3) poor reservoir sweep efficiency in contacting oil throughout the reservoir as well as in the nearby well regions; (4) channeling of injected fluids due to preferential fracturing caused by excessive injection rates; and (5) limited data availability and poor data quality. Infill drilling operations only need target areas of the reservoir which will be economically successful. If the most productive areas of a reservoir can be accurately identified by combining the results of geological, petrophysical, reservoir performance, and pressure transient analyses, then this ''integrated'' approach can be used to optimize reservoir performance during secondary and tertiary recovery operations without resorting to ''blanket'' infill drilling methods. New and emerging technologies such as geostatistical modeling, rock typing, and rigorous decline type curve analysis can be used to quantify reservoir quality and the degree of interwell communication. These results can then be used to develop a 3-D simulation model for prediction of infill locations. The application of reservoir surveillance techniques to identify additional reservoir ''pay'' zones

  11. 3D nonlinear MHD simulations of ultra-low q plasmas

    International Nuclear Information System (INIS)

    Bonfiglio, D.; Cappello, S.; Piovan, R.; Zanotto, L.; Zuin, M.

    2008-01-01

    Magnetohydrodynamic (MHD) phenomena occurring in the ultra-low safety factor (ULq) configuration are investigated by means of 3D nonlinear MHD simulations. The ULq configuration, a screw pinch characterized by the edge safety factor q edge in the interval 0 edge edge values which are about the major rational numbers, suggesting plasma self-organization. Similar behaviour is observed in experimental ULq discharges, like those recently obtained exploiting the flexibility of the RFX-mod device. The transition of q edge from a major rational number to the next one occurs together with the development of a kink deformation of the plasma column, whose stabilization yields a nearly axisymmetric state with a rather flat q profile. Numerical simulations also show that it is possible to sustain either of the two conditions, namely, the saturated kink helical configuration and the axisymmetric one, by forcing q edge at a suitable value. Finally, the effects of this MHD phenomenology on the confinement properties of ULq plasmas are discussed.

  12. Exploring Sub-Femtosecond Correlated Dynamics with an Ultra-low Energy Electrostatic Storage Ring

    International Nuclear Information System (INIS)

    Welsch, C.P.; Grieser, M.; Dorn, A.; Moshammer, R.; Ullrich, J.

    2005-01-01

    Whereas the three-body Coulomb problem for single excitation and ionization was claimed to be solved in a mathematically correct way during 1999 until 2004 for electron impact on hydrogen and helium, ion-impact ionization still represents a major challenge for theory. Troubling discrepancies have been observed recently in fully differential cross sections (FDCS) for helium single ionization by fast ion impact and even experimental total cross sections are in striking disagreement with the predictions of all state-of-the-art theories for low-energy antiproton collisions. Therefore, within the future Facility for Low-energy Antiproton and Ion Research (FLAIR), it has been proposed to combine state-of-the-art many-particle imaging methods with a novel electrostatic storage ring for slow antiprotons in order to realize single and multiple ionization cross section measurements for antiprotons colliding with atoms, molecules and clusters. Total, as well as any differential cross sections up to FDCS including ionization-excitation reactions are envisaged to become available, serving as benchmark data for theory. Here, the present status of experiments in comparison with theory is presented and the layout of an Ultra-low energy Storage Ring (USR) with its integrated reaction microscope at FLAIR is described

  13. Ultra-low velocity zone heterogeneities at the core-mantle boundary from diffracted PKKPab waves

    Science.gov (United States)

    Ma, Xiaolong; Sun, Xinlei

    2017-08-01

    Diffracted waves around Earth's core could provide important information of the lowermost mantle that other seismic waves may not. We examined PKKPab diffraction waves from 52 earthquakes occurring at the western Pacific region and recorded by USArray to probe the velocity structure along the core-mantle boundary (CMB). These diffracted waves emerge at distances up to 10° past the theoretical cutoff epicentral distance and show comparable amplitudes. We measured the ray parameters of PKKPab diffraction waves by Radon transform analysis that is suitable for large-aperture arrays. These ray parameters show a wide range of values from 4.250 to 4.840 s/deg, suggesting strong lateral heterogeneities in sampling regions at the base of the mantle. We further estimated the P-wave velocity variations by converting these ray parameters and found the CMB regions beneath the northwestern edge of African Anomaly (Ritsma et al. in Science 286:1925-1928, 1999) and southern Sumatra Islands exhibit velocity reductions up to 8.5% relative to PREM. We suggest that these low velocity regions are Ultra-low velocity zones, which may be related to partial melt or iron-enriched solids.[Figure not available: see fulltext.

  14. Global Ultra-Low-Frequency Geomagnetic Pulsations Associated with the March 24, 1991 Geomagnetic Storm

    Directory of Open Access Journals (Sweden)

    Nan-Wei Chen Jann-Yenq Liu

    2008-01-01

    Full Text Available On 24 March 1991, global ultra-low-frequency (ULF pulsations (1.1 - 3.3 mHz observed in the magnetosphere as well as on the ground were studied via analyzing magnetic field data obtained from a global network, comprising ground-based observatories and geosynchronous satellites. In the magnetosphere, the compressional and transverse components of the magnetic fields recorded at two satellites, GOES 6 and GOES 7, showed dominant fluctuations when they were in the vicinity of the noon sector, whereas the transverse fluctuations became dominant when they were at the dawn side. Similarly, on the ground, the H and D components had major fluctuations along with an increase in amplitude from low to high geomagnetic latitudes. In addition, the amplitude of the ULF pulsation was enhanced at the dawn and dusk sides. The geomagnetic pulsations propagated anti-sunward and were of counterclockwise and clockwise elliptical polarizations at the dawn and dusk sides respectively. The counterclockwise elliptical polarization reversed to a clockwise elliptical polarization at geomagnetic local noon and linear polarization was observed during the reversal. It appears that the analysis of the global network data not only provided us with a study of the characteristics of the waves in the magnetosphere and on the ground but also provided us with correlations between the geosynchronous and ground observations, which should be essential to the determination of possible mechanisms of this storm-related wave event.

  15. An ultra low noise AC beam transformer for deceleration and diagnostics of low intensity beams

    CERN Document Server

    González, C

    1999-01-01

    The design of a broad band ultra-low noise ferrite loaded AC beam transformer is presented. It is designed for use in the CERN Antiproton Decelerator (AD), where beams of a few 107 charges must be decelerated from 3.5 GeV/c to 100 MeV/c. It is used in the RF beam-phase loop, and for intensity and bunch shape measurements during deceleration. When the beam is debunched for cooling on magnetic flat tops, the pick-up is used for measurements of intensity and momentum distribution by means of longitudinal Schottky scans. When used as Schottky pick-up, the signal to noise ratio should be better by about 40 dB than the existing stripline based longitudinal Schottky pick-up. The integrated design of pick-up and associated low-noise amplifier is presented. The achieved noise performance of a few from 1 to 3 MHz is obtained by attaching a low-noise, high-impedance silicon JFET (junction field effect transistor) amplifier to a high-Q resonant ferrite loaded cavity, and then eliminating the resonant response by low-nois...

  16. Effect of PVDC on the Fire Performance of Ultra-Low Density Fiberboards (ULDFs

    Directory of Open Access Journals (Sweden)

    Zhenzeng Wu

    2016-08-01

    Full Text Available Poly vinylidene chloride-vinyl chloride emulsions (PVDC were added as a substitute for chlorinated paraffin (CP in the preparation of ultra-low density fiberboards (ULDFs. The micromorphology and fire performance of ULDFs were investigated using a scanning electron microscope, limiting oxygen index instrument, and cone calorimeter. The results showed that PVDC specimens were coated with a regularly smooth film, while the distribution of CP inside CP specimens was uneven. The limiting oxygen index increased with the dosage of PVDC, then reached a plateau at 50 mL and 28%, slightly higher than CP specimens (27.3%. The peak of heat release rate, mean heat release rate, mean CO, and total smoke release of PVDC specimens was reduced 43.3%, 13.5%, 38.5%, and 51.5% lower than respective CP specimens, and with nearly the same total heat release (only 0.04 MJ/m2 higher. Thus, PVDC exhibited excellent heat-reducing and smoke-suppressing properties and could replace CP in ULDFs.

  17. Effects of ultra-low sulphur diesel fuel and diesel oxidation catalysts on nitrogen dioxide emissions

    International Nuclear Information System (INIS)

    Stachulak, J.S.; Zarling, D.

    2010-01-01

    Diesel oxidation catalysts (DOCs) are used on diesel equipment in underground mines to reduce exhaust emissions of carbon monoxide (CO), hydrocarbons (C) and odour that are associated with gaseous HCs. New catalysts have also been formulated to minimize sulphate production, but little is know about their effects on nitrogen dioxide (NO 2 ) emissions. DOCs are known to oxidize nitric oxide (NO) to NO 2 , which is more toxic than NO at low levels. Vale Inco uses ultra-low sulphur diesel (ULSD) fuel for its underground diesel equipment. Although ULSD is a cleaner burning fuel, its impact on the emissions performance of DOCs is not fully known. Technical material gathered during a literature review suggested that ULSD fuel may increase NO 2 production if DOCs are used, but that the increase would be small. This paper presented the results of a laboratory evaluation of DOCs with varying amounts of time-in service in Vale Inco mines. The 4 Vale Inco DOCs were found to produce excess NO 2 during some test conditions. In both steady-state and transient testing, there were no obvious trends in NO 2 increases with increasing DOC age. Two possibilities for these observations are that the DOCs may have been well within their useful life or their initial compositions differed. Future studies will make use of improved instrumentation, notably NO 2 analyzers, to definitely determine the influence of DOCs on NO 2 formation. 13 refs., 1 tab., 8 figs.

  18. Ultra-low Dose CT for Attenuation Correction of 82Rb Cardiac PET

    DEFF Research Database (Denmark)

    Sørensen, Maria Balshøj; Bouchelouche, Kirsten; Tolbod, Lars Poulsen

    Aim: Myocardial perfusion imaging (MPI) using cardiac PET with tracers like 82Rb and 15O-water is substantially lower in radiation dose than classic MIBI-based SPECT. However, for cardiac PET, the dose contribution of CT for attenuation correction (CTAC) is typically 20-30% of the total dose....... To reduce the total radiation dose of cardiac PET further, we set out to examine if the use of ultra-low dose CTAC (UL-CTAC) would affect the accuracy of the quantitative parameters related to MPI. Furthermore, we examined whether the low quality of the UL-CTAC would affect the technologist’s ability...... to perform manual adjustment for misalignment between PET and CTAC. The CT reconstruction algorithm Q.AC was used to improve quality and consistency of the CTAC. Method: 23 consecutive clinical patients (BMI: 26.9 [range: 15.4-38.8]) referred for 82Rb PET rest and stress imaging were included in the study...

  19. Research and Development of Natural Draft Ultra-Low Emissions Burners for Gas Appliances

    Energy Technology Data Exchange (ETDEWEB)

    Therkelsen, Peter [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Cheng, Robert [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sholes, Darren [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2017-08-31

    Combustion systems used in residential and commercial cooking appliances must be robust and easy to use while meeting air quality standards. Current air quality standards for cooking appliances are far greater than other stationary combustion equipment. By developing an advanced low emission combustion system for cooking appliances, the air quality impacts from these devices can be reduced. This project adapted the Lawrence Berkeley National Laboratory (LBNL) Ring-Stabilizer Burner combustion technology for residential and commercial natural gas fired cooking appliances (such as ovens, ranges, and cooktops). LBNL originally developed the Ring-Stabilizer Burner for a NASA funded microgravity experiment. This natural draft combustion technology reduces NOx emissions significantly below current SCAQMD emissions standards without post combustion treatment. Additionally, the Ring-Stabilizer Burner technology does not require the assistance of a blower to achieve an ultra-low emission lean premix flame. The research team evaluated the Ring-Stabilizer Burner and fabricated the most promising designs based on their emissions and turndown.

  20. Reversed-field-pinch and ultra-low-q discharges in REPUTE-2

    International Nuclear Information System (INIS)

    Inoue, N.; Yoshida, Z.; Kamada, Y.; Saito, M.; Miyamoto, K.

    1987-01-01

    Ultra-low q (ULQ) and very-low q (VLQ) discharge experiments have been done using the REPUTE-1 RFP. It was found that in these q regime, the plasma density and beta are fairly high, and the confinement property is less sensitive to the error field compared to the RFP. However, since the temperature of the REPUTE-1 discharge is limited in low value because of the small plasma current due to the small toroidal field, its magnetic Reynolds number is too small to simulate the reactor plasma behavior. The radiation barrier has not been overcome yet, and consequently the energy confinement time is very short. In order to improve these aspects of the REPUTE-1 experiment, the REPUTE-2 is designed to produce higher toroidal field of 2T. The toroidal field increases slowly to the final value as in the case of the ramp-up mode of the RFP operation. The first stage of the REPUTE-2 project will be devoted to study the confinement physics of RFP, ULQ, and VLQ. In the second stage, innovation of these configurations, such as resistive shell RFP, neutral beam current drive, and higher current density, is planned. 8 refs., 1 fig., 2 tabs

  1. Ultra-low emittance electron beam generation using ionization injection in a plasma beatwave accelerator

    Science.gov (United States)

    Schroeder, Carl; Benedetti, Carlo; Esarey, Eric; Leemans, Wim

    2017-10-01

    Ultra-low emittance beams can be generated using ionization injection of electrons into a wakefield excited by a plasma beatwave accelerator. This all-optical method of electron beam generation uses three laser pulses of different colors. Two long-wavelength laser pulses, with frequency difference equal to the plasma frequency, resonantly drive a plasma wave without fully ionizing a gas. A short-wavelength injection laser pulse (with a small ponderomotive force and large peak electric field), co-propagating and delayed with respect to the beating long-wavelength lasers, ionizes a fraction of the remaining bound electrons at a trapped wake phase, generating an electron beam that is accelerated in the wakefield. Using the beating of long-wavelength pulses to generate the wakefield enables atomically-bound electrons to remain at low ionization potentials, reducing the required amplitude of the ionization pulse, and, hence, the initial transverse momentum and emittance of the injected electrons. An example is presented using two lines of a CO2 laser to form a plasma beatwave accelerator to drive the wake and a frequency-doubled Ti:Al2O3 laser for ionization injection. Supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

  2. Correlation of ultra-low dose chest CT findings with physiologic measures of asbestosis

    Energy Technology Data Exchange (ETDEWEB)

    Manners, David [Sir Charles Gairdner Hospital, Department of Respiratory Medicine, Nedlands, WA (Australia); Wong, Patrick; Murray, Conor; Teh, Joelin [Royal Perth Hospital, Department of Diagnostic Imaging, Perth (Australia); Kwok, Yi Jin [Sir Charles Gairdner Hospital, Department of Diagnostic Imaging, Nedlands, WA (Australia); De Klerk, Nick; Franklin, Peter [University of Western Australia, School of Population Health, Perth, WA (Australia); Alfonso, Helman; Reid, Alison [Curtin University, School of Public Health, Perth, WA (Australia); Musk, A.W.B. [Sir Charles Gairdner Hospital, Department of Respiratory Medicine, Nedlands, WA (Australia); University of Western Australia, School of Population Health, Perth, WA (Australia); University of Western Australia, School of Medicine and Pharmacology, Perth, WA (Australia); Brims, Fraser J.H. [Sir Charles Gairdner Hospital, Department of Respiratory Medicine, Nedlands, WA (Australia); University of Western Australia, School of Population Health, Perth, WA (Australia); Curtin University, Curtin Medical School, Perth (Australia)

    2017-08-15

    The correlation between ultra low dose computed tomography (ULDCT)-detected parenchymal lung changes and pulmonary function abnormalities is not well described. This study aimed to determine the relationship between ULDCT-detected interstitial lung disease (ILD) and measures of pulmonary function in an asbestos-exposed population. Two thoracic radiologists independently categorised prone ULDCT scans from 143 participants for ILD appearances as absent (score 0), probable (1) or definite (2) without knowledge of asbestos exposure or lung function. Pulmonary function measures included spirometry and diffusing capacity to carbon monoxide (DLCO). Participants were 92% male with a median age of 73.0 years. CT dose index volume was between 0.6 and 1.8 mGy. Probable or definite ILD was reported in 63 (44.1%) participants. Inter-observer agreement was good (k = 0.613, p < 0.001). There was a statistically significant correlation between the ILD score and both forced expiratory volume in 1 second (FEV{sub 1}) and forced vital capacity (FVC) (r = -0.17, p = 0.04 and r = -0.20, p = 0.02). There was a strong correlation between ILD score and DLCO (r = -0.34, p < 0.0001). Changes consistent with ILD on ULDCT correlate well with corresponding reductions in gas transfer, similar to standard CT. In asbestos-exposed populations, ULDCT may be adequate to detect radiological changes consistent with asbestosis. (orig.)

  3. High platinum utilization in ultra-low Pt loaded PEM fuel cell cathodes prepared by electrospraying

    Energy Technology Data Exchange (ETDEWEB)

    Martin, S.; Garcia-Ybarra, P.L.; Castillo, J.L. [Dept. Fisica Matematica y de Fluidos, Facultad de Ciencias, UNED, Senda del Rey 9, 28040 Madrid (Spain)

    2010-10-15

    Cathode electrodes for proton exchange membrane fuel cells (PEMFCs) with ultra-low platinum loadings as low as 0.012 mg{sub Pt}cm{sup -2} have been prepared by the electrospray method. The electrosprayed layers have nanostructured fractal morphologies with dendrites formed by clusters (about 100 nm diameter) of a few single catalyst particles rendering a large exposure surface of the catalyst. Optimization of the control parameters affecting this morphology has allowed us to overcome the state of the art for efficient electrodes prepared by electrospraying. Thus, using these cathodes in membrane electrode assemblies (MEAs), a high platinum utilization in the range 8-10 kW g{sup -1} was obtained for the fuel cell operating at 40 C and atmospheric pressure. Moreover, a platinum utilization of 20 kW g{sup -1} was attained under more suitable operating conditions (70 C and 3.4 bar over-pressure). These results substantially improve the performances achieved previously with other low platinum loading electrodes prepared by electrospraying. (author)

  4. An ultra-low-voltage electronic implementation of inertial neuron model with nonmonotonous Liao's activation function.

    Science.gov (United States)

    Kant, Nasir Ali; Dar, Mohamad Rafiq; Khanday, Farooq Ahmad

    2015-01-01

    The output of every neuron in neural network is specified by the employed activation function (AF) and therefore forms the heart of neural networks. As far as the design of artificial neural networks (ANNs) is concerned, hardware approach is preferred over software one because it promises the full utilization of the application potential of ANNs. Therefore, besides some arithmetic blocks, designing AF in hardware is the most important for designing ANN. While attempting to design the AF in hardware, the designs should be compatible with the modern Very Large Scale Integration (VLSI) design techniques. In this regard, the implemented designs should: only be in Metal Oxide Semiconductor (MOS) technology in order to be compatible with the digital designs, provide electronic tunability feature, and be able to operate at ultra-low voltage. Companding is one of the promising circuit design techniques for achieving these goals. In this paper, 0.5 V design of Liao's AF using sinh-domain technique is introduced. Furthermore, the function is tested by implementing inertial neuron model. The performance of the AF and inertial neuron model have been evaluated through simulation results, using the PSPICE software with the MOS transistor models provided by the 0.18-μm Taiwan Semiconductor Manufacturer Complementary Metal Oxide Semiconductor (TSM CMOS) process.

  5. Correlation of ultra-low dose chest CT findings with physiologic measures of asbestosis

    International Nuclear Information System (INIS)

    Manners, David; Wong, Patrick; Murray, Conor; Teh, Joelin; Kwok, Yi Jin; De Klerk, Nick; Franklin, Peter; Alfonso, Helman; Reid, Alison; Musk, A.W.B.; Brims, Fraser J.H.

    2017-01-01

    The correlation between ultra low dose computed tomography (ULDCT)-detected parenchymal lung changes and pulmonary function abnormalities is not well described. This study aimed to determine the relationship between ULDCT-detected interstitial lung disease (ILD) and measures of pulmonary function in an asbestos-exposed population. Two thoracic radiologists independently categorised prone ULDCT scans from 143 participants for ILD appearances as absent (score 0), probable (1) or definite (2) without knowledge of asbestos exposure or lung function. Pulmonary function measures included spirometry and diffusing capacity to carbon monoxide (DLCO). Participants were 92% male with a median age of 73.0 years. CT dose index volume was between 0.6 and 1.8 mGy. Probable or definite ILD was reported in 63 (44.1%) participants. Inter-observer agreement was good (k = 0.613, p < 0.001). There was a statistically significant correlation between the ILD score and both forced expiratory volume in 1 second (FEV 1 ) and forced vital capacity (FVC) (r = -0.17, p = 0.04 and r = -0.20, p = 0.02). There was a strong correlation between ILD score and DLCO (r = -0.34, p < 0.0001). Changes consistent with ILD on ULDCT correlate well with corresponding reductions in gas transfer, similar to standard CT. In asbestos-exposed populations, ULDCT may be adequate to detect radiological changes consistent with asbestosis. (orig.)

  6. Ultra-low specific on-resistance SOI double-gate trench-type MOSFET

    International Nuclear Information System (INIS)

    Lei Tianfei; Luo Xiaorong; Ge Rui; Chen Xi; Wang Yuangang; Yao Guoliang; Jiang Yongheng; Zhang Bo; Li Zhaoji

    2011-01-01

    An ultra-low specific on-resistance (R on,sp ) silicon-on-insulator (SOI) double-gate trench-type MOSFET (DG trench MOSFET) is proposed. The MOSFET features double gates and an oxide trench: the oxide trench is in the drift region, one trench gate is inset in the oxide trench and one trench gate is extended into the buried oxide. Firstly, the double gates reduce R on,sp by forming dual conduction channels. Secondly, the oxide trench not only folds the drift region, but also modulates the electric field, thereby reducing device pitch and increasing the breakdown voltage (BV). ABV of 93 V and a R on,sp of 51.8 mΩ·mm 2 is obtained for a DG trench MOSFET with a 3 μm half-cell pitch. Compared with a single-gate SOI MOSFET (SG MOSFET) and a single-gate SOI MOSFET with an oxide trench (SG trench MOSFET), the R on,sp of the DG trench MOSFET decreases by 63.3% and 33.8% at the same BV, respectively. (semiconductor devices)

  7. Investigation of plasma etch damage to porous oxycarbosilane ultra low-k dielectric

    International Nuclear Information System (INIS)

    Bruce, R L; Engelmann, S; Purushothaman, S; Volksen, W; Frot, T J; Magbitang, T; Dubois, G; Darnon, M

    2013-01-01

    There has been much interest recently in porous oxycarbosilane (POCS)-based materials as the ultra-low k dielectric (ULK) in back-end-of-line (BEOL) applications due to their superior mechanical properties compared to traditional organosilicate-based ULK materials at equivalent porosity and dielectric constant. While it is well known that plasma etching and strip processes can cause significant damage to ULK materials in general, little has been reported about the effect of plasma damage to POCS as the ULK material. We investigated the effect of changing the gas discharge chemistry and substrate bias in the dielectric trench etch and also the subsequent effect of the cap-open etch on plasma damage to POCS during BEOL integration. Large differences in surface roughness and damage behaviour were observed by changing the fluorocarbon depositing conditions. These damage behaviour trends will be discussed and potential rationalizations offered based on the formation of pits and craters at the etch front that lead to surface roughness and microtrenching. (paper)

  8. Frustrated incomplete donor ionization in ultra-low resistivity germanium films

    International Nuclear Information System (INIS)

    Xu, Chi; Menéndez, J.; Senaratne, C. L.; Kouvetakis, J.

    2014-01-01

    The relationship between carrier concentration and donor atomic concentration has been determined in n-type Ge films doped with P. The samples were carefully engineered to minimize non-active dopant incorporation by using specially designed P(SiH 3 ) 3 and P(GeH 3 ) 3 hydride precursors. The in situ nature of the doping and the growth at low temperatures, facilitated by the Ge 3 H 8 and Ge 4 H 10 Ge sources, promote the creation of ultra-low resistivity films with flat doping profiles that help reduce the errors in the concentration measurements. The results show that Ge deviates strongly from the incomplete ionization expected when the donor atomic concentration exceeds N d  = 10 17  cm −3 , at which the energy separation between the donor and Fermi levels ceases to be much larger than the thermal energy. Instead, essentially full ionization is seen even at the highest doping levels beyond the solubility limit of P in Ge. The results can be explained using a model developed for silicon by Altermatt and coworkers, provided the relevant model parameter is properly scaled. The findings confirm that donor solubility and/or defect formation, not incomplete ionization, are the major factors limiting the achievement of very high carrier concentrations in n-type Ge. The commercially viable chemistry approach applied here enables fabrication of supersaturated and fully ionized prototypes with potential for broad applications in group-IV semiconductor technologies

  9. Cross-validation of independent ultra-low-frequency magnetic recording systems for active fault studies

    Science.gov (United States)

    Wang, Can; Bin, Chen; Christman, Lilianna E.; Glen, Jonathan M. G.; Klemperer, Simon L.; McPhee, Darcy K.; Kappler, Karl N.; Bleier, Tom E.; Dunson, J. Clark

    2018-04-01

    When working with ultra-low-frequency (ULF) magnetic datasets, as with most geophysical time-series data, it is important to be able to distinguish between cultural signals, internal instrument noise, and natural external signals with their induced telluric fields. This distinction is commonly attempted using simultaneously recorded data from a spatially remote reference site. Here, instead, we compared data recorded by two systems with different instrumental characteristics at the same location over the same time period. We collocated two independent ULF magnetic systems, one from the QuakeFinder network and the other from the United States Geological Survey (USGS)-Stanford network, in order to cross-compare their data, characterize data reproducibility, and characterize signal origin. In addition, we used simultaneous measurements at a remote geomagnetic observatory to distinguish global atmospheric signals from local cultural signals. We demonstrated that the QuakeFinder and USGS-Stanford systems have excellent coherence, despite their different sensors and digitizers. Rare instances of isolated signals recorded by only one system or only one sensor indicate that caution is needed when attributing specific recorded signal features to specific origins.[Figure not available: see fulltext.

  10. Analytical validation of an ultra low-cost mobile phone microplate reader for infectious disease testing.

    Science.gov (United States)

    Wang, Li-Ju; Naudé, Nicole; Demissie, Misganaw; Crivaro, Anne; Kamoun, Malek; Wang, Ping; Li, Lei

    2018-07-01

    Most mobile health (mHealth) diagnostic devices for laboratory tests only analyze one sample at a time, which is not suitable for large volume serology testing, especially in low-resource settings with shortage of health professionals. In this study, we developed an ultra-low-cost clinically-accurate mobile phone microplate reader (mReader), and clinically validated this optical device for 12 infectious disease tests. The mReader optically reads 96 samples on a microplate at one time. 771 de-identified patient samples were tested for 12 serology assays for bacterial/viral infections. The mReader and the clinical instrument blindly read and analyzed all tests in parallel. The analytical accuracy and the diagnostic performance of the mReader were evaluated across the clinical reportable categories by comparison with clinical laboratorial testing results. The mReader exhibited 97.59-99.90% analytical accuracy and envision the mReader can benefit underserved areas/populations and low-resource settings in rural clinics/hospitals at a low cost (~$50 USD) with clinical-level analytical quality. It has the potential to improve health access, speed up healthcare delivery, and reduce health disparities and education disparities by providing access to a low-cost spectrophotometer. Copyright © 2018 Elsevier B.V. All rights reserved.

  11. The ultra low frequency electromagnetic radiation observed in the topside ionosphere above boundaries of tectonic plates

    Directory of Open Access Journals (Sweden)

    Michael A. Athanasiou

    2015-01-01

    Full Text Available In this paper we present results of a comparison between ultra low frequency (ULF electromagnetic (EM radiation, recorded by an electric field instrument onboard the satellite detection of electromagnetic emissions transmitted from earthquake regions in the topside ionosphere, and the seismicity of regions with high and low seismic activity. In particular, we evaluated the energy variations of the ULF Ezelectric field component during a period of four years (2006-2009, in order to examine the possible relation of ULF EM radiation with seismogenic regions located in Central America, Indonesia, the Eastern Mediterranean Basin and Greece. As a tool for evaluating the ULF Ez energy variations we used singular spectrum analysis techniques. The results of our analysis clearly show a significant increase of the ULF EM energy emitted from regions of highest seismic activity at the boundaries tectonic plates. Furthermore, we found that higher electromagnetic radiation was detected in a region above the northern- western Greek Arc (R1 than above the adjacent region including Athens and its urban area. We interpret these results of the present study as suggesting that: i the seismogenic regions at the boundary of tectonic plates radiate ULF EM emissions observed by satellites in the topside ionosphere; and ii that this EM radiation is not only related with the occurrence time of great (M≥5 earthquakes, but it is often present in intermediate times and it appears as a quasi-permanent phenomenon.

  12. Ultra-low background retrieval of photons stored in warm Rb vapor

    Science.gov (United States)

    Figueroa, Eden; Neuzner, Andreas; Latka, Tobias; Schupp, Josef; Noelleke, Christian; Reiserer, Andreas; Ritter, Stephan; Rempe, Gerhard

    2013-05-01

    The development of a simple and inexpensive platform for interconnecting light and matter at the quantum level has recently emerged as one of the key challenges of the rapidly evolving field of quantum engineering. Although elementary quantum memory capabilities have been already shown using ensembles of cold atoms or single-atoms in optical cavities, a scalable-friendly architecture might still require room temperature operation. Here we use an ensemble of Rb atoms in the gaseous state and store light pulses at the single-photon level to demonstrate that even in a common vapor cell it is possible to achieve quantum-level operation with ultra-low background noise. We have obtained a measured signal- to-background noise ratio of 3.5, which is the first time this figure of merit has been lifted beyond unity for experiments with room temperature operation. In addition, we also show the capabilities of the system to arbitrarily tailor the temporal properties of the retrieved single-photon-level pulses.

  13. Structural developments in un-stabilized ultra low carbon steel during warm deformation and annealing

    Energy Technology Data Exchange (ETDEWEB)

    Unnikrishnan, Rahul, E-mail: rahulunnikrishnannair@gmail.com [Department of Metallurgical and Materials Engineering, Visvesvaraya National Institute of Technology (VNIT), South Ambazari Road, Nagpur 440010, Maharashtra (India); Kumar, Amit, E-mail: chaudhary65amit@gmail.com [Department of Metallurgical and Materials Engineering, Visvesvaraya National Institute of Technology (VNIT), South Ambazari Road, Nagpur 440010, Maharashtra (India); Khatirkar, Rajesh K., E-mail: rajesh.khatirkar@gmail.com [Department of Metallurgical and Materials Engineering, Visvesvaraya National Institute of Technology (VNIT), South Ambazari Road, Nagpur 440010, Maharashtra (India); Shekhawat, Satish K., E-mail: satishshekhawat@gmail.com [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay (IITB), Powai, Mumbai 400076, Maharashtra (India); Sapate, Sanjay G., E-mail: sgsapate@yahoo.com [Department of Metallurgical and Materials Engineering, Visvesvaraya National Institute of Technology (VNIT), South Ambazari Road, Nagpur 440010, Maharashtra (India)

    2016-11-01

    In the present investigation, ultra low carbon steel samples were deformed in plane strain compression mode in a deformation simulator. The deformation was carried out at four different temperatures in the warm rolling region (293, 473, 673 and 873 K) upto 70% strain at two different strain rates (0.1/s and 1/s). Subsequently, all the deformed samples were fully recrystallized at 1073 K. Afterwards, all the deformed and fully recrystallized samples were subjected to detailed microstructural characterization using optical microscope, scanning electron microscope and electron backscattered diffraction. Bulk texture was measured for all the samples by X-ray diffraction. In-grain misorientation developments (kernel average misorientations) were estimated for the deformed γ-fibre (ND//<111>) and α-fibre (RD//<110>). Deformed γ-fibre showed an increase in in-grain misorientation at intermediate deformation temperatures. This increase was explained by using the plastic instability criterion. After complete recrystallization, the γ-fibre strengthened for deformation at lower temperatures (293 K and 473 K), while Goss texture developed for samples deformed at higher temperatures (673 K and 873 K). - Highlights: • ULC steel samples were deformed in near plane strain condition. • Microstructural developments were characterized using EBSD. • Increase in in-grain misorientation at intermediate deformation temperatures. • γ-fibre strengthened for low temperature deformation. • Goss texture developed for high temperature deformation.

  14. Environmental fate model for ultra-low-volume insecticide applications used for adult mosquito management

    Science.gov (United States)

    Schleier, Jerome J.; Peterson, Robert K.D.; Irvine, Kathryn M.; Marshall, Lucy M.; Weaver, David K.; Preftakes, Collin J.

    2012-01-01

    One of the more effective ways of managing high densities of adult mosquitoes that vector human and animal pathogens is ultra-low-volume (ULV) aerosol applications of insecticides. The U.S. Environmental Protection Agency uses models that are not validated for ULV insecticide applications and exposure assumptions to perform their human and ecological risk assessments. Currently, there is no validated model that can accurately predict deposition of insecticides applied using ULV technology for adult mosquito management. In addition, little is known about the deposition and drift of small droplets like those used under conditions encountered during ULV applications. The objective of this study was to perform field studies to measure environmental concentrations of insecticides and to develop a validated model to predict the deposition of ULV insecticides. The final regression model was selected by minimizing the Bayesian Information Criterion and its prediction performance was evaluated using k-fold cross validation. Density of the formulation and the density and CMD interaction coefficients were the largest in the model. The results showed that as density of the formulation decreases, deposition increases. The interaction of density and CMD showed that higher density formulations and larger droplets resulted in greater deposition. These results are supported by the aerosol physics literature. A k-fold cross validation demonstrated that the mean square error of the selected regression model is not biased, and the mean square error and mean square prediction error indicated good predictive ability.

  15. Input comparison of radiogenic neutron estimates for ultra-low background experiments

    Science.gov (United States)

    Cooley, J.; Palladino, K. J.; Qiu, H.; Selvi, M.; Scorza, S.; Zhang, C.

    2018-04-01

    Ultra-low-background experiments address some of the most important open questions in particle physics, cosmology and astrophysics: the nature of dark matter, whether the neutrino is its own antiparticle, and does the proton decay. These rare event searches require well-understood and minimized backgrounds. Simulations are used to understand backgrounds caused by naturally occurring radioactivity in the rock and in every piece of shielding and detector material used in these experiments. Most important are processes like spontaneous fission and (α,n) reactions in material close to the detectors that can produce neutrons. A comparison study of the (α,n) reactions between two dedicated software packages is detailed. The cross section libraries, neutron yields, and spectra from the Mei-Zhang-Hime and the SOURCES-4A codes are presented. The resultant yields and spectra are used as inputs to direct dark matter detector toy models in GEANT4, to study the impact of their differences on background estimates and fits. Although differences in neutron yield calculations up to 50% were seen, there was no systematic difference between the Mei-Hime-Zhang and SOURCES-4A results. Neutron propagation simulations smooth differences in spectral shape and yield, and both tools were found to meet the broad requirements of the low-background community.

  16. Transducer project and optimization of the ultra low magnetic field NMR tomograph reception system system

    International Nuclear Information System (INIS)

    Vidoto, Edson Luiz Gea

    1995-01-01

    The aim of the present work was to optimize the signal to noise ratio in our NMR imaging system (TORM 005) by improving transducer's reception quality through better designed coils, balanced tuning circuit for this coils and power decoupling circuits and by reducing interference from the electromagnetic environment. For this purpose, we had to modify the internal electromagnetic shielding and incorporate line filters in the more critical signals paths. Also, new types of coils were developed, improving the signal to noise ratio, and allowing us to make clinical exams with superior quality for several anatomies. Balanced circuits for tuning and matching of the coil were studied and built, allowing a reduction of the coil losses because patient's load. This produced a more reliable coil tuning after positioning each new patient. Circuits to avoid the receiver input overload and decoupling circuits for the isolation of receiver coils from excitation coil were designed and incorporated to the TORM 005. All these alterations of our imaging system (TORM 005) contributed to a significant improvement in the signal to noise ratio, reliability and reproducibility of the system. This permitted to operate the system routinely for clinical applications, research and development in the area of ultra low magnetic field tomography. (author)

  17. Analysis and application of classification methods of complex carbonate reservoirs

    Science.gov (United States)

    Li, Xiongyan; Qin, Ruibao; Ping, Haitao; Wei, Dan; Liu, Xiaomei

    2018-06-01

    There are abundant carbonate reservoirs from the Cenozoic to Mesozoic era in the Middle East. Due to variation in sedimentary environment and diagenetic process of carbonate reservoirs, several porosity types coexist in carbonate reservoirs. As a result, because of the complex lithologies and pore types as well as the impact of microfractures, the pore structure is very complicated. Therefore, it is difficult to accurately calculate the reservoir parameters. In order to accurately evaluate carbonate reservoirs, based on the pore structure evaluation of carbonate reservoirs, the classification methods of carbonate reservoirs are analyzed based on capillary pressure curves and flow units. Based on the capillary pressure curves, although the carbonate reservoirs can be classified, the relationship between porosity and permeability after classification is not ideal. On the basis of the flow units, the high-precision functional relationship between porosity and permeability after classification can be established. Therefore, the carbonate reservoirs can be quantitatively evaluated based on the classification of flow units. In the dolomite reservoirs, the average absolute error of calculated permeability decreases from 15.13 to 7.44 mD. Similarly, the average absolute error of calculated permeability of limestone reservoirs is reduced from 20.33 to 7.37 mD. Only by accurately characterizing pore structures and classifying reservoir types, reservoir parameters could be calculated accurately. Therefore, characterizing pore structures and classifying reservoir types are very important to accurate evaluation of complex carbonate reservoirs in the Middle East.

  18. Ultra-Low Inductance Design for a GaN HEMT Based 3L-ANPC Inverter

    DEFF Research Database (Denmark)

    Gurpinar, Emre; Castellazzi, Alberto; Iannuzzo, Francesco

    2016-01-01

    contributors to voltage overshoots and increase of switching losses, are discussed. The ultra-low inductance power cell design based on a four layer PCB with the aim to maximise the switching performance of GaN HEMTs is explained. Gate driver design for GaN HEMT devices is presented. Common-mode behaviours......In this paper, an ultra-low inductance power cell design for a 3L-ANPC based on 650 V GaN HEMT devices is presented. The 3L-ANPC topology with GaN HEMT devices and the selected modulation scheme suitable for wide-bandgap (WBG) devices are presented. The commutation loops, which are the main...

  19. Cystic Fibrosis: Are Volumetric Ultra-Low-Dose Expiratory CT Scans Sufficient for Monitoring Related Lung Disease?

    DEFF Research Database (Denmark)

    Loeve, Martine; Lequin, Maarten H; Bruijne, Marleen de

    2009-01-01

    Purpose: To assess whether chest computed tomography (CT) scores from ultra-low-dose end-expiratory scans alone could suffice for assessment of all cystic fibrosis (CF)-related structural lung abnormalities. Materials and Methods: In this institutional review board–approved study, 20 patients...... with CF aged 6–20 years (eight males, 12 females) underwent low-dose end-inspiratory CT and ultra-low-dose end-expiratory CT. Informed consent was obtained. Scans were randomized and scored by using the Brody-II CT scoring system to assess bronchiectasis, airway wall thickening, mucus plugging......-Altman plots. Results: Median age was 12.6 years (range, 6.3–20.3 years), median forced expiratory volume in 1 second was 100% (range, 46%–127%) of the predicted value, and median forced vital capacity was 99% (range, 61%–123%) of the predicted value. Very good agreement was observed between end...

  20. Ultra-low power anti-crosstalk collision avoidance light detection and ranging using chaotic pulse position modulation approach

    International Nuclear Information System (INIS)

    Hao Jie; Gong Ma-li; Du Peng-fei; Lu Bao-jie; Zhang Fan; Zhang Hai-tao; Fu Xing

    2016-01-01

    A novel concept of collision avoidance single-photon light detection and ranging (LIDAR) for vehicles has been demonstrated, in which chaotic pulse position modulation is applied on the transmitted laser pulses for robust anti-crosstalk purposes. Besides, single-photon detectors (SPD) and time correlated single photon counting techniques are adapted, to sense the ultra-low power used for the consideration of compact structure and eye safety. Parameters including pulse rate, discrimination threshold, and number of accumulated pulses have been thoroughly analyzed based on the detection requirements, resulting in specified receiver operating characteristics curves. Both simulation and indoor experiments were performed to verify the excellent anti-crosstalk capability of the presented collision avoidance LIDAR despite ultra-low transmitting power. (paper)

  1. Combination of Continuous Dexmedetomidine Infusion with Titrated Ultra-Low-Dose Propofol-Fentanyl for an Awake Craniotomy; Case report

    Directory of Open Access Journals (Sweden)

    Samaresh Das

    2016-08-01

    Full Text Available An awake craniotomy is a continuously evolving technique used for the resection of brain tumours from the eloquent cortex. We report a 29-year-old male patient who presented to the Khoula Hospital, Muscat, Oman, in 2016 with a two month history of headaches and convulsions due to a space-occupying brain lesion in close proximity with the left motor cortex. An awake craniotomy was conducted using a scalp block, continuous dexmedetomidine infusion and a titrated ultra-low-dose of propofol-fentanyl. The patient remained comfortable throughout the procedure and the intraoperative neuropsychological tests, brain mapping and tumour resection were successful. This case report suggests that dexmedetomidine in combination with titrated ultra-low-dose propofolfentanyl are effective options during an awake craniotomy, ensuring optimum sedation, minimal disinhibition and a rapid recovery. To the best of the authors’ knowledge, this is the first awake craniotomy conducted successfully in Oman.

  2. Combination of Continuous Dexmedetomidine Infusion with Titrated Ultra-Low-Dose Propofol-Fentanyl for an Awake Craniotomy

    Science.gov (United States)

    Das, Samaresh; Al-Mashani, Ali; Suri, Neelam; Salhotra, Neeraj; Chatterjee, Nilay

    2016-01-01

    An awake craniotomy is a continuously evolving technique used for the resection of brain tumours from the eloquent cortex. We report a 29-year-old male patient who presented to the Khoula Hospital, Muscat, Oman, in 2016 with a two month history of headaches and convulsions due to a space-occupying brain lesion in close proximity with the left motor cortex. An awake craniotomy was conducted using a scalp block, continuous dexmedetomidine infusion and a titrated ultra-low-dose of propofolfentanyl. The patient remained comfortable throughout the procedure and the intraoperative neuropsychological tests, brain mapping and tumour resection were successful. This case report suggests that dexmedetomidine in combination with titrated ultra-low-dose propofolfentanyl are effective options during an awake craniotomy, ensuring optimum sedation, minimal disinhibition and a rapid recovery. To the best of the authors’ knowledge, this is the first awake craniotomy conducted successfully in Oman. PMID:27606116

  3. Push-back technique facilitates ultra-low anterior resection without nerve injury in total mesorectal excision for rectal cancer.

    Science.gov (United States)

    Inoue, Yasuhiro; Hiro, Junichiro; Toiyama, Yuji; Tanaka, Koji; Uchida, Keiichi; Miki, Chikao; Kusunoki, Masato

    2011-01-01

    To describe our push-back approach to ultra-low anterior resection using the concept of the mucosal stump. We mobilize the rectum using an abdominal approach, and perform mucosal cutting circumferentially at the dentate line. The mucosal stump is closed, and the internal sphincteric muscle resected partially or totally according to tumor location. Perianal dissection is performed along the medial plane of the external sphincteric muscles, and the hiatal ligament is dissected posteriorly. To resect the entire rectum, the closed rectal stump is pushed back to the abdominal cavity using composed gauze. This prevents injury to the autonomic nerve. We performed colonic J-pouch anal anastomosis using our mucosal stump approach in 58 patients with rectal cancer located push-back approach for internal sphincter resection produces satisfactory functional and oncological results in ultra-low anterior rectal cancer. Copyright © 2011 S. Karger AG, Basel.

  4. Experimental study of ultra-low q discharges in the linear Extrap L1 device

    International Nuclear Information System (INIS)

    Brunsell, P.; Karlsson, Per.

    1991-01-01

    Linear pinch discharges with combined octupole and longitudinal magnetic fields are experimentally studied in the Extrap L1 device. Plasma currents are around I p =10 kA, plasma temperautres are up to T e =50 eV and plasma densities are of the order of n=5x10 21 m -3 . The plasma equilibria are in the ultra-low q (ULQ) regime corresponding to operation with plasma currents in excess of the Kruskal-Shafranov stability limit (q less than 1). The plasma current exhibits the typical time behaviour seen in toroidal ULQ experiments; the unstable setting up phase and the step-wise decay with current levels corresponding to q-values in windows between rational values. Longitudinal plasma current generated by radial plasma diffusion is seen, with amplitudes up to 30% of the externally driven current during the initial phase of the discharge. The effect of the octupole magnetic field on the ULQ confinement is investigated. The plasma temperature increases by more than a factor of two, for the optimum octupole rod current (I v =I p ), compared to the case without octupole field. A plasma current limitation for stable operation corresponding to q bigger than 1/2 is observed, excepts for low axial magnetic field strength. In the low axial field regime, the octupole field alone provides sufficient stabilization for operation with q less than 1/2. Plasma density and temperature both increase linearly with applied axial magnetic field. The density shows a strong, approximately exponential, dependence on discharge voltage. (au)

  5. Advanced 65 nm CMOS devices fabricated using ultra-low energy plasma doping

    International Nuclear Information System (INIS)

    Walther, S.; Lenoble, D.; Lallement, F.; Grouillet, A.; Erokhin, Y.; Singh, V.; Testoni, A.

    2005-01-01

    For leading edge CMOS and DRAM technologies, plasma doping (PLAD) offers several unique advantages over conventional beamline implantation. For ultra-low energy source and drain extensions (SDE), source drain contact and high dose poly doping implants PLAD delivers 2-5x higher throughput compared to beamline implanters. In this work we demonstrate process performance and process integration benefits enabled by plasma doping for advanced 65 nm CMOS devices. Specifically, p + /n ultra-shallow junctions formed with BF 3 plasma doping have superior X j /R s characteristics to beamline implants and yield up to 30% lower R s for 20 nm X j while using standard spike anneal with ramp-up rate of 75 deg. C/s. These results indicate that PLAD could extend applicability of standard spike anneal by at least one technology node past 65 nm. A CMOS split lot has been run to investigate process integration advantages unique to plasma doping and to determine CMOS device characteristics. Device data measured on 65 nm transistors fabricated with offset spacers indicate that devices with SDE formed by plasma doping have superior V t roll-off characteristics arguably due to improved lateral gate-overlap of PLAD SDE junctions. Furthermore, offset spacers could be eliminated in 65 nm devices with PLAD SDE implants while still achieving V t roll-off and I on -I off performance at least equivalent to control devices with offset spacers and SDE formed by beamline implantation. Thus, another advantage of PLAD is simplified 65 nm CMOS manufacturing process flow due to elimination of offset spacers. Finally, we present process transfer from beamline implants to PLAD for several applications, including SDE and gate poly doping with very high productivity

  6. Quantitative depth profiling of near surface semiconductor structures using ultra low energy SIMS analysis

    International Nuclear Information System (INIS)

    Elliner, D.I.

    1999-09-01

    The continual reduction in size of semiconductor structures and depths of junctions is putting a greater strain on characterization techniques. Accurate device and process modelling requires quantified electrical and dopant profiles from the topmost few nanometres. Secondary ion mass spectrometry (SIMS) is an analytical technique commonly used in the semiconductor industry to measure concentration depth profiles. To allow the quantification of the features that are closer to the surface, lower energy ions are employed, which also improves the available depth resolution. The development of the floating ion gun (FLIG) has made it possible to use sub keV beam energies on a routine basis, allowing quantified dopant profiles to be obtained within the first few nanometres of the surface. This thesis demonstrates that, when profiling with oxygen ion beams, greatest certainty in the retained dose is achieved at normal incidence, and when analysing boron accurate profile shapes are only obtained when the primary beam energy is less than half that of the implant. It was shown that it is now possible to profile, though with slower erosion rates and a limited dynamic range, with 100 eV oxygen (0 2 + ) ion beams. Profile features that had developed during rapid thermal annealing, that could only be observed when ultra low energy ion beams were used, were investigated using various analytical techniques. Explanations of the apparently inactive dopant were proposed, and included suggestions for cluster molecules. The oxide thickness of fully formed altered layers has also been investigated. The results indicate that a fundamental change in the mechanism of oxide formation occurs, and interfaces that are sharper than those grown by thermal oxidation can be produced using sub-keV ion beams. (author)

  7. Ultra-low dose CT attenuation correction for PET/CT

    International Nuclear Information System (INIS)

    Xia Ting; Kinahan, Paul E; Alessio, Adam M; De Man, Bruno; Manjeshwar, Ravindra; Asma, Evren

    2012-01-01

    A challenge for positron emission tomography/computed tomography (PET/CT) quantitation is patient respiratory motion, which can cause an underestimation of lesion activity uptake and an overestimation of lesion volume. Several respiratory motion correction methods benefit from longer duration CT scans that are phase matched with PET scans. However, even with the currently available, lowest dose CT techniques, extended duration cine CT scans impart a substantially high radiation dose. This study evaluates methods designed to reduce CT radiation dose in PET/CT scanning. We investigated selected combinations of dose reduced acquisition and noise suppression methods that take advantage of the reduced requirement of CT for PET attenuation correction (AC). These include reducing CT tube current, optimizing CT tube voltage, adding filtration, CT sinogram smoothing and clipping. We explored the impact of these methods on PET quantitation via simulations on different digital phantoms. CT tube current can be reduced much lower for AC than that in low dose CT protocols. Spectra that are higher energy and narrower are generally more dose efficient with respect to PET image quality. Sinogram smoothing could be used to compensate for the increased noise and artifacts at radiation dose reduced CT images, which allows for a further reduction of CT dose with no penalty for PET image quantitation. When CT is not used for diagnostic and anatomical localization purposes, we showed that ultra-low dose CT for PET/CT is feasible. The significant dose reduction strategies proposed here could enable respiratory motion compensation methods that require extended duration CT scans and reduce radiation exposure in general for all PET/CT imaging. (paper)

  8. The Role of Localized Compressional Ultra-low Frequency Waves in Energetic Electron Precipitation

    Science.gov (United States)

    Rae, I. Jonathan; Murphy, Kyle R.; Watt, Clare E. J.; Halford, Alexa J.; Mann, Ian R.; Ozeke, Louis G.; Sibeck, David G.; Clilverd, Mark A.; Rodger, Craig J.; Degeling, Alex W.; Forsyth, Colin; Singer, Howard J.

    2018-03-01

    Typically, ultra-low frequency (ULF) waves have historically been invoked for radial diffusive transport leading to acceleration and loss of outer radiation belt electrons. At higher frequencies, very low frequency waves are generally thought to provide a mechanism for localized acceleration and loss through precipitation into the ionosphere of radiation belt electrons. In this study we present a new mechanism for electron loss through precipitation into the ionosphere due to a direct modulation of the loss cone via localized compressional ULF waves. We present a case study of compressional wave activity in tandem with riometer and balloon-borne electron precipitation across keV-MeV energies to demonstrate that the experimental measurements can be explained by our new enhanced loss cone mechanism. Observational evidence is presented demonstrating that modulation of the equatorial loss cone can occur via localized compressional wave activity, which greatly exceeds the change in pitch angle through conservation of the first and second adiabatic invariants. The precipitation response can be a complex interplay between electron energy, the localization of the waves, the shape of the phase space density profile at low pitch angles, ionospheric decay time scales, and the time dependence of the electron source; we show that two pivotal components not usually considered are localized ULF wave fields and ionospheric decay time scales. We conclude that enhanced precipitation driven by compressional ULF wave modulation of the loss cone is a viable candidate for direct precipitation of radiation belt electrons without any additional requirement for gyroresonant wave-particle interaction. Additional mechanisms would be complementary and additive in providing means to precipitate electrons from the radiation belts during storm times.

  9. The role of localised Ultra-Low Frequency waves in energetic electron precipitation

    Science.gov (United States)

    Rae, J.; Murphy, K. R.; Watt, C.; Mann, I. R.; Ozeke, L.; Halford, A. J.; Sibeck, D. G.; Clilverd, M. A.; Rodger, C. J.; Degeling, A. W.; Singer, H. J.

    2016-12-01

    Electromagnetic waves play pivotal roles in radiation belt dynamics through a variety of different means. Typically, Ultra-Low Frequency (ULF) waves have historically been invoked for radial diffusive transport leading to both acceleration and loss of outer radiation belt electrons. Very-Low Frequency (VLF) and Extremely-Low Frequency (ELF) waves are generally thought to provide a mechanism for localized acceleration and loss through precipitation into the ionosphere. In this study we present a new mechanism for electron loss through precipitation into the ionosphere due to direct modulation of the loss cone via localized compressional ULF waves. Observational evidence is presented demonstrating that modulation of the equatorial loss cone can occur via localized compressional wave activity. We then perform statistical computations of the probability distribution to determine how likely a given magnetic perturbation would produce a given percentage change in the bounce loss-cone (BLC). We discuss the ramifications of the action of coherent, localized compressional ULF waves on drifting electron populations; their precipitation response can be a complex interplay between electron energy, the shape of the phase space density profile at pitch angles close to the loss cone, ionospheric decay timescales, and the time-dependence of the electron source. We present a case study of compressional wave activity in tandem with riometer and balloon-borne electron precipitation across keV-MeV energies to demonstrate that the experimental measurements can be explained by our new enhanced loss cone mechanism. We determine that the two pivotal components not usually considered are localized ULF wave fields and ionospheric decay timescales. We conclude that ULF wave modulation of the loss cone is a viable candidate for direct precipitation of radiation belt electrons without any additional requirement for gyroresonant wave-particle interaction. Additional mechanisms would be

  10. MESSENGER Magnetic Field Observations of Upstream Ultra-Low Frequency Waves at Mercury

    Science.gov (United States)

    Le, G.; Chi, P. J.; Boardsen, S.; Blanco-Cano, X.; Anderosn, B. J.; Korth, H.

    2012-01-01

    The region upstream from a planetary bow shock is a natural plasma laboratory containing a variety of wave particle phenomena. The study of foreshocks other than the Earth's is important for extending our understanding of collisionless shocks and foreshock physics since the bow shock strength varies with heliocentric distance from the Sun, and the sizes of the bow shocks are different at different planets. The Mercury's bow shock is unique in our solar system as it is produced by low Mach number solar wind blowing over a small magnetized body with a predominately radial interplanetary magnetic field. Previous observations of Mercury upstream ultra-low frequency (ULF) waves came exclusively from two Mercury flybys of Mariner 10. The MESSENGER orbiter data enable us to study of upstream waves in the Mercury's foreshock in depth. This paper reports an overview of upstream ULF waves in the Mercury's foreshock using high-time resolution magnetic field data, 20 samples per second, from the MESSENGER spacecraft. The most common foreshock waves have frequencies near 2 Hz, with properties similar to the I-Hz waves in the Earth's foreshock. They are present in both the flyby data and in every orbit of the orbital data we have surveyed. The most common wave phenomenon in the Earth's foreshock is the large-amplitude 30-s waves, but similar waves at Mercury have frequencies at near 0.1 Hz and occur only sporadically with short durations (a few wave cycles). Superposed on the "30-s" waves, there are spectral peaks at near 0.6 Hz, not reported previously in Mariner 10 data. We will discuss wave properties and their occurrence characteristics in this paper.

  11. Ultra-Low Field SQUID-NMR using LN2 Cooled Cu Polarizing Field coil

    Science.gov (United States)

    Demachi, K.; Kawagoe, S.; Ariyoshi, S.; Tanaka, S.

    2017-07-01

    We are developing an Ultra-Low Field (ULF) Magnetic Resonance Imaging (MRI) system using a High-Temperature Superconductor superconducting quantum interference device (HTS rf-SQUID) for food inspection. The advantages of the ULF-NMR (Nuclear Magnetic Resonance) / MRI as compared with a conventional high field MRI are that they are compact and of low cost. In this study, we developed a ULF SQUID-NMR system using a polarizing coil to measure fat of which relaxation time T1 is shorter. The handmade polarizing coil was cooled by liquid nitrogen to reduce the resistance and accordingly increase the allowable current. The measured decay time of the polarizing field was 40 ms. The measurement system consisted of the liquid nitrogen cooled polarizing coil, a SQUID, a Cu wound flux transformer, a measurement field coil for the field of 47 μT, and an AC pulse coil for a 90°pulse field. The NMR measurements were performed in a magnetically shielded room to reduce the environmental magnetic field. The size of the sample was ϕ35 mm × L80 mm. After applying a polarizing field and a 90°pulse, an NMR signal was detected by the SQUID through the flux transformer. As a result, the NMR spectra of fat samples were obtained at 2.0 kHz corresponding to the measurement field Bm of 47 μT. The T1 relaxation time of the mineral oil measured in Bm was 45 ms. These results suggested that the ULF-NMR/MRI system has potential for food inspection.

  12. Ultra-low-noise transition edge sensors for the SAFARI L-band on SPICA

    Science.gov (United States)

    Goldie, D. J.; Gao, J. R.; Glowacka, D. M.; Griffin, D. K.; Hijmering, R.; Khosropanah, P.; Jackson, B. D.; Mauskopf, P. D.; Morozov, D.; Murphy, J. A.; Ridder, M.; Trappe, N.; O'Sullivan, C.; Withington, S.

    2012-09-01

    The Far-Infrared Fourier transform spectrometer instrument SAFARI-SPICA which will operate with cooled optics in a low-background space environment requires ultra-sensitive detector arrays with high optical coupling efficiencies over extremely wide bandwidths. In earlier papers we described the design, fabrication and performance of ultra-low-noise Transition Edge Sensors (TESs) operated close to 100mk having dark Noise Equivalent Powers (NEPs) of order 4 × 10-19W/√Hz close to the phonon noise limit and an improvement of two orders of magnitude over TESs for ground-based applications. Here we describe the design, fabrication and testing of 388-element arrays of MoAu TESs integrated with far-infrared absorbers and optical coupling structures in a geometry appropriate for the SAFARI L-band (110 - 210 μm). The measured performance shows intrinsic response time τ ~ 11ms and saturation powers of order 10 fW, and a dark noise equivalent powers of order 7 × 10-19W/√Hz. The 100 × 100μm2 MoAu TESs have transition temperatures of order 110mK and are coupled to 320×320μm2 thin-film β-phase Ta absorbers to provide impedance matching to the incoming fields. We describe results of dark tests (i.e without optical power) to determine intrinsic pixel characteristics and their uniformity, and measurements of the optical performance of representative pixels operated with flat back-shorts coupled to pyramidal horn arrays. The measured and modeled optical efficiency is dominated by the 95Ω sheet resistance of the Ta absorbers, indicating a clear route to achieve the required performance in these ultra-sensitive detectors.

  13. Possible operation of the European XFEL with ultra-low emittance beams

    International Nuclear Information System (INIS)

    Brinkmann, R.; Schneidmiller, E.A.; Yurkov, M.V.

    2010-01-01

    Recent successful lasing of the Linac Coherent Light Source (LCLS) in the hard x-ray regime and the experimental demonstration of a possibility to produce low-charge bunches with ultra-small normalized emittance have lead to the discussions on optimistic scenarios of operation of the European XFEL. In this paper we consider new options that make use of low-emittance beams, a relatively high beam energy, tunable-gap undulators, and a multibunch capability of this facility. We study the possibility of operation of a spontaneous radiator (combining two of them, U1 and U2, in one beamline) in the SASE mode in the designed photon energy range 20-90 keV and show that it becomes possible with ultra-low emittance electron beams similar to those generated in LCLS. As an additional attractive option we consider the generation of powerful soft X-ray and VUV radiation by the same electron bunch for pump-probe experiments, making use of recently invented compact afterburner scheme. We also propose a betatron switcher as a simple, cheap, and robust solution for multi-color operation of SASE1 and SASE2 undulators, allowing to generate 2 to 5 X-ray beams of different independent colors from each of these undulators for simultaneous multi-user operation. We describe a scheme for pump-probe experiments, based on a production of two different colors by two closely spaced electron bunches (produced in photoinjector) with the help of a very fast betatron switcher. Finally, we discuss how without significant modifications of the layout the European XFEL can become a unique facility that continuously covers with powerful, coherent radiation a part of the electromagnetic spectrum from far infrared to gamma-rays. (orig.)

  14. Ultra-low level plutonium isotopes in the NIST SRM 4355A (Peruvian Soil-1)

    International Nuclear Information System (INIS)

    Inn, Kenneth G.W.; LaRosa, Jerome; Nour, Svetlana; Brooks, George; LaMont, Steve; Steiner, Rob; Williams, Ross; Patton, Brad; Bostick, Debbie; Eiden, Gregory; Petersen, Steve; Douglas, Matthew; Beals, Donna; Cadieux, James; Hall, Greg; Goldberg, Steve; Vogt, Stephan

    2009-01-01

    For more than 20 years, countries and their agencies which monitor radionuclide discharge sites and storage facilities have relied on the National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 4355 Peruvian Soil. Its low fallout contamination makes it an ideal soil blank for measurements associated with terrestrial-pathway-to-man studies. Presently, SRM 4355 is out of stock, and a new batch of the Peruvian soil is currently under development as future NIST SRM 4355A. Both environmental radioanalytical laboratories and mass spectrometry communities will benefit from the use of this SRM. The former must assess their laboratory procedural contamination and measurement detection limits by measurement of blank sample material. The Peruvian Soil is so low in anthropogenic radionuclide content that it is a suitable virtual blank. On the other hand, mass spectrometric laboratories have high sensitivity instruments that are capable of quantitative isotopic measurements at low plutonium levels in the SRM 4355 (first Peruvian Soil SRM) that provided the mass spectrometric community with the calibration, quality control, and testing material needed for methods development and legal defensibility. The quantification of the ultra-low plutonium content in the SRM 4355A was a considerable challenge for the mass spectrometric laboratories. Careful blank control and correction, isobaric interferences, instrument stability, peak assessment, and detection assessment were necessary. Furthermore, a systematic statistical evaluation of the measurement results and considerable discussions with the mass spectroscopy metrologists were needed to derive the certified values and uncertainties. The one sided upper limit of the 95% tolerance with 95% confidence for the massic 239 Pu content in SRM 4355A is estimated to be 54,000 atoms/g.

  15. Terrestrial gamma radiation baseline mapping using ultra low density sampling methods.

    Science.gov (United States)

    Kleinschmidt, R; Watson, D

    2016-01-01

    Baseline terrestrial gamma radiation maps are indispensable for providing basic reference information that may be used in assessing the impact of a radiation related incident, performing epidemiological studies, remediating land contaminated with radioactive materials, assessment of land use applications and resource prospectivity. For a large land mass, such as Queensland, Australia (over 1.7 million km(2)), it is prohibitively expensive and practically difficult to undertake detailed in-situ radiometric surveys of this scale. It is proposed that an existing, ultra-low density sampling program already undertaken for the purpose of a nationwide soil survey project be utilised to develop a baseline terrestrial gamma radiation map. Geoelement data derived from the National Geochemistry Survey of Australia (NGSA) was used to construct a baseline terrestrial gamma air kerma rate map, delineated by major drainage catchments, for Queensland. Three drainage catchments (sampled at the catchment outlet) spanning low, medium and high radioelement concentrations were selected for validation of the methodology using radiometric techniques including in-situ measurements and soil sampling for high resolution gamma spectrometry, and comparative non-radiometric analysis. A Queensland mean terrestrial air kerma rate, as calculated from the NGSA outlet sediment uranium, thorium and potassium concentrations, of 49 ± 69 nGy h(-1) (n = 311, 3σ 99% confidence level) is proposed as being suitable for use as a generic terrestrial air kerma rate background range. Validation results indicate that catchment outlet measurements are representative of the range of results obtained across the catchment and that the NGSA geoelement data is suitable for calculation and mapping of terrestrial air kerma rate. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

  16. An ion beam deceleration lens for ultra-low-energy ion bombardment of naked DNA

    Energy Technology Data Exchange (ETDEWEB)

    Thopan, P.; Prakrajang, K. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thongkumkoon, P. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Suwannakachorn, D. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Yu, L.D., E-mail: yuldyuld@gmail.com [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand)

    2013-07-15

    Highlights: ► An ion beam deceleration lens was designed and constructed. ► The deceleration lens was installed and tested. ► The decelerated ion beam energy was measured using an electrical field. ► Decelerated ultra-low-energy ion beam bombarded naked DNA. ► Ion beam with energy of a few tens of eV could break DNA strands. -- Abstract: Study of low-energy ion bombardment effect on biological living materials is of significance. High-energy ion beam irradiation of biological materials such as organs and cells has no doubt biological effects. However, ion energy deposition in the ion-bombarded materials dominantly occurs in the low-energy range. To investigate effects from very-low-energy ion bombardment on biological materials, an ion beam deceleration lens is necessary for uniform ion energy lower than keV. A deceleration lens was designed and constructed based on study of the beam optics using the SIMION program. The lens consisted of six electrodes, able to focus and decelerate primary ion beam, with the last one being a long tube to obtain a parallel uniform exiting beam. The deceleration lens was installed to our 30-kV bioengineering-specialized ion beam line. The final decelerated-ion energy was measured using a simple electrostatic field to bend the beam to range from 10 eV to 1 keV controlled by the lens parameters and the primary beam condition. In a preliminary test, nitrogen ion beam at 60 eV decelerated from a primary 20-keV beam bombarded naked plasmid DNA. The original DNA supercoiled form was found to change to relaxed and linear forms, indicating single or double strand breaks. The study demonstrated that the ion bombardment with energy as low as several-tens eV was possible to break DNA strands and thus potential to cause genetic modification of biological cells.

  17. Ultra-low dose CT attenuation correction for PET/CT

    Science.gov (United States)

    Xia, Ting; Alessio, Adam M.; De Man, Bruno; Manjeshwar, Ravindra; Asma, Evren; Kinahan, Paul E.

    2012-01-01

    A challenge for PET/CT quantitation is patient respiratory motion, which can cause an underestimation of lesion activity uptake and an overestimation of lesion volume. Several respiratory motion correction methods benefit from longer duration CT scans that are phase matched with PET scans. However, even with the currently-available, lowest dose CT techniques, extended duration CINE CT scans impart a substantially high radiation dose. This study evaluates methods designed to reduce CT radiation dose in PET/CT scanning. Methods We investigated selected combinations of dose reduced acquisition and noise suppression methods that take advantage of the reduced requirement of CT for PET attenuation correction (AC). These include reducing CT tube current, optimizing CT tube voltage, adding filtration, CT sinogram smoothing and clipping. We explored the impact of these methods on PET quantitation via simulations on different digital phantoms. Results CT tube current can be reduced much lower for AC than that in low dose CT protocols. Spectra that are higher energy and narrower are generally more dose efficient with respect to PET image quality. Sinogram smoothing could be used to compensate for the increased noise and artifacts at radiation dose reduced CT images, which allows for a further reduction of CT dose with no penalty for PET image quantitation. Conclusion When CT is not used for diagnostic and anatomical localization purposes, we showed that ultra-low dose CT for PET/CT is feasible. The significant dose reduction strategies proposed here could enable respiratory motion compensation methods that require extended duration CT scans and reduce radiation exposure in general for all PET/CT imaging. PMID:22156174

  18. An ion beam deceleration lens for ultra-low-energy ion bombardment of naked DNA

    International Nuclear Information System (INIS)

    Thopan, P.; Prakrajang, K.; Thongkumkoon, P.; Suwannakachorn, D.; Yu, L.D.

    2013-01-01

    Highlights: ► An ion beam deceleration lens was designed and constructed. ► The deceleration lens was installed and tested. ► The decelerated ion beam energy was measured using an electrical field. ► Decelerated ultra-low-energy ion beam bombarded naked DNA. ► Ion beam with energy of a few tens of eV could break DNA strands. -- Abstract: Study of low-energy ion bombardment effect on biological living materials is of significance. High-energy ion beam irradiation of biological materials such as organs and cells has no doubt biological effects. However, ion energy deposition in the ion-bombarded materials dominantly occurs in the low-energy range. To investigate effects from very-low-energy ion bombardment on biological materials, an ion beam deceleration lens is necessary for uniform ion energy lower than keV. A deceleration lens was designed and constructed based on study of the beam optics using the SIMION program. The lens consisted of six electrodes, able to focus and decelerate primary ion beam, with the last one being a long tube to obtain a parallel uniform exiting beam. The deceleration lens was installed to our 30-kV bioengineering-specialized ion beam line. The final decelerated-ion energy was measured using a simple electrostatic field to bend the beam to range from 10 eV to 1 keV controlled by the lens parameters and the primary beam condition. In a preliminary test, nitrogen ion beam at 60 eV decelerated from a primary 20-keV beam bombarded naked plasmid DNA. The original DNA supercoiled form was found to change to relaxed and linear forms, indicating single or double strand breaks. The study demonstrated that the ion bombardment with energy as low as several-tens eV was possible to break DNA strands and thus potential to cause genetic modification of biological cells

  19. Bystander Exposure to Ultra-Low-Volume Insecticide Applications Used for Adult Mosquito Management

    Directory of Open Access Journals (Sweden)

    Robert K.D. Peterson

    2011-06-01

    Full Text Available A popular and effective management option for adult mosquitoes is the use of insecticides applied by ultra-low-volume (ULV equipment. However, there is a paucity of data on human dermal exposure to insecticides applied by this method. The objective of the current study was to estimate dermal exposures to the insecticide active ingredient permethrin using water- (Aqua-Reslin® and oil-based (Permanone® 30-30 formulations with passive dosimetry. No significant differences in deposition of permethrin were observed between years, distance from the spray source, front or back of the body, or the placement of the patches on the body. However, exposure to Aqua-Reslin was significantly greater than Permanone 30-30 and average concentrations deposited on the body were 4.2 and 2.1 ng/cm2, respectively. The greater deposition of Aqua-Reslin is most likely due to the higher density of the water-based formulation which causes it to settle out faster than the lighter oil-based formulation of Permanone 30-30. The estimated average absorbed dermal exposure for permethrin from Aqua-Reslin and Permanone 30-30 was 0.00009 and 0.00005 mg/kg body weight, respectively. We also found that ground deposition of ULV insecticides can be used as a surrogate for estimating dermal exposure. The estimated exposures support the findings of previous risk assessments that exposure to ULV applications used for mosquito management are below regulatory levels of concern.

  20. Construction and Evaluation of an Ultra Low Latency Frameless Renderer for VR.

    Science.gov (United States)

    Friston, Sebastian; Steed, Anthony; Tilbury, Simon; Gaydadjiev, Georgi

    2016-04-01

    Latency - the delay between a user's action and the response to this action - is known to be detrimental to virtual reality. Latency is typically considered to be a discrete value characterising a delay, constant in time and space - but this characterisation is incomplete. Latency changes across the display during scan-out, and how it does so is dependent on the rendering approach used. In this study, we present an ultra-low latency real-time ray-casting renderer for virtual reality, implemented on an FPGA. Our renderer has a latency of ~1 ms from 'tracker to pixel'. Its frameless nature means that the region of the display with the lowest latency immediately follows the scan-beam. This is in contrast to frame-based systems such as those using typical GPUs, for which the latency increases as scan-out proceeds. Using a series of high and low speed videos of our system in use, we confirm its latency of ~1 ms. We examine how the renderer performs when driving a traditional sequential scan-out display on a readily available HMO, the Oculus Rift OK2. We contrast this with an equivalent apparatus built using a GPU. Using captured human head motion and a set of image quality measures, we assess the ability of these systems to faithfully recreate the stimuli of an ideal virtual reality system - one with a zero latency tracker, renderer and display running at 1 kHz. Finally, we examine the results of these quality measures, and how each rendering approach is affected by velocity of movement and display persistence. We find that our system, with a lower average latency, can more faithfully draw what the ideal virtual reality system would. Further, we find that with low display persistence, the sensitivity to velocity of both systems is lowered, but that it is much lower for ours.

  1. Ultra-low dose of Mycobacterium tuberculosis aerosol creates partial infection in mice.

    Science.gov (United States)

    Saini, Divey; Hopkins, Gregory W; Seay, Sarah A; Chen, Ching-Ju; Perley, Casey C; Click, Eva M; Frothingham, Richard

    2012-03-01

    A murine low dose (LD) aerosol model is commonly used to test tuberculosis vaccines. Doses of 50-400 CFU (24h lung CFU) infect 100% of exposed mice. The LD model measures progression from infection to disease based on organ CFU at defined time points. To mimic natural exposure, we exposed mice to an ultra-low dose (ULD) aerosol. We estimated the presented dose by sampling the aerosol. Female C57BL/6 mice were exposed to Mycobacterium tuberculosis H37Rv aerosol at 1.0, 1.1, 1.6, 5.4, and 11 CFU presented dose, infecting 27%, 36%, 36%, 100%, and 95% of mice, respectively. These data are compatible with a stochastic infection event (Poisson distribution, weighted R(2)=0.97) or with a dose-response relationship (sigmoid distribution, weighted R(2)=0.97). Based on the later assumption, the ID50 was 1.6CFU presented dose (95% confidence interval, 1.2-2.1). We compared organ CFU after ULD and LD aerosols (5.4 vs. 395CFU presented dose). Lung burden was 30-fold lower in the ULD model at 4 weeks (3.4 vs. 4.8 logs, pLD aerosols had greater within-group CFU variability. Exposure to ULD aerosols leads to infection in a subset of mice, and to persistently low organ CFU. The ULD aerosol model may resemble human pulmonary tuberculosis more closely than the standard LD model, and may be used to identify host or bacterial factors that modulate the initial infection event. Copyright © 2011 Elsevier Ltd. All rights reserved.

  2. Gamma-ray spectrometry of ultra low levels of radioactivity within the material screening program for the GERDA experiment.

    Science.gov (United States)

    Budjás, D; Gangapshev, A M; Gasparro, J; Hampel, W; Heisel, M; Heusser, G; Hult, M; Klimenko, A A; Kuzminov, V V; Laubenstein, M; Maneschg, W; Simgen, H; Smolnikov, A A; Tomei, C; Vasiliev, S I

    2009-05-01

    In present and future experiments in the field of rare events physics a background index of 10(-3) counts/(keV kg a) or better in the region of interest is envisaged. A thorough material screening is mandatory in order to achieve this goal. The results of a systematic study of radioactive trace impurities in selected materials using ultra low-level gamma-ray spectrometry in the framework of the GERDA experiment are reported.

  3. Sensitivity of LDEF foil analyses using ultra-low background germanium vs. large NaI(Tl) multidimensional spectrometers

    International Nuclear Information System (INIS)

    Reeves, J.H.; Arthur, R.J.; Brodzinski, R.L.

    1992-06-01

    Cobalt foils and stainless steel samples were analyzed for induced 6O Co activity with both an ultra-low background germanium gamma-ray spectrometer and with a large NaI(Tl) multidimensional spectrometer, both of which use electronic anticoincidence shielding to reduce background counts resulting from cosmic rays. Aluminum samples were analyzed for 22 Na. The results, in addition to the relative sensitivities and precisions afforded by the two methods, are presented

  4. An Analog Circuit Approximation of the Discrete Wavelet Transform for Ultra Low Power Signal Processing in Wearable Sensor Nodes

    OpenAIRE

    Casson, Alexander J.

    2015-01-01

    Ultra low power signal processing is an essential part of all sensor nodes, and particularly so in emerging wearable sensors for biomedical applications. Analog signal processing has an important role in these low power, low voltage, low frequency applications, and there is a key drive to decrease the power consumption of existing analog domain signal processing and to map more signal processing approaches into the analog domain. This paper presents an analog domain signal processing circuit ...

  5. Single-mode optical fiber design with wide-band ultra low bending-loss for FTTH application.

    Science.gov (United States)

    Watekar, Pramod R; Ju, Seongmin; Han, Won-Taek

    2008-01-21

    We propose a new design of a single-mode optical fiber (SMF) which exhibits ultra low bend sensitivity over a wide communication band (1.3 microm to 1.65 microm). A five-cladding fiber structure has been proposed to minimize the bending loss, estimated to be as low as 4.4x10(-10) dB/turn for the bend radius of 10 mm.

  6. Prevention of burn-on defect on surface of hydroturbine blade casting of ultra-low-carbon refining stainless steel

    Directory of Open Access Journals (Sweden)

    Li Ling

    2008-08-01

    Full Text Available The burn-on sand is common surface defect encountered in CO2-cured silicate-bonded sand casting of hydroturbine blade of ultra-low-carbon martensitic stainless steel, its feature, causes and prevention measures are presented in this paper. Experiments showed that the burn-on defect is caused by oxidization of chromium in the molten steel at high temperature and can be effectively eliminated by using chromium-corundum coating.

  7. Nanocrystals manufacturing by ultra-low-energy ion-beam-synthesis for non-volatile memory applications

    Energy Technology Data Exchange (ETDEWEB)

    Normand, P. E-mail: p.normand@imel.demokritos.gr; Kapetanakis, E.; Dimitrakis, P.; Skarlatos, D.; Beltsios, K.; Tsoukalas, D.; Bonafos, C.; Ben Assayag, G.; Cherkashin, N.; Claverie, A.; Berg, J.A. van den; Soncini, V.; Agarwal, A.; Ameen, M.; Perego, M.; Fanciulli, M

    2004-02-01

    An overview of recent developments regarding the fabrication and structure of thin silicon dioxide films with embedded nanocrystals through ultra-low-energy ion-beam-synthesis (ULE-IBS) is presented. Advances in fabrication, increased understanding of structure formation processes and ways to control them allow for the fabrication of reproducible and attractive silicon-nanocrystal memory devices for a wide-range of memory applications as herein demonstrated in the case of low-voltage EEPROM-like applications.

  8. Nanocrystals manufacturing by ultra-low-energy ion-beam-synthesis for non-volatile memory applications

    International Nuclear Information System (INIS)

    Normand, P.; Kapetanakis, E.; Dimitrakis, P.; Skarlatos, D.; Beltsios, K.; Tsoukalas, D.; Bonafos, C.; Ben Assayag, G.; Cherkashin, N.; Claverie, A.; Berg, J.A. van den; Soncini, V.; Agarwal, A.; Ameen, M.; Perego, M.; Fanciulli, M.

    2004-01-01

    An overview of recent developments regarding the fabrication and structure of thin silicon dioxide films with embedded nanocrystals through ultra-low-energy ion-beam-synthesis (ULE-IBS) is presented. Advances in fabrication, increased understanding of structure formation processes and ways to control them allow for the fabrication of reproducible and attractive silicon-nanocrystal memory devices for a wide-range of memory applications as herein demonstrated in the case of low-voltage EEPROM-like applications

  9. Performance of room temperature mercuric iodide (HgI2) detectors in the ultra low energy x-ray region

    International Nuclear Information System (INIS)

    Dabrowski, A.J.; Iwanczyk, J.S.; Barton, J.B.; Huth, G.C.; Whited, R.; Ortale, C.; Economou, T.E.; Turkevich, A.L.

    1980-01-01

    Performance of room temperature mercuric iodide x-ray spectrometers has been recently improved through new fabrication techniques and further development of low noise associated electronic systems. This progress has extended the range of measurements to the ultra low energy x-ray region at room temperature. This paper reports the study of the effect of contact material on the performance of HgI 2 detectors in the low energy x-ray region

  10. Rotatable Small Permanent Magnet Array for Ultra-Low Field Nuclear Magnetic Resonance Instrumentation: A Concept Study.

    Science.gov (United States)

    Vogel, Michael W; Giorni, Andrea; Vegh, Viktor; Pellicer-Guridi, Ruben; Reutens, David C

    2016-01-01

    We studied the feasibility of generating the variable magnetic fields required for ultra-low field nuclear magnetic resonance relaxometry with dynamically adjustable permanent magnets. Our motivation was to substitute traditional electromagnets by distributed permanent magnets, increasing system portability. The finite element method (COMSOL®) was employed for the numerical study of a small permanent magnet array to calculate achievable magnetic field strength, homogeneity, switching time and magnetic forces. A manually operated prototype was simulated and constructed to validate the numerical approach and to verify the generated magnetic field. A concentric small permanent magnet array can be used to generate strong sample pre-polarisation and variable measurement fields for ultra-low field relaxometry via simple prescribed magnet rotations. Using the array, it is possible to achieve a pre-polarisation field strength above 100 mT and variable measurement fields ranging from 20-50 μT with 200 ppm absolute field homogeneity within a field-of-view of 5 x 5 x 5 cubic centimetres. A dynamic small permanent magnet array can generate multiple highly homogeneous magnetic fields required in ultra-low field nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) instruments. This design can significantly reduce the volume and energy requirements of traditional systems based on electromagnets, improving portability considerably.

  11. An ultra-low power output capacitor-less low-dropout regulator with slew-rate-enhanced circuit

    Science.gov (United States)

    Cheng, Xin; Zhang, Yu; Xie, Guangjun; Yang, Yizhong; Zhang, Zhang

    2018-03-01

    An ultra-low power output-capacitorless low-dropout (LDO) regulator with a slew-rate-enhanced (SRE) circuit is introduced. The increased slew rate is achieved by sensing the transient output voltage of the LDO and then charging (or discharging) the gate capacitor quickly. In addition, a buffer with ultra-low output impedance is presented to improve line and load regulations. This design is fabricated by SMIC 0.18 μm CMOS technology. Experimental results show that, the proposed LDO regulator only consumes an ultra-low quiescent current of 1.2 μA. The output current range is from 10 μA to 200 mA and the corresponding variation of output voltage is less than 40 mV. Moreover, the measured line regulation and load regulation are 15.38 mV/V and 0.4 mV/mA respectively. Project supported by the National Natural Science Foundation of China (Nos. 61401137, 61404043, 61674049).

  12. CORK Study in Cystic Fibrosis: Sustained Improvements in Ultra-Low-Dose Chest CT Scores After CFTR Modulation With Ivacaftor.

    Science.gov (United States)

    Ronan, Nicola J; Einarsson, Gisli G; Twomey, Maria; Mooney, Denver; Mullane, David; NiChroinin, Muireann; O'Callaghan, Grace; Shanahan, Fergus; Murphy, Desmond M; O'Connor, Owen J; Shortt, Cathy A; Tunney, Michael M; Eustace, Joseph A; Maher, Michael M; Elborn, J Stuart; Plant, Barry J

    2018-02-01

    Ivacaftor produces significant clinical benefit in patients with cystic fibrosis (CF) with the G551D mutation. Prevalence of this mutation at the Cork CF Centre is 23%. This study assessed the impact of cystic fibrosis transmembrane conductance regulator modulation on multiple modalities of patient assessment. Thirty-three patients with the G551D mutation were assessed at baseline and prospectively every 3 months for 1 year after initiation of ivacaftor. Change in ultra-low-dose chest CT scans, blood inflammatory mediators, and the sputum microbiome were assessed. Significant improvements in FEV 1 , BMI, and sweat chloride levels were observed post-ivacaftor treatment. Improvement in ultra-low-dose CT imaging scores were observed after treatment, with significant mean reductions in total Bhalla score (P < .01), peribronchial thickening (P = .035), and extent of mucous plugging (P < .001). Reductions in circulating inflammatory markers, including interleukin (IL)-1β, IL-6, and IL-8 were demonstrated. There was a 30% reduction in the relative abundance of Pseudomonas species and an increase in the relative abundance of bacteria associated with more stable community structures. Posttreatment community richness increased significantly (P = .03). Early and sustained improvements on ultra-low-dose CT scores suggest it may be a useful method of evaluating treatment response. It paralleled improvement in symptoms, circulating inflammatory markers, and changes in the lung microbiota. Copyright © 2017 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

  13. Ultra-low-density genotype panels for breed assignment of Angus and Hereford cattle.

    Science.gov (United States)

    Judge, M M; Kelleher, M M; Kearney, J F; Sleator, R D; Berry, D P

    2017-06-01

    Angus and Hereford beef is marketed internationally for apparent superior meat quality attributes; DNA-based breed authenticity could be a useful instrument to ensure consumer confidence on premium meat products. The objective of this study was to develop an ultra-low-density genotype panel to accurately quantify the Angus and Hereford breed proportion in biological samples. Medium-density genotypes (13 306 single nucleotide polymorphisms (SNPs)) were available on 54 703 commercial and 4042 purebred animals. The breed proportion of the commercial animals was generated from the medium-density genotypes and this estimate was regarded as the gold-standard breed composition. Ten genotype panels (100 to 1000 SNPs) were developed from the medium-density genotypes; five methods were used to identify the most informative SNPs and these included the Delta statistic, the fixation (F st) statistic and an index of both. Breed assignment analyses were undertaken for each breed, panel density and SNP selection method separately with a programme to infer population structure using the entire 13 306 SNP panel (representing the gold-standard measure). Breed assignment was undertaken for all commercial animals (n=54 703), animals deemed to contain some proportion of Angus based on pedigree (n=5740) and animals deemed to contain some proportion of Hereford based on pedigree (n=5187). The predicted breed proportion of all animals from the lower density panels was then compared with the gold-standard breed prediction. Panel density, SNP selection method and breed all had a significant effect on the correlation of predicted and actual breed proportion. Regardless of breed, the Index method of SNP selection numerically (but not significantly) outperformed all other selection methods in accuracy (i.e. correlation and root mean square of prediction) when panel density was ⩾300 SNPs. The correlation between actual and predicted breed proportion increased as panel density increased. Using

  14. Back End of Line Nanorelays for Ultra-low Power Monolithic Integrated NEMS-CMOS Circuits

    KAUST Repository

    Lechuga Aranda, Jesus Javier

    2016-05-01

    Since the introduction of Complementary-Metal-Oxide-Semiconductor (CMOS) technology, the chip industry has enjoyed many benefits of transistor feature size scaling, including higher speed and device density and improved energy efficiency. However, in the recent years, the IC designers have encountered a few roadblocks, namely reaching the physical limits of scaling and also increased device leakage which has resulted in a slow-down of supply voltage and power density scaling. Therefore, there has been an extensive hunt for alternative circuit architectures and switching devices that can alleviate or eliminate the current crisis in the semiconductor industry. The Nano-Electro-Mechanical (NEM) relay is a promising alternative switch that offers zero leakage and abrupt turn-on behaviour. Even though these devices are intrinsically slower than CMOS transistors, new circuit design techniques tailored for the electromechanical properties of such devices can be leveraged to design medium performance, ultra-low power integrated circuits. In this thesis, we deal with a new generation of such devices that is built in the back end of line (BEOL) CMOS process and is an ideal option for full integration with current CMOS transistor technology. Simulation and verification at the circuit and system level is a critical step in the design flow of microelectronic circuits, and this is especially important for new technologies that lack the standard design infrastructure and well-known verification platforms. Although most of the physical and electrical properties of NEM structures can be simulated using standard electronic automation software, there is no report of a reliable behavioural model for NEMS switches that enable large circuit simulations. In this work, we present an optimised model of a BEOL nano relay that encompasses all the electromechanical characteristics of the device and is robust and lightweight enough for VLSI applications that require simulation of thousands of

  15. Estimation of Cosmic Induced Contamination in Ultra-low Background Detector Materials

    Energy Technology Data Exchange (ETDEWEB)

    Aguayo Navarrete, Estanislao; Kouzes, Richard T.; Orrell, John L.; Berguson, Timothy J.; Greene, Austen T.

    2012-08-01

    Executive Summary This document presents the result of investigating a way to reliably determine cosmic induced backgrounds for ultra-low background materials. In particular, it focuses on those radioisotopes produced by the interactions with cosmic ray particles in the detector materials that act as a background for experiments looking for neutrinoless double beta decay. This investigation is motivated by the desire to determine background contributions from cosmic ray activation of the electroformed copper that is being used in the construction of the MAJORANA DEMONSTRATOR. The most important radioisotope produced in copper that contributes to the background budget is 60Co, which has the potential to deposit energy in the region of interest of this experiment. Cobalt-60 is produced via cosmic ray neutron collisions in the copper. This investigation aims to provide a method for determining whether or not the copper has been exposed to cosmic radiation beyond the threshold which the Majorana Project has established as the maximum exposure. This threshold is set by the Project as the expected contribution of this source of background to the overall background budget. One way to estimate cosmic ray neutron exposure of materials on the surface of the Earth is to relate it to the cosmic ray muon exposure. Muons are minimum-ionizing particles and the available technologies to detect muons are easier to implement than those to detect neutrons. We present the results of using a portable, ruggedized muon detector, the µ-Witness made by our research group, for determination of muon exposure of materials for the MAJORANA DEMONSTRATOR. From the muon flux measurement, this report presents a method to estimate equivalent sea-level exposure, and then infer the neutron exposure of the tracked material and thus the cosmogenic activation of the copper. This report combines measurements of the muon flux taken by the µ-Witness detector with Geant4 simulations in order to assure our

  16. Results of ultra-low level 71ge counting for application in the Gallex-solar neutrino experiment at the Gran Sasso Underground Physics Laboratory

    Science.gov (United States)

    Hampel, W.; Heusser, G.; Huebner, M.; Kiko, J.; Kirsten, T.; Schneider, K.; Schlotz, R.

    1985-01-01

    It has been experimentally verified that the Ultra-Low-Level Counting System for the Gallex solar neutrino experiment is capable of measuring the expected solar up silon-flux to plus or minus 12% during two years of operation.

  17. Effect of reservoir heterogeneity on air injection performance in a light oil reservoir

    Directory of Open Access Journals (Sweden)

    Hu Jia

    2018-03-01

    Full Text Available Air injection is a good option to development light oil reservoir. As well-known that, reservoir heterogeneity has great effect for various EOR processes. This also applies to air injection. However, oil recovery mechanisms and physical processes for air injection in heterogeneous reservoir with dip angle are still not well understood. The reported setting of reservoir heterogeneous for physical model or simulation model of air injection only simply uses different-layer permeability of porous media. In practice, reservoir heterogeneity follows the principle of geostatistics. How much of contrast in permeability actually challenges the air injection in light oil reservoir? This should be investigated by using layered porous medial settings of the classical Dykstra-Parsons style. Unfortunately, there has been no work addressing this issue for air injection in light oil reservoir. In this paper, Reservoir heterogeneity is quantified based on the use of different reservoir permeability distribution according to classical Dykstra-Parsons coefficients method. The aim of this work is to investigate the effect of reservoir heterogeneity on physical process and production performance of air injection in light oil reservoir through numerical reservoir simulation approach. The basic model is calibrated based on previous study. Total eleven pseudo compounders are included in this model and ten complexity of reactions are proposed to achieve the reaction scheme. Results show that oil recovery factor is decreased with the increasing of reservoir heterogeneity both for air and N2 injection from updip location, which is against the working behavior of air injection from updip location. Reservoir heterogeneity sometimes can act as positive effect to improve sweep efficiency as well as enhance production performance for air injection. High O2 content air injection can benefit oil recovery factor, also lead to early O2 breakthrough in heterogeneous reservoir. Well

  18. In situ quantification of ultra-low O2 concentrations in oxygen minimum zones

    DEFF Research Database (Denmark)

    Larsen, Morten; Lehner, Philipp; Borisov, Sergey M.

    2016-01-01

    based on the palladium(II)-benzoporphyrin luminophore, immobilized in a perfluorinated matrix with high O2 permeability. The trace sensor has a detection limit of ∼5 nmol L−1 with a dynamic range extending up to ∼2 μmol L−1. The sensor demonstrates a response time ..., and fully reversible response to hydrostatic pressure and temperature. The sensor showed excellent stability for continuously measurements during depth profiling in Oxygen Minimum Zones (OMZ). The novel sensor was deployed in situ using a Trace Oxygen Profiler instrument (TOP) equipped with two additional O...

  19. Effect of temperature on sandstone permeability

    DEFF Research Database (Denmark)

    Rosenbrand, Esther; Kjøller, Claus

    Hot water injection in geothermal sandstone aquifers is considered for seasonal energy storage in Denmark. However, an increase in the aquifer temperature might reduce permeability, and thereby increase production costs. An understanding of the factors that control permeability is required in order...... and the Klinkenberg procedure showed the expected correlation between the two measures, however, differences could be around one order of magnitude. In tight gas sandstones, permeability is often sensitive to net stress, which might change due to the pore pressure change in the Klinkenberg procedure. Besides...... affecting the Klinkenberg procedure, the combined effect of slip and changes in permeability would affect production during pressure depletion in tight gas sandstone reservoirs; therefore effects of gas slip and net stress on permeability were combined in a model based on the Klinkenberg equation. A lower...

  20. A 32 kb 9T near-threshold SRAM with enhanced read ability at ultra-low voltage operation

    Science.gov (United States)

    Kim, Tony Tae-Hyoung; Lee, Zhao Chuan; Do, Anh Tuan

    2018-01-01

    Ultra-low voltage SRAMs are highly sought-after in energy-limited systems such as battery-powered and self-harvested SoCs. However, ultra-low voltage operation diminishes SRAM read bitline (RBL) sensing margin significantly. This paper tackles this issue by presenting a novel 9T cell with data-independent RBL leakage in combination with an RBL boosting technique for enhancing the sensing margin. The proposed technique automatically tracks process, temperature and voltage (PVT) variations for robust sensing margin enhancement. A test chip fabricated in 65 nm CMOS technology shows that the proposed scheme significantly enlarges the sensing margin compared to the conventional bitline sensing scheme. It also achieves the minimum operating voltage of 0.18 V and the minimum energy consumption of 0.92 J/access at 0.4 V. He received 2016 International Low Power Design Contest Award from ISLPED, a best paper award at 2014 and 2011 ISOCC, 2008 AMD/CICC Student Scholarship Award, 2008 Departmental Research Fellowship from Univ. of Minnesota, 2008 DAC/ISSCC Student Design Contest Award, 2008, 2001, and 1999 Samsung Humantec Thesis Award and, 2005 ETRI Journal Paper of the Year Award. He is an author/co-author of +100 journal and conference papers and has 17 US and Korean patents registered. His current research interests include low power and high performance digital, mixed- mode, and memory circuit design, ultra-low voltage circuits and systems design, variation and aging tolerant circuits and systems, and circuit techniques for 3D ICs. He serves as an associate editor of IEEE Transactions on VLSI Systems. He is an IEEE senior member and the Chair of IEEE Solid-State Circuits Society Singapore Chapter. He has served numerous conferences as a committee member.

  1. Sensitivity of new detection method for ultra-low frequency gravitational waves with pulsar spin-down rate statistics

    Science.gov (United States)

    Yonemaru, Naoyuki; Kumamoto, Hiroki; Takahashi, Keitaro; Kuroyanagi, Sachiko

    2018-04-01

    A new detection method for ultra-low frequency gravitational waves (GWs) with a frequency much lower than the observational range of pulsar timing arrays (PTAs) was suggested in Yonemaru et al. (2016). In the PTA analysis, ultra-low frequency GWs (≲ 10-10 Hz) which evolve just linearly during the observation time span are absorbed by the pulsar spin-down rates since both have the same effect on the pulse arrival time. Therefore, such GWs cannot be detected by the conventional method of PTAs. However, the bias on the observed spin-down rates depends on relative direction of a pulsar and GW source and shows a quadrupole pattern in the sky. Thus, if we divide the pulsars according to the position in the sky and see the difference in the statistics of the spin-down rates, ultra-low frequency GWs from a single source can be detected. In this paper, we evaluate the potential of this method by Monte-Carlo simulations and estimate the sensitivity, considering only the "Earth term" while the "pulsar term" acts like random noise for GW frequencies 10-13 - 10-10 Hz. We find that with 3,000 milli-second pulsars, which are expected to be discovered by a future survey with the Square Kilometre Array, GWs with the derivative of amplitude of about 3 × 10^{-19} {s}^{-1} can in principle be detected. Implications for possible supermassive binary black holes in Sgr* and M87 are also given.

  2. Free induction decay MR signal measurements toward ultra-low field MRI with an optically pumped atomic magnetometer.

    Science.gov (United States)

    Oida, Takenori; Kobayashi, Tetsuo

    2013-01-01

    Ultra-low field magnetic resonance imaging (ULF-MRI) has attracted attention because of its low running costs and minimum patient exposure. An optically pumped atomic magnetometer (OPAM) is a magnetic sensor with high sensitivity in the low frequency range, which does not require a cryogenic cooling system. In an effort to develop a ULF-MRI, we attempted to measure the free induction decay MR signals with an OPAM. We successfully detected the MR signals by combining an OPAM and a flux transformer, demonstrating the feasibility of the proposed system.

  3. Fe-based nanocrystalline powder cores with ultra-low core loss

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiangyue, E-mail: wangxiangyue1986@163.com [China Iron and Steel Research Institute Group, Beijing 100081 (China); Center of Advanced Technology and Materials Co., Ltd., Beijing 100081 (China); Lu, Zhichao; Lu, Caowei; Li, Deren [China Iron and Steel Research Institute Group, Beijing 100081 (China); Center of Advanced Technology and Materials Co., Ltd., Beijing 100081 (China)

    2013-12-15

    Melt-spun amorphous Fe{sub 73.5}Cu{sub 1}Nb{sub 3}Si{sub 15.5}B{sub 7} alloy strip was crushed to make flake-shaped fine powders. The passivated powders by phosphoric acid were mixed with organic and inorganic binder, followed by cold compaction to form toroid-shaped bonded powder-metallurgical magnets. The powder cores were heat-treated to crystallize the amorphous structure and to control the nano-grain structure. Well-coated phosphate-oxide insulation layer on the powder surface decreased the the core loss with the insulation of each powder. FeCuNbSiB nanocrystalline alloy powder core prepared from the powder having phosphate-oxide layer exhibits a stable permeability up to high frequency range over 2 MHz. Especially, the core loss could be reduced remarkably. At the other hand, the softened inorganic binder in the annealing process could effectively improve the intensity of powder cores. - Highlights: • Fe-based nanocrystalline powder cores were prepared with low core loss. • Well-coated phosphate-oxide insulation layer on the powder surface decreased the core loss. • Fe-based nanocrystalline powder cores exhibited a stable permeability up to high frequency range over 2 MHz. • The softened inorganic binder in the annealing process could effectively improve the intensity of powder cores.

  4. Characterization and estimation of permeability correlation structure from performance data

    Energy Technology Data Exchange (ETDEWEB)

    Ershaghi, I.; Al-Qahtani, M. [Univ. of Southern California, Los Angeles, CA (United States)

    1997-08-01

    In this study, the influence of permeability structure and correlation length on the system effective permeability and recovery factors of 2-D cross-sectional reservoir models, under waterflood, is investigated. Reservoirs with identical statistical representation of permeability attributes are shown to exhibit different system effective permeability and production characteristics which can be expressed by a mean and variance. The mean and variance are shown to be significantly influenced by the correlation length. Detailed quantification of the influence of horizontal and vertical correlation lengths for different permeability distributions is presented. The effect of capillary pressure, P{sub c1} on the production characteristics and saturation profiles at different correlation lengths is also investigated. It is observed that neglecting P{sub c} causes considerable error at large horizontal and short vertical correlation lengths. The effect of using constant as opposed to variable relative permeability attributes is also investigated at different correlation lengths. Next we studied the influence of correlation anisotropy in 2-D reservoir models. For a reservoir under five-spot waterflood pattern, it is shown that the ratios of breakthrough times and recovery factors of the wells in each direction of correlation are greatly influenced by the degree of anisotropy. In fully developed fields, performance data can aid in the recognition of reservoir anisotropy. Finally, a procedure for estimating the spatial correlation length from performance data is presented. Both the production performance data and the system`s effective permeability are required in estimating the correlation length.

  5. Unconventional Tight Reservoirs Characterization with Nuclear Magnetic Resonance

    Science.gov (United States)

    Santiago, C. J. S.; Solatpour, R.; Kantzas, A.

    2017-12-01

    The increase in tight reservoir exploitation projects causes producing many papers each year on new, modern, and modified methods and techniques on estimating characteristics of these reservoirs. The most ambiguous of all basic reservoir property estimations deals with permeability. One of the logging methods that is advertised to predict permeability but is always met by skepticism is Nuclear Magnetic Resonance (NMR). The ability of NMR to differentiate between bound and movable fluids and providing porosity increased the capability of NMR as a permeability prediction technique. This leads to a multitude of publications and the motivation of a review paper on this subject by Babadagli et al. (2002). The first part of this presentation is dedicated to an extensive review of the existing correlation models for NMR based estimates of tight reservoir permeability to update this topic. On the second part, the collected literature information is used to analyze new experimental data. The data are collected from tight reservoirs from Canada, the Middle East, and China. A case study is created to apply NMR measurement in the prediction of reservoir characterization parameters such as porosity, permeability, cut-offs, irreducible saturations etc. Moreover, permeability correlations are utilized to predict permeability. NMR experiments were conducted on water saturated cores. NMR T2 relaxation times were measured. NMR porosity, the geometric mean relaxation time (T2gm), Irreducible Bulk Volume (BVI), and Movable Bulk Volume (BVM) were calculated. The correlation coefficients were computed based on multiple regression analysis. Results are cross plots of NMR permeability versus the independently measured Klinkenberg corrected permeability. More complicated equations are discussed. Error analysis of models is presented and compared. This presentation is beneficial in understanding existing tight reservoir permeability models. The results can be used as a guide for choosing

  6. Reservoir management

    International Nuclear Information System (INIS)

    Satter, A.; Varnon, J.E.; Hoang, M.T.

    1992-01-01

    A reservoir's life begins with exploration leading to discovery followed by delineation of the reservoir, development of the field, production by primary, secondary and tertiary means, and finally to abandonment. Sound reservoir management is the key to maximizing economic operation of the reservoir throughout its entire life. Technological advances and rapidly increasing computer power are providing tools to better manage reservoirs and are increasing the gap between good and neural reservoir management. The modern reservoir management process involves goal setting, planning, implementing, monitoring, evaluating, and revising plans. Setting a reservoir management strategy requires knowledge of the reservoir, availability of technology, and knowledge of the business, political, and environmental climate. Formulating a comprehensive management plan involves depletion and development strategies, data acquisition and analyses, geological and numerical model studies, production and reserves forecasts, facilities requirements, economic optimization, and management approval. This paper provides management, engineers, geologists, geophysicists, and field operations staff with a better understanding of the practical approach to reservoir management using a multidisciplinary, integrated team approach

  7. Reservoir management

    International Nuclear Information System (INIS)

    Satter, A.; Varnon, J.E.; Hoang, M.T.

    1992-01-01

    A reservoir's life begins with exploration leading to discovery followed by delineation of the reservoir, development of the field, production by primary, secondary and tertiary means, and finally to abandonment. Sound reservoir management is the key to maximizing economic operation of the reservoir throughout its entire life. Technological advances and rapidly increasing computer power are providing tools to better manage reservoirs and are increasing the gap between good and neutral reservoir management. The modern reservoir management process involves goal setting, planning, implementing, monitoring, evaluating, and revising plans. Setting a reservoir management strategy requires knowledge of the reservoir, availability of technology, and knowledge of the business, political, and environmental climate. Formulating a comprehensive management plan involves depletion and development strategies, data acquisition and analyses, geological and numerical model studies, production and reserves forecasts, facilities requirements, economic optimization, and management approval. This paper provides management, engineers geologists, geophysicists, and field operations staff with a better understanding of the practical approach to reservoir management using a multidisciplinary, integrated team approach

  8. A low-cost, ultra-fast and ultra-low noise preamplifier for silicon avalanche photodiodes

    Science.gov (United States)

    Gasmi, Khaled

    2018-02-01

    An ultra-fast and ultra-low noise preamplifier for amplifying the fast and weak electrical signals generated by silicon avalanche photodiodes has been designed and developed. It is characterized by its simplicity, compactness, reliability and low cost of construction. A very wide bandwidth of 300 MHz, a very good linearity from 1 kHz to 280 MHz, an ultra-low noise level at the input of only 1.7 nV Hz-1/2 and a very good stability are its key features. The compact size (70 mm  ×  90 mm) and light weight (45 g), as well as its excellent characteristics, make this preamplifier very competitive compared to any commercial preamplifier. The preamplifier, which is a main part of the detection system of a homemade laser remote sensing system, has been successfully tested. In addition, it is versatile and can be used in any optical detection system requiring high speed and very low noise electronics.

  9. Magnetic Random Access Memory based non-volatile asynchronous Muller cell for ultra-low power autonomous applications

    Science.gov (United States)

    Di Pendina, G.; Zianbetov, E.; Beigne, E.

    2015-05-01

    Micro and nano electronic integrated circuit domain is today mainly driven by the advent of the Internet of Things for which the constraints are strong, especially in terms of power consumption and autonomy, not only during the computing phases but also during the standby or idle phases. In such ultra-low power applications, the circuit has to meet new constraints mainly linked to its changing energetic environment: long idle phases, automatic wake up, data back-up when the circuit is sporadically turned off, and ultra-low voltage power supply operation. Such circuits have to be completely autonomous regarding their unstable environment, while remaining in an optimum energetic configuration. Therefore, we propose in this paper the first MRAM-based non-volatile asynchronous Muller cell. This cell has been simulated and characterized in a very advanced 28 nm CMOS fully depleted silicon-on-insulator technology, presenting good power performance results due to an extremely efficient body biasing control together with ultra-wide supply voltage range from 160 mV up to 920 mV. The leakage current can be reduced to 154 pA thanks to reverse body biasing. We also propose an efficient standard CMOS bulk version of this cell in order to be compatible with different fabrication processes.

  10. Magnetic Random Access Memory based non-volatile asynchronous Muller cell for ultra-low power autonomous applications

    Energy Technology Data Exchange (ETDEWEB)

    Di Pendina, G., E-mail: gregory.dipendina@cea.fr, E-mail: eldar.zianbetov@cea.fr, E-mail: edith.beigne@cea.fr; Zianbetov, E., E-mail: gregory.dipendina@cea.fr, E-mail: eldar.zianbetov@cea.fr, E-mail: edith.beigne@cea.fr [Univ. Grenoble Alpes, INAC-SPINTEC, F-38000 Grenoble (France); CNRS, SPINTEC, F-38000 Grenoble (France); CEA, INAC-SPINTEC, F-38000 Grenoble (France); Beigne, E., E-mail: gregory.dipendina@cea.fr, E-mail: eldar.zianbetov@cea.fr, E-mail: edith.beigne@cea.fr [Univ. Grenoble Alpes, CEA, LETI, F-38000 Grenoble (France)

    2015-05-07

    Micro and nano electronic integrated circuit domain is today mainly driven by the advent of the Internet of Things for which the constraints are strong, especially in terms of power consumption and autonomy, not only during the computing phases but also during the standby or idle phases. In such ultra-low power applications, the circuit has to meet new constraints mainly linked to its changing energetic environment: long idle phases, automatic wake up, data back-up when the circuit is sporadically turned off, and ultra-low voltage power supply operation. Such circuits have to be completely autonomous regarding their unstable environment, while remaining in an optimum energetic configuration. Therefore, we propose in this paper the first MRAM-based non-volatile asynchronous Muller cell. This cell has been simulated and characterized in a very advanced 28 nm CMOS fully depleted silicon-on-insulator technology, presenting good power performance results due to an extremely efficient body biasing control together with ultra-wide supply voltage range from 160 mV up to 920 mV. The leakage current can be reduced to 154 pA thanks to reverse body biasing. We also propose an efficient standard CMOS bulk version of this cell in order to be compatible with different fabrication processes.

  11. Non-invasive paper-based microfluidic device for ultra-low detection of urea through enzyme catalysis

    Science.gov (United States)

    Suresh, Vignesh; Qunya, Ong; Kanta, Bera Lakshmi; Yuh, Lee Yeong; Chong, Karen S. L.

    2018-03-01

    This work describes the design, fabrication and characterization of a paper-based microfluidic device for ultra-low detection of urea through enzyme catalysis. The microfluidic system comprises an entry port, a fluidic channel, a reaction zone and two electrodes (contacts). Wax printing was used to create fluidic channels on the surface of a chromatography paper. Pre-conceptualized designs of the fluidic channel are wax-printed on the paper substrate while the electrodes are screen-printed. The paper printed with wax is heated to cause the wax reflow along the thickness of the paper that selectively creates hydrophilic and hydrophobic zones inside the paper. Urease immobilized in the reaction zone catalyses urea into releasing ions and, thereby, generating a current flow between the electrodes. A measure of current with respect to time at a fixed potential enables the detection of urea. The methodology enabled urea concentration down to 1 pM to be detected. The significance of this work lies in the use of simple and inexpensive paper-based substrates to achieve detection of ultra-low concentrations of analytes such as urea. The process is non-invasive and employs a less cumbersome two-electrode assembly.

  12. An Analog Circuit Approximation of the Discrete Wavelet Transform for Ultra Low Power Signal Processing in Wearable Sensor Nodes.

    Science.gov (United States)

    Casson, Alexander J

    2015-12-17

    Ultra low power signal processing is an essential part of all sensor nodes, and particularly so in emerging wearable sensors for biomedical applications. Analog signal processing has an important role in these low power, low voltage, low frequency applications, and there is a key drive to decrease the power consumption of existing analog domain signal processing and to map more signal processing approaches into the analog domain. This paper presents an analog domain signal processing circuit which approximates the output of the Discrete Wavelet Transform (DWT) for use in ultra low power wearable sensors. Analog filters are used for the DWT filters and it is demonstrated how these generate analog domain DWT-like information that embeds information from Butterworth and Daubechies maximally flat mother wavelet responses. The Analog DWT is realised in hardware via g(m)C circuits, designed to operate from a 1.3 V coin cell battery, and provide DWT-like signal processing using under 115 nW of power when implemented in a 0.18 μm CMOS process. Practical examples demonstrate the effective use of the new Analog DWT on ECG (electrocardiogram) and EEG (electroencephalogram) signals recorded from humans.

  13. An Analog Circuit Approximation of the Discrete Wavelet Transform for Ultra Low Power Signal Processing in Wearable Sensor Nodes

    Directory of Open Access Journals (Sweden)

    Alexander J. Casson

    2015-12-01

    Full Text Available Ultra low power signal processing is an essential part of all sensor nodes, and particularly so in emerging wearable sensors for biomedical applications. Analog signal processing has an important role in these low power, low voltage, low frequency applications, and there is a key drive to decrease the power consumption of existing analog domain signal processing and to map more signal processing approaches into the analog domain. This paper presents an analog domain signal processing circuit which approximates the output of the Discrete Wavelet Transform (DWT for use in ultra low power wearable sensors. Analog filters are used for the DWT filters and it is demonstrated how these generate analog domain DWT-like information that embeds information from Butterworth and Daubechies maximally flat mother wavelet responses. The Analog DWT is realised in hardware via g m C circuits, designed to operate from a 1.3 V coin cell battery, and provide DWT-like signal processing using under 115 nW of power when implemented in a 0.18 μm CMOS process. Practical examples demonstrate the effective use of the new Analog DWT on ECG (electrocardiogram and EEG (electroencephalogram signals recorded from humans.

  14. Passive shimming of the fringe field of a superconducting magnet for ultra-low field hyperpolarized noble gas MRI.

    Science.gov (United States)

    Parra-Robles, Juan; Cross, Albert R; Santyr, Giles E

    2005-05-01

    Hyperpolarized noble gases (HNGs) provide exciting possibilities for MR imaging at ultra-low magnetic field strengths (superconductive magnets used in clinical MR imaging can provide a stable magnetic field for this purpose. In addition to offering the benefit of HNG MR imaging alongside conventional high field proton MRI, this approach offers the other useful advantage of providing different field strengths at different distances from the magnet. However, the extremely strong field gradients associated with the fringe field present a major challenge for imaging since impractically high active shim currents would be required to achieve the necessary homogeneity. In this work, a simple passive shimming method based on the placement of a small number of ferromagnetic pieces is proposed to reduce the fringe field inhomogeneities to a level that can be corrected using standard active shims. The method explicitly takes into account the strong variations of the field over the volume of the ferromagnetic pieces used to shim. The method is used to obtain spectra in the fringe field of a high-field (1.89 T) superconducting magnet from hyperpolarized 129Xe gas samples at two different ultra-low field strengths (8.5 and 17 mT). The linewidths of spectra measured from imaging phantoms (30 Hz) indicate a homogeneity sufficient for MRI of the rat lung.

  15. Ultra-low-dose CT imaging of the thorax: decreasing the radiation dose by one order of magnitude

    International Nuclear Information System (INIS)

    Lambert, Lukas; Banerjee, Rohan; Votruba, Jiri; El-Lababidi, Nabil; Zeman, Jiri

    2016-01-01

    Computed tomography (CT) is an indispensable tool for imaging of the thorax and there is virtually no alternative without associated radiation burden. The authors demonstrate ultra-low-dose CT of the thorax in three interesting cases. In an 18-y-old girl with rheumatoid arthritis, CT of the thorax identified alveolitis in the posterior costophrenic angles (radiation dose = 0.2 mSv). Its resolution was demonstrated on a follow-up scan (4.2 mSv) performed elsewhere. In an 11-y-old girl, CT (0.1 mSv) showed changes of the right collar bone consistent with chronic recurrent multifocal osteomyelitis. CT (0.1 mSv) of a 9-y-old girl with mucopolysaccharidosis revealed altogether three hamartomas, peribronchial infiltrate, and spine deformity. In some indications, the radiation dose from CT of the thorax can approach that of several plain radiographs. This may help the pediatrician in deciding whether 'gentle' ultra-low-dose CT instead of observation or follow-up radiographs will alleviate the uncertainty of the diagnosis with little harm to the child. (author)

  16. An Ultra-Low Power CMOS Image Sensor with On-Chip Energy Harvesting and Power Management Capability

    Directory of Open Access Journals (Sweden)

    Ismail Cevik

    2015-03-01

    Full Text Available An ultra-low power CMOS image sensor with on-chip energy harvesting and power management capability is introduced in this paper. The photodiode pixel array can not only capture images but also harvest solar energy. As such, the CMOS image sensor chip is able to switch between imaging and harvesting modes towards self-power operation. Moreover, an on-chip maximum power point tracking (MPPT-based power management system (PMS is designed for the dual-mode image sensor to further improve the energy efficiency. A new isolated P-well energy harvesting and imaging (EHI pixel with very high fill factor is introduced. Several ultra-low power design techniques such as reset and select boosting techniques have been utilized to maintain a wide pixel dynamic range. The chip was designed and fabricated in a 1.8 V, 1P6M 0.18 µm CMOS process. Total power consumption of the imager is 6.53 µW for a 96 × 96 pixel array with 1 V supply and 5 fps frame rate. Up to 30 μW of power could be generated by the new EHI pixels. The PMS is capable of providing 3× the power required during imaging mode with 50% efficiency allowing energy autonomous operation with a 72.5% duty cycle.

  17. Digital pulse-shape discrimination applied to an ultra-low-background gas-proportional counting system. First results

    International Nuclear Information System (INIS)

    Aalseth, C.E.; Day, A.R.; Fuller, E.S.; Hoppe, E.W.; Keillor, M.E.; Mace, E.K.; Myers, A.W.; Overman, C.T.; Panisko, M.E.; Seifert, A.

    2013-01-01

    A new ultra-low-background proportional counter design was recently developed at Pacific Northwest National Laboratory (PNNL). This design, along with an ultra-low-background counting system which provides passive and active shielding with radon exclusion, has been developed to complement a new shallow underground laboratory (∼30 m water-equivalent) constructed at PNNL. After these steps to mitigate dominant backgrounds (cosmic rays, external gamma-rays, radioactivity in materials), remaining background events do not exclusively arise from ionization of the proportional counter gas. Digital pulse-shape discrimination (PSD) is thus employed to further improve measurement sensitivity. In this work, a template shape is generated for each individual sample measurement of interest, a 'self-calibrating' template. Differences in event topology can also cause differences in pulse shape. In this work, the temporal region analyzed for each event is refined to maximize background discrimination while avoiding unwanted sensitivity to event topology. This digital PSD method is applied to sample and background data, and initial measurement results from a biofuel methane sample are presented in the context of low-background measurements currently being developed. (author)

  18. An ultra-low power CMOS image sensor with on-chip energy harvesting and power management capability.

    Science.gov (United States)

    Cevik, Ismail; Huang, Xiwei; Yu, Hao; Yan, Mei; Ay, Suat U

    2015-03-06

    An ultra-low power CMOS image sensor with on-chip energy harvesting and power management capability is introduced in this paper. The photodiode pixel array can not only capture images but also harvest solar energy. As such, the CMOS image sensor chip is able to switch between imaging and harvesting modes towards self-power operation. Moreover, an on-chip maximum power point tracking (MPPT)-based power management system (PMS) is designed for the dual-mode image sensor to further improve the energy efficiency. A new isolated P-well energy harvesting and imaging (EHI) pixel with very high fill factor is introduced. Several ultra-low power design techniques such as reset and select boosting techniques have been utilized to maintain a wide pixel dynamic range. The chip was designed and fabricated in a 1.8 V, 1P6M 0.18 µm CMOS process. Total power consumption of the imager is 6.53 µW for a 96 × 96 pixel array with 1 V supply and 5 fps frame rate. Up to 30 μW of power could be generated by the new EHI pixels. The PMS is capable of providing 3× the power required during imaging mode with 50% efficiency allowing energy autonomous operation with a 72.5% duty cycle.

  19. Magnetic Random Access Memory based non-volatile asynchronous Muller cell for ultra-low power autonomous applications

    International Nuclear Information System (INIS)

    Di Pendina, G.; Zianbetov, E.; Beigne, E.

    2015-01-01

    Micro and nano electronic integrated circuit domain is today mainly driven by the advent of the Internet of Things for which the constraints are strong, especially in terms of power consumption and autonomy, not only during the computing phases but also during the standby or idle phases. In such ultra-low power applications, the circuit has to meet new constraints mainly linked to its changing energetic environment: long idle phases, automatic wake up, data back-up when the circuit is sporadically turned off, and ultra-low voltage power supply operation. Such circuits have to be completely autonomous regarding their unstable environment, while remaining in an optimum energetic configuration. Therefore, we propose in this paper the first MRAM-based non-volatile asynchronous Muller cell. This cell has been simulated and characterized in a very advanced 28 nm CMOS fully depleted silicon-on-insulator technology, presenting good power performance results due to an extremely efficient body biasing control together with ultra-wide supply voltage range from 160 mV up to 920 mV. The leakage current can be reduced to 154 pA thanks to reverse body biasing. We also propose an efficient standard CMOS bulk version of this cell in order to be compatible with different fabrication processes

  20. Ultra-low dose CT attenuation correction for PET/CT: analysis of sparse view data acquisition and reconstruction algorithms

    Science.gov (United States)

    Rui, Xue; Cheng, Lishui; Long, Yong; Fu, Lin; Alessio, Adam M.; Asma, Evren; Kinahan, Paul E.; De Man, Bruno

    2015-01-01

    For PET/CT systems, PET image reconstruction requires corresponding CT images for anatomical localization and attenuation correction. In the case of PET respiratory gating, multiple gated CT scans can offer phase-matched attenuation and motion correction, at the expense of increased radiation dose. We aim to minimize the dose of the CT scan, while preserving adequate image quality for the purpose of PET attenuation correction by introducing sparse view CT data acquisition. Methods We investigated sparse view CT acquisition protocols resulting in ultra-low dose CT scans designed for PET attenuation correction. We analyzed the tradeoffs between the number of views and the integrated tube current per view for a given dose using CT and PET simulations of a 3D NCAT phantom with lesions inserted into liver and lung. We simulated seven CT acquisition protocols with {984, 328, 123, 41, 24, 12, 8} views per rotation at a gantry speed of 0.35 seconds. One standard dose and four ultra-low dose levels, namely, 0.35 mAs, 0.175 mAs, 0.0875 mAs, and 0.04375 mAs, were investigated. Both the analytical FDK algorithm and the Model Based Iterative Reconstruction (MBIR) algorithm were used for CT image reconstruction. We also evaluated the impact of sinogram interpolation to estimate the missing projection measurements due to sparse view data acquisition. For MBIR, we used a penalized weighted least squares (PWLS) cost function with an approximate total-variation (TV) regularizing penalty function. We compared a tube pulsing mode and a continuous exposure mode for sparse view data acquisition. Global PET ensemble root-mean-squares-error (RMSE) and local ensemble lesion activity error were used as quantitative evaluation metrics for PET image quality. Results With sparse view sampling, it is possible to greatly reduce the CT scan dose when it is primarily used for PET attenuation correction with little or no measureable effect on the PET image. For the four ultra-low dose levels

  1. Chalk as a reservoir

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke

    , and the best reservoir properties are typically found in mudstone intervals. Chalk mudstones vary a lot though. The best mudstones are purely calcitic, well sorted and may have been redeposited by traction currents. Other mudstones are rich in very fine grained silica, which takes up pore space and thus...... basin, so stylolite formation in the chalk is controlled by effective burial stress. The stylolites are zones of calcite dissolution and probably are the source of calcite for porefilling cementation which is typical in water zone chalk and also affect the reservoirs to different extent. The relatively...... have hardly any stylolites and can have porosity above 40% or even 50% and thus also have relatively high permeability. Such intervals have the problem though, that increasing effective stress caused by hydrocarbon production results in mechanical compaction and overall subsidence. Most other chalk...

  2. Application of integrated reservoir management and reservoir characterization to optimize infill drilling, Class II

    Energy Technology Data Exchange (ETDEWEB)

    Bergeron, Jack; Blasingame, Tom; Doublet, Louis; Kelkar, Mohan; Freeman, George; Callard, Jeff; Moore, David; Davies, David; Vessell, Richard; Pregger, Brian; Dixon, Bill; Bezant, Bryce

    2000-03-16

    The major purpose of this project was to demonstrate the use of cost effective reservoir characterization and management tools that will be helpful to both independent and major operators for the optimal development of heterogeneous, low permeability carbonate reservoirs such as the North Robertson (Clearfork) Unit.

  3. Phase I Final Report: Ultra-Low Background Alpha Activity Counter

    International Nuclear Information System (INIS)

    Warburton, W.K.

    2005-01-01

    In certain important physics experiments that search for rare-events, such as neutrino or double beta decay detections, it is critical to minimize the number of background events that arise from alpha particle emitted by the natural radioactivity in the materials used to construct the experiment. Similarly, the natural radioactivity in materials used to connect and package silicon microcircuits must also be minimized in order to eliminate ''soft errors'' caused by alpha particles depositing charges within the microcircuits and thereby changing their logic states. For these, and related reasons in the areas of environmental cleanup and nuclear materials tracking, there is a need that is important from commercial, scientific, and national security perspectives to develop an ultra-low background alpha counter that would be capable of measuring materials' alpha particle emissivity at rates well below 0.00001 alpha/cm 2 /hour. This rate, which corresponds to 24 alpha particles per square meter per day, is essentially impossible to achieve with existing commercial instruments because the natural radioactivity of the materials used to construct even the best of these counters produces background rates at the 0.005 alpha/cm 2 /hr level. Our company (XIA) had previously developed an instrument that uses electronic background suppression to operate at the 0.0005 0.005 alpha/cm 2 /hr level. This patented technology sets up an electric field between a large planar sample and a large planar anode, and fills the gap with pure Nitrogen. An alpha particle entering the chamber ionizes the Nitrogen, producing a ''track'' of electrons, which drift to the anode in the electric field. Tracks close to the anode take less than 10 microseconds (us) to be collected, giving a preamplifier signal with a 10 us risetime. Tracks from the sample have to drift across the full anode-sample gap and produce a 35 us risetime signal. By analyzing the preamplifier signals with a digital signal

  4. Compressible fluid flow through rocks of variable permeability

    International Nuclear Information System (INIS)

    Lin, W.

    1977-01-01

    The effectiveness of course-grained igneous rocks as shelters for burying radioactive waste can be assessed by determining the rock permeabilities at their in situ pressures and stresses. Analytical and numerical methods were used to solve differential equations of one-dimensional fluid flow through rocks with permeabilities from 10 4 to 1 nD. In these calculations, upstream and downstream reservoir volumes of 5, 50, and 500 cm 3 were used. The optimal size combinations of the two reservoirs were determined for measurements of permeability, stress, strain, acoustic velocity, and electrical conductivity on low-porosity, coarse-grained igneous rocks

  5. Intermittent operation of ultra-low pressure ultrafiltration for decentralized drinking water treatment.

    Science.gov (United States)

    Peter-Varbanets, Maryna; Gujer, Willi; Pronk, Wouter

    2012-06-15

    River water was treated by ultrafiltration at a relatively low transmembrane pressure (40 mbar). As observed before, flux stabilization occurred after several days of operation although no back-flushing or cross flow was applied. Interruptions in flux were applied by temporary offset of the transmembrane pressure. After restoration of the transmembrane pressure, the initial flux was higher than the stable flux level, and the flux recovery depended on the standstill time. Furthermore, if a short cross flow was applied after standstill, the flux was restored to an even higher level. In all cases, the flux decreased again during operation to reach finally the same stable level as before standstill. In order to evaluate the influence of intermittent operation as practiced for water treatment on a household level, daily interruptions of flux were applied. An optimum of total daily water production rate was obtained at 21 h of operation and 3 h of standstill per day. A model was developed which can describe the impact of intermittent operation on the flux depending on the duration of the standstill and operating periods. This enables the prediction of production capacity of the system operated intermittently. The flux increase during standstill could be explained by a relaxation and expansion of the biofouling layer, while the higher flux after forward-flushing was caused by this layer being partially sloughed off. Household water treatment with the process presented here will generally be operated on a discontinuous basis. The results show that such operation schemes do not compromise the permeability of the system, but actually lead to higher fluxes after standstill. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. Exceptional oxygen barrier performance of pullulan nanocomposites with ultra-low loading of graphene oxide

    Science.gov (United States)

    Uysal Unalan, Ilke; Wan, Chaoying; Figiel, Łukasz; Olsson, Richard T.; Trabattoni, Silvia; Farris, Stefano

    2015-07-01

    Polymer nanocomposites are increasingly important in food packaging sectors. Biopolymer pullulan is promising in manufacturing packaging films or coatings due to its excellent optical clarity, mechanical strength, and high water-solubility as compared to other biopolymers. This work aims to enhance its oxygen barrier properties and overcome its intrinsic brittleness by utilizing two-dimensional planar graphene oxide (GO) nanoplatelets. It has been found that the addition of only 0.2 wt% of GO enhanced the tensile strength, Young’s modulus, and elongation at break of pullulan films by about 40, 44 and 52%, respectively. The light transmittance at 550 nm of the pullulan/GO films was 92.3% and haze values were within 3.0% threshold, which meets the general requirement for food packaging materials. In particular, the oxygen permeability coefficient of pullulan was reduced from 6337 to 2614 mL μm m-2 (24 h-1) atm-1 with as low as 0.05 wt% of GO loading and further to 1357 mL μm m-2 (24 h-1) atm-1 when GO concentration reached 0.3 wt%. The simultaneous improvement of the mechanical and oxygen barrier properties of pullulan was ascribed to the homogeneous distribution and prevalent unidirectional alignment of GO nanosheets, as determined from the characterization and theoretical modelling results. The exceptional oxygen barrier properties of pullulan/GO nanocomposites with enhanced mechanical flexibility and good optical clarity will add new values to high performance food packaging materials.

  7. Exceptional oxygen barrier performance of pullulan nanocomposites with ultra-low loading of graphene oxide

    International Nuclear Information System (INIS)

    Unalan, Ilke Uysal; Farris, Stefano; Wan, Chaoying; Figiel, Łukasz; Olsson, Richard T; Trabattoni, Silvia

    2015-01-01

    Polymer nanocomposites are increasingly important in food packaging sectors. Biopolymer pullulan is promising in manufacturing packaging films or coatings due to its excellent optical clarity, mechanical strength, and high water-solubility as compared to other biopolymers. This work aims to enhance its oxygen barrier properties and overcome its intrinsic brittleness by utilizing two-dimensional planar graphene oxide (GO) nanoplatelets. It has been found that the addition of only 0.2 wt% of GO enhanced the tensile strength, Young’s modulus, and elongation at break of pullulan films by about 40, 44 and 52%, respectively. The light transmittance at 550 nm of the pullulan/GO films was 92.3% and haze values were within 3.0% threshold, which meets the general requirement for food packaging materials. In particular, the oxygen permeability coefficient of pullulan was reduced from 6337 to 2614 mL μm m"−"2 (24 h"−"1) atm"−"1 with as low as 0.05 wt% of GO loading and further to 1357 mL μm m"−"2 (24 h"−"1) atm"−"1 when GO concentration reached 0.3 wt%. The simultaneous improvement of the mechanical and oxygen barrier properties of pullulan was ascribed to the homogeneous distribution and prevalent unidirectional alignment of GO nanosheets, as determined from the characterization and theoretical modelling results. The exceptional oxygen barrier properties of pullulan/GO nanocomposites with enhanced mechanical flexibility and good optical clarity will add new values to high performance food packaging materials. (paper)

  8. Ultra-low leakage and high breakdown Schottky diodes fabricated on free-standing GaN substrate

    International Nuclear Information System (INIS)

    Wang, Yaqi; Alur, Siddharth; Sharma, Yogesh; Tong, Fei; Thapa, Resham; Gartland, Patrick; Issacs-Smith, Tamara; Ahyi, Claude; Williams, John; Park, Minseo; Johnson, Mark; Paskova, Tanya; Preble, Edward A; Evans, Keith R

    2011-01-01

    Vertical Schottky diodes were fabricated on the bulk GaN substrate with decreasing impurity concentration from N-face to Ga-face. An array of circular Pt Schottky contacts and a full backside Ti/Al/Ni/Au ohmic contact were prepared on the Ga-face and the N-face of the n-GaN substrate, respectively. The Schottky diode exhibits a minimum specific on-state resistance of 1.3 mΩ cm 2 and a maximum breakdown voltage of 600 V, resulting in a figure-of- merit of 275 MW cm −2 . An ultra-low reverse leakage current density of 3.7 × 10 −4 A cm −2 at reverse bias of 400 V was observed. Temperature-dependent I–V measurements were also carried out to study the forward and reverse transportation mechanisms. (fast track communication)

  9. A study on low temperature transformation ferrite in ultra low carbon IF steels (I) - effects of manganese and annealing conditions

    International Nuclear Information System (INIS)

    Jeong, Woo Chang; Lee, Jae Yeon; Jin, Young Sool

    2001-01-01

    An investigation was made to determine the effects of Mn content and annealing conditions on the formation of the low temperature transformation products in ultra low carbon interstitial free steels. With increasing the Mn content, yield and tensile strengths increased, but yield ratio decreased. The Mn was found to be effective to decrease the yield point elongation, causing continuous yielding in 3% Mn steel. Low temperature transformation ferrites such as quasi-polygonal ferrite, granular bainitic ferrite, and bainitic ferrite more easily formed with higher Mn content, higher annealing temperature, longer annealing time, and faster cooling rate. Polygonal ferrite grain was readily identified in the light microscope and was characterized by the polyhedral and equiaxed shape while quasi-polygonal ferrite showed the irregular changeful grain boundaries. It was found that both granular bainitic and bainitic ferrites revealed some etching evidence of substructures in the light microscope

  10. Relevant parameters in the micro silica selection for the self-flowing ultra-low cement castables production

    International Nuclear Information System (INIS)

    Studart, A.R.; Pandolfelli, V.C.; Rodrigues, J.A.; Vendrasco, S.L.

    1997-01-01

    Self-flowing ultra-low cement castables typically contain a large fraction of the particles, usually fume silica, which increase their flowability and mechanical strength at low temperatures. Fume silicas available in the market differ mainly from their amount of impurities. It is assumed that the content of soluble alkali and free carbon containing in this raw-material affects strongly the processing of self-flowing castable. In this work high alumina castables with gap-sized particle size distribution were prepared to evaluate their flowability, workability and mechanical strength for each sort of fume silica studied. It was observed that the amount of impurities affects both deflocculation and setting time of the castables and their cold and hot mechanical strength. Considerations regarding the physical and chemical characteristics relevant for selecting fume silicas for the production of self-flowing castables are presented and discussed. (author)

  11. Quantum mechanical study of molecular collisions at ultra-low energy: applications to alkali and alkaline-earth systems

    International Nuclear Information System (INIS)

    Quemener, G.

    2006-10-01

    In order to investigate the collisional processes which occur during the formation of molecular Bose-Einstein condensates, a time-independent quantum mechanical formalism, based on hyperspherical coordinates, has been applied to the study of atom-diatom dynamics at ultra-low energies. We present theoretical results for three alkali systems, each composed of lithium, sodium or potassium atoms, and for an alkaline-earth system composed of calcium atoms. We also study dynamics at large and positive atom-atom scattering length. Evidence for the suppression of inelastic processes in a fermionic system is given, as well as a linear relation between the atom-diatom scattering length and the atom-atom scattering length. (author)

  12. Ultra-low temperature process by ion shower doping technique for poly-Si TFTs on plastics

    International Nuclear Information System (INIS)

    Kim, Jong-Man; Lim, Huck; Kim, Do-Young; Jung, Ji-Sim; Kwon, Jang-Yeon; Hong, Wan-Shick; Noguchi, Takashi

    2006-01-01

    An ion doping process was performed by using a basic ion shower system. After ion doping and subsequent activation of the dopants in the Si film by excimer laser annealing (ELA), we studied the crystallinity of the Si surface using UV-reflectance spectroscopy and the sheet resistance by using 4-point probe measurements. To prevent excessive temperature increase on the plastic substrate during ion shower doping, the plasma shower was applied in a series of short pulses. As a result, dopant ions were efficiently incorporated and were activated into the a-Si film on plastic substrate after ELA. The sheet resistance decreased with increase of actual doping time, which corresponds to the incorporated dose. Also, we confirmed a distinct relationship between the crystallinity and the sheet resistance. This work shows that pulsed ion shower doping is a promising technique for ultra-low-temperature poly-Si TFTs on plastic substrates.

  13. Ultra-low fouling and high antibody loading zwitterionic hydrogel coatings for sensing and detection in complex media.

    Science.gov (United States)

    Chou, Ying-Nien; Sun, Fang; Hung, Hsiang-Chieh; Jain, Priyesh; Sinclair, Andrew; Zhang, Peng; Bai, Tao; Chang, Yung; Wen, Ten-Chin; Yu, Qiuming; Jiang, Shaoyi

    2016-08-01

    For surface-based diagnostic devices to achieve reliable biomarker detection in complex media such as blood, preventing nonspecific protein adsorption and incorporating high loading of biorecognition elements are paramount. In this work, a novel method to produce nonfouling zwitterionic hydrogel coatings was developed to achieve these goals. Poly(carboxybetaine acrylamide) (pCBAA) hydrogel thin films (CBHTFs) prepared with a carboxybetaine diacrylamide crosslinker (CBAAX) were coated on gold and silicon dioxide surfaces via a simple spin coating process. The thickness of CBHTFs could be precisely controlled between 15 and 150nm by varying the crosslinker concentration, and the films demonstrated excellent long-term stability. Protein adsorption from undiluted human blood serum onto the CBHTFs was measured with surface plasmon resonance (SPR). Hydrogel thin films greater than 20nm exhibited ultra-low fouling (crosslinked, purely zwitterionic, carboxybetaine thin film hydrogel (CBHTF) coating platform. The CBHTF on a hydrophilic surface demonstrated long-term stability. By varying the crosslinker content in the spin-coated hydrogel solution, the thickness of CBHTFs could be precisely controlled. Optimized CBHTFs exhibited ultra-low nonspecific protein adsorption below 5ng/cm(2) measured by a surface plasmon resonance (SPR) sensor, and their 3D architecture allowed antibody loading to reach 693ng/cm(2). This strategy provides a facile method to modify SPR biosensor chips with an advanced nonfouling material, and can be potentially expanded to a variety of implantable medical devices and diagnostic biosensors. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  14. CTA-enhanced perfusion CT: an original method to perform ultra-low-dose CTA-enhanced perfusion CT

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Elizabeth; Wintermark, Max [University of Virginia, Department of Radiology, Neuroradiology Division, Charlottesville, VA (United States)

    2014-11-15

    Utilizing CT angiography enhances image quality in PCT, thereby permitting acquisition at ultra-low dose. Dynamic CT acquisitions were obtained at 80 kVp with decreasing tube current-time product [milliamperes x seconds (mAs)] in patients suspected of ischemic stroke, with concurrent CTA of the cervical and intracranial arteries. By utilizing fast Fourier transformation, high spatial frequencies of CTA were combined with low spatial frequencies of PCT to create a virtual PCT dataset. The real and virtual PCT datasets with decreasing mAs were compared by assessing contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), and noise and PCT values and by visual inspection of PCT parametric maps. Virtual PCT attained CNR and SNR three- to sevenfold superior to real PCT and noise reduction by a factor of 4-6 (p < 0.05). At 20 mAs, virtual PCT achieved diagnostic parametric maps, while the quality of real PCT maps was inadequate. At 10 mAs, both real and virtual PCT maps were nondiagnostic. Virtual PCT (but not real PCT) maps regained diagnostic quality at 10 mAs by applying 40 % adaptive statistical iterative reconstruction (ASIR) and improved further with 80 % ASIR. Our new method of creating virtual PCT by combining ultra-low-dose PCT with CTA information yields diagnostic perfusion parametric maps from PCT acquired at 20 or 10 mAs with 80 % ASIR. Effective dose is approximately 0.20 mSv, equivalent to two chest radiographs. (orig.)

  15. A novel ultra-low carbon grain oriented silicon steel produced by twin-roll strip casting

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yang, E-mail: wy069024019@163.com [State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); Zhang, Yuan-Xiang; Lu, Xiang; Fang, Feng; Xu, Yun-Bo; Cao, Guang-Ming; Li, Cheng-Gang [State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); Misra, R.D.K. [Laboratory for Excellence in Advanced Steel Research, Department of Metallurgical, Materials and Biomedical Engineering, University of Texas at El Paso, TX 79968 (United States); Wang, Guo-Dong [State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China)

    2016-12-01

    A novel ultra-low carbon grain oriented silicon steel was successfully produced by strip casting and two-stage cold rolling method. The microstructure, texture and precipitate evolution under different first cold rolling reduction were investigated. It was shown that the as-cast strip was mainly composed of equiaxed grains and characterized by very weak Goss texture ({110}<001>) and λ-fiber (<001>//ND). The coarse sulfides of size ~100 nm were precipitated at grain boundaries during strip casting, while nitrides remained in solution in the as-cast strip and the fine AlN particles of size ~20–50 nm, which were used as grain growth inhibitors, were formed in intermediate annealed sheet after first cold rolling. In addition, the suitable Goss nuclei for secondary recrystallization were also formed during intermediate annealing, which is totally different from the conventional process that the Goss nuclei originated in the subsurface layer of the hot rolled sheet. Furthermore, the number of AlN inhibitors and the intensity of desirable Goss texture increased with increasing first cold rolling reduction. After secondary recrystallization annealing, very large grains of size ~10–40 mm were formed and the final magnetic induction, B{sub 8}, was as high as 1.9 T. - Highlights: • A novel chemical composition base on strip casting silicon steel was proposed. • The ultra-low carbon design could shorten the processing routes. • The novel composition and processes were beneficial to obtain more inhibitors. • The magnetic induction of grain oriented silicon steel was significantly improved.

  16. Corrosion resistance of Ultra-Low-Carbon 19% Cr-11% Ni stainless steel for nuclear fuel reprocessing plants in nitric acid

    International Nuclear Information System (INIS)

    Ariga, Tamako; Takagi, Yoshio; Inazumi, Toru; Masamura, Katsumi; Sukekawa, M.

    1995-01-01

    An Ultra-Low-Carbon 19% Cr-11% Ni Stainless Steels used in nuclear fuel reprocessing plants where highly corrosion resistance in nitric acid is required has been developed. This steel has optimized the chemistry composition to decrease inclusions and deformation-induced martensitic transformation. The formation of deformation-induced martensite has the potential danger of accelerating corrosion in nitric acid. In this paper, effects of cold reduction and martensitic transformation on corrosion resistance of Ultra-Low-Carbon Stainless Steels in nitric acid are discussed. The developed steel showed excellent corrosion resistance during long-term exposure to nitric acid. (author)

  17. Developments in permeable and low permeability barriers

    International Nuclear Information System (INIS)

    Jefferis, S.A.; Norris, G.H.; Thomas, A.O.

    1997-01-01

    The concept of the reactive treatment zone whereby pollutants are attenuated as they move along a pathway in the ground has enabled a re-thinking of many of the concepts of containment. In particular it offers the potential for the control of the flux from a contaminated area by controlling the contaminant concentration in the pathway(s) as well as or instead of using a low permeability barrier. The paper outlines the basic concepts of the reactive treatment zone and the use of permeable and low permeability reactive systems. The paper then gives a case history of the installation of a permeable barrier using an in-situ reaction chamber

  18. Are Geotehrmal Reservoirs Stressed Out?

    Science.gov (United States)

    Davatzes, N. C.; Laboso, R. C.; Layland-Bachmann, C. E.; Feigl, K. L.; Foxall, W.; Tabrez, A. R.; Mellors, R. J.; Templeton, D. C.; Akerley, J.

    2017-12-01

    Crustal permeability can be strongly influenced by developing connected networks of open fractures. However, the detailed evolution of a fracture network, its extent, and the persistence of fracture porosity are difficult to analyze. Even in fault-hosted geothermal systems, where heat is brought to the surface from depth along a fault, hydrothermal flow is heterogeneously distributed. This is presumably due to variations in fracture density, connectivity, and attitude, as well as variations in fracture permeability caused by sealing of fractures by precipitated cements or compaction. At the Brady Geothermal field in Nevada, we test the relationship between the modeled local stress state perturbed by dislocations representing fault slip or volume changes in the geothermal reservoir inferred from surface deformation measured by InSAR and the location of successful geothermal wells, hydrothermal activity, and seismicity. We postulate that permeability is favored in volumes that experience positive Coulomb stress changes and reduced compression, which together promote high densities of dilatant fractures. Conversely, permeability can be inhibited in locations where Coulomb stress is reduced, compression promotes compaction, or where the faults are poorly oriented in the stress field and consequently slip infrequently. Over geologic time scales spanning the development of the fault system, these local stress states are strongly influenced by the geometry of the fault network relative to the remote stress driving slip. At shorter time scales, changes in fluid pressure within the fracture network constituting the reservoir cause elastic dilations and contractions. We integrate: (1) direct observations of stress state and fractures in boreholes and the mapped geometry of the fault network; (2) evidence of permeability from surface hydrothermal features, production/injection wells and surface deformations related to pumping history; and (3) seismicity to test the

  19. Economics of Developing Hot Stratigraphic Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Greg Mines; Hillary Hanson; Rick Allis; Joseph Moore

    2014-09-01

    Stratigraphic geothermal reservoirs at 3 – 4 km depth in high heat-flow basins are capable of sustaining 100 MW-scale power plants at about 10 c/kWh. This paper examines the impacts on the levelized cost of electricity (LCOE) of reservoir depth and temperature, reservoir productivity, and drillhole/casing options. For a reservoir at 3 km depth with a moderate productivity index by hydrothermal reservoir standards (about 50 L/s/MPa, 5.6 gpm/psi), an LCOE of 10c/kWh requires the reservoir to be at about 200°C. This is the upper temperature limit for pumps. The calculations assume standard hydrothermal drilling costs, with the production interval completed with a 7 inch liner in an 8.5 inch hole. If a reservoir at 4 km depth has excellent permeability characteristics with a productivity index of 100 L/s/MPa (11.3 gpm/psi), then the LCOE is about 11 c/kWh assuming the temperature decline rate with development is not excessive (< 1%/y, with first thermal breakthrough delayed by about 10 years). Completing wells with modest horizontal legs (e.g. several hundred meters) may be important for improving well productivity because of the naturally high, sub-horizontal permeability in this type of reservoir. Reducing the injector/producer well ratio may also be cost-effective if the injectors are drilled as larger holes.

  20. Is multidetector CT-based bone mineral density and quantitative bone microstructure assessment at the spine still feasible using ultra-low tube current and sparse sampling?

    Energy Technology Data Exchange (ETDEWEB)

    Mei, Kai; Kopp, Felix K.; Schwaiger, Benedikt J.; Gersing, Alexandra S.; Sauter, Andreas; Muenzel, Daniela; Rummeny, Ernst J. [Klinikum rechts der Isar, Technische Universitaet Muenchen, Department of Diagnostic and Interventional Radiology, Munich (Germany); Bippus, Rolf [Research Laboratories, Philips GmbH Innovative Technologies, Hamburg (Germany); Koehler, Thomas [Research Laboratories, Philips GmbH Innovative Technologies, Hamburg (Germany); Technische Universitaet Muenchen, TUM Institute for Advanced Studies, Garching (Germany); Fehringer, Andreas [Technische Universitaet Muenchen, Lehrstuhl fuer Biomedizinische Physik, Garching (Germany); Pfeiffer, Franz [Klinikum rechts der Isar, Technische Universitaet Muenchen, Department of Diagnostic and Interventional Radiology, Munich (Germany); Technische Universitaet Muenchen, TUM Institute for Advanced Studies, Garching (Germany); Technische Universitaet Muenchen, Lehrstuhl fuer Biomedizinische Physik, Garching (Germany); Kirschke, Jan S. [Klinikum rechts der Isar, Technische Universitaet Muenchen, Section of Diagnostic and Interventional Neuroradiology, Munich (Germany); Noel, Peter B. [Klinikum rechts der Isar, Technische Universitaet Muenchen, Department of Diagnostic and Interventional Radiology, Munich (Germany); Technische Universitaet Muenchen, Lehrstuhl fuer Biomedizinische Physik, Garching (Germany); Baum, Thomas [Klinikum rechts der Isar, Technische Universitaet Muenchen, Department of Diagnostic and Interventional Radiology, Munich (Germany); Klinikum rechts der Isar, Technische Universitaet Muenchen, Section of Diagnostic and Interventional Neuroradiology, Munich (Germany)

    2017-12-15

    Osteoporosis diagnosis using multidetector CT (MDCT) is limited to relatively high radiation exposure. We investigated the effect of simulated ultra-low-dose protocols on in-vivo bone mineral density (BMD) and quantitative trabecular bone assessment. Institutional review board approval was obtained. Twelve subjects with osteoporotic vertebral fractures and 12 age- and gender-matched controls undergoing routine thoracic and abdominal MDCT were included (average effective dose: 10 mSv). Ultra-low radiation examinations were achieved by simulating lower tube currents and sparse samplings at 50%, 25% and 10% of the original dose. BMD and trabecular bone parameters were extracted in T10-L5. Except for BMD measurements in sparse sampling data, absolute values of all parameters derived from ultra-low-dose data were significantly different from those derived from original dose images (p<0.05). BMD, apparent bone fraction and trabecular thickness were still consistently lower in subjects with than in those without fractures (p<0.05). In ultra-low-dose scans, BMD and microstructure parameters were able to differentiate subjects with and without vertebral fractures, suggesting osteoporosis diagnosis is feasible. However, absolute values differed from original values. BMD from sparse sampling appeared to be more robust. This dose-dependency of parameters should be considered for future clinical use. (orig.)

  1. A self-starting hybrid optoelectronic oscillator generating ultra low jitter 10-GHz optical pulses and low phase noise electrical signals

    DEFF Research Database (Denmark)

    Lasri, J.; Bilenca, A.; Dahan, D.

    2002-01-01

    In this letter, we describe a self-starting optical pulse source generating ultra low noise 15-ps-wide pulses at 10 GHz. It is based on a hybrid optoelectronic oscillator comprising a fiber extended cavity mode-locked diode laser which injection locks a self-oscillating heterojunction bipolar...

  2. Evaluation of ultra low volume and thermal fog pesticide applications against Old World Phlebotomine sand fly vectors of Leishmania in Kenya

    Science.gov (United States)

    One component of the Department of Defense (DoD) pest management system is ultra-low volume (ULV) and/or thermal fog aerosol pesticide application. Despite widespread implementations of this and other components of the system, such as use of repellents and permethrin, US military operations in hot-a...

  3. Is multidetector CT-based bone mineral density and quantitative bone microstructure assessment at the spine still feasible using ultra-low tube current and sparse sampling?

    International Nuclear Information System (INIS)

    Mei, Kai; Kopp, Felix K.; Schwaiger, Benedikt J.; Gersing, Alexandra S.; Sauter, Andreas; Muenzel, Daniela; Rummeny, Ernst J.; Bippus, Rolf; Koehler, Thomas; Fehringer, Andreas; Pfeiffer, Franz; Kirschke, Jan S.; Noel, Peter B.; Baum, Thomas

    2017-01-01

    Osteoporosis diagnosis using multidetector CT (MDCT) is limited to relatively high radiation exposure. We investigated the effect of simulated ultra-low-dose protocols on in-vivo bone mineral density (BMD) and quantitative trabecular bone assessment. Institutional review board approval was obtained. Twelve subjects with osteoporotic vertebral fractures and 12 age- and gender-matched controls undergoing routine thoracic and abdominal MDCT were included (average effective dose: 10 mSv). Ultra-low radiation examinations were achieved by simulating lower tube currents and sparse samplings at 50%, 25% and 10% of the original dose. BMD and trabecular bone parameters were extracted in T10-L5. Except for BMD measurements in sparse sampling data, absolute values of all parameters derived from ultra-low-dose data were significantly different from those derived from original dose images (p<0.05). BMD, apparent bone fraction and trabecular thickness were still consistently lower in subjects with than in those without fractures (p<0.05). In ultra-low-dose scans, BMD and microstructure parameters were able to differentiate subjects with and without vertebral fractures, suggesting osteoporosis diagnosis is feasible. However, absolute values differed from original values. BMD from sparse sampling appeared to be more robust. This dose-dependency of parameters should be considered for future clinical use. (orig.)

  4. Design and Analysis of Double-Gate MOSFETs for Ultra-Low Power Radio Frequency Identification (RFID: Device and Circuit Co-Design

    Directory of Open Access Journals (Sweden)

    Tony T. Kim

    2011-07-01

    Full Text Available Recently, double-gate MOSFETs (DGMOSFETs have been shown to be more optimal for ultra-low power circuit design due to the improved subthreshold slope and the reduced leakage current compared to bulk CMOS. However, DGMOSFETs for subthreshold circuit design have not been much explored in comparison to those for strong inversion-based design. In this paper, various configurations of DGMOSFETs, such as tied/independent gates and symmetric/asymmetric gate oxide thickness are explored for ultra-low power and high efficient radio frequency identification (RFID design. Comparison of bulk CMOS with DGMOSFETs has been conducted in ultra-low power subthreshold digital logic design and rectifier design, emphasizing the scope of the nano-scale DGMOSFET technology for future ultra-low power systems. The DGMOSFET-based subthreshold logic improves energy efficiency by more than 40% compared to the bulk CMOS-based logic at 32 nm. Among the various DGMOSFET configurations for RFID rectifiers, symmetric tied-gate DGMOSFET has the best power conversion efficiency and the lowest power consumption.

  5. Comparative study of Ta, TaN and Ta/TaN bi-layer barriers for Cu-ultra low-k porous polymer integration

    International Nuclear Information System (INIS)

    Yang, L.Y.; Zhang, D.H.; Li, C.Y.; Foo, P.D.

    2004-01-01

    Tantalum (Ta), TaN and bilayer Ta/TaN barriers deposited on ultra-low-k porous polymer (ULKPP) and the thermal stability of their structures are comparatively investigated using various techniques. The Ta/ultra-low-k polymer shows the smallest sheet resistance, but the poorest thermal stability, while TaN on the ultra-low-k polymer shows the highest resistance but the best thermal stability. The bi-layer Ta/TaN barrier takes the advantage of both Ta and TaN barriers and gives reasonable resistance and thermal stability. The electrical tests indicate that the Cu lines with the TaN and bi-layer Ta/TaN barriers exhibit the smaller leakage current and higher breakdown voltage compared with the Cu lines with the Ta barrier. The better thermal stability of the TaN and the bi-layer Ta/TaN barriers is mainly due to the amorphous/nanostructure and less grain boundaries of the barriers. In addition, the texture discontinuity at the Ta/TaN interfaces in the bi-layers barrier also plays an important role in reducing mutual diffusion of Ta atoms in the Ta barrier and some atoms in the ultra-low-k porous polymer

  6. FRACTURED PETROLEUM RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    Abbas Firoozabadi

    1999-06-11

    The four chapters that are described in this report cover a variety of subjects that not only give insight into the understanding of multiphase flow in fractured porous media, but they provide also major contribution towards the understanding of flow processes with in-situ phase formation. In the following, a summary of all the chapters will be provided. Chapter I addresses issues related to water injection in water-wet fractured porous media. There are two parts in this chapter. Part I covers extensive set of measurements for water injection in water-wet fractured porous media. Both single matrix block and multiple matrix blocks tests are covered. There are two major findings from these experiments: (1) co-current imbibition can be more efficient than counter-current imbibition due to lower residual oil saturation and higher oil mobility, and (2) tight fractured porous media can be more efficient than a permeable porous media when subjected to water injection. These findings are directly related to the type of tests one can perform in the laboratory and to decide on the fate of water injection in fractured reservoirs. Part II of Chapter I presents modeling of water injection in water-wet fractured media by modifying the Buckley-Leverett Theory. A major element of the new model is the multiplication of the transfer flux by the fractured saturation with a power of 1/2. This simple model can account for both co-current and counter-current imbibition and computationally it is very efficient. It can be orders of magnitude faster than a conventional dual-porosity model. Part II also presents the results of water injection tests in very tight rocks of some 0.01 md permeability. Oil recovery from water imbibition tests from such at tight rock can be as high as 25 percent. Chapter II discusses solution gas-drive for cold production from heavy-oil reservoirs. The impetus for this work is the study of new gas phase formation from in-situ process which can be significantly

  7. Frictional stability-permeability relationships for fractures in shales

    Science.gov (United States)

    Fang, Yi; Elsworth, Derek; Wang, Chaoyi; Ishibashi, Takuya; Fitts, Jeffrey P.

    2017-03-01

    There is wide concern that fluid injection in the subsurface, such as for the stimulation of shale reservoirs or for geological CO2 sequestration (GCS), has the potential to induce seismicity that may change reservoir permeability due to fault slip. However, the impact of induced seismicity on fracture permeability evolution remains unclear due to the spectrum of modes of fault reactivation (e.g., stable versus unstable). As seismicity is controlled by the frictional response of fractures, we explore friction-stability-permeability relationships through the concurrent measurement of frictional and hydraulic properties of artificial fractures in Green River shale (GRS) and Opalinus shale (OPS). We observe that carbonate-rich GRS shows higher frictional strength but weak neutral frictional stability. The GRS fracture permeability declines during shearing while an increased sliding velocity reduces the rate of permeability decline. By comparison, the phyllosilicate-rich OPS has lower friction and strong stability while the fracture permeability is reduced due to the swelling behavior that dominates over the shearing induced permeability reduction. Hence, we conclude that the friction-stability-permeability relationship of a fracture is largely controlled by mineral composition and that shale mineral compositions with strong frictional stability may be particularly subject to permanent permeability reduction during fluid infiltration.

  8. Effect of different reconstruction algorithms on computer-aided diagnosis (CAD) performance in ultra-low dose CT colonography

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eun Sun [Department of Radiology, Seoul National University Hospital (Korea, Republic of); Institute of Radiation Medicine, Seoul National University Hospital (Korea, Republic of); Kim, Se Hyung, E-mail: shkim7071@gmail.com [Department of Radiology, Seoul National University Hospital (Korea, Republic of); Institute of Radiation Medicine, Seoul National University Hospital (Korea, Republic of); Im, Jong Pil; Kim, Sang Gyun [Department of Internal Medicine, Seoul National University Hospital (Korea, Republic of); Shin, Cheong-il; Han, Joon Koo; Choi, Byung Ihn [Department of Radiology, Seoul National University Hospital (Korea, Republic of); Institute of Radiation Medicine, Seoul National University Hospital (Korea, Republic of)

    2015-04-15

    Highlights: •We assessed the effect of reconstruction algorithms on CAD in ultra-low dose CTC. •30 patients underwent ultra-low dose CTC using 120 and 100 kVp with 10 mAs. •CT was reconstructed with FBP, ASiR and Veo and then, we applied a CAD system. •Per-polyp sensitivity of CAD in ULD CT can be improved with the IR algorithms. •Despite of an increase in the number of FPs with IR, it was still acceptable. -- Abstract: Purpose: To assess the effect of different reconstruction algorithms on computer-aided diagnosis (CAD) performance in ultra-low-dose CT colonography (ULD CTC). Materials and methods: IRB approval and informed consents were obtained. Thirty prospectively enrolled patients underwent non-contrast CTC at 120 kVp/10 mAs in supine and 100 kVp/10 mAs in prone positions, followed by same-day colonoscopy. Images were reconstructed with filtered back projection (FBP), 80% adaptive statistical iterative reconstruction (ASIR80), and model-based iterative reconstruction (MBIR). A commercial CAD system was applied and per-polyp sensitivities and numbers of false-positives (FPs) were compared among algorithms. Results: Mean effective radiation dose of CTC was 1.02 mSv. Of 101 polyps detected and removed by colonoscopy, 61 polyps were detected on supine and on prone CTC datasets on consensus unblinded review, resulting in 122 visible polyps (32 polyps <6 mm, 52 6–9.9 mm, and 38 ≥ 10 mm). Per-polyp sensitivity of CAD for all polyps was highest with MBIR (56/122, 45.9%), followed by ASIR80 (54/122, 44.3%) and FBP (43/122, 35.2%), with significant differences between FBP and IR algorithms (P < 0.017). Per-polyp sensitivity for polyps ≥ 10 mm was also higher with MBIR (25/38, 65.8%) and ASIR80 (24/38, 63.2%) than with FBP (20/38, 58.8%), albeit without statistical significance (P > 0.017). Mean number of FPs was significantly different among algorithms (FBP, 1.4; ASIR, 2.1; MBIR, 2.4) (P = 0.011). Conclusion: Although the performance of stand-alone CAD

  9. Effect of different reconstruction algorithms on computer-aided diagnosis (CAD) performance in ultra-low dose CT colonography

    International Nuclear Information System (INIS)

    Lee, Eun Sun; Kim, Se Hyung; Im, Jong Pil; Kim, Sang Gyun; Shin, Cheong-il; Han, Joon Koo; Choi, Byung Ihn

    2015-01-01

    Highlights: •We assessed the effect of reconstruction algorithms on CAD in ultra-low dose CTC. •30 patients underwent ultra-low dose CTC using 120 and 100 kVp with 10 mAs. •CT was reconstructed with FBP, ASiR and Veo and then, we applied a CAD system. •Per-polyp sensitivity of CAD in ULD CT can be improved with the IR algorithms. •Despite of an increase in the number of FPs with IR, it was still acceptable. -- Abstract: Purpose: To assess the effect of different reconstruction algorithms on computer-aided diagnosis (CAD) performance in ultra-low-dose CT colonography (ULD CTC). Materials and methods: IRB approval and informed consents were obtained. Thirty prospectively enrolled patients underwent non-contrast CTC at 120 kVp/10 mAs in supine and 100 kVp/10 mAs in prone positions, followed by same-day colonoscopy. Images were reconstructed with filtered back projection (FBP), 80% adaptive statistical iterative reconstruction (ASIR80), and model-based iterative reconstruction (MBIR). A commercial CAD system was applied and per-polyp sensitivities and numbers of false-positives (FPs) were compared among algorithms. Results: Mean effective radiation dose of CTC was 1.02 mSv. Of 101 polyps detected and removed by colonoscopy, 61 polyps were detected on supine and on prone CTC datasets on consensus unblinded review, resulting in 122 visible polyps (32 polyps <6 mm, 52 6–9.9 mm, and 38 ≥ 10 mm). Per-polyp sensitivity of CAD for all polyps was highest with MBIR (56/122, 45.9%), followed by ASIR80 (54/122, 44.3%) and FBP (43/122, 35.2%), with significant differences between FBP and IR algorithms (P < 0.017). Per-polyp sensitivity for polyps ≥ 10 mm was also higher with MBIR (25/38, 65.8%) and ASIR80 (24/38, 63.2%) than with FBP (20/38, 58.8%), albeit without statistical significance (P > 0.017). Mean number of FPs was significantly different among algorithms (FBP, 1.4; ASIR, 2.1; MBIR, 2.4) (P = 0.011). Conclusion: Although the performance of stand-alone CAD

  10. Early detection of lung cancer using ultra-low-dose computed tomography in coronary CT angiography scans among patients with suspected coronary heart disease.

    Science.gov (United States)

    Zanon, Matheus; Pacini, Gabriel Sartori; de Souza, Vinicius Valério Silveiro; Marchiori, Edson; Meirelles, Gustavo Souza Portes; Szarf, Gilberto; Torres, Felipe Soares; Hochhegger, Bruno

    2017-12-01

    To assess whether an additional chest ultra-low-dose CT scan to the coronary CT angiography protocol can be used for lung cancer screening among patients with suspected coronary artery disease. 175 patients underwent coronary CT angiography for assessment of coronary artery disease, additionally undergoing ultra-low-dose CT screening to early diagnosis of lung cancer in the same scanner (80kVp and 15mAs). Patients presenting pulmonary nodules were followed-up for two years, repeating low-dose CTs in intervals of 3, 6, or 12 months based on nodule size and growth rate in accordance with National Comprehensive Cancer Network guidelines. Ultra-low-dose CT identified 71 patients with solitary pulmonary nodules (41%), with a mean diameter of 5.50±4.00mm. Twenty-eight were >6mm, and in 79% (n=22) of these cases they were false positive findings, further confirmed by follow-up (n=20), resection (n=1), or biopsy (n=1). Lung cancer was detected in six patients due to CT screening (diagnostic yield: 3%). Among these, four cases could not be detected in the cardiac field of view. Most patients were in early stages of the disease. Two patients diagnosed at advanced stages died due to cancer complications. The addition of the ultra-low-dose CT scan represented a radiation dose increment of 1.22±0.53% (effective dose, 0.11±0.03mSv). Lung cancer might be detected using additional ultra-low-dose protocols in coronary CT angiography scans among patients with suspected coronary artery disease. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Impact of the adaptive statistical iterative reconstruction technique on image quality in ultra-low-dose CT

    International Nuclear Information System (INIS)

    Xu, Yan; He, Wen; Chen, Hui; Hu, Zhihai; Li, Juan; Zhang, Tingting

    2013-01-01

    Aim: To evaluate the relationship between different noise indices (NIs) and radiation dose and to compare the effect of different reconstruction algorithm applications for ultra-low-dose chest computed tomography (CT) on image quality improvement and the accuracy of volumetric measurement of ground-glass opacity (GGO) nodules using a phantom study. Materials and methods: A 11 cm thick transverse phantom section with a chest wall, mediastinum, and 14 artificial GGO nodules with known volumes (919.93 ± 64.05 mm 3 ) was constructed. The phantom was scanned on a Discovery CT 750HD scanner with five different NIs (NIs = 20, 30, 40, 50, and 60). All data were reconstructed with a 0.625 mm section thickness using the filtered back-projection (FBP), 50% adaptive statistical iterative reconstruction (ASiR), and Veo model-base iterative reconstruction algorithms. Image noise was measured in six regions of interest (ROIs). Nodule volumes were measured using a commercial volumetric software package. The image quality and the volume measurement errors were analysed. Results: Image noise increased dramatically from 30.7 HU at NI 20 to 122.4 HU at NI 60, with FBP reconstruction. Conversely, Veo reconstruction effectively controlled the noise increase, with an increase from 9.97 HU at NI 20 to only 15.1 HU at NI 60. Image noise at NI 60 with Veo was even lower (50.8%) than that at NI 20 with FBP. The contrast-to-noise ratio (CNR) of Veo at NI 40 was similar to that of FBP at NI 20. All artificial GGO nodules were successfully identified and measured with an average relative volume measurement error with Veo at NI 60 of 4.24%, comparable to a value of 10.41% with FBP at NI 20. At NI 60, the radiation dose was only one-tenth that at NI 20. Conclusion: The Veo reconstruction algorithms very effectively reduced image noise compared with the conventional FBP reconstructions. Using ultra-low-dose CT scanning and Veo reconstruction, GGOs can be detected and quantified with an acceptable

  12. Modeling of non-equilibrium effects in solvent-enhanced spontaneous imbibition in fractured reservoirs

    NARCIS (Netherlands)

    Chahardowli, M.; Bruining, J.

    2013-01-01

    In fractured reservoirs, much of the oil is stored in low permeable matrix blocks that are surrounded by a high permeability fracture network. Therefore, production from fractured reservoir depends on the transfer between fracture and matrix, which is critically dependent on their interaction.

  13. Modeling of non-equilibrium effects in solvent-enhanced spontaneous imbibition in fractured reservoirs (poster)

    NARCIS (Netherlands)

    Chahardowli, M.; Bruining, J.

    2013-01-01

    In fractured reservoirs, much of the oil is stored in low permeable matrix blocks that are surrounded by a high permeability fracture network. Therefore, production from fractured reservoir depends on the transfer between fracture and matrix, which is critically dependent on their interaction.

  14. A Design Report of the Baseline for PEP-X: an Ultra-Low Emittance Storage Ring

    Energy Technology Data Exchange (ETDEWEB)

    Bane, Karl; Bertsche, Kirk; Cai, Yunhai; Chao, Alex; Corbett, Willian; Fox, John; Hettel, Robert; Huang, Xiaobiao; Huang, Zhirong; Ng, Cho-Kuen; Nosochkov, Yuri; Novokhatski, Sasha; Radedeau, Thomas; Raubenheimer, Tor; Rivetta, Claudio; Safranek, James; Seeman, John; Stohr, Joachim; Stupakov, Gennady; Wang, Lanfa; Wang, Min-Huey; /SLAC

    2010-06-02

    Over the past year, we have worked out a baseline design for PEP-X, as an ultra-low emittance storage ring that could reside in the existing 2.2-km PEPII tunnel. The design features a hybrid lattice with double bend achromat (DBA) cells in two arcs and theoretical minimum emittance (TME) cells in the remaining four arcs. Damping wigglers are used to reduce the horizontal emittance to 86 pm-rad at zero current for a 4.5 GeV electron beam. At a design current of 1.5 A, the horizontal emittance increases, due to intrabeam scattering, to 164 pm-rad when the vertical emittance is maintained at a diffraction limited 8 pm-rad. The baseline design will produce photon beams achieving a brightness of 10{sup 22} (ph/s/mm{sup 2}/mrad{sup 2}/0.1% BW) at 10 keV in a 3.5-m conventional planar undulator. Our study shows that an optimized lattice has adequate dynamic aperture, while accommodating a conventional off-axis injection system. In this report, we present the results of study, including the lattice properties, nonlinear dynamics, intra-beam scattering and Touschek lifetime, RF system, and collective instabilities. Finally, we discuss the possibility of partial lasing at soft X-ray wavelengths using a long undulator in a straight section.

  15. Natural time analysis on the ultra-low frequency magnetic field variations prior to the 2016 Kumamoto (Japan) earthquakes

    Science.gov (United States)

    Potirakis, Stelios M.; Schekotov, Alexander; Asano, Tomokazu; Hayakawa, Masashi

    2018-04-01

    On 15 April 2016 a very strong and shallow earthquake (EQ) (MW = 7.0 , depth ∼ 10 km) occurred in Southwest Japan under the city of Kumamoto, while two very strong foreshocks (MW = 6.2 and MW = 6.0) preceded by about one day. The Kumamoto EQs being very catastrophic, have already attracted much attention among the scientific community in a quest for understanding the generation mechanism, as well as for reporting any preseismic anomalies in various observables and assessing the effectivity of the current early warning systems. In the present article we report precursory behavior of the ground-based observed ultra-low frequency (ULF) magnetic field variations before the Kumamoto EQs. By analyzing specific ULF magnetic field characteristics in terms of the recently introduced natural time (NT) analysis method, we identified that ULF magnetic field variations presented critical features from 2 weeks up to 1 month before the Kumamoto EQs. Specifically, the ULF magnetic field characteristics Fh , Fz , Dh and δDep were analyzed. The first two represent variations of the horizontal and vertical components of the geomagnetic field. The third and fourth characteristics correspond to the depression (decrease) and a relative depression of the horizontal magnetic field variations, respectively. The latter depends on the degree of ionospheric disturbance. All of them were found to reach criticality before the Kumamoto EQs; however, in different time periods for each characteristic.

  16. Criticality features in ultra-low frequency magnetic fields prior to the 2013 M6.3 Kobe earthquake

    Directory of Open Access Journals (Sweden)

    Stelios M. Potirakis

    2016-07-01

    Full Text Available The nonlinear criticality of ultra-low frequency (ULF magnetic variations is investigated before a particular earthquake (EQ occurred in Kobe on April 12, 2013, by applying the “natural time” analysis on a few ULF parameters: Fh, Fz and Dh. The first two refer to radiation from the lithosphere, and the last parameter corresponds to depression of horizontal component as a signature of ionospheric perturbation. A recent paper of our team has indicated, using the same data as in this paper but by means of conventional statistical analysis, a clear effect of depression in the horizontal component as an ionospheric signature. But there seems to be no convincing signature of lithospheric ULF radiation according to the specific analysis, so this paper aims at extending our study on the electromagnetic data recorded prior to the specific EQ by trying to find any significant phenomenon in ULF effects (both lithospheric radiation and the depression of horizontal component using the critical, natural time analysis. The natural time analysis has yielded that criticality at Shigaraki (SGA, as the station closest to the EQ epicenter, is reached on March 27-29 for Fh and March 27 to April 1 for Fz (about two weeks before the EQ. But, the criticality for Dh was not observed at SGA probably due to high noise, on the other hand such criticality was observed at Kanoya (KNY because of its known property of a wider range of detection of ULF depression.

  17. Optics Design and Performance of an Ultra-Low Emittance Damping Ring for the Compact Linear Collider

    CERN Document Server

    Korostelev, M S

    2006-01-01

    A high-energy (0.5-3.0 TeV centre of mass) electron-positron Compact Linear Collider (CLIC) is being studied at CERN as a new physics facility. The design study has been optimized for 3 TeV centre-of-mass energy. Intense bunches injected into the main linac must have unprecedentedly small emittances to achieve the design luminosity 1035cm-2s-1 required for the physics experiments. The positron and electron bunch trains will be provided by the CLIC injection complex. This thesis describes an optics design and performance of a positron damping ring developed for producing such ultra-low emittance beam. The linear optics of the CLIC damping ring is optimized by taking into account the combined action of radiation damping, quantum excitation and intrabeam scattering. The required beam emittance is obtained by using a TME (Theoretical Minimum Emittance) lattice with compact arcs and short period wiggler magnets located in dispersionfree regions. The damping ring beam energy is chosen as 2.42 GeV. The lattice featu...

  18. Clean conditions for the determination of ultra-low levels of mercury in ice and snow samples

    International Nuclear Information System (INIS)

    Ferrari, C.P.; Moreau, A.L.; Boutron, C.F.; Univ. Joseph Fourier de Grenoble

    2000-01-01

    Laboratory facilities and methods are presented for the determination of ultra-low levels of mercury (Hg) in ice and snow samples originating from polar ice caps or temperate regions. Special emphasis will be given to the presentation of the clean laboratory and the cleaning procedures. The laboratory is pressurized with air filtered through high efficiency particle filters. This first filtration is not enough to get rid of contamination by Hg in air. Experiments are conducted in a clean bench, especially built for Hg analysis, equipped with both particle filter and activated charcoal filter. It allows to obtain very low levels of atmospheric Hg contamination. Ultrapure water is produced for cleaning all the plastic containers that will be used for ice and snow samples and also for the dilution of the standards. Hg content in laboratory water is about 0.08 ± 0.02 pg/g. A Teflon system has been developed for the determination of Hg in ice and snow samples based on Hg(II) reduction to Hg(0) with a SnCl 2 /HNO 3 solution followed by the measurement of gaseous Hg(0) with a Hg analyzer GARDIS 1A+ based on the Cold Vapor Atomic Absorption Spectroscopy method. Blank determination is discussed. (orig.)

  19. Electrical activation of solid-phase epitaxially regrown ultra-low energy boron implants in Ge preamorphised silicon and SOI

    International Nuclear Information System (INIS)

    Hamilton, J.J.; Collart, E.J.H.; Colombeau, B.; Jeynes, C.; Bersani, M.; Giubertoni, D.; Sharp, J.A.; Cowern, N.E.B.; Kirkby, K.J.

    2005-01-01

    The formation of highly activated ultra-shallow junctions (USJ) is one of the key requirements for the next generation of CMOS devices. One promising method for achieving this is the use of Ge preamorphising implants (PAI) prior to ultra-low energy B implantation. In future technology nodes, bulk silicon wafers may be supplanted by Silicon-on-Insulator (SOI), and an understanding of the Solid Phase Epitaxial (SPE) regrowth process and its correlation to dopant electrical activation in both bulk silicon and SOI is essential in order to understand the impact of this potential technology change. This kind of understanding will also enable tests of fundamental models for defect evolution and point-defect reactions at silicon/oxide interfaces. In the present work, B is implanted into Ge PAI silicon and SOI wafers with different PAI conditions and B doses, and resulting samples are annealed at various temperatures and times. Glancing-exit Rutherford Backscattering Spectrometry (RBS) is used to monitor the regrowth of the amorphous silicon, and the resulting redistribution and electrical activity of B are monitored by SIMS and Hall measurements. The results confirm the expected enhancement of regrowth velocity by B doping, and show that this velocity is otherwise independent of the substrate type and the Ge implant distribution within the amorphised layer. Hall measurements on isochronally annealed samples show that B deactivates less in SOI material than in bulk silicon, in cases where the Ge PAI end-of-range defects are close to the SOI back interface

  20. Ultra-low-cost 3D gaze estimation: an intuitive high information throughput compliment to direct brain-machine interfaces

    Science.gov (United States)

    Abbott, W. W.; Faisal, A. A.

    2012-08-01

    Eye movements are highly correlated with motor intentions and are often retained by patients with serious motor deficiencies. Despite this, eye tracking is not widely used as control interface for movement in impaired patients due to poor signal interpretation and lack of control flexibility. We propose that tracking the gaze position in 3D rather than 2D provides a considerably richer signal for human machine interfaces by allowing direct interaction with the environment rather than via computer displays. We demonstrate here that by using mass-produced video-game hardware, it is possible to produce an ultra-low-cost binocular eye-tracker with comparable performance to commercial systems, yet 800 times cheaper. Our head-mounted system has 30 USD material costs and operates at over 120 Hz sampling rate with a 0.5-1 degree of visual angle resolution. We perform 2D and 3D gaze estimation, controlling a real-time volumetric cursor essential for driving complex user interfaces. Our approach yields an information throughput of 43 bits s-1, more than ten times that of invasive and semi-invasive brain-machine interfaces (BMIs) that are vastly more expensive. Unlike many BMIs our system yields effective real-time closed loop control of devices (10 ms latency), after just ten minutes of training, which we demonstrate through a novel BMI benchmark—the control of the video arcade game ‘Pong’.

  1. Effectiveness of Biodiesel from Various Tropical Oil Crops on Lubricity Improvement of Ultra Low Sulfur Diesel (ULSD)

    Energy Technology Data Exchange (ETDEWEB)

    Chollacoop, Nuwong; Topaiboul, Subongkoj; Goodwin, Vituruch (Bioenergy Group, National Metal and Materials Technology Center (MTEC), Thailand Science Park, Pathumthani, 12120 (Thailand)). e-mail: nuwongc@mtec.or.th

    2008-10-15

    Ultra low sulfur diesel (ULSD) has been introduced worldwide with an aim to reduce emission. Since the desulfurization process for ULSD inadvertently reduces its lubricity, lubricity additive is needed. Biodiesel emerges as a potential candidate due to its excellent lubricity property and little sulfur content. In the present study, biodiesel from various energy crops available in Thailand was added at various amounts to ULSD to test the lubricity according to the CEC-F-06-A-96 standard (using High-Frequency Reciprocating Rig: HFRR [1]). It was found that when biodiesel from crude palm, jatropha, soybean, coconut, sunflower, rice, corn and sesame oils of less than 1% (by volume) is additized to ULSD, the lubricity is improved to meet the diesel standard. Further addition beyond 2% (by volume) does not improve lubricity remarkably, where the lubrication seems to saturate. Biodiesel improves lubricity property by film formation preventing mechanical contact between the rubbing surfaces, and the effectiveness varies among different feedstock oils. Biodiesel from crude palm oil, jatropha oil and coconut oil seemingly are superior lubricity additives in ULSD than that from soybean oil, sunflower oil, rice oil, corn oil and sesame oil. Keywords: biodiesel, bio-lubricants, palm oil, sunflower oil

  2. A numerical model for ocean ultra-low frequency noise: wave-generated acoustic-gravity and Rayleigh modes.

    Science.gov (United States)

    Ardhuin, Fabrice; Lavanant, Thibaut; Obrebski, Mathias; Marié, Louis; Royer, Jean-Yves; d'Eu, Jean-François; Howe, Bruce M; Lukas, Roger; Aucan, Jerome

    2013-10-01

    The generation of ultra-low frequency acoustic noise (0.1 to 1 Hz) by the nonlinear interaction of ocean surface gravity waves is well established. More controversial are the quantitative theories that attempt to predict the recorded noise levels and their variability. Here a single theoretical framework is used to predict the noise level associated with propagating pseudo-Rayleigh modes and evanescent acoustic-gravity modes. The latter are dominant only within 200 m from the sea surface, in shallow or deep water. At depths larger than 500 m, the comparison of a numerical noise model with hydrophone records from two open-ocean sites near Hawaii and the Kerguelen islands reveal: (a) Deep ocean acoustic noise at frequencies 0.1 to 1 Hz is consistent with the Rayleigh wave theory, in which the presence of the ocean bottom amplifies the noise by 10 to 20 dB; (b) in agreement with previous results, the local maxima in the noise spectrum support the theoretical prediction for the vertical structure of acoustic modes; and (c) noise level and variability are well predicted for frequencies up to 0.4 Hz. Above 0.6 Hz, the model results are less accurate, probably due to the poor estimation of the directional properties of wind-waves with frequencies higher than 0.3 Hz.

  3. Development of ultra low dew-point clean air generator; Cho tei roten seijo kuki hassei sochi no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, H.; Okamura, N. [Takasago thermal Engineering Co., Ltd., Kanagawa (Japan)

    2000-05-10

    To reduce the manufacturing cost of semiconductors, some systems have been proposed that use a cheap and high purity Clean Dry Air (CDA). CDA can reduce process step such as wafer cleaning, because CDA flow in stocker prevents the wafer surface from adsorbing of moisture and organic impurities. We have already optimized a two-stage rotary dehumidifier and have conducted a study of methods for cheaply manufacturing air that has a low dew-point of -70 degree C to -50 degree C. We have further developed the method in which a dry dehumidifier is used, and developed an ultra low dew-point air generator. The air generator is a three-stage rotary dehumidifier in which a further stage is added to the two-stage rotary dehumidifier. The main component of the rotors is metal silicate. The air generator can supply dry air with a dew-point of -110 degree C. or less, in which the concentration in all gaseous contaminants is far below 1 ppb. We made a trial calculation of the manufacturing cost, and an average cost of 0.25 yen/m{sup 3} was obtained. (author)

  4. Effect of heat treatment and cleanness of ultra low carbon bainitic (ULCB) steel on its impact toughness

    International Nuclear Information System (INIS)

    Lis, A.K.

    1998-01-01

    The small variations in sulphur and carbon concentrations can have a major influence on the impact transition temperature (ITT) of ultra low carbon HSLA-100 steel which has been quenched in water and tempered (WQ and T). Since the average carbon concentration is very low thus sensitivity of ITT to heat treatment parameters depends also on the yield strength increase due to precipitation effect of ε C u phase. The regression analysis has been used to establish equations taking into account those parameters. The properties of a mixed microstructure formed from partially austenitic regions have been also considered. The fine austenitic grains transform into more desirable fine bainitic ferrite phases with lower hardness values and higher toughness. On the other hand, if cooling rate is sufficiently large, then the carbon enriched austenite transforms partially into hard martensite and some of remaining untransformed austenite being retained to ambient temperature. Because hard martensite islands are located in much softer surroundings consisting of tempered ferrite, they do not cause a general reduction in impact toughness tests. Due to further grain refinement of microstructure the measured toughness on Charpy V specimens can be very high at low temperatures. The very detrimental effect of sulphur in ULCB steel has been confirmed by presented results. (author)

  5. Noise Reduction Effect of Multiple-Sampling-Based Signal-Readout Circuits for Ultra-Low Noise CMOS Image Sensors

    Directory of Open Access Journals (Sweden)

    Shoji Kawahito

    2016-11-01

    Full Text Available This paper discusses the noise reduction effect of multiple-sampling-based signal readout circuits for implementing ultra-low-noise image sensors. The correlated multiple sampling (CMS technique has recently become an important technology for high-gain column readout circuits in low-noise CMOS image sensors (CISs. This paper reveals how the column CMS circuits, together with a pixel having a high-conversion-gain charge detector and low-noise transistor, realizes deep sub-electron read noise levels based on the analysis of noise components in the signal readout chain from a pixel to the column analog-to-digital converter (ADC. The noise measurement results of experimental CISs are compared with the noise analysis and the effect of noise reduction to the sampling number is discussed at the deep sub-electron level. Images taken with three CMS gains of two, 16, and 128 show distinct advantage of image contrast for the gain of 128 (noise(median: 0.29 e−rms when compared with the CMS gain of two (2.4 e−rms, or 16 (1.1 e−rms.

  6. Creation of the first ultra-low gluten barley (Hordeum vulgare L.) for coeliac and gluten-intolerant populations.

    Science.gov (United States)

    Tanner, Gregory J; Blundell, Malcolm J; Colgrave, Michelle L; Howitt, Crispin A

    2016-04-01

    Coeliac disease is a well-defined condition that is estimated to affect approximately 1% of the population worldwide. Noncoeliac gluten sensitivity is a condition that is less well defined, but is estimated to affect up to 10% of the population, and is often self-diagnosed. At present, the only remedy for both conditions is a lifelong gluten-free diet. A gluten-free diet is often expensive, high in fat and low in fibre, which in themselves can lead to adverse health outcomes. Thus, there is an opportunity to use novel plant breeding strategies to develop alternative gluten-free grains. In this work, we describe the breeding and characterization of a novel ultra-low gluten (ULG) barley variety in which the hordein (gluten) content was reduced to below 5 ppm. This was achieved using traditional breeding strategies to combine three recessive alleles, which act independently of each other to lower the hordein content in the parental varieties. The grain of the initial variety was shrunken compared to wild-type barleys. We implemented a breeding strategy to improve the grain size to near wild-type levels and demonstrated that the grains can be malted and brewed successfully. The ULG barley has the potential to provide novel healthy foods and beverages for those who require a gluten-free diet. © 2015 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

  7. Efficient decomposition of formaldehyde at room temperature over Pt/honeycomb ceramics with ultra-low Pt content.

    Science.gov (United States)

    Nie, Longhui; Zheng, Yingqiu; Yu, Jiaguo

    2014-09-14

    Pt/honeycomb ceramic (Pt/HC) catalysts with ultra-low Pt content (0.005-0.055 wt%) were for the first time prepared by an impregnation of honeycomb ceramics with Pt precursor and NaBH4-reduction combined method. The microstructures, morphologies and textural properties of the resulting samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The obtained Pt/HC catalysts were used for catalytic oxidative decomposition of formaldehyde (HCHO) at room temperature. It was found that the as-prepared Pt/HC catalysts can efficiently decompose HCHO in air into CO2 and H2O at room temperature. The catalytic activity of the Pt/HC catalysts increases with increasing the Pt loading in the range of 0.005-0.013 wt%, and the further increase of the Pt loading does not obviously improve catalytic activity. From the viewpoint of cost and catalytic performance, 0.013 wt% Pt loading is the optimal Pt loading amount, and the Pt/HC catalyst with 0.013 wt% Pt loading also exhibited good catalytic stability. Considering practical applications, this work will provide new insights into the low-cost and large-scale fabrication of advanced catalytic materials for indoor air purification.

  8. Extraction of ultra-low-energy antiprotons from the PS200 catching trap for atomic physics experiments

    International Nuclear Information System (INIS)

    Holzscheiter, M.H.

    1996-01-01

    Approximately one million antiprotons have been captured in a large-scale Penning trap at the low energy antiproton ring at CERN. Up to 65% of the captured antiprotons have subsequently been cooled by electron cooling to energies below 1 eV and have been stored up to one hour. This has opened new discussions of the possible use of ultra-low-energy antiprotons for nuclear, atomic, and gravitational physics. For most of these experiments it will be necessary to extract the antiprotons from the trap in the form of either a continuous beam or as a bunched beam, allowing the timing structure to be used for post-acceleration schemes or as a time tag for subsequent measurements. We have designed an extraction scheme to accomplish this and have tested portions of it using a smaller-scale Penning trap loaded with protons. First results in generating a time-correlated beam of particles from a Penning trap are presented. (orig.)

  9. Cleanliness of Ti-bearing Al-killed ultra-low-carbon steel during different heating processes

    Science.gov (United States)

    Guo, Jian-long; Bao, Yan-ping; Wang, Min

    2017-12-01

    During the production of Ti-bearing Al-killed ultra-low-carbon (ULC) steel, two different heating processes were used when the converter tapping temperature or the molten steel temperature in the Ruhrstahl-Heraeus (RH) process was low: heating by Al addition during the RH decarburization process and final deoxidation at the end of the RH decarburization process (process-I), and increasing the oxygen content at the end of RH decarburization, heating and final deoxidation by one-time Al addition (process-II). Temperature increases of 10°C by different processes were studied; the results showed that the two heating processes could achieve the same heating effect. The T.[O] content in the slab and the refining process was better controlled by process-I than by process-II. Statistical analysis of inclusions showed that the numbers of inclusions in the slab obtained by process-I were substantially less than those in the slab obtained by process-II. For process-I, the Al2O3 inclusions produced by Al added to induce heating were substantially removed at the end of decarburization. The amounts of inclusions were substantially greater for process-II than for process-I at different refining stages because of the higher dissolved oxygen concentration in process-II. Industrial test results showed that process-I was more beneficial for improving the cleanliness of molten steel.

  10. Ultra-Low Voltage Sixth-Order Low Pass Filter for Sensing the T-Wave Signal in ECGs

    Directory of Open Access Journals (Sweden)

    Panagiotis Bertsias

    2014-11-01

    Full Text Available An ultra-low voltage sixth-order low pass filter topology, suitable for sensing the T-wave signal in an electrocardiogram (ECG, is presented in this paper. This is realized using a cascade connection of second-order building blocks constructed from a sinh-domain two-integrator loop. The performance of the filter has been evaluated using the Cadence Analog Design Environment and the design kit provided by the Austria Mikro Systeme (AMS 0.35-µm CMOS process. The power consumption of filters was 7.21 nW, while a total harmonic distortion (THD level of 4% was observed for an input signal of 220 pA. The RMS value of the input referred noise was 0.43 pA, and the simulated value of the dynamic range (DR was 51.1 dB. A comparison with already published counterparts shows that the proposed topology offers the benefits of 0.5-V supply voltage operation and significantly improved power efficiency.

  11. Ultra-low input transcriptomics reveal the spore functional content and phylogenetic affiliations of poorly studied arbuscular mycorrhizal fungi.

    Science.gov (United States)

    Beaudet, Denis; Chen, Eric C H; Mathieu, Stephanie; Yildirir, Gokalp; Ndikumana, Steve; Dalpé, Yolande; Séguin, Sylvie; Farinelli, Laurent; Stajich, Jason E; Corradi, Nicolas

    2017-12-02

    Arbuscular mycorrhizal fungi (AMF) are a group of soil microorganisms that establish symbioses with the vast majority of land plants. To date, generation of AMF coding information has been limited to model genera that grow well axenically; Rhizoglomus and Gigaspora. Meanwhile, data on the functional gene repertoire of most AMF families is non-existent. Here, we provide primary large-scale transcriptome data from eight poorly studied AMF species (Acaulospora morrowiae, Diversispora versiforme, Scutellospora calospora, Racocetra castanea, Paraglomus brasilianum, Ambispora leptoticha, Claroideoglomus claroideum and Funneliformis mosseae) using ultra-low input ribonucleic acid (RNA)-seq approaches. Our analyses reveals that quiescent spores of many AMF species harbour a diverse functional diversity and solidify known evolutionary relationships within the group. Our findings demonstrate that RNA-seq data obtained from low-input RNA are reliable in comparison to conventional RNA-seq experiments. Thus, our methodology can potentially be used to deepen our understanding of fungal microbial function and phylogeny using minute amounts of RNA material. © The Author 2017. Published by Oxford University Press on behalf of Kazusa DNA Research Institute.

  12. Particulate emissions from a stationary engine fueled with ultra-low-sulfur diesel and waste-cooking-oil-derived biodiesel.

    Science.gov (United States)

    Betha, Raghu; Balasubramanian, Rajasekhar

    2011-10-01

    Stationary diesel engines, especially diesel generators, are increasingly being used in both developing countries and developed countries because of increased power demand. Emissions from such engines can have adverse effects on the environment and public health. In this study, particulate emissions from a domestic stationary diesel generator running on ultra-low-sulfur diesel (ULSD) and biodiesel derived from waste cooking oil were characterized for different load conditions. Results indicated a reduction in particulate matter (PM) mass and number emissions while switching diesel to biodiesel. With increase in engine load, it was observed that particle mass increased, although total particle counts decreased for all the fuels. The reduction in total number concentration at higher loads was, however, dependent on percentage of biodiesel in the diesel-biodiesel blend. For pure biodiesel (B100), the reduction in PM emissions for full load compared to idle mode was around 9%, whereas for ULSD the reduction was 26%. A large fraction of ultrafine particles (UFPs) was found in the emissions from biodiesel compared to ULSD. Nearly 90% of total particle concentration in biodiesel emissions comprised ultrafine particles. Particle peak diameter shifted from a smaller to a lower diameter with increase in biodiesel percentage in the fuel mixture.

  13. Enhanced activity and interfacial durability study of ultra low Pt based electrocatalysts prepared by ion beam assisted deposition (IBAD) method

    International Nuclear Information System (INIS)

    Ramaswamy, N.; Arruda, T.M.; Wen, W.; Hakim, N.; Saha, M.; Gulla, A.; Mukerjee, S.

    2009-01-01

    Ultra low loading noble metal (0.04-0.12 mg Pt /cm 2 ) based electrodes were obtained by direct metallization of non-catalyzed gas diffusion layers via dual ion beam assisted deposition (IBAD) method. Fuel cell performance results reported earlier indicate significant improvements in terms of mass specific power density of 0.297 g Pt /kW with 250 A thick IBAD deposit (0.04 mg Pt /cm 2 for a total MEA loading of 0.08 mg Pt /cm 2 ) at 0.65 V in contrast to the state of the art power density of 1.18 g Pt /kW using 1 mg Pt(MEA) /cm 2 at 0.65 V. In this article we report the peroxide radical initiated attack of the membrane electrode assembly utilizing IBAD electrodes in comparison to commercially available E-TEK (now BASF Fuel Cell GmbH) electrodes and find the pathway of membrane degradation as well. A novel segmented fuel cell is used for this purpose to relate membrane degradation to peroxide generation at the electrode/electrolyte interface by means of systematic pre and post analyses of the membrane are presented. Also, we present the results of in situ X-ray absorption spectroscopy (XAS) experiments to elucidate the structure/property relationships of these electrodes that lead to superior performance in terms of gravimetric power density obtained during fuel cell operation.

  14. Ultra-low-energy ion-beam synthesis of nanometer-separated Si nanoparticles and Ag nanocrystals 2D layers

    Science.gov (United States)

    Carrada, M.; Haj Salem, A.; Pecassou, B.; Paillard, V.; Ben Assayag, G.

    2018-03-01

    2D networks of Si and Ag nanocrystals have been fabricated in the same SiO2 matrix by Ultra-Low-Energy Ion-Beam-Synthesis. Our synthesis scheme differs from a simple sequential ion implantation and its key point is the control of the matrix integrity through an appropriate intermediate thermal annealing. Si nanocrystal layer is synthesised first due to high thermal budget required for nucleation, while the second Ag nanocrystal plane is formed during a subsequent implantation due to the high diffusivity of Ag in silica. The aim of this work is to show how it is possible to overcome the limitation related to ion mixing and implantation damage to obtain double layers of Si-NCs and Ag-NCs with controlled characteristics. For this, we take advantage of annealing under slight oxidizing ambient to control the oxidation of Si-NCs and the Si excess in the matrix. The nanocrystal characteristics and in particular their position and size can be adjusted thanks to a compromise between the implantation energy, the implanted dose for both Si and Ag ions and the intermediate annealing conditions (atmosphere, temperature and duration).

  15. Design of a birefringent Michelson interferometer-based interleaver with ultra-low dispersion and low cost.

    Science.gov (United States)

    Hu, Haocheng; Zheng, Baozhong; Liu, Qingming; Li, Yang; Wu, Li; Gu, Shijie

    2011-11-21

    We design and demonstrate a birefringent Michelson interferometer based interleaver with ultra-low dispersion and low cost. The interleaver consists of polarizing beam splitters (PBS's) and quarter-wave plates and half-wave plates. The PBS's based Michelson interferometers provide the optical path difference for interference between the two orthogonal polarization components and the half-wave plates provide the birefringent needed to minimize ripple of output. The designed interleaver with two-stage interferometer in a 50 GHz channel spacing application exhibits a 0.5 dB passband and a 25 dB stopband both 27 GHz; a channel isolation higher than 35 dB and chromatic dispersion less than ±5 ps/nm within 0.5 dB passband; 1.3 dB insertion loss and 0.3 dB PDL; 0.04 GHz/°C thermal stability. Since all of the optical components can be optically bonded together, the device is robust and easy to be aligned, which reduces labor cost. © 2011 Optical Society of America

  16. Regeneration of volatile compounds in Fuji apples following ultra low oxygen atmosphere storage and its effect on sensory acceptability.

    Science.gov (United States)

    Altisent, Rosa; Graell, Jordi; Lara, Isabel; López, Luisa; Echeverría, Gemma

    2008-09-24

    The aim of this work was to assess whether extra time spent under AIR conditions after storage in an ultra low oxygen (ULO) atmosphere could allow the regeneration of volatile compound emission without negatively affecting quality parameters and the consumer acceptability of Fuji apples. Fruits were stored for 19 and 30 weeks at 1 degrees C and 92% RH under ULO atmosphere conditions (1 kPa O 2:1 kPa CO 2) or under ULO conditions followed by different periods (2 and 4 weeks) in cold AIR atmosphere (ULO + 2w or ULO + 4w, respectively). Standard quality and emission of volatile compounds were analyzed after storage plus 1 and 7 days at 20 degrees C. Sensory attributes and acceptability were also determined after 7 days at 20 degrees C. The extra period of 30 weeks in an AIR atmosphere after ULO storage resulted in an increase in the concentration of the compounds that most contribute to the flavor of Fuji apples. These fruits were relatively well accepted by consumers despite a slight decline in firmness and acidity.

  17. Dopant redistribution and electrical activation in silicon following ultra-low energy boron implantation and excimer laser annealing

    International Nuclear Information System (INIS)

    Whelan, S.; La Magna, A.; Privitera, V.; Mannino, G.; Italia, M.; Bongiorno, C.; Fortunato, G.; Mariucci, L.

    2003-01-01

    Excimer laser annealing (ELA) of ultra-low-energy (ULE) B-ion implanted Si has been performed. High-resolution transmission electron microscopy has been used to assess the as-implanted damage and the crystal recovery following ELA. The electrical activation and redistribution of B in Si during ELA has been investigated as a function of the laser energy density (melted depth), the implant dose, and the number of laser pulses (melt time). The activated and retained dose has been evaluated with spreading resistance profiling and secondary ion mass spectrometry. A significant amount of the implanted dopant was lost from the sample during ELA. However, the dopant that was retained in crystal material was fully activated following rapid resolidification. At an atomic concentration below the thermodynamic limit, the activation efficiency (dose activated/dose implanted into Si material) was a constant for a fixed melt depth, irrespective of the dose implanted and hence the total activated dose was raised as the implant dose was increased. The electrical activation was increased for high laser energy density annealing when the dopant was redistributed over a deeper range

  18. CalMagNet – an array of search coil magnetometers monitoring ultra low frequency activity in California

    Directory of Open Access Journals (Sweden)

    C. Dunson

    2008-04-01

    Full Text Available The California Magnetometer Network (CalMagNet consists of sixty-eight triaxial search-coil magnetometer systems measuring Ultra Low Frequency (ULF, 0.001–16 Hz, magnetic field fluctuations in California. CalMagNet provides data for comprehensive multi-point measurements of specific events in the Pc 1–Pc 5 range at mid-latitudes as well as a systematic, long-term study of ULF signals in active fault regions in California. Typical events include geomagnetic micropulsations and spectral resonant structures associated with the ionospheric Alfvén resonator. This paper provides a technical overview of the CalMagNet sensors and data processing systems. The network is composed of ten reference stations and fifty-eight local monitoring stations. The primary instruments at each site are three orthogonal induction coil magnetometers. A geophone monitors local site vibration. The systems are designed for future sensor expansion and include resources for monitoring four additional channels. Data is currently sampled at 32 samples per second with a 24-bit converter and time tagged with a GPS-based timing system. Several examples of representative magnetic fluctuations and signals as measured by the array are given.

  19. Film Permeability Determination Using Static Permeability Cells

    Science.gov (United States)

    The permeability of tarps to soil fumigant pesticides varies depending on the active ingredient chemical: dimethyl disulfide (DMDS), methyl bromide, chloropicrin, or other. The diffusion rate can be represented by the mass transfer coefficient (MTC).

  20. Reservoir model for the Alameda Central waterflood

    Energy Technology Data Exchange (ETDEWEB)

    Randall, T E

    1968-01-01

    The basic approach used in developing the model to characterize the Alameda Central Unit Waterflood assumes continuity of the reservoir mechanics with time. The past performance was analyzed to describe the reservoir and future performance was assumed to follow the established patterns. To develop a mathematical picture of the Alameda Central Unit reservoir, a two-dimensional single-phase steady-state model was used in conjunction with material balance calculations, real-time conversion methods and oil-water interface advance calculations. The model was developed to optimize water injection allocation, determine the configuration of the frontal advance and evaluate the success of the waterflood. The model also provides a basis for continuing review and revision of the basic concepts of reservoir operation. The results of the reservoir study have confirmed the apparent lack of permeability orientation in the pool and indicate that the waterflood is progressing better than originally anticipated.

  1. Reservoir Models for Gas Hydrate Numerical Simulation

    Science.gov (United States)

    Boswell, R.

    2016-12-01

    Scientific and industrial drilling programs have now providing detailed information on gas hydrate systems that will increasingly be the subject of field experiments. The need to carefully plan these programs requires reliable prediction of reservoir response to hydrate dissociation. Currently, a major emphasis in gas hydrate modeling is the integration of thermodynamic/hydrologic phenomena with geomechanical response for both reservoir and bounding strata. However, also critical to the ultimate success of these efforts is the appropriate development of input geologic models, including several emerging issues, including (1) reservoir heterogeneity, (2) understanding of the initial petrophysical characteristics of the system (reservoirs and seals), the dynamic evolution of those characteristics during active dissociation, and the interdependency of petrophysical parameters and (3) the nature of reservoir boundaries. Heterogeneity is ubiquitous aspect of every natural reservoir, and appropriate characterization is vital. However, heterogeneity is not random. Vertical variation can be evaluated with core and well log data; however, core data often are challenged by incomplete recovery. Well logs also provide interpretation challenges, particularly where reservoirs are thinly-bedded due to limitation in vertical resolution. This imprecision will extend to any petrophysical measurements that are derived from evaluation of log data. Extrapolation of log data laterally is also complex, and should be supported by geologic mapping. Key petrophysical parameters include porosity, permeability and it many aspects, and water saturation. Field data collected to date suggest that the degree of hydrate saturation is strongly controlled by/dependant upon reservoir quality and that the ratio of free to bound water in the remaining pore space is likely also controlled by reservoir quality. Further, those parameters will also evolve during dissociation, and not necessary in a simple

  2. Simulation study on AlGaN/GaN diode with Γ-shaped anode for ultra-low turn-on voltage

    Science.gov (United States)

    Wang, Zeheng; Chen, Wanjun; Wang, Fangzhou; Cao, Jun; Sun, Ruize; Ren, Kailin; Luo, Yi; Guo, Songnan; Wang, Zirui; Jin, Xiaosheng; Yang, Lei; Zhang, Bo

    2018-05-01

    An ultra-low turn-on voltage (VT) Γ-shaped anode AlGaN/GaN Schottky barrier diode (GA-SBD) is proposed via modeling and simulation for the first time, in which a Γ-shaped anode consists of a metal-2DEG junction together with a metal-AlGaN junction beside a shallowly recessed MIS field plate (MFP). An analytic forward current-voltage model matching the simulation results well is presented where an ultra-low VT of 0.08 V is obtained. The turn-on and blocking mechanisms are investigated to reveal the GA-SBD's great potential for applications of highly efficient power ICs.

  3. Characterization of enzymatically induced aggregation of casein micelles in natural concentration by in situ static light scattering and ultra low shear viscosimetry

    DEFF Research Database (Denmark)

    Lehner, D.; Worning, Peder; G, Fritz

    1999-01-01

    of multiple scattering whenthe transmission is above 0.85. Due to the very complex and porous structure of the casein aggregates theRayleigh-Debye-Gans scattering theory has been used in the data analysis. Measurements with a newinstrument using ultra low shear showed good agreement with theory. Copyright......The aggregation of casein micelles in undiluted skim milk after the addition of chymosin was studied bystatic light scattering and ultra low shear viscometry. The static light scattering measurements were madewith two different sample thicknesses, 72 and 16 mum. The scattering data were analyzed...... by indirect Fouriertransformation and by the polydispersity inversion technique which led to pair distance distributionfunctions and size distribution function, respectively. The minimum scattering angle was 1 degrees, whichallows for the determination of particle sizes up to a maximum diameter of 12 mum...

  4. Improvement of spin-exchange optical pumping of xenon-129 using in situ NMR measurement in ultra-low magnetic field

    Science.gov (United States)

    Takeda, Shun; Kumagai, Hiroshi

    2018-02-01

    Hyperpolarized (HP) noble gas has attracted attention in NMR / MRI. In an ultra-low magnetic field, the effectiveness of signal enhancement by HP noble gas should be required because reduction of the signal intensity is serious. One method of generating HP noble gas is spin exchange optical pumping which uses selective excitation of electrons of alkali metal vapor and spin transfer to nuclear spin by collision to noble gas. Although SEOP does not require extreme cooling or strong magnetic field, generally it required large-scale equipment including high power light source to generate HP noble gas with high efficiency. In this study, we construct a simply generation system of HP xenon-129 by SEOP with an ultralow magnetic field (up to 1 mT) and small-scale light source (about 1W). In addition, we measure in situ NMR signal at the same time, and then examine efficient conditions for SEOP in ultra-low magnetic fields.

  5. Experimental verification of a novel MEMS multi-modal vibration energy harvester for ultra-low power remote sensing nodes

    Science.gov (United States)

    Iannacci, J.; Sordo, G.; Serra, E.; Kucera, M.; Schmid, U.

    2015-05-01

    In this work, we discuss the verification and preliminary experimental characterization of a MEMS-based vibration Energy Harvester (EH) design. The device, named Four-Leaf Clover (FLC), is based on a circular-shaped mechanical resonator with four petal-like mass-spring cascaded systems. This solution introduces several mechanical Degrees of Freedom (DOFs), and therefore enables multiple resonant modes and deformation shapes in the vibrations frequency range of interest. The target is to realize a wideband multi-modal EH-MEMS device, that overcomes the typical narrowband working characteristics of standard cantilevered EHs, by ensuring flexible and adaptable power source to ultra-low power electronics for integrated remote sensing nodes (e.g. Wireless Sensor Networks - WSNs) in the Internet of Things (IoT) scenario, aiming to self-powered and energy autonomous smart systems. Finite Element Method simulations of the FLC EH-MEMS show the presence of several resonant modes for vibrations up to 4-5 kHz, and level of converted power up to a few μW at resonance and in closed-loop conditions (i.e. with resistive load). On the other hand, the first experimental tests of FLC fabricated samples, conducted with a Laser Doppler Vibrometer (LDV), proved the presence of several resonant modes, and allowed to validate the accuracy of the FEM modeling method. Such a good accordance holds validity for what concerns the coupled field behavior of the FLC EH-MEMS, as well. Both measurements and simulations performed at 190 Hz (i.e. out of resonance) showed the generation of power in the range of nW (Root Mean Square - RMS values). Further steps of this work will include the experimental characterization in a full range of vibrations, aiming to prove the whole functionality of the FLC EH-MEMS proposed design concept.

  6. Heart rate variability at limiting stationarity: evidence of neuro-cardiac control mechanisms operating at ultra-low frequencies

    International Nuclear Information System (INIS)

    Fisher, A C; Groves, D; Eleuteri, A; Mesum, P; Patterson, D; Taggart, P

    2014-01-01

    This study considers the linkage of exogenously stimulated emotional stress with the neurogenic regulation of heart rate operating at very low frequencies. The objectives were three-fold: to consider the present evidence that such a linkage exists as a primary phenomenon; to compare the potential of a frequency-domain method and a time-domain method in revealing this phenomenon by characterizing heart rate variability (HRV) at frequencies of [0.0005…0.4] Hz and to design, implement and report a physiological experiment in which alternating periods of exposure to bland and high valence visual stimuli might reveal this phenomenon. A methodical challenge was to optimize the length of exposure to the stimulus such that subjects did not have time to habituate to stimuli, whilst acquiring sufficient data (heart beats) such that the ultra-low frequency (ULF) components of HRV could be described. With exposure times set to approximately 5 min, during which time the strength of the stimulus and the corresponding evoked response were considered stationary, the lowest HRV frequency component that could be characterized was 0.003 Hz. In trials with parametrically defined test data, the time-domain method based on the Ornstein–Uhlenbeck Gaussian process (OU-GP) was shown to be better than the frequency-domain method in describing the ULF components of the HRV. In an experimental cohort of 16 subjects, analysis using the OU-GP revealed evidence of cardiac regulatory mechanisms influenced by emotional valence operating in the bandwidth (ULF*) [0.002…0.01] Hz. (paper)

  7. A regression-based differential expression detection algorithm for microarray studies with ultra-low sample size.

    Directory of Open Access Journals (Sweden)

    Daniel Vasiliu

    Full Text Available Global gene expression analysis using microarrays and, more recently, RNA-seq, has allowed investigators to understand biological processes at a system level. However, the identification of differentially expressed genes in experiments with small sample size, high dimensionality, and high variance remains challenging, limiting the usability of these tens of thousands of publicly available, and possibly many more unpublished, gene expression datasets. We propose a novel variable selection algorithm for ultra-low-n microarray studies using generalized linear model-based variable selection with a penalized binomial regression algorithm called penalized Euclidean distance (PED. Our method uses PED to build a classifier on the experimental data to rank genes by importance. In place of cross-validation, which is required by most similar methods but not reliable for experiments with small sample size, we use a simulation-based approach to additively build a list of differentially expressed genes from the rank-ordered list. Our simulation-based approach maintains a low false discovery rate while maximizing the number of differentially expressed genes identified, a feature critical for downstream pathway analysis. We apply our method to microarray data from an experiment perturbing the Notch signaling pathway in Xenopus laevis embryos. This dataset was chosen because it showed very little differential expression according to limma, a powerful and widely-used method for microarray analysis. Our method was able to detect a significant number of differentially expressed genes in this dataset and suggest future directions for investigation. Our method is easily adaptable for analysis of data from RNA-seq and other global expression experiments with low sample size and high dimensionality.

  8. The use of ultra-low-energy dynamic SIMS in the study of the tarnishing of silver

    International Nuclear Information System (INIS)

    Dowsett, M.G.; Adriaens, A.; Soares, M.; Wouters, H.; Palitsin, V.V.N.; Gibbons, R.; Morris, R.J.H.

    2005-01-01

    This paper describes a new application in cultural heritage and other areas for a highly surface specific analytical technique originally developed for semiconductor research. The technique, ultra-low-energy dynamic secondary ion mass spectrometry (uleSIMS), is microdestructive, but has a sensitivity typically better than 1 atom in 10 6 . It can provide an analysis within the top nm, or the top few μm of a surface, and gives chemical fingerprinting as well as atomic composition information. It is complimentary to other near-surface techniques such as SEM-EDX, XRD and electrochemical methods. Here, we describe the use of uleSIMS with SEM and SEM-EDX in a study of the tarnishing of museum silver. We report on the initial stages in the development of reference surfaces for control experiments, and on the data obtained from a lightly tarnished sterling silver test coupon exposed in a museum environment for 2 years. First results from a study of a XVII c. silver fragment, aimed at detecting differences in the tarnish or coating in different areas are also presented. Overall we show that the surface chemistry of all these surfaces is a complex mixture of that due to corrosion, contaminants deposited by solvents, polish media (in an overlayer which may only be a few nm thick), handling and the environment, as well as particulates - both from the environment and from polishes. However, surfaces with different histories show large variations in their uleSIMS spectra and depth profiles, and we attempt to lay the groundwork for the interpretation of these

  9. Effects of truck-mounted, ultra low volume mosquito adulticides on honey bees (Apis mellifera) in a suburban field setting

    Science.gov (United States)

    DeLisi, Nicholas A.; Danka, Robert G.; Walker, Todd W.; Ottea, James A.; Healy, Kristen B.

    2018-01-01

    Few studies have examined the impact of mosquito adulticides on honey bees under conditions that reflect actual field exposure. Whereas several studies have evaluated the toxicity of mosquito control products on honey bees, most have been laboratory based and have focused solely on acute mortality as a measure of impact. The goal of this study was to determine effects of routine applications of truck-based ultra-low volume (ULV) mosquito adulticides (i.e., Scourge, Duet, and Deltagard) on honey bees in a suburban setting. The mosquito adulticides used in this study were pyrethroids with active ingredients resmethrin (Scourge), prallethrin and sumithrin (Duet), and deltamethrin (Deltagard), in which resmethrin, prallethrin, and sumithrin were synergized with piperonyl butoxide. We measured and compared mortality and detoxification enzyme activities (esterase and glutathione S-transferase) from sentinel beehives within and outside of mosquito control areas. Concurrently, colony health (i.e., number of adult bees, brood quantity and brood quality) was compared throughout the study period. No significant differences were observed in honey bee mortality, colony health or detoxification enzyme activities between treated (five sprayed areas each received one to three insecticide treatment) and control sites (four unsprayed areas that did not receive insecticide treatment) over the seven week study period. However, our laboratory study showed that exposure to resmethrin, the active ingredient in Scourge, caused significant inhibition of esterase activity compared with the control group. Our findings suggest that proper application of truck based insecticides for mosquito control results in little or no exposure and therefore minimal effects on domestic honey bees. PMID:29494661

  10. Ultra-low noise supercontinuum source for ultra-high resolution optical coherence tomography at 1300 nm

    Science.gov (United States)

    Gonzalo, I. B.; Maria, M.; Engelsholm, R. D.; Feuchter, T.; Leick, L.; Moselund, P. M.; Podoleanu, A.; Bang, O.

    2018-02-01

    Supercontinuum (SC) sources are of great interest for many applications due to their ultra-broad optical bandwidth, good beam quality and high power spectral density [1]. In particular, the high average power over large bandwidths makes SC light sources excellent candidates for ultra-high resolution optical coherence tomography (UHR-OCT) [2-5]. However, conventional SC sources suffer from high pulse-to-pulse intensity fluctuations as a result of the noise-sensitive nonlinear effects involved in the SC generation process [6-9]. This intensity noise from the SC source can limit the performance of OCT, resulting in a reduced signal-to-noise ratio (SNR) [10-12]. Much work has been done to reduce the noise of the SC sources for instance with fiber tapers [7,8] or increasing the repetition rate of the pump laser for averaging in the spectrometer [10,12]. An alternative approach is to use all-normal dispersion (ANDi) fibers [13,14] to generate SC light from well-known coherent nonlinear processes [15-17]. In fact, reduction of SC noise using ANDi fibers compared to anomalous dispersion SC pumped by sub-picosecond pulses has been recently demonstrated [18], but a cladding mode was used to stabilize the ANDi SC. In this work, we characterize the noise performance of a femtosecond pumped ANDi based SC and a commercial SC source in an UHR-OCT system at 1300 nm. We show that the ANDi based SC presents exceptional noise properties compared to a commercial source. An improvement of 5 dB in SNR is measured in the UHR-OCT system, and the noise behavior resembles that of a superluminiscent diode. This preliminary study is a step forward towards development of an ultra-low noise SC source at 1300 nm for ultra-high resolution OCT.

  11. Instrument for all-fiber structure measurement of ultra-low turbidity by using single photon detection technique

    Science.gov (United States)

    Qin, Feihu; Hu, Juntao; Wang, Huanqin; Gui, Huaqiao; Liu, Jianguo; Lü, Liang; Kong, Deyi; Zhang, Jian; Han, Xia; Wang, Tianli

    2017-10-01

    An all-fiber structure detection system based on single photon detection technique(SPDT) has been developed to measure the ultra-low turbidity ofliquids. To assure the measurement accuracy,the total intensity of transmission light has been detected and quantified as number of photons by avalanche photodiode (APD) which has the advantage of high sensitivity.A fresh all-fiber structure optical fiber probe based on SPDT is applied in the system to reduce the volume and fluctuation of traditional transmission-light measurement system,in which the all-fiber structure probe is used to delivery and collection of transmission light.On the basis of Beer-Lambert (B-L) transmission law,a test system has been established and carried out a series of experiments.By combining B-Llaw with the principle of SPDT,a novel model for detecting turbidity has been proposed to explain the experimental results.The results have shown a well exponential relationship over the range of 0.01-1NTU (Nephelometric Turbidity Units).It also has showna good linear relationship with a resolution as high as 0.01NTUin the range of 0.01-0.09 NTU.When it is 1 secondofthe sampling time,the mean error of measurement result can be controlled within 5% of full scale.In addition,the new detection structure proposed in this paper, which makes the system more compact and more suitable in the small special space.

  12. Impact of image denoising on image quality, quantitative parameters and sensitivity of ultra-low-dose volume perfusion CT imaging

    International Nuclear Information System (INIS)

    Othman, Ahmed E.; Brockmann, Carolin; Afat, Saif; Pjontek, Rastislav; Nikoubashman, Omid; Brockmann, Marc A.; Wiesmann, Martin; Yang, Zepa; Kim, Changwon; Nikolaou, Konstantin; Kim, Jong Hyo

    2016-01-01

    To examine the impact of denoising on ultra-low-dose volume perfusion CT (ULD-VPCT) imaging in acute stroke. Simulated ULD-VPCT data sets at 20 % dose rate were generated from perfusion data sets of 20 patients with suspected ischemic stroke acquired at 80 kVp/180 mAs. Four data sets were generated from each ULD-VPCT data set: not-denoised (ND); denoised using spatiotemporal filter (D1); denoised using quanta-stream diffusion technique (D2); combination of both methods (D1 + D2). Signal-to-noise ratio (SNR) was measured in the resulting 100 data sets. Image quality, presence/absence of ischemic lesions, CBV and CBF scores according to a modified ASPECTS score were assessed by two blinded readers. SNR and qualitative scores were highest for D1 + D2 and lowest for ND (all p ≤ 0.001). In 25 % of the patients, ND maps were not assessable and therefore excluded from further analyses. Compared to original data sets, in D2 and D1 + D2, readers correctly identified all patients with ischemic lesions (sensitivity 1.0, kappa 1.0). Lesion size was most accurately estimated for D1 + D2 with a sensitivity of 1.0 (CBV) and 0.94 (CBF) and an inter-rater agreement of 1.0 and 0.92, respectively. An appropriate combination of denoising techniques applied in ULD-VPCT produces diagnostically sufficient perfusion maps at substantially reduced dose rates as low as 20 % of the normal scan. (orig.)

  13. Development of Search-Coil Magnetometer for Ultra Low Frequency (ULF) Wave Observations at Jang Bogo Station in Antarctica

    Science.gov (United States)

    Lee, J. K.; Shin, J.; Kim, K. H.; Jin, H.; Kim, H.; Kwon, J.; Lee, S.; Jee, G.; Lessard, M.

    2016-12-01

    A ground-based bi-axial search-coil magnetometer (SCM) has been devloped for observation of time-varying magnetic fields (dB/dt) in the Ultra Low Frequency (ULF) range (a few mHz up to 5 Hz) to understand magnetosphere-ionosphere coupling processes. The SCM consists of magnetic sensors, analog electronics, cables and data acquisition system (DAQ). The bi-axial magnetic sensor has coils of wire wound around a mu-metal cores, each of which measures magnetic field pulsations in the horizontal components, geomagnetic north-south and east-west, respectively. The analog electronics is designed to control the cut-off frequency of the instrument and to amplify detected signals. The DAQ has a 16 bit analog to digital converter (ADC) at the user defined rate of 10 Hz. It is also equipped with the Global Positioning System (GPS) and Network Time Protocol (NTP) for time synchronization and accuracy. We have carried out in-lab performance tests (e.g., frequency response, noise level, etc) using a magnetically shielded case and a field-test in a magnetically quiet location in South Korea. During the field test, a ULF Pi 2 event has been observed clearly. We also confirmed that it was a substorm activity from a fluxgate magnetometer data at Mineyama (35°57.3'N, 135°05'E, geographic). The SCM will be installed and operated at Jang Bogo Antarctic Research Station (74°37.4'S, 164°13.7'E, geographic) on Dec. 2016. The geomagnetic latitude of the station is similar to that of the US McMurdo station (77°51'S, 166°40'E, geographic), both of which are typically near the cusp region. Thus, we expect that the SCM can provide useful information to understand ULF wave propagation characteristics.

  14. Diagnostic Performance of Ultra-Low-Dose Computed Tomography for Detecting Asbestos-Related Pleuropulmonary Diseases: Prospective Study in a Screening Setting

    OpenAIRE

    Schaal, Marysa; Severac, Fran?ois; Labani, Aissam; Jeung, Mi-Young; Roy, Catherine; Ohana, Micka?l

    2016-01-01

    Objective To evaluate the diagnostic performance of Ultra-Low-Dose Chest CT (ULD CT) for the detection of any asbestos-related lesions (primary endpoint) and specific asbestos-related abnormalities, i.e. non-calcified and calcified pleural plaques, diffuse pleural thickening, asbestosis and significant lung nodules (secondary endpoints). Material and Methods 55 male patients (55.7?8.1 years old) with occupational asbestos exposure for at least 15 years and where CT screening was indicated wer...

  15. Permeability prediction in chalks

    DEFF Research Database (Denmark)

    Alam, Mohammad Monzurul; Fabricius, Ida Lykke; Prasad, Manika

    2011-01-01

    The velocity of elastic waves is the primary datum available for acquiring information about subsurface characteristics such as lithology and porosity. Cheap and quick (spatial coverage, ease of measurement) information of permeability can be achieved, if sonic velocity is used for permeability p...... significantly using the effective specific surface as the fluid-flow concept. The FZI unit is appropriate for highly permeable sedimentary rocks such as sandstones and limestones that have small surface areas....

  16. Coupling a fluid flow simulation with a geomechanical model of a fractured reservoir

    OpenAIRE

    Segura Segarra, José María; Paz, C.M.; de Bayser, M.; Zhang, J.; Bryant, P.W.; Gonzalez, Nubia Aurora; Rodrigues, E.; Vargas, P.E.; Carol, Ignacio; Lakshmikantha, Ramasesha Mookanahallipatna; Das, K. C.; Sandha, S.S.; Cerqueira, R.; Mello,, U.

    2013-01-01

    Improving the reliability of integrated reservoir development planning and addressing subsidence, fault reactivation and other environmental impacts, requires increasingly sophisticated geomechanical models, especially in the case of fractured reservoirs where fracture deformation is strongly coupled with its permeability change. Reservoir simulation has historically treated any geomechanical effects by means of a rock compressibility term/table, which can be improved by simulating the actual...

  17. Preparation of Ultra Low-κ Porous SiOCH Films from Ring-Type Siloxane with Unsaturated Hydrocarbon Side Chains by Spin-On Deposition

    International Nuclear Information System (INIS)

    Chun-Xiao, Yang; Chi, Zhang; Qing-Qing, Sun; Sai-Sheng, Xu; Li-Feng, Zhang; Yu, Shi; Shi-Jin, Ding; Wei, Zhang

    2010-01-01

    An ultra-low-dielectric-constant (ultra low-k, or ULK) porous SiOCH film is prepared using a single ring-type siloxane precursor of the 2,4,6,8-tetravinyl-2,4,6,8-tetramethylcyclotetrasiloxane by means of spin-on deposition, followed by crosslinking reactions between the precursor monomers under UV irradiation. The as-prepared film has an ultra low k of 2.41 at 1 MHz due to incorporation of pores and hydrocarbon crosslinkages, a leakage current density of 9.86 × 10 −7 A/cm 2 at 1 MV/cm, as well as a breakdown field strength of ∼1.5 MV/cm. Further, annealing at 300°C results in lower k (i.e., 1.94 at 1 MHz), smaller leakage current density (2.96 × 10 −7 A/cm 2 at 1 MV/cm) and higher breakdown field strength (about 3.5 MV/cm), which are likely caused by the short-ranged structural rearrangement and reduction of defects in the film. Finally, the mechanical properties and surface morphology of films are also evaluated after different temperature annealing. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  18. ACCEPTABILITY OF ULTRA LOW-DOSE ORAL CONTRACEPTIVES CONTAINING 20 µg ETHINYL ESTRADIOL AND 75 µg GESTODENE IN YOUNG FEMALES IN A MULTICENTER CLINICAL STUDY

    Directory of Open Access Journals (Sweden)

    Bojana Pinter

    2004-06-01

    Full Text Available Background. The acceptability of ultra low-dose oral contraception (OC among young females after three and six cycles of treatment was assessed.Methods. In the clinical prospective study, carried out in 10 outpatient clinics in Slovenia, 240 healthy women aged 16– 30 years choosing ultra low-dose OC (20 µg ethinyl estradiol and 75 µg gestodene were included.Results. The average age was 20.6 (± 3.5 years. After three cycles (N = 228 there were no changes in body weight or blood pressure; one tenth (9.6% of women reported irregular bleeding and 3.9% weight gain while other side effects occurred rarely. After three cycles 88.3% of the women initially included continued OC use (5% discontinued the use due to side effects. After six cycles (N = 195 there were no changes in blood pressure; body weight statistically significantly increased for 0.5 kg providing the weight changes during the time were not considered. Fewer women reported side effects (3.6% irregular bleeding, 2.6% weight gain and rarely other side effects. After six cycles 75.0% of the women initially included continued the OC use (7.5% discontinued the use due to the side effects.Conclusions. The study has shown good clinical acceptability of ultra low-dose OC by young females.

  19. Construction of an ultra low temperature cryostat and transverse acoustic spectroscopy in superfluid helium-3 in compressed aerogels

    Science.gov (United States)

    Bhupathi, Pradeep

    An ultra low temperature cryostat is designed and implemented in this work to perform experiments at sub-millikelvin temperatures, specifically aimed at understanding the superfluid phases of 3He in various scenarios. The cryostat is a combination of a dilution refrigerator (Oxford Kelvinox 400) with a base temperature of 5.2 mK and a 48 mole copper block as the adiabatic nuclear demagnetization stage with a lowest temperature of ≈ 200 muK. With the various techniques implemented for limiting the ambient heat leak to the cryostat, we were able to stay below 1 mK for longer than 5 weeks. The details of design, construction and performance of the cryostat are presented. We measured high frequency shear acoustic impedance in superfluid 3He in 98% porosity aerogel at pressures of 29 bar and 32 bar in magnetic fields upto 3 kG with the aerogel cylinder compressed along the symmetry axis to generate global anisotropy. With 5% compression, there is an indication of a supercooled A-like to B-like transition in aerogel in a wider temperature width than the A phase in the bulk, while at 10% axial compression, the A-like to B-like transition is absent on cooling down to ≈ 300 muK in zero magnetic field and in magnetic fields up to 3 kG. This behavior is in contrast to that in 3He in uncompressed aerogels, in which the supercooled A-like to B-like transitions have been identified by various experimental techniques. Our result is consistent with theoretical predictions. To characterize the anisotropy in compressed aerogels, optical birefringence is measured in 98% porosity silica aerogel samples subjected to various degrees of uniaxial compression up to 15% strain, with wavelengths between 200 to 800 nm. Uncompressed aerogels exhibit no or a minimal degree of birefringence, indicating the isotropic nature of the material over the length scale of the wavelength. Uniaxial compression of aerogel introduces global anisotropy, which produces birefringence in the material. We

  20. A high turndown, ultra low emission low swirl burner for natural gas, on-demand water heaters

    Energy Technology Data Exchange (ETDEWEB)

    Rapp, Vi H. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Cheng, Robert K. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Therkelsen, Peter L. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2017-06-13

    Previous research has shown that on-demand water heaters are, on average, approximately 37% more efficient than storage water heaters. However, approximately 98% of water heaters in the U.S. use storage water heaters while the remaining 2% are on-demand. A major market barrier to deployment of on-demand water heaters is their high retail cost, which is due in part to their reliance on multi-stage burner banks that require complex electronic controls. This project aims to research and develop a cost-effective, efficient, ultra-low emission burner for next generation natural gas on-demand water heaters in residential and commercial buildings. To meet these requirements, researchers at the Lawrence Berkeley National Laboratory (LBNL) are adapting and testing the low-swirl burner (LSB) technology for commercially available on-demand water heaters. In this report, a low-swirl burner is researched, developed, and evaluated to meet targeted on-demand water heater performance metrics. Performance metrics for a new LSB design are identified by characterizing performance of current on-demand water heaters using published literature and technical specifications, and through experimental evaluations that measure fuel consumption and emissions output over a range of operating conditions. Next, target metrics and design criteria for the LSB are used to create six 3D printed prototypes for preliminary investigations. Prototype designs that proved the most promising were fabricated out of metal and tested further to evaluate the LSB’s full performance potential. After conducting a full performance evaluation on two designs, we found that one LSB design is capable of meeting or exceeding almost all the target performance metrics for on-demand water heaters. Specifically, this LSB demonstrated flame stability when operating from 4.07 kBTU/hr up to 204 kBTU/hr (50:1 turndown), compliance with SCAQMD Rule 1146.2 (14 ng/J or 20 ppm NOX @ 3% O2), and lower CO emissions than state

  1. An Ultra-Low Voltage Analog Front End for Strain Gauge Sensory System Application in 0.18µm CMOS

    Science.gov (United States)

    Edward, Alexander; Chan, Pak Kwong

    This paper presents analysis and design of a new ultra-low voltage analog front end (AFE) dedicated to strain sensor applications. The AFE, designed in 0.18µm CMOS process, features a chopper-stabilized instrumentation amplifier (IA), a balanced active MOSFET-C 2nd order low pass filter (LPF), a clock generator and a voltage booster which operate at supply voltage (Vdd) of 0.6V. The designed IA achieves 30dB of closed-loop gain, 101dB of common-mode rejection ratio (CMRR) at 50Hz, 80dB of power-supply rejection ratio (PSRR) at 50Hz, thermal noise floor of 53.4 nV/√Hz, current consumption of 14µA, and noise efficiency factor (NEF) of 9.7. The high CMRR and rail-to-rail output swing capability is attributed to a new low voltage realization of the active-bootstrapped technique using a pseudo-differential gain-boosting operational transconductance amplifier (OTA) and proposed current-driven bulk (CDB) biasing technique. An output capacitor-less low-dropout regulator (LDO), with a new fast start-up LPF technique, is used to regulate this 0.6V supply from a 0.8-1.0V energy harvesting power source. It achieves power supply rejection (PSR) of 42dB at frequency of 1MHz. A cascode compensated pseudo differential amplifier is used as the filter's building block for low power design. The filter's single-ended-to-balanced converter is implemented using a new low voltage amplifier with two-stage common-mode cancellation. The overall AFE was simulated to have 65.6dB of signal-to-noise ratio (SNR), total harmonic distortion (THD) of less than 0.9% for a 100Hz sinusoidal maximum input signal, bandwidth of 2kHz, and power consumption of 51.2µW. Spectre RF simulations were performed to validate the design using BSIM3V3 transistor models provided by GLOBALFOUNDRIES 0.18µm CMOS process.

  2. Dictionary-based monitoring of premature ventricular contractions: An ultra-low-cost point-of-care service.

    Science.gov (United States)

    Bollepalli, S Chandra; Challa, S Sastry; Anumandla, Laxminarayana; Jana, Soumya

    2018-04-25

    While cardiovascular diseases (CVDs) are prevalent across economic strata, the economically disadvantaged population is disproportionately affected due to the high cost of traditional CVD management, involving consultations, testing and monitoring at medical facilities. Accordingly, developing an ultra-low-cost alternative, affordable even to groups at the bottom of the economic pyramid, has emerged as a societal imperative. Against this backdrop, we propose an inexpensive yet accurate home-based electrocardiogram (ECG) monitoring service. Specifically, we seek to provide point-of-care monitoring of premature ventricular contractions (PVCs), high frequency of which could indicate the onset of potentially fatal arrhythmia. Note that the first-generation telecardiology system acquires the ECG, transmits it to a professional diagnostic center without processing, and nearly achieves the diagnostic accuracy of a bedside setup. In the process, such a system incurs high bandwidth cost and requires the physicians to process the entire record for diagnosis. To reduce cost, current telecardiology systems compress data before transmitting. However, the burden on physicians remains undiminished. In this context, we develop a dictionary-based algorithm that reduces not only the overall bandwidth requirement, but also the physicians workload by localizing anomalous beats. Specifically, we detect anomalous beats with high sensitivity and only those beats are then transmitted. In fact, we further compress those beats using class-specific dictionaries subject to suitable reconstruction/diagnostic fidelity. Finally, using Monte Carlo cross validation on MIT/BIH arrhythmia database, we evaluate the performance of the proposed system. In particular, with a sensitivity target of at most one undetected PVC in one hundred beats, and a percentage root mean squared difference less than 9% (a clinically acceptable level of fidelity), we achieved about 99.15% reduction in bandwidth cost

  3. A mega Ultra Low Velocity Zone at the Base of the Iceland Plume: a Target for Tomographic Telescope Implementation

    Science.gov (United States)

    Romanowicz, Barbara; Yuan, Kaiqing; Masson, Yder; Adourian, Sevan

    2017-04-01

    We have recently constructed the first global whole mantle radially anisotropic shear wave velocity model based on time domain full waveform inversion and numerical wavefield computations using the Spectral Element Method (French et al., 2013; French and Romanowicz, 2014). This model's most salient features are broad chimney-like low velocity conduits, rooted within the large-low-shear-velocity provinces (LLSVPs) at the base of the mantle, and extending from the core-mantle boundary up through most of the lower mantle, projecting to the earth's surface in the vicinity of major hotspots. The robustness of these features is confirmed through several non-linear synthetic tests, which we present here, including several iterations of inversion using a different starting model than that which served for the published model. The roots of these not-so-classical "plumes" are regions of more pronounced low shear velocity. While the detailed structure is not yet resolvable tomographically, at least two of them contain large (>800 km diameter) ultra-low-velocity zones (ULVZs), one under Hawaii (Cottaar and Romanowicz, 2012) and the other one under Samoa (Thorne et al., 2013). Through 3D numerical forward modelling of Sdiff phases down to 10s period, using data from broadband arrays illuminating the base of the Iceland plume from different directions, we show that such a large ULVZ also exists at the root of this plume, embedded within a taller region of moderately reduced low shear velocity, such as proposed by He et al. (2015). We also show that such a wide, but localized ULVZ is unique in a broad region around the base of the Iceland Plume. Because of the intense computational effort required for forward modelling of trial structures, to first order this ULVZ is represented by a cylindrical structure of diameter 900 km, height 20 km and velocity reduction 20%. To further refine the model, we have developed a technique which we call "tomographic telescope", in which we are

  4. Full Useful Life (120,000 miles) Exhaust Emission Performance of a NOx Adsorber and Diesel Particle Filter Equipped Passenger Car and Medium-duty Engine in Conjunction with Ultra Low Sulfur Fuel (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Thornton, M.; Tatur, M.; Tomazic, D.; Weber, P.; Webb, C.

    2005-08-25

    Discusses the full useful life exhaust emission performance of a NOx (nitrogen oxides) adsorber and diesel particle filter equipped light-duty and medium-duty engine using ultra low sulfur diesel fuel.

  5. Estimation of permeability and permeability anisotropy in horizontal wells through numerical simulation of mud filtrate invasion

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Nelson [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). Exploracao e Producao; Altman, Raphael; Rasmus, John; Oliveira, Jansen [Schlumberger Servicos de Petroleo Ltda., Rio de Janeiro, RJ (Brazil)

    2008-07-01

    This paper describes how permeability and permeability anisotropy is estimated in horizontal wells using LWD (logging-while-drilling) laterolog resistivity data. Laterolog-while-drilling resistivity passes of while-drilling and timelapse (while reaming) were used to capture the invasion process. Radial positions of water based mud invasion fronts were calculated from while-drilling and reaming resistivity data. The invasion process was then recreated by constructing forward models with a fully implicit, near-wellbore numerical simulation such that the invasion front at a given time was consistent with the position of the front predicted by resistivity inversions. The radial position of the invasion front was shown to be sensitive to formation permeability. The while-drilling environment provides a fertile scenario to investigate reservoir dynamic properties because mud cake integrity and growth is not fully developed which means that the position of the invasion front at a particular point in time is more sensitive to formation permeability. The estimation of dynamic formation properties in horizontal wells is of particular value in marginal fields and deep-water offshore developments where running wireline and obtaining core is not always feasible, and where the accuracy of reservoir models can reduce the risk in field development decisions. (author)

  6. Development of Solution-Processable, Optically Transparent Polyimides with Ultra-Low Linear Coefficients of Thermal Expansion

    Directory of Open Access Journals (Sweden)

    Masatoshi Hasegawa

    2017-10-01

    Full Text Available This paper reviews the development of new high-temperature polymeric materials applicable to plastic substrates in image display devices with a focus on our previous results. Novel solution-processable colorless polyimides (PIs with ultra-low linear coefficients of thermal expansion (CTE are proposed in this paper. First, the principles of the coloration of PI films are briefly discussed, including the influence of the processing conditions on the film coloration, as well as the chemical and physical factors dominating the low CTE characteristics of the resultant PI films to clarify the challenges in simultaneously achieving excellent optical transparency, a very high Tg, a very low CTE, and excellent film toughness. A possible approach of achieving these target properties is to use semi-cycloaliphatic PI systems consisting of linear chain structures. However, semi-cycloaliphatic PIs obtained using cycloaliphatic diamines suffer various problems during precursor polymerization, cyclodehydration (imidization, and film preparation. In particular, when using trans-1,4-cyclohexanediamine (t-CHDA as the cycloaliphatic diamine, a serious problem emerges: salt formation in the initial stages of the precursor polymerization, which terminates the polymerization in some cases or significantly extends the reaction period. The system derived from 3,3′,4,4′-biphenyltetracarboxylic dianhydride (s-BPDA and t-CHDA can be polymerized by a controlled heating method and leads to a PI film with relatively good properties, i.e., excellent light transmittance at 400 nm (T400 = ~80%, a high Tg (>300 °C, and a very low CTE (10 ppm·K−1. However, this PI film is somewhat brittle (the maximum elongation at break, εb max is about 10%. On the other hand, the combination of cycloaliphatic tetracarboxylic dianhydrides and aromatic diamines does not result in salt formation. The steric structures of cycloaliphatic tetracarboxylic dianhydrides significantly influence

  7. Analytical Estimation of Water-Oil Relative Permeabilities through Fractures

    Directory of Open Access Journals (Sweden)

    Saboorian-Jooybari Hadi

    2016-05-01

    Full Text Available Modeling multiphase flow through fractures is a key issue for understanding flow mechanism and performance prediction of fractured petroleum reservoirs, geothermal reservoirs, underground aquifers and carbon-dioxide sequestration. One of the most challenging subjects in modeling of fractured petroleum reservoirs is quantifying fluids competition for flow in fracture network (relative permeability curves. Unfortunately, there is no standard technique for experimental measurement of relative permeabilities through fractures and the existing methods are very expensive, time consuming and erroneous. Although, several formulations were presented to calculate fracture relative permeability curves in the form of linear and power functions of flowing fluids saturation, it is still unclear what form of relative permeability curves must be used for proper modeling of flow through fractures and consequently accurate reservoir simulation. Basically, the classic linear relative permeability (X-type curves are used in almost all of reservoir simulators. In this work, basic fluid flow equations are combined to develop a new simple analytical model for water-oil two phase flow in a single fracture. The model gives rise to simple analytic formulations for fracture relative permeabilities. The model explicitly proves that water-oil relative permeabilities in fracture network are functions of fluids saturation, viscosity ratio, fluids density, inclination of fracture plane from horizon, pressure gradient along fracture and rock matrix wettability, however they were considered to be only functions of saturations in the classic X-type and power (Corey [35] and Honarpour et al. [28, 29] models. Eventually, validity of the proposed formulations is checked against literature experimental data. The proposed fracture relative permeability functions have several advantages over the existing ones. Firstly, they are explicit functions of the parameters which are known for

  8. Permeability of porour rhyolite

    Science.gov (United States)

    Cashman, K.; Rust, A.; Wright, H.; Roberge, J.

    2003-04-01

    The development of permeability in bubble-bearing magmas determines the efficiency of volatile escape during their ascent through volcanic conduits, which, in turn, controls their explosive potential. As permeability requires bubble connectivity, relationships between permeability and porosity in silicic magmas must be controlled by the formation, growth, deformation and coalescence of their constituent bubbles. Although permeability data on porous volcanic pyroclasts are limited, the database can be greatly extended by including data for ceramic and metallic foams1. Several studies indicate that a single number does not adequately describe the permeability of a foam because inertial effects, which predominate at high flow rates, cause deviations from Darcy's law. These studies suggest that permeability is best modeled using the Forschheimer equation to determine both the Darcy permeability (k1) and the non-Darcian (k2) permeability. Importantly, at the high porosities of ceramic foams (75-95%), both k1 and k2 are strongly dependent on pore size and geometry, suggesting that measurement of these parameters provides important information on foam structure. We determined both the connected porosity (by He-pycnometry) and the permeability (k1 and k2) of rhyolitic samples having a wide range in porosity (22-85%) and vesicle textures. In general, these data support previous observations of a power law relationship between connected porosity and Darcy permeability2. In detail, variations in k1 increase at higher porosities. Similarly, k2 generally increases in both mean and standard deviation with increasing porosity. Measurements made on three mutually perpendicular cores from individual pumice clasts suggest that some of the variability can be explained by anisotropy in the vesicle structure. By comparison with ceramic foams, we suggest that the remaining variability results from differences either in average vesicle size or, more likely, in the size of apertures

  9. Effects of Formation Damage on Productivity of Underground Gas Storage Reservoirs

    Directory of Open Access Journals (Sweden)

    C.I.C. Anyadiegwu

    2013-12-01

    Full Text Available Analysis of the effects of formation damage on the productivity of gas storage reservoirs was performed with depleted oil reservoir (OB-02, located onshore, Niger Delta, Nigeria. Information on the reservoir and the fluids from OB-02 were collected and used to evaluate the deliverabilities of the gas storage reservoir over a 10-year period of operation. The results obtained were used to plot graphs of deliverability against permeability and skin respectively. The graphs revealed that as the permeability decreased, the skin increased, and hence a decrease in deliverability of gas from the reservoir during gas withdrawal. Over the ten years of operating the reservoir for gas storage, the deliverability and permeability which were initially 2.7 MMscf/d and 50 mD, with a skin of 0.2, changed to new values of 0.88 MMscf/d and 24 mD with the skin as 4.1 at the tenth year.

  10. Determination of Three-Phase Relative Permeabilities under Reservoir Conditions by Hot Water and Steamflood Experiments Détermination de perméabilités relatives tri-phasiques en conditions de réservoir, à partir d'expériences de balayages à l'eau chaude et à la vapeur

    Directory of Open Access Journals (Sweden)

    Quettier L.

    2006-11-01

    Full Text Available In order to help the physical and numerical interpretation of Emeraude's steam pilot, two-phase waterfloods at four temperatures (between 30 and 240°C and a steamflood were performed in the laboratory using the same porous medium (compacted silt and under reservoir conditions. Dynamic isothermal displacements were interpreted with a thermal simulator taking into account capillary end effects. The corresponding oil-water relative permeability curves were obtained by matching observed pressure drop and oil production. Results show that temperature influences the end-point saturations but not the shape of the curves. The steamflood experiment was carried out in an adiabatic core holder. Oil stripping and production of a large amount of CO2 caused by dissolution of carbonates were pointed out. The numerical interpretation of this experiment, by making use of the oil-water relative permeabilities, provided the three-phase oil relative permeability which is an essential datum for numerical interpretation of a steam drive pilot. Then a parameter study was used to quantify the influence of the different mechanisms involved in hot water and steam floods. Dans le but de faciliter l'interprétation physique et numérique du pilote vapeur d' Emeraude, des balayages eau-huile à quatre températures (entre 30 et 240°C et un balayage à la vapeur ont été réalisés au laboratoire. Toutes ces expériences ont été effectuées sur le même milieu poreux (silt compacté et en conditions de réservoir. Les déplacements bi-phasiques isothermes, en écoulement transitoire, ont été interprétés avec un modèle numérique thermique qui prend en compte les effets capillaires aux extrémités de l'échantillon. Les courbes de perméabilités relatives dynamiques eau-huile sont déterminées par calage, sur les courbes expérimentales, de la différence de pression et de la production d'huile simulées. Les résultats montrent que la température influe sur les

  11. Soils - Mean Permeability

    Data.gov (United States)

    Kansas Data Access and Support Center — This digital spatial data set provides information on the magnitude and spatial pattern of depth-weighted, mean soil permeability throughout the State of Kansas. The...

  12. Hydrogen permeability through metals

    International Nuclear Information System (INIS)

    Pisarev, A.A.; Tsvetkov, I.V.; Marenkov, E.D.; Yarko, S.S.

    2011-01-01

    The mechanisms of hydrogen permeability through one-layer and multi-layer membranes are considered. The effect of surface roughness, crystal defects, cracks and pores is described. Mathematical description of the processes is given [ru

  13. Permeable pavement study (Edison)

    Data.gov (United States)

    U.S. Environmental Protection Agency — While permeable pavement is increasingly being used to control stormwater runoff, field-based, side-by-side investigations on the effects different pavement types...

  14. Effect of ultra-low doses, ASIR and MBIR on density and noise levels of MDCT images of dental implant sites.

    Science.gov (United States)

    Widmann, Gerlig; Al-Shawaf, Reema; Schullian, Peter; Al-Sadhan, Ra'ed; Hörmann, Romed; Al-Ekrish, Asma'a A

    2017-05-01

    Differences in noise and density values in MDCT images obtained using ultra-low doses with FBP, ASIR, and MBIR may possibly affect implant site density analysis. The aim of this study was to compare density and noise measurements recorded from dental implant sites using ultra-low doses combined with FBP, ASIR, and MBIR. Cadavers were scanned using a standard protocol and four low-dose protocols. Scans were reconstructed using FBP, ASIR-50, ASIR-100, and MBIR, and either a bone or standard reconstruction kernel. Density (mean Hounsfield units [HUs]) of alveolar bone and noise levels (mean standard deviation of HUs) was recorded from all datasets and measurements were compared by paired t tests and two-way ANOVA with repeated measures. Significant differences in density and noise were found between the reference dose/FBP protocol and almost all test combinations. Maximum mean differences in HU were 178.35 (bone kernel) and 273.74 (standard kernel), and in noise, were 243.73 (bone kernel) and 153.88 (standard kernel). Decreasing radiation dose increased density and noise regardless of reconstruction technique and kernel. The effect of reconstruction technique on density and noise depends on the reconstruction kernel used. • Ultra-low-dose MDCT protocols allowed more than 90 % reductions in dose. • Decreasing the dose generally increased density and noise. • Effect of IRT on density and noise varies with reconstruction kernel. • Accuracy of low-dose protocols for interpretation of bony anatomy not known. • Effect of low doses on accuracy of computer-aided design models unknown.

  15. Principal permeability determination from multiple horizontal well tests

    Energy Technology Data Exchange (ETDEWEB)

    Economides, M. [Texas A and M Univ., TX (United States); Munoz, A.; Ehlig-Economides, C.

    1998-12-31

    A method for obtaining principal permeability magnitudes and direction that requires only the linear flow regime from transient tests in three horizontal wells oriented in three distinct and arbitrary directions, is described. Well design optimization strategies require knowledge of both the principal permeability orientation as well as the horizontal permeability magnitudes. When the degree of horizontal permeability anisotropy (i.e. permeability in the bedding plane with respect to direction) is significant, the productivity of a long horizontal well will depend greatly on its direction, especially when the well is first brought into production. Productivities have been found to deviate substantially among wells in the same reservoir and this deviation has been attributed to differences in well orientation. In view of this fact, measuring permeability anisotropy becomes a compelling necessity. The success of the proposed method is illustrated by a case study in which the principal permeability magnitudes and direction from three wells were used to predict the productivity of a fourth well within 10 per cent. Use of the computed principal permeabilities from the case study, it was possible to forecast the cumulative production to show the significance of well trajectory optimization on the discounted cash flow and the net present value. 20 refs., 3 figs.

  16. AVE5026, a new hemisynthetic ultra-low-molecular-weight heparin for the prevention of venous thromboembolism in patients after total knee replacement surgery

    DEFF Research Database (Denmark)

    Lassen, Michael Rud; Dahl, O E; Mismetti, P

    2009-01-01

    BACKGROUND: AVE5026 is a new hemisynthetic ultra-low-molecular-weight heparin, with a novel anti-thrombotic profile resulting from high anti-factor (F)Xa activity and residual anti-FIIa activity. AVE5026 is in clinical development for venous thromboembolism (VTE) prevention, a frequent complication....... The primary safety outcome was the incidence of major bleeding. RESULTS: The primary efficacy outcome was assessed in 464 patients. There was a significant dose-response across the five AVE5026 groups for VTE prevention (Pincidence of VTE ranging from 5.3% to 44.1% compared with 35...

  17. Intestinal Permeability: The Basics

    Directory of Open Access Journals (Sweden)

    Ingvar Bjarnason

    1995-01-01

    Full Text Available The authors review some of the more fundamental principles underlying the noninvasive assessment of intestinal permeability in humans, the choice of test markers and their analyses, and the practical aspects of test dose composition and how these can be changed to allow the specific assessment of regional permeability changes and other intestinal functions. The implications of increased intestinal permeability in the pathogenesis of human disease is discussed in relation to findings in patients with Crohn’s disease. A common feature of increased intestinal permeability is the development of a low grade enteropathy, and while quantitatively similar changes may be found in Crohn’s disease these seem to predict relapse of disease. Moreover, factors associated with relapse of Crohn’s disease have in common an action to increase intestinal permeability. While increased intestinal permeability does not seem to be important in the etiology of Crohn’s disease it may be a central mechanism in the clinical relapse of disease.

  18. Stress- and Chemistry-Mediated Permeability Enhancement/Degradation in Stimulated Critically-Stressed Fractures

    Energy Technology Data Exchange (ETDEWEB)

    Derek Elsworth; Abraham S. Grader; Chris Marone; Phillip Halleck; Peter Rose; Igor Faoro; Joshua Taron; André Niemeijer; Hideaki Yasuhara

    2009-03-30

    This work has investigated the interactions between stress and chemistry in controlling the evolution of permeability in stimulated fractured reservoirs through an integrated program of experimentation and modeling. Flow-through experiments on natural and artificial fractures in Coso diorite have examined the evolution of permeability under paths of mean and deviatoric stresses, including the role of dissolution and precipitation. Models accommodating these behaviors have examined the importance of incorporating the complex couplings between stress and chemistry in examining the evolution of permeability in EGS reservoirs. This document reports the findings of experiment [1,2] and analysis [3,4], in four sequential chapters.

  19. Reservoir Identification: Parameter Characterization or Feature Classification

    Science.gov (United States)

    Cao, J.

    2017-12-01

    The ultimate goal of oil and gas exploration is to find the oil or gas reservoirs with industrial mining value. Therefore, the core task of modern oil and gas exploration is to identify oil or gas reservoirs on the seismic profiles. Traditionally, the reservoir is identify by seismic inversion of a series of physical parameters such as porosity, saturation, permeability, formation pressure, and so on. Due to the heterogeneity of the geological medium, the approximation of the inversion model and the incompleteness and noisy of the data, the inversion results are highly uncertain and must be calibrated or corrected with well data. In areas where there are few wells or no well, reservoir identification based on seismic inversion is high-risk. Reservoir identification is essentially a classification issue. In the identification process, the underground rocks are divided into reservoirs with industrial mining value and host rocks with non-industrial mining value. In addition to the traditional physical parameters classification, the classification may be achieved using one or a few comprehensive features. By introducing the concept of seismic-print, we have developed a new reservoir identification method based on seismic-print analysis. Furthermore, we explore the possibility to use deep leaning to discover the seismic-print characteristics of oil and gas reservoirs. Preliminary experiments have shown that the deep learning of seismic data could distinguish gas reservoirs from host rocks. The combination of both seismic-print analysis and seismic deep learning is expected to be a more robust reservoir identification method. The work was supported by NSFC under grant No. 41430323 and No. U1562219, and the National Key Research and Development Program under Grant No. 2016YFC0601

  20. Quantifying the clay content with borehole depth and impact on reservoir flow

    Science.gov (United States)

    Sarath Kumar, Aaraellu D.; Chattopadhyay, Pallavi B.

    2017-04-01

    This study focuses on the application of reservoir well log data and 3D transient numerical model for proper optimization of flow dynamics and hydrocarbon potential. Fluid flow through porous media depends on clay content that controls porosity, permeability and pore pressure. The pressure dependence of permeability is more pronounced in tight formations. Therefore, preliminary clay concentration analysis and geo-mechanical characterizations have been done by using wells logs. The assumption of a constant permeability for a reservoir is inappropriate and therefore the study deals with impact of permeability variation for pressure-sensitive formation. The study started with obtaining field data from available well logs. Then, the mathematical models are developed to understand the efficient extraction of oil in terms of reservoir architecture, porosity and permeability. The fluid flow simulations have been done using COMSOL Multiphysics Software by choosing time dependent subsurface flow module that is governed by Darcy's law. This study suggests that the reservoir should not be treated as a single homogeneous structure with unique porosity and permeability. The reservoir parameters change with varying clay content and it should be considered for effective planning and extraction of oil. There is an optimum drawdown for maximum production with varying permeability in a reservoir.

  1. Paragenetic evolution of reservoir facies, Middle Triassic Halfway Formation, PeeJay Field, northeastern British Columbia: controls on reservoir quality

    Energy Technology Data Exchange (ETDEWEB)

    Caplan, M. L. [Alberta Univ., Dept. of Earth and Atmospheric Sciences, Edmonton, AB (Canada); Moslow, T. F. [Ulster Petroleum Ltd., Calgary, AB (Canada)

    1998-09-01

    Because of the obvious importance of reservoir quality to reservoir performance, diagenetic controls on reservoir quality of Middle Triassic reservoir facies are investigated by comparing two reservoir lithofacies. The implications of porosity structure on the efficiency of primary and secondary hydrocarbon recovery are also assessed. Halfway reservoir facies are composed of bioclastic grainstones (lithofacies G) and litharenites/sublitharenites (lithofacies H), both of which are interpreted as tidal inlet fills. Although paragenetic evolution was similar for the two reservoir facies, subtle differences in reservoir quality are discernible. These are controlled by sedimentary structures, porosity type, grain constituents, and degree of cementation. Reservoir quality in lithofacies G is a function of connectivity of the pore network. In lithofacies H, secondary granular porosity creates a more homogeneous interconnected pore system, wide pore throats and low aspect ratios. The high porosity and low permeability values of the bioclastic grainstones are suspected to cause inefficient flushing of hydrocarbons during waterflooding. However, it is suggested that recovery may be enhanced by induced hydraulic fracturing and acidization of lower permeability calcareous cemented zones. 52 refs., 15 figs.

  2. Improved characterization of reservoir behavior by integration of reservoir performances data and rock type distributions

    Energy Technology Data Exchange (ETDEWEB)

    Davies, D.K.; Vessell, R.K. [David K. Davies & Associates, Kingwood, TX (United States); Doublet, L.E. [Texas A& M Univ., College Station, TX (United States)] [and others

    1997-08-01

    An integrated geological/petrophysical and reservoir engineering study was performed for a large, mature waterflood project (>250 wells, {approximately}80% water cut) at the North Robertson (Clear Fork) Unit, Gaines County, Texas. The primary goal of the study was to develop an integrated reservoir description for {open_quotes}targeted{close_quotes} (economic) 10-acre (4-hectare) infill drilling and future recovery operations in a low permeability, carbonate (dolomite) reservoir. Integration of the results from geological/petrophysical studies and reservoir performance analyses provide a rapid and effective method for developing a comprehensive reservoir description. This reservoir description can be used for reservoir flow simulation, performance prediction, infill targeting, waterflood management, and for optimizing well developments (patterns, completions, and stimulations). The following analyses were performed as part of this study: (1) Geological/petrophysical analyses: (core and well log data) - {open_quotes}Rock typing{close_quotes} based on qualitative and quantitative visualization of pore-scale features. Reservoir layering based on {open_quotes}rock typing {close_quotes} and hydraulic flow units. Development of a {open_quotes}core-log{close_quotes} model to estimate permeability using porosity and other properties derived from well logs. The core-log model is based on {open_quotes}rock types.{close_quotes} (2) Engineering analyses: (production and injection history, well tests) Material balance decline type curve analyses to estimate total reservoir volume, formation flow characteristics (flow capacity, skin factor, and fracture half-length), and indications of well/boundary interference. Estimated ultimate recovery analyses to yield movable oil (or injectable water) volumes, as well as indications of well and boundary interference.

  3. Sensitivity Analysis of Methane Hydrate Reservoirs: Effects of Reservoir Parameters on Gas Productivity and Economics

    Science.gov (United States)

    Anderson, B. J.; Gaddipati, M.; Nyayapathi, L.

    2008-12-01

    This paper presents a parametric study on production rates of natural gas from gas hydrates by the method of depressurization, using CMG STARS. Seven factors/parameters were considered as perturbations from a base-case hydrate reservoir description based on Problem 7 of the International Methane Hydrate Reservoir Simulator Code Comparison Study led by the Department of Energy and the USGS. This reservoir is modeled after the inferred properties of the hydrate deposit at the Prudhoe Bay L-106 site. The included sensitivity variables were hydrate saturation, pressure (depth), temperature, bottom-hole pressure of the production well, free water saturation, intrinsic rock permeability, and porosity. A two-level (L=2) Plackett-Burman experimental design was used to study the relative effects of these factors. The measured variable was the discounted cumulative gas production. The discount rate chosen was 15%, resulting in the gas contribution to the net present value of a reservoir. Eight different designs were developed for conducting sensitivity analysis and the effects of the parameters on the real and discounted production rates will be discussed. The breakeven price in various cases and the dependence of the breakeven price on the production parameters is given in the paper. As expected, initial reservoir temperature has the strongest positive effect on the productivity of a hydrate deposit and the bottom-hole pressure in the production well has the strongest negative dependence. Also resulting in a positive correlation is the intrinsic permeability and the initial free water of the formation. Negative effects were found for initial hydrate saturation (at saturations greater than 50% of the pore space) and the reservoir porosity. These negative effects are related to the available sensible heat of the reservoir, with decreasing productivity due to decreasing available sensible heat. Finally, we conclude that for the base case reservoir, the break-even price (BEP

  4. Evaluation of an ultra-low-dose oral contraceptive for dysmenorrhea: a placebo-controlled, double-blind, randomized trial.

    Science.gov (United States)

    Harada, Tasuku; Momoeda, Mikio

    2016-12-01

    To evaluate the efficacy and safety of an ultra-low-dose oral contraceptive (NPC-01; 0.02 mg ethinyl estradiol and 1 mg norethisterone) in subjects with dysmenorrhea. Placebo-controlled, double-blind, randomized trial. Clinical trial sites. Two hundred fifteen subjects with dysmenorrhea. Subjects were randomly assigned to receive NPC-01, placebo, or IKH-01 (0.035 mg ethinyl estradiol and 1 mg norethisterone) for four cycles. Total dysmenorrhea score (verbal rating scale) assessing pain on the basis of limited ability to work and need for analgesics. The reductions of total dysmenorrhea score and visual analog scale score after the treatment were significantly higher in the NPC-01 group than in the placebo group. Furthermore, the efficacy of NPC-01 was comparable to that of IKH-01. The overall incidence of side effects was significantly higher in the NPC-01 group than in the placebo group. All side effects that occurred in the NPC-01 group were previously reported in patients receiving IKH-01. No serious side effects occurred. The ultra-low-dose contraceptive NPC-01 relieved dysmenorrhea as effectively as IKH-01. Thus, NPC-01 could represent a new option for long-term treatment of dysmenorrhea. NCT01129102. Copyright © 2016 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  5. A highly order-structured membrane electrode assembly with vertically aligned carbon nanotubes for ultra-low Pt loading PEM fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Zhi Qun; Lim, San Hua; Poh, Chee Kok; Lin, Jianyi [Institute of Chemical and Engineering Sciences, 1 Pesek Road, Jurong Island, Singapore 627833 (Singapore); Tang, Zhe; Chua, Daniel [Department of Materials Science and Engineering, National University of Singapore, Singapore 117542 (Singapore); Xia, Zetao [Institute of Materials Research and Engineering, 3 Research Link, Singapore 117602 (Singapore); Luo, Zhiqiang; Shen, Zexiang [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore (Singapore); Shen, Pei Kang [State Key Laboratory of Optoelectronic Materials and Technologies, and Key Laboratory of Low-carbon Chemistry and Energy Conservation of Guangdong Province, School of Physics and Engineering, Sun Yat-sen University, Guangzhou, 510275 (China); Feng, Yuan Ping [Department of Physics, National University of Singapore, Singapore 117542 (Singapore)

    2011-11-15

    A simple method was developed to prepare ultra-low Pt loading membrane electrode assembly (MEA) using vertically aligned carbon nanotubes (VACNTs) as highly ordered catalyst support for PEM fuel cells application. In the method, VACNTs were directly grown on the cheap household aluminum foil by plasma enhanced chemical vapor deposition (PECVD), using Fe/Co bimetallic catalyst. By depositing a Pt thin layer on VACNTs/Al and subsequent hot pressing, Pt/VACNTs can be 100% transferred from Al foil onto polymer electrolyte membrane for the fabrication of MEA. The whole transfer process does not need any chemical removal and destroy membrane. The PEM fuel cell with the MEA fabricated using this method showed an excellent performance with ultra-low Pt loading down to 35 {mu}g cm{sup -2} which was comparable to that of the commercial Pt catalyst on carbon powder with 400 {mu}g cm{sup -2}. To the best of our knowledge, for the first time, we identified that it is possible to substantially reduce the Pt loading one order by application of order-structured electrode based on VACNTs as Pt catalysts support, compared with the traditional random electrode at a comparable performance through experimental and mathematical methods. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Effect of ultra-low doses, ASIR and MBIR on density and noise levels of MDCT images of dental implant sites

    Energy Technology Data Exchange (ETDEWEB)

    Widmann, Gerlig; Schullian, Peter [Medical University of Innsbruck, Department of Radiology, Innsbruck (Austria); Al-Shawaf, Reema; Al-Sadhan, Ra' ed; Al-Ekrish, Asma' a A. [King Saud University, Department of Oral Medicine and Diagnostic Sciences, College of Dentistry, Riyadh (Saudi Arabia); Hoermann, Romed [Medical University of Innsbruck, Division of Clinical and Functional Anatomy, Innsbruck (Austria)

    2017-05-15

    Differences in noise and density values in MDCT images obtained using ultra-low doses with FBP, ASIR, and MBIR may possibly affect implant site density analysis. The aim of this study was to compare density and noise measurements recorded from dental implant sites using ultra-low doses combined with FBP, ASIR, and MBIR. Cadavers were scanned using a standard protocol and four low-dose protocols. Scans were reconstructed using FBP, ASIR-50, ASIR-100, and MBIR, and either a bone or standard reconstruction kernel. Density (mean Hounsfield units [HUs]) of alveolar bone and noise levels (mean standard deviation of HUs) was recorded from all datasets and measurements were compared by paired t tests and two-way ANOVA with repeated measures. Significant differences in density and noise were found between the reference dose/FBP protocol and almost all test combinations. Maximum mean differences in HU were 178.35 (bone kernel) and 273.74 (standard kernel), and in noise, were 243.73 (bone kernel) and 153.88 (standard kernel). Decreasing radiation dose increased density and noise regardless of reconstruction technique and kernel. The effect of reconstruction technique on density and noise depends on the reconstruction kernel used. (orig.)

  7. Effect of ultra-low doses, ASIR and MBIR on density and noise levels of MDCT images of dental implant sites

    International Nuclear Information System (INIS)

    Widmann, Gerlig; Schullian, Peter; Al-Shawaf, Reema; Al-Sadhan, Ra'ed; Al-Ekrish, Asma'a A.; Hoermann, Romed

    2017-01-01

    Differences in noise and density values in MDCT images obtained using ultra-low doses with FBP, ASIR, and MBIR may possibly affect implant site density analysis. The aim of this study was to compare density and noise measurements recorded from dental implant sites using ultra-low doses combined with FBP, ASIR, and MBIR. Cadavers were scanned using a standard protocol and four low-dose protocols. Scans were reconstructed using FBP, ASIR-50, ASIR-100, and MBIR, and either a bone or standard reconstruction kernel. Density (mean Hounsfield units [HUs]) of alveolar bone and noise levels (mean standard deviation of HUs) was recorded from all datasets and measurements were compared by paired t tests and two-way ANOVA with repeated measures. Significant differences in density and noise were found between the reference dose/FBP protocol and almost all test combinations. Maximum mean differences in HU were 178.35 (bone kernel) and 273.74 (standard kernel), and in noise, were 243.73 (bone kernel) and 153.88 (standard kernel). Decreasing radiation dose increased density and noise regardless of reconstruction technique and kernel. The effect of reconstruction technique on density and noise depends on the reconstruction kernel used. (orig.)

  8. Effective Stress Law in Unconventional Reservoirs under Different Boundary Conditions

    Science.gov (United States)

    Saurabh, S.; Harpalani, S.

    2017-12-01

    Unconventional reservoirs have attracted a great deal of research interest worldwide during the past two decades. Low permeability and specialized techniques required to exploit these resources present opportunities for improvement in both production rates and ultimate recovery. Understanding subsurface stress modifications and permeability evolution are valuable when evaluating the prospects of unconventional reservoirs. These reservoir properties are functions of effective stress. As a part of this study, effective stress law, specifically the variation of anisotropic Biot's coefficient under various boundary conditions believed to exist in gas reservoirs by different researchers, has been established. Pressure-dependent-permeability (PdK) experiments were carried out on San Juan coal under different boundary conditions, that is, uniaxial strain condition and constant volume condition. Stress and strain in the vertical and horizontal directions were monitored throughout the experiment. Data collected during the experiments was used to determine the Biot's coefficient in vertical and horizontal directions under these two boundary conditions, treating coal as transversely isotropic. The variation of Biot's coefficient was found to be well correlated with the variation in coal permeability. Based on the estimated values of Biot's coefficients, a theory of variation in its value is presented for other boundary conditions. The findings of the study shed light on the inherent behavior of Biot's coefficient under different reservoir boundary conditions. This knowledge can improve the modeling work requiring estimation of effective stress in reservoirs, such as, pressure-/stress- dependent permeability. At the same time, if the effective stresses are known with more certainty by other methods, it enables assessment of the unknown reservoir boundary conditions.

  9. Analysis of Fault Permeability Using Mapping and Flow Modeling, Hickory Sandstone Aquifer, Central Texas

    Energy Technology Data Exchange (ETDEWEB)

    Nieto Camargo, Jorge E., E-mail: jorge.nietocamargo@aramco.com; Jensen, Jerry L., E-mail: jjensen@ucalgary.ca [University of Calgary, Department of Chemical and Petroleum Engineering (Canada)

    2012-09-15

    Reservoir compartments, typical targets for infill well locations, are commonly created by faults that may reduce permeability. A narrow fault may consist of a complex assemblage of deformation elements that result in spatially variable and anisotropic permeabilities. We report on the permeability structure of a km-scale fault sampled through drilling a faulted siliciclastic aquifer in central Texas. Probe and whole-core permeabilities, serial CAT scans, and textural and structural data from the selected core samples are used to understand permeability structure of fault zones and develop predictive models of fault zone permeability. Using numerical flow simulation, it is possible to predict permeability anisotropy associated with faults and evaluate the effect of individual deformation elements in the overall permeability tensor. We found relationships between the permeability of the host rock and those of the highly deformed (HD) fault-elements according to the fault throw. The lateral continuity and predictable permeability of the HD fault elements enhance capability for estimating the effects of subseismic faulting on fluid flow in low-shale reservoirs.

  10. Changes in permeability caused by transient stresses: field observations, experiments, and mechanisms

    Science.gov (United States)

    Manga, Michael; Beresnev, Igor; Brodsky, Emily E.; Elkhoury, Jean E.; Elsworth, Derek; Ingebritsen, Steve E.; Mays, David C.; Wang, Chi-Yuen

    2012-01-01

    Oscillations in stress, such as those created by earthquakes, can increase permeability and fluid mobility in geologic media. In natural systems, strain amplitudes as small as 10–6 can increase discharge in streams and springs, change the water level in wells, and enhance production from petroleum reservoirs. Enhanced permeability typically recovers to prestimulated values over a period of months to years. Mechanisms that can change permeability at such small stresses include unblocking pores, either by breaking up permeability-limiting colloidal deposits or by mobilizing droplets and bubbles trapped in pores by capillary forces. The recovery time over which permeability returns to the prestimulated value is governed by the time to reblock pores, or for geochemical processes to seal pores. Monitoring permeability in geothermal systems where there is abundant seismicity, and the response of flow to local and regional earthquakes, would help test some of the proposed mechanisms and identify controls on permeability and its evolution.

  11. An asymptotic model of seismic reflection from a permeable layer

    Energy Technology Data Exchange (ETDEWEB)

    Silin, D.; Goloshubin, G.

    2009-10-15

    Analysis of compression wave propagation in a poroelastic medium predicts a peak of reflection from a high-permeability layer in the low-frequency end of the spectrum. An explicit formula expresses the resonant frequency through the elastic moduli of the solid skeleton, the permeability of the reservoir rock, the fluid viscosity and compressibility, and the reservoir thickness. This result is obtained through a low-frequency asymptotic analysis of Biot's model of poroelasticity. A review of the derivation of the main equations from the Hooke's law, momentum and mass balance equations, and Darcy's law suggests an alternative new physical interpretation of some coefficients of the classical poroelasticity. The velocity of wave propagation, the attenuation factor, and the wave number, are expressed in the form of power series with respect to a small dimensionless parameter. The absolute value of this parameter is equal to the product of the kinematic reservoir fluid mobility and the wave frequency. Retaining only the leading terms of the series leads to explicit and relatively simple expressions for the reflection and transmission coefficients for a planar wave crossing an interface between two permeable media, as well as wave reflection from a thin highly-permeable layer (a lens). Practical applications of the obtained asymptotic formulae are seismic modeling, inversion, and at-tribute analysis.

  12. Ultra low-dose of gadobenate dimeglumine for late gadolinium enhancement (LGE) imaging in acute myocardial infarction: A feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Galea, Nicola, E-mail: nicola.galea@uniroma1.it [Department of Radiological Sciences, Pathology and Oncology, Policlinico Umberto I, “Sapienza” University of Rome, Viale Regina Elena 315, 00161 Rome (Italy); Francone, Marco, E-mail: marco.francone@uniroma1.it [Department of Radiological Sciences, Pathology and Oncology, Policlinico Umberto I, “Sapienza” University of Rome, Viale Regina Elena 315, 00161 Rome (Italy); Zaccagna, Fulvio, E-mail: f.zaccagna@gmail.com [Department of Radiological Sciences, Pathology and Oncology, Policlinico Umberto I, “Sapienza” University of Rome, Viale Regina Elena 315, 00161 Rome (Italy); Ciolina, Federica, E-mail: federica.ciolina@gmail.com [Department of Radiological Sciences, Pathology and Oncology, Policlinico Umberto I, “Sapienza” University of Rome, Viale Regina Elena 315, 00161 Rome (Italy); Cannata, David, E-mail: davidrum@yahoo.it [Department of Radiological Sciences, Pathology and Oncology, Policlinico Umberto I, “Sapienza” University of Rome, Viale Regina Elena 315, 00161 Rome (Italy); Algeri, Emanuela, E-mail: emanuela_algeri@yahoo.com [Service de Radiologie et Imagerie Cardiovasculaire, Hôpital Cardiologique, Centre Hospitalier Régional et Universitaire de Lille, Avenue Oscar Lambret, 59037 Lille Cedex (France); Agati, Luciano, E-mail: luciano.agati@uniroma1.it [Department of Cardiovascular, Respiratory, Nephrologic, Anestesiologic and Geriatric Sciences, Sapienza University of Rome, Policlinico Umberto I, Via del Policlinico 165, 00161 Rome, Rome (Italy); and others

    2014-12-15

    Highlights: • We compared two gadolinium dose for late enhancement imaging in acute infarction. • We evaluated image quality both qualitatively and quantitatively. • Low dose regimen is feasible and provides better image quality at 5–10 min delay. • Standard dose warrants better image quality and should be routinely preferred. - Abstract: Purpose: To assess the feasibility of using an ultra-low dose (0.05 mmol/kg of body weight [BW]) of high relaxivity contrast agent for late gadolinium enhancement (LGE) imaging in patients with acute myocardial infarction (AMI). Materials and methods: 17 consecutive patients (mean age, 60.1 ± 10.3 years) with ST-segment elevation AMI underwent two randomized cardiac magnetic resonance studies (exam intervals between 24 and 48 h) on a 1.5 T unit during the first week after the event using gadobenate dimeglumine (Gd-BOPTA) at the dose of 0.1 mmol/kg BW (standard dose or SD group) and 0.05 mmol/kg BW (half dose or HD group). Image quality was qualitatively assessed. Quantitative analysis of LGE were performed by measuring signal intensity (SI), signal-to-noise ratio (SNR) in the infarcted myocardium (IM), non-infarcted myocardium (N-IM) and left ventricular cavity (LVC) in images acquired at 1, 3, 5, 10, 15 and 20 min after administration of Gd-BOPTA using both contrast media protocol. Contrast-to-noise ratio (CNR) between IM and N-IM (CNR IM/N-IM) and between IM and LVC (CNR IM/LVC) were also quantified for each time point. Moreover the extent of infarcted myocardium was measured. Results: 102 LGE images were evaluated for each dose group. Quality score was significantly higher for SD at 1, 15 and 20 min (0.002 < p < 0.046) and for HD at 5 min (p = 0.013). SNR has been higher in the SD group compared to the HD group even though not statistically significant at any time-point for both IM (SD vs. HD: 87.7 ± 73 vs. 65 ± 66; 0.15 < p < 0.38) and N-IM (SD vs. HD: 22 ± 61 vs. 9.9 ± 6.5; 0.09 < p < 0.43). LVC SNR was

  13. Numerical modeling of shear stimulation in naturally fractured geothermal reservoirs

    OpenAIRE

    Ucar, Eren

    2018-01-01

    Shear-dilation-based hydraulic stimulations are conducted to create enhanced geothermal systems (EGS) from low permeable geothermal reservoirs, which are initially not amenable to energy production. Reservoir stimulations are done by injecting low-pressurized fluid into the naturally fractured formations. The injection aims to activate critically stressed fractures by decreasing frictional strength and ultimately cause a shear failure. The shear failure leads to a permanent ...

  14. Integration of rock typing methods for carbonate reservoir characterization

    International Nuclear Information System (INIS)

    Aliakbardoust, E; Rahimpour-Bonab, H

    2013-01-01

    Reservoir rock typing is the most important part of all reservoir modelling. For integrated reservoir rock typing, static and dynamic properties need to be combined, but sometimes these two are incompatible. The failure is due to the misunderstanding of the crucial parameters that control the dynamic behaviour of the reservoir rock and thus selecting inappropriate methods for defining static rock types. In this study, rock types were defined by combining the SCAL data with the rock properties, particularly rock fabric and pore types. First, air-displacing-water capillary pressure curues were classified because they are representative of fluid saturation and behaviour under capillary forces. Next the most important rock properties which control the fluid flow and saturation behaviour (rock fabric and pore types) were combined with defined classes. Corresponding petrophysical properties were also attributed to reservoir rock types and eventually, defined rock types were compared with relative permeability curves. This study focused on representing the importance of the pore system, specifically pore types in fluid saturation and entrapment in the reservoir rock. The most common tests in static rock typing, such as electrofacies analysis and porosity–permeability correlation, were carried out and the results indicate that these are not appropriate approaches for reservoir rock typing in carbonate reservoirs with a complicated pore system. (paper)

  15. Biostable glucose permeable polymer

    DEFF Research Database (Denmark)

    2017-01-01

    A new biostable glucose permeable polymer has been developed which is useful, for example, in implantable glucose sensors. This biostable glucose permeable polymer has a number of advantageous characteristics and, for example, does not undergo hydrolytic cleavage and degradation, thereby providing...... a composition that facilitates long term sensor stability in vivo. The versatile characteristics of this polymer allow it to be used in a variety of contexts, for example to form the body of an implantable glucose sensor. The invention includes the polymer composition, sensor systems formed from this polymer...

  16. Field data provide estimates of effective permeability, fracture spacing, well drainage area and incremental production in gas shales

    KAUST Repository

    Eftekhari, Behzad; Marder, M.; Patzek, Tadeusz

    2018-01-01

    the external unstimulated reservoir. This allows us to estimate for the first time the effective permeability of the unstimulated shale and the spacing of fractures in the stimulated region. From an analysis of wells in the Barnett shale, we find

  17. Stress dependence of permeability of intact and fractured shale cores.

    Science.gov (United States)

    van Noort, Reinier; Yarushina, Viktoriya

    2016-04-01

    Whether a shale acts as a caprock, source rock, or reservoir, understanding fluid flow through shale is of major importance for understanding fluid flow in geological systems. Because of the low permeability of shale, flow is thought to be largely confined to fractures and similar features. In fracking operations, fractures are induced specifically to allow for hydrocarbon exploration. We have constructed an experimental setup to measure core permeabilities, using constant flow or a transient pulse. In this setup, we have measured the permeability of intact and fractured shale core samples, using either water or supercritical CO2 as the transporting fluid. Our measurements show decreasing permeability with increasing confining pressure, mainly due to time-dependent creep. Furthermore, our measurements show that for a simple splitting fracture, time-dependent creep will also eliminate any significant effect of this fracture on permeability. This effect of confinement on fracture permeability can have important implications regarding the effects of fracturing on shale permeability, and hence for operations depending on that.

  18. Porosity, petrophysics and permeability of the Whitby Mudstone (UK)

    Science.gov (United States)

    Houben, M.; Barnhoorn, A.; Hardebol, N.; Ifada, M.; Boersma, Q.; Douma, L.; Peach, C. J.; Bertotti, G.; Drury, M. R.

    2016-12-01

    Typically pore diameters in shales range from the µm down to the nm scale and the effective permeability of shale reservoirs is a function of the interconnectivity between the pore space and the natural fracture network present. The length and spacing of mechanical induced and natural fractures is one of the factors controlling gas produtivity from unconventional reservoirs. Permeability of the Whitby Mudstone measured on 1 inch cores was linked to microstructure and combined with natural fracture spacing present in outcrops along the Yorkshire coast (UK) to get insight into possible fluid pathways from reservoir to well. We used a combination of different techniques to characterize the porosity (gas adsorption, Scanning Electron Microscopy), mineralogy (X-Ray Fluorescence, X-Ray Diffraction, Scanning Electron Microscopy) and permeability (pressure step decay) of the Whitby Mudstone. In addition, we mapped the natural fracture network as present in outcrops along the Yorkshire coast (UK) at the 10-2-101m scale. Mineralogically we are dealing with a rock that is high in clay content and has an average organic matter content of about 10%. Results show a low porosity (max. 7%) as well as low permeability for the Whitby Mudstone. The permeability, measured parallel to bedding, depends on the confining pressure and is 86 nanodarcy at 10 MPa effective confining pressure and decreases to 16 nanodarcy at 40 MPa effective confining pressure. At the scale of observation the average distance to nearest natural fracture is in the order of 0.13 meter and 90 percent of all matrix elements are spaced within 0.4 meter to the nearest fracture. By assuming darcy flow, a permeability of 100 nanodarcy and 10% of overpressure we calculated that for the Whitby mudstone most of the gas resides in the matrix for less than 60 days until it reaches the fracture network.

  19. Measuring the permeability of Eleana argillite from area 17, Nevada Test Site, using the transient method

    International Nuclear Information System (INIS)

    Lin, W.

    1978-01-01

    Using the transient method, we determine the permeability of high-quartz Eleana argillite from the Nevada Test Site as a function of effective pressure. By comparing calculated and observed pressure decay in the upstream reservoir, we have determined the permeability of intact and fractured specimens at effective pressures ranging from 1.0 to 24.0 MPa. Over this pressure range, Eleana argillite has a low permeability (10 -16 to 10 -19 cm 2 ) when intact and a higher permeability (10 -12 to 10 -17 cm 2 ) with one induced through-going fracture

  20. Silicon on ferroelectic insulator field effect transistor (SOF-FET) a new device for the next generation ultra low power circuits

    Science.gov (United States)

    Es-Sakhi, Azzedin D.

    Field effect transistors (FETs) are the foundation for all electronic circuits and processors. These devices have progressed massively to touch its final steps in sub-nanometer level. Left and right proposals are coming to rescue this progress. Emerging nano-electronic devices (resonant tunneling devices, single-atom transistors, spin devices, Heterojunction Transistors rapid flux quantum devices, carbon nanotubes, and nanowire devices) took a vast share of current scientific research. Non-Si electronic materials like III-V heterostructure, ferroelectric, carbon nanotubes (CNTs), and other nanowire based designs are in developing stage to become the core technology of non-classical CMOS structures. FinFET present the current feasible commercial nanotechnology. The scalability and low power dissipation of this device allowed for an extension of silicon based devices. High short channel effect (SCE) immunity presents its major advantage. Multi-gate structure comes to light to improve the gate electrostatic over the channel. The new structure shows a higher performance that made it the first candidate to substitute the conventional MOSFET. The device also shows a future scalability to continue Moor's Law. Furthermore, the device is compatible with silicon fabrication process. Moreover, the ultra-low-power (ULP) design required a subthreshold slope lower than the thermionic-emission limit of 60mV/ decade (KT/q). This value was unbreakable by the new structure (SOI-FinFET). On the other hand most of the previews proposals show the ability to go beyond this limit. However, those pre-mentioned schemes have publicized a very complicated physics, design difficulties, and process non-compatibility. The objective of this research is to discuss various emerging nano-devices proposed for ultra-low-power designs and their possibilities to replace the silicon devices as the core technology in the future integrated circuit. This thesis proposes a novel design that exploits the

  1. DEVELOPMENT OF RESERVOIR CHARACTERIZATION TECHNIQUES AND PRODUCTION MODELS FOR EXPLOITING NATURALLY FRACTURED RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    Michael L. Wiggins; Raymon L. Brown; Faruk Civan; Richard G. Hughes

    2002-12-31

    For many years, geoscientists and engineers have undertaken research to characterize naturally fractured reservoirs. Geoscientists have focused on understanding the process of fracturing and the subsequent measurement and description of fracture characteristics. Engineers have concentrated on the fluid flow behavior in the fracture-porous media system and the development of models to predict the hydrocarbon production from these complex systems. This research attempts to integrate these two complementary views to develop a quantitative reservoir characterization methodology and flow performance model for naturally fractured reservoirs. The research has focused on estimating naturally fractured reservoir properties from seismic data, predicting fracture characteristics from well logs, and developing a naturally fractured reservoir simulator. It is important to develop techniques that can be applied to estimate the important parameters in predicting the performance of naturally fractured reservoirs. This project proposes a method to relate seismic properties to the elastic compliance and permeability of the reservoir based upon a sugar cube model. In addition, methods are presented to use conventional well logs to estimate localized fracture information for reservoir characterization purposes. The ability to estimate fracture information from conventional well logs is very important in older wells where data are often limited. Finally, a desktop naturally fractured reservoir simulator has been developed for the purpose of predicting the performance of these complex reservoirs. The simulator incorporates vertical and horizontal wellbore models, methods to handle matrix to fracture fluid transfer, and fracture permeability tensors. This research project has developed methods to characterize and study the performance of naturally fractured reservoirs that integrate geoscience and engineering data. This is an important step in developing exploitation strategies for

  2. A new method for the experimental determination of three-phase relative permeabilities

    International Nuclear Information System (INIS)

    Perez Carrillo, Edgar Ricardo; Jose Francisco Zapata Arango; Santos Santos, Nicolas

    2008-01-01

    Petroleum reservoirs under primary, secondary or tertiary recovery processes usually experience simultaneous flow of three fluids phases (oil, water and gas). Reports on some mathematical models for calculating three-phase relative permeability are available in the Literature. Nevertheless, many of these models were designed based on certain experimental conditions and reservoir rocks and fluids. Therefore, special care has to be taken when applying them to specific reservoirs. At the laboratory level, three-phase relative permeability can be calculated using experimental unsteady-state or steady state methodologies. This paper proposes an unsteady-state methodology to evaluate three-phase relative permeability using the equipment available at the petrophysical analysis Laboratory of the Instituto Colombiano del Petroleo (ICP) of Ecopetrol S.A. Improvements to the equipment were effected in order to achieve accuracy in the unsteady-state measurement of three-phase relative permeability. The target of improvements was directed toward to the attainment of two objectives:1) the modification of the equipment to obtain more reliable experimental data and 2) the appropriate interpretation of the data obtained. Special attention was given to the differential pressure and uncertainty measurement in the determination of fluid saturation in the rock samples. Three experiments for three-phase relative permeability were conducted using a sample A and reservoir rock from the Colombian Foothills. Fluid tests included the utilization of synthetic brine, mineral oil, reservoir crude oil and nitrogen. Two runs were conducted at the laboratory conditions while one run was conducted at reservoir conditions. Experimental results of these tests were compared using 16 mathematical models of three-phase relative permeability. For the three-phase relative permeability to oil, the best correlations between experimental data and tests using Blunt, Hustad Hasen, and Baker's models were

  3. Ultra-low switching energy and scaling in electric-field-controlled nanoscale magnetic tunnel junctions with high resistance-area product

    Energy Technology Data Exchange (ETDEWEB)

    Grezes, C.; Alzate, J. G.; Cai, X.; Wang, K. L. [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); Ebrahimi, F.; Khalili Amiri, P. [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); Inston, Inc., Los Angeles, California 90024 (United States); Katine, J. A. [HGST, Inc., San Jose, California 95135 (United States); Langer, J.; Ocker, B. [Singulus Technologies AG, Kahl am Main 63796 (Germany)

    2016-01-04

    We report electric-field-induced switching with write energies down to 6 fJ/bit for switching times of 0.5 ns, in nanoscale perpendicular magnetic tunnel junctions (MTJs) with high resistance-area product and diameters down to 50 nm. The ultra-low switching energy is made possible by a thick MgO barrier that ensures negligible spin-transfer torque contributions, along with a reduction of the Ohmic dissipation. We find that the switching voltage and time are insensitive to the junction diameter for high-resistance MTJs, a result accounted for by a macrospin model of purely voltage-induced switching. The measured performance enables integration with same-size CMOS transistors in compact memory and logic integrated circuits.

  4. A wide range ultra-low power Phase-Locked Loop with automatic frequency setting in 130 nm CMOS technology for data serialisation

    International Nuclear Information System (INIS)

    Firlej, M.; Fiutowski, T.; Idzik, M.; Moroń, J.; Świentek, K.

    2015-01-01

    The design and measurements results of a wide frequency range ultra-low power Phase-Locked Loop (PLL) for applications in readout systems of particle physics detectors are presented. The PLL was fabricated in a 130 nm CMOS technology. To allow the implementation of different data serialisation schemes multiple division factors (6, 8, 10, 16) were implemented in the PLL feedback loop. The main PLL block—VCO works in 16 frequency ranges/modes, switched either manually or automatically. A dedicated automatic frequency mode switching circuit was developed to allow simple frequency tuning. Although the PLL was designed and simulated for a frequency range of 30 MHz–3 GHz, due to the SLVS interface limits, the measurements were done only up to 1.3 GHz. The full PLL functionality was experimentally verified, confirming a very low and frequency scalable power consumption (0.7 mW at 1 GHz)

  5. A wide range ultra-low power Phase-Locked Loop with automatic frequency setting in 130 nm CMOS technology for data serialisation

    Science.gov (United States)

    Firlej, M.; Fiutowski, T.; Idzik, M.; Moroń, J.; Świentek, K.

    2015-12-01

    The design and measurements results of a wide frequency range ultra-low power Phase-Locked Loop (PLL) for applications in readout systems of particle physics detectors are presented. The PLL was fabricated in a 130 nm CMOS technology. To allow the implementation of different data serialisation schemes multiple division factors (6, 8, 10, 16) were implemented in the PLL feedback loop. The main PLL block—VCO works in 16 frequency ranges/modes, switched either manually or automatically. A dedicated automatic frequency mode switching circuit was developed to allow simple frequency tuning. Although the PLL was designed and simulated for a frequency range of 30 MHz-3 GHz, due to the SLVS interface limits, the measurements were done only up to 1.3 GHz. The full PLL functionality was experimentally verified, confirming a very low and frequency scalable power consumption (0.7 mW at 1 GHz).

  6. Limited impacts of truck-based ultra-low-volume applications of mosquito adulticides on mortality in honey bees (Apis mellifera).

    Science.gov (United States)

    Rinkevich, F D; Margotta, J W; Pokhrel, V; Walker, T W; Vaeth, R H; Hoffman, W C; Fritz, B K; Danka, R G; Rinderer, T E; Aldridge, R L; Linthicum, K J; Ottea, J A; Healy, K B

    2017-12-01

    Adulticides applied against mosquitoes can reduce vector populations during times of high arbovirus transmission. However, impacts of these insecticides on pollinators and other non-target organisms are of concern to mosquito control professionals, beekeepers and others. We evaluated mortality of Culex quinquefasciatus and Apis mellifera when caged insects were exposed to low and high label rates of four common adulticides (Aqua-Pursuit™ [permethrin], Duet® [prallethrin + sumithrin], Fyfanon® [malathion] and Scourge® [resmethrin]) at six distances up to 91.4 m from a truck-mounted ultra-low-volume sprayer. Honey bee mortality was both absolutely low (61 m had limited impacts on honey bee mortality while providing effective mosquito control.

  7. Space heating with ultra-low-temperature district heating - A case study of four single-family houses from the 1980s

    DEFF Research Database (Denmark)

    Østergaard, Dorte Skaarup; Svendsen, Svend

    . These benefits can be maximized if district heating temperatures are lowered as much as possible. In this paper we report on a project where 18 Danish single-family houses from the 1980s were supplied by ultra-low-temperature district heating with a supply temperature as low as 45 °C for the main part...... the four houses were modelled in the building simulation tool IDA ICE. The simulation models included the actual radiator sizes and the models were used to simulate the expected thermal comfort in the houses and resulting district heating return temperatures. Secondly measurements of the actual district...... heating return temperatures in the houses were analysed for different times of the year. The study found that existing Danish single-family houses from the 1980s can be heated with supply temperatures as low as 45 °C for the main part of the year. Both simulation models and test measurements showed...

  8. Determination of ultra-low level 129I in vegetation using pyrolysis for iodine separation and accelerator mass spectrometry measurements

    DEFF Research Database (Denmark)

    Hou, Xiaolin; Wang, Yanyun

    2016-01-01

    Radioactive isotopes of iodine are the most common radiological toxins from nuclear accidents due to their high release and high enrichment in human thyroid. Among the radioactive isotopes, long-lived 129I can not only be used for the estimation of the radioactive risk of short-lived radioactive...... and ultra-low concentration in normal environmental and biological samples, it is important to efficiently separate iodine from the sample matrix and sensitively measure 129I. However, the complicated chemical properties of iodine and high organic content in biological samples make efficient separation...... of iodine very difficult using conventional acid digestion and alkaline ashing methods. By optimizing the key parameters related to the separation of iodine by pyrolysis using a tube furnace, including carbonization temperature, heating protocol, combustion assisting gas, iodine volatilization process...

  9. Energy deposition evaluation for ultra-low energy electron beam irradiation systems using calibrated thin radiochromic film and Monte Carlo simulations

    Energy Technology Data Exchange (ETDEWEB)

    Matsui, S., E-mail: smatsui@gpi.ac.jp; Mori, Y. [The Graduate School for the Creation of New Photonics Industries, 1955-1 Kurematsucho, Nishiku, Hamamatsu, Shizuoka 431-1202 (Japan); Nonaka, T.; Hattori, T.; Kasamatsu, Y.; Haraguchi, D.; Watanabe, Y.; Uchiyama, K.; Ishikawa, M. [Hamamatsu Photonics K.K. Electron Tube Division, 314-5 Shimokanzo, Iwata, Shizuoka 438-0193 (Japan)

    2016-05-15

    For evaluation of on-site dosimetry and process design in industrial use of ultra-low energy electron beam (ULEB) processes, we evaluate the energy deposition using a thin radiochromic film and a Monte Carlo simulation. The response of film dosimeter was calibrated using a high energy electron beam with an acceleration voltage of 2 MV and alanine dosimeters with uncertainty of 11% at coverage factor 2. Using this response function, the results of absorbed dose measurements for ULEB were evaluated from 10 kGy to 100 kGy as a relative dose. The deviation between the responses of deposit energy on the films and Monte Carlo simulations was within 15%. As far as this limitation, relative dose estimation using thin film dosimeters with response function obtained by high energy electron irradiation and simulation results is effective for ULEB irradiation processes management.

  10. Space heating with ultra-low-temperature district heating - a case study of four single-family houses from the 1980s

    DEFF Research Database (Denmark)

    Østergaard, Dorte Skaarup; Svendsen, Svend

    2017-01-01

    . These benefits can be maximized if district heating temperatures are lowered as much as possible. In this paper we report on a project where 18 Danish single-family houses from the 1980s were supplied by ultra-low temperature district heating with a supply temperature as low as 45 degrees C for the main part...... of the year. The houses were heated by the existing hydraulic radiator systems, while domestic hot water was prepared by use of district heating and electric boosting. This paper evaluated the heating system temperatures that were necessary in order to maintain thermal comfort in four of the houses. First...... the four houses were modelled in the building simulation tool IDA ICE. The simulation models included the actual radiator sizes and the models were used to simulate the expected thermal comfort in the houses and resulting district heating return temperatures. Secondly measurements of the actual district...

  11. Modulational instability of ultra-low-frequency shear dust Alfvén waves in a plasma medium of positive and negatively charged dust fluids

    International Nuclear Information System (INIS)

    Mamun, A. A.

    2014-01-01

    The propagation of finite amplitude ultra-low-frequency shear dust Alfvén (SDA) waves, and their modulational instability in a magnetized plasma medium of positive and negatively charged dust fluids have been theoretically investigated by using the reductive perturbation method. The derivative nonlinear Schrödinger equation is derived to examine the stability analysis of such SDA waves. It is found that the SDA waves propagating in such an opposite polarity dust plasma medium are modulationally unstable, and that the instability criterion and the growth rate of these unstable SDA waves in such a novel opposite polarity dust plasma medium are found to be significantly different from those in electron–ion or electron–positron plasma media. The implications of the present investigation in different space environments and laboratory devices are briefly discussed.

  12. Long range surface plasmon resonance with ultra-high penetration depth for self-referenced sensing and ultra-low detection limit using diverging beam approach

    Energy Technology Data Exchange (ETDEWEB)

    Isaacs, Sivan, E-mail: sivan.isaacs@gmail.com; Abdulhalim, Ibrahim [Department of Electro-Optical Engineering and TheIlse Katz Institute for Nanoscale Science and Technology, Ben Gurion University of the Negev, Beer Sheva 84105 (Israel); NEW CREATE Programme, School of Materials Science and Engineering, 1 CREATE Way, Research Wing, #02-06/08, Singapore 138602 (Singapore)

    2015-05-11

    Using an insulator-metal-insulator structure with dielectric having refractive index (RI) larger than the analyte, long range surface plasmon (SP) resonance exhibiting ultra-high penetration depth is demonstrated for sensing applications of large bioentities at wavelengths in the visible range. Based on the diverging beam approach in Kretschmann-Raether configuration, one of the SP resonances is shown to shift in response to changes in the analyte RI while the other is fixed; thus, it can be used as a built in reference. The combination of the high sensitivity, high penetration depth and self-reference using the diverging beam approach in which a dark line is detected of the high sensitivity, high penetration depth, self-reference, and the diverging beam approach in which a dark line is detected using large number of camera pixels with a smart algorithm for sub-pixel resolution, a sensor with ultra-low detection limit is demonstrated suitable for large bioentities.

  13. Helical CT for lung-cancer screening. 3. Fundamental study for ultra-low-dose CT by application of small tube current and filter

    International Nuclear Information System (INIS)

    Itoh, Shigeki; Koyama, Shuji; Tusaka, Masatoshi; Maekoshi, Hisashi; Satake, Hiroko; Ishigaki, Takeo.

    1996-01-01

    In order to develop ultra-low-dose helical CT for lung cancer screening, the effect of reduction of the tube current to 20 mA and application of a 10 mm thick aluminium filter upon radiation dose and image quality was evaluated with a phantom. Exposure dose at the center of a gantry and absorbed dose at the center of an acrylic phantom at 20 mA with the filter were 15% and 29% of the dose at 50 mA without the filter, respectively. For reduction of absorbed dose, reduction of the tube current was more useful than application of the filter. Image noise at 20 mA with the filter was double that at 50 mA without the filter. Neither reduction of the tube current nor application of the filter changed full width at half maximum on section sensitivity of the Z-axis. Although reduction of the tube current did not affect the difference in CT values between an acrylic sphere and styroform, application of the filter caused a reduction of 4.5% in the difference in CT values. Neither reduction of the tube current nor application of the filter affected the contrast resolution of the high-contrast phantom; however, that of the low-contrast phantom deteriorated. Although improvement of the filter and evaluation of clinical images are necessary, reduction of the tube current to 20 mA and application of the aluminium filter appear to be a promising method for ultra-low-dose helical CT of the lung. (author)

  14. Evaluation of the liver in normal subjects and cases of hepatic diseases by ultra-low field (0.02 T) magnetic resonance imaging

    International Nuclear Information System (INIS)

    Iwasaki, Yoshie

    1988-01-01

    A total of 123 cases (45 controls, 14 liver cirrhoses, 6 fatty livers, 22 cavernous hemangiomas, 14 hepatomas, 9 metastases, 10 cysts, and 3 hemorrhagic cysts) were studied by ultra-low field magnetic resonance imaging. On T1-weighted images, the means of the intesity ratio in controls were 0.703±0.074 (liver to spleen), 0.658±0.073 (liver to kidney) and 0.932±0.058 (spleen to kidney). On T2-weighted images, the means of the intensity ratios in controls were 0.449±0.083 (liver to spleen), 0.363±0.069 (liver to kidney) and 0.822±0.115 (spleen to kidney). In liver cirrhosis, on T2-weighted images, the intensity ratio of liver to kidney and spleen to kidney. In liver cirrhosis were significantly higher than those in controls. In fatty liver, the intensity ratio of liver to spleen on T1-weighted image, and those of liver to spleen and liver to kidney on T2-weighted image were higher than those in controls. On T2-weighted images, the intensity ratio of tumor to liver in hepatic cavernous hemangioma were significantly higher than those in hepatocellular carcinoma and metastatic liver tumor. Ultra-low field magnetic resonance imaging with the intensity ratio of tumor to liver was valuable in distinguishing between hepatic cavernous hemangioma and hepatic malignancies and it was also possible to distinguish hemorrhagic liver cyst from non-hemorrhagic liver cyst. (author)

  15. Production induced boiling and cold water entry in the Cerro Prieto geothermal reservoir indicated by chemical and physical measurements

    Energy Technology Data Exchange (ETDEWEB)

    Grant, M.A. (DSIR, Wellington, New Zealand); Truesdell, A.H.; Manon, A.

    1981-01-01

    Chemical and physical data suggest that the relatively shallow western part of the Cerro Prieto reservoir is bounded below by low permeability rocks, and above and at the sides by an interface with cooler water. There is no continuous permeability barrier around or immediately above the reservoir. Permeability within the reservoir is dominantly intergranular. Mixture with cooler water rather than boiling is the dominant cooling process in the natural state, and production causes displacement of hot water by cooler water, not by vapor. Local boiling occurs near most wells in response to pressure decreases, but no general vapor zone has formed.

  16. Characteristics of volcanic reservoirs and distribution rules of effective reservoirs in the Changling fault depression, Songliao Basin

    Directory of Open Access Journals (Sweden)

    Pujun Wang

    2015-11-01

    Full Text Available In the Songliao Basin, volcanic oil and gas reservoirs are important exploration domains. Based on drilling, logging, and 3D seismic (1495 km2 data, 546 sets of measured physical properties and gas testing productivity of 66 wells in the Changling fault depression, Songliao Basin, eruptive cycles and sub-lithofacies were distinguished after lithologic correction of the 19,384 m volcanic well intervals, so that a quantitative analysis was conducted on the relation between the eruptive cycles, lithologies and lithofacies and the distribution of effective reservoirs. After the relationship was established between lithologies, lithofacies & cycles and reservoir physical properties & oil and gas bearing situations, an analysis was conducted on the characteristics of volcanic reservoirs and the distribution rules of effective reservoirs. It is indicated that 10 eruptive cycles of 3 sections are totally developed in this area, and the effective reservoirs are mainly distributed at the top cycles of eruptive sequences, with those of the 1st and 3rd Members of Yingcheng Formation presenting the best reservoir properties. In this area, there are mainly 11 types of volcanic rocks, among which rhyolite, rhyolitic tuff, rhyolitic tuffo lava and rhyolitic volcanic breccia are the dominant lithologies of effective reservoirs. In the target area are mainly developed 4 volcanic lithofacies (11 sub-lithofacies, among which upper sub-lithofacies of effusive facies and thermal clastic sub-lithofacies of explosion lithofacies are predominant in effective reservoirs. There is an obvious corresponding relationship between the physical properties of volcanic reservoirs and the development degree of effective reservoirs. The distribution of effective reservoirs is controlled by reservoir physical properties, and the formation of effective reservoirs is influenced more by porosity than by permeability. It is concluded that deep volcanic gas exploration presents a good

  17. Production Optimization of Oil Reservoirs

    DEFF Research Database (Denmark)

    Völcker, Carsten

    with emphasis on optimal control of water ooding with the use of smartwell technology. We have implemented immiscible ow of water and oil in isothermal reservoirs with isotropic heterogenous permeability elds. We use the method of lines for solution of the partial differential equation (PDE) system that governs...... the uid ow. We discretize the the two-phase ow model spatially using the nite volume method (FVM), and we use the two point ux approximation (TPFA) and the single-point upstream (SPU) scheme for computing the uxes. We propose a new formulation of the differential equation system that arise...... as a consequence of the spatial discretization of the two-phase ow model. Upon discretization in time, the proposed equation system ensures the mass conserving property of the two-phase ow model. For the solution of the spatially discretized two-phase ow model, we develop mass conserving explicit singly diagonally...

  18. Possibility of predicting the water drive mechanism of oil bearing reservoirs before its exploitation

    Energy Technology Data Exchange (ETDEWEB)

    Cubric, S

    1971-10-01

    The study deals with the application of Van Everdingen and Hurst's method to prediction of water influx from aquifer into an oil-bearing part of a reservoir. The examples show an influence of the factors affecting the water influx (time, permeability, ratio of radii of the aquifer, and oil-bearing part of reservoir.)

  19. Development of a segmentation method for analysis of Campos basin typical reservoir rocks

    Energy Technology Data Exchange (ETDEWEB)

    Rego, Eneida Arendt; Bueno, Andre Duarte [Universidade Estadual do Norte Fluminense Darcy Ribeiro (UENF), Macae, RJ (Brazil). Lab. de Engenharia e Exploracao de Petroleo (LENEP)]. E-mails: eneida@lenep.uenf.br; bueno@lenep.uenf.br

    2008-07-01

    This paper represents a master thesis proposal in Exploration and Reservoir Engineering that have the objective to development a specific segmentation method for digital images of reservoir rocks, which produce better results than the global methods available in the bibliography for the determination of rocks physical properties as porosity and permeability. (author)

  20. Biopolymer system for permeability modification in porous media

    Energy Technology Data Exchange (ETDEWEB)

    Stepp, A.K.; Bryant, R.S.; Llave, F.M. [BMD-Oklahoma, Inc., Bartlesville, OK (United States)] [and others

    1995-12-31

    New technologies are needed to reduce the current high rate of well abandonment. Improved sweep efficiency, reservoir conformance, and permeability modification can have a significant impact on oil recovery processes. Microorganisms can be used to selectively plug high-permeability zones to improve sweep efficiency and impart conformance control. Studies of a promising microbial system for polymer production were conducted to evaluate reservoir conditions in which this system would be effective. Factors which can affect microbial growth and polymer production include salinity, pH, temperature, divalent ions, presence of residual oil, and rock matrix. Flask tests and coreflooding experiments were conducted to optimize and evaluate the effectiveness of this system. Nuclear magnetic resonance imaging (NMRI) was used to visualize microbial polymer production in porous media. Changes in fluid distribution within the pore system of the core were detected.