WorldWideScience

Sample records for hydrate-bearing core kinetic

  1. Multiple-pressure-tapped core holder combined with X-ray computed tomography scanning for gas-water permeability measurements of methane-hydrate-bearing sediments

    Science.gov (United States)

    Konno, Yoshihiro; Jin, Yusuke; Uchiumi, Takashi; Nagao, Jiro

    2013-06-01

    We present a novel setup for measuring the effective gas-water permeability of methane-hydrate-bearing sediments. We developed a core holder with multiple pressure taps for measuring the pressure gradient of the gas and water phases. The gas-water flooding process was simultaneously detected using an X-ray computed tomography scanner. We successfully measured the effective gas-water permeability of an artificial sandy core with methane hydrate during the gas-water flooding test.

  2. Grain-scale imaging and compositional characterization of cryo-preserved India NGHP 01 gas-hydrate-bearing cores

    Science.gov (United States)

    Stern, Laura A.; Lorenson, T.D.

    2014-01-01

    We report on grain-scale characteristics and gas analyses of gas-hydrate-bearing samples retrieved by NGHP Expedition 01 as part of a large-scale effort to study gas hydrate occurrences off the eastern-Indian Peninsula and along the Andaman convergent margin. Using cryogenic scanning electron microscopy, X-ray spectroscopy, and gas chromatography, we investigated gas hydrate grain morphology and distribution within sediments, gas hydrate composition, and methane isotopic composition of samples from Krishna–Godavari (KG) basin and Andaman back-arc basin borehole sites from depths ranging 26 to 525 mbsf. Gas hydrate in KG-basin samples commonly occurs as nodules or coarse veins with typical hydrate grain size of 30–80 μm, as small pods or thin veins 50 to several hundred microns in width, or disseminated in sediment. Nodules contain abundant and commonly isolated macropores, in some places suggesting the original presence of a free gas phase. Gas hydrate also occurs as faceted crystals lining the interiors of cavities. While these vug-like structures constitute a relatively minor mode of gas hydrate occurrence, they were observed in near-seafloor KG-basin samples as well as in those of deeper origin (>100 mbsf) and may be original formation features. Other samples exhibit gas hydrate grains rimmed by NaCl-bearing material, presumably produced by salt exclusion during original hydrate formation. Well-preserved microfossil and other biogenic detritus are also found within several samples, most abundantly in Andaman core material where gas hydrate fills microfossil crevices. The range of gas hydrate modes of occurrence observed in the full suite of samples suggests a range of formation processes were involved, as influenced by local in situconditions. The hydrate-forming gas is predominantly methane with trace quantities of higher molecular weight hydrocarbons of primarily microbial origin. The composition indicates the gas hydrate is Structure I.

  3. Thermal conductivity of hydrate-bearing sediments

    Science.gov (United States)

    Cortes, Douglas D.; Martin, Ana I.; Yun, Tae Sup; Francisca, Franco M.; Santamarina, J. Carlos; Ruppel, Carolyn

    2009-11-01

    A thorough understanding of the thermal conductivity of hydrate-bearing sediments is necessary for evaluating phase transformation processes that would accompany energy production from gas hydrate deposits and for estimating regional heat flow based on the observed depth to the base of the gas hydrate stability zone. The coexistence of multiple phases (gas hydrate, liquid and gas pore fill, and solid sediment grains) and their complex spatial arrangement hinder the a priori prediction of the thermal conductivity of hydrate-bearing sediments. Previous studies have been unable to capture the full parameter space covered by variations in grain size, specific surface, degree of saturation, nature of pore filling material, and effective stress for hydrate-bearing samples. Here we report on systematic measurements of the thermal conductivity of air dry, water- and tetrohydrofuran (THF)-saturated, and THF hydrate-saturated sand and clay samples at vertical effective stress of 0.05 to 1 MPa (corresponding to depths as great as 100 m below seafloor). Results reveal that the bulk thermal conductivity of the samples in every case reflects a complex interplay among particle size, effective stress, porosity, and fluid-versus-hydrate filled pore spaces. The thermal conductivity of THF hydrate-bearing soils increases upon hydrate formation although the thermal conductivities of THF solution and THF hydrate are almost the same. Several mechanisms can contribute to this effect including cryogenic suction during hydrate crystal growth and the ensuing porosity reduction in the surrounding sediment, increased mean effective stress due to hydrate formation under zero lateral strain conditions, and decreased interface thermal impedance as grain-liquid interfaces are transformed into grain-hydrate interfaces.

  4. Thermal conductivity of hydrate-bearing sediments

    Science.gov (United States)

    Cortes, D.D.; Martin, A.I.; Yun, T.S.; Francisca, F.M.; Santamarina, J.C.; Ruppel, C.

    2009-01-01

    A thorough understanding of the thermal conductivity of hydrate-bearing sediments is necessary for evaluating phase transformation processes that would accompany energy production from gas hydrate deposits and for estimating regional heat flow based on the observed depth to the base of the gas hydrate stability zone. The coexistence of multiple phases (gas hydrate, liquid and gas pore fill, and solid sediment grains) and their complex spatial arrangement hinder the a priori prediction of the thermal conductivity of hydrate-bearing sediments. Previous studies have been unable to capture the full parameter space covered by variations in grain size, specific surface, degree of saturation, nature of pore filling material, and effective stress for hydrate-bearing samples. Here we report on systematic measurements of the thermal conductivity of air dry, water- and tetrohydrofuran (THF)-saturated, and THF hydrate-saturated sand and clay samples at vertical effective stress of 0.05 to 1 MPa (corresponding to depths as great as 100 m below seafloor). Results reveal that the bulk thermal conductivity of the samples in every case reflects a complex interplay among particle size, effective stress, porosity, and fluid-versus-hydrate filled pore spaces. The thermal conductivity of THF hydrate-bearing soils increases upon hydrate formation although the thermal conductivities of THF solution and THF hydrate are almost the same. Several mechanisms can contribute to this effect including cryogenic suction during hydrate crystal growth and the ensuing porosity reduction in the surrounding sediment, increased mean effective stress due to hydrate formation under zero lateral strain conditions, and decreased interface thermal impedance as grain-liquid interfaces are transformed into grain-hydrate interfaces. Copyright 2009 by the American Geophysical Union.

  5. Methane Recovery from Hydrate-bearing Sediments

    Energy Technology Data Exchange (ETDEWEB)

    J. Carlos Santamarina; Costas Tsouris

    2011-04-30

    Gas hydrates are crystalline compounds made of gas and water molecules. Methane hydrates are found in marine sediments and permafrost regions; extensive amounts of methane are trapped in the form of hydrates. Methane hydrate can be an energy resource, contribute to global warming, or cause seafloor instability. This study placed emphasis on gas recovery from hydrate bearing sediments and related phenomena. The unique behavior of hydrate-bearing sediments required the development of special research tools, including new numerical algorithms (tube- and pore-network models) and experimental devices (high pressure chambers and micromodels). Therefore, the research methodology combined experimental studies, particle-scale numerical simulations, and macro-scale analyses of coupled processes. Research conducted as part of this project started with hydrate formation in sediment pores and extended to production methods and emergent phenomena. In particular, the scope of the work addressed: (1) hydrate formation and growth in pores, the assessment of formation rate, tensile/adhesive strength and their impact on sediment-scale properties, including volume change during hydrate formation and dissociation; (2) the effect of physical properties such as gas solubility, salinity, pore size, and mixed gas conditions on hydrate formation and dissociation, and it implications such as oscillatory transient hydrate formation, dissolution within the hydrate stability field, initial hydrate lens formation, and phase boundary changes in real field situations; (3) fluid conductivity in relation to pore size distribution and spatial correlation and the emergence of phenomena such as flow focusing; (4) mixed fluid flow, with special emphasis on differences between invading gas and nucleating gas, implications on relative gas conductivity for reservoir simulations, and gas recovery efficiency; (5) identification of advantages and limitations in different gas production strategies with

  6. Strengthening mechanism of cemented hydrate-bearing sand at microscales

    Science.gov (United States)

    Yoneda, Jun; Jin, Yusuke; Katagiri, Jun; Tenma, Norio

    2016-07-01

    On the basis of hypothetical particle-level mechanisms, several constitutive models of hydrate-bearing sediments have been proposed previously for gas production. However, to the best of our knowledge, the microstructural large-strain behaviors of hydrate-bearing sediments have not been reported to date because of the experimental challenges posed by the high-pressure and low-temperature testing conditions. Herein, a novel microtriaxial testing apparatus was developed, and the mechanical large-strain behavior of hydrate-bearing sediments with various hydrate saturation values (Sh = 0%, 39%, and 62%) was analyzed using microfocus X-ray computed tomography. Patchy hydrates were observed in the sediments at Sh = 39%. The obtained stress-strain relationships indicated strengthening with increasing hydrate saturation and a brittle failure mode of the hydrate-bearing sand. Localized deformations were quantified via image processing at the submillimeter and micrometer scale. Shear planes and particle deformation and/or rotation were detected, and the shear band thickness decreased with increasing hydrate saturation.

  7. Geomechanical Performance of Hydrate-Bearing Sediments in Offshore Environments

    Energy Technology Data Exchange (ETDEWEB)

    Stephen A. Holditch

    2006-12-31

    The main objective of this study is to develop the necessary knowledge base and quantitative predictive capability for the description of geomechanical performance of hydrate bearing sediments (hereafter referred to as HBS) in oceanic environments. The focus is on the determination of the envelope of hydrate stability under conditions typical of those related to the construction and operation of offshore platforms. To achieve this objective, we have developed a robust numerical simulator of hydrate behavior in geologic media by coupling a reservoir model with a commercial geomechanical code. To be sure our geomechanical modeling is realistic, we are also investigating the geomechanical behavior of oceanic HBS using pore-scale models (conceptual and mathematical) of fluid flow, stress analysis, and damage propagation. In Phase II of the project, we will review all published core data and generate additional core data to verify the models. To generate data for our models, we are using data from the literature and we will be conducting laboratory studies in 2007 that generate data to (1) evaluate the conceptual pore-scale models, (2) calibrate the mathematical models, (3) determine dominant relations and critical parameters defining the geomechanical behavior of HBS, and (4) establish relationships between the geomechanical status of HBS and the corresponding geophysical signature. The milestones for Phase I of this project are given as follows: Literature survey on typical sediments containing gas hydrates in the ocean (TAMU); Recommendations on how to create typical sediments in the laboratory (TAMU); Demonstrate that typical sediments can be created in a repeatable manner in the laboratory and gas hydrates can be created in the pore space (TAMU); Develop a conceptual pore-scale model based on available data and reports (UCB); Test the developed pore-scale concepts on simple configurations and verify the results against known measurements and observations (UCB

  8. Water retention curve for hydrate-bearing sediments

    Science.gov (United States)

    Dai, Sheng; Santamarina, J. Carlos

    2013-11-01

    water retention curve plays a central role in numerical algorithms that model hydrate dissociation in sediments. The determination of the water retention curve for hydrate-bearing sediments faces experimental difficulties, and most studies assume constant water retention curves regardless of hydrate saturation. This study employs network model simulation to investigate the water retention curve for hydrate-bearing sediments. Results show that (1) hydrate in pores shifts the curve to higher capillary pressures and the air entry pressure increases as a power function of hydrate saturation; (2) the air entry pressure is lower in sediments with patchy rather than distributed hydrate, with higher pore size variation and pore connectivity or with lower specimen slenderness along the flow direction; and (3) smaller specimens render higher variance in computed water retention curves, especially at high water saturation Sw > 0.7. Results are relevant to other sediment pore processes such as bioclogging and mineral precipitation.

  9. Methane Flux and Authigenic Carbonate in Shallow Sediments Overlying Methane Hydrate Bearing Strata in Alaminos Canyon, Gulf of Mexico

    Directory of Open Access Journals (Sweden)

    Joseph P. Smith

    2014-09-01

    Full Text Available In June 2007 sediment cores were collected in Alaminos Canyon, Gulf of Mexico across a series of seismic data profiles indicating rapid transitions between the presence of methane hydrates and vertical gas flux. Vertical profiles of dissolved sulfate, chloride, calcium, magnesium, and dissolved inorganic carbon (DIC concentrations in porewaters, headspace methane, and solid phase carbonate concentrations were measured at each core location to investigate the cycling of methane-derived carbon in shallow sediments overlying the hydrate bearing strata. When integrated with stable carbon isotope ratios of DIC, geochemical results suggest a significant fraction of the methane flux at this site is cycled into the inorganic carbon pool. The incorporation of methane-derived carbon into dissolved and solid inorganic carbon phases represents a significant sink in local carbon cycling and plays a role in regulating the flux of methane to the overlying water column at Alaminos Canyon. Targeted, high-resolution geochemical characterization of the biogeochemical cycling of methane-derived carbon in shallow sediments overlying hydrate bearing strata like those in Alaminos Canyon is critical to quantifying methane flux and estimating methane hydrate distributions in gas hydrate bearing marine sediments.

  10. Chemical and isotopic characteristics of gas hydrate- and pore-water samples obtained from gas hydrate-bearing sediment cores retrieved from a mud volcano in the Kukuy Canyon, Lake Baikal

    Energy Technology Data Exchange (ETDEWEB)

    Minami, H.; Hachikubo, A.; Krylov, A.; Sakagami, H.; Ohashi, M.; Bai, J.; Kataoka, S.; Yamashita, S.; Takahashi, N.; Shoji, H. [Kitami Inst. of Technology, Kitami (Japan); Khlystov, O.; Zemskaya, T.; Grachev, M. [Russian Academy of Sciences, Irkutsk (Russian Federation). Limnological Inst.

    2008-07-01

    This paper provided details of a method developed to obtain gas hydrate water samples from a mud volcano in Lake Baikal, Russia. Chemical and isotopic analyses were conducted to examine the hydrate and pore water samples as well as to evaluate the original water involved in shallow gas hydrate accumulations in the region. Lake sediment core samples were retrieved from the bottom of the lake with gravity corers. A squeezer was used to take pore water samples from the sediments. Hydrate samples were taken from a gas hydrate placed on a polyethylene funnel. Dissolved hydrate water was filtered through a membrane into bottles. Both samples were kept under chilled or liquid nitrogen temperatures. Ion chromatography was used to determine concentrations of anions and hydrogen carbonate ions. Sodium and magnesium concentrations were determined using an inductively coupled plasma atomic emission spectrometer. An absorption spectrometer was used to determine potassium and calcium concentrations, and a mass spectrometer was used to analyze stable isotopes of oxygen and hydrogen. Results of the study suggested that the gas dissolved in pore water and adsorbed on the surfaces of sediment particles was not the original gas from the hydrates retrieved at the mud volcano. Original gas hydrate-forming fluids were chemically different from the pore- and lake-water samples. The oxygen isotopic composition of the gas hydrate water samples correlated well with hydrogen values. It was concluded that ascending fluid and water delivered the gas into the gas stability zone, and is the main gas hydrate-forming fluid in the area of study. 12 refs., 1 fig.

  11. Hydro-bio-geomechanical properties of hydrate-bearing sediments from Nankai Trough

    Science.gov (United States)

    Santamarina, J.C.; Dai, Shifeng; Terzariol, M.; Jang, Jeonghwan; Waite, William F.; Winters, William J.; Nagao, J.; Yoneda, J.; Konno, Y.; Fujii, T.; Suzuki, K.

    2015-01-01

    Natural hydrate-bearing sediments from the Nankai Trough, offshore Japan, were studied using the Pressure Core Characterization Tools (PCCTs) to obtain geomechanical, hydrological, electrical, and biological properties under in situ pressure, temperature, and restored effective stress conditions. Measurement results, combined with index-property data and analytical physics-based models, provide unique insight into hydrate-bearing sediments in situ. Tested cores contain some silty-sands, but are predominantly sandy- and clayey-silts. Hydrate saturations Sh range from 0.15 to 0.74, with significant concentrations in the silty-sands. Wave velocity and flexible-wall permeameter measurements on never-depressurized pressure-core sediments suggest hydrates in the coarser-grained zones, the silty-sands where Sh exceeds 0.4, contribute to soil-skeletal stability and are load-bearing. In the sandy- and clayey-silts, where Sh < 0.4, the state of effective stress and stress history are significant factors determining sediment stiffness. Controlled depressurization tests show that hydrate dissociation occurs too quickly to maintain thermodynamic equilibrium, and pressure–temperature conditions track the hydrate stability boundary in pure-water, rather than that in seawater, in spite of both the in situ pore water and the water used to maintain specimen pore pressure prior to dissociation being saline. Hydrate dissociation accompanied with fines migration caused up to 2.4% vertical strain contraction. The first-ever direct shear measurements on never-depressurized pressure-core specimens show hydrate-bearing sediments have higher sediment strength and peak friction angle than post-dissociation sediments, but the residual friction angle remains the same in both cases. Permeability measurements made before and after hydrate dissociation demonstrate that water permeability increases after dissociation, but the gain is limited by the transition from hydrate saturation

  12. THCM Coupled Model for Hydrate-Bearing Sediments: Data Analysis and Design of New Field Experiments (Marine and Permafrost Settings)

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, Marcelo J. [Texas A & M Univ., College Station, TX (United States); Santamarina, J. Carlos [King Abdullah Univ. of Science and Technology (Saudi Arabia)

    2017-02-14

    Gas hydrates are solid compounds made of water molecules clustered around low molecular weight gas molecules such as methane, hydrogen, and carbon dioxide. Methane hydrates form under pressure (P) and temperature (T) conditions that are common in sub-permafrost layers and in deep marine sediments. Stability conditions constrain the occurrence of gas hydrates to submarine sediments and permafrost regions. The amount of technically recoverable methane trapped in gas hydrate may exceed 104tcf. Gas hydrates are a potential energy resource, can contribute to climate change, and can cause large-scale seafloor instabilities. In addition, hydrate formation can be used for CO2 sequestration (also through CO2-CH4 replacement), and efficient geological storage seals. The experimental study of hydrate bearing sediments has been hindered by the very low solubility of methane in water (lab testing), and inherent sampling difficulties associated with depressurization and thermal changes during core extraction. This situation has prompted more decisive developments in numerical modeling in order to advance the current understanding of hydrate bearing sediments, and to investigate/optimize production strategies and implications. The goals of this research has been to addresses the complex thermo-hydro-chemo-mechanical THCM coupled phenomena in hydrate-bearing sediments, using a truly coupled numerical model that incorporates sound and proven constitutive relations, satisfies fundamental conservation principles. Analytical solutions aimed at verifying the proposed code have been proposed as well. These tools will allow to better analyze available data and to further enhance the current understanding of hydrate bearing sediments in view of future field experiments and the development of production technology.

  13. Stability Analysis of Methane Hydrate-Bearing Soils Considering Dissociation

    Directory of Open Access Journals (Sweden)

    Hiromasa Iwai

    2015-06-01

    Full Text Available It is well known that the methane hydrate dissociation process may lead to unstable behavior such as large ground deformations, uncontrollable gas production, etc. A linear instability analysis was performed in order to investigate which variables have a significant effect on the onset of the instability behavior of methane hydrate-bearing soils subjected to dissociation. In the analysis a simplified viscoplastic constitutive equation is used for the soil sediment. The stability analysis shows that the onset of instability of the material system mainly depends on the strain hardening-softening parameter, the degree of strain, and the permeability for water and gas. Then, we conducted a numerical analysis of gas hydrate-bearing soil considering hydrate dissociation in order to investigate the effect of the parameters on the system. The simulation method used in the present study can describe the chemo-thermo-mechanically coupled behaviors such as phase changes from hydrates to water and gas, temperature changes and ground deformation. From the numerical results, we found that basically the larger the permeability for water and gas is, the more stable the simulation results are. These results are consistent with those obtained from the linear stability analysis.

  14. Geomechanical Performance of Hydrate-Bearing Sediment in Offshore Environments

    Energy Technology Data Exchange (ETDEWEB)

    Stephen Holditch; Tad Patzek; Jonny Rutqvist; George Moridis; Richard Plumb

    2008-03-31

    The objective of this multi-year, multi-institutional research project was to develop the knowledge base and quantitative predictive capability for the description of geomechanical performance of hydrate-bearing sediments (hereafter referred to as HBS) in oceanic environments. The focus was on the determination of the envelope of hydrate stability under conditions typical of those related to the construction and operation of offshore platforms. We have developed a robust numerical simulator of hydrate behavior in geologic media by coupling a reservoir model with a commercial geomechanical code. We also investigated the geomechanical behavior of oceanic HBS using pore-scale models (conceptual and mathematical) of fluid flow, stress analysis, and damage propagation. The objective of the UC Berkeley work was to develop a grain-scale model of hydrate-bearing sediments. Hydrate dissociation alters the strength of HBS. In particular, transformation of hydrate clusters into gas and liquid water weakens the skeleton and, simultaneously, reduces the effective stress by increasing the pore pressure. The large-scale objective of the study is evaluation of geomechanical stability of offshore oil and gas production infrastructure. At Lawrence Berkeley National Laboratory (LBNL), we have developed the numerical model TOUGH + Hydrate + FLAC3D to evaluate how the formation and disassociation of hydrates in seafloor sediments affects seafloor stability. Several technical papers were published using results from this model. LBNL also developed laboratory equipment and methods to produce realistic laboratory samples of sediments containing gas hydrates so that mechanical properties could be measured in the laboratory. These properties are required to run TOUGH + Hydrate + FLAC3D to evaluate seafloor stability issues. At Texas A&M University we performed a detailed literature review to determine what gas hydrate formation properties had been measured and reported in the literature. We

  15. Hydrate bearing clayey sediments: Formation and gas production concepts

    KAUST Repository

    Jang, Jaewon

    2016-06-20

    Hydro-thermo-chemo and mechanically coupled processes determine hydrate morphology and control gas production from hydrate-bearing sediments. Force balance, together with mass and energy conservation analyses anchored in published data provide robust asymptotic solutions that reflect governing processes in hydrate systems. Results demonstrate that hydrate segregation in clayey sediments results in a two-material system whereby hydrate lenses are surrounded by hydrate-free water-saturated clay. Hydrate saturation can reach ≈2% by concentrating the excess dissolved gas in the pore water and ≈20% from metabolizable carbon. Higher hydrate saturations are often found in natural sediments and imply methane transport by advection or diffusion processes. Hydrate dissociation is a strongly endothermic event; the available latent heat in a reservoir can sustain significant hydrate dissociation without triggering ice formation during depressurization. The volume of hydrate expands 2-to-4 times upon dissociation or CO2single bondCH4 replacement. Volume expansion can be controlled to maintain lenses open and to create new open mode discontinuities that favor gas recovery. Pore size is the most critical sediment parameter for hydrate formation and gas recovery and is controlled by the smallest grains in a sediment. Therefore any characterization must carefully consider the amount of fines and their associated mineralogy.

  16. Simulation experiments on gas production from hydrate-bearing sediments

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Experiments were made on 58 sediment samples from four sites(1244,1245,1250 and 1251) of ODP204 at five temperature points(25,35,45,55 and 65℃) to simulate methane production from hydrate-bearing sediments.Simulation results from site 1244 show that the gas components consist mainly of methane and carbon dioxide,and heavy hydrocarbons more than C2+ cannot be detected.This site also gives results,similar to those from the other three,that the methane production is controlled by experimental temperatures,generally reaching the maximum gas yields per gram sediment or TOC under lower temperatures(25 and 35 ℃).In other words,the methane amount could be related to the buried depth of sediments,given the close relation between the depth and temperature.Sediments less than 1200 m below seafloor are inferred to still act as a biogenic gas producer to pour methane into the present hydrate zone,while sedimentary layers more than 1200 m below seafloor have become too biogenically exhausted to offer any biogas,but instead they produce thermogenic gas to give additional supply to the hydrate formation in the study area.

  17. Physical property changes in hydrate-bearing sediment due to depressurization and subsequent repressurization

    Science.gov (United States)

    Waite, W.F.; Kneafsey, T.J.; Winters, W.J.; Mason, D.H.

    2008-01-01

    Physical property measurements of sediment cores containing natural gas hydrate are typically performed on material exposed, at least briefly, to non-in situ conditions during recovery. To examine the effects of a brief excursion from the gas-hydrate stability field, as can occur when pressure cores are transferred to pressurized storage vessels, we measured physical properties on laboratory-formed sand packs containing methane hydrate and methane pore gas. After depressurizing samples to atmospheric pressure, we repressurized them into the methane-hydrate stability field and remeasured their physical properties. Thermal conductivity, shear strength, acoustic compressional and shear wave amplitudes, and speeds of the original and depressurized/repressurized samples are compared. X-ray computed tomography images track how the gas-hydrate distribution changes in the hydrate-cemented sands owing to the depressurizaton/repressurization process. Because depressurization-induced property changes can be substantial and are not easily predicted, particularly in water-saturated, hydrate-bearing sediment, maintaining pressure and temperature conditions throughout the core recovery and measurement process is critical for using laboratory measurements to estimate in situ properties.

  18. Polyethylene Glycol Drilling Fluid for Drilling in Marine Gas Hydrates-Bearing Sediments: An Experimental Study

    Directory of Open Access Journals (Sweden)

    Lixin Kuang

    2011-01-01

    Full Text Available Shale inhibition, low-temperature performance, the ability to prevent calcium and magnesium-ion pollution, and hydrate inhibition of polyethylene glycol drilling fluid were each tested with conventional drilling-fluid test equipment and an experimental gas-hydrate integrated simulation system developed by our laboratory. The results of these tests show that drilling fluid with a formulation of artificial seawater, 3% bentonite, 0.3% Na2CO3, 10% polyethylene glycol, 20% NaCl, 4% SMP-2, 1% LV-PAC, 0.5% NaOH and 1% PVP K-90 performs well in shale swelling and gas hydrate inhibition. It also shows satisfactory rheological properties and lubrication at temperature ranges from −8 °C to 15 °C. The PVP K-90, a kinetic hydrate inhibitor, can effectively inhibit gas hydrate aggregations at a dose of 1 wt%. This finding demonstrates that a drilling fluid with a high addition of NaCl and a low addition of PVP K-90 is suitable for drilling in natural marine gas-hydrate-bearing sediments.

  19. Methane hydrate-bearing sediments in the Terrebonne basin, northern Gulf of Mexico

    Science.gov (United States)

    Meazell, K.; Flemings, P. B.

    2015-12-01

    We characterize the geological, geophysical, and thermodynamic state of three dipping, hydrate-bearing sands in the Terrebonne mini basin of the northern Gulf of Mexico, and describe three potential drilling locations to sample these hydrate reservoirs. Within the sand bodies, there is a prominent negative polarity seismic reflection (opposite phase to the seafloor reflector) that we interpret to record the boundary between gas hydrate above and free gas below. This anomaly is the Bottom Simulating Reflector (BSR) and the base of the Gas Hydrate Stability Zone (BGHSZ). Above the BSR, reflection seismic data record these reservoirs with a positive polarity while below it, they record the reservoirs with a negative polarity event. Within the sand bodies, seismic amplitudes are generally strongest immediately above and below the BSR and weaken in updip and downdip directions. Beneath the BSR, two of the reservoirs have a strong negative amplitude event that parallels structure that we interpret to record a gas-water contact, while the third reservoir does not clearly record this behavior. Much like the seafloor, the BSR is bowl-shaped, occurring at greatest depths in the northwest and rising near salt bodies in the south and east. In the north east area of previous exploration, the BSR is found at a depth of 2868 meters below sealevel, implying a geothermal gradient of 20.1oC/km for type I hydrates. Logging while drilling data reveal that the sands are composed of numerous thin, hydrocarbon-charged, coarse-grained sediments. Hydrate saturation in these sands is greatest near the BGHSZ. Pressure coring is proposed for three wells that will penetrate the reservoirs at different structural elevations in order to further elucidate reservoir conditions of the sands.

  20. Model-based temperature measurement system development for marine methane hydrate-bearing sediments

    Energy Technology Data Exchange (ETDEWEB)

    Fukuhara, Masafumi; Sugiyama, Hitoshi; Igarashi, Juei; Fujii, Kasumi; Shun' etsu, Onodera; Tertychnyi, Vladimir; Shandrygin, Alexander; Pimenov, Viacheslav; Shako, Valery; Matsubayashi, Osamu; Ochiai, Koji

    2005-07-01

    This paper describes the effect of the sensor installation on the temperature of the hydrate-bearing sediments through modeling, how the system was deployed in Nankai Trough area in Japan, and the features of the marine methane hydrate temperature measurement system. (Author)

  1. Parametric study of the physical properties of hydrate-bearing sand, silt, and clay sediments: 2. Small-strain mechanical properties

    Science.gov (United States)

    Lee, J. Y.; Francisca, F. M.; Santamarina, J. C.; Ruppel, C.

    2010-11-01

    The small-strain mechanical properties (e.g., seismic velocities) of hydrate-bearing sediments measured under laboratory conditions provide reference values for calibration of logging and seismic exploration results acquired in hydrate-bearing formations. Instrumented cells were designed for measuring the compressional (P) and shear (S) velocities of sand, silts, and clay with and without hydrate and subject to vertical effective stresses of 0.01 to 2 MPa. Tetrahydrofuran (THF), which is fully miscible in water, was used as the hydrate former to permit close control over the hydrate saturation Shyd and to produce hydrate from dissolved phase, as methane hydrate forms in most natural marine settings. The results demonstrate that laboratory hydrate formation technique controls the pattern of P and S velocity changes with increasing Shyd and that the small-strain properties of hydrate-bearing sediments are governed by effective stress, σ'v and sediment specific surface. The S velocity increases with hydrate saturation owing to an increase in skeletal shear stiffness, particularly when hydrate saturation exceeds Shyd≈ 0.4. At very high hydrate saturations, the small strain shear stiffness is determined by the presence of hydrates and becomes insensitive to changes in effective stress. The P velocity increases with hydrate saturation due to the increases in both the shear modulus of the skeleton and the bulk modulus of pore-filling phases during fluid-to-hydrate conversion. Small-strain Poisson's ratio varies from 0.5 in soft sediments lacking hydrates to 0.25 in stiff sediments (i.e., subject to high vertical effective stress or having high Shyd). At Shyd ≥ 0.5, hydrate hinders expansion and the loss of sediment stiffness during reduction of vertical effective stress, meaning that hydrate-rich natural sediments obtained through pressure coring should retain their in situ fabric for some time after core retrieval if the cores are maintained within the hydrate

  2. Evidence for Freshwater Discharge at a Gas Hydrate-Bearing Seafloor Mound on the Beaufort Sea Continental Slope

    Science.gov (United States)

    Pohlman, J.; Lorenson, T. D.; Hart, P. E.; Ruppel, C. D.; Joseph, C.; Torres, M. E.; Edwards, B. D.

    2011-12-01

    A deep-water (~2.5 km water depth) seafloor mound located ~150 km offshore of the North Slope Alaska, informally named the Canning Seafloor Mound (CSM), contains a documented occurrence of gas hydrate; the first from the Beaufort Sea. Gases and porewater extracted from cores taken at the CSM summit several months after core recovery provided surprisingly consistent and outstanding results. Gases migrating into the structure are likely a mixture of primary microbial gas formed by carbonate reduction and secondary microbial gas formed from degraded thermogenic gases, linking the system to deep oil and gas generation (see companion abstract by Lorenson et al.). Pore fluids extracted from the base of the 572 cm-long hydrate-bearing core had chloride values as low as 160 mM, which equates to an ~80% freshwater contribution. Low chloride values, often interpreted as a product of gas hydrate dissociation in hydrate-bearing cores, were coincident with sulfate values in excess of 1 mM and as high as 22 mM (seawater is ~28mM). High sulfate concentrations generally indicate an absence of methane, and, thus, gas hydrate; therefore, an allochthonous source of freshwater is required. Potential sources are clay mineral dehydration, clay membrane filtration and/or a meteoric water influx. Several lines of evidence indicate the Canning Seafloor Mound is connected to either a deep, landward freshwater aquifer or to an unusually fresh oil field brine. First, Na/Cl ratios decrease from marine (~0.86) near the seafloor to distinctly higher values of 1.20 at the bottom of the core. Second, clay dehydration and ion filtration processes have not, to our knowledge, yielded fluids as fresh as measured in these near-seafloor sediments. Third, and most importantly, δ18O-δD systematics of fluid end members are entirely consistent with a meteoric water source and inconsistent with trends expected for either gas hydrate dissociation, smectite to illite clay dewatering or ion filtration

  3. Numerical simulations of sand production in interbedded hydrate-bearing sediments during depressurization

    Science.gov (United States)

    Uchida, Shun; Lin, Jeen-Shang; Myshakin, Evgeniy; Seol, Yongkoo; Collett, Timothy S.; Boswell, Ray

    2017-01-01

    Geomechanical behavior of hydrate-bearing sediments during gas production is complex, involving changes in hydrate-dependent mechanical properties. When interbedded clay layers are present, the complexity is more pronounced because hydrate dissociation tends to occur preferentially in the sediments adjacent to the clay layers due to clay layers acting as a heat source. This would potentially lead to shearing deformation along the sand/clay contacts and may contribute to solid migration, which hindered past field-scale gas production tests. This paper presents a near-wellbore simulation of sand/clay interbedded hydrate-bearing sediments that have been subjected to depressurization and discusses the effect of clay layers on sand production.

  4. The effect of hydrate saturation on water retention curves in hydrate-bearing sediments

    Science.gov (United States)

    Mahabadi, Nariman; Zheng, Xianglei; Jang, Jaewon

    2016-05-01

    The experimental measurement of water retention curve in hydrate-bearing sediments is critically important to understand the behavior of hydrate dissociation and gas production. In this study, tetrahydrofuran (THF) is selected as hydrate former. The pore habit of THF hydrates is investigated by visual observation in a transparent micromodel. It is confirmed that THF hydrates are not wetting phase on the quartz surface of the micromodel and occupy either an entire pore or part of pore space resulting in change in pore size distribution. And the measurement of water retention curves in THF hydrate-bearing sediments with hydrate saturation ranging from Sh = 0 to Sh = 0.7 is conducted for excess water condition. The experimental results show that the gas entry pressure and the capillary pressure increase with increasing hydrate saturation. Based on the experimental results, fitting parameters for van Genuchten equation are suggested for different hydrate saturation conditions.

  5. Water permeability in hydrate-bearing sediments: A pore-scale study

    Science.gov (United States)

    Dai, Sheng; Seol, Yongkoo

    2014-06-01

    Permeability is a critical parameter governing methane flux and fluid flow in hydrate-bearing sediments; however, limited valid data are available due to experimental challenges. Here we investigate the relationship between apparent water permeability (k') and hydrate saturation (Sh), accounting for hydrate pore-scale growth habit and meso-scale heterogeneity. Results from capillary tube models rely on cross-sectional tube shapes and hydrate pore habits, thus are appropriate only for sediments with uniform hydrate distribution and known hydrate pore character. Given our pore network modeling results showing that accumulating hydrate in sediments decreases sediment porosity and increases hydraulic tortuosity, we propose a modified Kozeny-Carman model to characterize water permeability in hydrate-bearing sediments. This model agrees well with experimental results and can be easily implemented in reservoir simulators with no empirical variables other than Sh. Results are also relevant to flow through other natural sediments that undergo diagenesis, salt precipitation, or bio-clogging.

  6. Thessaloniki Mud Volcano, the Shallowest Gas Hydrate-Bearing Mud Volcano in the Anaximander Mountains, Eastern Mediterranean

    Directory of Open Access Journals (Sweden)

    C. Perissoratis

    2011-01-01

    Full Text Available A detailed multibeam survey and the subsequent gravity coring carried out in the Anaximander Mountains, Eastern Mediterranean, detected a new active gas hydrate-bearing mud volcano (MV that was named Thessaloniki. It is outlined by the 1315 m bathymetric contour, is 1.67 km2 in area, and has a summit depth of 1260 m. The sea bottom water temperature is 13.7∘C. The gas hydrate crystals generally have the form of flakes or rice, some larger aggregates of them are up to 2 cm across. A pressure core taken at the site contained 3.1 lt. of hydrocarbon gases composed of methane, nearly devoid of propane and butane. The sediment had a gas hydrate occupancy of 0.7% of the core volume. These characteristics place the gas hydrate field at Thessaloniki MV at the upper boundary of the gas hydrate stability zone, prone to dissociation with the slightest increase in sea water temperature, decrease in hydrostatic pressure, or change in the temperature of the advecting fluids.

  7. Transport Mechanisms for CO2-CH4 Exchange and Safe CO2 Storage in Hydrate-Bearing Sandstone

    Directory of Open Access Journals (Sweden)

    Knut Arne Birkedal

    2015-05-01

    Full Text Available CO2 injection in hydrate-bearing sediments induces methane (CH4 production while benefitting from CO2 storage, as demonstrated in both core and field scale studies. CH4 hydrates have been formed repeatedly in partially water saturated Bentheim sandstones. Magnetic Resonance Imaging (MRI and CH4 consumption from pump logs have been used to verify final CH4 hydrate saturation. Gas Chromatography (GC in combination with a Mass Flow Meter was used to quantify CH4 recovery during CO2 injection. The overall aim has been to study the impact of CO2 in fractured and non-fractured samples to determine the performance of CO2-induced CH4 hydrate production. Previous efforts focused on diffusion-driven exchange from a fracture volume. This approach was limited by gas dilution, where free and produced CH4 reduced the CO2 concentration and subsequent driving force for both diffusion and exchange. This limitation was targeted by performing experiments where CO2 was injected continuously into the spacer volume to maintain a high driving force. To evaluate the effect of diffusion length multi-fractured core samples were used, which demonstrated that length was not the dominating effect on core scale. An additional set of experiments is presented on non-fractured samples, where diffusion-limited transportation was assisted by continuous CO2 injection and CH4 displacement. Loss of permeability was addressed through binary gas (N2/CO2 injection, which regained injectivity and sustained CO2-CH4 exchange.

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

    Science.gov (United States)

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

    2011-01-01

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

  9. Experimental study on steam and inhibitor injection into methane hydrate bearing sediments

    Science.gov (United States)

    Kawamura, T.; Sakamoto, Y.; Temma, N.; Yamamoto, Y.; Komai, T.

    2007-12-01

    Natural gas hydrate that exists in the ocean sediment is thought to constitute a large methane gas reservoir and is expected to be an energy resource in the future. In order to make recovery of natural gas from hydrates commercially viable, hydrates must be dissociated in-situ. Inhibitor injection method is thought to be one of the effective dissociation method as well as depressurization and thermal stimulation. Meanwhile, steam injection method is practically used for oil sand to recover heavy oil and recognized as a means that is commercially successful. In this study, the inhibitor injection method and the steam injection method for methane hydrate bearing sediments have been examined and discussed on an experimental basis. New experimental apparatuses have been designed and constructed. Using these apparatuses, inhibitor and steam were successfully injected into artificial methane hydrate bearing sediments that were simulated in laboratory scale. In the case of inhibitor injection, characteristic temperature drop during dissociation was observed. And decreases of permeability that is caused by the reformation of methane hydrate were prevented effectively. In the case of steam injection, the phase transition from vapor water to liquid water in methane hydrate bearing sediments was observed. It can be concluded that roughly 44 % of total hydrate origin gas was produced after steam injection. From these approaches, the applicability of these methods as enhanced gas recovery methods are discussed.

  10. Stability evaluation of hydrate-bearing sediments during thermally-driven hydrate dissociation

    Science.gov (United States)

    Kwon, T.; Cho, G.; Santamarina, J.; Kim, H.; Lee, J.

    2009-12-01

    Hydrate-bearing sediments may destabilize spontaneously as part of geological processes, unavoidably during petroleum drilling/production operations, or intentionally as part of gas extraction from the hydrate itself. In all cases, high pore fluid pressure generation is anticipated during hydrate dissociation. This study examined how thermal changes destabilize gas hydrate-bearing sediments. First, an analytical formulation was derived for predicting fluid pressure evolution in hydrate-bearing sediments subjected to thermal stimulation without mass transfer. The formulation captures the self-preservation behavior, calculates the hydrate and free gas quantities during dissociation, considering effective stress-controlled sediment compressibility and gas solubility in aqueous phase. Pore fluid pressure generation is proportional to the initial hydrate fraction and the sediment bulk stiffness; is inversely proportional to the initial gas fraction and gas solubility; and is limited by changes in effective stress that cause the failure of the sediment. Second, the analytical formulation for hydrate dissociation was incorporated as a user-defined function into a verified finite difference code (FLAC2D). The underlying physical processes of hydrate-bearing sediments, including hydrate dissociation, self-preservation, pore pressure evolution, gas dissolution, and sediment volume expansion, were coupled with the thermal conduction, pore fluid flow, and mechanical response of sediments. We conducted the simulations for a duration of 20 years, assuming a constant-temperature wellbore transferred heat to the surrounding hydrate-bearing sediments, resulting in dissociation of methane hydrate in the well vicinity. The model predicted dissociation-induced excess pore fluid pressures which resulted in a large volume expansion and plastic deformation of the sediments. Furthermore, when the critical stress was reached, localized shear failure of the sediment around the borehole was

  11. Biogeographical distribution and diversity of microbes in methane hydrate-bearing deep marine sediments, on the Pacific Ocean Margin

    DEFF Research Database (Denmark)

    Inagaki, F.; Nunoura, T.; Nakagawa, S.

    2006-01-01

    The deep subseafloor biosphere is among the least-understood habitats on Earth, even though the huge microbial biomass therein plays an important role for potential long-term controls on global biogeochemical cycles. We report here the vertical and geographical distribution of microbes and their ......The deep subseafloor biosphere is among the least-understood habitats on Earth, even though the huge microbial biomass therein plays an important role for potential long-term controls on global biogeochemical cycles. We report here the vertical and geographical distribution of microbes...... in prokaryotic distribution patterns in sediments with or without methane hydrates, we studied > 2,800 clones possessing partial sequences (400-500 bp) of the 16S rRNA gene and 348 representative clone sequences (approximate to 1 kbp) from the two geographically separated subseafloor environments. Archaea...... of the JS1 group, Planctomycetes, and Chloroflexi. Results from cluster and principal component analyses, which include previously reported data from the West and East Pacific Margins, suggest that, For these locations in the Pacific Ocean, prokaryotic communities from methane hydrate-bearing sediment cores...

  12. A constitutive mechanical model for gas hydrate bearing sediments incorporating inelastic mechanisms

    KAUST Repository

    Sánchez, Marcelo

    2016-11-30

    Gas hydrate bearing sediments (HBS) are natural soils formed in permafrost and sub-marine settings where the temperature and pressure conditions are such that gas hydrates are stable. If these conditions shift from the hydrate stability zone, hydrates dissociate and move from the solid to the gas phase. Hydrate dissociation is accompanied by significant changes in sediment structure and strongly affects its mechanical behavior (e.g., sediment stiffenss, strength and dilatancy). The mechanical behavior of HBS is very complex and its modeling poses great challenges. This paper presents a new geomechanical model for hydrate bearing sediments. The model incorporates the concept of partition stress, plus a number of inelastic mechanisms proposed to capture the complex behavior of this type of soil. This constitutive model is especially well suited to simulate the behavior of HBS upon dissociation. The model was applied and validated against experimental data from triaxial and oedometric tests conducted on manufactured and natural specimens involving different hydrate saturation, hydrate morphology, and confinement conditions. Particular attention was paid to model the HBS behavior during hydrate dissociation under loading. The model performance was highly satisfactory in all the cases studied. It managed to properly capture the main features of HBS mechanical behavior and it also assisted to interpret the behavior of this type of sediment under different loading and hydrate conditions.

  13. Models for Gas Hydrate-Bearing Sediments Inferred from Hydraulic Permeability and Elastic Velocities

    Science.gov (United States)

    Lee, Myung W.

    2008-01-01

    Elastic velocities and hydraulic permeability of gas hydrate-bearing sediments strongly depend on how gas hydrate accumulates in pore spaces and various gas hydrate accumulation models are proposed to predict physical property changes due to gas hydrate concentrations. Elastic velocities and permeability predicted from a cementation model differ noticeably from those from a pore-filling model. A nuclear magnetic resonance (NMR) log provides in-situ water-filled porosity and hydraulic permeability of gas hydrate-bearing sediments. To test the two competing models, the NMR log along with conventional logs such as velocity and resistivity logs acquired at the Mallik 5L-38 well, Mackenzie Delta, Canada, were analyzed. When the clay content is less than about 12 percent, the NMR porosity is 'accurate' and the gas hydrate concentrations from the NMR log are comparable to those estimated from an electrical resistivity log. The variation of elastic velocities and relative permeability with respect to the gas hydrate concentration indicates that the dominant effect of gas hydrate in the pore space is the pore-filling characteristic.

  14. Submarine Slope Failure Primed and Triggered by Bottom Water Warming in Oceanic Hydrate-Bearing Deposits

    Directory of Open Access Journals (Sweden)

    Tae-Hyuk Kwon

    2012-08-01

    Full Text Available Many submarine slope failures in hydrate-bearing sedimentary deposits might be directly triggered, or at least primed, by gas hydrate dissociation. It has been reported that during the past 55 years (1955–2010 the 0–2000 m layer of oceans worldwide has been warmed by 0.09 °C because of global warming. This raises the following scientific concern: if warming of the bottom water of deep oceans continues, it would dissociate natural gas hydrates and could eventually trigger massive slope failures. The present study explored the submarine slope instability of oceanic gas hydrate-bearing deposits subjected to bottom water warming. One-dimensional coupled thermal-hydraulic-mechanical (T-H-M finite difference analyses were performed to capture the underlying physical processes initiated by bottom water warming, which includes thermal conduction through sediments, thermal dissociation of gas hydrates, excess pore pressure generation, pressure diffusion, and hydrate dissociation against depressurization. The temperature rise at the seafloor due to bottom water warming is found to create an excess pore pressure that is sufficiently large to reduce the stability of a slope in some cases. Parametric study results suggest that a slope becomes more susceptible to failure with increases in thermal diffusivity and hydrate saturation and decreases in pressure diffusivity, gas saturation, and water depth. Bottom water warming can be further explored to gain a better understanding of the past methane hydrate destabilization events on Earth, assuming that more reliable geological data is available.

  15. Active downhole thermal property measurement system for characterization of gas hydrate-bearing formations

    Energy Technology Data Exchange (ETDEWEB)

    Fukuhara, Masafumi; Fujii, Kasumi; Tertychnyi, Vladimir; Shandrygin, Alexander; Popov, Yuri; Matsubayashi, Osamu; Kusaka, Koji; Yasuda, Masato

    2005-07-01

    Gas hydrates dissociate or form when temperature and/or pressure conditions cross the equilibrium border. When we consider gas hydrates as an energy resource, understanding those parameters is very important for developing efficient production schemes. Therefore, thermal measurement is one of the key components of the characterization of the gas hydrate-bearing formation, not only statically but also dynamically. To estimate thermal properties such as thermal conductivity and diffusivity of subsurface formations, the conventional method has been to monitor temperature passively at several underground locations and interpret collected information with assumptions such as steady heat flow or relaxation from thermal disturbance by fluid flow, etc. Because the thermal properties are estimated based on several assumptions, these passive measurement methods sometimes leave a lot of uncertainties. On the other hand, active thermal property measurement, which could minimize those uncertainties, is commonly used in a laboratory and many types of equipment exist commercially for the purpose. The concept of measurement is very simple: creating a known thermal disturbance with a thermal source and then monitoring the response of the specimen. However, simply applying this method to subsurface formation measurement has many technical and logistical difficulties. In this paper, newly developed thermal property measurement equipment and its measurement methodology are described. Also discussed are the theoretical background for the application of the methodology to a gas hydrate-bearing formation through numerical simulation and the experimental results of laboratory mockup in a controlled environment. (Author)

  16. Investigation of gas hydrate-bearing sandstone reservoirs at the "Mount Elbert" stratigraphic test well, Milne Point, Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Boswell, R.M.; Hunter, R. (ASRC Energy Services, Anchorage, AK); Collett, T. (USGS, Denver, CO); Digert, S. (BP Exploration (Alaska) Inc., Anchorage, AK); Hancock, S. (RPS Energy Canada, Calgary, Alberta, Canada); Weeks, M. (BP Exploration (Alaska) Inc., Anchorage, AK); Mt. Elbert Science Team

    2008-01-01

    In February 2007, the U.S. Department of Energy, BP Exploration (Alaska), Inc., and the U.S. Geological Survey conducted an extensive data collection effort at the "Mount Elbert #1" gas hydrates stratigraphic test well on the Alaska North Slope (ANS). The 22-day field program acquired significant gas hydrate-bearing reservoir data, including a full suite of open-hole well logs, over 500 feet of continuous core, and open-hole formation pressure response tests. Hole conditions, and therefore log data quality, were excellent due largely to the use of chilled oil-based drilling fluids. The logging program confirmed the existence of approximately 30 m of gashydrate saturated, fine-grained sand reservoir. Gas hydrate saturations were observed to range from 60% to 75% largely as a function of reservoir quality. Continuous wire-line coring operations (the first conducted on the ANS) achieved 85% recovery through 153 meters of section, providing more than 250 subsamples for analysis. The "Mount Elbert" data collection program culminated with open-hole tests of reservoir flow and pressure responses, as well as gas and water sample collection, using Schlumberger's Modular Formation Dynamics Tester (MDT) wireline tool. Four such tests, ranging from six to twelve hours duration, were conducted. This field program demonstrated the ability to safely and efficiently conduct a research-level openhole data acquisition program in shallow, sub-permafrost sediments. The program also demonstrated the soundness of the program's pre-drill gas hydrate characterization methods and increased confidence in gas hydrate resource assessment methodologies for the ANS.

  17. Investigation of gas hydrate-bearing sandstone reservoirs at the Mount Elbert stratigraphic test well, Milne Point, Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Boswell, R. [United States Dept. of Energy, Morgantown, WV (United States). National Energy Technology Lab; Hunter, R. [ASRC Energy Services, Anchorage, AK (United States); Collett, T. [United States Geological Survey, Denver, CO (United States); Digert, S.; Weeks, M. [BP Exploration Alaska Inc., Anchorage, AK (United States); Hancock, S. [RPS Energy Canada, Calgary, AB (Canada)

    2008-07-01

    Gas hydrates occur within the shallow sand reservoirs on the Alaska North Slope (ANS). The mean estimate for gas hydrate in-place resources on the ANS is 16.7 trillion cubic metres. In the past, they were viewed primarily as a drilling hazard to be managed during the development of deeper oil resources. In 2002, a cooperative research program was launched to help determine the potential for environmentally-sound and economically-viable production of methane from gas hydrates. Additional objectives were to refine ANS gas hydrate resource potential, improve the geologic and geophysical methods used to locate and asses gas hydrate resources, and develop numerical modeling capabilities that are essential in both planning and evaluating gas hydrate field programs. This paper reviewed the results of the an extensive data collection effort conducted at the Mount Elbert number 1 gas hydrates stratigraphic test well on the ANS. The 22-day field program acquired significant gas hydrate-bearing reservoir data, including a suite of open-hole well logs, over 500 feet of continuous core, and open-hole formation pressure response tests. The logging program confirmed the existence of approximately 30 m of gas hydrate saturated, fine-grained sand reservoir. Gas hydrate saturations were observed to range from 60 to 75 per cent. Continuous wire-line coring operations achieved 85 per cent recovery. The Mount Elbert field program also involved gas and water sample collection. It demonstrated the ability to safely and efficiently conduct a research-level open-hole data acquisition program in shallow, sub-permafrost sediments and increased confidence in gas hydrate resource assessment methodologies for the ANS. 10 refs., 9 figs.

  18. New Approaches for the Production of Hydrocarbons from Hydrate Bearing Sediments

    Directory of Open Access Journals (Sweden)

    Ronny Giese

    2011-01-01

    Full Text Available The presence of natural gas hydrates at all active and passive continental margins has been proven. Their global occurrence as well as the fact that huge amounts of methane and other lighter hydrocarbons are stored in natural gas hydrates has led to the idea of using hydrate bearing sediments as an energy resource. However, natural gas hydrates remain stable as long as they are in mechanical, thermal and chemical equilibrium with their environment. Thus, for the production of gas from hydrate bearing sediments, at least one of these equilibrium states must be disturbed by depressurization, heating or addition of chemicals such as CO2. Depressurization, thermal or chemical stimulation may be used alone or in combination, but the idea of producing hydrocarbons from hydrate bearing sediments by CO2 injection suggests the potential of an almost emission free use of this unconventional natural gas resource. However, up to now there are still open questions regarding all three production principles. Within the framework of the German national research project SUGAR the thermal stimulation method by use of in situ combustion was developed and tested on a pilot plant scale and the CH4-CO2 swapping process in gas hydrates studied on a molecular level. Microscopy, confocal Raman spectroscopy and X-ray diffraction were used for in situ investigations of the CO2-hydrocarbon exchange process in gas hydrates and its driving forces. For the thermal stimulation a heat exchange reactor was designed and tested for the exothermal catalytic oxidation of methane. Furthermore, a large scale reservoir simulator was realized to synthesize hydrates in sediments under conditions similar to nature and to test the efficiency of the reactor. Thermocouples placed in the reservoir simulator with a total volume of 425 L collect data regarding the propagation of the heat front. In addition, CH4 sensors are placed in the water saturated sediment to detect the distribution of CH4

  19. Composite model to reproduce the mechanical behaviour of methane hydrate bearing soils

    Science.gov (United States)

    De la Fuente, Maria

    2016-04-01

    Methane hydrate bearing sediments (MHBS) are naturally-occurring materials containing different components in the pores that may suffer phase changes under relative small temperature and pressure variations for conditions typically prevailing a few hundreds of meters below sea level. Their modelling needs to account for heat and mass balance equations of the different components, and several strategies already exist to combine them (e.g., Rutqvist & Moridis, 2009; Sánchez et al. 2014). These equations have to be completed by restrictions and constitutive laws reproducing the phenomenology of heat and fluid flows, phase change conditions and mechanical response. While the formulation of the non-mechanical laws generally includes explicitly the mass fraction of methane in each phase, which allows for a natural update of parameters during phase changes, mechanical laws are, in most cases, stated for the whole solid skeleton (Uchida et al., 2012; Soga et al. 2006). In this paper, a mechanical model is proposed to cope with the response of MHBS. It is based on a composite approach that allows defining the thermo-hydro-mechanical response of mineral skeleton and solid hydrates independently. The global stress-strain-temperature response of the solid phase (grains + hydrate) is then obtained by combining both responses according to energy principle following the work by Pinyol et al. (2007). In this way, dissociation of MH can be assessed on the basis of the stress state and temperature prevailing locally within the hydrate component. Besides, its structuring effect is naturally accounted for by the model according to patterns of MH inclusions within soil pores. This paper describes the fundamental hypothesis behind the model and its formulation. Its performance is assessed by comparison with laboratory data presented in the literature. An analysis of MHBS response to several stress-temperature paths representing potential field cases is finally presented. References

  20. Experimental characterization of production behavior accompanying the hydrate reformation in methane hydrate bearing sediments

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, T.; Kang, J.M.; Nguyen, H.T. [Seoul National Univ., Seoul (Korea, Republic of); Park, C. [Kangwon National Univ., (Korea, Republic of); Lee, J. [Korea Inst., of Geoscience and Mineral Resources (Korea, Republic of)

    2010-07-01

    This study investigated the production behaviour associated with gas hydrate reformation in methane hydrate-bearing sediment by hot-brine injection. A range of different temperature and brine injection rates were used to analyze the pressure and temperature distribution, the gas production behaviour and the movement of the dissociation front. The study showed that hydrate reformation reduces the production rate considerably at an early time. However, gas production increases during the dissociation, near the outlet because the dissociated methane around the inlet is consumed in reforming the hydrate and increases the hydrate saturation around the outlet. Higher temperature also increases the gas production rate and the speed of the dissociation front. 12 refs., 2 tabs., 4 figs.

  1. Studies of Reaction Kinetics of Methane Hydrate Dissocation in Porous Media

    Energy Technology Data Exchange (ETDEWEB)

    Moridis, George J.; Seol, Yongkoo; Kneafsey, Timothy J.

    2005-03-10

    The objective of this study is the description of the kinetic dissociation of CH4-hydrates in porous media, and the determination of the corresponding kinetic parameters. Knowledge of the kinetic dissociation behavior of hydrates can play a critical role in the evaluation of gas production potential of gas hydrate accumulations in geologic media. We analyzed data from a sequence of tests of CH4-hydrate dissociation by means of thermal stimulation. These tests had been conducted on sand cores partially saturated with water, hydrate and CH4 gas, and contained in an x-ray-transparent aluminum pressure vessel. The pressure, volume of released gas, and temperature (at several locations within the cores) were measured. To avoid misinterpreting local changes as global processes, x-ray computed tomography scans provided accurate images of the location and movement of the reaction interface during the course of the experiments. Analysis of the data by means of inverse modeling (history matching ) provided estimates of the thermal properties and of the kinetic parameters of the hydration reaction in porous media. Comparison of the results from the hydrate-bearing porous media cores to those from pure CH4-hydrate samples provided a measure of the effect of the porous medium on the kinetic reaction. A tentative model of composite thermal conductivity of hydrate-bearing media was also developed.

  2. Joint Electrical and Seismic Interpretation of Gas Hydrate Bearing Sediments From the Cascadia Margin

    Science.gov (United States)

    Ellis, M.; Minshull, T.; Sinha, M.; Best, A.

    2008-12-01

    Gas hydrates are found in continental margin sediments worldwide. Their global importance as future energy reserves and their potential impact on slope stability and abrupt climate change all require better knowledge of where they occur and how much hydrate is present. However, current estimates of the distribution and volume of gas hydrate beneath the seabed range widely. Improved geophysical methods could provide much better constraints on hydrate concentrations. Geophysical measurements of seismic velocity and electrical resistivity using seabed or borehole techniques are often used to determine the hydrate saturation of sediments. Gas hydrates are well known to affect these physical properties; hydrate increases sediment p-wave velocity and electrical resistivity by replacing the conductive pore fluids, by cementing grains together and by blocking pores. A range of effective medium theoretical models have been developed to interpret these measurements in terms of hydrate content, but uncertainties about the pore-scale distribution of hydrate can lead to large uncertainties in the results. This study developed effective medium models to determine the seismic and electrical properties of hydrate bearing sediments in terms of their porosity, micro-structure and hydrate saturation. The seismic approach combines a Self Consistent Approximation (SCA) and Differential Effective Medium (DEM), which can model a bi-connected effective medium and allows the shape and alignment of the grains to be taken into account. The electrical effective medium method was developed to complement the seismic models and is based on the application of a geometric correction to the Hashin-Shrikman conductive bound. The electrical and seismic models are non-unique and hence it was necessary to develop a joint electrical and seismic interpretation method to investigate hydrate bearing sediments. The joint method allows two variables (taken from porosity, aspect ratio or hydrate saturation

  3. Methane flux in potential hydrate-bearing sediments offshore southwestern Taiwan

    Science.gov (United States)

    Chen, Nai-Chen; Yang, Tsanyao Frank; Chuang, Pei-Chuan; Hong, Wei-Li; Chen, Hsuan-Wen; Lin, Saulwood; Lin, Li-Hung; Mastumoto, Ryo; Hiruta, Akihiro; Sun, Chih-Hsien; Wang, Pei-Ling; Yang, Tau; Jiang, Shao-yong; Wang, Yun-shuen; Chung, San-Hsiung; Chen, Cheng-Hong

    2016-04-01

    Methane in interstitial water of hydrate-bearing marine sediments ascends with buoyant fluids and is discharged into seawater, exerting profound impacts on ocean biogeochemistry and greenhouse effects. Quantifying the exact magnitude of methane transport across different geochemical transitions in different geological settings would provide bases to better constrain global methane discharge to seawater and to assess physio-chemical contexts imposed on microbial methane production and consumption and carbon sequestration in marine environments. Using sediments collected from different geological settings offshore southwestern Taiwan through decadal exploration on gas hydrates, this study analyzed gas and aqueous geochemistry and calculated methane fluxes across different compartments. Three geochemical transitions, including sulfate-methane transition zone (SMTZ), shallow sediments, and sediment-seawater interface were specifically focused for the flux calculation. The results combined with previous published data showed that methane fluxes at three interfaces of 2.71×10-3 to 3.52×10-1, 5.28×10-7 to 1.08×100, and 1.34×10-6 to 3.17×100 mmol m-2 d-1, respectively. The ranges of fluxes suggest that more than 90 % of methane originating from depth was consumed by anaerobic methanotrophy at the SMTZ, and further >90% of the remnant methane was removed by aerobic methanotrophy prior to reaching the sediment-seawater interface. Exceptions are sites at cold seeps where the percentage of methane released into seawater can reach more than 80% of methane at depth. Most sites with such high methane fluxes are located at active margin where thrusts and diapirism are well developed. Carbon mass balance method was applied for the calculation of anaerobic oxidation of methane (AOM) and organotrophic sulfate reduction rates at SMTZ. Results indicated that AOM rates were comparable with fluxes deduced from concentration gradients for most sites. At least 60% of sulfate

  4. Role of critical state framework in understanding geomechanical behavior of methane hydrate-bearing sediments

    Science.gov (United States)

    Uchida, Shun; Xie, Xiao-Guang; Leung, Yat Fai

    2016-08-01

    A proper understanding of geomechanical behavior of methane hydrate-bearing sediments is crucial for sustainable future gas production. There are a number of triaxial experiments conducted over synthetic and natural methane hydrate (MH)-bearing sediments, and several soil constitutive models have been proposed to describe their behavior. However, the generality of a sophisticated model is questioned if it is tested only for a limited number of cases. Furthermore, it is difficult to experimentally determine the associated parameters if their physical meanings and significance are not elucidated. The objective of this paper is to demonstrate that a simple extension of the critical state framework is sufficient to capture the geomechanical behavior of MH-bearing soils from various sources around the world, while the significance of each parameter is quantified through variance-based global sensitivity analyses. Our results show that the influence of hydrates can be largely represented by one hydrate-dependent parameter, pcd', which controls the expansion of the initial yield surface. This is validated through comparisons with shearing and volumetric response of MH-bearing soils tested at various institutes under different confining stresses and with varying degrees of hydrate saturation. Our study suggests that the behavior of MH-bearing soils can be reasonably predicted based on pcd' and the conventional critical state parameters of the host sediments that can be obtained through typical geotechnical testing procedures.

  5. Relative water and gas permeability for gas production from hydrate-bearing sediments

    Science.gov (United States)

    Mahabadi, Nariman; Jang, Jaewon

    2014-06-01

    water and gas permeability equations are important for estimating gas and water production from hydrate-bearing sediments. However, experimental or numerical study to determine fitting parameters of those equations is not available in the literature. In this study, a pore-network model is developed to simulate gas expansion and calculate relative water and gas permeability. Based on the simulation results, fitting parameters for modified Stone equation are suggested for a distributed hydrate system where initial hydrate saturations range from Sh = 0.1 to 0.6. The suggested fitting parameter for relative water permeability is nw ≈ 2.4 regardless of initial hydrate saturation while the suggested fitting parameter for relative gas permeability is increased from ng = 1.8 for Sh = 0.1 to ng = 3.5 for Sh = 0.6. Results are relevant to other systems that experience gas exsolution such as pockmark formation due to sea level change, CO2 gas formation during geological CO2 sequestration, and gas bubble accumulation near the downstream of dams.

  6. Modeling on the gas-generating amount of sediments hydrate-bearing

    Energy Technology Data Exchange (ETDEWEB)

    Gong, J.M.; Cao, Z.M. [Ocean Univ. of China, Qingdao (China); Jian-Ming, G.; Chen, J.W. [Qingdao Inst. of Marine Geology, Qingdao (China); Zhang, M.; Yang, G.F. [Yangtze Univ., Jingzhou (China); Li, J. [PetroChina, HeBei (China). Langfang Branch, Research Inst. of Petroleum Exploration and Development

    2008-07-01

    Gas hydrate is a form of clean fossil energy. It has the characteristics of extensive distribution, large reserve, high-energy capacity and less pollution after combustion. It also has a great energy value, generating interest from governments and scientists in different countries. This paper discussed a study in which methane generating hydrate-bearing sediments were investigated. A total of 58 sediment samples from 4 sites of ODP Leg 204 were modeled by 5 temperature points. ODP Leg 204 lies offshore western United States, in the Hydrate Ridge region (Oregon) of the Pacific. It is one of the most studied areas and clearest about hydrate distribution in the world. The paper described the study area and sample preparation. It also discussed the modeling and geochemical characteristics of the gas-generating samples. A model section revealed bacteria species, substrate deployment, selection of culture flask, and sample culture. The geochemical characteristics of the gas-generating samples were also described. It was concluded that the sediments within 1,200 meters below the seafloor were the main gas source of the biogenic gas hydrate. The organic matter abundance of the sediments at this depth and the migration passage of the fluids in the strata were important for the formation and preservation of the gas hydrate deposits. 21 refs., 1 tab., 6 figs.

  7. Evaluation of Different CH4-CO2 Replacement Processes in Hydrate-Bearing Sediments by Measuring P-Wave Velocity

    Directory of Open Access Journals (Sweden)

    Bei Liu

    2013-11-01

    Full Text Available The replacement of methane with carbon dioxide in natural gas hydrate-bearing sediments is considered a promising technology for simultaneously recovering natural gas and entrapping CO2. During the CH4-CO2 replacement process, the variations of geophysical property of the hydrate reservoir need to be adequately known. Since the acoustic wave velocity is an important geophysical property, in this work, the variations of P-wave velocity of hydrate-bearing sediments were measured during different CH4-CO2 replacement processes using pure gaseous CO2 and CO2/N2 gas mixtures. Our experimental results show that P-wave velocity continually decreased during all replacement processes. Compared with injecting pure gaseous CO2, injection of CO2/N2 mixture can promote the replacement process, however, it is found that the sediment experiences a loss of stiffness during the replacement process, especially when using CO2/N2 gas mixtures.

  8. Microbial Diversity in Hydrate-bearing and -free Seafloor Surface Sediments in the Shenhu Area, South China Sea

    Science.gov (United States)

    Su, X.

    2015-12-01

    In 2007, the China's first gas hydrate drilling expedition GMGS-1 in the Shenhu area on the northern continental slope of the South China Sea was performed (Zhang et al., 2007). Six holes (namely Sites SH1B, SH2B, SH3B, SH5B, SH5C and SH7B) were drilled, and gas hydrate samples were recovered at three sites: Sites SH2B, SH3B and SH7B. In order to investigate microbial diversity and community features in correlation to gas hydrate-bearing sediments, a study on microbial diversity in the surface sediments at hydrate-bearing sites (SH3B and SH7B) and -free sites (SH1B, SH5B, SH5C) was carried out by using 16S rRNA gene phylogenetic analysis. The phylogenetic results indicated difference in microbial communities between hydrate-bearing and -free sediments. At the gas hydrate-bearing sites, bacterial communities were dominated by Deltaproteobacteria (30.5%), and archaeal communities were dominated by Miscellaneous Crenarchaeotic Group (33.8%); In contrast, Planctomycetes was the major group (43.9%) in bacterial communities, while Marine Benthic Group-D (MBG-D) (32.4%) took up the largest proportion in the archaeal communities. Moreover, the microbial communities have characteristics different from those in other hydrate-related sediments around the world, indicating that the presence of hydrates could affect the microbial distribution and community composition. In addition, the microbial community composition in the studied sediments has its own uniqueness, which may be resulted by co-effect of geochemical characteristics and presence/absence of gas hydrates.

  9. Experimental study of enhanced gas recovery from gas hydrate bearing sediments by inhibitor and steam injection methods

    Energy Technology Data Exchange (ETDEWEB)

    Kawamura, T.; Ohtake, M.; Sakamoto, Y.; Yamamoto, Y.; Haneda, H. [National Inst. of Advanced Industrial Science and Technology, Tsukuba (Japan). Methane Hydrate Research Laboratory; Komai, T. [National Inst. of Advanced Industrial Science and Technoloyg, Tsukuba (Japan). Inst. for Geo-Resource and Environment; Higuchi, S. [Nihon Axis Co. Ltd., Mito (Japan)

    2008-07-01

    Inhibitor and steam injection methods for recovering methane hydrate-bearing sediments were investigated. New apparatus designs were used to inject steam into artificial methane hydrate-bearing sediments. Aqueous methanol was injected into a silica-based hydrate-bearing sediment in order to examine the dissociation behaviour of the methane hydrates. Experiments were conducted to examine the effects of steam injection using pure water; an aqueous methyl alcohol (MeOh) solution at 10 wt per cent; and an aqueous sodium chloride (NaC1) solution at 3 wt per cent. Temperatures for the injected fluids were set at 40 degrees C. Total gas production behaviour was divided into 3 stages: (1) the replacement of the remaining gas with the injected solution in the pore space; (2) gas production by hydrate dissociation; and (3) steady state and gas release. Results showed that cumulative gas production using the inhibitor solutions of MeOH and NaC1 proceeded more rapidly than the pure water samples. Downstream temperatures were not maintained at initial temperatures but decreased following the initiation of hydrate dissociation. Temperature changes were attributed to the coupling effect of the dissociation temperature and changes in inhibitor concentrations at the methane hydrate's surface. The use of inhibitors resulted in higher levels of cumulative gas production and more rapid hydrate dissociation rates. It was concluded that depressurization and steam injection induced hydrate dissociation from both upstream and downstream to the center of the sediment sample. 18 refs., 9 figs.

  10. Permeability of laboratory-formed methane-hydrate-bearing sand: Measurements and observations using x-ray computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Kneafsey, T. J.; Seol, Y.; Gupta, A.; Tomutsa, L.

    2010-09-15

    Methane hydrate was formed in two moist sands and a sand/silt mixture under a confining stress in an X-ray-transparent pressure vessel. Three initial water saturations were used to form three different methane-hydrate saturations in each medium. X-ray computed tomography (CT) was used to observe location-specific density changes caused by hydrate formation and flowing water. Gas-permeability measurements in each test for the dry, moist, frozen, and hydrate-bearing states are presented. As expected, the effective permeabilities (intrinsic permeability of the medium multiplied by the relative permeability) of the moist sands decreased with increasing moisture content. In a series of tests on a single sample, the effective permeability typically decreased as the pore space became more filled, in the order of dry, moist, frozen, and hydrate-bearing. In each test, water was flowed through the hydrate-bearing medium and we observed the location-specific changes in water saturation using CT scanning. We compared our data to a number of models, and our relative permeability data compare most favorably with models in which hydrate occupies the pore bodies rather than the pore throats. Inverse modeling (using the data collected from the tests) will be performed to extend the relative permeability measurements.

  11. Fluid-solid coupling model for studying wellbore instability in drilling of gas hydrate bearing sediments

    Institute of Scientific and Technical Information of China (English)

    程远方; 李令东; 崔青

    2013-01-01

    As the oil or gas exploration and development activities in deep and ultra-deep waters become more and more, encountering gas hydrate bearing sediments (HBS) is almost inevitable. The variation in temperature and pressure can destabilize gas hydrate in nearby formation around the borehole, which may reduce the strength of the formation and result in wellbore instability. A non-isothermal, transient, two-phase, and fluid-solid coupling mathematical model is proposed to simulate the complex stability performance of a wellbore drilled in HBS. In the model, the phase transition of hydrate dissociation, the heat exchange between drilling fluid and formation, the change of mechanical and petrophysical properties, the gas-water two-phase seepage, and its interaction with rock deformation are considered. A finite element simulator is developed, and the impact of drilling mud on wellbore instability in HBS is simulated. Results indicate that the re-duction in pressure and the increase in temperature of the drilling fluid can accelerate hydrate decomposition and lead to mechanical properties getting worse tremendously. The cohesion decreases by 25% when the hydrate totally dissociates in HBS. This easily causes the wellbore instability accordingly. In the first two hours after the formation is drilled, the regions of hydrate dissociation and wellbore instability extend quickly. Then, with the soaking time of drilling fluid increasing, the regions enlarge little. Choosing the low temperature drilling fluid and increasing the drilling mud pressure appropriately can benefit the wellbore stability of HBS. The established model turns out to be an efficient tool in numerical studies of the hydrate dissociation behavior and wellbore stability of HBS.

  12. The Water Retention Curves in THF Hydrate-Bearing Sediments - Experimental Measurement and Pore Scale Simulation

    Science.gov (United States)

    Mahabadi, N.; Zheng, X.; Dai, S.; Seol, Y.; Zapata, C.; Yun, T.; Jang, J.

    2015-12-01

    The water retention curve (WRC) of hydrate-bearing sediments is critically important to understand the behaviour of hydrate dissociation for gas production. Most gas hydrates in marine environment have been formed from an aqueous phase (gas-dissolved water). However, the gas hydrate formation from an aqueous phase in a laboratory requires long period due to low gas solubility in water and is also associated with many experimental difficulties such as hydrate dissolution, difficult hydrate saturation control, and dynamic hydrate dissolution and formation. In this study, tetrahydrofuran (THF) is chosen to form THF hydrate because the formation process is faster than gas hydrate formation and hydrate saturation is easy to control. THF hydrate is formed at water-excess condition. Therefore, there is only water in the pore space after a target THF hydrate saturation is obtained. The pore habit of THF hydrate is investigated by visual observation in a transparent micromodel and X-ray computed tomography images; and the water retention curves are obtained under different THF hydrate saturation conditions. Targeted THF hydrate saturations are Sh=0, 0.2, 0.4, 0.6 and 0.8. Results shown that at a given water saturation the capillary pressure increases as THF hydrate saturation increases. And the gas entry pressure increases with increasing hydrate saturation. The WRC obtained by experiments is also compared with the results of a pore-network model simulation and Lattice Boltzmann Method. The fitting parameters of van Genuchten equation for different hydrate saturation conditions are suggested for the use as input parameters of reservoir simulators.

  13. Core Physics and Kinetics Calculations for the Fissioning Plasma Core Reactor

    Science.gov (United States)

    Butler, C.; Albright, D.

    2007-01-01

    Highly efficient, compact nuclear reactors would provide high specific impulse spacecraft propulsion. This analysis and numerical simulation effort has focused on the technical feasibility issues related to the nuclear design characteristics of a novel reactor design. The Fissioning Plasma Core Reactor (FPCR) is a shockwave-driven gaseous-core nuclear reactor, which uses Magneto Hydrodynamic effects to generate electric power to be used for propulsion. The nuclear design of the system depends on two major calculations: core physics calculations and kinetics calculations. Presently, core physics calculations have concentrated on the use of the MCNP4C code. However, initial results from other codes such as COMBINE/VENTURE and SCALE4a. are also shown. Several significant modifications were made to the ISR-developed QCALC1 kinetics analysis code. These modifications include testing the state of the core materials, an improvement to the calculation of the material properties of the core, the addition of an adiabatic core temperature model and improvement of the first order reactivity correction model. The accuracy of these modifications has been verified, and the accuracy of the point-core kinetics model used by the QCALC1 code has also been validated. Previously calculated kinetics results for the FPCR were described in the ISR report, "QCALC1: A code for FPCR Kinetics Model Feasibility Analysis" dated June 1, 2002.

  14. Comparison of the physical and geotechnical properties of gas-hydrate-bearing sediments from offshore India and other gas-hydrate-reservoir systems

    Science.gov (United States)

    Winters, William J.; Wilcox-Cline, R.W.; Long, P.; Dewri, S.K.; Kumar, P.; Stern, Laura A.; Kerr, Laura A.

    2014-01-01

    The sediment characteristics of hydrate-bearing reservoirs profoundly affect the formation, distribution, and morphology of gas hydrate. The presence and type of gas, porewater chemistry, fluid migration, and subbottom temperature may govern the hydrate formation process, but it is the host sediment that commonly dictates final hydrate habit, and whether hydrate may be economically developed.In this paper, the physical properties of hydrate-bearing regions offshore eastern India (Krishna-Godavari and Mahanadi Basins) and the Andaman Islands, determined from Expedition NGHP-01 cores, are compared to each other, well logs, and published results of other hydrate reservoirs. Properties from the hydrate-free Kerala-Konkan basin off the west coast of India are also presented. Coarser-grained reservoirs (permafrost-related and marine) may contain high gas-hydrate-pore saturations, while finer-grained reservoirs may contain low-saturation disseminated or more complex gas-hydrates, including nodules, layers, and high-angle planar and rotational veins. However, even in these fine-grained sediments, gas hydrate preferentially forms in coarser sediment or fractures, when present. The presence of hydrate in conjunction with other geologic processes may be responsible for sediment porosity being nearly uniform for almost 500 m off the Andaman Islands.Properties of individual NGHP-01 wells and regional trends are discussed in detail. However, comparison of marine and permafrost-related Arctic reservoirs provides insight into the inter-relationships and common traits between physical properties and the morphology of gas-hydrate reservoirs regardless of location. Extrapolation of properties from one location to another also enhances our understanding of gas-hydrate reservoir systems. Grain size and porosity effects on permeability are critical, both locally to trap gas and regionally to provide fluid flow to hydrate reservoirs. Index properties corroborate more advanced

  15. X-ray computed-tomography observations of water flow through anisotropic methane hydrate-bearing sand

    Energy Technology Data Exchange (ETDEWEB)

    Seol, Yongkoo; Kneafsey, Timothy J.

    2009-06-01

    We used X-ray computed tomography (CT) to image and quantify the effect of a heterogeneous sand grain-size distribution on the formation and dissociation of methane hydrate, as well as the effect on water flow through the heterogeneous hydrate-bearing sand. A 28 cm long sand column was packed with several segments having vertical and horizontal layers with sands of different grain-size distributions. During the hydrate formation, water redistribution occurred. Observations of water flow through the hydrate-bearing sands showed that water was imbibed more readily into the fine sand, and that higher hydrate saturation increased water imbibition in the coarse sand due to increased capillary strength. Hydrate dissociation induced by depressurization resulted in different flow patterns with the different grain sizes and hydrate saturations, but the relationships between dissociation rates and the grain sizes could not be identified using the CT images. The formation, presence, and dissociation of hydrate in the pore space dramatically impact water saturation and flow in the system.

  16. The water retention curve and relative permeability for gas production from hydrate-bearing sediments: pore-network model simulation

    Science.gov (United States)

    Mahabadi, Nariman; Dai, Sheng; Seol, Yongkoo; Sup Yun, Tae; Jang, Jaewon

    2016-08-01

    The water retention curve and relative permeability are critical to predict gas and water production from hydrate-bearing sediments. However, values for key parameters that characterize gas and water flows during hydrate dissociation have not been identified due to experimental challenges. This study utilizes the combined techniques of micro-focus X-ray computed tomography (CT) and pore-network model simulation to identify proper values for those key parameters, such as gas entry pressure, residual water saturation, and curve fitting values. Hydrates with various saturation and morphology are realized in the pore-network that was extracted from micron-resolution CT images of sediments recovered from the hydrate deposit at the Mallik site, and then the processes of gas invasion, hydrate dissociation, gas expansion, and gas and water permeability are simulated. Results show that greater hydrate saturation in sediments lead to higher gas entry pressure, higher residual water saturation, and steeper water retention curve. An increase in hydrate saturation decreases gas permeability but has marginal effects on water permeability in sediments with uniformly distributed hydrate. Hydrate morphology has more significant impacts than hydrate saturation on relative permeability. Sediments with heterogeneously distributed hydrate tend to result in lower residual water saturation and higher gas and water permeability. In this sense, the Brooks-Corey model that uses two fitting parameters individually for gas and water permeability properly capture the effect of hydrate saturation and morphology on gas and water flows in hydrate-bearing sediments.

  17. TOUGH+Hydrate v1.0 User's Manual: A Code for the Simulation of System Behavior in Hydrate-Bearing Geologic Media

    Energy Technology Data Exchange (ETDEWEB)

    Moridis, George; Moridis, George J.; Kowalsky, Michael B.; Pruess, Karsten

    2008-03-01

    TOUGH+HYDRATE v1.0 is a new code for the simulation of the behavior of hydrate-bearing geologic systems. By solving the coupled equations of mass and heat balance, TOUGH+HYDRATE can model the non-isothermal gas release, phase behavior and flow of fluids and heat under conditions typical of common natural CH{sub 4}-hydrate deposits (i.e., in the permafrost and in deep ocean sediments) in complex geological media at any scale (from laboratory to reservoir) at which Darcy's law is valid. TOUGH+HYDRATE v1.0 includes both an equilibrium and a kinetic model of hydrate formation and dissociation. The model accounts for heat and up to four mass components, i.e., water, CH{sub 4}, hydrate, and water-soluble inhibitors such as salts or alcohols. These are partitioned among four possible phases (gas phase, liquid phase, ice phase and hydrate phase). Hydrate dissociation or formation, phase changes and the corresponding thermal effects are fully described, as are the effects of inhibitors. The model can describe all possible hydrate dissociation mechanisms, i.e., depressurization, thermal stimulation, salting-out effects and inhibitor-induced effects. TOUGH+HYDRATE is the first member of TOUGH+, the successor to the TOUGH2 [Pruess et al., 1991] family of codes for multi-component, multiphase fluid and heat flow developed at the Lawrence Berkeley National Laboratory. It is written in standard FORTRAN 95, and can be run on any computational platform (workstation, PC, Macintosh) for which such compilers are available.

  18. Testing a coupled hydro-thermo-chemo-geomechanical model for gas hydrate bearing sediments using triaxial compression lab experiments

    CERN Document Server

    Gupta, Shubhangi; Haeckel, Matthias; Helmig, Rainer; Wohlmuth, Barbara

    2015-01-01

    The presence of gas hydrates influences the stress-strain behavior and increases the load-bearing capacity of sub-marine sediments. This stability is reduced or completely lost when gas hydrates become unstable. Since natural gas hydrate reservoirs are considered as potential resources for gas production on industrial scales, there is a strong need for numerical production simulators with geomechanical capabilities. To reliably predict the mechanical behavior of gas hydrate-bearing sediments during gas production, numerical tools must be sufficiently calibrated against data from controlled experiments or field tests, and the models must consider thermo-hydro-chemo-mechanical process coupling in a suitable manner. In this study, we perform a controlled triaxial volumetric strain test on a sediment sample in which methane hydrate is first formed under controlled isotropic effective stress and then dissociated via depressurization under controlled total stress. Sample deformations were kept small, and under thes...

  19. A Counter-Current Heat-Exchange Reactor for the Thermal Stimulation of Hydrate-Bearing Sediments

    Directory of Open Access Journals (Sweden)

    Manja Luzi-Helbing

    2013-06-01

    Full Text Available Since huge amounts of CH4 are bound in natural gas hydrates occurring at active and passive continental margins and in permafrost regions, the production of natural gas from hydrate-bearing sediments has become of more and more interest. Three different methods to destabilize hydrates and release the CH4 gas are discussed in principle: thermal stimulation, depressurization and chemical stimulation. This study focusses on the thermal stimulation using a counter-current heat-exchange reactor for the in situ combustion of CH4. The principle of in situ combustion as a method for thermal stimulation of hydrate bearing sediments has been introduced and discussed earlier [1,2]. In this study we present the first results of several tests performed in a pilot plant scale using a counter-current heat-exchange reactor. The heat of the flameless, catalytic oxidation of CH4 was used for the decomposition of hydrates in sand within a LArge Reservoir Simulator (LARS. Different catalysts were tested, varying from diverse elements of the platinum group to a universal metal catalyst. The results show differences regarding the conversion rate of CH4 to CO2. The promising results of the latest reactor test, for which LARS was filled with sand and ca. 80% of the pore space was saturated with CH4 hydrate, are also presented in this study. The data analysis showed that about 15% of the CH4 gas released from hydrates would have to be used for the successful dissociation of all hydrates in the sediment using thermal stimulation via in situ combustion.

  20. The impact of hydrate saturation on the mechanical, electrical, and thermal properties of hydrate-bearing sand, silts, and clay

    Energy Technology Data Exchange (ETDEWEB)

    Santamarina, J.C. [Georgia Inst. of Technology, Atlanta, GA (United States). School of Civil and Environmental Engineering; Ruppel, C. [United States Geological Survey, Woods Hole, MA (United States)

    2008-07-01

    A study was conducted to provide an internally-consistent, systematically-acquired database that could help in evaluating gas hydrate reservoirs. Other objectives were to assist in geomechanical analyses, hazards evaluation and the development of methane hydrate production techniques in sandy lithologies and fine-grained sediments that exist in the northern Gulf of Mexico. An understanding of the physical properties of hydrate-bearing sediments facilitates the interpretation of geophysical field data, borehole and slope stability analyses, and reservoir simulation and production models. This paper reported on the key findings derived from 5 years of laboratory experiments conducted on synthetic samples of sand, silts, or clays subjected to various confining pressures. The samples contained controlled saturations of tetrahydrofuran hydrate formed from the dissolved phase. This internally-consistent data set was used to conduct a comprehensive analysis of the trends in geophysical and geotechnical properties as a function of hydrate saturation, soil characteristics, and other parameters. The experiments emphasized measurements of seismic velocities, electrical conductivity and permittivity, large strain deformation and strength, and thermal conductivity. The impact of hydrate formation technique on the resulting physical properties measurements were discussed. The data set was used to identify systematic effects of sediment characteristics, hydrate concentration, and state of stress. The study showed that the electrical properties of hydrate-bearing sediments are less sensitive to the method used to form hydrate in the laboratory than to hydrate saturation. It was concluded that mechanical properties are strongly influenced by both soil properties and the hydrate loci. Since the thermal conductivity depends on the interaction of several factors, it cannot be readily predicted by volume average formulations. 23 refs., 2 tabs., 9 figs.

  1. The assessment of different production methods for hydrate bearing sediments - results from small and large scale experiments

    Science.gov (United States)

    Schicks, Judith; Heeschen, Katja; Spangenberg, Erik; Luzi-Helbing, Manja; Beeskow-Strauch, Bettina; Priegnitz, Mike; Giese, Ronny; Abendroth, Sven; Thaler, Jan

    2017-04-01

    Natural gas hydrates occur at all active and passive continental margins, in permafrost regions, and deep lakes. Since they are supposed to contain enormous amounts of methane, gas hydrates are discussed as an energy resource. For the production of gas from hydrate bearing sediments, three different production methods were tested during the last decade: depressurization, thermal and chemical stimulation as well as combinations of these methods. In the framework of the SUGAR project we developed a Large Scale Reservoir Simulator (LARS) with a total volume of 425L to test these three methods in a pilot plant scale. For this purpose we formed hydrate from methane saturated brine in sediments under conditions close to natural gas hydrate deposits. The obtained hydrate saturations varied between 40-90%. Hydrate saturation and distribution were determined using electrical resistivity tomography (ERT). The volumes of the produced gas and water were determined and the gas phase was analyzed via gas chromatography. Multi-step depressurization, thermal stimulation applying in-situ combustion as well as chemical stimulation via the injection of CO2 and a CO2-N2-mixture were tested. Depressurization and thermal stimulation appear to be less complicated compared to the chemical stimulation. For the understanding of the macroscopically observed processes on a molecular level, we also performed experiments on a smaller scale using microscopic observation, Raman spectroscopy and X-ray diffraction. The results of these experiments are of particular importance for the understanding of the processes occurring during the CO2-CH4 swapping. Under the chosen experimental conditions the observations indicate a (partial) decomposition and reformation of the hydrate structure rather than a diffusion-controlled exchange of the molecules.

  2. Invasion of drilling mud into gas-hydrate-bearing sediments. Part I: effect of drilling mud properties

    Science.gov (United States)

    Ning, Fulong; Zhang, Keni; Wu, Nengyou; Zhang, Ling; Li, Gang; Jiang, Guosheng; Yu, Yibing; Liu, Li; Qin, Yinghong

    2013-06-01

    To our knowledge, this study is the first to perform a numerical simulation and analysis of the dynamic behaviour of drilling mud invasion into oceanic gas-hydrate-bearing sediment (GHBS) and to consider the effects of such an invasion on borehole stability and the reliability of well logging. As a case study, the simulation background sets up the conditions of mud temperature over hydrate equilibrium temperature and overbalanced drilling, considering the first Chinese expedition to drill gas hydrate (GMGS-1). The results show that dissociating gas may form secondary hydrates in the sediment around borehole by the combined effects of increased pore pressure (caused by mud invasion and flow resistance), endothermic cooling that accompanies hydrate dissociation compounded by the Joule-Thompson effect and the lagged effect of heat transfer in sediments. The secondary hydrate ring around the borehole may be more highly saturated than the in situ sediment. Mud invasion in GHBS is a dynamic process of thermal, fluid (mud invasion), chemical (hydrate dissociation and reformation) and mechanical couplings. All of these factors interact and influence the pore pressure, flow ability, saturation of fluid and hydrates, mechanical parameters and electrical properties of sediments around the borehole, thereby having a strong effect on borehole stability and the results of well logging. The effect is particularly clear in the borehole SH7 of GMGS-1 project. The borehole collapse and resistivity distortion were observed during practical drilling and wireline logging operations in borehole SH7 of the GMGS-1.mud density (i.e. the corresponding borehole pressure), temperature and salinity have a marked influence on the dynamics of mud invasion and on hydrate stability. Therefore, perhaps well-logging distortion caused by mud invasion, hydrate dissociation and reformation should be considered for identifying and evaluating gas hydrate reservoirs. And some suitable drilling

  3. Application of Crunch-Flow Routines to Constrain Present and Past Carbon Fluxes at Gas-Hydrate Bearing Sites

    Energy Technology Data Exchange (ETDEWEB)

    Torres, Marta

    2014-01-31

    In November 2012, Oregon State University initiated the project entitled: Application of Crunch-Flow routines to constrain present and past carbon fluxes at gas-hydrate bearing sites. Within this project we developed Crunch-Flow based modeling modules that include important biogeochemical processes that need to be considered in gas hydrate environments. Our modules were applied to quantify carbon cycling in present and past systems, using data collected during several DOE-supported drilling expeditions, which include the Cascadia margin in US, Ulleung Basin in South Korea, and several sites drilled offshore India on the Bay of Bengal and Andaman Sea. Specifically, we completed modeling efforts that: 1) Reproduce the compositional and isotopic profiles observed at the eight drilled sites in the Ulleung Basin that constrain and contrast the carbon cycling pathways at chimney (high methane flux) and non-chimney sites (low methane, advective systems); 2) Simulate the Ba record in the sediments to quantify the past dynamics of methane flux in the southern Hydrate Ridge, Cascadia margin; and 3) Provide quantitative estimates of the thickness of individual mass transport deposits (MTDs), time elapsed after the MTD event, rate of sulfate reduction in the MTD, and time required to reach a new steady state at several sites drilled in the Krishna-Godavari (K-G) Basin off India. In addition we developed a hybrid model scheme by coupling a home-made MATLAB code with CrunchFlow to address the methane transport and chloride enrichment at the Ulleung Basins chimney sites, and contributed the modeling component to a study focusing on pore-scale controls on gas hydrate distribution in sediments from the Andaman Sea. These efforts resulted in two manuscripts currently under review, and contributed the modeling component of another pare, also under review. Lessons learned from these efforts are the basis of a mini-workshop to be held at Oregon State University (Feb 2014) to instruct

  4. Neural network analysis of crosshole tomographic images: The seismic signature of gas hydrate bearing sediments in the Mackenzie Delta (NW Canada)

    Science.gov (United States)

    Bauer, K.; Pratt, R. G.; Haberland, C.; Weber, M.

    2008-10-01

    Crosshole seismic experiments were conducted to study the in-situ properties of gas hydrate bearing sediments (GHBS) in the Mackenzie Delta (NW Canada). Seismic tomography provided images of P velocity, anisotropy, and attenuation. Self-organizing maps (SOM) are powerful neural network techniques to classify and interpret multi-attribute data sets. The coincident tomographic images are translated to a set of data vectors in order to train a Kohonen layer. The total gradient of the model vectors is determined for the trained SOM and a watershed segmentation algorithm is used to visualize and map the lithological clusters with well-defined seismic signatures. Application to the Mallik data reveals four major litho-types: (1) GHBS, (2) sands, (3) shale/coal interlayering, and (4) silt. The signature of seismic P wave characteristics distinguished for the GHBS (high velocities, strong anisotropy and attenuation) is new and can be used for new exploration strategies to map and quantify gas hydrates.

  5. Pressure Core Characterization

    Science.gov (United States)

    Santamarina, J. C.

    2014-12-01

    Natural gas hydrates form under high fluid pressure and low temperature, and are found in permafrost, deep lakes or ocean sediments. Hydrate dissociation by depressurization and/or heating is accompanied by a multifold hydrate volume expansion and host sediments with low permeability experience massive destructuration. Proper characterization requires coring, recovery, manipulation and testing under P-T conditions within the stability field. Pressure core technology allows for the reliable characterization of hydrate bearing sediments within the stability field in order to address scientific and engineering needs, including the measurement of parameters used in hydro-thermo-mechanical analyses, and the monitoring of hydrate dissociation under controlled pressure, temperature, effective stress and chemical conditions. Inherent sampling effects remain and need to be addressed in test protocols and data interpretation. Pressure core technology has been deployed to study hydrate bearing sediments at several locations around the world. In addition to pressure core testing, a comprehensive characterization program should include sediment analysis, testing of reconstituted specimens (with and without synthetic hydrate), and in situ testing. Pressure core characterization technology can be used to study other gas-charged formations such as deep sea sediments, coal bed methane and gas shales.

  6. Magnetic to magnetic and kinetic to magnetic energy transfers at the top of the Earth's core

    Science.gov (United States)

    Huguet, Ludovic; Amit, Hagay; Alboussière, Thierry

    2016-11-01

    We develop the theory for the magnetic to magnetic and kinetic to magnetic energy transfer between different spherical harmonic degrees due to the interaction of fluid flow and radial magnetic field at the top of the Earth's core. We show that non-zero secular variation of the total magnetic energy could be significant and may provide evidence for the existence of stretching secular variation, which suggests the existence of radial motions at the top of the Earth's core-whole core convection or MAC waves. However, the uncertainties of the small scales of the geomagnetic field prevent a definite conclusion. Combining core field and flow models we calculate the detailed magnetic to magnetic and kinetic to magnetic energy transfer matrices. The magnetic to magnetic energy transfer shows a complex behaviour with local and non-local transfers. The spectra of magnetic to magnetic energy transfers show clear maxima and minima, suggesting an energy cascade. The kinetic to magnetic energy transfers, which are much weaker due to the weak poloidal flow, are either local or non-local between degree one and higher degrees. The patterns observed in the matrices resemble energy transfer patterns that are typically found in 3-D MHD numerical simulations.

  7. Application of the Split Hopkinson Resonant Bar Test for Seismic Property Characterization of Hydrate-bearing Sand Undergoing Water Saturation

    Energy Technology Data Exchange (ETDEWEB)

    Nakagawa, S.; Kneafsey, T.J.

    2011-05-03

    Conventional resonant bar tests allow the measurement of seismic properties of rocks and sediments at low frequencies (several kilohertz). However, the tests require a long, slender sample which is often difficult to obtain from the deep subsurface and weak and fractured formations. We present an alternative low-frequency measurement technique to the conventional resonant bar tests. This technique involves a jacketed core sample placed between a pair of long, metal extension rods with attached seismic source and receiver—the same geometry as the split Hopkinson pressure bar test for large-strain, dynamic impact experiments. Because of the added length and mass to the sample, the resonance frequency of the entire system can be lowered significantly, compared to the sample alone. The proposed “Split Hopkinson Resonant Bar (SHRB)” test is applied in two steps. In the first step, extension and torsion-mode resonance frequencies and attenuation of the system are measured. Then, numerical inversions for the compressional and shear wave velocities and attenuation are performed. We initially applied the SHRB test to synthetic materials (plastics) for testing its accuracy, then used it for measuring the seismic velocities and attenuation of a rock core containing supercritical CO{sub 2}, and a sediment core while methane hydrate formed in the pore space.

  8. Kinetic AGN feedback effects on cluster cool cores simulated using SPH

    Science.gov (United States)

    Barai, Paramita; Murante, Giuseppe; Borgani, Stefano; Gaspari, Massimo; Granato, Gian Luigi; Monaco, Pierluigi; Ragone-Figueroa, Cinthia

    2016-09-01

    We implement novel numerical models of AGN feedback in the SPH code GADGET-3, where the energy from a supermassive black hole (BH) is coupled to the surrounding gas in the kinetic form. Gas particles lying inside a bi-conical volume around the BH are imparted a one-time velocity (10 000 km s-1) increment. We perform hydrodynamical simulations of isolated cluster (total mass 1014 h-1 M⊙), which is initially evolved to form a dense cool core, having central T ≤ 106 K. A BH resides at the cluster centre, and ejects energy. The feedback-driven fast wind undergoes shock with the slower moving gas, which causes the imparted kinetic energy to be thermalized. Bipolar bubble-like outflows form propagating radially outward to a distance of a few 100 kpc. The radial profiles of median gas properties are influenced by BH feedback in the inner regions (r < 20-50 kpc). BH kinetic feedback, with a large value of the feedback efficiency, depletes the inner cool gas and reduces the hot gas content, such that the initial cool core of the cluster is heated up within a time 1.9 Gyr, whereby the core median temperature rises to above 107 K, and the central entropy flattens. Our implementation of BH thermal feedback (using the same efficiency as kinetic), within the star formation model, cannot do this heating, where the cool core remains. The inclusion of cold gas accretion in the simulations produces naturally a duty cycle of the AGN with a periodicity of 100 Myr.

  9. An algorithm for multi-group two-dimensional neutron diffusion kinetics in nuclear reactor cores

    OpenAIRE

    Marcelo Schramm

    2016-01-01

    The objective of this thesis is to introduce a new methodology for two{dimensional multi{ group neutron diffusion kinetics in a reactor core. The presented methodology uses a polyno- mial approximation in a rectangular homogeneous domain with non{homogeneous boundary conditions. As it consists on a truncated Taylor series, its error estimates varies with the size of the rectangle. The coefficients are obtained mainly by their relations with the independent term, which is determined by the dif...

  10. On the path to the digital rock physics of gas hydrate-bearing sediments - processing of in situ synchrotron-tomography data

    Science.gov (United States)

    Sell, Kathleen; Saenger, Erik H.; Falenty, Andrzej; Chaouachi, Marwen; Haberthür, David; Enzmann, Frieder; Kuhs, Werner F.; Kersten, Michael

    2016-08-01

    To date, very little is known about the distribution of natural gas hydrates in sedimentary matrices and its influence on the seismic properties of the host rock, in particular at low hydrate concentration. Digital rock physics offers a unique approach to this issue yet requires good quality, high-resolution 3-D representations for the accurate modeling of petrophysical and transport properties. Although such models are readily available via in situ synchrotron radiation X-ray tomography, the analysis of such data asks for complex workflows and high computational power to maintain valuable results. Here, we present a best-practice procedure complementing data from Chaouachi et al. (2015) with data post-processing, including image enhancement and segmentation as well as exemplary numerical simulations of an acoustic wave propagation in 3-D using the derived results. A combination of the tomography and 3-D modeling opens a path to a more reliable deduction of properties of gas hydrate-bearing sediments without a reliance on idealized and frequently imprecise models.

  11. Simulation on reactor TRIGA Puspati core kinetics fueled with thorium (Th) based fuel element

    Science.gov (United States)

    Mohammed, Abdul Aziz; Pauzi, Anas Muhamad; Rahman, Shaik Mohmmed Haikhal Abdul; Zin, Muhamad Rawi Muhammad; Jamro, Rafhayudi; Idris, Faridah Mohamad

    2016-01-01

    In confronting global energy requirement and the search for better technologies, there is a real case for widening the range of potential variations in the design of nuclear power plants. Smaller and simpler reactors are attractive, provided they can meet safety and security standards and non-proliferation issues. On fuel cycle aspect, thorium fuel cycles produce much less plutonium and other radioactive transuranic elements than uranium fuel cycles. Although not fissile itself, Th-232 will absorb slow neutrons to produce uranium-233 (233U), which is fissile. By introducing Thorium, the numbers of highly enriched uranium fuel element can be reduced while maintaining the core neutronic performance. This paper describes the core kinetic of a small research reactor core like TRIGA fueled with a Th filled fuel element matrix using a general purpose Monte Carlo N-Particle (MCNP) code.

  12. Simulation on reactor TRIGA Puspati core kinetics fueled with thorium (Th) based fuel element

    Energy Technology Data Exchange (ETDEWEB)

    Mohammed, Abdul Aziz, E-mail: azizM@uniten.edu.my; Rahman, Shaik Mohmmed Haikhal Abdul [Universiti Tenaga Nasional. Jalan Ikram-UNITEN, 43000 Kajang, Selangor (Malaysia); Pauzi, Anas Muhamad, E-mail: anas@uniten.edu.my; Zin, Muhamad Rawi Muhammad; Jamro, Rafhayudi; Idris, Faridah Mohamad [Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor (Malaysia)

    2016-01-22

    In confronting global energy requirement and the search for better technologies, there is a real case for widening the range of potential variations in the design of nuclear power plants. Smaller and simpler reactors are attractive, provided they can meet safety and security standards and non-proliferation issues. On fuel cycle aspect, thorium fuel cycles produce much less plutonium and other radioactive transuranic elements than uranium fuel cycles. Although not fissile itself, Th-232 will absorb slow neutrons to produce uranium-233 ({sup 233}U), which is fissile. By introducing Thorium, the numbers of highly enriched uranium fuel element can be reduced while maintaining the core neutronic performance. This paper describes the core kinetic of a small research reactor core like TRIGA fueled with a Th filled fuel element matrix using a general purpose Monte Carlo N-Particle (MCNP) code.

  13. Effects of different per translational kinetics on the dynamics of a core circadian clock model.

    Directory of Open Access Journals (Sweden)

    Paula S Nieto

    Full Text Available Living beings display self-sustained daily rhythms in multiple biological processes, which persist in the absence of external cues since they are generated by endogenous circadian clocks. The period (per gene is a central player within the core molecular mechanism for keeping circadian time in most animals. Recently, the modulation PER translation has been reported, both in mammals and flies, suggesting that translational regulation of clock components is important for the proper clock gene expression and molecular clock performance. Because translational regulation ultimately implies changes in the kinetics of translation and, therefore, in the circadian clock dynamics, we sought to study how and to what extent the molecular clock dynamics is affected by the kinetics of PER translation. With this objective, we used a minimal mathematical model of the molecular circadian clock to qualitatively characterize the dynamical changes derived from kinetically different PER translational mechanisms. We found that the emergence of self-sustained oscillations with characteristic period, amplitude, and phase lag (time delays between per mRNA and protein expression depends on the kinetic parameters related to PER translation. Interestingly, under certain conditions, a PER translation mechanism with saturable kinetics introduces longer time delays than a mechanism ruled by a first-order kinetics. In addition, the kinetic laws of PER translation significantly changed the sensitivity of our model to parameters related to the synthesis and degradation of per mRNA and PER degradation. Lastly, we found a set of parameters, with realistic values, for which our model reproduces some experimental results reported recently for Drosophila melanogaster and we present some predictions derived from our analysis.

  14. Analysis of core samples from the BPXA-DOE-USGS Mount Elbert gas hydrate stratigraphic test well: Insights into core disturbance and handling

    Energy Technology Data Exchange (ETDEWEB)

    Kneafsey, Timothy J.; Lu, Hailong; Winters, William; Boswell, Ray; Hunter, Robert; Collett, Timothy S.

    2009-09-01

    Collecting and preserving undamaged core samples containing gas hydrates from depth is difficult because of the pressure and temperature changes encountered upon retrieval. Hydrate-bearing core samples were collected at the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well in February 2007. Coring was performed while using a custom oil-based drilling mud, and the cores were retrieved by a wireline. The samples were characterized and subsampled at the surface under ambient winter arctic conditions. Samples thought to be hydrate bearing were preserved either by immersion in liquid nitrogen (LN), or by storage under methane pressure at ambient arctic conditions, and later depressurized and immersed in LN. Eleven core samples from hydrate-bearing zones were scanned using x-ray computed tomography to examine core structure and homogeneity. Features observed include radial fractures, spalling-type fractures, and reduced density near the periphery. These features were induced during sample collection, handling, and preservation. Isotopic analysis of the methane from hydrate in an initially LN-preserved core and a pressure-preserved core indicate that secondary hydrate formation occurred throughout the pressurized core, whereas none occurred in the LN-preserved core, however no hydrate was found near the periphery of the LN-preserved core. To replicate some aspects of the preservation methods, natural and laboratory-made saturated porous media samples were frozen in a variety of ways, with radial fractures observed in some LN-frozen sands, and needle-like ice crystals forming in slowly frozen clay-rich sediments. Suggestions for hydrate-bearing core preservation are presented.

  15. Magnetic Field Generation in Core-Sheath Jets via the Kinetic Kelvin-Helmholtz Instability

    CERN Document Server

    Nishikawa, K -I; Dutan, I; Niemiec, J; Medvedev, M; Mizuno, Y; Meli, A; Sol, H; Zhang, B; Pohl, M; Hartmann, D H

    2014-01-01

    We have investigated magnetic field generation in velocity shears via the kinetic Kelvin-Helmholtz instability (kKHI) using a relativistic plasma jet core and stationary plasma sheath. Our three-dimensional particle-in-cell simulations consider plasma jet cores with Lorentz factors of 1.5, 5, and 15 for both electron-proton and electron-positron plasmas. For electron-proton plasmas we find generation of strong large-scale DC currents and magnetic fields which extend over the entire shear-surface and reach thicknesses of a few tens of electron skin depths. For electron-positron plasmas we find generation of alternating currents and magnetic fields. Jet and sheath plasmas are accelerated across the shear surface in the strong magnetic fields generated by the kKHI. The mixing of jet and sheath plasmas generates transverse structure similar to that produced by the Weibel instability.

  16. Magnetic field generation in core-sheath jets via the kinetic Kelvin-Helmholtz instability

    Energy Technology Data Exchange (ETDEWEB)

    Nishikawa, K.-I. [Department of Physics, University of Alabama in Huntsville, ZP12, Huntsville, AL 35899 (United States); Hardee, P. E. [Department of Physics and Astronomy, The University of Alabama, Tuscaloosa, AL 35487 (United States); Duţan, I. [Institute of Space Science, Atomistilor 409, Bucharest-Magurele RO-077125 (Romania); Niemiec, J. [Institute of Nuclear Physics PAN, ul. Radzikowskiego 152, 31-342 Kraków (Poland); Medvedev, M. [Department of Physics and Astronomy, University of Kansas, KS 66045 (United States); Mizuno, Y. [Institute of Astronomy, National Tsing-Hua University, Hsinchu, Taiwan 30013 (China); Meli, A. [Department of Physics and Astronomy, University of Gent, Proeftuinstraat 86 B-9000, Gent (Belgium); Sol, H. [LUTH, Observatore de Paris-Meudon, 5 place Jules Jansen, F-92195 Meudon Cedex (France); Zhang, B. [Department of Physics, University of Nevada, Las Vegas, NV 89154 (United States); Pohl, M. [Institut fur Physik und Astronomie, Universität Potsdam, D-14476 Potsdam-Golm (Germany); Hartmann, D. H., E-mail: ken-ichi.nishikawa@nasa.gov [Department of Physics and Astronomy, Clemson University, Clemson, SC 29634 (United States)

    2014-09-20

    We have investigated magnetic field generation in velocity shears via the kinetic Kelvin-Helmholtz instability (kKHI) using a relativistic plasma jet core and stationary plasma sheath. Our three-dimensional particle-in-cell simulations consider plasma jet cores with Lorentz factors of 1.5, 5, and 15 for both electron-proton and electron-positron plasmas. For electron-proton plasmas, we find generation of strong large-scale DC currents and magnetic fields that extend over the entire shear surface and reach thicknesses of a few tens of electron skin depths. For electron-positron plasmas, we find generation of alternating currents and magnetic fields. Jet and sheath plasmas are accelerated across the shear surface in the strong magnetic fields generated by the kKHI. The mixing of jet and sheath plasmas generates a transverse structure similar to that produced by the Weibel instability.

  17. Six weeks of core stability training improves landing kinetics among female capoeira athletes: a pilot study.

    Science.gov (United States)

    Araujo, Simone; Cohen, Daniel; Hayes, Lawrence

    2015-03-29

    Core stability training (CST) has increased in popularity among athletes and the general fitness population despite limited evidence CST programmes alone lead to improved athletic performance. In female athletes, neuromuscular training combining balance training and trunk and hip/pelvis dominant CST is suggested to reduce injury risk, and specifically peak vertical ground reaction forces (vGRF) in a drop jump landing task. However, the isolated effect of trunk dominant core stability training on vGRF during landing in female athletes had not been evaluated. Therefore, the objective of this study was to evaluate landing kinetics during a drop jump test following a CST intervention in female capoeira athletes. After giving their informed written consent, sixteen female capoeira athletes (mean ± SD age, stature, and body mass of 27.3 ± 3.7 years, 165.0 ± 4.0 cm, and 59.7 ± 6.3 kg, respectively) volunteered to participate in the training program which consisted of static and dynamic CST sessions, three times per week for six weeks. The repeated measures T-test revealed participants significantly reduced relative vGRF from pre- to post-intervention for the first (3.40 ± 0.78 vs. 2.85 ± 0.52 N·NBW-1, respectively [pcore stability training improves landing kinetics without improving jump height, and may reduce lower extremity injury risk in female athletes.

  18. Kinetic AGN Feedback Effects on Cluster Cool Cores Simulated using SPH

    CERN Document Server

    Barai, Paramita; Borgani, Stefano; Gaspari, Massimo; Granato, Gian Luigi; Monaco, Pierluigi; Ragone-Figueroa, Cinthia

    2016-01-01

    We implement novel numerical models of AGN feedback in the SPH code GADGET-3, where the energy from a supermassive black hole (BH) is coupled to the surrounding gas in the kinetic form. Gas particles lying inside a bi-conical volume around the BH are imparted a one-time velocity (10,000 km/s) increment. We perform hydrodynamical simulations of isolated cluster (total mass 10^14 /h M_sun), which is initially evolved to form a dense cool core, having central T<10^6 K. A BH resides at the cluster center, and ejects energy. The feedback-driven fast wind undergoes shock with the slower-moving gas, which causes the imparted kinetic energy to be thermalized. Bipolar bubble-like outflows form propagating radially outward to a distance of a few 100 kpc. The radial profiles of median gas properties are influenced by BH feedback in the inner regions (r<20-50 kpc). BH kinetic feedback, with a large value of the feedback efficiency, depletes the inner cool gas and reduces the hot gas content, such that the initial c...

  19. 含气水合物沉积物弹塑性损伤本构模型探讨%A constitutive model coupling elastoplasticity and damage for methane hydrate-bearing sediments

    Institute of Scientific and Technical Information of China (English)

    杨期君; 赵春风

    2014-01-01

    天然气水合物的开采会带来一系列的岩土工程问题,为了保障相关工程设施的安全,有必要建立一个合理的水合物沉积物本构模型。通过深入分析水合物沉积物力学特点,从颗粒间的作用机制出发,认为水合物沉积物的力学响应是沉积物中土体颗粒间摩擦与水合物胶结二者共同作用的结果;考虑到摩擦与接触特性不同的力学机制,分别采用修正剑桥模型和弹性损伤模型对土体骨架及水合物胶结的应力-应变关系进行描述;通过假定水合物胶结的损伤演化规律,并认为在受力变形过程中二者的应变始终相等,初步建立了一个水合物沉积物的弹塑性损伤本构模型。不同水合物饱和度沉积物应力-应变曲线的模型预测结果与室内三轴排水试验结果吻合良好,表明了所建模型的可行性和合理性。%The extraction of methane hydrate in the seabed will result in a series of geotechnical engineering problems and disasters. In order to ensure the safety of the related engineering facilities during the extraction, it is necessary to build reasonable constitutive model for methane hydrate bearing sediments. Based on the thorough study of the geomechanical characteristics of hydrate bearing sediments and the contacts between soil grains, the authors suppose that the geomechanical behavior of hydrate bearing sediments resulting from the combination of the friction between soil grains and cementation due to methane hydrate. Considering the different mechanical mechanisms of the friction and cementation, the modified Cam-clay model and elasticity damage model are employed to describe their mechanical responses respectively. By assuming that soil skeleton and cementation have the same strain during the loading, a constitutive model coupling elastoplasticity and damage for methane hydrate bearing sediments is then established based on a simplified damage evolution law. The

  20. Determination of the kinetic parameters of the CALIBAN metallic core reactor from stochastic neutron measurements

    Energy Technology Data Exchange (ETDEWEB)

    Casoli, P.; Authier, N.; Chapelle, A. [Commissariat a l' Energie Atomique et Aux Energies Alternatives, CEA, DAM, F-21120 Is sur Tille (France)

    2012-07-01

    Several experimental devices are operated by the Criticality and Neutron Science Research Dept. of the CEA Valduc Laboratory. One of these is the Caliban metallic core reactor. The purpose of this study is to develop and perform experiments allowing to determinate some of fundamental kinetic parameters of the reactor. The prompt neutron decay constant and particularly its value at criticality can be measured with reactor noise techniques such as Rossi-{alpha} and Feynman variance-to-mean methods. Subcritical, critical, and even supercritical experiments were performed. Fission chambers detectors were put nearby the core and measurements were analyzed with the Rossi-{alpha} technique. A new value of the prompt neutron decay constant at criticality was determined, which allows, using the Nelson number method, new evaluations of the effective delayed neutron fraction and the in core neutron lifetime. As an introduction of this paper, some motivations of this work are given in part 1. In part 2, principles of the noise measurements experiments performed at the CEA Valduc Laboratory are reminded. The Caliban reactor is described in part 3. Stochastic neutron measurements analysis techniques used in this study are then presented in part 4. Results of fission chamber experiments are summarized in part 5. Part 6 is devoted to the current work, improvement of the experimental device using He 3 neutron detectors and first results obtained with it. Finally, conclusions and perspectives are given in part 7. (authors)

  1. A Kinetic Vlasov Model for Plasma Simulation Using Discontinuous Galerkin Method on Many-Core Architectures

    Science.gov (United States)

    Reddell, Noah

    Advances are reported in the three pillars of computational science achieving a new capability for understanding dynamic plasma phenomena outside of local thermodynamic equilibrium. A continuum kinetic model for plasma based on the Vlasov-Maxwell system for multiple particle species is developed. Consideration is added for boundary conditions in a truncated velocity domain and supporting wall interactions. A scheme to scale the velocity domain for multiple particle species with different temperatures and particle mass while sharing one computational mesh is described. A method for assessing the degree to which the kinetic solution differs from a Maxwell-Boltzmann distribution is introduced and tested on a thoroughly studied test case. The discontinuous Galerkin numerical method is extended for efficient solution of hyperbolic conservation laws in five or more particle phase-space dimensions using tensor-product hypercube elements with arbitrary polynomial order. A scheme for velocity moment integration is integrated as required for coupling between the plasma species and electromagnetic waves. A new high performance simulation code WARPM is developed to efficiently implement the model and numerical method on emerging many-core supercomputing architectures. WARPM uses the OpenCL programming model for computational kernels and task parallelism to overlap computation with communication. WARPM single-node performance and parallel scaling efficiency are analyzed with bottlenecks identified guiding future directions for the implementation. The plasma modeling capability is validated against physical problems with analytic solutions and well established benchmark problems.

  2. Reflection and transmission of bottom simulating reflectors in gas hydrate-bearing sediments: Two-phase media models%天然气水合物似海底反射层(BSR)AVA特征:双相介质模型

    Institute of Scientific and Technical Information of China (English)

    麻纪强; 耿建华

    2008-01-01

    The bottom simulating reflector (BSR) in gas hydrate-bearing sediments is a physical interface which is composed of solid, gas, and liquid and is influenced by temperature and pressure. Deep sea floor sediment is a porous, unconsolidated, fluid saturated media. Therefore, the reflection and transmission coefficients computed by the Zoeppritz equation based on elastic media do not match reality. In this paper, a two-phase media model is applied to study the reflection and transmission at the bottom simulating reflector in order to find an accurate wave propagation energy distribution and the relationship between reflection and transmission and fluid saturation on the BSR. The numerical experiments show that the type I compressional (fast) and shear waves are not sensitive to frequency variation and the velocities change slowly over the whole frequency range. However, type II compressional (slow) waves are more sensitive to frequency variation and the velocities change over a large range. We find that reflection and transmission coefficients change with the amount of hydrate and free gas. Frequency, pore fluid saturation, and incident angle have different impacts on the reflection and transmission coefficients. We can use these characteristics to estimate gas hydrate saturation or detect lithological variations in the gas hydrate-bearing sediments.

  3. Kinetic and Thermodynamic Characterization of the Cobalt and Manganese Oxyhydroxide Cores Formed in Horse Spleen Ferritin

    Science.gov (United States)

    Zhang, Bo; Harb, John N.; Davis, Robert C.; Kim, Jae-Woo; Chu, Sang-Hyon; Choi, Sang; Miller, Tim; Watt, Gerald D.

    2004-01-01

    Horse spleen ferritin (HoSF) containing 800-1500 cobalt or 250-1200 manganese atoms as Co(O)OH and Mn(O)OH mineral cores within the HoSF interior (Co-HoSF and Mn-HoSF) was synthesized, and the chemical reactivity, kinetics of reduction, and the reduction potentials were measured. Microcoulometric and chemical reduction of HoSF containing the M(O)OH mineral core (M = Co or Mn) was rapid and quantitative with a reduction stoichiometry of 1.05+/-0.10 e/M forming a stable M(OH)2 mineral core. At pH 9.0, ascorbic acid (AH2), a two-electron reductant, effectively reduced the mineral cores; however, the reaction was incomplete and rapidly reached equilibrium. The addition of excess AH2 shifted the reaction to completion with a M(3+)/AH2 stoichiometry of 1.9-2.1, consistent with a single electron per metal atom reduction. The rate of reaction between M(0)OH and excess AH2 was measured by monitoring the decrease in mineral core absorbance with time. The reaction was first order in each reactant with second-order rate constants of 0.53 and 4.74/M/min, respectively, for Co- and Mn-HoSF at pH 9.0. From the variation of absorbance with increasing AH2 concentration, equilibrium constants at pH 9.0 of 5.0+/-1.9 for Co-HoSF and 2.9+/-0.9 for Mn-HoSF were calculated for 2M(O)OH + AH2 = 2M(OH)2 f D, where AH2 and D are ascorbic acid and dehydroascorbic acid, respectively. Consistent with these equilibrium constants, the standard potential for the reduction of Co(III)-HoSF is 42 mV more positive than that of the ascorbic acid reaction, while the standard potential of Mn(III)-HoSF is 27 mV positive relative to AH2. Fe(2+) in solution with Co- and Mn-HoSF under anaerobic conditions was oxidized to form Fe(O)OH within the HoSF interior, resulting in partial displacement of the Co or Mn by iron.

  4. Six Weeks of Core Stability Training Improves Landing Kinetics Among Female Capoeira Athletes: A Pilot Study

    Science.gov (United States)

    Araujo, Simone; Cohen, Daniel; Hayes, Lawrence

    2015-01-01

    Core stability training (CST) has increased in popularity among athletes and the general fitness population despite limited evidence CST programmes alone lead to improved athletic performance. In female athletes, neuromuscular training combining balance training and trunk and hip/pelvis dominant CST is suggested to reduce injury risk, and specifically peak vertical ground reaction forces (vGRF) in a drop jump landing task. However, the isolated effect of trunk dominant core stability training on vGRF during landing in female athletes had not been evaluated. Therefore, the objective of this study was to evaluate landing kinetics during a drop jump test following a CST intervention in female capoeira athletes. After giving their informed written consent, sixteen female capoeira athletes (mean ± SD age, stature, and body mass of 27.3 ± 3.7 years, 165.0 ± 4.0 cm, and 59.7 ± 6.3 kg, respectively) volunteered to participate in the training program which consisted of static and dynamic CST sessions, three times per week for six weeks. The repeated measures T-test revealed participants significantly reduced relative vGRF from pre- to post-intervention for the first (3.40 ± 0.78 vs. 2.85 ± 0.52 N·NBW-1, respectively [p<0.05, effect size = 0.60]), and second landing phase (5.09 ± 1.17 vs. 3.02 ± 0.41 N·NBW-1, respectively [p<0.001, effect size = 0.87]). The average loading rate was reduced from pre- to post-intervention during the second landing phase (30.96 ± 18.84 vs. 12.06 ± 9.83 N·NBW·s-1, respectively [p<0.01, effect size = 0.68]). The peak loading rate was reduced from pre- to post-intervention during the first (220.26 ± 111.51 vs. 120.27 ± 64.57 N·NBW·s-1 respectively [p<0.01, effect size = 0.64]), and second (99.52 ± 54.98 vs. 44.71 ± 30.34 N·NBW·s-1 respectively [p<0.01, effect size = 0.70]) landing phase. Body weight, average loading rate during the first landing phase, and jump height were not significantly different between week 0 and week 6

  5. Examination of core samples from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope: Effects of retrieval and preservation

    Energy Technology Data Exchange (ETDEWEB)

    Kneafsey, T.J.; Liu, T.J. H.; Winters, W.; Boswell, R.; Hunter, R.; Collett, T.S.

    2011-06-01

    Collecting and preserving undamaged core samples containing gas hydrates from depth is difficult because of the pressure and temperature changes encountered upon retrieval. Hydrate-bearing core samples were collected at the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well in February 2007. Coring was performed while using a custom oil-based drilling mud, and the cores were retrieved by a wireline. The samples were characterized and subsampled at the surface under ambient winter arctic conditions. Samples thought to be hydrate bearing were preserved either by immersion in liquid nitrogen (LN), or by storage under methane pressure at ambient arctic conditions, and later depressurized and immersed in LN. Eleven core samples from hydrate-bearing zones were scanned using x-ray computed tomography to examine core structure and homogeneity. Features observed include radial fractures, spalling-type fractures, and reduced density near the periphery. These features were induced during sample collection, handling, and preservation. Isotopic analysis of the methane from hydrate in an initially LN-preserved core and a pressure-preserved core indicate that secondary hydrate formation occurred throughout the pressurized core, whereas none occurred in the LN-preserved core, however no hydrate was found near the periphery of the LN-preserved core. To replicate some aspects of the preservation methods, natural and laboratory-made saturated porous media samples were frozen in a variety of ways, with radial fractures observed in some LN-frozen sands, and needle-like ice crystals forming in slowly frozen clay-rich sediments. Suggestions for hydrate-bearing core preservation are presented.

  6. Examination of core samples from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope: Effects of retrieval and preservation

    Science.gov (United States)

    Kneafsey, T.J.; Lu, H.; Winters, W.; Boswell, R.; Hunter, R.; Collett, T.S.

    2011-01-01

    Collecting and preserving undamaged core samples containing gas hydrates from depth is difficult because of the pressure and temperature changes encountered upon retrieval. Hydrate-bearing core samples were collected at the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well in February 2007. Coring was performed while using a custom oil-based drilling mud, and the cores were retrieved by a wireline. The samples were characterized and subsampled at the surface under ambient winter arctic conditions. Samples thought to be hydrate bearing were preserved either by immersion in liquid nitrogen (LN), or by storage under methane pressure at ambient arctic conditions, and later depressurized and immersed in LN. Eleven core samples from hydrate-bearing zones were scanned using x-ray computed tomography to examine core structure and homogeneity. Features observed include radial fractures, spalling-type fractures, and reduced density near the periphery. These features were induced during sample collection, handling, and preservation. Isotopic analysis of the methane from hydrate in an initially LN-preserved core and a pressure-preserved core indicate that secondary hydrate formation occurred throughout the pressurized core, whereas none occurred in the LN-preserved core, however no hydrate was found near the periphery of the LN-preserved core. To replicate some aspects of the preservation methods, natural and laboratory-made saturated porous media samples were frozen in a variety of ways, with radial fractures observed in some LN-frozen sands, and needle-like ice crystals forming in slowly frozen clay-rich sediments. Suggestions for hydrate-bearing core preservation are presented.

  7. Calculation of kinetic parameters of Caliban metallic core experimental reactor from stochastic neutron measurements

    Energy Technology Data Exchange (ETDEWEB)

    Casoli, P.; Authier, N.; Baud, J. [Commissariat a l' energie Atomique, Centre de Valduc, 21120 Is-sur-Tille (France)

    2009-07-01

    Several experimental devices are operated by the Criticality and Neutron Science Research Department of the CEA Valduc Laboratory. One of these is the metallic core reactor Caliban. The knowledge of the fundamental kinetic parameters of the reactor is very useful, indeed necessary, to the operator. The purpose of this study was to develop and perform experiments allowing to determinate some of these parameters. The prompt neutron decay constant and particularly its value at criticality can be measured with reactor noise techniques such as the interval-distribution, the Feynman variance-to-mean, and the Rossi-{alpha} methods. By introducing the Nelson number, the effective delayed neutron fraction and the average neutron lifetime can also be calculated with the Rossi-{alpha} method. Subcritical, critical, and even supercritical experiments were performed. With the Rossi-{alpha} technique, it was found that the prompt neutron decay constant at criticality was (6.02*10{sup 5} {+-} 9%). Experiments also brought out the limitations of the used experimental parameters. (authors)

  8. Kinetic Parameters Estimation of MgO-C Refractory by Shrinking Core Model

    Institute of Scientific and Technical Information of China (English)

    B.Hashemi; Z.A.Nemati; S.K. Sadrnezhaad; Z.A.Moghimi

    2006-01-01

    Kinetics of oxidation of MgO-C refractories was investigated by shrinking core modeling of the gas-solid reactions taking place during heating the porous materials to the high temperatures. Samples containing 4.5~17 wt pct graphite were isothermally oxidized at 1000~1350℃. Weight loss data was compared with predictions of the model. A mixed 2-stage mechanism comprised of pore diffusion plus boundary layer gas transfer was shown to generally control the oxidation rate. Pore diffusion was however more effective, especially at graphite contents lower than 10 wt pct under forced convection blowing of the air. Model calculations showed that effective gas diffusion coefficients were in the range of 0.08 to 0.55 cm2/s. These values can be utilized to determine the corresponding tortuosity factors of 6.85 to 2.22. Activation energies related to the pore diffusion mechanism appeared to be around (46.4±2)kJ/mol. The estimated intermolecular diffusion coefficients were shown to be independent of the graphite content, when the percentage of the graphite exceeded a marginal value of 10.

  9. Core-Shell Nanocatalysts Obtained in Reverse Micelles: Structural and Kinetic Aspects

    Directory of Open Access Journals (Sweden)

    Concha Tojo

    2015-01-01

    Full Text Available Ability to control the metal arrangement in bimetallic nanocatalysts is the key to improving their catalytic activity. To investigate how metal distribution in nanostructures can be modified, we developed a computer simulation model on the synthesis of bimetallic nanoparticles obtained in microemulsions by a one-pot method. The calculations allow predicting the metal arrangement in nanoparticle under different experimental conditions. We present results for two couples of metals, Au/Pt (Δε=0.26 V and Au/Ag (Δε=0.19 V, but conclusions can be generalized to other bimetallic pairs with similar difference in standard reduction potentials. It was proved that both surface and interior compositions can be controlled at nanometer resolution easily by changing the initial reactant concentration inside micelles. Kinetic analysis demonstrates that the confinement of reactants inside micelles has a strong effect on the reaction rates of the metal precursors. As a result, the final nanocatalyst shows a more mixed core and a better defined shell as concentration is higher.

  10. 含天然气水合物沉积物损伤统计本构模型%A statistical damage constitutive model of hydrate-bearing sediments

    Institute of Scientific and Technical Information of China (English)

    吴二林; 韦昌富; 魏厚振; 颜荣涛

    2013-01-01

    Hydrate saturation and effective confining pressure can significantly influence the mechanical behaviour of hydrate-bearing sediments. In the case, that the effects of the hydrate type, grain size, and testing conditions are excluded, these two variables are the critical factors that determine their elastic modulus. Based on the relationship between equivalent elastic modulus and hydrate saturation, a power function is established for the damage variable, which takes into account the influence of effective confining pressure. Drucker-Prager failure criterion is adopted to describe the strength of a micro-element of hydrate-bearing sediments. By assuming that the variation of the micro-element strength follows Weibull's distribution, a statistical damage constitutive model of hydrate-bearing sediments is developed. By comparing the simulated results with the experimental data available in the literature, we show that the proposed model can describe the stress-strain behavior of the hydrate-bearing sediments very well under the triaxial shearing condition. The results can provide reference for numerical simulation of engineering properties of gas hydrate sediments.%水合物含量、有效围压是影响含天然气水合物沉积物力学性质的主要因素,在忽略其他次要因素(包括水合物种类、试样颗粒大小、试验条件等)的情况下,水合物含量和有效围压是决定试样弹性模量的两个关键参数.在分析等效弹性模量与水合物含量相互关系的基础上,考虑有效围压的影响,建立了弹性模量与有效围压的幂函数关系;同时采用Drucker-Prager破坏准则来表示含天然气水合物沉积物微元强度,并假设其微元强度服从Weibull分布,从而建立了含天然气水合物沉积物的损伤统计本构模型,与不同有效围压下的试验结果及已有研究成果相比较,表明了所建模型能够很好地模拟三轴剪切条件下含水合物沉积物试样的应力-应变

  11. Kinetic parameters study based on burn-up for improving the performance of research reactor equilibrium core

    Directory of Open Access Journals (Sweden)

    Muhammad Atta

    2014-01-01

    Full Text Available In this study kinetic parameters, effective delayed neutron fraction and prompt neutron generation time have been investigated at different burn-up stages for research reactor's equilibrium core utilizing low enriched uranium high density fuel (U3Si2-Al fuel with 4.8 g/cm3 of uranium. Results have been compared with reference operating core of Pakistan research Reactor-1. It was observed that by increasing fuel burn-up, effective delayed neutron fraction is decreased while prompt neutron generation time is increased. However, over all ratio beff/L is decreased with increasing burn-up. Prompt neutron generation time L in the understudy core is lower than reference operating core of reactor at all burn-up steps due to hard spectrum. It is observed that beff is larger in the understudy core than reference operating core of due to smaller size. Calculations were performed with the help of computer codes WIMSD/4 and CITATION.

  12. Micro-bond contact model and its parameters for the deep-sea methane hydrate bearing soils%深海能源土微观力学胶结模型及参数研究

    Institute of Scientific and Technical Information of China (English)

    蒋明镜; 肖俞; 朱方园

    2012-01-01

    天然气水合物主要以胶结物形式存在深海能源土颗粒之间,对能源土强度影响显著,因此研究水合物胶结接触力学特性对能源土力学性质研究有重要作用,而其中的关键是水合物胶结模型及胶结参数的确定。首先,引入并讨论了一种微观胶结接触模型及其对于能源土胶结接触力学特性的适用性;其次,通过文献资料系统分析,获取不同温度、压力及水合物密度条件下天然气水合物的强度与弹性模量表达式;最后,进一步研究了水合物微观胶结模型中的胶结参数,该类水合物微观胶结参数取决于能源土中水合物埋藏深度(赋存环境压力)、温度、水合物密度,这些宏观参量容易确定。%Methane hydrate (MH), which has significant influences on the strength of methane hydrate bearing soils, exits mainly in the form of cement materials between soil particles. Hence, the study of bond mechanical behavior of MH between soil particles is significant to the research of methane hydrate bearing soils, of which the keypoint is the determination of the micro-contact model and corresponding bond parameters of MH. First, a micro-bond contact model is introduced to reflect the contact properties of the soil particles. Second, the strengths and elastic modulus of MH (such as the tensile strength, compressive strength, shear strength and torsion strength) are obtained through the literatures about methane hydrate triaxial tests. Finally, micro bond parameters needed by the contact model are obtained. The results show that the micro bond parameters of gas hydrate are determined by the saturation and strength parameters of gas hydrate, which can be obtained through the temperature, density of hydrate and its burial depth which are easy to be determined.

  13. Full Core TREAT Kinetics Demonstration Using Rattlesnake/BISON Coupling Within MAMMOTH

    Energy Technology Data Exchange (ETDEWEB)

    Ortensi, Javier [Idaho National Lab. (INL), Idaho Falls, ID (United States); DeHart, Mark D. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Gleicher, Frederick N. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Wang, Yaqi [Idaho National Lab. (INL), Idaho Falls, ID (United States); Alberti, Anthony L. [Oregon State Univ., Corvallis, OR (United States); Palmer, Todd S. [Oregon State Univ., Corvallis, OR (United States)

    2015-08-01

    This report summarizes key aspects of research in evaluation of modeling needs for TREAT transient simulation. Using a measured TREAT critical measurement and a transient for a small, experimentally simplified core, Rattlesnake and MAMMOTH simulations are performed building from simple infinite media to a full core model. Cross sections processing methods are evaluated, various homogenization approaches are assessed and the neutronic behavior of the core studied to determine key modeling aspects. The simulation of the minimum critical core with the diffusion solver shows very good agreement with the reference Monte Carlo simulation and the experiment. The full core transient simulation with thermal feedback shows a significantly lower power peak compared to the documented experimental measurement, which is not unexpected in the early stages of model development.

  14. Constraining gas hydrate occurrence in the northern Gulf of Mexico continental slope : fine scale analysis of grain-size in hydrate-bearing sediments

    Energy Technology Data Exchange (ETDEWEB)

    Hangsterfer, A.; Driscoll, N.; Kastner, M. [Scripps Inst. of Oceanography, La Jolla, CA (United States). Geosciences Research Division

    2008-07-01

    Methane hydrates can form within the gas hydrate stability zone (GHSZ) in sea beds. The Gulf of Mexico (GOM) contains an underlying petroleum system and deeply buried, yet dynamic salt deposits. Salt tectonics and fluid expulsion upward through the sediment column result in the formation of fractures, through which high salinity brines migrate into the GHSZ, destabilizing gas hydrates. Thermogenic and biogenic hydrocarbons also migrate to the seafloor along the GOMs northern slope, originating from the thermal and biogenic degradation of organic matter. Gas hydrate occurrence can be controlled by either primary permeability, forming in coarse-grained sediment layers, or by secondary permeability, forming in areas where hydrofracture and faulting generate conduits through which hydrocarbon-saturated fluids flow. This paper presented a study that attempted to determine the relationship between grain-size, permeability, and gas hydrate distribution. Grain-size analyses were performed on cores taken from Keathley Canyon and Atwater Valley in the GOM, on sections of cores that both contained and lacked gas hydrate. Using thermal anomalies as proxies for the occurrence of methane hydrate within the cores, samples of sediment were taken and the grain-size distributions were measured to see if there was a correlation between gas hydrate distribution and grain-size. The paper described the methods, including determination of hydrate occurrence and core analysis. It was concluded that gas hydrate occurrence in Keathley Canyon and Atwater Valley was constrained by secondary permeability and was structurally controlled by hydrofractures and faulting that acted as conduits through which methane-rich fluids flowed. 11 refs., 2 tabs., 5 figs.

  15. 海底扩散体系含天然气水合物沉积物制样方法与装置%A method and apparatus for formation sample of gas hydrates bearing sediments in marine diffusion system

    Institute of Scientific and Technical Information of China (English)

    魏厚振; 韦昌富; 颜荣涛; 吴二林; 陈盼

    2011-01-01

    Natural gas hydrate is one of the most important potential energy sources distributing in the seabed and continental permafrost; at the same time, the dissociation of hydrate in hydrates bearing layers is a triggering factor of global climate change and geologic hazards. The method and apparatus for formation sample is a basic issue for researching on hydrates-bearing sediments(HBS), which require homogeneity of the sample according with in-situ formation mode as soon as possible. Most marine hadrate formed in diffusion system, which means the gas transferred to the hydrate occur zone by diffusion in water and formed hydrate.Gas-bearing water is moved in cycles by constant-flow pump in this method and apparatus; and gas solubility in water is enlarged through stirred by magnetic stirring apparatus; soil sample could be saturated with gas-bearing water in short time; and then reduce the temperature of soil sample, Gas dissolved in water associates with water to form hydrate filling in the pore of soil sample equably. The experiments show that 1 day is spent to form the hydrates-bearing sediments used by silt and CO2 sample. Homogeneity is testified through observing and testing water-contents of different positions in formed sample. Thereby , heterogeneity caused by hydrate distribution in pore of sample and cost time too long is dissolved well; technological basis is provided for physico-mechanical experiments of hydrates bearing sediments.%天然气水合物是分布在海洋和大陆多年冻土中的一种具有巨大商业开发价值的新型战略性替代能源.同时,含天然气水合物地层中水合物的分解将带来严重的地质灾害和气候问题的关注.试验室内开展含天然气水合物沉积物物理力学性质研究需要首先解决的是制样问题,即在试验室内快速形成符合现场原位形成模式的试样,并且水合物均匀分布于土样孔隙中.海洋天然气水合物主要是在扩散体系中形成的,即溶

  16. Alkaline hemp woody core pulping : impregnation characteristics, kinetic modelling and papermaking qualities

    NARCIS (Netherlands)

    Groot, de B.

    1998-01-01

    The aim of this thesis is to elucidate alkaline processing of hemp woody core, supporting the development and optimization of an efficient and non-polluting pulping process. This study has been a constituent of an integral programme to study fibre hemp.

    It is known that

  17. Alkaline hemp woody core pulping: impregnation characteristics, kinetic modelling and papermaking qualities.

    NARCIS (Netherlands)

    Groot, de B.

    1998-01-01

    The aim of this thesis is to elucidate alkaline processing of hemp woody core, supporting the development and optimization of an efficient and non-polluting pulping process. This study has been a constituent of an integral programme to study fibre hemp.It is known that the outer part of the fibre he

  18. TOUGH+HYDRATE v1.2 User's Manual: A Code for the Simulation of System Behavior in Hydrate-Bearing Geologic Media

    Energy Technology Data Exchange (ETDEWEB)

    Moridis, George J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kowalsky, Michael B. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Pruess, Karsten [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2012-08-01

    TOUGH+HYDRATE v1.2 is a code for the simulation of the behavior of hydratebearing geologic systems, and represents the second update of the code since its first release [Moridis et al., 2008]. By solving the coupled equations of mass and heat balance, TOUGH+HYDRATE can model the non-isothermal gas release, phase behavior and flow of fluids and heat under conditions typical of common natural CH4-hydrate deposits (i.e., in the permafrost and in deep ocean sediments) in complex geological media at any scale (from laboratory to reservoir) at which Darcy’s law is valid. TOUGH+HYDRATE v1.2 includes both an equilibrium and a kinetic model of hydrate formation and dissociation. The model accounts for heat and up to four mass components, i.e., water, CH4, hydrate, and water-soluble inhibitors such as salts or alcohols. These are partitioned among four possible phases (gas phase, liquid phase, ice phase and hydrate phase). Hydrate dissociation or formation, phase changes and the corresponding thermal effects are fully described, as are the effects of inhibitors. The model can describe all possible hydrate dissociation mechanisms, i.e., depressurization, thermal stimulation, salting-out effects and inhibitor-induced effects. TOUGH+HYDRATE is a member of TOUGH+, the successor to the TOUGH2 [Pruess et al., 1991] family of codes for multi-component, multiphase fluid and heat flow developed at the Lawrence Berkeley National Laboratory. It is written in standard FORTRAN 95/2003, and can be run on any computational platform (workstation, PC, Macintosh) for which such compilers are available.

  19. CORE

    DEFF Research Database (Denmark)

    Krigslund, Jeppe; Hansen, Jonas; Hundebøll, Martin

    2013-01-01

    different flows. Instead of maintaining these approaches separate, we propose a protocol (CORE) that brings together these coding mechanisms. Our protocol uses random linear network coding (RLNC) for intra- session coding but allows nodes in the network to setup inter- session coding regions where flows...... intersect. Routes for unicast sessions are agnostic to other sessions and setup beforehand, CORE will then discover and exploit intersecting routes. Our approach allows the inter-session regions to leverage RLNC to compensate for losses or failures in the overhearing or transmitting process. Thus, we...... increase the benefits of XORing by exploiting the underlying RLNC structure of individual flows. This goes beyond providing additional reliability to each individual session and beyond exploiting coding opportunistically. Our numerical results show that CORE outperforms both forwarding and COPE...

  20. CORE

    DEFF Research Database (Denmark)

    Krigslund, Jeppe; Hansen, Jonas; Hundebøll, Martin

    2013-01-01

    different flows. Instead of maintaining these approaches separate, we propose a protocol (CORE) that brings together these coding mechanisms. Our protocol uses random linear network coding (RLNC) for intra- session coding but allows nodes in the network to setup inter- session coding regions where flows...... intersect. Routes for unicast sessions are agnostic to other sessions and setup beforehand, CORE will then discover and exploit intersecting routes. Our approach allows the inter-session regions to leverage RLNC to compensate for losses or failures in the overhearing or transmitting process. Thus, we...... increase the benefits of XORing by exploiting the underlying RLNC structure of individual flows. This goes beyond providing additional reliability to each individual session and beyond exploiting coding opportunistically. Our numerical results show that CORE outperforms both forwarding and COPE...

  1. Continuum-kinetic-microscopic model of lung clearance due to core-annular fluid entrainment

    Science.gov (United States)

    Mitran, Sorin

    2013-07-01

    The human lung is protected against aspirated infectious and toxic agents by a thin liquid layer lining the interior of the airways. This airway surface liquid is a bilayer composed of a viscoelastic mucus layer supported by a fluid film known as the periciliary liquid. The viscoelastic behavior of the mucus layer is principally due to long-chain polymers known as mucins. The airway surface liquid is cleared from the lung by ciliary transport, surface tension gradients, and airflow shear forces. This work presents a multiscale model of the effect of airflow shear forces, as exerted by tidal breathing and cough, upon clearance. The composition of the mucus layer is complex and variable in time. To avoid the restrictions imposed by adopting a viscoelastic flow model of limited validity, a multiscale computational model is introduced in which the continuum-level properties of the airway surface liquid are determined by microscopic simulation of long-chain polymers. A bridge between microscopic and continuum levels is constructed through a kinetic-level probability density function describing polymer chain configurations. The overall multiscale framework is especially suited to biological problems due to the flexibility afforded in specifying microscopic constituents, and examining the effects of various constituents upon overall mucus transport at the continuum scale.

  2. Continuum-kinetic-microscopic model of lung clearance due to core-annular fluid entrainment

    Energy Technology Data Exchange (ETDEWEB)

    Mitran, Sorin, E-mail: mitran@unc.edu

    2013-07-01

    The human lung is protected against aspirated infectious and toxic agents by a thin liquid layer lining the interior of the airways. This airway surface liquid is a bilayer composed of a viscoelastic mucus layer supported by a fluid film known as the periciliary liquid. The viscoelastic behavior of the mucus layer is principally due to long-chain polymers known as mucins. The airway surface liquid is cleared from the lung by ciliary transport, surface tension gradients, and airflow shear forces. This work presents a multiscale model of the effect of airflow shear forces, as exerted by tidal breathing and cough, upon clearance. The composition of the mucus layer is complex and variable in time. To avoid the restrictions imposed by adopting a viscoelastic flow model of limited validity, a multiscale computational model is introduced in which the continuum-level properties of the airway surface liquid are determined by microscopic simulation of long-chain polymers. A bridge between microscopic and continuum levels is constructed through a kinetic-level probability density function describing polymer chain configurations. The overall multiscale framework is especially suited to biological problems due to the flexibility afforded in specifying microscopic constituents, and examining the effects of various constituents upon overall mucus transport at the continuum scale.

  3. Application of the isopycnic kinetic plot method for elucidating the potential of sub-2 µm and core-shell particles in SFC.

    Science.gov (United States)

    Delahaye, Sander; Broeckhoven, Ken; Desmet, Gert; Lynen, Frédéric

    2013-11-15

    In this work the isopycnic method to construct kinetic plots for SFC was used to investigate the performance limits of an SFC system when using sub-2 µm fully porous particles and sub-3 µm superficially porous (core-shell) particles. This isopycnic kinetic plot method for SFC was developed and tested earlier for SFC separations on native silica with pure CO2 as mobile phase. In the current work, octadecyl based reversed phase columns were used in combination with a mobile phase that contains 10% methanol as modifier in order to study the applicability of the described methodology to assess the kinetic performance limits of experimental setups in which SFC is used and will, according to all probability, be evolving. SFC and HPLC van Deemter and kinetic plots are constructed for columns packed with fully porous particles with various diameters and for a column packed with core-shell particles. The influence of the experimental kinetic performance limits of the particle diameter and morphology in SFC is shown to be the same as in HPLC. Additionally, kinetic plot predictions were constructed for separations on 1 µm and 0.5 µm particles using the data measured on the 5 µm, 3.5 µm and 1.8 µm fully porous particles. By doing this the potential applicability of 1 µm particles on the contemporary SFC and HPLC systems was demonstrated together with the irrelevance of the use of 0.5 µm particles in SFC.

  4. A New Coupled CFD/Neutron Kinetics System for High Fidelity Simulations of LWR Core Phenomena: Proof of Concept

    Directory of Open Access Journals (Sweden)

    Jorge Pérez Mañes

    2014-01-01

    Full Text Available The Institute for Neutron Physics and Reactor Technology (INR at the Karlsruhe Institute of Technology (KIT is investigating the application of the meso- and microscale analysis for the prediction of local safety parameters for light water reactors (LWR. By applying codes like CFD (computational fluid dynamics and SP3 (simplified transport reactor dynamics it is possible to describe the underlying phenomena in a more accurate manner than by the nodal/coarse 1D thermal hydraulic coupled codes. By coupling the transport (SP3 based neutron kinetics (NK code DYN3D with NEPTUNE-CFD, within a parallel MPI-environment, the NHESDYN platform is created. The newly developed system will allow high fidelity simulations of LWR fuel assemblies and cores. In NHESDYN, a heat conduction solver, SYRTHES, is coupled to NEPTUNE-CFD. The driver module of NHESDYN controls the sequence of execution of the solvers as well as the communication between the solvers based on MPI. In this paper, the main features of NHESDYN are discussed and the proof of the concept is done by solving a single pin problem. The prediction capability of NHESDYN is demonstrated by a code-to-code comparison with the DYNSUB code. Finally, the future developments and validation efforts are highlighted.

  5. Occurrence of dead core in catalytic particles containing immobilized enzymes: analysis for the Michaelis-Menten kinetics and assessment of numerical methods.

    Science.gov (United States)

    Pereira, Félix Monteiro; Oliveira, Samuel Conceição

    2016-11-01

    In this article, the occurrence of dead core in catalytic particles containing immobilized enzymes is analyzed for the Michaelis-Menten kinetics. An assessment of numerical methods is performed to solve the boundary value problem generated by the mathematical modeling of diffusion and reaction processes under steady state and isothermal conditions. Two classes of numerical methods were employed: shooting and collocation. The shooting method used the ode function from Scilab software. The collocation methods included: that implemented by the bvode function of Scilab, the orthogonal collocation, and the orthogonal collocation on finite elements. The methods were validated for simplified forms of the Michaelis-Menten equation (zero-order and first-order kinetics), for which analytical solutions are available. Among the methods covered in this article, the orthogonal collocation on finite elements proved to be the most robust and efficient method to solve the boundary value problem concerning Michaelis-Menten kinetics. For this enzyme kinetics, it was found that the dead core can occur when verified certain conditions of diffusion-reaction within the catalytic particle. The application of the concepts and methods presented in this study will allow for a more generalized analysis and more accurate designs of heterogeneous enzymatic reactors.

  6. 堆芯核设计程序CYCAS动力学模型开发%Development of Kinetics Model in Core Nuclear Design Code CYCAS

    Institute of Scientific and Technical Information of China (English)

    毕光文; 汤春桃; 杨波

    2016-01-01

    The kinetics model and its numerical verification were studied for core nuclear design code CYCAS .The kinetics model employed by CYCAS code was introduced in detail .In order to verify the effectiveness of the kinetics model , the L M W transient benchmark and the dynamic insertion issue of control rod in AP1000 core were simulated and analyzed .The calculation results show that the kinetics model of CYCAS code could obtain reliable results .%对堆芯核设计程序CYCAS的动力学模型及其数值验证进行了研究.详细介绍了CYCAS程序采用的动力学模型.为验证模型的有效性,对L M W瞬态基准题和基于AP1000堆芯动态插棒问题进行了数值模拟和分析.结果表明,CYCAS程序的动力学模型可获得可靠的计算结果.

  7. Analysis of precore/core covariances associated with viral kinetics and genotypes in hepatitis B e antigen-positive chronic hepatitis B patients.

    Directory of Open Access Journals (Sweden)

    Chun-Pei Cheng

    Full Text Available Hepatitis B virus (HBV is one of the most common DNA viruses that can cause aggressive hepatitis, cirrhosis and hepatocellular carcinoma. Although many people are persistently infected with HBV, the kinetics in serum levels of viral loads and the host immune responses vary from person to person. HBV precore/core open reading frame (ORF encoding proteins, hepatitis B e antigen (HBeAg and core antigen (HBcAg, are two indicators of active viral replication. The aim of this study was to discover a variety of amino acid covariances in responses to viral kinetics, seroconversion and genotypes during the course of HBV infection. A one year follow-up study was conducted with a total number of 1,694 clones from 23 HBeAg-positive chronic hepatitis B patients. Serum alanine aminotransferase, HBV DNA and HBeAg levels were measured monthly as criteria for clustering patients into several different subgroups. Monthly derived multiple precore/core ORFs were directly sequenced and translated into amino acid sequences. For each subgroup, time-dependent covariances were identified from their time-varying sequences over the entire follow-up period. The fluctuating, wavering, HBeAg-nonseroconversion and genotype C subgroups showed greater degrees of covariances than the stationary, declining, HBeAg-seroconversion and genotype B. Referring to literature, mutation hotspots within our identified covariances were associated with the infection process. Remarkably, hotspots were predominant in genotype C. Moreover, covariances were also identified at early stage (spanning from baseline to a peak of serum HBV DNA in order to determine the intersections with aforementioned time-dependent covariances. Preserved covariances, namely representative covariances, of each subgroup are visually presented using a tree-based structure. Our results suggested that identified covariances were strongly associated with viral kinetics, seroconversion and genotypes. Moreover

  8. Insight into strain effects on band alignment shifts, carrier localization and recombination kinetics in CdTe/CdS core/shell quantum dots.

    Science.gov (United States)

    Jing, Lihong; Kershaw, Stephen V; Kipp, Tobias; Kalytchuk, Sergii; Ding, Ke; Zeng, Jianfeng; Jiao, Mingxia; Sun, Xiaoyu; Mews, Alf; Rogach, Andrey L; Gao, Mingyuan

    2015-02-11

    The impact of strain on the optical properties of semiconductor quantum dots (QDs) is fundamentally important while still awaiting detailed investigation. CdTe/CdS core/shell QDs represent a typical strained system due to the substantial lattice mismatch between CdTe and CdS. To probe the strain-related effects, aqueous CdTe/CdS QDs were synthesized by coating different sized CdTe QD cores with CdS shells upon the thermal decomposition of glutathione as a sulfur source under reflux. The shell growth was carefully monitored by both steady-state absorption and fluorescence spectroscopy and transient fluorescence spectroscopy. In combination with structural analysis, the band alignments as a consequence of the strain were modified based on band deformation potential theory. By further taking account of these strain-induced band shifts, the effective mass approximation (EMA) model was modified to simulate the electronic structure, carrier spatial localization, and electron-hole wave function overlap for comparing with experimentally derived results. In particular, the electron/hole eigen energies were predicted for a range of structures with different CdTe core sizes and different CdS shell thicknesses. The overlap of electron and hole wave functions was further simulated to reveal the impact of strain on the electron-hole recombination kinetics as the electron wave function progressively shifts into the CdS shell region while the hole wave function remains heavily localized in CdTe core upon the shell growth. The excellent agreement between the strain-modified EMA model with the experimental data suggests that strain exhibits remarkable effects on the optical properties of mismatched core/shell QDs by altering the electronic structure of the system.

  9. Testing of pressurised cores containing gas hydrate from deep ocean sediments

    Energy Technology Data Exchange (ETDEWEB)

    Clayton, C.; Kingston, E.; Priest, J. [Southampton Univ., Highfield, Southampton (United Kingdom). School of Civil Engineering and the Environment; Schultheiss, P. [Geotek Ltd., Daventry, Northamptonshire (United Kingdom)]|[Indian National Gas Hydrate Program Expedition 01, New Delhi (India)

    2008-07-01

    The geotechnical properties of hydrate-bearing sediments were investigated given their importance in predicting the stability of wellbores drilled in hydrate bearing sediments. The properties can also be used to assess the potential for submarine slope instability during exploration or development activity or environmental change. This paper reported on a program of laboratory testing conducted on samples obtained using the hydrate autoclave coring equipment (HYACE) pressurized core barrel system, received at Southampton University following the Indian National Gas Hydrate Program (NGHP) 01 Expedition. The paper described the techniques used at Southampton University, the difficulties encountered, and the results obtained from geotechnical testing of these samples. The program involved a number of stages of testing, including initial appraisal of the geometry, disturbance and hydrate content of the frozen cores using computerized tomography scanning; creation of a photographic record of the frozen cores following their removal from plastic liners; identification of different sections and masses of core to be used in subsequent testing; testing of the best preserved core in the GHRC; selection of small sub-samples for moisture content, organic content and salinity testing; unfreezing of core, and collection of dissociating gas; imaging of subsamples using scanning electron microscopy; particle size distribution (PSD) testing of subsamples; analysis of subsamples for moisture content, salinity and organic content; and a combination of samples to provide sufficient mass for subsequent geotechnical testing. Other stages that were discussed in the paper included a geotechnical description of the sediment; plasticity testing at as received salinity; unconsolidated undrained triaxial shear strength testing at as-received salinity; washing to remove salts; and determination of plasticity with zero salinity pore fluid. The results of the geotechnical testing were reported

  10. Change of Muscle Activity as Well as Kinematic and Kinetic Parameters during Headers after Core Muscle Fatigue

    Directory of Open Access Journals (Sweden)

    Stephan Becker

    2017-01-01

    Full Text Available In soccer, headers are a tactical measure and influenced by numerous factors. The goal of this study was to identify whether changes in kinematics and muscular activity, especially of the head-stabilizing muscles, occur during headers when the core musculature is fatigued. In two subgroups, muscular activity (12 amateur players, age 23.6 ± 4.2 years and kinematics and dynamics (29 amateur players, age 23.7 ± 2.8 years were examined during straight headers on a pendulum header. Data were collected before and after the core muscles were fatigued by an exercise program. Telemetric surface EMG, 3D acceleration sensor, force plate, and video recordings were used. Under fatigue, the activity of M. erector spinae and M. rectus abdominis was significantly reduced in the preparation phase of the header. The activity of M. sternocleidomastoideus was significantly increased during the jump phase, and the hip extension angle during maximum arched body tension was significantly reduced under fatigue. Jumping height, acceleration force impulse, and linear head acceleration were also significantly reduced. We conclude that fatigue of the core muscles affects the motion technique of the header and the activity of the muscle groups stabilizing the head. Therefore, the necessity of specific training in soccer should be emphasized from a medical-preventive point of view.

  11. 钻井液侵入海洋含水合物地层的一维数值模拟研究%Invasion of water-based drilling mud into oceanic gas-hydrate-bearing sediment:One-dimensional numerical simulations

    Institute of Scientific and Technical Information of China (English)

    宁伏龙; 张可霓; 吴能友; 蒋国盛; 张凌; 刘力; 余义兵

    2013-01-01

    mud invasion into oceanic gas hydrate bearing sediments (GHBS) by taking hydrate reservoirs in the Gulf of Mexico as a case. Compared with the conventional oil/gas-bearing sediments, hydrate dissociation and reformation are the main characteristics of mud invasion in GHBS when the invasion condition is in an unstable region of gas hydrates phase diagram. The simulation results show that the density (I. E. , corresponding pressure), temperature, and salt content of drilling fluids have great effects on the process of drilling fluid invasion. When the temperature and salt content of drilling fluids are constants, the higher the density of the drilling fluid is, the greater degree of invasion and hydrate dissociation are. The increased pore pressure caused by the mud invasion, endothermic cooling with hydrate dissociation compounded by the Joule-Thompson effect and lagged effect of heat transfer in sediments, together make water and gas forming secondary hydrates. The secondary hydrate together with existing hydrate probably makes the hydrate saturation higher than original hydrate saturation. This high saturation hydrate ring could be attributed to the displacement effect of mud invasion and the permeability reduction because of secondary hydrates forming. Under the same temperature and pressure of drilling fluids, the higher the salt concentration of the drilling fluid, the faster rate and greater degree of hydrate dissociation due to the stronger thermodynamic inhibition effect and heat transfer efficiency. The occurrence of high-saturation hydrate girdle band seems to mainly depend on the temperature and salinity of drilling fluids. The dissociated free gas, the dilution of water salinity associated with hydrate dissociation and the occurrence of high saturation hydrate ring probably cause the calculated hydrate saturation based on well logging is higher than that of actual hydrate-bearing sediments. Our simulations suggest that in order to keep wellbore stability

  12. Seismic velocities for hydrate-bearing sediments using weighted equation

    Science.gov (United States)

    Lee, M.W.; Hutchinson, D.R.; Collett, T.S.; Dillon, William P.

    1996-01-01

    A weighted equation based on the three-phase time-average and Wood equations is applied to derive a relationship between the compressional wave (P wave) velocity and the amount of hydrates filling the pore space. The proposed theory predicts accurate P wave velocities of marine sediments in the porosity range of 40-80% and provides a practical means of estimating the amount of in situ hydrate using seismic velocity. The shear (S) wave velocity is derived under the assumption that the P to S wave velocity ratio of the hydrated sediments is proportional to the weighted average of the P to S wave velocity ratios of the constituent components of the sediment. In the case that all constituent components are known, a weighted equation using multiphase time-average and Wood equations is possible. However, this study showed that a three-phase equation with modified matrix velocity, compensated for the clay content, is sufficient to accurately predict the compressional wave velocities for the marine sediments. This theory was applied to the laboratory measurements of the P and S wave velocities in permafrost samples to infer the amount of ice in the unconsolidated sediment. The results are comparable to the results obtained by repeatedly applying the two-phase wave scattering theory. The theory predicts that the Poisson's ratio of the hydrated sediments decreases as the hydrate concentration increases and the porosity decreases. In consequence, the amplitude versus offset (AVO) data for the bottom-simulating reflections may reveal positive, negative, or no AVO anomalies depending on the concentration of hydrates in the sediments.

  13. Simulation experiments on gas production from hydrate-bearing sediments

    Institute of Scientific and Technical Information of China (English)

    GONG JianMing; CAO ZhiMin; CHEN JianWen; ZHANG Min; LI Jin; YANG GuiFang

    2009-01-01

    Experiments were made on 58 sediment samples from four sites (1244, 1245, 1250 and 1251) of ODP204 at five temperature points (25, 35, 45, 55 and 65℃) to simulate methane production from hy drate-bearing sediments. Simulation results from site 1244 show that the gas components consist mainly of methane and carbon dioxide, and heavy hydrocarbons more than C2+ cannot be detected.This site also gives results, similar to those from the other three, that the methane production is con trolled by experimental temperatures, generally reaching the maximum gas yields per gram sediment or TOC under lower temperatures (25 and 35℃). In other words, the methane amount could be related to the buried depth of sediments, given the close relation between the depth and temperature. Sediments less than 1200 m below seafioor are inferred to still act as a biogenic gas producer to pour methane into the present hydrate zone, while sedimentary layers more than 1200 m below seafloor have become too biogenically exhausted to offer any biogas, but instead they produce thermogenic gas to give ad ditional supply to the hydrate formation in the study area.

  14. Pore capillary pressure and saturation of methane hydrate bearing sediments

    Institute of Scientific and Technical Information of China (English)

    SUN Shicai; LIU Changling; YE Yuguang; LIU Yufeng

    2014-01-01

    To better understand the relationship between the pore capillary pressure and hydrate saturation in sedi-ments, a new method was proposed. First, the phase equilibria of methane hydrate in fine-grained silica sands were measured. As to the equilibrium data, the pore capillary pressure and saturation of methane hydrate were calculated. The results showed that the phase equilibria of methane hydrates in fine-grained silica sands changed due to the depressed activity of pore water caused by the surface group and negatively charged characteristic of silica particles as well as the capillary pressure in small pores together. The capil-lary pressure increased with the increase of methane hydrate saturation due to the decrease of the available pore space. However, the capillary-saturation relationship could not yet be described quantitatively because of the stochastic habit of hydrate growth.

  15. DNA immunization with fusion of CTLA-4 to hepatitis B virus (HBV core protein enhanced Th2 type responses and cleared HBV with an accelerated kinetic.

    Directory of Open Access Journals (Sweden)

    Ying Yin

    Full Text Available BACKGROUND: Typically, DNA immunization via the intramuscular route induces specific, Th1-dominant immune responses. However, plasmids expressing viral proteins fused to cytotoxic T lymphocyte antigen 4 (CTLA-4 primed Th2-biased responses and were able to induced effective protection against viral challenge in the woodchuck model. Thus, we addressed the question in the mouse model how the Th1/Th2 bias of primed immune responses by a DNA vaccine influences hepatitis B virus (HBV clearance. PRINCIPAL FINDINGS: Plasmids expressing HBV core protein (HBcAg or HBV e antigen and HBcAg fused to the extracellular domain of CTLA-4 (pCTLA-4-HBc, CD27, and full length CD40L were constructed. Immunizations of these DNA plasmids induced HBcAg-specific antibody and cytotoxic T-cell responses in mice, but with different characteristics regarding the titers and subtypes of specific antibodies and intensity of T-cell responses. The plasmid pHBc expressing HBcAg induced an IgG2a-dominant response while immunizations of pCTLA-4-HBc induced a balanced IgG1/IgG2a response. To assess the protective values of the immune responses of different characteristics, mice were pre-immunized with pCTLA-4-HBc and pHBc, and challenged by hydrodynamic injection (HI of pAAV/HBV1.2. HBV surface antigen (HBsAg and DNA in peripheral blood and HBcAg in liver tissue were cleared with significantly accelerated kinetics in both groups. The clearance of HBsAg was completed within 16 days in immunized mice while more than 50% of the control mice are still positive for HBsAg on day 22. Stronger HBcAg-specific T-cell responses were primed by pHBc correlating with a more rapid decline of HBcAg expression in liver tissue, while anti-HBs antibody response developed rapidly in the mice immunized with pCTLA-4-HBc, indicating that the Th1/Th2 bias of vaccine-primed immune responses influences the mode of viral clearance. CONCLUSION: Viral clearance could be efficiently achieved by Th1/Th2-balanced

  16. Simulation of an MSLB scenario using the 3D neutron kinetic core model DYN3D coupled with the CFD software Trio-U

    Energy Technology Data Exchange (ETDEWEB)

    Grahn, Alexander, E-mail: a.grahn@hzdr.de; Gommlich, André; Kliem, Sören; Bilodid, Yurii; Kozmenkov, Yaroslav

    2017-04-15

    Highlights: • Improved thermal-hydraulic description of nuclear reactor cores. • Providing reactor dynamics code with realistic thermal-hydraulic boundary conditions. • Possibility of three-dimensional flow phenomena in the core, such as cross flow, flow reversal. • Simulation at higher spatial resolution as compared to system codes. - Abstract: In the framework of the European project NURESAFE, the reactor dynamics code DYN3D, developed at Helmholtz-Zentrum Dresden-Rossendorf (HZDR), was coupled with the Computational Fluid Dynamics (CFD) solver Trio-U, developed at CEA France, in order to replace DYN3D’s one-dimensional hydraulic part with a full three-dimensional description of the coolant flow in the reactor core at higher spatial resolution. The present document gives an introduction into the coupling method and shows results of its application to the simulation of a Main Steamline Break (MSLB) accident of a Pressurised Water Reactor (PWR).

  17. Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope: Coring operations, core sedimentology, and lithostratigraphy

    Science.gov (United States)

    Rose, K.; Boswell, R.; Collett, T.

    2011-01-01

    In February 2007, BP Exploration (Alaska), the U.S. Department of Energy, and the U.S. Geological Survey completed the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well (Mount Elbert well) in the Milne Point Unit on the Alaska North Slope. The program achieved its primary goals of validating the pre-drill estimates of gas hydrate occurrence and thickness based on 3-D seismic interpretations and wireline log correlations and collecting a comprehensive suite of logging, coring, and pressure testing data. The upper section of the Mount Elbert well was drilled through the base of ice-bearing permafrost to a casing point of 594??m (1950??ft), approximately 15??m (50??ft) above the top of the targeted reservoir interval. The lower portion of the well was continuously cored from 606??m (1987??ft) to 760??m (2494??ft) and drilled to a total depth of 914??m. Ice-bearing permafrost extends to a depth of roughly 536??m and the base of gas hydrate stability is interpreted to extend to a depth of 870??m. Coring through the targeted gas hydrate bearing reservoirs was completed using a wireline-retrievable system. The coring program achieved 85% recovery of 7.6??cm (3??in) diameter core through 154??m (504??ft) of the hole. An onsite team processed the cores, collecting and preserving approximately 250 sub-samples for analyses of pore water geochemistry, microbiology, gas chemistry, petrophysical analysis, and thermal and physical properties. Eleven samples were immediately transferred to either methane-charged pressure vessels or liquid nitrogen for future study of the preserved gas hydrate. Additional offsite sampling, analyses, and detailed description of the cores were also conducted. Based on this work, one lithostratigraphic unit with eight subunits was identified across the cored interval. Subunits II and Va comprise the majority of the reservoir facies and are dominantly very fine to fine, moderately sorted, quartz, feldspar, and lithic fragment-bearing to

  18. Heave Compensation Evaluation and Formation Strength Estimation from Drill String Acceleration Measurements While Coring

    Science.gov (United States)

    Guerin, G.; Goldberg, D.; Meltser, A.

    2001-05-01

    One of the recurring challenges in deep-sea drilling has been to maintain a precise control of coring depths, and to limit the influence of surface heave on drill bit motion. Operating in water depths between 1 and 6 km, the Ocean Drilling Program has relied on a drill string heave compensator to collect more than 200 km of cores, with maximum penetration of 2km. To evaluate the efficiency of the heave compensation, a device was developed to measure downhole acceleration from the top of the core barrel. This probe records three-axis acceleration and pressure at up to 100 samples per second. The first deployments of this instrument on ODP Legs 185 and 191 show that the heave compensator limits the bit motion to about 10% of the surface heave. This device could prove most useful to monitor heave compensation on shallow water drilling platforms where heave is a primary concern. The high-resolution downhole acceleration data can also be used to determine some of the mechanical properties of the formation. When deployed on piston cores, a maximum vertical acceleration of up to 3G is recorded as the coring shoe penetrates the formation. This maximum value is characteristic of the sediment strength and its degree of consolidation and can be used to identify formations that are typically difficult to recover, such as hard layers or hydrate-bearing sediments. With rotary coring, downhole acceleration signals decrease in magnitude and frequency content with the increasing hardness of the formation. High amplitude is observed in uncompacted sediments and low amplitudes in low-porosity oceanic basalt. Comparison between acceleration records and geophysical logs show that this relationship can be observed at a dm-scale within an individual core. Easy to deploy and adding almost no time to coring operations, the downhole accelerometer tool offers a way to characterize formations continuously while coring, which is particularly useful in the event of poor core recovery.

  19. Investigation of MA Content Effect on Kinetic Parameter in ADS Core%MA 含量对 ADS 堆芯动力学参数的影响研究

    Institute of Scientific and Technical Information of China (English)

    罗润; 宋洪兵; 赵福宇

    2016-01-01

    The effective delayed neutron fraction (βef ),mean neutron generation time (Λ)and reactivity feedback coefficient (α)are the most important parameters in nuclear reactor kinetics.In this study,Monte Carlo method was applied to calculate the kinetic parameters of accelerator driven sub-critical system (ADS)cores,and the effect of mi-nor actinides (MA)content on these parameters was analyzed.The different contents of MA in the fuel were investigated to determine its effect on the kinetic parameters.The results show that when the content of MA reaches 5% in the fuel,theβef andΛ decrease by about 18% and 31%,respectively.With the increase of MA content from 0% to 5%,the average value of Doppler feedback coefficientαD varies from -0.56 pcm/K to-0.36 pcm/K,and the average value of coolant feedback coefficient αC varies from-2.1 1 pcm/K to -1.73 pcm/K.%有效缓发中子份额(βef )、平均中子代时间(Λ)和反应性反馈系数(α)是核反应堆动力学中至关重要的参数。本文采用蒙特卡罗方法计算了加速器驱动的次临界系统(ADS)堆芯的动力学参数,并分析了次锕系核素(MA)装载量对这些参数的影响。通过在燃料中添加不同含量的 MA,来研究其对 ADS堆芯动力学参数的影响。结果表明,当 MA 在燃料中的含量从0%增加到5%时,βef 和Λ的值分别降低了18%和31%,多普勒反馈系数平均值αD 由-0.56 pcm/K 变化到-0.36 pcm/K,冷却剂反馈系数平均值αC 由-2.11 pcm/K变化到-1.73 pcm/K。

  20. The key to the extraordinary thermal stability of P. furiosus holo-rubredoxin: iron binding-guided packing of a core aromatic cluster responsible for high kinetic stability of the native structure.

    Science.gov (United States)

    Prakash, Satya; Sundd, Monica; Guptasarma, Purnananda

    2014-01-01

    Pyrococcus furiosus rubredoxin (PfRd), a small, monomeric, 53 residues-long, iron-containing, electron-transfer protein of known structure is sometimes referred to as being the most structurally-stable protein known to man. Here, using a combination of mutational and spectroscopic (CD, fluorescence, and NMR) studies of differently made holo- and apo-forms of PfRd, we demonstrate that it is not the presence of iron, or even the folding of the PfRd chain into a compact well-folded structure that causes holo-PfRd to display its extraordinary thermal stability, but rather the correct iron binding-guided packing of certain residues (specifically, Trp3, Phe29, Trp36, and also Tyr10) within a tight aromatic cluster of six residues in PfRd's hydrophobic core. Binding of the iron atom appears to play a remarkable role in determining subtle details of residue packing, forcing the chain to form a hyper-thermally stable native structure which is kinetically stable enough to survive (subsequent) removal of iron. On the other hand, failure to bind iron causes the same chain to adopt an equally well-folded native-like structure which, however, has a differently-packed aromatic cluster in its core, causing it to be only as stable as any other ordinary mesophile-derived rubredoxin. Our studies demonstrate, perhaps for the very first time ever that hyperthermal stability in proteins can owe to subtle differences in residue packing vis a vis mesostable proteins, without there being any underlying differences in either amino acid sequence, or bound ligand status.

  1. Kinetic Atom.

    Science.gov (United States)

    Wilson, David B.

    1981-01-01

    Surveys the research of scientists like Joule, Kelvin, Maxwell, Clausius, and Boltzmann as it comments on the basic conceptual issues involved in the development of a more precise kinetic theory and the idea of a kinetic atom. (Author/SK)

  2. Kinetic Typography

    DEFF Research Database (Denmark)

    van Leeuwen, Theo; Djonov, Emilia

    2014-01-01

    After discussing broad cultural drivers behind the development of kinetic typography, the chapter outlines an approach to analysing kinetic typography which is based on Halliday's theory of transitivity, as applied by Kress and Van Leeuwen to visual images.......After discussing broad cultural drivers behind the development of kinetic typography, the chapter outlines an approach to analysing kinetic typography which is based on Halliday's theory of transitivity, as applied by Kress and Van Leeuwen to visual images....

  3. Proteomics Core

    Data.gov (United States)

    Federal Laboratory Consortium — Proteomics Core is the central resource for mass spectrometry based proteomics within the NHLBI. The Core staff help collaborators design proteomics experiments in a...

  4. Proteomics Core

    Data.gov (United States)

    Federal Laboratory Consortium — Proteomics Core is the central resource for mass spectrometry based proteomics within the NHLBI. The Core staff help collaborators design proteomics experiments in...

  5. ALCHEMIC: Advanced time-dependent chemical kinetics

    Science.gov (United States)

    Semenov, Dmitry A.

    2017-08-01

    ALCHEMIC solves chemical kinetics problems, including gas-grain interactions, surface reactions, deuterium fractionization, and transport phenomena and can model the time-dependent chemical evolution of molecular clouds, hot cores, corinos, and protoplanetary disks.

  6. Ice cores

    DEFF Research Database (Denmark)

    Svensson, Anders

    2014-01-01

    Ice cores from Antarctica, from Greenland, and from a number of smaller glaciers around the world yield a wealth of information on past climates and environments. Ice cores offer unique records on past temperatures, atmospheric composition (including greenhouse gases), volcanism, solar activity......, dustiness, and biomass burning, among others. In Antarctica, ice cores extend back more than 800,000 years before present (Jouzel et al. 2007), whereas. Greenland ice cores cover the last 130,000 years...

  7. Ice cores

    DEFF Research Database (Denmark)

    Svensson, Anders

    2014-01-01

    Ice cores from Antarctica, from Greenland, and from a number of smaller glaciers around the world yield a wealth of information on past climates and environments. Ice cores offer unique records on past temperatures, atmospheric composition (including greenhouse gases), volcanism, solar activity......, dustiness, and biomass burning, among others. In Antarctica, ice cores extend back more than 800,000 years before present (Jouzel et al. 2007), whereas. Greenland ice cores cover the last 130,000 years...

  8. Characterization of gas hydrate reservoirs by integration of core and log data in the Ulleung Basin, East Sea

    Science.gov (United States)

    Bahk, J.-J.; Kim, G.-Y.; Chun, J.-H.; Kim, J.-H.; Lee, J.Y.; Ryu, B.-J.; Lee, J.-H.; Son, B.-K.; Collett, Timothy S.

    2013-01-01

    Examinations of core and well-log data from the Second Ulleung Basin Gas Hydrate Drilling Expedition (UBGH2) drill sites suggest that Sites UBGH2-2_2 and UBGH2-6 have relatively good gas hydrate reservoir quality in terms of individual and total cumulative thicknesses of gas-hydrate-bearing sand (HYBS) beds. In both of the sites, core sediments are generally dominated by hemipelagic muds which are intercalated with turbidite sands. The turbidite sands are usually thin-to-medium bedded and mainly consist of well sorted coarse silt to fine sand. Anomalies in infrared core temperatures and porewater chlorinity data and pressure core measurements indicate that “gas hydrate occurrence zones” (GHOZ) are present about 68–155 mbsf at Site UBGH2-2_2 and 110–155 mbsf at Site UBGH2-6. In both the GHOZ, gas hydrates are preferentially associated with many of the turbidite sands as “pore-filling” type hydrates. The HYBS identified in the cores from Site UBGH2-6 are medium-to-thick bedded particularly in the lower part of the GHOZ and well coincident with significant high excursions in all of the resistivity, density, and velocity logs. Gas-hydrate saturations in the HYBS range from 12% to 79% with an average of 52% based on pore-water chlorinity. In contrast, the HYBS from Site UBGH2-2_2 are usually thin-bedded and show poor correlations with both of the resistivity and velocity logs owing to volume averaging effects of the logging tools on the thin HYBS beds. Gas-hydrate saturations in the HYBS range from 15% to 65% with an average of 37% based on pore-water chlorinity. In both of the sites, large fluctuations in biogenic opal contents have significant effects on the sediment physical properties, resulting in limited usage of gamma ray and density logs in discriminating sand reservoirs.

  9. Kinetic Interface

    DEFF Research Database (Denmark)

    2009-01-01

    A kinetic interface for orientation detection in a video training system is disclosed. The interface includes a balance platform instrumented with inertial motion sensors. The interface engages a participant's sense of balance in training exercises.......A kinetic interface for orientation detection in a video training system is disclosed. The interface includes a balance platform instrumented with inertial motion sensors. The interface engages a participant's sense of balance in training exercises....

  10. Kinetics and

    Directory of Open Access Journals (Sweden)

    Mojtaba Ahmadi

    2016-11-01

    Full Text Available The aqueous degradation of Reactive Yellow 84 (RY84 by potassium peroxydisulfate (K2S2O8 has been studied in laboratory scale experiments. The effect of the initial concentrations of potassium peroxydisulfate and RY84, pH and temperature on RY84 degradation were also examined. Experimental data were analyzed using first and second-order kinetics. The degradation kinetics of RY84 of the potassium peroxydisulfate process followed the second-order reaction kinetics. These rate constants have an extreme values similar to of 9.493 mM−1min−1 at a peroxydisulfate dose of 4 mmol/L. Thermodynamic parameters such as activation (Ea and Gibbs free energy (ΔG° were also evaluated. The negative value of ΔGo and Ea shows the spontaneous reaction natural conditions and exothermic nature.

  11. Transformer core

    NARCIS (Netherlands)

    Mehendale, A.; Hagedoorn, Wouter; Lötters, Joost Conrad

    2010-01-01

    A transformer core includes a stack of a plurality of planar core plates of a magnetically permeable material, which plates each consist of a first and a second sub-part that together enclose at least one opening. The sub-parts can be fitted together via contact faces that are located on either side

  12. Transformer core

    NARCIS (Netherlands)

    Mehendale, A.; Hagedoorn, Wouter; Lötters, Joost Conrad

    2008-01-01

    A transformer core includes a stack of a plurality of planar core plates of a magnetically permeable material, which plates each consist of a first and a second sub-part that together enclose at least one opening. The sub-parts can be fitted together via contact faces that are located on either side

  13. Ice Cores

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Records of past temperature, precipitation, atmospheric trace gases, and other aspects of climate and environment derived from ice cores drilled on glaciers and ice...

  14. Core BPEL

    DEFF Research Database (Denmark)

    Hallwyl, Tim; Højsgaard, Espen

    extensions. Combined with the fact that the language definition does not provide a formal semantics, it is an arduous task to work formally with the language (e.g. to give an implementation). In this paper we identify a core subset of the language, called Core BPEL, which has fewer and simpler constructs......, does not allow omissions, and does not contain ignorable elements. We do so by identifying syntactic sugar, including default values, and ignorable elements in WS-BPEL. The analysis results in a translation from the full language to the core subset. Thus, we reduce the effort needed for working...... formally with WS-BPEL, as one, without loss of generality, need only consider the much simpler Core BPEL. This report may also be viewed as an addendum to the WS-BPEL standard specification, which clarifies the WS-BPEL syntax and presents the essential elements of the language in a more concise way...

  15. Core BPEL

    DEFF Research Database (Denmark)

    Hallwyl, Tim; Højsgaard, Espen

    extensions. Combined with the fact that the language definition does not provide a formal semantics, it is an arduous task to work formally with the language (e.g. to give an implementation). In this paper we identify a core subset of the language, called Core BPEL, which has fewer and simpler constructs......, does not allow omissions, and does not contain ignorable elements. We do so by identifying syntactic sugar, including default values, and ignorable elements in WS-BPEL. The analysis results in a translation from the full language to the core subset. Thus, we reduce the effort needed for working...... formally with WS-BPEL, as one, without loss of generality, need only consider the much simpler Core BPEL. This report may also be viewed as an addendum to the WS-BPEL standard specification, which clarifies the WS-BPEL syntax and presents the essential elements of the language in a more concise way...

  16. Core benefits

    National Research Council Canada - National Science Library

    Keith, Brian W

    2010-01-01

    This SPEC Kit explores the core employment benefits of retirement, and life, health, and other insurance -benefits that are typically decided by the parent institution and often have significant governmental regulation...

  17. Physisorption kinetics

    CERN Document Server

    Kreuzer, Hans Jürgen

    1986-01-01

    This monograph deals with the kinetics of adsorption and desorption of molecules physisorbed on solid surfaces. Although frequent and detailed reference is made to experiment, it is mainly concerned with the theory of the subject. In this, we have attempted to present a unified picture based on the master equation approach. Physisorption kinetics is by no means a closed and mature subject; rather, in writing this monograph we intended to survey a field very much in flux, to assess its achievements so far, and to give a reasonable basis from which further developments can take off. For this reason we have included many papers in the bibliography that are not referred to in the text but are of relevance to physisorption. To keep this monograph to a reasonable size, and also to allow for some unity in the presentation of the material, we had to omit a number of topics related to physisorption kinetics. We have not covered to any extent the equilibrium properties of physisorbed layers such as structures, phase tr...

  18. Kinetic Biochemistry

    Directory of Open Access Journals (Sweden)

    Lorentz JÄNTSCHI

    2003-03-01

    Full Text Available Mathematics and computer programming have a major contribution to chemistry. Two directions can be identified: one that searches and tries (rich to explain the structural binding and shape of the chemical compounds [1] with major applications in QSPR/QSAR studies [2], and applied sciences such as engineering of materials or agriculture [3]; the second direction is to models the kinetic processes that are involved in chemical reactions [4]. Many such models are available here. The present paper describes three variants of well the known kinetic models and presents the mathematical equations associated with them. The differential equations are numerically solved and fitted with MathCad program. [1] Diudea M., Gutman I., Jäntschi L., Molecular Topology, Nova Science, Huntington, New York, 332 p., 2001, 2002. [2] Diudea M. V., Ed., QSPR / QSAR Studies by Molecular Descriptors, Nova Science, Huntington, New York, 438 p., 2001. [3] Jäntschi L., Microbiology and Toxicology. Phytochemistry Studies (in Romanian, Amici, Cluj-Napoca, 184 p., 2003. [4] Jäntschi L., Unguresan M., Physical Chemistry. Molecular Kinetic and Dynamic (in Romanian, Mediamira, Cluj-Napoca, 159 p., 2001.

  19. Parallelization of Kinetic Theory Simulations

    CERN Document Server

    Howell, Jim; Colbry, Dirk; Pickett, Rodney; Staber, Alec; Sagert, Irina; Strother, Terrance

    2013-01-01

    Numerical studies of shock waves in large scale systems via kinetic simulations with millions of particles are too computationally demanding to be processed in serial. In this work we focus on optimizing the parallel performance of a kinetic Monte Carlo code for astrophysical simulations such as core-collapse supernovae. Our goal is to attain a flexible program that scales well with the architecture of modern supercomputers. This approach requires a hybrid model of programming that combines a message passing interface (MPI) with a multithreading model (OpenMP) in C++. We report on our approach to implement the hybrid design into the kinetic code and show first results which demonstrate a significant gain in performance when many processors are applied.

  20. Characterizing electrical properties and permeability changes of hydrate bearing sediments using ERT data

    Science.gov (United States)

    Priegnitz, Mike; Thaler, Jan; Spangenberg, Erik; Schicks, Judith M.; Schrötter, Jörg; Abendroth, Sven

    2015-09-01

    A LArge Reservoir Simulator (LARS) was equipped with an electrical resistivity tomography (ERT) array to monitor hydrate formation and dissociation experiments. During two hydrate formation experiments reaching 90 per cent bulk hydrate saturation, frequent measurements of the electrical properties within the sediment sample were performed. Subsequently, several common mixing rules, including two different interpretations of Archie's law, were tested to convert the obtained distribution of the electrical resistivity into the spatial distribution of local hydrate saturation. It turned out that the best results estimating values of local hydrate saturation were obtained using the Archievar-phi approach where the increasing hydrate phase is interpreted as part of the sediment grain framework reducing the sample's porosity. These values of local hydrate saturation were used to determine local permeabilities by applying the Carman-Kozeny relation. The formed hydrates were dissociated via depressurization. The decomposition onset as well as areas featuring hydrates and free gas were inferred from the ERT results. Supplemental consideration of temperature and pressure data granted information on discrete areas of hydrate dissociation.

  1. Polyethylene Glycol Drilling Fluid for Drilling in Marine Gas Hydrates-Bearing Sediments: An Experimental Study

    OpenAIRE

    Lixin Kuang; Yibing Yu; Yunzhong Tu; Ling Zhang; Fulong Ning; Guosheng Jiang; Tianle Liu

    2011-01-01

    Shale inhibition, low-temperature performance, the ability to prevent calcium and magnesium-ion pollution, and hydrate inhibition of polyethylene glycol drilling fluid were each tested with conventional drilling-fluid test equipment and an experimental gas-hydrate integrated simulation system developed by our laboratory. The results of these tests show that drilling fluid with a formulation of artificial seawater, 3% bentonite, 0.3% Na 2 CO 3 , 10% polyethylene glycol, 20% NaCl, 4% SMP-2, 1% ...

  2. Elastic velocity models for gas-hydrate-bearing sediments-a comparison

    Science.gov (United States)

    Chand, Shyam; Minshull, Tim A.; Gei, Davide; Carcione, José M.

    2004-11-01

    The presence of gas hydrate in oceanic sediments is mostly identified by bottom-simulating reflectors (BSRs), reflection events with reversed polarity following the trend of the seafloor. Attempts to quantify the amount of gas hydrate present in oceanic sediments have been based mainly on the presence or absence of a BSR and its relative amplitude. Recent studies have shown that a BSR is not a necessary criterion for the presence of gas hydrates, but rather its presence depends on the type of sediments and the in situ conditions. The influence of hydrate on the physical properties of sediments overlying the BSR is determined by the elastic properties of their constituents and on sediment microstructure. In this context several approaches have been developed to predict the physical properties of sediments, and thereby quantify the amount of gas/gas hydrate present from observed deviations of these properties from those predicted for sediments without gas hydrate. We tested four models: the empirical weighted equation (WE); the three-phase effective-medium theory (TPEM); the three-phase Biot theory (TPB) and the differential effective-medium theory (DEM). We compared these models for a range of variables (porosity and clay content) using standard values for physical parameters. The comparison shows that all the models predict sediment properties comparable to field values except for the WE model at lower porosities and the TPB model at higher porosities. The models differ in the variation of velocity with porosity and clay content. The variation of velocity with hydrate saturation is also different, although the range is similar. We have used these models to predict velocities for field data sets from sediment sections with and without gas hydrates. The first is from the Mallik 2L-38 well, Mackenzie Delta, Canada, and the second is from Ocean Drilling Program (ODP) Leg 164 on Blake Ridge. Both data sets have Vp and Vs information along with the composition and porosity of the matrix. Models are considered successful if predictions from both Vp and Vs match hydrate saturations inferred from other data. Three of the models predict consistent hydrate saturations of 60-80 per cent from both Vp and Vs from log and vertical seismic profiling data for the Mallik 2L-38 well data set, but the TPEM model predicts 20 per cent higher saturations, as does the DEM model with a clay-water starting medium. For the clay-rich sediments of Blake Ridge, the DEM, TPEM and WE models predict 10-20 per cent hydrate saturation from Vp data, comparable to that inferred from resistivity data. The hydrate saturation predicted by the TPB model from Vp is higher. Using Vs data, the DEM and TPEM models predict very low or zero hydrate saturation while the TPB and WE models predict hydrate saturation very much higher than those predicted from Vp data. Low hydrate saturations are observed to have little effect on Vs. The hydrate phase appears to be connected within the sediment microstructure even at low saturations.

  3. Impact of Residual Water on CH4-CO2 Exchange rate in Hydrate bearing Sandstone

    Science.gov (United States)

    Ersland, G.; Birkedal, K.; Graue, A.

    2012-12-01

    It is previously shown that sequestration of CO2 in natural gas hydrate reservoirs may offer stable long term deposition of a greenhouse gas while benefiting from methane production, without adding heat to the process. In this work CH4 hydrate formation and CO2 reformation in sandstone has been quantified in a series of experiments using Magnetic Resonance Imaging. The overall objective was to provide an improved basic understanding of processes involved in formation and production of methane from methane hydrates within porous media, and to provide data for numerical modeling and scaling. CH4 hydrate has been formed repeatedly in Bentheim sandstone rocks to study hydrate growth patterns for various brine salinities and saturations to prepare for subsequent lab-scale methane production tests through carbon dioxide replacement at various residual water saturations. Surface area for CO2 exposure and the role of permeability and diffusion on the CH4-CO2 exchange rate will also be discussed.

  4. Water Retention Curve and Relative Permeability for Gas Production from Hydrate-Bearing Sediments

    Science.gov (United States)

    Mahabadi, N.; Dai, S.; Seol, Y.; Jang, J.

    2014-12-01

    Water retention curve (soil water characteristic curve SWCC) and relative permeability equations are important to determine gas and water production for gas hydrate development. However, experimental studies to determine fitting parameters of those equations are not available in the literature. The objective of this research is to obtain reliable parameters for capillary pressure functions and relative permeability equations applicable to hydrate dissociation and gas production. In order to achieve this goal, (1) micro X-ray Computer Tomography (CT) is used to scan the specimen under 10MPa effective stress, (2) a pore network model is extracted from the CT image, (3) hydrate dissociation and gas expansion are simulated in the pore network model, (4) the parameters for the van Genuchten-type soil water characteristic curve and relative permeability equation during gas expansion are suggested. The research outcome will enhance the ability of numerical simulators to predict gas and water production rate.

  5. Electrical anisotropy of gas hydrate-bearing sand reservoirs in the Gulf of Mexico

    Science.gov (United States)

    Cook, Anne E.; Anderson, Barbara I.; Rasmus, John; Sun, Keli; Li, Qiming; Collett, Timothy S.; Goldberg, David S.

    2012-01-01

    We present new results and interpretations of the electricalanisotropy and reservoir architecture in gashydrate-bearingsands using logging data collected during the Gulf of MexicoGasHydrate Joint Industry Project Leg II. We focus specifically on sandreservoirs in Hole Alaminos Canyon 21 A (AC21-A), Hole Green Canyon 955 H (GC955-H) and Hole Walker Ridge 313 H (WR313-H). Using a new logging-while-drilling directional resistivity tool and a one-dimensional inversion developed by Schlumberger, we resolve the resistivity of the current flowing parallel to the bedding, R| and the resistivity of the current flowing perpendicular to the bedding, R|. We find the sandreservoir in Hole AC21-A to be relatively isotropic, with R| and R| values close to 2 Ω m. In contrast, the gashydrate-bearingsandreservoirs in Holes GC955-H and WR313-H are highly anisotropic. In these reservoirs, R| is between 2 and 30 Ω m, and R| is generally an order of magnitude higher. Using Schlumberger's WebMI models, we were able to replicate multiple resistivity measurements and determine the formation resistivity the gashydrate-bearingsandreservoir in Hole WR313-H. The results showed that gashydrate saturations within a single reservoir unit are highly variable. For example, the sand units in Hole WR313-H contain thin layers (on the order of 10-100 cm) with varying gashydrate saturations between 15 and 95%. Our combined modeling results clearly indicate that the gashydrate-bearingsandreservoirs in Holes GC955-H and WR313-H are highly anisotropic due to varying saturations of gashydrate forming in thin layers within larger sand units.

  6. Methane sources in gas hydrate-bearing cold seeps: Evidence from radiocarbon and stable isotopes

    Science.gov (United States)

    Pohlman, J.W.; Bauer, J.E.; Canuel, E.A.; Grabowski, K.S.; Knies, D.L.; Mitchell, C.S.; Whiticar, Michael J.; Coffin, R.B.

    2009-01-01

    Fossil methane from the large and dynamic marine gas hydrate reservoir has the potential to influence oceanic and atmospheric carbon pools. However, natural radiocarbon (14C) measurements of gas hydrate methane have been extremely limited, and their use as a source and process indicator has not yet been systematically established. In this study, gas hydrate-bound and dissolved methane recovered from six geologically and geographically distinct high-gas-flux cold seeps was found to be 98 to 100% fossil based on its 14C content. Given this prevalence of fossil methane and the small contribution of gas hydrate (??? 1%) to the present-day atmospheric methane flux, non-fossil contributions of gas hydrate methane to the atmosphere are not likely to be quantitatively significant. This conclusion is consistent with contemporary atmospheric methane budget calculations. In combination with ??13C- and ??D-methane measurements, we also determine the extent to which the low, but detectable, amounts of 14C (~ 1-2% modern carbon, pMC) in methane from two cold seeps might reflect in situ production from near-seafloor sediment organic carbon (SOC). A 14C mass balance approach using fossil methane and 14C-enriched SOC suggests that as much as 8 to 29% of hydrate-associated methane carbon may originate from SOC contained within the upper 6??m of sediment. These findings validate the assumption of a predominantly fossil carbon source for marine gas hydrate, but also indicate that structural gas hydrate from at least certain cold seeps contains a component of methane produced during decomposition of non-fossil organic matter in near-surface sediment.

  7. Buprenorphine kinetics.

    Science.gov (United States)

    Bullingham, R E; McQuay, H J; Moore, A; Bennett, M R

    1980-11-01

    Buprenorphine kinetics was determined in surgical patients using radioimmunoassay. Buprenorphine was measured in the plasma of 24 patients who had received 0.3 mg buprenorphine intraoperatively. After 3 hr 10 of these patients then received a further 0.3 mg buprenorphine intravenously for postoperative pain relief, and 11 patients were given 0.3 mg intramuscularly; again, plasma levels were measured for 3 hr. The data fitted closely to a triexponential decay curve. There was a very fast initial phase, with a half-life (t1/2) of 2 min. The terminal t1/2 was slow, approximately 3 hr. Comparison of the kinetics of the same patient, awake and anesthetized, showed that the clearance was significantly lower in the anesthetized state. A notable feature of the drug given intramuscularly is rapid systemic availability, so that peaks are obtained in 2 to 5 min, and in 10 min the resulting levels are the same as for the intravenous and intramuscular routes.

  8. Kinetic buffers.

    Science.gov (United States)

    Alibrandi, Giuseppe; Fabbrizzi, Luigi; Licchelli, Maurizio; Puglisi, Antonio

    2015-01-12

    This paper proposes a new type of molecular device that is able to act as an inverse proton sponge to slowly decrease the pH inside a reaction vessel. This makes the automatic monitoring of the concentration of pH-sensitive systems possible. The device is a composite formed of an alkyl chloride, which kinetically produces acidity, and a buffer that thermodynamically modulates the variation in pH value. Profiles of pH versus time (pH-t plots) have been generated under various experimental conditions by computer simulation, and the device has been tested by carrying out automatic spectrophotometric titrations, without using an autoburette. To underline the wide variety of possible applications, this new system has been used to realize and monitor HCl uptake by a di-copper(II) bistren complex in a single run, in a completely automatic experiment. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Core Java

    CERN Document Server

    Horstmann, Cay S

    2013-01-01

    Fully updated to reflect Java SE 7 language changes, Core Java™, Volume I—Fundamentals, Ninth Edition, is the definitive guide to the Java platform. Designed for serious programmers, this reliable, unbiased, no-nonsense tutorial illuminates key Java language and library features with thoroughly tested code examples. As in previous editions, all code is easy to understand, reflects modern best practices, and is specifically designed to help jumpstart your projects. Volume I quickly brings you up-to-speed on Java SE 7 core language enhancements, including the diamond operator, improved resource handling, and catching of multiple exceptions. All of the code examples have been updated to reflect these enhancements, and complete descriptions of new SE 7 features are integrated with insightful explanations of fundamental Java concepts.

  10. Understanding Chemical Reaction Kinetics and Equilibrium with Interlocking Building Blocks

    Science.gov (United States)

    Cloonan, Carrie A.; Nichol, Carolyn A.; Hutchinson, John S.

    2011-01-01

    Chemical reaction kinetics and equilibrium are essential core concepts of chemistry but are challenging topics for many students, both at the high school and undergraduate university level. Visualization at the molecular level is valuable to aid understanding of reaction kinetics and equilibrium. This activity provides a discovery-based method to…

  11. Kinetic chain abnormalities in the athletic shoulder.

    Science.gov (United States)

    Sciascia, Aaron; Thigpen, Charles; Namdari, Surena; Baldwin, Keith

    2012-03-01

    Overhead activities require the shoulder to be exposed to and sustain repetitive loads. The segmental activation of the body's links, known as the kinetic chain, allows this to occur effectively. Proper muscle activation is achieved through generation of energy from the central segment or core, which then transfers the energy to the terminal links of the shoulder, elbow, and hand. The kinetic chain is best characterized by 3 components: optimized anatomy, reproducible efficient motor patterns, and the sequential generation of forces. However, tissue injury and anatomic deficits such as weakness and/or tightness in the leg, pelvic core, or scapular musculature can lead to overuse shoulder injuries. These injuries can be prevented and maladaptations can be detected with a thorough understanding of biomechanics of the kinetic chain as it relates to overhead activity.

  12. Influence of core sand properties on flow dynamics of core shooting process based on experiment and multiphase simulation

    Directory of Open Access Journals (Sweden)

    Chang-jiang Ni

    2017-03-01

    Full Text Available The influence of core sand properties on flow dynamics was investigated synchronously with various core sands, transparent core-box and high-speed camera. To confirm whether the core shooting process has significant turbulence, the flow pattern of sand particles in the shooting head and core box was reproduced with colored core sands. By incorporating the kinetic theory of granular flow (KTGF, kinetic-frictional constitutive correlation and turbulence model, a two-fluid model (TFM was established to study the flow dynamics of the core shooting process. Two-fluid model (TFM simulations were then performed and a areasonable agreement was achieved between the simulation and experimental results. Based on the experimental and simulation results, the effects of turbulence, sand density, sand diameter and binder ratio were analyzed in terms of filling process, sand volume fraction (αs and sand velocity (Vs.

  13. Magnetic Probing of Core Geodynamics

    Science.gov (United States)

    Voorhies, Coerte V.

    2004-01-01

    To better understand geomagnetic theory and observation, we can use spatial magnetic spectra for the main field and secular variation to test core dynmcal hypotheses against seismology. The hypotheses lead to theoretical spectra which are fitted to observational spectra. Each fit yields an estimate of the radius of Earth's core and uncertainty. If this agrees with the seismologic value, then the hypothes pass the test. A new way to obtain theoretical spectra extends the hydromagnetic scale analysis of Benton to scale-variant field and flow. For narrow scale flow and a dynamically weak field by the top of Earth's core, this yields a generalized Stevenson-McLeod spectrum for the core-source field, and a secular variation spectrum modulated by a cubic polynomial in spherical harmonic degree n. The former passes the tests. The latter passes many tests, but does not describe rapid dipole decline and quadrupole rebound; some tests suggest it is a bit hard, or rich in narrow scale change. In a core geodynamo, motion of the fluid conductor does work against the Lorentz force. This converts kinetic into magnetic energy which, in turn, is lost to heat via Ohmic dissipation. In the analysis at lentgh-scale l/k, if one presumes kinetic energy is converted in either eddy- overturning or magnetic free-decay time-scales, then Kolmogorov or other spectra in conflict with observational spectra can result. Instead, the rate work is done roughly balances the dissipation rate, which is consistent with small scale flow. The conversion time-scale depends on dynamical constraints. These are summarized by the magneto-geostrophic vertical vorticity balance by the top of the core, which includes anisotropic effects of rotation, the magnetic field, and the core- mantle boundary. The resulting theoretical spectra for the core-source field and its SV are far more compatible with observation. The conversion time-scale of order l20 years is pseudo-scale-invarient. Magnetic spectra of other

  14. Geological & Geophysical findings from seismic, well log and core data for marine gas hydrate deposits at the 1st offshore methane hydrate production test site in the eastern Nankai Trough, offshore Japan: An overview

    Science.gov (United States)

    Fujii, T.; Noguchi, S.; Takayama, T.; Suzuki, K.; Yamamoto, K.

    2012-12-01

    In order to evaluate productivity of gas from marine gas hydrate by the depressurization method, Japan Oil, Gas and Metals National Corporation is planning to conduct a full-scale production test in early 2013 at the AT1 site in the north slope of Daini-Atsumi Knoll in the eastern Nankai Trough, Japan. The test location was determined using the combination of detailed 3D seismic reflection pattern analysis, high-density velocity analysis, and P-impedance inversion analysis, which were calibrated using well log data obtained in 2004. At the AT1 site, one production well (AT1-P) and two monitoring wells (AT1-MC and MT1) were drilled from February to March 2012, followed by 1 coring well (AT1-C) from June to July 2012. An extensive logging program with logging while drilling (LWD) and wireline-logging tools, such as GeoVISION (resistivity image), EcoScope (neutron/density porosity, mineral spectroscopy etc.), SonicScanner (Advanced Sonic tool), CMR/ProVISION (Nuclear Magnetic Resonance Tools), XPT (formation pressure, fluid mobility), and IsolationScanner (ultrasonic cement evaluation tools) was conducted at AT1-MC well to evaluate physical reservoir properties of gas hydrate-bearing sediments, to determine production test interval in 2013, and to evaluate cement bonding. Methane hydrate concentrated zone (MHCZ) confirmed by the well logging at AT1-MC was thin turbidites (tens of centimeters to few meters) with 60 m of gross thickness, which is composed of lobe type sequences in the upper part of it and channel sand sequences in the lower part. The gross thickness of MHCZ in the well is thicker than previous wells in 2004 (A1, 45 m) located around 150 m northeast, indicating that the prediction given by seismic inversion analysis was reasonable. Well-to-well correlation between AT1-MC and MT1 wells within 40 m distance exhibited that lateral continuity of these sand layers (upper part of reservoir) are fairly good, which representing ideal reservoir for the production

  15. Kinetic modeling of exciton migration in photosynthetic systems. 3. Application of genetic algorithms to simulations of excitation dynamics in three-dimensional photosystem I core antenna/reaction center complexes.

    Science.gov (United States)

    Trinkunas, G; Holzwarth, A R

    1996-07-01

    A procedure is described to generate and optimize the lattice models for spectrally inhomogeneous photosynthetic antenna/reaction center (RC) particles. It is based on the genetic algorithm search for the pigment spectral type distributions on the lattice by making use of steady-state and time-resolved spectroscopic input data. Upon a proper fitness definition, a family of excitation energy transfer models can be tested for their compatibility with the availability experimental data. For the case of the photosystem I core antenna (99 chlorophyll + primary electron donor pigment (P700)), three spectrally inhomogeneous three-dimensional lattice models, differing in their excitation transfer conditions, were tested. The relevant fit parameters were the pigment distribution on the lattice, the average lattice spacing of the main pool pigments, the distance of P700 and of long wavelength-absorbing (LWA) pigments to their nearest-neighbor main pool pigments, and the rate constant of charge separation from P700. For cyanobacterial PS I antenna/RC particles containing a substantial amount of LWA pigments, it is shown that the currently available experimental fluorescence data are consistent both with more migration-limited, and with more trap-limited excitation energy transfer models. A final decision between these different models requires more detailed experimental data. From all search runs about 30 different relative arrangements of P700 and LWA pigments were found. Several general features of all these different models can be noticed: 1) The reddest LWA pigment never appears next to P700. 2) The LWA pigments in most cases are spread on the surface of the lattice not far away from P700, with a pronounced tendency toward clustering of the LWA pigments. 3) The rate constant kP700 of charge separation is substantially higher than 1.2 ps-1, i.e., it exceeds the corresponding rate constant of purple bacterial RCs by at least a factor of four. 4) The excitation transfer

  16. A comparative study of kinetics of nuclear reactors

    Directory of Open Access Journals (Sweden)

    Obaidurrahman Khalilurrahman

    2009-01-01

    Full Text Available The paper deals with the study of reactivity initiated transients to investigate major differences in the kinetics behavior of various reactor systems under different operating conditions. The article also states guidelines to determine the safety limits on reactivity insertion rates. Three systems, light water reactors (pressurized water reactors, heavy water reactors (pressurized heavy water reactors, and fast breeder reactors are considered for the sake of analysis. The upper safe limits for reactivity insertion rate in these reactor systems are determined. The analyses of transients are performed by a point kinetics computer code, PKOK. A simple but accurate method for accounting total reactivity feedback in kinetics calculations is suggested and used. Parameters governing the kinetics behavior of the core are studied under different core states. A few guidelines are discussed to project the possible kinetics trends in the next generation reactors.

  17. Magnectic Probing of Core Geodynamics

    Science.gov (United States)

    Voorhies, Coerte

    2004-01-01

    To better understand geomagnetic theory and observation, we can use spatial magnetic spectra for the main field and secular variation to test core dynamical hypotheses against seismology. The hypotheses lead to theoretical spectra which are fitted to observational spectra. Each fit yields an estimate of the radius of Earth s core and uncertainty. If this agrees with the seismologic value, then the hypotheses pass the test. A new way to obtain theoretical spectra extends the hydromagnetic scale analysis of Benton to scale-variant field and flow. For narrow scale flow and a dynamically weak field by the top of Earth s core, this yields a JGR-PI, and a secular variation spectrum modulated by a cubic polynomial in spherical harmonic degree n. The former passes the tests. The latter passes many tests, but does not describe rapid dipole decline and quadrupole rebound; some tests suggest it is a bit hard, or rich in narrow scale change.In a core geodynamo, motion of the fluid conductor does work against the Lorentz force. This converts kinetic into magnetic energy which, in turn, is lost to heat via Ohmic dissipation. In the analysis at length- scale l/k, if one presumes kinetic energy is converted in either eddy- overturning or magnetic free-decay time-scales, then Kolmogorov or other spectra in conflict with observational spectra can result. Instead, the rate work is done roughly balances the dissipation rate, which is consistent with small scale flow. The conversion time-scale depends on dynamical constraints. These are summarized by the magneto- geostrophic vertical vorticity balance by the top of the core, which includes anisotropic effects of rotation, the magnetic field, and the core-mantle boundary. The resulting theoretical spectra for the core- source field and its SV are far more compatible with observation. The conversion time-scale of order 120 years is pseudo-scale-invariant. Magnetic spectra of other planets may differ; however, if a transition to non

  18. Analysis of the three dimensional core kinetics NESTLE code coupling with the advanced thermo-hydraulic code systems, RELAP5/SCDAPSIM and its application to the Laguna Verde Central reactor; Analisis para el acoplamiento del codigo NESTLE para la cinetica tridimensional del nucleo al codigo avanzado de sistemas termo-hidraulicos, RELAP5/SCDAPSIM y su aplicacion al reactor de la CNLV

    Energy Technology Data Exchange (ETDEWEB)

    Salazar C, J.H.; Nunez C, A. [CNSNS, Dr. Jose Ma. Barragan No. 779, Col. Narvarte, 03020 Mexico D.F. (Mexico); Chavez M, C. [UNAM, Facultad de Ingenieria, DEPFI Campus Morelos (Mexico)]. E-mail: hsalazar22@prodigy.net.mx

    2004-07-01

    The objective of the written present is to propose a methodology for the joining of the codes RELAP5/SCDAPSIM and NESTLE. The development of this joining will be carried out inside a doctoral program of Engineering in Energy with nuclear profile of the Ability of Engineering of the UNAM together with the National Commission of Nuclear Security and Safeguards (CNSNS). The general purpose of this type of developments, is to have tools that are implemented by multiple programs or codes such a that systems or models of the three-dimensional kinetics of the core can be simulated and those of the dynamics of the reactor (water heater-hydraulics). In the past, by limitations for the calculation of the complete answer of both systems, the developed models they were carried out for separate, putting a lot of emphasis in one but neglecting the other one. These methodologies, calls of better estimate, will be good to the nuclear industry to evaluate, with more high grades of detail, the designs of the nuclear power plant (for modifications to those already existent or for new concepts in the designs of advanced reactors), besides analysing events (transitory and have an accident), among other applications. The coupled system was applied to design studies and investigation of the Laguna Verde Nuclear power plant (CNLV). (Author)

  19. Non-Isothermal Kinetics.

    Science.gov (United States)

    Brown, M. E.; Phillpotts, C. A. R.

    1978-01-01

    Discusses the principle of nonisothermal kinetics and some of the factors involved in such reactions, especially when considering the reliability of the kinetic parameters, compared to those of isothermal conditions. (GA)

  20. Core shift effect in blazars

    Science.gov (United States)

    Agarwal, A.; Mohan, P.; Gupta, Alok C.; Mangalam, A.; Volvach, A. E.; Aller, M. F.; Aller, H. D.; Gu, M. F.; Lähteenmäki, A.; Tornikoski, M.; Volvach, L. N.

    2017-07-01

    We studied the pc-scale core shift effect using radio light curves for three blazars, S5 0716+714, 3C 279 and BL Lacertae, which were monitored at five frequencies (ν) between 4.8 and 36.8 GHz using the University of Michigan Radio Astronomical Observatory (UMRAO), the Crimean Astrophysical Observatory (CrAO) and Metsähovi Radio Observatory for over 40 yr. Flares were Gaussian fitted to derive time delays between observed frequencies for each flare (Δt), peak amplitude (A) and their half width. Using A ∝ να, we infer α in the range of -16.67-2.41 and using Δ t ∝ ν ^{1/k_r}, we infer kr ∼ 1, employed in the context of equipartition between magnetic and kinetic energy density for parameter estimation. From the estimated core position offset (Ωrν) and the core radius (rcore), we infer that opacity model may not be valid in all cases. The mean magnetic field strengths at 1 pc (B1) and at the core (Bcore) are in agreement with previous estimates. We apply the magnetically arrested disc model to estimate black hole spins in the range of 0.15-0.9 for these blazars, indicating that the model is consistent with expected accretion mode in such sources. The power-law-shaped power spectral density has slopes -1.3 to -2.3 and is interpreted in terms of multiple shocks or magnetic instabilities.

  1. Dual-core antiresonant hollow core fibers.

    Science.gov (United States)

    Liu, Xuesong; Fan, Zhongwei; Shi, Zhaohui; Ma, Yunfeng; Yu, Jin; Zhang, Jing

    2016-07-25

    In this work, dual-core antiresonant hollow core fibers (AR-HCFs) are numerically demonstrated, based on our knowledge, for the first time. Two fiber structures are proposed. One is a composite of two single-core nested nodeless AR-HCFs, exhibiting low confinement loss and a circular mode profile in each core. The other has a relatively simple structure, with a whole elliptical outer jacket, presenting a uniform and wide transmission band. The modal couplings of the dual-core AR-HCFs rely on a unique mechanism that transfers power through the air. The core separation and the gap between the two cores influence the modal coupling strength. With proper designs, both of the dual-core fibers can have low phase birefringence and short modal coupling lengths of several centimeters.

  2. Methods of nonlinear kinetics

    OpenAIRE

    Gorban, A. N.; Karlin, I.V.

    2003-01-01

    Nonlinear kinetic equations are reviewed for a wide audience of specialists and postgraduate students in physics, mathematical physics, material science, chemical engineering and interdisciplinary research. Contents: The Boltzmann equation, Phenomenology and Quasi-chemical representation of the Boltzmann equation, Kinetic models, Discrete velocity models, Direct simulation, Lattice Gas and Lattice Boltzmann models, Minimal Boltzmann models for flows at low Knudsen number, Other kinetic equati...

  3. Development, validation and application of multi-point kinetics model in RELAP5 for analysis of asymmetric nuclear transients

    Energy Technology Data Exchange (ETDEWEB)

    Pradhan, Santosh K., E-mail: santosh@aerb.gov.in [Nuclear Safety Analysis Division, Atomic Energy Regulatory Board, Mumbai 400094 (India); Obaidurrahman, K. [Nuclear Safety Analysis Division, Atomic Energy Regulatory Board, Mumbai 400094 (India); Iyer, Kannan N. [Department of Mechanical Engineering, IIT Bombay, Mumbai 400076 (India); Gaikwad, Avinash J. [Nuclear Safety Analysis Division, Atomic Energy Regulatory Board, Mumbai 400094 (India)

    2016-04-15

    Highlights: • A multi-point kinetics model is developed for RELAP5 system thermal hydraulics code. • Model is validated against extensive 3D kinetics code. • RELAP5 multi-point kinetics formulation is used to investigate critical break for LOCA in PHWR. - Abstract: Point kinetics approach in system code RELAP5 limits its use for many of the reactivity induced transients, which involve asymmetric core behaviour. Development of fully coupled 3D core kinetics code with system thermal-hydraulics is the ultimate requirement in this regard; however coupling and validation of 3D kinetics module with system code is cumbersome and it also requires access to source code. An intermediate approach with multi-point kinetics is appropriate and relatively easy to implement for analysis of several asymmetric transients for large cores. Multi-point kinetics formulation is based on dividing the entire core into several regions and solving ODEs describing kinetics in each region. These regions are interconnected by spatial coupling coefficients which are estimated from diffusion theory approximation. This model offers an advantage that associated ordinary differential equations (ODEs) governing multi-point kinetics formulation can be solved using numerical methods to the desired level of accuracy and thus allows formulation based on user defined control variables, i.e., without disturbing the source code and hence also avoiding associated coupling issues. Euler's method has been used in the present formulation to solve several coupled ODEs internally at each time step. The results have been verified against inbuilt point-kinetics models of RELAP5 and validated against 3D kinetics code TRIKIN. The model was used to identify the critical break in RIH of a typical large PHWR core. The neutronic asymmetry produced in the core due to the system induced transient was effectively handled by the multi-point kinetics model overcoming the limitation of in-built point kinetics model

  4. Animal MRI Core

    Data.gov (United States)

    Federal Laboratory Consortium — The Animal Magnetic Resonance Imaging (MRI) Core develops and optimizes MRI methods for cardiovascular imaging of mice and rats. The Core provides imaging expertise,...

  5. Kinetics of methane fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y. R.; Hashimoto, A. G.

    1978-01-01

    The kinetics on methane fermentation are described using published data for livestock residue, sewage sludge, and municipal refuse. Methods are presented to determine the kinetic constants and the finally attainable methane production using steady-state methane production data. The effects of temperature, loading rate, and influent substrate concentration on methane fermentation kinetics are discussed. These relationships were used to predict the rate of methane production of a pilot-scale fermentor with excellent results.

  6. Kinetic mean-field theories

    Science.gov (United States)

    Karkheck, John; Stell, George

    1981-08-01

    A kinetic mean-field theory for the evolution of the one-particle distribution function is derived from maximizing the entropy. For a potential with a hard-sphere core plus tail, the resulting theory treats the hard-core part as in the revised Enskog theory. The tail, weighted by the hard-sphere pair distribution function, appears linearly in a mean-field term. The kinetic equation is accompanied by an entropy functional for which an H theorem was proven earlier. The revised Enskog theory is obtained by setting the potential tail to zero, the Vlasov equation is obtained by setting the hard-sphere diameter to zero, and an equation of the Enskog-Vlasov type is obtained by effecting the Kac limit on the potential tail. At equilibrium, the theory yields a radial distribution function that is given by the hard-sphere reference system and thus furnishes through the internal energy a thermodynamic description which is exact to first order in inverse temperature. A second natural route to thermodynamics (from the momentum flux which yields an approximate equation of state) gives somewhat different results; both routes coincide and become exact in the Kac limit. Our theory furnishes a conceptual basis for the association in the heuristically based modified Enskog theory (MET) of the contact value of the radial distribution function with the ''thermal pressure'' since this association follows from our theory (using either route to thermodynamics) and moreover becomes exact in the Kac limit. Our transport theory is readily extended to the general case of a soft repulsive core, e.g., as exhibited by the Lennard-Jones potential, via by-now-standard statistical-mechanical methods involving an effective hard-core potential, thus providing a self-contained statistical-mechanical basis for application to such potentials that is lacking in the standard versions of the MET. We obtain very good agreement with experiment for the thermal conductivity and shear viscosity of several

  7. Introduction to chemical kinetics

    CERN Document Server

    Soustelle, Michel

    2013-01-01

    This book is a progressive presentation of kinetics of the chemical reactions. It provides complete coverage of the domain of chemical kinetics, which is necessary for the various future users in the fields of Chemistry, Physical Chemistry, Materials Science, Chemical Engineering, Macromolecular Chemistry and Combustion. It will help them to understand the most sophisticated knowledge of their future job area. Over 15 chapters, this book present the fundamentals of chemical kinetics, its relations with reaction mechanisms and kinetic properties. Two chapters are then devoted to experimental re

  8. Principles of chemical kinetics

    CERN Document Server

    House, James E

    2007-01-01

    James House's revised Principles of Chemical Kinetics provides a clear and logical description of chemical kinetics in a manner unlike any other book of its kind. Clearly written with detailed derivations, the text allows students to move rapidly from theoretical concepts of rates of reaction to concrete applications. Unlike other texts, House presents a balanced treatment of kinetic reactions in gas, solution, and solid states. The entire text has been revised and includes many new sections and an additional chapter on applications of kinetics. The topics covered include quantitative rela

  9. A model of reactor kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, A.S.; Thompson, B.R.

    1988-09-01

    The analytical model of nuclear reactor transients, incorporating both mechanical and nuclear effects, simulates reactor kinetics. Linear analysis shows the stability borderline for small power perturbations. In a stable system, initial power disturbances die out with time. With an unstable combination of nuclear and mechanical characteristics, initial disturbances persist and may increase with time. With large instability, oscillations of great magnitude occur. Stability requirements set limits on the power density at which particular reactors can operate. The limiting power density depends largely on the product of two terms: the fraction of delayed neutrons and the frictional damping of vibratory motion in reactor core components. As the fraction of delayed neutrons is essentially fixed, mechanical damping largely determines the maximum power density. A computer program, based on the analytical model, calculates and plots reactor power as a nonlinear function of time in response to assigned values of mechanical and nuclear characteristics.

  10. k-core covers and the core

    NARCIS (Netherlands)

    Sanchez-Rodriguez, E.; Borm, Peter; Estevez-Fernandez, A.; Fiestras-Janeiro, G.; Mosquera, M.A.

    2015-01-01

    This paper extends the notion of individual minimal rights for a transferable utility game (TU-game) to coalitional minimal rights using minimal balanced families of a specific type, thus defining a corresponding minimal rights game. It is shown that the core of a TU-game coincides with the core of

  11. Academic Rigor: The Core of the Core

    Science.gov (United States)

    Brunner, Judy

    2013-01-01

    Some educators see the Common Core State Standards as reason for stress, most recognize the positive possibilities associated with them and are willing to make the professional commitment to implementing them so that academic rigor for all students will increase. But business leaders, parents, and the authors of the Common Core are not the only…

  12. k-core covers and the core

    NARCIS (Netherlands)

    Sanchez-Rodriguez, E.; Borm, Peter; Estevez-Fernandez, A.; Fiestras-Janeiro, G.; Mosquera, M.A.

    This paper extends the notion of individual minimal rights for a transferable utility game (TU-game) to coalitional minimal rights using minimal balanced families of a specific type, thus defining a corresponding minimal rights game. It is shown that the core of a TU-game coincides with the core of

  13. Turbulence and cooling in cluster cores

    CERN Document Server

    Banerjee, Nilanjan

    2014-01-01

    We study the interplay between turbulent heating, mixing, and radiative cooling in an idealized model of cool cluster cores. Active galactic nuclei (AGN) jets are expected to drive turbulence and heat cluster cores. Cooling of the intracluster medium (ICM) and stirring by AGN jets are tightly coupled in a feedback loop. We impose the feedback loop by balancing radiative cooling with turbulent heating. In addition to heating the plasma, turbulence also mixes it, suppressing the formation of cold gas at small scales. In this regard, the effect of turbulence is analogous to thermal conduction. For uniform plasma in thermal balance (turbulent heating balancing radiative cooling), cold gas condenses only if the cooling time is shorter than the mixing time. This condition requires the turbulent kinetic energy to be $\\gtrsim$ the plasma internal energy; such high velocities in cool cores are ruled out by observations. The results with realistic magnetic fields and thermal conduction are qualitatively similar to the ...

  14. Kinetically tuned dimensional augmentation as a versatile synthetic route towards robust metal-organic frameworks

    National Research Council Canada - National Science Library

    Feng, Dawei; Wang, Kecheng; Wei, Zhangwen; Chen, Ying-Pin; Simon, Cory M; Arvapally, Ravi K; Martin, Richard L; Bosch, Mathieu; Liu, Tian-Fu; Fordham, Stephen; Yuan, Daqiang; Omary, Mohammad A; Haranczyk, Maciej; Smit, Berend; Zhou, Hong-Cai

    2014-01-01

    .... Here we present a kinetically tuned dimensional augmentation synthetic route for the preparation of highly crystalline and extremely robust metal-organic frameworks with a preserved metal cluster core...

  15. Comodules over semiperfect corings

    CERN Document Server

    Caenepeel, S

    2011-01-01

    We discuss when the Rat functor associated to a coring satisfying the left $\\alpha$-condition is exact. We study the category of comodules over a semiperfect coring. We characterize semiperfect corings over artinian rings and over qF-rings.

  16. Coring Sample Acquisition Tool

    Science.gov (United States)

    Haddad, Nicolas E.; Murray, Saben D.; Walkemeyer, Phillip E.; Badescu, Mircea; Sherrit, Stewart; Bao, Xiaoqi; Kriechbaum, Kristopher L.; Richardson, Megan; Klein, Kerry J.

    2012-01-01

    A sample acquisition tool (SAT) has been developed that can be used autonomously to sample drill and capture rock cores. The tool is designed to accommodate core transfer using a sample tube to the IMSAH (integrated Mars sample acquisition and handling) SHEC (sample handling, encapsulation, and containerization) without ever touching the pristine core sample in the transfer process.

  17. Irreversible processes kinetic theory

    CERN Document Server

    Brush, Stephen G

    2013-01-01

    Kinetic Theory, Volume 2: Irreversible Processes deals with the kinetic theory of gases and the irreversible processes they undergo. It includes the two papers by James Clerk Maxwell and Ludwig Boltzmann in which the basic equations for transport processes in gases are formulated, together with the first derivation of Boltzmann's ""H-theorem"" and a discussion of this theorem, along with the problem of irreversibility.Comprised of 10 chapters, this volume begins with an introduction to the fundamental nature of heat and of gases, along with Boltzmann's work on the kinetic theory of gases and s

  18. Banded transformer cores

    Science.gov (United States)

    Mclyman, C. W. T. (Inventor)

    1974-01-01

    A banded transformer core formed by positioning a pair of mated, similar core halves on a supporting pedestal. The core halves are encircled with a strap, selectively applying tension whereby a compressive force is applied to the core edge for reducing the innate air gap. A dc magnetic field is employed in supporting the core halves during initial phases of the banding operation, while an ac magnetic field subsequently is employed for detecting dimension changes occurring in the air gaps as tension is applied to the strap.

  19. Kinetic equations: computation

    CERN Document Server

    Pareschi, Lorenzo

    2013-01-01

    Kinetic equations bridge the gap between a microscopic description and a macroscopic description of the physical reality. Due to the high dimensionality the construction of numerical methods represents a challenge and requires a careful balance between accuracy and computational complexity.

  20. Thermal kinetic inductance detector

    Energy Technology Data Exchange (ETDEWEB)

    Cecil, Thomas; Gades, Lisa; Miceli, Antonio; Quaranta, Orlando

    2016-12-20

    A microcalorimeter for radiation detection that uses superconducting kinetic inductance resonators as the thermometers. The detector is frequency-multiplexed which enables detector systems with a large number of pixels.

  1. Chemical Kinetics Database

    Science.gov (United States)

    SRD 17 NIST Chemical Kinetics Database (Web, free access)   The NIST Chemical Kinetics Database includes essentially all reported kinetics results for thermal gas-phase chemical reactions. The database is designed to be searched for kinetics data based on the specific reactants involved, for reactions resulting in specified products, for all the reactions of a particular species, or for various combinations of these. In addition, the bibliography can be searched by author name or combination of names. The database contains in excess of 38,000 separate reaction records for over 11,700 distinct reactant pairs. These data have been abstracted from over 12,000 papers with literature coverage through early 2000.

  2. REACTION KINETICS OF CA-BASED SORBENTS WITH HC1

    Science.gov (United States)

    The kinetics of the reaction between CaO and HCl were investigated under conditions that minimize bulk mass transfer and pore diffusion limitations. Reactivity data from 0.2- to 1-s exposure to 5000 ppm HCl in a fixed bed reactor were analyzed by a shrinking core model of diffusi...

  3. Electrochemical kinetics theoretical aspects

    CERN Document Server

    Vetter, Klaus J

    1967-01-01

    Electrochemical Kinetics: Theoretical Aspects focuses on the processes, methodologies, reactions, and transformations in electrochemical kinetics. The book first offers information on electrochemical thermodynamics and the theory of overvoltage. Topics include equilibrium potentials, concepts and definitions, electrical double layer and electrocapillarity, and charge-transfer, diffusion, and reaction overvoltage. Crystallization overvoltage, total overvoltage, and resistance polarization are also discussed. The text then examines the methods of determining electrochemical reaction mechanisms

  4. Parametric study of the physical properties of hydrate-bearing sand, silt, and clay sediments: 1. Electromagnetic properties

    Science.gov (United States)

    Lee, J.Y.; Santamarina, J.C.; Ruppel, C.

    2010-01-01

    The marked decrease in bulk electrical conductivity of sediments in the presence of gas hydrates has been used to interpret borehole electrical resistivity logs and, to a lesser extent, the results of controlled source electromagnetic surveys to constrain the spatial distribution and predicted concentration of gas hydrate in natural settings. Until now, an exhaustive laboratory data set that could be used to assess the impact of gas hydrate on the electromagnetic properties of different soils (sand, silt, and clay) at different effective stress and with different saturations of hydrate has been lacking. The laboratory results reported here are obtained using a standard geotechnical cell and the hydrate-formed tetrahydrofuran (THF), a liquid that is fully miscible in water and able to produce closely controlled saturations of hydrate from dissolved phase. Both permittivity and electrical conductivity are good indicators of the volume fraction of free water in the sediment, which is in turn dependent on hydrate saturation. Permittivity in the microwave frequency range is particularly predictive of free water content since it is barely affected by ionic concentration, pore structure, and surface conduction. Electrical conductivity (or resistivity) is less reliable for constraining water content or hydrate saturation: In addition to fluid-filled porosity, other factors, such as the ionic concentration of the pore fluid and possibly other conduction effects (e.g., surface conduction in high specific surface soils having low conductivity pore fluid), also influence electrical conductivity.

  5. Modified effective medium model for gas hydrate bearing,clay-dominated sediments in the Krishna-Godavari Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Sriram, G.; Dewangan, P.; Ramprasad, T.

    volume fraction qf and cf are related to the original fraction ( if ) as, ( ) ( ) ( ) ( ),11 ,11 φφ φφ −−= −−= ic iq ff ff (6) and ( ) ( ).1 φ−= hh Cf The effective dry bulk )( HMK and shear )( HMG moduli at critical...

  6. HyFlux - Part II: Subsurface sequestration of methane-derived carbon in gas-hydrate- bearing marine sediments

    Science.gov (United States)

    Naehr, T. H.; Asper, V. L.; Garcia, O.; Kastner, M.; Leifer, I.; MacDonald, I. R.; Solomon, E. A.; Yvon-Lewis, S.; Zimmer, B.

    2008-12-01

    The recently funded DOE/NETL study "HyFlux: Remote sensing and sea-truth measurements of methane flux to the atmosphere" (see MacDonald et al.: HyFlux - Part I) will combine sea surface, water column and shallow subsurface observations to improve our estimates of methane flux from submarine seeps and associated gas hydrate deposits to the water column and atmosphere along the Gulf of Mexico continental margin and other selected areas world-wide. As methane-rich fluids rise towards the sediment-water interface, they will interact with sulfate-rich pore fluids derived from overlying bottom water, which results in the formation of an important biogeochemical redox boundary, the so-called sulfate-methane interface, or SMI. Both methane and sulfate are consumed within the SMI and dissolved inorganic carbon, mostly bicarbonate (HCO3-) and hydrogen sulfide are produced, stimulating authigenic carbonate precipitation at and immediately below the SMI. Accordingly, the formation of authigenic carbonates in methane- and gas-hydrate-rich sediments will sequester a portion of the methane-derived carbon. To date, however, little is known about the quantitative aspects of these reactions. Rates of DIC production are not well constrained, but recent biogeochemical models indicate that CaCO3 precipitation rates may be as high as 120 μmol cm-2a-1. Therefore, AOM-driven carbonate precipitation must be considered when assessing the impact of gas-hydrate-derived methane on the global carbon cycle. As part of HyFlux, we will conduct pore water analyses (DOC, DIC, CH4, δ13CDIC, δ13CDOC, δ13CCH4, δ18O, and δD isotope ratios) to evaluate the importance of authigenic carbonate precipitation as a sequestration mechanism for methane- derived carbon. In addition, sediment and seafloor carbonate samples will be analyzed for bulk sedimentary carbonate (δ13C and δ18O) and bulk sedimentary organic matter (δ13C and δ15N), as well as sulfur, bulk mineralogy, texture and morphological features, and carbonate stable isotopes. We will then combine observational, geochemical, microbiological, and mathematical methods to assess the effectiveness of authigenic carbonate precipitation as a sink for methane-derived carbon under varying environmental conditions. Results of water column flux analysis, air-sea flux modeling, and sediment and pore water analysis will contribute to the development of a working model for quantifying regional fluxes of gas-hydrate-derived methane from the subsurface to the water column and atmosphere.

  7. Hydro-geomechanical behaviour of gas-hydrate bearing soils during gas production through depressurization and CO2 injection

    Science.gov (United States)

    Deusner, C.; Gupta, S.; Kossel, E.; Bigalke, N.; Haeckel, M.

    2015-12-01

    Results from recent field trials suggest that natural gas could be produced from marine gas hydrate reservoirs at compatible yields and rates. It appears, from a current perspective, that gas production would essentially be based on depressurization and, when facing suitable conditions, be assisted by local thermal stimulation or gas hydrate conversion after injection of CO2-rich fluids. Both field trials, onshore in the Alaska permafrost and in the Nankai Trough offshore Japan, were accompanied by different technical issues, the most striking problems resulting from un-predicted geomechanical behaviour, sediment destabilization and catastrophic sand production. So far, there is a lack of experimental data which could help to understand relevant mechanisms and triggers for potential soil failure in gas hydrate production, to guide model development for simulation of soil behaviour in large-scale production, and to identify processes which drive or, further, mitigate sand production. We use high-pressure flow-through systems in combination with different online and in situ monitoring tools (e.g. Raman microscopy, MRI) to simulate relevant gas hydrate production scenarios. Key components for soil mechanical studies are triaxial systems with ERT (Electric resistivity tomography) and high-resolution local strain analysis. Sand production control and management is studied in a novel hollow-cylinder-type triaxial setup with a miniaturized borehole which allows fluid and particle transport at different fluid injection and flow conditions. Further, the development of a large-scale high-pressure flow-through triaxial test system equipped with μ-CT is ongoing. We will present results from high-pressure flow-through experiments on gas production through depressurization and injection of CO2-rich fluids. Experimental data are used to develop and parametrize numerical models which can simulate coupled process dynamics during gas-hydrate formation and gas production.

  8. Relative permeability of hydrate-bearing sediments from percolation theory and critical path analysis: theoretical and experimental results

    Science.gov (United States)

    Daigle, H.; Rice, M. A.

    2015-12-01

    Relative permeabilities to water and gas are important parameters for accurate modeling of the formation of methane hydrate deposits and production of methane from hydrate reservoirs. Experimental measurements of gas and water permeability in the presence of hydrate are difficult to obtain. The few datasets that do exist suggest that relative permeability obeys a power law relationship with water or gas saturation with exponents ranging from around 2 to greater than 10. Critical path analysis and percolation theory provide a framework for interpreting the saturation-dependence of relative permeability based on percolation thresholds and the breadth of pore size distributions, which may be determined easily from 3-D images or gas adsorption-desorption hysteresis. We show that the exponent of the permeability-saturation relationship for relative permeability to water is related to the breadth of the pore size distribution, with broader pore size distributions corresponding to larger exponents. Relative permeability to water in well-sorted sediments with narrow pore size distributions, such as Berea sandstone or Toyoura sand, follows percolation scaling with an exponent of 2. On the other hand, pore-size distributions determined from argon adsorption measurements we performed on clays from the Nankai Trough suggest that relative permeability to water in fine-grained intervals may be characterized by exponents as large as 10 as determined from critical path analysis. We also show that relative permeability to the gas phase follows percolation scaling with a quadratic dependence on gas saturation, but the threshold gas saturation for percolation changes with hydrate saturation, which is an important consideration in systems in which both hydrate and gas are present, such as during production from a hydrate reservoir. Our work shows how measurements of pore size distributions from 3-D imaging or gas adsorption may be used to determine relative permeabilities.

  9. Relative permeability of hydrate-bearing sediments from percolation theory and critical path analysis: theoretical and experimental results

    Energy Technology Data Exchange (ETDEWEB)

    Daigle, Hugh [University of Texas at Austin; Rice, Mary Anna [North Carolina State University; Daigle, Hugh

    2015-12-14

    Relative permeabilities to water and gas are important parameters for accurate modeling of the formation of methane hydrate deposits and production of methane from hydrate reservoirs. Experimental measurements of gas and water permeability in the presence of hydrate are difficult to obtain. The few datasets that do exist suggest that relative permeability obeys a power law relationship with water or gas saturation with exponents ranging from around 2 to greater than 10. Critical path analysis and percolation theory provide a framework for interpreting the saturation-dependence of relative permeability based on percolation thresholds and the breadth of pore size distributions, which may be determined easily from 3-D images or gas adsorption-desorption hysteresis. We show that the exponent of the permeability-saturation relationship for relative permeability to water is related to the breadth of the pore size distribution, with broader pore size distributions corresponding to larger exponents. Relative permeability to water in well-sorted sediments with narrow pore size distributions, such as Berea sandstone or Toyoura sand, follows percolation scaling with an exponent of 2. On the other hand, pore-size distributions determined from argon adsorption measurements we performed on clays from the Nankai Trough suggest that relative permeability to water in fine-grained intervals may be characterized by exponents as large as 10 as determined from critical path analysis. We also show that relative permeability to the gas phase follows percolation scaling with a quadratic dependence on gas saturation, but the threshold gas saturation for percolation changes with hydrate saturation, which is an important consideration in systems in which both hydrate and gas are present, such as during production from a hydrate reservoir. Our work shows how measurements of pore size distributions from 3-D imaging or gas adsorption may be used to determine relative permeabilities.

  10. The core paradox.

    Science.gov (United States)

    Kennedy, G. C.; Higgins, G. H.

    1973-01-01

    Rebuttal of suggestions from various critics attempting to provide an escape from the seeming paradox originated by Higgins and Kennedy's (1971) proposed possibility that the liquid in the outer core was thermally stably stratified and that this stratification might prove a powerful inhibitor to circulation of the outer core fluid of the kind postulated for the generation of the earth's magnetic field. These suggestions are examined and shown to provide no reasonable escape from the core paradox.

  11. K-core inflation

    OpenAIRE

    Alexander L. Wolman

    2011-01-01

    K-core inflation is a new class of underlying inflation measures. The two most popular measures of underlying inflation are core inflation and trimmed mean inflation. The former removes fixed categories of goods and services (food and energy) from the inflation calculation, and the latter removes fixed percentiles of the weighted distribution of price changes. In contrast, k-core inflation specifies a size of relative price change to be removed from the inflation calculation. Thus, the catego...

  12. Sediment Core Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Provides instrumentation and expertise for physical and geoacoustic characterization of marine sediments. DESCRIPTION: The multisensor core logger measures...

  13. Sediment Core Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Provides instrumentation and expertise for physical and geoacoustic characterization of marine sediments.DESCRIPTION: The multisensor core logger measures...

  14. Multiple alternative substrate kinetics.

    Science.gov (United States)

    Anderson, Vernon E

    2015-11-01

    The specificity of enzymes for their respective substrates has been a focal point of enzyme kinetics since the initial characterization of metabolic chemistry. Various processes to quantify an enzyme's specificity using kinetics have been utilized over the decades. Fersht's definition of the ratio kcat/Km for two different substrates as the "specificity constant" (ref [7]), based on the premise that the important specificity existed when the substrates were competing in the same reaction, has become a consensus standard for enzymes obeying Michaelis-Menten kinetics. The expansion of the theory for the determination of the relative specificity constants for a very large number of competing substrates, e.g. those present in a combinatorial library, in a single reaction mixture has been developed in this contribution. The ratio of kcat/Km for isotopologs has also become a standard in mechanistic enzymology where kinetic isotope effects have been measured by the development of internal competition experiments with extreme precision. This contribution extends the theory of kinetic isotope effects to internal competition between three isotopologs present at non-tracer concentrations in the same reaction mix. This article is part of a special issue titled: Enzyme Transition States from Theory and Experiment.

  15. Onsager reciprocity principle for kinetic models and kinetic schemes

    CERN Document Server

    Mahendra, Ajit Kumar

    2013-01-01

    Boltzmann equation requires some alternative simpler kinetic model like BGK to replace the collision term. Such a kinetic model which replaces the Boltzmann collision integral should preserve the basic properties and characteristics of the Boltzmann equation and comply with the requirements of non equilibrium thermodynamics. Most of the research in development of kinetic theory based methods have focused more on entropy conditions, stability and ignored the crucial aspect of non equilibrium thermodynamics. The paper presents a new kinetic model formulated based on the principles of non equilibrium thermodynamics. The new kinetic model yields correct transport coefficients and satisfies Onsager's reciprocity relationship. The present work also describes a novel kinetic particle method and gas kinetic scheme based on this linkage of non-equilibrium thermodynamics and kinetic theory. The work also presents derivation of kinetic theory based wall boundary condition which complies with the principles of non-equili...

  16. Kinetics examination of pressurised steam gasification of beech wood

    Directory of Open Access Journals (Sweden)

    Grzywacz Przemysław

    2016-01-01

    Full Text Available In Poland, among all renewable energy sources, share of biomass in electricity production is the largest. Great potential in biomass utilization involves use of gasification technology. The course of biomass gasification process in steam atmosphere is the subject of numerous scientific studies. The aim of this study was kinetics examination of pressurized beech wood waste gasification, that can be successfully used in industrial gasification. Measurements were carried out on a unique laboratory installation, that allows kinetics examination of solid fuels gasification with steam at wide range of pressures, via using thermovolumetric method. Formation rates of main gaseous products were determined, moreover, composition of post-reaction gas, as well as biomass conversion degree depending on the temperature were specified. Kinetic parameters of gasification were calculated and series of kinetic models were used to their designation ie Isoconvesional method, Integrated Core Model (ICM, Grain Model (GM and Random Pore Model (RPM.

  17. A spatial kinetic model for simulating VVER-1000 start-up transient

    Energy Technology Data Exchange (ETDEWEB)

    Kashi, Samira [Department of Nuclear Engineering, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Moghaddam, Nader Maleki, E-mail: nader.moghaddam@gmail.com [Department of Nuclear Engineering and Physics, Amir Kabir University of Technology, Tehran (Iran, Islamic Republic of); Shahriari, Majid [Department of Nuclear Engineering, Shahid Beheshti University, Tehran (Iran, Islamic Republic of)

    2011-06-15

    Research highlights: > A spatial kinetic model of a VVER-1000 reactor core is presented. > The reactor power is tracked using the point kinetic equations from 100 W to 612 kW. > The lamped parameter approximation is used for solving the energy balance equations. > The value of reactivity related to feedback effects of core elements is calculated. > The main neutronic parameters during the transient are calculated. - Abstract: An accurate prediction of reactor core behavior in transients depends on how much it could be possible to exactly determine the thermal feedbacks of the core elements such as fuel, clad and coolant. In short time transients, results of these feedbacks directly affect the reactor power and determine the reactor response. Such transients are commonly happened during the start-up process which makes it necessary to carefully evaluate the detail of process. Hence this research evaluates a short time transient occurring during the start up of VVER-1000 reactor. The reactor power was tracked using the point kinetic equations from HZP state (100 W) to 612 kW. Final power (612 kW) was achieved by withdrawing control rods and resultant excess reactivity was set into dynamic equations to calculate the reactor power. Since reactivity is the most important part in the point kinetic equations, using a Lumped Parameter (LP) approximation, energy balance equations were solved in different zones of the core. After determining temperature and total reactivity related to feedbacks in each time step, the exact value of reactivity is obtained and is inserted into point kinetic equations. In reactor core each zone has a specific temperature and its corresponding thermal feedback. To decrease the effects of point kinetic approximations, these partial feedbacks in different zones are superposed to show an accurate model of reactor core dynamics. In this manner the reactor point kinetic can be extended to the whole reactor core which means 'Reactor spatial

  18. The Magnetic Furnace: Intense Core Dynamos in B-stars

    CERN Document Server

    Augustson, Kyle C; Toomre, Juri

    2016-01-01

    The dynamo action achieved in the convective cores of main-sequence massive stars is explored here through 3-D global simulations of convective core dynamos operating within a young 10$M_{\\mathrm{sun}}$ B-type star, using the anelastic spherical harmonic (ASH) code. These simulations capture the inner 65% of this star by radius, encompassing the convective nuclear-burning core (about 23% by radius) and a portion of the overlying radiative envelope. Eight rotation rates are considered, ranging from 0.05% to 16% of the surface breakup velocity, thereby capturing both convection barely sensing the effects of rotation to others in which the Coriolis forces are prominent. The vigorous dynamo action realized within all of these turbulent convective cores builds magnetic fields with peak strengths exceeding a megagauss, with the overall magnetic energy (ME) in the faster rotators reaching super-equipartition levels compared to the convective kinetic energy (KE). The core convection typically involves turbulent colum...

  19. Erbium hydride decomposition kinetics.

    Energy Technology Data Exchange (ETDEWEB)

    Ferrizz, Robert Matthew

    2006-11-01

    Thermal desorption spectroscopy (TDS) is used to study the decomposition kinetics of erbium hydride thin films. The TDS results presented in this report are analyzed quantitatively using Redhead's method to yield kinetic parameters (E{sub A} {approx} 54.2 kcal/mol), which are then utilized to predict hydrogen outgassing in vacuum for a variety of thermal treatments. Interestingly, it was found that the activation energy for desorption can vary by more than 7 kcal/mol (0.30 eV) for seemingly similar samples. In addition, small amounts of less-stable hydrogen were observed for all erbium dihydride films. A detailed explanation of several approaches for analyzing thermal desorption spectra to obtain kinetic information is included as an appendix.

  20. Ice Core Investigations

    Science.gov (United States)

    Krim, Jessica; Brody, Michael

    2008-01-01

    What can glaciers tell us about volcanoes and atmospheric conditions? How does this information relate to our understanding of climate change? Ice Core Investigations is an original and innovative activity that explores these types of questions. It brings together popular science issues such as research, climate change, ice core drilling, and air…

  1. Making an Ice Core.

    Science.gov (United States)

    Kopaska-Merkel, David C.

    1995-01-01

    Explains an activity in which students construct a simulated ice core. Materials required include only a freezer, food coloring, a bottle, and water. This hands-on exercise demonstrates how a glacier is formed, how ice cores are studied, and the nature of precision and accuracy in measurement. Suitable for grades three through eight. (Author/PVD)

  2. Ice Core Investigations

    Science.gov (United States)

    Krim, Jessica; Brody, Michael

    2008-01-01

    What can glaciers tell us about volcanoes and atmospheric conditions? How does this information relate to our understanding of climate change? Ice Core Investigations is an original and innovative activity that explores these types of questions. It brings together popular science issues such as research, climate change, ice core drilling, and air…

  3. Iowa Core Annual Report

    Science.gov (United States)

    Iowa Department of Education, 2015

    2015-01-01

    One central component of a great school system is a clear set of expectations, or standards, that educators help all students reach. In Iowa, that effort is known as the Iowa Core. The Iowa Core represents the statewide academic standards, which describe what students should know and be able to do in math, science, English language arts, and…

  4. Mercury's core evolution

    Science.gov (United States)

    Deproost, Marie-Hélène; Rivoldini, Attilio; Van Hoolst, Tim

    2016-10-01

    Remote sensing data of Mercury's surface by MESSENGER indicate that Mercury formed under reducing conditions. As a consequence, silicon is likely the main light element in the core together with a possible small fraction of sulfur. Compared to sulfur, which does almost not partition into solid iron at Mercury's core conditions and strongly decreases the melting temperature, silicon partitions almost equally well between solid and liquid iron and is not very effective at reducing the melting temperature of iron. Silicon as the major light element constituent instead of sulfur therefore implies a significantly higher core liquidus temperature and a decrease in the vigor of compositional convection generated by the release of light elements upon inner core formation.Due to the immiscibility in liquid Fe-Si-S at low pressure (below 15 GPa), the core might also not be homogeneous and consist of an inner S-poor Fe-Si core below a thinner Si-poor Fe-S layer. Here, we study the consequences of a silicon-rich core and the effect of the blanketing Fe-S layer on the thermal evolution of Mercury's core and on the generation of a magnetic field.

  5. Quantum kinetic theory

    CERN Document Server

    Bonitz, Michael

    2016-01-01

    This book presents quantum kinetic theory in a comprehensive way. The focus is on density operator methods and on non-equilibrium Green functions. The theory allows to rigorously treat nonequilibrium dynamics in quantum many-body systems. Of particular interest are ultrafast processes in plasmas, condensed matter and trapped atoms that are stimulated by rapidly developing experiments with short pulse lasers and free electron lasers. To describe these experiments theoretically, the most powerful approach is given by non-Markovian quantum kinetic equations that are discussed in detail, including computational aspects.

  6. The logic of kinetic regulation in the thioredoxin system

    Directory of Open Access Journals (Sweden)

    Hofmeyr Jan-Hendrik S

    2011-01-01

    Full Text Available Abstract Background The thioredoxin system consisting of NADP(H, thioredoxin reductase and thioredoxin provides reducing equivalents to a large and diverse array of cellular processes. Despite a great deal of information on the kinetics of individual thioredoxin-dependent reactions, the kinetic regulation of this system as an integrated whole is not known. We address this by using kinetic modeling to identify and describe kinetic behavioral motifs found within the system. Results Analysis of a realistic computational model of the Escherichia coli thioredoxin system revealed several modes of kinetic regulation in the system. In keeping with published findings, the model showed that thioredoxin-dependent reactions were adaptable (i.e. changes to the thioredoxin system affected the kinetic profiles of these reactions. Further and in contrast to other systems-level descriptions, analysis of the model showed that apparently unrelated thioredoxin oxidation reactions can affect each other via their combined effects on the thioredoxin redox cycle. However, the scale of these effects depended on the kinetics of the individual thioredoxin oxidation reactions with some reactions more sensitive to changes in the thioredoxin cycle and others, such as the Tpx-dependent reduction of hydrogen peroxide, less sensitive to these changes. The coupling of the thioredoxin and Tpx redox cycles also allowed for ultrasensitive changes in the thioredoxin concentration in response to changes in the thioredoxin reductase concentration. We were able to describe the kinetic mechanisms underlying these behaviors precisely with analytical solutions and core models. Conclusions Using kinetic modeling we have revealed the logic that underlies the functional organization and kinetic behavior of the thioredoxin system. The thioredoxin redox cycle and associated reactions allows for a system that is adaptable, interconnected and able to display differential sensitivities to changes

  7. Mars' core and magnetism.

    Science.gov (United States)

    Stevenson, D J

    2001-07-12

    The detection of strongly magnetized ancient crust on Mars is one of the most surprising outcomes of recent Mars exploration, and provides important insight about the history and nature of the martian core. The iron-rich core probably formed during the hot accretion of Mars approximately 4.5 billion years ago and subsequently cooled at a rate dictated by the overlying mantle. A core dynamo operated much like Earth's current dynamo, but was probably limited in duration to several hundred million years. The early demise of the dynamo could have arisen through a change in the cooling rate of the mantle, or even a switch in convective style that led to mantle heating. Presently, Mars probably has a liquid, conductive outer core and might have a solid inner core like Earth.

  8. The t-core of an s-core

    OpenAIRE

    Fayers, Matthew

    2010-01-01

    We consider the $t$-core of an $s$-core partition, when $s$ and $t$ are coprime positive integers. Olsson has shown that the $t$-core of an $s$-core is again an $s$-core, and we examine certain actions of the affine symmetric group on $s$-cores which preserve the $t$-core of an $s$-core. Along the way, we give a new proof of Olsson's result. We also give a new proof of a result of Vandehey, showing that there is a simultaneous $s$- and $t$-core which contains all others.

  9. The t-core of an s-core

    OpenAIRE

    Fayers, Matthew

    2010-01-01

    We consider the $t$-core of an $s$-core partition, when $s$ and $t$ are coprime positive integers. Olsson has shown that the $t$-core of an $s$-core is again an $s$-core, and we examine certain actions of the affine symmetric group on $s$-cores which preserve the $t$-core of an $s$-core. Along the way, we give a new proof of Olsson's result. We also give a new proof of a result of Vandehey, showing that there is a simultaneous $s$- and $t$-core which contains all others.

  10. Korrelasjon mellom core styrke, core stabilitet og utholdende styrke i core

    OpenAIRE

    Berg-Olsen, Andrea Marie; Fugelsøy, Eivor; Maurstad, Ann-Louise

    2010-01-01

    Formålet med studien var å se hvilke korrelasjon det er mellom core styrke, core stabilitet og utholdende styrke i core. Testingen bestod av tre hoveddeler hvor vi testet core styrke, core stabilitet og utholdende styrke i core. Innenfor core styrke og utholdende styrke i core ble tre ulike tester utført. Ved måling av core stabilitet ble det gjennomført kun en test. I core styrke ble isometrisk abdominal fleksjon, isometrisk rygg ekstensjon og isometrisk lateral fleksjon testet. Sit-ups p...

  11. Korrelasjon mellom core styrke, core stabilitet og utholdende styrke i core

    OpenAIRE

    Berg-Olsen, Andrea Marie; Fugelsøy, Eivor; Maurstad, Ann-Louise

    2010-01-01

    Formålet med studien var å se hvilke korrelasjon det er mellom core styrke, core stabilitet og utholdende styrke i core. Testingen bestod av tre hoveddeler hvor vi testet core styrke, core stabilitet og utholdende styrke i core. Innenfor core styrke og utholdende styrke i core ble tre ulike tester utført. Ved måling av core stabilitet ble det gjennomført kun en test. I core styrke ble isometrisk abdominal fleksjon, isometrisk rygg ekstensjon og isometrisk lateral fleksjon testet. Sit-ups p...

  12. Earth's inner core: Innermost inner core or hemispherical variations?

    NARCIS (Netherlands)

    Lythgoe, K. H.; Deuss, A.; Rudge, J. F.; Neufeld, J. A.

    2014-01-01

    The structure of Earth's deep inner core has important implications for core evolution, since it is thought to be related to the early stages of core formation. Previous studies have suggested that there exists an innermost inner core with distinct anisotropy relative to the rest of the inner core.

  13. Earth's inner core: Innermost inner core or hemispherical variations?

    NARCIS (Netherlands)

    Lythgoe, K. H.; Deuss, A.; Rudge, J. F.; Neufeld, J. A.

    2014-01-01

    The structure of Earth's deep inner core has important implications for core evolution, since it is thought to be related to the early stages of core formation. Previous studies have suggested that there exists an innermost inner core with distinct anisotropy relative to the rest of the inner core.

  14. Physical properties of dense cores in Orion B9

    CERN Document Server

    Miettinen, Oskari; Haikala, Lauri K; Juvela, Mika

    2010-01-01

    We aim to determine the physical and chemical properties of dense cores in Orion B9. We observed the NH3(1,1) and (2,2), and the N2H+(3-2) lines towards the submm peak positions. These data are used in conjunction with our LABOCA 870 micron dust continuum data. The gas kinetic temperature in the cores is between ~9.4-13.9 K. The non-thermal velocity dispersion is subsonic in most of the cores. The non-thermal linewidth in protostellar cores appears to increase with increasing bolometric luminosity. The core masses are very likely drawn from the same parent distribution as the core masses in Orion B North. Starless cores in the region are likely to be gravitationally bound, and thus prestellar. Some of the cores have a lower radial velocity than the systemic velocity of the region, suggesting that they are members of the "low-velocity part" of Orion B. The observed core-separation distances deviate from the corresponding random-like model distributions. The distances between the nearest-neighbours are comparab...

  15. Oxidative desulfurization: kinetic modelling.

    Science.gov (United States)

    Dhir, S; Uppaluri, R; Purkait, M K

    2009-01-30

    Increasing environmental legislations coupled with enhanced production of petroleum products demand, the deployment of novel technologies to remove organic sulfur efficiently. This work represents the kinetic modeling of ODS using H(2)O(2) over tungsten-containing layered double hydroxide (LDH) using the experimental data provided by Hulea et al. [V. Hulea, A.L. Maciuca, F. Fajula, E. Dumitriu, Catalytic oxidation of thiophenes and thioethers with hydrogen peroxide in the presence of W-containing layered double hydroxides, Appl. Catal. A: Gen. 313 (2) (2006) 200-207]. The kinetic modeling approach in this work initially targets the scope of the generation of a superstructure of micro-kinetic reaction schemes and models assuming Langmuir-Hinshelwood (LH) and Eley-Rideal (ER) mechanisms. Subsequently, the screening and selection of above models is initially based on profile-based elimination of incompetent schemes followed by non-linear regression search performed using the Levenberg-Marquardt algorithm (LMA) for the chosen models. The above analysis inferred that Eley-Rideal mechanism describes the kinetic behavior of ODS process using tungsten-containing LDH, with adsorption of reactant and intermediate product only taking place on the catalyst surface. Finally, an economic index is presented that scopes the economic aspects of the novel catalytic technology with the parameters obtained during regression analysis to conclude that the cost factor for the catalyst is 0.0062-0.04759 US $ per barrel.

  16. Kinetics and Catalysis Demonstrations.

    Science.gov (United States)

    Falconer, John L.; Britten, Jerald A.

    1984-01-01

    Eleven videotaped kinetics and catalysis demonstrations are described. Demonstrations include the clock reaction, oscillating reaction, hydrogen oxidation in air, hydrogen-oxygen explosion, acid-base properties of solids, high- and low-temperature zeolite reactivity, copper catalysis of ammonia oxidation and sodium peroxide decomposition, ammonia…

  17. Kinetic Gravity Separation

    NARCIS (Netherlands)

    Van Kooy, L.; Mooij, M.; Rem, P.

    2004-01-01

    Separations by density, such as the separation of non-ferrous scrap into light and heavy alloys, are often realized by means of heavy media. In principle, kinetic gravity separations in water can be faster and cheaper, because they do not rely on suspensions or salt solutions of which the density

  18. Vlasov simulations of kinetic Alfvén waves at proton kinetic scales

    Energy Technology Data Exchange (ETDEWEB)

    Vásconez, C. L. [Dipartimento di Fisica, Università della Calabria, I-87036 Cosenza (Italy); Observatorio Astronómico de Quito, Escuela Politécnica Nacional, Quito (Ecuador); Valentini, F.; Veltri, P. [Dipartimento di Fisica, Università della Calabria, I-87036 Cosenza (Italy); Camporeale, E. [Centrum Wiskunde and Informatica, Amsterdam (Netherlands)

    2014-11-15

    Kinetic Alfvén waves represent an important subject in space plasma physics, since they are thought to play a crucial role in the development of the turbulent energy cascade in the solar wind plasma at short wavelengths (of the order of the proton gyro radius ρ{sub p} and/or inertial length d{sub p} and beyond). A full understanding of the physical mechanisms which govern the kinetic plasma dynamics at these scales can provide important clues on the problem of the turbulent dissipation and heating in collisionless systems. In this paper, hybrid Vlasov-Maxwell simulations are employed to analyze in detail the features of the kinetic Alfvén waves at proton kinetic scales, in typical conditions of the solar wind environment (proton plasma beta β{sub p} = 1). In particular, linear and nonlinear regimes of propagation of these fluctuations have been investigated in a single-wave situation, focusing on the physical processes of collisionless Landau damping and wave-particle resonant interaction. Interestingly, since for wavelengths close to d{sub p} and β{sub p} ≃ 1 (for which ρ{sub p} ≃ d{sub p}) the kinetic Alfvén waves have small phase speed compared to the proton thermal velocity, wave-particle interaction processes produce significant deformations in the core of the particle velocity distribution, appearing as phase space vortices and resulting in flat-top velocity profiles. Moreover, as the Eulerian hybrid Vlasov-Maxwell algorithm allows for a clean almost noise-free description of the velocity space, three-dimensional plots of the proton velocity distribution help to emphasize how the plasma departs from the Maxwellian configuration of thermodynamic equilibrium due to nonlinear kinetic effects.

  19. IGCSE core mathematics

    CERN Document Server

    Wall, Terry

    2013-01-01

    Give your core level students the support and framework they require to get their best grades with this book dedicated to the core level content of the revised syllabus and written specifically to ensure a more appropriate pace. This title has been written for Core content of the revised Cambridge IGCSE Mathematics (0580) syllabus for first teaching from 2013. ? Gives students the practice they require to deepen their understanding through plenty of practice questions. ? Consolidates learning with unique digital resources on the CD, included free with every book. We are working with Cambridge

  20. Core shroud corner joints

    Science.gov (United States)

    Gilmore, Charles B.; Forsyth, David R.

    2013-09-10

    A core shroud is provided, which includes a number of planar members, a number of unitary corners, and a number of subassemblies each comprising a combination of the planar members and the unitary corners. Each unitary corner comprises a unitary extrusion including a first planar portion and a second planar portion disposed perpendicularly with respect to the first planar portion. At least one of the subassemblies comprises a plurality of the unitary corners disposed side-by-side in an alternating opposing relationship. A plurality of the subassemblies can be combined to form a quarter perimeter segment of the core shroud. Four quarter perimeter segments join together to form the core shroud.

  1. Subnanometer Control of Mean Core Size during Mesofluidic Synthesis of Small (D(core) Nanoparticles.

    Science.gov (United States)

    Elliott, Edward W; Haben, Patrick M; Hutchison, James E

    2015-11-03

    A convenient, single-step synthesis is reported that produces ligand-stabilized, water-soluble gold nanoparticles (AuNPs) with subnanometer-level precision of the mean core diameter over a range of 2-9 nm for a series of desired surface chemistries. The synthesis involves the reduction of a Au(III) species with sodium borohydride in the presence of a functionalized alkyl thiosulfate (Bunte salt) to yield thiolate-protected AuNPs. A key advantage of this synthesis is that simply adjusting the pH of the gold salt solution leads to control over the AuNP core size. The speciation of Au(III), and therefore the kinetics for its reduction and the core size produced, depends upon pH. The use of pH as the sole variable to control core size is a more reliable and convenient method than traditional approaches that rely on adjusting the concentrations and ratios of ligand, metal salt, and reducing agent. The average core size increased as the pH was raised for each ligand studied. Because the influence of pH was different for each of the ligands, working curves were plotted for each ligand to identify conditions to synthesize particles with specific, targeted core diameters. Using this approach, reaction conditions can be rapidly optimized using a combination of a mesofluidic reactor and small-angle X-ray scattering (SAXS) size analysis. The use of the mesofluidic reactor was needed to ensure fast mixing given the rapid kinetics for core formation. Using the reactor, it is possible to obtain reproducible sizes across multiple syntheses (size variation) and subnanometer control of the mean core dimensions. The synthetic method demonstrated here provides an attractive alternative to two-step syntheses involving ligand exchange because it is more efficient and eliminates the possibility of nanoparticle core size changes during exchange steps. This approach enables the development of "size ladders" of particles with the same surface chemistry for investigations of structure

  2. Biospecimen Core Resource - TCGA

    Science.gov (United States)

    The Cancer Genome Atlas (TCGA) Biospecimen Core Resource centralized laboratory reviews and processes blood and tissue samples and their associated data using optimized standard operating procedures for the entire TCGA Research Network.

  3. NICHD Zebrafish Core

    Data.gov (United States)

    Federal Laboratory Consortium — The core[HTML_REMOVED]s goal is to help researchers of any expertise perform zebrafish experiments aimed at illuminating basic biology and human disease mechanisms,...

  4. iPSC Core

    Data.gov (United States)

    Federal Laboratory Consortium — The induced Pluripotent Stem Cells (iPSC) Core was created in 2011 to accelerate stem cell research in the NHLBI by providing investigators consultation, technical...

  5. Reference: -300CORE [PLACE

    Lifescience Database Archive (English)

    Full Text Available -300CORE Forde BG, Heyworth A, Pywell J, Kreis M Nucleotide sequence of a B1 hordein gene and the identifica...tion of possible upstream regulatory elements in endosperm storage protein genes fr

  6. INTEGRAL core programme

    Science.gov (United States)

    Gehrels, N.; Schoenfelder, V.; Ubertini, P.; Winkler, C.

    1997-01-01

    The International Gamma Ray Astrophysics Laboratory (INTEGRAL) mission is described with emphasis on the INTEGRAL core program. The progress made in the planning activities for the core program is reported on. The INTEGRAL mission has a nominal lifetime of two years with a five year extension option. The observing time will be divided between the core program (between 30 and 35 percent during the first two years) and general observations. The core program consists of three main elements: the deep survey of the Galactic plane in the central radian of the Galaxy; frequent scans of the Galactic plane in the search for transient sources, and pointed observations of several selected sources. The allocation of the observation time is detailed and the sensitivities of the observations are outlined.

  7. Focusing on Core Business

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    China is regulating state-owned enterprises that are investing outside of their core business realms, concerned that poor investment decisions could lead to loss of state-owned assets, but some doubt the effect of the new regulation

  8. Organizing Core Tasks

    DEFF Research Database (Denmark)

    Boll, Karen

    Civil servants conduct the work which makes welfare states functions on an everyday bases: Police men police, school teachers teach, and tax inspectors inspect. Focus in this paper is on the core tasks of tax inspectors. The paper argues that their core task of securing the collection of revenue...... has remained much the same within the last 10 years. However, how the core task has been organized has changed considerable under the influence of various “organizing devices”. The paper focusses on how organizing devices such as risk assessment, output-focus, effect orientation, and treatment...... projects influence the organization of core tasks within the tax administration. The paper shows that the organizational transformations based on the use of these devices have had consequences both for the overall collection of revenue and for the employees’ feeling of “making a difference”. All in all...

  9. Trafficking of hepatitis C virus core protein during virus particle assembly.

    Directory of Open Access Journals (Sweden)

    Natalie A Counihan

    2011-10-01

    Full Text Available Hepatitis C virus (HCV core protein is directed to the surface of lipid droplets (LD, a step that is essential for infectious virus production. However, the process by which core is recruited from LD into nascent virus particles is not well understood. To investigate the kinetics of core trafficking, we developed methods to image functional core protein in live, virus-producing cells. During the peak of virus assembly, core formed polarized caps on large, immotile LDs, adjacent to putative sites of assembly. In addition, LD-independent, motile puncta of core were found to traffic along microtubules. Importantly, core was recruited from LDs into these puncta, and interaction between the viral NS2 and NS3-4A proteins was essential for this recruitment process. These data reveal new aspects of core trafficking and identify a novel role for viral nonstructural proteins in virus particle assembly.

  10. Kinetic Monte Carlo studies of the reaction kinetics of crystal defects that diffuse one-dimensionally with occasional transverse migration

    DEFF Research Database (Denmark)

    Heinisch, H.L.; Trinkaus, H.; Singh, Bachu Narain

    2007-01-01

    and confirmed by kinetic Monte Carlo (KMC) simulations. Here we report on KMC simulations investigating a different transition from 1D to 3D diffusion of 1D gliding loops for which their 1D migration is interrupted by occasional 2D migration due to conservative climb by dislocation core diffusion within a plane...... transverse to their 1D glide direction. Their transition from 1D to 3D kinetics is significantly different from that due to direction changes. The KMC results are compared to an analytical description of this diffusion mode in the form of a master curve relating the 1D normalized sink strength...

  11. Core collapse supernova remnants with ears

    CERN Document Server

    Grichener, Aldana

    2016-01-01

    We study the morphologies of core collapse supernova remnants (CCSNRs) and find that about third of CCSNRs have two opposite `ears' protruding from their main shell, and that the typical energy that is required to inflate these ears is about 10 percents of the explosion kinetic energy. We argue that these properties are most compatible with the expectation from the explosion jet feedback mechanism (JFM). Based on previous studies of ears in CCSNRs and the similarity of some ears to those found in planetary nebulae, we assume that the ears are inflated by jets that are launched during the explosion, or a short time after it. In the JFM explosion process the last jets' launching episode takes place just after the core has been ejected. These jets expand freely, interact with the exploding gas at some distance from the center, and form the ears. Under simple geometrical assumptions we find that the extra kinetic energy of the ears is in the range of 1 to 10 percents of the explosion energy. As not all of the kin...

  12. Kinetic Damage from Meteorites

    Science.gov (United States)

    Cooke, W.; Brown, P.; Matney, M.

    2017-01-01

    Comparing the natural meteorite flux at the Earth's surface to that of space debris, re-entering debris is 2 orders of magnitude less of a kinetic hazard at all but the very largest (and therefore rarest) sizes compared to natural impactors. Debris re-entries over several metric tonnes are roughly as frequent as natural impactors, but the survival fraction is expected to be much higher. Kinetic hazards from meteorites are very small, with only one recorded (indirect) injury reported. We expect fatalities to be even more rare, on the order of one person killed per several millennia. That several reports exist of small fragments/sand hitting people during meteorite falls is consistent with our prediction that this should occur every decade or so.

  13. Kinetic Actviation Relaxation Technique

    CERN Document Server

    Béland, Laurent Karim; El-Mellouhi, Fedwa; Joly, Jean-François; Mousseau, Normand

    2011-01-01

    We present a detailed description of the kinetic Activation-Relaxation Technique (k-ART), an off-lattice, self-learning kinetic Monte Carlo algorithm with on-the-fly event search. Combining a topological classification for local environments and event generation with ART nouveau, an efficient unbiased sampling method for finding transition states, k-ART can be applied to complex materials with atoms in off-lattice positions or with elastic deformations that cannot be handled with standard KMC approaches. In addition to presenting the various elements of the algorithm, we demonstrate the general character of k-ART by applying the algorithm to three challenging systems: self-defect annihilation in c-Si, self-interstitial diffusion in Fe and structural relaxation in amorphous silicon.

  14. Photon kinetics in plasmas

    Directory of Open Access Journals (Sweden)

    V.G. Morozov

    2009-01-01

    Full Text Available We present a kinetic theory of radiative processes in many-component plasmas with relativistic electrons and nonrelativistic heavy particles. Using the non-equilibrium Green's function technique in many-particle QED, we show that the transverse field correlation functions can be naturally decomposed into sharply peaked (non-Lorentzian parts that describe resonant (propagating photons and off-shell parts corresponding to virtual photons in the medium. Analogous decompositions are obtained for the longitudinal field correlation functions and the correlation functions of relativistic electrons. We derive a kinetic equation for the resonant photons with a finite spectral width and show that the off-shell parts of the particle and field correlation functions are essential to calculate the local radiating power in plasmas and recover the results of vacuum QED. The plasma effects on radiative processes are discussed.

  15. Kinetic Tetrazolium Microtiter Assay

    Science.gov (United States)

    Pierson, Duane L.; Stowe, Raymond; Koenig, David

    1993-01-01

    Kinetic tetrazolium microtiter assay (KTMA) involves use of tetrazolium salts and Triton X-100 (or equivalent), nontoxic, in vitro color developer solubilizing colored metabolite formazan without injuring or killing metabolizing cells. Provides for continuous measurement of metabolism and makes possible to determine rate of action of antimicrobial agent in real time as well as determines effective inhibitory concentrations. Used to monitor growth after addition of stimulatory compounds. Provides for kinetic determination of efficacy of biocide, greatly increasing reliability and precision of results. Also used to determine relative effectiveness of antimicrobial agent as function of time. Capability of generating results on day of test extremely important in treatment of water and waste, disinfection of hospital rooms, and in pharmaceutical, agricultural, and food-processing industries. Assay also used in many aspects of cell biology.

  16. Flocculation Kinetics of Chitosan

    Institute of Scientific and Technical Information of China (English)

    陈亮; 林志艳; 陈东辉

    2003-01-01

    Under the various conditions, the experiments of flocculation of bentonite solution with chitosan were carried out. And the flocculation kinetics was studied by the changes of floc size along with time. The results show that hydraulic gradient G (s-1) plays a key role in growing up of floc size and both of molecular weight and initial turbidity of bentonite solution influence the floc size in steady state and the time needed for steady floc size.

  17. Kinetics of hole nucleation in biomembrane rupture

    Energy Technology Data Exchange (ETDEWEB)

    Evans, Evan [Biomedical Engineering, Boston University, Boston, MA 02215 (United States); Smith, Benjamin A, E-mail: evanse@bu.edu [Departments of Physics and Pathology, University of British Columbia, Vancouver, BC, V6T 2A6 (Canada)

    2011-09-15

    The core component of a biological membrane is a fluid-lipid bilayer held together by interfacial-hydrophobic and van der Waals interactions, which are balanced for the most part by acyl chain entropy confinement. If biomembranes are subjected to persistent tensions, an unstable (nanoscale) hole will emerge at some time to cause rupture. Because of the large energy required to create a hole, thermal activation appears to be requisite for initiating a hole and the activation energy is expected to depend significantly on mechanical tension. Although models exist for the kinetic process of hole nucleation in tense membranes, studies of membrane survival have failed to cover the ranges of tension and lifetime needed to critically examine nucleation theory. Hence, rupturing giant ({approx}20 {mu}m) membrane vesicles ultra-slowly to ultra-quickly with slow to fast ramps of tension, we demonstrate a method to directly quantify kinetic rates at which unstable holes form in fluid membranes, at the same time providing a range of kinetic rates from <0.01 to >100 s{sup -1}. Measuring lifetimes of many hundreds of vesicles, each tensed by precision control of micropipette suction, we have determined the rates of failure for vesicles made from several synthetic phospholipids plus 1:1 mixtures of phospho- and sphingo-lipids with cholesterol, all of which represent prominent constituents of eukaryotic cell membranes. Plotted on a logarithmic scale, the failure rates for vesicles are found to rise dramatically with an increase in tension. Converting the experimental profiles of kinetic rates into changes of activation energy versus tension, we show that the results closely match expressions for thermal activation derived from a combination of meso-scale theory and molecular-scale simulations of hole formation. Moreover, we demonstrate a generic approach to transform analytical fits of activation energies obtained from rupture experiments into energy landscapes characterizing the

  18. Packing in protein cores

    Science.gov (United States)

    Gaines, J. C.; Clark, A. H.; Regan, L.; O'Hern, C. S.

    2017-07-01

    Proteins are biological polymers that underlie all cellular functions. The first high-resolution protein structures were determined by x-ray crystallography in the 1960s. Since then, there has been continued interest in understanding and predicting protein structure and stability. It is well-established that a large contribution to protein stability originates from the sequestration from solvent of hydrophobic residues in the protein core. How are such hydrophobic residues arranged in the core; how can one best model the packing of these residues, and are residues loosely packed with multiple allowed side chain conformations or densely packed with a single allowed side chain conformation? Here we show that to properly model the packing of residues in protein cores it is essential that amino acids are represented by appropriately calibrated atom sizes, and that hydrogen atoms are explicitly included. We show that protein cores possess a packing fraction of φ ≈ 0.56 , which is significantly less than the typically quoted value of 0.74 obtained using the extended atom representation. We also compare the results for the packing of amino acids in protein cores to results obtained for jammed packings from discrete element simulations of spheres, elongated particles, and composite particles with bumpy surfaces. We show that amino acids in protein cores pack as densely as disordered jammed packings of particles with similar values for the aspect ratio and bumpiness as found for amino acids. Knowing the structural properties of protein cores is of both fundamental and practical importance. Practically, it enables the assessment of changes in the structure and stability of proteins arising from amino acid mutations (such as those identified as a result of the massive human genome sequencing efforts) and the design of new folded, stable proteins and protein-protein interactions with tunable specificity and affinity.

  19. Sterile neutrino oscillations in core-collapse supernova simulations

    CERN Document Server

    Warren, MacKenzie L; Mathews, Grant; Hidaka, Jun; Kajino, Toshitaka

    2014-01-01

    We have made core-collapse supernova simulations that allow oscillations between electron neutrinos (or their anti particles) with right-handed sterile neutrinos. We have considered a range of mixing angles and sterile neutrino masses including those consistent with sterile neutrinos as a dark matter candidate. We examine whether such oscillations can impact the core bounce and shock reheating in supernovae. We identify the optimum ranges of mixing angles and masses that can dramatically enhance the supernova explosion by efficiently transporting electron anti-neutrinos from the core to behind the shock where they provide additional heating leading to much larger explosion kinetic energies. We show that an interesting oscillation in the neutrino luminosity develops due to a cycle of depletion of the neutrino density by conversion to sterile neutrinos that shuts off the conversion, followed by a replenished neutrino density as neutrinos transport through the core.

  20. Inner core structure behind the PKP core phase triplication

    NARCIS (Netherlands)

    Blom, Nienke A.; Deuss, Arwen; Paulssen, Hanneke; Waszek, Lauren

    2015-01-01

    The structure of the Earth's inner core is not well known between depths of ∼100–200 km beneath the inner core boundary. This is a result of the PKP core phase triplication and the existence of strong precursors to PKP phases, which hinder the measurement of inner core compressional PKIKP waves at e

  1. Inner core structure behind the PKP core phase triplication

    NARCIS (Netherlands)

    Blom, Nienke A.; Deuss, Arwen; Paulssen, Hanneke; Waszek, Lauren

    The structure of the Earth's inner core is not well known between depths of ∼100–200 km beneath the inner core boundary. This is a result of the PKP core phase triplication and the existence of strong precursors to PKP phases, which hinder the measurement of inner core compressional PKIKP waves at

  2. Apparent Dissolution Kinetics of Diatomite in Alkaline Solution

    Institute of Scientific and Technical Information of China (English)

    DU Gaoxiang; L(U) Guocheng; HE Xuwen

    2013-01-01

    The dissolution kinetics of diatomite in alkaline solution is the theoretical basis for the process optimization of alkali-diatomite reaction and its applications.In this study,the dissolution kinetics of diatomite in NaOH solution is investigated.The results indicate that the dissolution reaction fits well the unreacted shrinking core model for solid-liquid heterogeneous reactions.The apparent reaction order for NaOH is 2 and the apparent activation energy for the reaction (Ea) is 28.06 kJ.mol-1.The intra-particle diffusion through the sodium silicate layer is the rate-controlling step.When the dissolution reaction occurs at the interface of unreacted diatomite solid core,the diffusion in the trans-layer (the liquid film around the wetted particle) reduces the rate of whole dissolution process.

  3. The Role of Discs in the Collapse and Fragmentation of Prestellar Cores

    CERN Document Server

    Lomax, O; Hubber, D A

    2015-01-01

    Disc fragmentation provides an important mechanism for producing low mass stars in prestellar cores. Here, we describe Smoothed Particle Hydrodynamics simulations which show how populations of prestellar cores evolve into stars. We find the observed masses and multiplicities of stars can be recovered under certain conditions. First, protostellar feedback from a star must be episodic. The continuous accretion of disc material on to a central protostar results in local temperatures which are too high for disc fragmentation. If, however, the accretion occurs in intense outbursts, separated by a downtime of $\\sim10^4\\,\\mathrm{years}$, gravitational instabilities can develop and the disc can fragment. Second, a significant amount of the cores' internal kinetic energy should be in solenoidal turbulent modes. Cores with less than a third of their kinetic energy in solenoidal modes have insufficient angular momentum to form fragmenting discs. In the absence of discs, cores can fragment but results in a top heavy dist...

  4. Integrating folding kinetics and protein function: biphasic kinetics and dual binding specificity in a WW domain.

    Science.gov (United States)

    Karanicolas, John; Brooks, Charles L

    2004-03-09

    Because of the association of beta-sheet formation with the initiation and propagation of amyloid diseases, model systems have been sought to further our understanding of this process. WW domains have been proposed as one such model system. Whereas the folding of the WW domains from human Yes-associated protein (YAP) and Pin have been shown to obey single-exponential kinetics, the folding of the WW domain from formin-binding protein (FBP) 28 has been shown to proceed via biphasic kinetics. From an analysis of free-energy landscapes from atomic-level molecular dynamics simulations, the biphasic folding kinetics observed in the FBP WW domain may be traced to the ability of this WW domain to adopt two slightly different forms of packing in its hydrophobic core. This conformational change is propagated along the peptide backbone and affects the position of a tryptophan residue shown in other WW domains to play a key role in binding. The WW domains of Pin and YAP do not support more than one type of packing each, leading to monophasic folding kinetics. The ability of the FBP WW domain to assume two different types of packing may, in turn, explain the capacity of this WW domain to bind two classes of ligand, a property that is not shared by other WW domains. These findings lead to the hypothesis that lability with respect to conformations separated by an observable barrier as a requirement for function is incompatible with the ability of a protein to fold via single-exponential kinetics.

  5. Kinetic theory and long range correlations in moderately dense gases

    Energy Technology Data Exchange (ETDEWEB)

    Petrosky, T.; Prigogine, I. [Univ. of Texas, Austin, TX (United States)

    1997-01-01

    The complex spectral representation of the Liouville operator is applied to moderately dense gases interacting through hard-core potentials in arbitrary d-dimensional spaces. It is shown that Markovian kinetic equations exist for all d. This provides an answer to the long standing question do kinetic equations exist in two dimensional systems. The non-Markovian effects, such as the long-time tails for arbitrary n-mode coupling, are estimated by superposition of the Markovian evolutions in each subspace as introduced in our spectral decomposition. The long-time tail effects invalidate the traditional kinetic theory based on a truncation of BBGKY hierarchy for d < 4, as well as the Green-Kubo formalism, as there appear contributions of order t{sup -1}, t{sup -{1/2}},... coming from multiple mode-mode couplings even for d = 3.

  6. Kinetic distance and kinetic maps from molecular dynamics simulation

    CERN Document Server

    Noe, Frank

    2015-01-01

    Characterizing macromolecular kinetics from molecular dynamics (MD) simulations requires a distance metric that can distinguish slowly-interconverting states. Here we build upon diffusion map theory and define a kinetic distance for irreducible Markov processes that quantifies how slowly molecular conformations interconvert. The kinetic distance can be computed given a model that approximates the eigenvalues and eigenvectors (reaction coordinates) of the MD Markov operator. Here we employ the time-lagged independent component analysis (TICA). The TICA components can be scaled to provide a kinetic map in which the Euclidean distance corresponds to the kinetic distance. As a result, the question of how many TICA dimensions should be kept in a dimensionality reduction approach becomes obsolete, and one parameter less needs to be specified in the kinetic model construction. We demonstrate the approach using TICA and Markov state model (MSM) analyses for illustrative models, protein conformation dynamics in bovine...

  7. GREEN CORE HOUSE

    Directory of Open Access Journals (Sweden)

    NECULAI Oana

    2017-05-01

    Full Text Available The Green Core House is a construction concept with low environmental impact, having as main central element a greenhouse. The greenhouse has the innovative role to use the biomass energy provided by plants to save energy. Although it is the central piece, the greenhouse is not the most innovative part of the Green Core House, but the whole building ensemble because it integrates many other sustainable systems as "waste purification systems", "transparent photovoltaic panels" or "double skin façades".

  8. Birefringent hollow core fibers

    DEFF Research Database (Denmark)

    Roberts, John

    2007-01-01

    Hollow core photonic crystal fiber (HC-PCF), fabricated according to a nominally non-birefringent design, shows a degree of un-controlled birefringence or polarization mode dispersion far in excess of conventional non polarization maintaining fibers. This can degrade the output pulse in many...... and an increased overlap between the polarization modes at the glass interfaces. The interplay between these effects leads to a wavelength for optimum polarization maintenance, lambda(PM), which is detuned from the wavelength of highest birefringence. By a suitable fiber design involving antiresonance of the core...

  9. Birefringent hollow core fibers

    DEFF Research Database (Denmark)

    Roberts, John

    2007-01-01

    Hollow core photonic crystal fiber (HC-PCF), fabricated according to a nominally non-birefringent design, shows a degree of un-controlled birefringence or polarization mode dispersion far in excess of conventional non polarization maintaining fibers. This can degrade the output pulse in many...... and an increased overlap between the polarization modes at the glass interfaces. The interplay between these effects leads to a wavelength for optimum polarization maintenance, lambda(PM), which is detuned from the wavelength of highest birefringence. By a suitable fiber design involving antiresonance of the core...

  10. Kinetics of tetrataenite disordering

    Energy Technology Data Exchange (ETDEWEB)

    Dos Santos, E., E-mail: edisanfi@cbpf.br [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro (Brazil); Gattacceca, J.; Rochette, P. [Centre Européen de Recherche et d’Enseignement des Géosciences de l’Environnement, UM34, CNRS/Aix-Marseille University, Aix-en-Provence (France); Fillion, G. [Laboratoire National des Champs Magnétiques Intenses (LNCMI), CNRS, UJF, 38042 Grenoble (France); Scorzelli, R.B. [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro (Brazil)

    2015-02-01

    Tetrataenite is a chemically ordered L1{sub 0}-type Fe{sub 50}Ni{sub 50} alloy detected for the first time in 1977 by {sup 57}Fe Mössbauer spectroscopy studies in iron meteorites. The thermal history of meteorites, in particular short thermal events like those associated to hypervelocity impacts, can be constrained by tracing the presence of tetrataenite or its disordering into taenite. The knowledge of the disordering kinetics of tetrataenite, that is associated with changes in its magnetic properties, is still very fragmentary so that the time–temperature history of these meteorites cannot be constrained in details. Furthermore, knowledge of disordering kinetics is important due to potential technological application of tetrataenite as a rare-earth free strong magnet. Thus, this work provides the first time–temperature data for disordering reaction of tetrataenite. We have shown that disordering is not an instantaneous process but is a kinetic limited reaction. It was shown that disordering may take place at any temperature above the order–disorder transition for L{sub 10} superstructure phase (∼320 °C) when the appropriate time-scale is considered. This result means that the apparent Curie point for tetrataenite is not an absolute property in the sense that any estimate of this parameter should be referred to a given time-scale. - Highlights: • The first time–temperature data for tetrataenite disordering reaction is provided. • Previous works does not give a complete picture of tetrataenite disordering. • Apparent Curie temperature of tetrataenite should be referred to a time-scale. • Tetrataenite can be used as a probe to detect thermal/shock events recorded in meteorites.

  11. Chemical kinetics modeling

    Energy Technology Data Exchange (ETDEWEB)

    Westbrook, C.K.; Pitz, W.J. [Lawrence Livermore National Laboratory, CA (United States)

    1993-12-01

    This project emphasizes numerical modeling of chemical kinetics of combustion, including applications in both practical combustion systems and in controlled laboratory experiments. Elementary reaction rate parameters are combined into mechanisms which then describe the overall reaction of the fuels being studied. Detailed sensitivity analyses are used to identify those reaction rates and product species distributions to which the results are most sensitive and therefore warrant the greatest attention from other experimental and theoretical research programs. Experimental data from a variety of environments are combined together to validate the reaction mechanisms, including results from laminar flames, shock tubes, flow systems, detonations, and even internal combustion engines.

  12. Stochastic Electrochemical Kinetics

    CERN Document Server

    Beruski, O

    2016-01-01

    A model enabling the extension of the Stochastic Simulation Algorithm to electrochemical systems is proposed. The physical justifications and constraints for the derivation of a chemical master equation are provided and discussed. The electrochemical driving forces are included in the mathematical framework, and equations are provided for the associated electric responses. The implementation for potentiostatic and galvanostatic systems is presented, with results pointing out the stochastic nature of the algorithm. The electric responses presented are in line with the expected results from the theory, providing a new tool for the modeling of electrochemical kinetics.

  13. Essential ingredients in core-collapse supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Hix, W. Raphael [Physics Division, Oak Ridge National Laboratory, Oak Ridge TN 37831-6354 (United States); Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996-1200 (United States); Lentz, Eric J.; Chertkow, M. Austin; Harris, J. Austin [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996-1200 (United States); Endeve, Eirik [Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge TN 37831-6008 (United States); Baird, Mark [Reactor and Nuclear Systems Division, Oak Ridge National Laboratory, Oak Ridge TN 37831-6003 (United States); Messer, O. E. Bronson [Physics Division, Oak Ridge National Laboratory, Oak Ridge TN 37831-6354 (United States); Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996-1200 (United States); Center for Computational Sciences, Oak Ridge National Laboratory, Oak Ridge TN 37831-6008 (United States); Mezzacappa, Anthony [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996-1200 (United States); Joint Institute for Computational Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6173 (United States); Bruenn, Stephen [Department of Physics, Florida Atlantic University, 777 W Glades Road, Boca Raton, FL 33431-0991 (United States); Blondin, John [Department of Physics, North Carolina State University, Raleigh, NC 27695-8202 (United States)

    2014-04-15

    Carrying 10{sup 44} joules of kinetic energy and a rich mix of newly synthesized atomic nuclei, core-collapse supernovae are the preeminent foundries of the nuclear species which make up our solar system and ourselves. Signaling the inevitable death of a massive star, and the birth of a neutron star or black hole, core-collapse supernovae combine physics over a wide range in spatial scales, from kilometer-sized hydrodynamic motions (eventually growing to gigameter scale) down to femtometer-scale nuclear reactions. We will discuss our emerging understanding of the convectively-unstable, neutrino-driven explosion mechanism, based on increasingly realistic neutrino radiation hydrodynamic simulations that include progressively better nuclear and particle physics. Multi-dimensional models with spectral neutrino transport from several research groups, which slowly develop successful explosions for a range of progenitors, have recently motivated changes in our understanding of the neutrino reheating mechanism. In a similar fashion, improvements in nuclear physics, most notably explorations of weak interactions on nuclei and the nuclear equation of state, continue to refine our understanding of the births of neutron stars and the supernovae that result. Recent progress on both the macroscopic and microscopic effects that affect core-collapse supernovae are discussed.

  14. Essential ingredients in core-collapse supernovae

    Directory of Open Access Journals (Sweden)

    W. Raphael Hix

    2014-03-01

    Full Text Available Carrying 1044 joules of kinetic energy and a rich mix of newly synthesized atomic nuclei, core-collapse supernovae are the preeminent foundries of the nuclear species which make up our solar system and ourselves. Signaling the inevitable death of a massive star, and the birth of a neutron star or black hole, core-collapse supernovae combine physics over a wide range in spatial scales, from kilometer-sized hydrodynamic motions (eventually growing to gigameter scale down to femtometer-scale nuclear reactions. We will discuss our emerging understanding of the convectively-unstable, neutrino-driven explosion mechanism, based on increasingly realistic neutrino radiation hydrodynamic simulations that include progressively better nuclear and particle physics. Multi-dimensional models with spectral neutrino transport from several research groups, which slowly develop successful explosions for a range of progenitors, have recently motivated changes in our understanding of the neutrino reheating mechanism. In a similar fashion, improvements in nuclear physics, most notably explorations of weak interactions on nuclei and the nuclear equation of state, continue to refine our understanding of the births of neutron stars and the supernovae that result. Recent progress on both the macroscopic and microscopic effects that affect core-collapse supernovae are discussed.

  15. Investigation of EAS cores

    Science.gov (United States)

    Shaulov, S. B.; Beyl, P. F.; Beysembaev, R. U.; Beysembaeva, E. A.; Bezshapov, S. P.; Borisov, A. S.; Cherdyntceva, K. V.; Chernyavsky, M. M.; Chubenko, A. P.; Dalkarov, O. D.; Denisova, V. G.; Erlykin, A. D.; Kabanova, N. V.; Kanevskaya, E. A.; Kotelnikov, K. A.; Morozov, A. E.; Mukhamedshin, R. A.; Nam, R. A.; Nesterova, N. M.; Nikolskaya, N. M.; Pavluchenko, V. P.; Piskal, V. V.; Puchkov, V. S.; Pyatovsky, S. E.; Ryabov, V. A.; Sadykov, T. Kh.; Schepetov, A. L.; Smirnova, M. D.; Stepanov, A. V.; Uryson, A. V.; Vavilov, Yu. N.; Vildanov, N. G.; Vildanova, L. I.; Zayarnaya, I. S.; Zhanceitova, J. K.; Zhukov, V. V.

    2017-06-01

    The development of nuclear-electromagnetic cascade models in air in the late forties have shown informational content of the study of cores of extensive air showers (EAS). These investigations were the main goal in different experiments which were carried out over many years by a variety of methods. Outcomes of such investigations obtained in the HADRON experiment using an X-ray emulsion chamber (XREC) as a core detector are considered. The Ne spectrum of EAS associated with γ-ray families, spectra of γ-rays (hadrons) in EAS cores and the Ne dependence of the muon number, ⟨Nμ⟩, in EAS with γ-ray families are obtained for the first time at energies of 1015-1017 eV with this method. A number of new effects were observed, namely, an abnormal scaling violation in hadron spectra which are fundamentally different from model predictions, an excess of muon number in EAS associated with γ-ray families, and the penetrating component in EAS cores. It is supposed that the abnormal behavior of γ-ray spectra and Ne dependence of the muon number are explained by the emergence of a penetrating component in the 1st PCR spectrum `knee' range. Nuclear and astrophysical explanations of the origin of the penetrating component are discussed. The necessity of considering the contribution of a single close cosmic-ray source to explain the PCR spectrum in the knee range is noted.

  16. Some Core Contested Concepts

    Science.gov (United States)

    Chomsky, Noam

    2015-01-01

    Core concepts of language are highly contested. In some cases this is legitimate: real empirical and conceptual issues arise. In other cases, it seems that controversies are based on misunderstanding. A number of crucial cases are reviewed, and an approach to language is outlined that appears to have strong conceptual and empirical motivation, and…

  17. Looking for Core Values

    Science.gov (United States)

    Carter, Margie

    2010-01-01

    People who view themselves as leaders, not just managers or teachers, are innovators who focus on clarifying core values and aligning all aspects of the organization with these values to grow their vision. A vision for an organization can't be just one person's idea. Visions grow by involving people in activities that help them name and create…

  18. Nucleosome Core Particle

    Science.gov (United States)

    1997-01-01

    Nucleosome Core Particle grown on STS-81. The fundamental structural unit of chromatin and is the basis for organization within the genome by compaction of DNA within the nucleus of the cell and by making selected regions of chromosomes available for transcription and replication. Principal Investigator's are Dr. Dan Carter and Dr. Gerard Bunick of New Century Pharmaceuticals.

  19. Investigation of EAS cores

    Directory of Open Access Journals (Sweden)

    Shaulov S.B.

    2017-01-01

    Full Text Available The development of nuclear-electromagnetic cascade models in air in the late forties have shown informational content of the study of cores of extensive air showers (EAS. These investigations were the main goal in different experiments which were carried out over many years by a variety of methods. Outcomes of such investigations obtained in the HADRON experiment using an X-ray emulsion chamber (XREC as a core detector are considered. The Ne spectrum of EAS associated with γ-ray families, spectra of γ-rays (hadrons in EAS cores and the Ne dependence of the muon number, ⟨Nμ⟩, in EAS with γ-ray families are obtained for the first time at energies of 1015–1017 eV with this method. A number of new effects were observed, namely, an abnormal scaling violation in hadron spectra which are fundamentally different from model predictions, an excess of muon number in EAS associated with γ-ray families, and the penetrating component in EAS cores. It is supposed that the abnormal behavior of γ-ray spectra and Ne dependence of the muon number are explained by the emergence of a penetrating component in the 1st PCR spectrum ‘knee’ range. Nuclear and astrophysical explanations of the origin of the penetrating component are discussed. The necessity of considering the contribution of a single close cosmic-ray source to explain the PCR spectrum in the knee range is noted.

  20. Modeling Core Collapse Supernovae

    Science.gov (United States)

    Mezzacappa, Anthony

    2017-01-01

    Core collapse supernovae, or the death throes of massive stars, are general relativistic, neutrino-magneto-hydrodynamic events. The core collapse supernova mechanism is still not in hand, though key components have been illuminated, and the potential for multiple mechanisms for different progenitors exists. Core collapse supernovae are the single most important source of elements in the Universe, and serve other critical roles in galactic chemical and thermal evolution, the birth of neutron stars, pulsars, and stellar mass black holes, the production of a subclass of gamma-ray bursts, and as potential cosmic laboratories for fundamental nuclear and particle physics. Given this, the so called ``supernova problem'' is one of the most important unsolved problems in astrophysics. It has been fifty years since the first numerical simulations of core collapse supernovae were performed. Progress in the past decade, and especially within the past five years, has been exponential, yet much work remains. Spherically symmetric simulations over nearly four decades laid the foundation for this progress. Two-dimensional modeling that assumes axial symmetry is maturing. And three-dimensional modeling, while in its infancy, has begun in earnest. I will present some of the recent work from the ``Oak Ridge'' group, and will discuss this work in the context of the broader work by other researchers in the field. I will then point to future requirements and challenges. Connections with other experimental, observational, and theoretical efforts will be discussed, as well.

  1. The Earth's Core.

    Science.gov (United States)

    Jeanloz, Raymond

    1983-01-01

    The nature of the earth's core is described. Indirect evidence (such as that determined from seismological data) indicates that it is an iron alloy, solid toward its center but otherwise liquid. Evidence also suggests that it is the turbulent flow of the liquid that generates the earth's magnetic field. (JN)

  2. Some Core Contested Concepts

    Science.gov (United States)

    Chomsky, Noam

    2015-01-01

    Core concepts of language are highly contested. In some cases this is legitimate: real empirical and conceptual issues arise. In other cases, it seems that controversies are based on misunderstanding. A number of crucial cases are reviewed, and an approach to language is outlined that appears to have strong conceptual and empirical motivation, and…

  3. Languages for Dublin Core.

    Science.gov (United States)

    Baker, Thomas

    1998-01-01

    Focusing on languages for the Dublin Core, examines the experience of some related ways to seek semantic interoperability through simplicity: planned languages, interlingua constructs, and pidgins. Also defines the conceptual and organizational problem of maintaining a metadata standard in multiple languages. (AEF)

  4. Core calculations of JMTR

    Energy Technology Data Exchange (ETDEWEB)

    Nagao, Yoshiharu [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment

    1998-03-01

    In material testing reactors like the JMTR (Japan Material Testing Reactor) of 50 MW in Japan Atomic Energy Research Institute, the neutron flux and neutron energy spectra of irradiated samples show complex distributions. It is necessary to assess the neutron flux and neutron energy spectra of an irradiation field by carrying out the nuclear calculation of the core for every operation cycle. In order to advance core calculation, in the JMTR, the application of MCNP to the assessment of core reactivity and neutron flux and spectra has been investigated. In this study, in order to reduce the time for calculation and variance, the comparison of the results of the calculations by the use of K code and fixed source and the use of Weight Window were investigated. As to the calculation method, the modeling of the total JMTR core, the conditions for calculation and the adopted variance reduction technique are explained. The results of calculation are shown. Significant difference was not observed in the results of neutron flux calculations according to the difference of the modeling of fuel region in the calculations by K code and fixed source. The method of assessing the results of neutron flux calculation is described. (K.I.)

  5. The core and cosmopolitans

    DEFF Research Database (Denmark)

    Dahlander, Linus; Frederiksen, Lars

    2012-01-01

    Users often interact and help each other solve problems in communities, but few scholars have explored how these relationships provide opportunities to innovate. We analyze the extent to which people positioned within the core of a community as well as people that are cosmopolitans positioned...

  6. Schumpeter's core works revisited

    DEFF Research Database (Denmark)

    Andersen, Esben Sloth

    2012-01-01

    This paper organises Schumpeter’s core books in three groups: the programmatic duology,the evolutionaryeconomic duology,and the socioeconomic synthesis. By analysing these groups and their interconnections from the viewpoint of modern evolutionaryeconomics,the paper summarises resolved problems...

  7. Adult educators' core competences

    DEFF Research Database (Denmark)

    Wahlgren, Bjarne

    2016-01-01

    environment as well as the kind of adult education concerned (e.g. basic education, work-related education etc.). However, it seems that it is possible to identify certain competence requirements which transcend national, cultural and functional boundaries. This research note summarises these common or “core...

  8. Adult educators' core competences

    DEFF Research Database (Denmark)

    Wahlgren, Bjarne

    2016-01-01

    environment as well as the kind of adult education concerned (e.g. basic education, work-related education etc.). However, it seems that it is possible to identify certain competence requirements which transcend national, cultural and functional boundaries. This research note summarises these common or “core...

  9. Development and Investigation of Reactivity Measurement Methods in Subcritical Cores

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Johanna

    2005-05-01

    Subcriticality measurements during core loading and in future accelerator driven systems have a clear safety relevance. In this thesis two subcriticality methods are treated: the Feynman-alpha and the source modulation method. The Feynman-alpha method is a technique to determine the reactivity from the relative variance of the detector counts during a measurement period. The period length is varied to get the full time dependence of the variance-to-mean. The corresponding theoretical formula was known only with stationary sources. In this thesis, due to its relevance for novel reactivity measurement methods, the Feynman-alpha formulae for pulsed sources for both the stochastic and the deterministic cases are treated. Formulae neglecting as well as including the delayed neutrons are derived. The formulae neglecting delayed neutrons are experimentally verified with quite good agreement. The second reactivity measurement technique investigated in this thesis is the so-called source modulation technique. The theory of the method was elaborated on the assumption of point kinetics, but in practice the method will be applied by using the signal from a single local neutron detector. Applicability of the method therefore assumes point kinetic behaviour of the core. Hence, first the conditions of the point kinetic behaviour of subcritical cores was investigated. After that the performance of the source modulation technique in the general case as well as and in the limit of exact point kinetic behaviour was examined. We obtained the unexpected result that the method has a finite, non-negligible error even in the limit of point kinetic behaviour, and a substantial error in the operation range of future accelerator driven subcritical reactors (ADS). In practice therefore the method needs to be calibrated by some other method for on-line applications.

  10. Kinetics of coal pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Seery, D.J.; Freihaut, J.D.; Proscia, W.M. (United Technologies Research Center, East Hartford, CT (USA)); Howard, J.B.; Peters, W.; Hsu, J.; Hajaligol, M.; Sarofim, A. (Massachusetts Inst. of Tech., Cambridge, MA (USA)); Jenkins, R.; Mallin, J.; Espindola-Merin, B. (Pennsylvania State Univ., University Park, PA (USA)); Essenhigh, R.; Misra, M.K. (Ohio State Univ., Columbus, OH (USA))

    1989-07-01

    This report contains results of a coordinated, multi-laboratory investigation of coal devolatilization. Data is reported pertaining to the devolatilization for bituminous coals over three orders of magnitude in apparent heating rate (100 to 100,000 + {degree}C/sec), over two orders of magnitude in particle size (20 to 700 microns), final particle temperatures from 400 to 1600{degree}C, heat transfer modes ranging from convection to radiative, ambient pressure ranging from near vacuum to one atmosphere pressure. The heat transfer characteristics of the reactors are reported in detail. It is assumed the experimental results are to form the basis of a devolatilization data base. Empirical rate expressions are developed for each phase of devolatilization which, when coupled to an awareness of the heat transfer rate potential of a particular devolatilization reactor, indicate the kinetics emphasized by a particular system reactor plus coal sample. The analysis indicates the particular phase of devolatilization that will be emphasized by a particular reactor type and, thereby, the kinetic expressions appropriate to that devolatilization system. Engineering rate expressions are developed from the empirical rate expressions in the context of a fundamental understanding of coal devolatilization developed in the course of the investigation. 164 refs., 223 figs., 44 tabs.

  11. Sequential reactions directed by core/shell catalytic reactors.

    Science.gov (United States)

    Wei, Yanhu; Soh, Siowling; Apodaca, Mario M; Kim, Jiwon; Grzybowski, Bartosz A

    2010-04-09

    Millimeter-sized reactor particles made of permeable polymer doped with catalysts arranged in a core/shell fashion direct sequences of chemical reactions (e.g., alkyne coupling followed by hydrogenation or hydrosilylation followed by hydrogenation). Spatial compartmentalization of catalysts coupled with the diffusion of substrates controls reaction order and avoids formation of byproducts. The experimentally observed yields of reaction sequences are reproduced by a theoretical model, which accounts for the reaction kinetics and the diffusion of the species involved.

  12. Chemical kinetics of gas reactions

    CERN Document Server

    Kondrat'Ev, V N

    2013-01-01

    Chemical Kinetics of Gas Reactions explores the advances in gas kinetics and thermal, photochemical, electrical discharge, and radiation chemical reactions. This book is composed of 10 chapters, and begins with the presentation of general kinetic rules for simple and complex chemical reactions. The next chapters deal with the experimental methods for evaluating chemical reaction mechanisms and some theories of elementary chemical processes. These topics are followed by discussions on certain class of chemical reactions, including unimolecular, bimolecular, and termolecular reactions. The rema

  13. Adsorption analysis equilibria and kinetics

    CERN Document Server

    Do, Duong D

    1998-01-01

    This book covers topics of equilibria and kinetics of adsorption in porous media. Fundamental equilibria and kinetics are dealt with for homogeneous as well as heterogeneous particles. Five chapters of the book deal with equilibria and eight chapters deal with kinetics. Single component as well as multicomponent systems are discussed. In kinetics analysis, we deal with the various mass transport processes and their interactions inside a porous particle. Conventional approaches as well as the new approach using Maxwell-Stefan equations are presented. Various methods to measure diffusivity, such

  14. Stochastic Kinetics of Nascent RNA

    Science.gov (United States)

    Xu, Heng; Skinner, Samuel O.; Sokac, Anna Marie; Golding, Ido

    2016-09-01

    The stochastic kinetics of transcription is typically inferred from the distribution of RNA numbers in individual cells. However, cellular RNA reflects additional processes downstream of transcription, hampering this analysis. In contrast, nascent (actively transcribed) RNA closely reflects the kinetics of transcription. We present a theoretical model for the stochastic kinetics of nascent RNA, which we solve to obtain the probability distribution of nascent RNA per gene. The model allows us to evaluate the kinetic parameters of transcription from single-cell measurements of nascent RNA. The model also predicts surprising discontinuities in the distribution of nascent RNA, a feature which we verify experimentally.

  15. Application of Core Dynamics Modeling to Core-Mantle Interactions

    Science.gov (United States)

    Kuang, Weijia

    2003-01-01

    Observations have demonstrated that length of day (LOD) variation on decadal time scales results from exchange of axial angular momentum between the solid mantle and the core. There are in general four core-mantle interaction mechanisms that couple the core and the mantle. Of which, three have been suggested likely the dominant coupling mechanism for the decadal core-mantle angular momentum exchange, namely, gravitational core-mantle coupling arising from density anomalies in the mantle and in the core (including the inner core), the electromagnetic coupling arising from Lorentz force in the electrically conducting lower mantle (e.g. D-layer), and the topographic coupling arising from non-hydrostatic pressure acting on the core-mantle boundary (CMB) topography. In the past decades, most effort has been on estimating the coupling torques from surface geomagnetic observations (kinematic approach), which has provided insights on the core dynamical processes. In the meantime, it also creates questions and concerns on approximations in the studies that may invalidate the corresponding conclusions. The most serious problem is perhaps the approximations that are inconsistent with dynamical processes in the core, such as inconsistencies between the core surface flow beneath the CMB and the CMB topography, and that between the D-layer electric conductivity and the approximations on toroidal field at the CMB. These inconsistencies can only be addressed with numerical core dynamics modeling. In the past few years, we applied our MoSST (Modular, Scalable, Self-consistent and Three-dimensional) core dynamics model to study core-mantle interactions together with geodynamo simulation, aiming at assessing the effect of the dynamical inconsistencies in the kinematic studies on core-mantle coupling torques. We focus on topographic and electromagnetic core-mantle couplings and find that, for the topographic coupling, the consistency between the core flow and the CMB topography is

  16. Kinetic transport simulation of energetic particles

    Science.gov (United States)

    Sheng, He; Waltz, R. E.

    2016-05-01

    A kinetic transport code (EPtran) is developed for the transport of the energetic particles (EPs). The EPtran code evolves the EP distribution function in radius, energy, and pitch angle phase space (r, E, λ) to steady state with classical slowing down, pitch angle scattering, as well as radial and energy transport of the injected EPs (neutral beam injection (NBI) or fusion alpha). The EPtran code is illustrated by treating the transport of NBI fast ions from high-n ITG/TEM micro-turbulence and EP driven unstable low-n Alfvén eigenmodes (AEs) in a well-studied DIII-D NBI heated discharge with significant AE central core loss. The kinetic transport code results for this discharge are compared with previous study using a simple EP density moment transport code ALPHA (R.E. Waltz and E.M. Bass 2014 Nucl. Fusion 54 104006). The dominant EP-AE transport is treated with a local stiff critical EP density (or equivalent pressure) gradient radial transport model modified to include energy-dependence and the nonlocal effects EP drift orbits. All previous EP transport models assume that the EP velocity space distribution function is not significantly distorted from the classical ‘no transport’ slowing down distribution. Important transport distortions away from the slowing down EP spectrum are illustrated by a focus on the coefficient of convection: EP energy flux divided by the product of EP average energy and EP particle flux.

  17. Coal char oxidation kinetics in air medium

    Directory of Open Access Journals (Sweden)

    Korotkikh Alexander G.

    2017-01-01

    Full Text Available Study of oxidation kinetics for three types of coal char with different carbon content in air is presented. The coal char powders of anthracite, bituminous T-grade coal and 2B-grade lignite with particle size less than 80 μm were tested. The coal char oxidation was researched by isothermal method via simultaneous TG-DSC analyzer Netzsch STA 449 Jupiter F3 in the temperature range of 1000–1200 °C. Measurements were carried out at ambient pressure. Volumetric flow rate of oxidizing medium into analyser chamber was 250 ml/min. Flow consisted of air and argon with volumetric ratio 24/1. Carbon average rate of oxidation reaction at each temperature were defined based on experimental results. Kinetic constants (the frequency factor and activation energy were defined for Arrhenius equation modified with three submodels: volumetric model, shrinking core model and random pore model. The activation energy values for anthracite are 1,6-1,7 times higher than for chars of bituminous coal and lignite.

  18. Flow Dynamic Analysis of Core Shooting Process through Experiment and Multiphase Modeling

    Directory of Open Access Journals (Sweden)

    Changjiang Ni

    2016-01-01

    Full Text Available Core shooting process is the most widely used technique to make sand cores and it plays an important role in the quality of sand cores as well as the manufacture of complicated castings in metal casting industry. In this paper, the flow behavior of sand particles in the core box was investigated synchronously with transparent core box, high-speed camera, and pressure measuring system. The flow pattern of sand particles in the shooting head of the core shooting machine was reproduced with various colored core sand layers. Taking both kinetic and frictional stress into account, a kinetic-frictional constitutive correlation was established to describe the internal momentum transfer in the solid phase. Two-fluid model (TFM simulations with turbulence model were then performed and good agreement was achieved between the experimental and simulation results on the flow behavior of sand particles in both the shooting head and the core box. Based on the experimental and simulation results, the flow behavior of sand particles in the core box, the formation of “dead zone” in the shooting head, and the effect of drag force were analyzed in terms of sand volume fraction (αs, sand velocity (Vs, and pressure variation (P.

  19. USGS Core Research Center (CRC) Collection of Core

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Core Research Center (CRC) was established in 1974 by the U.S. Geological Survey (USGS) to preserve valuable rock cores for use by scientists and educators from...

  20. Ice Cores of the National Ice Core Laboratory

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The U.S. National Ice Core Laboratory (NICL) is a facility for storing, curating, and studying ice cores recovered from the polar regions of the world. It provides...

  1. Kinetic transport in crystals

    CERN Document Server

    Marklof, Jens

    2009-01-01

    One of the central challenges in kinetic theory is the derivation of macroscopic evolution equations--describing, for example, the dynamics of an electron gas--from the underlying fundamental microscopic laws of classical or quantum mechanics. An iconic mathematical model in this research area is the Lorentz gas, which describes an ensemble of non-interacting point particles in an infinite array of spherical scatterers. In the case of a disordered scatterer configuration, the classical results by Gallavotti, Spohn and Boldrighini-Bunimovich-Sinai show that the time evolution of a macroscopic particle cloud is governed, in the limit of small scatterer density (Boltzmann-Grad limit), by the linear Boltzmann equation. In this lecture I will discuss the recent discovery that for a periodic configuration of scatterers the linear Boltzmann equation fails, and the random flight process that emerges in the Boltzmann-Grad limit is substantially more complicated. The key ingredient in the description of the limiting st...

  2. Kinetic inductance magnetometer.

    Science.gov (United States)

    Luomahaara, Juho; Vesterinen, Visa; Grönberg, Leif; Hassel, Juha

    2014-09-10

    Sensing ultra-low magnetic fields has various applications in the fields of science, medicine and industry. There is a growing need for a sensor that can be operated in ambient environments where magnetic shielding is limited or magnetic field manipulation is involved. To this end, here we demonstrate a new magnetometer with high sensitivity and wide dynamic range. The device is based on the current nonlinearity of superconducting material stemming from kinetic inductance. A further benefit of our approach is of extreme simplicity: the device is fabricated from a single layer of niobium nitride. Moreover, radio frequency multiplexing techniques can be applied, enabling the simultaneous readout of multiple sensors, for example, in biomagnetic measurements requiring data from large sensor arrays.

  3. Kinetics of Social Contagion

    Science.gov (United States)

    Ruan, Zhongyuan; Iñiguez, Gerardo; Karsai, Márton; Kertész, János

    2015-11-01

    Diffusion of information, behavioral patterns or innovations follows diverse pathways depending on a number of conditions, including the structure of the underlying social network, the sensitivity to peer pressure and the influence of media. Here we study analytically and by simulations a general model that incorporates threshold mechanism capturing sensitivity to peer pressure, the effect of "immune" nodes who never adopt, and a perpetual flow of external information. While any constant, nonzero rate of dynamically introduced spontaneous adopters leads to global spreading, the kinetics by which the asymptotic state is approached shows rich behavior. In particular, we find that, as a function of the immune node density, there is a transition from fast to slow spreading governed by entirely different mechanisms. This transition happens below the percolation threshold of network fragmentation, and has its origin in the competition between cascading behavior induced by adopters and blocking due to immune nodes. This change is accompanied by a percolation transition of the induced clusters.

  4. Kinetics of Social Contagion

    CERN Document Server

    Ruan, Zhongyuan; Karsai, Marton; Kertesz, Janos

    2015-01-01

    Diffusion of information, behavioural patterns or innovations follows diverse pathways depending on a number of conditions, including the structure of the underlying social network, the sensitivity to peer pressure and the influence of media. Here we study analytically and by simulations a general model that incorporates threshold mechanism capturing sensitivity to peer pressure, the effect of `immune' nodes who never adopt, and a perpetual flow of external information. While any constant, non-zero rate of dynamically-introduced innovators leads to global spreading, the kinetics by which the asymptotic state is approached show rich behaviour. In particular we find that, as a function of the density of immune nodes, there is a transition from fast to slow spreading governed by entirely different mechanisms. This transition happens below the percolation threshold of fragmentation of the network, and has its origin in the competition between cascading behaviour induced by innovators and blocking of adoption due ...

  5. Core Outlet Temperature Study

    Energy Technology Data Exchange (ETDEWEB)

    Moisseytsev, A. [Argonne National Laboratory (ANL), Argonne, IL (United States); Hoffman, E. [Argonne National Laboratory (ANL), Argonne, IL (United States); Majumdar, S. [Argonne National Laboratory (ANL), Argonne, IL (United States)

    2008-07-28

    It is a known fact that the power conversion plant efficiency increases with elevation of the heat addition temperature. The higher efficiency means better utilization of the available resources such that higher output in terms of electricity production can be achieved for the same size and power of the reactor core or, alternatively, a lower power core could be used to produce the same electrical output. Since any nuclear power plant, such as the Advanced Burner Reactor, is ultimately built to produce electricity, a higher electrical output is always desirable. However, the benefits of the higher efficiency and electricity production usually come at a price. Both the benefits and the disadvantages of higher reactor outlet temperatures are analyzed in this work.

  6. Geomagnetism of earth's core

    Science.gov (United States)

    Benton, E. R.

    1983-01-01

    Instrumentation, analytical methods, and research goals for understanding the behavior and source of geophysical magnetism are reviewed. Magsat, launched in 1979, collected global magnetometer data and identified the main terrestrial magnetic fields. The data has been treated by representing the curl-free field in terms of a scalar potential which is decomposed into a truncated series of spherical harmonics. Solutions to the Laplace equation then extend the field upward or downward from the measurement level through intervening spaces with no source. Further research is necessary on the interaction between harmonics of various spatial scales. Attempts are also being made to analytically model the main field and its secular variation at the core-mantle boundary. Work is also being done on characterizing the core structure, composition, thermodynamics, energetics, and formation, as well as designing a new Magsat or a tethered satellite to be flown on the Shuttle.

  7. Geomagnetism of earth's core

    Science.gov (United States)

    Benton, E. R.

    1983-01-01

    Instrumentation, analytical methods, and research goals for understanding the behavior and source of geophysical magnetism are reviewed. Magsat, launched in 1979, collected global magnetometer data and identified the main terrestrial magnetic fields. The data has been treated by representing the curl-free field in terms of a scalar potential which is decomposed into a truncated series of spherical harmonics. Solutions to the Laplace equation then extend the field upward or downward from the measurement level through intervening spaces with no source. Further research is necessary on the interaction between harmonics of various spatial scales. Attempts are also being made to analytically model the main field and its secular variation at the core-mantle boundary. Work is also being done on characterizing the core structure, composition, thermodynamics, energetics, and formation, as well as designing a new Magsat or a tethered satellite to be flown on the Shuttle.

  8. Dynamics of core accretion

    Science.gov (United States)

    Nelson, Andrew F.; Ruffert, Maximilian

    2013-02-01

    We perform three-dimensional hydrodynamic simulations of gas flowing around a planetary core of mass Mpl = 10M⊕ embedded in a near Keplerian background flow, using a modified shearing box approximation. We assume an ideal gas behaviour following an equation of state with a fixed ratio of the specific heats, γ = 1.42, consistent with the conditions of a moderate-temperature background disc with solar composition. No radiative heating or cooling is included in the models. We employ a nested grid hydrodynamic code implementing the `Piecewise Parabolic Method' with as many as six fixed nested grids, providing spatial resolution on the finest grid comparable to the present-day diameters of Neptune and Uranus. We find that a strongly dynamically active flow develops such that no static envelope can form. The activity is not sensitive to plausible variations in the rotation curve of the underlying disc. It is sensitive to the thermodynamic treatment of the gas, as modelled by prescribed equations of state (either `locally isothermal' or `locally isentropic') and the temperature of the background disc material. The activity is also sensitive to the shape and depth of the core's gravitational potential, through its mass and gravitational softening coefficient. Each of these factors influences the magnitude and character of hydrodynamic feedback of the small-scale flow on the background, and we conclude that accurate modelling of such feedback is critical to a complete understanding of the core accretion process. The varying flow pattern gives rise to large, irregular eruptions of matter from the region around the core which return matter to the background flow: mass in the envelope at one time may not be found in the envelope at any later time. No net mass accretion into the envelope is observed over the course of the simulation and none is expected, due to our neglect of cooling. Except in cases of very rapid cooling however, as defined by locally isothermal or

  9. Some core contested concepts.

    Science.gov (United States)

    Chomsky, Noam

    2015-02-01

    Core concepts of language are highly contested. In some cases this is legitimate: real empirical and conceptual issues arise. In other cases, it seems that controversies are based on misunderstanding. A number of crucial cases are reviewed, and an approach to language is outlined that appears to have strong conceptual and empirical motivation, and to lead to conclusions about a number of significant issues that differ from some conventional beliefs.

  10. Central core disease

    Directory of Open Access Journals (Sweden)

    Jungbluth Heinz

    2007-05-01

    Full Text Available Abstract Central core disease (CCD is an inherited neuromuscular disorder characterised by central cores on muscle biopsy and clinical features of a congenital myopathy. Prevalence is unknown but the condition is probably more common than other congenital myopathies. CCD typically presents in infancy with hypotonia and motor developmental delay and is characterized by predominantly proximal weakness pronounced in the hip girdle; orthopaedic complications are common and malignant hyperthermia susceptibility (MHS is a frequent complication. CCD and MHS are allelic conditions both due to (predominantly dominant mutations in the skeletal muscle ryanodine receptor (RYR1 gene, encoding the principal skeletal muscle sarcoplasmic reticulum calcium release channel (RyR1. Altered excitability and/or changes in calcium homeostasis within muscle cells due to mutation-induced conformational changes of the RyR protein are considered the main pathogenetic mechanism(s. The diagnosis of CCD is based on the presence of suggestive clinical features and central cores on muscle biopsy; muscle MRI may show a characteristic pattern of selective muscle involvement and aid the diagnosis in cases with equivocal histopathological findings. Mutational analysis of the RYR1 gene may provide genetic confirmation of the diagnosis. Management is mainly supportive and has to anticipate susceptibility to potentially life-threatening reactions to general anaesthesia. Further evaluation of the underlying molecular mechanisms may provide the basis for future rational pharmacological treatment. In the majority of patients, weakness is static or only slowly progressive, with a favourable long-term outcome.

  11. Dimensional enhancement of kinetic energies

    DEFF Research Database (Denmark)

    Schleich, W.P.; Dahl, Jens Peder

    2002-01-01

    Simple thermodynamics considers kinetic energy to be an extensive variable which is proportional to the number N of particles. We present a quantum state of N noninteracting particles for which the kinetic energy increases quadratically with N. This enhancement effect is tied to the quantum centr...

  12. Kinetic competition during glass formation

    Energy Technology Data Exchange (ETDEWEB)

    Perepezko, J.H., E-mail: perepezk@engr.wisc.edu [University of Wisconsin-Madison, Department of Materials Science and Engineering, 1509 University Ave., Madison, WI 53706 (United States); Santhaweesuk, C.; Wang, J.Q. [University of Wisconsin-Madison, Department of Materials Science and Engineering, 1509 University Ave., Madison, WI 53706 (United States); Imhoff, S.D. [Los Alamos National Laboratory, Materials Science and Technology Div., Los Alamos, NM 87545 (United States)

    2014-12-05

    Highlights: • The kinetics of glass formation has been elucidated in an Fe and Au-base alloy. • A critical cooling rate range should be considered for glass formation. • Wedge casting, calorimetry and upquenching data are used to model TTT curves. - Abstract: For vitrification of an alloy melt during cooling there is a kinetic competition with the nucleation and growth of metastable and stable crystalline phases. Many of the measures of glass forming ability (GFA) attempt to capture some of the features of the kinetic competition, but the GFA metrics are static measures and the kinetic processes are dynamic in nature. In fact, the critical cooling rate for glass formation should be viewed in terms of a critical cooling rate range to acknowledge the stochastic nature of crystal nucleation behavior. Direct measurements of the critical cooling rate range confirm this behavior and also provide useful input for kinetics analysis. Usually kinetics analyses are based upon crystallization behavior that is measured either isothermally or upon heating to temperatures near the crystallization onset, T{sub x} and the results are extrapolated to much higher temperatures. This practice is based upon a number of assumptions about transport behavior in the undercooled liquid. With rapid up-quenching of amorphous samples, the high temperature crystallization behavior can be measured and used to refine the kinetics analysis and provide useful insight on the kinetic competition and glass forming ability.

  13. Core-seis: a code for LMFBR core seismic analysis

    Energy Technology Data Exchange (ETDEWEB)

    Chellapandi, P.; Ravi, R.; Chetal, S.C.; Bhoje, S.B. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Reactor Group

    1995-12-31

    This paper deals with a computer code CORE-SEIS specially developed for seismic analysis of LMFBR core configurations. For demonstrating the prediction capability of the code, results are presented for one of the MONJU reactor core mock ups which deals with a cluster of 37 subassemblies kept in water. (author). 3 refs., 7 figs., 2 tabs.

  14. Core Exercises: Why You Should Strengthen Your Core Muscles

    Science.gov (United States)

    Healthy Lifestyle Fitness You know core exercises are good for you — but do you include core exercises in your fitness routine? Here's why ... 18, 2014 Original article: http://www.mayoclinic.org/healthy-lifestyle/fitness/in-depth/core-exercises/art-20044751 . Mayo Clinic Footer Legal Conditions and ...

  15. Kinetics of Bio-Reactions

    DEFF Research Database (Denmark)

    2015-01-01

    his chapter predicts the specific rates of reaction by means of a mathematical expression, the kinetics of the reaction. This expression can be derived through a mechanistic interpretation of an enzymatically catalyzed reaction, but it is essentially of empirical nature for cell reactions....... The models can be used in mass balances for design of processes under process conditions not yet studied experimentally. The value of the predictive kinetic model depends on the quality of the experimental data on which the model is based, and well-founded kinetic models for enzyme reactions have...... a considerable predictive power. This is also true for cell reaction models, when the model is used in its proper context. The chapter first discusses the kinetics for enzymatically catalyzed reactions (“enzyme reactions”). The kinetics can be derived from a mechanistic model. Then, the chapter derives empirical...

  16. Use of a palladium(II)-catalyzed oxidative kinetic resolution in synthetic efforts toward bielschowskysin.

    Science.gov (United States)

    Meyer, Michael E; Phillips, John H; Ferreira, Eric M; Stoltz, Brian M

    2013-09-09

    Progress toward the cyclobutane core of bielshowskysin is reported. The core was thought to arise from a cyclopropane intermediate via a furan-mediated cyclopropane fragmentation, followed by a 1,4-Michael addition. The synthesis of the cyclopropane intermediate utilizes a Suzuki coupling reaction, an esterification with 2-diazoacetoacetic acid, and a copper catalyzed cyclopropanation. An alcohol intermediate within the synthetic route was obtained in high enantiopurity via a highly selective palladium(II)-catalyzed oxidative kinetic resolution (OKR).

  17. Liquid-core waveguide in CE.

    Science.gov (United States)

    Okada, Tetsuo

    2007-10-01

    Liquid-core waveguide (LCW) brings about several advantages in CE. This review discusses some aspects of fundamental and practical importance involved in this method. Sensitivity in absorption and fluorescence detection is in general improved by more than one order of magnitude over usual crossbeam detection arrangements; the improvements come from the long light path in absorption detection and low light scattering in fluorescence detection. Versatile instrumental arrangements are another advantage of LCW in CE, leading to several detection schemes, some of which provide information that is not gained by usual capillary-end crossbeam detection, e.g. whole-capillary imaging, simultaneous monitoring of multicapillary separation, and kinetic evaluation. The high potential and perspectives of LCW in CE are discussed based on the state-of-the-art developments.

  18. Water turnover and core temperature on Mount Rainier.

    Science.gov (United States)

    Hailes, Walter S; Cuddy, John S; Slivka, Dustin S; Hansen, Kent; Ruby, Brent C

    2012-09-01

    Hydration is an important logistical consideration for persons performing in austere environments because water demands must be balanced with the burden of carrying water. Seven novice climbers participated in a study to determine the hydration kinetics and core temperatures associated with a successful summit of Mount Rainier. Ingestible radio-equipped thermometer capsules were swallowed to monitor core temperature, and an oral dose of deuterium (0.12 ± 0.02 g·kg⁻¹ body weight) was administered to determine hydration kinetics. Mean core temperature throughout the 5.5-hour climb to Camp Muir (3000 m) was 37.6 ± 0.3°C. Water turnover was 95.0 ± 17.5 mL·kg⁻¹·24 h⁻¹ over the duration of the 43-hour study. There was a trend for reduced body mass from before (75.9 ± 13.0 kg) to after (74.8 ± 12.5 kg) the climb (P = .06), and urine specific gravity increased from before (1.013 ± 0.002) to after (1.022 ± 0.006) the climb (P = .004). Hydration demands of climbing Mount Rainier are highly elevated despite modest fluctuations in core temperature. Participants experienced hypohydration but were able to maintain sufficient hydration to successfully summit Mount Rainier and return home safely. Copyright © 2012 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.

  19. ICF Core Sets for stroke

    National Research Council Canada - National Science Library

    Szilvia Geyh; Alarcos Cieza; Jan Schouten; Hugh Dickson; Peter Frommelt; Zaliha Omar; Nenad Kostanjsek; Haim Ring; Gerold Stucki

    2004-01-01

    Objective: To report on the results of the consensus process integrating evidence from preliminary studies to develop the first version of the Comprehensive ICF Core Set and the Brief ICF Core Set for stroke. Methods...

  20. STOMP Subsurface Transport Over Multiple Phases Version 1.0 Addendum: ECKEChem Equilibrium-Conservation-Kinetic Equation Chemistry and Reactive Transport

    Energy Technology Data Exchange (ETDEWEB)

    White, Mark D.; McGrail, B. Peter

    2005-12-01

    flow and transport simulator, STOMP (Subsurface Transport Over Multiple Phases). Prior to these code development activities, the STOMP simulator included sequential and scalable implementations for numerically simulating the injection of supercritical CO2 into deep saline aquifers. Additionally, the sequential implementations included operational modes that considered nonisothermal conditions and kinetic dissolution of CO2 into the saline aqueous phase. This addendum documents the advancement of these numerical simulation capabilities to include reactive transport in the STOMP simulator through the inclusion of the recently PNNL developed batch geochemistry solution module ECKEChem (Equilibrium-Conservation-Kinetic Equation Chemistry). Potential geologic reservoirs for sequestering CO2 include deep saline aquifers, hydrate-bearing formations, depleted or partially depleted natural gas and petroleum reservoirs, and coal beds. The mechanisms for sequestering carbon dioxide in geologic reservoirs include physical trapping, dissolution in the reservoir fluids, hydraulic trapping (hysteretic entrapment of nonwetting fluids), and chemical reaction. This document and the associated code development and verification work are concerned with the chemistry of injecting CO2 into geologic reservoirs. As geologic sequestration of CO2 via chemical reaction, namely precipitation reactions, are most dominate in deep saline aquifers, the principal focus of this document is the numerical simulation of CO2 injection, migration, and geochemical reaction in deep saline aquifers. The ECKEChem batch chemistry module was developed in a fashion that would allow its implementation into all operational modes of the STOMP simulator, making it a more versatile chemistry component. Additionally, this approach allows for verification of the ECKEChem module against more classical reactive transport problems involving aqueous systems.

  1. Kinetic distance and kinetic maps from molecular dynamics simulation.

    Science.gov (United States)

    Noé, Frank; Clementi, Cecilia

    2015-10-13

    Characterizing macromolecular kinetics from molecular dynamics (MD) simulations requires a distance metric that can distinguish slowly interconverting states. Here, we build upon diffusion map theory and define a kinetic distance metric for irreducible Markov processes that quantifies how slowly molecular conformations interconvert. The kinetic distance can be computed given a model that approximates the eigenvalues and eigenvectors (reaction coordinates) of the MD Markov operator. Here, we employ the time-lagged independent component analysis (TICA). The TICA components can be scaled to provide a kinetic map in which the Euclidean distance corresponds to the kinetic distance. As a result, the question of how many TICA dimensions should be kept in a dimensionality reduction approach becomes obsolete, and one parameter less needs to be specified in the kinetic model construction. We demonstrate the approach using TICA and Markov state model (MSM) analyses for illustrative models, protein conformation dynamics in bovine pancreatic trypsin inhibitor and protein-inhibitor association in trypsin and benzamidine. We find that the total kinetic variance (TKV) is an excellent indicator of model quality and can be used to rank different input feature sets.

  2. CdSe/Cd(x)Zn1-xS core/shell nanocrystals: core morphology and luminescent property.

    Science.gov (United States)

    Yang, Ping; Yang, Jie; Cao, Yongqiang; Ma, Qian; Zhang, Aiyu; Wang, Jianrong; Shi, Ruixia; Zhu, Yuanna

    2012-06-01

    CdSe cores with rod (an aspect ratio of 1.8, d-5 nm) and spherical (an aspect ratio of 1, d-5 nm) morphologies were fabricated by two kinds of organic approaches through adjusting growth processes. Because of large difference of size and morphology, two kinds of cores revealed different absorption spectra. However, these cores exhibited almost same photoluminescence (PL) spectra with a red-emitting PL peak of around 625 nm. This is ascribed that they have a similar size in diameter. A graded Cd(x)Zn1-xS shell of larger band gap was grown around CdSe rods and spheres using oleic acid as a capping agent. Based on the growth kinetics of CdS and ZnS, interfacial segregation was created to preferentially deposit CdS near the core, providing relaxation of the strain at the core/shell interface. For spherical CdSe cores, the homogeneous deposition of the Cd(x)Zn1-xS shell created spherical core/shell nanocrystals (NCs) with a size of 7.1 nm in diameter. In the case of using CdSe cores with rod morphology, the anisotropic aggregation behaviors of CdS monomers on CdSe rods led to the size (approximately 10 nm in diameter) of spherical CdSe/Cd(x)Zn1-xS core/shell NCs with a small difference to the length of the CdSe rod (approximately 8.9 nm). The resulting spherical core/shell NCs created by the rod and spherical cores exhibited almost same PL peak wavelength (652 and 653 nm for using rod and spherical cores, respectively), high PL efficiency up to 50%, and narrow PL spectra (36 and 28 nm of full with at half maximum of PL spectra for the core/shell NCs with CdSe spheres and rods, respectively). These core/shell NCs provide an opportunity for the study of the evolution of PL properties as the shape of semiconductor NCs.

  3. Studying the effects of dynamical parameters on reactor core temperature

    Directory of Open Access Journals (Sweden)

    R Khodabakhsh

    2015-01-01

    Full Text Available In order to increase productivity, reduce depreciation, and avoid possible accidents in a system such as fuel rods' melting and overpressure, control of temperature changes in the reactor core is an important factor. There are several methods for solving and analysing the stability of point kinetics equations. In most previous analyses, the effects of various factors on the temperature of the reactor core have been ignored. In this work, the effects of various dynamical parameters on the temperature of the reactor core and stability of the system in the presence of temperature feedback reactivity with external reactivity step, ramp and sinusoidal for six groups of delayed neutrons were studied using the method of Lyapunov exponent. The results proved to be in good agreement with other works

  4. Probing the Core-Collapse Supernova Mechanism with Gravitational Waves

    CERN Document Server

    Ott, C D

    2009-01-01

    The mechanism of core-collapse supernova explosions must draw on the energy provided by gravitational collapse and transfer the necessary fraction to the kinetic and internal energy of the ejecta. Despite many decades of concerted theoretical effort, the detailed mechanism of core-collapse supernova explosions is still unknown, but indications are strong that multi-D processes lie at its heart. This opens up the possibility of probing the supernova mechanism with gravitational waves, carrying direct dynamical information from the supernova engine deep inside a dying massive star. I present a concise overview of the physics and primary multi-D dynamics in neutrino-driven, magnetorotational, and acoustically-driven core-collapse supernova explosion scenarios. Discussing and contrasting estimates for the gravitational-wave emission characteristics of these mechanisms, I argue that their gravitational-wave signatures are clearly distinct and that the observation (or non-observation) of gravitational waves from a ...

  5. Hollow-Core Fiber Lamp

    Science.gov (United States)

    Yi, Lin (Inventor); Tjoelker, Robert L. (Inventor); Burt, Eric A. (Inventor); Huang, Shouhua (Inventor)

    2016-01-01

    Hollow-core capillary discharge lamps on the millimeter or sub-millimeter scale are provided. The hollow-core capillary discharge lamps achieve an increased light intensity ratio between 194 millimeters (useful) and 254 millimeters (useless) light than conventional lamps. The capillary discharge lamps may include a cone to increase light output. Hollow-core photonic crystal fiber (HCPCF) may also be used.

  6. On core stability and extendability

    OpenAIRE

    Shellshear, Evan

    2007-01-01

    This paper investigates conditions under which the core of a TU cooperative game is stable. In particular the author extends the idea of extendability to find new conditions under which the core is stable. It is also shown that these new conditions are not necessary for core stability.

  7. Dual-core Itanium Processor

    CERN Multimedia

    2006-01-01

    Intel’s first dual-core Itanium processor, code-named "Montecito" is a major release of Intel's Itanium 2 Processor Family, which implements the Intel Itanium architecture on a dual-core processor with two cores per die (integrated circuit). Itanium 2 is much more powerful than its predecessor. It has lower power consumption and thermal dissipation.

  8. On core stability and extendability

    OpenAIRE

    Shellshear, Evan

    2007-01-01

    This paper investigates conditions under which the core of a TU cooperative game is stable. In particular the author extends the idea of extendability to find new conditions under which the core is stable. It is also shown that these new conditions are not necessary for core stability.

  9. The Kinetics of Enzyme Mixtures

    Directory of Open Access Journals (Sweden)

    Simon Brown

    2014-03-01

    Full Text Available Even purified enzyme preparations are often heterogeneous. For example, preparations of aspartate aminotransferase or cytochrome oxidase can consist of several different forms of the enzyme. For this reason we consider how different the kinetics of the reactions catalysed by a mixture of forms of an enzyme must be to provide some indication of the characteristics of the species present. Based on the standard Michaelis-Menten model, we show that if the Michaelis constants (Km of two isoforms differ by a factor of at least 20 the steady-state kinetics can be used to characterise the mixture. However, even if heterogeneity is reflected in the kinetic data, the proportions of the different forms of the enzyme cannot be estimated from the kinetic data alone. Consequently, the heterogeneity of enzyme preparations is rarely reflected in measurements of their steady-state kinetics unless the species present have significantly different kinetic properties. This has two implications: (1 it is difficult, but not impossible, to detect molecular heterogeneity using kinetic data and (2 even when it is possible, a considerable quantity of high quality data is required.

  10. Kinetic properties of cyanase.

    Science.gov (United States)

    Anderson, P M; Little, R M

    1986-04-01

    Cyanase is an inducible enzyme in Escherichia coli that catalyzes the hydrolysis of cyanate. Bicarbonate is required for activity, perhaps as a substrate, and the initial product of the reaction is carbamate, which spontaneously breaks down to ammonia and bicarbonate [Anderson, P. M. (1980) Biochemistry 19, 2882]. The purpose of this study was to characterize the kinetic properties of cyanase. Initial velocity studies showed that both cyanate and bicarbonate act as competitive substrate inhibitors. A number of monovalent anions act as inhibitors. Azide and acetate appear to act as competitive inhibitors with respect to cyanate and bicarbonate, respectively. Chloride, bromide, nitrate, nitrite, and formate also inhibit, apparently as the result of binding at either substrate site. Malonate and several other dicarboxylic dianions at very low concentrations display "slow-binding", reversible inhibition which can be prevented by saturating concentrations of either substrate. The results are consistent with a rapid equilibrium random mechanism in which bicarbonate acts as a substrate, bicarbonate and cyanate bind at adjacent anion-binding sites, and both substrates can bind at the other substrate anion binding site to give a dead-end complex.

  11. Measuring Kinetic Plasma Eigenmodes

    Science.gov (United States)

    Mattingly, Sean; Berumen, Jorge; Chu, Feng; Hood, Ryan; Skiff, Fred

    2015-11-01

    We present a method for measuring kinetic plasma eigenmodes of a cylindrical axially magnetized (1 kG) laboratory plasma (n ~109cm-3 , Te ~ 5eV , Ti ~ 0 . 06eV) by measuring velocity space correlation functions. This method simultaneously observes two separate laser induced fluorescence schemes. Each scheme has its own indepedently tunable laser and its own set of collection optics. With this setup, we are able to measure the time - averaged correlation function as a function of position on the cylindrical axis parallel to the magnetic field (z) and velocity on the deconvolved ion velocity distribution function (v) : C (z , v ,z' ,v' , τ) = t. The freedom of two lasers allows us to measure a two dimensional velocity correlation matrix. This matrix is investigated with the Vlasov equation in the collisionless and weakly collisional regime. The former case, which is continuous, is diagonalized with an integral transform defined by P. J. Morrison while the latter case, which is discrete, is diagonalized through the use of Hermite polynomials.

  12. Kinetic Transport in Crystals

    Science.gov (United States)

    Marklof, Jens

    2010-03-01

    One of the central challenges in kinetic theory is the derivation of macroscopic evolution equations--describing, for example, the dynamics of an electron gas--from the underlying fundamental microscopic laws of classical or quantum mechanics. An iconic mathematical model in this research area is the Lorentz gas, which describes an ensemble of non-interacting point particles in an infinite array of spherical scatterers. In the case of a disordered scatterer configuration, the classical results by Gallavotti, Spohn and Boldrighini-Bunimovich-Sinai show that the time evolution of a macroscopic particle cloud is governed, in the limit of small scatterer density (Boltzmann-Grad limit), by the linear Boltzmann equation. In this lecture I will discuss the recent discovery that for a periodic configuration of scatterers the linear Boltzmann equation fails, and the random flight process that emerges in the Boltzmann-Grad limit is substantially more complicated. The key ingredient in the description of the limiting stochastic process is the renormalization dynamics on the space of lattices, a powerful technique that has recently been successfully applied also to other open problems in mathematical physics, including KAM theory and quantum chaos. This lecture is based on joint work with Andreas Strömbergsson, Uppsala.

  13. Winning Cores in Parity Games

    DEFF Research Database (Denmark)

    Vester, Steen

    2016-01-01

    We introduce the novel notion of winning cores in parity games and develop a deterministic polynomial-time under-approximation algorithm for solving parity games based on winning core approximation. Underlying this algorithm are a number properties about winning cores which are interesting...... in their own right. In particular, we show that the winning core and the winning region for a player in a parity game are equivalently empty. Moreover, the winning core contains all fatal attractors but is not necessarily a dominion itself. Experimental results are very positive both with respect to quality...

  14. Chain exchange kinetics of block copolymer micelles in ionic liquids

    Science.gov (United States)

    Ma, Yuanchi; Lodge, Timothy

    The chain exchange kinetics of block copolymer micelles has been studied using time-resolved small-angle neutron scattering (TR-SANS), a key tool in determining the average micelle composition in contrast-matched solvents. In this work, PMMA-block-PnBMA was selected as the model block copolymer, which has a LCST behavior in the common ionic liquids, [EMIM][TFSI] and [BMIM][TFSI]. We examined the chain exchange kinetics of three PMMA-block-PnBMA copolymers, with identical PMMA block length (MPMMA = 25000) and different PnBMA block lengths (MPnBMA = 24000, 35000 and 53000); the Flory-Huggins interaction parameter (χ) between the core (PnBMA) and the solvent were varied by mixing [EMIM][TFSI] and [BMIM][TFSI] in different ratios. We found that the relaxation of the initial segregation of h- and d- micelles followed the same form with the time as previously developed by our group. Assuming that single chain expulsion is the rate limiting step, the thermal barrier was found to depend linearly on the core block length (Ncore) . Furthermore, the effect of χ on the chain exchange kinetics will also be discussed.

  15. Heat Pipe Reactor Dynamic Response Tests: SAFE-100 Reactor Core Prototype

    Science.gov (United States)

    Bragg-Sitton, Shannon M.

    2005-01-01

    The SAFE-I00a test article at the NASA Marshall Space Flight Center was used to simulate a variety of potential reactor transients; the SAFEl00a is a resistively heated, stainless-steel heat-pipe (HP)-reactor core segment, coupled to a gas-flow heat exchanger (HX). For these transients the core power was controlled by a point kinetics model with reactivity feedback based on core average temperature; the neutron generation time and the temperature feedback coefficient are provided as model inputs. This type of non-nuclear test is expected to provide reasonable approximation of reactor transient behavior because reactivity feedback is very simple in a compact fast reactor (simple, negative, and relatively monotonic temperature feedback, caused mostly by thermal expansion) and calculations show there are no significant reactivity effects associated with fluid in the HP (the worth of the entire inventory of Na in the core is .kinetics model was based on core thermal expansion via deflection measurements. It was found that core deflection was a strung function of how the SAFE-100 modules were fabricated and assembled (in terms of straightness, gaps, and other tolerances). To remove the added variable of how this particular core expands as compared to a different concept, it was decided to use a temperature based feedback model (based on several thermocouples placed throughout the core).

  16. Models of the earth's core

    Science.gov (United States)

    Stevenson, D. J.

    1981-01-01

    Combined inferences from seismology, high-pressure experiment and theory, geomagnetism, fluid dynamics, and current views of terrestrial planetary evolution lead to models of the earth's core with five basic properties. These are that core formation was contemporaneous with earth accretion; the core is not in chemical equilibrium with the mantle; the outer core is a fluid iron alloy containing significant quantities of lighter elements and is probably almost adiabatic and compositionally uniform; the more iron-rich inner solid core is a consequence of partial freezing of the outer core, and the energy release from this process sustains the earth's magnetic field; and the thermodynamic properties of the core are well constrained by the application of liquid-state theory to seismic and labroatory data.

  17. Starless Cores as Fundamental Physics Labs

    Science.gov (United States)

    Mignano, Arturo; Molaro, Paolo; Levshakov, Sergei; Centurión, Miriam; Maccaferri, Giuseppe; Lapinov, Alexander

    We present high resolution observations in the starless dense molecular core L1512 performed with the Medicina 32m radio telescope. The resolved hfs components of HC3N and NH3 show no kinematic sub-structure and consist of an apparently symmetric peak profile without broadened line wings or self-absorption features suggesting that they sample the same material. The velocity dispersion is 101( ± 1) m s - 1for NH3 and 85( ± 2) m s - 1 for HC3N. The kinetic temperature of the cloud is estimated at 9.2 ( ± 1.2) K and the turbulence is of 76 m s - 1in a subsonic regime. This places L1512 among the most quiescent dark cores and makes it an ideal laboratory to study variations of the electron-to-proton mass ratio, μ = {m}e/{m}p by means of observations of inversion lines of NH3 combined with rotational lines of other molecular species.

  18. Modelling heart rate kinetics.

    Science.gov (United States)

    Zakynthinaki, Maria S

    2015-01-01

    The objective of the present study was to formulate a simple and at the same time effective mathematical model of heart rate kinetics in response to movement (exercise). Based on an existing model, a system of two coupled differential equations which give the rate of change of heart rate and the rate of change of exercise intensity is used. The modifications introduced to the existing model are justified and discussed in detail, while models of blood lactate accumulation in respect to time and exercise intensity are also presented. The main modification is that the proposed model has now only one parameter which reflects the overall cardiovascular condition of the individual. The time elapsed after the beginning of the exercise, the intensity of the exercise, as well as blood lactate are also taken into account. Application of the model provides information regarding the individual's cardiovascular condition and is able to detect possible changes in it, across the data recording periods. To demonstrate examples of successful numerical fit of the model, constant intensity experimental heart rate data sets of two individuals have been selected and numerical optimization was implemented. In addition, numerical simulations provided predictions for various exercise intensities and various cardiovascular condition levels. The proposed model can serve as a powerful tool for a complete means of heart rate analysis, not only in exercise physiology (for efficiently designing training sessions for healthy subjects) but also in the areas of cardiovascular health and rehabilitation (including application in population groups for which direct heart rate recordings at intense exercises are not possible or not allowed, such as elderly or pregnant women).

  19. Modelling heart rate kinetics.

    Directory of Open Access Journals (Sweden)

    Maria S Zakynthinaki

    Full Text Available The objective of the present study was to formulate a simple and at the same time effective mathematical model of heart rate kinetics in response to movement (exercise. Based on an existing model, a system of two coupled differential equations which give the rate of change of heart rate and the rate of change of exercise intensity is used. The modifications introduced to the existing model are justified and discussed in detail, while models of blood lactate accumulation in respect to time and exercise intensity are also presented. The main modification is that the proposed model has now only one parameter which reflects the overall cardiovascular condition of the individual. The time elapsed after the beginning of the exercise, the intensity of the exercise, as well as blood lactate are also taken into account. Application of the model provides information regarding the individual's cardiovascular condition and is able to detect possible changes in it, across the data recording periods. To demonstrate examples of successful numerical fit of the model, constant intensity experimental heart rate data sets of two individuals have been selected and numerical optimization was implemented. In addition, numerical simulations provided predictions for various exercise intensities and various cardiovascular condition levels. The proposed model can serve as a powerful tool for a complete means of heart rate analysis, not only in exercise physiology (for efficiently designing training sessions for healthy subjects but also in the areas of cardiovascular health and rehabilitation (including application in population groups for which direct heart rate recordings at intense exercises are not possible or not allowed, such as elderly or pregnant women.

  20. Modelling Heart Rate Kinetics

    Science.gov (United States)

    Zakynthinaki, Maria S.

    2015-01-01

    The objective of the present study was to formulate a simple and at the same time effective mathematical model of heart rate kinetics in response to movement (exercise). Based on an existing model, a system of two coupled differential equations which give the rate of change of heart rate and the rate of change of exercise intensity is used. The modifications introduced to the existing model are justified and discussed in detail, while models of blood lactate accumulation in respect to time and exercise intensity are also presented. The main modification is that the proposed model has now only one parameter which reflects the overall cardiovascular condition of the individual. The time elapsed after the beginning of the exercise, the intensity of the exercise, as well as blood lactate are also taken into account. Application of the model provides information regarding the individual’s cardiovascular condition and is able to detect possible changes in it, across the data recording periods. To demonstrate examples of successful numerical fit of the model, constant intensity experimental heart rate data sets of two individuals have been selected and numerical optimization was implemented. In addition, numerical simulations provided predictions for various exercise intensities and various cardiovascular condition levels. The proposed model can serve as a powerful tool for a complete means of heart rate analysis, not only in exercise physiology (for efficiently designing training sessions for healthy subjects) but also in the areas of cardiovascular health and rehabilitation (including application in population groups for which direct heart rate recordings at intense exercises are not possible or not allowed, such as elderly or pregnant women). PMID:25876164

  1. Kinetic Magnetorotational Turbulence and Dynamo

    Science.gov (United States)

    Kunz, Matthew; Stone, James; Quataert, Eliot

    2016-10-01

    Low-luminosity black-hole accretion flows, such as that at the Galactic center, are collisionless. A kinetic approach is thus necessary to understand the transport of heat and angular momentum, the acceleration of particles, and the growth and structure of the magnetic field in these systems. We present results from the first 6D kinetic numerical simulation of magnetorotational turbulence and dynamo, using the local shearing-box model. Special attention will be paid to the enhanced transport of angular momentum by field-aligned pressure anisotropies, as well as to the ion-Larmor-scale kinetic instabilities (firehose, mirror, ion-cyclotron) which regulate those anisotropies. Energy spectra and phase-space evolution will be discussed. Time permitting, dedicated nonlinear studies of firehose and mirror instabilities in a shearing plasma will also be presented as a complement to the study of the magnetorotational instability. The profits, perils, and price of using a kinetic approach will be briefly mentioned.

  2. Kinetic properties of fractal media

    CERN Document Server

    Chumak, Oleg V

    2016-01-01

    Kinetic processes in fractal stellar media are analyzed in terms of the approach developed in our earlier paper (Chumak, Rastorguev, 2016) involving a generalization of the nearest neighbor and random force distributions to fractal media. Diffusion is investigated in the approximation of scale-dependent conditional density based on an analysis of the solutions of the corresponding Langevin equations. It is shown that kinetic parameters (time scales, coefficients of dynamic friction, diffusion, etc.) for fractal stellar media can differ significantly both qualitatively and quantitatively from the corresponding parameters for a quasi-uniform random media with limited fluctuations. The most important difference is that in the fractal case kinetic parameters depend on spatial scale length and fractal dimension of the medium studied. A generalized kinetic equation for stellar media (fundamental equation of stellar dynamics) is derived in the Fokker-Planck approximation with the allowance for the fractal properties...

  3. An Inexpensive Kinetic Study: The Reaction of FD&C Red #3 (Erythrosin B) with Hypochlorite

    Science.gov (United States)

    Henary, Maher M.; Russell, Arlene A.

    2007-01-01

    Kinetics constitutes a core topic in both the lecture and laboratory components of lower- level chemistry courses. While textbook examples can ignore issues of time, temperature and safety, the laboratory can not. Reactions must occur slowly enough to be detected by students, occur rapidly enough for data collection in the few hours assigned to a…

  4. Kinetics Modeling of Cancer Immunology.

    Science.gov (United States)

    1986-05-09

    CANCER IMMUNOLOGY -1 DTICS ELECTED SEP 9 8 UNITED STATES NAVAL ACADEMY ANNAPOLIS, MARYLAND V ,1986 %,e docment ha le approved for public A." I and sale...1986 4. TITLE (and Subtitle) S. TYPE OF REPORT & PERIOD COVERED KINETICS MODELING OF CANCER IMMUNOLOGY Final: 1985/1986 6. PERFORMING ORG. REPORT...137 (1986) "Kinetics Modeling of Cancer Immunology " A Trident Scholar Project Report by Midn I/C Scott Helmers, Class of 1986 United States Naval

  5. Morphogenesis of Kinetic Reciprocal Frames

    DEFF Research Database (Denmark)

    Parigi, Dario; Sassone, Mario

    2011-01-01

    Kinetic structures in civil engineering and architecture gained considerable more attention in the very recent years as a practical solution to face time dependant performances. Realized projects are mostly bridges, retractable roofs, while in architecture the trend follows the category of intera......Kinetic structures in civil engineering and architecture gained considerable more attention in the very recent years as a practical solution to face time dependant performances. Realized projects are mostly bridges, retractable roofs, while in architecture the trend follows the category...

  6. Complex coacervate core micelles.

    Science.gov (United States)

    Voets, Ilja K; de Keizer, Arie; Cohen Stuart, Martien A

    2009-01-01

    In this review we present an overview of the literature on the co-assembly of neutral-ionic block, graft, and random copolymers with oppositely charged species in aqueous solution. Oppositely charged species include synthetic (co)polymers of various architectures, biopolymers - such as proteins, enzymes and DNA - multivalent ions, metallic nanoparticles, low molecular weight surfactants, polyelectrolyte block copolymer micelles, metallo-supramolecular polymers, equilibrium polymers, etcetera. The resultant structures are termed complex coacervate core/polyion complex/block ionomer complex/interpolyelectrolyte complex micelles (or vesicles); i.e., in short C3Ms (or C3Vs) and PIC, BIC or IPEC micelles (and vesicles). Formation, structure, dynamics, properties, and function will be discussed. We focus on experimental work; theory and modelling will not be discussed. Recent developments in applications and micelles with heterogeneous coronas are emphasized.

  7. Understanding core conductor fabrics

    Energy Technology Data Exchange (ETDEWEB)

    Swenson, D E, E-mail: deswenson@affinity-esd.com [Affinity Static Control Consulting, LLC 2609 Quanah Drive, Round Rock, Texas, 78681 (United States)

    2011-06-23

    ESD Association standard test method ANSI/ESD STM2.1 - Garments (STM2.1), provides electrical resistance test procedures that are applicable for materials and garments that have surface conductive or surface dissipative properties. As has been reported in other papers over the past several years{sup 1} fabrics are now used in many industries for electrostatic control purposes that do not have surface conductive properties and therefore cannot be evaluated using the procedures in STM2.1{sup 2}. A study was conducted to compare surface conductive fabrics with samples of core conductor fibre based fabrics in order to determine differences and similarities with regards to various electrostatic properties. This work will be used to establish a new work item proposal within WG-2, Garments, in the ESD Association Standards Committee in the USA.

  8. Growth outside the core.

    Science.gov (United States)

    Zook, Chris; Allen, James

    2003-12-01

    Growth in an adjacent market is tougher than it looks; three-quarters of the time, the effort fails. But companies can change those odds dramatically. Results from a five-year study of corporate growth conducted by Bain & Company reveal that adjacency expansion succeeds only when built around strong core businesses that have the potential to become market leaders. And the best place to look for adjacency opportunities is inside a company's strongest customers. The study also found that the most successful companies were able to consistently, profitably outgrow their rivals by developing a formula for pushing out the boundaries of their core businesses in predictable, repeatable ways. Companies use their repeatability formulas to expand into any number of adjacencies. Some companies make repeated geographic moves, as Vodafone has done in expanding from one geographic market to another over the past 13 years, building revenues from $1 billion in 1990 to $48 billion in 2003. Others apply a superior business model to new segments. Dell, for example, has repeatedly adapted its direct-to-customer model to new customer segments and new product categories. In other cases, companies develop hybrid approaches. Nike executed a series of different types of adjacency moves: it expanded into adjacent customer segments, introduced new products, developed new distribution channels, and then moved into adjacent geographic markets. The successful repeaters in the study had two common characteristics. First, they were extraordinarily disciplined, applying rigorous screens before they made an adjacency move. This discipline paid off in the form of learning curve benefits, increased speed, and lower complexity. And second, in almost all cases, they developed their repeatable formulas by studying their customers and their customers' economics very, very carefully.

  9. McCARD for Neutronics Design and Analysis of Research Reactor Cores

    Science.gov (United States)

    Shim, Hyung Jin; Park, Ho Jin; Kwon, Soonwoo; Seo, Geon Ho; Hyo Kim, Chang

    2014-06-01

    McCARD is a Monte Carlo (MC) neutron-photon transport simulation code developed exclusively for the neutronics design and analysis of nuclear reactor cores. McCARD is equipped with the hierarchical modeling and scripting functions, the CAD-based geometry processing module, the adjoint-weighted kinetics parameter and source multiplication factor estimation modules as well as the burnup analysis capability for the neutronics design and analysis of both research and power reactor cores. This paper highlights applicability of McCARD for the research reactor core neutronics analysis, as demonstrated for Kyoto University Critical Assembly, HANARO, and YALINA.

  10. Advances in core drilling technology

    Science.gov (United States)

    Holdsworth, G.

    Some notable technical advances in drill design were reported at the meeting, held in Canada August 30-September 1, 1982, at the University of Calgary. Chief amongst these was a battery powered, computer assisted electromechanical core drill which has recently been used by the Danes in Greenland to continuously core to the base of the ice sheet at 2038 m. This is the deepest coring operation so far on the Greenland ice sheet. (The record for deep glacier drilling is held by the U.S. Army Cold Regions Research and Engineering Laboratory for the continuous coring through 2164 m of ice to bedrock at Byrd Station, Antarctica, in 1968). In early 1982, a current Soviet core drilling operation was reported to be at a depth of 2000 m at Vostok station, Antarctica, where the total ice thickness is about 4000 m; the goal of core drilling the entire ice thickness there could be achieved before the end of 1983.

  11. Crystallization Kinetics within a Generic Modelling Framework

    DEFF Research Database (Denmark)

    Meisler, Kresten Troelstrup; von Solms, Nicolas; Gernaey, Krist

    2013-01-01

    An existing generic modelling framework has been expanded with tools for kinetic model analysis. The analysis of kinetics is carried out within the framework where kinetic constitutive models are collected, analysed and utilized for the simulation of crystallization operations. A modelling...... procedure is proposed to gain the information of crystallization operation kinetic model analysis and utilize this for faster evaluation of crystallization operations....

  12. Massive molecular cloud cores and activities of star formation

    Institute of Scientific and Technical Information of China (English)

    Zhou Wu-Fei; Wu Yue-Fang; Wei Yue; Ju Bing-Gang

    2005-01-01

    We have mapped 23 sources in the J=1-0 lines of 12CO, 13CO and C18O with the 13.7-m telescope at Qinghai station of Purple Mountain Observatory. The samples were chosen from the massive star formation regions whose single point lines have the broad-wing profile. The mapping shows that 12 clouds have cores and 5 outflows were identified with the 12CO J=1-0 lines. Among the 12 cores, systematic velocity shifts were found in 2 cores, and blue asymmetric double-peak profile of 12CO line was found in IRAS 19529+2704, indicating that it may be an infall candidate. Physical parameters of the cores and outflows were derived from the local thermodynamic equilibrium assumption. The masses range from ~ 9.4 × 102M⊙ to ~ 2.2 × 105M⊙. The hydrogen molecule densities range from ~ 3.4 × 102cm-3 to~ 1.2 × 104cm-3. The molecular outflows have masses larger than 3.5M⊙, and kinetic energies greater than 0.9× 1038J.The outflows have significantly greater masses and kinetic energies than those from low-mass young stellar objects(YSOs). For the cores, 2MASS data are available, dozens of 2MASS sources with different colour indices and brightness are often found around IRAS source, among which the reddest 2MASS source is always within the IRAS error ellipse thus probably corresponds to the IRAS source.

  13. Antitumor efficacy of dexamethasone-loaded core-crosslinked polymeric micelles

    NARCIS (Netherlands)

    Coimbra, M.; Rijcken, C.J.; Stigter, M.; Hennink, W.E.; Storm, Gerrit; Schiffelers, R.M.

    2012-01-01

    Abstract In the current study, core-crosslinked polymeric micelles (DEX-PMs) loaded with three different DEX derivatives designed to display different drug release kinetics, were evaluated for cancer therapy and compared to another effective nanomedicine formulation (long-circulating liposomes encap

  14. Observations of Shoaling Nonlinear Internal Waves: Formation of Trapped Cores

    Science.gov (United States)

    Lien, R.; D'Asaro, E. A.; Chang, M.; Tang, T.; Yang, Y.

    2006-12-01

    Large-amplitude nonlinear internal waves (NLIWs) shoaling on the continental slope in the northern South China Sea are observed. Observed NLIWs often reach the breaking limit, the maximum horizontal current velocity exceeding the wave speed, and trapped cores are formed with recirculating fluid. The conjugate flow does not form. The vertical position of the maximum horizontal velocity is displaced from surface to subsurface, via the formation of the trapped core. Trapped-core NLIWs are strongly dissipative and evolve rapidly into trains of NLIWs. The vertical overturning is as large as 75 m, and the turbulence kinetic energy dissipation rate is estimated as O(10^{-5}) W kg-1. We propose that the formation and the evolution of trapped cores catalyze the generation of the trains of NLIWs on the Dongsha plateau often captured by satellite images and by recent field observations. The generation, evolution, fission, dissipation, and energetics of observed trapped-core NLIWs will be discussed and compared with results of numerical models and laboratory experiments.

  15. Code Coupling for Multi-Dimensional Core Transient Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jin-Woo; Park, Guen-Tae; Park, Min-Ho; Ryu, Seok-Hee; Um, Kil-Sup; Lee Jae-Il [KEPCO NF, Daejeon (Korea, Republic of)

    2015-05-15

    After the CEA ejection, the nuclear power of the reactor dramatically increases in an exponential behavior until the Doppler effect becomes important and turns the reactivity balance and power down to lower levels. Although this happens in a very short period of time, only few seconds, the energy generated can be very significant and cause fuel failures. The current safety analysis methodology which is based on overly conservative assumptions with the point kinetics model results in quite adverse consequences. Thus, KEPCO Nuclear Fuel(KNF) is developing the multi-dimensional safety analysis methodology to mitigate the consequences of the single CEA ejection accident. For this purpose, three-dimensional core neutron kinetics code ASTRA, sub-channel analysis code THALES, and fuel performance analysis code FROST, which have transient calculation performance, were coupled using message passing interface (MPI). This paper presents the methodology used for code coupling and the preliminary simulation results with the coupled code system (CHASER). Multi-dimensional core transient analysis code system, CHASER, has been developed and it was applied to simulate a single CEA ejection accident. CHASER gave a good prediction of multi-dimensional core transient behaviors during transient. In the near future, the multi-dimension CEA ejection analysis methodology using CHASER is planning to be developed. CHASER is expected to be a useful tool to gain safety margin for reactivity initiated accidents (RIAs), such as a single CEA ejection accident.

  16. Core TuLiP

    OpenAIRE

    Czenko, M.R.; Etalle, Sandro

    2007-01-01

    We propose CoreTuLiP - the core of a trust management language based on Logic Programming. CoreTuLiP is based on a subset of moded logic programming, but enjoys the features of TM languages such as RT; in particular clauses are issued by different authorities and stored in a distributed manner. We present a lookup and inference algorithm which we prove to be correct and complete w.r.t. the declarative semantics. CoreTuLiP enjoys uniform syntax and the well-established semantics and is express...

  17. Biochemistry Instrumentation Core Technology Center

    Data.gov (United States)

    Federal Laboratory Consortium — The UCLA-DOE Biochemistry Instrumentation Core Facility provides the UCLA biochemistry community with easy access to sophisticated instrumentation for a wide variety...

  18. Accelerating finite-rate chemical kinetics with coprocessors: comparing vectorization methods on GPUs, MICs, and CPUs

    CERN Document Server

    Stone, Christopher P

    2016-01-01

    Efficient ordinary differential equation solvers for chemical kinetics must take into account the available thread and instruction-level parallelism of the underlying hardware, especially on many-core coprocessors, as well as the numerical efficiency. A stiff Rosenbrock and nonstiff Runge-Kutta solver are implemented using the single instruction, multiple thread (SIMT) and single instruction, multiple data (SIMD) paradigms with OpenCL. The performances of these parallel implementations were measured with three chemical kinetic models across several multicore and many-core platforms. Two runtime benchmarks were conducted to clearly determine any performance advantage offered by either method: evaluating the right-hand-side source terms in parallel, and integrating a series of constant-pressure homogeneous reactors using the Rosenbrock and Runge-Kutta solvers. The right-hand-side evaluations with SIMD parallelism on the host multicore Xeon CPU and many-core Xeon Phi co-processor performed approximately three ti...

  19. Waves in the core and mechanical core-mantle interactions

    DEFF Research Database (Denmark)

    Jault, D.; Finlay, Chris

    2015-01-01

    the motions in the direction parallel to the Earth'srotation axis. This property accounts for the signicance of the core-mantle topography.In addition, the stiening of the uid in the direction parallel to the rotation axis gives riseto a magnetic diusion layer attached to the core-mantle boundary, which would...

  20. Characterizing the Core via K-Core Covers

    NARCIS (Netherlands)

    Sanchez, S.M.; Borm, P.E.M.; Estevez, A.

    2013-01-01

    This paper extends the notion of individual minimal rights for a transferable utility game (TU-game) to coalitional minimal rights using minimal balanced families of a specific type, thus defining a corresponding minimal rights game. It is shown that the core of a TU-game coincides with the core of

  1. Characterizing the Core via K-Core Covers

    NARCIS (Netherlands)

    Sanchez, S.M.; Borm, P.E.M.; Estevez, A.

    2013-01-01

    This paper extends the notion of individual minimal rights for a transferable utility game (TU-game) to coalitional minimal rights using minimal balanced families of a specific type, thus defining a corresponding minimal rights game. It is shown that the core of a TU-game coincides with the core of

  2. Non-isothermal decomposition kinetics of magnesite

    OpenAIRE

    Maitra, S; Mukherjee, S.; Saha, N; Pramanik, J

    2007-01-01

    Kinetics of thermal decomposition of Indian magnesite was studied by thermo-gravimetric analysis under non-isothermal condition. Coats and Redfern Integral approximation method was used to determine the kinetic parameters. Using the kinetic parameters different kinetic functions were analyzed with the experimental data to ascertain the decomposition mechanism of magnesium carbonate and it was observed that the decomposition reaction followed a contracting sphere kinetic mechanism.

  3. Kinetics of Reduction Reaction in Micro-Fluidized Bed

    Institute of Scientific and Technical Information of China (English)

    LINYin-he; GUOZhan—cheng; TANGHui—qing; REN Shan; LIJing—wei

    2012-01-01

    Micro-fluidized bed reactor is a new research method for the reduction of iron ore fines. The reactor is op- erated as a differential reactor to ensure a constant gas concentration and temperature within the reactor volume. In order to understand the dynamic process of the reduction reaction in micro-fluidized bed, a series of kinetic experi- ments were designed. In the micro fluidized bed, the use of shrinking core model describes the dynamic behavior of reduction of iron ore. And the apparent activation energy is calculated in the range of 700--850 ~C while the initial atmosphere is 100% content of CO.

  4. Relativistic frozen core potential scheme with relaxation of core electrons

    Science.gov (United States)

    Nakajima, Yuya; Seino, Junji; Hayami, Masao; Nakai, Hiromi

    2016-10-01

    This letter proposes a relaxation scheme for core electrons based on the frozen core potential method at the infinite-order Douglas-Kroll-Hess level, called FCP-CR. The core electrons are self-consistently relaxed using frozen molecular valence potentials after the valence SCF calculation is performed. The efficiency of FCP-CR is confirmed by calculations of gold clusters. Furthermore, FCP-CR reproduces the results of the all-electron method for the energies of coinage metal dimers and the core ionization energies and core level shifts of vinyl acetate and three tungsten complexes at the Hartree-Fock and/or symmetry-adapted cluster configuration interaction levels.

  5. TREAT Transient Analysis Benchmarking for the HEU Core

    Energy Technology Data Exchange (ETDEWEB)

    Kontogeorgakos, D. C. [Argonne National Lab. (ANL), Argonne, IL (United States); Connaway, H. M. [Argonne National Lab. (ANL), Argonne, IL (United States); Wright, A. E. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2014-05-01

    This work was performed to support the feasibility study on the potential conversion of the Transient Reactor Test Facility (TREAT) at Idaho National Laboratory from the use of high enriched uranium (HEU) fuel to the use of low enriched uranium (LEU) fuel. The analyses were performed by the GTRI Reactor Conversion staff at the Argonne National Laboratory (ANL). The objective of this study was to benchmark the transient calculations against temperature-limited transients performed in the final operating HEU TREAT core configuration. The MCNP code was used to evaluate steady-state neutronics behavior, and the point kinetics code TREKIN was used to determine core power and energy during transients. The first part of the benchmarking process was to calculate with MCNP all the neutronic parameters required by TREKIN to simulate the transients: the transient rod-bank worth, the prompt neutron generation lifetime, the temperature reactivity feedback as a function of total core energy, and the core-average temperature and peak temperature as a functions of total core energy. The results of these calculations were compared against measurements or against reported values as documented in the available TREAT reports. The heating of the fuel was simulated as an adiabatic process. The reported values were extracted from ANL reports, intra-laboratory memos and experiment logsheets and in some cases it was not clear if the values were based on measurements, on calculations or a combination of both. Therefore, it was decided to use the term “reported” values when referring to such data. The methods and results from the HEU core transient analyses will be used for the potential LEU core configurations to predict the converted (LEU) core’s performance.

  6. Thermodynamics and Kinetics of Gas Storage in Porous Liquids.

    Science.gov (United States)

    Zhang, Fei; Yang, Fengchang; Huang, Jingsong; Sumpter, Bobby G; Qiao, Rui

    2016-07-28

    The recent synthesis of organic molecular liquids with permanent porosity opens up exciting new avenues for gas capture, storage, and separation. Using molecular simulations, we study the thermodynamics and kinetics for the storage of CH4, CO2, and N2 molecules in porous liquids consisting of crown-ether-substituted cage molecules in a 15-crown-5 solvent. It is found that the intrinsic gas storage capacity per cage molecule follows the order CH4 > CO2 > N2, which does not correlate simply with the size of gas molecules. Different gas molecules are stored inside the cage differently; e.g., CO2 molecules prefer the cage's core whereas CH4 molecules favor both the core and the branch regions. All gas molecules considered can enter the cage essentially without energy barriers and leave the cage on a nanosecond time scale by overcoming a modest energy penalty. The molecular mechanisms of these observations are clarified.

  7. Adult educators' core competences

    Science.gov (United States)

    Wahlgren, Bjarne

    2016-06-01

    Which competences do professional adult educators need? This research note discusses the topic from a comparative perspective, finding that adult educators' required competences are wide-ranging, heterogeneous and complex. They are subject to context in terms of national and cultural environment as well as the kind of adult education concerned (e.g. basic education, work-related education etc.). However, it seems that it is possible to identify certain competence requirements which transcend national, cultural and functional boundaries. This research note summarises these common or "core" requirements, organising them into four thematic subcategories: (1) communicating subject knowledge; (2) taking students' prior learning into account; (3) supporting a learning environment; and (4) the adult educator's reflection on his or her own performance. At the end of his analysis of different competence profiles, the author notes that adult educators' ability to train adult learners in a way which then enables them to apply and use what they have learned in practice (thus performing knowledge transfer) still seems to be overlooked.

  8. Core of Cloud Computing

    Directory of Open Access Journals (Sweden)

    Prof. C.P.Chandgude

    2017-04-01

    Full Text Available Advancement in computing facilities marks back from 1960’s with introduction of mainframes. Each of the computing has one or the other issues, so keeping this in mind cloud computing was introduced. Cloud computing has its roots in older technologies such as hardware virtualization, distributed computing, internet technologies, and autonomic computing. Cloud computing can be described with two models, one is service model and second is deployment model. While providing several services, cloud management’s primary role is resource provisioning. While there are several such benefits of cloud computing, there are challenges in adopting public clouds because of dependency on infrastructure that is shared by many enterprises. In this paper, we present core knowledge of cloud computing, highlighting its key concepts, deployment models, service models, benefits as well as security issues related to cloud data. The aim of this paper is to provide a better understanding of the cloud computing and to identify important research directions in this field

  9. Dissolution kinetics of aluminum and iron from coal mining waste by hydrochloric acid☆

    Institute of Scientific and Technical Information of China (English)

    Li Cui; Yanxia Guo; Xuming Wang; Zhiping Du; Fangqin Cheng

    2015-01-01

    The extraction of aluminum from coal mining waste (CMW) is an important industrial process. The two major problems in applications are low aluminum dissolution efficiency and high iron content in the raw material, which affect the quantity and quality of products. To improve the aluminum recovery process, the leaching kinet-ics of CMW with hydrochloric acid was studied. A shrinking core model was used to investigate aluminum and iron dissolution kinetics. Based on the kinetic characteristics, a process for recovering aluminum was proposed and tested experimental y. It is found that the aluminum leaching reaction is controlled by surface reaction at low temperatures (40–80 °C) and by diffusion process at higher temperatures (90–106 °C). The iron dissolution process is dominated by surface reaction at 40–100 °C. The results show that iron could be dissolved or separated by concentrated hydrochloric acid. Fine grinding wil improve aluminum dissolution significantly.

  10. Dissolution profile of novel composite pellet cores based on different ratios of microcrystalline cellulose and isomalt.

    Science.gov (United States)

    Luhn, Oliver; Kállai, Nikolett; Nagy, Zsombor Kristóf; Kovács, Kristóf; Fritzsching, Bodo; Klebovich, Imre; Antal, István

    2012-08-01

    There is a growing interest towards the application of inert cores as starting materials for pharmaceutical pellet manufacturing. They serve as alternatives to develop and adapt a relatively simple manufacturing technology compared with an extrusion/spheronisation process. The major objective of this study was to investigate the effect of the compositions of core materials on the drug release profile. Pure microcrystalline cellulose (MCC), isomalt and different types of novel composite MCC-isomalt cores were layered with model drug (sodium diclofenac) and were coated with acrylic polymer. The effect of the osmolality in the gastrointestinal tract was simulated using glucose as osmotically active agent during in vitro dissolution tests. The results demonstrated the dependence of drug dissolution profile on the ratio of MCC and isomalt in the core and the influence of osmotic properties of the dissolution medium. Isomalt used in the composite core was able to decrease the vulnerability of the dissolution kinetics to the changes in the osmotic environment.

  11. Introducing FACETS, the Framework Application for Core-Edge Transport Simulations

    Energy Technology Data Exchange (ETDEWEB)

    Cary, John R. [Tech-X Corporation; Candy, Jeff [General Atomics; Cohen, Ronald H. [Lawrence Livermore National Laboratory (LLNL); Krasheninnikov, Sergei I [ORNL; McCune, Douglas C [ORNL; Estep, Donald J [Colorado State University, Fort Collins; Larson, Jay W [ORNL; Malony, Allen [University of Oregon; Worley, Patrick H [ORNL; Carlsson, Johann Anders [ORNL; Hakim, A H [Tech-X Corporation; Hamill, P [Tech-X Corporation; Kruger, Scott E [ORNL; Muzsala, S [Tech-X Corporation; Pletzer, Alexander [ORNL; Shasharina, Svetlana [Tech-X Corporation; Wade-Stein, D [Tech-X Corporation; Wang, N [Tech-X Corporation; McInnes, Lois C [ORNL; Wildey, T [Tech-X Corporation; Casper, T. A. [Lawrence Livermore National Laboratory (LLNL); Diachin, Lori A [ORNL; Epperly, Thomas [Lawrence Livermore National Laboratory (LLNL); Rognlien, T. D. [Lawrence Livermore National Laboratory (LLNL); Fahey, Mark R [ORNL; Kuehn, Jeffery A [ORNL; Morris, A [University of Oregon; Shende, Sameer [University of Oregon; Feibush, E [Tech-X Corporation; Hammett, Gregory W [ORNL; Indireshkumar, K [Tech-X Corporation; Ludescher, C [Tech-X Corporation; Randerson, L [Tech-X Corporation; Stotler, D. [Princeton Plasma Physics Laboratory (PPPL); Pigarov, A [University of California, San Diego; Bonoli, P. [Massachusetts Institute of Technology (MIT); Chang, C S [New York University; D' Ippolito, D. A. [Lodestar Research Corporation; Colella, Philip [Lawrence Berkeley National Laboratory (LBNL); Keyes, David E [Columbia University; Bramley, R [Indiana University; Myra, J. R. [Lodestar Research Corporation

    2007-06-01

    The FACETS (Framework Application for Core-Edge Transport Simulations) project began in January 2007 with the goal of providing core to wall transport modeling of a tokamak fusion reactor. This involves coupling previously separate computations for the core, edge, and wall regions. Such a coupling is primarily through connection regions of lower dimensionality. The project has started developing a component-based coupling framework to bring together models for each of these regions. In the first year, the core model will be a 1 dimensional model (1D transport across flux surfaces coupled to a 2D equilibrium) with fixed equilibrium. The initial edge model will be the fluid model, UEDGE, but inclusion of kinetic models is planned for the out years. The project also has an embedded Scientific Application Partnership that is examining embedding a full-scale turbulence model for obtaining the crosssurface fluxes into a core transport code.

  12. Introducing FACETS, the Framework Application for Core-Edge Transport Simulations

    Science.gov (United States)

    Cary, J. R.; Candy, J.; Cohen, R. H.; Krasheninnikov, S.; McCune, D. C.; Estep, D. J.; Larson, J.; Malony, A. D.; Worley, P. H.; Carlsson, J. A.; Hakim, A. H.; Hamill, P.; Kruger, S.; Muzsala, S.; Pletzer, A.; Shasharina, S.; Wade-Stein, D.; Wang, N.; McInnes, L.; Wildey, T.; Casper, T.; Diachin, L.; Epperly, T.; Rognlien, T. D.; Fahey, M. R.; Kuehn, J. A.; Morris, A.; Shende, S.; Feibush, E.; Hammett, G. W.; Indireshkumar, K.; Ludescher, C.; Randerson, L.; Stotler, D.; Pigarov, A. Yu; Bonoli, P.; Chang, C. S.; D'Ippolito, D. A.; Colella, P.; Keyes, D. E.; Bramley, R.; Myra, J. R.

    2007-07-01

    The FACETS (Framework Application for Core-Edge Transport Simulations) project began in January 2007 with the goal of providing core to wall transport modeling of a tokamak fusion reactor. This involves coupling previously separate computations for the core, edge, and wall regions. Such a coupling is primarily through connection regions of lower dimensionality. The project has started developing a component-based coupling framework to bring together models for each of these regions. In the first year, the core model will be a 1 ½ dimensional model (1D transport across flux surfaces coupled to a 2D equilibrium) with fixed equilibrium. The initial edge model will be the fluid model, UEDGE, but inclusion of kinetic models is planned for the out years. The project also has an embedded Scientific Application Partnership that is examining embedding a full-scale turbulence model for obtaining the crosssurface fluxes into a core transport code.

  13. Maximum stellar iron core mass

    Indian Academy of Sciences (India)

    F W Giacobbe

    2003-03-01

    An analytical method of estimating the mass of a stellar iron core, just prior to core collapse, is described in this paper. The method employed depends, in part, upon an estimate of the true relativistic mass increase experienced by electrons within a highly compressed iron core, just prior to core collapse, and is significantly different from a more typical Chandrasekhar mass limit approach. This technique produced a maximum stellar iron core mass value of 2.69 × 1030 kg (1.35 solar masses). This mass value is very near to the typical mass values found for neutron stars in a recent survey of actual neutron star masses. Although slightly lower and higher neutron star masses may also be found, lower mass neutron stars are believed to be formed as a result of enhanced iron core compression due to the weight of non-ferrous matter overlying the iron cores within large stars. And, higher mass neutron stars are likely to be formed as a result of fallback or accretion of additional matter after an initial collapse event involving an iron core having a mass no greater than 2.69 × 1030 kg.

  14. The INTEGRAL Core Observing Programme

    OpenAIRE

    Winkler, C; Gehrels, N.; Lund, N.; Schoenfelder, V.; Ubertini, P.

    1999-01-01

    The Core Programme of the INTEGRAL mission is defined as the portion of the scientific programme covering the guaranteed time observations for the INTEGRAL Science Working Team. This paper describes the current status of the Core Programme preparations and summarizes the key elements of the observing programme.

  15. The INTEGRAL Core Observing Programme

    DEFF Research Database (Denmark)

    Winkler, C.; Gehrels, N.; Lund, Niels

    1999-01-01

    The Core Programme of the INTEGRAL mission is defined as the portion of the scientific programme covering the guaranteed time observations for the INTEGRAL Science Working Team. This paper describes the current status of the Core Programme preparations and summarizes the key elements...

  16. Complicated Politics to the Core

    Science.gov (United States)

    McGuinn, Patrick

    2015-01-01

    People dislike the Common Core for several different reasons, and so it is important to disaggregate the sources of opposition and to assess and then to dispel some of the myths that have built up around it. It also is important to understand the unusual political alliances that have emerged in opposition to Common Core implementation and how they…

  17. Common Core: Victory Is Yours!

    Science.gov (United States)

    Fink, Jennifer L. W.

    2012-01-01

    In this article, the author discusses how to implement the Common Core State Standards in the classroom. She presents examples and activities that will leave teachers feeling "rosy" about tackling the new standards. She breaks down important benchmarks and shows how other teachers are doing the Core--and loving it!

  18. The INTEGRAL Core Observing Programme

    DEFF Research Database (Denmark)

    Winkler, C.; Gehrels, N.; Lund, Niels

    1999-01-01

    The Core Programme of the INTEGRAL mission is defined as the portion of the scientific programme covering the guaranteed time observations for the INTEGRAL Science Working Team. This paper describes the current status of the Core Programme preparations and summarizes the key elements...

  19. Complicated Politics to the Core

    Science.gov (United States)

    McGuinn, Patrick

    2015-01-01

    People dislike the Common Core for several different reasons, and so it is important to disaggregate the sources of opposition and to assess and then to dispel some of the myths that have built up around it. It also is important to understand the unusual political alliances that have emerged in opposition to Common Core implementation and how they…

  20. Kinetic theory and transport phenomena

    CERN Document Server

    Soto, Rodrigo

    2016-01-01

    This textbook presents kinetic theory, which is a systematic approach to describing nonequilibrium systems. The text is balanced between the fundamental concepts of kinetic theory (irreversibility, transport processes, separation of time scales, conservations, coarse graining, distribution functions, etc.) and the results and predictions of the theory, where the relevant properties of different systems are computed. The book is organised in thematic chapters where different paradigmatic systems are studied. The specific features of these systems are described, building and analysing the appropriate kinetic equations. Specifically, the book considers the classical transport of charges, the dynamics of classical gases, Brownian motion, plasmas, and self-gravitating systems, quantum gases, the electronic transport in solids and, finally, semiconductors. Besides these systems that are studied in detail, concepts are applied to some modern examples including the quark–gluon plasma, the motion of bacterial suspen...

  1. Kinetic Measurements for Enzyme Immobilization.

    Science.gov (United States)

    Cooney, Michael J

    2017-01-01

    Enzyme kinetics is the study of the chemical reactions that are catalyzed by enzymes, with a focus on their reaction rates. The study of an enzyme's kinetics considers the various stages of activity, reveals the catalytic mechanism of this enzyme, correlates its value to assay conditions, and describes how a drug or a poison might inhibit the enzyme. Victor Henri initially reported that enzyme reactions were initiated by a bond between the enzyme and the substrate. By 1910, Michaelis and Menten were advancing their work by studying the kinetics of an enzyme saccharase which catalyzes the hydrolysis of sucrose into glucose and fructose. They published their analysis and ever since the Michaelis-Menten equation has been used as the standard to describe the kinetics of many enzymes. Unfortunately, soluble enzymes must generally be immobilized to be reused for long times in industrial reactors. In addition, other critical enzyme properties have to be improved like stability, activity, inhibition by reaction products, and selectivity towards nonnatural substrates. Immobilization is by far the chosen process to achieve these goals.Although the Michaelis-Menten approach has been regularly adapted to the analysis of immobilized enzyme activity, its applicability to the immobilized state is limited by the barriers the immobilization matrix places upon the measurement of compounds that are used to model enzyme kinetics. That being said, the estimated value of the Michaelis-Menten coefficients (e.g., V max, K M) can be used to evaluate effects of immobilization on enzyme activity in the immobilized state when applied in a controlled manner. In this review enzyme activity and kinetics are discussed in the context of the immobilized state, and a few novel protocols are presented that address some of the unique constraints imposed by the immobilization barrier.

  2. Kinetics of the thermal decomposition of pine needles

    Directory of Open Access Journals (Sweden)

    Dhaundiyal Alok

    2015-12-01

    Full Text Available A kinetic study of the pyrolysis process of pine needles was examined using a thermogravimetric analyser. The weight loss was measured in nitrogen atmosphere at a purge flow rate of 100 ml/min. The samples were heated over a range of temperature of 19°C–600°C with a heating rate of 10°C/min. The results obtained from the thermal decomposition process indicate that there are three main stages: dehydration, active and passive pyrolysis. The kinetic parameters for the different samples, such as activation energy and pre-exponential factor, are obtained by the shrinking core model (reaction-controlled regime, the model-free, and the first-order model. Experimental results showed that the shrinking model is in good agreement and can be successfully used to understand degradation mechanism of loose biomass. The result obtained from the reaction-controlled regime represented actual values of kinetic parameters which are the same for the whole pyrolysis process; whereas the model-free method presented apparent values of kinetic parameters, as they are dependent on the unknown function ϕ(C, on the sum of the parameters of the physical processes, and on the chemical reactions that happen simultaneously during pyrolysis. Experimental results showed that values of kinetic constant from the first-order model and the SCM are in good agreement and can be successfully used to understand the behaviour of loose biomass (pine needles in the presence of inert atmosphere. Using TGA results, the simulating pyrolysis can be done, with the help of computer software, to achieve a comprehensive detail of the devolatilization process of different types of biomasses.

  3. Chemical kinetics and combustion modeling

    Energy Technology Data Exchange (ETDEWEB)

    Miller, J.A. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

    The goal of this program is to gain qualitative insight into how pollutants are formed in combustion systems and to develop quantitative mathematical models to predict their formation rates. The approach is an integrated one, combining low-pressure flame experiments, chemical kinetics modeling, theory, and kinetics experiments to gain as clear a picture as possible of the process in question. These efforts are focused on problems involved with the nitrogen chemistry of combustion systems and on the formation of soot and PAH in flames.

  4. Selected readings in chemical kinetics

    CERN Document Server

    Back, Margaret H

    2013-01-01

    Selected Readings in Chemical Kinetics covers excerpts from 12 papers in the field of general and gas-phase kinetics. The book discusses papers on the laws of connexion between the conditions of a chemical change and its amount; on the reaction velocity of the inversion of the cane sugar by acids; and the calculation in absolute measure of velocity constants and equilibrium constants in gaseous systems. The text then tackles papers on simple gas reactions; on the absolute rate of reactions in condensed phases; on the radiation theory of chemical action; and on the theory of unimolecular reacti

  5. Robustness Analysis of Kinetic Structures

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Sørensen, John Dalsgaard

    2009-01-01

    The present paper considers robustness of kinetic structures. Robustness of structures has obtained a renewed interest due to a much more frequent use of advanced types of structures with limited redundancy and serious consequences in case of failure. Especially for these types of structural syst...... systems, it is of interest to investigate how robust the structures are, or what happens if a structural element is added to or removed from the original structure. The present paper discusses this issue for kinetic structures in architecture....

  6. Chemical kinetics and reaction dynamics

    CERN Document Server

    Houston, Paul L

    2006-01-01

    This text teaches the principles underlying modern chemical kinetics in a clear, direct fashion, using several examples to enhance basic understanding. It features solutions to selected problems, with separate sections and appendices that cover more technical applications.Each chapter is self-contained and features an introduction that identifies its basic goals, their significance, and a general plan for their achievement. This text's important aims are to demonstrate that the basic kinetic principles are essential to the solution of modern chemical problems, and to show how the underlying qu

  7. Core body temperature in obesity.

    Science.gov (United States)

    Heikens, Marc J; Gorbach, Alexander M; Eden, Henry S; Savastano, David M; Chen, Kong Y; Skarulis, Monica C; Yanovski, Jack A

    2011-05-01

    A lower core body temperature set point has been suggested to be a factor that could potentially predispose humans to develop obesity. We tested the hypothesis that obese individuals have lower core temperatures than those in normal-weight individuals. In study 1, nonobese [body mass index (BMI; in kg/m(2)) temperature-sensing capsules, and we measured core temperatures continuously for 24 h. In study 2, normal-weight (BMI of 18-25) and obese subjects swallowed temperature-sensing capsules to measure core temperatures continuously for ≥48 h and kept activity logs. We constructed daily, 24-h core temperature profiles for analysis. Mean (±SE) daily core body temperature did not differ significantly between the 35 nonobese and 46 obese subjects (36.92 ± 0.03°C compared with 36.89 ± 0.03°C; P = 0.44). Core temperature 24-h profiles did not differ significantly between 11 normal-weight and 19 obese subjects (P = 0.274). Women had a mean core body temperature ≈0.23°C greater than that of men (36.99 ± 0.03°C compared with 36.76 ± 0.03°C; P body temperature. It may be necessary to study individuals with function-altering mutations in core temperature-regulating genes to determine whether differences in the core body temperature set point affect the regulation of human body weight. These trials were registered at clinicaltrials.gov as NCT00428987 and NCT00266500.

  8. Non-kinetic capabilities: complementing the kinetic prevalence to targeting

    NARCIS (Netherlands)

    Ducheine, P.A.L.; Ducheine, P.A.L.; Schmitt, M.N.; Osinga, F.P.B.

    2016-01-01

    Targeting is used in military doctrine to describe a military operational way, using (military) means to influence a target (or addressee) in order to achieve designated political and/or military goals. The four factors italicized are used to analyse non-kinetic targeting, thereby complementing our

  9. Non-kinetic capabilities: complementing the kinetic prevalence to targeting

    NARCIS (Netherlands)

    Ducheine, P.A.L.; Ducheine, P.A.L.; Schmitt, M.N.; Osinga, F.P.B.

    2016-01-01

    Targeting is used in military doctrine to describe a military operational way, using (military) means to influence a target (or addressee) in order to achieve designated political and/or military goals. The four factors italicized are used to analyse non-kinetic targeting, thereby complementing our

  10. Non-kinetic capabilities: complementing the kinetic prevalence to targeting

    NARCIS (Netherlands)

    Ducheine, P.

    2014-01-01

    Targeting is used in military doctrine to describe a military operational way, using (military) means to influence a target (or addressee) in order to achieve designated political and/or military goals. The four factors italicized are used to analyse non-kinetic targeting, complementing our

  11. Core-in-cup tablet design of metoprolol succinate and its evaluation for controlled release.

    Science.gov (United States)

    Nagaraju, Ravouru; Meera, Durgumahanthi Sai; Kaza, Rajesh; Arvind, Vakati Venkata; Venkateswarlu, Vobalaboina

    2009-12-01

    The core-in-cup matrix tablets of Metoprolol succinate were prepared by wet granulation technique. Of all the investigated formulations, the optimized formulation of MS-09 followed zero-order kinetics of drug release. Trail on MS-09 was formulated using 7.5% hydrogenated castor-oil (HCO) and 4% of hydroxyl propyl methylcellulose (HPMC K15M) with an objective to achieve a linear release profile for 24 h. There is no initial burst release, with 16.17% of drug released during the first hour and release was extended up to 24 hrs. Study of drug release kinetics was performed by application of dissolution data to various kinetic equations like zero-order; first order, Higuchi and Korsmeyer-Peppas, from R(2) value (0.9975) it was concluded that the drug release followed zero order kinetics with both erosion and diffusion as the release mechanisms.

  12. COSIS: COre State Indication System

    Energy Technology Data Exchange (ETDEWEB)

    Cho, J. Y.; Lee, K. B.; Koo, B. S.; Lee, W. K.; Lee, C. C; Zee, S. Q

    2006-02-15

    COSIS (COre State Indication System) which implemented in the SMART research reactor plays a role to supply the core state parameters or graphs for the operator to recognize the core state effectively. The followings are the main functions of COSIS. (1) Validity Check for the Process Signals and Determination of the COSIS Inputs (SIGVAL) (2) Coolant Flow Rate Calculation (FLOW) (3) Core Thermal Power Calculation (COREPOW) (4) In-core 3-Dimensional Power Distribution Calculation and Peaking Parameters Generation (POWER3D) (5) Azimuthal Tilt Calculation (AZITILT). This report describes the methodology of COSIS which produces the core state parameters using the process and detector signals. In the SIGVAL module, COSIS checks most signals except for the CEA position and determines the input signals. In the FLOW module, the corelation coefficient between the RPM signal and coolant flow is updated from the energy balance at the steam generator, and the coolant flow rate is calculated using the RPM signal. In the COREPOW module, the secondary calorimetric power, the primary {delta}T power and the ex-core power are calculated, and the final core thermal power and biased core power are determined. In the POWER3D module, the 3-dimensional power distribution is calculated using the in-core detector signal, and the 3-D peaking factor, 2-D radial peaking factor, axial offset, maximum linear power density are produced. In the AZITILT module, the arithmetic averaged and vector averaged azimuthal tilts are calculated, and the final tilt is determined. The COSIS performance test of the COSIS is performed for the temperature compensation method, the COREPOW and the POWER3D modules. The test for the temperature compensation method is performed for the temperature variations of the linear, parabolic, exponential, sine function. The test shows that the implemented temperature compensation method works soundly. The COREPOW test is performed by varying the core power from the initial

  13. Building a Hydrodynamics Code with Kinetic Theory

    CERN Document Server

    Sagert, Irina; Colbry, Dirk; Pickett, Rodney; Strother, Terrance

    2013-01-01

    We report on the development of a test-particle based kinetic Monte Carlo code for large systems and its application to simulate matter in the continuum regime. Our code combines advantages of the Direct Simulation Monte Carlo and the Point-of-Closest-Approach methods to solve the collision integral of the Boltzmann equation. With that, we achieve a high spatial accuracy in simulations while maintaining computational feasibility when applying a large number of test-particles. The hybrid setup of our approach allows us to study systems which move in and out of the hydrodynamic regime, with low and high particle densities. To demonstrate our code's ability to reproduce hydrodynamic behavior we perform shock wave simulations and focus here on the Sedov blast wave test. The blast wave problem describes the evolution of a spherical expanding shock front and is an important verification problem for codes which are applied in astrophysical simulation, especially for approaches which aim to study core-collapse supern...

  14. Epistemology and ontology in core ontologies: FOLaw and LRI-Core, two core ontologies for law

    NARCIS (Netherlands)

    Breukers, J.A.P.J.; Hoekstra, R.J.

    2004-01-01

    For more than a decade constructing ontologies for legal domains, we, at the Leibniz Center for Law, felt really the need to develop a core ontology for law that would enable us to re-use the common denominator of the various legal domains. In this paper we present two core ontologies for law. The

  15. [Clinical benefit of HCV core antigen assay in patients receiving interferon and ribavirin combination therapy].

    Science.gov (United States)

    Higashimoto, Makiko; Takahashi, Masahiko; Jokyu, Ritsuko; Saito, Hidetsugu

    2006-02-01

    A highly sensitive second generation HCV core antigen assay has recently been developed. We compared viral disappearance and kinetics data between commercially available core antigen assays, Lumipulse Ortho HCV Ag, and a quantitative HCV RNA PCR assay, Cobas Amplicor HCV Monitor Test, Version 2 to estimate the predictive benefit of sustained viral response (SVR) and non-SVR in 59 patients treated with interferon and ribavirin combination therapy. We found a good correlation between HCV core Ag and HCV RNA level regardless of genotype. Although the sensitivity of the core antigen assay was lower than PCR, the dynamic range was broader than that of the PCR assay, so that we did not need to dilute the samples in 59 patients. We detected serial decline of core Ag levels in 24 hrs, 7 days and 14 days after interferon combination therapy. The decline of core antigen levels was significant in SVR patients compared to non-SVR as well as in genotype 2a, 2b patients compared to 1b. Core antigen-negative on day 1 could predict all 10 SVR patients (PPV = 100%), whereas RNA-negative could predict 22 SVR out of 25 on day 14 (PPV = 88.0%). None of the patients who had detectable serum core antigen on day 14 became SVR(NPV = 100%), although NPV was 91.2% on RNA negativity. An easy, simple, low cost new HCV core antigen detecting system seems to be useful for assessing and monitoring IFN treatment for HCV.

  16. ASRL core research program 2010 - 2011

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2010-01-15

    This article summarized the core research program of Alberta Sulphur Research Ltd. The high-priority projects are improved liquid sulfur degassing technologies, improved tail gas treatment processes, oxygen consumption in amine systems, formation of hydrogen sulphide (H{sub 2}S) in shale gas reservoirs and during the steam assisted gravity drainage (SAGD) recovery of heavy oil and bitumen, designer hydrocarbon sulfur solvents for sour gas production, determination of the kinetics of H{sub 2}S oxidation in compression systems, H{sub 2}S and sulphur dioxide (SO{sub 2}) solubility in liquid sulfur updating and checking FTIR calibrations, low tonnage sulfur recovery, the effect of BTX on reduction catalysts used in Claus tail gas processing, measurement of acid gas properties at high pressure, catalytic tail gas incineration, and sulfur dust properties. The projects identified as important areas of research are acid gas injection water holding capacity for acid gas mixtures; rate of decomposition of polymeric sulfur; ammonium salt plugging in the Claus Converter Train; re-examination of catalytic partial oxidation for sulfur recovery from low H{sub 2}S content hydrocarbon contaminated acid gas; primary upgrading of oil sands bitumen; prediction of sulfur deposition in sour gas reservoirs; and new extended uses of elemental sulfur. There are two fundamental research programs, which include ongoing research and partial external funding: production of C{sub 3} - C{sub 6} olefins, high octane alkylate, and valuable petrochemicals and computational modeling of catalytic systems. The commercial and specific objectives of each project were described. Two special projects, which aim to take Alberta Sulphur Research Ltd. (ASRL) core research to the commercial demonstration phase, involve injection of SO{sub 2} into disposal reservoirs and above-ground sulfur storage. 1 tab., 22 figs.

  17. Systematic technology evaluation program for SiC/SiC composite-based accident-tolerant LWR fuel cladding and core structures: Revision 2015

    Energy Technology Data Exchange (ETDEWEB)

    Katoh, Yutai [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Terrani, Kurt A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-08-01

    Fuels and core structures in current light water reactors (LWR’s) are vulnerable to catastrophic failure in severe accidents as unfortunately evidenced by the March 2011 Fukushima Dai-ichi Nuclear Power Plant Accident. This vulnerability is attributed primarily to the rapid oxidation kinetics of zirconium alloys in a water vapor environment at very high temperatures. Zr alloys are the primary material in LWR cores except for the fuel itself. Therefore, alternative materials with reduced oxidation kinetics as compared to zirconium alloys are sought to enable enhanced accident-tolerant fuels and cores.

  18. Kinetic theory of hard spheres

    NARCIS (Netherlands)

    Beijeren, H. van; Ernst, M.H.

    1979-01-01

    Kinetic equations for the hard-sphere system are derived by diagrammatic techniques. A linear equation is obtained for the one-particle-one particle equilibrium time correlation function and a nonlinear equation for the one-particle distribution function in nonequilibrium. Both equations are nonloca

  19. Superconductivity by kinetic energy saving?

    NARCIS (Netherlands)

    Van der Marel, D; Molegraaf, HJA; Presura, C; Santoso, [No Value; Hewson, AC; Zlatic,

    2003-01-01

    A brief introduction is given in the generic microscopic framework of superconductivity. The consequences for the temperature dependence of the kinetic energy, and the correlation energy are discussed for two cases: The BCS scenario and the non-Fermi liquid scenario. A quantitative comparison is mad

  20. Biodegradation kinetics at low concentrations (

    DEFF Research Database (Denmark)

    Toräng, Lars; Albrechtsen, Hans-Jørgen; Nyholm, Niels

    2000-01-01

    Aerobic biodegradation of 2,4-dichlorophenoxyacetic acid (2,4-D) was studied in groundwater added sediment fines. At concentrations at or below 1 mu g/L of 2,4-D degradation kinetic was of true first order without significant growth of specific degraders and with half-life for mineralization...

  1. Robustness Analysis of Kinetic Structures

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Sørensen, John Dalsgaard

    2009-01-01

    Kinetic structures in architecture follows a new trend which is emerging in responsive architecture coined by Nicholas Negroponte when he proposed that architecture may benefit from the integration of computing power into built spaces and structures, and that better performing, more rational...

  2. Disco Dancing and Kinetic Theory

    Science.gov (United States)

    Karakas, Mehmet

    2010-01-01

    This paper provides an example of an innovative science activity used in a science methods course for future elementary teachers at a small university in northeastern Turkey. The activity aims to help prospective elementary teachers understand kinetic-molecular theory in a simple way and to expose these preservice teachers to an innovative…

  3. Mass Conservation and Chemical Kinetics.

    Science.gov (United States)

    Barbara, Thomas M.; Corio, P. L.

    1980-01-01

    Presents a method for obtaining all mass conservation conditions implied by a given mechanism in which the conditions are used to simplify integration of the rate equations and to derive stoichiometric relations. Discusses possibilities of faulty inference of kinetic information from a given stoichiometry. (CS)

  4. Superconductivity by kinetic energy saving?

    NARCIS (Netherlands)

    Van der Marel, D; Molegraaf, HJA; Presura, C; Santoso, [No Value; Hewson, AC; Zlatic,

    2003-01-01

    A brief introduction is given in the generic microscopic framework of superconductivity. The consequences for the temperature dependence of the kinetic energy, and the correlation energy are discussed for two cases: The BCS scenario and the non-Fermi liquid scenario. A quantitative comparison is

  5. Robustness Analysis of Kinetic Structures

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Sørensen, John Dalsgaard

    2009-01-01

    Kinetic structures in architecture follows a new trend which is emerging in responsive architecture coined by Nicholas Negroponte when he proposed that architecture may benefit from the integration of computing power into built spaces and structures, and that better performing, more rational...

  6. Superconductivity by kinetic energy saving?

    NARCIS (Netherlands)

    Van der Marel, D; Molegraaf, HJA; Presura, C; Santoso, [No Value; Hewson, AC; Zlatic,

    2003-01-01

    A brief introduction is given in the generic microscopic framework of superconductivity. The consequences for the temperature dependence of the kinetic energy, and the correlation energy are discussed for two cases: The BCS scenario and the non-Fermi liquid scenario. A quantitative comparison is mad

  7. Surfactant adsorption kinetics in microfluidics

    Science.gov (United States)

    Riechers, Birte; Maes, Florine; Akoury, Elias; Semin, Benoît; Gruner, Philipp; Baret, Jean-Christophe

    2016-10-01

    Emulsions are metastable dispersions. Their lifetimes are directly related to the dynamics of surfactants. We design a microfluidic method to measure the kinetics of adsorption of surfactants to the droplet interface, a key process involved in foaming, emulsification, and droplet coarsening. The method is based on the pH decay in the droplet as a direct measurement of the adsorption of a carboxylic acid surfactant to the interface. From the kinetic measurement of the bulk equilibration of the pH, we fully determine the adsorption process of the surfactant. The small droplet size and the convection during the droplet flow ensure that the transport of surfactant through the bulk is not limiting the kinetics of adsorption. To validate our measurements, we show that the adsorption process determines the timescale required to stabilize droplets against coalescence, and we show that the interface should be covered at more than 90% to prevent coalescence. We therefore quantitatively link the process of adsorption/desorption, the stabilization of emulsions, and the kinetics of solute partitioning—here through ion exchange—unraveling the timescales governing these processes. Our method can be further generalized to other surfactants, including nonionic surfactants, by making use of fluorophore-surfactant interactions.

  8. Chemical kinetics on extrasolar planets.

    Science.gov (United States)

    Moses, Julianne I

    2014-04-28

    Chemical kinetics plays an important role in controlling the atmospheric composition of all planetary atmospheres, including those of extrasolar planets. For the hottest exoplanets, the composition can closely follow thermochemical-equilibrium predictions, at least in the visible and infrared photosphere at dayside (eclipse) conditions. However, for atmospheric temperatures approximately planets.

  9. Kinetic Modeling of Biological Systems

    Energy Technology Data Exchange (ETDEWEB)

    Resat, Haluk; Petzold, Linda; Pettigrew, Michel F.

    2009-04-21

    The dynamics of how its constituent components interact define the spatio-temporal response of a natural system to stimuli. Modeling the kinetics of the processes that represent a biophysical system has long been pursued with the aim of improving our understanding of the studied system. Due to the unique properties of biological systems, in addition to the usual difficulties faced in modeling the dynamics of physical or chemical systems, biological simulations encounter difficulties that result from intrinsic multiscale and stochastic nature of the biological processes. This chapter discusses the implications for simulation of models involving interacting species with very low copy numbers, which often occur in biological systems and give rise to significant relative fluctuations. The conditions necessitating the use of stochastic kinetic simulation methods and the mathematical foundations of the stochastic simulation algorithms are presented. How the well-organized structural hierarchies often seen in biological systems can lead to multiscale problems, and possible ways to address the encountered computational difficulties are discussed. We present the details of the existing kinetic simulation methods, and discuss their strengths and shortcomings. A list of the publicly available kinetic simulation tools and our reflections for future prospects are also provided.

  10. An equilibrium and kinetic modeling

    African Journals Online (AJOL)

    SERVER

    2007-06-18

    Jun 18, 2007 ... Potato dextrose agar medium was prepared by taking 200 g of peeled and sliced potato with .... of glucose as carbon source and ammonium chloride as nitrogen source each. .... Pore and solid diffusion kinetics in fixed bed ...

  11. Solving Simple Kinetics without Integrals

    Science.gov (United States)

    de la Pen~a, Lisandro Herna´ndez

    2016-01-01

    The solution of simple kinetic equations is analyzed without referencing any topic from differential equations or integral calculus. Guided by the physical meaning of the rate equation, a systematic procedure is used to generate an approximate solution that converges uniformly to the exact solution in the case of zero, first, and second order…

  12. Kinetic energy equations for the average-passage equation system

    Science.gov (United States)

    Johnson, Richard W.; Adamczyk, John J.

    1989-01-01

    Important kinetic energy equations derived from the average-passage equation sets are documented, with a view to their interrelationships. These kinetic equations may be used for closing the average-passage equations. The turbulent kinetic energy transport equation used is formed by subtracting the mean kinetic energy equation from the averaged total instantaneous kinetic energy equation. The aperiodic kinetic energy equation, averaged steady kinetic energy equation, averaged unsteady kinetic energy equation, and periodic kinetic energy equation, are also treated.

  13. Kinetic energy equations for the average-passage equation system

    Science.gov (United States)

    Johnson, Richard W.; Adamczyk, John J.

    1989-01-01

    Important kinetic energy equations derived from the average-passage equation sets are documented, with a view to their interrelationships. These kinetic equations may be used for closing the average-passage equations. The turbulent kinetic energy transport equation used is formed by subtracting the mean kinetic energy equation from the averaged total instantaneous kinetic energy equation. The aperiodic kinetic energy equation, averaged steady kinetic energy equation, averaged unsteady kinetic energy equation, and periodic kinetic energy equation, are also treated.

  14. Multi-Core Cache Hierarchies

    CERN Document Server

    Balasubramonian, Rajeev

    2011-01-01

    A key determinant of overall system performance and power dissipation is the cache hierarchy since access to off-chip memory consumes many more cycles and energy than on-chip accesses. In addition, multi-core processors are expected to place ever higher bandwidth demands on the memory system. All these issues make it important to avoid off-chip memory access by improving the efficiency of the on-chip cache. Future multi-core processors will have many large cache banks connected by a network and shared by many cores. Hence, many important problems must be solved: cache resources must be allocat

  15. Characterizing Facesheet/Core Disbonding in Honeycomb Core Sandwich Structure

    Science.gov (United States)

    Rinker, Martin; Ratcliffe, James G.; Adams, Daniel O.; Krueger, Ronald

    2013-01-01

    Results are presented from an experimental investigation into facesheet core disbonding in carbon fiber reinforced plastic/Nomex honeycomb sandwich structures using a Single Cantilever Beam test. Specimens with three, six and twelve-ply facesheets were tested. Specimens with different honeycomb cores consisting of four different cell sizes were also tested, in addition to specimens with three different widths. Three different data reduction methods were employed for computing apparent fracture toughness values from the test data, namely an area method, a compliance calibration technique and a modified beam theory method. The compliance calibration and modified beam theory approaches yielded comparable apparent fracture toughness values, which were generally lower than those computed using the area method. Disbonding in the three-ply facesheet specimens took place at the facesheet/core interface and yielded the lowest apparent fracture toughness values. Disbonding in the six and twelve-ply facesheet specimens took place within the core, near to the facesheet/core interface. Specimen width was not found to have a significant effect on apparent fracture toughness. The amount of scatter in the apparent fracture toughness data was found to increase with honeycomb core cell size.

  16. On the oxidation of uraninite from natural reactor cores

    Energy Technology Data Exchange (ETDEWEB)

    Cui, D.; Eriksen, T.; Eklund, U.B.

    1999-07-01

    Natural nuclear reactors provide unique evidence in helping to understand the processes that might occur over long timescales in radioactive waste disposal sites. In the presented work, the extent and kinetics of oxidation of core material from the Oklo-Bangombe natural reactors are investigated. The X-ray powder diffraction analysis shows that the uraninites core samples from the Bangombe Reactor and Oklo Reactor 2, and Oklo Reactor 13 have the same unit-cell parameters as synthetic UO{sub 2.25}. A significant amount of fourmarierite, Pb(UO{sub 2}){sub 4}O{sub 3}(OH){sub 4}.4H{sub 2}O, was identified in the core samples from two shallow reactors Bangombe and Oklo 2, but not in the deeper reactor Oklo 13. The results of U(IV)/U(IV) measurements indicate that the extent of oxidative weathering of shallow reactors (Bangombe and Oklo 2) is greater than for the deeper reactor Oklo 13. Evaporable organic compounds found in the uraninite inclusion containing bitumen at the edge of Okelobondo Reactor (400 C) and in the black shale immediately above the Bangombe Reactor (260 C) may work as a reducing buffer or/and a hydrophobic water shield to depress the oxidative dissolution of the uraninite cores.

  17. Introduction to the Core Curriculum in GIS

    OpenAIRE

    2015-01-01

    This short narrative introduces the Core Curriculum in GIS and provides a historical overview of the Core Curriculum Project, including the later Core Curriculum in GIScience and Core Curriculum for Technical Programs. Appended to this description is an original pamphlet advertising the Core Curriculum in GIS.

  18. Kinetic investigation of wood pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Thurner, F.; Mann, U.; Beck, S. R.

    1980-06-01

    The objective of this investigation was to determine the kinetics of the primary reactions of wood pyrolysis. A new experimental method was developed which enabled us to measure the rate of gas, tar, and char production while taking into account the temperature variations during the wood heating up. The experimental method developed did not require any sophisticated instruments. It facilitated the collection of gas, tar and residue (unreacted wood and char) as well as accurate measurement of the temperature inside the wood sample. Expressions relating the kinetic parameters to the measured variables were derived. The pyrolysis kinetics was investigated in the range of 300 to 400/sup 0/C at atmospheric pressure and under nitrogen atmosphere. Reaction temperature and mass fractions of gas, tar, and residue were measured as a function of time. Assuming first-order reactions, the kinetic parameters were determined using differential method. The measured activation energies of wood pyrolysis to gas, tar, and char were 88.6, 112.7, and 106.5 kJ/mole, respectively. These kinetic data were then used to predict the yield of the various pyrolysis products. It was found that the best prediction was obtained when an integral-mean temperature obtained from the temperature-time curve was used as reaction temperature. The pyrolysis products were analyzed to investigate the influence of the pyrolysis conditions on the composition. The gas consisted mainly of carbon dioxide, carbon monoxide, oxygen, and C/sub 3//sup +/-compounds. The gas composition depended on reaction time as well as reactor temperature. The tar analysis indicated that the tar consisted of about seven compounds. Its major compound was believed to be levoglucosan. Elemental analysis for the char showed that the carbon content increased with increasing temperature.

  19. The Magnetic Furnace: Intense Core Dynamos in B Stars

    Science.gov (United States)

    Augustson, Kyle C.; Brun, Allan Sacha; Toomre, Juri

    2016-10-01

    The dynamo action achieved in the convective cores of main-sequence massive stars is explored here through three-dimensional (3D) global simulations of convective core dynamos operating within a young 10 {M}⊙ B-type star, using the anelastic spherical harmonic code. These simulations capture the inner 65% of this star by radius, encompassing the convective nuclear-burning core (about 23% by radius) and a portion of the overlying radiative envelope. Eight rotation rates are considered, ranging from 0.05% to 16% of the surface breakup velocity, thereby capturing both convection that barely senses the effects of rotation and other situations in which the Coriolis forces are prominent. The vigorous dynamo action realized within all of these turbulent convective cores builds magnetic fields with peak strengths exceeding a megagauss, with the overall magnetic energy (ME) in the faster rotators reaching super-equipartition levels compared to the convective kinetic energy (KE). The core convection typically involves turbulent columnar velocity structures roughly aligned with the rotation axis, with magnetic fields threading through these rolls and possessing complex linkages throughout the core. The very strong fields are able to coexist with the flows without quenching them through Lorentz forces. The velocity and magnetic fields achieve such a state by being nearly co-aligned, and with peak magnetic islands being somewhat displaced from the fastest flows as the intricate evolution proceeds. As the rotation rate is increased, the primary force balance shifts from nonlinear advection balancing Lorentz forces to a magnetostrophic balance between Coriolis and Lorentz forces.

  20. Design and Performance of South Ukraine Nuclear Power Plant Mixed Cores

    Energy Technology Data Exchange (ETDEWEB)

    Abdullayev, A. M.; Baydulin, V.; Zhukov, A. I.; Latorre, Richard

    2011-09-24

    In 2010, 42 Westinghouse fuel assemblies (WFAs) were loaded into the core of South Ukraine Nuclear Power Plant (SUNPP) Unit 3 after four successful cycles with 6 Westinghouse Lead Test Assemblies. The scope of safety substantiating documents required for the regulatory approval of this mixed core was extended considerably, particularly with development and implementation of new methodologies and 3-D kinetic codes. Additional verification for all employed codes was also performed. Despite the inherent hydraulic non-uniformity of a mixed core, it was possible to demonstrate that all design and operating restrictions for three different types of fuel (TVS-M, TVSA and WFA) loaded in the core were conservatively met. This paper provides the main results from the first year of operation of the core loaded with 42 WFAs, the predicted parameters for the transition and equilibrium cycles with WFAs, comparisons of predicted versus measured core parameters, as well as the acceptable margin evaluation results for reactivity accidents using the 3-D kinetic codes. To date WFA design parameters have been confirmed by operation experience.

  1. Colloidal crystals of core-shell type spheres with poly(styrene) core and poly(ethylene oxide) shell.

    Science.gov (United States)

    Okamoto, Junichi; Kimura, Hiroshi; Tsuchida, Akira; Okubo, Tsuneo; Ito, Koichi

    2007-04-15

    Elastic modulus and crystal growth kinetics have been studied for colloidal crystals of core-shell type colloidal spheres (diameter=160-200 nm) in aqueous suspension. Crystallization properties of three kinds of spheres, which have poly(styrene) core and poly(ethylene oxide) shell with different oxyethylene chain length (n=50, 80 and 150), were examined by reflection spectroscopy. The suspensions were deionized exhaustively for more than 1 year using mixed bed of ion-exchange resins. The rigidities of the crystals range from 0.11 to 120 Pa and from 0.56 to 76 Pa for the spheres of n=50 and 80, respectively, and increase sharply as the sphere volume fraction increase. The g factor, parameter for crystal stability, range from 0.029 to 0.13 and from 0.040 to 0.11 for the spheres of n=50 and 80, respectively. These g values indicate the formation of stable crystals, and the values were decreased as the sphere volume fraction increased. Two components of crystal growth rate coefficients, fast and slow, were observed in the order from 10(-3) to 10(1)s(-1). This is due to the secondary process in the colloidal crystallization mechanism, corresponding to reorientation from metastable crystals formed in the primary process and/or Ostwald-ripening process. There are no distinct differences in the structural, kinetic and elastic properties among the colloidal crystals of the different core-shell size spheres, nor difference between those of core-shell spheres and silica or poly(styrene) spheres. The results are very reasonably interpreted by the fact that colloidal crystals are formed in a closed container owing to long-range repulsive forces and the Brownian movement of colloidal spheres surrounded by extended electrical double layers, and their formation is not influenced by the rigidity and internal structure of the spheres.

  2. Assessing Core Competencies

    Science.gov (United States)

    Narayanan, M.

    2004-12-01

    Catherine Palomba and Trudy Banta offer the following definition of assessment, adapted from one provided by Marches in 1987. Assessment in the systematic collection, review, and use of information about educational programs undertaken for the purpose of improving student learning and development. (Palomba and Banta 1999). It is widely recognized that sophisticated computing technologies are becoming a key element in today's classroom instructional techniques. Regardless, the Professor must be held responsible for creating an instructional environment in which the technology actually supplements learning outcomes of the students. Almost all academic disciplines have found a niche for computer-based instruction in their respective professional domain. In many cases, it is viewed as an essential and integral part of the educational process. Educational institutions are committing substantial resources to the establishment of dedicated technology-based laboratories, so that they will be able to accommodate and fulfill students' desire to master certain of these specific skills. This type of technology-based instruction may raise some fundamental questions about the core competencies of the student learner. Some of the most important questions are : 1. Is the utilization of these fast high-powered computers and user-friendly software programs creating a totally non-challenging instructional environment for the student learner ? 2. Can technology itself all too easily overshadow the learning outcomes intended ? 3. Are the educational institutions simply training students how to use technology rather than educating them in the appropriate field ? 4. Are we still teaching content-driven courses and analysis oriented subject matter ? 5. Are these sophisticated modern era technologies contributing to a decline in the Critical Thinking Capabilities of the 21st century technology-savvy students ? The author tries to focus on technology as a tool and not on the technology

  3. On the relationships between the Michaelis-Menten kinetics, reverse Michaelis-Menten kinetics, equilibrium chemistry approximation kinetics, and quadratic kinetics

    National Research Council Canada - National Science Library

    Tang, J. Y

    2015-01-01

      The Michaelis-Menten kinetics and the reverse Michaelis-Menten kinetics are two popular mathematical formulations used in many land biogeochemical models to describe how microbes and plants would...

  4. Developments in kinetic modelling of chalcocite particle oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Jaervi, J.; Ahokainen, T.; Jokilaakso, A. [Helsinki Univ. of Technology, Otaniemi (Finland). Lab. of Materials Processing and Powder Metallurgy

    1997-12-31

    A mathematical model for simulating chalcocite particle oxidation is presented. Combustion of pure chalcocite with oxygen is coded as a kinetic module which can be connected as a separate part of commercial CFD-package, PHOENICS. Heat transfer, fluid flow and combustion phenomena can be simulated using CFD-calculation together with the kinetic model. Interaction between gas phase and particles are taken into account by source terms. The aim of the kinetic model is to calculate the particle temperature, contents of species inside the particle, oxygen consumption and formation of sulphur dioxide. Four oxidation reactions are considered and the shrinking core model is used to describe the rate of the oxidation reactions. The model is verified by simulating the particle oxidation reactions in a laboratory scale laminar-flow furnace under different conditions and the model predicts the effects of charges correctly. In the future, the model validation will be done after experimental studies in the laminar flow-furnace. (author) 18 refs.

  5. Viral Evolution Core | FNLCR Staging

    Science.gov (United States)

    Brandon F. Keele, Ph.D. PI/Senior Principal Investigator, Retroviral Evolution Section Head, Viral Evolution Core Leidos Biomedical Research, Inc. Frederick National Laboratory for Cancer Research Frederick, MD 21702-1201 Tel: 301-846-173

  6. Lunar Core Drive Tubes Summary

    Data.gov (United States)

    National Aeronautics and Space Administration — Contains a brief summary and high resolution imagery from various lunar rock and core drive tubes collected from the Apollo and Luna missions to the moon.

  7. Cholesterol increases kinetic, energetic, and mechanical stability of the human β2-adrenergic receptor

    DEFF Research Database (Denmark)

    Zocher, Michael; Zhang, Cheng; Rasmussen, Søren Gøgsig Faarup;

    2012-01-01

    the kinetic, energetic, and mechanical stability of almost every structural segment at sufficient magnitude to alter the structure and functional relationship of β(2)AR. One exception was the structural core segment of β(2)AR, which establishes multiple ligand binding sites, and its properties were...... to quantify the mechanical strength and flexibility, conformational variability, and kinetic and energetic stability of structural segments stabilizing the human β(2)-adrenergic receptor (β(2)AR) in the absence and presence of the cholesterol analog cholesteryl hemisuccinate (CHS). CHS considerably increased...

  8. A Method to Use Solar Energy for the Production of Gas from Marine Hydrate-Bearing Sediments: A Case Study on the Shenhu Area

    Directory of Open Access Journals (Sweden)

    Fenglin Tang

    2010-12-01

    Full Text Available A method is proposed that uses renewable solar energy to supply energy for the exploitation of marine gas hydrates using thermal stimulation. The system includes solar cells, which are installed on the platform and a distributor with electric heaters. The solar module is connected with electric heaters via an insulated cable, and provides power to the heaters. Simplified equations are given for the calculation of the power of the electric heaters and the solar battery array. Also, a case study for the Shenhu area is provided to illustrate the calculation of the capacity of electric power and the solar cell system under ideal conditions. It is shown that the exploitation of marine gas hydrates by solar energy is technically and economically feasible in typical marine areas and hydrate reservoirs such as the Shenhu area. This method may also be used as a good assistance for depressurization exploitation of marine gas hydrates in the future.

  9. Estimation of seismic attenuation of gas hydrate bearing sediments from multi-channel seismic data: A case study from Krishna-Godavari offshore basin

    Digital Repository Service at National Institute of Oceanography (India)

    Dewangan, P.; Mandal, R.; Jaiswal, P.; Ramprasad, T.; Sriram, G.

    the quality of the manuscript. This is NIO contribution no. xxx. Appendix A: Peak frequency method (Zhang and Ulrych, 2002) The propagating wavelet at the onset of source (t=0) can be approximated by a Ricker wavelet with dominant frequency fm as...

  10. Ocean Bottom Gamma-Ray Anomaly Around Methane Seeps Related to Gas Hydrate- Bearing Zone in The Eastern Margin of Japan Sea and Off Southwest Taiwan

    Science.gov (United States)

    Machiyama, H.; Kinoshita, M.; Lin, S.; Matsumoto, R.; Soh, W.

    2008-12-01

    JAMSTEC has conducted the ocean bottom gamma-ray measurement using ROVs and Submersibles since 1997. Gamma-ray spectrometer utilizes 3-inch spherical NaI(Tl) scintillator and the signal processor including DA converter in a pressure case. After processing data, we get total count rate (intensity value: count per second (cps)) of gamma ray and contents of K, U-, and Th-series radionuclides. The sensor was equipped to the side of the sample basket or foot of ROVs and submersibles, and always touches the seafloor when ROVs completely landed. Their results are posted on JAMSTEC website as a database. On the basis of past achievements, we present the results of the ocean bottom gamma-ray measurement at the methane seep sites related to gas hydrate off Joetsu in the eastern margin of Japan Sea and off southwest Taiwan. Off Joetsu: A number of mounds, large pockmarks (20 - 50 m deep and 200 - 500 m across), gas plumes, and gas hydrate are found at water depth of 900 - 1000 m in the Umitaka Spur and the Joetsu Knoll. Gamma-ray intensity values are 50 - 70 cps in normal muddy seafloor. On the other hand, the intensity values are 100 - 200 cps around methane venting sites, bacteria mats, and 'collapsed hydrate zone' which has an undulating, rugged seafloor with carbonate nodules and gravels. Contents of each radionuclide are also high. Low U/Th ratio suggests that there is less contribution of Rn accompanied with a recent fault activity. Off southwest Taiwan: Large, dense chemosynthetic communities, associated with carbonate pavements, were discovered at water depth of about 1100 - 1200 m on the top of the Formosa Ridge. Gamma-ray intensity values in normal muddy seafloor (120 - 150 cps) are higher than those around Japan. Since Th-series radionuclide easily absorbs other particles, it is commonly included in surface sediments. This may cause higher content of Th-series radionuclide in normal muddy seafloor. On the other hand, anomaly of gamma-ray intensity (200 - 300 cps) shows a methane seep activity from subsurface. It is hard to pinpoint the location and occurrence of seeps and fault without biotic activities. The ocean bottom gamma-ray measurement is one of the effective tools for the exploration of seeps and faults, though their values are different among areas and are not quantitative.

  11. Viscosity of the earth's core.

    Science.gov (United States)

    Gans, R. F.

    1972-01-01

    Calculation of the viscosity of the core at the boundary of the inner and outer core. It is assumed that this boundary is a melting transition and the viscosity limits of the Andrade (1934,1952) hypothesis (3.7 to 18.5 cp) are adopted. The corresponding kinematic viscosities are such that the precessional system explored by Malkus (1968) would be unstable. Whether it would be sufficiently unstable to overcome a severely subadiabatic temperature gradient cannot be determined.

  12. Nanoporous polymer liquid core waveguides

    DEFF Research Database (Denmark)

    Gopalakrishnan, Nimi; Christiansen, Mads Brøkner; Ndoni, Sokol

    2010-01-01

    We demonstrate liquid core waveguides defined by UV to enable selective water infiltration in nanoporous polymers, creating an effective refractive index shift Δn=0.13. The mode confinement and propagation loss in these waveguides are presented.......We demonstrate liquid core waveguides defined by UV to enable selective water infiltration in nanoporous polymers, creating an effective refractive index shift Δn=0.13. The mode confinement and propagation loss in these waveguides are presented....

  13. Core Collapse Supernova Models For Nucleosynthesis

    Science.gov (United States)

    Casanova, Jordi; Frohlich, C.; Perego, A.; Hempel, M.

    2014-01-01

    Type II supernova explosions are the product of the collapse of massive stars (M > 8-10 Msun), which explode with a kinetic energy release of 1e51 erg. While sophisticated multi-dimensional models can reveal details of the explosion mechanism (role of convection, fluid instabilities, etc.), they are computationally too expensive for nucleosynthesis studies. However, precise nucleosynthesis predictions are needed to understand the supernova contribution to the heavy elements and the abundances observed in metal-poor stars. We have modeled the core collapse, bounce and subsequent explosion of massive stars assuming spherical symmetry with the code Agile-IDSA (Liebendoerfer et al. 2009) combined with a novel method to artificially trigger the explosion (PUSH). The code also includes the Hempel EOS, which uses a modern non-NSE to cover the entire nucleosynthesis duration. In our simulations, based on the neutrino-delayed explosion mechanism, the explosion sets in by depositing a small amount of additional energy (from mu and tau neutrinos) to revive the stalled shock. Our results show that the code Agile-IDSA combined with PUSH is very robust and can successfully reproduce an explosion with a more reliable treatment of the crucial quantities involved in nucleosynthesis (i.e., the electron fraction). Here, we present a detailed isotopic abundance study for a wide variety of progenitors, as well as an analysis of the explosion properties, such as the explosion energies, remnant masses or compactness of the progenitor models.

  14. Holographic kinetic k-essence model

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, Norman [Departamento de Fisica, Facultad de Ciencia, Universidad de Santiago de Chile, Casilla 307, Santiago (Chile)], E-mail: ncruz@lauca.usach.cl; Gonzalez-Diaz, Pedro F.; Rozas-Fernandez, Alberto [Colina de los Chopos, Instituto de Fisica Fundamental, Consejo Superior de Investigaciones Cientificas, Serrano 121, 28006 Madrid (Spain)], E-mail: a.rozas@cfmac.csic.es; Sanchez, Guillermo [Departamento de Matematica y Ciencia de la Computacion, Facultad de Ciencia, Universidad de Santiago de Chile, Casilla 307, Santiago (Chile)], E-mail: gsanchez@usach.cl

    2009-08-31

    We consider a connection between the holographic dark energy density and the kinetic k-essence energy density in a flat FRW universe. With the choice c{>=}1, the holographic dark energy can be described by a kinetic k-essence scalar field in a certain way. In this Letter we show this kinetic k-essential description of the holographic dark energy with c{>=}1 and reconstruct the kinetic k-essence function F(X)

  15. Some Aspects of Extended Kinetic Equation

    Directory of Open Access Journals (Sweden)

    Dilip Kumar

    2015-09-01

    Full Text Available Motivated by the pathway model of Mathai introduced in 2005 [Linear Algebra and Its Applications, 396, 317–328] we extend the standard kinetic equations. Connection of the extended kinetic equation with fractional calculus operator is established. The solution of the general form of the fractional kinetic equation is obtained through Laplace transform. The results for the standard kinetic equation are obtained as the limiting case.

  16. Benefit of Hepatitis C Virus Core Antigen Assay in Prediction of Therapeutic Response to Interferon and Ribavirin Combination Therapy

    OpenAIRE

    Takahashi, Masahiko; Saito, Hidetsugu; Higashimoto, Makiko; Atsukawa, Kazuhiro; Ishii, Hiromasa

    2005-01-01

    A highly sensitive second-generation hepatitis C virus (HCV) core antigen assay has recently been developed. We compared viral disappearance and first-phase kinetics between commercially available core antigen (Ag) assays, Lumipulse Ortho HCV Ag (Lumipulse-Ag), and a quantitative HCV RNA PCR assay, Cobas Amplicor HCV Monitor test, version 2 (Amplicor M), to estimate the predictive benefit of a sustained viral response (SVR) and non-SVR in 44 genotype 1b patients treated with interferon (IFN) ...

  17. Kinetics of yttrium oxide carbochlorination

    Energy Technology Data Exchange (ETDEWEB)

    Gaviria, J.P., E-mail: gaviriaj@cab.cnea.gov.ar [Division Cinetica Quimica - Complejo Tecnologico Pilcaniyeu - Centro Atomico Bariloche - Comision Nacional de Energia Atomica, Av. Bustillo km 9500 (8400), S.C. de Bariloche, Rio Negro (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (Argentina); Fouga, G.G. [Division Cinetica Quimica - Complejo Tecnologico Pilcaniyeu - Centro Atomico Bariloche - Comision Nacional de Energia Atomica, Av. Bustillo km 9500 (8400), S.C. de Bariloche, Rio Negro (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (Argentina); Bohe, A.E. [Division Cinetica Quimica - Complejo Tecnologico Pilcaniyeu - Centro Atomico Bariloche - Comision Nacional de Energia Atomica, Av. Bustillo km 9500 (8400), S.C. de Bariloche, Rio Negro (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (Argentina); Centro Regional Universitario Bariloche - Universidad Nacional del Comahue (Argentina)

    2011-04-20

    Research highlights: {yields} Chlorination kinetics of Y{sub 2}O{sub 3}-C system was studied by thermogravimetry. {yields} The influence of carbon content, flow rate, sample mass and pCl{sub 2} were evaluated. {yields} Reaction proceeds through three successive stages until the formation of YCl{sub 3}(l). {yields}STAGE I is the formation of YOCl(s) and is under chemical control for T < 700 {sup o}C. {yields}STAGE I follows a nucleation and growth model. Kinetics parameters were obtained. - Abstract: The chlorination kinetics of the Y{sub 2}O{sub 3}-sucrose carbon system was studied by thermogravimetry. This work is a continuation of a previous one in which the reaction stages and the stoichiometry of each reaction have been determined. The influence of carbon content, total flow rate, sample initial mass and chlorine partial pressure was evaluated. The effect of carbon content on the reactive mixture was studied between 6.7 and 70% (carbon mass/total mass). The results showed that the reaction rate of each stage is strongly increased as the carbon content increases and the range of occurrence of the stages depends on the amount of carbon in the solid reactive mixture. The formation reaction of YOCl (STAGE I) is chemically controlled for temperatures lower than 700 {sup o}C with average effective activation energies of 165 {+-} 6 and 152 {+-} 7 kJ/mol for 8.7 and 16.7%C, respectively. The formation of the YOCl follows a nucleation and growth mechanism, with a combination of continuous nucleation and site saturation, and anisotropic growth controlled by diffusion. The kinetics of STAGE I can be expressed by the following global rate equation that includes the variables analyzed: (d{alpha})/(dt) =k{sub 0}Bexp(-(Ea)/(R{sub g}T) )pCl{sub 2}{l_brace}n(1-{alpha})[-ln(1-{alpha})]{r_brace}{sup (n-1)/n} where k{sub 0}B = 1.9 x 10{sup 4}, n = 1.20 for 8.7%C, and k{sub 0}B = 8.4 x 10{sup 3}, n = 1.14 for 16.7%C. STAGES II and III correspond to the YOCl carbochlorination to

  18. Kinetic modelling of enzymatic starch hydrolysis

    NARCIS (Netherlands)

    Bednarska, K.A.

    2015-01-01

    Kinetic modelling of enzymatic starch hydrolysis – a summary K.A. Bednarska The dissertation entitled ‘Kinetic modelling of enzymatic starch hydrolysis’ describes the enzymatic hydrolysis and kinetic modelling of liquefaction and saccharification of wheat starch. A

  19. Kinetic models of conjugated metabolic cycles

    Science.gov (United States)

    Ershov, Yu. A.

    2016-01-01

    A general method is developed for the quantitative kinetic analysis of conjugated metabolic cycles in the human organism. This method is used as a basis for constructing a kinetic graph and model of the conjugated citric acid and ureapoiesis cycles. The results from a kinetic analysis of the model for these cycles are given.

  20. Crystallization in Micellar Cores: confinement effects and dynamics

    Science.gov (United States)

    Lund, Reidar; Zinn, Thomas; Willner, Lutz; Department of Chemistry, University of Oslo Team; Forschungszentrum Jülich Collaboration

    It is well known that liquids confined to small nanoscopic pores and droplets exhibit thermal behavior very different from bulk samples. Here we demonstrate that n-alkanes forming 2-3 nm small micellar cores are considerably affected by confinement in analogue with hard confined systems. We study micelles form by self-assembly of a series of well-defined n-Alkyl-PEO polymers in aqueous solutions. By using small-angle X-ray scattering (SAXS), densiometry and differential scanning calorimetry (DSC), we show that n-alkane exhibit a first-order phase transition i.e. melting. Correlating the structural and thermodynamic data, we find that a melting depression can be accurately described by the Gibbs-Thomson equation. ∖f1 The effect of core crystallinity on the molecular exchange kinetics is investigated using time-resolved small-angle neutron scattering (TR-SANS). We show that there are considerable entropic and enthalpic contributions from the chain packing that affect the kinetic stability of micelles. ∖pard

  1. Role of the Hepatitis C Virus Core+1 Open Reading Frame and Core cis-Acting RNA Elements in Viral RNA Translation and Replication▿ †

    Science.gov (United States)

    Vassilaki, Niki; Friebe, Peter; Meuleman, Philipe; Kallis, Stephanie; Kaul, Artur; Paranhos-Baccalà, Glaucia; Leroux-Roels, Geert; Mavromara, Penelope; Bartenschlager, Ralf

    2008-01-01

    Four conserved RNA stem-loop structures designated SL47, SL87, SL248, and SL443 have been predicted in the hepatitis C virus (HCV) core encoding region. Moreover, alternative translation products have been detected from a reading frame overlapping the core gene (core+1/ARFP/F). To study the importance of the core+1 frame and core-RNA structures for HCV replication in cell culture and in vivo, a panel of core gene silent mutations predicted to abolish core+1 translation and affecting core-RNA stem-loops were introduced into infectious-HCV genomes of the isolate JFH1. A mutation disrupting translation of all known forms of core+1 and affecting SL248 did not alter virus production in Huh7 cells and in mice xenografted with human liver tissue. However, a combination of mutations affecting core+1 at multiple codons and at the same time, SL47, SL87, and SL248, delayed RNA replication kinetics and substantially reduced virus titers. The in vivo infectivity of this mutant was impaired, and in virus genomes recovered from inoculated mice, SL87 was restored by reversion and pseudoreversion. Mutations disrupting the integrity of this stem-loop, as well as that of SL47, were detrimental for virus viability, whereas mutations disrupting SL248 and SL443 had no effect. This phenotype was not due to impaired RNA stability but to reduced RNA translation. Thus, SL47 and SL87 are important RNA elements contributing to HCV genome translation and robust replication in cell culture and in vivo. PMID:18799568

  2. Crystallization in Earth's Core after High-Temperature Core Formation

    Science.gov (United States)

    Hirose, K.; Morard, G.; Hernlund, J. W.; Helffrich, G. R.; Ozawa, H.

    2015-12-01

    Recent core formation models based on the metal-silicate partitioning of siderophile elements suggest that the Earth's core was formed by metal segregation at high pressure and high temperature in a deep magma ocean. It is also thought that the simultaneous solubility of silicon and oxygen in liquid iron are strongly enhanced at high pressure and high temperature, such that at the end of accretion the core was rich in both silicon and oxygen. Here we performed crystallization experiments on the Fe-Si binary and Fe-Si-O ternary systems up to core pressure in a laser-heated diamond-anvil cell. The starting material for the latter was a homogeneous mixture of fine-grain Fe-Si and SiO2 (sustain without extreme degrees of secular cooling. However, even for modest degrees of joint Si-O incorporation into the early core, the buoyancy released by crystallization of SiO2 is sufficient to overcome thermal stratification and sustain the geodynamo.

  3. Variational Approach to Molecular Kinetics.

    Science.gov (United States)

    Nüske, Feliks; Keller, Bettina G; Pérez-Hernández, Guillermo; Mey, Antonia S J S; Noé, Frank

    2014-04-08

    The eigenvalues and eigenvectors of the molecular dynamics propagator (or transfer operator) contain the essential information about the molecular thermodynamics and kinetics. This includes the stationary distribution, the metastable states, and state-to-state transition rates. Here, we present a variational approach for computing these dominant eigenvalues and eigenvectors. This approach is analogous to the variational approach used for computing stationary states in quantum mechanics. A corresponding method of linear variation is formulated. It is shown that the matrices needed for the linear variation method are correlation matrices that can be estimated from simple MD simulations for a given basis set. The method proposed here is thus to first define a basis set able to capture the relevant conformational transitions, then compute the respective correlation matrices, and then to compute their dominant eigenvalues and eigenvectors, thus obtaining the key ingredients of the slow kinetics.

  4. Biochemical kinetics in changing volumes.

    Science.gov (United States)

    Pawłowski, Piotr H; Zielenkiewicz, Piotr

    2004-01-01

    The need of taking into account the change of compartment volume when developing chemical kinetics analysis inside the living cell is discussed. Literature models of a single enzymatic Michaelis-Menten process, glycolytic oscillations, and mitotic cyclin oscillations were tested with appropriate theoretical extension in the direction of volume modification allowance. Linear and exponential type of volume increase regimes were compared. Due to the above, in a growing cell damping of the amplitude, phase shift, and time pattern deformation of the metabolic rhythms considered were detected, depending on the volume change character. The performed computer simulations allow us to conclude that evolution of the cell volume can be an essential factor of the chemical kinetics in a growing cell. The phenomenon of additional metabolite oscillations caused by the periodic cell growth and division was theoretically predicted and mathematically described. Also, the hypothesis of the periodized state in the growing cell as the generalization of the steady-state was formulated.

  5. Kinetic activation-relaxation technique

    Science.gov (United States)

    Béland, Laurent Karim; Brommer, Peter; El-Mellouhi, Fedwa; Joly, Jean-François; Mousseau, Normand

    2011-10-01

    We present a detailed description of the kinetic activation-relaxation technique (k-ART), an off-lattice, self-learning kinetic Monte Carlo (KMC) algorithm with on-the-fly event search. Combining a topological classification for local environments and event generation with ART nouveau, an efficient unbiased sampling method for finding transition states, k-ART can be applied to complex materials with atoms in off-lattice positions or with elastic deformations that cannot be handled with standard KMC approaches. In addition to presenting the various elements of the algorithm, we demonstrate the general character of k-ART by applying the algorithm to three challenging systems: self-defect annihilation in c-Si (crystalline silicon), self-interstitial diffusion in Fe, and structural relaxation in a-Si (amorphous silicon).

  6. Art Engineering and Kinetic Art

    Directory of Open Access Journals (Sweden)

    Barış Yılmaz

    2014-12-01

    Full Text Available Performing an art, either by painting or by sculpturing, requires to be interdisciplinary. When an artist creates his/her work of art, the process he/she realizes is supported by different engineering disciplines. Therefore, especially modern artists need to understand engineering science and this results in transforming artists into engineers. Opportunities provided by technology and science enable artists to expand his/her vision and to improve his/her works. Especially kinetic art has become an approach that combines art with engineering. Kinetic art, which is nourished with varied disciplines, is an excellent example to prove that art is interdisciplinary and to show the relationship between artist/art and engineering.

  7. Kinetic mixing at strong coupling

    Science.gov (United States)

    Del Zotto, Michele; Heckman, Jonathan J.; Kumar, Piyush; Malekian, Arada; Wecht, Brian

    2017-01-01

    A common feature of many string-motivated particle physics models is additional strongly coupled U (1 )'s. In such sectors, electric and magnetic states have comparable mass, and integrating out modes also charged under U (1 ) hypercharge generically yields C P preserving electric kinetic mixing and C P violating magnetic kinetic mixing terms. Even though these extra sectors are strongly coupled, we show that in the limit where the extra sector has approximate N =2 supersymmetry, we can use formal methods from Seiberg-Witten theory to compute these couplings. We also calculate various quantities of phenomenological interest such as the cross section for scattering between visible sector states and heavy extra sector states as well as the effects of supersymmetry breaking induced from coupling to the minimal supersymmetric Standard Model.

  8. Kinetic Quantum Theory of Gravity

    CERN Document Server

    DeAquino, F

    2002-01-01

    Starting from the action function we have derived a theoretical background that leads to quantization of gravity and the deduction of a correlation between the gravitational and inertial masses, which depends on the kinetic momentum of the particle. We show that there is a reaffirmation of the strong equivalence principle and consequently the Einstein's equations are preserved. In fact such equations are deduced here directly from this kinetic approach to Gravity. Moreover, we have obtained a generalized equation for inertial forces, which incorporates the Mach's principle into Gravitation. Also, we have deduced the equation of Entropy; the Hamiltonian for a particle in an electromagnetic field and the reciprocal fine structure constant. It is possible to deduce the expression of the Casimir force and also to explain the Inflation Period and the Missing Matter without assuming the existence of vacuum fluctuations. This new approach for Gravity will allow us to understand some crucial matters in Cosmology.

  9. Kinetic Quantum Theory of Gravity

    CERN Document Server

    DeAquino, F

    2002-01-01

    Gravity is here quantized starting from the generalization of the action function. This leads to an equation of correlation between gravitational and inertial masses, which depends on the particle's kinetic energy. We show that there is a reaffirmation of the strong equivalence principle and consequently the Einstein's equations are preserved. In fact such equations are deduced here directly from this kinetic approach to Gravity. Moreover, we have obtained a generalized equation for inertial forces, which incorporates the Mach's principle into Gravitation. Also, we have deduced the equation of Entropy; the Hamiltonian for a particle in an electromagnetic field and the reciprocal fine structure constant. It is possible to deduce the expression of the Casimir force and also to explain the Inflation Period and the Missing Matter without assuming the existence of vacuum fluctuations. This new approach for Gravity will allow us to understand some crucial matters in Cosmology.

  10. Kinetic activation-relaxation technique.

    Science.gov (United States)

    Béland, Laurent Karim; Brommer, Peter; El-Mellouhi, Fedwa; Joly, Jean-François; Mousseau, Normand

    2011-10-01

    We present a detailed description of the kinetic activation-relaxation technique (k-ART), an off-lattice, self-learning kinetic Monte Carlo (KMC) algorithm with on-the-fly event search. Combining a topological classification for local environments and event generation with ART nouveau, an efficient unbiased sampling method for finding transition states, k-ART can be applied to complex materials with atoms in off-lattice positions or with elastic deformations that cannot be handled with standard KMC approaches. In addition to presenting the various elements of the algorithm, we demonstrate the general character of k-ART by applying the algorithm to three challenging systems: self-defect annihilation in c-Si (crystalline silicon), self-interstitial diffusion in Fe, and structural relaxation in a-Si (amorphous silicon).

  11. Kinetic ELISA in Microfluidic Channels

    Directory of Open Access Journals (Sweden)

    Debashis Dutta

    2011-06-01

    Full Text Available In this article, we describe the kinetic ELISA of Blue Tongue and Epizootic Hemorrhagic Disease viral antibodies in microfluidic channels by monitoring the rate of generation of the enzyme reaction product under static conditions. It has been shown that this format of the immunoassay allows very reliable quantitation of the target species using inexpensive glass microchips and a standard epifluorescence microscope system coupled to a CCD camera. For the viral antibodies assayed here, the limit of detection (LOD for the analyte concentration in our microchips was established to be 3–5 times lower than that obtained on commercial microwell plates using a fiftieth of the sample volume and less than a third of the incubation time. Our analyses further show that when compared to the end-point ELISA format, the kinetic mode of this assay yields an improvement in the LOD by over an order of magnitude in microfluidic devices. This benefit is primarily realized as the observed variation in the background fluorescence (signal at the start of the enzyme reaction period was significantly larger than that in the rate of signal generation upon repeating these assays in different microchannels/microchips. Because the kinetic ELISA results depend only on the latter quantity, the noise level in them was substantially lower compared to that in its end-point counterpart in which the absolute fluorescence measurements are of greater significance. While a similar benefit was also recorded through implementation of kinetic ELISAs on the microwell platform, the improvement in LOD registered in that system was not as significant as was observed in the case of microfluidic assays.

  12. Validation Results for Core-Scale Oil Shale Pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Staten, Josh; Tiwari, Pankaj

    2015-03-01

    This report summarizes a study of oil shale pyrolysis at various scales and the subsequent development a model for in situ production of oil from oil shale. Oil shale from the Mahogany zone of the Green River formation was used in all experiments. Pyrolysis experiments were conducted at four scales, powdered samples (100 mesh) and core samples of 0.75”, 1” and 2.5” diameters. The batch, semibatch and continuous flow pyrolysis experiments were designed to study the effect of temperature (300°C to 500°C), heating rate (1°C/min to 10°C/min), pressure (ambient and 500 psig) and size of the sample on product formation. Comprehensive analyses were performed on reactants and products - liquid, gas and spent shale. These experimental studies were designed to understand the relevant coupled phenomena (reaction kinetics, heat transfer, mass transfer, thermodynamics) at multiple scales. A model for oil shale pyrolysis was developed in the COMSOL multiphysics platform. A general kinetic model was integrated with important physical and chemical phenomena that occur during pyrolysis. The secondary reactions of coking and cracking in the product phase were addressed. The multiscale experimental data generated and the models developed provide an understanding of the simultaneous effects of chemical kinetics, and heat and mass transfer on oil quality and yield. The comprehensive data collected in this study will help advance the move to large-scale in situ oil production from the pyrolysis of oil shale.

  13. Aluminum corrosion product release kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, Matt, E-mail: Matthew.Edwards@cnl.ca; Semmler, Jaleh; Guzonas, Dave; Chen, Hui Qun; Toor, Arshad; Hoendermis, Seanna

    2015-07-15

    Highlights: • Release of Al corrosion product was measured in simulated post-LOCA sump solutions. • Increased boron was found to enhance Al release kinetics at similar pH. • Models of Al release as functions of time, temperature, and pH were developed. - Abstract: The kinetics of aluminum corrosion product release was examined in solutions representative of post-LOCA sump water for both pressurized water and pressurized heavy-water reactors. Coupons of AA 6061 T6 were exposed to solutions in the pH 7–11 range at 40, 60, 90 and 130 °C. Solution samples were analyzed by inductively coupled plasma atomic emission spectroscopy, and coupon samples were analyzed by secondary ion mass spectrometry. The results show a distinct “boron effect” on the release kinetics, expected to be caused by an increase in the solubility of the aluminum corrosion products. New models were developed to describe both sets of data as functions of temperature, time, and pH (where applicable)

  14. Hydration kinetics of transgenic soybeans

    Directory of Open Access Journals (Sweden)

    Aline Francielle Fracasso

    2015-01-01

    Full Text Available The kinetic and experimental analyses of the hydration process of transgenic soybeans (BRS 225 RR are provided. The importance of the hydration process consists of the grain texture modifications which favor grinding and extraction of soybeans. The soaking isotherms were obtained for four different temperatures. Results showed that temperature affected transgenic soybeans´ hydration rate and time. Moisture content d.b. of the soybeans increased from 0.12 ± 0.01 kg kg-1 to 1.45 ± 0.19 kg kg-1 during 270 min. of process. Two models were used to fit the kinetic curves: an empirical model developed by Peleg (1988 and a phenomenological one, proposed by Omoto et al. (2009. The two models adequately represented the hydration kinetics. Peleg model was applied to the experimental data and the corresponding parameters were obtained and correlated to temperature. The model by Omoto et al. (2009 showed a better statistical fitting. Although Ks was affected by temperature (Ks = 0.38079 exp (-2289.3 T-1, the equilibrium concentration remained practically unchanged.

  15. Fribrinolysis Kinetics and Its Application

    Institute of Scientific and Technical Information of China (English)

    WEI Wenning; YANG Rui; GUO Tao; YANG Yan; HU Yu

    2007-01-01

    A new, convenient, and rapid method for kinetic measurement of human fibrinolysis was established. The alteration of absorbance (A) in the process of blood coagulation and lyses was automatically scanned and recorded using a UV2000 spectrophotometer connected to a computer. The parameters of human fibrinolysis kinetics were established. Urokinase at 20 U/mL was the optimal concentration used. There was significant difference in fibrinolysis kinetics and plasma plasminogen concentration between 22 normal subjects and 27 patients with acute myeloblastic leukemia (P<0.05 and <0.01 respectively). The coefficience of variation was (5.24±1.51)%. This method could also be used to measure the plasma fibrinogen concentration at the same time. It was concluded that this method was stable and was capable of providing dynamic, direct experimental data and multiparemeters for clinicians. It was also valuable in evaluating the anti- and pro-fibrinolytic capcity of patients' plasmas, allowing for monitoring of therapy, choice of drugs and adjustment of drug concentrations.

  16. Classical kinetic energy, quantum fluctuation terms and kinetic-energy functionals

    OpenAIRE

    Hamilton, I. P.; Mosna, Ricardo A.; Site, L. Delle

    2006-01-01

    We employ a recently formulated dequantization procedure to obtain an exact expression for the kinetic energy which is applicable to all kinetic-energy functionals. We express the kinetic energy of an N-electron system as the sum of an N-electron classical kinetic energy and an N-electron purely quantum kinetic energy arising from the quantum fluctuations that turn the classical momentum into the quantum momentum. This leads to an interesting analogy with Nelson's stochastic approach to quant...

  17. Particle Filter-Based Recursive Data Fusion With Sensor Indexing for Large Core Neutron Flux Estimation

    Science.gov (United States)

    Tamboli, Prakash Kumar; Duttagupta, Siddhartha P.; Roy, Kallol

    2017-06-01

    We introduce a sequential importance sampling particle filter (PF)-based multisensor multivariate nonlinear estimator for estimating the in-core neutron flux distribution for pressurized heavy water reactor core. Many critical applications such as reactor protection and control rely upon neutron flux information, and thus their reliability is of utmost importance. The point kinetic model based on neutron transport conveniently explains the dynamics of nuclear reactor. The neutron flux in the large core loosely coupled reactor is sensed by multiple sensors measuring point fluxes located at various locations inside the reactor core. The flux values are coupled to each other through diffusion equation. The coupling facilitates redundancy in the information. It is shown that multiple independent data about the localized flux can be fused together to enhance the estimation accuracy to a great extent. We also propose the sensor anomaly handling feature in multisensor PF to maintain the estimation process even when the sensor is faulty or generates data anomaly.

  18. Core formation in silicate bodies

    Science.gov (United States)

    Nimmo, F.; O'Brien, D. P.; Kleine, T.

    2008-12-01

    Differentiation of a body into a metallic core and silicate mantle occurs most efficiently if temperatures are high enough to allow at least the metal to melt [1], and is enhanced if matrix deformation occurs [2]. Elevated temperatures may occur due to either decay of short-lived radio-isotopes, or gravitational energy release during accretion [3]. For bodies smaller than the Moon, core formation happens primarily due to radioactive decay. The Hf-W isotopic system may be used to date core formation; cores in some iron meteorites and the eucrite parent body (probably Vesta) formed within 1 My and 1-4~My of solar system formation, respectively [4]. These formation times are early enough to ensure widespread melting and differentiation by 26Al decay. Incorporation of Fe60 into the core, together with rapid early mantle solidification and cooling, may have driven early dynamo activity on some bodies [5]. Iron meteorites are typically depleted in sulphur relative to chondrites, for unknown reasons [6]. This depletion contrasts with the apparently higher sulphur contents of cores in larger planetary bodies, such as Mars [7], and also has a significant effect on the timing of core solidification. For bodies of Moon-size and larger, gravitational energy released during accretion is probably the primary cause of core formation [3]. The final stages of accretion involve large, stochastic collisions [8] between objects which are already differentiated. During each collision, the metallic cores of the colliding objects merge on timescales of a few hours [9]. Each collision will reset the Hf-W isotopic signature of both mantle and core, depending on the degree to which the impactor core re-equilibrates with the mantle of the target [10]. The re-equilibration efficiency depends mainly on the degree to which the impactor emulsifies [11], which is very uncertain. Results from N-body simulations [8,12] suggest that significant degrees of re- equilibration are required [4,10]. Re

  19. Viscosity of Earth's Outer Core

    CERN Document Server

    Smylie, D E

    2007-01-01

    A viscosity profile across the entire fluid outer core is found by interpolating between measured boundary values, using a differential form of the Arrhenius law governing pressure and temperature dependence. The discovery that both the retrograde and prograde free core nutations are in free decay (Palmer and Smylie, 2005) allows direct measures of viscosity at the top of the outer core, while the reduction in the rotational splitting of the two equatorial translational modes of the inner core allows it to be measured at the bottom. We find 2,371 plus/minus 1,530 Pa.s at the top and 1.247 plus/minus 0.035 x 10^11 Pa.s at the bottom. Following Brazhkin (1998) and Brazhkin and Lyapin (2000) who get 10^2 Pa.s at the top, 10^11 Pa.s at the bottom, by an Arrhenius extrapolation of laboratory experiments, we use a differential form of the Arrhenius law to interpolate along the melting temperature curve to find a viscosity profile across the outer core. We find the variation to be closely log-linear between the meas...

  20. The role of chlorine chemistry in Antarctic ozone loss - Implications of new kinetic data

    Science.gov (United States)

    Rodriguez, Jose M.; Ko, Malcolm K. W.; Sze, Nien Dak

    1990-01-01

    New kinetic data yielding a slower formation rate and larger absorption cross sections of Cl2O2 are incorporated into a photochemical model to reassess the role of chlorine chemistry in accounting for the ozone reductions derived from TOMS observations in different regions of the Antarctic polar vortex during 1987. The model is further constrained by existing measurements from the Airborne Antarctic Ozone Experiment and the National Ozone Expedition II. Calculated concentrations of ClO based on the new kinetic data increase by almost a factor of two between the collar and core regions of the vortex during the second half of September. The calculated ozone reductions in the vortex core appear to be consistent with the TOMS observations in spite of the slower rate for the self-reaction of ClO.

  1. Measuring the kinetic power of active galactic nuclei in the radio mode

    Science.gov (United States)

    Merloni, Andrea; Heinz, Sebastian

    2007-10-01

    We have studied the relationship among nuclear radio and X-ray power, Bondi rate and the kinetic luminosity of sub-Eddington active galactic nucleus (AGN) jets, as estimated from the pdV work done to inflate the cavities and bubbles observed in the hot X-ray-emitting atmospheres of their host galaxies and clusters. Besides the recently discovered correlation between jet kinetic and Bondi power, we show that a clear correlation exists also between Eddington-scaled kinetic power and bolometric luminosity, given by log(Lkin/LEdd) = (0.49 +/- 0.07) log(Lbol/LEdd) - (0.78 +/- 0.36). The measured slope suggests that these objects are in a radiatively inefficient accretion mode, and have been used to put stringent constraints on the properties of the accretion flow. Interestingly, we found no statistically significant correlations between Bondi power and bolometric AGN luminosity, apart from that induced by their common dependence on Lkin, thus confirming the idea that most of the accretion power emerges from these systems in kinetic form. We have then analysed the relation between kinetic power and radio core luminosity. Combining the measures of jet power with estimators of the unbeamed radio flux of the jet cores as, for example, the so-called Fundamental Plane of active black holes, we are able to determine, in a statistical sense, both the probability distribution of the mean jet Lorentz factor, which peaks at Γm ~ 7, and the intrinsic relationship between kinetic and radio core luminosity (and thus the jet radiative efficiency), which we estimate as logLkin = (0.81 +/- 0.11) logLR + 11.9+4.1-4.4, in good agreement with theoretical predictions of synchrotron jet models. With the aid of these findings, quantitative assessments of kinetic feedback from supermassive black holes in the radio mode (i.e. at low dimensionless accretion rates) will be possible based on accurate determinations of the central engine properties alone, such as mass, radio core and/or X

  2. SMART core protection system design

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J. K.; Park, H. Y.; Koo, I. S. [KAERI, Taejon (Korea, Republic of); Park, H. S.; Kim, J. S.; Son, C. H. [Samchang Enterprise Co., Ltd., Taejon (Korea, Republic of)

    2003-10-01

    SMART COre Protection System(SCOPS) is designed with real-tims Digital Signal Processor(DSP) board and Network Interface Card(NIC) board. SCOPS has a Control Rod POSition (CRPOS) software module while Core Protection Calculator System(CPCS) consists of Core Protection Calculators(CPCs) and Control Element Assembly(CEA) Calculators(CEACs) in the commercial nuclear plant. It's not necessary to have a independent cabinets for SCOPS because SCOPS is physically very small. Then SCOPS is designed to share the cabinets with Plant Protection System(PPS) of SMART. Therefor it's very easy to maintain the system because CRPOS module is used instead of the computer with operating system.

  3. Atmospheric Methane in Ice Cores

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The reconstruction of air trapped in ice cores provides us the most direct information about atmospheric CH4 variations in the past history. Ice core records from the "Three Poles (Antarctica, Greenland and Tibetan Plateau)" reveal the detailed fluctuations of atmospheric CH4 concentration with time and are allowed to quantify the CH4 differences among latitudes. These data are indispensably in the farther study of the relationship between greenhouse gases and climatic change, and of the past changes in terrestrial CH4 emissions. Ice cores reconstruction indicates that atmospheric CH4 concentration has increased quickly since industrialization, and the present day's level of atmospheric CH4 (1800 ppbv) is unprecedented during the past Glacial-Interglacial climate cycles.

  4. Distributed k-Core Decomposition

    CERN Document Server

    Montresor, Alberto; Miorandi, Daniele

    2011-01-01

    Among the novel metrics used to study the relative importance of nodes in complex networks, k-core decomposition has found a number of applications in areas as diverse as sociology, proteinomics, graph visualization, and distributed system analysis and design. This paper proposes new distributed algorithms for the computation of the k-core decomposition of a network, with the purpose of (i) enabling the run-time computation of k-cores in "live" distributed systems and (ii) allowing the decomposition, over a set of connected machines, of very large graphs, that cannot be hosted in a single machine. Lower bounds on the algorithms complexity are given, and an exhaustive experimental analysis on real-world graphs is provided.

  5. Mapping the prestellar core Ophiuchus D (L1696A) in ammonia

    CERN Document Server

    Ruoskanen, Jukka; Juvela, Mika; Miettinen, Oskari; Liljeström, Anne; Väisälä, Miikka; Lunttila, Tuomas; Kontinen, Samu

    2011-01-01

    The gas kinetic temperature in the centres of starless, high-density cores is predicted to fall as low as 5-6 K. The aim of this study was to determine the kinetic temperature distribution in the low-mass prestellar core Oph D where previous observations suggest a very low central temperature. The densest part of the Oph D core was mapped in the NH3(1,1) and (2,2) inversion lines using the Very Large Array (VLA). The physical quantities were derived from the observed spectra by fitting the hyperfine structure of the lines, and subsequently the temperature distribution of Oph D was calculated using the standard rotational temperature techniques. A physical model of the cores was constructed, and the simulated spectra after radiative transfer calculations with a 3D Monte Carlo code were compared with the observed spectra. Temperature, density, and ammonia abundance of the core model were tuned until a satisfactory match with the observation was obtained. The high resolution of the interferometric data reveals t...

  6. Transient and stability analysis of a BWR core with thorium-uranium fuel

    Energy Technology Data Exchange (ETDEWEB)

    Nunez-Carrera, Alejandro [Comision Nacional de Seguridad Nuclear y Salvaguardias, Dr. Barragan 779 Col. Narvarte, 03020 Mexico, DF (Mexico); Espinosa-Paredes, Gilberto [Division de Ciencias Basicas e Ingenieria, Universidad Autonoma Metropolitana, Av. San Rafael Atlixco 186, Col. Vicentina, 09340 Mexico, DF (Mexico)], E-mail: gepe@xanum.uam.mx; Francois, Juan-Luis [Departamento de Sistemas Energeticos, Facultad de Ingenieria, Universidad Nacional Autonoma de Mexico, Paseo Cuauhnahuac 8532, 62550 Jiutepec Mor. (Mexico)

    2008-08-15

    The kinetic response of a boiling water reactor (BWR) equilibrium core using thorium as a nuclear material, in an integrated blanket-seed assembly, is presented in this work. Additionally an in-house code was developed to evaluate this core under steady state and transient conditions including a stability analysis. The code has two modules: (a) the time domain module for transient analysis and (b) the frequency domain module for stability analysis. The thermal-hydraulic process is modeled by a set of five equations, considering no homogeneous flow with drift-flux approximation and non-equilibrium thermodynamic. The neutronic process is calculated with a point kinetics model. Typical BWR reactivity effects are considered: void fraction, fuel temperature, moderator temperature and control rod density. Collapsed parameters were included in the code to represent the core using an average fuel channel. For the stability analysis, in the frequency domain, the transfer function is determined by applying Laplace-transforming to the calculated pressure drop perturbations in each of the considered regions where a constant total pressure drop was considered. The transfer function was used to study the system response in the frequency domain when an inlet flow perturbation is applied. The results show that the neutronic behavior of the core with thorium uranium fuel is similar to a UO{sub 2} core, even during transient conditions. The stability and transient analysis show that the thorium-uranium fuel can be operated safely in current BWRs.

  7. Identifying ELIXIR Core Data Resources.

    Science.gov (United States)

    Durinx, Christine; McEntyre, Jo; Appel, Ron; Apweiler, Rolf; Barlow, Mary; Blomberg, Niklas; Cook, Chuck; Gasteiger, Elisabeth; Kim, Jee-Hyub; Lopez, Rodrigo; Redaschi, Nicole; Stockinger, Heinz; Teixeira, Daniel; Valencia, Alfonso

    2016-01-01

    The core mission of ELIXIR is to build a stable and sustainable infrastructure for biological information across Europe. At the heart of this are the data resources, tools and services that ELIXIR offers to the life-sciences community, providing stable and sustainable access to biological data. ELIXIR aims to ensure that these resources are available long-term and that the life-cycles of these resources are managed such that they support the scientific needs of the life-sciences, including biological research. ELIXIR Core Data Resources are defined as a set of European data resources that are of fundamental importance to the wider life-science community and the long-term preservation of biological data. They are complete collections of generic value to life-science, are considered an authority in their field with respect to one or more characteristics, and show high levels of scientific quality and service. Thus, ELIXIR Core Data Resources are of wide applicability and usage. This paper describes the structures, governance and processes that support the identification and evaluation of ELIXIR Core Data Resources. It identifies key indicators which reflect the essence of the definition of an ELIXIR Core Data Resource and support the promotion of excellence in resource development and operation. It describes the specific indicators in more detail and explains their application within ELIXIR's sustainability strategy and science policy actions, and in capacity building, life-cycle management and technical actions. The identification process is currently being implemented and tested for the first time. The findings and outcome will be evaluated by the ELIXIR Scientific Advisory Board in March 2017. Establishing the portfolio of ELIXIR Core Data Resources and ELIXIR Services is a key priority for ELIXIR and publicly marks the transition towards a cohesive infrastructure.

  8. Earth's core and the geodynamo

    Science.gov (United States)

    Buffett

    2000-06-16

    Earth's magnetic field is generated by fluid motion in the liquid iron core. Details of how this occurs are now emerging from numerical simulations that achieve a self-sustaining magnetic field. Early results predict a dominant dipole field outside the core, and some models even reproduce magnetic reversals. The simulations also show how different patterns of flow can produce similar external fields. Efforts to distinguish between the various possibilities appeal to observations of the time-dependent behavior of the field. Important constraints will come from geological records of the magnetic field in the past.

  9. Core competencies in internal medicine.

    Science.gov (United States)

    Porcel, José Manuel; Casademont, Jordi; Conthe, Pedro; Pinilla, Blanca; Pujol, Ramón; García-Alegría, Javier

    2012-06-01

    The working group on Competencies of Internal Medicine from the Spanish Society of Internal Medicine (SEMI) proposes a series of core competencies that we consider should be common to all European internal medicine specialists. The competencies include aspects related to patient care, clinical knowledge, technical skills, communication skills, professionalism, cost-awareness in medical care and academic activities. The proposal could be used as a working document for the Internal Medicine core curriculum in the context of the educational framework of medical specialties in Europe.

  10. Core Task and Organizational Reality

    DEFF Research Database (Denmark)

    Vikkelsø, Signe

    2015-01-01

    of core objects such as ‘task’ and ‘coordination,’ contemporary organization studies emphasize, much like other social science disciplines, broader topics such as ‘network,’ ‘identity,’ and ‘change.’ The paper argues that this altered focus and vocabulary is accompanied by a diminished ability to specify...... and intervene into the practical reality of organizations. It further argues that a discipline's core objects are not anachronisms to be discarded with, but crucial for specifying reality in ways that have proven practically relevant and still are....

  11. Improved neutron kinetics for coupled three-dimensional boiling water reactor analysis

    Science.gov (United States)

    Akdeniz, Bedirhan

    The need for a more accurate method of modelling cross section variations for off-nominal core conditions is becoming an important issue with the increased use of coupled three-dimensional (3-D) thermal-hydraulics/neutronics simulations. In traditional reactor core analysis, thermal reactor core calculations are customarily performed with 3-D two-group nodal diffusion methods. Steady-state multi-group transport theory calculations on heterogeneous single assembly domains subject to reflective boundary conditions are normally used to prepare the equivalent two-group spatially homogenized nodal parameters. For steady-state applications, the equivalent nodal parameters are theoretically well-defined; but, for transient applications, the definition of the nodal kinetics parameters, in particular, delayed neutron precursor data is somewhat unclear. The fact that delayed neutrons are emitted at considerably lower energies than prompt neutrons and that this difference cannot be accounted for in a two-group representation is of particular concern. To compensate for this inherent deficiency of the two-group model a correction is applied to the nodal values of the delayed neutron fractions; however, the adequacy of this correction has never been tested thoroughly for Boiling Water Reactor (BWR) applications, especially where the instantaneous thermal-hydraulic conditions play an important role on the core neutron kinetics calculations. This thesis proposes a systematic approach to improve the 3-D neutron kinetics modelling in coupled BWR transient calculations by developing, implementing and validating methods for consistent generation of neutron kinetics and delayed neutron data for such coupled thermal-hydraulics/neutronics simulations.

  12. A Streamlined Approach to Solving Simple and Complex Kinetic Systems Analytically

    Science.gov (United States)

    Andraos, John

    1999-11-01

    The use of Laplace transforms and integration techniques for the solution of simultaneous differential equations is demonstrated for obtaining the analytical solutions of simple and complex kinetic systems well known to students of the chemical sciences. These techniques learned in core first- and second-year mathematics courses provide a firm grounding in students' ability to understand the derivation of various rate expressions, and illustrate the value of cross-disciplinary approaches to education between the chemical and mathematical sciences.

  13. Hierarchical fractional-step approximations and parallel kinetic Monte Carlo algorithms

    OpenAIRE

    Arampatzis, Giorgos; Katsoulakis, Markos A.; Plechac, Petr; Taufer, Michela; Xu, Lifan

    2011-01-01

    We present a mathematical framework for constructing and analyzing parallel algorithms for lattice Kinetic Monte Carlo (KMC) simulations. The resulting algorithms have the capacity to simulate a wide range of spatio-temporal scales in spatially distributed, non-equilibrium physiochemical processes with complex chemistry and transport micro-mechanisms. The algorithms can be tailored to specific hierarchical parallel architectures such as multi-core processors or clusters of Graphical Processin...

  14. Producing gapped-ferrite transformer cores

    Science.gov (United States)

    Mclyman, W. T.

    1980-01-01

    Improved manufacturing techniques make reproducible gaps and minimize cracking. Molded, unfired transformer cores are cut with thin saw and then fired. Hardened semicircular core sections are bonded together, placed in aluminum core box, and fluidized-coated. After winding is run over box, core is potted. Economical method significantly reduces number of rejects.

  15. Multi-core Architectures and Streaming Applications

    NARCIS (Netherlands)

    Smit, Gerard J.M.; Kokkeler, André B.J.; Wolkotte, Pascal T.; Burgwal, van de Marcel D.; Mandoiu, I.; Kennings, A.

    2008-01-01

    In this paper we focus on algorithms and reconfigurable multi-core architectures for streaming digital signal processing (DSP) applications. The multi-core concept has a number of advantages: (1) depending on the requirements more or fewer cores can be switched on/off, (2) the multi-core structure f

  16. Core Stability Training for Injury Prevention

    OpenAIRE

    2013-01-01

    Context: Enhancing core stability through exercise is common to musculoskeletal injury prevention programs. Definitive evidence demonstrating an association between core instability and injury is lacking; however, multifaceted prevention programs including core stabilization exercises appear to be effective at reducing lower extremity injury rates. Evidence Acquisition: PubMed was searched for epidemiologic, biomechanic, and clinical studies of core stability for injury prevention (keywords: ...

  17. MCNP5 study on kinetics parameters of coupled fast-thermal system HERBE

    Directory of Open Access Journals (Sweden)

    Pešić Milan P.

    2011-01-01

    Full Text Available New validation of the well-known Monte Carlo code MCNP5 against measured criticality and kinetics data for the coupled fast-thermal HERBE System at the Reactor B critical assembly is shown in this paper. Results of earlier calculations of these criticality and kinetics parameters, done by combination of transport and diffusion codes using two-dimension geometry model are compared to results of new calculations carried out by the MCNP5 code in three-dimension geometry. Satisfactory agreements in comparison of new results with experimental data, in spite complex heterogeneous composition of the HERBE core, are achieved confirming that MCNP5 code could apply successfully to study on HERBE kinetics parameters after uncertainties in impurities in material compositions and positions of fuel elements in fast zone were removed.

  18. Kinetic modelling of the demineralization of shrimp exoskeleton using citric acid

    Directory of Open Access Journals (Sweden)

    Alewo Opuada AMEH

    2014-11-01

    Full Text Available Citric acid was used in the demineralization of shrimp exoskeleton and the kinetics of the demineralization process was studied. Kinetic data was obtained by demineralisation using five acid concentrations (0.1, 0.2, 0.3, 0.4 and 0.5M. The obtained kinetic data were fitted to the shrinking core model for fluid particle reactions. The concentration of calcium was found to decrease with time. For all acid concentrations considered, the best predictive mechanism for the demineralization process was determined to be Ash Layer Diffusion Control Mechanism. This was indicated by the high R2 values obtained (0.965 with 150% excess of citric acid.

  19. Pre-Steady-State Kinetic Analysis of Single-Nucleotide Incorporation by DNA Polymerases.

    Science.gov (United States)

    Su, Yan; Peter Guengerich, F

    2016-06-01

    Pre-steady-state kinetic analysis is a powerful and widely used method to obtain multiple kinetic parameters. This protocol provides a step-by-step procedure for pre-steady-state kinetic analysis of single-nucleotide incorporation by a DNA polymerase. It describes the experimental details of DNA substrate annealing, reaction mixture preparation, handling of the RQF-3 rapid quench-flow instrument, denaturing polyacrylamide DNA gel preparation, electrophoresis, quantitation, and data analysis. The core and unique part of this protocol is the rationale for preparation of the reaction mixture (the ratio of the polymerase to the DNA substrate) and methods for conducting pre-steady-state assays on an RQF-3 rapid quench-flow instrument, as well as data interpretation after analysis. In addition, the methods for the DNA substrate annealing and DNA polyacrylamide gel preparation, electrophoresis, quantitation and analysis are suitable for use in other studies. © 2016 by John Wiley & Sons, Inc.

  20. Visual Feedback for Rover-based Coring

    Science.gov (United States)

    Backes, Paul; Helmick, Daniel; Bajracharya, Max

    2008-01-01

    Technology for coring from a low-mass rover has been developed to enable core sample acquisition where a planetary rover experiences moderate slip during the coring operation. A new stereo vision technique, Absolute Motion Visual Odometry, is used to measure rover slip during coring and the slip is accommodated through corresponding arm pose updating. Coring rate is controlled by feedback of themeasured force of the coring tool against the environment. Test results in the JPL Marsyard show for the first time that coring from a low-mass rover with slip is feasible.

  1. Reaction networks and kinetics of biochemical systems.

    Science.gov (United States)

    Arceo, Carlene Perpetua P; Jose, Editha C; Lao, Angelyn R; Mendoza, Eduardo R

    2017-01-01

    This paper further develops the connection between Chemical Reaction Network Theory (CRNT) and Biochemical Systems Theory (BST) that we recently introduced [1]. We first use algebraic properties of kinetic sets to study the set of complex factorizable kinetics CFK(N) on a CRN, which shares many characteristics with its subset of mass action kinetics. In particular, we extend the Theorem of Feinberg-Horn [9] on the coincidence of the kinetic and stoichiometric subsets of a mass action system to CF kinetics, using the concept of span surjectivity. We also introduce the branching type of a network, which determines the availability of kinetics on it and allows us to characterize the networks for which all kinetics are complex factorizable: A "Kinetics Landscape" provides an overview of kinetics sets, their algebraic properties and containment relationships. We then apply our results and those (of other CRNT researchers) reviewed in [1] to fifteen BST models of complex biological systems and discover novel network and kinetic properties that so far have not been widely studied in CRNT. In our view, these findings show an important benefit of connecting CRNT and BST modeling efforts. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Oxidation kinetics of aluminum diboride

    Energy Technology Data Exchange (ETDEWEB)

    Whittaker, Michael L., E-mail: michaelwhittaker2016@u.northwestern.edu [Department of Materials Science and Engineering, University of Utah, 122S. Central Campus Drive, Salt Lake City, UT 84112 (United States); Sohn, H.Y. [Department of Metallurgical Engineering, University of Utah, 135S 1460 E, Rm 00412, Salt Lake City, UT 84112 (United States); Cutler, Raymond A. [Ceramatec, Inc., 2425S. 900W., Salt Lake City, UT 84119 (United States)

    2013-11-15

    The oxidation characteristics of aluminum diboride (AlB{sub 2}) and a physical mixture of its constituent elements (Al+2B) were studied in dry air and pure oxygen using thermal gravimetric analysis to obtain non-mechanistic kinetic parameters. Heating in air at a constant linear heating rate of 10 °C/min showed a marked difference between Al+2B and AlB{sub 2} in the onset of oxidation and final conversion fraction, with AlB{sub 2} beginning to oxidize at higher temperatures but reaching nearly complete conversion by 1500 °C. Kinetic parameters were obtained in both air and oxygen using a model-free isothermal method at temperatures between 500 and 1000 °C. Activation energies were found to decrease, in general, with increasing conversion for AlB{sub 2} and Al+2B in both air and oxygen. AlB{sub 2} exhibited O{sub 2}-pressure-independent oxidation behavior at low conversions, while the activation energies of Al+2B were higher in O{sub 2} than in air. Differences in the composition and morphology between oxidized Al+2B and AlB{sub 2} suggested that Al{sub 2}O{sub 3}–B{sub 2}O{sub 3} interactions slowed Al+2B oxidation by converting Al{sub 2}O{sub 3} on aluminum particles into a Al{sub 4}B{sub 2}O{sub 9} shell, while the same Al{sub 4}B{sub 2}O{sub 9} developed a needle-like morphology in AlB{sub 2} that reduced oxygen diffusion distances and increased conversion. The model-free kinetic analysis was critical for interpreting the complex, multistep oxidation behavior for which a single mechanism could not be assigned. At low temperatures, moisture increased the oxidation rate of Al+2B and AlB{sub 2}, but both appear to be resistant to oxidation in cool, dry environments. - Graphical abstract: Isothermal kinetic data for AlB{sub 2} in air, showing a constantly decreasing activation energy with increasing conversion. Model-free analysis allowed for the calculation of global kinetic parameters despite many simultaneous mechanisms occurring concurrently. (a) Time

  3. A Reacting-Shrinking Core Model for Pyrolysis and Combustion of a Single Biomass Particle

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, Alfredo L.; Avila, Claudio R.; Garcia, Ximena A. (Dept. of Chemical Engineering, Univ. of Concepcion (Chile)). e-mail: algordon@udec.cl

    2008-10-15

    Consecutive heating and pyrolysis of the solid due to incident heat flow represented by a shrinking reacting core approximation and combustion, described by a shrinking unreacting core description, allow modeling the combustion of a cylindrical biomass particle. A bi-dimensional approach (radial and axial) describes mass and heat balances and first order kinetics characterizes the reaction rates. A finite differences algorithm numerically solved the model. Results showed good agreement with available experimental data. The parameter analysis for the pyrolysis step shows high sensibility to the kinetic constants, the incident heat flow, the initial moisture and particle size. Parameters with a significant effect on combustion are the concentration and effective diffusivity of the oxidizing agent in the atmosphere around the reaction surface

  4. Kinetic Study on the Formation of Bimetallic Core-Shell Nanoparticles via Microemulsions

    Directory of Open Access Journals (Sweden)

    Concha Tojo

    2014-11-01

    Full Text Available Computer calculations were carried out to determine the reaction rates and the mean structure of bimetallic nanoparticles prepared via a microemulsion route. The rates of reaction of each metal were calculated for a particular microemulsion composition (fixed intermicellar exchange rate and varying reduction rate ratios between both metal and metal salt concentration inside the micelles. Model predictions show that, even in the case of a very small difference in reduction potential of both metals, the formation of an external shell in a bimetallic nanoparticle is possible if a large reactant concentration is used. The modification of metal arrangement with concentration was analyzed from a mechanistic point of view, and proved to be due to the different impact of confinement on each metal: the reaction rate of the faster metal is only controlled by the intermicellar exchange rate but the slower metal is also affected by a cage-like effect.

  5. Kinetic Study on the Formation of Bimetallic Core-Shell Nanoparticles via Microemulsions

    Science.gov (United States)

    Tojo, Concha; Vila-Romeu, Nuria

    2014-01-01

    Computer calculations were carried out to determine the reaction rates and the mean structure of bimetallic nanoparticles prepared via a microemulsion route. The rates of reaction of each metal were calculated for a particular microemulsion composition (fixed intermicellar exchange rate) and varying reduction rate ratios between both metal and metal salt concentration inside the micelles. Model predictions show that, even in the case of a very small difference in reduction potential of both metals, the formation of an external shell in a bimetallic nanoparticle is possible if a large reactant concentration is used. The modification of metal arrangement with concentration was analyzed from a mechanistic point of view, and proved to be due to the different impact of confinement on each metal: the reaction rate of the faster metal is only controlled by the intermicellar exchange rate but the slower metal is also affected by a cage-like effect. PMID:28788260

  6. Effect of Temperature and Sheet Temper on Isothermal Solidification Kinetics in Clad Aluminum Brazing Sheet

    Science.gov (United States)

    Benoit, Michael J.; Whitney, Mark A.; Wells, Mary A.; Winkler, Sooky

    2016-09-01

    Isothermal solidification (IS) is a phenomenon observed in clad aluminum brazing sheets, wherein the amount of liquid clad metal is reduced by penetration of the liquid clad into the core. The objective of the current investigation is to quantify the rate of IS through the use of a previously derived parameter, the Interface Rate Constant (IRC). The effect of peak temperature and initial sheet temper on IS kinetics were investigated. The results demonstrated that IS is due to the diffusion of silicon (Si) from the liquid clad layer into the solid core. Reduced amounts of liquid clad at long liquid duration times, a roughened sheet surface, and differences in resolidified clad layer morphology between sheet tempers were observed. Increased IS kinetics were predicted at higher temperatures by an IRC model as well as by experimentally determined IRC values; however, the magnitudes of these values are not in good agreement due to deficiencies in the model when applied to alloys. IS kinetics were found to be higher for sheets in the fully annealed condition when compared with work-hardened sheets, due to the influence of core grain boundaries providing high diffusivity pathways for Si diffusion, resulting in more rapid liquid clad penetration.

  7. Watching nanoparticle kinetics in liquid

    Directory of Open Access Journals (Sweden)

    Yugang Sun

    2012-04-01

    Full Text Available Real-time monitoring of reaction kinetics involved in nanoparticle growth and transformation in liquid environments is crucial for understanding the complex chemical and physical events associated with nanophase evolution. Accordingly, in situ techniques that can “see through” liquids to probe nanomaterial variation are in high demand, as they will help us understand reaction mechanisms and design better synthetic strategies for building nanoparticles with precisely tailored properties. In this review, in situ transmission x-ray microscopy and time-resolved high-energy x-ray scattering techniques are discussed, highlight their capabilities in studying the dynamic processes of nanoparticles.

  8. Collisions in Chiral Kinetic Theory

    CERN Document Server

    Chen, Jing-Yuan; Stephanov, Mikhail A

    2015-01-01

    Using a covariant formalism, we construct a chiral kinetic theory Lorentz invariant to order $\\mathcal O(\\hbar)$ which includes collisions. We find a new contribution to the particle number current due to the side jumps required by the conservation of angular momentum during collisions. We also find a conserved symmetric stress-energy tensor as well as the $H$-function obeying Boltzmann's $H$-theorem. We demonstrate their use by finding a general equilibrium solution and the values of the anomalous transport coefficients characterizing chiral vortical effect.

  9. Freezing Kinetics in Overcompressed Water

    Energy Technology Data Exchange (ETDEWEB)

    Bastea, M; Bastea, S; Reaugh, J; Reisman, D

    2006-09-27

    We report high pressure dynamic compression experiments of liquid water along a quasi-adiabatic path leading to the formation of ice VII. We observe dynamic features resembling Van der Waals loops and find that liquid water is compacted to a metastable state close to the ice density before the onset of crystallization. By analyzing the characteristic kinetic time scale involved we estimate the nucleation barrier and conclude that liquid water has been compressed to a high pressure state close to its thermodynamic stability limit.

  10. Kinetics of heterogeneous catalytic reactions

    CERN Document Server

    Boudart, Michel

    2014-01-01

    This book is a critical account of the principles of the kinetics of heterogeneous catalytic reactions in the light of recent developments in surface science and catalysis science. Originally published in 1984. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These paperback editions preserve the original texts of these important books while presenting them in durable paperback editions. The goal of the Princeton Legacy Library is to vastly increase acc

  11. Thermodynamic basis for cluster kinetics

    DEFF Research Database (Denmark)

    Hu, Lina; Bian, Xiufang; Qin, Xubo

    2006-01-01

    Due to the inaccessibility of the supercooled region of marginal metallic glasses (MMGs) within the experimental time window, we study the cluster kinetics above the liquidus temperature, Tl, to acquire information on the fragility of the MMG systems. Thermodynamic basis for the stability...... of locally ordered structure in the MMG liquids is discussed in terms of the two-order-parameter model. It is found that the Arrhenius activation energy of clusters, h, is proportional to the chemical mixing enthalpy of alloys, Hchem. Fragility of the MMG forming liquids can be described by the ratio...

  12. Core Competence Development : paradigm and practical implementations

    OpenAIRE

    Koay, Ze Wei; E.Markov, Denis

    2011-01-01

    The theory of core competence has drawn a large amount of attention in the academic field as well as of practitioners in the corporate world. Theory asserts that long-term value creation and competitiveness of the corporation relies on full-scale exploitation and timely development of company Core Competences; business strategies should be built around the core competencies of a firm. Identification and exploitation of Core Competences as well as essential elements comprising Core Competences...

  13. Fuzzy Cores and Fuzzy Balancedness

    NARCIS (Netherlands)

    van Gulick, G.; Norde, H.W.

    2011-01-01

    We study the relation between the fuzzy core and balancedness for fuzzy games. For regular games, this relation has been studied by Bondareva (1963) and Shapley (1967). First, we gain insight in this relation when we analyse situations where the fuzzy game is continuous. Our main result shows that a

  14. Competition for cores in remanufacturing

    NARCIS (Netherlands)

    Bulmus, Serra Caner; Zhu, Stuart X.; Teunter, Ruud

    2014-01-01

    We study competition between an original equipment manufacturer (OEM) and an independently operating remanufacturer (IO). Different from the existing literature, the OEM and IO compete not only for selling their products but also for collecting returned products (cores) through their acquisition pri

  15. One Health Core Competency Domains.

    Science.gov (United States)

    Frankson, Rebekah; Hueston, William; Christian, Kira; Olson, Debra; Lee, Mary; Valeri, Linda; Hyatt, Raymond; Annelli, Joseph; Rubin, Carol

    2016-01-01

    The emergence of complex global challenges at the convergence of human, animal, and environmental health has catalyzed a movement supporting "One Health" approaches. Despite recognition of the importance of One Health approaches to address these complex challenges, little effort has been directed at identifying the seminal knowledge, skills, and attitudes necessary for individuals to successfully contribute to One Health efforts. Between 2008 and 2011, three groups independently embarked on separate initiatives to identify core competencies for professionals involved with One Health approaches. Core competencies were considered critically important for guiding curriculum development and continuing professional education, as they describe the knowledge, skills, and attitudes required to be effective. A workshop was convened in 2012 to synthesize the various strands of work on One Health competencies. Despite having different mandates, participants, and approaches, all of these initiatives identified similar core competency domains: management; communication and informatics; values and ethics; leadership; teams and collaboration; roles and responsibilities; and systems thinking. These core competency domains have been used to develop new continuing professional education programs for One Health professionals and help university curricula prepare new graduates to be able to contribute more effectively to One Health approaches.

  16. Fuzzy Cores and Fuzzy Balancedness

    NARCIS (Netherlands)

    van Gulick, G.; Norde, H.W.

    2011-01-01

    We study the relation between the fuzzy core and balancedness for fuzzy games. For regular games, this relation has been studied by Bondareva (1963) and Shapley (1967). First, we gain insight in this relation when we analyse situations where the fuzzy game is continuous. Our main result shows that

  17. Common Core: Solve Math Problems

    Science.gov (United States)

    Strom, Erich

    2012-01-01

    The new common core standards for mathematics demand that students (and teachers!) exhibit deeper conceptual understanding. That's music to the ears of education professor John Tapper, who says teachers have overemphasized teaching procedures--and getting right answers. In his new book, "Solving for Why," he makes a powerful case for moving beyond…

  18. Reference: GT1CORE [PLACE

    Lifescience Database Archive (English)

    Full Text Available GT1CORE Green PJ, Yong M-H, Cuozzo M, Kano-Murakami Y, Silverstein P, Chua N-H Binding site require...ments for pea nuclear protein factor GT-1 correlate with sequences required for light-depend

  19. One Health Core Competency Domains

    Science.gov (United States)

    Frankson, Rebekah; Hueston, William; Christian, Kira; Olson, Debra; Lee, Mary; Valeri, Linda; Hyatt, Raymond; Annelli, Joseph; Rubin, Carol

    2016-01-01

    The emergence of complex global challenges at the convergence of human, animal, and environmental health has catalyzed a movement supporting “One Health” approaches. Despite recognition of the importance of One Health approaches to address these complex challenges, little effort has been directed at identifying the seminal knowledge, skills, and attitudes necessary for individuals to successfully contribute to One Health efforts. Between 2008 and 2011, three groups independently embarked on separate initiatives to identify core competencies for professionals involved with One Health approaches. Core competencies were considered critically important for guiding curriculum development and continuing professional education, as they describe the knowledge, skills, and attitudes required to be effective. A workshop was convened in 2012 to synthesize the various strands of work on One Health competencies. Despite having different mandates, participants, and approaches, all of these initiatives identified similar core competency domains: management; communication and informatics; values and ethics; leadership; teams and collaboration; roles and responsibilities; and systems thinking. These core competency domains have been used to develop new continuing professional education programs for One Health professionals and help university curricula prepare new graduates to be able to contribute more effectively to One Health approaches. PMID:27679794

  20. Stability of Molten Core Materials

    Energy Technology Data Exchange (ETDEWEB)

    Layne Pincock; Wendell Hintze

    2013-01-01

    The purpose of this report is to document a literature and data search for data and information pertaining to the stability of nuclear reactor molten core materials. This includes data and analysis from TMI-2 fuel and INL’s LOFT (Loss of Fluid Test) reactor project and other sources.

  1. One Health Core Competency Domains

    Directory of Open Access Journals (Sweden)

    Rebekah Frankson

    2016-09-01

    Full Text Available The emergence of complex global challenges at the convergence of human, animal, and environmental health has catalyzed a movement supporting ‘One Health’ approaches. Despite recognition of the importance of One Health approaches to address these complex challenges, little effort has been directed at identifying the seminal knowledge, skills and attitudes necessary for individuals to successfully contribute to One Health efforts. Between 2008 and 2011, three groups independently embarked on separate initiatives to identify core competencies for professionals involved with One Health approaches. Core competencies were considered critically important for guiding curriculum development and continuing professional education as they describe the knowledge, skills and attitudes required to be effective. A workshop was convened in 2012 to synthesize the various strands of work on One Health competencies. Despite having different mandates, participants, and approaches, all of these initiatives identified similar core competency domains: management; communication and informatics; values and ethics; leadership; teams and collaboration; roles and responsibilities; and systems thinking. These core competency domains have been used to develop new continuing professional education programs for One Health professionals and help university curricula prepare new graduates to be able to contribute more effectively to One Health approaches.

  2. Earth rotation and core topography

    Science.gov (United States)

    Hager, Bradford H.; Clayton, Robert W.; Spieth, Mary Ann

    1988-01-01

    The NASA Geodynamics program has as one of its missions highly accurate monitoring of polar motion, including changes in length of day (LOD). These observations place fundamental constraints on processes occurring in the atmosphere, in the mantle, and in the core of the planet. Short-timescale (t less than or approx 1 yr) variations in LOD are mainly the result of interaction between the atmosphere and the solid earth, while variations in LOD on decade timescales result from the exchange of angular momentum between the mantle and the fluid core. One mechanism for this exchange of angular momentum is through topographic coupling between pressure variations associated with flow in the core interacting with topography at the core-mantel boundary (CMB). Work done under another NASA grant addressing the origin of long-wavelength geoid anomalies as well as evidence from seismology, resulted in several models of CMB topography. The purpose of work supported by NAG5-819 was to study further the problem of CMB topography, using geodesy, fluid mechanics, geomagnetics, and seismology. This is a final report.

  3. CopperCore Service Integration

    Science.gov (United States)

    Vogten, Hubert; Martens, Harrie; Nadolski, Rob; Tattersall, Colin; van Rosmalen, Peter; Koper, Rob

    2007-01-01

    In an e-learning environment there is a need to integrate various e-learning services like assessment services, collaboration services, learning design services and communication services. In this article we present the design and implementation of a generic integrative service framework, called CopperCore Service Integration (CCSI). We will…

  4. Multifrequency studies of massive cores with complex spatial and kinematic structures

    Science.gov (United States)

    Pirogov, L. E.; Shul'ga, V. M.; Zinchenko, I. I.; Zemlyanukha, P. M.; Patoka, A. N.; Tomasson, M.

    2016-10-01

    Five regions of massive-star formation have been observed in various molecular lines in the frequency range˜85-89 GHz. The studied regions comprise dense cores, which host young stellar objects. The physical parameters of the cores are estimated, including the kinetic temperatures (˜20-40 K), the sizes of the emitting regions (˜0.1-0.6 pc), and the virial masses (˜40-500 M ⊙). The column densities and abundances of various molecules are calculated assuming Local Thermodynamical Equilibrium(LTE). The core in 99.982+4.17, which is associated with the weakest IRAS source, is characterized by reduced molecular abundances. The molecular line widths decrease with increasing distance from the core centers ( b). For b ≳ 0.1 pc, the dependences Δ V ( b) are close to power laws (∝ b - p ), where p varies from ~0.2 to ~0.5, depending on the object. In four cores, the asymmetries of the optically thick HCN(1-0) and HCO+(1-0) lines indicates systematicmotions along the line of sight: collapse in two cores and expansion in two others. Approximate estimates of the accretion rates in the collapsing cores indicate that the forming stars have masses exceeding the solar mass.

  5. Evaluation of Drug Release From Coated Pellets Based on Isomalt, Sugar, and Microcrystalline Cellulose Inert Cores

    OpenAIRE

    2010-01-01

    The objective of the present study was to investigate the effect of the pellet core materials isomalt, sugar, and microcrystalline cellulose on the in vitro drug release kinetics of coated sustained-release pellets as well as to evaluate the influence of different ratios of polymethacrylate copolymers exhibiting different permeability characteristics on the drug release rate. For characterization of the drug release process of pellets, the effect of osmolality was studied using glucose as an ...

  6. Kinetic Chain Rehabilitation: A Theoretical Framework

    Directory of Open Access Journals (Sweden)

    Aaron Sciascia

    2012-01-01

    Full Text Available Sequenced physiologic muscle activations in the upper and lower extremity result in an integrated biomechanical task. This sequencing is known as the kinetic chain, and, in upper extremity dominant tasks, the energy development and output follows a proximal to distal sequencing. Impairment of one or more kinetic chain links can create dysfunctional biomechanical output leading to pain and/or injury. When deficits exist in the preceding links, they can negatively affect the shoulder. Rehabilitation of shoulder injuries should involve evaluation for and restoration of all kinetic chain deficits that may hinder kinetic chain function. Rehabilitation programs focused on eliminating kinetic chain deficits, and soreness should follow a proximal to distal rationale where lower extremity impairments are addressed in addition to the upper extremity impairments. A logical progression focusing on flexibility, strength, proprioception, and endurance with kinetic chain influence is recommended.

  7. Kinetic chain rehabilitation: a theoretical framework.

    Science.gov (United States)

    Sciascia, Aaron; Cromwell, Robin

    2012-01-01

    Sequenced physiologic muscle activations in the upper and lower extremity result in an integrated biomechanical task. This sequencing is known as the kinetic chain, and, in upper extremity dominant tasks, the energy development and output follows a proximal to distal sequencing. Impairment of one or more kinetic chain links can create dysfunctional biomechanical output leading to pain and/or injury. When deficits exist in the preceding links, they can negatively affect the shoulder. Rehabilitation of shoulder injuries should involve evaluation for and restoration of all kinetic chain deficits that may hinder kinetic chain function. Rehabilitation programs focused on eliminating kinetic chain deficits, and soreness should follow a proximal to distal rationale where lower extremity impairments are addressed in addition to the upper extremity impairments. A logical progression focusing on flexibility, strength, proprioception, and endurance with kinetic chain influence is recommended.

  8. Mathematical Model for Growth of Inclusion in Deoxidization on the Basis of Unreacted Core Model

    Institute of Scientific and Technical Information of China (English)

    WU Su-zhou; ZHANG Jiong-ming

    2008-01-01

    Controlling inclusion composition,from the point of view of thermodynamics,only explains the probability and limit of reaction.However,kinetics makes the nucleation and the velocity of growth of inclusions clear,and these kinetic factors arc very important to the quality of slab.The basic kinetic theory of unreacted core model was used to build the mathematical model for the growth of inclusions and the concerned software was developed through Visual Basic 6.0.The time that different radius inclusions attain saturation was calculated to determine the controlling step of reaction between steel and inclusions.The time for the growth of inclusion obtained from the model was in good agreement with the data measured by Japanese Okuyama G,which indicated that the model is reasonable.

  9. Combustion kinetics and reaction pathways

    Energy Technology Data Exchange (ETDEWEB)

    Klemm, R.B.; Sutherland, J.W. [Brookhaven National Laboratory, Upton, NY (United States)

    1993-12-01

    This project is focused on the fundamental chemistry of combustion. The overall objectives are to determine rate constants for elementary reactions and to elucidate the pathways of multichannel reactions. A multitechnique approach that features three independent experiments provides unique capabilities in performing reliable kinetic measurements over an exceptionally wide range in temperature, 300 to 2500 K. Recent kinetic work has focused on experimental studies and theoretical calculations of the methane dissociation system (CH{sub 4} + Ar {yields} CH{sub 3} + H + Ar and H + CH{sub 4} {yields} CH{sub 3} + H{sub 2}). Additionally, a discharge flow-photoionization mass spectrometer (DF-PIMS) experiment is used to determine branching fractions for multichannel reactions and to measure ionization thresholds of free radicals. Thus, these photoionization experiments generate data that are relevant to both reaction pathways studies (reaction dynamics) and fundamental thermochemical research. Two distinct advantages of performing PIMS with high intensity, tunable vacuum ultraviolet light at the National Synchrotron Light Source are high detection sensitivity and exceptional selectivity in monitoring radical species.

  10. Interleaved Core Assignment for Bidirectional Transmission in Multi-Core Fibers

    DEFF Research Database (Denmark)

    Ye, Feihong; Morioka, Toshio

    2013-01-01

    We study interleaved core assignment for bidirectional transmission in multi-core fibers. By combining it with heterogeneous core structure in an 18-core fiber, the transmission distance is extended by 10 times compared to homogeneous core structure with unidirectional transmission, achieving...

  11. Interleaved Core Assignment for Bidirectional Transmission in Multi-Core Fibers

    OpenAIRE

    2013-01-01

    We study interleaved core assignment for bidirectional transmission in multi-core fibers. By combining it with heterogeneous core structure in an 18-core fiber, the transmission distance is extended by 10 times compared to homogeneous core structure with unidirectional transmission, achieving a total capacity of 1 Pb/s per direction.

  12. Interleaved Core Assignment for Bidirectional Transmission in Multi-Core Fibers

    DEFF Research Database (Denmark)

    Ye, Feihong; Morioka, Toshio

    2013-01-01

    We study interleaved core assignment for bidirectional transmission in multi-core fibers. By combining it with heterogeneous core structure in an 18-core fiber, the transmission distance is extended by 10 times compared to homogeneous core structure with unidirectional transmission, achieving a t...

  13. KINETICS STUDY ON NITRATION OF METHYL RICINOLEATE

    OpenAIRE

    Abdullah, Abdullah; Triyono, Triyono; Trisunaryanti, Wega; Haryadi, Winarto

    2012-01-01

    Kinetics parameter values of methyl ricinoleate nitration (rate constant, reaction order and the rate of reaction) have been determined. Nitration was carried out with both concentrations of HNO3 and acetic anhydride in excess to the concentration of methyl ricinoleate. Thus, the kinetics parameter value was only affected by the concentration of methyl ricinoleate. Based on kinetic study conducted, it could be concluded that the nitration follows pseudo first-order, and the reaction rate for ...

  14. Generalized Bloch-Wangsness-Redfield Kinetic Equations

    OpenAIRE

    Fatkullin, Nail

    2011-01-01

    We present a compact and general derivation of the generalized Bloch-Wangsness-Redfield kinetic equations for systems with the static spin Hamiltonian utilizing the concept of the Liouville space. We show that the assumptions of short correlation times and large heat capacity of the lattice are sufficient to derive the kinetic equations without the use of perturbation theory for the spin-lattice interaction operator. The perturbation theory is only applied for calculation of the kinetic coeff...

  15. Removal of Reactive Orange 16 Dye from Aqueous Solution by Using Modified Kenaf Core Fiber

    Directory of Open Access Journals (Sweden)

    Maytham Kadhim Obaid

    2016-01-01

    Full Text Available Evaluated removal of reactive orange 16 (RO16 dye from aqueous solution was studied in batch mode by using kenaf core fiber as low-cost adsorbents. In this attempt, kenaf core fiber with size 0.25–1 mm was treated by using (3-chloro-2-hydroxypropyl trimethylammonium chloride (CHMAC as quaternization agent. Then effective parameters include adsorbent dose, pH, and contact time and initial dye concentration on adsorption by modified kenaf core fiber was investigated. In addition, isotherms and kinetics adsorption studies were estimated for determination of the equilibrium adsorption capacity and reactions dynamics, respectively. Results showed that the best dose of MKCF was 0.1 g/100 mL, the maximum removal of RO16 was 97.25 at 30°C, pH = 6.5, and agitation speed was 150 rpm. The results also showed that the equilibrium data were represented by Freundlich isotherm with correlation coefficients R2=0.9924, and the kinetic study followed the pseudo-second-order kinetic model with correlation coefficients R2=0.9997 for Co=100 mg/L. Furthermore, the maximum adsorption capacity was 416.86 mg/g. Adsorption through kenaf was found to be very effective for the removal of the RO16 dye.

  16. Cores to the rescue: how old cores enable new science

    Science.gov (United States)

    Ito, E.; Noren, A. J.; Brady, K.

    2016-12-01

    The value of archiving scientific specimens and collections for the purpose of enabling further research using new analytical techniques, resolving conflicting results, or repurposing them for entirely new research, is often discussed in abstract terms. We all agree that samples with adequate metadata ought to be archived systematically for easy access, for a long time and stored under optimal conditions. And yet, as storage space fills, there is a temptation to cull the collection, or when a researcher retires, to discard the collection unless the researcher manages to make his or her own arrangement for the collection to be accessioned elsewhere. Nobody has done anything with these samples in over 20 years! Who would want them? It turns out that plenty of us do want them, if we know how to find them and if they have sufficient metadata to assess past work and suitability for new analyses. The LacCore collection holds over 33 km of core from >6700 sites in diverse geographic locations worldwide with samples collected as early as 1950s. From these materials, there are many examples to illustrate the scientific value of archiving geologic samples. One example that benefitted Ito personally were cores from Lakes Mirabad and Zeribar, Iran, acquired in 1963 by Herb Wright and his associates. Several doctoral and postdoctoral students generated and published paleoecological reconstructions based on cladocerans, diatoms, pollen or plant macrofossils, mostly between 1963 and 1967. The cores were resampled in 1990s by a student being jointly advised by Wright and Ito for oxygen isotope analysis of endogenic calcite. The results were profitably compared with pollen and the results published in 2001 and 2006. From 1979 until very recently, visiting Iran for fieldwork was not pallowed for US scientists. Other examples will be given to further illustrate the power of archived samples to advance science.

  17. Hydrologic characterization of four cores from the Geysers Coring Project

    Energy Technology Data Exchange (ETDEWEB)

    Persoff, Peter; Hulen, Jeffrey B.

    1996-01-24

    Results of hydrologic tests conducted on four representative core plugs from Geysers Coring Project drill hole SB-15-D have been related to detailed mineralogic and textural characterization of the plugs to yield new information about permeability, porosity, and capillary-pressure characteristics of the uppermost Geysers steam reservoir and its immediately overlying caprock. The core plugs are all fine- to medium-grained, Franciscan-assemblage (late Mesozoic) metagraywacke with sparse Franciscan metamorphic quartz-calcite veins and late Cenozoic, hydrothermal quartz-calcite-pyrite veins. The matrices of three plugs from the caprock are rich in metamorphic mixed-layer illite/smectite and disseminated hydrothermal pyrite; the reservoir plug instead contains abundant illite and only minor pyrite. The reservoir plug and one caprock plug are sparsely disrupted by latest-stage, unmineralized microfractures which both follow and crosscut veinlets but which could be artifacts. Porosities of the plugs, measured by Boyles-law gas expansion, range between 1.9 and 2.5%. Gas permeability and Klinkenberg slip factor were calculated from gas-pressure-pulse-decay measurements using a specially designed permeameter with small (2 mL) reservoirs. Matrix permeabilities in the range 10-21 m² ( = 1 nanodarcy) were measured for two plugs that included mineral-filled veins but no unfilled microfractures. Greater permeabilities were measured on plugs that contained microfractures; at 500 psi net confining pressure, an effective aperture of 1.6 µm was estimated for one plug. Capillary pressure curves were determined for three cores by measuring saturation as weight gain of plugs equilibrated with atmospheres in which the relative humidity was controlled by saturated brines.

  18. Drug-Target Kinetics in Drug Discovery.

    Science.gov (United States)

    Tonge, Peter J

    2017-07-14

    The development of therapies for the treatment of neurological cancer faces a number of major challenges including the synthesis of small molecule agents that can penetrate the blood-brain barrier (BBB). Given the likelihood that in many cases drug exposure will be lower in the CNS than in systemic circulation, it follows that strategies should be employed that can sustain target engagement at low drug concentration. Time dependent target occupancy is a function of both the drug and target concentration as well as the thermodynamic and kinetic parameters that describe the binding reaction coordinate, and sustained target occupancy can be achieved through structural modifications that increase target (re)binding and/or that decrease the rate of drug dissociation. The discovery and deployment of compounds with optimized kinetic effects requires information on the structure-kinetic relationships that modulate the kinetics of binding, and the molecular factors that control the translation of drug-target kinetics to time-dependent drug activity in the disease state. This Review first introduces the potential benefits of drug-target kinetics, such as the ability to delineate both thermodynamic and kinetic selectivity, and then describes factors, such as target vulnerability, that impact the utility of kinetic selectivity. The Review concludes with a description of a mechanistic PK/PD model that integrates drug-target kinetics into predictions of drug activity.

  19. Hydrologic characterization of four cores from the Geysers Coring Project

    Energy Technology Data Exchange (ETDEWEB)

    Persoff, P. [Lawrence Berkeley National Lab., CA (United States); Hulen, J.B. [Univ. of Utah, Salt Lake City, UT (United States). Earth Sciences and Resources Institute

    1996-01-01

    Results of hydrologic tests on 4 representative core plugs from Geysers Coring Project drill hole SB-15-D were related to mineralogy and texture. Permeability measurements were made on 3 plugs from caprock and one plug from the steam reservoir. Late-stage microfractures present in 2 of the plugs contributed to greater permeability, but the values for the 2 other plugs indicate a typical matrix permeability of 1 to 2 {times} 10{sup {minus}21}m{sup 2}. Klinkenberg slip factor b for these plugs is generally consistent with the inverse relation between slip factor and permeability observed by Jones (1972) for plugs of much more permeable material. The caprock and reservoir samples are nearly identical metagraywackes with slight mineralogical differences which appear to have little effect on hydrology. The late stage microfractures are suspected of being artifacts. The capillary pressure curves for 3 cores are fit by power-law relations which can be used to estimate relative permeability curves for the matrix rocks.

  20. Logging-while-coring method and apparatus

    Science.gov (United States)

    Goldberg, David S.; Myers, Gregory J.

    2007-11-13

    A method and apparatus for downhole coring while receiving logging-while-drilling tool data. The apparatus includes core collar and a retrievable core barrel. The retrievable core barrel receives core from a borehole which is sent to the surface for analysis via wireline and latching tool The core collar includes logging-while-drilling tools for the simultaneous measurement of formation properties during the core excavation process. Examples of logging-while-drilling tools include nuclear sensors, resistivity sensors, gamma ray sensors, and bit resistivity sensors. The disclosed method allows for precise core-log depth calibration and core orientation within a single borehole, and without at pipe trip, providing both time saving and unique scientific advantages.