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Sample records for subcritical gradient richardson

  1. Diffusible gradients are out - an interview with Lewis Wolpert. Interviewed by Richardson, Michael K.

    Science.gov (United States)

    Wolpert, Lewis

    2009-01-01

    In 1969, Lewis Wolpert published a paper outlining his new concepts of "pattern formation" and "positional information". He had already published research on the mechanics of cell membranes in amoebae, and a series of classic studies of sea urchin gastrulation with Trygve Gustavson. Wolpert had presented his 1969 paper a year earlier at a Woods Hole conference, where it received a very hostile reception: "I wasnt asked back to America for many years!". But with Francis Crick lining up in support of diffusible morphogen gradients, positional information eventually became established as a guiding principle for research into biological pattern formation. It is now clear that pattern formation is much more complex than could possibly have been imagined in 1969. But Wolpert still believes in positional information, and regards intercalation during regeneration as its best supporting evidence. However, he and others doubt that diffusible morphogen gradients are a plausible mechanism: "Diffusible gradients are too messy", he says. Since his retirement, Lewis Wolpert has remained active as a theoretical biologist and continues to publish in leading journals. He has also campaigned for a greater public understanding of the stigma of depression. He was interviewed at home in London on July 26th, 2007 by Michael Richardson.

  2. Studies on mixing of the waters of different salinity gradients using Richardsons number and the suspended sediment distribution in the Beypore Estuary, south west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    AnilKumar, N.; Sankaranarayanan, V.N.; Josanto, V.

    of Richardsons number (log R sub(L)) shows high variation at river mouth section of the estuary (section-1) and at about 10 km upstream (section-2) during the postmonsoon period. During the premonsoon period there was no noticeable variation in log R sub...

  3. Richardson, Prof. Owen Willians

    Indian Academy of Sciences (India)

    Richardson, Prof. Owen Willians Nobel Laureate (Physics) - 1928. Date of birth: 26 April 1879. Date of death: 15 February 1959. YouTube ... Posted on 21 December 2017. ASTROPHYSICS: An Observational View of the Universe. Math Art and Design: MAD about Math, Math Education and Outreach. Math and Finance ...

  4. Richardson WCAP 39

    African Journals Online (AJOL)

    user

    body weight at 90 d (Richardson, 1983). The post-weaning stocking rates were 0.22 and 0.43 animals/ha. The experiment was carried out on a large heterogeneous area of land that included rocky hillsides, flat land and fertile riverine areas, while the grass growth model was developed from experiments on a uniform area.

  5. Memoirs of Eileen Richardson

    Index Scriptorium Estoniae

    Richardson, Eileen

    2010-01-01

    Bournemouthi Ülikooli professor Eileen Richardson projektist ”Inequalities in access to rural communities”, mis on mõeldud Kanada ja Euroopa tervishoiuerialade tudengitele ning mille eesmärgiks on edendada erinevate tervishoiuerialade tudengite vahetust, rajada õpetlaste ja töötavate tervishoiuspetsialistide võrgustik arendamaks välja ühised õppekavad ja juhendid. Projektiga ühines ka Tallinna Tervishoiu Kõrgkool

  6. Fort Richardson moose tagging project

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Of the big game animals that inhabit the Fort Richardson-Elmendorf AFB military reservation, moose (Alces a1ces gigas) are the predominant species and may be found...

  7. Subcritical multiplication determination studies

    Energy Technology Data Exchange (ETDEWEB)

    Estes, G.P.; Goulding, C.A.

    1995-07-01

    A series of measurements and improvements to computational techniques are in progress at Los Alamos National Laboratory that are aimed at better understanding the determination of the reactivity of subcritical systems from measurements of the apparent multiplication of the system. Such studies are being performed in order to improve the special nuclear material (SNM) assays of unknown systems such as those encountered in SNM safeguards, arms-control verification, imports of foreign-generated SNM, etc. Improved techniques and understanding are needed since measured multiplication is not always an invariant characteristic of a subcritical system, especially if one has a system with no significant intrinsic internal neutron source that is illuminated nonuniformly with an external source (i.e., a non-normal mode system).

  8. Quantum Subcritical Bubbles

    Science.gov (United States)

    Uesugi, T.; Morikawa, M.; Shiromizu, T.

    1996-08-01

    We quantize subcritical bubbles which are formed in the weakly first order phase transition. We find that the typical size of the thermal fluctuation reduces in quantum-statistical physics. We estimate the typical size and the amplitude of thermal fluctuations near the critical temperature in the electroweak phase transition using a quantum statistical average. Furthermore, based on our study, we discuss implications for the dynamics of phase transitions.

  9. Subcritical nuclear assembly

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H. R., E-mail: fermineutron@yahoo.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)

    2014-08-15

    A Subcritical Nuclear Assembly is a device where the nuclear-fission chain reaction is initiated and maintained using an external neutron source. It is a valuable educational and research tool where in a safe way many reactor parameters can be measured. Here, we have used the Wigner-Seitz method in the six-factor formula to calculate the effective multiplication factor of a subcritical nuclear reactor Nuclear Chicago model 9000. This reactor has approximately 2500 kg of natural uranium heterogeneously distributed in slugs. The reactor uses a {sup 239}PuBe neutron source that is located in the center of an hexagonal array. Using Monte Carlo methods, with the MCNP5 code, a three-dimensional model of the subcritical reactor was designed to estimate the effective multiplication factor, the neutron spectra, the total and thermal neutron fluences along the radial and axial axis. With the neutron spectra in two locations outside the reactor the ambient dose equivalent were estimated. (Author)

  10. A Freudian Reading of Samuel Richardson's Pamela

    Directory of Open Access Journals (Sweden)

    Shadi Torabi Sarijaloo

    2016-03-01

    Full Text Available Richardson's Pamela (1740_1 is replete with elements and incidents that make it worthy enough to be viewed from Freud's perspective. The present study focuses upon how Richardson's characters unconsciously attempt to conceal and repress their own conflicting emotions, thoughts, wishes, impulses and how they struggle against their anxiety-ridden situations to regain their psychic balance. Moreover, the repetition of certain occurrences and elements play a crucial role in generating the uncanny effect in Pamela, including the role of double and déjà-vu, the castle-like settings, heroine's intimidating situations and also her master's past secret. In addition, the way Richardson's characters dress for the noteworthy masquerade ball scene and the ambiguous words of Pamela's master are considerably implies something that is affiliated with characters' psyche according to Freud's condensation theory. With regard to Freud's concepts of The 'Tripartite Psyche', 'Anxiety and Ego Defense Mechanisms' and 'Uncanny' the researcher attempts to delve into the heroine and her master's psyche through her letters which reveal the contents of the heroine's unconscious mind.

  11. Accelerator driven sub-critical core

    Science.gov (United States)

    McIntyre, Peter M; Sattarov, Akhdiyor

    2015-03-17

    Systems and methods for operating an accelerator driven sub-critical core. In one embodiment, a fission power generator includes a sub-critical core and a plurality of proton beam generators. Each of the proton beam generators is configured to concurrently provide a proton beam into a different area of the sub-critical core. Each proton beam scatters neutrons within the sub-critical core. The plurality of proton beam generators provides aggregate power to the sub-critical core, via the proton beams, to scatter neutrons sufficient to initiate fission in the sub-critical core.

  12. Marion Richardson: "Art and the Child," a Forgotten Classic

    Science.gov (United States)

    Armstrong, Michael

    2015-01-01

    Marion Richardson was a revolutionary art teacher and schools inspector. First published in 1948, her book "Art and the Child" is one of the most remarkable educational documents of the period between the first and second world wars. This article reviews Richardson's philosophy and practice of art and suggests its continuing…

  13. Black carp (Mylopharyngodon piceus, Richardson. Thematic bibliography

    Directory of Open Access Journals (Sweden)

    I. Hrytsynyak

    2017-03-01

    Full Text Available Purpose. Creating a thematic bibliographic list of publications in Ukrainian and Russian, dedicated to the ecology, biology, selection and cultivation of such Far East fish fauna species as black carp (Mylopharyngodon piceus Richardson in conditions of fish farms of Ukraine and neighboring countries, as well as the possibility of it introduction into water bodies for bioameliorative purpose. Methodology. The complete and selective methods were applied in the process of the systematic search. The bibliographic core has been formed with the literature from the fund of the scientific library of the Institute of Fisheries NAAS. Findings. There was composed a thematic list of publications with a total quantity of 67 sources, containing characteristics of black carp as representative of cyprinids, which is very important species from the point of view of aquaculture. This bibliography covers the time period from 1949 till 2011.The literary sources were arranged in alphabetical order by author or title, and described according to DSTU 7.1:2006 «System of standards on information, librarianship and publishing. Bibliographic entry. Bibliographic description. General requirements and rules», as well as in accordance with the requirements of APA style — international standard of references. Practical value. The list may be useful for scientists, practitioners, students, whose area of interests covers the questions of breeding and study of the biological features of black carp.

  14. Richardson Number, stability and turbulence- A coherent view

    Digital Repository Service at National Institute of Oceanography (India)

    Varkey, M.J.

    As turbulence in water is governed by vertical mobility controlled by static stability and horizontal mobility controlled by currents, the Richardson Number should give a measure of turbulence also. It is argued in this note that inverse...

  15. Richardson-Schottky transport mechanism in ZnS nanoparticles

    Directory of Open Access Journals (Sweden)

    Hassan Ali

    2016-05-01

    Full Text Available We report the synthesis and electrical transport mechanism in ZnS semiconductor nanoparticles. Temperature dependent direct current transport measurements on the compacts of ZnS have been performed to investigate the transport mechanism for temperature ranging from 300 K to 400 K. High frequency dielectric constant has been used to obtain the theoretical values of Richardson-Schottky and Poole-Frenkel barrier lowering coefficients. Experimental value of the barrier lowering coefficient has been calculated from conductance-voltage characteristics. The experimental value of barrier lowering coefficient βexp lies close to the theoretical value of Richardson-Schottky barrier lowering coefficient βth,RS showing Richardson-Schottky emission has been responsible for conduction in ZnS nanoparticles for the temperature range studied.

  16. Richardson-Schottky transport mechanism in ZnS nanoparticles

    Science.gov (United States)

    Ali, Hassan; Khan, Usman; Rafiq, M. A.; Falak, Attia; Narain, Adeela; Jing, Tang; Xu, Xiulai

    2016-05-01

    We report the synthesis and electrical transport mechanism in ZnS semiconductor nanoparticles. Temperature dependent direct current transport measurements on the compacts of ZnS have been performed to investigate the transport mechanism for temperature ranging from 300 K to 400 K. High frequency dielectric constant has been used to obtain the theoretical values of Richardson-Schottky and Poole-Frenkel barrier lowering coefficients. Experimental value of the barrier lowering coefficient has been calculated from conductance-voltage characteristics. The experimental value of barrier lowering coefficient βexp lies close to the theoretical value of Richardson-Schottky barrier lowering coefficient βth,RS showing Richardson-Schottky emission has been responsible for conduction in ZnS nanoparticles for the temperature range studied.

  17. Richardson's pair diffusion and the stagnation point structure of turbulence.

    Science.gov (United States)

    Dávila, J; Vassilicos, J C

    2003-10-03

    DNS and laboratory experiments show that the spatial distribution of straining stagnation points in homogeneous isotropic 3D turbulence has a fractal structure with dimension D(s)=2. In kinematic simulations the exponent gamma in Richardson's law and the fractal dimension D(s) are related by gamma=6/D(s). The Richardson constant is found to be an increasing function of the number density of straining stagnation points in agreement with pair diffusion occurring in bursts when pairs meet such points in the flow.

  18. Parametrization of the Richardson weather generator within the European Union

    NARCIS (Netherlands)

    Voet, van der P.; Kramer, K.; Diepen, van C.A.

    1996-01-01

    The Richardson model for mathematically generating daily weather data was parametrized. Thirty years' time-series of the 355 main meteorological stations in the European Union formed the database. Model parameters were derived from both observed weather station data and interpolated weather data on

  19. Subcritical flutter in the acoustics of friction

    National Research Council Canada - National Science Library

    O.N Kirillov

    2008-01-01

    ...-simple eigenfrequencies at the nodes. At contact with friction pads, the rotating continua, such as the singing wine glass or the squealing disc brake, start to vibrate owing to the subcritical flutter instability...

  20. The founder of Vicks: Lunsford Richardson (1854-1919).

    Science.gov (United States)

    Al Aboud, Khalid

    2010-01-01

    Vicks VapoRub (Procter & Gamble, Cincinnati, OH) is one of the most popular over-the-counter therapies in the world, used to provide relief from the symptoms of the common cold and non-life-threatening respiratory infections. Even as more advanced products have come and gone, VapoRub continues to dominate the market almost 9 decades after the death of its formulator, Lunsford Richardson (Figure).

  1. Generalization of Richardson-Gaudin models to rank-2 algebras

    Energy Technology Data Exchange (ETDEWEB)

    Errea, B; Lerma, S; Dukelsky, J; Dimitrova, S S; Pittel, S; Van Isacker, P; Gueorguiev, V G

    2006-07-20

    A generalization of Richardson-Gaudin models to the rank-2 SO(5) and SO(3,2) algebras is used to describe systems of two kinds of fermions or bosons interacting through a pairing force. They are applied to the proton-neutron neutron isovector pairing model and to the Interacting Boson Model 2, in the transition from vibration to gamma-soft nuclei, respectively. In both cases, the integrals of motion and their eigenvalues are obtained.

  2. The physics of accelerator driven sub-critical reactors

    Indian Academy of Sciences (India)

    Keywords. Accelerator driven systems; nuclear waste transmutation; computer codes; reactor physics; reactor noise; kinetics; burnup; transport theory; Monte Carlo; thorium utilization; neutron multiplication; sub-criticality; sub-critical facilities.

  3. Gravity-driven soap film dynamics in subcritical regimes

    Science.gov (United States)

    Auliel, M. I.; Castro, F.; Sosa, R.; Artana, G.

    2015-10-01

    We undertake the analysis of soap-film dynamics with the classical approach of asymptotic expansions. We focus our analysis in vertical soap film tunnels operating in subcritical regimes with elastic Mach numbers Me=O(10-1) . Considering the associated set of nondimensional numbers that characterize this flow, we show that the flow behaves as a two-dimensional (2D) divergence free flow with variable mass density. When the soap film dynamics agrees with that of a 2D and almost constant mass density flow, the regions where the second invariant of the velocity gradient is non-null correspond to regions where the rate of change of film thickness is non-negligible.

  4. Modeling of Parameters of Subcritical Assembly SAD

    CERN Document Server

    Petrochenkov, S; Puzynin, I

    2005-01-01

    The accepted conceptual design of the experimental Subcritical Assembly in Dubna (SAD) is based on the MOX core with a nominal unit capacity of 25 kW (thermal). This corresponds to the multiplication coefficient $k_{\\rm eff} =0.95$ and accelerator beam power 1 kW. A subcritical assembly driven with the existing 660 MeV proton accelerator at the Joint Institute for Nuclear Research has been modelled in order to make choice of the optimal parameters for the future experiments. The Monte Carlo method was used to simulate neutron spectra, energy deposition and doses calculations. Some of the calculation results are presented in the paper.

  5. Mechanisms of Subcritical Cracking in Calcite

    Science.gov (United States)

    Royne, A.; Dysthe, D. K.; Bisschop, J.

    2008-12-01

    Brittle materials are characterized by a critical stress intensity factor above which they will fail catastrophically by dynamic cracking. However, it has been observed that materials can also fail at much lower stresses, through slow crack growth, often referred to as subcritical cracking. This phenomenon can take place even in vacuum, but is greatly enhanced by water and other reactive species in the environment. For a given material and environmental condition there is a systematic relationship between the crack tip velocity and the stress intensity factor. The presence of a lower stress limit to subcritical cracking has been predicted from thermodynamics but has not been firmly demonstrated experimentally. This parameter would control the long- term strength of geological materials. Subcritical cracking must necessarily be important in controlling the rock strength in near-surface processes where water and other active species are present and the displacements and stresses are low. Weathering is one example of such a process. Modelling has shown that fracture networks generated by a high degree of subcritical cracking will percolate at much lower fracture densities than purely stochastical fracture networks. This has important implications for how water can move through the crust. Understanding the mechanisms for subcritical crack growth in geological materials is also important in assessing the stability and long term performance of sequestration reservoirs for CO2 or nuclear waste. The mechanism for stress corrosion is well known for glasses and quartz. For carbonate minerals, the mechanism for subcritical crack growth has not been identified, and the only experimental studies on calcitic materials have been on polycrystalline rocks such as marble. Suggested mechanisms include stress corrosion (weakening reactions at the crack tip), preferential dissolution at the crack tip with rapid removal of dissolved species, and environmentally controlled

  6. MCNP multiplication analysis of subcritical HEU experiments

    Energy Technology Data Exchange (ETDEWEB)

    Estes, G.P. [Los Alamos National Lab., NM (United States); Brockhoff, R.C. [Kansas State Univ., Manhattan, KS (United States)

    1998-12-31

    A series of measurements and improvements to computational techniques was described in Ref. 1 that were aimed at better understanding the determination of the reactivity of subcritical systems from measurements of the multiplying characteristics of the system. This methodology has been applied to a number of the bare highly enriched uranium (HEU) measurements (simulating 0.5- to 21.5-kg balls with nesting shells) of Ref. 2, demonstrating that the experimental multiplication results can be reproduced computationally with good accuracy. This capability promises to improve special nuclear material (SNM) assays of unknown systems such as those encountered in SNM safeguards, arms-control verification, imports of foreign-generated SNM, smuggling of SNM, etc. Improved techniques and understanding are needed since traditionally measured or calculated multiplications are not always an invariant characteristic of a subcritical system, especially if one has an SNM system with no significant intrinsic internal neutron source that is illuminated nonuniformly with an external source (i.e., a nonnormal mode system). The measurement techniques used in Refs. 1 and 2 to determine multiplication are based on the Feynman variance-to-mean method, which has been previously documented in Refs. 3 and 4 and applied successfully to normal mode systems such as plutonium and uranium spheres. These techniques have been applied to nonnormal mode problems with less success, and both Refs. 1 and 2 as well as the current paper are attempts to better understand the subcritical multiplication of such systems.

  7. Subcritical neutron production using multiple accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, W.Y.; Jones, J.L. [Idaho National Engineering Lab., Idaho Falls, ID (United States); Harmon, J.F. [Idaho State Univ., Pocatello, ID (United States)

    1994-12-31

    A subcritical neutron production technique using multiple accelerators is being developed to provide a selective alternative (for small volumes) to nuclear reactor neutron production. The concept combines the capabilities of multiple commercially-available linear accelerators and a compact subcritical assembly design to generate reactor-like thermal neutron fluxes (i.e., 10{sup 13}-10{sup 14} n/cm{sup 2}/s) in small irradiation volumes of up to 500 cm{sup 3}. In addition, fast and epithermal neutron fluxes will also be available. The neutron source utilizes radially-oriented, pulsed, electron accelerators. The subcritical neutron production assembly is in the form of a compact right-cylinder (approximately 20-cm dia.). This assembly uses an outer ring of graphite (i.e., reflector) with re-entrant holes to enable penetration of the electron beam to the internal structure which comprises of uranium as an electron convertor/neutron multiplier followed by H{sub 2}O beryllium, H{sub 2}O aluminum, and D{sub 2}O in succession toward the center. The inner-most region filled with D{sub 2}O is the central irradiation volume. The material configuration and overall design is to maximize thermal neutron fluxes in the central irradiation volume based on photoneutron/photofission and neutron multiplication processes as well as neutron transport. This assembly will be designed not to reach a nuclear critical state under any normal and/or accidental condition.

  8. Monte Carlo simulation of a perturbed subcritical core

    Energy Technology Data Exchange (ETDEWEB)

    Jaradat, Mustafa K.; Park, Chang Je [KAERI, Daejeon (Korea, Republic of)

    2012-10-15

    Jordan Subcritical Assembly (JSA) is designed for the purpose of education, training, and experiment research. Jordan subcritical assembly is considered Jordan's First Nuclear Facility Moving Jordan into the nuclear age. It is a teaching and training experimental facility that is designed to stay in a subcriticality A subcritical assembly is a multiplying system of nuclear fuel and moderator whose effective multiplication factor is less than unity. An extraneous source of neutron is required for the operation in order to compensate for the difference between the production rate of fission neutrons in the fuel and the rate of loss caused by absorption and leakage.

  9. Environmental contaminants in an osprey egg from the Upper Richardson Lake, Maine

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — On July 19, 2003 a non-viable, addled osprey (Pandion haliaetus) egg was collected from a nest at the northern end of Upper Richardson Lake in Richardsontown...

  10. Ring-Opening Reactions of the N-4-Nosyl Hough-Richardson Aziridine with Nitrogen Nucleophiles.

    Science.gov (United States)

    Ručil, Tomáš; Trávníček, Zdeněk; Cankař, Petr

    2017-01-06

    Dinosylated α-d-glucopyranoside was directly transformed into α-d-altropyranosides via in situ formed N-4-nosyl Hough-Richardson aziridine with nitrogen nucleophiles under mild conditions in fair to excellent yields. The scope of the aziridine ring-opening reaction was substantially broadened contrary to the conventional methods introducing solely the azide anion at high temperatures. If necessary, the N-4-nosyl Hough-Richardson aziridine can be isolated by filtration in a very good yield and high purity.

  11. QUANTITATIVE ANALYSIS FOR SHAPE IRREGULARITY OF CERAMIC PARTICLES BASED ON RICHARDSON EFFECT

    OpenAIRE

    Tatsuo, SAKAI; Masashi, FUJIKAWA; Suzie, LAURICH-McINTYRE; Richard C., BRADT; Department of Mechanica Engineering, Ritsumeikan University; Graduate School of Science and Engineering, Ritsumeikan University; Ceramic Tooling Division, PYRO MEDIA; Department of Metallurgical and Materials Engineering, University of Alabama

    1996-01-01

    Quanitative analysis for the shape irregularity of ceramic particles was performed by applying the concept of"Fractal"proposed by B. B. Mandelbrot. Two types of ceramic particles processed by different methods were employed as samples. Silhouette of each particle was repcatedly observed along 3-dimensional Cartesian axes, and then Richardson effect of the configuration of the respective silhouette was normalized by the perimeter. In this normalized Richardson effect, a characteristic aspect c...

  12. New Richardson's extrapolation spreadsheet calculator using VBA programming for numerical differentiations

    Science.gov (United States)

    Tay, Kim Gaik; Kek, Sie Long; Abdul-Kahar, Rosmila

    2015-05-01

    In this paper, we have further improved the limitations of our previous two Richardson's extrapolation spreadsheet calculators for computing differentiations numerically. The new feature in this new Richardson's extrapolation spreadsheet calculator is fully automated up to any level based on the stopping criteria using VBA programming. The new version is more flexible because it is controlled by programming. Furthermore, it reduces computational time and CPU memory.

  13. Glacial Geology and Stratigraphy of Fort Richardson, Alaska. A Review of Available Data on the Hydrogeology

    Science.gov (United States)

    2000-04-01

    Matanuska Valley. In Richardson and Glenn Highways, Alaska: Guidebook to Permafrost and Quaternary Geology (T.L. Péwé and R.D. Reger, Ed.). Fairbanks, Alaska...Matanuska Valley. In Glacial Geol- ogy and Geomorphology of North America: Quater- nary Geology and Permafrost Along the Richardson and Glenn Highways...Snowhawk Valley. gml Deposits of Glen Alps moraines (Pleis- tocene)—Probably well compacted and oxi- dized. Thickness poorly known, probably a few to

  14. Subcritical water extraction of lipids from wet algal biomass

    Science.gov (United States)

    Deng, Shuguang; Reddy, Harvind K.; Schaub, Tanner; Holguin, Francisco Omar

    2016-05-03

    Methods of lipid extraction from biomass, in particular wet algae, through conventionally heated subcritical water, and microwave-assisted subcritical water. In one embodiment, fatty acid methyl esters from solids in a polar phase are further extracted to increase biofuel production.

  15. Production of value added materials by subcritical water hydrolysis ...

    African Journals Online (AJOL)

    The aim of this study was the determination of the best experimental conditions for the production of useful materials such as amino acids by subcritical water hydrolysis from supercritical carbon dioxide extracted krill residues and to compare the results with raw krill. Subcritical water hydrolysis efficiency from raw and ...

  16. The physics of accelerator driven sub-critical reactors

    Indian Academy of Sciences (India)

    utilization; neutron multiplication; sub-criticality; sub-critical facilities. PACS Nos 89.30.Gg; 28.41.-I; 28.50.-k. 1. Introduction. Accelerator driven systems (ADS) are attracting worldwide attention increasingly due to their superior safety characteristics and their potential for burning actinide and fission product-waste and energy ...

  17. Subcritical water extraction of bioactive compounds from dry loquat ...

    African Journals Online (AJOL)

    ERASTO

    concentrated in a rotary evaporator at 60°C until dry. The total extraction yield was obtained by the mean value of the total extracts divided by the mass of dry loquat leaves used. Subcritical water extraction. Subcritical water extraction was carried using an extractor. (Hangzhou Huali Co. Ltd, Hangzhou, China). The extractor ...

  18. Dynamics of Subcritical Bubbles in First Order Phase Transition

    Science.gov (United States)

    Shiromizu, T.; Morikawa, M.; Yokoyama, J.

    1995-11-01

    We derivate the Langevin and the Fokker-Planck equations for the radius of O(3)-symmetric subcritical bubbles as a phenomenological model to treat thermal fluctuation. The effect of thermal noise on subcritical bubbles is examined. We find that the fluctuation-dissipation relation holds and that in the high temperature phase the system settles down rapidly to the thermal equilibrium state even if it was in a nonequilibrium state initially. We then estimate the typical size of subcritical bubbles as well as the amplitude of fluctuations on that scale. We also discuss their implication to the electroweak phase transition.

  19. Design, Development and Installation of Jordan Subcritical Assembly

    OpenAIRE

    Ned Xoubi

    2013-01-01

    Following its announcement in 2007 to pursue a nuclear power program and in the absence of any nuclear facility essential for the education, training, and research, Jordan decided to build a subcritical reactor as its first nuclear facility. Jordan Subcritical Assembly (JSA) is uranium fueled light water moderated and reflected subcritical reactor driven by a plutonium-beryllium source, and the core consists of 313 LEU fuel rods, loaded into a water-filled vessel in a square lattice of 19.11 ...

  20. Astrobionibbler: In Situ Microfluidic Subcritical Water Extraction of Amino Acids

    Science.gov (United States)

    Noell, A. C.; Fisher, A. M.; Takano, N.; Fors-Francis, K.; Sherrit, S.; Grunthaner, F.

    2016-10-01

    A fluidic-chip based instrument for subcritical water extraction (SCWE) of amino acids and other organics from powder samples has been developed. A variety of soil analog extractions have been performed to better understand SCWE capabilities.

  1. Prophet”or Professor? The Life and Work of Lewis Fry Richardson

    Science.gov (United States)

    Smagorinsky, Joseph

    This book focuses on a man who, in his lifetime, was scarcely known to the general public. Yet within certain circles, Richardson has had enormous impact within recent years. Although there are many scientists and humanists who exercise influence in their own respective fields, rarely do they bridge disciplines. It is this combination that has made Lewis Fry Richardson a figure worthy of a full-length biography, not just to record his contributions to each field but to provide an analysis and understanding of what motivated his diversity. In another age, Richardson would have been counted as a Renaissance man. He has variously been referred to as a chemist, physicist, mathematician, psychologist, meteorologist, economist, and biologist. In retrospect, he clearly was well ahead of his time, whether the subject in question was his work in numerical weather prediction or in war studies.

  2. Pulsed neutron source based on accelerator-subcritical-assembly

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Makoto; Noda, Akira; Iwashita, Yoshihisa; Okamoto, Hiromi; Shirai, Toshiyuki [Kyoto Univ., Uji (Japan). Inst. for Chemical Research

    1997-03-01

    A new pulsed neutron source which consists of a 300MeV proton linac and a nuclear fuel subcritical assembly is proposed. The proton linac produces pulsed spallation neutrons, which are multipied by the subcritical assembly. A prototype proton linac that accelerates protons up to 7MeV has been developed and a high energy section of a DAW structure is studied with a power model. Halo formations in high intensity beam are also being studied. (author)

  3. On Respiratory Rate of Cherry Tomatoes under Subcritical Heights

    Directory of Open Access Journals (Sweden)

    Fang Duan

    2013-01-01

    Full Text Available The influence of subcritical drop heights on respiratory rate was studied for cherry tomatoes. The cherry tomatoes were dropped, and the mean value of O2 concentration was measured, and then the respiration rate was calculated. The results showed that the respiration rate of the cherry tomatoes increases remarkably with the dropping height. Finally, the relationship between the subcritical dropping heights and respiration rate was modeled and validated, showing good agreement.

  4. On Respiratory Rate of Cherry Tomatoes under Subcritical Heights

    OpenAIRE

    Fang Duan; Yu-fen Chen; Zhong-zheng Sun; Ming-qing Chen; Hui Zhang; Jing Zhang

    2013-01-01

    The influence of subcritical drop heights on respiratory rate was studied for cherry tomatoes. The cherry tomatoes were dropped, and the mean value of O2 concentration was measured, and then the respiration rate was calculated. The results showed that the respiration rate of the cherry tomatoes increases remarkably with the dropping height. Finally, the relationship between the subcritical dropping heights and respiration rate was modeled and validated, showing good agreement.

  5. Neutrino Physics with Accelerator Driven Subcritical Reactors

    Science.gov (United States)

    Ciuffoli, Emilio

    2017-09-01

    Accelerator Driven Subcritical System (ADS) reactors are being developed around the world, to produce energy and, at the same time, to provide an efficient way to dispose of and to recycle nuclear waste. Used nuclear fuel, by itself, cannot sustain a chain reaction; however in ADS reactors the additional neutrons which are required will be supplied by a high-intensity accelerator. This accelerator will produce, as a by-product, a large quantity of {\\bar{ν }}μ via muon Decay At Rest (µDAR). Using liquid scintillators, it will be possible to to measure the CP-violating phase δCP and to look for experimental signs of the presence of sterile neutrinos in the appearance channel, testing the LSND and MiniBooNE anomalies. Even in the first stage of the project, when the beam energy will be lower, it will be possible to produce {\\bar{ν }}e via Isotope Decay At Rest (IsoDAR), which can be used to provide competitive bounds on sterile neutrinos in the disappearance channel. I will consider several experimental setups in which the antineutrinos are created using accelerators that will be constructed as part of the China-ADS program.

  6. Optimization Review, Optimization Review, Sidney and Richardson Hill Road Landfills, Delaware County, New York

    Science.gov (United States)

    The Sidney Landfill site is located on Richardson Hill Road approximately 10 miles southeast of Sidney, New York. In March 1989, the site was added to the National Priorities List (NPL) based on investigations completed by the New York State Department...

  7. Test Reliability and the Kuder-Richardson Formulas: Derivation from Probability Theory

    Science.gov (United States)

    Zimmerman, Donald W.

    1972-01-01

    Although a great deal of attention has been devoted over a period of years to the estimation of reliability from item statistics, there are still gaps in the mathematical derivation of the Kuder-Richardson results. The main purpose of this paper is to fill some of these gaps, using language consistent with modern probability theory. (Author)

  8. Virginia Tech Corps of Cadets alumnus Daniel Richardson named Central Michigan game Hokie Hero

    OpenAIRE

    Cox, Carrie

    2010-01-01

    Virginia Tech Corps of Cadets alumnus Capt. Daniel Richardson, U.S. Air Force, who earned a degree in industrial and systems engineering from the College of Engineering and a minor in leadership studies from the Virginia Tech Corps of Cadets Rice Center for Leader Development in 2004 has been selected as the Hokie Hero for the Virginia Tech versus Central Michigan University game.

  9. Ion-scale turbulence in MAST: anomalous transport, subcritical transitions, and comparison to BES measurements

    Science.gov (United States)

    van Wyk, F.; Highcock, E. G.; Field, A. R.; Roach, C. M.; Schekochihin, A. A.; Parra, F. I.; Dorland, W.

    2017-11-01

    We investigate the effect of varying the ion temperature gradient (ITG) and toroidal equilibrium scale sheared flow on ion-scale turbulence in the outer core of MAST by means of local gyrokinetic simulations. We show that nonlinear simulations reproduce the experimental ion heat flux and that the experimentally measured values of the ITG and the flow shear lie close to the turbulence threshold. We demonstrate that the system is subcritical in the presence of flow shear, i.e., the system is formally stable to small perturbations, but transitions to a turbulent state given a large enough initial perturbation. We propose that the transition to subcritical turbulence occurs via an intermediate state dominated by low number of coherent long-lived structures, close to threshold, which increase in number as the system is taken away from the threshold into the more strongly turbulent regime, until they fill the domain and a more conventional turbulence emerges. We show that the properties of turbulence are effectively functions of the distance to threshold, as quantified by the ion heat flux. We make quantitative comparisons of correlation lengths, times, and amplitudes between our simulations and experimental measurements using the MAST BES diagnostic. We find reasonable agreement of the correlation properties, most notably of the correlation time, for which significant discrepancies were found in previous numerical studies of MAST turbulence.

  10. Subcritical water as reaction environment: fundamentals of hydrothermal biomass transformation.

    Science.gov (United States)

    Möller, Maria; Nilges, Peter; Harnisch, Falk; Schröder, Uwe

    2011-05-23

    Subcritical water, that is, water above the boiling and below critical point, is a unique and sustainable reaction medium. Based on its solvent properties, in combination with the often considerable intrinsic water content of natural biomass, it is often considered as a potential solvent for biomass processing. Current knowledge on biomass transformation in subcritical water is, however, still rather scattered without providing a consistent picture. Concentrating on fundamental physical and chemical aspects, this review summarizes the current state of knowledge of hydrothermal biomass conversion in subcritical water. After briefly introducing subcritical water as a reaction medium, its advantages for biomass processing compared to other thermal processes are highlighted. Subsequently, the physical-chemical properties of subcritical water are discussed in the light of their impact on the occurring chemical reactions. The influence of major operational parameters, including temperature, pressure, and reactant concentration on hydrothermal biomass transformation processes are illustrated for selected carbohydrates. Major emphasis is put on the nature of the carbohydrate monomers, since the conversion of the respective polymers is analogous with the additional prior step of hydrolytic depolymerization. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Modeling of the CTEx subcritical unit using MCNPX code

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Avelino [Divisao de Defesa Quimica, Biologica e Nuclear. Centro Tecnologico do Exercito - CTEx, Guaratiba, Rio de Janeiro, RJ (Brazil); Silva, Ademir X. da, E-mail: ademir@con.ufrj.br [Programa de Engenharia Nuclear. Universidade Federal do Rio de Janeiro - UFRJ Centro de Tecnologia, Rio de Janeiro, RJ (Brazil); Rebello, Wilson F. [Secao de Engenharia Nuclear - SE/7 Instituto Militar de Engenharia - IME Rio de Janeiro, RJ (Brazil); Cunha, Victor L. Lassance [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2011-07-01

    The present work aims at simulating the subcritical unit of Army Technology Center (CTEx) namely ARGUS pile (subcritical uranium-graphite arrangement) by using the computational code MCNPX. Once such modeling is finished, it could be used in k-effective calculations for systems using natural uranium as fuel, for instance. ARGUS is a subcritical assembly which uses reactor-grade graphite as moderator of fission neutrons and metallic uranium fuel rods with aluminum cladding. The pile is driven by an Am-Be spontaneous neutron source. In order to achieve a higher value for k{sub eff}, a higher concentration of U235 can be proposed, provided it safely remains below one. (author)

  12. Subcritical Multiplication Parameters of the Accelerator-Driven System with 100 MeV Protons at the Kyoto University Critical Assembly

    OpenAIRE

    Jae-Yong Lim; Cheol Ho Pyeon; Takahiro Yagi; Tsuyoshi Misawa

    2012-01-01

    Basic experiments on the accelerator-driven system (ADS) at the Kyoto University Critical Assembly are carried out by combining a solid-moderated and -reflected core with the fixed-field alternating gradient accelerator. The reaction rates are measured by the foil activation method to obtain the subcritical multiplication parameters. The numerical calculations are conducted with the use of MCNPX and JENDL/HE-2007 to evaluate the reaction rates of activation foils set in the core region and at...

  13. Microwave ion source for accelerator driven sub-critical system

    CERN Document Server

    Cui Bao Qun; Jiang Wei; LiLiQiang; WangRongWen

    2002-01-01

    A microwave ion source is under developing for a demonstration prototype of a accelerator driven sub-critical system at CIAE (China Institute of Atomic Energy), 100 mA hydrogen beam has been extracted from the source through a 7.3 mm aperture in diameter, proton ratio is more than 85%, reliability has been tested for 100 h without any failures

  14. Experimental Study of Subcritical Water Liquefaction of Biomass

    DEFF Research Database (Denmark)

    Zhu, Zhe; Toor, Saqib; Rosendahl, Lasse

    2014-01-01

    In this work, hydrothermal liquefaction (HTL) of wood industry residues (wood, bark, sawdust) and macroalgae for producing biofuels has been investigated under subcritical water conditions (at temperature of 300 C), with and without the presence of catalyst. The effects of catalyst and biomass type...

  15. Local energy losses at positive and negative steps in subcritical ...

    African Journals Online (AJOL)

    Local energy losses occur when there is a transition in open channel flow. Even though local losses in subcritical open channel flow due to changes in channel width have been studied, to date no studies have been reported for losses due to changes in bed elevations. Steps are commonly used in engineering applications ...

  16. Monte Carlo Alpha Iteration Algorithm for a Subcritical System Analysis

    Directory of Open Access Journals (Sweden)

    Hyung Jin Shim

    2015-01-01

    Full Text Available The α-k iteration method which searches the fundamental mode alpha-eigenvalue via iterative updates of the fission source distribution has been successfully used for the Monte Carlo (MC alpha-static calculations of supercritical systems. However, the α-k iteration method for the deep subcritical system analysis suffers from a gigantic number of neutron generations or a huge neutron weight, which leads to an abnormal termination of the MC calculations. In order to stably estimate the prompt neutron decay constant (α of prompt subcritical systems regardless of subcriticality, we propose a new MC alpha-static calculation method named as the α iteration algorithm. The new method is derived by directly applying the power method for the α-mode eigenvalue equation and its calculation stability is achieved by controlling the number of time source neutrons which are generated in proportion to α divided by neutron speed in MC neutron transport simulations. The effectiveness of the α iteration algorithm is demonstrated for two-group homogeneous problems with varying the subcriticality by comparisons with analytic solutions. The applicability of the proposed method is evaluated for an experimental benchmark of the thorium-loaded accelerator-driven system.

  17. Local energy losses at positive and negative steps in subcritical ...

    African Journals Online (AJOL)

    2010-04-22

    7) 554-568. MORRIS HM and WIGGERT JM (1972) Applied Hydraulics in. Engineering. John Wiley & Sons, New York. ÖRSEL SI (2002) Local Losses at a Step in a Sub-critical Open. Channel Flow. M.Sc. Thesis, Department ...

  18. Extraction of antioxidants from Chlorella sp. using subcritical water treatment

    Science.gov (United States)

    Zakaria, S. M.; Mustapa Kamal, S. M.; Harun, M. R.; Omar, R.; Siajam, S. I.

    2017-06-01

    Chlorella sp. microalgae is one of the main source of natural bioactive compounds used in the food and pharmaceutical industries. Subcritical water extraction is the technique that offers an efficient, non-toxic, and environmental-friendly method to obtain natural ingredients. In this work, the extracts of Chlorella sp. microalgae was evaluated in terms of: chemical composition, extraction (polysaccharides) yield and antioxidant activity, using subcritical water extraction. Extractions were performed at temperatures ranging from 100°C to 300°C. The results show that by using subcritical water, the highest yield of polysaccharides is 23.6 that obtained at 150°C. Analysis on the polysaccharides yield show that the contents were highly influenced by the extraction temperature. The individual antioxidant activity were evaluated by in vitro assay using a free radical method. In general, the antioxidant activity of the extracts obtained at different water temperatures was high, with values of 31.08-54.29 . The results indicated that extraction by subcritical water was effective and Chlorella sp. can be a useful source of natural antioxidants.

  19. The imprint of the Hawking effect in subcritical flows

    CERN Document Server

    Coutant, Antonin

    2016-01-01

    We study the propagation of low frequency shallow water waves on a one dimensional flow of varying depth. When taking into account dispersive effects, the linear propagation of long wavelength modes on uneven bottoms excites new solutions of the dispersion relation which possess a much shorter wavelength. The peculiarity is that one of these new solutions has a negative energy. When the flow becomes supercritical, this mode has been shown to be responsible for the (classical) analog of the Hawking effect. For subcritical flows, the production of this mode has been observed numerically and experimentally, but the precise physics governing the scattering remained unclear. In this work, we provide an analytic treatment of this effect in subcritical flows. We analyze the scattering of low frequency waves using a new perturbative series, derived from a generalization of the Bremmer series. We show that the production of short wavelength modes is governed by a complex value of the position: a complex turning point....

  20. Analysis of reactivity determination methods in the subcritical experiment Yalina

    Science.gov (United States)

    Persson, Carl-Magnus; Seltborg, Per; Åhlander, Alexandra; Gudowski, Waclaw; Stummer, Thomas; Kiyavitskaya, Hanna; Bournos, Victor; Fokov, Yurij; Serafimovich, Ivan; Chigrinov, Sergey

    2005-12-01

    Different reactivity determination methods have been investigated, based on experiments performed at the subcritical assembly Yalina in Minsk, Belarus. The development of techniques for on-line monitoring of the reactivity level in a future accelerator-driven system (ADS) is of major importance for safe operation. Since an ADS is operating in a subcritical mode, the safety margin to criticality must be sufficiently large. The investigated methods are the Slope Fit Method, the Sjöstrand Method and the Source Jerk Method. The results are compared with Monte Carlo simulations performed with different nuclear data libraries. The results of the Slope Fit Method are in good agreement with the Monte Carlo simulation results, whereas the Sjöstrand Method appears to underestimate the criticality somewhat. The Source Jerk Method is subject to inadequate statistical accuracy.

  1. A microfluidic sub-critical water extraction instrument

    Science.gov (United States)

    Sherrit, Stewart; Noell, Aaron C.; Fisher, Anita; Lee, Mike C.; Takano, Nobuyuki; Bao, Xiaoqi; Kutzer, Thomas C.; Grunthaner, Frank

    2017-11-01

    This article discusses a microfluidic subcritical water extraction (SCWE) chip for autonomous extraction of amino acids from astrobiologically interesting samples. The microfluidic instrument is composed of three major components. These include a mixing chamber where the soil sample is mixed and agitated with the solvent (water), a subcritical water extraction chamber where the sample is sealed with a freeze valve at the chip inlet after a vapor bubble is injected into the inlet channels to ensure the pressure in the chip is in equilibrium with the vapor pressure and the slurry is then heated to ≤200 °C in the SCWE chamber, and a filter or settling chamber where the slurry is pumped to after extraction. The extraction yield of the microfluidic SCWE chip process ranged from 50% compared to acid hydrolysis and 80%-100% compared to a benchtop microwave SCWE for low biomass samples.

  2. A simple proof of exponential decay of subcritical contact processes

    Czech Academy of Sciences Publication Activity Database

    Swart, Jan M.

    2018-01-01

    Roč. 170, 1-2 (2018), s. 1-9 ISSN 0178-8051 R&D Projects: GA ČR(CZ) GA16-15238S Institutional support: RVO:67985556 Keywords : subcritical contact process * sharpness of the phase transition * eigenmeasure Subject RIV: BA - General Mathematics Impact factor: 1.895, year: 2016 http:// library .utia.cas.cz/separaty/2016/SI/swart-0462694.pdf

  3. 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.

  4. Design, Development and Installation of Jordan Subcritical Assembly

    Directory of Open Access Journals (Sweden)

    Ned Xoubi

    2013-01-01

    Full Text Available Following its announcement in 2007 to pursue a nuclear power program and in the absence of any nuclear facility essential for the education, training, and research, Jordan decided to build a subcritical reactor as its first nuclear facility. Jordan Subcritical Assembly (JSA is uranium fueled light water moderated and reflected subcritical reactor driven by a plutonium-beryllium source, and the core consists of 313 LEU fuel rods, loaded into a water-filled vessel in a square lattice of 19.11 mm pitch. The fuel rods are based on PWR fuel structural pattern type, made of uranium oxide (UO2 with 3.4 wt% 235U enrichment in zirconium alloy (Zr-4 cladding. Design, optimization, and verification were performed using MCNP5 nuclear code; the computed effective multiplication factor is 0.95923. The JSA is designed to fulfill the training needs of students and is equipped to perform all of the fundamental experiments required for a typical nuclear engineering university program. This paper presents the design, development, modeling, core analysis, and utilization of Jordan’s first nuclear facility and why this simplified low cost reactor presents an attractive choice to fulfill the preliminary experimental needs of nuclear engineering education in developing countries.

  5. The contributions of Lewis Fry Richardson to drainage theory, soil physics, and the soil-plant-atmosphere continuum

    Science.gov (United States)

    Knight, John; Raats, Peter

    2016-04-01

    The EGU Division on Nonlinear Processes in Geophysics awards the Lewis Fry Richardson Medal. Richardson's significance is highlighted in http://www.egu.eu/awards-medals/portrait-lewis-fry-richardson/, but his contributions to soil physics and to numerical solutions of heat and diffusion equations are not mentioned. We would like to draw attention to those little known contributions. Lewis Fry Richardson (1881-1953) made important contributions to many fields including numerical weather prediction, finite difference solutions of partial differential equations, turbulent flow and diffusion, fractals, quantitative psychology and studies of conflict. He invented numerical weather prediction during World War I, although his methods were not successfully applied until 1950, after the invention of fast digital computers. In 1922 he published the book `Numerical weather prediction', of which few copies were sold and even fewer were read until the 1950s. To model heat and mass transfer in the atmosphere, he did much original work on turbulent flow and defined what is now known as the Richardson number. His technique for improving the convergence of a finite difference calculation is known as Richardson extrapolation, and was used by John Philip in his 1957 semi-analytical solution of the Richards equation for water movement in unsaturated soil. Richardson's first papers in 1908 concerned the numerical solution of the free surface problem of unconfined flow of water in saturated soil, arising in the design of drain spacing in peat. Later, for the lower boundary of his atmospheric model he needed to understand the movement of heat, liquid water and water vapor in what is now called the vadose zone and the soil plant atmosphere system, and to model coupled transfer of heat and flow of water in unsaturated soil. Finding little previous work, he formulated partial differential equations for transient, vertical flow of liquid water and for transfer of heat and water vapor. He

  6. High-Resolution Profiling of Richardson Number Across the Surface Boundary Layer Using Heated Fiber Optics

    Science.gov (United States)

    Sayde, C.; Higgins, C. W.; Perdosa, R.; Mahaffee, W.; Selker, J. S.

    2016-12-01

    Most critical atmospheric processes are a balance between buoyancy and shear, typically measured with the Richardson number. The fine scale motions associated with critical or near critical valued of Richardson number are understudied because the location and timing of these events are not known a-priori. To study these motions and quantify their importance for transport of heat momentum and water vapor in the atmospheric boundary layer, a distributed measurement approach for temperature and wind speed is required. Here we present the results of 12.5 cm resolution distributed profiling of wind speed and temperature for the first 37 m of the surface boundary layer. Distributed Temperature Sensing (DTS) technology was employed to measure temperature every 5 s and 12.5 cm along two Fiber Optics (FO) cables suspended from 37 m elevation to ground by a blimp anchored above a vineyard in the Willamette Valley, Oregon. 3D printed FO holders installed every 3 m along the suspended FO cables insured constant spacing of 7.5 cm between the two cables. The first FO cable was 0.9mm in diameter and reported ambient air temperature. The second FO cable was embedded in a thin stainless steel tube (1.3 mm OD) continuously heated by an electrical current to provide continuous wind speed measurements every 12.5 cm along the heated cable. Analogous to a hot-wire anemometer, this approach is based on the principal of velocity-dependent heat transfer from a heated surface. The co-located wind speed and ambient temperature measurements are used to calculate Richardson number with a spatial and temporal resolution of 12.5 cm and 5 s respectively for the first 37 m of the surface boundary layer. The equipment employed, including the heating system, which is available to all US scientists, was provided by CTEMPs.org thanks to the generous grant support from the National Science Foundation under Grant Number EAR 0930061. Any opinions, findings, and conclusions or recommendations expressed in

  7. Subcritical Multiplication Parameters of the Accelerator-Driven System with 100 MeV Protons at the Kyoto University Critical Assembly

    Directory of Open Access Journals (Sweden)

    Jae-Yong Lim

    2012-01-01

    Full Text Available Basic experiments on the accelerator-driven system (ADS at the Kyoto University Critical Assembly are carried out by combining a solid-moderated and -reflected core with the fixed-field alternating gradient accelerator. The reaction rates are measured by the foil activation method to obtain the subcritical multiplication parameters. The numerical calculations are conducted with the use of MCNPX and JENDL/HE-2007 to evaluate the reaction rates of activation foils set in the core region and at the location of the target. Here, a comparison between the measured and calculated eigenvalues reveals a relative difference of around 10% in C/E values. A special mention is made of the fact that the reaction rate analyses in the subcritical systems demonstrate apparently the actual effect of moving the tungsten target into the core on neutron multiplication. A series of further ADS experiments with 100 MeV protons needs to be carried out to evaluate the accuracy of subcritical multiplication parameters.

  8. Vector Extrapolation-Based Acceleration of Regularized Richardson Lucy Image Deblurring

    Science.gov (United States)

    Remmele, Steffen; Hesser, Jürgen

    Confocal fluorescence microscopy has become an important tool in biological and medical sciences for imaging thin specimen, even living ones. Due to out-of-focus blurring and noise the acquired images are degraded and thus it is necessary to restore them. One of the most popular methods is an iterative Richardson-Lucy algorithm with total variation regularization. This algorithm while improving the image quality is converging slowly whereas with a constantly increasing amount of image data fast methods are required. In this paper, we present an accelerated version of the algorithm and investigate the achieved speed up. The acceleration method is based on a vector extrapolation technique and avoids a computational intensive evaluation of the underlying cost function. To evaluate the acceleration two synthetic test images are used. The accelerated algorithm reaches an acceptable result within 30% to 40% less computational time.

  9. Optimal 2D-SIM reconstruction by two filtering steps with Richardson-Lucy deconvolution

    Science.gov (United States)

    Perez, Victor; Chang, Bo-Jui; Stelzer, Ernst Hans Karl

    2016-11-01

    Structured illumination microscopy relies on reconstruction algorithms to yield super-resolution images. Artifacts can arise in the reconstruction and affect the image quality. Current reconstruction methods involve a parametrized apodization function and a Wiener filter. Empirically tuning the parameters in these functions can minimize artifacts, but such an approach is subjective and produces volatile results. We present a robust and objective method that yields optimal results by two straightforward filtering steps with Richardson-Lucy-based deconvolutions. We provide a resource to identify artifacts in 2D-SIM images by analyzing two main reasons for artifacts, out-of-focus background and a fluctuating reconstruction spectrum. We show how the filtering steps improve images of test specimens, microtubules, yeast and mammalian cells.

  10. EGS Richardson AGU Chapman NVAG3 Conference: Nonlinear Variability in Geophysics: scaling and multifractal processes

    Directory of Open Access Journals (Sweden)

    D. Schertzer

    1994-01-01

    Full Text Available 1. The conference The third conference on "Nonlinear VAriability in Geophysics: scaling and multifractal processes" (NVAG 3 was held in Cargese, Corsica, Sept. 10-17, 1993. NVAG3 was joint American Geophysical Union Chapman and European Geophysical Society Richardson Memorial conference, the first specialist conference jointly sponsored by the two organizations. It followed NVAG1 (Montreal, Aug. 1986, NVAG2 (Paris, June 1988; Schertzer and Lovejoy, 1991, five consecutive annual sessions at EGS general assemblies and two consecutive spring AGU meeting sessions. As with the other conferences and workshops mentioned above, the aim was to develop confrontation between theories and experiments on scaling/multifractal behaviour of geophysical fields. Subjects covered included climate, clouds, earthquakes, atmospheric and ocean dynamics, tectonics, precipitation, hydrology, the solar cycle and volcanoes. Areas of focus included new methods of data analysis (especially those used for the reliable estimation of multifractal and scaling exponents, as well as their application to rapidly growing data bases from in situ networks and remote sensing. The corresponding modelling, prediction and estimation techniques were also emphasized as were the current debates about stochastic and deterministic dynamics, fractal geometry and multifractals, self-organized criticality and multifractal fields, each of which was the subject of a specific general discussion. The conference started with a one day short course of multifractals featuring four lectures on a Fundamentals of multifractals: dimension, codimensions, codimension formalism, b Multifractal estimation techniques: (PDMS, DTM, c Numerical simulations, Generalized Scale Invariance analysis, d Advanced multifractals, singular statistics, phase transitions, self-organized criticality and Lie cascades (given by D. Schertzer and S. Lovejoy, detailed course notes were sent to participants shortly after the

  11. EGS Richardson AGU Chapman NVAG3 Conference: Nonlinear Variability in Geophysics: scaling and multifractal processes

    Science.gov (United States)

    Schertzer, D.; Lovejoy, S.

    1. The conference The third conference on "Nonlinear VAriability in Geophysics: scaling and multifractal processes" (NVAG 3) was held in Cargese, Corsica, Sept. 10-17, 1993. NVAG3 was joint American Geophysical Union Chapman and European Geophysical Society Richardson Memorial conference, the first specialist conference jointly sponsored by the two organizations. It followed NVAG1 (Montreal, Aug. 1986), NVAG2 (Paris, June 1988; Schertzer and Lovejoy, 1991), five consecutive annual sessions at EGS general assemblies and two consecutive spring AGU meeting sessions. As with the other conferences and workshops mentioned above, the aim was to develop confrontation between theories and experiments on scaling/multifractal behaviour of geophysical fields. Subjects covered included climate, clouds, earthquakes, atmospheric and ocean dynamics, tectonics, precipitation, hydrology, the solar cycle and volcanoes. Areas of focus included new methods of data analysis (especially those used for the reliable estimation of multifractal and scaling exponents), as well as their application to rapidly growing data bases from in situ networks and remote sensing. The corresponding modelling, prediction and estimation techniques were also emphasized as were the current debates about stochastic and deterministic dynamics, fractal geometry and multifractals, self-organized criticality and multifractal fields, each of which was the subject of a specific general discussion. The conference started with a one day short course of multifractals featuring four lectures on a) Fundamentals of multifractals: dimension, codimensions, codimension formalism, b) Multifractal estimation techniques: (PDMS, DTM), c) Numerical simulations, Generalized Scale Invariance analysis, d) Advanced multifractals, singular statistics, phase transitions, self-organized criticality and Lie cascades (given by D. Schertzer and S. Lovejoy, detailed course notes were sent to participants shortly after the conference). This

  12. Fungsi Bangunan Dokwi Vam dan Kembu Vam Bagi Suku Yali dalam Novel Penguasa-penguasa Bumi Karya Don Richardson

    Directory of Open Access Journals (Sweden)

    Ummu Fatimah Ria Lestari

    2016-04-01

    Full Text Available This study discusses the function of the building of Dokwi Vam and Kembu Vam contained in the novel-Sovereign Ruler of the Earth works Don Richardson. In general, this novel tells the story of the life of Stan Dale and Yali tribe. Stan Dale is a missionary who served in Papua. He struggled to introduce Christianity to the Yali tribe. This study uses the description of the technical literature. This research resulted in a description of the function of the building of Dokwi Vam and Kembu Vam contained in the novel Lord of-Ruler of the Earth works Don Richardson. Dokwi Vam used as a museum (where the old stuff to worship as they still follow animism, while the Kembu Vam serves as a temple / animism worship in Yali tribe. Penelitian ini membahas tentang fungsi bangunan Dokwi Vam dan Kembu Vam yang terdapat dalam novel Penguasa-Penguasa Bumi karya Don Richardson. Secara umum, novel ini bercerita tentang kehidupan Stan Dale dan suku Yali. Stan Dale adalah seorang missionaris yang melayani di Tanah Papua. Ia berjuang untuk memperkenalkan agama Nasrani kepada suku Yali. Penelitian ini menggunakan metode deskripsi dengan teknik studi pustaka. Penelitian ini menghasilkan deskripsi tentang fungsi bangunan Dokwi Vam dan Kembu Vam yang terdapat dalam novel Penguasa-Penguasa Bumi karya Don Richardson. Dokwi Vam digunakan sebagai museum (tempat barang-barang kuno untuk penyembahan karena mereka masih menganut kepercayaan animisme, sedangkan Kembu Vam berfungsi sebagai rumah peribadatan/penyembahan dalam kepercayaan animisme suku Yali.

  13. The safe, economical operation of a slightly subcritical reactor and transmutor with a small proton accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Hiroshi

    1994-04-01

    This report describes methods in which an accelerator can be used to increase the safety and neutron economy of a power reactor and transmutor of long-lived radioactive wastes, such as minor actinides and fission products, by providing neutrons for its subcritical operation. Instead of the rather large subcriticality of k=0.9--0.95 which we originally proposed for such a transmutor, we propose to use a slightly subcritical reactor, such as k=0.99, which will avoid many of the technical difficulties that are associated with large subcriticality, such as localized power peaking, radiation damage due to the injection of medium-energy protons, the high current accelerator, and the requirement for a long beam-expansion section. We analyzed the power drop that occurred in Phoenix reactor, and show that the operating this reactor in subcritical condition improves its safety.

  14. Subcritical and supercritical water oxidation of CELSS model wastes

    Science.gov (United States)

    Takahashi, Y.; Wydeven, T.; Koo, C.

    1989-01-01

    A mixture of ammonium hydroxide with acetic acid and a slurry of human feces, urine, and wipes were used as CELSS model wastes to be wet-oxidized at temperatures from 250 to 500 C, i.e. below and above the critical point of water (374 C and 218 kg/sq cm or 21.4 MPa). The effects of oxidation temperature ( 250-500 C) and residence time (0-120 mn) on carbon and nitrogen and on metal corrosion from the reactor material were studied. Almost all of the organic matter in the model wastes was oxidized in the temperature range from 400 to 500 C, above the critical conditions for water. In contrast, only a small portion of the organic matter was oxidized at subcritical conditions. A substantial amount of nitrogen remained in solution in the form of ammonia at temperatures ranging from 350 to 450 C suggesting that, around 400 C, organic carbon is completely oxidized and most of the nitrogen is retained in solution. The Hastelloy C-276 alloy reactor corroded during subcritical and supercritical water oxidation.

  15. Hydrolysis of sweet blue lupin hull using subcritical water technology.

    Science.gov (United States)

    Ciftci, Deniz; Saldaña, Marleny D A

    2015-10-01

    Hydrolysis of sweet blue lupin hulls was conducted in this study using subcritical water technology. Effects of process parameters, such as pressure (50-200 bar), temperature (160-220°C), flow rate (2-10 mL/min), and pH (2-12), were studied to optimize maximum hemicellulose sugars recovery in the extracts. Extracts were analyzed for total hemicellulose sugars, phenolics and organic carbon contents and solid residues left after treatments were also characterized. Temperature, flow rate, and pH had a significant effect on hemicellulose sugar removal; however, the effect of pressure was not significant. The highest yield of hemicellulose sugars in the extracts (85.5%) was found at 180°C, 50 bar, 5 mL/min and pH 6.2. The thermal stability of the solid residue obtained at optimum conditions improved after treatment and the crystallinity index increased from 11.5% to 58.6%. The results suggest that subcritical water treatment is a promising technology for hemicellulose sugars removal from biomass. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Subcritical water extractor for Mars analog soil analysis.

    Science.gov (United States)

    Amashukeli, Xenia; Grunthaner, Frank J; Patrick, Steven B; Yung, Pun To

    2008-06-01

    Abstract Technologies that enable rapid and efficient extraction of biomarker compounds from various solid matrices are a critical requirement for the successful implementation of in situ chemical analysis of the martian regolith. Here, we describe a portable subcritical water extractor that mimics multiple organic solvent polarities by tuning the dielectric constant of liquid water through adjustment of temperature and pressure. Soil samples, collected from the Yungay region of the Atacama Desert (martian regolith analogue) in the summer of 2005, were used to test the instrument's performance. The total organic carbon was extracted from the samples at concentrations of 0.2-55.4 parts per million. The extraction data were compared to the total organic carbon content in the bulk soil, which was determined via a standard analytical procedure. The instrument's performance was examined over the temperature range of 25-250 degrees C at a fixed pressure of 20.7 MPa. Under these conditions, water remains in a subcritical fluid state with a dielectric constant varying between approximately 80 (at 25 degrees C) and approximately 30 (at 250 degrees C).

  17. Thorium as a Fuel for Accelerator Driven Subcritical Electronuclear Systems

    CERN Document Server

    Barashenkov, V S; Singh, V

    2000-01-01

    Neutron yield and energy production in a very large, practically infinite, uranium and thorium target-blocks irradiated by protons with energies in the range 0.1-2 GeV are studied by Monte Carlo method. Though the comparison of uranium and thorium targets shows that the neutron yield in the latter is 30-40 % less and the energy gain is approximatelly two times smaller, accelerator Driven subcritical Systems (ADS) with thorium fuel are very perspective at the bombarding energies higher than several hundreds MeV. An admixture of fissile elements U^{233}, U^{235}, Pu^{239} in the set-up gives larger neutron multiplication which in turn shows better energy amplification. It is argued that due to the practically complete burning of the fuel in such set-up there is no need of technology of conversion of the exhaust fuel.

  18. Scanning two-photon microscopy with upconverting lanthanide nanoparticles via Richardson-Lucy deconvolution

    Science.gov (United States)

    Gainer, Christian F.; Utzinger, Urs

    2012-01-01

    Abstract. The use of upconverting lanthanide nanoparticles in fast-scanning microscopy is hindered by a long luminescence decay time, which greatly blurs images acquired in a nondescanned mode. We demonstrate herein an image processing method based on Richardson-Lucy deconvolution that mitigates the detrimental effects of their luminescence lifetime. This technique generates images with lateral resolution on par with the system’s performance, ∼1.2  μm, while maintaining an axial resolution of 5 μm or better at a scan rate comparable with traditional two-photon microscopy. Remarkably, this can be accomplished with near infrared excitation power densities of 850  W/cm2, several orders of magnitude below those used in two-photon imaging with molecular fluorophores. By way of illustration, we introduce the use of lipids to coat and functionalize these nanoparticles, rendering them water dispersible and readily conjugated to biologically relevant ligands, in this case epidermal growth factor receptor antibody. This deconvolution technique combined with the functionalized nanoparticles will enable three-dimensional functional tissue imaging at exceptionally low excitation power densities. PMID:22894486

  19. In vitro cultivation model for Heterosporis saurida (Microsporidia) isolated from lizardfish, Saurida undosquamis (Richardson).

    Science.gov (United States)

    Kumar, G; Saleh, M; Abdel-Baki, A-A S; Al-Quraishy, S; El-Matbouli, M

    2014-05-01

    Heterosporis saurida is a microsporidian that infects lizardfish, Saurida undosquamis (Richardson, 1848), in the Arabian Sea. Spores were isolated from infected lizardfish and used to infect derived fish cell lines: common carp brain (CCB), epithelioma papulosum cyprinid (EPC), fathead minnow epithelial (FHM), rainbow trout gonad (RTG), bluegill fry (BF-2) and chinook salmon embryo (CHSE). Non-fish cell lines were also tested that include: insect (SF-9), rabbit (RK-13) and African green monkey (Vero E6). No growth of H. saurida was observed in any fish cell line, SF-9 or Vero E6 cell lines. H. saurida spores grew only in RK-13 cell line and were detected by immunofluorescence. Developmental stages of H. saurida were seen in RK-13 cells by light and transmission electron microscopy, and species identification was confirmed by sequencing. This study demonstrated that H. saurida was able to proliferate in the mammalian RK-13 cell line, which thus represents an in vitro model for conducting molecular genetics and cell-pathogen interaction studies of Heterosporis. © 2013 John Wiley & Sons Ltd.

  20. Towards social autonomous vehicles: Efficient collision avoidance scheme using Richardson's arms race model.

    Directory of Open Access Journals (Sweden)

    Faisal Riaz

    Full Text Available This paper presents the concept of a social autonomous agent to conceptualize such Autonomous Vehicles (AVs, which interacts with other AVs using social manners similar to human behavior. The presented AVs also have the capability of predicting intentions, i.e. mentalizing and copying the actions of each other, i.e. mirroring. Exploratory Agent Based Modeling (EABM level of the Cognitive Agent Based Computing (CABC framework has been utilized to design the proposed social agent. Furthermore, to emulate the functionality of mentalizing and mirroring modules of proposed social agent, a tailored mathematical model of the Richardson's arms race model has also been presented. The performance of the proposed social agent has been validated at two levels-firstly it has been simulated using NetLogo, a standard agent-based modeling tool and also, at a practical level using a prototype AV. The simulation results have confirmed that the proposed social agent-based collision avoidance strategy is 78.52% more efficient than Random walk based collision avoidance strategy in congested flock-like topologies. Whereas practical results have confirmed that the proposed scheme can avoid rear end and lateral collisions with the efficiency of 99.876% as compared with the IEEE 802.11n-based existing state of the art mirroring neuron-based collision avoidance scheme.

  1. Towards social autonomous vehicles: Efficient collision avoidance scheme using Richardson's arms race model.

    Science.gov (United States)

    Riaz, Faisal; Niazi, Muaz A

    2017-01-01

    This paper presents the concept of a social autonomous agent to conceptualize such Autonomous Vehicles (AVs), which interacts with other AVs using social manners similar to human behavior. The presented AVs also have the capability of predicting intentions, i.e. mentalizing and copying the actions of each other, i.e. mirroring. Exploratory Agent Based Modeling (EABM) level of the Cognitive Agent Based Computing (CABC) framework has been utilized to design the proposed social agent. Furthermore, to emulate the functionality of mentalizing and mirroring modules of proposed social agent, a tailored mathematical model of the Richardson's arms race model has also been presented. The performance of the proposed social agent has been validated at two levels-firstly it has been simulated using NetLogo, a standard agent-based modeling tool and also, at a practical level using a prototype AV. The simulation results have confirmed that the proposed social agent-based collision avoidance strategy is 78.52% more efficient than Random walk based collision avoidance strategy in congested flock-like topologies. Whereas practical results have confirmed that the proposed scheme can avoid rear end and lateral collisions with the efficiency of 99.876% as compared with the IEEE 802.11n-based existing state of the art mirroring neuron-based collision avoidance scheme.

  2. A stopping criterion to halt iterations at the Richardson-Lucy deconvolution of radiographic images

    Science.gov (United States)

    Almeida, G. L.; Silvani, M. I.; Souza, E. S.; Lopes, R. T.

    2015-07-01

    Radiographic images, as any experimentally acquired ones, are affected by spoiling agents which degrade their final quality. The degradation caused by agents of systematic character, can be reduced by some kind of treatment such as an iterative deconvolution. This approach requires two parameters, namely the system resolution and the best number of iterations in order to achieve the best final image. This work proposes a novel procedure to estimate the best number of iterations, which replaces the cumbersome visual inspection by a comparison of numbers. These numbers are deduced from the image histograms, taking into account the global difference G between them for two subsequent iterations. The developed algorithm, including a Richardson-Lucy deconvolution procedure has been embodied into a Fortran program capable to plot the 1st derivative of G as the processing progresses and to stop it automatically when this derivative - within the data dispersion - reaches zero. The radiograph of a specially chosen object acquired with thermal neutrons from the Argonauta research reactor at Institutode Engenharia Nuclear - CNEN, Rio de Janeiro, Brazil, have undergone this treatment with fair results.

  3. A Novel Richardson-Lucy Model with Dictionary Basis and Spatial Regularization for Isolating Isotropic Signals.

    Directory of Open Access Journals (Sweden)

    Tiantian Xu

    Full Text Available Diffusion-weighted magnetic resonance imaging is a non-invasive imaging method that has been increasingly used in neuroscience imaging over the last decade. Partial volume effects (PVEs exist in sampling signal for many physical and actual reasons, which lead to inaccurate fiber imaging. We overcome the influence of PVEs by separating isotropic signal from diffusion-weighted signal, which can provide more accurate estimation of fiber orientations. In this work, we use a novel response function (RF and the correspondent fiber orientation distribution function (fODF to construct different signal models, in which case the fODF is represented using dictionary basis function. We then put forward a new index Piso, which is a part of fODF to quantify white and gray matter. The classic Richardson-Lucy (RL model is usually used in the field of digital image processing to solve the problem of spherical deconvolution caused by highly ill-posed least-squares algorithm. In this case, we propose an innovative model integrating RL model with spatial regularization to settle the suggested double-models, which improve noise resistance and accuracy of imaging. Experimental results of simulated and real data show that the proposal method, which we call iRL, can robustly reconstruct a more accurate fODF and the quantitative index Piso performs better than fractional anisotropy and general fractional anisotropy.

  4. Water ice in the dark dune spots of Richardson crater on Mars

    CERN Document Server

    Kereszturi, A; Schmidt, F

    2010-01-01

    In this study we assess the presence, nature and properties of ices - in particular water ice - that occur within these spots using HIRISE and CRISM observations, as well as the LMD Global Climate Model. Our studies focus on Richardson crater (72{\\deg}S, 179{\\deg}E) and cover southern spring and summer (LS 175{\\deg} - 17 341{\\deg}). Three units have been identified of these spots: dark core, gray ring and bright halo. Each unit show characteristic changes as the season progress. In winter, the whole area is covered by CO2 ice with H2O ice contamination. Dark spots form during late winter and early spring. During spring, the dark spots are located in a 10 cm thick depression compared to the surrounding bright ice-rich layer. They are spectrally characterized by weak CO2 ice signatures that probably result from spatial mixing of CO2 ice rich and ice free regions within pixels, and from mixing of surface signatures due to aerosols scattering. The bright halo shaped by winds shows stronger CO2 absorptions than th...

  5. Subcritical-Water Extraction of Organics from Solid Matrices

    Science.gov (United States)

    Amashukeli, Xenia; Grunthaner, Frank; Patrick, Steven; Kirby, James; Bickler, Donald; Willis, Peter; Pelletier, Christine; Bryson, Charles

    2009-01-01

    An apparatus for extracting organic compounds from soils, sands, and other solid matrix materials utilizes water at subcritical temperature and pressure as a solvent. The apparatus, called subcritical water extractor (SCWE), is a prototype of subsystems of future instrumentation systems to be used in searching for organic compounds as signs of past or present life on Mars. An aqueous solution generated by an apparatus like this one can be analyzed by any of a variety of established chromatographic or spectroscopic means to detect the dissolved organic compound( s). The apparatus can be used on Earth: indeed, in proof-of-concept experiments, SCWE was used to extract amino acids from soils of the Atacama Desert (Chile), which was chosen because the dryness and other relevant soil conditions there approximate those on Mars. The design of the apparatus is based partly on the fact that the relative permittivity (also known as the dielectric constant) of liquid water varies with temperature and pressure. At a temperature of 30 C and a pressure of 0.1 MPa, the relative permittivity of water is 79.6, due to the strong dipole-dipole electrostatic interactions between individual molecular dipoles. As the temperature increases, increasing thermal energy causes increasing disorientation of molecular dipoles, with a consequent decrease in relative permittivity. For example, water at a temperature of 325 C and pressure of 20 MPa has a relative permittivity of 17.5, which is similar to the relative permittivities of such nonpolar organic solvents as 1-butanol (17.8). In the operation of this apparatus, the temperature and pressure of water are adjusted so that the water can be used in place of commonly used organic solvents to extract compounds that have dissimilar physical and chemical properties.

  6. Review of Bonnie Latimer, Making Gender, Culture, and the Self in the Fiction of Samuel Richardson: The Novel Individual

    Directory of Open Access Journals (Sweden)

    Karen Lipsedge

    2014-03-01

    Full Text Available Latimer’s Making Gender, Culture, and the Self in the Fiction of Samuel Richardson answers a need in eighteenth-century Richardsonian studies. It is also a thoughtful and long overdue study, which deserves praise and attention. Latimer provides the reader with a greater understanding of the notion of female individuality in Richardson’s novels, and also of eighteenth-century culture and contemporary literature. Her research is gratifying in its level of detail, and she is deft in showing correspondences between eighteenth-century culture, fiction and Richardson’s novels. Although Sir Charles Grandison lies at the heart of this study, Latimer is equally skilful in devoting attention to Richardson’s last novel without marginalizing his other work. In addition, Latimer offers a refreshing and fitting conclusion to Making Gender, Culture, and the Self in the Fiction of Samuel Richardson. By ending with an Afterword, Latimer ensures that she opens out and extends the discussion on the female individual, Richardson’s novels and his literary legacy. In Making Gender, Culture, and the Self in the Fiction of Samuel Richardson Latimer suggests that further examination of these areas is not only timely, but also necessary and rewarding.

  7. Coupled Subcritical Water and Solid Phase Extraction for In-Situ Chemical Analysis Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Leiden Measurement Technology (LMT) will design and develop a low volume analyte separation, concentration, and transfer system (ConTech), that couples a Subcritical...

  8. Dietary leucine requirement for juvenile large yellow croaker Pseudosciaena crocea (Richardson, 1846)

    Science.gov (United States)

    Li, Yan; Ai, Qinghui; Mai, Kangsen; Xu, Wei; Cheng, Zhenyan; He, Zhigang

    2010-12-01

    Dietary leucine requirement for juvenile large yellow croaker, Pseudosciaena crocea Richardson 1846 (initial body weight 6.0 g ± 0.1 g) was determined using dose-response method. Six isonitogenous (crude protein 43%) and isoenergetic (19 kJ g-1) practical diets containing six levels of leucine (Diets 1-6) ranging from 1.23% to 4.80% (dry matter) were made at about 0.7% increment of leucine. Equal amino acid nitrogen was maintained by replacing leucine with glutamic acid. Triplicate groups of 60 individuals were fed to apparent satiation by hand twice daily (05:00 and 17:30). The water temperature was 26-32°C, salinity 26-30 and dissolved oxygen approximately 7 mg L-1 during the experimental period. Final weight (FW) of large yellow croaker initially increased with increasing level of dietary leucine but then decreased at further higher level of leucine. The highest FW was obtained in fish fed diet with 3.30% Leucine (Diet 4). FW of fish fed the diet with 4.80% Leucine (Diet 6) was significantly lower than those fed Diet 4. However, no significant differences were observed between the other dietary treatments. Feed efficiency (FE) and whole body composition were independent of dietary leucine contents ( P > 0.05). The results indicated that leucine was essential for growth of juvenile large yellow croaker. On the basis of FW, the optimum dietary leucine requirement for juvenile large yellow croaker was estimated to be 2.92% of dry matter (6.79% of dietary protein).

  9. La fotografia tra Arte e Scienza sociale. Arturo Ghergo, Bob Richardson, Bettina Rheims

    Directory of Open Access Journals (Sweden)

    Alessandra Olivares

    2015-12-01

    Full Text Available What does the photography in contemporary visual culture? In the ever increasing interference between art and society, photography took over, as you can see, a leading role in what Enrico Menduni defines the process of "picture show", especially if it isconsidered in its close relationship with the advertising industry. However you cannot ignore the fact that, being closely bound to functions that is responsible, photography is also a social practice. These considerations have a concrete response in the contemporary art. Arturo Ghergo (1901-1959, Bob Richardson (1928-2005 and Bettina Rheims (1952 are artists with very different poetics that while making photographs on commission (for movies, advertising, fashion and magazines told through pictures their time (and the aspects of reality that have characterized reaching high and recognized results of artistic and aesthetic value. They are just three of the many photographers who put us in front of the hybrid status of photography as "a medium [...] inextricably linked to two aspects: aesthetic and sociological" (Dorfles 2012. Discussions on the border between photography-craft and photography-art, which long have marked and restricted the destiny of many photographers, today finally appear anachronistic, but not entirely overcome. We see more and more often a dissolution of identity between the two areas with important examples of the deep connection of the dichotomy between art and social aspects. If it is true that art has always told, interpreted and reflected on the reality that is part, what seems interesting to highlight is the fact that the impact on the collective imaginary that new visual media, photography in primis, have had and continue to have increasingly appears to have no background. Therefore, art has never been so close to life.

  10. Theoretical Analysis for Heat Transfer Optimization in Subcritical Electrothermal Energy Storage Systems

    OpenAIRE

    Peng Hu; Gao-Wei Zhang; Long-Xiang Chen; Ming-Hou Liu

    2017-01-01

    Electrothermal energy storage (ETES) provides bulk electricity storage based on heat pump and heat engine technologies. A subcritical ETES is described in this paper. Based on the extremum principle of entransy dissipation, a geometry model is developed for heat transfer optimization for subcritical ETES. The exergy during the heat transfer process is deduced in terms of entropy production. The geometry model is validated by the extremum principle of entropy production. The theoretical analys...

  11. Subcritical Noise Analysis Measurements with Fresh and Spent Research Reactor Fuels Elements

    Energy Technology Data Exchange (ETDEWEB)

    Valentine, T.E.; Mihalczo, J.T.; Kryter, R.C.; Miller, V.C.

    1999-02-01

    The verification of the subcriticality is of utmost importance for the safe transportation and storage of nuclear reactor fuels. Transportation containers and storage facilities are designed such that nuclear fuels remain in a subcritical state. Such designs often involve excess conservatism because of the lack of relevant experimental data to verify the accuracy of Monte Carlo codes used in nuclear criticality safety analyses. A joint experimental research program between Oak Ridge National Laboratory, Westinghouse Safety Management Solutions, Inc., and the University of Missouri was initiated to obtain measured quantities that could be directly related to the subcriticality of simple arrays of Missouri University Research Reactor (MURR) fuel elements. A series of measurement were performed to assess the reactivity of materials such as BORAL, stainless steel, aluminum, and lead that are typically used in the construction of shipping casks. These materials were positioned between the fuel elements. In addition, a limited number of measurements were performed with configurations of fresh and spent (irradiated) fuel elements to ascertain the reactivity of the spent fuel elements. In these experiments, fresh fuel elements were replaced by spent fuel elements such that the subcritical reactivity change could be measured. The results of these measurements were used by Westinghouse Safety Management Solutions to determine the subcriticality of MURR fuel elements isolated by absorbing materials. The measurements were interpreted using the MCNP-DSP Monte Carlo code to obtain the subcritical neutron multiplication factor k(sub eff), and the bias in K(sub eff) that are used in criticality safety analyses.

  12. Numerical simulations of subcritical reactor kinetics in thermal hydraulic transient phases

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, J.; Park, W. S. [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1998-12-31

    A subcritical reactor driven by a linear proton accelerator has been considered as a nuclear waste incinerator at Korea Atomic Energy Research Institute (KAERI). Since the multiplication factor of a subcritical reactor is less than unity, to compensate exponentially decreasing fission neutrons, external neutrons form spallation reactions are essentially required for operating the reactor in its steady state. Furthermore, the profile of accelerator beam currents is very important in controlling a subcritical reactor, because the reactor power varies in accordance to the profile of external neutrons. We have developed a code system to find numerical solutions of reactor kinetics equations, which are the simplest dynamic model for controlling reactors. In a due course of our previous numerical study of point kinetics equations for critical reactors, however, we learned that the same code system can be used in studying dynamic behavior of the subcritical reactor. Our major motivation of this paper is to investigate responses of subcritical reactors for small changes in thermal hydraulic parameters. Building a thermal hydraulic model for the subcritical reactor dynamics, we performed numerical simulations for dynamic responses of the reactor based on point kinetics equations with a source term. Linearizing a set of coupled differential equations for reactor responses, we focus our research interest on dynamic responses of the reactor to variations of the thermal hydraulic parameters in transient phases. 5 refs., 8 figs. (Author)

  13. Subcritical Water Hydrolysis of Peptides: Amino Acid Side-Chain Modifications

    Science.gov (United States)

    Powell, Thomas; Bowra, Steve; Cooper, Helen J.

    2017-09-01

    Previously we have shown that subcritical water may be used as an alternative to enzymatic digestion in the proteolysis of proteins for bottom-up proteomics. Subcritical water hydrolysis of proteins was shown to result in protein sequence coverages greater than or equal to that obtained following digestion with trypsin; however, the percentage of peptide spectral matches for the samples treated with trypsin were consistently greater than for those treated with subcritical water. This observation suggests that in addition to cleavage of the peptide bond, subcritical water treatment results in other hydrolysis products, possibly due to modifications of amino acid side chains. Here, a model peptide comprising all common amino acid residues (VQSIKCADFLHYMENPTWGR) and two further model peptides (VCFQYMDRGDR and VQSIKADFLHYENPTWGR) were treated with subcritical water with the aim of probing any induced amino acid side-chain modifications. The hydrolysis products were analyzed by direct infusion electrospray tandem mass spectrometry, either collision-induced dissociation or electron transfer dissociation, and liquid chromatography collision-induced dissociation tandem mass spectrometry. The results show preferential oxidation of cysteine to sulfinic and sulfonic acid, and oxidation of methionine. In the absence of cysteine and methionine, oxidation of tryptophan was observed. In addition, water loss from aspartic acid and C-terminal amidation were observed in harsher subcritical water conditions. [Figure not available: see fulltext.

  14. Experimental subcritical facility driven by D-D/D-T neutron generator at BARC, India

    Science.gov (United States)

    Sinha, Amar; Roy, Tushar; Kashyap, Yogesh; Ray, Nirmal; Shukla, Mayank; Patel, Tarun; Bajpai, Shefali; Sarkar, P. S.; Bishnoi, Saroj

    2015-05-01

    The paper presents design of an experimental subcritical assembly driven by D-D/D-T neutron and preliminary experimental measurements. The system has been developed for investigating the static and dynamic neutronic properties of accelerator driven sub-critical systems. This system is modular in design and it is first in the series of subcritical assemblies being designed. The subcritical core consists of natural uranium fuel with high density polyethylene as moderator and beryllium oxide as reflector. The fuel is embedded in high density polyethylene moderator matrix. Estimated keff of the system is ∼0.89. One of the unique features of subcritical core is the use of Beryllium oxide (BeO) as reflector and HDPE as moderator making the assembly a compact modular system. The subcritical core is coupled to Purnima Neutron Generator which works in D-D and D-T mode with both DC and pulsed operation. It has facility for online source strength monitoring using neutron tagging and programmable source modulation. Preliminary experiments have been carried out for spatial flux measurement and reactivity estimation using pulsed neutron source (PNS) techniques with D-D neutrons. Further experiments are being planned to measure the reactivity and other kinetic parameters using noise methods. This facility would also be used for carrying out studies on effect of source importance and measurement of source multiplication factor ks and external neutron source efficiency φ∗ in great details. Experiments with D-T neutrons are also underway.

  15. Development study on subcriticality monitor. 1. Report under business contract with Japan Nuclear Fuel Cycle Development Institute

    CERN Document Server

    Yamada, S

    2002-01-01

    In this trust fund, we reviewed subcriticality measuring methods and neutron or gamma ray measuring and date transmission systems appropriate for realizing inexpensive on-line criticality surveillance systems, which is required for ensuring the safety of nuclear fuel reprocessing plants. Since the neutron flux level in subcritical systems is fairly low without external neutron sources, it is desirable to use pulse type neutron detectors for subcritical measurement systems. This logically implies that subcriticality measurement methods based on the temporal domain should be used for developing an on-line criticality surveillance system. In the deep subcriticality conditions, a strong external neutron source is needed for eactivity measurement and a D-T tube can be used in order to improve the accuracy of the measurement. A D-T tube is convenient since it is free from Tritium problem since Tritium is sealed in an airtight container and also can be controlled by power supply. Hence, under deep subcritical condit...

  16. Subcritical hydrothermal conversion of organic wastes and biomass. Reaction pathways

    Directory of Open Access Journals (Sweden)

    Alejandro Amadeus Castro Vega

    2010-04-01

    Full Text Available Hydrothermal conversion is a procedure which emulates organic matter’s natural conversion into bio-crude having physical and chemical properties analogous to petroleum. The artificial transformation of biomass requi- res previous knowledge of the main reaction routes and product availability. The main component of biomass (depolymerisation by hydrolysis is presented in hydrothermal cellulose conversion, producing oligosaccharides which exhibit dehydration and retro-aldol condensation reactions for transforming into furfurals and carboxylic acids. Other biomass components (such as lignin, proteins, and fat esters present both hydrolysis and pyrolysis reaction routes. As long as biomass mainly contains carbohydrates, subcritical hydrothermal conversion products and their wastes will be fundamentally analogous to those displaying cellulose. These substances have added- value by far surpassing raw material’s acquisition cost. When the main hydrothermal conversion products’ O/C, H/C molar ratios as reported in literature are plotted, an evolutionary tralectory for conversion products appears to be closely or even overlapped with fossil fuels’ geological evolution.

  17. Effect of fluid salinity on subcritical crack propagation in calcite

    Science.gov (United States)

    Rostom, Fatma; Røyne, Anja; Dysthe, Dag Kristian; Renard, François

    2013-01-01

    The slow propagation of cracks, also called subcritical crack growth, is a mechanism of fracturing responsible for a ductile deformation of rocks under crustal conditions. In the present study, the double-torsion technique was used to measure the effect of fluid chemistry on the slow propagation of cracks in calcite single crystals at room temperature. Time-lapse images and measurements of force and load-point displacement allowed accurate characterization of crack velocities in a range of 10- 8 to 10- 4 m/s. Velocity curves as a function of energy-release rates were obtained for different fluid compositions, varying NH4Cl and NaCl concentrations. Our results show the presence of a threshold in fluid composition, separating two regimes: weakening conditions where the crack propagation is favored, and strengthening conditions where crack propagation slows down. We suggest that electrostatic surface forces that modify the repulsion forces between the two surfaces of the crack may be responsible for this behavior.

  18. Effective Subcritical Butane Extraction of Bifenthrin Residue in Black Tea.

    Science.gov (United States)

    Zhang, Yating; Gu, Lingbiao; Wang, Fei; Kong, Lingjun; Qin, Guangyong

    2017-03-30

    As a natural and healthy beverage, tea is widely enjoyed; however, the pesticide residues in tea leaves affect the quality and food safety. To develop a highly selective and efficient method for the facile removal of pesticide residues, the subcritical butane extraction (SBE) technique was employed, and three variables involving temperature, time and extraction cycles were studied. The optimum SBE conditions were found to be as follows: extraction temperature 45 °C, extraction time 30 min, number of extraction cycles 1, and in such a condition that the extraction efficiency reached as high as 92%. Further, the catechins, theanine, caffeine and aroma components, which determine the quality of the tea, fluctuated after SBE treatment. Compared with the uncrushed leaves, pesticide residues can more easily be removed from crushed leaves, and the practical extraction efficiency was 97%. These results indicate that SBE is a useful method to efficiently remove the bifenthrin, and as appearance is not relevant in the production process, tea leaves should first be crushed and then extracted in order that residual pesticides are thoroughly removed.

  19. The Chain-Length Distribution in Subcritical Systems

    Energy Technology Data Exchange (ETDEWEB)

    Nolen, Steven Douglas [Texas A & M Univ., College Station, TX (United States)

    2000-06-01

    The individual fission chains that appear in any neutron multiplying system provide a means, via neutron noise analysis, to unlock a wealth of information regarding the nature of the system. This work begins by determining the probability density distributions for fission chain lengths in zero-dimensional systems over a range of prompt neutron multiplication constant (K) values. This section is followed by showing how the integral representation of the chain-length distribution can be used to obtain an estimate of the system's subcritical prompt multiplication (MP). The lifetime of the chains is then used to provide a basis for determining whether a neutron noise analysis will be successful in assessing the neutron multiplication constant, k, of the system in the presence of a strong intrinsic source. A Monte Carlo transport code, MC++, is used to model the evolution of the individual fission chains and to determine how they are influenced by spatial effects. The dissertation concludes by demonstrating how experimental validation of certain global system parameters by neutron noise analysis may be precluded in situations in which the system K is relatively low and in which realistic detector efficiencies are simulated.

  20. Catalytic upgrading of duckweed biocrude in subcritical water.

    Science.gov (United States)

    Zhang, Caicai; Duan, Peigao; Xu, Yuping; Wang, Bing; Wang, Feng; Zhang, Lei

    2014-08-01

    Herein, a duckweed biocrude produced from the hydrothermal liquefaction of Lemna minor was treated in subcritical water with added H₂. Effects of several different commercially available materials such as Ru/C, Pd/C, Pt/C, Pt/γ-Al₂O₃, Pt/C-sulfide, Rh/γ-Al₂O₃, activated carbon, MoS₂, Mo₂C, Co-Mo/γ-Al₂O₃, and zeolite on the yields of product fractions and the deoxygenation, denitrogenation, and desulfurization of biocrude at 350°C were examined, respectively. All the materials showed catalytic activity for deoxygenation and desulfurization of the biocrude and only Ru/C showed activity for denitrogenation. Of those catalysts examined, Pt/C showed the best performance for deoxygenation. Among all the upgraded oils, the oil produced with Ru/C shows the lowest sulfur, the highest hydrocarbon content (25.6%), the highest energy recovery (85.5%), and the highest higher heating value (42.6 MJ/kg). The gaseous products were mainly unreacted H₂, CH₄, CO₂, and C₂H6. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Reynolds number effect on VIV: from subcritical to supercritical flow

    Energy Technology Data Exchange (ETDEWEB)

    Triantafyllou, M.S.; Hover, F.S.; Techet, A.H. [Massachusetts Inst. of Tech., Dept. of Ocean Engineering, Cambridge, MA (United States)

    2004-07-01

    Vortex Induced Vibrations in flexibly supported rigid cylinders and long, flexible slender structures, such as cables and risers, are caused by the formation of large-scale vortices, whose dynamics are controlled to a large extend by inviscid mechanisms. Reynolds number remains a very important parameter, however, because it influences the formation and shedding mechanisms of the vortical patterns. For low Reynolds numbers, below a few thousand, a nearly complete understanding has been obtained in recent years, at least for flexibly mounted rigid cylinders. This is not the case, though, for VIV above Re=10,000 and - especially - above the critical Reynolds number of about Re=250,000 for smooth cylinders. The talk provides observed WV trends of flexibly mounted cylinders, obtained in recent experiments as function of the Reynolds number, from Re about 1,000 up to 1,000,000. In particular, similarities and differences between subcritical and supercritical force and motion data will be discussed, and conclusions on the governing principal mechanisms will be drawn, including transitions in the arrangement of vortical patterns and effects of correlation length. (authors)

  2. Effective Subcritical Butane Extraction of Bifenthrin Residue in Black Tea

    Directory of Open Access Journals (Sweden)

    Yating Zhang

    2017-03-01

    Full Text Available As a natural and healthy beverage, tea is widely enjoyed; however, the pesticide residues in tea leaves affect the quality and food safety. To develop a highly selective and efficient method for the facile removal of pesticide residues, the subcritical butane extraction (SBE technique was employed, and three variables involving temperature, time and extraction cycles were studied. The optimum SBE conditions were found to be as follows: extraction temperature 45 °C, extraction time 30 min, number of extraction cycles 1, and in such a condition that the extraction efficiency reached as high as 92%. Further, the catechins, theanine, caffeine and aroma components, which determine the quality of the tea, fluctuated after SBE treatment. Compared with the uncrushed leaves, pesticide residues can more easily be removed from crushed leaves, and the practical extraction efficiency was 97%. These results indicate that SBE is a useful method to efficiently remove the bifenthrin, and as appearance is not relevant in the production process, tea leaves should first be crushed and then extracted in order that residual pesticides are thoroughly removed.

  3. Enhanced Capabilities for Subcritical Experiments (ECSE) Risk Management Plan

    Energy Technology Data Exchange (ETDEWEB)

    Urban, Mary Elizabeth [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Process Modeling and Analysis Group

    2016-05-02

    Risk is a factor, element, constraint, or course of action that introduces an uncertainty of outcome that could impact project objectives. Risk is an inherent part of all activities, whether the activity is simple and small, or large and complex. Risk management is a process that identifies, evaluates, handles, and monitors risks that have the potential to affect project success. The risk management process spans the entire project, from its initiation to its successful completion and closeout, including both technical and programmatic (non-technical) risks. This Risk Management Plan (RMP) defines the process to be used for identifying, evaluating, handling, and monitoring risks as part of the overall management of the Enhanced Capabilities for Subcritical Experiments (ECSE) ‘Project’. Given the changing nature of the project environment, risk management is essentially an ongoing and iterative process, which applies the best efforts of a knowledgeable project staff to a suite of focused and prioritized concerns. The risk management process itself must be continually applied throughout the project life cycle. This document was prepared in accordance with DOE O 413.3B, Program and Project Management for the Acquisition of Capital Assets, its associated guide for risk management DOE G 413.3-7, Risk Management Guide, and LANL ADPM AP-350-204, Risk and Opportunity Management.

  4. The biology of species of Serolis (Crustacea, Isopoda, Flabellifera: reproductive behavior of Serolis polaris Richardson, 1911

    Directory of Open Access Journals (Sweden)

    Plínio Soares Moreira

    1973-01-01

    Full Text Available An account based on observations of the reproductive behavior of Serolis polaris is presented. Correlative additional information obtained from the examination of a large number of preserved specimens is discussed. Both the pre-copulatory behavior, and the copulatory position are described. Pre-adult females show sexual escape behavior. The pair of pereopods II are the only clasping appendages utilized in copulation. They are especially morphologically structured to perform this function. Marks, cuts and sores may be produced on the females by the rubbing movements of the clasping pereopods. Experiments show that when mature, males and females do not ingest food. A full discussion of all these behavioral aspects connected with reproduction is provided.O presente trabalho relata as observações sobre o comportamento reprodutivo de Serolis polaris Richardson, 1911. Informações correlatas adicionais, obtidas pelo exame de grande número de espécies, complementam diversos aspectos relacionados a eventos que ocorrem na época da reprodução. Descreve-se o comportamento pré-copulatório, assim como, a posição de copulação. Fêmeas pré-adultas apresentam comportamento de escape à aproximação inadequada dos machos, em suas tentativas de copulação. O pereopodo II é o apêndice que mantém a fêmea em posição de copulação, daí apresentar modificações morfológicas adaptadas a execução dessa função específica. Cicatrizes e anomalias diversas podem ser produzidas nas fêmeas pela subquela do pereópodo II do macho. Numerosas experiências demonstraram que machos e fêmeas não mais se alimentam ao atingirem a maturação sexual. Finalmente, os diversos aspectos do comportamento reprodutivo são detalhada e amplamente discutidos.

  5. Experimental subcritical facility driven by D-D/D-T neutron generator at BARC, India

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Amar, E-mail: image@barc.gov.in; Roy, Tushar; Kashyap, Yogesh; Ray, Nirmal; Shukla, Mayank; Patel, Tarun; Bajpai, Shefali; Sarkar, P.S.; Bishnoi, Saroj

    2015-05-01

    Highlights: •Experimental subcritical facility BRAHMMA coupled to D-D/D-T neutron generator. •Preliminary results of PNS experiments reported. •Feynman-alpha noise measurements explored with continuous source. -- Abstract: The paper presents design of an experimental subcritical assembly driven by D-D/D-T neutron and preliminary experimental measurements. The system has been developed for investigating the static and dynamic neutronic properties of accelerator driven sub-critical systems. This system is modular in design and it is first in the series of subcritical assemblies being designed. The subcritical core consists of natural uranium fuel with high density polyethylene as moderator and beryllium oxide as reflector. The fuel is embedded in high density polyethylene moderator matrix. Estimated k{sub eff} of the system is ∼0.89. One of the unique features of subcritical core is the use of Beryllium oxide (BeO) as reflector and HDPE as moderator making the assembly a compact modular system. The subcritical core is coupled to Purnima Neutron Generator which works in D-D and D-T mode with both DC and pulsed operation. It has facility for online source strength monitoring using neutron tagging and programmable source modulation. Preliminary experiments have been carried out for spatial flux measurement and reactivity estimation using pulsed neutron source (PNS) techniques with D-D neutrons. Further experiments are being planned to measure the reactivity and other kinetic parameters using noise methods. This facility would also be used for carrying out studies on effect of source importance and measurement of source multiplication factor k{sub s} and external neutron source efficiency φ{sup ∗} in great details. Experiments with D-T neutrons are also underway.

  6. Energy surveys of army central heating and power plants, Energy Engineering Analysis Program (EEAP), Fort Richardson. Volume 1 - executive summary

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1986-04-01

    The purpose of this study is to review and study all potential energy conservation opportunities (ECOs) at the Fort Richardson Central Heating and Power Plant (CHPP). These ECOs would then be developed to determine the economies and feasibility of implementation. The equipment at this plant is over 30 years old. The CHPP is meeting the requirements of providing electrical power generation steam for heating the base. It is a functional operating plant that will, with proper maintenance and repairs, continue to perform for many more years. With a CHPP of this age there was reason to believe that many energy conservation opportunities do exist.

  7. High power ring methods and accelerator driven subcritical reactor application

    Energy Technology Data Exchange (ETDEWEB)

    Tahar, Malek Haj [Univ. of Grenoble (France)

    2016-08-07

    High power proton accelerators allow providing, by spallation reaction, the neutron fluxes necessary in the synthesis of fissile material, starting from Uranium 238 or Thorium 232. This is the basis of the concept of sub-critical operation of a reactor, for energy production or nuclear waste transmutation, with the objective of achieving cleaner, safer and more efficient process than today’s technologies allow. Designing, building and operating a proton accelerator in the 500-1000 MeV energy range, CW regime, MW power class still remains a challenge nowadays. There is a limited number of installations at present achieving beam characteristics in that class, e.g., PSI in Villigen, 590 MeV CW beam from a cyclotron, SNS in Oakland, 1 GeV pulsed beam from a linear accelerator, in addition to projects as the ESS in Europe, a 5 MW beam from a linear accelerator. Furthermore, coupling an accelerator to a sub-critical nuclear reactor is a challenging proposition: some of the key issues/requirements are the design of a spallation target to withstand high power densities as well as ensure the safety of the installation. These two domains are the grounds of the PhD work: the focus is on the high power ring methods in the frame of the KURRI FFAG collaboration in Japan: upgrade of the installation towards high intensity is crucial to demonstrate the high beam power capability of FFAG. Thus, modeling of the beam dynamics and benchmarking of different codes was undertaken to validate the simulation results. Experimental results revealed some major losses that need to be understood and eventually overcome. By developing analytical models that account for the field defects, one identified major sources of imperfection in the design of scaling FFAG that explain the important tune variations resulting in the crossing of several betatron resonances. A new formula is derived to compute the tunes and properties established that characterize the effect of the field imperfections on the

  8. Solubility of Benzo[a]pyrene and Organic Matter of Soil in Subcritical Water

    Directory of Open Access Journals (Sweden)

    Svetlana Sushkova

    2015-12-01

    Full Text Available A dynamic subcritical water extraction method of benzo[a]pyrene from soils is under consideration. The optimum conditions for benzo[a]pyrene extraction from soil are described including the soil treatment by subcritical water at 250 °C and 100 atm for 30 min. The effectiveness of developed method was determined using the matrix spiking recovery technique. A comparative analysis was made to evaluate the results of benzo[a]pyrene extraction from soils using the subcritical water and organic solvents. The advantages of the subcritical water extraction involve the use of ecologically friendly solvent, a shorter time for the analysis and a higher amount of benzo[a]pyrene extracted from soil (96 %. The influence of subcritical water extraction on soil properties was measured the investigation of the processes occurring within soil under the influence the high temperature and pressure. Under appropriate conditions of the experiment there is the destruction of the soil organic matter while the composition of the soil mineral fraction remains practically unchanged.

  9. Subcritical water extraction of flavoring and phenolic compounds from cinnamon bark (Cinnamomum zeylanicum).

    Science.gov (United States)

    Khuwijitjaru, Pramote; Sayputikasikorn, Nucha; Samuhasaneetoo, Suched; Penroj, Parinda; Siriwongwilaichat, Prasong; Adachi, Shuji

    2012-01-01

    Cinnamon bark (Cinnamomum zeylanicum) powder was treated with subcritical water at 150 and 200°C in a semi-continuous system at a constant flow rate (3 mL/min) and pressure (6 MPa). Major flavoring compounds, i.e., cinnamaldehyde, cinnamic acid, cinnamyl alcohol and coumarin, were extracted at lower recoveries than the extraction using methanol, suggesting that degradation of these components might occur during the subcritical water treatment. Caffeic, ferulic, p-coumaric, protocatechuic and vanillic acids were identified from the subcritical water treatment. Extraction using subcritical water was more effective to obtain these acids than methanol (50% v/v) in both number of components and recovery, especially at 200°C. Subcritical water treatment at 200°C also resulted in a higher total phenolic content and DPPH radical scavenging activity than the methanol extraction. The DPPH radical scavenging activity and total phenolic content linearly correlated but the results suggested that the extraction at 200°C might result in other products that possessed a free radical scavenging activity other than the phenolic compounds.

  10. Effect of water on critical and subcritical fracture properties of Woodford shale

    Science.gov (United States)

    Chen, Xiaofeng; Eichhubl, Peter; Olson, Jon E.

    2017-04-01

    Subcritical fracture behavior of shales under aqueous conditions is poorly characterized despite increased relevance to oil and gas resource development and seal integrity in waste disposal and subsurface carbon sequestration. We measured subcritical fracture properties of Woodford shale in ambient air, dry CO2 gas, and deionized water by using the double-torsion method. Compared to tests in ambient air, the presence of water reduces fracture toughness by 50%, subcritical index by 77%, and shear modulus by 27% and increases inelastic deformation. Comparison between test specimens coated with a hydrophobic agent and uncoated specimens demonstrates that the interaction of water with the bulk rock results in the reduction of fracture toughness and enhanced plastic effects, while water-rock interaction limited to the vicinity of the propagating fracture tip by a hydrophobic specimen coating lowers subcritical index and increases fracture velocity. The observed deviation of a rate-dependent subcritical index from the power law K-V relations for coated specimens tested in water is attributed to a time-dependent weakening process resulting from the interaction between water and clays in the vicinity of the fracture tip.

  11. Concept of turbines for ultrasupercritical, supercritical, and subcritical steam conditions

    Science.gov (United States)

    Mikhailov, V. E.; Khomenok, L. A.; Pichugin, I. I.; Kovalev, I. A.; Bozhko, V. V.; Vladimirskii, O. A.; Zaitsev, I. V.; Kachuriner, Yu. Ya.; Nosovitskii, I. A.; Orlik, V. G.

    2017-11-01

    The article describes the design features of condensing turbines for ultrasupercritical initial steam conditions (USSC) and large-capacity cogeneration turbines for super- and subcritical steam conditions having increased steam extractions for district heating purposes. For improving the efficiency and reliability indicators of USSC turbines, it is proposed to use forced cooling of the head high-temperature thermally stressed parts of the high- and intermediate-pressure rotors, reaction-type blades of the high-pressure cylinder (HPC) and at least the first stages of the intermediate-pressure cylinder (IPC), the double-wall HPC casing with narrow flanges of its horizontal joints, a rigid HPC rotor, an extended system of regenerative steam extractions without using extractions from the HPC flow path, and the low-pressure cylinder's inner casing moving in accordance with the IPC thermal expansions. For cogeneration turbines, it is proposed to shift the upper district heating extraction (or its significant part) to the feedwater pump turbine, which will make it possible to improve the turbine plant efficiency and arrange both district heating extractions in the IPC. In addition, in the case of using a disengaging coupling or precision conical bolts in the coupling, this solution will make it possible to disconnect the LPC in shifting the turbine to operate in the cogeneration mode. The article points out the need to intensify turbine development efforts with the use of modern methods for improving their efficiency and reliability involving, in particular, the use of relatively short 3D blades, last stages fitted with longer rotor blades, evaporation techniques for removing moisture in the last-stage diaphragm, and LPC rotor blades with radial grooves on their leading edges.

  12. Characterization of the Subcritical Water Extraction of Fluoxetine-Hydrochloride.

    Science.gov (United States)

    Murakami, Jillian N; Thurbide, Kevin B; Lambertus, Gordon; Jensen, Eric

    2012-08-10

    The characteristics of using Subcritical Water Extraction (SWE) to recover Fluoxetine-Hydrochloride from both standard solutions and the contents of commercial capsule formulations were investigated. Analysis of solutions and extracts was done by HPLC with UV detection at 254 nm. Standard solutions of Fluoxetine-Hydrochloride were exposed to a variety of SWE operating conditions, including temperatures from 125 to 275°C and periods ranging from 5 to 30 min. Fluoxetine-Hydrochloride could be quantitatively recovered from standard solutions (1.0mg/mL) that were heated up to 175°C for 30 min, up to 200°C for 15 min, or up to 225°C for 10 min. At higher temperatures and/or times, Fluoxetine-Hydrochloride recoveries were generally incomplete and often produced decomposition by-products during the process. By comparison, the concentration of Fluoxetine-Hydrochloride in the standard solution had relatively little effect on recovery. Considering these parameters, an SWE method was developed to extract Fluoxetine-Hydrochloride from the contents of Prozac(®) capsules. It was found that Fluoxetine-Hydrochloride could be quantitatively extracted from the capsule contents in 8 min at a temperature of 200°C using 3.5 mL of water as the extraction solvent. Gelatinization of the starch excipient in the capsule contents was also observed to occur temporarily during the capsule extractions, before ultimately disappearing again. The period of this phenomenon was dependent on both temperature and sample size. The results indicate that SWE can be a very useful method for Fluoxetine-Hydrochloride extraction and suggest that it may be interesting to explore other pharmaceuticals using this method as well. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Growth and Reproduction of Female Brushtooth Lizardfish Saurida undosquamis (Richardson from the Gulf of Suez, Egypt.

    Directory of Open Access Journals (Sweden)

    Magdy M. El-Halfawy

    2015-12-01

    Full Text Available Süveyş Körfezi’nde (Mısır lokum balığı Saurida undosquamis (Richardson dişi bireylerinin büyüme ve üremesi. Ekim 2004’ten Mayıs 2005’e kadar Süveyş Körfezinden trol ile yakalanan ve Attaka balıkçı limanından çıkarılan 434 Lokum balığının (Saurida undosquamis ilk olgunluk boyu, yumurtlama dönemi, büyüme parametreleri ve yaş kompozisyonu ele alındı. Dişilerin total uzunluğu 13.2 ile 34 cm arasında değişim göstermiştir. Boy (L-Ağırlık (W arasındaki ilişki W=0.0038 L3.1666 olarak tespit edildi. FISAT programı ile analizi yapılan boy frekanslarından elde edilen yaş verileri von Bertalanffy denkleminin (1938 büyüme parametrelerinin tahmininde kullanıldı. Tahmin edilen parametreler L∞=35.56cm, K=0.26 ve t=-1.059 idi. Saurida undosquamis dişileri için maksimum yaş 6 olarak tespit edilmiştir. Yakalananlar içinde 3 yaş grubu dominant olarak gözlenmiştir. Ovaryum, gonadosomatik indeks ve oosit çapının makroskobik görüntülerinden Saurida undosquamis’in yumurtlama mevsiminin Aralık ve Mayıs’ta iki dönemlik artış göstermesiyle birlikte tüm yıl boyunca sürdüğü anlaşıldı. Gonadların, bakir, olgun bakir, gelişmekte olan, gelişmiş, yumurtlayan ve yumurtalarını dökmüş gibi dış görünüşe dayanan yedi aşaması belirlendi. Dişilerin 18.1cm’lik total boyda olgunluğa ulaşmığı tespit edilmiştir. Total, doğal ve avcılıktan kaynaklanan ölümlerinin yıllık değerleri sırasıyla 1.22, 0.99 ve 0.23 yıl-1 olarak hesaplandı. Tüketim oranı (E 0.81 olarak tahmin edildi. Her toplamadaki ilgili verim ve biomas analizleri Süveyş körfezindeki Saurida undosquamis dişi stoklarının tüketilmiş oldugu bulunmuştur. Bireylerin en azından %50’sinin toplanma ve yumurtlatma için korunmasını garantilemek amacıyla, şu anki kullanım oranının yaklaşık %53.1’e kadar azaltılması gerekmektedir

  14. The song remains the same: Juvenile Richardson's ground squirrels do not respond differentially to mother's or colony member's alarm calls

    Directory of Open Access Journals (Sweden)

    James F. HARE, Kurtis J. WARKENTIN

    2012-10-01

    Full Text Available Alarm calls are emitted by Richardson's ground squirrels Urocitellus richardsonii in response to avian and terrestrial predators. Conspecifics detecting these calls respond with increased vigilance, promoting predator detection and evasion, but in doing so, lose time from foraging. That loss can be minimized if alarm call recipients discriminate among signalers, and weight their response accordingly. For juvenile ground squirrels, we predicted that the trade-off between foraging and vigilance could be optimized via selective response to alarm calls emitted by their own dam, and/or neighboring colony members over calls broadcast by less familiar conspecifics. Alarm calls of adult female Richardson's ground squirrels were elicited in the field using a predator model and recorded on digital audio tape. Free-living focal juveniles were subjected to playbacks of a call of their mother, and on a separate occasion a call from either another adult female from their own colony, or an adult female from another colony. Neither immediate postural responses and escape behavior, nor the duration of vigilance manifested by juveniles differed with exposure to alarm calls of the three adult female signaler types. Thus, juveniles did not respond preferentially to alarm calls emitted by their mothers or colony members, likely reflecting the high cost of ignoring alarm signals where receivers have had limited opportunity to establish past signaler reliability [Current Zoology 58 (5: 773–780, 2012].

  15. Subcritical measurements of the WINCO slab tank experiment using the source-jerk technique

    Energy Technology Data Exchange (ETDEWEB)

    Spriggs, G.D.; Hansen, G.E.; Martin, E.R.; Plassmann, E.A.; Pederson, R.A.; Schlesser, J.A.; Krawczyk, T.L.; Tanner, J.E.; Smolen, G.R. (Los Alamos National Lab., NM (USA); Martin Marietta Energy Systems, Inc., Oak Ridge, TN (USA); Westinghouse Idaho Nuclear Co., Inc., Idaho Falls, ID (USA); Martin Marietta Energy Systems, Inc., Oak Ridge, TN (USA))

    1989-01-01

    Subcritical measurements of the WINCO slab tank using the source-jerk technique are presented. This technique determines subcriticality by analyzing the transient response produced by the sudden removal of an extraneous neutron source (i.e., a source jerk). We have found that the technique can provide an accurate means of measuring k in configurations that are close to critical (i.e., 0.90 < k < 1.0). As the system becomes more subcritical (i.e., k < 0.90), spatial effects introduce significant biases depending on the source and detector positions. A comparison between the measurements and Monte Carlo code calculations is also presented. 15 refs., 6 figs., 2 tabs.

  16. Subcritical calculation of the nuclear material warehouse;Calculo de subcriticidad del almacen del material nuclear

    Energy Technology Data Exchange (ETDEWEB)

    Garcia M, T.; Mazon R, R., E-mail: teodoro.garcia@inin.gob.m [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2009-07-01

    In this work the subcritical calculation of the nuclear material warehouse of the Reactor TRIGA Mark III labyrinth in the Mexico Nuclear Center is presented. During the adaptation of the nuclear warehouse (vault I), the fuel was temporarily changed to the warehouse (vault II) and it was also carried out the subcritical calculation for this temporary arrangement. The code used for the calculation of the effective multiplication factor, it was the Monte Carlo N-Particle Extended code known as MCNPX, developed by the National Laboratory of Los Alamos, for the particles transport. (Author)

  17. Subcritical water extraction of amino acids from Mars analog soils.

    Science.gov (United States)

    Noell, Aaron C; Fisher, Anita M; Fors-Francis, Kisa; Sherrit, Stewart

    2018-01-18

    For decades, the Martian regolith has stymied robotic mission efforts to catalog the organic molecules present. Perchlorate salts, found widely throughout Mars, are the main culprit as they breakdown and react with organics liberated from the regolith during pyrolysis, the primary extraction technique attempted to date on Mars. This work further develops subcritical water extraction (SCWE) as a technique for extraction of amino acids on future missions. The effect of SCWE temperature (185, 200, and 215°C) and duration of extraction (10-120 min) on the total amount and distribution of amino acids recovered was explored for three Mars analog soils (JSC Mars-1A simulant, an Atacama desert soil, and an Antarctic Dry Valleys soil) and bovine serum albumin (as a control solution of known amino acid content). Total amounts of amino acids extracted increased with both time and temperature; however, the distribution shifted notably due to the destruction of the amino acids with charged or polar side chains at the higher temperatures. The pure bovine serum albumin solution and JSC Mars 1A also showed lower yields than the Atacama and Antarctic extractions suggesting that SCWE may be less effective at hydrolyzing large or aggregated proteins. Changing solvent from water to a dilute (10 mM) HCl solution allowed total extraction efficiencies comparable to the higher temperature/time combinations while using the lowest temperature/time (185°C/20 min). The dilute HCl extractions also did not lead to the shift in amino acid distribution observed at the higher temperatures. Additionally, adding sodium perchlorate salt to the extraction did not interfere with recoveries. Native magnetite in the JSC Mars-1A may have been responsible for destruction of glycine, as evidenced by its uncharacteristic decrease as the temperature/time of extraction increased. This work shows that SCWE can extract high yields of native amino acids out of Mars analog soils with minimal disruption of the

  18. La musicalisation de Pilgrimage de Dorothy Richardson: l’emprunt de la forme musicale, le récit et le temps

    Directory of Open Access Journals (Sweden)

    Ivana Trajanoska

    2016-05-01

    Full Text Available Hormis dans quelques articles occasionnels, le grand potentiel d’une recherche musico-littéraire du roman Pilgrimage de Dorothy Richardson reste encore peu exploré. Dans ce sens, cet article tente de dévoiler le lien fondamental entre la musique et ce roman moderniste. En s’appuyant sur Barthes, Huxley, Prieto, nous cernons la musicalisation du roman que Richardson met en avant. Nous recherchons la possibilité d’un emprunt de forme musicale comme modèle narratif, la nature et le but de cette expérimentation moderniste. En outre, nous examinons ce que la musicalisation de Pilgrimage apporte à ce récit, comment elle l’enrichit et l’approfondit, et la façon dont elle a permis à Richardson d’exprimer son avis sur la structure, le contenu du roman et sur la représentation du temps. Apart from occasional contributions, the great potential of a musico-literary research on Pilgrimage by Dorothy Richardson remains underexplored. In this perspective, the present article aims at revealing the fundamental link between music and the writing of Richardson’s modernist novel. Building upon Barthes, Huxley, Prieto critical statements, the article outlines how Richardson achieves the musicalisation of fiction in her novel. The possibility of borrowing a musical form as a narrative model, as well as the nature and the purpose of such modernist experimentation, will be explored. Furthermore, the article scrutinises the effect of the muscalisation of Pilgrimage on its narrative form, how it enriched and deepened the novel, and helped Richardson express her opinions on the structure and content of the novel and its strategies of representation of time.

  19. Correlations and non-local transport in a critical-gradient fluctuation model

    Science.gov (United States)

    Nicolau, J. H.; García, L.; Carreras, B. A.

    2016-11-01

    A one-dimensional model based on critical-gradient fluctuation dynamics is used to study turbulent transport in magnetically confined plasmas. The model exhibits the selforganized criticality (SOC) dynamics. At the steady state, two regions are found: the outer one is close to critical state and the inner one remaining at the subcritical gradient. The gradient- flux relation exhibits a parabola-like profile centered in the most probable gradient following experimental studies. This is a signature of the non-locality of particle transport driven by avalanches: at the given position transport is due to gradients situated into closer but different positions. The R/S analysis, applied to the fluxes dynamics reveals memory and correlation. Different H exponents corresponding to different dynamical behavior are obtained. The flux at the edge exhibits long time correlations, which can be suppressed if the external drive or the system size is modified. On the other hand, we found that in the sub-critical region the quasiperiodicity is present in the avalanches.

  20. Nonlinear dynamics aspects of subcritical transitions and singular flows in viscoelastic fluids

    NARCIS (Netherlands)

    Becherer, Paul

    2008-01-01

    Recently, there has been a renewed interest in theoretical aspects of flows of viscoelastic fluids (such as dilute polymer solutions). This thesis addresses two distinct issues related to such flows. Motivated by the possible occurrence of subcritical (finite-amplitude) instabilities in parallel

  1. Subcritical water - a perspective reaction media for biomass processing to chemicals

    OpenAIRE

    Pavlovič, Irena; Škerget, Mojca; Knez, Željko

    2015-01-01

    Biomass and water are recognized as a key renewable feedstock in sustainable production of chemicals, fuels and energy. Subcritical water (SubCW), or commonly referred as hot compressed water (HCW), is the water above boiling and below critical point (CP

  2. LAVENDER: A steady-state core analysis code for design studies of accelerator driven subcritical reactors

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Shengcheng; Wu, Hongchun; Cao, Liangzhi; Zheng, Youqi, E-mail: yqzheng@mail.xjtu.edu.cn; Huang, Kai; He, Mingtao; Li, Xunzhao

    2014-10-15

    Highlights: • A new code system for design studies of accelerator driven subcritical reactors (ADSRs) is developed. • S{sub N} transport solver in triangular-z meshes, fine deletion analysis and multi-channel thermal-hydraulics analysis are coupled in the code. • Numerical results indicate that the code is reliable and efficient for design studies of ADSRs. - Abstract: Accelerator driven subcritical reactors (ADSRs) have been proposed and widely investigated for the transmutation of transuranics (TRUs). ADSRs have several special characteristics, such as the subcritical core driven by spallation neutrons, anisotropic neutron flux distribution and complex geometry etc. These bring up requirements for development or extension of analysis codes to perform design studies. A code system named LAVENDER has been developed in this paper. It couples the modules for spallation target simulation and subcritical core analysis. The neutron transport-depletion calculation scheme is used based on the homogenized cross section from assembly calculations. A three-dimensional S{sub N} nodal transport code based on triangular-z meshes is employed and a multi-channel thermal-hydraulics analysis model is integrated. In the depletion calculation, the evolution of isotopic composition in the core is evaluated using the transmutation trajectory analysis algorithm (TTA) and fine depletion chains. The new code is verified by several benchmarks and code-to-code comparisons. Numerical results indicate that LAVENDER is reliable and efficient to be applied for the steady-state analysis and reactor core design of ADSRs.

  3. Promotion or suppression of glucose isomerization in subcritical aqueous straight- and branched-chain alcohols.

    Science.gov (United States)

    Gao, Da-Ming; Kobayashi, Takashi; Adachi, Shuji

    2015-01-01

    The influence of water-miscible alcohols (methanol, 1-propanol, 2-propanol, and t-butyl alcohol) on the isomerization of glucose to fructose and mannose was investigated under subcritical aqueous conditions (180-200 °C). Primary and secondary alcohols promoted the conversion and isomerization of glucose to afford fructose and mannose with high and low selectivity, respectively. On the other hand, the decomposition (side-reaction) of glucose was suppressed in the presence of the primary and secondary alcohols compared with that in subcritical water. The yield of fructose increased with increasing concentration of the primary and secondary alcohols, and the species of the primary and secondary alcohols tested had little effect on the isomerization behavior of glucose. In contrast, the isomerization of glucose was suppressed in subcritical aqueous t-butyl alcohol. Both the conversion of glucose and the yield of fructose decreased with increasing concentration of t-butyl alcohol. In addition, mannose was not detected in reactions using subcritical aqueous t-butyl alcohol.

  4. Subcritical localization in the discrete nonlinear Schrödinger equation with arbitrary power nonlinearity

    DEFF Research Database (Denmark)

    Bang, O.; Juul Rasmussen, J.; Christiansen, P.L.

    1994-01-01

    Discretizing the continuous nonlinear Schrodinger equation with arbitrary power nonlinearity influences the time evolution of its ground state solitary solution. In the subcritical case, for grid resolutions above a certain transition value, depending on the degree of nonlinearity, the solution w...

  5. Subcritical crack growth behavior of AI2O3-Glass dental composites

    NARCIS (Netherlands)

    Zhu, Q.; With, G. de; Dortmans, L.J.M.G.; Feenstra, F.

    2003-01-01

    The purpose of this study is to investigate the subcritical crack growth (SCG) behavior of alumina-glass dental composites. Alumina-glass composites were fabricated by infiltrating molten glass to porous alumina preforms. Rectangular bars of the composite were subject to dynamic loading in air, with

  6. Effects of Canals and Roads on Hydrologic Conditions and Health of Atlantic White Cedar at Emily and Richardson Preyer Buckridge Coastal Reserve, North Carolina, 2003-2006

    Science.gov (United States)

    Ferrell, Gloria M.; Strickland, A. Gerald; Spruill, Timothy B.

    2007-01-01

    The effects of canals and roads on hydrologic conditions and on the health of Atlantic white cedar at the Emily and Richardson Preyer Buckridge Coastal Reserve in North Carolina were evaluated by using data collected from the 1980s to 2006. Water levels were monitored along two transects established perpendicular to roads and canals in areas of healthy and unhealthy Atlantic white cedar as part of a study conducted from February 2003 through March 2006. Because of the low hydraulic gradient at the Reserve, the rate and direction of water movement are sensitive to disturbance. Canals increased drainage and contributed to lower water levels in some parts of the Reserve, whereas roads, depending on orientation, impeded drainage. Canals also appeared to facilitate movement of brackish water from the Alligator River into the interior of the Reserve during storms and wind tides. Data indicate that an influx of brackish water occurred in mid-September 2005 several days after the passage of Hurricane Ophelia. Although precipitation amounts and wind speeds associated with Hurricane Ophelia were not large, substantial changes in specific conductance occurred at the canal site on the unhealthy Atlantic white cedar transect. No corresponding increase in specific conductance was observed at the canal site on the healthy Atlantic white cedar transect. The specific conductance of water samples from canals and piezometers was highly correlated with concentrations of chloride and sodium. Ion ratios of some of the water samples, particularly samples with high specific conductance, were similar to those of seawater. Thermal and chemical stratification of water in the canals occurred during summer and winter months, and turnover and mixing occurred in the spring and fall. Upwelling of ground water as a result of excavation for roads did not appear to have a significant effect on the water quality of samples from the canals or piezometers. The specific conductance of water samples from

  7. Comparative evaluation of the modified Scarff-Bloom-Richardson grading system on breast carcinoma aspirates and histopathology

    Directory of Open Access Journals (Sweden)

    Cherry Bansal

    2012-01-01

    Full Text Available Background: Fine needle aspiration (FNA is a quick, minimally invasive procedure for evaluation of breast tumors. The Scarff-Bloom-Richardson (SBR grade on histological sections is a well-established tool to guide selection of adjuvant systemic therapy. Grade evaluation is possible on cytology smears to avoid and minimize the morbidity associated with overtreatment of lower grade tumors. Aim : The aim was to test the hypothesis whether breast FNA from the peripheral portion of the lesion is representative of Scarff-Bloom-Richardson grade on histopathology as compared to FNA from the central portion. Materials and Methods : Fine-needle aspirates and subsequent tissue specimens from 45 women with ductal carcinoma (not otherwise specified were studied. FNAs were performed under ultrasound guidance from the central as well as the peripheral third of the lesion for each case avoiding areas of necrosis/calcification. The SBR grading was compared on alcohol fixed aspirates and tissue sections for each case. Results : Comparative analysis of SBR grade on aspirates from the peripheral portion and histopathology by the Pearson chi-square test (χ2 =78.00 showed that it was statistically significant (P<0.001 with 93% concordance. Lower mitotic score on aspirates from the peripheral portion was observed in only 4 out of 45 (9% cases. The results of the Pearson chi-square test (χ2 = 75.824 with statistically significant (P=0.000. Conclusion : This prospective study shows that FNA smears from the peripheral portion of the lesion are representative of the grading performed on the corresponding histopathological sections. It is possible to score and grade by SBR system on FNA smears.

  8. Plutonium Critical Mass Curve Comparison to Mass at Upper Subcritical Limit (USL) Using Whisper

    Energy Technology Data Exchange (ETDEWEB)

    Alwin, Jennifer Louise [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Monte Carlo Codes; Zhang, Ning [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Nuclear Criticality Safety Division

    2016-09-27

    Whisper is computational software designed to assist the nuclear criticality safety analyst with validation studies with the MCNP® Monte Carlo radiation transport package. Standard approaches to validation rely on the selection of benchmarks based upon expert judgment. Whisper uses sensitivity/uncertainty (S/U) methods to select relevant benchmarks to a particular application or set of applications being analyzed. Using these benchmarks, Whisper computes a calculational margin. Whisper attempts to quantify the margin of subcriticality (MOS) from errors in software and uncertainties in nuclear data. The combination of the Whisper-derived calculational margin and MOS comprise the baseline upper subcritical limit (USL), to which an additional margin may be applied by the nuclear criticality safety analyst as appropriate to ensure subcriticality. A series of critical mass curves for plutonium, similar to those found in Figure 31 of LA-10860-MS, have been generated using MCNP6.1.1 and the iterative parameter study software, WORM_Solver. The baseline USL for each of the data points of the curves was then computed using Whisper 1.1. The USL was then used to determine the equivalent mass for plutonium metal-water system. ANSI/ANS-8.1 states that it is acceptable to use handbook data, such as the data directly from the LA-10860-MS, as it is already considered validated (Section 4.3 4) “Use of subcritical limit data provided in ANSI/ANS standards or accepted reference publications does not require further validation.”). This paper attempts to take a novel approach to visualize traditional critical mass curves and allows comparison with the amount of mass for which the keff is equal to the USL (calculational margin + margin of subcriticality). However, the intent is to plot the critical mass data along with USL, not to suggest that already accepted handbook data should have new and more rigorous requirements for validation.

  9. The thermohaline, Richardson, Rayleigh-Taylor, Solberg-Høiland, and GSF criteria in rotating stars

    Science.gov (United States)

    Maeder, A.; Meynet, G.; Lagarde, N.; Charbonnel, C.

    2013-05-01

    Aims: We examine the interactions of various instabilities in rotating stars, which usually are considered as independent. Methods: An analytical study of the problem is performed accounting for radiative losses, μ-gradients, and horizontal turbulence. Results: The diffusion coefficient for an ensemble of instabilities is not given by the sum of the specific coefficients for each instability, but by the solution of a general equation. We find that thermohaline mixing is possible in low-mass red giants only if the horizontal turbulence is very weak. In rotating stars the Rayleigh-Taylor and the shear instabilities need simultaneous treating. This leads to rotation laws of the form 1/rα being predicted to be unstable for α > 1.6568, while the usual Rayleigh criterion only predicts instability for α > 2. Also, the shear instabilities are somehow reduced in main sequence stars by the effect of the Rayleigh-Taylor criterion. Various instability criteria should be expressed differently in rotating stars than in simplified geometries.

  10. A vibrating membrane bioreactor operated at supra- and sub-critical flux: Influence of extracellular polymeric substances from yeast cells

    DEFF Research Database (Denmark)

    Beier, Søren Prip; Jonsson, Gunnar Eigil

    2007-01-01

    A vibrating membrane bioreactor, in which the fouling problems are reduced by vibrating a hollow fiber membrane module, has been tested in constant flux microfiltration above (supra-critical) and below (sub-critical) an experimentally determined critical flux. Suspensions of bakers yeast cells were....... Filtration just below the critical flux (sub-critical) seems to be a good compromise between acceptable flux level and acceptable increase of fouling resistance and trans-membrane pressure (TMP) in a given time period. EPS from the yeast cells causes the membrane module to foul and part of the fouling...... is continually washed out during supra-critical flux operation whereas the washing out at sub-critical flux operation is not observed. This might be due to locally different hydrodynamic conditions at the membrane surface and pore entrances at supra- and sub-critical flux respectively....

  11. Subcritical tests - nuclear weapon testing under the Comprehensive Test Ban Treaty; Subkritiske tester - kjernevaapentesting under avtalen om fullstendig proevestans

    Energy Technology Data Exchange (ETDEWEB)

    Hoeibraaten, S

    1998-10-01

    The report discusses possible nuclear weapons related experiments and whether these are permitted under the 1996 Comprehensive Test Ban Treaty (CTBT). The term ''subcritical experiments'' as used in the United States includes experiments in which one studies fissile materials (so far only plutonium) under extreme conditions generated by conventional high explosives, and in which a self-sustained chain reaction never develops in the fissile material. The known facts about the American subcritical experiments are presented. There is very little reason to doubt that these experiments were indeed subcritical and therefore permitted under the CTBT. Little is known about the Russian efforts that are being made on subcritical experiments.

  12. PILOT-SCALE SUBCRITICAL WATER REMEDIATION OF POLYCYCLIC AROMATIC HYDROCARBON- AND PESTICIDE-CONTAMINATED SOIL. (R825394)

    Science.gov (United States)

    Subcritical water (hot water under enough pressure to maintain the liquid state) was used to remove polycyclic aromatic hydrocarbons (PAHs) and pesticides from highly contaminated soils. Laboratory-scale (8 g of soil) experiments were used to determine conditions f...

  13. Research Programme for the 660 Mev Proton Accelerator Driven MOX-Plutonium Subcritical Assembly

    CERN Document Server

    Barashenkov, V S; Buttseva, G L; Dudarev, S Yu; Polanski, A; Puzynin, I V; Sissakian, A N

    2000-01-01

    The paper presents a research programme of the Experimental Acclerator Driven System (ADS), which employs a subcritical assembly and a 660 MeV proton acceletator operating at the Laboratory of Nuclear Problems of the JINR, Dubna. MOX fuel (25% PuO_2 + 75% UO_2) designed for the BN-600 reactor use will be adopted for the core of the assembly. The present conceptual design of the experimental subcritical assembly is based on a core of a nominal unit capacity of 15 kW (thermal). This corresponds to the multiplication coefficient k_eff = 0.945, energetic gain G = 30 and the accelerator beam power 0.5 kW.

  14. Tuning colloidal interactions in subcritical solvents by solvophobicity: explicit versus implicit modeling.

    Science.gov (United States)

    Dzubiella, J; Chakrabarti, J; Löwen, H

    2009-07-28

    The distance-resolved effective interaction between two colloidal particles in a subcritical solvent is explored both by an explicit and implicit modeling. An implicit solvent approach based on a simple thermodynamic interface model is tested against grand-canonical Monte Carlo computer simulations using explicit Lennard-Jones solvent molecules. Close to liquid-gas coexistence, a joint gas bubble surrounding the colloidal particle pair yields an effective attraction between the colloidal particles, the strength of which can be vastly tuned by the solvophobicity of the colloids. The implicit model is in good agreement with our explicit computer simulations, thus enabling an efficient modeling and evaluation of colloidal interactions and self-assembly in subcritical solvent environments.

  15. A fusion-driven subcritical system concept based on viable technologies

    Science.gov (United States)

    Wu, Y.; Jiang, J.; Wang, M.; Jin, M.; FDS Team

    2011-10-01

    A fusion-driven hybrid subcritical system (FDS) concept has been designed and proposed as spent fuel burner based on viable technologies. The plasma fusion driver can be designed based on relatively easily achieved plasma parameters extrapolated from the successful operation of existing fusion experimental devices such as the EAST tokamak in China and other tokamaks in the world, and the subcritical fission blanket can be designed based on the well-developed technologies of fission power plants. The simulation calculations and performance analyses of plasma physics, neutronics, thermal-hydraulics, thermomechanics and safety have shown that the proposed concept can meet the requirements of tritium self-sufficiency and sufficient energy gain as well as effective burning of nuclear waste from fission power plants and efficient breeding of nuclear fuel to feed fission power plants.

  16. Theoretical Analysis for Heat Transfer Optimization in Subcritical Electrothermal Energy Storage Systems

    Directory of Open Access Journals (Sweden)

    Peng Hu

    2017-02-01

    Full Text Available Electrothermal energy storage (ETES provides bulk electricity storage based on heat pump and heat engine technologies. A subcritical ETES is described in this paper. Based on the extremum principle of entransy dissipation, a geometry model is developed for heat transfer optimization for subcritical ETES. The exergy during the heat transfer process is deduced in terms of entropy production. The geometry model is validated by the extremum principle of entropy production. The theoretical analysis results show that the extremum principle of entransy dissipation is an effective criterion for the optimization, and the optimum heat transfer for different cases with the same mass flux or pressure has been discussed. The optimum heat transfer can be achieved by adjusting the mass flux and pressure of the working fluid. It also reveals that with the increase of mass flux, there is a minimum exergy in the range under consideration, and the exergy decreases with the increase of the pressure.

  17. Determination of subcriticality and effective source strength by source drop and jerk experiments

    Energy Technology Data Exchange (ETDEWEB)

    Taninaka, Hiroshi [Interdisciplinary Graduate School of Science and Technology, Kinki University, 3-4-1, Kowakae, Higashi-Osaka, 577-8502 (Japan); Hashimoto, Kengo [Atomic Energy Research Institute, Kinki University, 3-4-1, Kowakae, Higashi-Osaka, 577-8502 (Japan)

    2008-07-01

    This paper presents applicability of least squares inverse kinetics method (LSIKM) to source drop and source jerk experiments. The LSIKM can estimate both reactivity and source strength by applying least square approximation to a correlation between time-sequence count data and inverse kinetics analysis data. The experiments were performed in the UTR-KINKI reactor to demonstrate the applicability of the LSIKM. To source jerk data, for comparison, conventional integral method is also applied. In the subcriticality and source strength obtained by the LSIKM, spatial dependence is slightly observed. However, the integral method leads to significant spatial dependence. The sub-criticalities inferred from source drop data are consistent with the results from source jerk data. (authors)

  18. Influence of moderator to fuel ratio (MFR) on burning thorium in a subcritical assembly

    Energy Technology Data Exchange (ETDEWEB)

    Wojciechowski, Andrzej, E-mail: andrzej.wojciechowski@ncbj.gov.pl [National Center for Nuclear Research, Otwock-Swierk (Poland); Joint Institute for Nuclear Research, Dubna (Russian Federation)

    2014-10-15

    The conversion ratio (CR) of Th-232 to U-233 calculation results for a subcritical reactor assembly is presented as a function of MFR, burnup, power density (PD) and fissile concentration. The calculated model is based on subcritical assembly which makes configuration of fuel rods and volumes of moderator and coolant changes possible. This comfortable assembly enables investigation of CR in a thorium cycle for different value of MFR. Additionally, the calculation results of U-233 saturation concentration are explained by mathematical model. The value of MFR main influences the saturation concentration of U-233 and fissile and the fissile concentration dependence of CR. The saturation value of CR is included in the range CR ∈ (0.911, 0.966) and is a slowly increasing function of MFR. The calculations were done with a MCNPX 2.7 code.

  19. Subcritical ethanol extraction of flavonoids from Moringa oleifera leaf and evaluation of antioxidant activity.

    Science.gov (United States)

    Wang, Yongqiang; Gao, Yujie; Ding, Hui; Liu, Shejiang; Han, Xu; Gui, Jianzhou; Liu, Dan

    2017-03-01

    A large-scale process to extract flavonoids from Moringa oleifera leaf by subcritical ethanol was developed and HPLC-MS analysis was conducted to qualitatively identify the compounds in the extracts. To optimize the effects of process parameters on the yield of flavonoids, a Box-Behnken design combined with response surface methodology was conducted in the present work. The results indicated that the highest extraction yield of flavonoids by subcritical ethanol extraction could reach 2.60% using 70% ethanol at 126.6°C for 2.05h extraction. Under the optimized conditions, flavonoids yield was substantially improved by 26.7% compared with the traditional ethanol reflux method while the extraction time was only 2h, and obvious energy saving was observed. FRAP and DPPH assays showed that the extracts had strong antioxidant and free radical scavenging activities. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Coupling of subcritical methanol with acidic ionic liquids for the acidity reduction of naphthenic acids

    Directory of Open Access Journals (Sweden)

    Zafar Faisal

    2017-09-01

    Full Text Available The presence of naphthenic acids (NAs in crude oil is the major cause of corrosion in the refineries and its processing equipment. The goal of this study is to reduce the total acid number (TAN of NAs by treating them with subcritical methanol in the presence of acidic ionic liquid (AIL catalysts. Experiments were carried out in an autoclave batch reactor and the effect of different reaction parameters was investigated. It was observed that TAN reduction was positively dependent on the temperature and concentration of the AIL whereas excess of methanol has a negative effect. Approximately 90% TAN reduction was achieved under the optimized reaction conditions using [BMIM]HSO4 as catalyst. It was also perceived from the experimental results that the AILs with longer alkyl chain exhibited higher catalytic activity. The activity and stability of AIL showed that they can be promising catalyst to esterify NAs under subcritical methanol.

  1. Enhanced enzymatic cellulose hydrolysis by subcritical carbon dioxide pretreatment of sugarcane bagasse.

    Science.gov (United States)

    Zhang, Hongdan; Wu, Shubin

    2014-04-01

    Most biomass pretreatment processes for sugar production are run at low-solid concentration (carbon dioxide (CO2) could provide a more sustainable pretreatment medium while using relative high-solid contents (15 wt.%). The effects of subcritical CO2 pretreatment of sugarcane bagasse to the solid and glucan recoveries at different pretreatment conditions were investigated. Subsequently, enzymatic hydrolysis at different hydrolysis time was applied to obtain maximal glucose yield, which can be used for ethanol fermentation. The maximum glucose yield in enzyme hydrolyzate reached 38.5 g based on 100g raw material after 72 h of enzymatic hydrolysis, representing 93.0% glucose in sugarcane bagasse. The enhanced digestibilities of subcritical CO2 pretreated sugarcane bagasse were due to the removal of hemicellulose, which were confirmed by XRD, FTIR, SEM, and TGA analyses. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Equilibria of ternary system acetic acid-water-CO2 under subcritical conditions

    DEFF Research Database (Denmark)

    Gutierrez, Jose M. Jimenez; Mussatto, Solange I.; Tsou, Joana

    in a very wide range of applications. However, those conditions, especially the levels of high pressure required at larger scale, involve certain equipment limitations. An alternative to overcome those restrictions is to use subcritical carbon dioxide. In order to understand the different systems......) of the ternary system HAc—H2O—CO2 at different subcritical conditions. A proposed computer model could be validated with experimental data, leading to a certain degree of adjustment due to specific factors, such as the binary interaction parameter kij, used in the model based on the Peng-Robinson EoS coupled...... it will be returned to the atmosphere (as part of the carbon cycle), CO2 is an inexpensive and clean source with numerous industrial applications in diverse fields: from chemical processes to biotechnological purposes [1]. Many of these studies have been focused on supercritical CO2, due to its broad potential uses...

  3. Sub-Critical Closed String Field Theory in D Less Than 26

    OpenAIRE

    Kaku, Michio

    1993-01-01

    We construct the second quantized action for sub-critical closed string field theory with zero cosmological constant in dimensions $ 2 \\leq D < 26$, generalizing the non-polynomial closed string field theory action proposed by the author and the Kyoto and MIT groups for $D = 26$. The proof of gauge invariance is considerably complicated by the presence of the Liouville field $\\phi$ and the non-polynomial nature of the action. However, we explicitly show that the polyhedral vertex functions ob...

  4. Sensitivity Analysis of Core Neutronic Parameters in Electron Accelerator-driven Subcritical Advanced Liquid Metal Reactor

    OpenAIRE

    Ebrahimkhani, Marziye; Hassanzadeh, Mostafa; Feghhi, Sayed Amier Hossian; Masti, Darush

    2016-01-01

    Calculation of the core neutronic parameters is one of the key components in all nuclear reactors. In this research, the energy spectrum and spatial distribution of the neutron flux in a uranium target have been calculated. In addition, sensitivity of the core neutronic parameters in accelerator-driven subcritical advanced liquid metal reactors, such as electron beam energy (Ee) and source multiplication coefficient (ks), has been investigated. A Monte Carlo code (MCNPX_2.6) has been used to ...

  5. Subcritical mineralization of sodium salt of dodecyl benzene sulfonate using sonication-wet oxidation (SONIWO) technique.

    Science.gov (United States)

    Dhale, A D; Mahajani, V V

    2001-06-01

    Subcritical mineralization of sodium salt of dodecyl benzene sulfonate via hybrid process-sonication followed by wet oxidation (SONIWO) has been investigated. Sonication of the compound enhanced the rates and % COD reduction during wet oxidation. In this process, homogenous CuSO4 catalyst was found to be effective. In wet oxidation studies, phenol, hydroquinone, maleic acid, oxalic acid, propionic acid, and acetic acid were identified as intermediates. The global rate equations for wet oxidation in terms of COD reduction were developed.

  6. Observation of subcritical geodesic acoustic mode excitation in the large helical device

    Science.gov (United States)

    Ido, T.; Itoh, K.; Lesur, M.; Osakabe, M.; Shimizu, A.; Ogawa, K.; Nishiura, M.; Yamada, I.; Yasuhara, R.; Kosuga, Y.; Sasaki, M.; Ida, K.; Inagaki, S.; Itoh, S.-I.; the LHD Experiment Group

    2017-07-01

    The abrupt and strong excitation of the geodesic acoustic mode (GAM) has been found in the large helical device (LHD), when the frequency of a chirping energetic particle-driven GAM (EGAM) approaches twice that of the GAM frequency. The temporal evolution of the phase relation between the abrupt GAM and the chirping EGAM is common in all events. The result indicates a coupling between the GAM and the EGAM. In addition, the nonlinear evolution of the growth rate of the GAM is observed, and there is a threshold in the amplitude of the GAM for the appearance of nonlinear behavior. A threshold in the amplitude of the EGAM for the abrupt excitation of the GAM is also observed. According to one theory (Lesur et al 2016 Phys. Rev. Lett. 116 015003, Itoh et al 2016 Plasma Phys. Rep. 42 418) the observed abrupt phenomenon can be interpreted as the excitation of the subcritical instability of the GAM. The excitation of a subcritical instability requires a trigger and a seed with sufficient amplitude. The observed threshold in the amplitude of the GAM seems to correspond with the threshold in the seed, and the threshold in the amplitude of the EGAM seems to correspond with the threshold in the magnitude of the trigger. Thus, the observed threshold supports the interpretation that the abrupt phenomenon is the excitation of a subcritical instability of the GAM.

  7. Efficient decomposition of perchlorate to chloride ions in subcritical water by use of steel slag.

    Science.gov (United States)

    Hori, Hisao; Kamijo, Ayae; Inoue, Miki; Chino, Asako; Wu, Qian; Kannan, Kurunthachalam

    2016-08-03

    Decomposition of perchlorate (ClO4(-)) in subcritical water in the presence of steel slag, a by-product of the steel industry, was investigated. Reactivity of ClO4(-) was low in pure subcritical water state up to 300 °C, whereas adding steel slag efficiently accelerated the decomposition of ClO4(-) to Cl(-), with no leaching of heavy metals such as chromium and other environmentally undesirable elements (boron and fluorine). When the reaction was performed in subcritical water at a relatively low temperature (250 °C) for 6 h, virtually all ClO4(-) ions were removed from the reaction solution. The concentration of Cl(-) after the reaction was well accounted for by the sum of the amount of Cl(-) ascribed to the decomposition of ClO4(-) and the amount of Cl(-) leached from the slag. This method was successfully applied to decompose ClO4(-) in water samples collected from a man-made reflection pond following a fireworks display, even though these samples contained much higher concentrations of Cl(-) and SO4(2-) than ClO4(-).

  8. Neutron Detector Signal Processing to Calculate the Effective Neutron Multiplication Factor of Subcritical Assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Talamo, Alberto [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Gohar, Yousry [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division

    2016-06-01

    This report describes different methodologies to calculate the effective neutron multiplication factor of subcritical assemblies by processing the neutron detector signals using MATLAB scripts. The subcritical assembly can be driven either by a spontaneous fission neutron source (e.g. californium) or by a neutron source generated from the interactions of accelerated particles with target materials. In the latter case, when the particle accelerator operates in a pulsed mode, the signals are typically stored into two files. One file contains the time when neutron reactions occur and the other contains the times when the neutron pulses start. In both files, the time is given by an integer representing the number of time bins since the start of the counting. These signal files are used to construct the neutron count distribution from a single neutron pulse. The built-in functions of MATLAB are used to calculate the effective neutron multiplication factor through the application of the prompt decay fitting or the area method to the neutron count distribution. If the subcritical assembly is driven by a spontaneous fission neutron source, then the effective multiplication factor can be evaluated either using the prompt neutron decay constant obtained from Rossi or Feynman distributions or the Modified Source Multiplication (MSM) method.

  9. Th and U fuel photofission study by NTD for AD-MSR subcritical assembly

    Energy Technology Data Exchange (ETDEWEB)

    Sajo-Bohus, Laszlo; Greaves, Eduardo D.; Barros, Haydn; Pino, Felix; Barrera, Maria T.; Farina, Fulvio [Universidad Simón Bolívar, Nuclear Physics Laboratory, Apdo 89000, Caracas 1080A (Venezuela, Bolivarian Republic of); Davila, Jesus [Física Médica C. A. and Universidad Central de Venezuela, Caracas (Venezuela, Bolivarian Republic of)

    2015-07-23

    During the last decade a considerable effort has been devoted for developing energy generating systems based on advanced nuclear technology within the design concepts of GEN-IV. Thorium base fuel systems such as accelerator driven nuclear reactors are one of the often mentioned attractive and affordable options. Several radiotherapy linear accelerators are on the market and due to their reliability, they could be employed as drivers for subcritical liquid fuel assemblies. Bremsstrahlung photons with energies above 5.5MeV, induce (γ,n) and (e,e’n) reactions in the W-target. Resulting gamma radiation and photo or fission neutrons may be absorbed in target materials such as thorium and uranium isotopes to induce sustained fission or nuclear transmutation in waste radioactive materials. Relevant photo driven and photo-fission reaction cross sections are important for actinides {sup 232}Th, {sup 238}U and {sup 237}Np in the radiotherapy machines energy range of 10-20 MV. In this study we employ passive nuclear track detectors (NTD) to determine fission rates and neutron production rates with the aim to establish the feasibility for gamma and photo-neutron driven subcritical assemblies. To cope with these objectives a 20 MV radiotherapy machine has been employed with a mixed fuel target. Results will support further development for a subcritical assembly employing a thorium containing liquid fuel. It is expected that acquired technological knowledge will contribute to the Venezuelan nuclear energy program.

  10. Universal gradient descent

    OpenAIRE

    Gasnikov, Alexander

    2017-01-01

    In this small book we collect many different and useful facts around gradient descent method. First of all we consider gradient descent with inexact oracle. We build a general model of optimized function that include composite optimization approach, level's methods, proximal methods etc. Then we investigate primal-dual properties of the gradient descent in general model set-up. At the end we generalize method to universal one.

  11. The pattern of verbal, visuospatial and procedural learning in Richardson variant of progressive supranuclear palsy in comparison to Parkinson's disease.

    Science.gov (United States)

    Sitek, Emilia J; Wieczorek, Dariusz; Konkel, Agnieszka; Dąbrowska, Magda; Sławek, Jarosław

    2017-08-29

    Progressive supranuclear palsy (PSP) is regarded either within spectrum of atypical parkinsonian syndromes or frontotemporal lobar degeneration. We compared the verbal, visuospatial and procedural learning profiles in patients with PSP and Parkinson's disease (PD). Furthermore, the relationship between executive factors (initiation and inhibition) and learning outcomes was analyzed. Thirty-three patients with the clinical diagnosis of PSP-Richardson's syndrome (PSP-RS), 39 patients with PD and 29 age -and education -matched controls were administered Mini-Mental State Examination (MMSE), phonemic and semantic fluency tasks, Auditory Verbal Learning Test (AVLT), Visual Learning and Memory Test for Neuropsychological Assessment by Lamberti and Weidlich (Diagnosticum für Cerebralschädigung, DCS), Tower of Toronto (ToT) and two motor sequencing tasks. Patients with PSP-RS and PD were matched in terms of MMSE scores and mood. Performance on DCS was lower in PSP-RS than in PD. AVLT delayed recall was better in PSP-RS than PD. Motor sequencing task did not differentiate between patients. Scores on AVLT correlated positively with phonemic fluency scores in both PSP-RS and PD. ToT rule violation scores were negatively associated with DCS performance in PSP-RS and PD as well as with AVLT performance in PD. Global memory performance is relatively similar in PSP-RS and PD. Executive factors (initiation and inhibition) are closely related to memory performance in PSP-RS and PD. Visuospatial learning impairment in PSP-RS is possibly linked to impulsivity and failure to inhibit automatic responses.

  12. Gradient and vorticity banding

    NARCIS (Netherlands)

    Dhont, Jan K.G.; Briels, Willem J.

    2008-01-01

    "Banded structures" of macroscopic dimensions can be induced by simple shear flow in many different types of soft matter systems. Depending on whether these bands extend along the gradient or vorticity direction, the banding transition is referred to as "gradient banding" or "vorticity banding,"

  13. Richardson WCAP 39

    African Journals Online (AJOL)

    user

    ... energy and protein as a result of drought, high stocking rates, or during the dry season low digestibility and low protein content of the forage (Butterworth, 1984). The growth and milk yield of cattle are reduced during such periods of undernutrition. Growing animals respond in different ways to nutritional restriction because ...

  14. Evaluation of reactivity monitoring techniques at the Yalina - Booster sub-critical facility

    Energy Technology Data Exchange (ETDEWEB)

    Becares Palacios, V.

    2014-07-01

    The management of long-lived radioactive wastes produced by nuclear reactors constitutes one of the main challenges of nuclear technology nowadays. A possible option for its management consists in the transmutation of long lived nuclides into shorter lived ones. Accelerator Driven Subcritical Systems (ADS) are one of the technologies in development to achieve this goal. An ADS consists in a subcritical nuclear reactor maintained in a steady state by an external neutron source driven by a particle accelerator. The interest of these systems lays on its capacity to be loaded with fuels having larger contents of minor actinides than conventional critical reactors, and in this way, increasing the transmutation rates of these elements, that are the main responsible of the long-term radiotoxicity of nuclear waste. One of the key points that have been identified for the operation of an industrial-scale ADS is the need of continuously monitoring the reactivity of the subcritical system during operation. For this reason, since the 1990s a number of experiments have been conducted in zero-power subcritical assemblies (MUSE, RACE, KUCA, Yalina, GUINEVERE/FREYA) in order to experimentally validate these techniques. In this context, the present thesis is concerned with the validation of reactivity monitoring techniques at the Yalina-Booster subcritical assembly. This assembly belongs to the Joint Institute for Power and Nuclear Research (JIPNR-Sosny) of the National Academy of Sciences of Belarus. Experiments concerning reactivity monitoring have been performed in this facility under the EUROTRANS project of the 6th EU Framework Program in year 2008 under the direction of CIEMAT. Two types of experiments have been carried out: experiments with a pulsed neutron source (PNS) and experiments with a continuous source with short interruptions (beam trips). For the case of the first ones, PNS experiments, two fundamental techniques exist to measure the reactivity, known as the prompt

  15. Surface chemistry and corrosion behavior of Inconel 625 and 718 in subcritical, supercritical, and ultrasupercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, David; Merwin, Augustus; Karmiol, Zachary; Chidambaram, Dev, E-mail: dcc@unr.edu

    2017-05-15

    Highlights: • Mixtures of oxides containing Ni, Fe, Cr and Nb formed on the surface. • Short term exposure tests observed breakdown of native film. • Formation of a Fe rich oxide layer on Inconel 718 prevents mass loss. - Abstract: Corrosion behavior of Inconel 625 and 718 in subcritical, supercritical and ultrasupercritical water was studied as a function of temperature and time. The change in the chemistry of the as-received surface film on Inconel 625 and 718 after exposure to subcritical water at 325 °C and supercritical water at 425 °C and 527.5 °C for 2 h was studied. After exposure to 325 °C subcritical water, the CrO{sub 4}{sup 2−} based film formed; however minor quantities of NiFe{sub x}Cr{sub 2-x}O{sub 4} spinel compounds were observed. The oxide film formed on both alloys when exposed to supercritical water at 425 °C consisted of NiFe{sub x}Cr{sub 2-x}O{sub 4} spinel. The surface films on both alloys were identified as NiFe{sub 2}O{sub 4} when exposed to supercritical water at 527.5 °C. To characterize the fully developed oxide layer, studies were conducted at test solution temperatures of 527.5 and 600 °C. Samples were exposed to these temperatures for 24, 96, and 200 h. Surface chemistry was analyzed using X-ray diffraction, as well as Raman and X-ray photoelectron spectroscopies. Inconel 718 exhibited greater mass gain than Inconel 625 for all temperatures and exposure times. The differences in corrosion behavior of the two alloys are attributed to the lower content of chromium and increased iron content of Inconel 718 as compared to Inconel 625.

  16. Surface chemistry and corrosion behavior of Inconel 625 and 718 in subcritical, supercritical, and ultrasupercritical water

    Science.gov (United States)

    Rodriguez, David; Merwin, Augustus; Karmiol, Zachary; Chidambaram, Dev

    2017-05-01

    Corrosion behavior of Inconel 625 and 718 in subcritical, supercritical and ultrasupercritical water was studied as a function of temperature and time. The change in the chemistry of the as-received surface film on Inconel 625 and 718 after exposure to subcritical water at 325 °C and supercritical water at 425 °C and 527.5 °C for 2 h was studied. After exposure to 325 °C subcritical water, the CrO42- based film formed; however minor quantities of NiFexCr2-xO4 spinel compounds were observed. The oxide film formed on both alloys when exposed to supercritical water at 425 °C consisted of NiFexCr2-xO4 spinel. The surface films on both alloys were identified as NiFe2O4 when exposed to supercritical water at 527.5 °C. To characterize the fully developed oxide layer, studies were conducted at test solution temperatures of 527.5 and 600 °C. Samples were exposed to these temperatures for 24, 96, and 200 h. Surface chemistry was analyzed using X-ray diffraction, as well as Raman and X-ray photoelectron spectroscopies. Inconel 718 exhibited greater mass gain than Inconel 625 for all temperatures and exposure times. The differences in corrosion behavior of the two alloys are attributed to the lower content of chromium and increased iron content of Inconel 718 as compared to Inconel 625.

  17. Odd-number theorem: Optical feedback control at a subcritical Hopf bifurcation in a semiconductor laser

    Science.gov (United States)

    Schikora, S.; Wünsche, H.-J.; Henneberger, F.

    2011-02-01

    A subcritical Hopf bifurcation is prepared in a multisection semiconductor laser. In the free-running state, hysteresis is absent due to noise-induced escape processes. The missing branches are recovered by stabilizing them against noise through application of phase-sensitive noninvasive delayed optical feedback control. The same type of control is successfully used to stabilize the unstable pulsations born in the Hopf bifurcation. This experimental finding represents an optical counterexample to the so-called odd-number limitation of delayed feedback control. However, as a leftover of the limitation, the domains of control are extremely small.

  18. Numerical simulations of flow field in the target region of accelerator-driven subcritical reactor system

    CERN Document Server

    Chen Hai Yan

    2002-01-01

    Numerical simulations of flow field were performed by using the PHOENICS 3.2 code for the proposed spallation target of accelerator-driven subcritical reactor system (ADS). The fluid motion in the target is axisymmetric and is treated as a 2-D steady-state problem. A body-fitted coordinate system (BFC) is then chosen and a two-dimensional mesh of the flow channel is generated. Results are presented for the ADS target under both upward and downward flow, and for the target with diffuser plate installed below the window under downward flow

  19. Study on design of superconducting proton linac for accelerator driven subcritical nuclear power system

    CERN Document Server

    Yu Qi; Xu Tao Guang

    2002-01-01

    As a prior option of the next generation of energy source, the accelerator driven subcritical nuclear power system (ADS) can use efficiently the uranium and thorium resource, transmute the high-level long-lived radioactive wastes and raise nuclear safety. The ADS accelerator should provide the proton beam with tens megawatts. The superconducting linac (SCL) is a good selection of ADS accelerator because of its high efficiency and low beam loss rate. It is constitute by a series of the superconducting accelerating cavities. The cavity geometry is determined by means of the electromagnetic field computation. The SCL main parameters are determined by the particle dynamics computation

  20. Subcritical experiments at the FREYA experiment; Experimentos subcriticos en el proyecto FREYA

    Energy Technology Data Exchange (ETDEWEB)

    Becares Palacios, V.; Villamarin fernandez, D.

    2013-07-01

    The FREYA Project of the 7th Framework Program is aimed to the study of the kinetics of subcritical reactors coupled to an external neutron source, and, more specifically, to the validation of reactivity monitoring techniques. CIEMAT activities within the frame of this project have consisted in analyzing the possible ways of correcting the spatial and energy effects on these reactivity monitoring techniques, as well as analyzing the effects that may have on them the presence of different materials in the reflector and the position of the neutron source.

  1. Ion acoustic wave generation by a standing electromagnetic field in a subcritical plasma

    OpenAIRE

    P. Fischer; Gauthereau, C.; Godiot, J.; G. Matthieussent

    1987-01-01

    An electromagnetic wave ( f = 9 GHz, Pi = 150 kW, τ = 1.5 μs) is launched into a subcritical argon plasma (n e ≃1011 cm-3, P0 ≃ 5 × 10-4 Torr), resulting in a standing wave. The associated ponderomotive force generates an ion acoustic wave with a wave vector equal to twice the electromagnetic one and with a frequency satisfying the usual dispersion relation (fA ≃ 150 kHz). The main features of the ion acoustic wave, as measured in this 3D experiment, agree with a simple theory. However, varyi...

  2. PRACTICAL APPLICATION OF THE SINGLE-PARAMETER SUBCRITICAL MASS LIMIT FOR PLUTONIUM METAL

    Energy Technology Data Exchange (ETDEWEB)

    MITCHELL, MARK VON [Los Alamos National Laboratory

    2007-01-10

    According to ANS-8.1, operations with fissile materials can be performed safely by complying with any of the listed single-parameter subcritical limits. For metallic units, when interspersed moderators are present, the mass limits apply to a single piece having no concave surfaces. On a practical level, when has any operation with fissile metal involved a single piece and absolutely no moderating material, e.g., water, oil, plastic, etc.? This would be rare. This paper explores the application of the single-parameter plutonium metal mass limit for realistic operational environments.

  3. Hydrothermal liquefaction of Spirulina and Nannochloropsis Salina under subcritical and supercritical water conditions

    DEFF Research Database (Denmark)

    Toor, Saqib; Reddy, H.; Deng, S.

    2013-01-01

    Six hydrothermal liquefaction experiments on Nannochloropsis salina and Spirulina platensis at subcritical and supercritical water conditions (220-375 °C, 20-255 bar) were carried out to explore the feasibility of extracting lipids from wet algae, preserving nutrients in lipid-extracted algae solid...... on Nannochloropsis salina at 350 °C and 175 bar. For Spirulina platensis algae sample, the optimal hydrothermal liquefaction condition appears to be at 310 °C and 115 bar, while the optimal condition for Nannochloropsis salina is at 350 °C and 175 bar. Preliminary data also indicate that a lipid-extracted algae...

  4. Semiclassical Limit of the Non-linear Schroedinger-Poisson Equation With Subcritical Initial Data

    Science.gov (United States)

    2002-12-01

    lim ∇xargψ. As noted earlier, this argument is self - consistent as long as the solution of the Euler- Poisson system (1.5)-(1.6) remains classical...00-2003 to 00-00-2003 4. TITLE AND SUBTITLE Semiclassical Limit of the Non-linear Schrodinger - Poisson Equation with Subcritical Initial Data 5a...classical limit of a self - consistent quantum-Vlasov equation in 3-D, Math. Models Methods Appl. Sci., 3 (1993), pp. 109–124. [SMM] C. Sparber, P. Markowich

  5. Criticality Safety Evaluation of the LLNL Inherently Safe Subcritical Assembly (ISSA)

    Energy Technology Data Exchange (ETDEWEB)

    Percher, Catherine [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2012-06-19

    The LLNL Nuclear Criticality Safety Division has developed a training center to illustrate criticality safety and reactor physics concepts through hands-on experimental training. The experimental assembly, the Inherently Safe Subcritical Assembly (ISSA), uses surplus highly enriched research reactor fuel configured in a water tank. The training activities will be conducted by LLNL following the requirements of an Integration Work Sheet (IWS) and associated Safety Plan. Students will be allowed to handle the fissile material under the supervision of LLNL instructors. This report provides the technical criticality safety basis for instructional operations with the ISSA experimental assembly.

  6. The glass transition in a nutshell: a source of inspiration to describe the subcritical transition to turbulence.

    Science.gov (United States)

    Dauchot, Olivier; Bertin, Eric

    2014-04-01

    The starting point of the present work is the observation of possible analogies, both at the phenomenological and at the methodological level, between the subcritical transition to turbulence and the glass transition. Having recalled the phenomenology of the subcritical transition to turbulence, we review the theories of the glass transition at a very basic level, focusing on the history of their development as well as on the concepts they have elaborated. Doing so, we aim at attracting the attention on the above-mentioned analogies, which we believe could inspire new developments in the theory of the subcritical transition to turbulence. We then briefly describe a model inspired by one of the simplest and most inspiring models of the glass transition, the so-called Random Energy Model, as a first step in that direction.

  7. Applications of subcritical and supercritical water conditions for extraction, hydrolysis, gasification, and carbonization of biomass: a critical review

    Directory of Open Access Journals (Sweden)

    D. Lachos-Perez

    2017-06-01

    Full Text Available This review summarizes the recent essential aspects of subcritical and supercritical water technology applied tothe extraction, hydrolysis, carbonization, and gasification processes. These are clean and fast technologies which do not need pretreatment, require less reaction time, generate less corrosion and residues, do not usetoxic solvents, and reduce the synthesis of degradation byproducts. The equipment design, process parameters, and types of biomass used for subcritical and supercritical water process are presented. The benefits of catalysis to improve process efficiency are addressed. Bioactive compounds, reducing sugars, hydrogen, biodiesel, and hydrothermal char are the final products of subcritical and supercritical water processes. The present review also revisits advances of the research trends in the development of subcriticaland supercritical water process technologies.

  8. Final Progress Report: FRACTURE AND SUBCRITICAL DEBONDING IN THIN LAYERED STRUCTURES: EXPERIMENTS AND MULTI-SCALE MODELING

    Energy Technology Data Exchange (ETDEWEB)

    Reinhold H. Dauskardt

    2005-08-30

    Final technical report detailing unique experimental and multi-scale computational modeling capabilities developed to study fracture and subcritical cracking in thin-film structures. Our program to date at Stanford has studied the mechanisms of fracture and fatigue crack-growth in structural ceramics at high temperature, bulk and thin-film glasses in selected moist environments where we demonstrated the presence of a true mechanical fatigue effect in some glass compositions. We also reported on the effects of complex environments and fatigue loading on subcritical cracking that effects the reliability of MEMS and other micro-devices using novel micro-machined silicon specimens and nanomaterial layers.

  9. Dynamic properties of nucleated microtubules: GTP utilisation in the subcritical concentration regime.

    Science.gov (United States)

    Symmons, M F; Martin, S R; Bayley, P M

    1996-11-01

    Microtubule assembly kinetics have been studied quantitatively under solution conditions supporting microtubule dynamic instability. Purified GTP-tubulin (Tu-GTP) and covalently cross-linked short microtubule seeds (EGS-seeds; Koshland et al. (1988) Nature 331, 499) were used with and without biotinylation. Under sub-critical concentration conditions ([Tu-GTP] assembly, that was found to abolish the GDP release. The variation of the GDP release with tubulin concentration (Jh(c) plot) was determined below the critical concentration (Cc). The GDP production observed was consistent with the elongation of the observed seeded microtubules with an apparent rate constant of 1.5 x 10(6) M-1 second-1 above a threshold of approximately 1 microM tubulin. The form of this Jh(c) plot for elongation below Cc is reproduced by the Lateral Cap model for microtubule dynamic instability adapted for seeded assembly. The behaviour of the system is contrasted with that previously studied in the absence of detectable microtubule elongation (Caplow and Shanks (1990) J. Biol. Chem. 265, 8935-8941). The approach provides a means of monitoring microtubule dynamics at concentrations inaccessible to optical microscopy, and shows that essentially the same dynamic mechanisms apply at all concentrations. Numerical simulation of the subcritical concentration regime shows dynamic growth features applicable to the initiation of microtubule growth in vivo.

  10. Vacuum ultraviolet spectroscopy of the lowest-lying electronic state in subcritical and supercritical water.

    Science.gov (United States)

    Marin, Timothy W; Janik, Ireneusz; Bartels, David M; Chipman, Daniel M

    2017-05-17

    The nature and extent of hydrogen bonding in water has been scrutinized for decades, including how it manifests in optical properties. Here we report vacuum ultraviolet absorption spectra for the lowest-lying electronic state of subcritical and supercritical water. For subcritical water, the spectrum redshifts considerably with increasing temperature, demonstrating the gradual breakdown of the hydrogen-bond network. Tuning the density at 381 °C gives insight into the extent of hydrogen bonding in supercritical water. The known gas-phase spectrum, including its vibronic structure, is duplicated in the low-density limit. With increasing density, the spectrum blueshifts and the vibronic structure is quenched as the water monomer becomes electronically perturbed. Fits to the supercritical water spectra demonstrate consistency with dimer/trimer fractions calculated from the water virial equation of state and equilibrium constants. Using the known water dimer interaction potential, we estimate the critical distance between molecules (ca. 4.5 Å) needed to explain the vibronic structure quenching.

  11. Homoclinic connections and subcritical Neimark bifurcation in a duopoly model with adaptively adjusted productions

    Energy Technology Data Exchange (ETDEWEB)

    Agliari, Anna [Dipartimento di Scienze Economiche e Sociali, Universita Cattolica del Sacro Cuore, Via Emilia Parmense, 84, 29100 Piacenza (Italy)]. E-mail: anna.agliari@unicatt.it

    2006-08-15

    In this paper we study some global bifurcations arising in the Puu's oligopoly model when we assume that the producers do not adjust to the best reply but use an adaptive process to obtain at each step the new production. Such bifurcations cause the appearance of a pair of closed invariant curves, one attracting and one repelling, this latter being involved in the subcritical Neimark bifurcation of the Cournot equilibrium point. The aim of the paper is to highlight the relationship between the global bifurcations causing the appearance/disappearance of two invariant closed curves and the homoclinic connections of some saddle cycle, already conjectured in [Agliari A, Gardini L, Puu T. Some global bifurcations related to the appearance of closed invariant curves. Comput Math Simul 2005;68:201-19]. We refine the results obtained in such a paper, showing that the appearance/disappearance of closed invariant curves is not necessarily related to the existence of an attracting cycle. The characterization of the periodicity tongues (i.e. a region of the parameter space in which an attracting cycle exists) associated with a subcritical Neimark bifurcation is also discussed.

  12. Total acid number reduction kinetics of naphthenic acids using non-catalytic subcritical methanol

    Science.gov (United States)

    Zafar, Faisal; Mandal, Pradip Chandra; Shaari, Ku Zilati bt Ku; Nadeem, Saad

    2017-10-01

    Naphthenic acids (NAs) are weak organic acids present in the heavy crude oil and Oil Sand Bitumens. Whereas, the NAs are the major cause of corrosion in different processing, handling and storage equipment's of the refinery. Esterification of these acids can be an interesting method to reduce the NAs content in the crude oil besides its esters are valuable commodity and can be used as added lubricant in the oils. In this study, NAs reduction kinetics were investigated in a batch type reactor with subcritical methanol, the experiments were performed at temperatures of 150-210°C and fixed methanol partial pressure of 2 MPa. Findings of this study demonstrate that the 59% of total acid number (TAN) reduction was achieved at the temperature of 210°C, methanol partial pressure of 2 MPa and reaction time of 150 min. The TAN reduction followed second order kinetics with activation energy and frequency factor of 54.15 KJ/mol and 7.6×103, respectively. These results suggest that subcritical methanol can be an effective to reduce the TAN non-catalytically.

  13. Kinetics and reaction pathways of total acid number reduction of cyclopentane carboxylic acid using subcritical methanol

    Directory of Open Access Journals (Sweden)

    Mandal Pradip C.

    2016-09-01

    Full Text Available Cyclopentane carboxylic acid (CPCA is a model compound of Naphthenic acids (NAs. This objective of this paper is to discover total acid number (TAN reduction kinetics and pathways of the reaction between CAPA and subcritical methanol (SubC-MeOH. The experiments were carried out in an autoclave reactor at temperatures of 180-220°C, a methanol partial pressure (MPP of 3 MPa, reaction times of 0-30 min and CPCA initial gas phase concentrations of 0.016-0.04 g/mL. TAN content of the samples were analyzed using ASTM D 974 techniques. The reaction products were identified and quantified with the help of GC/MS and GC-FID respectively. Experimental results reveal that TAN removal kinetics followed first order kinetics with an activation energy of 13.97 kcal/mol and a pre-exponential factor of 174.21 s-1. Subcritical methanol is able to reduce TAN of CPCA decomposing CPCA into new compounds such as cyclopentane, formaldehyde, methyl acetate and 3-pentanol.

  14. Subcritical saturation of the magnetorotational instability through mean magnetic field generation

    Science.gov (United States)

    Xie, Jin-Han; Julien, Keith; Knobloch, Edgar

    2018-03-01

    The magnetorotational instability is widely believed to be responsible for outward angular momentum transport in astrophysical accretion discs. The efficiency of this transport depends on the amplitude of this instability in the saturated state. We employ an asymptotic expansion based on an explicit, astrophysically motivated time-scale separation between the orbital period, Alfvén crossing time and viscous or resistive dissipation time-scales, originally proposed by Knobloch and Julien, to formulate a semi-analytical description of the saturated state in an incompressible disc. In our approach a Keplerian shear flow is maintained by the central mass but the instability saturates via the generation of a mean vertical magnetic field. The theory assumes that the time-averaged angular momentum flux and the radial magnetic flux are constant and determines both self-consistently. The results predict that, depending on parameters, steady saturation may be supercritical or subcritical, and in the latter case that the upper (lower) solution branch is always stable (unstable). The angular momentum flux is always outward, consistent with the presence of accretion, and for fixed wavenumber peaks in the subcritical regime. The limit of infinite Reynolds number at large but finite magnetic Reynolds number is also discussed.

  15. Ultrasound-Enhanced Subcritical CO2 Extraction of Lutein from Chlorella pyrenoidosa.

    Science.gov (United States)

    Fan, Xiao-Dan; Hou, Yan; Huang, Xing-Xin; Qiu, Tai-Qiu; Jiang, Jian-Guo

    2015-05-13

    Lutein is an important pigment of Chlorella pyrenoidosa with many beneficial functions in human health. The main purpose of this study was to extract lutein from C. pyrenoidosa using ultrasound-enhanced subcritical CO2 extraction (USCCE). Effects of operating conditions on the extraction, including extraction pretreatment, temperature, pressure, time, CO2 flow rate, and ultrasonic power, were investigated, and an orthogonal experiment was designed to study the effects of extraction pressure, temperature, cosolvent amount, and time on the extraction yields. The USCCE method was compared with other extraction methods in terms of the yields of lutein and the microstructure of C. pyrenoidosa powder by scanning electron microscopy. A maximal extraction yield of 124.01 mg lutein/100 g crude material was achieved under optimal conditions of extraction temperature at 27 °C, extraction pressure at 21 MPa, cosolvent amount at 1.5 mL/g ethanol, and ultrasound power at 1000 W. Compared to other methods, USCCE could significantly increase the lutein extraction yield at lower extraction temperature and pressure. Furthermore, the kinetic models of USCCE and subcritical CO2 extraction (SCCE) of lutein from C. pyrenoidosa were set as E = 130.64 × (1 - e(-0.6599t)) and E = 101.82 × (1 - e(-0.5683t)), respectively. The differences of parameters in the kinetic models indicate that ultrasound was able to enhance the extraction process of SCCE.

  16. Optimization of Subcritical Water Extraction of Resveratrol from Grape Seeds by Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    Yajie Tian

    2017-03-01

    Full Text Available The subcritical water extraction (SWE is a high-efficiency and environment-friendly extraction method. The extraction of resveratrol (RES of grape seeds obtained from the wine production process was proposed using subcritical water extraction (SWE. The effects of different extraction process parameters on RES yield were investigated by single factors. Extraction optimization was conducted using response surface methodology (RSM. Extraction temperature was proven to be the most significant factor influencing RES yield. The optimal conditions was as follows: extraction pressure of 1.02 MPa, temperature of 152.32 °C, time of 24.89 min, and a solid/solvent ratio of 1:15 g/mL. Under these optimal conditions, the predicted extraction RES yield was 6.90 μg/g and the recoveries was up to 91.98%. Compared to other previous studies, this method required less pollution and less treatment time to extract RES from grape seeds. From these results, added economic value to this agroindustrial residue is proposed using environmentally friendly extraction techniques.

  17. Release of phenolic acids from defatted rice bran by subcritical water treatment.

    Science.gov (United States)

    Fabian, Cynthia; Tran-Thi, Ngoc Yen; Kasim, Novy S; Ju, Yi-Hsu

    2010-12-01

    Oil production from rice bran, an undervalued by-product of rice milling, produces defatted rice bran (DRB) as a waste material. Although it is considered a less valuable product, DRB still contains useful substances such as phenolic compounds with antioxidant, UV-B-protecting and anti-tumour activities. In this study the phenolic acids in DRB were extracted with subcritical water at temperatures of 125, 150, 175 and 200 °C. Analysis of total phenolics using Folin-Ciocalteu reagent showed about 2-20 g gallic acid equivalent kg(-1) bran in the extracts. High-performance liquid chromatography analysis showed low contents of phenolic acids (about 0.4-2 g kg(-1) bran). Ferulic, p-coumaric, gallic and caffeic acids were the major phenolic acids identified in the extracts. Thermal analysis of the phenolic acids was also done. The thermogravimetric curves showed that p-coumaric, caffeic and ferulic acids started to decompose at about 170 °C, while gallic acid did not start to decompose until about 200 °C. Subcritical water can be used to hydrolyse rice bran and release phenolic compounds, but the high temperatures used in the extraction can also cause the decomposition of phenolic acids. Copyright © 2010 Society of Chemical Industry.

  18. Pilot-scale subcritical solvent extraction of curcuminoids from Curcuma long L.

    Science.gov (United States)

    Kwon, Hye-Lim; Chung, Myong-Soo

    2015-10-15

    Curcuminoids consisted curcumin, demethoxycurcumin and bisdemethoxycurcumin, were extracted from turmeric using subcritical solvent by varying conditions of temperature (110-150 °C), time (1-10 min), pressure (5-100 atm), solid-to-solvent ratio, and mixing ratio of solvent. Preliminary lab-scale experiments were conducted to determine the optimum extraction temperature and mixing ratio of water and ethanol for the pilot-scale extraction. The maximum yield of curcuminoids in the pilot-scale system was 13.58% (curcumin 4.94%, demethoxycurcumin 4.73%, and bisdemethoxycurcumin 3.91% in dried extracts) at 135 °C/5 min with water/ethanol mixture (50:50, v/v) as a solvent. On the other hand, the extraction yields of curcuminoids were obtained as 10.49%, 13.71% and 13.96% using the 50%, 95% and 100% ethanol, respectively, at the atmospheric condition (60 °C/120 min). Overall results showed that the subcritical solvent extraction is much faster and efficient extraction method considering extracted curcuminoids contents and has a potential to develop a commercial process for the extraction of curcuminoids. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Production of valued materials from squid viscera by subcritical water hydrolysis.

    Science.gov (United States)

    Uddin, M Salim; Ahn, Hyang-Min; Kishimura, Hideki; Chun, Byung-Soo

    2010-09-01

    Subcritical water hydrolysis was carried out to produce valued materials from squid viscera, the waste product of fish processing industries. The reaction temperatures for hydrolysis of rawand deoiled squid viscera were maintained from 180 to 280 degrees C for5 min. The ratio of material to water forhydrolysis was 1:50. Most of the proteins from deoiled squid viscera were recovered at high temperature. The protein yield in raw squid viscera hydrolyzate decreased with the rise of temperature. The reducing sugar yield was higher at high temperature in subcritical water hydrolysis of both raw and deoiled squid viscera. The highest yield of amino acids in raw and deoiled squid viscera hydrolyzates were 233.25 +/- 3.25 and 533.78 +/- 4.13 mg g(-1) at 180 and 280 degrees C, respectively. Most amino acids attained highest yield at the reaction temperature range of 180-220 degrees C and 260-280 degrees C for raw and deoiled samples, respectively. The recovery of amino acids from deoiled squid viscera was about 1.5 times higher than that of raw squid viscera.

  20. Subcritical convection in a rapidly rotating sphere at low Prandtl number

    CERN Document Server

    Guervilly, Celine

    2016-01-01

    We study non-linear convection in a low Prandtl number fluid ($Pr = 0.01-0.1$) in a rapidly rotating sphere with internal heating. We use a numerical model based on the quasi-geostrophic approximation, in which variations of the axial vorticity along the rotation axis are neglected, whereas the temperature field is fully three-dimensional. We identify two separate branches of convection close to onset: (i) a well-known weak branch for Ekman numbers greater than $10^{-6}$, which is continuous at the onset (supercritical bifurcation) and consists of a superposition of thermal Rossby waves, and (ii) a novel strong branch at lower Ekman numbers, which is discontinuous at the onset. The strong branch becomes subcritical for Ekman numbers of the order of $10^{-8}$. On the strong branch, the Reynolds number of the flow is greater than $10^3$, and a strong zonal flow with multiple jets develops, even close to the non-linear onset of convection. We find that the subcriticality is amplified by decreasing the Prandtl nu...

  1. Subcritical Thermal Convection of Liquid Metals in a Rapidly Rotating Sphere

    Science.gov (United States)

    Kaplan, E. J.; Schaeffer, N.; Vidal, J.; Cardin, P.

    2017-09-01

    Planetary cores consist of liquid metals (low Prandtl number Pr) that convect as the core cools. Here, we study nonlinear convection in a rotating (low Ekman number Ek) planetary core using a fully 3D direct numerical simulation. Near the critical thermal forcing (Rayleigh number Ra), convection onsets as thermal Rossby waves, but as Ra increases, this state is superseded by one dominated by advection. At moderate rotation, these states (here called the weak branch and strong branch, respectively) are smoothly connected. As the planetary core rotates faster, the smooth transition is replaced by hysteresis cycles and subcriticality until the weak branch disappears entirely and the strong branch onsets in a turbulent state at Ek <10-6. Here, the strong branch persists even as the thermal forcing drops well below the linear onset of convection (Ra =0.7 Racrit in this study). We highlight the importance of the Reynolds stress, which is required for convection to subsist below the linear onset. In addition, the Péclet number is consistently above 10 in the strong branch. We further note the presence of a strong zonal flow that is nonetheless unimportant to the convective state. Our study suggests that, in the asymptotic regime of rapid rotation relevant for planetary interiors, thermal convection of liquid metals in a sphere onsets through a subcritical bifurcation.

  2. Beam transient analyses of Accelerator Driven Subcritical Reactors based on neutron transport method

    Energy Technology Data Exchange (ETDEWEB)

    He, Mingtao; Wu, Hongchun [School of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Zheng, Youqi, E-mail: yqzheng@mail.xjtu.edu.cn [School of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Wang, Kunpeng [Nuclear and Radiation Safety Center, PO Box 8088, Beijing 100082 (China); Li, Xunzhao; Zhou, Shengcheng [School of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China)

    2015-12-15

    Highlights: • A transport-based kinetics code for Accelerator Driven Subcritical Reactors is developed. • The performance of different kinetics methods adapted to the ADSR is investigated. • The impacts of neutronic parameters deteriorating with fuel depletion are investigated. - Abstract: The Accelerator Driven Subcritical Reactor (ADSR) is almost external source dominated since there is no additional reactivity control mechanism in most designs. This paper focuses on beam-induced transients with an in-house developed dynamic analysis code. The performance of different kinetics methods adapted to the ADSR is investigated, including the point kinetics approximation and space–time kinetics methods. Then, the transient responds of beam trip and beam overpower are calculated and analyzed for an ADSR design dedicated for minor actinides transmutation. The impacts of some safety-related neutronics parameters deteriorating with fuel depletion are also investigated. The results show that the power distribution varying with burnup leads to large differences in temperature responds during transients, while the impacts of kinetic parameters and feedback coefficients are not very obvious. Classification: Core physic.

  3. The Free Overfall in Circular Sections with Different Flat Base in Supercritical and Subcritical Flow Regimes

    Directory of Open Access Journals (Sweden)

    A.R. Vatankhah

    2017-01-01

    Full Text Available Introduction: A free overfall offers a simple device for flow discharge measuring by a single measurement of depth at the end of the channel yb which is known as the end depth or brink depth. When the bottom of a channel drops suddenly, the flow separates from sharp edge of the brink and the pressure distribution is not hydrostatic because of the curvature of the flow. In channels with subcritical flow regime, control section occurs at the upstream with a critical depth (yc. Although pressure distribution at the critical depth is hydrostatic, the location of the critical depth can vary with respect to the discharge value. So, the end depth at brink is offered to estimate the discharge. A unique relationship between the brink depth (yb and critical depth (yc, known as end-depth ratio (EDR = yb/yc, exist. Since a relationship between the discharge and critical depth exists, the discharge can ultimately be related to yb. However, when the approaching flow is supercritical, critical section does not exist. Therefore, the discharge will be a function of end depth and channel longitudinal slope. In current study, an analytical model is presented for a circular free overfall with different flat base height in subcritical and supercritical flow regimes. The flow over a drop in a free overfall is simulated by applying the energy to calculate the EDR and end depth-discharge (EDD relationship. End-depth-discharge relationship: The flow of a free overfall in a channel can be assumed that is similar to the flow over a sharp-crested weir by taking weir height equal to zero. It is assumed that pressure at the end section is atmospheric, and also streamlines at the end section are parallel. To account for the curvature of streamlines, the deflection of jet due to gravity, the coefficient of contraction, Cc, is considered. At a short distance upstream the end section, the pressure is hydrostatic. By applying the energy equation between end section and control

  4. Second gradient poromechanics

    CERN Document Server

    Sciarra, Giulio; Coussy, Olivier

    2010-01-01

    Second gradient theories have been developed in mechanics for treating different phenomena as capillarity in fluids, plasticity and friction in granular materials or shear band deformations. Here, there is an attempt of formulating a second gradient Biot like model for porous materials. In particular the interest is focused in describing the local dilatant behaviour of a porous material induced by pore opening elastic and capillary interaction phenomena among neighbouring pores and related micro-filtration phenomena by means of a continuum microstructured model. The main idea is to extend the classical macroscopic Biot model by including in the description second gradient effects. This is done by assuming that the surface contribution to the external work rate functional depends on the normal derivative of the velocity or equivalently assuming that the strain work rate functional depends on the porosity and strain gradients. According to classical thermodynamics suitable restrictions for stresses and second g...

  5. Benzo(a)pyrene accumulation in soils of technogenic emission zone by subcritical water extraction method

    Science.gov (United States)

    Sushkova, Svetlana; Minkina, Tatiana; Kizilkaya, Ridvan; Mandzhieva, Saglara; Batukaev, Abdulmalik; Bauer, Tatiana; Gulser, Coskun

    2016-04-01

    The purpose of research is the assessment of main marker of polycyclic aromatic hydrocarbons contamination, benzo[a]pyrene (BaP) content in soils of emission zone of the power complex plant in soils with use of ecologically clean and effective subcritical water extraction method. Studies were conducted on the soils of monitoring plots subjected to Novocherkassk Power Plant emissions from burning coal. In 2000, monitoring plots were established at different distances from the NPS (1.0-20.0 km). Soil samples for the determination of soil properties and the contents of BaP were taken from a depth of 0-20 cm. The soil cover in the region under study consisted of ordinary chernozems, meadow-chernozemic soils, and alluvial meadow soils. This soil revealed the following physical and chemical properties: Corg-3.1-5.0%, pH-7.3-7.6, ECE-31.2-47.6 mmol(+)/100g; CaCO3-0.2-1.0%, the content of physical clay - 51-67% and clay - 3-37%. BaP extraction from soils was carried out by a subcritical water extraction method. Subcritical water extraction of BaP from soil samples was conducted in a specially developed extraction cartridge made of stainless steel and equipped with screw-on caps at both ends. It was also equipped with a manometer that included a valve for pressure release to maintain an internal pressure of 100 atm. The extraction cartridge containing a sample and water was placed into an oven connected to a temperature regulator under temperature 250oC and pressure 60 atm. The BaP concentration in the acetonitrile extract was determined by HPLC. The efficiency of BaP extraction from soil was determined using a matrix spike. The main accumulation of pollutant in 20 cm layer of soils is noted directly in affected zone on the plots situated at 1.2, 1.6, 5.0, 8.0 km from emission source in the direction of prevailing winds. The maximum quantity of a pollutant was founded in the soil of the plot located mostly close to a source of pollution in the direction of prevailing winds

  6. Analysis of product distribution and characteristics in hydrothermal liquefaction of barley straw in subcritical and supercritical water

    DEFF Research Database (Denmark)

    Zhu, Zhe; Toor, Saqib; Rosendahl, Lasse

    2014-01-01

    In this study, hydrothermal liquefaction of barley straw in subcritical and supercritical water with potassium carbonate catalyst was performed in the temperatures range of 280-400°C. The influence of final reaction temperature on products yield was investigated and some physicochemical properties...

  7. Supercritical CO(2) and subcritical propane extraction of pungent paprika and quantification of carotenoids, tocopherols, and capsaicinoids.

    Science.gov (United States)

    Gnayfeed, M H; Daood, H G; Illés, V; Biacs, P A

    2001-06-01

    Ground paprika (Capsicum annuum L.) was extracted with supercritical carbon dioxide (SC-CO(2)) and subcritical propane at different conditions of pressure and temperature to estimate the yield and variation in carotenoid, tocopherol, and capsaicinoid contents and composition. The yield of paprika extract was found to be affected by the extraction conditions with SC-CO(2) but fairly constant at different conditions with subcritical propane. The maximum yields of oleoresin were 7.9 and 8.1% of ground paprika by SC-CO(2) and subcritical propane, respectively. The quantitative distribution of carotenoids, tocopherols, and capsaicinoids between paprika extract and powder was influenced by extraction conditions. SC-CO(2) was inefficient in the extraction of diesters of xanthophylls even at 400 bar and 55 degrees C, whereas tocopherols and capsaicinoids were easy to extract at these conditions. Under mild conditions subcritical propane was superior to SC-CO(2) in the extraction of carotenoids and tocopherols but less efficient in the extraction of capsaicinoids.

  8. Hydrolysis of polycarbonate in sub-critical water in fused silica capillary reactor with in situ Raman spectroscopy

    Science.gov (United States)

    Pan, Z.; Chou, I.-Ming; Burruss, R.C.

    2009-01-01

    The advantages of using fused silica capillary reactor (FSCR) instead of conventional autoclave for studying chemical reactions at elevated pressure and temperature conditions were demonstrated in this study, including the allowance for visual observation under a microscope and in situ Raman spectroscopic characterization of polycarbonate and coexisting phases during hydrolysis in subcritical water. ?? 2009 The Royal Society of Chemistry.

  9. High Gradient Accelerator Research

    Energy Technology Data Exchange (ETDEWEB)

    Temkin, Richard [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Physics. Plasma Science and Fusion Center

    2016-07-12

    The goal of the MIT program of research on high gradient acceleration is the development of advanced acceleration concepts that lead to a practical and affordable next generation linear collider at the TeV energy level. Other applications, which are more near-term, include accelerators for materials processing; medicine; defense; mining; security; and inspection. The specific goals of the MIT program are: • Pioneering theoretical research on advanced structures for high gradient acceleration, including photonic structures and metamaterial structures; evaluation of the wakefields in these advanced structures • Experimental research to demonstrate the properties of advanced structures both in low-power microwave cold test and high-power, high-gradient test at megawatt power levels • Experimental research on microwave breakdown at high gradient including studies of breakdown phenomena induced by RF electric fields and RF magnetic fields; development of new diagnostics of the breakdown process • Theoretical research on the physics and engineering features of RF vacuum breakdown • Maintaining and improving the Haimson / MIT 17 GHz accelerator, the highest frequency operational accelerator in the world, a unique facility for accelerator research • Providing the Haimson / MIT 17 GHz accelerator facility as a facility for outside users • Active participation in the US DOE program of High Gradient Collaboration, including joint work with SLAC and with Los Alamos National Laboratory; participation of MIT students in research at the national laboratories • Training the next generation of Ph. D. students in the field of accelerator physics.

  10. Preconditioned Stochastic Gradient Descent.

    Science.gov (United States)

    Li, Xi-Lin

    2017-03-09

    Stochastic gradient descent (SGD) still is the workhorse for many practical problems. However, it converges slow, and can be difficult to tune. It is possible to precondition SGD to accelerate its convergence remarkably. But many attempts in this direction either aim at solving specialized problems, or result in significantly more complicated methods than SGD. This paper proposes a new method to adaptively estimate a preconditioner, such that the amplitudes of perturbations of preconditioned stochastic gradient match that of the perturbations of parameters to be optimized in a way comparable to Newton method for deterministic optimization. Unlike the preconditioners based on secant equation fitting as done in deterministic quasi-Newton methods, which assume positive definite Hessian and approximate its inverse, the new preconditioner works equally well for both convex and nonconvex optimizations with exact or noisy gradients. When stochastic gradient is used, it can naturally damp the gradient noise to stabilize SGD. Efficient preconditioner estimation methods are developed, and with reasonable simplifications, they are applicable to large-scale problems. Experimental results demonstrate that equipped with the new preconditioner, without any tuning effort, preconditioned SGD can efficiently solve many challenging problems like the training of a deep neural network or a recurrent neural network requiring extremely long-term memories.

  11. Radioactive isotope production for medical applications using Kharkov electron driven subcritical assembly facility.

    Energy Technology Data Exchange (ETDEWEB)

    Talamo, A.; Gohar, Y.; Nuclear Engineering Division

    2007-05-15

    Kharkov Institute of Physics and Technology (KIPT) of Ukraine has a plan to construct an accelerator driven subcritical assembly. The main functions of the subcritical assembly are the medical isotope production, neutron thereby, and the support of the Ukraine nuclear industry. Reactor physics experiments and material research will be carried out using the capabilities of this facility. The United States of America and Ukraine have started collaboration activity for developing a conceptual design for this facility with low enrichment uranium (LEU) fuel. Different conceptual designs are being developed based on the facility mission and the engineering requirements including nuclear physics, neutronics, heat transfer, thermal hydraulics, structure, and material issues. Different fuel designs with LEU and reflector materials are considered in the design process. Safety, reliability, and environmental considerations are included in the facility conceptual design. The facility is configured to accommodate future design improvements and upgrades. This report is a part of the Argonne National Laboratory Activity within this collaboration for developing and characterizing the subcritical assembly conceptual design. In this study, the medical isotope production function of the Kharkov facility is defined. First, a review was carried out to identify the medical isotopes and its medical use. Then a preliminary assessment was performed without including the self-shielding effect of the irradiated samples. Finally, more detailed investigation was carried out including the self-shielding effect, which defined the sample size and irradiation location for producing each medical isotope. In the first part, the reaction rates were calculated as the multiplication of the cross section with the unperturbed neutron flux of the facility. Over fifty isotopes were considered and all transmutation channels are used including (n,{gamma}), (n,2n), (n,p), and ({gamma},n). In the second part

  12. Uniform gradient expansions

    Directory of Open Access Journals (Sweden)

    Massimo Giovannini

    2015-06-01

    Full Text Available Cosmological singularities are often discussed by means of a gradient expansion that can also describe, during a quasi-de Sitter phase, the progressive suppression of curvature inhomogeneities. While the inflationary event horizon is being formed the two mentioned regimes coexist and a uniform expansion can be conceived and applied to the evolution of spatial gradients across the protoinflationary boundary. It is argued that conventional arguments addressing the preinflationary initial conditions are necessary but generally not sufficient to guarantee a homogeneous onset of the conventional inflationary stage.

  13. FINAL DESIGN REVIEW REPORT Subcritical Experiments Gen 2, 3-ft Confinement Vessel Weldment

    Energy Technology Data Exchange (ETDEWEB)

    Romero, Christopher [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-09-28

    A Final Design Review (FDR) of the Subcritical Experiments (SCE) Gen 2, 3-ft. Confinement Vessel Weldment was held at Los Alamos National Laboratory (LANL) on September 14, 2017. The review was a focused review on changes only to the confinement vessel weldment (versus a system design review). The changes resulted from lessons-learned in fabricating and inspecting the current set of confinement vessels used for the SCE Program. The baseline 3-ft. confinement vessel weldment design has successfully been used (to date) for three (3) high explosive (HE) over-tests, two (2) fragment tests, and five (5) integral HE experiments. The design team applied lessons learned from fabrication and inspection of these vessel weldments to enhance fit-up, weldability, inspection, and fitness for service evaluations. The review team consisted of five (5) independent subject matter experts with engineering design, analysis, testing, fabrication, and inspection experience. The

  14. Conceptual study of high power proton linac for accelerator driven subcritical nuclear power system

    CERN Document Server

    Yu Qi; Ouyang Hua Fu; Xu Tao Guang

    2001-01-01

    As a prior option of the next generation of energy source, the accelerator driven subcritical nuclear power system (ADS) can use efficiently the uranium and thorium resource, transmute the high-level long-lived radioactive wastes and raise nuclear safety. The ADS accelerator should provide the proton beam with tens megawatts. The superconducting linac is a good selection of ADS accelerator because of its high efficiency and low beam loss rate. The ADS accelerator presented by the consists of a 5 MeV radio-frequency quadrupole, a 100 MeV independently phased superconducting cavity linac and a 1 GeV elliptical superconducting cavity linac. The accelerating structures and main parameters are determined and the research and development plan is considered

  15. Conceptual design based on scale laws and algorithms for sub-critical transmutation reactors

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kwang Gu; Chang, Soon Heung [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)

    1997-12-31

    In order to conduct the effective integration of computer-aided conceptual design for integrated nuclear power reactor, not only is a smooth information flow required, but also decision making for both conceptual design and construction process design must be synthesized. In addition to the aboves, the relations between the one step and another step and the methodologies to optimize the decision variables are verified, in this paper especially, that is, scaling laws and scaling criteria. In the respect with the running of the system, the integrated optimization process is proposed in which decisions concerning both conceptual design are simultaneously made. According to the proposed reactor types and power levels, an integrated optimization problems are formulated. This optimization is expressed as a multi-objective optimization problem. The algorithm for solving the problem is also presented. The proposed method is applied to designing a integrated sub-critical reactors. 6 refs., 5 figs., 1 tab. (Author)

  16. Kinetic model for the esterification of oleic acid catalyzed by zinc acetate in subcritical methanol

    Energy Technology Data Exchange (ETDEWEB)

    Song, Chengcai; Deng, Tiansheng [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, P.O. Box 165, Taiyuan, Shanxi 030001 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Qi, Yongqin; Hou, Xianglin; Qin, Zhangfeng [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, P.O. Box 165, Taiyuan, Shanxi 030001 (China)

    2010-03-15

    The esterification of oleic acid in subcritical methanol catalyzed by zinc acetate was investigated in a batch-type autoclave. The effect of reaction conditions such as temperature, pressure, reaction time and molar ratio of oleic acid to methanol on the esterification was examined. The oleic acid conversion reached 95.0% under 220 C and 6.0 MPa with the molar ratio of methanol to oleic acid being 4 and 1.0 wt% zinc acetate as catalyst. A kinetic model for the esterification was established. By fitting the kinetic model with the experimental results, the reaction order n = 2.2 and activation energy E{sub a} = 32.62 KJ/mol were obtained. (author)

  17. The mechanism of lipids extraction from wet microalgae Scenedesmus sp. by ionic liquid assisted subcritical water

    Science.gov (United States)

    Yu, Zhuanni; Chen, Xiaolin; Xia, Shuwei

    2016-06-01

    In this paper, the total sugar concentration, protein concentration, lipid yield and morphology characteristics of the algae residue were determined to explain the mechanism of lipids extraction from wet microalgae Scenedesmus sp. by ionic liquid assisted subcritical water. The results showed similar variation for the sugar, protein and lipid. However, the total sugar was more similar to lipids yield, so the results showed that the reaction between ionic liquid and cellulose and hemicellulose in cell wall was the most important step which determined the lipids extration directly. And the total sugar variation may be representing the lipids yield. For later lipids extraction, we can determine the total sugar concentration to predict the extraction end product.

  18. An integrated green process: Subcritical water, enzymatic hydrolysis, and fermentation, for biohydrogen production from coconut husk.

    Science.gov (United States)

    Muharja, Maktum; Junianti, Fitri; Ranggina, Dian; Nurtono, Tantular; Widjaja, Arief

    2017-10-09

    The objective of this work is to develop an integrated green process of subcritical water (SCW), enzymatic hydrolysis and fermentation of coconut husk (CCH) to biohydrogen. The maximum sugar yield was obtained at mild severity factor. This was confirmed by the degradation of hemicellulose, cellulose and lignin. The tendency of the changing of sugar yield as a result of increasing severity factor was opposite to the tendency of pH change. It was found that CO2 gave a different tendency of severity factor compared to N2 as the pressurizing gas. The result of SEM analysis confirmed the structural changes during SCW pretreatment. This study integrated three steps all of which are green processes which ensured an environmentally friendly process to produce a clean biohydrogen. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Experimental study of subcritical laboratory magnetized collisionless shocks using a laser-driven magnetic piston

    Energy Technology Data Exchange (ETDEWEB)

    Schaeffer, D. B., E-mail: dschaeffer@physics.ucla.edu; Everson, E. T.; Bondarenko, A. S.; Clark, S. E.; Constantin, C. G.; Gekelman, W.; Niemann, C. [Department of Physics and Astronomy, University of California—Los Angeles, Los Angeles, California 90095 (United States); Winske, D. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2015-11-15

    Recent experiments at the University of California, Los Angeles have successfully generated subcritical magnetized collisionless shocks, allowing new laboratory studies of shock formation relevant to space shocks. The characteristics of these shocks are compared with new data in which no shock or a pre-shock formed. The results are consistent with theory and 2D hybrid simulations and indicate that the observed shock or shock-like structures can be organized into distinct regimes by coupling strength. With additional experiments on the early time parameters of the laser plasma utilizing Thomson scattering, spectroscopy, and fast-gate filtered imaging, these regimes are found to be in good agreement with theoretical shock formation criteria.

  20. Subcritical Growth of Electron Phase-space Holes in Planetary Radiation Belts

    Science.gov (United States)

    Osmane, Adnane; Turner, Drew L.; Wilson, Lynn B.; Dimmock, Andrew P.; Pulkkinen, Tuija I.

    2017-09-01

    The discovery of long-lived electrostatic coherent structures with large-amplitude electric fields (1≤slant E ≤slant 500 mV/m) by the Van Allen Probes has revealed alternative routes through which planetary radiation belts’ acceleration can take place. Following previous reports showing that small phase-space holes, with qφ /{T}ec≃ {10}-2{--}{10}-3, could result from electron interaction with large-amplitude whistlers, we demonstrate one possible mechanism through which holes can grow nonlinearly (I.e., γ \\propto \\sqrt{φ }) and subcritically as a result of momentum exchange between hot and cold electron populations. Our results provide an explanation for the common occurrence and fast growth of large-amplitude electron phase-space holes in the Earth’s radiation belts.

  1. A review on green trend for oil extraction using subcritical water technology and biodiesel production.

    Science.gov (United States)

    Abdelmoez, Weal; Ashour, Eman; Naguib, Shahenaz M

    2015-01-01

    It became a global agenda to develop clean alternative fuels which were domestically available, environmentally acceptable and technically feasible. Thus, biodiesel was destined to make a substantial contribution to the future energy demands of the domestic and industrial economies. Utilization of the non edible vegetable oils as raw materials for biodiesel production had been handled frequently for the past few years. The oil content of these seeds could be extracted by different oil extraction methods, such as mechanical extraction, solvent extraction and by subcritical water extraction technology SWT. Among them, SWT represents a new promising green extraction method. Therefore this review covered the current used non edible oil seeds for biodiesel production as well as giving a sharp focus on the efficiency of using the SWT as a promising extraction method. In addition the advantages and the disadvantages of the different biodiesel production techniques would be covered.

  2. Nonlinear elastic behavior of sub-critically damaged body armor panel

    Science.gov (United States)

    Fisher, Jason T.; Chimenti, D. E.

    2012-05-01

    A simple go/no-go test for body armor panels using pressure-sensitive, dye-indicator film (PSF) has been shown to be statistically effective in revealing subcritical damage to body armor panels. Previous measurements have shown that static indicator levels are accurately reproduced in dynamic loading events. Further impact tests on armor worn by a human resuscitation dummy using instrumented masses with an attached accelerometer and embedded force transducer have been performed and analyzed. New impact tests have shown a reliable correlation between PSF indication (as digitized images) and impact force for a wide range of impactor energies and masses. Numerical evaluation of digital PSF images is presented and correlated with impact parameters. Relationships between impactor mass and energy, and corresponding measured force are shown. We will also report on comparisons between ballistic testing performed on panels damaged under various impact conditions and tests performed on undamaged panels.

  3. Temperature effects on diffusion coefficient for 6-gingerol and 6-shogaol in subcritical water extraction

    Science.gov (United States)

    Ilia Anisa, Nor; Azian, Noor; Sharizan, Mohd; Iwai, Yoshio

    2014-04-01

    6-gingerol and 6-shogaol are the main constituents as anti-inflammatory or bioactive compounds from zingiber officinale Roscoe. These bioactive compounds have been proven for inflammatory disease, antioxidatives and anticancer. The effect of temperature on diffusion coefficient for 6-gingerol and 6-shogaol were studied in subcritical water extraction. The diffusion coefficient was determined by Fick's second law. By neglecting external mass transfer and solid particle in spherical form, a linear portion of Ln (1-(Ct/Co)) versus time was plotted in determining the diffusion coefficient. 6-gingerol obtained the higher yield at 130°C with diffusion coefficient of 8.582x10-11 m2/s whilst for 6-shogaol, the higher yield and diffusion coefficient at 170°C and 19.417 × 10-11 m2/s.

  4. Operation and reactivity measurements of an accelerator driven subcritical TRIGA reactor

    Science.gov (United States)

    O'Kelly, David Sean

    Experiments were performed at the Nuclear Engineering Teaching Laboratory (NETL) in 2005 and 2006 in which a 20 MeV linear electron accelerator operating as a photoneutron source was coupled to the TRIGA (Training, Research, Isotope production, General Atomics) Mark II research reactor at the University of Texas at Austin (UT) to simulate the operation and characteristics of a full-scale accelerator driven subcritical system (ADSS). The experimental program provided a relatively low-cost substitute for the higher power and complexity of internationally proposed systems utilizing proton accelerators and spallation neutron sources for an advanced ADSS that may be used for the burning of high-level radioactive waste. Various instrumentation methods that permitted ADSS neutron flux monitoring in high gamma radiation fields were successfully explored and the data was used to evaluate the Stochastic Pulsed Feynman method for reactivity monitoring.

  5. Experimental study of subcritical laboratory magnetized collisionless shocks using a laser-driven magnetic piston

    Science.gov (United States)

    Schaeffer, D. B.; Everson, E. T.; Bondarenko, A. S.; Clark, S. E.; Constantin, C. G.; Winske, D.; Gekelman, W.; Niemann, C.

    2015-11-01

    Recent experiments at the University of California, Los Angeles have successfully generated subcritical magnetized collisionless shocks, allowing new laboratory studies of shock formation relevant to space shocks. The characteristics of these shocks are compared with new data in which no shock or a pre-shock formed. The results are consistent with theory and 2D hybrid simulations and indicate that the observed shock or shock-like structures can be organized into distinct regimes by coupling strength. With additional experiments on the early time parameters of the laser plasma utilizing Thomson scattering, spectroscopy, and fast-gate filtered imaging, these regimes are found to be in good agreement with theoretical shock formation criteria.

  6. Source-jerk method for application on ADS neutronics study The ADS is stated for Accelerator Driven sub-critical System

    CERN Document Server

    Zhu Qing Fu; Li Yi; Xia Pu; Zheng Wu Qing; Zhu Guo Sheng

    2003-01-01

    The paper is concerned in the source-jerk method used to measure the sub-criticality, and the sub-critical experiment facility, which is used for the study on the neutronics of ADS, driven by external neutron source sup 2 sup 5 sup 2 Cf. The effects of the location of neutron source and material buffer where is at the location of the pipe of proton beam and target of fission-product dispersion on the sub-criticality of reactor are studied by source-jerk method

  7. Global bifurcations to subcritical magnetorotational dynamo action in Keplerian shear flow

    Science.gov (United States)

    Riols, A.; Rincon, F.; Cossu, C.; Lesur, G.; Longaretti, P.-Y.; Ogilvie, G. I.; Herault, J.

    2013-09-01

    Magnetorotational dynamo action in Keplerian shear flow is a three-dimensional, nonlinear magnetohydrodynamic process whose study is relevant to the understanding of accretion and magnetic field generation in astrophysics. Transition to this form of dynamo is subcritical and shares many characteristics of transition to turbulence in non-rotating hydrodynamic shear flows. This suggests that these different fluid systems become active through similar generic bifurcation mechanisms, which in both cases have eluded detailed understanding so far. In this paper, we investigate numerically the bifurcation mechanisms at work in the incompressible Keplerian magnetorotational dynamo problem in the shearing box framework. Using numerical techniques imported from dynamical systems research, we show that the onset of chaotic dynamo action at magnetic Prandtl numbers larger than unity is primarily associated with global homoclinic and heteroclinic bifurcations of nonlinear magnetorotational dynamo cycles. These global bifurcations are supplemented by local bifurcations of cycles marking the beginning of period-doubling cascades. This suggests that nonlinear magnetorotational dynamo cycles provide the pathway to turbulent injection of both kinetic and magnetic energy in incompressible magnetohydrodynamic Keplerian shear flow in the absence of an externally imposed magnetic field. Studying the nonlinear physics and bifurcations of these cycles in different regimes and configurations may subsequently help to better understand the conditions of excitation of magnetohydrodynamic turbulence and instability-driven dynamos in various astrophysical systems and laboratory experiments. The detailed characterization of global bifurcations provided for this three-dimensional subcritical fluid dynamics problem may also prove useful for the problem of transition to turbulence in hydrodynamic shear flows.

  8. Monte Carlo modeling and analyses of YALINA- booster subcritical assembly Part II : pulsed neutron source.

    Energy Technology Data Exchange (ETDEWEB)

    Talamo, A.; Gohar, M. Y. A.; Rabiti, C.; Nuclear Engineering Division

    2008-10-22

    One of the most reliable experimental methods for measuring the kinetic parameters of a subcritical assembly is the Sjoestrand method applied to the reaction rate generated from a pulsed neutron source. This study developed a new analytical methodology for characterizing the kinetic parameters of a subcritical assembly using the Sjoestrand method, which allows comparing the analytical and experimental time dependent reaction rates and the reactivity measurements. In this methodology, the reaction rate, detector response, is calculated due to a single neutron pulse using MCNP/MCNPX computer code or any other neutron transport code that explicitly simulates the fission delayed neutrons. The calculation simulates a single neutron pulse over a long time period until the delayed neutron contribution to the reaction is vanished. The obtained reaction rate is superimposed to itself, with respect to the time, to simulate the repeated pulse operation until the asymptotic level of the reaction rate, set by the delayed neutrons, is achieved. The superimposition of the pulse to itself was calculated by a simple C computer program. A parallel version of the C program is used due to the large amount of data being processed, e.g. by the Message Passing Interface (MPI). The new calculation methodology has shown an excellent agreement with the experimental results available from the YALINA-Booster facility of Belarus. The facility has been driven by a Deuterium-Deuterium or Deuterium-Tritium pulsed neutron source and the (n,p) reaction rate has been experimentally measured by a {sup 3}He detector. The MCNP calculation has utilized the weight window and delayed neutron biasing variance reduction techniques since the detector volume is small compared to the assembly volume. Finally, this methodology was used to calculate the IAEA benchmark of the YALINA-Booster experiment.

  9. Application of supercritical and subcritical fluids for the extraction of hazardous materials from soil

    Directory of Open Access Journals (Sweden)

    Skorupan Dara

    2002-01-01

    Full Text Available Subcritical and supercritical extractions are novel, non destructive techniques which can be applied for the removal of hazardous compounds from contaminated soil without any changes of the soil composition and structure. The aim of the presented review paper is to give information on up-to day results of this method commonly applied by several institutions worldwide. Interest in the application of SC CO2 has been more expressed in the last two decades, which may be related to its favorable characteristics (non-toxic, non-flammable, increase diffusion into small pores, low viscosity under SC conditions, low price and others. However, interest in wet oxidation (WO and especially in SCWO (the application of water under supercritical conditions with air has also increased in the last few years. Interest in H2O as a SC fluid, as well as in extraction with water under subcritical conditions may also be related to specific characteristics and the enhanced rate of extraction. Moreover, the solubility of some specific compounds present in soil can be easily changed by adjusting the pressure and temperature of extraction. The high price of the units designed to operate safely at a pressure and temperature much higher than the a critical one of the applied fluids is the main reason why, at present, there is no more broader application of such techniques for the removal hazardous materials from contaminated soil. In the present paper, among many literature citations and their overall review, some specific details related to the development of specific analytical methods under SC conditions are also considered.

  10. TNT and RDX degradation and extraction from contaminated soil using subcritical water.

    Science.gov (United States)

    Islam, Mohammad Nazrul; Shin, Moon-Su; Jo, Young-Tae; Park, Jeong-Hun

    2015-01-01

    The use of explosives either for industrial or military operations have resulted in the environmental pollution, poses ecological and health hazard. In this work, a subcritical water extraction (SCWE) process at laboratory scale was used at varying water temperature (100-175 °C) and flow rate (0.5-1.5 mL min(-1)), to treat 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) contaminated soil, to reveal information with respect to the explosives removal (based on the analyses of soil residue after extraction), and degradation performance (based on the analyses of water extracts) of this process. Continuous flow subcritical water has been considered on removal of explosives to avoid the repartitioning of non-degraded compounds to the soil upon cooling which usually occurs in the batch system. In the SCWE experiments, near complete degradation of both TNT and RDX was observed at 175 °C based on analysis of water extracts and soil. Test results also indicated that TNT removal of >99% and a complete RDX removal were achieved by this process, when the operating conditions were 1 mL min(-1), and treatment time of 20 min, after the temperature reached 175 °C. HPLC-UV and ion chromatography analysis confirmed that the explosives underwent for degradation. The low concentration of explosives found in the process wastewater indicates that water recycling may be viable, to treat additional soil. Our results have shown in the remediation of explosives contaminated soil, the effectiveness of the continuous flow SCWE process. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Highly Selective and Considerable Subcritical Butane Extraction to Separate Abamectin in Green Tea.

    Science.gov (United States)

    Zhang, Yating; Gu, Lingbiao; Wang, Fei; Kong, Lingjun; Pang, Huili; Qin, Guangyong

    2017-06-01

    We specially carried out the subcritical butane extraction to separate abamectin from tea leaves. Four parameters, such as extraction temperature, extraction time, number of extraction cycles, and solid-liquid ratio were studied and optimized through the response surface methodology with design matrix developed by Box-Behnken. Seventeen experiments with three various factors and three variable levels were employed to investigate the effect of these parameters on the extraction of abamectin. Besides, catechins, theanine, caffeine, and aroma components were determined by both high-performance liquid chromatography and gas chromatography-mass spectrometry to evaluate the tea quality before and after the extraction. The results showed that the extraction temperature was the uppermost parameter compared with others. The optimal extraction conditions selected as follows: extraction temperature, 42°C; number of extraction cycles and extraction time, 1 and 30 min, respectively; and solid-liquid ratio, 1:10. Based on the above study, the separation efficiency of abamectin was up to 93.95%. It is notable that there has a quite low loss rate, including the negligible damage of aroma components, the bits reduce of catechins within the range of 0.7%-13.1%, and a handful lessen of caffeine and theanine of 1.81% and 2.6%, respectively. The proposed method suggested subcritical butane possesses solubility for lipid-soluble pesticides, and since most of the pesticides are attached to the surfaces of tea, thus the as-applied method was successfully effective to separate abamectin because of the so practical and promising method.

  12. Probabilistic Multileave Gradient Descent

    NARCIS (Netherlands)

    Oosterhuis, H.; Schuth, A.; de Rijke, M.; Ferro, N.; Crestani, F.; Moens, M.-F.; Mothe, J.; Silvestri, F.; Di Nunzio, G.M.; Hauff, C.; Silvello, G.

    2016-01-01

    Online learning to rank methods aim to optimize ranking models based on user interactions. The dueling bandit gradient descent (DBGD) algorithm is able to effectively optimize linear ranking models solely from user interactions. We propose an extension of DBGD, called probabilistic multileave

  13. US Department of Energy Secretary Bill Richardson (centre) at an LHC interaction region quadrupole test cryostat. part of the US contribution to LHC construction and built by the US-LHC collaboration (hence the Fermilab logo)

    CERN Multimedia

    Barbara Warmbein

    2000-01-01

    Photo 01 : September 2000 - Mr Bill Richardson, Secretary of Energy, United States of America (centre) at an LHC interaction region quadrupole test cryostat, part of the US contribution to LHC construction and built by the US-LHC collaboration (hence the Fermilab logo); with l. to r. Dr Mildred Dresselhaus, Dr Carlo Wyss, CERN Director General, Profesor Luciano Maiani, Professor Roger Cashmore, Ambassador George Moose, Dr Peter Rosen, Dr John Ellis. Photo 02 : Mr. Bill Richardson (right), Secretary of Energy United States of America with Prof. Luciano Maiani leaning over one of the LHC magnets produced at Fermilab during his visit to CERN on 16th September 2000.

  14. SUB-LEU-METAL-THERM-001 SUBCRITICAL MEASUREMENTS OF LOW ENRICHED TUBULAR URANIUM METAL FUEL ELEMENTS BEFORE & AFTER IRRADIATION

    Energy Technology Data Exchange (ETDEWEB)

    SCHWINKENDORF, K.N.

    2006-05-12

    With the shutdown of the Hanford PUREX (Plutonium-Uranium Extraction Plant) reprocessing plant in the 1970s, adequate storage capacity for spent Hanford N Reactor fuel elements in the K and N Reactor pools became a concern. To maximize space utilization in the pools, accounting for fuel burnup was considered. Calculations indicated that at typical fuel exposures for N Reactor, the spent-fuel critical mass would be twice the critical mass for green fuel. A decision was reached to test the calculational result with a definitive experiment. If the results proved positive, storage capacity could be increased and N Reactor operation could be prolonged. An experiment to be conducted in the N Reactor spent-fuel storage pool was designed and assembled and the services of the Battelle Northwest Laboratories (BNWL) (now Pacific Northwest National Laboratory [PNNL]) critical mass laboratory were procured for the measurements. The experiments were performed in April 1975 in the Hanford N Reactor fuel storage pool. The fuel elements were MKIA fuel assemblies, comprising two concentric tubes of low-enriched metallic uranium. Two separate sets of measurements were performed: one with ''green'' (fresh) fuel and one with spent fuel. Both the green and spent fuel, were measured in the same geometry. The spent-fuel MKIA assemblies had an average burnup of 2865 MWd (megawatt days)/t. A constraint was imposed restricting the measurements to a subcritical limit of k{sub eff} = 0.97. Subcritical count rate data was obtained with pulsed-neutron and approach-to-critical measurements. Ten (10) configurations with green fuel and nine (9) configurations with spent fuel are described and evaluated. Of these, 3 green fuel and 4 spent fuel loading configurations were considered to serve as benchmark models. However, shortcomings in experimental data failed to meet the high standards for a benchmark problem. Nevertheless, the data provided by these subcritical measurements can

  15. First reactivity determination of a subcritical reactor using a single beam-trip and fission chambers operating in current mode

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Ordonez, M.; Villamarin, D.; Becares, V.; Gonzalez-Romero, E.M. [Nuclear Innovation Group, CIEMAT, Avda. Complutense, Madrid (Spain); Bergloef, C. [Reactor Physics Department, Royal Institute of Technology, Stockholm (Sweden); Bournos, V.; Fokov, Y.; Kiyavitskaya, H. [Joint Institute for Power and Nuclear Research, National Academy of Sciences, Minsk (Belarus)

    2009-06-15

    Transmutation of spent nuclear fuel in Accelerator-Driven Systems (ADS) is considered as a key technology for achieving sustainable nuclear energy. In the design of future ADS facilities, the reactivity monitoring system is of highest importance. An extensive experimental program devoted to reactivity monitoring of ADS has been carried out at the subcritical facility YALINA-Booster in the framework of IP-EUROTRANS. The main objective, besides the qualification of the reactivity monitoring techniques, has been to develop electronic chains that can be used in a full power ADS. For this purpose, YALINA-Booster couples a D-T neutron generator to a flexible zero-power subcritical assembly with a coupled fast-thermal neutron spectrum. The high intensity of the accelerator and the possibility to work in continuous or pulsed mode allowed the study of the current-to-flux relationship and beam-trip experiments. In addition, the experimental facility provided the opportunity to test electronic chains in current mode, which correspond to the most probable condition in a full power ADS. There exists a relationship between the reactivity of a subcritical core, the intensity of the accelerator and the neutron source intensity. Hence, by monitoring these three quantities it should be possible to determine the origin of any reactivity or power change within the subcritical assembly. We have developed the necessary acquisition system to monitor the conditions of these three variables in the millisecond scale. The current-to-flux technique provides relative changes in the behavior of the core, however, in order to determine absolute values of the reactivity, we have taken profit of short imposed beam interruptions in the millisecond scale, thus providing the possibility for applying the Source-Jerk method within few milliseconds. It is the first time that the reactivity of an ADS is determined in a single beam-trip using fission chambers operating in current mode. The experiments

  16. SIMPLE METHOD FOR ESTIMATING POLYCHLORINATED BIPHENYL CONCENTRATIONS ON SOILS AND SEDIMENTS USING SUBCRITICAL WATER EXTRACTION COUPLED WITH SOLID-PHASE MICROEXTRACTION. (R825368)

    Science.gov (United States)

    A rapid method for estimating polychlorinated biphenyl (PCB) concentrations in contaminated soils and sediments has been developed by coupling static subcritical water extraction with solid-phase microextraction (SPME). Soil, water, and internal standards are placed in a seale...

  17. Short communication: antiviral activity of subcritical water extract of Brassica juncea against influenza virus A/H1N1 in nonfat milk

    National Research Council Canada - National Science Library

    Lee, N-K; Lee, J-H; Lim, S-M; Lee, K A; Kim, Y B; Chang, P-S; Paik, H-D

    2014-01-01

    Subcritical water extract (SWE) of Brassica juncea was studied for antiviral effects against influenza virus A/H1N1 and for the possibility of application as a nonfat milk supplement for use as an "antiviral food...

  18. The history of NATO TNF policy: The role of studies, analysis and exercises conference proceedings. Volume 3: Papers by Gen. Robert C. Richardson III (Ret.)

    Energy Technology Data Exchange (ETDEWEB)

    Rinne, R.L. [ed.

    1994-02-01

    This conference was organized to study and analyze the role of simulation, analysis, modeling, and exercises in the history of NATO policy. The premise was not that the results of past studies will apply to future policy, but rather that understanding what influenced the decision process-and how-would be of value. The structure of the conference was built around discussion panels. The panels were augmented by a series of papers and presentations focusing on particular TNF events, issues, studies, or exercises. The conference proceedings consist of three volumes. Volume 1 contains the conference introduction, agenda, biographical sketches of principal participants, and analytical summary of the presentations and discussion panels. Volume 2 contains a short introduction and the papers and presentations from the conference. This volume contains selected papers by Brig. Gen. Robert C. Richardson III (Ret.).

  19. Increasing SLEDed Linac Gradient

    Energy Technology Data Exchange (ETDEWEB)

    Farkas, Zoltan D

    2001-11-08

    This note will show how to increase the SLED [1] gradient by varying Q{sub e}, the external Q of the SLED cavity, by increasing its Q{sub 0} and by increasing the compression ratio. If varying the external Q is to be effective, then the copper losses should be small so that Q{sub 0} >> Q{sub e}. Methods of varying Q{sub e} will be indicated but no experimental data will be presented. If we increase the klystron pulse width from 3.5 to 5 {micro}S and increase Q{sub 0} from the present 100000 to 300000, then the gradient increases by 19% and the beam energy increases from 50 to 60 GeV. This note will also discuss SLED operation at 11424 MHz, the NLC frequency. Without Q{sub e} switching, using SLED at 11424 MHz increases the SLAC gradient from 21 MV/m to 34 MV/m, and at the same repetition rate, uses about 1/5 of rf average power. If we also double the compression ratio, we reach 47 MV/m and over 100 GeV beam energy.

  20. Implementation and qualification of neutronic calculation methodology in subcritical reactors driven by external neutron sources and applications

    OpenAIRE

    Thiago Carluccio

    2011-01-01

    O trabalho teve como objetivo a investigação de Metodologias de Cálculo dos Reatores Subcríticos acionados por fonte externa de nêutrons, tais como, \\"Accelerator Driven Subcritical Reactor\\" (ADSR) e \\"Fusion Driven Subcritical Reator\\" (FDSR) , que são reatores nucleares subcríticos com uma fonte externa de nêutrons. Tais nêutrons são produzidos, no caso do ADSR, através da interação de partículas aceleradas (prótons, deutério) com um alvo (Pb, Bi, etc) ou através das reações de fusão, no c...

  1. Ginger and turmeric starches hydrolysis using subcritical water + CO2: the effect of the SFE pre-treatment

    Directory of Open Access Journals (Sweden)

    S. R. M. Moreschi

    2006-06-01

    Full Text Available In this work, the hydrolysis of fresh and dried turmeric (Curcuma longa L. and ginger (Zingiber officinale R. in the presence of subcritical water + CO2 was studied. The hydrolysis of ginger and turmeric bagasses from supercritical fluid extraction was also studied. The reactions were done using subcritical water and CO2 at 150 bar, 200 °C and reaction time of 11 minutes; the degree of reaction was monitored through the amount of starch hydrolyzed. Process yields were calculated using the amount of reducing and total sugars formed. The effects of supercritical fluid extraction in the starchy structures were observed by scanning electron microscopy. Higher degree of hydrolysis (97- 98 % were obtained for fresh materials and the highest total sugar yield (74% was established for ginger bagasse. The supercritical fluid extraction did not significantly modify the degree of hydrolysis in the tested conditions.

  2. Application of the Modified Source Multiplication (MSM) Technique to Subcritical Reactivity Worth Measurements in Thermal and Fast Reactor Systems

    Science.gov (United States)

    Blaise, Patrick; Mellier, Frédéric; Fougeras, Philippe

    2011-06-01

    The Amplified Source Multiplication (ASM) method and its improved Modified Source Multiplication (MSM) method have been widely used in the CEA's EOLE and MASURCA critical facilities over the past decades for the determination of reactivity worths by using fission chambers in subcritical configurations. The ASM methodology uses relatively simple relationships between count rates of efficient miniature fission chambers located in slightly subcritical reference and perturbed configurations. While this method works quite well for small reactivity variations, the raw results need to be corrected to take into account the flux perturbation at the fission chamber location. This is performed by applying to the measurement a correction factor called MSM. This paper describes in detail both methodologies, with their associated uncertainties. Applications on absorber cluster worth in the MISTRAL-4 full MOX mock-up core and the last core loaded in MASURCA show the importance of the MSM correction on raw ASM data.

  3. Analysis of the Temporal Response of Coupled Asymmetrical Zero-Power Subcritical Bare Metal Reactor Systems

    Energy Technology Data Exchange (ETDEWEB)

    Klain, Kimberly L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-06-21

    The behavior of symmetrical coupled-core systems has been extensively studied, yet there is a dearth of research on asymmetrical systems due to the increased complexity of the analysis of such systems. In this research, the multipoint kinetics method is applied to asymmetrical zeropower, subcritical, bare metal reactor systems. Existing research on asymmetrical reactor systems assumes symmetry in the neutronic coupling; however, it will be shown that this cannot always be assumed. Deep subcriticality adds another layer of complexity and requires modification of the multipoint kinetics equations to account for the effect of the external neutron source. A modified set of multipoint kinetics equations is derived with this in mind. Subsequently, the Rossi-alpha equations are derived for a two-region asymmetrical reactor system. The predictive capabilities of the radiation transport code MCNP6 for neutron noise experiments are shown in a comparison to the results of a series of Rossi-alpha measurements performed by J. Mihalczo utilizing a coupled set of symmetrical bare highly-enriched uranium (HEU) cylinders. The ptrac option within MCNP6 can generate time-tagged counts in a cell (list-mode data). The list-mode data can then be processed similarly to measured data to obtain values for system parameters such as the dual prompt neutron decay constants observable in a coupled system. The results from the ptrac simulations agree well with the historical measured values. A series of case studies are conducted to study the effects of geometrical asymmetry in the coupling between two bare metal HEU cylinders. While the coupling behavior of symmetrical systems has been reported on extensively, that of asymmetrical systems remains sparse. In particular, it appears that there has been no previous research in obtaining the coupling time constants for asymmetrically-coupled systems. The difficulty in observing such systems is due in part to the inability to determine the

  4. Recovery of solid fuel from municipal solid waste by hydrothermal treatment using subcritical water

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, In-Hee, E-mail: hwang@eng.hokudai.ac.jp [Laboratory of Solid Waste Disposal Engineering, Faculty of Engineering, Hokkaido University, Kita 13 Nishi 8, Kita-ku, Sapporo 060 8628 (Japan); Aoyama, Hiroya; Matsuto, Toshihiko; Nakagishi, Tatsuhiro; Matsuo, Takayuki [Laboratory of Solid Waste Disposal Engineering, Faculty of Engineering, Hokkaido University, Kita 13 Nishi 8, Kita-ku, Sapporo 060 8628 (Japan)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer Hydrothermal treatment using subcritical water was studied to recover solid fuel from MSW. Black-Right-Pointing-Pointer More than 75% of carbon in MSW was recovered as char. Black-Right-Pointing-Pointer Heating value of char was comparable to that of brown coal and lignite. Black-Right-Pointing-Pointer Polyvinyl chloride was decomposed at 295 Degree-Sign C and 8 MPa and was removed by washing. - Abstract: Hydrothermal treatments using subcritical water (HTSW) such as that at 234 Degree-Sign C and 3 MPa (LT condition) and 295 Degree-Sign C and 8 MPa (HT condition) were investigated to recover solid fuel from municipal solid waste (MSW). Printing paper, dog food (DF), wooden chopsticks, and mixed plastic film and sheets of polyethylene, polypropylene, and polystyrene were prepared as model MSW components, in which polyvinylchloride (PVC) powder and sodium chloride were used to simulate Cl sources. While more than 75% of carbon in paper, DF, and wood was recovered as char under both LT and HT conditions, plastics did not degrade under either LT or HT conditions. The heating value (HV) of obtained char was 13,886-27,544 kJ/kg and was comparable to that of brown coal and lignite. Higher formation of fixed carbon and greater oxygen dissociation during HTSW were thought to improve the HV of char. Cl atoms added as PVC powder and sodium chloride to raw material remained in char after HTSW. However, most Cl originating from PVC was found to converse into soluble Cl compounds during HTSW under the HT condition and could be removed by washing. From these results, the merit of HTSW as a method of recovering solid fuel from MSW is considered to produce char with minimal carbon loss without a drying process prior to HTSW. In addition, Cl originating from PVC decomposes into soluble Cl compound under the HT condition. The combination of HTSW under the HT condition and char washing might improve the quality of char as alternative fuel.

  5. Extraction of Fenugreek (Trigonella foenum-graceum L.) Seed Oil Using Subcritical Butane: Characterization and Process Optimization.

    Science.gov (United States)

    Gu, Ling-Biao; Liu, Xiao-Ning; Liu, Hua-Min; Pang, Hui-Li; Qin, Guang-Yong

    2017-02-02

    In this study, the subcritical butane extraction process of fenugreek seed oil was optimized using response surface methodology with a Box-Behnken design. The optimum conditions for extracted oil from fenugreek seed was as follows: extraction temperature of 43.24 °C , extraction time of 32.80 min, and particle size of 0.26 mm. No significant differences were found between the experimental and predicted values. The physical and chemical properties of the oil showed that the oil could be used as edible oil. Fatty acid composition of oils obtained by subcritical butane under the optimum conditions and by accelerated solvent extraction showed negligible difference. The oils were rich in linoleic acid (42.71%-42.80%), linolenic acid (26.03%-26.15%), and oleic acid (14.24%-14.40%). The results revealed that the proposed method was feasible, and this essay shows the way to exploit fenugreek seeds by subcritical butane extraction under the scope of edible oils.

  6. Production of medical radioactive isotopes using KIPT electron driven subcritical facility.

    Science.gov (United States)

    Talamo, Alberto; Gohar, Yousry

    2008-05-01

    Kharkov Institute of Physics and Technology (KIPT) of Ukraine in collaboration with Argonne National Laboratory (ANL) has a plan to construct an electron accelerator driven subcritical assembly. One of the facility objectives is the production of medical radioactive isotopes. This paper presents the ANL collaborative work performed for characterizing the facility performance for producing medical radioactive isotopes. First, a preliminary assessment was performed without including the self-shielding effect of the irradiated samples. Then, more detailed investigation was carried out including the self-shielding effect, which defined the sample size and location for producing each medical isotope. In the first part, the reaction rates were calculated as the multiplication of the cross section with the unperturbed neutron flux of the facility. Over fifty isotopes have been considered and all transmutation channels are used including (n, gamma), (n, 2n), (n, p), and (gamma, n). In the second part, the parent isotopes with high reaction rate were explicitly modeled in the calculations. Four irradiation locations were considered in the analyses to study the medical isotope production rate. The results show the self-shielding effect not only reduces the specific activity but it also changes the irradiation location that maximizes the specific activity. The axial and radial distributions of the parent capture rates have been examined to define the irradiation sample size of each parent isotope.

  7. CFD Analysis and Design of Detailed Target Configurations for an Accelerator-Driven Subcritical System

    Energy Technology Data Exchange (ETDEWEB)

    Kraus, Adam; Merzari, Elia; Sofu, Tanju; Zhong, Zhaopeng; Gohar, Yousry

    2016-08-01

    High-fidelity analysis has been utilized in the design of beam target options for an accelerator driven subcritical system. Designs featuring stacks of plates with square cross section have been investigated for both tungsten and uranium target materials. The presented work includes the first thermal-hydraulic simulations of the full, detailed target geometry. The innovative target cooling manifold design features many regions with complex flow features, including 90 bends and merging jets, which necessitate three-dimensional fluid simulations. These were performed using the commercial computational fluid dynamics code STAR-CCM+. Conjugate heat transfer was modeled between the plates, cladding, manifold structure, and fluid. Steady-state simulations were performed but lacked good residual convergence. Unsteady simulations were then performed, which converged well and demonstrated that flow instability existed in the lower portion of the manifold. It was established that the flow instability had little effect on the peak plate temperatures, which were well below the melting point. The estimated plate surface temperatures and target region pressure were shown to provide sufficient margin to subcooled boiling for standard operating conditions. This demonstrated the safety of both potential target configurations during normal operation.

  8. Recycling high-performance carbon fiber reinforced polymer composites using sub-critical and supercritical water

    Science.gov (United States)

    Knight, Chase C.

    Carbon fiber reinforced plastics (CFRP) are composite materials that consist of carbon fibers embedded in a polymer matrix, a combination that yields materials with properties exceeding the individual properties of each component. CFRP have several advantages over metals: they offer superior strength to weight ratios and superior resistance to corrosion and chemical attack. These advantages, along with continuing improvement in manufacturing processes, have resulted in rapid growth in the number of CFRP products and applications especially in the aerospace/aviation, wind energy, automotive, and sporting goods industries. Due to theses well-documented benefits and advancements in manufacturing capabilities, CFRP will continue to replace traditional materials of construction throughout several industries. However, some of the same properties that make CFRP outstanding materials also pose a major problem once these materials reach the end of service life. They become difficult to recycle. With composite consumption in North America growing by almost 5 times the rate of the US GDP in 2012, this lack of recyclability is a growing concern. As consumption increases, more waste will inevitably be generated. Current composite recycling technologies include mechanical recycling, thermal processing, and chemical processing. The major challenge of CFRP recycling is the ability to recover materials of high-value and preserve their properties. To this end, the most suitable technology is chemical processing, where the polymer matrix can be broken down and removed from the fiber, with limited damage to the fibers. This can be achieved using high concentration acids, but such a process is undesirable due to the toxicity of such materials. A viable alternative to acid is water in the sub-critical and supercritical region. Under these conditions, the behavior of this abundant and most environmentally friendly solvent resembles that of an organic compound, facilitating the breakdown

  9. High-pressure cell for neutron reflectometry of supercritical and subcritical fluids at solid interfaces.

    Science.gov (United States)

    Carmichael, Justin R; Rother, Gernot; Browning, James F; Ankner, John F; Banuelos, Jose L; Anovitz, Lawrence M; Wesolowski, David J; Cole, David R

    2012-04-01

    A new high-pressure cell design for use in neutron reflectometry (NR) for pressures up to 50 MPa and a temperature range of 300-473 K is described. The cell design guides the neutron beam through the working crystal without passing through additional windows or the bulk fluid, which provides for a high neutron transmission, low scattering background, and low beam distortion. The o-ring seal is suitable for a wide range of subcritical and supercritical fluids and ensures high chemical and pressure stability. Wafers with a diameter of 5.08 cm (2 in.) and 5 mm or 10 mm thickness can be used with the cells, depending on the required pressure and momentum transfer range. The fluid volume in the sample cell is very small at about 0.1 ml, which minimizes scattering background and stored energy. The cell design and pressure setup for measurements with supercritical fluids are described. NR data are shown for silicon/silicon oxide and quartz wafers measured against air and subsequently within the high-pressure cell to demonstrate the neutron characteristics of the high-pressure cell. Neutron reflectivity data for supercritical CO(2) in contact with quartz and Si/SiO(2) wafers are also shown. © 2012 American Institute of Physics

  10. Complete degradation of Orange G by electrolysis in sub-critical water.

    Science.gov (United States)

    Yuksel, Asli; Sasaki, Mitsuru; Goto, Motonobu

    2011-06-15

    Complete degradation of azo dye Orange G was studied using a 500 mL continuous flow reactor made of SUS 316 stainless steel. In this system, a titanium reactor wall acted as a cathode and a titanium plate-type electrode was used as an anode in a subcritical reaction medium. This hydrothermal electrolysis process provides an environmentally friendly route that does not use any organic solvents or catalysts to remove organic pollutants from wastewater. Reactions were carried out from 30 to 90 min residence times at a pressure of 7 MPa, and at different temperatures of 180-250°C by applying various direct currents ranging from 0.5 to 1A. Removal of dye from the product solution and conversion of TOC increased with increasing current value. Moreover, the effect of salt addition on degradation of Orange G and TOC conversion was investigated, because in real textile wastewater, many salts are also included together with dye. Addition of Na(2)CO(3) resulted in a massive degradation of the dye itself and complete mineralization of TOC, while NaCl and Na(2)SO(4) obstructed the removal of Orange G. Greater than 99% of Orange G was successfully removed from the product solution with a 98% TOC conversion. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Vortex-Induced Vibration Tests of a Marine Growth Wrapped Cylinder at Subcritical Reynolds Number

    Directory of Open Access Journals (Sweden)

    Kurian V. J.

    2017-01-01

    Full Text Available Vortex Induced Vibrations (VIV may cause great damage to deep water risers. Estimation of accurate hydrodynamic coefficients and response amplitudes for fouled tubular cylinders subjected to VIVs is a complex task. This paper presents the results of an extensive experimental investigation on in-line and cross-flow forces acting on cylinders wrapped with marine growth, subjected to current at Subcritical Reynolds Number. The drag and lift force coefficients have been determined through the use of the Fast Fourier Analysis methods. The different tests were conducted in the offshore engineering laboratory at Universiti Teknologi PETRONAS (UTP, Malaysia. In this study, a cylinder with outer diameter Do = 27 mm, fixed at top as cantilever beam was used. The in-line and cross-flow forces were measured using VIV Force Totaller (VIVFT. VIVFT is a two degree of freedom (2DOF forces sensor developed by UTP to measure the VIV forces. The tests were conducted for current velocity varied between 0.118 to 0.59 m/s. The test results suggest that the cylinder wrapped with marine growth has shown an overall increase in drag and inertia coefficients as well as on response amplitudes.

  12. Hydrothermal liquefaction of Spirulina and Nannochloropsis salina under subcritical and supercritical water conditions.

    Science.gov (United States)

    Toor, Saqib S; Reddy, Harvind; Deng, Shuguang; Hoffmann, Jessica; Spangsmark, Dorte; Madsen, Linda B; Holm-Nielsen, Jens Bo; Rosendahl, Lasse A

    2013-03-01

    Six hydrothermal liquefaction experiments on Nannochloropsis salina and Spirulina platensis at subcritical and supercritical water conditions (220–375 °C, 20–255 bar) were carried out to explore the feasibility of extracting lipids from wet algae, preserving nutrients in lipid-extracted algae solid residue, and recycling process water for algae cultivation. GC–MS, elemental analyzer, FT-IR, calorimeter and nutrient analysis were used to analyze bio-crude, lipid-extracted algae and water samples produced in the hydrothermal liquefaction process. The highest bio-crude yield of 46% was obtained on N. salina at 350 °C and 175 bar. For S. platensis algae sample, the optimal hydrothermal liquefaction condition appears to be at 310 °C and 115 bar, while the optimal condition for N. salina is at 350 °C and 175 bar. Preliminary data also indicate that a lipid-extracted algae solid residue sample obtained in the hydrothermal liquefaction process contains a high level of proteins. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Energy conversion of biomass with supercritical and subcritical water using large-scale plants.

    Science.gov (United States)

    Okajima, Idzumi; Sako, Takeshi

    2014-01-01

    Exploiting unused or waste biomass as an alternative fuel is currently receiving much attention because of the potential reductions in CO2 emissions and the lower cost in comparison to expensive fossil fuels. If we are to use biomass domestically or industrially, we must be able to convert biomass to high-quality and easy-to-use liquid, gas, or solid fuels that have high-calorific values, low moisture and ash contents, uniform composition, and suitable for stored over long periods. In biomass treatment, hot and high-pressure water including supercritical and subcritical water is an excellent solvent, as it is clean and safe and its action on biomass can be optimized by varying the temperature and pressure. In this article, the conversion of waste biomass to fuel using hot and high-pressure water is reviewed, and the following examples are presented: the production of large amounts of hydrogen from waste biomass, the production of cheap bioethanol from non-food raw materials, and the production of composite powder fuel from refractory waste biomass in the rubble from the Great East Japan Earthquake. Several promising techniques for the conversion of biomass have been demonstrated in large-scale plants and commercial deployment is expected in the near future. Copyright © 2013. Published by Elsevier B.V.

  14. Subcritical Butane Extraction of Wheat Germ Oil and Its Deacidification by Molecular Distillation

    Directory of Open Access Journals (Sweden)

    Jinwei Li

    2016-12-01

    Full Text Available Extraction and deacidification are important stages for wheat germ oil (WGO production. Crude WGO was extracted using subcritical butane extraction (SBE and compared with traditional solvent extraction (SE and supercritical carbon dioxide extraction (SCE based on the yield, chemical index and fatty acid profile. Furthermore, the effects of the molecular distillation temperature on the quality of WGO were also investigated in this study. Results indicated that WGO extracted by SBE has a higher yield of 9.10% and better quality; at the same time, its fatty acid composition has no significant difference compared with that of SE and SCE. The molecular distillation experiment showed that the acid value, peroxide value and p-anisidine value of WGO were reduced with the increase of the evaporation temperatures, and the contents of the active constituents of tocopherol, polyphenols and phytosterols are simultaneously decreased. Generally, the distillation temperature of 150 °C is an appropriate condition for WGO deacidification with the higher deacidification efficiency of 77.78% and the higher retention rate of active constituents.

  15. Studies on subcritical and overcritical density laser ablated TAC foam targets

    Science.gov (United States)

    Chaurasia, S.; Leshma, P.; Murali, C. G.; Borisenko, N. G.; Munda, D. S.; Orekhov, A.; Gromov, A. I.; Merkuliev, Yu. A.; Dhareshwar, L. J.

    2015-05-01

    In this paper, the interaction of high power laser with low density polymer foam with density as low as 2 mg/cm3, 4 mg/cm3, 20 mg/cm3 30 mg/cm3 and 50 mg/cm3 targets are investigated and compared with solid polymer targets. An understanding of such interaction is important from fusion research point of view. Low density foam coating of fusion capsule has been proposed in order to smooth in direct drive scheme and also it is being used as efficient x-ray converter in indirect drive scheme. It is observed that about 75-80% of the laser energy is absorbed in the subcritical (with density case is almost two times that measured in the over dense (supper critical) targets. The optical shadowgraphy of the targets shows that the laser coupling in low density foam is associated with a supersonic heat wave while, with increasing density this phenomenon is replaced by subsonic absorption and shock formation. In the case of a 50 mg/cm3 foams the foil velocity reduced by 35% (i.e. 5×106 cm/s), which further reduced to 3.8×106 cm/s in case solid polymer targets.

  16. Particle formation of budesonide from alcohol-modified subcritical water solutions.

    Science.gov (United States)

    Carr, Adam G; Mammucari, Raffaella; Foster, Neil R

    2011-02-28

    Recently, subcritical water (SBCW: water that has been heated to a temperature between 100°C and 200°C at pressures of up to 70bar) has been used to dissolve several hydrophobic pharmaceutical compounds (Carr et al., 2010a). Furthermore, a number of active pharmaceutical ingredients (APIs) have been rapidly precipitated from SBCW solutions (Carr et al., 2010b,c). It is possible to alter the precipitate morphology by altering the processing variables; including the SBCW-API solution injection temperature and adding impurities (such as pharmaceutical excipients, e.g. lactose) to the precipitation chamber. The work presented in this article demonstrates that the morphology of pharmaceutical particles can be tuned by adding organic solvents (ethanol and methanol) to the SBCW-API solutions. Particle morphology has also been tuned by adding different pharmaceutical excipients (polyethylene glycol 400 and lactose) to the precipitation chamber. Different morphologies of pharmaceutical particles were produced, ranging from nanospheres of 60nm diameter to 5μm plate particles. Budesonide was used as the model API in this study. Two experimental products were spray dried to form dry powder products. The aerodynamic particle size of the powder was established by running the powder through an Andersen Cascade Impactor. It has been shown that the drug particles produced from the SBCW micronization process, when coupled with a spray drying process, are suitable for delivery to the lungs. Copyright © 2010 Elsevier B.V. All rights reserved.

  17. Polyethylene-reflected plutonium metal sphere : subcritical neutron and gamma measurements.

    Energy Technology Data Exchange (ETDEWEB)

    Mattingly, John K.

    2009-11-01

    Numerous benchmark measurements have been performed to enable developers of neutron transport models and codes to evaluate the accuracy of their calculations. In particular, for criticality safety applications, the International Criticality Safety Benchmark Experiment Program (ICSBEP) annually publishes a handbook of critical and subcritical benchmarks. Relatively fewer benchmark measurements have been performed to validate photon transport models and codes, and unlike the ICSBEP, there is no program dedicated to the evaluation and publication of photon benchmarks. Even fewer coupled neutron-photon benchmarks have been performed. This report documents a coupled neutron-photon benchmark for plutonium metal reflected by polyethylene. A 4.5-kg sphere of ?-phase, weapons-grade plutonium metal was measured in six reflected configurations: (1) Bare; (2) Reflected by 0.5 inch of high density polyethylene (HDPE); (3) Reflected by 1.0 inch of HDPE; (4) Reflected by 1.5 inches of HDPE; (5) Reflected by 3.0 inches of HDPE; and (6) Reflected by 6.0 inches of HDPE. Neutron and photon emissions from the plutonium sphere were measured using three instruments: (1) A gross neutron counter; (2) A neutron multiplicity counter; and (3) A high-resolution gamma spectrometer. This report documents the experimental conditions and results in detail sufficient to permit developers of radiation transport models and codes to construct models of the experiments and to compare their calculations to the measurements. All of the data acquired during this series of experiments are available upon request.

  18. High-pressure cell for neutron reflectometry of supercritical and subcritical fluids at solid interfaces

    Science.gov (United States)

    Carmichael, Justin R.; Rother, Gernot; Browning, James F.; Ankner, John F.; Banuelos, Jose L.; Anovitz, Lawrence M.; Wesolowski, David J.; Cole, David R.

    2012-04-01

    A new high-pressure cell design for use in neutron reflectometry (NR) for pressures up to 50 MPa and a temperature range of 300-473 K is described. The cell design guides the neutron beam through the working crystal without passing through additional windows or the bulk fluid, which provides for a high neutron transmission, low scattering background, and low beam distortion. The o-ring seal is suitable for a wide range of subcritical and supercritical fluids and ensures high chemical and pressure stability. Wafers with a diameter of 5.08 cm (2 in.) and 5 mm or 10 mm thickness can be used with the cells, depending on the required pressure and momentum transfer range. The fluid volume in the sample cell is very small at about 0.1 ml, which minimizes scattering background and stored energy. The cell design and pressure setup for measurements with supercritical fluids are described. NR data are shown for silicon/silicon oxide and quartz wafers measured against air and subsequently within the high-pressure cell to demonstrate the neutron characteristics of the high-pressure cell. Neutron reflectivity data for supercritical CO2 in contact with quartz and Si/SiO2 wafers are also shown.

  19. Subcritical water extraction and characterization of bioactive compounds from Haematococcus pluvialis microalga.

    Science.gov (United States)

    Rodríguez-Meizoso, I; Jaime, L; Santoyo, S; Señoráns, F J; Cifuentes, A; Ibáñez, E

    2010-01-20

    In this work, extraction and characterization of compounds with antioxidant and antimicrobial activity from Haematococcus pluvialis microalga in red phase have been carried out. To do this, subcritical water extraction (SWE) has been combined with analytical techniques such as HPLC-DAD, HPLC-QqQ-MS and GC-MS and in vitro assays (i.e., for antioxidant and antimicrobial activity). The effect of the extraction temperature (50, 100, 150 and 200 degrees C) and solvent polarity has been studied in terms of yield and activity of the extracts. Results demonstrate that the extraction temperature has a positive influence in the extraction yield and antioxidant activity. Thus, the extraction yield achieved with this process was higher than 30% of dry weight at 200 degrees C as extraction temperature. Moreover, the extract obtained at 200 degrees C presented the highest antioxidant activity by far, while temperature does not seem to significatively affect the antimicrobial activity. Chemical composition was determined by HPLC-DAD, HPLC-QqQ-MS and GC-MS. Short chain fatty acids turned out to be responsible of the antimicrobial activity, whereas the antioxidant activity was correlated to vitamin E (present exclusively in the 200 degrees C extract), together with simple phenols, caramelization products and possible Maillard reaction products obtained during the extraction at high temperatures.

  20. High performance curcumin subcritical water extraction from turmeric (Curcuma longa L.).

    Science.gov (United States)

    Valizadeh Kiamahalleh, Mohammad; Najafpour-Darzi, Ghasem; Rahimnejad, Mostafa; Moghadamnia, Ali Akbar; Valizadeh Kiamahalleh, Meisam

    2016-06-01

    Curcumin is a hydrophobic polyphenolic compound derived from turmeric rhizome, which consists about 2-5% of the total rhizome content and is a more valuable component of turmeric. For reducing the drawbacks of conventional extraction (using organic solvents) of curcumin, the water as a clean solvent was used for extracting curcumin. Subcritical water extraction (SWE) experimental setup was fabricated in a laboratory scale and the influences of some parameters (e.g. extraction temperature, particle size, retention time and pressure) on the yield of extraction were investigated. Optimum extraction conditions such as SWE pressure of 10bar, extractive temperature of 140°C, particle size of 0.71mm and retention time of 14min were defined. The maximum amount of curcumin extracted at the optimum condition was 3.8wt%. The yield of curcumin extraction was more than 76wt% with regards to the maximum possible curcumin content of turmeric, as known to be 5%. The scanning electron microscope (SEM) images from the outer surface of turmeric, before and after extraction, clearly demonstrated the effect of each parameter; changes in porosity and hardness of turmeric that is directly related to the amount of extracted curcumin in process optimization of the extraction parameters. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. The TRADE experiment: shielding calculations for the building hosting the subcritical system.

    Science.gov (United States)

    Burn, K W; Carta, M; Casalini, L; Kadi, Y; Monti, S; Nava, E; Palomba, M; Petrovich, C; Picardi, L; Rubbia, C; Troiani, F

    2005-01-01

    The TRADE project (TRiga Accelerator Driven Experiment), to be performed at the existing TRIGA reactor at ENEA Casaccia, has been proposed as a validation of the accelerator-driven system (ADS) concept. TRADE will be the first experiment in which the three main components of an ADS--the accelerator, spallation target and sub-critical blanket--are coupled at a power level sufficient to encounter reactivity feedback effects. As such, TRADE represents the necessary intermediate step in the development of hybrid transmutation systems, its expected outcomes being considered crucial--in terms of proof of stability of operation, dynamic behaviour and licensing issues--for the subsequent realisation of an ADS Transmutation Demonstrator. An essential role in the feasibility study of the experiment is played by radioprotection calculations. Such a system exhibits new characteristics with respect to a traditional reactor, owing to the presence of the proton accelerator. As beam losses always occur under normal operating conditions of an accelerator, shielding studies need to be performed not only around the reactor but also along the beam line from the accelerator to the spallation target. This paper illustrates a preliminary evaluation, using Monte Carlo methods, of the additional shielding to be located around the reactor structures, the beam transport line and the existing reactor building to allow access into the reactor hall and to restrict the doses outside to their legal limits.

  2. Optimization of subcritical water extraction of polysaccharides from Grifola frondosa using response surface methodology

    Science.gov (United States)

    Yang, Liuqing; Qu, Hongyuan; Mao, Guanghua; Zhao, Ting; Li, Fang; Zhu, Bole; Zhang, Bingtao; Wu, Xiangyang

    2013-01-01

    Background: This research is among the few that has been conducted on the feasibility of subcritical water extraction (SWE) as a rapid and efficient extraction tool for polysaccharides. Objective: The aim of the study was to extractand optimize the parameter conditions of SWE of polysaccharides from Grifola frondosa using response surface methodology. Materials and Methods: In the study, SWEwas applied to extractbioactive compounds from G. frondosa. A preliminary analysis was made on the physical properties and content determination of extracts using SWE and hot water extraction (HWE). Analysis of the sample residues and antioxidant activities of the polysaccharides extracted by SWE and HWE were then evaluated. Results: The optimal extraction conditions include: extraction temperature of 210°C, extraction time of 43.65 min and the ratio of water to raw material of 26.15:1. Under these optimal conditions, the experimental yield of the polysaccharides (25.1 ± 0.3%) corresponded with the mean value predicted by the model and two times more than the mean value obtained by the traditional HWE. The antioxidant activities of polysaccharides extracted by SWE were generally higher than those extracted by HWE. From the study, the SWE technology could be a time-saving, high yield, and bioactive technique for production of polysaccharides. PMID:23772107

  3. The effect of a hydroxyapatite impregnated PCL membrane in rat subcritical calvarial bone defects.

    Science.gov (United States)

    Groppo, Monica Feresini; Caria, Paulo Henrique; Freire, Alexandre Rodrigues; Figueroba, Sidney R; Ribeiro-Neto, Wilson Alves; Bretas, Rosario Elida Suman; Prado, Felippe Bevilacqua; Haiter-Neto, Francisco; Aguiar, Flavio Henrique; Rossi, Ana Claudia

    2017-10-01

    The present study evaluated the effect of polymeric-nanofibers membranes impregnated with microparticulate hydroxyapatite (HA) in the subcritical calvarial bone defects (SCBD) healing. PCL membranes with and without HA were obtained by electrospinning. SCBD were perforated (3.3mm) in left and right sides of 36 rat calvarias. The right-side SBCD of 18 animals was filled with HA mixed with blood clot and blood clot at the contralateral side. The remaining animals received PCL+HA membrane at the right-side SCBD and PCL membrane at the contralateral side. Animals were killed after 30, 60 and 90days after surgery. Bone defect volume (in mm3) was measured by tomography (CBCT). Qualitative histological analysis and SBCD area (in mm2) were measured. Quantitative data were submitted to Kruskal-Wallis/Dunn tests. Reduction of SBCD volume was observed in all treatments but PCL. Association with HA significantly improved bone healing induced by PCL and blood clot. PCL+HA induced the lowest SBCD volume at 60 and 90days. Complete bone healing was not observed even at 90days in SCBD treated with blood clot. In every period, more bone formation was observed for SCBD treated with membranes. We concluded that both PCL membrane and HA were able to improve bone healing. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Subcritical carbon dioxide-water hydrolysis of sugarcane bagasse pith for reducing sugars production.

    Science.gov (United States)

    Liang, Jiezhen; Chen, Xiaopeng; Wang, Linlin; Wei, Xiaojie; Wang, Huasheng; Lu, Songzhou; Li, Yunhua

    2017-03-01

    The aim of present study was to obtain total reducing sugars (TRS) by hydrolysis in subcritical CO2-water from sugarcane bagasse pith (SCBP), the fibrous residue remaining after papermaking from sugarcane bagasse. The optimum hydrolysis conditions were evaluated by L16(4(5)) orthogonal experiments. The TRS yield achieved 45.8% at the optimal conditions: 200°C, 40min, 500rmin(-1), CO2 initial pressure of 1MPa and liquid-to-solid ratio of 50:1. Fourier transform infrared spectrometry and two-dimensional heteronuclear single quantum coherence nuclear magnetic resonance were used to characterize hydrolysis liquor, treated and untreated SCBP, resulting in the removal of hemicelluloses to mainly produce xylose, glucose and arabinose during hydrolysis. The severity factors had no correlation to TRS yield, indicating that the simple kinetic processes of biomass solubilisation cannot perfectly describe the SCBP hydrolysis. The first-order kinetic model based on consecutive reaction was used to obtain rate constants, activation energies and pre-exponential factors. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Sugars and char formation on subcritical water hydrolysis of sugarcane straw.

    Science.gov (United States)

    Lachos-Perez, D; Tompsett, G A; Guerra, P; Timko, M T; Rostagno, M A; Martínez, Julian; Forster-Carneiro, T

    2017-11-01

    Subcritical water has potential as an environmentally friendly solvent for applications including hydrolysis, liquefaction, extraction, and carbonization. Here, we report hydrolysis of sugarcane straw, an abundant byproduct of sugar production, in a semi-continuous reactor at reaction temperatures ranging from 190 to 260°C and at operating pressures of 9 and 16MPa. The target hydrolysis products were total reducing sugars. The main products of sugarcane straw hydrolysis were glucose, xylose, arabinose, and galactose in addition to 5- hydroxymethylfurfural and furfural as minor byproducts. Fourier transform infrared spectroscopy and thermogravimetric analysis provided additional information on the surface and bulk composition of the residual biomass. Char was present on samples treated at temperatures equal to and greater than 190°C. Samples treated at 260°C contained approximately 20wt% char, yet retained substantial hemicellulose and cellulose content. Hydrolysis temperature of 200°C provided the greatest TRS yield while minimizing char formation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Subcritical co-solvents extraction of lipid from wet microalgae pastes of Nannochloropsis sp

    Science.gov (United States)

    Chen, Min; Liu, Tianzhong; Chen, Xiaolin; Chen, Lin; Zhang, Wei; Wang, Junfeng; Gao, Lili; Chen, Yu; Peng, Xiaowei

    2012-01-01

    In this paper subcritical co-solvents extraction (SCE) of algal lipid from wet pastes of Nannochloropsis sp. is examined. The influences of five operating parameters including the ratio between ethanol to hexane, the ratio of mixed solvents to algal biomass (dry weight), extraction temperature, pressure, and time were investigated. The determined optimum extraction conditions were 3:1 (hexane to ethanol ratio), 10:1 ratio (co-solvents to microalgae (dry weight) ratio), 90°C, 1.4 MPa, and 50 min, which could produce 88% recovery rate of the total lipids. In addition, electron micrographs of transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were conducted to show that the algal cell presented shrunken, collapsed with some wrinkles and microholes after SCE extraction. The main composition of total lipids extracted under the optimum conditions was TAG which represented more than 80%. And the fatty acid profile of triglycerides revealed that C16:0 (35.67 ± 0.2%), C18:1 (26.84 ± 0.044%) and C16:1 (25.96 ± 0.011%) were dominant. Practical applications: The reported method could save energy consumption significantly through avoiding deep dewatering (for example drying). The composition of the extracted lipid is suitable for the production of high quality biodiesel. PMID:22745570

  7. Microwave Assisted Extraction of Defatted Roselle (Hibiscus sabdariffa L. Seed at Subcritical Conditions with Statistical Analysis

    Directory of Open Access Journals (Sweden)

    N. I. Yusoff

    2017-01-01

    Full Text Available Roselle seeds are the waste product of roselle processing, but they are now labeled as a polyphenol source with great herbal quality. In this work, polyphenols were extracted using ethanol-water (70% (v/v in a closed vessel under microwave irradiation. The main objective was to determine the optimal parameters statistically. The influence of extraction time (4–10 min, microwave power (100–300 W, and solvent/solid ratio (25–100 mL/g was studied. The total phenolic and flavonoids content were determined using Folin-Ciocalteu and aluminum chloride methods, respectively. Without temperature control, the subcritical conditions could occur and the highest flavonoid content (14.4251 mg QE/g was achieved at 158°C and 16.4 bar. Although the optimum MAE conditions (10 min, 300 W, and 97.7178 mL/g resulted in the highest yield (65.0367% and phenolic content (18.2244 mg GAE/g, low flavonoids content (6.4524 mg QE/g was unexpectedly obtained due to degradation at 163°C.

  8. Subcritical Growth of Electron Phase-space Holes in Planetary Radiation Belts

    Science.gov (United States)

    Osmane, A.; Wilson, L. B., III; Turner, D. L.; Dimmock, A. P.; Pulkkinen, T. I.

    2017-12-01

    The discovery of self-sustained coherent structures with large-amplitude electric fields (E ˜ 10 - 100 mV/m) by the Van Allen Probes has revealed alternative routes through which energy-momentum exchange can take place in planetary radiation belts. When originating from energetic electrons in Landau resonance with large-amplitude whistlers, phase-space electron holes form with small amplitudes of the order of the hot to cold electron density, i.e., qφ/T_e≃ n_h/n_c ≃ 10^{-3}, and orders of magnitude smaller than observed values of the largest phase-space holes amplitude, i.e., qφ /T_e ≃ 1. In this report we present a mechanism through which electron holes can grow nonlinearly (i.e. γ ∝ √{φ}) and subcritically as a result of momentum exchange with passing (untrapped) electrons. Growth rates are computed analytically for plasma parameters consistent with those measured in the Earth's radiation belts under quiet and disturbed conditions. Our results provide an explanation for the fast growth of electron phase-space holes in the Earth's radiation belts from small initial values qφ/T_c ≃ 10^{-3}, to larger values of the order qφ /T_e ≃ 1.

  9. The Optimal Evaporation Temperature of Subcritical ORC Based on Second Law Efficiency for Waste Heat Recovery

    Directory of Open Access Journals (Sweden)

    Xiaoxiao Xu

    2012-03-01

    Full Text Available The subcritical Organic Rankine Cycle (ORC with 28 working fluids for waste heat recovery is discussed in this paper. The effects of the temperature of the waste heat, the critical temperature of working fluids and the pinch temperature difference in the evaporator on the optimal evaporation temperature (OET of the ORC have been investigated. The second law efficiency of the system is regarded as the objective function and the evaporation temperature is optimized by using the quadratic approximations method. The results show that the OET will appear for the temperature ranges investigated when the critical temperatures of working fluids are lower than the waste heat temperatures by 18 ± 5 K under the pinch temperature difference of 5 K in the evaporator. Additionally, the ORC always exhibits the OET when the pinch temperature difference in the evaporator is raised under the fixed waste heat temperature. The maximum second law efficiency will decrease with the increase of pinch temperature difference in the evaporator.

  10. Sub-critical crack growth in silicate glasses: Role of network topology

    Science.gov (United States)

    Smedskjaer, Morten M.; Bauchy, Mathieu

    2015-10-01

    The presence of water in the surrounding atmosphere can cause sub-critical crack growth (SCCG) in glasses, a phenomenon known as fatigue or stress corrosion. Here, to facilitate the compositional design of more fatigue-resistant glasses, we investigate the composition dependence of SCCG by studying fourteen silicate glasses. The fatigue curves (V-KI) have been obtained by indentation experiments through measurements of the crack length as a function of post-indentation fatigue duration. Interestingly, we find that the fatigue resistance parameter N is generally improved by increasing the alumina content and is thereby found to exhibit a fairly linear dependence on the measured Vickers hardness HV for a wide range of N and HV values. This finding highlights the important role of network topology in governing the SCCG in silicate glasses, since hardness has been shown to scale linearly with the number of atomic constraints. Our results therefore suggest that glasses showing under-constrained flexible networks, which feature floppy internal modes of deformation, are more readily attacked by water molecules, thus promoting stress corrosion and reducing the fatigue resistance.

  11. Efficient, high-speed methane fermentation for sewage sludge using subcritical water hydrolysis as pretreatment.

    Science.gov (United States)

    Yoshida, Hiroyuki; Tokumoto, Hayato; Ishii, Kyoko; Ishii, Ryo

    2009-06-01

    A novel biomass-energy process for the production of methane from sewage sludge using a subcritical water (sub-CW) hydrolysis reaction as pretreatment is proposed. The main substances of sewage sludge hydrolyzed by sub-CW at 513 K for 10 min were acetic acid, formic acid, pyroglutamic acid, alanine, and glycine. Fermentation experiments were conducted in an anaerobic-sludge reactor for two different samples: real sewage sludge and a model solution containing components typically produced by the sub-CW pretreatment of sewage sludge. In the experiment for the sub-CW pretreatment of sewage sludge, methane generation was twice that for non-pretreatment after 3 days of incubation. In the model experiment, the methane conversion was about 40% with the application of mixture of organic acids and amino acids after 5 days of incubation. Furthermore, the methane conversion was about 60% for 2 days when only organic acids, such as acetic acid and formic acid, were applied. Because acetic acid is the key intermediate and main precursor of the methanogenesis step, fermentation experiments were conducted in an anaerobic-sludge reactor with high concentrations of acetic acid (0.01-0.1M). Nearly 100% of acetic acid was converted to methane and carbon dioxide in 1-3 days.

  12. Subcritical Butane Extraction of Wheat Germ Oil and Its Deacidification by Molecular Distillation.

    Science.gov (United States)

    Li, Jinwei; Sun, Dewei; Qian, Lige; Liu, Yuanfa

    2016-12-07

    Extraction and deacidification are important stages for wheat germ oil (WGO) production. Crude WGO was extracted using subcritical butane extraction (SBE) and compared with traditional solvent extraction (SE) and supercritical carbon dioxide extraction (SCE) based on the yield, chemical index and fatty acid profile. Furthermore, the effects of the molecular distillation temperature on the quality of WGO were also investigated in this study. Results indicated that WGO extracted by SBE has a higher yield of 9.10% and better quality; at the same time, its fatty acid composition has no significant difference compared with that of SE and SCE. The molecular distillation experiment showed that the acid value, peroxide value and p-anisidine value of WGO were reduced with the increase of the evaporation temperatures, and the contents of the active constituents of tocopherol, polyphenols and phytosterols are simultaneously decreased. Generally, the distillation temperature of 150 °C is an appropriate condition for WGO deacidification with the higher deacidification efficiency of 77.78% and the higher retention rate of active constituents.

  13. Physics design of an accelerator for an accelerator-driven subcritical system

    Directory of Open Access Journals (Sweden)

    Zhihui Li

    2013-08-01

    Full Text Available An accelerator-driven subcritical system (ADS program was launched in China in 2011, which aims to design and build an ADS demonstration facility with the capability of more than 1000 MW thermal power in multiple phases lasting about 20 years. The driver linac is defined to be 1.5 GeV in energy, 10 mA in current and in cw operation mode. To meet the extremely high reliability and availability, the linac is designed with much installed margin and fault tolerance, including hot-spare injectors and local compensation method for key element failures. The accelerator complex consists of two parallel 10-MeV injectors, a joint medium-energy beam transport line, a main linac, and a high-energy beam transport line. The superconducting acceleration structures are employed except for the radio frequency quadrupole accelerators (RFQs which are at room temperature. The general design considerations and the beam dynamics design of the driver linac complex are presented here.

  14. Subcritical Water Induced Complexation of Soy Protein and Rutin: Improved Interfacial Properties and Emulsion Stability.

    Science.gov (United States)

    Chen, Xiao-Wei; Wang, Jin-Mei; Yang, Xiao-Quan; Qi, Jun-Ru; Hou, Jun-Jie

    2016-09-01

    Rutin is a common dietary flavonoid with important antioxidant and pharmacological activities. However, its application in the food industry is limited mainly because of its poor water solubility. The subcritical water (SW) treatment provides an efficient technique to solubilize and achieve the enrichment of rutin in soy protein isolate (SPI) by inducing their complexation. The physicochemical, interfacial, and emulsifying properties of the complex were investigated and compared to the mixtures. SW treatment had much enhanced rutin-combined capacity of SPI than that of conventional method, ascribing to the well-contacted for higher water solubility of rutin with stronger collision-induced hydrophobic interactions. Compared to the mixtures of rutin with proteins, the complex exhibited an excellent surface activity and improved the physical and oxidative stability of its stabilized emulsions. This improving effect could be attributed to the targeted accumulation of rutin at the oil-water interface accompanied by the adsorption of SPI resulting in the thicker interfacial layer, as evidenced by higher interfacial protein and rutin concentrations. This study provides a novel strategy for the design and enrichment of nanovehicle providing water-insoluble hydrophobic polyphenols for interfacial delivery in food emulsified systems. © 2016 Institute of Food Technologists®

  15. Combined subcritical water and enzymatic hydrolysis for reducing sugar production from coconut husk

    Science.gov (United States)

    Muharja, Maktum; Junianti, Fitri; Nurtono, Tantular; Widjaja, Arief

    2017-05-01

    Coconut husk wastes are abundantly available in Indonesia. It has a potential to be used into alternative renewable energy sources such as hydrogen using enzymatic hydrolysis followed by a fermentation process. Unfortunately, enzymatic hydrolysis is hampered by the complex structure of lignocellulose, so the cellulose component is hard to degrade. In this study, Combined Subcritical Water (SCW) and enzymatic hydrolysis are applied to enhance fermentable, thereby reducing production of sugar from coconut husk. There were two steps in this study, the first step was coconut husk pretreated by SCW in batch reactor at 80 bar and 150-200°C for 60 minutes reaction time. Secondly, solid fraction from the results of SCW was hydrolyzed using the mixture of pure cellulose and xylanase enzymes. Analysis was conducted on untreated and SCW-treated by gravimetric assay, liquid fraction after SCW and solid fraction after enzymatic hydrolysis using DNS assay. The maximum yield of reducing sugar (including xylose, arabinose glucose, galactose, mannose) was 1.254 gr per 6 gr raw material, representing 53.95% of total sugar in coconut husk biomass which was obtained at 150°C 80 bar for 60 minutes reaction time of SCW-treated and 6 hour of enzymatic hydrolysis using mixture of pure cellulose and xylanase enzymes (18.6 U /gram of coconut husk).

  16. On the refinement of the rotation rate based Smagorinsky model using velocity field gradients

    Science.gov (United States)

    Ghorbaniasl, Ghader; Ricks, Nathan; Siozos-Rousoulis, Leonidas; Degrez, Gérard; Contino, Francesco

    2017-10-01

    In this paper, a gradient-based refinement of the rotation rate-based Smagorinsky (RoSM) subgrid scale (SGS) model is presented. The refined model satisfies the Galilean invariance condition generally, without any assumptions. The suggested model retains the advantages offered by the original RoSM, thus being simple and efficient. It provides a Smagorinsky model constant that is always positive, with low fluctuations in space and time, without the need for any numerical stability control algorithms. The validity of the proposed SGS model is shown through three test cases, namely, a turbulent channel flow, subcritical flow past a stationary cylinder, and a spatially developing free round jet. The refined RoSM provides comparable results with the dynamic Smagorinsky, while matching well to reference data. The refined RoSM is shown to be computationally efficient, being 20% faster than the dynamic Smagorinsky model.

  17. Generalized conjugate gradient squared

    Energy Technology Data Exchange (ETDEWEB)

    Fokkema, D.R.; Sleijpen, G.L.G. [Utrecht Univ. (Netherlands)

    1994-12-31

    In order to solve non-symmetric linear systems of equations, the Conjugate Gradient Squared (CGS) is a well-known and widely used iterative method. In practice the method converges fast, often twice as fast as the Bi-Conjugate Gradient method. This is what you may expect, since CGS uses the square of the BiCG polynomial. However, CGS may suffer from its erratic convergence behavior. The method may diverge or the approximate solution may be inaccurate. BiCGSTAB uses the BiCG polynomial and a product of linear factors in an attempt to smoothen the convergence. In many cases, this has proven to be very effective. Unfortunately, the convergence of BiCGSTAB may stall when a linear factor (nearly) degenerates. BiCGstab({ell}) is designed to overcome this degeneration of linear factors. It generalizes BiCGSTAB and uses both the BiCG polynomial and a product of higher order factors. Still, CGS may converge faster than BiCGSTAB or BiCGstab({ell}). So instead of using a product of linear or higher order factors, it may be worthwhile to look for other polynomials. Since the BiCG polynomial is based on a three term recursion, a natural choice would be a polynomial based on another three term recursion. Possibly, a suitable choice of recursion coefficients would result in method that converges faster or as fast as CGS, but less erratic. It turns out that an algorithm for such a method can easily be formulated. One particular choice for the recursion coefficients leads to CGS. Therefore one could call this algorithm generalized CGS. Another choice for the recursion coefficients leads to BiCGSTAB. It is therefore possible to mix linear factors and some polynomial based on a three term recursion. This way one may get the best of both worlds. The authors will report on their findings.

  18. Conceptual design of minor actinides burner with an accelerator-driven subcritical system.

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Y.; Gohar, Y. (Nuclear Engineering Division)

    2011-11-04

    In the environmental impact study of the Yucca Mountain nuclear waste repository, the limit of spent nuclear fuel (SNF) for disposal is assessed at 70,000 metric tons of heavy metal (MTHM), among which 63,000 MTHM are the projected SNF discharge from U.S. commercial nuclear power plants though 2011. Within the 70,000 MTHM of SNF in storage, approximately 115 tons would be minor actinides (MAs) and 585 tons would be plutonium. This study describes the conceptual design of an accelerator-driven subcritical (ADS) system intended to utilize (burn) the 115 tons of MAs. The ADS system consists of a subcritical fission blanket where the MAs fuel will be burned, a spallation neutron source to drive the fission blanket, and a radiation shield to reduce the radiation dose to an acceptable level. The spallation neutrons are generated from the interaction of a 1 GeV proton beam with a lead-bismuth eutectic (LBE) or liquid lead target. In this concept, the fission blanket consists of a liquid mobile fuel and the fuel carrier can be LBE, liquid lead, or molten salt. The actinide fuel materials are dissolved, mixed, or suspended in the liquid fuel carrier. Therefore, fresh fuel can be fed into the fission blanket to adjust its reactivity and to control system power during operation. Monte Carlo analyses were performed to determine the overall parameters of an ADS system utilizing LBE as an example. Steady-state Monte Carlo simulations were studied for three fission blanket configurations that are similar except that the loaded amount of actinide fuel in the LBE is either 5, 7, or 10% of the total volume of the blanket, respectively. The neutron multiplication factor values of the three configurations are all approximately 0.98 and the MA initial inventories are each approximately 10 tons. Monte Carlo burnup simulations using the MCB5 code were performed to analyze the performance of the three conceptual ADS systems. Preliminary burnup analysis shows that all three conceptual ADS

  19. Innovative leaching of cobalt and lithium from spent lithium-ion batteries and simultaneous dechlorination of polyvinyl chloride in subcritical water.

    Science.gov (United States)

    Liu, Kang; Zhang, Fu-Shen

    2016-10-05

    In this work, an effective and environmentally friendly process for the recovery of cobalt (Co) and lithium (Li) from spent lithium-ion batteries (LIBs) and simultaneously detoxification of polyvinyl chloride (PVC) in subcritical water was developed. Lithium cobalt oxide (LiCoO2) power from spent LIBs and PVC were co-treated by subcritical water oxidation, in which PVC served as a hydrochloric acid source to promote metal leaching. The dechlorination of PVC and metal leaching was achieved simultaneously under subcritical water oxidation. More than 95% Co and nearly 98% Li were recovered under the optimum conditions: temperature 350°C, PVC/LiCoO2 ratio 3:1, time 30min, and a solid/liquid ratio 16:1 (g/L), respectively. Moreover, PVC was completely dechlorinated at temperatures above 350°C without any release of toxic chlorinated organic compounds. Assessment on economical and environmental impacts revealed that the PVC and LiCoO2 subcritical co-treatment process had significant technical, economic and environmental benefits over the traditional hydrometallurgy and pyrometallurgy processes. This innovative co-treatment process is efficient, environmentally friendly and adequate for Co and Li recovery from spent LIBs and simultaneous dechlorination of PVC in subcritical water. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Gradient Boosting Machines, A Tutorial

    Directory of Open Access Journals (Sweden)

    Alexey eNatekin

    2013-12-01

    Full Text Available Gradient boosting machines are a family of powerful machine-learning techniques that have shown considerable success in a wide range of practical applications. They are highly customizable to the particular needs of the application, like being learned with respect to different loss functions. This article gives a tutorial introduction into the methodology of gradient boosting methods. A theoretical information is complemented with many descriptive examples and illustrations which cover all the stages of the gradient boosting model design. Considerations on handling the model complexity are discussed. A set of practical examples of gradient boosting applications are presented and comprehensively analyzed.

  1. Enhancement of a 252Cf-based neutron beam via subcritical multiplication for neutron capture therapy.

    Science.gov (United States)

    Wang, C K; Zino, J F; Kessler, G

    2000-01-01

    Previous studies indicated that an epithermal-neutron beam based on bare 252Cf is not feasible for neutron capture therapy (NCT). It was reported that a clinically useful epithermal-neutron beam requires a minimum of 1.0 g of 252Cf, which is more than twice the US current annual supply. However, it was reasoned that the required quantity of 252Cf could be dramatically reduced when used with a subcritical multiplying assembly (SMA). This reasoning is based on the assumption that the epithermal-neutron beam intensity for NCT is directly proportional to the fission neutron population, and that the neutron multiplying factor of the SMA can be estimated by 1/(1 - k(eff)). We have performed detailed Monte Carlo calculations to investigate the validity of the above reasoning. Our results show that 1/(1 - k(eff)) grossly overestimates the beam enhancement factor for NCT. For example, Monte Carlo calculations predict a beam enhancement factor of 6.0 for an optimized SMA geometry with k(eff) = 0.968. This factor is much less than 31 predicted by 1/(1 - k(eff)). The overestimation is due to the fact that most of the neutrons produced in the SMA are self-shielded, whereas self-shielding is negligible in a bare 252Cf source. Since the beam intensity of a 0.1 g 252Cf with the optimized SMA enhancement is still more than an order of magnitude too low compared to the existing reactor beams, we conclude that the enhancement via an SMA for a 252Cf-based epithermal-neutron beam is inadequate for NCT.

  2. Catalyst-free ethyl biodiesel production from rice bran under subcritical condition

    Science.gov (United States)

    Zullaikah, Siti; Afifudin, Riza; Amalia, Rizky

    2015-12-01

    In-situ ethyl biodiesel production from rice bran under subcritical water and ethanol with no catalyst was employed. This process is environmentally friendly and is very flexible in term of feedstock utilization since it can handle relatively high moisture and free fatty acids (FFAs) contents. In addition, the alcohol, i.e. bioethanol, is a non-toxic, biodegradable, and green raw material when produced from non-edible biomass residues, leading to a 100% renewable biodiesel. The fatty acid ethyl esters (FAEEs, ethyl biodiesel) are better than fatty acid methyl esters (FAMEs, methyl biodiesel) in terms of fuel properties, including cetane number, oxidation stability and cold flow properties. The influences of the operating variables such as reaction time (1 - 10 h), ethanol concentration (12.5 - 87.5%), and pressurizing gas (N2 and CO2) on the ethyl biodiesel yield and purity have been investigated systematically while the temperature and pressure were kept constant at 200 °C and 40 bar. The optimum results were obtained at 5 h reaction time and 75% ethanol concentration using CO2 as compressing gas. Ethyl biodiesel yield and purity of 58.78% and 61.35%, respectively, were obtained using rice bran with initial FFAs content of 37.64%. FFAs level was reduced to 14.22% with crude ethyl biodiesel recovery of 95.98%. Increasing the reaction time up to 10 h only increased the yield and purity by only about 3%. Under N2 atmosphere and at the same operating conditions (5h and 75% ethanol), ethyl biodiesel yield and purity decreased to 54.63% and 58.07%, respectively, while FFAs level was increased to 17.93% and crude ethyl biodiesel recovery decreased to 87.32%.

  3. In-situ biodiesel and sugar production from rice bran under subcritical condition

    Science.gov (United States)

    Zullaikah, Siti; Rahkadima, Yulia Tri

    2015-12-01

    An integrated method of producing biodiesel and sugar using subcritical water and methanol has been employed as a potential way to reduce the high cost of single biofuel production from rice bran. The effects of temperature, methanol to water ratio and reaction time on the biodiesel yield and purity, and the concentration of sugar in hydrolysate were investigated systematically. Biodiesel with yield and purity of 65.21%and 73.53%, respectively, was obtained from rice bran with initial free fatty acid (FFA) content of 37.64% under the following conditions: T= 200 oC, P= 4.0 MPa (using CO2 as pressurizing gas), ratio of rice bran/water/methanol of 1/2/6 (g/mL/mL), and 3 h of reaction time. FFAs level was reduced to 10.00% with crude biodiesel recovery of 88.69%. However, the highest biodiesel yield (67.39%) and crude biodiesel recovery (100.00%) were obtained by decreasing the amount of methanol so that the ratio of rice bran/water/methanol became 1/4/4, g/mL/mL. In addition, the highest sugar concentration of 0.98 g/L was obtained at 180 oC and 4.0 MPa with ratio of rice bran/water/methanol of 1/4/4 (g/mL/mL) and reaction time of 3 h. Since no catalyst was employed and the biodiesel and reducing sugar were produced directly from rice bran with high water and FFA contents, the process was simple and environmentally friendly, which would make the production of biofuel more economical and sustainable.

  4. Subcritical CO2 sintering of microspheres of different polymeric materials to fabricate scaffolds for tissue engineering.

    Science.gov (United States)

    Bhamidipati, Manjari; Sridharan, BanuPriya; Scurto, Aaron M; Detamore, Michael S

    2013-12-01

    The aim of this study was to use CO2 at sub-critical pressures as a tool to sinter 3D, macroporous, microsphere-based scaffolds for bone and cartilage tissue engineering. Porous scaffolds composed of ~200 μm microspheres of either poly(lactic-co-glycolic acid) (PLGA) or polycaprolactone (PCL) were prepared using dense phase CO2 sintering, which were seeded with rat bone marrow mesenchymal stromal cells (rBMSCs), and exposed to either osteogenic (PLGA, PCL) or chondrogenic (PLGA) conditions for 6 weeks. Under osteogenic conditions, the PLGA constructs produced over an order of magnitude more calcium than the PCL constructs, whereas the PCL constructs had far superior mechanical and structural integrity (125 times stiffer than PLGA constructs) at week 6, along with twice the cell content of the PLGA constructs. Chondrogenic cell performance was limited in PLGA constructs, perhaps as a result of the polymer degradation rate being too high. The current study represents the first long-term culture of CO2-sintered microsphere-based scaffolds, and has established important thermodynamic differences in sintering between the selected formulations of PLGA and PCL, with the former requiring adjustment of pressure only, and the latter requiring the adjustment of both pressure and temperature. Based on more straightforward sintering conditions and more favorable cell performance, PLGA may be the material of choice for microspheres in a CO2 sintering application, although a different PLGA formulation with the encapsulation of growth factors, extracellular matrix-derived nanoparticles, and/or buffers in the microspheres may be advantageous for achieving a more superior cell performance than observed here. © 2013.

  5. Alpha Eigenvalue Estimation from Dynamic Monte Carlo Calculation for Subcritical Systems

    Energy Technology Data Exchange (ETDEWEB)

    Shaukat, Nadeem; Shim, Hyung Jin; Jang, Sang Hoon [Seoul National University, Seoul (Korea, Republic of)

    2016-05-15

    The dynamic Monte Carlo (DMC) method has been used in the TART code for the α eigenvalue calculations. A unique method has been equipped to measure the α in time-stepwise Monte Carlo simulations. For off-critical systems, the neutron population is allowed to change exponentially over a period of time. The neutron population is uniformly combed to return it to the neutron population started with at the beginning of time boundary. In this study, the conventional dynamic Monte Carlo method has been implemented in the McCARD. There is an exponential change of neutron population at the end of each time boundary for off-critical systems. In order to control this exponential change at the end of each time boundary, a conventional time cut-off controlling population strategy is included in the DMC module implemented in the McCARD. the conventional combing method to control the neutron population for off-critical systems is implemented. Instead of considering the cycles, the simulation is divided in time intervals. At the end of each time interval, neutron population control is applied on the banked neutrons. Randomly selected neutrons are discarded, until the size of neutron population matches the initial neutron histories at the beginning of time simulation. The prompt neutron decay constant α is estimated from DMC algorithm for subcritical systems. The effectiveness of the results is examined for two-group infinite homogeneous problems with varying the k-value. From the comparisons with the analytical solutions, it is observed that the results are quite comparable with each other for each k-value.

  6. Subcritical water extraction of antioxidant phenolic compounds from XiLan olive fruit dreg.

    Science.gov (United States)

    Yu, Xue-Mei; Zhu, Ping; Zhong, Qiu-Ping; Li, Meng-Ying; Ma, Han-Ruo

    2015-08-01

    Olive fruit dreg (OFD), waste from olive softdrink processing, has caused disposal problems. Nevertheless, OFD is a good source of functional ingredients, such as phenolic compounds. This study investigated the extraction conditions of phenolic compounds from OFD by using subcritical water (SCW) extraction method, antioxidant activity of SCW extracts, and components of phenolic compounds by LC-MS. SCW extraction experiments were performed in a batch stainless steel reactor at temperatures ranging from 100 to 180 °C at residence time of 5 to 60 min, and at solid-to-liquid ratio of 1:20 to 1:60. Higher recoveries of phenolic compounds [37.52 ± 0.87 mg gallic acid equivalents (GAE)/g, dry weight (DW)] were obtained at 160 °C, solid-to-liquid ratio of 1:50, and extract time of 30 min than at 2 h extraction with methanol (1.21 ± 0.16 mg GAE/g DW), ethanol (0.24 ± 0.07 mg GAE/g DW), and acetone (0.34 ± 0.01 mg GAE/g DW). The antioxidant activities of the SCW extracts were significantly stronger than those in methanol extracts at the same concentration of total phenolic contents. LC-MS analysis results indicated that SCW extracts contained higher amounts of phenolic compounds, such as chlorogenic acid, homovanillic acid, gallic acid, hydroxytyrosol, quercetin, and syringic acid. SCW at 160 °C, 30 min, and solid-to-liquid ratio of 1:50 may be a good substitute of organic solvents, such as methanol, ethanol, and acetone to recover phenolic compounds from OFD.

  7. Recovery of solid fuel from municipal solid waste by hydrothermal treatment using subcritical water.

    Science.gov (United States)

    Hwang, In-Hee; Aoyama, Hiroya; Matsuto, Toshihiko; Nakagishi, Tatsuhiro; Matsuo, Takayuki

    2012-03-01

    Hydrothermal treatments using subcritical water (HTSW) such as that at 234°C and 3MPa (LT condition) and 295°C and 8MPa (HT condition) were investigated to recover solid fuel from municipal solid waste (MSW). Printing paper, dog food (DF), wooden chopsticks, and mixed plastic film and sheets of polyethylene, polypropylene, and polystyrene were prepared as model MSW components, in which polyvinylchloride (PVC) powder and sodium chloride were used to simulate Cl sources. While more than 75% of carbon in paper, DF, and wood was recovered as char under both LT and HT conditions, plastics did not degrade under either LT or HT conditions. The heating value (HV) of obtained char was 13,886-27,544 kJ/kg and was comparable to that of brown coal and lignite. Higher formation of fixed carbon and greater oxygen dissociation during HTSW were thought to improve the HV of char. Cl atoms added as PVC powder and sodium chloride to raw material remained in char after HTSW. However, most Cl originating from PVC was found to converse into soluble Cl compounds during HTSW under the HT condition and could be removed by washing. From these results, the merit of HTSW as a method of recovering solid fuel from MSW is considered to produce char with minimal carbon loss without a drying process prior to HTSW. In addition, Cl originating from PVC decomposes into soluble Cl compound under the HT condition. The combination of HTSW under the HT condition and char washing might improve the quality of char as alternative fuel. Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. Kinetic and Thermodynamics studies for Castor Oil Extraction Using Subcritical Water Technology.

    Science.gov (United States)

    Abdelmoez, Wael; Ashour, Eman; Naguib, Shahenaz M; Hilal, Amr; Al Mahdy, Dalia A; Mahrous, Engy A; Abdel-Sattar, Essam

    2016-06-01

    In this work both kinetic and thermodynamics of castor oil extraction from its seeds using subcritical water technique were studied. It was found that the extraction process followed two consecutive steps. In these steps, the oil was firstly extracted from inside the powder by diffusion mechanism. Then the extracted oil, due to extending the extraction time under high temperature and pressure, was subjected to a decomposition reaction following first order mechanism. The experimental data correlated well with the irreversible consecutive unimolecular-type first order mechanism. The values of both oil extraction rate constants and decomposition rate constants were calculated through non-linear fitting using DataFit software. The extraction rate constants were found to be 0.0019, 0.024, 0.098, 0.1 and 0.117 min(-1), while the decomposition rate constants were 0.057, 0.059, 0.014, 0.019 and 0.17 min(-1) at extraction temperatures of 240, 250, 260, 270 and 280°C, respectively. The thermodynamic properties of the oil extraction process were investigated using Arrhenius equation. The values of the activation energy, Ea, and the frequency factor, A, were 73 kJ mol(-1) and 946, 002 min(-1), respectively. The physicochemical properties of the extracted castor oil including the specific gravity, viscosity, acid value, pH value and calorific value were found to be 0.947, 7.487, 1.094 mg KOH/g, 6.1, and 41.5 MJ/Kg, respectively. Gas chromatography analysis showed that ricinoleic acid (83.6%) appears as the predominant fatty acid in the extracted oil followed by oleic acid (5.5%) and linoleic acid (2.3%).

  9. SUB-LEU-METAL-THERM-001 SUBCRITICAL MEASUREMENTS OF LOW ENRICHED TUBULAR URANIUM METAL FUEL ELEMENTS BEFORE & AFTER IRRADIATION

    Energy Technology Data Exchange (ETDEWEB)

    TOFFER, H.

    2006-07-18

    With the shutdown of the Hanford PUREX (Plutonium-Uranium Extraction Plant) reprocessing plant in the 1970s, adequate storage capacity for spent Hanford N Reactor fuel elements in the K and N Reactor pools became a concern. To maximize space utilization in the pools, accounting for fuel burnup was considered. Fuel that had experienced a neutron environment in a reactor is known as spent, exposed, or irradiated fuel. In contrast fuel that has not yet been placed in a reactor is known as green, unexposed, or unirradiated fuel. Calculations indicated that at typical fuel exposures for N Reactor, the spent-fuel critical mass would be twice the critical mass for green fuel. A decision was reached to test the calculational result with a definitive experiment. If the results proved positive, storage capacity could be increased and N Reactor operation could be prolonged. An experiment to be conducted in the N Reactor spent-fuel storage pool was designed and assembled (References 1 and 2) and the services of the Battelle Northwest Laboratories (BNWL) (now Pacific Northwest National Laboratory [PNNL]) critical mass laboratory were procured for the measurements (Reference 3). The experiments were performed in April 1975 in the Hanford N Reactor fuel storage pool. The fuel elements were MKIA fuel assemblies, comprised of two concentric tubes of low-enriched metallic uranium. Two separate sets of measurements were performed: one with unirradiated fuel and one with irradiated fuel. Both the unirradiated and irradiated fuel, were measured in the same geometry. The spent-fuel MKIA assemblies had an average burnup of 2865 MWd (megawatt days)/t. A constraint was imposed restricting the measurements to a subcritical limit of k{sub eff} = 0.97. Subcritical count rate data was obtained with pulsed-neutron and approach-to-critical measurements. Ten (10) configurations with green fuel and nine (9) configurations with spent fuel are described and evaluated. Of these, three (3) green fuel

  10. Efficient decomposition of a new fluorochemical surfactant: perfluoroalkane disulfonate to fluoride ions in subcritical and supercritical water.

    Science.gov (United States)

    Hori, Hisao; Saito, Hiroki; Sakai, Hidenori; Kitahara, Toshiyuki; Sakamoto, Takehiko

    2015-06-01

    Decomposition of (-)O3SC3F6SO3(-) in subcritical and supercritical water was investigated, and the results were compared with the results for C3F7SO3(-). This is the first report on the decomposition of perfluoroalkane disulfonates, which are being introduced in electronics industry as greener alternatives to environmentally persistent and bioaccumulative perfluoroalkyl surfactants. Addition of zerovalent iron to the reaction system dramatically increased the yield of F(-) in the reaction solution: when the reaction of (-)O3SC3F6SO3(-) was carried out in subcritical water at 350°C for 6h, the F(-) yield was 70%, which was 23times the yield without zerovalent iron. Prolonged reaction increased the F(-) formation: after 18h, the F(-) yield from the reaction of (-)O3SC3F6SO3(-) reached 81%, which was 2.1times the F(-) yield from the reaction of C3F7SO3(-). Although the reactivity of FeO toward these substrates was lower than zerovalent iron in subcritical water, the reactivity was enhanced when the reaction temperature was elevated to supercritical state, at which temperature FeO underwent in situ disproportionation to form zerovalent iron, which acted as the reducing agent. When the reaction of (-)O3SC3F6SO3(-) was carried out in the presence of FeO in supercritical water at 380°C for 18h, the F(-) yield reached 92%, which was the highest yield among tested. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Effect of Subcritical Fluid Extraction on the High Quality of Headspace Oil from Jasminum sambac (L.) Aiton.

    Science.gov (United States)

    Ye, Qiuping; Jin, Xinyi; Wei, Shiqin; Zheng, Gongyu; Li, Xinlei

    2016-05-01

    Subcritical fluid extraction (SFE), as a novel method, was applied to investigate the yield, quality, and sensory evaluation of headspace oil from Jasminum sambac (L.) Aiton in comparison with petroleum ether extraction (PEE). The results indicated that the yield of the headspace oil using SFE was significantly higher (P headspace oil. The contents of linalool (21.90%) and benzyl acetate (16.31%) were higher via SFE than PEE. In addition, the sensory evaluation of SFE was superior to PEE, indicating a fresh, jasmine-like odor and green-yellow color. Thus, SFE is an improved method for obtaining natural headspace oil from jasmine flowers.

  12. Effect of Subcritical Fluid Extraction on the High Quality of Headspace Oil from Jasminum sambac (L.) Aiton.

    Science.gov (United States)

    2016-04-22

    Subcritical fluid extraction (SFE), as a novel method, was applied to investigate the yield, quality, and sensory evaluation of headspace oil from Jasminum sambac (L.) Aiton in comparison with petroleum ether extraction (PEE). The results indicated that the yield of the headspace oil using SFE was significantly higher (P headspace oil. The contents of linalool (21.90%) and benzyl acetate (16.31%) were higher via SFE than PEE. In addition, the sensory evaluation of SFE was superior to PEE, indicating a fresh, jasmine-like odor and green-yellow color. Thus, SFE is an improved method for obtaining natural headspace oil from jasmine flowers.

  13. The Impact of a Mild Sub-Critical Hydrothermal Carbonization Pretreatment on Umbila Wood. A Mass and Energy Balance Perspective

    Directory of Open Access Journals (Sweden)

    Carlos Alberto Cuvilas

    2015-03-01

    Full Text Available Over the last years, the pretreatment of biomass as a source of energy has become one of the most important steps of biomass conversion. In this work the effect of a mild subcritical hydrothermal carbonization of a tropical woody biomass was studied. Results indicate considerable change in carbon content from 52.78% to 65.1%, reduction of oxygen content from 41.14% to 28.72% and ash slagging and fouling potential. Even though decarboxylation, decarbonylation and dehydration reactions take place, dehydration is the one that prevails. The mass and energy balance was affected by the treatment conditions than the severity of the treatment.

  14. Strain gradients in epitaxial ferroelectrics

    NARCIS (Netherlands)

    Catalan, G; Noheda, Beatriz; McAneney, J; Sinnamon, LJ; Gregg, JM

    2005-01-01

    X-ray analysis of ferroelectric thin layers of Ba1/2Sr1/2TiO3 with different thicknesses reveals the presence of strain gradients across the films and allows us to propose a functional form for the internal strain profile. We use this to calculate the influence of strain gradient, through

  15. Computational Strain Gradient Crystal Plasticity

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Kysar, Jeffrey W.

    2011-01-01

    A model for strain gradient crystal visco-plasticity is formulated along the lines proposed by Fleck andWillis (2009) for isotropic plasticity. Size-effects are included in the model due to the addition of gradient terms in both the free energy as well as through a dissipation potential. A finite...

  16. Sobolev gradients and differential equations

    CERN Document Server

    Neuberger, J W

    2010-01-01

    A Sobolev gradient of a real-valued functional on a Hilbert space is a gradient of that functional taken relative to an underlying Sobolev norm. This book shows how descent methods using such gradients allow a unified treatment of a wide variety of problems in differential equations. For discrete versions of partial differential equations, corresponding Sobolev gradients are seen to be vastly more efficient than ordinary gradients. In fact, descent methods with these gradients generally scale linearly with the number of grid points, in sharp contrast with the use of ordinary gradients. Aside from the first edition of this work, this is the only known account of Sobolev gradients in book form. Most of the applications in this book have emerged since the first edition was published some twelve years ago. What remains of the first edition has been extensively revised. There are a number of plots of results from calculations and a sample MatLab code is included for a simple problem. Those working through a fair p...

  17. Innovative leaching of cobalt and lithium from spent lithium-ion batteries and simultaneous dechlorination of polyvinyl chloride in subcritical water

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Kang; Zhang, Fu-Shen, E-mail: fszhang@rcees.ac.cn

    2016-10-05

    Highlights: • A co-treatment process for recovery of Co and Li and simultaneous detoxification of PVC in subcritical water was proposed. • PVC was used as a hydrochloric acid source. • More than 95% Co and nearly 98% Li were leached under the optimum conditions. • Neither corrosive acid nor reducing agent was used. • The co-treatment process has technical, economic and environmental benefits over the traditional recovery processes. - Abstract: In this work, an effective and environmentally friendly process for the recovery of cobalt (Co) and lithium (Li) from spent lithium-ion batteries (LIBs) and simultaneously detoxification of polyvinyl chloride (PVC) in subcritical water was developed. Lithium cobalt oxide (LiCoO{sub 2}) power from spent LIBs and PVC were co-treated by subcritical water oxidation, in which PVC served as a hydrochloric acid source to promote metal leaching. The dechlorination of PVC and metal leaching was achieved simultaneously under subcritical water oxidation. More than 95% Co and nearly 98% Li were recovered under the optimum conditions: temperature 350 °C, PVC/LiCoO{sub 2} ratio 3:1, time 30 min, and a solid/liquid ratio 16:1 (g/L), respectively. Moreover, PVC was completely dechlorinated at temperatures above 350 °C without any release of toxic chlorinated organic compounds. Assessment on economical and environmental impacts revealed that the PVC and LiCoO{sub 2} subcritical co-treatment process had significant technical, economic and environmental benefits over the traditional hydrometallurgy and pyrometallurgy processes. This innovative co-treatment process is efficient, environmentally friendly and adequate for Co and Li recovery from spent LIBs and simultaneous dechlorination of PVC in subcritical water.

  18. Gradient elution in capillary electrochromatography

    Energy Technology Data Exchange (ETDEWEB)

    Anex, D.; Rakestraw, D.J. [Sandia National Labs., Livermore, CA (United States); Yan, Chao; Dadoo, R.; Zare, R.N. [Stanford Univ., CA (United States). Dept. of Chemistry

    1997-08-01

    In analogy to pressure-driven gradient techniques in high-performance liquid chromatography, a system has been developed for delivering electroosmotically-driven solvent gradients for capillary electrochromatography (CEC). Dynamic gradients with sub-mL/min flow rates are generated by merging two electroosmotic flows that are regulated by computer-controlled voltages. These flows are delivered by two fused-silica capillary arms attached to a T-connector, where they mix and then flow into a capillary column that has been electrokinetically packed with 3-mm reversed-phase particles. The inlet of one capillary arm is placed in a solution reservoir containing one mobile phase and the inlet of the other is placed in a second reservoir containing a second mobile phase. Two independent computer-controlled programmable high-voltage power supplies (0-50 kV)--one providing an increasing ramp and the other providing a decreasing ramp--are used to apply variable high-voltage potentials to the mobile phase reservoirs to regulate the electroosmotic flow in each arm. The ratio of the electroosmotic flow rates between the two arms is changed with time according to the computer-controlled voltages to deliver the required gradient profile to the separation column. Experiments were performed to confirm the composition of the mobile phase during a gradient run and to determine the change of the composition in response to the programmed voltage profile. To demonstrate the performance of electroosmotically-driven gradient elution in CEC, a mixture of 16 polycyclic aromatic hydrocarbons (PAHs) was separated in less than 90 minutes. This gradient technique is expected to be well-suited for generating not only solvent gradients in CEC, but also other types of gradients such as pH- and ionic-strength gradients in capillary electrokinetic separations and analyses.

  19. Gradient zone boundary control in salt gradient solar ponds

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R. (Downers Grove, IL)

    1984-01-01

    A method and apparatus for suppressing zone boundary migration in a salt gradient solar pond includes extending perforated membranes across the pond at the boundaries, between the convective and non-convective zones, the perforations being small enough in size to prevent individual turbulence disturbances from penetrating the hole, but being large enough to allow easy molecular diffusion of salt thereby preventing the formation of convective zones in the gradient layer. The total area of the perforations is a sizable fraction of the membrane area to allow sufficient salt diffusion while preventing turbulent entrainment into the gradient zone.

  20. Reactivity analysis for numerical solution of the point kinetic equation for subcritical; Analise da reatividade para solucao numerica da equacao da cinetica pontual para sistemas subcriticos

    Energy Technology Data Exchange (ETDEWEB)

    Henrice Junior, Edson; Goncalves, Alessandro da Cruz, E-mail: ejunior@nuclear.ufrj.br, E-mail: alessandro@nuclear.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Energia Nuclear; Palma, Daniel Artur Pinheiro, E-mail: dapalma@cnen.gov.br [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil); Mesquita, Amir Zacarias, E-mail: amir@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2015-07-01

    This paper provides a comparison between the reactivity calculated by the approximation based on the multiplication factor (K{sub eff}) and a new approach for the reactivity calculation to be used in the kinetics point equation for subcritical systems. To obtain the necessary kinetic parameters as well and the reference Power value calculation and validation, a subcritical system was simulated with the Monte Carlo code Serpent. This study is important for determining nuclear Power in such systems. The results shown consistent values with the validation method and new in-depth studies to calculate the reactivity should be performed to such systems, making the issue a very current theme. (author)

  1. Geochemical controls on the kinetics of quartz fracture at subcritical tensile stresses

    Science.gov (United States)

    Dove, Patricia M.

    1995-11-01

    A new kinetic model links physical and chemical controls on the subcritical fracture kinetics of quartz from the assumption that molecular level reactions governing fracture and dissolution proceed by similar pathways. The model formulation combines fracture theory with a mechanistically based description of chemical, thermal, and tensile stress effects on reactivity in aqueous environments. Water, as a vapor or liquid, promotes rupture of Si-O bonds by end-member processes: (1) reaction of a protonated surface with molecular water and (2) reaction of hydroxyl ions at an ionized surface. In humid environments, reaction frequency is determined by water accessibility to the crack tip. In wetted environments, the relative contributions of these mechanisms are determined by bulk solution composition which affects surface ionization and sol vent-surf ace interactions. The macroscopic fracture rate law is given in meters per second by the fractional sum of these end-member reaction mechanisms per a first-order equation. Agreement of this empirical rate expression with reported measurements of quartz fracture rates suggests the model is robust. It gives a good fit to fracture rates over 6 orders of magnitude and explains increasing rates with increasing solution pH, the dependence of rate upon crystallographic direction, and thermal dependence of rate over 20° to 80°C. Findings in this study suggest that (1) fracture models based upon changes in surface free energy with solution composition are macroscopic descriptions of solvent-surface interactions and parallel the mechanistic model presented here; (2) faster fracture rates observed in basic solutions are not facilitated by decreases in the activation barrier but are due to a transition in the solvent-surface reaction to give a higher reaction frequency and (3) power law expressions applied to fracture rate versus stress intensity measurements may not have direct mechanistic significance since log-linear relations

  2. Enhanced Production of Phenolic Compounds from Pumpkin Leaves by Subcritical Water Hydrolysis.

    Science.gov (United States)

    Ko, Jeong-Yeon; Ko, Mi-Ok; Kim, Dong-Shin; Lim, Sang-Bin

    2016-06-01

    Enhanced production of individual phenolic compounds by subcritical water hydrolysis (SWH) of pumpkin leaves was investigated at various temperatures ranging from 100 to 220°C at 20 min and at various reaction times ranging from 10 to 50 min at 160°C. Caffeic acid, p-coumaric acid, ferulic acid, and gentisic acid were the major phenolic compounds in the hydrolysate of pumpkin leaves. All phenolic compounds except gentisic acid showed the highest yield at 160°C, but gentisic acid showed the highest yield at 180°C. The cumulative amount of individual phenolic compounds gradually increased by 48.1, 52.2, and 78.4 μg/g dry matter at 100°C, 120°C, and 140°C, respectively, and then greatly increased by 1,477.1 μg/g dry matter at 160°C. The yields of caffeic acid and ferulic acid showed peaks at 20 min, while those of cinnamic acid, p-coumaric acid, p-hydroxybenzoic acid, and procatechuic acid showed peaks at 30 min. Antioxidant activities such as 2,2-diphenyl-1-picrylhydrazyl and ferric reducing antioxidant power values gradually increased with hydrolysis temperature and ranged from 6.77 to 12.42 mg ascorbic acid equivalents/g dry matter and from 4.25 to 8.92 mmol Fe(2+)/100 g dry matter, respectively. Color L* and b* values gradually decreased as hydrolysis temperature increased from 100°C to 140°C. At high temperatures (160°C to 220°C), L* and b* values decreased suddenly. The a* value peaked at 160°C and then decreased as temperature increased from 160°C to 220°C. These results suggest that SWH of pumpkin leaves was strongly influenced by hydrolysis temperature and may enhanced the production of phenolic compounds and antioxidant activities.

  3. Designing a mini subcritical nuclear reactor; Diseno de un mini reactor nuclear subcritico

    Energy Technology Data Exchange (ETDEWEB)

    Escobedo G, C. R.; Vega C, H. R.; Davila H, V. M., E-mail: rafelaescobedo@hotmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Jardin Juarez 147, Col. Centro, 98000 Zacatecas, Zac. (Mexico)

    2015-10-15

    In this work the design of a mini subcritical nuclear reactor formed by means of light water moderator, uranium as fuel, and isotopic neutron source of {sup 239}PuBe was carried out. The design was done by Monte Carlo methods with the code MCNP5 in which uranium was modeled in an array of concentric holes cylinders of 8.5, 14.5, 20.5, 26.5, 32.5 cm of internal radius and 3 cm of thickness, 36 cm of height. Different models were made from a single fuel cylinder (natural uranium) to five. The neutron source of {sup 239}PuBe was situated in the center of the mini reactor; in each arrangement was used water as moderator. Cross sections libraries Endf/Vi were used and the number of stories was large enough to ensure less uncertainty than 3%. For each case the effective multiplication factor k{sub e}-f{sub f}, the amplification factor and the power was calculated. Outside the mini reactor the ambient dose equivalent H (10) was calculated for different cases. The value of k{sub eff}, the amplification factor and power are directly related to the number of cylinders of uranium as fuel. Although the average energy of the neutrons {sup 239}PuBe is between 4.5 and 5 MeV in the case of the mini reactor for a cylinder, in the neutron spectrum the presence of thermal neutrons does not exist, so that produced fissions are generated with fast neutrons, and in designs of two and three rings the neutron spectra shows the presence of thermal neutrons, however the fissions are being generated with fast neutrons. Finally in the four and five cases the amount of moderator is enough to thermalized the neutrons and thereby produce the fission. The maximum value for k{sub eff} was 0.82; this value is very close to the assembly of Universidad Autonoma de Zacatecas generating a k{sub eff} of 0.86. According to the safety and radiation protection standards for the design of mini reactor of one, two and three cylinders they comply with the established safety, while designs of four and five

  4. Neutronic design study of accelerator driven system (ADS) for Jordan subcritical reactor as a neutron source for nuclear research.

    Science.gov (United States)

    Xoubi, Ned

    2018-01-01

    In this paper, a preliminary neutronic design study of an accelerator driven subcritical system for Jordan Subcritical Assembly (JSA) is presented. The conceptual design of coupling the JSA core with proton accelerator and spallation target is investigated, and its feasibility as a neutron source for nuclear research, and possibly for target irradiation and isotope production evaluated. 3D MCNPX model of the JSA reactor, the accelerator beam, and the Pb target was developed, based on actual reactor parameters. MCNPX calculations were carried out to estimate the absolute radial and axial neutron flux in the reactor, and to calculate the multiplication factor K eff and heat generated in the reactor. Numerical results showed an enormous increase in the neutron flux, by seven orders of magnitude, compared to the current JSA core design using Pu-Be source. In this research the results obtained are discussed and compared with those of the JSA, and do confirm the feasibility of utilizing the JSA as a viable nuclear research facility with adequate neutron flux. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Non-Catalytic and MgSO4 - Catalyst based Degradation of Glycerol in Subcritical and Supercritical Water Media

    Directory of Open Access Journals (Sweden)

    Mahfud Mahfud

    2011-02-01

    Full Text Available This research aims to study the glycerol degradation reaction in subcritical and supercritical water media. The degradation of glycerol into other products was performed both with sulphate salt catalysts and without catalyst. The reactant was made from glycerol and water with the mass ratio of 1:10. The experiments were carried out using a batch reactor at a constant pressure of 250 kgf/cm2, with the temperature range of 200-400oC, reaction time of 30 minutes, and catalyst mol ratio in glycerol of 1:10 and 1:8. The products of the non-catalytic glycerol degradation were acetaldehyde, methanol, and ethanol. The use of sulphate salt as catalyst has high selectivity to acetaldehyde and still allows the formation alcohol product in small quantities. The mechanism of ionic reaction and free radical reaction can occur at lower temperature in hydrothermal area or subcritical water. Conversion of glycerol on catalytic reaction showed a higher yield when compared with the reaction performed without catalyst

  6. Subcritical water extraction, UPLC-Triple-TOF/MS analysis and antioxidant activity of anthocyanins from Lycium ruthenicum Murr.

    Science.gov (United States)

    Wang, Yuwei; Luan, Guangxiang; Zhou, Wu; Meng, Jing; Wang, Honglun; Hu, Na; Suo, Yourui

    2018-05-30

    In this work, it has been developed an efficient method for extraction of anthocyanin from Lycium ruthenicum Murr. and the antioxidative activities research. Subcritical water extraction was investigated as a green technology for the extraction of anthocyanin from L. ruthenicum. Several key parameters affecting extraction efficiency were investigated and optimized by response surface methodology (RSM) combined with Box-Behnken design (BBD). The optimum extraction conditions and the desirability of model were the time of extraction = 55 min and the flow rate was 3 mL/min at 170 °C. At this operating condition, the content of anthocyanin was high to 26.33%. Subcritical water extraction was more efficient than using hot water or methyl alcohol for the extraction of anthocyanin. The composition of anthocyanins from L. ruthenicum has been investigated by high-performance liquid chromatography with diode array detector (HPLC-DAD) and Ultra Performance Liquid Chromatography-Triple-Time of Flight Mass Spectrometer (UPLC-Triple-TOF/MS). Seven anthocyanins have been detected, all of which were identified and quantified. Furthermore, the anthocyanins extracted by SWE showed significantly better antioxidant activity than the anthocyanins extracted by hot water or methyl alcohol according to DPPH and ABTS assay. SWE with significantly higher anthocyanin and antioxidant activity were achieved compared to conventional methods. Copyright © 2018 Elsevier Ltd. All rights reserved.

  7. Effect of SO2 concentration as an impurity on carbon steel corrosion under subcritical CO2 environment

    Science.gov (United States)

    Mahlobo, MGR; Premlall, K.; Olubambi, PA

    2017-12-01

    Carbon dioxide (CO2) is considered to be easier to transport over moderate distances when turned into supercritical state (dense phase) than at any other state. Because of this reason, the transportation of CO2 during carbon capture and storage requires CO2 to be at its supercritical state. CO2 temperature profile from different regions causes CO2 to deviate between supercritical and subcritical state (gas/liquid phase). In this study the influence of sulphur dioxide (SO2) on the corrosion of carbon steel was evaluated under different SO2 concentrations (0.5, 1.5 and 5%) in combination with subcritical CO2. Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Energy-Dispersive X-ray Spectroscopy (EDS) were used to characterize the CO2 corrosion product layer formed on the carbon steel surface. The weight loss results showed that corrosion rate increased with SO2 concentration with corrosion rate up to 7.45 mm/year while at 0% SO2 the corrosion rate was 0.067 mm/year.

  8. Conceptual design for accelerator-driven sodium-cooled sub-critical transmutation reactors using scale laws

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kwang Gu; Chang, Soon Heung [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)

    1998-12-31

    The feasibility study on conceptual design methodology for accelerator-driven sodium-cooled sub-critical transmutation reactors has been conducted to optimize the design parameters from the scale laws and validates the reactor performance with the integrated code system. A 1000 MWth sodium-cooled sub-critical transmutation reactor has been scaled and verified through the methodology in this paper, which is referred to Advanced Liquid Metal Reactor (ALMR). A Pb-Bi target material and a partitioned fuel are the liquid phases, and they are cooled by the circulation of secondary Pb-Bi coolant and by primary sodium coolant, respectively. Overall key design parameters are generated from the scale laws and they are improved and validated by the integrated code system. Integrated Code System (ICS) consists of LAHET, HMCNP, ORIGEN2, and COMMIX codes and some files. Through ICS the target region, the core region, and thermal-hydraulic related regions are analyzed once-through Results of conceptual design are attached in this paper. 5 refs., 4 figs., 1 tab. (Author)

  9. Toxicity of smelter slag-contaminated sediments from Upper Lake Roosevelt and associated metals to early life stage White Sturgeon (Acipenser transmontanus Richardson, 1836)

    Science.gov (United States)

    Little, E.E.; Calfee, R.D.; Linder, G.

    2014-01-01

    The toxicity of five smelter slag-contaminated sediments from the upper Columbia River and metals associated with those slags (cadmium, copper, zinc) was evaluated in 96-h exposures of White Sturgeon (Acipenser transmontanus Richardson, 1836) at 8 and 30 days post-hatch. Leachates prepared from slag-contaminated sediments were evaluated for toxicity. Leachates yielded a maximum aqueous copper concentration of 11.8 μg L−1 observed in sediment collected at Dead Man's Eddy (DME), the sampling site nearest the smelter. All leachates were nonlethal to sturgeon that were 8 day post-hatch (dph), but leachates from three of the five sediments were toxic to fish that were 30 dph, suggesting that the latter life stage is highly vulnerable to metals exposure. Fish maintained consistent and prolonged contact with sediments and did not avoid contaminated sediments when provided a choice between contaminated and uncontaminated sediments. White Sturgeon also failed to avoid aqueous copper (1.5–20 μg L−1). In water-only 96-h exposures of 35 dph sturgeon with the three metals, similar toxicity was observed during exposure to water spiked with copper alone and in combination with cadmium and zinc. Cadmium ranging from 3.2 to 41 μg L−1 or zinc ranging from 21 to 275 μg L−1 was not lethal, but induced adverse behavioral changes including a loss of equilibrium. These results suggest that metals associated with smelter slags may pose an increased exposure risk to early life stage sturgeon if fish occupy areas contaminated by slags.

  10. MODIFIED ARMIJO RULE ON GRADIENT DESCENT AND CONJUGATE GRADIENT

    Directory of Open Access Journals (Sweden)

    ZURAIDAH FITRIAH

    2017-10-01

    Full Text Available Armijo rule is an inexact line search method to determine step size in some descent method to solve unconstrained local optimization. Modified Armijo was introduced to increase the numerical performance of several descent algorithms that applying this method. The basic difference of Armijo and its modified are in existence of a parameter and estimating the parameter that is updated in every iteration. This article is comparing numerical solution and time of computation of gradient descent and conjugate gradient hybrid Gilbert-Nocedal (CGHGN that applying modified Armijo rule. From program implementation in Matlab 6, it's known that gradient descent was applying modified Armijo more effectively than CGHGN from one side: iteration needed to reach some norm of the gradient  (input by the user. The amount of iteration was representing how long the step size of each algorithm in each iteration. In another side, time of computation has the same conclusion.

  11. The geomagnetic field gradient tensor

    DEFF Research Database (Denmark)

    Kotsiaros, Stavros; Olsen, Nils

    2012-01-01

    of the magnetic gradient tensor and provide explicit expressions of its elements in terms of spherical harmonics. Finally we discuss the benefit of using gradient measurements for exploring the Earth’s magnetic field from space, in particular the advantage of the various tensor elements for a better determination......We develop the general mathematical basis for space magnetic gradiometry in spherical coordinates. The magnetic gradient tensor is a second rank tensor consisting of 3 × 3 = 9 spatial derivatives. Since the geomagnetic field vector B is always solenoidal (∇ · B = 0) there are only eight independent...

  12. Discharge Computation of Trapezoidal Side Weir in Subcritical Flow Regime Using Conventional Weir Theory

    Directory of Open Access Journals (Sweden)

    S. Riahi

    2016-02-01

    Full Text Available Introduction: Side weir structures are extensively used in hydraulic engineering, irrigation and environmental engineering, and it usually consists of a main weir and a lateral channel. Side weirs are also used as an emergency structure. This structure is installed on one side or both sides of the main channel to divert the flow from the main channel to the side channel. Lateral outflow takes place when the water surface in the main channel rises above the weir sill. Flow over a side weir is a typical case of spatially varied flow with decreasing discharge. There have been extensive studies on side weir overflows. Most of the previous theoretical analysis and experimental research works are related to the flow over rectangular side weirs in rectangular main channels. In the current study, the flow conditions over a trapezoidal side weir located in a rectangular main channel in subcritical flow regime is considered. Materials and Methods: The experiments were performed in a rectangular open channel having provisions for a side weir at one side of the channel. The main channel was horizontal with 12 m length, 0.25 m width, and 0.5 m height, and it was installed on a frame; lateral channel that has a length of 6 m, width of 0.25 m, and height of 1 m. It was set up parallel to the main channel; walls and its bed were made up of Plexiglas plates. The side weir was positioned at a distance of 6 m from the channel’s entrance. A total of 121 experiments on trapezoidal side weirs were carried out. Results and Discussion: For trapezoidal side weir, effective non-dimensionnal parameters were identified using dimensional analysis and Buckingham's Pi-Theorem. Finally, the following non-dimensional parameters were considered as the most effective ones on the discharge coefficient of the trapezoidal side weir flow. in which Fr1= upstream Froude number, P= hight of the trapezoidal side weir, y1= upstream water depth, z=side slope of the trapezoidal side weir

  13. Sobolev gradients and differential equations

    CERN Document Server

    Neuberger, John William

    1997-01-01

    A Sobolev gradient of a real-valued functional is a gradient of that functional taken relative to the underlying Sobolev norm. This book shows how descent methods using such gradients allow a unified treatment of a wide variety of problems in differential equations. Equal emphasis is placed on numerical and theoretical matters. Several concrete applications are made to illustrate the method. These applications include (1) Ginzburg-Landau functionals of superconductivity, (2) problems of transonic flow in which type depends locally on nonlinearities, and (3) minimal surface problems. Sobolev gradient constructions rely on a study of orthogonal projections onto graphs of closed densely defined linear transformations from one Hilbert space to another. These developments use work of Weyl, von Neumann and Beurling.

  14. Graded/Gradient Porous Biomaterials

    Directory of Open Access Journals (Sweden)

    Xigeng Miao

    2009-12-01

    Full Text Available Biomaterials include bioceramics, biometals, biopolymers and biocomposites and they play important roles in the replacement and regeneration of human tissues. However, dense bioceramics and dense biometals pose the problem of stress shielding due to their high Young’s moduli compared to those of bones. On the other hand, porous biomaterials exhibit the potential of bone ingrowth, which will depend on porous parameters such as pore size, pore interconnectivity, and porosity. Unfortunately, a highly porous biomaterial results in poor mechanical properties. To optimise the mechanical and the biological properties, porous biomaterials with graded/gradient porosity, pores size, and/or composition have been developed. Graded/gradient porous biomaterials have many advantages over graded/gradient dense biomaterials and uniform or homogenous porous biomaterials. The internal pore surfaces of graded/gradient porous biomaterials can be modified with organic, inorganic, or biological coatings and the internal pores themselves can also be filled with biocompatible and biodegradable materials or living cells. However, graded/gradient porous biomaterials are generally more difficult to fabricate than uniform or homogenous porous biomaterials. With the development of cost-effective processing techniques, graded/gradient porous biomaterials can find wide applications in bone defect filling, implant fixation, bone replacement, drug delivery, and tissue engineering.

  15. Optimization of supercritical phase and combined supercritical/subcritical conversion of lignocellulose for hexose production by using a flow reaction system.

    Science.gov (United States)

    Zhao, Yan; Lu, Wen-Jing; Wu, Hua-Yong; Liu, Jin-Wen; Wang, Hong-Tao

    2012-12-01

    A flow reaction system was utilized to investigate lignocellulose conversion using combined supercritical/subcritical conditions for hexose production. Initially, investigation of cellulose hydrolysis in supercritical water and optimization of reaction parameters were done. Oligosaccharide yields reached over 30% at cellulose concentrations of 3-5 gL(-1) and reaction times of 6-10s at 375 °C, and 2.5-4 gL(-1) and 8-10s at 380 °C. Temperatures above 380 °C were not appropriate for the supercritical phase in the combined process. Subsequently, conversion of lignocellulosic materials under combined supercritical/subcritical conditions was studied. Around 30% hexose was produced from corn stalks under the optimal parameters for supercritical (380 °C, 23-24 MPa, 9-10s) and subcritical (240 °C, 8-9 MPa, 45-50s) phases. Flow systems utilizing the combined supercritical/subcritical technology present a promising method for lignocellulosic conversion. The results of this study provide an important guide for the operational optimization and practical application of the proposed system. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Evaluation of sub-critical water as an extraction fluid for model contaminants from recycled PET for reuse as food packaging material.

    Science.gov (United States)

    Santos, Amélia S F; Agnelli, José A M; Manrich, Sati

    2010-04-01

    Recycling of plastics for food-contact packaging is an important issue and research into meaningful and cost-effective solutions is in progress. In this paper, the use of sub-critical water was evaluated as an alternative way of purifying poly(ethylene terephthalate) (PET) flakes for direct food contact applications. The effects of temperature, pressure and flow rate were assessed on the extraction efficiency of two of the most challenging classes of contaminants (toluene and benzophenone) from PET by sub-critical water using a first-order fractional experimental design. Extraction yield was quantified using GC/FID. The most important parameter was flow rate, indicating that the decrease in sub-critical water polarity with temperature was insufficient to eliminate partition effects. Temperature was also important, but only for the optimization of toluene extraction. These results may be explained by the poor solubility of higher molar mass compounds in sub-critical water compared to lower molar mass compounds under the same conditions, and the small decrease in dielectric constant with temperature under the experimental conditions evaluated. As cleaning efficiency is low and PET is very susceptible to hydrolysis, which limits the use of higher temperatures vis-à-vis physical recycling, the proposed extraction is unsuitable for a standalone super-clean process but may be a step in the process.

  17. Analysis of Subcritical Crack Growth in Dental Ceramics Using Fracture Mechanics and Fractography

    Science.gov (United States)

    Taskonak, Burak; Griggs, Jason A.; Mecholsky, John J.; Yan, Jia-Hau

    2008-01-01

    .05) but did not have significantly different fracture toughness (P>0.05). Regarding critical flaw size, stressing rate had a significant effect for In-Ceram® Zirconia specimens (P≤0.05) but not for Vitadur Alpha specimens (P>0.05). Fatigue parameters, n and ln B, were 38.4 and −12.7 for Vitadur Alpha and were 13.1 and 10.4 for In-Ceram® Zirconia. Significance Moisture assisted subcritical crack growth had a more deleterious effect on In-Ceram® Zirconia core ceramic than on Vitadur Alpha porcelain. Fracture surface analysis identified fracture surface features that can potentially mislead investigators into misidentifying the critical flaw. PMID:17845817

  18. The influence of resistivity gradients on shock conditions for a Petschek reconnection geometry

    Directory of Open Access Journals (Sweden)

    C. Nabert

    2016-04-01

    Full Text Available Shock waves can strongly influence magnetic reconnection as seen by the slow shocks attached to the diffusion region in Petschek reconnection. We derive necessary conditions for such shocks in a nonuniform resistive magnetohydrodynamic plasma and discuss them with respect to the slow shocks in Petschek reconnection. Expressions for the spatial variation of the velocity and the magnetic field are derived by rearranging terms of the resistive magnetohydrodynamic equations without solving them. These expressions contain removable singularities if the flow velocity of the plasma equals a certain characteristic velocity depending on the other flow quantities. Such a singularity can be related to the strong spatial variations across a shock. In contrast to the analysis of Rankine–Hugoniot relations, the investigation of these singularities allows us to take the finite resistivity into account. Starting from considering perpendicular shocks in a simplified one-dimensional geometry to introduce the approach, shock conditions for a more general two-dimensional situation are derived. Then the latter relations are limited to an incompressible plasma to consider the subcritical slow shocks of Petschek reconnection. A gradient of the resistivity significantly modifies the characteristic velocity of wave propagation. The corresponding relations show that a gradient of the resistivity can lower the characteristic Alfvén velocity to an effective Alfvén velocity. This can strongly impact the conditions for shocks in a Petschek reconnection geometry.

  19. Pore pressure migration during hydraulic stimulation due to permeability enhancement by low-pressure subcritical fracture slip

    Science.gov (United States)

    Mukuhira, Yusuke; Moriya, Hirokazu; Ito, Takatoshi; Asanuma, Hiroshi; Häring, Markus

    2017-04-01

    Understanding the details of pressure migration during hydraulic stimulation is important for the design of an energy extraction system and reservoir management, as well as for the mitigation of hazardous-induced seismicity. Based on microseismic and regional stress information, we estimated the pore pressure increase required to generate shear slip on an existing fracture during stimulation. Spatiotemporal analysis of pore pressure migration revealed that lower pore pressure migrates farther and faster and that higher pore pressure migrates more slowly. These phenomena can be explained by the relationship between fracture permeability and stress state criticality. Subcritical fractures experience shear slip following smaller increases of pore pressure and promote migration of pore pressure because of their enhanced permeability. The difference in migration rates between lower and higher pore pressures suggests that the optimum wellhead pressure is the one that can stimulate relatively permeable fractures, selectively. Its selection optimizes economic benefits and minimizes seismic risk.

  20. On the significance of the energy correlations of spallation neutrons on the neutron fluctuations in accelerator-driven subcritical systems

    CERN Document Server

    Pázsit, I; Fhager, V

    2000-01-01

    Studies of neutron fluctuations in spallation-driven subcritical systems require the use of energy-dependent master equations. In particular, calculation of the second moment of the neutron distribution requires knowledge on the energy correlations (two-point distributions) of the source particles. It is shown here that such correlations will exist even if the energies of all neutrons, generated in any single spallation event, are independent, provided that the energy distribution of the neutrons for separate spallation events is dependent on the number of neutrons generated. A simple model of number dependence of the energy spectrum is constructed, and the arising energy correlations are calculated. The error in calculating the second moment of the neutron distribution, arising when assuming zero correlations (i.e. using only one-particle energy spectra), is estimated in a simple model of neutron slowing down.

  1. High-energy-density electron beam from interaction of two successive laser pulses with subcritical-density plasma

    Directory of Open Access Journals (Sweden)

    J. W. Wang

    2016-02-01

    Full Text Available It is shown by particle-in-cell simulations that a narrow electron beam with high energy and charge density can be generated in a subcritical-density plasma by two consecutive laser pulses. Although the first laser pulse dissipates rapidly, the second pulse can propagate for a long distance in the thin wake channel created by the first pulse and can further accelerate the preaccelerated electrons therein. Given that the second pulse also self-focuses, the resulting electron beam has a narrow waist and high charge and energy densities. Such beams are useful for enhancing the target-back space-charge field in target normal sheath acceleration of ions and bremsstrahlung sources, among others.

  2. Optimization of subcritical water extraction parameters of antioxidant polyphenols from sea buckthorn (Hippophaë rhamnoides L.) seed residue.

    Science.gov (United States)

    Gong, Ying; Zhang, Xiaofei; He, Li; Yan, Qiuli; Yuan, Fang; Gao, Yanxiang

    2015-03-01

    Polyphenols was extracted with subcritical water from the sea buckthorn seed residue (after oil recovery), and the extraction parameters were optimized using response surface methodology (RSM). The independent processing variables were extraction temperature, extraction time and the ratio of water to solid. The optimal extraction parameters for the extracts with highest ABTS radical scavenging activity were 120 °C, 36 min and the water to solid ratio of 20, and the maximize antioxidant capacity value was 32.42 mmol Trolox equivalent (TE)/100 g. Under the optimal conditions, the yield of total phenolics, total flavonoids and proanthocyanidins was 36.62 mg gallic acid equivalents (GAE)/g, 19.98 mg rutin equivalent (RE)/g and 10.76 mg catechin equivalents (CE)/g, respectively.

  3. Study of the enantiomeric separation of oxfendazole and cetirizine using subcritical fluid chromatography on an amylose-based column.

    Science.gov (United States)

    Toribio, L; del Nozal, M J; Bernal, J L; Cristofol, C; Alonso, C

    2006-07-21

    The enantiomeric separation of cetirizine and oxfendazole on a Chiralpak AD column using subcritical fluid chromatography has been studied in this work. The enantioseparation of cetirizine was only possible when 2-propanol was used as a modifier, obtaining better results in presence of the additives triethylamine (TEA) and trifluoroacetic acid (TFAA). On the contrary, 2-propanol provided the lowest enantioresolutions for oxfendazole, in this case the best results in terms of high resolution and short analysis time were obtained with ethanol. The study of the temperature effect revealed that in the case of cetirizine using 2-propanol, and oxfendazole using methanol, the separation was enthalpy-driven and the isoelution temperature was above the working range. Using ethanol or 2-propanol, the results showed that the oxfendazole enantioseparation was entropically driven and the isoelution temperatures were below the range studied.

  4. Life cycle assessment of biodiesel production from algal bio-crude oils extracted under subcritical water conditions.

    Science.gov (United States)

    Ponnusamy, Sundaravadivelnathan; Reddy, Harvind Kumar; Muppaneni, Tapaswy; Downes, Cara Meghan; Deng, Shuguang

    2014-10-01

    A life cycle assessment study is performed for the energy requirements and greenhouse gas emissions in an algal biodiesel production system. Subcritical water (SCW) extraction was applied for extracting bio-crude oil from algae, and conventional transesterification method was used for converting the algal oil to biodiesel. 58MJ of energy is required to produce 1kg of biodiesel without any co-products management, of which 36% was spent on cultivation and 56% on lipid extraction. SCW extraction with thermal energy recovery reduces the energy consumption by 3-5 folds when compared to the traditional solvent extraction. It is estimated that 1kg of algal biodiesel fixes about 0.6kg of CO2. An optimized case considering the energy credits from co-products could further reduce the total energy demand. The energy demand for producing 1kg of biodiesel in the optimized case is 28.23MJ. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Extraction of bioactive compounds from sesame (Sesamum indicum L.) defatted seeds using water and ethanol under sub-critical conditions.

    Science.gov (United States)

    Bodoira, Romina; Velez, Alexis; Andreatta, Alfonsina E; Martínez, Marcela; Maestri, Damián

    2017-12-15

    Sesame seeds contain a vast array of lignans and phenolic compounds having important biological properties. An optimized method to obtain these seed components was designed by using water and ethanol at high pressure and temperature conditions. The maximum concentrations of lignans, total phenolics, flavonoids and flavonols compounds were achieved at 220°C extraction temperature and 8MPa pressure, using 63.5% ethanol as co-solvent. Under these conditions, the obtained sesame extracts gave the best radical scavenging capacity. Kinetic studies showed a high extraction rate of phenolic compounds until the first 50min of extraction, and it was in parallel with the highest scavenging capacity. The comparison of our results with those obtained under conventional extraction conditions (normal pressure, ambient temperature) suggests that recovery of sesame bioactive compounds may be markedly enhanced using water/ethanol mixtures at sub-critical conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. A theory of gradient analysis

    NARCIS (Netherlands)

    Braak, ter C.J.F.

    1988-01-01

    The theory of gradient analysis is presented in this chapter, in which the heuristic techniques are integrated with regression, calibration, ordination and constrained ordination as distinct, well-defined statistical problems. The various techniques used for each type of problem are classified into

  7. Orderings for conjugate gradient preconditionings

    Science.gov (United States)

    Ortega, James M.

    1991-01-01

    The effect of orderings on the rate of convergence of the conjugate gradient method with SSOR or incomplete Cholesky preconditioning is examined. Some results also are presented that help to explain why red/black ordering gives an inferior rate of convergence.

  8. Compositional gradients in Gramineae genes

    DEFF Research Database (Denmark)

    Wong, Gane Ka-Shu; Wang, Jun; Tao, Lin

    2002-01-01

    In this study, we describe a property of Gramineae genes, and perhaps all monocot genes, that is not observed in eudicot genes. Along the direction of transcription, beginning at the junction of the 5'-UTR and the coding region, there are gradients in GC content, codon usage, and amino-acid usage...

  9. Fine structure of the retinal pigment epithelium and cones of Antarctic fish Notohenia coriiceps Richardson in light and dark-conditions Ultraestrutra do epitélio pigmentar da retina e dos cones do peixe Antártico Notothenia coriiceps Richardson submetido à luz e ao escuro

    Directory of Open Access Journals (Sweden)

    Lucélia Donatti

    2007-03-01

    Full Text Available The Antarctic fish Notothenia coriiceps Richardson, 1844 lives in an environment of daily and annual photic variation and retina cells have to adjust morphologically to environmental luminosity. After seven day dark or seven day light acclimation of two groups of fish, retinas were extracted and processed for light and transmission electron microscopy. In seven day dark adapted, retina pigment epithelium melanin granules were aggregated at the basal region of cells, and macrophages were seen adjacent to the apical microvilli, between the photoreceptors. In seven day light adapted epithelium, melanin granules were inside the apical microvilli of epithelial cells and macrophages were absent. The supranuclear region of cones adapted to seven day light had less electron dense cytoplasm, and an endoplasmic reticulum with broad tubules. The mitochondria in the internal segment of cones adapted to seven day light were larger, and less electron dense. The differences in the morphology of cones and pigment epithelial cells indicate that N. coriiceps has retinal structural adjustments presumably optimizing vision in different light conditions.O peixe Antártico Notothenia coriiceps Richardson, 1844 habita meios com variações fóticas diária e anual e as células da retina se adaptam morfologicamente a esta luminosidade ambiental. Dois grupos de peixes foram aclimatados durante sete dias à luz constante ou ao escuro constante. Após secção medular, as retinas foram extraídas e processadas para microscopia de luz e microscopia eletrônica de transmissão. No epitélio pigmentar da retina adaptado sete dias ao escuro, os pigmentos de melanina agregam-se na base coroidal das células epiteliais pigmentares e macrófagos são encontrados no interior do processos apicais entre as células fotorreceptoras. No epitélio adaptado sete dias à luz os pigmentos de melanina se dispõem ao longo das projeções apicais das células epiteliais pigmentares e os

  10. Comparative analysis of operation and safety of subcritical nuclear systems and innovative critical reactors; Analyse comparative du fonctionnement et de la surete de systemes sous-critiques et de reacteurs critiques innovants

    Energy Technology Data Exchange (ETDEWEB)

    Bokov, P.M

    2005-05-01

    The main goal of this thesis work is to investigate the role of core subcriticality for safety enhancement of advanced nuclear systems, in particular, molten salt reactors, devoted to both energy production and waste incineration/transmutation. The inherent safety is considered as ultimate goal of this safety improvement. An attempt to apply a systematic approach for the analysis of the subcriticality contribution to inherent properties of hybrid system was performed. The results of this research prove that in many cases the subcriticality may improve radically the safety characteristics of nuclear reactors, and in some configurations it helps to reach the 'absolute' intrinsic safety. In any case, a proper choice of subcriticality level makes all analyzed transients considerably slower and monotonic. It was shown that the weakest point of the independent-source systems with respect to the intrinsic safety is thermohydraulic unprotected transients, while in the case of the coupled-source systems the excess reactivity/current insertion events remain a matter of concern. To overcome these inherent drawbacks a new principle of realization of a coupled sub-critical system (DENNY concept) is proposed. In addition, the ways to remedy some particular safety-related problems with the help of the core sub-criticality are demonstrated. A preliminary safety analysis of the fast-spectrum molten salt reactor (REBUS concept) is also carried out in this thesis work. Finally, the potential of the alternative (to spallation) neutron sources for application in hybrid systems is examined. (author)

  11. Implementation and training methodology of subcritical reactors neutronic calculations triggered by external neutron source and applications; Implementacao e qualificacao de metodologia de calculos neutronicos em reatores subcriticos acionados por fonte externa de neutrons e aplicacoes

    Energy Technology Data Exchange (ETDEWEB)

    Carluccio, Thiago

    2011-07-01

    This works had as goal to investigate calculational methodologies on subcritical source driven reactor, such as Accelerator Driven Subcritical Reactor (ADSR) and Fusion Driven Subcritical Reactor (FDSR). Intense R and D has been done about these subcritical concepts, mainly due to Minor Actinides (MA) and Long Lived Fission Products (LLFP) transmutation possibilities. In this work, particular emphasis has been given to: (1) complement and improve calculation methodology with neutronic transmutation and decay capabilities and implement it computationally, (2) utilization of this methodology in the Coordinated Research Project (CRP) of the International Atomic Energy Agency Analytical and Experimental Benchmark Analysis of ADS and in the Collaborative Work on Use of Low Enriched Uranium in ADS, especially in the reproduction of the experimental results of the Yalina Booster subcritical assembly and study of a subcritical core of IPEN / MB-01 reactor, (3) to compare different nuclear data libraries calculation of integral parameters, such as k{sub eff} and k{sub src}, and differential distributions, such as spectrum and flux, and nuclides inventories and (4) apply the develop methodology in a study that may help future choices about dedicated transmutation system. The following tools have been used in this work: MCNP (Monte Carlo N particle transport code), MCB (enhanced version of MCNP that allows burnup calculation) and NJOY to process nuclear data from evaluated nuclear data files. (author)

  12. Comparison studies of surface cleaning methods for PAN-based carbon fibers with acetone, supercritical acetone and subcritical alkali aqueous solutions

    Science.gov (United States)

    Meng, Linghui; Fan, Dapeng; Huang, Yudong; Jiang, Zaixing; Zhang, Chunhua

    2012-11-01

    Four kinds of polyacrylonitrile-based carbon fibers were cleaned by three methods and were characterized by X-ray photoelectron spectroscopy, monofilament tensile strength test and atomic force microscopy (AFM). Experimental results of these tests reveal that the method using supercritical acetone or subcritical potassium hydroxide aqueous solution act as the processing medium shows a better cleaning effect compared to the traditional method, Soxhlet extraction with acetone. The method using supercritical acetone is more appropriate to wipe off the oxygenated contaminants on carbon fibers' surfaces and causes a relatively smaller damage to the bulk strength of each carbon fiber. As far as treating method using the subcritical alkali aqueous solution, it can thoroughly remove silicious contaminants on the surfaces of treated fibers.

  13. (n,xn) cross section measurements for Y-89 foils used as detectors for high energy neutron measurements in the deeply subcritical assembly “QUINTA”

    OpenAIRE

    Bielewicz Marcin; Kilim Stanisław; Strugalska-Gola Elżbieta; Szuta Marcin; Wojciechowski Andrzej; Tyutyunnikov Sergey; Prokofiev Alexander; Passoth Elke

    2017-01-01

    Study of the deep subcritical systems (QUINTA) using relativistic beams is performed within the project “Energy and Transmutation of Radioactive Wastes” (E&T – RAW). The experiment assembly was irradiated by deuteron/proton beam (Dubna NUCLOTRON). We calculated the neutron energy spectrum inside the whole assembly by using threshold energy (n,xn) reactions in yttrium (Y-89) foils. There are almost no experimental cross section data for those reactions. New Y-89(n,xn) cross section measurement...

  14. Optimization of Biomass-Fuelled Combined Cooling, Heating and Power (CCHP) Systems Integrated with Subcritical or Transcritical Organic Rankine Cycles (ORCs)

    OpenAIRE

    Daniel Maraver; Sylvain Quoilin; Javier Royo

    2014-01-01

    This work is focused on the thermodynamic optimization of Organic Rankine Cycles (ORCs), coupled with absorption or adsorption cooling units, for combined cooling heating and power (CCHP) generation from biomass combustion. Results were obtained by modelling with the main aim of providing optimization guidelines for the operating conditions of these types of systems, specifically the subcritical or transcritical ORC, when integrated in a CCHP system to supply typical heating and cooling deman...

  15. Sub-critical long-term operation of industrial scale hollow-fibre membranes in a submerged anaerobic MBR (HF-SAnMBR) system

    OpenAIRE

    Robles Martínez, Ángel; Ruano García, María Victoria; Ribes Bertomeu, José; Ferrer, J.

    2012-01-01

    The aim of this study was to evaluate the long-term performance of hollow-fibre (HF) membranes used to treat urban wastewater in a submerged anaerobic MBR when operating sub-critically. To this end, a demonstration plant with two industrial scale HF ultrafiltration membrane modules was operated under different conditions. The main factor affecting membrane performance was the concentration of mixed liquor total solids (MLTS). The reversible fouling rate remained low even when MLTS levels (abo...

  16. Vertebrate pressure-gradient receivers

    DEFF Research Database (Denmark)

    Christensen-Dalsgaard, Jakob

    2011-01-01

    The eardrums of all terrestrial vertebrates (tetrapods) are connected through Eustachian tubes or interaural canals. In some of the animals, these connections create pressure-gradient directionality, an enhanced directionality by interaction of sound arriving at both sides of the eardrum and stro......The eardrums of all terrestrial vertebrates (tetrapods) are connected through Eustachian tubes or interaural canals. In some of the animals, these connections create pressure-gradient directionality, an enhanced directionality by interaction of sound arriving at both sides of the eardrum....... Recent vertebrates form a continuum from perfect interaural transmission (0 dB in a certain frequency band) and pronounced eardrum directionality (30-40 dB) in the lizards, over somewhat attenuated transmission and limited directionality in birds and frogs, to the strongly attenuated interaural...

  17. Computational strain gradient crystal plasticity

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Kysar, Jeffrey W.

    2014-01-01

    oriented face centered cubic crystals are developed in terms of the crystallographic slip parameters. The effect on geometrically necessary dislocation structures introduced by plastic deformation is investigated as a function of the ratio of void radius to plasticity length scale.......A numerical method for viscous strain gradient crystal plasticity theory is presented, which incorporates both energetic and dissipative gradient effects. The underlying minimum principles are discussed as well as convergence properties of the proposed finite element procedure. Three problems...... of plane crystal plasticity are studied: pure shear of a single crystal between rigid platens as well as plastic deformation around cylindrical voids in hexagonal close packed and face centered cubic crystals. Effective in-plane constitutive slip parameters for plane strain deformation of specifically...

  18. Primordial vorticity and gradient expansion

    CERN Document Server

    Giovannini, Massimo

    2012-01-01

    The evolution equations of the vorticities of the electrons, ions and photons in a pre-decoupling plasma are derived, in a fully inhomogeneous geometry, by combining the general relativistic gradient expansion and the drift approximation within the Adler-Misner-Deser decomposition. The vorticity transfer between the different species is discussed in this novel framework and a set of general conservation laws, connecting the vorticities of the three-component plasma with the magnetic field intensity, is derived. After demonstrating that a source of large-scale vorticity resides in the spatial gradients of the geometry and of the electromagnetic sources, the total vorticity is estimated to lowest order in the spatial gradients and by enforcing the validity of the momentum constraint. By acknowledging the current bounds on the tensor to scalar ratio in the (minimal) tensor extension of the $\\Lambda$CDM paradigm the maximal comoving magnetic field induced by the total vorticity turns out to be, at most, of the or...

  19. Effect of residence time on two-step liquefaction of rice straw in a CO2 atmosphere: Differences between subcritical water and supercritical ethanol.

    Science.gov (United States)

    Yang, Tianhua; Wang, Jian; Li, Bingshuo; Kai, Xingping; Li, Rundong

    2017-04-01

    This study investigated the influence of temperature and residence time on liquefaction of rice straw in subcritical CO2-subcritical water (subCO2-subH2O) and in subcritical CO2-supercritical ethanol (subCO2-scEtOH), considering the final reaction temperatures (270-345°C) and residence times (15 and 30min). Residence time was identified as a crucial parameter in the subCO2-subH2O liquefaction, whereas residence time had a marginal influence on subCO2-scEtOH liquefaction. When reaction conditions were 320°C and 15min, solvents have weak impact on the quality of bio-oil, HHV 28.57MJ/kg and 28.62MJ/kg, respectively. There was an obvious difference between the subCO2-subH2O and subCO2-scEtOH liquefaction mechanisms. In subCO2-subH2O, CO2 promoted the carbonyl reaction. In subCO2-scEtOH, supercritical ethanol have the function of donating hydrogen and promoting the reaction of hydroxyl-alkylation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Comparison studies of surface cleaning methods for PAN-based carbon fibers with acetone, supercritical acetone and subcritical alkali aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Meng Linghui; Fan Dapeng [School of Chemical Engineering and Technology, Harbin Institute of Technology, P.O. Box 410, Harbin 150001 (China); Huang Yudong, E-mail: ydhuang.hit1@yahoo.com.cn [School of Chemical Engineering and Technology, Harbin Institute of Technology, P.O. Box 410, Harbin 150001 (China); Jiang Zaixing; Zhang Chunhua [School of Chemical Engineering and Technology, Harbin Institute of Technology, P.O. Box 410, Harbin 150001 (China)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Cleaning with supercritical acetone is appropriate to wipe off the oxygenated contaminants. Black-Right-Pointing-Pointer Cleaning with supercritical acetone causes smaller damage to bulk strength of carbon fibers. Black-Right-Pointing-Pointer Cleaning with subcritical alkali aqueous solution can thoroughly remove silicious contaminants. - Abstract: Four kinds of polyacrylonitrile-based carbon fibers were cleaned by three methods and were characterized by X-ray photoelectron spectroscopy, monofilament tensile strength test and atomic force microscopy (AFM). Experimental results of these tests reveal that the method using supercritical acetone or subcritical potassium hydroxide aqueous solution act as the processing medium shows a better cleaning effect compared to the traditional method, Soxhlet extraction with acetone. The method using supercritical acetone is more appropriate to wipe off the oxygenated contaminants on carbon fibers' surfaces and causes a relatively smaller damage to the bulk strength of each carbon fiber. As far as treating method using the subcritical alkali aqueous solution, it can thoroughly remove silicious contaminants on the surfaces of treated fibers.

  1. Sub-critical water as a green solvent for production of valuable materials from agricultural waste biomass: A review of recent work

    Directory of Open Access Journals (Sweden)

    A. Shitu

    2015-07-01

    Full Text Available Agricultural waste biomass generated from agricultural production and food processing industry are abundant, such as durian  peel, mango peel, corn straw, rice bran, corn shell, potato peel and many more. Due to low commercial value, these wastes are disposed in landfill, which if not managed properly may cause environmental problems. Currently, environmental laws and regulations pertaining to the pollution from agricultural waste streams by regulatory agencies are stringent and hence the application of toxic solvents during processing has become public concern. Recent development in valuable materials extraction from the decomposition of agricultural waste by sub-critical water treatment from the published literature was review. Physico-chemical characteristic (reaction temperature, reaction time and solid to liquid ratio of the sub-critical water affecting its yield were also reviewed. The utilization of biomass residue from agriculture, forest wood production and from food and feed processing industry may be an important alternative renewable energy supply. The paper also presents future research on sub-critical water.

  2. 3D CAD model of the subcritical nuclear reactor of IPN; Modelo CAD 3D del reactor nuclear subcritico del IPN

    Energy Technology Data Exchange (ETDEWEB)

    Pahuamba V, F. de J.; Delfin L, A.; Gomez T, A. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Ibarra R, G.; Del Valle G, E.; Sanchez R, A., E-mail: narehc@hotmail.com [IPN, Escuela Superior de Fisica y Matematicas, Av. IPN, Edif. 9, Unidad Profesional Adolfo Lopez Mateos, San Pedro Zacatenco, 07738 Ciudad de Mexico (Mexico)

    2016-09-15

    The three-dimensional (3D) CAD model of the subcritical reactor Chicago model 9000 of Instituto Politecnico Nacional (IPN) allows obtaining a 3D view with the dimensions of each of its components, such as: natural uranium cylindrical rods, fuel elements, hexagonal reactor core arrangement, cylindrical stainless steel tank containing the core, fuel element support grids and reactor water cleaning system. As a starting point for the development of the model, the Chicago model 9000 subcritical reactor manual provided by the manufacturer was used, the measurement and verification of the components to adapt the geometric, physical and mechanical characteristics was carried out and materials standards were used to obtain a design that allows to elaborate a new manual according to the specifications. In addition, the 3D models of the building of the Advanced Physics Laboratory, neutron generator, cobalt source and the corridors connecting to the subcritical reactor facility were developed, allowing an animated ride, developed by computer-aided design software. The manual provided by the company Nuclear Chicago, dates from the year 1959 and presents diverse deviations in the design and dimensions of the reactor components. The model developed; in addition to supporting the development of the new manual represents a learning tool to visualize the reactor components. (Author)

  3. Paleohydraulic Reconstruction of Modern Large Floods at Subcritical Speed in a Confined Valley: Proof of Concept

    Directory of Open Access Journals (Sweden)

    Patricio Bohorquez

    2016-12-01

    Full Text Available The present study aims to show the accuracy of paleoflood reconstruction techniques based on two-dimensional (2D hydraulic modelling of a large flood. Using this reconstruction technique, we determined trends in flood stages over time in a regulated river. A stretch of the Guadalquivir River (Southern Spain was selected as the study site. High-resolution orthophotos and LiDAR (Light Detection and Ranging elevations were acquired just after modern floods. They were used for the identification and location of stage indicators. In addition, water gradients were estimated from gauging records, documentary information and paleostage indicators (PSIs in two situations: (i pre-vegetation encroachment; and (ii post-vegetation encroachment due to upstream impoundment. Standard two-dimensional, flow depth-averaged equations over fixed beds were used in the hydraulic modelling. In a first stage, long records of instrumental data at gauging stations and documentary evidence of flood levels served to calibrate the input parameters of the hydraulic model. In a second stage, paleoflood signatures within sedimentary and botanical sequences served to verify the flood stages in the numerical simulations not only at the river reach where instrumental data exist but also in the downstream river reach. Interestingly, the rating curve obtained from the combined use of documentary information and imagery was nearly as accurate as gauging measurements. The thoughtful comparison of 2D modelled hydraulic variables against inferred values from PSIs and instrumental data supports the paleoflood reconstruction method over fixed beds. Vegetation encroachment provoked 10% deeper floods at the water discharge of 2000 m3 · s−1, which implied an increase of Manning’s roughness coefficient from 0.04 to 0.055 s · m−1/3 in less than 15 years.

  4. 40 CFR 230.25 - Salinity gradients.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Salinity gradients. 230.25 Section 230... Physical and Chemical Characteristics of the Aquatic Ecosystem § 230.25 Salinity gradients. (a) Salinity... fresh or salt water may change existing salinity gradients. For example, partial blocking of the...

  5. Gradient remediability in linear distributed parabolic systems ...

    African Journals Online (AJOL)

    The aim of this paper is the introduction of a new concept that concerned the analysis of a large class of distributed parabolic systems. It is the general concept of gradient remediability. More precisely, we study with respect to the gradient observation, the existence of an input operator (gradient efficient actuators) ensuring ...

  6. Subcritical, nontypical and period-doubling bifurcations of a delta wing in a low speed wind tunnel

    Science.gov (United States)

    Korbahti, Banu; Kagambage, Emile; Andrianne, Thomas; Abdul Razak, Norizham; Dimitriadis, Grigorios

    2011-04-01

    Limit Cycle Oscillations (LCOs) involving Delta wings are an important area of research in modern aeroelasticity. Such phenomena can be the result of geometric or aerodynamic nonlinearity. In this paper, a flexible half-span Delta wing is tested in a low speed wind tunnel in order to investigate its dynamic response. The wing is designed to be more flexible than the models used in previous research on the subject in order to expand the airspeed range in which LCOs occur. The experiments reveal that this wing features a very rich bifurcation behavior. Three types of bifurcation are observed for the first time for such an aeroelastic system: subcritical bifurcations, period-doubling/period-halving and nontypical bifurcations. They give rise to a great variety of LCOs, even at very low angles of attack. The LCOs resulting from the nontypical bifurcation display Hopf-type behavior, i.e. having fundamental frequencies equal to one of the linear modal frequencies. All of the other LCOs have fundamental frequencies that are unrelated to the underlying linear system modes.

  7. Comparing the effect of sub-critical water extraction with conventional extraction methods on the chemical composition of Lavandula stoechas.

    Science.gov (United States)

    Giray, E Sultan; Kirici, Saliha; Kaya, D Alpaslan; Türk, Murat; Sönmez, Ozgür; Inan, Memet

    2008-01-15

    The volatile extract composition of Lavandula stoechas flowers obtained by hydrodistillation (HD), subcrtical water extraction (SbCWE) and organic solvent extraction under ultrasonic irradiation (USE) were estimated by gas chromatography-mass spectrometry (GC-MS). One hundred and twenty four components were detected in SbCWE extracts while 94 and 65 signals were gained from HD and USE extracts, respectively. Most of the constituents were identified. The major compounds in all three extracts were fenchon, camphor, myrtenyl acetate, myrtenol and 1,8-cineol, but they differ in quantitatively. The total monoterpene hydrocarbons are higher in HD and USE extracts than those of SbCWE extract. However, SbCWE extract had higher concentration of light oxygenated compounds which contributes to the fragrance of the oil in a major extension. Heavy-oxygenated compounds was also in higher abundance in SbCWE extract (9.90%) than those of HD and USE extracts (3.19 and 4.78%, respectively). Effect of temperature on the extraction yield of SbCWE was investigated and while oil yield was increasing with an increase in temperature, a decrease in the extraction ability of sub-critical water toward the more polar compounds such as, 1,8-cineol, camphor and fenchon, was observed. Kinetic studies shown that SbCWE is clearly quicker than conventional alternatives. Most of components of volatile compounds were extracted at 15min.

  8. Subcritical water extraction combined with molecular imprinting technology for sample preparation in the detection of triazine herbicides.

    Science.gov (United States)

    Zhao, Fengnian; Wang, Shanshan; She, Yongxin; Zhang, Chao; Zheng, Lufei; Jin, Maojun; Shao, Hua; Jin, Fen; Du, Xinwei; Wang, Jing

    2017-09-15

    A selective, environmentally friendly, and cost-effective sample extraction method based on a combination of subcritical water extraction (SWE) and molecularly imprinted solid-phase extraction (MISPE) was developed for the determination of eight triazine herbicides in soil samples by liquid chromatography-tandem mass spectrometry (LC-MS/MS). In SWE, the highest extraction yields of triazine herbicides were obtained under 150°C for 15min using 20% ethanol as the organic modifier. Addition of MIP during SWE increased the extraction efficiency, and using MIP as a selective SPE sorbent improved the enrichment capability. Soil samples were treated with the optimized extraction MIP/SWE-MISPE method and analyzed by LC-MS/MS. The novel technique was then applied to soil samples for the determination of triazine herbicides, and better recoveries (78.9%-101%) were obtained compared with using SWE-MISPE (30%-67%). Moreover, this newly developed method displayed good linearity (R2>0.99) and precision (2.7-9.8%), and low enough detection limits (0.4-3.3μgkg-1). This combination of SWE and MIP technology is a simple, effective and promising method to selectively extract class-specific compounds in complex samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Dynamic Simulation of the Water-steam System in Once-through Boilers - Sub-critical Power Boiler Case -

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seongil; Choi, Sangmin [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2017-05-15

    The dynamics of a water-steam system in a once-through boiler was simulated based on the physics-based modeling approach, representing the system in response to large load change or scale disturbance simulations. The modeling considered the mass, energy conservation, and momentum equation in the water pipe and the focus was limited to the sub-critical pressure region. An evaporator tube modeling was validated against the reference data. A simplified boiler system consisting of economizer, evaporator, and superheater was constructed to match a 500 MW power boiler. The dynamic response of the system following a disturbance was discussed along with the quantitative response characteristics. The dynamic response of the boiler system was further evaluated by checking the case of an off-design point operation of the feedwater-to-fuel supply ratio. The results re-emphasized the significance of controlling the feedwater-to-fuel supply ratio and additional design requirements of the water-steam separator and spray attemperator.

  10. Molecular modification of native coffee polysaccharide using subcritical water treatment: Structural characterization, antioxidant, and DNA protecting activities.

    Science.gov (United States)

    Getachew, Adane Tilahun; Chun, Byung Soo

    2017-06-01

    Polysaccharides are an abundant resource in coffee beans and have proved to show numerous bioactivities. Despite their abundance, their activities are not always satisfactory mostly due to their structure and large molecular size. Molecular modifications of native polysaccharides can overcome this problem. In this study, we used a novel and green method to modify native coffee polysaccharides using subcritical water (SCW) treatment. The SCW treatment was used at the temperature of 180°C-220°C and pressure of 30-60bar. The molecular and structural modification of the polysaccharides was confirmed using several techniques such as FT-IR, UV spectroscopy, XRD, and TGA. The antioxidant activity of the modified polysaccharides was evaluated using several chemical and Saccharomyces cerevisiae-based high throughput assays. The modified polysaccharides showed high antioxidant activities in all tested assays. Moreover, the polysaccharides showed high DNA protection activities. Therefore, SCW could be employed as a green solvent for molecular modification of polysaccharides. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Transient analysis of subcritical/supercritical carbon dioxide based natural circulation loop with end heat exchangers: experimental study

    Science.gov (United States)

    Yadav, Ajay Kumar; Ramgopal, Maddali; Bhattacharyya, Souvik

    2017-09-01

    Carbon dioxide (CO2) based natural circulation loops (NCLs) has gained attention due to its compactness with higher heat transfer rate. In the present study, experimental investigations have been carried out to capture the transient behaviour of a CO2 based NCL operating under subcritical as well as supercritical conditions. Water is used as the external fluid in cold and hot heat exchangers. Results are obtained for various inlet temperatures (323-353 K) of water in the hot heat exchanger and a fixed inlet temperature (305 K) of cooling water in the cold heat exchanger. Effect of loop operating pressure (50-90 bar) on system performance is also investigated. Effect of loop tilt in two different planes (XY and YZ) is also studied in terms of transient as well as steady state behaviour of the loop. Results show that the time required to attain steady state decreases as operating pressure of the loop increases. It is also observed that the change in temperature of loop fluid (CO2) across hot or cold heat exchanger decreases as operating pressure increases.

  12. Hydrogen adsorption and diffusion, and subcritical-crack growth in high strength steels and nickel base alloys

    Science.gov (United States)

    Wei, R. P.; Klier, K.; Simmons, G. W.; Chornet, E.

    1973-01-01

    Embrittlement, or the enhancement of crack growth by gaseous hydrogen in high strength alloys, is of primary interest in selecting alloys for various components in the space shuttle. Embrittlement is known to occur at hydrogen gas pressures ranging from fractions to several hundred atmospheres, and is most severe in the case of martensitic high strength steels. Kinetic information on subcritical crack growth in gaseous hydrogen is sparse at this time. Corroborative information on hydrogen adsorption and diffusion is inadequate to permit a clear determination of the rate controlling process and possible mechanism in hydrogen enhanced crack growth, and for estimating behavior over a range of temperatures and pressures. Therefore, coordinated studies of the kinetics of crack growth, and adsorption and diffusion of hydrogen, using identical materials, have been initiated. Comparable conditions of temperature and pressure will be used in the chemical and mechanical experiments. Inconel 718 alloy and 18Ni(200) maraging steel have been selected for these studies. Results from these studies are expected to provide not only a better understanding of the gaseous hydrogen embrittlement phenomenon itself, but also fundamental information on hydrogen adsorption and diffusion, and crack growth information that can be used directly for design.

  13. Solvent tailoring in coal liquefaction. Quarterly report, May 1982-August 1982. [Comparison of subcritical and supercritical conditions

    Energy Technology Data Exchange (ETDEWEB)

    Tarrer, A.R.; Guin, J.A.; Curtis, C.W.; Williams, D.C.

    1982-01-01

    The initial objective of this work was to study the phase distribution of donor solvents and solvent mixtures during the liquefaction of coal, to investigate the effects of phase distribution on coal conversion, and to determine the advantages, if any, of operating at subcritical and/or supercritical conditions. Computer simulations were used to predict the phase distribution, for various binary systems, as a function of temperature. The FLASH program was used to theoretically predict phase distribution for various model systems. Due to limitations in the computer program, success was achieved only in a few cases. Even in these cases, the existence of two-phase regions was observed only at temperatures and pressures far below normal liquefaction conditions. An extensive review of the literature was carried out in order to survey methods of experimentally studying vapor-liquid equilibria. Finally, some preliminary laboratory studies were carried out with the use of benzothiophene-dodecane as the model reaction system. It was felt that the study of the effect of reactor configuration on conversion would provide insight into whether phase distribution or mass transfer was the limiting consideration for coal conversion. However, no conclusive results were obtained from these studies.

  14. Degradation of Acid Red 274 using H2O2 in subcritical water: application of response surface methodology.

    Science.gov (United States)

    Kayan, Berkant; Gözmen, Belgin

    2012-01-30

    In this research, the degradation of Acid Red 274 (AR 274) was investigated under subcritical water conditions using H(2)O(2), which led to the oxidative degradation of Acid Red 274 up to its 80% of mineralization. The Box-Behnken design matrix and response surface methodology (RSM) were applied in designing the experiments for evaluating the interactive effects of the three most important operating variables. Thus, the interactive effects of temperature (100-250°C), oxidant (H(2)O(2)) concentration (50-250 mM), and time (30-60 min.) on the degradation of AR 274 were investigated. A total of 17 experiments were conducted in this research, and the analysis of variance (ANOVA) indicated that the proposed quadratic model could be used for navigating the design space. The proposed model was essentially in accordance with the experimental case with correlation coefficient R(2)=0.9930 and Adj-R(2)=0.9839, respectively. The results confirmed that RSM based on the Box-Behnken design was a compatible method for optimizing the operating conditions of AR 274 degradation. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. Design-theoretical study of cascade CO2 sub-critical mechanical compression/butane ejector cooling cycle

    KAUST Repository

    Petrenko, V.O.

    2011-11-01

    In this paper an innovative micro-trigeneration system composed of a cogeneration system and a cascade refrigeration cycle is proposed. The cogeneration system is a combined heat and power system for electricity generation and heat production. The cascade refrigeration cycle is the combination of a CO2 mechanical compression refrigerating machine (MCRM), powered by generated electricity, and an ejector cooling machine (ECM), driven by waste heat and using refrigerant R600. Effect of the cycle operating conditions on ejector and ejector cycle performances is studied. Optimal geometry of the ejector and performance characteristics of ECM are determined at wide range of the operating conditions. The paper also describes a theoretical analysis of the CO2 sub-critical cycle and shows the effect of the MCRM evaporating temperature on the cascade system performance. The obtained data provide necessary information to design a small-scale cascade system with cooling capacity of 10 kW for application in micro-trigeneration systems. © 2010 Elsevier Ltd and IIR. All rights reserved.

  16. Oxygen Gradients in the Microcirculation

    Science.gov (United States)

    Pittman, Roland N.

    2010-01-01

    Early in the last century August Krogh embarked on a series of seminal studies to understand the connection between tissue metabolism and mechanisms by which the cardiovascular system supplied oxygen to meet those needs. Krogh recognized that oxygen was supplied from blood to the tissues by passive diffusion and that the most likely site for oxygen exchange was the capillary network. Studies of tissue oxygen consumption and diffusion coefficient, coupled with anatomical studies of capillarity in various tissues, led him to formulate a model of oxygen diffusion from a single capillary. Fifty years after the publication of this work, new methods were developed which allowed the direct measurement of oxygen in and around microvessels. These direct measurements have confirmed the predictions by Krogh and have led to extensions of his ideas resulting in our current understanding of oxygenation within the microcirculation. Developments during the last 40 years are reviewed, including studies of oxygen gradients in arterioles, capillaries, venules, microvessel wall and surrounding tissue. These measurements were made possible by the development and use of new methods to investigate oxygen in the microcirculation, so mention is made of oxygen microelectrodes, microspectrophotometry of haemoglobin and phosphorescence quenching microscopy. Our understanding of oxygen transport from the perspective of the microcirculation has gone from a consideration of oxygen gradients in capillaries and tissue to the realization that oxygen has the ability to diffuse from any microvessel to another location under the conditions that there exists a large enough PO2 gradient and that the permeability for oxygen along the intervening pathway is sufficient. PMID:21281453

  17. Dai-Kou type conjugate gradient methods with a line search only using gradient.

    Science.gov (United States)

    Huang, Yuanyuan; Liu, Changhe

    2017-01-01

    In this paper, the Dai-Kou type conjugate gradient methods are developed to solve the optimality condition of an unconstrained optimization, they only utilize gradient information and have broader application scope. Under suitable conditions, the developed methods are globally convergent. Numerical tests and comparisons with the PRP+ conjugate gradient method only using gradient show that the methods are efficient.

  18. Stringy bounces and gradient instabilities

    CERN Document Server

    Giovannini, Massimo

    2017-01-01

    Bouncing solutions are obtained from a generally covariant action characterized by a potential which is a nonlocal functional of the dilaton field at two separated space-time points. Gradient instabilities are shown to arise in this context but they are argued to be nongeneric. After performing a gauge-invariant and frame-invariant derivation of the evolution equations of the fluctuations, a heuristic criterium for the avoidance of pathological instabilities is proposed and corroborated by a number of explicit examples that turn out to be compatible with a quasi-flat spectrum of curvature inhomogeneities for typical wavelengths larger than the Hubble radius.

  19. Richardson constant and electrostatics in transfer-free CVD grown few-layer MoS2/graphene barristor with Schottky barrier modulation >0.6eV

    Science.gov (United States)

    Jahangir, Ifat; Uddin, M. Ahsan; Singh, Amol K.; Koley, Goutam; Chandrashekhar, M. V. S.

    2017-10-01

    We demonstrate a large area MoS2/graphene barristor, using a transfer-free method for producing 3-5 monolayer (ML) thick MoS2. The gate-controlled diodes show good rectification, with an ON/OFF ratio of ˜103. The temperature dependent back-gated study reveals Richardson's coefficient to be 80.3 ± 18.4 A/cm2/K and a mean electron effective mass of (0.66 ± 0.15)m0. Capacitance and current based measurements show the effective barrier height to vary over a large range of 0.24-0.91 eV due to incomplete field screening through the thin MoS2. Finally, we show that this barristor shows significant visible photoresponse, scaling with the Schottky barrier height. A response time of ˜10 s suggests that photoconductive gain is present in this device, resulting in high external quantum efficiency.

  20. The impact of resin-coating on sub-critical crack extension in a porcelain laminate veneer material.

    Science.gov (United States)

    Cao, Xu; Fleming, Garry J P; Addison, Owen

    2017-05-01

    Characterisation of the interaction between crack extension, crack stabilisation and stress/strain relaxation in the polymeric matrix, the interplay between stress corrosion cracking and the mechanical response of a resin-based luting adhesive within a surface defect population could extend PLV restoration longevity by optimising cementation protocols. The aim was to investigate the influence of stress corrosion cracking and the viscoelastic behaviour of a resin-based luting adhesive independently by controlling the environmental conditions operative during test specimen fabrication. The effects of stress corrosion at ceramic crack tips and potential viscoelastic responses to loading of the resin-coated impregnating cracks were isolated. Resin-coated feldspathic ceramic test specimens were fabricated in ambient humidity or following moisture exclusion. Bi-axial flexure strengths of groups (n = 20) were determined at constant loading rates of 2.5, 10, 40, 160 or 640 N/min and data was compared with uncoated controls. Fractographic analyses were performed on all fractured test specimens. Resin-cement coating resulted in significant ceramic strengthening in all conditions tested (p < 0.01). A two-way ANOVA demonstrated that the exclusion of moisture during resin- coating significantly increased mean BFS (p<0.01) but post-hoc Tukey tests identified that moisture exclusion resulted in significant increases in BFS values only at intermediate loading rates with no significant differences observed at either the fastest or slowest loading rates (640 and 2.5 N/min, respectively). Mechanical reinforcement of PLV materials by resin-cement systems is yet to be optimized. The viscoelastic behavior of the resin-cement itself can influence the magnitude of reinforcement observed and sub-critical crack growth. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  1. The Effect of Subcritical Bone Loss and Exposure on Recurrent Instability After Arthroscopic Bankart Repair in Intercollegiate American Football.

    Science.gov (United States)

    Dickens, Jonathan F; Owens, Brett D; Cameron, Kenneth L; DeBerardino, Thomas M; Masini, Brendan D; Peck, Karen Y; Svoboda, Steven J

    2017-07-01

    There is no consensus on the optimal method of stabilization (arthroscopic or open) in collision athletes with anterior shoulder instability. To examine the effect of "subcritical" bone loss and football-specific exposure on the rate of recurrent shoulder instability after arthroscopic stabilization in an intercollegiate American football population. Case-control study; Level of evidence, 3. Fifty intercollegiate football players underwent primary arthroscopic stabilization for anterior shoulder instability and returned to football for at least a single season. Preoperatively, 32 patients experienced recurrent subluxations, and 18 patients experienced a single or recurrent dislocation. Shoulders with glenoid bone loss >20%, an engaging Hill-Sachs lesion, an off-track lesion, and concomitant rotator cuff repair were excluded from the study. The primary outcome of interest was the ability to return to football without subsequent instability. Patients were followed for time to a subsequent instability event after return to play using days of exposure to football and total follow-up time after arthroscopic stabilization. Fifty consecutive patients returned to American football for a mean 1.5 seasons (range, 1-3) after arthroscopic stabilization. Three of 50 (6%; 95% CI, 1.3%-16.5%) patients experienced recurrent instability. There were no subsequent instability events after a mean 3.2 years of military service. All shoulders with glenoid bone loss >13.5% (n = 3) that underwent arthroscopic stabilization experienced recurrent instability upon returning to sport, while none of the shoulders with football ( X 2 = 15.80, P 13.5% glenoid bone loss had an incidence rate of 5.31 cases of recurrent instability per 1000 athlete-exposures of football. In 72,000 athlete-exposures to football with football players with <13.5% glenoid bone loss provides reliable outcomes and low recurrence rates.

  2. Monte Carlo modeling and analyses of YALINA-booster subcritical assembly part 1: analytical models and main neutronics parameters.

    Energy Technology Data Exchange (ETDEWEB)

    Talamo, A.; Gohar, M. Y. A.; Nuclear Engineering Division

    2008-09-11

    This study was carried out to model and analyze the YALINA-Booster facility, of the Joint Institute for Power and Nuclear Research of Belarus, with the long term objective of advancing the utilization of accelerator driven systems for the incineration of nuclear waste. The YALINA-Booster facility is a subcritical assembly, driven by an external neutron source, which has been constructed to study the neutron physics and to develop and refine methodologies to control the operation of accelerator driven systems. The external neutron source consists of Californium-252 spontaneous fission neutrons, 2.45 MeV neutrons from Deuterium-Deuterium reactions, or 14.1 MeV neutrons from Deuterium-Tritium reactions. In the latter two cases a deuteron beam is used to generate the neutrons. This study is a part of the collaborative activity between Argonne National Laboratory (ANL) of USA and the Joint Institute for Power and Nuclear Research of Belarus. In addition, the International Atomic Energy Agency (IAEA) has a coordinated research project benchmarking and comparing the results of different numerical codes with the experimental data available from the YALINA-Booster facility and ANL has a leading role coordinating the IAEA activity. The YALINA-Booster facility has been modeled according to the benchmark specifications defined for the IAEA activity without any geometrical homogenization using the Monte Carlo codes MONK and MCNP/MCNPX/MCB. The MONK model perfectly matches the MCNP one. The computational analyses have been extended through the MCB code, which is an extension of the MCNP code with burnup capability because of its additional feature for analyzing source driven multiplying assemblies. The main neutronics parameters of the YALINA-Booster facility were calculated using these computer codes with different nuclear data libraries based on ENDF/B-VI-0, -6, JEF-2.2, and JEF-3.1.

  3. Process optimization and characterization of fragrant oil from red pepper (Capsicum annuum L.) seed extracted by subcritical butane extraction.

    Science.gov (United States)

    Gu, Ling-Biao; Pang, Hui-Li; Lu, Ke-Ke; Liu, Hua-Min; Wang, Xue-De; Qin, Guang-Yong

    2017-04-01

    Red pepper seeds account for 450-500 g kg-1 of the total pepper weight and are often discarded as waste. In this study, process optimization and characterization of fragrant oil from roasted red pepper seed extracted by subcritical butane extraction were carried out. The optimal conditions of extraction were a temperature of 74.61 °C, a time of 68.65 min and a liquid/solid ratio of 30.24:1. The oil had a refractive index (25 °C) of 1.471, a relative density of 0.900, an acid value of 1.421 mg g-1 oil, an iodine value of 127.035 g per 100 g, a saponification value of 184.060 mg KOH g-1 , an unsaponifiable matter content of 12.400 g kg-1 , a peroxide value of 2.465 meq. O2 kg-1 and a viscosity of 52.094 cP. The main fatty acids in the oil were linoleic acid (72.95%) followed by palmitic acid (11.43%) and oleic acid (10.00%). The oil showed desirable thermal and oxidative stability. A total of 19 volatile compounds, mostly aldehydes and alkenes, were identified from the oil. The results indicated that the method is appropriate for the preparation of fragrant red pepper seed oil, and the oil is suitable for used as edible oil. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  4. Physics design of a 10 MeV injector test stand for an accelerator-driven subcritical system

    Directory of Open Access Journals (Sweden)

    Fang Yan

    2015-05-01

    Full Text Available The 10 MeV accelerator-driven subcritical system (ADS Injector I test stand at Institute of High Energy Physics (IHEP is a testing facility dedicated to demonstrate one of the two injector design schemes [Injector Scheme-I, which works at 325 MHz], for the ADS project in China. The injector is composed of two parts, the linac part and the beam dump line. The former is designed on the basis of 325 MHz four-vane type copper structure radio frequency quadrupole and superconducting (SC spoke cavities with β=0.12. The latter is designed to transport the beam coming out of the SC section of the linac to the beam dump, where the beam transverse profile is fairly enlarged and unformed to simplify the beam target design. The SC section consists of two cryomodules with 14 β=0.12 Spoke cavities, 14 solenoid and 14 BPMs in total. The first challenge in the physics design comes from the necessary space required for the cryomodule separation where the periodical lattice is destroyed at a relatively lower energy of ∼5  MeV. Another challenge is the beam dump line design, as it will be the first beam dump line being built by using a step field magnet for the transverse beam expansion and uniformity in the world. This paper gives an overview of the physics design study together with the design principles and machine construction considerations. The results of an optimized design, fabrication status and end to end simulations including machine errors are presented.

  5. The study of isochoric subcritical water using power series: A potential of energy generation with ISCW reactor

    Science.gov (United States)

    Sangian, Hanny F.; Tunena, Mercyas; Pani, Sutaryono

    2017-09-01

    The present study was aimed to analyze the behaviors of PVT and Z of ISCW (isochoric subcritical water) condition using mathematical series. The data showed that the pressure extremely increased from 15 bars until 80 bars taking only a few seconds that was probably to generate energy. The study was initiated by formulating power series in term of P and T with parameters, a0, a1, a2, a3, a4, a5, a6, and a7 whereas they were solved by performing the fitting method. By employing that technique, parameters were obtained as follows: a0= 7.63x-6, a1=0.23K/bar, a2=0.0035K2/bar2, a3=0.0068 K3/bar3, a4=8.27x10-7K4/bar4, a5=1.33x10-7K5/bar5, a6=2.18x10-8K6/bar6, and a7=3.64x10-9K7/bar7. Compressibility factor increased as pressure and temperature improved. In an isochoric condition, there was extremity that was located at a temperature above 450K in which compressibility factor abruptly increased with the tangent of the line was infinity. All parameters attaching on terms of a mathematical model proposed were assumed constant during P and T increase. At the request of the authors of the paper and with the agreement of the proceedings editor, an updated version of this article was published on 4 October 2017. The original version supplied to AIP Publishing included an incorrect spelling in the name of the first author. This has been corrected in the updated and re-published version.

  6. Unnatural Narratology. Basic Concepts and Recent Work [Jan Alber / Rüdiger Heinze: Unnatural Narratives – Unnatural Narratology. Berlin 2011. Per Krogh Hansen / Stefan Iversen / Henrik Skov Nielsen / Rolf Reitan (Eds.: Strange Voices in Narrative Fiction. Berlin 2011. David Herman / James Phelan / Peter Rabinowitz / Brian Richardson / Robyn Warhol: Narrative Theory: Core Concepts and Critical Debates. Columbus 2012

    Directory of Open Access Journals (Sweden)

    Brian Richardson

    2012-12-01

    Full Text Available Rezension zu / Review of:Jan Alber / Rüdiger Heinze: Unnatural Narratives – Unnatural Narratology. Berlin 2011. Per Krogh Hansen / Stefan Iversen / Henrik Skov Nielsen / Rolf Reitan (Eds.: Strange Voices in Narrative Fiction. Berlin  2011. David Herman / James Phelan / Peter Rabinowitz / Brian Richardson / Robyn Warhol: Narrative Theory: Core Concepts and Critical Debates. Columbus 2012.

  7. Superconductors in a temperature gradient

    CERN Document Server

    Huebener, Rudolf Peter

    1995-01-01

    In the mixed state of a type II superconductor quasiparticles and magnetic flux quanta respond to a temperature gradient by thermal diffusion, in this way generating the Seebeck and Nernst effects, respectively. Our understanding of the Seebeck effect originates from an extension of the two-fluid counterflow concept, originally introduced by Ginzburg, to the situation where vortices (with a normal core) are imbedded in the superconducting phase. This mechanism results in an intimate connection between the Seebeck coefficient and the electric resistivity due to vortex motion. In all thermal diffusion processes it is the transport entropy of the diffusing species that determines the driving force, and the physics of this quantity is illustrated. Our discussion of the experimental side concentrates on the recent work performed with the cuprate superconductors. The characteristic broadening of the resistive transition in the mixed state, found in these materials due to their high anisotropy and the peculiar vorte...

  8. The Educational Gradient in Health in China

    Science.gov (United States)

    Chen, Qiulin; Eggleston, Karen; Zhang, Wei; Zhao, Jiaying; Zhou, Sen

    2017-01-01

    It has been well established that better educated individuals enjoy better health and longevity. In theory, the educational gradients in health could be flattening if diminishing returns to improved average education levels and the influence of earlier population health interventions outweigh the gradient-steepening effects of new medical and health technologies. This paper documents how the gradients are evolving in China, a rapidly developing country, about which little is known on this topic. Based on recent mortality data and nationally representative health surveys, we find large and, in some cases, steepening educational gradients. We also find that the gradients vary by cohort, gender and region. Further, we find that the gradients can only partially be accounted for by economic factors. These patterns highlight the double disadvantage of those with low education, and suggest the importance of policy interventions that foster both aspects of human capital for them. PMID:29056815

  9. Community and ecosystem responses to elevational gradients

    DEFF Research Database (Denmark)

    Sundqvist, Maja K.; Sanders, Nate; Wardle, David A.

    2013-01-01

    Community structure and ecosystem processes often vary along elevational gradients. Their responses to elevation are commonly driven by changes in temperature, and many community- and ecosystem-level variables therefore frequently respond similarly to elevation across contrasting gradients. There...... will provide powerful information that can improve predictions of climate change impacts within and across ecosystems.......Community structure and ecosystem processes often vary along elevational gradients. Their responses to elevation are commonly driven by changes in temperature, and many community- and ecosystem-level variables therefore frequently respond similarly to elevation across contrasting gradients...... elevational gradients for understanding community and ecosystem responses to global climate change at much larger spatial and temporal scales than is possible through conventional ecological experiments. However, future studies that integrate elevational gradient approaches with experimental manipulations...

  10. Effect of Carreau-Yasuda rheological parameters on subcritical Lapwood convection in horizontal porous cavity saturated by shear-thinning fluid

    Science.gov (United States)

    Khechiba, Khaled; Mamou, Mahmoud; Hachemi, Madjid; Delenda, Nassim; Rebhi, Redha

    2017-06-01

    The present study is focused on Lapwood convection in isotropic porous media saturated with non-Newtonian shear thinning fluid. The non-Newtonian rheological behavior of the fluid is modeled using the general viscosity model of Carreau-Yasuda. The convection configuration consists of a shallow porous cavity with a finite aspect ratio and subject to a vertical constant heat flux, whereas the vertical walls are maintained impermeable and adiabatic. An approximate analytical solution is developed on the basis of the parallel flow assumption, and numerical solutions are obtained by solving the full governing equations. The Darcy model with the Boussinesq approximation and energy transport equations are solved numerically using a finite difference method. The results are obtained in terms of the Nusselt number and the flow fields as functions of the governing parameters. A good agreement is obtained between the analytical approximation and the numerical solution of the full governing equations. The effects of the rheological parameters of the Carreau-Yasuda fluid and Rayleigh number on the onset of subcritical convection thresholds are demonstrated. Regardless of the aspect ratio of the enclosure and thermal boundary condition type, the subcritical convective flows are seen to occur below the onset of stationary convection. Correlations are proposed to estimate the subcritical Rayleigh number for the onset of finite amplitude convection as a function of the fluid rheological parameters. Linear stability of the convective motion, predicted by the parallel flow approximation, is studied, and the onset of Hopf bifurcation, from steady convective flow to oscillatory behavior, is found to depend strongly on the rheological parameters. In general, Hopf bifurcation is triggered earlier as the fluid becomes more and more shear-thinning.

  11. Color and population gradients in globular clusters

    Science.gov (United States)

    Djorgovski, S.; Piotto, G.; Mallen-Ornelas, G.

    1991-01-01

    We present preliminary results from a survey for color and population gradients in globular cluster cores. Color gradients, in the sense of becoming bluer inwards, are always found in post-core-collapse clusters. They seem to be caused by the demise of red giants, and possibly an increased number of blue stragglers. This may be a consequence of stellar interactions during and after the core collapse. No gradients are seen in clusters with King-model morphology.

  12. Ant colony optimization and stochastic gradient descent.

    Science.gov (United States)

    Meuleau, Nicolas; Dorigo, Marco

    2002-01-01

    In this article, we study the relationship between the two techniques known as ant colony optimization (ACO) and stochastic gradient descent. More precisely, we show that some empirical ACO algorithms approximate stochastic gradient descent in the space of pheromones, and we propose an implementation of stochastic gradient descent that belongs to the family of ACO algorithms. We then use this insight to explore the mutual contributions of the two techniques.

  13. Testing the limits of gradient sensing.

    Directory of Open Access Journals (Sweden)

    Vinal Lakhani

    2017-02-01

    Full Text Available The ability to detect a chemical gradient is fundamental to many cellular processes. In multicellular organisms gradient sensing plays an important role in many physiological processes such as wound healing and development. Unicellular organisms use gradient sensing to move (chemotaxis or grow (chemotropism towards a favorable environment. Some cells are capable of detecting extremely shallow gradients, even in the presence of significant molecular-level noise. For example, yeast have been reported to detect pheromone gradients as shallow as 0.1 nM/μm. Noise reduction mechanisms, such as time-averaging and the internalization of pheromone molecules, have been proposed to explain how yeast cells filter fluctuations and detect shallow gradients. Here, we use a Particle-Based Reaction-Diffusion model of ligand-receptor dynamics to test the effectiveness of these mechanisms and to determine the limits of gradient sensing. In particular, we develop novel simulation methods for establishing chemical gradients that not only allow us to study gradient sensing under steady-state conditions, but also take into account transient effects as the gradient forms. Based on reported measurements of reaction rates, our results indicate neither time-averaging nor receptor endocytosis significantly improves the cell's accuracy in detecting gradients over time scales associated with the initiation of polarized growth. Additionally, our results demonstrate the physical barrier of the cell membrane sharpens chemical gradients across the cell. While our studies are motivated by the mating response of yeast, we believe our results and simulation methods will find applications in many different contexts.

  14. Optimum design and criticality safety of a beam-shaping assembly with an accelerator-driven subcritical neutron multiplier for boron neutron capture therapies.

    Science.gov (United States)

    Hiraga, F

    2015-12-01

    The beam-shaping assembly for boron neutron capture therapies with a compact accelerator-driven subcritical neutron multiplier was designed so that an epithermal neutron flux of 1.9×10(9) cm(-2) s(-1) at the treatment position was generated by 5 MeV protons in a beam current of 2 mA. Changes in the atomic density of (135)Xe in the nuclear fuel due to the operation of the beam-shaping assembly were estimated. The criticality safety of the beam-shaping assembly in terms of Xe poisoning is discussed. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. (n,xn) cross section measurements for Y-89 foils used as detectors for high energy neutron measurements in the deeply subcritical assembly "QUINTA"

    Science.gov (United States)

    Bielewicz, Marcin; Kilim, Stanisław; Strugalska-Gola, Elżbieta; Szuta, Marcin; Wojciechowski, Andrzej; Tyutyunnikov, Sergey; Prokofiev, Alexander; Passoth, Elke

    2017-09-01

    Study of the deep subcritical systems (QUINTA) using relativistic beams is performed within the project "Energy and Transmutation of Radioactive Wastes" (E&T - RAW). The experiment assembly was irradiated by deuteron/proton beam (Dubna NUCLOTRON). We calculated the neutron energy spectrum inside the whole assembly by using threshold energy (n,xn) reactions in yttrium (Y-89) foils. There are almost no experimental cross section data for those reactions. New Y-89(n,xn) cross section measurements were carried out at The Svedberg laboratory (TSL) in Uppsala, Sweden in 2015. In this paper we present preliminary results of those experiments.

  16. SubcriticalWater – a Perspective ReactionMedia for Biomass Processing to Chemicals: Study on Cellulose Conversion as aModel for Biomass

    OpenAIRE

    Pavlovič, I.; Knez, Ž.; Škerget, M.

    2013-01-01

    Biomass and water are recognized as a key renewable feedstock in sustainable production of chemicals, fuels and energy. Subcritical water (SubCW), or commonly referred as hot compressed water (HCW), is the water above boiling and below critical point (CP; 374 °C, 22.1 MPa). It has gained great attention in the last few decades as a green, cheap, and nontoxic reagent for conversion of biomass into valuable chemicals. In this paper, hydrothermal reactions of cellulose, as the model biomass s...

  17. (n,xn cross section measurements for Y-89 foils used as detectors for high energy neutron measurements in the deeply subcritical assembly “QUINTA”

    Directory of Open Access Journals (Sweden)

    Bielewicz Marcin

    2017-01-01

    Full Text Available Study of the deep subcritical systems (QUINTA using relativistic beams is performed within the project “Energy and Transmutation of Radioactive Wastes” (E&T – RAW. The experiment assembly was irradiated by deuteron/proton beam (Dubna NUCLOTRON. We calculated the neutron energy spectrum inside the whole assembly by using threshold energy (n,xn reactions in yttrium (Y-89 foils. There are almost no experimental cross section data for those reactions. New Y-89(n,xn cross section measurements were carried out at The Svedberg laboratory (TSL in Uppsala, Sweden in 2015. In this paper we present preliminary results of those experiments.

  18. Canonical trivialization of gravitational gradients

    Science.gov (United States)

    Niedermaier, Max

    2017-06-01

    A one-parameter family of canonical transformations is constructed that reduces the Hamiltonian form of the Einstein-Hilbert action to its strong coupling limit where dynamical spatial gradients are absent. The parameter can alternatively be viewed as the overall scale of the spatial metric or as a fractional inverse power of Newton’s constant. The generating function of the canonical transformation is constructed iteratively as a powerseries in the parameter to all orders. The algorithm draws on Lie-Deprit transformation theory and defines a ‘trivialization map’ with several bonus properties: (i) Trivialization of the Hamiltonian constraint implies that of the action while the diffeomorphism constraint is automatically co-transformed. (ii) Only a set of ordinary differential equations needs to be solved to drive the iteration via a homological equation where no gauge fixing is required. (iii) In contrast to (the classical limit of) a Lagrangian trivialization map the algorithm also produces series solutions of the field equations. (iv) In the strong coupling theory temporal gauge variations are abelian, nevertheless the map intertwines with the respective gauge symmetries on the action, the field equations, and their solutions.

  19. Regulation of leaf traits in canopy gradients.

    NARCIS (Netherlands)

    Pons, T.L.|info:eu-repo/dai/nl/069365822

    2016-01-01

    The gradient of leaf traits in a canopy from sunlit upper regions to shaded lower ones is regulated in response to the density of its leaf area. The gradients of environmental factors act as signals for the regulation. The result is improved resource use efficiency for carbon gain at the whole plant

  20. Preconditioning the modified conjugate gradient method ...

    African Journals Online (AJOL)

    In this paper, the convergence analysis of the conventional conjugate Gradient method was reviewed. And the convergence analysis of the modified conjugate Gradient method was analysed with our extension on preconditioning the algorithm. Convergence of the algorithm is a function of the condition number of M-1A.

  1. Gradient High Performance Liquid Chromatography Method ...

    African Journals Online (AJOL)

    Purpose: To develop a gradient high performance liquid chromatography (HPLC) method for the simultaneous determination of phenylephrine (PHE) and ibuprofen (IBU) in solid dosage form. Methods: HPLC determination was carried out on an Agilent XDB C-18 column (4.6 x 150mm, 5 μ particle size) with a gradient ...

  2. An Inexpensive Digital Gradient Controller for HPLC.

    Science.gov (United States)

    Brady, James E.; Carr, Peter W.

    1983-01-01

    Use of gradient elution techniques in high performance liquid chromatography (HPLC) is often essential for direct separation of complex mixtures. Since most commercial controllers have features that are of marginal value for instructional purposes, a low-cost controller capable of illustrating essential features of gradient elution was developed.…

  3. Newton's method in the context of gradients

    Directory of Open Access Journals (Sweden)

    John W. Neuberger

    2007-09-01

    Full Text Available This paper gives a common theoretical treatment for gradient and Newton type methods for general classes of problems. First, for Euler-Lagrange equations Newton's method is characterized as an (asymptotically optimal variable steepest descent method. Second, Sobolev gradient type minimization is developed for general problems using a continuous Newton method which takes into account a "boundary condition" operator.

  4. Patterns of macromycete community assemblage along an elevation gradient: options for fungal gradient and metacommunity analyse

    Science.gov (United States)

    Marko Gómez-Hernández; Guadalupe Williams-Linera; Roger Guevara; D. Jean Lodge

    2012-01-01

    Gradient analysis is rarely used in studies of fungal communities. Data on macromycetes from eight sites along an elevation gradient in central Veracruz, Mexico, were used to demonstrate methods for gradient analysis that can be applied to studies of communities of fungi. Selected sites from 100 to 3,500 m altitude represent tropical dry forest, tropical montane cloud...

  5. Subcritical crack propagation due to chemical rock weakening: macroscale chemo-plasticity and chemo-elasticity modeling

    Science.gov (United States)

    Hueckel, T.; Hu, M.

    2015-12-01

    Crack propagation in a subcritically stressed rock subject to chemically aggressive environment is analyzed and numerically simulated. Chemically induced weakening is often encountered in hydraulic fracturing of low-permeability oil/gas reservoirs and heat reservoirs, during storage of CO2 and nuclear waste corroding canisters, and other circumstances when rock matrix acidizing is involved. Upon acidizing, mineral mass dissolution is substantially enhanced weakening the rock and causing crack propagation and eventually permeability changes in the medium. The crack process zone is modeled mathematically via a chemo-plastic coupling and chemo-elastic coupling model. In plasticity a two-way coupling is postulated between mineral dissolution and a yield limit of rock matrix. The rate of dissolution is described by a rate law, but the mineral mass removal per unit volume is also a function of a variable internal specific surface area, which is in turn affected by the micro-cracking (treated as a plastic strain). The behavior of the rock matrix is modeled as rigid-plastic adding a chemical softening capacity to Cam-Clay model. Adopting the Extended Johnson's approximation of processes around the crack tip, the evolution of the stress field and deformation as a function of the chemically enhanced rock damage is modeled in a simplified way. In addition, chemical reactive transport is made dependent on plastic strain representing micro-cracking. Depending on mechanical and chemical boundary conditions, the area of enhanced chemical softening is near or somewhat away from the crack tip.In elasticity, chemo-mechanical effect is postulated via a chemical volumetric shrinkage strain proportional to mass removal variable, conceived analogously to thermal expansion. Two versions are considered: of constant coefficient of shrinkage and a variable one, coupled to deviatoric strain. Airy Potential approach used for linear elasticity is extended considering an extra term, which is

  6. Subcritical CO{sub 2} sintering of microspheres of different polymeric materials to fabricate scaffolds for tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Bhamidipati, Manjari; Sridharan, BanuPriya [Bioengineering Graduate Program, University of Kansas, Lawrence, KS (United States); Scurto, Aaron M. [Bioengineering Graduate Program, University of Kansas, Lawrence, KS (United States); Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, KS (United States); Detamore, Michael S., E-mail: detamore@ku.edu [Bioengineering Graduate Program, University of Kansas, Lawrence, KS (United States); Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, KS (United States)

    2013-12-01

    The aim of this study was to use CO{sub 2} at sub-critical pressures as a tool to sinter 3D, macroporous, microsphere-based scaffolds for bone and cartilage tissue engineering. Porous scaffolds composed of ∼ 200 μm microspheres of either poly(lactic-co-glycolic acid) (PLGA) or polycaprolactone (PCL) were prepared using dense phase CO{sub 2} sintering, which were seeded with rat bone marrow mesenchymal stromal cells (rBMSCs), and exposed to either osteogenic (PLGA, PCL) or chondrogenic (PLGA) conditions for 6 weeks. Under osteogenic conditions, the PLGA constructs produced over an order of magnitude more calcium than the PCL constructs, whereas the PCL constructs had far superior mechanical and structural integrity (125 times stiffer than PLGA constructs) at week 6, along with twice the cell content of the PLGA constructs. Chondrogenic cell performance was limited in PLGA constructs, perhaps as a result of the polymer degradation rate being too high. The current study represents the first long-term culture of CO{sub 2}-sintered microsphere-based scaffolds, and has established important thermodynamic differences in sintering between the selected formulations of PLGA and PCL, with the former requiring adjustment of pressure only, and the latter requiring the adjustment of both pressure and temperature. Based on more straightforward sintering conditions and more favorable cell performance, PLGA may be the material of choice for microspheres in a CO{sub 2} sintering application, although a different PLGA formulation with the encapsulation of growth factors, extracellular matrix-derived nanoparticles, and/or buffers in the microspheres may be advantageous for achieving a more superior cell performance than observed here. - Highlights: • The first long-term culture of CO{sub 2}-sintered microsphere-based scaffolds. • Established important thermodynamic differences between sintering PLGA and PCL. • PCL sintering with CO{sub 2} required manipulation of both

  7. Approximate error conjugation gradient minimization methods

    Science.gov (United States)

    Kallman, Jeffrey S

    2013-05-21

    In one embodiment, a method includes selecting a subset of rays from a set of all rays to use in an error calculation for a constrained conjugate gradient minimization problem, calculating an approximate error using the subset of rays, and calculating a minimum in a conjugate gradient direction based on the approximate error. In another embodiment, a system includes a processor for executing logic, logic for selecting a subset of rays from a set of all rays to use in an error calculation for a constrained conjugate gradient minimization problem, logic for calculating an approximate error using the subset of rays, and logic for calculating a minimum in a conjugate gradient direction based on the approximate error. In other embodiments, computer program products, methods, and systems are described capable of using approximate error in constrained conjugate gradient minimization problems.

  8. Dual fuel gradients in uranium silicide plates

    Energy Technology Data Exchange (ETDEWEB)

    Pace, B.W. [Babock and Wilcox, Lynchburg, VA (United States)

    1997-08-01

    Babcock & Wilcox has been able to achieve dual gradient plates with good repeatability in small lots of U{sub 3}Si{sub 2} plates. Improvements in homogeneity and other processing parameters and techniques have allowed the development of contoured fuel within the cladding. The most difficult obstacles to overcome have been the ability to evaluate the bidirectional fuel loadings in comparison to the perfect loading model and the different methods of instilling the gradients in the early compact stage. The overriding conclusion is that to control the contour of the fuel, a known relationship between the compact, the frames and final core gradient must exist. Therefore, further development in the creation and control of dual gradients in fuel plates will involve arriving at a plausible gradient requirement and building the correct model between the compact configuration and the final contoured loading requirements.

  9. Protein gradient films of fibroin and gelatine.

    Science.gov (United States)

    Claussen, Kai U; Lintz, Eileen S; Giesa, Reiner; Schmidt, Hans-Werner; Scheibel, Thomas

    2013-10-01

    Gradients are a natural design principle in biological systems that are used to diminish stress concentration where materials of differing mechanical properties connect. An interesting example of a natural gradient material is byssus, which anchors mussels to rocks and other hard substrata. Building upon previous work with synthetic polymers and inspired by byssal threads, protein gradient films are cast using glycerine-plasticized gelatine and fibroin exhibiting a highly reproducible and smooth mechanical gradient, which encompasses a large range of modulus from 160 to 550 MPa. The reproducible production of biocompatible gradient films represents a first step towards medical applications. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Experimental Assessment of a Helical Coil Heat Exchanger Operating at Subcritical and Supercritical Conditions in a Small-Scale Solar Organic Rankine Cycle

    Directory of Open Access Journals (Sweden)

    Marija Lazova

    2017-05-01

    Full Text Available In this study, the performance of a helical coil heat exchanger operating at subcritical and supercritical conditions is analysed. The counter-current heat exchanger was specially designed to operate at a maximal pressure and temperature of 42 bar and 200 °C, respectively. The small-scale solar organic Rankine cycle (ORC installation has a net power output of 3 kWe. The first tests were done in a laboratory where an electrical heater was used instead of the concentrated photovoltaic/thermal (CPV/T collectors. The inlet heating fluid temperature of the water was 95 °C. The effects of different parameters on the heat transfer rate in the heat exchanger were investigated. Particularly, the performance analysis was elaborated considering the changes of the mass flow rate of the working fluid (R-404A in the range of 0.20–0.33 kg/s and the inlet pressure varying from 18 bar up to 41 bar. Hence, the variation of the heat flux was in the range of 5–9 kW/m2. The results show that the working fluid’s mass flow rate has significant influence on the heat transfer rate rather than the operational pressure. Furthermore, from the comparison between the experimental results with the heat transfer correlations from the literature, the experimental results fall within the uncertainty range for the supercritical analysis but there is a deviation of the investigated subcritical correlations.

  11. The use of sub-critical water hydrolysis for the recovery of peptides and free amino acids from food processing wastes. Review of sources and main parameters.

    Science.gov (United States)

    Marcet, Ismael; Álvarez, Carlos; Paredes, Benjamín; Díaz, Mario

    2016-03-01

    Food industry processing wastes are produced in enormous amounts every year, such wastes are usually disposed with the corresponding economical cost it implies, in the best scenario they can be used for pet food or composting. However new promising technologies and tools have been developed in the last years aimed at recovering valuable compounds from this type of materials. In particular, sub-critical water hydrolysis (SWH) has been revealed as an interesting way for recovering high added-value molecules, and its applications have been broadly referred in the bibliography. Special interest has been focused on recovering protein hydrolysates in form of peptides or amino acids, from both animal and vegetable wastes, by means of SWH. These recovered biomolecules have a capital importance in fields such as biotechnology research, nutraceuticals, and above all in food industry, where such products can be applied with very different objectives. Present work reviews the current state of art of using sub-critical water hydrolysis for protein recovering from food industry wastes. Key parameters as reaction time, temperature, amino acid degradation and kinetic constants have been discussed. Besides, the characteristics of the raw material and the type of products that can be obtained depending on the substrate have been reviewed. Finally, the application of these hydrolysates based on their functional properties and antioxidant activity is described. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Recovery of Oil with Unsaturated Fatty Acids and Polyphenols from Chaenomelessinensis (Thouin) Koehne: Process Optimization of Pilot-Scale Subcritical Fluid Assisted Extraction.

    Science.gov (United States)

    Zhu, Zhenzhou; Zhang, Rui; Zhan, Shaoying; He, Jingren; Barba, Francisco J; Cravotto, Giancarlo; Wu, Weizhong; Li, Shuyi

    2017-10-22

    The potential effects of three modern extraction technologies (cold-pressing, microwaves and subcritical fluids) on the recovery of oil from Chaenomelessinensis (Thouin) Koehne seeds have been evaluated and compared to those of conventional chemical extraction methods (Soxhlet extraction). This oil contains unsaturated fatty acids and polyphenols. Subcritical fluid extraction (SbFE) provided the highest yield-25.79 g oil/100 g dry seeds-of the three methods. Moreover, the fatty acid composition in the oil samples was analysed using gas chromatography-mass spectrometry. This analysis showed that the percentages of monounsaturated (46.61%), and polyunsaturated fatty acids (42.14%), after applying SbFE were higher than those obtained by Soxhlet, cold-pressing or microwave-assisted extraction. In addition, the oil obtained under optimized SbFE conditions (35 min extraction at 35 °C with four extraction cycles), showed significant polyphenol (527.36 mg GAE/kg oil), and flavonoid (15.32 mg RE/kg oil), content, had a good appearance and was of high quality.

  13. YALINA facility a sub-critical Accelerator- Driven System (ADS) for nuclear energy research facility description and an overview of the research program (1997-2008).

    Energy Technology Data Exchange (ETDEWEB)

    Gohar, Y.; Smith, D. L.; Nuclear Engineering Division

    2010-04-28

    The YALINA facility is a zero-power, sub-critical assembly driven by a conventional neutron generator. It was conceived, constructed, and put into operation at the Radiation Physics and Chemistry Problems Institute of the National Academy of Sciences of Belarus located in Minsk-Sosny, Belarus. This facility was conceived for the purpose of investigating the static and dynamic neutronics properties of accelerator driven sub-critical systems, and to serve as a neutron source for investigating the properties of nuclear reactions, in particular transmutation reactions involving minor-actinide nuclei. This report provides a detailed description of this facility and documents the progress of research carried out there during a period of approximately a decade since the facility was conceived and built until the end of 2008. During its history of development and operation to date (1997-2008), the YALINA facility has hosted several foreign groups that worked with the resident staff as collaborators. The participation of Argonne National Laboratory in the YALINA research programs commenced in 2005. For obvious reasons, special emphasis is placed in this report on the work at YALINA facility that has involved Argonne's participation. Attention is given here to the experimental program at YALINA facility as well as to analytical investigations aimed at validating codes and computational procedures and at providing a better understanding of the physics and operational behavior of the YALINA facility in particular, and ADS systems in general, during the period 1997-2008.

  14. Basic concept for an accelerator-driven subcritical system to be used as a long-pulse neutron source for Condensed Matter research

    Energy Technology Data Exchange (ETDEWEB)

    Vivanco, R., E-mail: raul.vivanco.sanchez@gmail.com [ESS-BILBAO, Parque Tecnológico Bizkaia, Laida Bidea, Edificio 207 B Planta Baja, 48160 Derio (Spain); Instituto de Fusión Nuclear - UPM, ETS Ingenieros Industriales, C/ José Gutiérrez Abascal, 2, 28006 Madrid Spain (Spain); Ghiglino, A.; Vicente, J.P. de; Sordo, F.; Terrón, S.; Magán, M. [ESS-BILBAO, Parque Tecnológico Bizkaia, Laida Bidea, Edificio 207 B Planta Baja, 48160 Derio (Spain); Instituto de Fusión Nuclear - UPM, ETS Ingenieros Industriales, C/ José Gutiérrez Abascal, 2, 28006 Madrid Spain (Spain); Perlado, J.M. [Instituto de Fusión Nuclear - UPM, ETS Ingenieros Industriales, C/ José Gutiérrez Abascal, 2, 28006 Madrid Spain (Spain); Bermejo, F.J. [Instituto de Estructura de la Materia, IEM-CSIC, Consejo Superior de Investigaciones Científicas, Serrano 123, 28006 Madrid (Spain)

    2014-12-11

    A model for an accelerator-driven subcritical system to be operated as a source of cold neutrons for Condensed Matter research is developed at the conceptual level. Its baseline layout relies upon proven accelerator, spalattion target and fuel array technologies, and consists in a proton accelerator able to deliver some 67.5 mA of proton beam with kinetic energy 0.6 GeV, a pulse length of 2.86 ms, and repetition rate of 14 Hz. The particle beam hits a target of conventional design that is surrounded by a multiplicative core made of fissile/fertile material, composed by a subcritical array of fuel bars made of aluminium Cermet cooled by light water poisoned with boric acid. Relatively low enriched uranium is chosen as fissile material. An optimisation of several parameters is carried out, using as components of the objective function several characteristics pertaining the cold neutron pulse. The results show that the optimal device will deliver up to 80% of the cold neutron flux expected for some of the ongoing projects using a significantly lower proton beam power than that managed in such projects. The total power developed within the core rises up to 22.8 MW, and the criticality range shifts to a final k{sub eff} value of around 0.9 after the 50 days cycle.

  15. Integrated modeling of CO2 storage and leakage scenarios including transitions between super- and sub-critical conditions, and phase change between liquid and gaseous CO2

    Energy Technology Data Exchange (ETDEWEB)

    Pruess, K.

    2011-05-15

    Storage of CO{sub 2} in saline aquifers is intended to be at supercritical pressure and temperature conditions, but CO{sub 2} leaking from a geologic storage reservoir and migrating toward the land surface (through faults, fractures, or improperly abandoned wells) would reach subcritical conditions at depths shallower than 500-750 m. At these and shallower depths, subcritical CO{sub 2} can form two-phase mixtures of liquid and gaseous CO{sub 2}, with significant latent heat effects during boiling and condensation. Additional strongly non-isothermal effects can arise from decompression of gas-like subcritical CO{sub 2}, the so-called Joule-Thomson effect. Integrated modeling of CO{sub 2} storage and leakage requires the ability to model non-isothermal flows of brine and CO{sub 2} at conditions that range from supercritical to subcritical, including three-phase flow of aqueous phase, and both liquid and gaseous CO{sub 2}. In this paper, we describe and demonstrate comprehensive simulation capabilities that can cope with all possible phase conditions in brine-CO{sub 2} systems. Our model formulation includes: (1) an accurate description of thermophysical properties of aqueous and CO{sub 2}-rich phases as functions of temperature, pressure, salinity and CO{sub 2} content, including the mutual dissolution of CO{sub 2} and H{sub 2}O; (2) transitions between super- and subcritical conditions, including phase change between liquid and gaseous CO{sub 2}; (3) one-, two-, and three-phase flow of brine-CO{sub 2} mixtures, including heat flow; (4) non-isothermal effects associated with phase change, mutual dissolution of CO{sub 2} and water, and (de-) compression effects; and (5) the effects of dissolved NaCl, and the possibility of precipitating solid halite, with associated porosity and permeability change. Applications to specific leakage scenarios demonstrate that the peculiar thermophysical properties of CO{sub 2} provide a potential for positive as well as negative

  16. Chemically grafted carbon nanotube surface coverage gradients.

    Science.gov (United States)

    Shearer, Cameron J; Ellis, Amanda V; Shapter, Joseph G; Voelcker, Nicolas H

    2010-12-07

    Two approaches to producing gradients of vertically aligned single-walled carbon nanotubes (SWCNTs) on silicon surfaces by chemical grafting are presented here. The first approach involves the use of a porous silicon (pSi) substrate featuring a pore size gradient, which is functionalized with 3-aminopropyltriethoxysilane (APTES). Carboxylated SWCNTs are then immobilized on the topography gradient via carbodiimide coupling. Our results show that as the pSi pore size and porosity increase across the substrate the SWCNT coverage decreases concurrently. In contrast, the second gradient is an amine-functionality gradient produced by means of vapor-phase diffusion of APTES from a reservoir onto a silicon wafer where APTES attachment changes as a function of distance from the APTES reservoir. Carboxylated SWCNTs are then immobilized via carbodiimide coupling to the amine-terminated silicon gradient. Our observations confirm that with decreasing APTES density on the surface the coverage of the attached SWCNTs also decreases. These gradient platforms pave the way for the time-efficient optimization of SWCNT coverage for applications ranging from field emission to water filtration to drug delivery.

  17. Chemical gradients and chemotropism in yeast.

    Science.gov (United States)

    Arkowitz, Robert A

    2009-08-01

    Chemical gradients of peptide mating pheromones are necessary for directional growth, which is critical for yeast mating. These gradients are generated by cell-type specific secretion or export and specific degradation in receiving cells. Spatial information is sensed by dedicated seven-transmembrane G-protein coupled receptors and yeast cells are able to detect extremely small differences in ligand concentration across their approximately 5-microm cell surface. Here, I will discuss our current knowledge of how cells detect and respond to such shallow chemical gradients and in particular what is known about the proteins that are involved in directional growth and the establishment of the polarity axis during yeast mating.

  18. Sound beam manipulation based on temperature gradients

    Energy Technology Data Exchange (ETDEWEB)

    Qian, Feng [Key Laboratory of Modern Acoustics, Institute of Acoustics and School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); School of Physics & Electronic Engineering, Changshu Institute of Technology, Changshu 215500 (China); Quan, Li; Liu, Xiaozhou, E-mail: xzliu@nju.edu.cn; Gong, Xiufen [Key Laboratory of Modern Acoustics, Institute of Acoustics and School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China)

    2015-10-28

    Previous research with temperature gradients has shown the feasibility of controlling airborne sound propagation. Here, we present a temperature gradients based airborne sound manipulation schemes: a cylindrical acoustic omnidirectional absorber (AOA). The proposed AOA has high absorption performance which can almost completely absorb the incident wave. Geometric acoustics is used to obtain the refractive index distributions with different radii, which is then utilized to deduce the desired temperature gradients. Since resonant units are not applied in the scheme, its working bandwidth is expected to be broadband. The scheme is temperature-tuned and easy to realize, which is of potential interest to fields such as noise control or acoustic cloaking.

  19. Speciation gradients and the distribution of biodiversity.

    Science.gov (United States)

    Schluter, Dolph; Pennell, Matthew W

    2017-05-31

    Global patterns of biodiversity are influenced by spatial and environmental variations in the rate at which new species form. We relate variations in speciation rates to six key patterns of biodiversity worldwide, including the species-area relationship, latitudinal gradients in species and genetic diversity, and between-habitat differences in species richness. Although they sometimes mirror biodiversity patterns, recent rates of speciation, at the tip of the tree of life, are often highest where species richness is low. Speciation gradients therefore shape, but are also shaped by, biodiversity gradients and are often more useful for predicting future patterns of biodiversity than for interpreting the past.

  20. Gradients of cortical hierarchy in Autism

    Directory of Open Access Journals (Sweden)

    Richard Bethlehem

    2017-05-01

    Full Text Available Autism is a developmental condition associated with altered functional connectivity. We propose to re-frame the functional connectivity alterations in terms of gradients that capture the functional hierarchy of cortical processing from sensory to default-mode network regions. We hypothesized that this hierarchy will be altered in ASD. To test that, we compared the scale of gradients in people with autism and healthy controls. The present results do not support our hypothesis. There are two alternative implications: either the processing hierarchies are preserved in autism or the scale of the gradients does not capture them. In the future we will attempt to settle which alternative is more likely.

  1. Discussion of liquid threshold pressure gradient

    OpenAIRE

    Wang, Xiukun; James J. Sheng

    2017-01-01

    Some authors believe that a minimum pressure gradient (called threshold pressure gradient (TPG)) is required before a liquid starts to flow in a porous medium. In a tight or shale oil formation, this TPG phenomenon becomes more important, as it is more difficult for a fluid to flow. In this paper, experimental data on TPG published in the literature are carefully reviewed. What we found is that a very low flow velocity corresponding to a very low pressure gradient cannot be measured in the ex...

  2. Recuperation of the organic matter from oil shales with phenol in subcritical conditions; Recuperation a l'autoclave de la matiere organique de schistes bitumineux marocains par le phenol en conditions sub-critiques

    Energy Technology Data Exchange (ETDEWEB)

    Abourriche, A.; Oumam, M.; Hannache, H. [Faculte des Sciences Ben M' sik, Lab. des Materiaux Thermostructuraux, Casablanca (Morocco); Pailler, R.; Naslain, R. [Bordeaux-1 Univ., Lab. des Composites Thermostructuraux, UMR 5801 CNRS-CEA-Snecma, 33 - Pessac (France); Birot, M.; Pillot, J.P. [Bordeaux-1 Univ., Lab. de Chimie Organique et Organometallique, UMR 5802 CNRS, 33 - Pessac (France)

    2005-02-01

    Phenol was used for the recovery of the organic matter from Tarfaya's oil shales in subcritical conditions. The analyses carried out on the recovered oils revealed that phenol had a significant role on the increase of the yield of recuperation, amount of maltenes, aromatic compounds and the reduction of the amount of sulphur in oils. (author)

  3. Nuclear power history calculation for subcritical systems using Euler-MacLaurin formula; Calculo do historico de potencia nuclear para sistemas subcriticos utilizando a formula de Euler-MacLaurin

    Energy Technology Data Exchange (ETDEWEB)

    Henrice Junior, Edson; Goncalves, Alessandro da Cruz, E-mail: ejunior@nuclear.ufrj.br, E-mail: alessandro@nuclear.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Departamento de Engenharia Nuclear; Palma, Daniel Arthur Pinheiro, E-mail: dapalma@cnen.gov.br [Comissao Nacional de Energia Nucleara (CNEN), Rio de Janeiro, RJ (Brazil)

    2013-07-01

    This paper presents an efficient method for calculating the reactivity using inverse point kinetic equation for subcritical systems by applying the Euler-MacLaurin summation formula to calculate the nuclear power history. In accordance with the accuracy of the numerical results, this method does not require a large number of points for calculation, providing accurate results with low computational cost. (author)

  4. Subcritical and supercritical water oxidation of organic, wet wastes for carbon cycling in regenerative life support systems

    Science.gov (United States)

    Ronsse, Frederik; Lasseur, Christophe; Rebeyre, Pierre; Clauwaert, Peter; Luther, Amanda; Rabaey, Korneel; Zhang, Dong Dong; López Barreiro, Diego; Prins, Wolter; Brilman, Wim

    2016-07-01

    For long-term human spaceflight missions, one of the major requirements is the regenerative life support system which has to be capable of recycling carbon, nutrients and water from both solid and liquid wastes generated by the crew and by the local production of food through living organisms (higher plants, fungi, algae, bacteria, …). The European Space Agency's Life Support System, envisioned by the MELiSSA project, consists of a 5 compartment artificial ecosystem, in which the waste receiving compartment (so-called compartment I or briefly 'CI') is based on thermophilic fermentation. However, as the waste generated by the crew compartment and food production compartment contain typical plant fibres (lignin, cellulose and hemicellulose), these recalcitrant fibres end up largely unaffected in the digestate (sludge) generated in the C-I compartment. Therefore, the C-I compartment has to be supplemented with a so-called fibre degradation unit (in short, FDU) for further oxidation or degradation of said plant fibres. A potential solution to degrading these plant fibres and other recalcitrant organics is their oxidation, by means of subcritical or supercritical water, into reusable CO2 while retaining the nutrients in an organic-free liquid effluent. By taking advantage of the altered physicochemical properties of water above or near its critical point (647 K, 22.1 MPa) - including increased solubility of non-polar compounds and oxygen, ion product and diffusivity - process conditions can be created for rapid oxidation of C into CO2. In this research, the oxidizer is provided as a hydrogen peroxide solution which, at elevated temperature, will dissociated into O2. The purpose of this study is to identify ideal process conditions which (a) ensure complete oxidation of carbon, (b) retaining the nutrients other than C in the liquid effluent and (c) require as little oxidizer as possible. Experiments were conducted on a continuous, tubular heated reactor and on batch

  5. Integral Field Spectroscopy Surveys: Oxygen Abundance Gradients

    Science.gov (United States)

    Sánchez, S. F.; Sánchez-Menguiano, L.

    2017-07-01

    We present here the recent results on our understanding of oxygen abundance gradients derived using Integral Field Spectroscopic surveys. In particular we analyzed more than 2124 datacubes corresponding to individual objects observed by the CALIFA (˜ 734 objects) and the public data by MaNGA (˜ 1390 objects), deriving the oxygen abundance gradient for each galaxy. We confirm previous results that indicate that the shape of this gradient is very similar for all galaxies with masses above 109.5M⊙, presenting in average a very similar slope of ˜ -0.04 dex within 0.5-2.0 re, with a possible drop in the inner regions (r109.5M⊙) the gradient seems to be flatter than for more massive ones. All these results agree with an inside-out growth of massive galaxies and indicate that low mass ones may still be growing in an outside in phase.

  6. Optimizing sampling approaches along ecological gradients

    DEFF Research Database (Denmark)

    Schweiger, Andreas; Irl, Severin D. H.; Steinbauer, Manuel

    2016-01-01

    1. Natural scientists and especially ecologists use manipulative experiments or field observations along gradients to differentiate patterns driven by processes from those caused by random noise. A well-conceived sampling design is essential for identifying, analysing and reporting underlying...

  7. Program predicts two-phase pressure gradients

    Energy Technology Data Exchange (ETDEWEB)

    Jacks, D.C.; Hill, A.D.

    1983-11-18

    The calculator program discussed, ORK, was designed for the HP-41CV hand-held calculator and uses the Orkiszewski correlation for predicting 2-phase pressure gradients in vertical tubulars. Accurate predictions of pressure gradients in flowing and gas lift wells over a wide range of well conditions can be obtained with this method, which was developed based on data from 148 wells. The correlation is one of the best generalized 2-phase pressure gradient prediction methods developed to date for vertical flow. It is unique in that hold-up is derived from observed physical phenomena, and the pressure gradient is related to the geometrical distribution of the liquid and gas phase (flow regime).

  8. Full Gradient Solution to Adaptive Hybrid Control

    Science.gov (United States)

    Bean, Jacob; Schiller, Noah H.; Fuller, Chris

    2017-01-01

    This paper focuses on the adaptation mechanisms in adaptive hybrid controllers. Most adaptive hybrid controllers update two filters individually according to the filtered reference least mean squares (FxLMS) algorithm. Because this algorithm was derived for feedforward control, it does not take into account the presence of a feedback loop in the gradient calculation. This paper provides a derivation of the proper weight vector gradient for hybrid (or feedback) controllers that takes into account the presence of feedback. In this formulation, a single weight vector is updated rather than two individually. An internal model structure is assumed for the feedback part of the controller. The full gradient is equivalent to that used in the standard FxLMS algorithm with the addition of a recursive term that is a function of the modeling error. Some simulations are provided to highlight the advantages of using the full gradient in the weight vector update rather than the approximation.

  9. Vegetation patterns and environmental gradients in Benin

    NARCIS (Netherlands)

    Adomou, A.

    2005-01-01

    Key words: West Africa, Benin, vegetation patterns, floristic areas, phytogeography, chorology, floristic gradients, climatic factors, water availability, Dahomey Gap, threatened plants, biodiversity, conservation.Understanding plant species distribution patterns and the underlying factors is a

  10. Ultimate gradient in solid-state accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Whittum, D.H.

    1998-08-01

    The authors recall the motivation for research in high-gradient acceleration and the problems posed by a compact collider. They summarize the phenomena known to appear in operation of a solid-state structure with large fields, and research relevant to the question of the ultimate gradient. They take note of new concepts, and examine one in detail, a miniature particle accelerator based on an active millimeter-wave circuit and parallel particle beams.

  11. On fracture in finite strain gradient plasticity

    DEFF Research Database (Denmark)

    Martínez Pañeda, Emilio; Niordson, Christian Frithiof

    2016-01-01

    In this work a general framework for damage and fracture assessment including the effect of strain gradients is provided. Both mechanism-based and phenomenological strain gradient plasticity (SGP) theories are implemented numerically using finite deformation theory and crack tip fields are invest...... in the multiple parameter version of the phenomenological SGP theory. Since this also dominates the mechanics of indentation testing, results suggest that length parameters characteristic of mode I fracture should be inferred from nanoindentation....

  12. Microinstabilities in weak density gradient tokamak systems

    Energy Technology Data Exchange (ETDEWEB)

    Tang, W.M.; Rewoldt, G.; Chen, L.

    1986-04-01

    A prominent characteristic of auxiliary-heated tokamak discharges which exhibit improved (''H-mode type'') confinement properties is that their density profiles tend to be much flatter over most of the plasma radius. Depsite this favorable trend, it is emphasized here that, even in the limit of zero density gradient, low-frequency microinstabilities can persist due to the nonzero temperature gradient.

  13. Minimizing hallucination in Histogram of Oriented Gradients

    OpenAIRE

    Ortiz, Javier; Bak, Slawomir; Koperski, Michał; Brémond, François

    2015-01-01

    International audience; Histogram of Oriented Gradients is one of the most extensively used image descriptors in computer vision. It has successfully been applied to various vision tasks such as localization, classification and recognition. As it mainly captures gradient strengths in an image, it is sensitive to local variations in illumination and contrast. In the result, a normalization of this descriptor turns out to be essential for good performance [3, 4]. Although different normal-izati...

  14. Thermal gradient analysis of solidifying casting

    Directory of Open Access Journals (Sweden)

    J. Suchoń

    2008-08-01

    Full Text Available For description of casting solidification and crystallization process the thermal derivative analysis (TDA is commonly used. Besides the process kinetics considered in TDA method to describe the solidification process, the thermal gradient analysis can be also used for this purpose [1, 2]. In conducted studies analysis of thermal gradient distribution inside the solidifying wedge casting was shown which enabled determination of heat flow intensity on casting section.

  15. Estimation of gradients in quantum metrology

    Science.gov (United States)

    Altenburg, Sanah; Oszmaniec, Michał; Wölk, Sabine; Gühne, Otfried

    2017-10-01

    We develop a general theory to estimate magnetic field gradients in quantum metrology. We consider a system of N particles distributed on a line whose internal degrees of freedom interact with a magnetic field. Usually gradient estimation is based on precise measurements of the magnetic field at two different locations, performed with two independent groups of particles. This approach, however, is sensitive to fluctuations of the offset field determining the level splitting of the particles and results in collective dephasing. In this work, we use the framework of quantum metrology to assess the maximal accuracy for gradient estimation. For arbitrary positioning of particles, we identify optimal entangled and separable states, allowing the estimation of gradients with maximal accuracy, quantified by the quantum Fisher information. We also analyze the performance of states from the decoherence-free subspace (DFS), which are insensitive to the fluctuations of the magnetic offset field. We find that these states allow us to measure a gradient directly, without the necessity of estimating the magnetic offset field. Moreover, we show that DFS states attain a precision for gradient estimation comparable to the optimal entangled states. Finally, for the above classes of states, we find simple and feasible measurements saturating the quantum Cramér-Rao bound.

  16. 3D Gradient coil design - Toroidal surfaces

    Science.gov (United States)

    While, Peter T.; Forbes, Larry K.; Crozier, Stuart

    2009-05-01

    Gradient coil design typically involves optimisation of current densities or coil windings on familiar cylindrical, planar, spherical or conical surfaces. In this paper, an analytic inverse method is presented for the theoretical design of toroidal transverse gradient coils. This novel geometry is based on previous work involving a 3D current density solution, in which the precise geometry of the gradient coils was obtained as part of the optimisation process. Regularisation is used to solve for the toroidal current densities, whereby the field error is minimised in conjunction with the total power of the coil. The method is applied to the design of unshielded and shielded, whole-body and head coil gradient systems. Preliminary coil windings displaying high gradient homogeneity, low inductance, high efficiency and good force balancing are displayed and discussed. Potential benefits associated with this morphology include self-shielding gradient sets, greater access to cooling mechanisms, a reduction in acoustic noise due to force-balancing, a lessening of patient claustrophobia and greater patient access for clinicians.

  17. The mechanical design and fabrication of 162.5 MHz buncher for China accelerator driven sub-critical system injector II

    Energy Technology Data Exchange (ETDEWEB)

    Niu, Hai Hua; Li, Youtang [Lanzhou University of Technology, Lanzhou (China); He, Yuan; Zhang, Bin; Huang, Shichun; Yuan, Chenzhang; Jia, Huan; Zhang, Shenghu [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou (China)

    2017-08-15

    A buncher is one of the main pieces of equipment in the medium energy beam transport line (MEBT) for China accelerator driven sub-critical system (C-ADS) Injector II. To focus the beam longitudinally and match the beam for the acceptance of the superconducting linac section, two room temperature quarter wave resonator (QWR) bunchers with frequency of 162.5 MHz have been designed as parts of the MEBT. According to the beam transmission matching of the MEBT and the geometric parameters requirements of bunchers, the unique mechanical structure and the main processing technology of buncher cavities and their couplers and tuners are described in this paper. The fabrication of bunchers and their parts have been completed and tested at high power, the test results agree well with the design requirements. These bunchers work well for about two years in Institute of Modern Physics, Chinese Academy of Sciences.

  18. The mechanical design and fabrication of 162.5 MHz buncher for China accelerator driven sub-critical system injector II

    Directory of Open Access Journals (Sweden)

    Haihua Niu

    2017-08-01

    Full Text Available A buncher is one of the main pieces of equipment in the medium energy beam transport line (MEBT for China accelerator driven sub-critical system (C-ADS Injector II. To focus the beam longitudinally and match the beam for the acceptance of the superconducting linac section, two room temperature quarter wave resonator (QWR bunchers with frequency of 162.5 MHz have been designed as parts of the MEBT. According to the beam transmission matching of the MEBT and the geometric parameters requirements of bunchers, the unique mechanical structure and the main processing technology of buncher cavities and their couplers and tuners are described in this paper. The fabrication of bunchers and their parts have been completed and tested at high power, the test results agree well with the design requirements. These bunchers work well for about two years in Institute of Modern Physics, Chinese Academy of Sciences.

  19. STUDY OF THE PREPARATION OF SUGAR FROM HIGH-LIGNIN LIGNOCELLULOSE APPLYING SUBCRITICAL WATER AND ENZYMATIC HYDROLYSIS: SYNTHESIS AND CONSUMABLE COST EVALUATION

    Directory of Open Access Journals (Sweden)

    HANNY F. SANGIAN

    2015-05-01

    Full Text Available This study concern sugars hydrolyzed from the high-lignin coconut coir dust using moderate subcritical water (SCW hydrolysis at pressures 20-40 bar for 1 h and to evaluate the consumable costs driver generated. The SCW method produced two products, sugar liquid and solid (SCW-treated substrate. The solid was proceeded to prepare the sugar via enzymatic hydrolysis using pure cellulase. Yield of sugar hydrolyzed from lignocellulose by SCW technique was 0.25 gram sugar/gram cellulose +hemicellulose, or 0.09-gram sugar/gram lignocellulose at 160 °C and 40 bar. While, the maximum yield of sugar liberated enzymatically from SCW-treated solid was 0.35-gram sugar/gram cellulose+hemicellulose, or 0.13-gram sugar/gram SCW-treated solid. It was found that carbon dioxide gas was the highest cost driving in SCW hydrolysis.

  20. Evidence of counter-gradient growth in western pond turtles (Actinemys marmorata) across thermal gradients

    Science.gov (United States)

    Snover, Melissa; Adams, Michael J.; Ashton, Donald T.; Bettaso, Jamie B.; Welsh, Hartwell H.

    2015-01-01

    Counter-gradient growth, where growth per unit temperature increases as temperature decreases, can reduce the variation in ectothermic growth rates across environmental gradients. Understanding how ectothermic species respond to changing temperatures is essential to their conservation and management due to human-altered habitats and changing climates.

  1. Momentum-weighted conjugate gradient descent algorithm for gradient coil optimization.

    Science.gov (United States)

    Lu, Hanbing; Jesmanowicz, Andrzej; Li, Shi-Jiang; Hyde, James S

    2004-01-01

    MRI gradient coil design is a type of nonlinear constrained optimization. A practical problem in transverse gradient coil design using the conjugate gradient descent (CGD) method is that wire elements move at different rates along orthogonal directions (r, phi, z), and tend to cross, breaking the constraints. A momentum-weighted conjugate gradient descent (MW-CGD) method is presented to overcome this problem. This method takes advantage of the efficiency of the CGD method combined with momentum weighting, which is also an intrinsic property of the Levenberg-Marquardt algorithm, to adjust step sizes along the three orthogonal directions. A water-cooled, 12.8 cm inner diameter, three axis torque-balanced gradient coil for rat imaging was developed based on this method, with an efficiency of 2.13, 2.08, and 4.12 mT.m(-1).A(-1) along X, Y, and Z, respectively. Experimental data demonstrate that this method can improve efficiency by 40% and field uniformity by 27%. This method has also been applied to the design of a gradient coil for the human brain, employing remote current return paths. The benefits of this design include improved gradient field uniformity and efficiency, with a shorter length than gradient coil designs using coaxial return paths. Copyright 2003 Wiley-Liss, Inc.

  2. Nonlinear conjugate gradient methods in micromagnetics

    Science.gov (United States)

    Fischbacher, J.; Kovacs, Alexander; Oezelt, Harald; Schrefl, T.; Exl, L.; Fidler, J.; Suess, D.; Sakuma, N.; Yano, M.; Kato, A.; Shoji, T.; Manabe, A.

    2017-04-01

    Conjugate gradient methods for energy minimization in micromagnetics are compared. The comparison of analytic results with numerical simulation shows that standard conjugate gradient method may fail to produce correct results. A method that restricts the step length in the line search is introduced, in order to avoid this problem. When the step length in the line search is controlled, conjugate gradient techniques are a fast and reliable way to compute the hysteresis properties of permanent magnets. The method is applied to investigate demagnetizing effects in NdFe12 based permanent magnets. The reduction of the coercive field by demagnetizing effects is μ0ΔH = 1.4 T at 450 K.

  3. Gradient Solvent Vapor Annealing of Thin Films

    Science.gov (United States)

    Albert, Julie; Bogart, Timothy; Lewis, Ronald; Epps, Thomas

    2011-03-01

    The development of block copolymer materials for emerging nanotechnologies requires an understanding of how surface energy/chemistry and annealing conditions affect thin film self-assembly. Specifically, in solvent vapor annealing (SVA), the use of solvent mixtures and the manipulation of solvent vapor concentration are promising approaches for obtaining a desired morphology or nanostructure orientation. We designed and fabricated solvent-resistant devices to produce discrete SVA gradients in composition and/or concentration to efficiently explore SVA parameter space. We annealed copolymer films containing poly(styrene), poly(isoprene), and/or poly(methyl methacrylate) blocks, monitored film thicknesses during annealing, and characterized film morphologies with atomic force microscopy. Morphological changes across the gradients such as the transformation from parallel cylinders to spheres with increasing solvent selectivity provided insight into thin film self-assembly, and the gradient device has enabled us to determine transition compositions and/or concentrations.

  4. Conjugate gradient algorithms using multiple recursions

    Energy Technology Data Exchange (ETDEWEB)

    Barth, T.; Manteuffel, T.

    1996-12-31

    Much is already known about when a conjugate gradient method can be implemented with short recursions for the direction vectors. The work done in 1984 by Faber and Manteuffel gave necessary and sufficient conditions on the iteration matrix A, in order for a conjugate gradient method to be implemented with a single recursion of a certain form. However, this form does not take into account all possible recursions. This became evident when Jagels and Reichel used an algorithm of Gragg for unitary matrices to demonstrate that the class of matrices for which a practical conjugate gradient algorithm exists can be extended to include unitary and shifted unitary matrices. The implementation uses short double recursions for the direction vectors. This motivates the study of multiple recursion algorithms.

  5. Dynamics of gradient formation by intracellular shuttling

    Energy Technology Data Exchange (ETDEWEB)

    Berezhkovskii, Alexander M. [Mathematical and Statistical Computing Laboratory, Division of Computational Bioscience, Center for Information Technology, National Institutes of Health, Bethesda, Maryland 20892 (United States); Shvartsman, Stanislav Y. [Department of Chemical and Biological Engineering and Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544 (United States)

    2015-08-21

    A number of important cellular functions rely on the formation of intracellular protein concentration gradients. Experimental studies discovered a number of mechanisms for the formation of such gradients. One of the mechanisms relies on the intracellular shuttling of a protein that interconverts between the two states with different diffusivities, under the action of two enzymes, one of which is localized to the plasma membrane, whereas the second is uniformly distributed in the cytoplasm. Recent work reported an analytical solution for the steady state gradient in this mechanism, obtained in the framework of a one-dimensional reaction-diffusion model. Here, we study the dynamics in this model and derive analytical expressions for the Laplace transforms of the time-dependent concentration profiles in terms of elementary transcendental functions. Inverting these transforms numerically, one can obtain time-dependent concentration profiles of the two forms of the protein.

  6. Collective chemotaxis through noisy multicellular gradient sensing

    CERN Document Server

    Varennes, Julien; Mugler, Andrew

    2016-01-01

    Collective cell migration in response to a chemical cue occurs in many biological processes such as morphogenesis and cancer metastasis. Clusters of migratory cells in these systems are capable of responding to gradients of less than 1% difference in chemical concentration across a cell length. Multicellular systems are extremely sensitive to their environment and while the limits to multicellular sensing are becoming known, how this information leads to coherent migration remains poorly understood. We develop a computational model of multicellular sensing and migration in which groups of cells collectively measure noisy chemical gradients. The output of the sensing process is coupled to individual cells polarization to model migratory behavior. Through the use of numerical simulations, we find that larger clusters of cells detect the gradient direction with higher precision and thus achieve stronger polarization bias, but larger clusters also induce more drag on collective motion. The trade-off between these...

  7. Gradients in Planarian Regeneration and Homeostasis

    Science.gov (United States)

    Adell, Teresa; Cebrià, Francesc; Saló, Emili

    2010-01-01

    Planarian regeneration was one of the first models in which the gradient concept was developed. Morphological studies based on the analysis of the regeneration rates of planarian fragments from different body regions, the generation of heteromorphoses, and experiments of tissue transplantation led T.H. Morgan (1901) and C.M Child (1911) to postulate different kinds of gradients responsible for the regenerative process in these highly plastic animals. However, after a century of research, the role of morphogens in planarian regeneration has yet to be demonstrated. This may change soon, as the sequencing of the planarian genome and the possibility of performing gene functional analysis by RNA interference (RNAi) have led to the isolation of elements of the bone morphogenetic protein (BMP), Wnt, and fibroblast growth factor (FGF) pathways that control patterning and axial polarity during planarian regeneration and homeostasis. Here, we discuss whether the actions of these molecules could be based on morphogenetic gradients. PMID:20182600

  8. Inversion gradients for acoustic VTI wavefield tomography

    KAUST Repository

    Li, Vladimir

    2017-03-21

    Wavefield tomography can handle complex subsurface geology better than ray-based techniques and, ultimately, provide a higher resolution. Here, we implement forward and adjoint wavefield extrapolation for VTI (transversely isotropic with a vertical symmetry axis) media using a generalized pseudospectral operator based on a separable approximation for the P-wave dispersion relation. This operator is employed to derive the gradients of the differential semblance optimization (DSO) and modified image-power objective functions. We also obtain the gradient expressions for a data-domain objective function that can more easily incorporate borehole information necessary for stable VTI velocity analysis. These gradients are similar to the ones obtained with a space-time finite-difference (FD) scheme for a system of coupled wave equations but the pseudospectral method is not hampered by the imprint of the shear-wave artifact. Numerical examples also show the potential advantages of the modified image-power objective function in estimating the anellipticity parameter η.

  9. On lower order strain gradient plasticity theories

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Hutchinson, J. W.

    2002-01-01

    By way of numerical examples, this paper explores the nature of solutions to a class of strain gradient plasticity theories that employ conventional stresses, equilibrium equations and boundary conditions. Strain gradients come into play in these modified conventional theories only to alter the t...... the tangential moduli governing increments of stress and strain. It is shown that the modification is far from benign from a mathematical standpoint, changing the qualitative character of solutions and leading to a new type of localization that appears to be unphysical....

  10. Spectral Projected Gradient Methods: Review and Perspectives

    Directory of Open Access Journals (Sweden)

    Ernesto G. Birgin

    2014-09-01

    Full Text Available Over the last two decades, it has been observed that using the gradient vector as a search direction in large-scale optimization may lead to efficient algorithms. The effectiveness relies on choosing the step lengths according to novel ideas that are related to the spectrum of the underlying local Hessian rather than related to the standard decrease in the objective function. A review of these so-called spectral projected gradient methods for convex constrained optimization is presented. To illustrate the performance of these low-cost schemes, an optimization problem on the set of positive definite matrices is described.

  11. Improving dimensionality reduction with spectral gradient descent.

    Science.gov (United States)

    Memisevic, Roland; Hinton, Geoffrey

    2005-01-01

    We introduce spectral gradient descent, a way of improving iterative dimensionality reduction techniques. The method uses information contained in the leading eigenvalues of a data affinity matrix to modify the steps taken during a gradient-based optimization procedure. We show that the approach is able to speed up the optimization and to help dimensionality reduction methods find better local minima of their objective functions. We also provide an interpretation of our approach in terms of the power method for finding the leading eigenvalues of a symmetric matrix and verify the usefulness of the approach in some simple experiments.

  12. Gradient Elasticity Formulations for Micro/Nanoshells

    Directory of Open Access Journals (Sweden)

    Bohua Sun

    2014-01-01

    Full Text Available The focus of this paper is on illustrating how to extend the second author’s gradient theory of elasticity to shells. Three formulations are presented based on the implicit gradient elasticity constitutive relation 1 -ld2∇2σij=Cijkl(1-ls2∇2εkl and its two approximations 1+ls2∇2-ld2∇2σij=Cijklεkl and σij=Cijkl(1+ld2∇2-ls2∇2εkl.

  13. Richardson extrapolation practical aspects and applications

    CERN Document Server

    Zlatev, Zahari; Faragó, István; Havasi, Ágnes

    2017-01-01

    The series is devoted to the publication of high-level monographs and specialized graduate texts which cover the whole spectrum of applied mathematics, including its numerical aspects. The focus of the series is on the interplay between mathematical and numerical analysis, and also on its applications to mathematical models in the physical and life sciences.

  14. Up-gradient transport in a probabilistic transport model

    DEFF Research Database (Denmark)

    Gavnholt, J.; Juul Rasmussen, J.; Garcia, O.E.

    2005-01-01

    The transport of particles or heat against the driving gradient is studied by employing a probabilistic transport model with a characteristic particle step length that depends on the local concentration or heat gradient. When this gradient is larger than a prescribed critical value, the standard....... These results supplement recent works by van Milligen [Phys. Plasmas 11, 3787 (2004)], which applied Levy distributed step sizes in the case of supercritical gradients to obtain the up-gradient transport. (c) 2005 American Institute of Physics....

  15. Large Airborne Full Tensor Gradient Data Inversion Based on a Non-Monotone Gradient Method

    Science.gov (United States)

    Sun, Yong; Meng, Zhaohai; Li, Fengting

    2017-11-01

    Following the development of gravity gradiometer instrument technology, the full tensor gravity (FTG) data can be acquired on airborne and marine platforms. Large-scale geophysical data can be obtained using these methods, making such data sets a number of the "big data" category. Therefore, a fast and effective inversion method is developed to solve the large-scale FTG data inversion problem. Many algorithms are available to accelerate the FTG data inversion, such as conjugate gradient method. However, the conventional conjugate gradient method takes a long time to complete data processing. Thus, a fast and effective iterative algorithm is necessary to improve the utilization of FTG data. Generally, inversion processing is formulated by incorporating regularizing constraints, followed by the introduction of a non-monotone gradient-descent method to accelerate the convergence rate of FTG data inversion. Compared with the conventional gradient method, the steepest descent gradient algorithm, and the conjugate gradient algorithm, there are clear advantages of the non-monotone iterative gradient-descent algorithm. Simulated and field FTG data were applied to show the application value of this new fast inversion method.

  16. Weakening of lower tropospheric temperature gradient between ...

    Indian Academy of Sciences (India)

    e-mail: bawiskar@hotmail.com bawiskar@tropmet.res.in. The study shows that in the scenario of global warming temperature gradient (TG) between Indian landmass and Arabian Sea/Bay of Bengal is significantly decreasing in the lower troposphere with maxima around 850hPa. TG during pre-monsoon (March to May) is ...

  17. Conjugate Gradient Algorithms For Manipulator Simulation

    Science.gov (United States)

    Fijany, Amir; Scheid, Robert E.

    1991-01-01

    Report discusses applicability of conjugate-gradient algorithms to computation of forward dynamics of robotic manipulators. Rapid computation of forward dynamics essential to teleoperation and other advanced robotic applications. Part of continuing effort to find algorithms meeting requirements for increased computational efficiency and speed. Method used for iterative solution of systems of linear equations.

  18. Hydrodynamic Gradient Expansion in Gauge Theory Plasmas,

    NARCIS (Netherlands)

    Heller, M.P.; Janik, R.A.; Witaszczyk, P

    2013-01-01

    We utilize the fluid-gravity duality to investigate the large order behavior of hydrodynamic gradient expansion of the dynamics of a gauge theory plasma system. This corresponds to the inclusion of dissipative terms and transport coefficients of very high order. Using the dual gravity description,

  19. Gradient lasso for Cox proportional hazards model.

    Science.gov (United States)

    Sohn, Insuk; Kim, Jinseog; Jung, Sin-Ho; Park, Changyi

    2009-07-15

    There has been an increasing interest in expressing a survival phenotype (e.g. time to cancer recurrence or death) or its distribution in terms of a subset of the expression data of a subset of genes. Due to high dimensionality of gene expression data, however, there is a serious problem of collinearity in fitting a prediction model, e.g. Cox's proportional hazards model. To avoid the collinearity problem, several methods based on penalized Cox proportional hazards models have been proposed. However, those methods suffer from severe computational problems, such as slow or even failed convergence, because of high-dimensional matrix inversions required for model fitting. We propose to implement the penalized Cox regression with a lasso penalty via the gradient lasso algorithm that yields faster convergence to the global optimum than do other algorithms. Moreover the gradient lasso algorithm is guaranteed to converge to the optimum under mild regularity conditions. Hence, our gradient lasso algorithm can be a useful tool in developing a prediction model based on high-dimensional covariates including gene expression data. Results from simulation studies showed that the prediction model by gradient lasso recovers the prognostic genes. Also results from diffuse large B-cell lymphoma datasets and Norway/Stanford breast cancer dataset indicate that our method is very competitive compared with popular existing methods by Park and Hastie and Goeman in its computational time, prediction and selectivity. R package glcoxph is available at http://datamining.dongguk.ac.kr/R/glcoxph.

  20. Instabilities in power law gradient hardening materials

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Tvergaard, Viggo

    2005-01-01

    Tension and compression instabilities are investigated for specimens with dimensions in the micron range. A finite strain generalization of a higher order strain gradient plasticity theory is implemented in a finite element scheme capable of modeling power law hardening materials. Effects...

  1. Mass balance gradients and climatic change

    NARCIS (Netherlands)

    Oerlemans, J.; Hoogendoorn, N.C.

    1989-01-01

    It is generally assumed that the mass-balance gradient on glaciers is more or less conserved under climatic change. In studies of the dynamic response of glaciers to climatic change, one of the following assumptions is normally made: (i) the mass-balance perturbation is independent of altitude

  2. Lactate uptake against a concentration gradient

    DEFF Research Database (Denmark)

    Nordström, Carl-Henrik; Nielsen, Troels Halfeld; Nielsen, Hans Boye

    2014-01-01

    The recently published article by Jalloh et al (Jalloh I, Helmy A, Shannon RJ, Gallagher CN, Menon D, Carpenter K, Hutchinson P. Lactate uptake by the injured human brain - evidence from an arterio-venous gradient and cerebral microdialysis study. J Neurotrauma. 2013 Aug 22. [Epub ahead of print...

  3. Density Gradient Columns for Chemical Displays.

    Science.gov (United States)

    Guenther, William B.

    1986-01-01

    Procedures for preparing density gradient columns for chemical displays are presented. They include displays illustrating acid-base reactions, metal ion equilibria, and liquid density. The lifetime of these metastable displays is surprising, some lasting for months in display cabinets. (JN)

  4. GOCE gravitational gradients along the orbit

    NARCIS (Netherlands)

    Bouman, J.; Fiorot, S.; Fuchs, M.; Gruber, T.; Schrama, E.J.O.; Tscherning, C.; Veicherts, M.; Visser, P.N.A.M.

    2011-01-01

    GOCE is ESA’s gravity field mission and the first satellite ever that measures gravitational gradients in space, that is, the second spatial derivatives of the Earth’s gravitational potential. The goal is to determine the Earth’s mean gravitational field with unprecedented accuracy at spatial

  5. Proton gradients at the origin of life.

    Science.gov (United States)

    Lane, Nick

    2017-06-01

    Chemiosmotic coupling - the harnessing of electrochemical ion gradients across membranes to drive metabolism - is as universally conserved as the genetic code. As argued previously in these pages, such deep conservation suggests that ion gradients arose early in evolution, and might have played a role in the origin of life. Alkaline hydrothermal vents harbour pH gradients of similar polarity and magnitude to those employed by modern cells, one of many properties that make them attractive models for life's origin. Their congruence with the physiology of anaerobic autotrophs that use the acetyl CoA pathway to fix CO2 gives the alkaline vent model broad appeal to biologists. Recently, however, a paper by Baz Jackson criticized the hypothesis, concluding that natural pH gradients were unlikely to have played any role in the origin of life. Unfortunately, Jackson mainly criticized his own interpretations of the theory, not what the literature says. This counterpoint is intended to set the record straight. © 2017 WILEY Periodicals, Inc.

  6. GOCE gravity gradient data for lithospheric modeling

    NARCIS (Netherlands)

    Bouman, J.; Ebbing, J.; Meekes, S.; Fattah, R.A.; Fuchs, M.; Gradmann, S.; Haagmans, R.; Lieb, V.; Schmidt, M.; Dettmering, D.; Bosch, W.

    2015-01-01

    The Gravity field and steady-state Ocean Circulation Explorer (GOCE) is the European Space Agency's (ESA)satellite gravity mission to determine the Earth's mean gravity field. GOCE delivers gravity gradients, anew type of satellite data. We study how these data can improve modeling of the Earth's

  7. Gradient computation for VTI acoustic wavefield tomography

    KAUST Repository

    Li, Vladimir

    2016-09-06

    Wavefield tomography can handle complex subsurface geology better than ray-based techniques and, ultimately, provide a higher resolution. Here, we implement forward and adjoint wavefield extrapolation for VTI (transversely isotropic with a vertical symmetry axis) media using a pseudospectral operator that employes a separable approximation of the P-wave dispersion relation. This operator is employed to derive the gradients of the differential semblance optimization (DSO) and modified stack-power objective functions. We also obtain the gradient expressions for the data-domain objective function, which can incorporate borehole information necessary for stable VTI velocity analysis. These gradients are compared to the ones obtained with a space-time finite-difference (FD) scheme for a system of coupled wave equations. Whereas the kernels computed with the two wave-equation operators are similar, the pseudospectral method is not hampered by the imprint of the shear-wave artifact. Numerical examples also show that the modified stack-power objective function produces cleaner gradients than the more conventional DSO operator.

  8. Annular beam with segmented phase gradients

    Directory of Open Access Journals (Sweden)

    Shubo Cheng

    2016-08-01

    Full Text Available An annular beam with a single uniform-intensity ring and multiple segments of phase gradients is proposed in this paper. Different from the conventional superposed vortices, such as the modulated optical vortices and the collinear superposition of multiple orbital angular momentum modes, the designed annular beam has a doughnut intensity distribution whose radius is independent of the phase distribution of the beam in the imaging plane. The phase distribution along the circumference of the doughnut beam can be segmented with different phase gradients. Similar to a vortex beam, the annular beam can also exert torques and rotate a trapped particle owing to the orbital angular momentum of the beam. As the beam possesses different phase gradients, the rotation velocity of the trapped particle can be varied along the circumference. The simulation and experimental results show that an annular beam with three segments of different phase gradients can rotate particles with controlled velocities. The beam has potential applications in optical trapping and optical information processing.

  9. Annular beam with segmented phase gradients

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Shubo; Wu, Liang [School of Physics and Electronics, Central South University, Changsha, Hunan 410083 (China); Tao, Shaohua, E-mail: eshtao@csu.edu.cn [School of Physics and Electronics, Central South University, Changsha, Hunan 410083 (China); Hunan Key Laboratory for Super-microstructure and Ultrafast Process, School of Physics and Electronics, Central South University, Changsha, Hunan 410083 (China)

    2016-08-15

    An annular beam with a single uniform-intensity ring and multiple segments of phase gradients is proposed in this paper. Different from the conventional superposed vortices, such as the modulated optical vortices and the collinear superposition of multiple orbital angular momentum modes, the designed annular beam has a doughnut intensity distribution whose radius is independent of the phase distribution of the beam in the imaging plane. The phase distribution along the circumference of the doughnut beam can be segmented with different phase gradients. Similar to a vortex beam, the annular beam can also exert torques and rotate a trapped particle owing to the orbital angular momentum of the beam. As the beam possesses different phase gradients, the rotation velocity of the trapped particle can be varied along the circumference. The simulation and experimental results show that an annular beam with three segments of different phase gradients can rotate particles with controlled velocities. The beam has potential applications in optical trapping and optical information processing.

  10. Extracellular Processing of Molecular Gradients by Eukaryotic Cells Can Improve Gradient Detection Accuracy

    Science.gov (United States)

    Segota, Igor; Franck, Carl

    2017-12-01

    Eukaryotic cells sense molecular gradients by measuring spatial concentration variation through the difference in the number of occupied receptors to which molecules can bind. They also secrete enzymes that degrade these molecules, and it is presently not well understood how this affects the local gradient perceived by cells. Numerical and analytical results show that these enzymes can substantially increase the signal-to-noise ratio of the receptor difference and allow cells to respond to a much broader range of molecular concentrations and gradients than they would without these enzymes.

  11. GPS, GNSS, and Ionospheric Density Gradients

    Science.gov (United States)

    Kintner, P. M.; O'Hanlon, B.; Humphreys, T. E.

    2009-12-01

    Ionospheric density and density gradients affect GNSS signals in two ways. They can introduce ranging errors or irregularities that form on the density gradients producing scintillation. Here we focus on the issue of ranging errors. There are two approaches to mitigating ranging errors produced by ionospheric density gradients which can be 20-30 m during major magnetic storms. The first approach is to use a reference receiver(s) to determine the ionospheric contribution to ranging errors. The ranging error is then transmitted to the user for correction within the mobile receiver. This approach is frequently referred to as differential GPS and, when multiple reference receivers are used, the system is referred to as an augmentation system. This approach is vulnerable to ionospheric gradients depending on the reference receiver spacing(s) and latency in applying the correction within the mobile receiver. The second approach is to transmit navigation signals at two frequencies and then use the relative delay between the two signals to both estimate the ranging error and calculate the correct range. Currently the dual frequency technique is used by US military receivers with an encryption key and some civilian receivers which must be stationary and average over times long compared to those required for navigation. However, the technology of space based radio navigation is changing. GPS will soon be a system with three frequencies and multiple codes. Furthermore Europe, Russia, and China are developing independent systems to complement and compete with GPS while India and Japan are developing local systems to enhance GPS performance in their regions. In this talk we address two questions. How do density gradients affect augmentation systems including the social consequences and will the new GPS/GNSS systems with multiple civilian frequencies be able to remove ionospheric errors. The answers are not at all clear.

  12. Design and construction of an automatic measurement electronic system and graphical neutron flux for the subcritical reactor; Diseno y construccion de un sistema electronico automatico de medicion y graficado del flujo neutronico para el reactor subcritico

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez M, J.L.; Balderas, E.G.; Rivero G, T. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    1997-07-01

    The National Institute of Nuclear Research (ININ) has in its installations with a nuclear subcritical reactor which was designed and constructed with the main purpose to be used in the nuclear sciences education in the Physics areas and Reactors engineering. Within the nuclear experiments that can be realized in this reactor are very interesting those about determinations of neutron and gamma fluxes spectra, since starting from these some interesting nuclear parameters can be obtained. In order to carry out this type of experiments different radioactive sources are used which exceed the permissible doses by far to human beings. Therefore it is necessary the remote handling as of the source as of detectors used in different experiments. In this work it is presented the design of an electronic system which allows the different positions inside of the tank of subcritical reactor at ININ over the radial and axial axes in manual or automatic ways. (Author)

  13. Computational investigation of 99Mo, 89Sr, and 131I production rates in a subcritical UO2(NO32 aqueous solution reactor driven by a 30-MeV proton accelerator

    Directory of Open Access Journals (Sweden)

    Z. Gholamzadeh

    2015-12-01

    Full Text Available The use of subcritical aqueous homogenous reactors driven by accelerators presents an attractive alternative for producing 99Mo. In this method, the medical isotope production system itself is used to extract 99Mo or other radioisotopes so that there is no need to irradiate common targets. In addition, it can operate at much lower power compared to a traditional reactor to produce the same amount of 99Mo by irradiating targets. In this study, the neutronic performance and 99Mo, 89Sr, and 131I production capacity of a subcritical aqueous homogenous reactor fueled with low-enriched uranyl nitrate was evaluated using the MCNPX code. A proton accelerator with a maximum 30-MeV accelerating power was used to run the subcritical core. The computational results indicate a good potential for the modeled system to produce the radioisotopes under completely safe conditions because of the high negative reactivity coefficients of the modeled core. The results show that application of an optimized beam window material can increase the fission power of the aqueous nitrate fuel up to 80%. This accelerator-based procedure using low enriched uranium nitrate fuel to produce radioisotopes presents a potentially competitive alternative in comparison with the reactor-based or other accelerator-based methods. This system produces ∼1,500 Ci/wk (∼325 6-day Ci of 99Mo at the end of a cycle.

  14. Optimisation of gradient elution with serially-coupled columns. Part I: single linear gradients.

    Science.gov (United States)

    Ortiz-Bolsico, C; Torres-Lapasió, J R; García-Alvarez-Coque, M C

    2014-07-11

    A mixture of compounds often cannot be resolved with a single chromatographic column, but the analysis can be successful using columns of different nature, serially combined through zero-dead volume junctions. In previous work (JCA 1281 (2013) 94), we developed an isocratic approach that optimised simultaneously the mobile phase composition, stationary phase nature and column length. In this work, we take the challenge of implementing optimal linear gradients for serial columns to decrease the analysis time for compounds covering a wide polarity range. For this purpose, five ACE columns of different selectivity (three C18 columns of different characteristics, a cyano and a phenyl column) were combined, aimed to resolve a mixture of 15 sulphonamides using acetonitrile-water gradients. A gradient predictive system, based on numerical integration, was built to simulate chromatograms under linear gradient profiles. Two approaches were compared: the optimisation of the combination of columns pre-selecting the gradient profile, developed by De Beer et al. (Anal. Chem. 82 (2010) 1733), and the optimisation of the gradient program after pre-selecting the column combination using isocratic elution, developed for this work. Several refinements concerning the gradient delays along the solute migration and peak half-width modelling were included to improve the realism of the predictions. Pareto plots (expressed as analysis time versus predicted global resolution) assisted in the selection of the best separation conditions. The massive computation time in the gradient optimisation, once the column combination was optimised, was reduced to ca. 3min by using genetic algorithms. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Magnetoelectric Transverse Gradient Sensor with High Detection Sensitivity and Low Gradient Noise.

    Science.gov (United States)

    Zhang, Mingji; Or, Siu Wing

    2017-10-25

    We report, theoretically and experimentally, the realization of a high detection performance in a novel magnetoelectric (ME) transverse gradient sensor based on the large ME effect and the magnetic field gradient (MFG) technique in a pair of magnetically-biased, electrically-shielded, and mechanically-enclosed ME composites having a transverse orientation and an axial separation. The output voltage of the gradient sensor is directly obtained from the transverse MFG-induced difference in ME voltage between the two ME composites and is calibrated against transverse MFGs to give a high detection sensitivity of 0.4-30.6 V/(T/m), a strong common-mode magnetic field noise rejection rate of noise of 0.16-620 nT/m/ Hz in a broad frequency range of 1 Hz-170 kHz under a small baseline of 35 mm. An analysis of experimental gradient noise spectra obtained in a magnetically-unshielded laboratory environment reveals the domination of the pink (1/ f ) noise, dielectric loss noise, and power-frequency noise below 3 kHz, in addition to the circuit noise above 3 kHz, in the gradient sensor. The high detection performance, together with the added merit of passive and direct ME conversion by the large ME effect in the ME composites, makes the gradient sensor suitable for the passive, direct, and broadband detection of transverse MFGs.

  16. Gradient waveform pre-emphasis based on the gradient system transfer function.

    Science.gov (United States)

    Stich, Manuel; Wech, Tobias; Slawig, Anne; Ringler, Ralf; Dewdney, Andrew; Greiser, Andreas; Ruyters, Gudrun; Bley, Thorsten A; Köstler, Herbert

    2018-02-25

    The gradient system transfer function (GSTF) has been used to describe the distorted k-space trajectory for image reconstruction. The purpose of this work was to use the GSTF to determine the pre-emphasis for an undistorted gradient output and intended k-space trajectory. The GSTF of the MR system was determined using only standard MR hardware without special equipment such as field probes or a field camera. The GSTF was used for trajectory prediction in image reconstruction and for a gradient waveform pre-emphasis. As test sequences, a gradient-echo sequence with phase-encoding gradient modulation and a gradient-echo sequence with a spiral read-out trajectory were implemented and subsequently applied on a structural phantom and in vivo head measurements. Image artifacts were successfully suppressed by applying the GSTF-based pre-emphasis. Equivalent results are achieved with images acquired using GSTF-based post-correction of the trajectory as a part of image reconstruction. In contrast, the pre-emphasis approach allows reconstruction using the initially intended trajectory. The artifact suppression shown for two sequences demonstrates that the GSTF can serve for a novel pre-emphasis. A pre-emphasis based on the GSTF information can be applied to any arbitrary sequence type. © 2018 International Society for Magnetic Resonance in Medicine.

  17. Entanglement-Gradient Routing for Quantum Networks.

    Science.gov (United States)

    Gyongyosi, Laszlo; Imre, Sandor

    2017-10-27

    We define the entanglement-gradient routing scheme for quantum repeater networks. The routing framework fuses the fundamentals of swarm intelligence and quantum Shannon theory. Swarm intelligence provides nature-inspired solutions for problem solving. Motivated by models of social insect behavior, the routing is performed using parallel threads to determine the shortest path via the entanglement gradient coefficient, which describes the feasibility of the entangled links and paths of the network. The routing metrics are derived from the characteristics of entanglement transmission and relevant measures of entanglement distribution in quantum networks. The method allows a moderate complexity decentralized routing in quantum repeater networks. The results can be applied in experimental quantum networking, future quantum Internet, and long-distance quantum communications.

  18. Bioactive Molecule Prediction Using Extreme Gradient Boosting.

    Science.gov (United States)

    Babajide Mustapha, Ismail; Saeed, Faisal

    2016-07-28

    Following the explosive growth in chemical and biological data, the shift from traditional methods of drug discovery to computer-aided means has made data mining and machine learning methods integral parts of today's drug discovery process. In this paper, extreme gradient boosting (Xgboost), which is an ensemble of Classification and Regression Tree (CART) and a variant of the Gradient Boosting Machine, was investigated for the prediction of biological activity based on quantitative description of the compound's molecular structure. Seven datasets, well known in the literature were used in this paper and experimental results show that Xgboost can outperform machine learning algorithms like Random Forest (RF), Support Vector Machines (LSVM), Radial Basis Function Neural Network (RBFN) and Naïve Bayes (NB) for the prediction of biological activities. In addition to its ability to detect minority activity classes in highly imbalanced datasets, it showed remarkable performance on both high and low diversity datasets.

  19. Subduction zones seen by GOCE gravity gradients

    DEFF Research Database (Denmark)

    Švarc, Mario; Herceg, Matija; Cammarano, Fabio

    In this study, the GOCE (Gravity field and steady state Ocean Circulation Explorer) gradiometry data were used to study geologic structures and mass variations within the lithosphere in areas of known subduction zones. The advantage of gravity gradiometry over other gravity methods...... is that gradients are extremely sensitive to localized density contrasts within regional geological settings, which makes it ideally suited for detecting subduction zones. Second order gravity gradients of disturbing potential were extracted from global geopotential model, the fifth release GOCE model ‘EGM_TIM_RL05......’. In order to remove the signal which mainly corresponds to the gravity signal of the lower mantle, long wavelength part of the gravity signal was removed up to degree and order 60. Because the areas with notable topography differences coincide with subduction zones, topography correction was also performed...

  20. Sequential pattern formation governed by signaling gradients

    CERN Document Server

    Jörg, David J; Jülicher, Frank

    2016-01-01

    Rhythmic and sequential segmentation of the embryonic body plan is a vital developmental patterning process in all vertebrate species. However, a theoretical framework capturing the emergence of dynamic patterns of gene expression from the interplay of cell oscillations with tissue elongation and shortening and with signaling gradients, is still missing. Here we show that a set of coupled genetic oscillators in an elongating tissue that is regulated by diffusing and advected signaling molecules can account for segmentation as a self-organized patterning process. This system can form a finite number of segments and the dynamics of segmentation and the total number of segments formed depend strongly on kinetic parameters describing tissue elongation and signaling molecules. The model accounts for existing experimental perturbations to signaling gradients, and makes testable predictions about novel perturbations. The variety of different patterns formed in our model can account for the variability of segmentatio...

  1. Functional evolution of a morphogenetic gradient.

    Science.gov (United States)

    Kwan, Chun Wai; Gavin-Smyth, Jackie; Ferguson, Edwin L; Schmidt-Ott, Urs

    2016-12-22

    Bone Morphogenetic Proteins (BMPs) pattern the dorsal-ventral axis of bilaterian embryos; however, their roles in the evolution of body plan are largely unknown. We examined their functional evolution in fly embryos. BMP signaling specifies two extraembryonic tissues, the serosa and amnion, in basal-branching flies such as Megaselia abdita, but only one, the amnioserosa, in Drosophila melanogaster. The BMP signaling dynamics are similar in both species until the beginning of gastrulation, when BMP signaling broadens and intensifies at the edge of the germ rudiment in Megaselia, while remaining static in Drosophila. Here we show that the differences in gradient dynamics and tissue specification result from evolutionary changes in the gene regulatory network that controls the activity of a positive feedback circuit on BMP signaling, involving the tumor necrosis factor alpha homolog eiger. These data illustrate an evolutionary mechanism by which spatiotemporal changes in morphogen gradients can guide tissue complexity.

  2. Analytic gradients in electronic structure theory

    Science.gov (United States)

    Shroll, Robert Marvin

    1997-10-01

    The energy gradients for the Hartree Fock ground state, Dirac-Hartree-Fock ground state, singles-only configuration interaction approximation to the first singlet excited state, and a set of restricted singles- only configuration interaction equations are presented. Algebraic approximations will be used in all of these state energy equation derivations. This leads us to a commonality between the various methods which is the need to calculate gradients with respect to basis set expansion coefficients. For the non-relativistic correlated energy states, these coefficient derivatives will be determined using Coupled Perturbed Hartree Fock (CPHF) theory. For the relativistic case, an analogous set of equations are presented which have been called the Coupled Perturbed Dirac-Hartree-Fock (CPDHF) equations.

  3. Examining the education gradient in chronic illness

    OpenAIRE

    Chatterji, Pinka; Joo, Heesoo; Lahiri, Kajal

    2012-01-01

    This study examines the education gradient in three chronic conditions – diabetes, hypertension, and high cholesterol. In the analysis, we take into account diagnosed as well as undiagnosed cases, and we use methods that account for the possibility that unmeasured factors exist that are correlated with education and drive both the likelihood of having the illness and the propensity to be diagnosed with illness if it exists. Data come from the National Health and Nutrition Examination Survey (...

  4. Conjugate gradient optimization programs for shuttle reentry

    Science.gov (United States)

    Powers, W. F.; Jacobson, R. A.; Leonard, D. A.

    1972-01-01

    Two computer programs for shuttle reentry trajectory optimization are listed and described. Both programs use the conjugate gradient method as the optimization procedure. The Phase 1 Program is developed in cartesian coordinates for a rotating spherical earth, and crossrange, downrange, maximum deceleration, total heating, and terminal speed, altitude, and flight path angle are included in the performance index. The programs make extensive use of subroutines so that they may be easily adapted to other atmospheric trajectory optimization problems.

  5. M-step preconditioned conjugate gradient methods

    Science.gov (United States)

    Adams, L.

    1983-01-01

    Preconditioned conjugate gradient methods for solving sparse symmetric and positive finite systems of linear equations are described. Necessary and sufficient conditions are given for when these preconditioners can be used and an analysis of their effectiveness is given. Efficient computer implementations of these methods are discussed and results on the CYBER 203 and the Finite Element Machine under construction at NASA Langley Research Center are included.

  6. Intergenerational and socioeconomic gradients of childhood obesity

    OpenAIRE

    Joan Costa-i-Font; Joan Gil

    2013-01-01

    Can the rise in obesity among children be attributed to intergenerationally parental influences? How important is a parent’s socioeconomic status in accounting for the emergence of obesity among children? This paper documents evidence of an emerging social gradient of obesity in pre-school children resulting from a combination of income and education effects, as well as less intensive childcare associated with maternal employment, when different forms of intergenerational transmission are con...

  7. Designing optimal nanofocusing with a gradient hyperlens

    Science.gov (United States)

    Shen, Lian; Prokopeva, Ludmila J.; Chen, Hongsheng; Kildishev, Alexander V.

    2017-11-01

    We report the design of a high-throughput gradient hyperbolic lenslet built with real-life materials and capable of focusing a beam into a deep sub-wavelength spot of λ/23. This efficient design is achieved through high-order transformation optics and circular effective-medium theory (CEMT), which are used to engineer the radially varying anisotropic artificial material based on the thin alternating cylindrical metal and dielectric layers. The radial gradient of the effective anisotropic optical constants allows for matching the impedances at the input and output interfaces, drastically improving the throughput of the lenslet. However, it is the use of the zeroth-order CEMT that enables the practical realization of a gradient hyperlens with realistic materials. To illustrate the importance of using the CEMT versus the conventional planar effective-medium theory (PEMT) for cylindrical anisotropic systems, such as our hyperlens, both the CEMT and PEMT are adopted to design gradient hyperlenses with the same materials and order of elemental layers. The CEMT- and PEMT-based designs show similar performance if the number of metal-dielectric binary layers is sufficiently large (9+ pairs) and if the layers are sufficiently thin. However, for the manufacturable lenses with realistic numbers of layers (e.g. five pairs) and thicknesses, the performance of the CEMT design continues to be practical, whereas the PEMT-based design stops working altogether. The accurate design of transformation optics-based layered cylindrical devices enabled by CEMT allow for a new class of robustly manufacturable nanophotonic systems, even with relatively thick layers of real-life materials.

  8. Fracture driven by a Thermal Gradient

    CERN Document Server

    Pla, O

    1995-01-01

    Motivated by recent experiments by Yuse and Sano (Nature, 362, 329 (1993)), we propose a discrete model of linear springs for studying fracture in thin and elastically isotropic brittle films. The method enables us to draw a map of the stresses in the material. Cracks generated by the model, imposing a moving thermal gradient in the material, can branch or wiggle depending on the driving parameters. The results may be used to compare with other recent theoretical work, or to design future experiments.

  9. Advanced concepts for high-gradient acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Whittum, D.H.

    1998-08-01

    The promise of high-gradient accelerator research is a future for physics beyond the 5-TeV energy scale. Looking beyond what can be engineered today, the authors examine basic research directions for colliders of the future, from mm-waves to lasers, and from solid-state to plasmas, with attention to material damage, beam-dynamics, a workable collision scheme, and energetics.

  10. Velocity Gradient Power Functional for Brownian Dynamics.

    Science.gov (United States)

    de Las Heras, Daniel; Schmidt, Matthias

    2018-01-12

    We present an explicit and simple approximation for the superadiabatic excess (over ideal gas) free power functional, admitting the study of the nonequilibrium dynamics of overdamped Brownian many-body systems. The functional depends on the local velocity gradient and is systematically obtained from treating the microscopic stress distribution as a conjugate field. The resulting superadiabatic forces are beyond dynamical density functional theory and are of a viscous nature. Their high accuracy is demonstrated by comparison to simulation results.

  11. Self-organization of intracellular gradients during mitosis

    Directory of Open Access Journals (Sweden)

    Fuller Brian G

    2010-01-01

    Full Text Available Abstract Gradients are used in a number of biological systems to transmit spatial information over a range of distances. The best studied are morphogen gradients where information is transmitted over many cell lengths. Smaller mitotic gradients reflect the need to organize several distinct events along the length of the mitotic spindle. The intracellular gradients that characterize mitosis are emerging as important regulatory paradigms. Intracellular gradients utilize intrinsic auto-regulatory feedback loops and diffusion to establish stable regions of activity within the mitotic cytosol. We review three recently described intracellular mitotic gradients. The Ran GTP gradient with its elaborate cascade of nuclear transport receptors and cargoes is the best characterized, yet the dynamics underlying the robust gradient of Ran-GTP have received little attention. Gradients of phosphorylation have been observed on Aurora B kinase substrates both before and after anaphase onset. In both instances the phosphorylation gradient appears to result from a soluble gradient of Aurora B kinase activity. Regulatory properties that support gradient formation are highlighted. Intracellular activity gradients that regulate localized mitotic events bare several hallmarks of self-organizing biologic systems that designate spatial information during pattern formation. Intracellular pattern formation represents a new paradigm in mitotic regulation.

  12. Gradient field microscopy of unstained specimens

    Science.gov (United States)

    Kim, Taewoo; Sridharan, Shamira; Popescu, Gabriel

    2012-01-01

    We present a phase derivative microscopy technique referred to as gradient field microscopy (GFM), which provides the first-order derivatives of the phase associated with an optical field passing through a transparent specimen. GFM utilizes spatial light modulation at the Fourier plane of a bright field microscope to optically obtain the derivatives of the phase and increase the contrast of the final image. The controllable spatial modulation pattern allows us to obtain both one component of the field gradient (derivative along one direction) and the gradient intensity, which offers some advantages over the regular differential interference contrast (DIC) microscopy. Most importantly, unlike DIC, GFM does not use polarizing optics and, thus, it is applicable to birefringent samples. We demonstrate these features of GFM with studies of static and dynamic biological cells (HeLa cells and red blood cells). We show that GFM is capable of qualitatively providing information about cell membrane fluctuations. Specifically, we captured the disappearance of the bending mode of fluctuations in osmotically swollen red blood cells. PMID:22418558

  13. Air temperature gradient in large industrial hall

    Science.gov (United States)

    Karpuk, Michał; Pełech, Aleksander; Przydróżny, Edward; Walaszczyk, Juliusz; Szczęśniak, Sylwia

    2017-11-01

    In the rooms with dominant sensible heat load, volume airflow depends on many factors incl. pre-established temperature difference between exhaust and supply airflow. As the temperature difference is getting higher, airflow volume drops down, consequently, the cost of AHU is reduced. In high industrial halls with air exhaust grids located under the ceiling additional temperature gradient above working zone should be taken into consideration. In this regard, experimental research of the vertical air temperature gradient in high industrial halls were carried out for the case of mixing ventilation system The paper presents the results of air temperature distribution measurements in high technological hall (mechanically ventilated) under significant sensible heat load conditions. The supply airflow was delivered to the hall with the help of the swirl diffusers while exhaust grids were located under the hall ceiling. Basing on the air temperature distribution measurements performed on the seven pre-established levels, air temperature gradient in the area between 2.0 and 7.0 m above the floor was calculated and analysed.

  14. High-thermal-gradient Superalloy Crystal Growth

    Science.gov (United States)

    Pearson, D. D.; Anton, D. L.; Giamei, A. F.

    1985-01-01

    Single, (001)-oriented crystals of PWA 1480 were processed in alumina/silica shell molds in a laboratory high gradient furnace. The furnace employs a graphite resistance heated element, a radiation baffle, and a water cooled radiation trap below the baffle. All crystals were grown in vacuum (10 torr) and all heat transfer was radiative. The element is constructed with a variable cross section that is tapered just above the baffle to maximize heat input and therefore thermal gradient. A maximum alloy temperature of 1600 C was used. A thermal gradient of 130 deg C/cm was recorded at 1370 C just above the solidus of the PWA 1480 alloys. Crystal bars with 14.4 and 17.5 mm diameters were grown in alumina/silica shell molds. Each crystal was started from a 1.6 mm pencil seed at a rate of 76 mm/hr and slowly accelerated to a rate of 200 mm/hr under computer control. Volume percent porosity and average pore size were measured as functions of distance in representative bars. Low cycle fatigue behavior and stress rupture properties were determined.

  15. Experimental study on neutronics in bombardment of thick targets by high energy proton beams for accelerator-driven sub-critical system

    CERN Document Server

    Guo Shi Lun; Shi Yong Qian; Shen Qing Biao; Wan Jun Sheng; Brandt, R; Vater, P; Kulakov, B A; Krivopustov, M I; Sosnin, A N

    2002-01-01

    The experimental study on neutronics in the target region of accelerator-driven sub-critical system is carried out by using the high energy accelerator in Joint Institute for Nuclear Research, Dubna, Russia. The experiments with targets U(Pb), Pb and Hg bombarded by 0.533, 1.0, 3.7 and 7.4 GeV proton beams show that the neutron yield ratio of U(Pb) to Hg and Pb to Hg targets is (2.10 +- 0.10) and (1.76 +- 0.33), respectively. Hg target is disadvantageous to U(Pb) and Pb targets to get more neutrons. Neutron yield drops along 20 cm thick targets as the thickness penetrated by protons increases. The lower the energy of protons, the steeper the neutron yield drops. In order to get more uniform field of neutrons in the targets, the energy of protons from accelerators should not be lower than 1 GeV. The spectra of secondary neutrons produced by different energies of protons are similar, but the proportion of neutrons with higher energy gradually increases as the proton energy increases

  16. Biodiesel from Hydrolyzed Waste Cooking Oil Using a S-ZrO2/SBA-15 Super Acid Catalyst under Sub-Critical Conditions

    Directory of Open Access Journals (Sweden)

    Muhammad Nobi Hossain

    2018-01-01

    Full Text Available Due to rapid changes in food habits, a substantial amount of waste fat and used oils are generated each year. Due to strong policies, the disposal of this material into nearby sewers causes ecological and environmental problems in many parts of the world. For efficient management, waste cooking oil, a less expensive, alternative and promising feedstock, can be used as a raw material for producing biofuel. In the present study, we produced a biodiesel from hydrolyzed waste cooking oil with a subcritical methanol process using a synthesized solid super acid catalyst, a sulfated zirconium oxide supported on Santa Barbara Amorphous silica (S-ZrO2/SBA-15. The characterization of the synthesized catalyst was carried out using scanning electron microscopy (SEM, X-ray diffraction (XRD, and the Brunauer-Emmett-Teller (BET method. The catalytic effect on biodiesel production was examined by varying the parameters: temperatures of 120 to 200 °C, 5–20 min times, oil-to-methanol mole ratios between 1:5 to 1:20, and catalyst loadings of 1–2.5%. The maximum biodiesel yield was 96.383%, obtained under optimum reaction conditions of 140 °C, 10 min, and a 1:10 oil-to-methanol molar ratio with a 2.0% catalyst loading. We successfully reused the catalyst five times without regeneration with a 90% efficiency. The fuel properties were found to be within the limits set by the biodiesel standard.

  17. Design of a heterogeneous subcritical nuclear reactor with molten salts based on thorium; Diseno de un reactor nuclear subcritico heterogeneo con sales fundidas a base de torio

    Energy Technology Data Exchange (ETDEWEB)

    Medina C, D.; Hernandez A, P.; Letechipia de L, C.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Sajo B, L., E-mail: dmedina_c@hotmail.com [Universidad Simon Bolivar, Laboratorio de Fisica Nuclear, Apdo. Postal 89000, Caracas 1080-A (Venezuela, Bolivarian Republic of)

    2015-09-15

    This paper presents the design of a heterogeneous subcritical nuclear reactor with molten salts based on thorium, with graphite moderator and a {sup 252}Cf source, whose dose levels at the periphery allows its use in teaching and research activities. The design was realized by the Monte Carlo method, where the geometry, dimensions and the fuel was varied in order to obtain the best design. The result was a cubic reactor of 110 cm of side, with graphite moderator and reflector. In the central part having 9 ducts of 3 cm in diameter, eight of them are 110 cm long, which were placed on the Y axis; the separation between each duct is 10 cm. The central duct has 60 cm in length and this contains the {sup 252}Cf source, also there are two irradiation channels and the other six contain a molten salt ({sup 7}LiF - BeF{sub 2} - ThF{sub 4} - UF{sub 4}) as fuel. For the design the k{sub eff} was calculated, neutron spectra and ambient dose equivalent. In the first instance the above was calculated for a virgin fuel, was called case 1; then a percentage of {sup 233}U was used and the percentage of Th was decreased and was called case 2. This with the purpose of comparing two different fuels operating within the reactor. For the two irradiation ducts three positions are used: center, back and front, in each duct in order to have different flows. (Author)

  18. Short communication: antiviral activity of subcritical water extract of Brassica juncea against influenza virus A/H1N1 in nonfat milk.

    Science.gov (United States)

    Lee, N-K; Lee, J-H; Lim, S-M; Lee, K A; Kim, Y B; Chang, P-S; Paik, H-D

    2014-09-01

    Subcritical water extract (SWE) of Brassica juncea was studied for antiviral effects against influenza virus A/H1N1 and for the possibility of application as a nonfat milk supplement for use as an "antiviral food." At maximum nontoxic concentrations, SWE had higher antiviral activity against influenza virus A/H1N1 than n-hexane, ethanol, or hot water (80°C) extracts. Addition of 0.5mg/mL of B. juncea SWE to culture medium led to 50.35% cell viability (% antiviral activity) for Madin-Darby canine kidney cells infected with influenza virus A/H1N1. Nonfat milk supplemented with 0.28mg/mL of B. juncea SWE showed 39.62% antiviral activity against influenza virus A/H1N1. Thus, the use of B. juncea SWE as a food supplement might aid in protection from influenza viral infection. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  19. Subcritical water oxidation of 6-aminopenicillanic acid and cloxacillin using H2O2, K2S2O8, and O2.

    Science.gov (United States)

    Yabalak, Erdal; Döndaş, H Ali; Gizir, Ahmet Murat

    2017-02-23

    This study was undertaken to investigate the degradation of 6-aminopenicillanic acid (6-APA) and cloxacillin in aqueous solution by the combined effect of subcritical water and the oxidising agents O2, H2O2, and K2S2O8. Nano ZnO was used as a solid catalyst. Response surface methodology was used to determine the optimum experimental parameters (temperature, treatment time, and concentration of oxidising agent). For 6-APA, the maximum organic carbon (TOC) removal rates of 83.54%, 81.11% and 42.42% were obtained using H2O2, K2S2O8, and O2, respectively. For cloxacillin, the maximum TOC removal rates of 67.69%, 76.02% and 14.45% were obtained using H2O2, K2S2O8, and O2, respectively. Additionally, the impact of nano and commercial ZnO on TOC removal rates was determined. Secondary ions produced during the degradation process-such as nitrite, nitrate, sulphate and chloride-were determined using ion chromatography.

  20. Subcritical water treatment of explosive and heavy metals co-contaminated soil: Removal of the explosive, and immobilization and risk assessment of heavy metals.

    Science.gov (United States)

    Islam, Mohammad Nazrul; Jung, Ho-Young; Park, Jeong-Hun

    2015-11-01

    Co-contamination of explosives and heavy metals (HMs) in soil, particularly army shooting range soil, has received increasing environmental concern due to toxicity and risks to ecological systems. In this study, a subcritical water (SCW) extraction process was used to remediate the explosives-plus-HMs-co-contaminated soil. A quantitative evaluation of explosives in the treated soil, compared with untreated soil, was applied to assess explosive removal. The immobilization of HMs was assessed by toxicity characteristic leaching procedure tests, and by investigating the migration of HMs fractions. The environmental risk of HMs in the soil residue was assessed according to the risk assessment code (RAC) and ecological risk indices (Er and RI). The results indicated that SCW treatment could eliminate the explosives, >99%, during the remediation, while the HM was effectively immobilized. The effect of water temperature on reducing the explosives and the risk of HMs in soil was observed. A marked increase in the non-bioavailable concentration of each HM was observed, and the leaching rate of HMs was decreased by 70-97% after SCW treatment at 250 °C, showing the effective immobilization of HMs. According to the RAC or RI, each tested HM showed no or low risk to the environment after treatment. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Subcritical hydrothermal liquefaction of cattle manure to bio-oil: Effects of conversion parameters on bio-oil yield and characterization of bio-oil.

    Science.gov (United States)

    Yin, Sudong; Dolan, Ryan; Harris, Matt; Tan, Zhongchao

    2010-05-01

    In this study, cattle manure was converted to bio-oil by subcritical hydrothermal liquefaction in the presence of NaOH. The effects of conversion temperature, process gas, initial conversion pressure, residence time and mass ratio of cattle manure to water on the bio-oil yield were studied. The bio-oil was characterized in terms of elemental composition, higher heating value, ultraviolet-visible (UV/Vis) spectroscopy, Fourier transform infrared spectroscopy (FTIR), gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Results showed that the bio-oil yield depended on the conversion temperature and the process gas. Higher initial conversion pressure, longer residence time and larger mass ratio of cattle manure to water, however, had negative impacts on the bio-oil yield. The higher heating value of bio-oil was 35.53MJ/kg on average. The major non-polar components of bio-oil were toluene, ethyl benzene and xylene, which are components of crude oil, gasoline and diesel. Copyright 2010 Elsevier Ltd. All rights reserved.

  2. The effect of filler addition and oven temperature to the antioxidant quality in the drying of Physalis angulata fruit extract obtained by subcritical water extraction

    Science.gov (United States)

    Susanti, R. F.; Christianto, G.

    2016-01-01

    Physalis angulata or ceplukan is medicinal herb, which grows naturally in Indonesia. It has been used in traditional medicine to treat several diseases. It is also reported to have antimycobacterial, antileukemic, antipyretic. In this research, Pysalis angulata fruit was investigated for its antioxidant capacity. In order to avoid the toxic organic solvent commonly used in conventional extraction, subcritical water extraction method was used. During drying, filler which is inert was added to the extract. It can absorb water and change the oily and sticky form of extract to powder form. The effects of filler types, concentrations and drying temperatures were investigated to the antioxidant quality covering total phenol, flavonoid and antioxidant activity. The results showed that total phenol, flavonoid and antioxidant activity were improved by addition of filler because the drying time was shorter compared to extract without filler. Filler absorbs water and protects extract from exposure to heat during drying. The combination between high temperature and shorter drying time are beneficial to protect the antioxidant in extract. The type of fillers investigation showed that aerosil gave better performance compared to Microcrystalline Celullose (MCC).

  3. High-resolution gas-chromatographic analysis of the secondary metabolites obtained by subcritical-fluid extraction from Colombian rue (Ruta graveolens L.).

    Science.gov (United States)

    Stashenko, E E; Acosta, R; Martínez, J R

    2000-07-05

    Subcritical (CO(2)) extraction, carried out in a J&W Scientific High Pressure Soxhlet Extractor, was used to isolate secondary metabolites from leaves, flowers, stems and roots of Colombian rue (Ruta graveolens L.). The various extracts were analyzed by capillary chromatography, on an HP-5 (30 m) column, using nitrogen-phosphorus, flame ionization, and mass selective detection systems. Kováts indexes and mass spectra (electron impact, 70 eV) were employed for compound identification. The extracts from the various parts of rue studied had different compositions. The number of compounds detected at concentrations above 0.01% (w/w) in the extracts from leaves, flowers, stems and roots, was 78, 45, 25 and 24, respectively. 2-Nonanone (8.9%), 2-undecanone (13.4%), chalepensin (13.0%), and geijerene (19.3%) were the main constituents found in the extracts from rue leaves, flowers, stems and roots, respectively. Furanocoumarins, furoquinolines, hydrocarbons and benzodioxol derivatives were the main compound families found in all extracts, at total concentrations between 3.7 and 33.9%, depending on the part of the plant. The extraction method used has low environmental impact and produced solvent-free extracts in good yield with no pigments, waxes, resins, or high-molecular weight compounds which may interfere with the isolation and analysis of the alkaloids responsible for rue's biological activity, which were extracted in relatively high yield.

  4. High sensitivity isotope analysis with a /sup 252/Cf--/sup 235/U fueled subcritical multiplier and low background photon detector systems

    Energy Technology Data Exchange (ETDEWEB)

    Wogman, N.A.; Rieck, H.G. Jr.; Laul, J.C.; MacMurdo, K.W.

    1976-09-01

    A /sup 252/Cf activation analysis facility has been developed for routine multielement analysis of a wide variety of solid and liquid samples. The facility contains six sources of /sup 252/Cf totaling slightly over 100 mg. These sources are placed in a 93 percent /sup 235/U-enriched uranium core which is subcritical with a K effective of 0.985 (multiplication factor of 66). The system produces a thermal flux on the order of 10/sup +1/ neutrons per square centimeter per second. A pneumatic rabbit system permits automatic irradiation, decay, and counting regimes to be performed unattended on the samples. The activated isotopes are analyzed through their photon emissions with state-of-the-art intrinsic Ge detectors, Ge(Li) detectors, and NaI(Tl) multidimensional gamma ray spectrometers. High efficiency (25 percent), low background, anticoincidence shielded Ge(Li) gamma ray detector systems have been constructed to provide the lowest possible background, yet maintain a peak to Compton ratio of greater than 1000 to 1. The multidimensional gamma ray spectrometer systems are composed of 23 cm diameter x 20 cm thick NaI(Tl) crystals surrounded by NaI(Tl) anticoincidence shields. The detection limits for over 65 elements have been determined for this system. Over 40 elements are detectable at the 1 part per million level at a precision of +-10 percent.

  5. Technical note: Development of a gradient tube method for ...

    African Journals Online (AJOL)

    Technical note: Development of a gradient tube method for examining microbial population structures in floating sulphur biofilms. ... parameters within the system. Keywords: gradient tube method, floating biofilms, floating sulphur biofilms, microbial ecology, sulphur biotechnology, acid mine drainage wastewaters ...

  6. Integrated gravity and gravity gradient 3D inversion using the non-linear conjugate gradient

    Science.gov (United States)

    Qin, Pengbo; Huang, Danian; Yuan, Yuan; Geng, Meixia; Liu, Jie

    2016-03-01

    Gravity data, which are critical in mineral, oil, and gas exploration, are obtained from the vertical component of the gravity field, while gravity gradient data are measured from changes in the gravity field in three directions. However, few studies have sought to improve exploration techniques by integrating gravity and gravity gradient data using inversion methods. In this study, we developed a new method to integrate gravity and gravity gradient data in a 3D density inversion using the non-linear conjugate gradient (NLCG) method and the minimum gradient support (MGS) functional to regularize the 3D inverse problem and to obtain a clear and accurate image of the anomalous body. The NLCG algorithm, which is suitable for solving large-scale nonlinear optimization problems and requires no memory storage, was compared to the Broyden-Fletcher-Goldfarb-Shanno (BFGS) quasi-Newton algorithm and the results indicated that the convergence rate of NLCG is slower, but that the storage requirement and computation time is lower. To counteract the decay in kernel function, we introduced a depth weighting function for anomalous bodies at the same depth, with information about anomalous body depth obtained from well log and seismic exploration data. For anomalous bodies at different depths, we introduced a spatial gradient weighting function to incorporate additional information obtained in the inversion. We concluded that the spatial gradient weighting function enhanced the spatial resolution of the recovered model. Furthermore, our results showed that including multiple components for inversion increased the resolution of the recovered model. We validated our model by applying our inversion method to survey data from Vinton salt dome, Louisiana, USA. The results showed good agreement with known geologic information; thus confirming the accuracy of this approach.

  7. Magnetoelectric Transverse Gradient Sensor with High Detection Sensitivity and Low Gradient Noise

    Directory of Open Access Journals (Sweden)

    Mingji Zhang

    2017-10-01

    Full Text Available We report, theoretically and experimentally, the realization of a high detection performance in a novel magnetoelectric (ME transverse gradient sensor based on the large ME effect and the magnetic field gradient (MFG technique in a pair of magnetically-biased, electrically-shielded, and mechanically-enclosed ME composites having a transverse orientation and an axial separation. The output voltage of the gradient sensor is directly obtained from the transverse MFG-induced difference in ME voltage between the two ME composites and is calibrated against transverse MFGs to give a high detection sensitivity of 0.4–30.6 V/(T/m, a strong common-mode magnetic field noise rejection rate of <−14.5 dB, a small input-output nonlinearity of <10 ppm, and a low gradient noise of 0.16–620 nT/m/ Hz in a broad frequency range of 1 Hz–170 kHz under a small baseline of 35 mm. An analysis of experimental gradient noise spectra obtained in a magnetically-unshielded laboratory environment reveals the domination of the pink (1/f noise, dielectric loss noise, and power-frequency noise below 3 kHz, in addition to the circuit noise above 3 kHz, in the gradient sensor. The high detection performance, together with the added merit of passive and direct ME conversion by the large ME effect in the ME composites, makes the gradient sensor suitable for the passive, direct, and broadband detection of transverse MFGs.

  8. Comparing species interaction networks along environmental gradients.

    Science.gov (United States)

    Pellissier, Loïc; Albouy, Camille; Bascompte, Jordi; Farwig, Nina; Graham, Catherine; Loreau, Michel; Maglianesi, Maria Alejandra; Melián, Carlos J; Pitteloud, Camille; Roslin, Tomas; Rohr, Rudolf; Saavedra, Serguei; Thuiller, Wilfried; Woodward, Guy; Zimmermann, Niklaus E; Gravel, Dominique

    2017-09-22

    Knowledge of species composition and their interactions, in the form of interaction networks, is required to understand processes shaping their distribution over time and space. As such, comparing ecological networks along environmental gradients represents a promising new research avenue to understand the organization of life. Variation in the position and intensity of links within networks along environmental gradients may be driven by turnover in species composition, by variation in species abundances and by abiotic influences on species interactions. While investigating changes in species composition has a long tradition, so far only a limited number of studies have examined changes in species interactions between networks, often with differing approaches. Here, we review studies investigating variation in network structures along environmental gradients, highlighting how methodological decisions about standardization can influence their conclusions. Due to their complexity, variation among ecological networks is frequently studied using properties that summarize the distribution or topology of interactions such as number of links, connectance, or modularity. These properties can either be compared directly or using a procedure of standardization. While measures of network structure can be directly related to changes along environmental gradients, standardization is frequently used to facilitate interpretation of variation in network properties by controlling for some co-variables, or via null models. Null models allow comparing the deviation of empirical networks from random expectations and are expected to provide a more mechanistic understanding of the factors shaping ecological networks when they are coupled with functional traits. As an illustration, we compare approaches to quantify the role of trait matching in driving the structure of plant-hummingbird mutualistic networks, i.e. a direct comparison, standardized by null models and hypothesis

  9. Controllable Soluble Protein Concentration Gradients in Hydrogel Networks**

    OpenAIRE

    Peret, Brian J.; William L Murphy

    2008-01-01

    Here we report controlled formation of sustained, soluble protein concentration gradients within hydrated polymer networks. The approach involves spatially localizing proteins or biodegradable, protein-loaded microspheres within hydrogels to form a protein-releasing “depot”. Soluble protein concentration gradients are then formed as the released protein diffuses away from the localized source. Control over key gradient parameters, including maximum concentration, gradient magnitude, slope, an...

  10. Salinity Gradient Energy: Current State and New Trends

    Directory of Open Access Journals (Sweden)

    Olivier Schaetzle

    2015-06-01

    Full Text Available In this article we give an overview of the state of the art of salinity gradient technologies. We first introduce the concept of salinity gradient energy, before describing the current state of development of the most advanced of these technologies. We conclude with the new trends in the young field of salinity gradient technologies.

  11. Gradient Descent Bit Flipping Algorithms for Decoding LDPC Codes

    OpenAIRE

    Wadayama, Tadashi; Nakamura, Keisuke; Yagita, Masayuki; Funahashi, Yuuki; Usami, Shogo; Takumi, Ichi

    2007-01-01

    A novel class of bit-flipping (BF) algorithms for decoding low-density parity-check (LDPC) codes is presented. The proposed algorithms, which are called gradient descent bit flipping (GDBF) algorithms, can be regarded as simplified gradient descent algorithms. Based on gradient descent formulation, the proposed algorithms are naturally derived from a simple non-linear objective function.

  12. Compressive and extensive strain along gradient trajectories

    Energy Technology Data Exchange (ETDEWEB)

    Gampert, Markus; Goebbert, Jens Henrik; Schaefer, Philip; Gauding, Michael; Peters, Norbert [Institut fuer Technische Verbrennung, RWTH Aachen (Germany); Aldudak, Fettah; Oberlack, Martin, E-mail: m.gampert@itv.rwth-aachen.de [Fachgebiet fuer Stroemungsdynamik, Technische Universitaet Darmstadt (Germany)

    2011-12-22

    Based on direct numerical simulations of forced turbulence, shear turbulence, decaying turbulence, a turbulent channel flow as well as a Kolmogorov flow with Taylor based Reynolds numbers Re{sub {lambda}} between 69 and 295, the normalized probability density function of the length distribution P-tilde (l-tilde) of dissipation elements, the conditional mean scalar difference < {Delta}k | l > at the extreme points as well as the scaling of the two-point velocity difference along gradient trajectories < {Delta}u{sub n}> are studied. Using the field of the instantanous turbulent kinetic energy k as a scalar, we find a good agreement between the model equation for P-tilde (l-tilde) as proposed by Wang and Peters (2008) and the results obtained in the different DNS cases. This confirms the independance of the model solution from both, the Reynolds number and the type of turbulent flow, so that it can be considered universally valid. In addition, we show a 2/3 scaling for the mean conditional scalar difference. In the second part of the paper, we examine the scaling of the conditional two-point velocity difference along gradient trajectories. In particular, we compare the linear s/{tau} scaling, where {tau} denotes an integral time scale and s the separation arclength along a gradient trajectory in the inertial range as derived by Wang (2009) with the s {center_dot} a{sub {infinity}} scaling, where a{sub {infinity}} denotes the asymtotic value of the conditional mean strain rate of large dissipation elements.

  13. Damping of toroidal ion temperature gradient modes

    Energy Technology Data Exchange (ETDEWEB)

    Sugama, H. [National Inst. for Fusion Science, Toki, Gifu (Japan)

    1999-04-01

    The temporal evolution of linear toroidal ion temperature gradient (ITG) modes is studied based on a kinetic integral equation including an initial condition. It is shown how to evaluate the analytic continuation of the integral kernel as a function of a complex-valued frequency, which is useful for analytical and numerical calculations of the asymptotic damping behavior of the ITG mode. In the presence of the toroidal {nabla}B-curvature drift, the temporal dependence of the density and potential perturbations consists of normal modes and a continuum mode, which correspond to contributions from poles and from an integral along a branch cut, respectively, of the Laplace-transformed potential function of the complex-valued frequency. The normal modes have exponential time dependence with frequencies and growth rates determined by the dispersion relation while the continuum mode, which has a ballooning structure, shows a power law decay {proportional_to} t{sup -2} in the asymptotic limit, where t is the time variable. Therefore, the continuum mode dominantly describes the long-time asymptotic behavior of the density and potential perturbations for the stable system where all normal modes have negative growth rates. By performing proper analytic continuation for the homogeneous version of the kinetic integral equation, dependences of the normal modes` growth rate, real frequency, and eigenfunction on {eta}{sub i} (the ratio of the ion temperature gradient to the density gradient), k{sub {theta}} (the poloidal wavenumber), s (the magnetic shear parameter), and {theta}{sub k} (the ballooning angle corresponding to the minimum radial wavenumber) are numerically obtained for both stable and unstable cases. (author)

  14. Stochastic stability of measures in gradient systems

    Science.gov (United States)

    Huang, Wen; Ji, Min; Liu, Zhenxin; Yi, Yingfei

    2016-01-01

    Stochastic stability of a compact invariant set of a finite dimensional, dissipative system is studied in our recent work "Concentration and limit behaviors of stationary measures" (Huang et al., 2015) for general white noise perturbations. In particular, it is shown under some Lyapunov conditions that the global attractor of the systems is always stable under general noise perturbations and any strong local attractor in it can be stabilized by a particular family of noise perturbations. Nevertheless, not much is known about the stochastic stability of an invariant measure in such a system. In this paper, we will study the issue of stochastic stability of invariant measures with respect to a finite dimensional, dissipative gradient system with potential function f. As we will show, a special property of such a system is that it is the set of equilibria which is stable under general noise perturbations and the set Sf of global minimal points of f which is stable under additive noise perturbations. For stochastic stability of invariant measures in such a system, we will characterize two cases of f, one corresponding to the case of finite Sf and the other one corresponding to the case when Sf is of positive Lebesgue measure, such that either some combined Dirac measures or the normalized Lebesgue measure on Sf is stable under additive noise perturbations. However, we will show by constructing an example that such measure stability can fail even in the simplest situation, i.e., in 1-dimension there exists a potential function f such that Sf consists of merely two points but no invariant measure of the corresponding gradient system is stable under additive noise perturbations. Crucial roles played by multiplicative and additive noise perturbations to the measure stability of a gradient system will also be discussed. In particular, the nature of instabilities of the normalized Lebesgue measure on Sf under multiplicative noise perturbations will be exhibited by an example.

  15. Smoothed Analysis for the Conjugate Gradient Algorithm

    Science.gov (United States)

    Menon, Govind; Trogdon, Thomas

    2016-11-01

    The purpose of this paper is to establish bounds on the rate of convergence of the conjugate gradient algorithm when the underlying matrix is a random positive definite perturbation of a deterministic positive definite matrix. We estimate all finite moments of a natural halting time when the random perturbation is drawn from the Laguerre unitary ensemble in a critical scaling regime explored in Deift et al. (2016). These estimates are used to analyze the expected iteration count in the framework of smoothed analysis, introduced by Spielman and Teng (2001). The rigorous results are compared with numerical calculations in several cases of interest.

  16. Gradient based filtering of digital elevation models

    DEFF Research Database (Denmark)

    Knudsen, Thomas; Andersen, Rune Carbuhn

    We present a filtering method for digital terrain models (DTMs). The method is based on mathematical morphological filtering within gradient (slope) defined domains. The intention with the filtering procedure is to improbé the cartographic quality of height contours generated from a DTM based...... on draping and optimum interpolation methods. The contours from the unfiltered DTM has shown to become ragged and hard-to-interpret—especially in areas of minor slope. The contours from the filtered DTM are significantly more smooth. They are however not smoothed to an extent where local breaks...

  17. Human impact gradient on mammalian biodiversity

    Directory of Open Access Journals (Sweden)

    Mariana Munguía

    2016-04-01

    Full Text Available Drastic changes have been caused by human influence in natural landscapes, which may exert an intensive effect on species loss. However, species loss from human pressure is not random but depends on a series of environmentally associated factors. Linking species traits to environmental attributes may allow us to detect the ecological impacts of habitat so that meaningful habitat degradation gradients can be identified. The relationships between environmental factors and species traits provide the basis for identifying those biological traits that make species more sensitive to disturbance. These relationships are also helpful to detect the geographic distribution of latent risk to reveal areas where biodiversity is threatened. Here, we identify a “Human Impact Gradient for Biodiversity (HIGB” based on a three-table ordination method (RLQ analysis and fourth-corner analysis to identify key species traits that are associated with environmental gradient. Species distribution and environmental geographic data were gathered nationwide to analyze 68 localities, which represent 27% of Mexico’s surface, including 211 species of mammals. Nine environmental variables (including biophysical, geophysical and land-use impacts were analyzed by using the Geographic Information System. Three types of species’ traits were evaluated: locomotion, trophic habit and body size. We identified a human impact gradient, which was mainly determined by the percentage of the area that was covered by seedlings, the plant richness, the understory coverage percentage and the human settlement index. The most important species traits that are associated with non-human-impacted sites were carnivores, frugivores–herbivores and a body size that was greater than 17.8 kg; 25 species were selected by the decision criteria framework for species that were sensitive to degradation based on ecological function information. Conversely, granivores, fossorial and semifossorial

  18. Gradient-index optics fundamentals and applications

    CERN Document Server

    Gomez-Reino, Carlos; Bao, Carmen

    2010-01-01

    Gradient-Index (GRIN) optics provides a comprehensive and thorough treatment on fundamentals and applications of light propagation through inhomogeneous media. The book can be used both as a classroom text for students in physics and engineering and as a reference for specialists. A description of the phenomena, components and technology used in GRIN Optics are presented. The relationship to lenses, waveguides, optical connections, spatial solitons and vision is demonstrated. Applications of GRIN components and hybrid structures for optical connections, optical sensing and Talbot effect are analyzed.

  19. Quasi parton distributions and the gradient flow

    Science.gov (United States)

    Monahan, Christopher; Orginos, Kostas

    2017-03-01

    We propose a new approach to determining quasi parton distribution functions (PDFs) from lattice quantum chromodynamics. By incorporating the gradient flow, this method guarantees that the lattice quasi PDFs are finite in the continuum limit and evades the thorny, and as yet unresolved, issue of the renormalization of quasi PDFs on the lattice. In the limit that the flow time is much smaller than the length scale set by the nucleon momentum, the moments of the smeared quasi PDF are proportional to those of the lightfront PDF. We use this relation to derive evolution equations for the matching kernel that relates the smeared quasi PDF and the light-front PDF.

  20. Impact of Ozone Gradient on Grapevine Leaves

    Science.gov (United States)

    Alebic-Juretic, Ana; Bokan-Vucelic, Itana; Mifka, Boris; Zatezalo, Marija; Zubak, Velimir

    2017-04-01

    Due to complex orography and air mass circulation, the Rijeka Bay area is characterized by O3 gradient, with concentrations risen with the altitude (1). Therefore AOT40 values were often exceeded and should result in harmful effects on vegetation. Based on previous controlled experiments (2), we examined the possible effect of atmospheric ozone on grape leaves under natural O3 gradient. Grapevine leaves (2-5) were collected from May to September 2016 at two sampling points in the proximity of two AQM stations: Site 1 in the city centre (20m asl) and Site 2 (186m asl) in the suburban settlement. Subsequent to weighing and determination of surface area, the leaves (0,5 g) were extracted in 95% ethanol and analysed on chlorophyl a (Chla), chlorophyl b (Chlb) and carotene (Car) content by UV-VIS spectrometry on 3 wavelengths (664, 649, 470 nm) (3) In summer 2016 O3 gradient was not that pronounced as usual (1), but stil the concentrations differed by approx. 20%, exceeding national AOT40 value at both sites (22.360 and 28.061 μg m-3 h, respectively, at Sites 1 and 2). The concentrations of other pollutants were bellow limit values (LV). The Cha and Chb in a sample leaves collected at the end of May at Site 2 are equal to that with filtered O3 in control experiment (2), i.e. without damage caused by ozone, while the Car content is lower approx. 50% and is kept at the same level. The con-centrations of pigments obtained in July prooved the possible damage by O3, while in subsequent months could speed up natural ageing. This is the first evidence of O3 damage on plants in the Rijeka Bay area, in spite of weaker O3 gradient and lacking visible signs of damage. Preliminary results indicate the need for more frequent sampling, particularly in the period included in AOT40 (May-July). References: 1. Alebić-Juretić A (2012) Int J Remote Sensing, 33(2): 335-345 2. Britvec M, Reichenauer T, Soja G., Ljubešić N, Pećina M (2001) Biologia (Bratislava),56/4: 417-424 3. Sumanata

  1. The educational gradient in coronary heart disease

    DEFF Research Database (Denmark)

    Ariansen, Inger; Mortensen, Laust Hvas; Igland, Jannicke

    2015-01-01

    BACKGROUND: Independently of cardiovascular disease (CVD) risk factors, cognitive ability may account for some of the excess risk of coronary heart disease (CHD) associated with lower education. We aimed to assess how late adolescence cognitive ability and midlife CVD risk factors are associated...... with the educational gradient in CHD in Norway. METHODS: In a cohort of 57 279 men born during 1949-1959, health survey information was linked to military conscription records of cognitive ability, to national educational data, to hospitalisation records from the Cardiovascular Disease in Norway (CVDNOR) project...

  2. Method of thermal derivative gradient analysis (TDGA

    Directory of Open Access Journals (Sweden)

    M. Cholewa

    2009-07-01

    Full Text Available In this work a concept of thermal analysis was shown, using for crystallization kinetics description the temperature derivatives after time and direction. Method of thermal derivative gradient analysis (TDGA is assigned for alloys and metals investigation as well as cast composites in range of solidification. The construction and operation characteristics were presented for the test stand including processing modules and probes together with thermocouples location. Authors presented examples of results interpretation for AlSi11 alloy castings with diversified wall thickness and at different pouring temperature.

  3. Complex surface concentration gradients by stenciled "electro click chemistry".

    Science.gov (United States)

    Hansen, Thomas S; Lind, Johan U; Daugaard, Anders E; Hvilsted, Søren; Andresen, Thomas L; Larsen, Niels B

    2010-10-19

    Complex one- or two-dimensional concentration gradients of alkynated molecules are produced on azidized conducting polymer substrates by stenciled "electro click chemistry". The latter describes the local electrochemical generation of catalytically active Cu(I) required to complete a "click reaction" between alkynes and azides at room temperature. A stencil on the counter electrode defines the shape and multiplicity of the gradient(s) on the conducting polymer substrate, while the specific reaction conditions control gradient steepness and the maximum concentration deposited. Biologically active ligands including cell binding peptides are patterned in gradients by this method without losing their biological function or the conductivity of the polymer.

  4. Regularized Multitask Learning for Multidimensional Log-Density Gradient Estimation.

    Science.gov (United States)

    Yamane, Ikko; Sasaki, Hiroaki; Sugiyama, Masashi

    2016-07-01

    Log-density gradient estimation is a fundamental statistical problem and possesses various practical applications such as clustering and measuring nongaussianity. A naive two-step approach of first estimating the density and then taking its log gradient is unreliable because an accurate density estimate does not necessarily lead to an accurate log-density gradient estimate. To cope with this problem, a method to directly estimate the log-density gradient without density estimation has been explored and demonstrated to work much better than the two-step method. The objective of this letter is to improve the performance of this direct method in multidimensional cases. Our idea is to regard the problem of log-density gradient estimation in each dimension as a task and apply regularized multitask learning to the direct log-density gradient estimator. We experimentally demonstrate the usefulness of the proposed multitask method in log-density gradient estimation and mode-seeking clustering.

  5. Gradient hydrogel coatings for medical applications

    Science.gov (United States)

    Chinnayan Kannan, Pandiyarajan; Genzer, Jan

    Mussel byssus is a typical example for gradient material that demonstrates a continues variation in mechanical property (or modulus), i . e . , soft (proximal) part is connected to mussel, while the stiffer (distal) part facilitates the attachment of mussel to a stone. Mimicking such materials is highly demanding especially in the areas of artificial implants. We developed a simple synthetic route to produce gradient hydrogels that are covalently anchored to the substrate. N-isopropylacrylamide has been copolymerized with 5 mole% of photo-active (methacrylyloxybenzophenone) and/or 5% of thermally-active (styrenesulfonylazide) crosslinkers. The incorporation of photo and/or thermal crosslinkers allows us for a complete control over the network properties in orthogonal directions. A systematic investigation towards the gel kinetics, swelling, crosslink density, elasticity and protein adsorption was performed. Our results instigate that weakly crosslinked (low modulus) gels swell strong in aqueous medium than the densely crosslinked (high modulus) gels. The results of protein adsorption are discussed based on the previously developed model entropic shielding and size exclusion effect.

  6. Asymmetric Uncertainty Expression for High Gradient Aerodynamics

    Science.gov (United States)

    Pinier, Jeremy T

    2012-01-01

    When the physics of the flow around an aircraft changes very abruptly either in time or space (e.g., flow separation/reattachment, boundary layer transition, unsteadiness, shocks, etc), the measurements that are performed in a simulated environment like a wind tunnel test or a computational simulation will most likely incorrectly predict the exact location of where (or when) the change in physics happens. There are many reasons for this, includ- ing the error introduced by simulating a real system at a smaller scale and at non-ideal conditions, or the error due to turbulence models in a computational simulation. The un- certainty analysis principles that have been developed and are being implemented today do not fully account for uncertainty in the knowledge of the location of abrupt physics changes or sharp gradients, leading to a potentially underestimated uncertainty in those areas. To address this problem, a new asymmetric aerodynamic uncertainty expression containing an extra term to account for a phase-uncertainty, the magnitude of which is emphasized in the high-gradient aerodynamic regions is proposed in this paper. Additionally, based on previous work, a method for dispersing aerodynamic data within asymmetric uncer- tainty bounds in a more realistic way has been developed for use within Monte Carlo-type analyses.

  7. The multigrid preconditioned conjugate gradient method

    Science.gov (United States)

    Tatebe, Osamu

    1993-01-01

    A multigrid preconditioned conjugate gradient method (MGCG method), which uses the multigrid method as a preconditioner of the PCG method, is proposed. The multigrid method has inherent high parallelism and improves convergence of long wavelength components, which is important in iterative methods. By using this method as a preconditioner of the PCG method, an efficient method with high parallelism and fast convergence is obtained. First, it is considered a necessary condition of the multigrid preconditioner in order to satisfy requirements of a preconditioner of the PCG method. Next numerical experiments show a behavior of the MGCG method and that the MGCG method is superior to both the ICCG method and the multigrid method in point of fast convergence and high parallelism. This fast convergence is understood in terms of the eigenvalue analysis of the preconditioned matrix. From this observation of the multigrid preconditioner, it is realized that the MGCG method converges in very few iterations and the multigrid preconditioner is a desirable preconditioner of the conjugate gradient method.

  8. Adaptive Gradient Multiobjective Particle Swarm Optimization.

    Science.gov (United States)

    Han, Honggui; Lu, Wei; Zhang, Lu; Qiao, Junfei

    2017-10-09

    An adaptive gradient multiobjective particle swarm optimization (AGMOPSO) algorithm, based on a multiobjective gradient (stocktickerMOG) method and a self-adaptive flight parameters mechanism, is developed to improve the computation performance in this paper. In this AGMOPSO algorithm, the stocktickerMOG method is devised to update the archive to improve the convergence speed and the local exploitation in the evolutionary process. Meanwhile, the self-adaptive flight parameters mechanism, according to the diversity information of the particles, is then established to balance the convergence and diversity of AGMOPSO. Attributed to the stocktickerMOG method and the self-adaptive flight parameters mechanism, this AGMOPSO algorithm not only has faster convergence speed and higher accuracy, but also its solutions have better diversity. Additionally, the convergence is discussed to confirm the prerequisite of any successful application of AGMOPSO. Finally, with regard to the computation performance, the proposed AGMOPSO algorithm is compared with some other multiobjective particle swarm optimization algorithms and two state-of-the-art multiobjective algorithms. The results demonstrate that the proposed AGMOPSO algorithm can find better spread of solutions and have faster convergence to the true Pareto-optimal front.

  9. Intergenerational and socioeconomic gradients of child obesity.

    Science.gov (United States)

    Costa-Font, Joan; Gil, Joan

    2013-09-01

    Can the rise in obesity among children be attributed to the intergenerational transmission of parental influences? Does this trend affect the influence of parent's socioeconomic status on obesity? This paper documents evidence of an emerging social gradient of obesity in pre-school children resulting from a combination of both socio-economic status and less intensive childcare associated with maternal employment, when different forms of intergenerational transmission are controlled for. We also estimate and decompose income related inequalities in child obesity. We take advantage of a uniquely constructed dataset from Spain that contains records form 13,358 individuals for a time period (years 2003-2006) in which a significant spike in the growth of child obesity was observed. Our results suggest robust evidence of both socioeconomic and intergenerational gradients. Results are suggestive of a high income effect in child obesity, alongside evidence that income inequalities have doubled in just three years with a pure income effect accounting for as much as 72-66% of these income inequality estimates, even when intergenerational transmission is accounted for. Although, intergenerational transmission does not appear to be gender specific, when accounted for, mother's labour market participation only explains obesity among boys but not among girls. Hence, it appears income and parental influences are the central determinants of obesity among children. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Temperature gradients assist carbohydrate allocation within trees.

    Science.gov (United States)

    Sperling, Or; Silva, Lucas C R; Tixier, Aude; Théroux-Rancourt, Guillaume; Zwieniecki, Maciej A

    2017-06-12

    Trees experience two distinct environments: thermally-variable air and thermally-buffered soil. This generates intra-tree temperature gradients, which can affect carbon metabolism and water transport. In this study, we investigated whether carbohydrate allocation within trees is assisted by temperature gradients. We studied pistachio (Pistacia integerrima) to determine: (1) temperature-induced variation in xylem sugar concentration in excised branches; (2) changes in carbon allocation in young trees under simulated spring and fall conditions; and (3) seasonal variability of starch levels in mature orchard trees under field conditions. We found that warm branches had less sugar in perfused sap than cold branches due to increasing parenchyma storage. Simulated spring conditions promoted allocation of carbohydrates from cold roots to warm canopy and explained why starch levels surged in canopies of orchard trees during early spring. This driving force of sugar transport is interrupted in fall when canopies are colder than roots and carbohydrate redistribution is compartmentalized. On the basis of these findings, we propose a new mechanistic model of temperature-assisted carbohydrate allocation that links environmental cues and tree phenology. This data-enabled model provides insights into thermal "fine-tuning" of carbohydrate metabolism and a warning that the physiological performance of trees might be impaired by climatic changes.

  11. GradientOptimizer: an open-source graphical environment for calculating optimized gradients in reversed-phase liquid chromatography.

    Science.gov (United States)

    Moruz, Luminita; Käll, Lukas

    2014-06-01

    We here present GradientOptimizer, an intuitive, lightweight graphical user interface to design nonlinear gradients for separation of peptides by reversed-phase liquid chromatography. The software allows to calculate three types of nonlinear gradients, each of them optimizing a certain retention time distribution of interest. GradientOptimizer is straightforward to use, requires minimum processing of the input files, and is supported under Windows, Linux, and OS X platforms. The software is open-source and can be downloaded under an Apache 2.0 license at https://github.com/statisticalbiotechnology/NonlinearGradientsUI. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Adaptive microfluidic gradient generator for quantitative chemotaxis experiments

    Science.gov (United States)

    Anielski, Alexander; Pfannes, Eva K. B.; Beta, Carsten

    2017-03-01

    Chemotactic motion in a chemical gradient is an essential cellular function that controls many processes in the living world. For a better understanding and more detailed modelling of the underlying mechanisms of chemotaxis, quantitative investigations in controlled environments are needed. We developed a setup that allows us to separately address the dependencies of the chemotactic motion on the average background concentration and on the gradient steepness of the chemoattractant. In particular, both the background concentration and the gradient steepness can be kept constant at the position of the cell while it moves along in the gradient direction. This is achieved by generating a well-defined chemoattractant gradient using flow photolysis. In this approach, the chemoattractant is released by a light-induced reaction from a caged precursor in a microfluidic flow chamber upstream of the cell. The flow photolysis approach is combined with an automated real-time cell tracker that determines changes in the cell position and triggers movement of the microscope stage such that the cell motion is compensated and the cell remains at the same position in the gradient profile. The gradient profile can be either determined experimentally using a caged fluorescent dye or may be alternatively determined by numerical solutions of the corresponding physical model. To demonstrate the function of this adaptive microfluidic gradient generator, we compare the chemotactic motion of Dictyostelium discoideum cells in a static gradient and in a gradient that adapts to the position of the moving cell.

  13. Ant functional responses along environmental gradients.

    Science.gov (United States)

    Arnan, Xavier; Cerdá, Xim; Retana, Javier

    2014-11-01

    Understanding species distributions and diversity gradients is a central challenge in ecology and requires prior knowledge of the functional traits mediating species' survival under particular environmental conditions. While the functional ecology of plants has been reasonably well explored, much less is known about that of animals. Ants are among the most diverse, abundant and ecologically significant organisms on earth, and they perform a great variety of ecological functions. In this study, we analyse how the functional species traits present in ant communities vary along broad gradients in climate, productivity and vegetation type in the south-western Mediterranean. To this end, we compiled one of the largest animal databases to date: it contains information on 211 local ant communities (including eight climate variables, productivity, and vegetation type) and 124 ant species, for which 10 functional traits are described. We used traits that characterize different dimensions of the ant functional niche with respect to morphology, life history and behaviour at both individual and colony level. We calculated two complementary functional trait community indices ('trait average' and 'trait dissimilarity') for each trait, and we analysed how they varied along the three different gradients using generalized least squares models that accounted for spatial autocorrelation. Our results show that productivity, vegetation type and, to a lesser extent, each climate variable per se might play an important role in shaping the occurrence of functional species traits in ant communities. Among the climate variables, temperature and precipitation seasonality had a much higher influence on functional responses than their mean values, whose effects were almost lacking. Our results suggest that strong relationships might exist between the abiotic environment and the distribution of functional traits among south-western Mediterranean ant communities. This finding indicates that

  14. cultivadas bajo un gradiente de sombra

    Directory of Open Access Journals (Sweden)

    Marco V. Gutiérrez

    2007-01-01

    Full Text Available Se evaluó el crecimiento de 9 especies de palmas cultivadas bajo un gradiente de sombra producido por mallas de polipropileno negro de 40, 50, 60, 70 y 80% de sombra, más un tratamiento de malla aluminizada de 70%, y uno con plantas a pleno sol. Las especies evaluadas fueron Caryota mitis (cola de pez, Chamaedorea costaricana (pacaya, Chamaedorea tepejilote (tepejilote, Dypsis lutescens (areca, Licuala elegans (licuala, Phoenix roebelenii (fénix, Ptychosperma macarthurii (palma macarthur, Roystonea regia (palma real, y Veitchia merrillii (navideña. Se midió la altura de las plantas, la longitud de las hojas maduras, y el número de hojas cosechadas, durante 5 cosechas por 2 años. En general, la altura de las plantas y la longitud de las hojas fueron menores a 0-40% de sombra, se incrementaron a 50-70%, y decrecieron a 80%. C. mitis, C. tepejilote, L. elegans y P. macarthurii, se comportaron como especies obligadas de sombra y no sobrevivieron a pleno sol. C. costaricana y D. lutescens sobrevivieron a plena exposición solar, y su crecimiento alcanzó valores máximos a 50-60%. P. roebelenii, R. regia, y V. merrillii mostraron un crecimiento reducido a 0-40%, pero éste mejoró bajo los demás niveles de sombra a lo largo del gradiente. En general, 1-2 años es un periodo apropiado para el cultivo de palmas de crecimiento rápido (R. regia, Chamedorea spp., D. lutescens en casas de mallas. Palmas de lento crecimiento (L.elegans pueden permanecer 3-5 años en una casa de sombra. Se discute estrategias para el uso de gradientes de sombra en el tiempo y en el espacio, según la utilidad y los requerimientos de las especies, los requisitos establecidos por el mercado, y el ciclo de producción del material vegetal.

  15. Advanced compositional gradient and compartmentalization analysis

    Energy Technology Data Exchange (ETDEWEB)

    Canas, Jesus A.; Petti, Daniela; Mullins, Oliver [Schlumberger Servicos de Petroleo Ltda., Rio de Janeiro, RJ (Brazil)

    2008-07-01

    Acquisition of hydrocarbons samples from the reservoir prior to oil or gas production is essential in order to design production strategies and production facilities. In addition, reservoir compartmentalization and hydrocarbon compositional grading magnify the necessity to map fluid properties vertically and laterally in the reservoir prior to production. Formation testers supply a wealth of information to observe and predict the state of fluids in hydrocarbon reservoirs, through detailed pressure and fluid analysis measurements. With the correct understanding of the state of fluids in the reservoirs, reserve calculations and adequate development plans can be prepared. Additionally, flow barriers may then be revealed. This paper describes a new Downhole Fluid Analysis technology (DFA) for improved reservoir management. DFA is a unique process that combines new fluid identification sensors, which allow real time monitoring of a wide range of parameters as GOR, fluid density, viscosity, fluorescence and composition (CH{sub 4}, C2- C5, C6 +, CO{sub 2}), free gas and liquid phases detection, saturation pressure, as well WBM and OBM filtrate differentiation and pH. This process is not limited to light fluid evaluation and we extended to heavy oil (HO) reservoirs analysis successfully. The combination of DFA Fluid Profiling with pressure measurements has shown to be very effective for compartmentalization characterization. The ability of thin barriers to hold off large depletion pressures has been established, as the gradual variation of hydrocarbon quality in biodegraded oils. In addition, heavy oils can show large compositional variation due to variations in source rock charging but without fluid mixing. Our findings indicates that steep gradients are common in gas condensates or volatile oils, and that biodegradation is more common in HO than in other hydrocarbons, which generate fluid gradients and heavy ends tars near the OWC, limiting the aquifer activity and

  16. Eigen-Gradients for Traffic Sign Recognition

    Directory of Open Access Journals (Sweden)

    Sheila Esmeralda Gonzalez-Reyna

    2013-01-01

    Full Text Available Traffic sign detection and recognition systems include a variety of applications like autonomous driving, road sign inventory, and driver support systems. Machine learning algorithms provide useful tools for traffic sign identification tasks. However, classification algorithms depend on the preprocessing stage to obtain high accuracy rates. This paper proposes a road sign characterization method based on oriented gradient maps and the Karhunen-Loeve transform in order to improve classification performance. Dimensionality reduction may be important for portable applications on resource constrained devices like FPGAs; therefore, our approach focuses on achieving a good classification accuracy by using a reduced amount of attributes compared to some state-of-the-art methods. The proposed method was tested using German Traffic Sign Recognition Benchmark, reaching a dimensionality reduction of 99.3% and a classification accuracy of 95.9% with a Multi-Layer Perceptron.

  17. Dynamic pulsed-field-gradient NMR

    CERN Document Server

    Sørland, Geir Humborstad

    2014-01-01

    Dealing with the basics, theory and applications of dynamic pulsed-field-gradient NMR NMR (PFG NMR), this book describes the essential theory behind diffusion in heterogeneous media that can be combined with NMR measurements to extract important information of the system being investigated. This information could be the surface to volume ratio, droplet size distribution in emulsions, brine profiles, fat content in food stuff, permeability/connectivity in porous materials and medical applications currently being developed. Besides theory and applications it will provide the readers with background knowledge on the experimental set-ups, and most important, deal with the pitfalls that are numerously present in work with PFG-NMR. How to analyze the NMR data and some important basic knowledge on the hardware will be explained, too.

  18. A fast, preconditioned conjugate gradient Toeplitz solver

    Science.gov (United States)

    Pan, Victor; Schrieber, Robert

    1989-01-01

    A simple factorization is given of an arbitrary hermitian, positive definite matrix in which the factors are well-conditioned, hermitian, and positive definite. In fact, given knowledge of the extreme eigenvalues of the original matrix A, an optimal improvement can be achieved, making the condition numbers of each of the two factors equal to the square root of the condition number of A. This technique is to applied to the solution of hermitian, positive definite Toeplitz systems. Large linear systems with hermitian, positive definite Toeplitz matrices arise in some signal processing applications. A stable fast algorithm is given for solving these systems that is based on the preconditioned conjugate gradient method. The algorithm exploits Toeplitz structure to reduce the cost of an iteration to O(n log n) by applying the fast Fourier Transform to compute matrix-vector products. Matrix factorization is used as a preconditioner.

  19. Error analysis of stochastic gradient descent ranking.

    Science.gov (United States)

    Chen, Hong; Tang, Yi; Li, Luoqing; Yuan, Yuan; Li, Xuelong; Tang, Yuanyan

    2013-06-01

    Ranking is always an important task in machine learning and information retrieval, e.g., collaborative filtering, recommender systems, drug discovery, etc. A kernel-based stochastic gradient descent algorithm with the least squares loss is proposed for ranking in this paper. The implementation of this algorithm is simple, and an expression of the solution is derived via a sampling operator and an integral operator. An explicit convergence rate for leaning a ranking function is given in terms of the suitable choices of the step size and the regularization parameter. The analysis technique used here is capacity independent and is novel in error analysis of ranking learning. Experimental results on real-world data have shown the effectiveness of the proposed algorithm in ranking tasks, which verifies the theoretical analysis in ranking error.

  20. Seismic Velocity Gradients Across the Transition Zone

    Science.gov (United States)

    Escalante, C.; Cammarano, F.; de Koker, N.; Piazzoni, A.; Wang, Y.; Marone, F.; Dalton, C.; Romanowicz, B.

    2006-12-01

    One-D elastic velocity models derived from mineral physics do a notoriously poor job at predicting the velocity gradients in the upper mantle transition zone, as well as some other features of models derived from seismological data. During the 2006 CIDER summer program, we computed Vs and Vp velocity profiles in the upper mantle based on three different mineral physics approaches: two approaches based on the minimization of Gibbs Free Energy (Stixrude and Lithgow-Bertelloni, 2005; Piazzoni et al., 2006) and one obtained by using experimentally determined phase diagrams (Weidner and Wang, 1998). The profiles were compared by assuming a vertical temperature profile and two end-member compositional models, the pyrolite model of Ringwood (1979) and the piclogite model of Anderson and Bass (1984). The predicted seismic profiles, which are significantly different from each other, primarily due to different choices of properties of single minerals and their extrapolation with temperature, are tested against a global dataset of P and S travel times and spheroidal and toroidal normal mode eigenfrequencies. All the models derived using a potential temperature of 1600K predict seismic velocities that are too slow in the upper mantle, suggesting the need to use a colder geotherm. The velocity gradient in the transition zone is somewhat better for piclogite than for pyrolite, possibly indicating the need to increase Ca content. The presence of stagnant slabs in the transition zone is a possible explanation for the need for 1) colder temperature and 2) increased Ca content. Future improvements in seismic profiles obtained from mineral physics will arise from better knowledge of elastic properties of upper mantle constituents and aggregates at high temperature and pressure, a better understanding of differences between thermodynamic models, and possibly the effect of water through and on Q. High resolution seismic constraints on velocity jumps at 400 and 660 km also need to be