WorldWideScience

Sample records for site constrained hydrogen

  1. A comparative economic assessment of hydrogen production from large central versus smaller distributed plant in a carbon constrained world

    International Nuclear Information System (INIS)

    Nguyen, Y.V.; Ngo, Y.A.; Tinkler, M.J.; Cowan, N.

    2003-01-01

    This paper compares the economics of producing hydrogen at large central plants versus smaller distributed plants at user sites. The economics of two types of central plant, each at 100 million standard cubic feet per day of hydrogen, based on electrolysis and natural gas steam reforming technologies, will be discussed. The additional cost of controlling CO 2 emissions from the natural gas steam reforming plant will be included in the analysis in order to satisfy the need to live in a future carbon constrained world. The cost of delivery of hydrogen from the large central plant to the user sites in a large metropolitan area will be highlighted, and the delivered cost will be compared to the cost from on-site distributed generation plants. Five types of distributed generation plants, based on proton exchange membrane, alkaline electrolysis and advanced steam reforming, will be analysed and discussed. Two criteria were used to rank various hydrogen production options, the cost of production and the price of hydrogen to achieve an acceptable return of investment. (author)

  2. Anomalous ortho-para conversion of solid hydrogen in constrained geometries

    International Nuclear Information System (INIS)

    Rall, M.; Brison, J.P.; Sullivan, N.S.

    1991-01-01

    Using cw NMR techniques, we have measured the ortho-para conversion of solid hydrogen constrained to the interior of the molecular cages of zeolite. The conversion observed in the constrained geometry is very different from that of bulk solid hydrogen. Two distinct conversion rates were observed for short and long times. An apparently bimolecular conversion rate of 0.43% h -1 (one-fourth of the bulk value) dominates during the first 500 h, and the rate then increases to 2.2% h -1 . The initial slow rate is explained in terms of a reduced number of nearest neighbors and possible wall effects, and the fast rate is attributed to the formation of small ortho-H 2 Rclusters at later times. Surface effects due to magnetic impurities do not appear to determine the conversion rate in the samples studied

  3. Constraining Born-Infeld-like nonlinear electrodynamics using hydrogen's ionization energy

    Energy Technology Data Exchange (ETDEWEB)

    Akmansoy, P.N. [Universidade Federal do Rio Grande do Norte, Departamento de Fisica Teorica e Experimental, Natal (Brazil); Medeiros, L.G. [Universidade Estadual Paulista, Instituto de Fisica Teorica, Sao Paulo, SP (Brazil); Universidade Federal do Rio Grande do Norte, Escola de Ciencia e Tecnologia, Natal, RN (Brazil)

    2018-02-15

    In this work, the hydrogen's ionization energy was used to constrain the free parameter b of three Born-Infeld-like electrodynamics namely Born-Infeld itself, Logarithmic electrodynamics and Exponential electrodynamics. An analytical methodology capable of calculating the hydrogen ground state energy level correction for a generic nonlinear electrodynamics was developed. Using the experimental uncertainty in the ground state energy of the hydrogen atom, the bound b > 5.37 x 10{sup 20}K(V)/(m), where K = 2, 4√(2)/3 and √(π) for the Born-Infeld, Logarithmic and Exponential electrodynamics respectively, was established. In the particular case of Born-Infeld electrodynamics, the constraint found for b was compared with other constraints present in the literature. (orig.)

  4. Regional Consumer Hydrogen Demand and Optimal Hydrogen Refueling Station Siting

    Energy Technology Data Exchange (ETDEWEB)

    Melendez, M.; Milbrandt, A.

    2008-04-01

    Using a GIS approach to spatially analyze key attributes affecting hydrogen market transformation, this study proposes hypothetical hydrogen refueling station locations in select subregions to demonstrate a method for determining station locations based on geographic criteria.

  5. Hydrogen production from small hyropower sites. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1980-04-01

    A synergistic relationship was not found to exist between low-head hydropower and electrolytic hydrogen production. The storageability of hydrogen was expected to mitigate problems of hydrogen generation variability associated with the use of low-head hydropower as the power source. The expense of gaseous hydrogen storage equipment effectively eliminates storage as a means to decouple hydrogen demand and power/hydrogen production. From the opposite perspective, the availability of a low and stable cost of power from low-head hydro was expected to improve the competitiveness of electrolysis. In actuality, the results indicated that hydroelectric power from small dams would be comparatively expensive by current grid power standards (mid-1979). Electrolysis, in the capacity range considered here, is less sensitive to the cost of the power than originally presumed. Other costs including depreciation and capital related charges are more significant. Due to power generation variability, sole reliance on low-head hydropower to provide electricity to the cells would reduce the utilization of the hydrogen production investment, resulting in an increase in unit production costs. These factors were paramount in the Air Products recommendation to discontinue the study before continuing to more detailed stages of analysis, including an analysis of a site specific facility and the construction of a demonstration facility. Another major factor was the unavailability of a pipeline hydrogen supply situation which, because of lower distribution and capital costs, could have been commercially viable. An unfavorable judgment on the combined facility should not be misinterpreted and extended to the component systems. Although a detailed analysis of the individual prospects for electrolysis and low-head hydropower was beyond the study scope, the reader will realize, as the study is reviewed, that each is worthy of individual consideration.

  6. Intracrystalline site preference of hydrogen isotopes in borax

    International Nuclear Information System (INIS)

    Pradhananga, T.M.; Matsuo, S.

    1985-01-01

    The total hydrogen involved in borax synthesized at 25 0 C in aqueous solution is enriched in deuterium by 5.3% compared with the mother liquor. There is no change in the value of the D/H fractionation factor between the hydrogen in borax and those in the mother liquor with changes in the degree of supersaturation. The fractionation factor changes slightly with a change in the crystallization temperature of borax in the range from 5 to 25 0 C. The D/H ratio in the different sites of borax was estimated by a fractional dehydration technique. The results show that hydrogen atoms of the polyanionic group [B 4 O 5 (OH) 4 ] are much more enriched in deuterium than those of the cationic group [Na 2 x 8H 2 O]. The delta D values, referred to the mother liquor from which the borax was crystallized, for the cationic group (site A) and the polyanionic group (site B) are -35 +/- 3 and 167 +/- 13%, respectively based on the fractional dehydration results obtained at -21 0 C. At -21 0 C, isotopic exchange between different sites during dehydration is assumed not to occur. The mechanism for dehydration of borax is discussed. 48 references, 8 figures, 3 tables

  7. Site-Specific Hydrogen Isotope Composition of Propane: Mass spectrometric methods, equilibrium temperature dependence, and kinetics of exchange

    Science.gov (United States)

    Xie, H.; Ponton, C.; Kitchen, N.; Lloyd, M. K.; Lawson, M.; Formolo, M. J.; Eiler, J. M.

    2016-12-01

    Intramolecular isotope ordering can constrain temperatures of synthesis, mechanisms of formation, and/or source substrates of organic compounds. Here we explore site-specific hydrogen isotope variations of propane. Statistical thermodynamic models predict that at equilibrium methylene hydrogen (-CH2-) in propane will be 10's of per mil higher in D/H ratio than methyl hydrogen (-CH3) at geologically relevant temperatures, and that this difference is highly temperature dependent ( 0.5-1 ‰/°C). Chemical-kinetic controls on site-specific D/H in propane could constrain the mechanisms, conditions and extents of propane synthesis or destruction. We have developed a method for measuring the difference in D/H ratio between methylene and methyl hydrogen in propane by gas source mass spectrometry. The data were measured using the Thermo Fisher Double Focusing Sector high resolution mass spectrometer (DFS), and involve comparison of the D/H ratios of molecular ion (C3H8+) and the ethyl fragmental ion (C2H5+). We demonstrate the accuracy and precision of this method through analysis of D-labeled and independently analyzed propanes. In the exchange experiments, propane was heated (100-200 oC) either alone or in the presence of D-enriched water (δD=1,1419 ‰ SMOW), with or without one of several potentially catalytic substrates for hours to weeks. Propane was found to exchange hydrogen with water vigorously at 200 °C in the presence of metal catalysts. In the presence of Ni catalyst, methylene hydrogen exchanges 2.5 times faster than methyl hydrogen. Hydrogen exchange in the presence of Pd catalyst is more effective and can equilibrate hydrogen isotope distribution on propane on the order of 7 days. Isotopic exchange in the presence of natural materials have also been tested, but is only measurable in the methylene group at 200 °C. High catalytic activity of Pd permits attainment of a bracketed, time-invariant equilibrium state that we use to calibrate the site

  8. Hydrogen isotope separation experience at the Savannah River Site

    International Nuclear Information System (INIS)

    Lee, M.W.

    1993-01-01

    Savannah River Site (SRS) is a sole producer of tritium for US Weapons Program. SRS has built Facilities, developed the tritium handling processes, and operated safely for the last forty years. Tritium is extracted from the irradiated reactor target, purified, mixed with deuterium, and loaded to the booster gas bottle in the weapon system for limited lifetime. Tritium is recovered from the retired bottle and recycled. Newly produced tritium is branded into the recycled tritium. One of the key process is the hydrogen isotope separation that tritium is separated from deuterium and protium. Several processes have been used for the hydrogen isotope separation at SRS: Thermal Diffusion Column (TD), Batch Cryogenic Still (CS), and Batch Chromatography called Fractional Sorption (FS). TD and CS requires straight vertical columns. The overall system separation factor depends on the length of the column. These are three story building high and difficult to put in glove box. FS is a batch process and slow operation. An improved continuous chromatographic process called Thermal Cycling Absorption Process (TCAP) has been developed. It is small enough to be about to put in a glove box yet high capacity comparable to CS. The SRS tritium purification processes can be directly applicable to the Fusion Fuel Cycle System of the fusion reactor

  9. Constraining climate change with nuclear electricity and hydrogen (N + H2)

    International Nuclear Information System (INIS)

    Miller, A.I.; Duffey, R.B.

    2003-08-01

    Electricity produced from non-carbon-based sources is the only available technology to curb the rise of CO 2 levels in the Earth's atmosphere. While it is comparatively easy to replace carbon-fuelled electricity production with nuclear and other non-carbon sources, electricity will also have to penetrate deeply into transportation to achieve sufficient leverage to displace existing carbon-based energy use. The use of hydrogen, produced by water electrolysis, resolves the intractability of on-board storage of electricity, and provides a distributed source. This paper first reviews the scenarios for future energy use and supply created by the Intergovernmental Panel on Climate Change (IPCC), which are also representative of the main IAEA/NEA scenarios. It then discusses ways in which non-carbon-based energy can be applied to the transportation sector in the form of hydrogen. Finally, the potential effects of this application have been calculated for the key IPCC marker scenarios using the MAGICC-SCENGEN software package. A mechanism inherent in the model can provide quite accurate prediction of the effect of CO 2 concentration on global temperatures 20 years later. This provides a useful and new way to estimate the effects of delayed action to reduce CO 2 emissions. The IPCC's scenarios already include considerable expansion of energy from nuclear and other sustainable energy sources (e.g. wind, solar, biomass), but the extent is generally too small to substantially restrain the build-up of greenhouse gases in the Earth's atmosphere and to diminish the consequent projected rate of rise of average global temperatures. Much greater substitution is needed, and this paper argues that only nuclear power can provide the preponderant source of energy for a sufficient and sustainable switch away from carbon. Though the storage of spent-fuel wastes is now developed technology, waste disposal is often cited as a constraint on nuclear power. It is a strange objection given that

  10. Constraining climate change with nuclear electricity and hydrogen (N + H{sub 2})

    Energy Technology Data Exchange (ETDEWEB)

    Miller, A.I.; Duffey, R.B

    2003-08-01

    Electricity produced from non-carbon-based sources is the only available technology to curb the rise of CO{sub 2} levels in the Earth's atmosphere. While it is comparatively easy to replace carbon-fuelled electricity production with nuclear and other non-carbon sources, electricity will also have to penetrate deeply into transportation to achieve sufficient leverage to displace existing carbon-based energy use. The use of hydrogen, produced by water electrolysis, resolves the intractability of on-board storage of electricity, and provides a distributed source. This paper first reviews the scenarios for future energy use and supply created by the Intergovernmental Panel on Climate Change (IPCC), which are also representative of the main IAEA/NEA scenarios. It then discusses ways in which non-carbon-based energy can be applied to the transportation sector in the form of hydrogen. Finally, the potential effects of this application have been calculated for the key IPCC marker scenarios using the MAGICC-SCENGEN software package. A mechanism inherent in the model can provide quite accurate prediction of the effect of CO{sub 2} concentration on global temperatures 20 years later. This provides a useful and new way to estimate the effects of delayed action to reduce CO{sub 2} emissions. The IPCC's scenarios already include considerable expansion of energy from nuclear and other sustainable energy sources (e.g. wind, solar, biomass), but the extent is generally too small to substantially restrain the build-up of greenhouse gases in the Earth's atmosphere and to diminish the consequent projected rate of rise of average global temperatures. Much greater substitution is needed, and this paper argues that only nuclear power can provide the preponderant source of energy for a sufficient and sustainable switch away from carbon. Though the storage of spent-fuel wastes is now developed technology, waste disposal is often cited as a constraint on nuclear power. It is

  11. Constraining the Type Ia Supernova Progenitor: The Search for Hydrogen in Nebular Spectra

    Science.gov (United States)

    Leonard, Douglas C.

    2007-12-01

    Despite intense scrutiny, the progenitor system(s) that gives rise to Type Ia supernovae remains unknown. The favored theory invokes a carbon-oxygen white dwarf accreting hydrogen-rich material from a close companion until a thermonuclear runaway ensues that incinerates the white dwarf. However, simulations resulting from this single-degenerate, binary channel demand the presence of low-velocity Hα emission in spectra taken during the late nebular phase, since a portion of the companion's envelope becomes entrained in the ejecta. This hydrogen has never been detected, but has only rarely been sought. Here we present results from a campaign to obtain deep, nebular-phase spectroscopy of nearby Type Ia supernovae, and include multiepoch observations of two events: SN 2005am (slightly subluminous) and SN 2005cf (normally bright). No Hα emission is detected in the spectra of either object. An upper limit of 0.01 Msolar of solar abundance material in the ejecta is established from the models of Mattila et al., which, when coupled with the mass-stripping simulations of Marietta et al. and Meng et al., effectively rules out progenitor systems for these supernovae with secondaries close enough to the white dwarf to be experiencing Roche lobe overflow at the time of explosion. Alternative explanations for the absence of Hα emission, along with suggestions for future investigations necessary to confidently exclude them as possibilities, are critically evaluated. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Additional observations were obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a

  12. Constraining climate change with nuclear electricity and hydrogen (N + H{sub 2})

    Energy Technology Data Exchange (ETDEWEB)

    Miller, A I; Duffey, R B

    2003-08-01

    Electricity produced from non-carbon-based sources is the only available technology to curb the rise of CO{sub 2} levels in the Earth's atmosphere. While it is comparatively easy to replace carbon-fuelled electricity production with nuclear and other non-carbon sources, electricity will also have to penetrate deeply into transportation to achieve sufficient leverage to displace existing carbon-based energy use. The use of hydrogen, produced by water electrolysis, resolves the intractability of on-board storage of electricity, and provides a distributed source. This paper first reviews the scenarios for future energy use and supply created by the Intergovernmental Panel on Climate Change (IPCC), which are also representative of the main IAEA/NEA scenarios. It then discusses ways in which non-carbon-based energy can be applied to the transportation sector in the form of hydrogen. Finally, the potential effects of this application have been calculated for the key IPCC marker scenarios using the MAGICC-SCENGEN software package. A mechanism inherent in the model can provide quite accurate prediction of the effect of CO{sub 2} concentration on global temperatures 20 years later. This provides a useful and new way to estimate the effects of delayed action to reduce CO{sub 2} emissions. The IPCC's scenarios already include considerable expansion of energy from nuclear and other sustainable energy sources (e.g. wind, solar, biomass), but the extent is generally too small to substantially restrain the build-up of greenhouse gases in the Earth's atmosphere and to diminish the consequent projected rate of rise of average global temperatures. Much greater substitution is needed, and this paper argues that only nuclear power can provide the preponderant source of energy for a sufficient and sustainable switch away from carbon. Though the storage of spent-fuel wastes is now developed technology, waste disposal is often cited as a constraint on nuclear power. It is a strange

  13. Comparison of conventional vs. modular hydrogen refueling stations and on-site production vs. delivery.

    Energy Technology Data Exchange (ETDEWEB)

    Hecht, Ethan S. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Pratt, Joseph William [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2017-03-01

    To meet the needs of public and private stakeholders involved in the development, construction, and operation of hydrogen fueling stations needed to support the widespread roll-out of hydrogen fuel cell electric vehicles, this work presents publicly available station templates and analyses. These ‘Reference Stations’ help reduce the cost and speed the deployment of hydrogen stations by providing a common baseline with which to start a design, enable quick assessment of potential sites for a hydrogen station, identify contributors to poor economics, and suggest areas of research. This work presents layouts, bills of materials, piping and instrumentation diagrams, and detailed analyses of five new station designs. In the near term, delivered hydrogen results in a lower cost of hydrogen compared to on-site production via steam methane reforming or electrolysis, although the on-site production methods have other advantages. Modular station concepts including on-site production can reduce lot sizes from conventional assemble-on-site stations.

  14. Solid hydrogen and deuterium. I. Ground-state energy calculated by a lowest order constrained-variation method

    International Nuclear Information System (INIS)

    Pettersen, G.; Oestgaard, E.

    1988-01-01

    The ground-state energy of solid hydrogen and deuterium is calculated by means of a modified variational lowest order constrained-variation (LOCV) method. Both fcc and hcp H 2 and D 2 are considered, and the calculations are done for five different two-body potentials. For solid H 2 we obtain theoretical results for the ground-state binding energy per particle from -74.9 K at an equilibrium particle density of 0.700 σ -3 or a molar volume of 22.3 cm 3 /mole to -91.3 K at a particle density of 0.725 σ -3 or a molar volume of 21.5 cm 3 /mole, where σ = 2.958 A. The corresponding experimental result is -92.3 K at a particle density of 0.688 σ -3 or a molar volume of 22.7 cm 3 /mole. For solid D 2 we obtain theoretical results for the ground-state binding energy per particle from -125.7 K at an equilibrium particle density of 0.830 σ -3 or a molar volume of 18.8 cm 3 /mole to -140.1 K at a particle density of 0.843 σ -3 or a molar volume of 18.5 cm 3 /mole. The corresponding experimental result is -137.9 K at a particle density of 0.797 σ -3 or a molar volume of 19.6 cm 3 /mole

  15. Constraining groundwater flow model with geochemistry in the FUA and Cabril sites. Use in the ENRESA 2000 PA exercise

    International Nuclear Information System (INIS)

    Samper, J.; Carrera, J.; Bajos, C.; Astudillo, J.; Santiago, J.L.

    1999-01-01

    Hydrogeochemical activities have been a key factor for the verification and constraining of the groundwater flow model developed for the safety assessment of the FUA Uranium mill tailings restoration and the Cabril L/ILW disposal facility. The lesson learned in both sites will be applied to the ground water transport modelling in the current PA exercises (ENRESA 2000). The groundwater flow model in the Cabril site, represents a low permeability fractured media, and was performed using the TRANSIN code series developed by UPC-ENRESA. The hydrogeochemical data obtained from systematic yearly sampling and analysis campaigns were successfully applied to distinguish between local and regional flow and young and old groundwater. The salinity content, mainly the chlorine anion content, was the most critical hydrogeochemical data for constraining the groundwater flow model. (author)

  16. Sulfur tolerance of Pt/mordenites for benzene hydrogenation. Do Bronsted acid sites participate in hydrogenation?

    NARCIS (Netherlands)

    Simon, L.; van Ommen, J.G.; Jentys, A.; Lercher, J.A.

    2002-01-01

    The comparison of Pt electronic properties studied by in situ XANES and the kinetic study of benzene hydrogenation strongly suggests that the hydrogenation of benzene on Pt/mordenites occurs along two parallel reaction pathways. The routes proposed include (i) the monofunctional hydrogenation of

  17. Heat of solution and site energies of hydrogen in disordered transition-metal alloys

    International Nuclear Information System (INIS)

    Brouwer, R.C.; Griessen, R.

    1989-01-01

    Site energies, long-range effective hydrogen-hydrogen interactions, and the enthalpy of solution in transition-metal alloys are calculated by means of an embedded-cluster model. The energy of a hydrogen atom is assumed to be predominantly determined by the first shell of neighboring metal atoms. The semiempirical local band-structure model is used to calculate the energy of the hydrogen atoms in the cluster, taking into account local deviations from the average lattice constant. The increase in the solubility limit and the weak dependence of the enthalpy of solution on hydrogen concentration in disordered alloys are discussed. Calculated site energies and enthalpies of solution in the alloys are compared with experimental data, and good agreement is found. Due to the strong interactions with the nearest-neighbor metal atoms, hydrogen atoms can be used to determine local lattice separations and the extent of short-range order in ''disordered'' alloys

  18. Relationship between hydrogen-induced phase transformations and pitting nucleation sites in duplex stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Liqiu; Yang, Binjie; Qin, Sixiao [University of Science and Technology Beijing (China). Corrosion and Protection Center

    2016-02-15

    This paper demonstrates the hydrogen-induced phase transformation and the associated pitting nucleation sites of 2507 duplex stainless steel using scanning Kelvin probe force microscopy and magnetic force microscopy. The low potential sites in Volta potential images, which are considered as the pitting nucleation sites, are strongly dependent on the hydrogen-induced phase transformation. They firstly initiate on the magnetic martensite laths in the austenite phase or at the ferrite/austenite boundaries, and then appear near the needle-shaped microtwins in the ferrite phase, because of the difference in physicochemical properties of hydrogen-induced phase transformation microstructures.

  19. What Would It Take for an Atmospheric Neutrino Detector to Constrain the Hydrogen Content of the Earth's Core ?

    Science.gov (United States)

    Bourret, S.; Coelho, J. A. B.; Kaminski, E. C.; Van Elewyck, V.

    2017-12-01

    The difference between PREM density and seismic profiles in the Earth's core and the values for pure iron and iron-nickel alloys inferred from high pressure/high temperature experiments and ab initio calculations requires the presence of a few wt% of light elements. The nature and amount of these light elements (O, Si, S, H, C...) remains controversial. Recent studies have renewed the interest in H. It is the most abundant element in the nebula and can be easily dissolved in iron in the early stages of Earth's evolution. 1 to 2 wt% of H could explain the difference between PREM and pure iron. However, current geophysical methods alone cannot settle the debate between H and the other candidate elements. Neutrino oscillation tomography using atmospheric neutrinos opens an avenue to collect independent data on Earth's core composition. This method exploits the quantum phenomenon of neutrino flavour oscillations, which depends on the electron density along the path of the neutrino through the Earth. The combination of a neutrino-based measurement of the electron density with the PREM mass density profile constrains the average proton-to-nucleon ratio of the medium (Z/A). Since this parameter varies among chemical elements, e.g. 0.466 for Fe and 1 for H, this technique has the potential to provide unprecedented insights into the chemical composition of the core, and in particular its hydrogen content. Performing such a measurement requires large-size detectors with good efficiency in the relevant energy range and precise determination of the neutrino energy, arrival direction, and flavour. Considering a generic but realistic model of detector response, we quantify the influence of various detector performance indicators on the sensitivity to the average Z/A in the core. We further evaluate the impact of systematic uncertainties, such as those related to the physical model for neutrino oscillations and the incoming flux of atmospheric neutrinos. We consider specific

  20. Management of Ground and Groundwater Contamination on a Compact Site Constrained by Ongoing Activities

    International Nuclear Information System (INIS)

    Eilbeck, K.E.; Reeve, P.

    2009-01-01

    Sellafield Site is a compact and complex site which since the 1940's has been home to a range of facilities associated with the production and reprocessing of fissile material. The site contains the UK equivalent of the Chicago Pile-1 reactor, Hanford B Reactor, Rocky Flats Buildings 771 and 774, West Valley Main Process Plant Building, Savannah River Vitrification Plant, Savannah River MOX Plant, Savannah River F Canyon, Hanford 222 Analytical Laboratory, Savannah River K-, L-, and P-Basins, and the Fort St. Vrain Reactor all in an area of approximately 1000 acres. Spent fuel reprocessing is still undertaken on site; however waste management and decommissioning activities are of increasing importance. These include the emptying and removal of fragile ponds and silos containing significant radioactive inventories, the decommissioning of reactors (including the world's first commercial reactor for power generation and the Windscale Piles, the site of a reactor fire in the late 1950's) and the construction of a new generation of vitrification and encapsulation plants. Leaks, spills and on-site disposals during the site's industrial lifetime have resulted in a legacy of fission products and other radionuclides in the ground and groundwater. Volumes of contaminated ground have been estimated as being as much as 18 million m 3 and an estimated below ground inventory of approximately 1.8 E16 Bq. These have all occurred within close proximity to a range of receptors including farm land and the sea. The cramped nature of the facilities on site, overlapping source terms and ongoing decommissioning, waste management and operating activities all raise significant challenges in the management and remediation of contaminated land and groundwater. The strategy to address these challenges includes: 1. Data collection, management and interpretation. The congested nature of the site and the age of some of the monitoring facilities has resulted in particular difficulties. For

  1. Hydrogen solution in tetrahedral or octahedral interstitial sites in Al

    International Nuclear Information System (INIS)

    Zeng, C.A.; Hu, J.P.; Ouyang, C.Y.

    2011-01-01

    Highlights: → The physical nature of the site preference for H solution in BCC Al is revealed. → The site preference is result of competition between Al-H bonding interaction and local lattice distortion. → The Al-H bonding interaction lowers the solution energy while the local lattice distortion increases the solution energy. - Abstract: It is reported that H atoms prefer to stay at interstitial (defect) sites with larger space in most metals. However, H atom prefers to occupy tetrahedral interstitial sites (T-site) that provide smaller space than octahedral sites (O-site) in Al. This paper studied the H-Al interactions from first principles calculations. Through analysis of the H-induced electronic states and the local atomic relaxations, we show that H-Al bonding interaction is stronger for T-site H, which is in favor of the solution energy. On the other hand, larger local atomic distortion is observed around the T-site H, which increases the total energy.

  2. Age of a prehistoric "Rodedian" cult site constrained by sediment and rock surface luminescence dating techniques

    DEFF Research Database (Denmark)

    Sohbati, Reza; Murray, Andrew; Porat, N.

    2015-01-01

    The construction age of a pavement in a “Rodedian” prehistoric cult site in Negev desert, Israel, is established by determining the burial age of (i) a cobble used in the pavement, and (ii) the underlying sediment. The quartz OSL age and the K-feldspar corrected IR50 age from the sediment...

  3. Intracrystalline site preference of hydrogen isotopes in the water of crystallization of copper sulfate pentahydrate

    International Nuclear Information System (INIS)

    Kita, I.; Matsuo, S.

    1981-01-01

    Difference in the isotopic partition at different sites of the water of crystallization of CuSO 4 .5H 2 O (the site preference) was estimated for the hydrogen isotopes. Fractional dehydration of CuSO 4 .5H 2 O under vacuum at 0 and 25 0 C was used to determine the isotopic ratio, the amount of dehydrated water, and the rate process of dehydration. The following results were obtained. (1) Two maxima occur in the isotopic ratio in the dehydration range, F < 0.8. (2) The dehydration occurs by the three sequential zeroth-order rate processes which have different rate constants for dehydration. The three different rate constants may be explained by the combination of the rate constants of dehydration of the water molecules dehydrated. The estimation of the difference in hydrogen isotope distribution for different sites, i.e., four of the five water molecules in the coordination sphere of copper ion (site A) and one bonded to the sulfate ion through hydrogen bonding (site B) was made. The site preference of hydrogen isotopes (delta D,%) was concluded to be -3.20 +- 0.52 for site A and +2.26 +- 2.09 for site B, where the delta D value was referred to the isotopic ratio of the mother liquor from which the crystal was formed

  4. Intracrystalline site preference of hydrogen isotopes in the water of crystallization of copper sulfate pentahydrate

    Energy Technology Data Exchange (ETDEWEB)

    Kita, I.; Matsuo, S.

    1981-04-02

    Difference in the isotopic partition at different sites of the water of crystallization of CuSO/sub 4/.5H/sub 2/O (the site preference) was estimated for the hydrogen isotopes. Fractional dehydration of CuSO/sub 4/.5H/sub 2/O under vacuum at 0 and 25/sup 0/C was used to determine the isotopic ratio, the amount of dehydrated water, and the rate process of dehydration. The following results were obtained. (1) Two maxima occur in the isotopic ratio in the dehydration range, F < 0.8. (2) The dehydration occurs by the three sequential zeroth-order rate processes which have different rate constants for dehydration. The three different rate constants may be explained by the combination of the rate constants of dehydration of the water molecules dehydrated. The estimation of the difference in hydrogen isotope distribution for different sites, i.e., four of the five water molecules in the coordination sphere of copper ion (site A) and one bonded to the sulfate ion through hydrogen bonding (site B) was made. The site preference of hydrogen isotopes (delta D,%) was concluded to be -3.20 +- 0.52 for site A and +2.26 +- 2.09 for site B, where the delta D value was referred to the isotopic ratio of the mother liquor from which the crystal was formed.

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

    Energy Technology Data Exchange (ETDEWEB)

    Torres, Marta [Oregon State Univ., Corvallis, OR (United States). College of Earth, Ocean, and Atmospheric Sciences

    2014-01-31

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

  6. Hydrogenation active sites of unsupported molybdenum sulfide catalysts for hydroprocessing heavy oils

    Energy Technology Data Exchange (ETDEWEB)

    Iwata, Y.; Araki, Y.; Honna, K. [Tsukuba-branch, Advanced Catalyst Research Laboratory, Petroleum Energy Center, 1-1 Higashi, Tsukuba, 305-8565 Ibaraki (Japan); Miki, Y.; Sato, K.; Shimada, H. [National Institute of Materials and Chemical Research, 1-1 Higashi, Tsukuba, 305-8565 Ibaraki (Japan)

    2001-02-20

    The purpose of the present study was to elucidate the nature of the hydrogenation active sites on unsupported molybdenum sulfide catalysts, aimed at the improvement of the catalysts for the slurry processes. The number of hydrogenation active sites was found to relate to the 'inflection' on the basal plane of the catalyst particles. The comparison of the catalytic activity to that of an oil-soluble catalyst in the hydroprocessing of heavy oils suggests that the performance of the oil-soluble catalyst was near the maximum, unless another component such as Ni or Co was incorporated.

  7. Single-site catalyst promoters accelerate metal-catalyzed nitroarene hydrogenation

    KAUST Repository

    Wang, Liang

    2018-04-04

    Atomically dispersed supported metal catalysts are drawing wide attention because of the opportunities they offer for new catalytic properties combined with efficient use of the metals. We extend this class of materials to catalysts that incorporate atomically dispersed metal atoms as promoters. The catalysts are used for the challenging nitroarene hydrogenation and found to have both high activity and selectivity. The promoters are single-site Sn on TiO2 supports that incorporate metal nanoparticle catalysts. Represented as M/Sn-TiO2 (M = Au, Ru, Pt, Ni), these catalysts decidedly outperform the unpromoted supported metals, even for hydrogenation of nitroarenes substituted with various reducible groups. The high activity and selectivity of these catalysts result from the creation of oxygen vacancies on the TiO2 surface by single-site Sn, which leads to efficient, selective activation of the nitro group coupled with a reaction involving hydrogen atoms activated on metal nanoparticles.

  8. Single-site catalyst promoters accelerate metal-catalyzed nitroarene hydrogenation

    KAUST Repository

    Wang, Liang; Guan, Erjia; Zhang, Jian; Yang, Junhao; Zhu, Yihan; Han, Yu; Yang, Ming; Cen, Cheng; Fu, Gang; Gates, Bruce C.; Xiao, Feng-Shou

    2018-01-01

    Atomically dispersed supported metal catalysts are drawing wide attention because of the opportunities they offer for new catalytic properties combined with efficient use of the metals. We extend this class of materials to catalysts that incorporate atomically dispersed metal atoms as promoters. The catalysts are used for the challenging nitroarene hydrogenation and found to have both high activity and selectivity. The promoters are single-site Sn on TiO2 supports that incorporate metal nanoparticle catalysts. Represented as M/Sn-TiO2 (M = Au, Ru, Pt, Ni), these catalysts decidedly outperform the unpromoted supported metals, even for hydrogenation of nitroarenes substituted with various reducible groups. The high activity and selectivity of these catalysts result from the creation of oxygen vacancies on the TiO2 surface by single-site Sn, which leads to efficient, selective activation of the nitro group coupled with a reaction involving hydrogen atoms activated on metal nanoparticles.

  9. Foraging habitat quality constrains effectiveness of artificial nest-site provisioning in reversing population declines in a colonial cavity nester.

    Directory of Open Access Journals (Sweden)

    Inês Catry

    Full Text Available Among birds, breeding numbers are mainly limited by two resources of major importance: food supply and nest-site availability. Here, we investigated how differences in land-use and nest-site availability affected the foraging behaviour, breeding success and population trends of the colonial cavity-dependent lesser kestrel Falco naumanni inhabiting two protected areas. Both areas were provided with artificial nests to increase nest-site availability. The first area is a pseudo-steppe characterized by traditional extensive cereal cultivation, whereas the second area is a previous agricultural zone now abandoned or replaced by forested areas. In both areas, lesser kestrels selected extensive agricultural habitats, such as fallows and cereal fields, and avoided scrubland and forests. In the second area, tracked birds from one colony travelled significantly farther distances (6.2 km ± 1.7 vs. 1.8 km ± 0.4 and 1.9 km ± 0.6 and had significant larger foraging-ranges (144 km(2 vs. 18.8 and 14.8 km(2 when compared to the birds of two colonies in the extensive agricultural area. Longer foraging trips were reflected in lower chick feeding rates, lower fledging success and reduced chick fitness. Availability and occupation of artificial nests was high in both areas but population followed opposite trends, with a positive increment recorded exclusively in the first area with a large proportion of agricultural areas. Progressive habitat loss around the studied colony in the second area (suitable habitat decreased from 32% in 1990 to only 7% in 2002 is likely the main driver of the recorded population decline and suggests that the effectiveness of bird species conservation based on nest-site provisioning is highly constrained by habitat quality in the surrounding areas. Therefore, the conservation of cavity-dependent species may be enhanced firstly by finding the best areas of remaining habitat and secondly by increasing the carrying capacity of high

  10. HECTR [Hydrogen Event: Containment Transient Response] analyses of the Nevada Test Site (NTS) premixed combustion experiments

    International Nuclear Information System (INIS)

    Wong, C.C.

    1988-11-01

    The HECTR (Hydrogen Event: Containment Transient Response) computer code has been developed at Sandia National Laboratories to predict the transient pressure and temperature responses within reactor containments for hypothetical accidents involving the transport and combustion of hydrogen. Although HECTR was designed primarily to investigate these phenomena in LWRs, it may also be used to analyze hydrogen transport and combustion experiments as well. It is in this manner that HECTR is assessed and empirical correlations, such as the combustion completeness and flame speed correlations for the hydrogen combustion model, if necessary, are upgraded. In this report, we present HECTR analyses of the large-scale premixed hydrogen combustion experiments at the Nevada Test Site (NTS) and comparison with the test results. The existing correlations in HECTR version 1.0, under certain conditions, have difficulty in predicting accurately the combustion completeness and burn time for the NTS experiments. By combining the combustion data obtained from the NTS experiments with other experimental data (FITS, VGES, ACUREX, and Whiteshell), a set of new and better combustion correlations was generated. HECTR prediction of the containment responses, using a single-compartment model and EPRI-provided combustion completeness and burn time, compares reasonably well against the test results. However, HECTR prediction of the containment responses using a multicompartment model does not compare well with the test results. This discrepancy shows the deficiency of the homogeneous burning model used in HECTR. To overcome this deficiency, a flame propagation model is highly recommended. 16 refs., 84 figs., 5 tabs

  11. Active Edge Sites Engineering in Nickel Cobalt Selenide Solid Solutions for Highly Efficient Hydrogen Evolution

    KAUST Repository

    Xia, Chuan

    2017-01-06

    An effective multifaceted strategy is demonstrated to increase active edge site concentration in NiCoSe solid solutions prepared by in situ selenization process of nickel cobalt precursor. The simultaneous control of surface, phase, and morphology result in as-prepared ternary solid solution with extremely high electrochemically active surface area (C = 197 mF cm), suggesting significant exposure of active sites in this ternary compound. Coupled with metallic-like electrical conductivity and lower free energy for atomic hydrogen adsorption in NiCoSe, identified by temperature-dependent conductivities and density functional theory calculations, the authors have achieved unprecedented fast hydrogen evolution kinetics, approaching that of Pt. Specifically, the NiCoSe solid solutions show a low overpotential of 65 mV at -10 mV cm, with onset potential of mere 18 mV, an impressive small Tafel slope of 35 mV dec, and a large exchange current density of 184 μA cm in acidic electrolyte. Further, it is shown that the as-prepared NiCoSe solid solution not only works very well in acidic electrolyte but also delivers exceptional hydrogen evolution reaction (HER) performance in alkaline media. The outstanding HER performance makes this solid solution a promising candidate for mass hydrogen production.

  12. Solid hydrogen and deuterium. II. Pressure and compressibility calculated by a lowest-order constrained-variation method

    International Nuclear Information System (INIS)

    Pettersen, G.; Ostgaard, E.

    1988-01-01

    The pressure and the compressibility of solid H 2 and D 2 are obtained from ground-state energies calculated by means of a modified variational lowest order constrained-variation (LOCV) method. Both fcc and hcp structures are considered, but results are given for the fcc structure only. The pressure and the compressibility are calculated or estimated from the dependence of the ground-state energy on density or molar volume, generally in a density region of 0.65σ -3 to 1.3σ -3 , corresponding to a molar volume of 0.65σ -3 to 1.3σ -3 , corresponding to a molar volume of 12-24 cm 3 mole, where σ = 2.958 angstrom, and the calculations are done for five different two-body potentials. Theoretical results for the pressure are 340-460 atm for solid H 2 at a particle density of 0.82σ -3 or a molar volume of 19 cm 3 /mole, and 370-490 atm for solid 4 He at a particle density of 0.92σ -3 or a molar volume of 17 cm 3 /mole. The corresponding experimental results are 650 and 700 atm, respectively. Theoretical results for the compressibility are 210 times 10 -6 to 260 times 10 -6 atm -1 for solid H 2 at a particle density of 0.82σ -3 or a molar volume of 19 cm 3 /mole, and 150 times 10 -6 to 180 times 10 -6 atm -1 for solid D 2 at a particle density of 0.92σ -3 or a molar volume of 17 cm 3 mole. The corresponding experimental results are 180 times 10 -6 and 140 times 10 -6 atm -1 , respectively. The agreement with experimental results is better for higher densities

  13. Comment on "Active sites for CO2 hydrogenation to methanol on Cu/ZnO catalysts"

    DEFF Research Database (Denmark)

    Nakamura, Junji; Fujitani, Tadahiro; Kuld, Sebastian

    2017-01-01

    Kattel et al (Reports, 24 March 2017, p. 1296) report that a zinc on copper (Zn/Cu) surface undergoes oxidation to zinc oxide/copper (ZnO/Cu) during carbon dioxide (CO2) hydrogenation to methanol and conclude that the Cu-ZnO interface is the active site for methanol synthesis. Similar experiments...... conducted two decades ago by Fujitani and Nakamura et al demonstrated that Zn is attached to formate rather than being fully oxidized....

  14. Preliminary analysis of an hydrogen generator system based on nuclear energy in the Laguna Verde site

    International Nuclear Information System (INIS)

    Flores y Flores, A.; Francois L, J.L.

    2003-01-01

    The shortage of fossil fuels in the next future, as well as the growing one demand of energetics and the high cost of the production of alternating fuels, it forces us to take advantage of to the maximum the fossil fuel with the one which we count and to look for the form of producing alternating fuels at a low cost and better even if these supply sources are reliable and non pollutants. It is intended a solution to the shortage of fuel; to use the thermal energy liberated of some appropriate nuclear reactor to be able to obtain a fuel but clean and relatively cheap as it is the hydrogen. In the first place the methods were looked for to produce hydrogen using thermal energy, later it was analyzed the temperature liberated by the existent nuclear reactors as well as the advanced designs, according to this liberated temperature settled down that the methods but feasible to produce hydrogen its were the one of reformed with water stream of the natural gas (methane) and the other one of the S-I thermochemical cycle, and the nuclear reactors that give the thermal energy for this production they are those of gas of high temperature. Once established the processes and the appropriate reactors, it was analyzed the site of Laguna Verde, with relationship to the free space to be able to place the reactor and the plant producer of hydrogen, as well as the direction in which blow the dominant winds and the near towns to the place, it was carried out an analysis of some explosion of tanks that could store hydrogen and the damage that its could to cause depending from the distance to which its were of the fire. Finally it was carried out an evaluation of capital and of operation costs for those two methods of hydrogen production. (Author)

  15. Site-Dependent Environmental Impacts of Industrial Hydrogen Production by Alkaline Water Electrolysis

    Directory of Open Access Journals (Sweden)

    Jan Christian Koj

    2017-06-01

    Full Text Available Industrial hydrogen production via alkaline water electrolysis (AEL is a mature hydrogen production method. One argument in favor of AEL when supplied with renewable energy is its environmental superiority against conventional fossil-based hydrogen production. However, today electricity from the national grid is widely utilized for industrial applications of AEL. Also, the ban on asbestos membranes led to a change in performance patterns, making a detailed assessment necessary. This study presents a comparative Life Cycle Assessment (LCA using the GaBi software (version 6.115, thinkstep, Leinfelden-Echterdingen, Germany, revealing inventory data and environmental impacts for industrial hydrogen production by latest AELs (6 MW, Zirfon membranes in three different countries (Austria, Germany and Spain with corresponding grid mixes. The results confirm the dependence of most environmental effects from the operation phase and specifically the site-dependent electricity mix. Construction of system components and the replacement of cell stacks make a minor contribution. At present, considering the three countries, AEL can be operated in the most environmentally friendly fashion in Austria. Concerning the construction of AEL plants the materials nickel and polytetrafluoroethylene in particular, used for cell manufacturing, revealed significant contributions to the environmental burden.

  16. Cocrystals of 5-fluorocytosine. I. Coformers with fixed hydrogen-bonding sites.

    Science.gov (United States)

    Tutughamiarso, Maya; Wagner, Guido; Egert, Ernst

    2012-08-01

    The antifungal drug 5-fluorocytosine (4-amino-5-fluoro-1,2-dihydropyrimidin-2-one) was cocrystallized with five complementary compounds in order to better understand its drug-receptor interaction. The first two compounds, 2-aminopyrimidine (2-amino-1,3-diazine) and N-acetylcreatinine (N-acetyl-2-amino-1-methyl-5H-imidazol-4-one), exhibit donor-acceptor sites for R(2)(2)(8) heterodimer formation with 5-fluorocytosine. Such a heterodimer is observed in the cocrystal with 2-aminopyrimidine (I); in contrast, 5-fluorocytosine and N-acetylcreatinine [which forms homodimers in its crystal structure (II)] are connected only by a single hydrogen bond in (III). The other three compounds 6-aminouracil (6-amino-2,4-pyrimidinediol), 6-aminoisocytosine (2,6-diamino-3H-pyrimidin-4-one) and acyclovir [acycloguanosine or 2-amino-9-[(2-hydroxyethoxy)methyl]-1,9-dihydro-6H-purin-6-one] possess donor-donor-acceptor sites; therefore, they can interact with 5-fluorocytosine to form a heterodimer linked by three hydrogen bonds. In the cocrystals with 6-aminoisocytosine (Va)-(Vd), as well as in the cocrystal with the antiviral drug acyclovir (VII), the desired heterodimers are observed. However, they are not formed in the cocrystal with 6-aminouracil (IV), where the components are connected by two hydrogen bonds. In addition, a solvent-free structure of acyclovir (VI) was obtained. A comparison of the calculated energies released during dimer formation helped to rationalize the preference for hydrogen-bonding interactions in the various cocrystal structures.

  17. Accident for natural gas well with hydrogen sulfide in relation to nuclear power plant siting

    International Nuclear Information System (INIS)

    Tan Chengjun; Shangguang Zhihong; Sha Xiangdong

    2010-01-01

    In order to make assessment to the potential impact from accident of natural gas wells with hydrogen sulfide on the habitability of main control room of nuclear power plant (NPP), several assumptions such as source terms of maximum credible accident, conservative atmospheric conditions and release characteristics were proposed in the paper, and the impact on the habitability of main control room was evaluated using toxicity thresholds recommended by foreign authority. Case results indicate that the method can provide the reference for the preliminary assessment to external human-induced events during the siting phrase of NPP. (authors)

  18. Hydrogen.

    Science.gov (United States)

    Bockris, John O'M

    2011-11-30

    The idea of a "Hydrogen Economy" is that carbon containing fuels should be replaced by hydrogen, thus eliminating air pollution and growth of CO₂ in the atmosphere. However, storage of a gas, its transport and reconversion to electricity doubles the cost of H₂ from the electrolyzer. Methanol made with CO₂ from the atmosphere is a zero carbon fuel created from inexhaustible components from the atmosphere. Extensive work on the splitting of water by bacteria shows that if wastes are used as the origin of feed for certain bacteria, the cost for hydrogen becomes lower than any yet known. The first creation of hydrogen and electricity from light was carried out in 1976 by Ohashi et al. at Flinders University in Australia. Improvements in knowledge of the structure of the semiconductor-solution system used in a solar breakdown of water has led to the discovery of surface states which take part in giving rise to hydrogen (Khan). Photoelectrocatalysis made a ten times increase in the efficiency of the photo production of hydrogen from water. The use of two electrode cells; p and n semiconductors respectively, was first introduced by Uosaki in 1978. Most photoanodes decompose during the photoelectrolysis. To avoid this, it has been necessary to create a transparent shield between the semiconductor and its electronic properties and the solution. In this way, 8.5% at 25 °C and 9.5% at 50 °C has been reached in the photo dissociation of water (GaP and InAs) by Kainthla and Barbara Zeleney in 1989. A large consortium has been funded by the US government at the California Institute of Technology under the direction of Nathan Lewis. The decomposition of water by light is the main aim of this group. Whether light will be the origin of the post fossil fuel supply of energy may be questionable, but the maximum program in this direction is likely to come from Cal. Tech.

  19. Widely available active sites on Ni2P for electrochemical hydrogen evolution - insights from first principles calculations

    DEFF Research Database (Denmark)

    Hansen, Martin Hangaard; Stern, Lucas-Alexandre; Feng, Ligang

    2015-01-01

    We present insights into the mechanism and the active site for hydrogen evolution on nickel phosphide (Ni2P). Ni2P was recently discovered to be a very active non-precious hydrogen evolution catalyst. Current literature attributes the activity of Ni2P to a particular site on the (0001) facet....... In the present study, using Density Functional Theory (DFT) calculations, we show that several widely available low index crystal facets on Ni2P have better properties for a high catalytic activity. DFT calculations were used to identify moderately bonding nickel bridge sites and nickel hollow sites for hydrogen...... adsorption and to calculate barriers for the Tafel pathway. The investigated surfaces in this study were the (10 (1) over bar0), ((1) over bar(1) over bar 20), (11 (2) over bar0), (11 (2) over bar1) and (0001) facets of the hexagonal Ni2P crystal. In addition to the DFT results, we present experiments on Ni2...

  20. Single cobalt sites in mesoporous N-doped carbon matrix for selective catalytic hydrogenation of nitroarenes

    KAUST Repository

    Sun, Xiaohui

    2017-11-20

    A supported cobalt catalyst with atomically dispersed Co-Nx sites (3.5 wt% Co) in a mesoporous N-doped carbon matrix (named Co@mesoNC) is synthesized by hydrolysis of tetramethyl orthosilicate (TMOS) in a Zn/Co bimetallic zeolitic imidazolate framework (BIMZIF(Co,Zn)), followed by high-temperature pyrolysis and SiO2 leaching. A combination of TEM, XRD XPS and X-ray absorption spectroscopy studies confirm the absence of cobalt nanoparticles and indicate that these highly dispersed cobalt species are present in the form of Co-Nx. The exclusive formation of Co-Nx sites in the carbon matrix is attributed to the presence of a large amount of Zn and N in the BIMZIF precursor together with the presence of SiO2 in the pore space of this framework, extending the initial spatial distance between cobalt atoms and thereby impeding their agglomeration. The presence of SiO2 during high-temperature pyrolysis is proven crucial to create mesoporosity and a high BET area and pore volume in the N-doped carbon support (1780 m2 g−1, 1.54 cm3 g−1). This heterogeneous Co@mesoNC catalyst displays high activity and selectivity (>99%) for the selective hydrogenation of nitrobenzene to aniline at mild conditions (0.5–3 MPa, 343–383 K). When more challenging substrates (functionalized nitroarenes) are hydrogenated, the catalyst Co@mesoNC displays an excellent chemoselectivity to the corresponding substituted anilines.The presence of mesoporosity improves mass transport of reactants and/or products and the accessibility of the active Co-Nx sites, and greatly reduces deactivation due to fouling.

  1. Single cobalt sites in mesoporous N-doped carbon matrix for selective catalytic hydrogenation of nitroarenes

    KAUST Repository

    Sun, Xiaohui; Olivos-Suarez, Alma I.; Osadchii, Dmitrii; Romero, Maria Jose Valero; Kapteijn, Freek; Gascon, Jorge

    2017-01-01

    A supported cobalt catalyst with atomically dispersed Co-Nx sites (3.5 wt% Co) in a mesoporous N-doped carbon matrix (named Co@mesoNC) is synthesized by hydrolysis of tetramethyl orthosilicate (TMOS) in a Zn/Co bimetallic zeolitic imidazolate framework (BIMZIF(Co,Zn)), followed by high-temperature pyrolysis and SiO2 leaching. A combination of TEM, XRD XPS and X-ray absorption spectroscopy studies confirm the absence of cobalt nanoparticles and indicate that these highly dispersed cobalt species are present in the form of Co-Nx. The exclusive formation of Co-Nx sites in the carbon matrix is attributed to the presence of a large amount of Zn and N in the BIMZIF precursor together with the presence of SiO2 in the pore space of this framework, extending the initial spatial distance between cobalt atoms and thereby impeding their agglomeration. The presence of SiO2 during high-temperature pyrolysis is proven crucial to create mesoporosity and a high BET area and pore volume in the N-doped carbon support (1780 m2 g−1, 1.54 cm3 g−1). This heterogeneous Co@mesoNC catalyst displays high activity and selectivity (>99%) for the selective hydrogenation of nitrobenzene to aniline at mild conditions (0.5–3 MPa, 343–383 K). When more challenging substrates (functionalized nitroarenes) are hydrogenated, the catalyst Co@mesoNC displays an excellent chemoselectivity to the corresponding substituted anilines.The presence of mesoporosity improves mass transport of reactants and/or products and the accessibility of the active Co-Nx sites, and greatly reduces deactivation due to fouling.

  2. Hydrogen

    Directory of Open Access Journals (Sweden)

    John O’M. Bockris

    2011-11-01

    Full Text Available The idea of a “Hydrogen Economy” is that carbon containing fuels should be replaced by hydrogen, thus eliminating air pollution and growth of CO2 in the atmosphere. However, storage of a gas, its transport and reconversion to electricity doubles the cost of H2 from the electrolyzer. Methanol made with CO2 from the atmosphere is a zero carbon fuel created from inexhaustible components from the atmosphere. Extensive work on the splitting of water by bacteria shows that if wastes are used as the origin of feed for certain bacteria, the cost for hydrogen becomes lower than any yet known. The first creation of hydrogen and electricity from light was carried out in 1976 by Ohashi et al. at Flinders University in Australia. Improvements in knowledge of the structure of the semiconductor-solution system used in a solar breakdown of water has led to the discovery of surface states which take part in giving rise to hydrogen (Khan. Photoelectrocatalysis made a ten times increase in the efficiency of the photo production of hydrogen from water. The use of two electrode cells; p and n semiconductors respectively, was first introduced by Uosaki in 1978. Most photoanodes decompose during the photoelectrolysis. To avoid this, it has been necessary to create a transparent shield between the semiconductor and its electronic properties and the solution. In this way, 8.5% at 25 °C and 9.5% at 50 °C has been reached in the photo dissociation of water (GaP and InAs by Kainthla and Barbara Zeleney in 1989. A large consortium has been funded by the US government at the California Institute of Technology under the direction of Nathan Lewis. The decomposition of water by light is the main aim of this group. Whether light will be the origin of the post fossil fuel supply of energy may be questionable, but the maximum program in this direction is likely to come from Cal. Tech.

  3. Simulations of hydrogen sorption in rht-MOF-1: identifying the binding sites through explicit polarization and quantum rotation calculations

    KAUST Repository

    Pham, Tony

    2014-01-01

    Grand canonical Monte Carlo (GCMC) simulations of hydrogen sorption were performed in rht-MOF-1, a metal-organic framework (MOF) that consists of isophthalate groups joined by copper paddlewheel clusters and Cu3O trimers through tetrazolate moeities. This is a charged rht-MOF that contains extra-framework nitrate counterions within the material. For the simulations performed herein, excellent agreement with experiment was achieved for the simulated hydrogen sorption isotherms and calculated isosteric heat of adsorption, Qst, values only when using a polarizable potential. Thermodynamic agreement is demonstrated via comparing to experimental isotherms and binding sites are revealed by combining simulation and inelastic neutron scattering (INS) data. Simulations involving explicit many-body polarization interactions assisted in the determination of the binding sites in rht-MOF-1 through the distribution of the induced dipoles that led to strong adsorbate interactions. Four distinct hydrogen sorption sites were determined from the polarization distribution: the nitrate ions located in the corners of the truncated tetrahedral cages, the Cu2+ ions of the paddlewheels that project into the truncated tetrahedral and truncated octahedral cages (Cu1 ions), the Cu2+ ions of the Cu3O trimers (Cu3 ions), and the sides of the paddlewheels in the cuboctahedral cage. The simulations revealed that the initial sorption sites for hydrogen in rht-MOF-1 are the nitrate ions; this site corresponds to the high initial Qst value for hydrogen (9.5 kJ mol-1) in the MOF. The radial distribution functions, g(r), about the Cu2+ ions at various loadings revealed that the Cu1 ions are the preferred open-metal sorption sites for hydrogen at low loading, while the Cu3 ions become occupied at higher loadings. The validation of the aforementioned sorption sites in rht-MOF-1 was confirmed by calculating the two-dimensional quantum rotational levels about each site and comparing the levels to the

  4. Physiological and genomic features of highly alkaliphilic hydrogen-utilizing Betaproteobacteria from a continental serpentinizing site.

    Science.gov (United States)

    Suzuki, Shino; Kuenen, J Gijs; Schipper, Kira; van der Velde, Suzanne; Ishii, Shun'ichi; Wu, Angela; Sorokin, Dimitry Y; Tenney, Aaron; Meng, XianYing; Morrill, Penny L; Kamagata, Yoichi; Muyzer, Gerard; Nealson, Kenneth H

    2014-05-21

    Serpentinization, or the aqueous alteration of ultramafic rocks, results in challenging environments for life in continental sites due to the combination of extremely high pH, low salinity and lack of obvious electron acceptors and carbon sources. Nevertheless, certain Betaproteobacteria have been frequently observed in such environments. Here we describe physiological and genomic features of three related Betaproteobacterial strains isolated from highly alkaline (pH 11.6) serpentinizing springs at The Cedars, California. All three strains are obligate alkaliphiles with an optimum for growth at pH 11 and are capable of autotrophic growth with hydrogen, calcium carbonate and oxygen. The three strains exhibit differences, however, regarding the utilization of organic carbon and electron acceptors. Their global distribution and physiological, genomic and transcriptomic characteristics indicate that the strains are adapted to the alkaline and calcium-rich environments represented by the terrestrial serpentinizing ecosystems. We propose placing these strains in a new genus 'Serpentinomonas'.

  5. Active Edge Sites Engineering in Nickel Cobalt Selenide Solid Solutions for Highly Efficient Hydrogen Evolution

    KAUST Repository

    Xia, Chuan; Liang, Hanfeng; Zhu, Jiajie; Schwingenschlö gl, Udo; Alshareef, Husam N.

    2017-01-01

    free energy for atomic hydrogen adsorption in NiCoSe, identified by temperature-dependent conductivities and density functional theory calculations, the authors have achieved unprecedented fast hydrogen evolution kinetics, approaching that of Pt

  6. Comparison of reactivity on step and terrace sites of Pd (3 3 2) surface for the dissociative adsorption of hydrogen: A quantum chemical molecular dynamics study

    International Nuclear Information System (INIS)

    Ahmed, Farouq; Nagumo, Ryo; Miura, Ryuji; Ai, Suzuki; Tsuboi, Hideyuki; Hatakeyama, Nozomu; Endou, Akira; Takaba, Hiromitsu; Kubo, Momoji; Miyamoto, Akira

    2011-01-01

    The notion of 'active sites' is fundamental to heterogeneous catalysis. However, the exact nature of the active sites, and hence the mechanism by which they act, are still largely a matter of speculation. In this study, we have presented a systematic quantum chemical molecular dynamics (QCMD) calculations for the interaction of hydrogen on different step and terrace sites of the Pd (3 3 2) surface. Finally the dissociative adsorption of hydrogen on step and terrace as well as the influence of surface hydrogen vacancy for the dissociative adsorption of hydrogen has been investigated through QCMD. This is a state-of-the-art method for calculating the interaction of atoms and molecules with metal surfaces. It is found that fully hydrogen covered (saturated) step sites can dissociate hydrogen moderately and that a monovacancy surface is suitable for significant dissociative adsorption of hydrogen. However in terrace site of the surface we have found that dissociation of hydrogen takes place only on Pd sites where the metal atom is not bound to any pre-adsorbed hydrogen atoms. Furthermore, from the molecular dynamics and electronic structure calculations, we identify a number of consequences for the interpretation and modeling of diffusion experiments demonstrating the coverage and directional dependence of atomic hydrogen diffusion on stepped palladium surface.

  7. Small constrained SP1-7 analogs bind to a unique site and promote anti-allodynic effects following systemic injection in mice.

    Science.gov (United States)

    Jonsson, A; Fransson, R; Haramaki, Y; Skogh, A; Brolin, E; Watanabe, H; Nordvall, G; Hallberg, M; Sandström, A; Nyberg, F

    2015-07-09

    Previous results have shown that the substance P (SP) N-terminal fragment SP1-7 may attenuate hyperalgesia and produce anti-allodynia in animals using various experimental models for neuropathic pain. The heptapeptide was found to induce its effects through binding to and activating specific sites apart from any known neurokinin or opioid receptor. Furthermore, we have applied a medicinal chemistry program to develop lead compounds mimicking the effect of SP1-7. The present study was designed to evaluate the pharmacological effect of these compounds using the mouse spared nerve injury (SNI) model of chronic neuropathic pain. Also, as no comprehensive screen with the aim to identify the SP1-7 target has yet been performed we screened our lead compound H-Phe-Phe-NH2 toward a panel of drug targets. The extensive target screen, including 111 targets, did not reveal any hit for the binding site among a number of known receptors or enzymes involved in pain modulation. Our animal studies confirmed that SP1-7, but also synthetic analogs thereof, possesses anti-allodynic effects in the mouse SNI model of neuropathic pain. One of the lead compounds, a constrained H-Phe-Phe-NH2 analog, was shown to exhibit a significant anti-allodynic effect. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

  8. Probing the Watson-Crick, wobble, and sugar-edge hydrogen bond sites of uracil and thymine.

    Science.gov (United States)

    Müller, Andreas; Frey, Jann A; Leutwyler, Samuel

    2005-06-16

    The nucleobases uracil (U) and thymine (T) offer three hydrogen-bonding sites for double H-bond formation via neighboring N-H and C=O groups, giving rise to the Watson-Crick, wobble and sugar-edge hydrogen bond isomers. We probe the hydrogen bond properties of all three sites by forming hydrogen bonded dimers of U, 1-methyluracil (1MU), 3-methyluracil (3MU), and T with 2-pyridone (2PY). The mass- and isomer-specific S1 origins exhibit large spectral blue shifts relative to the 2PY monomer. Ab initio CIS calculations of the spectral shifts of the different hydrogen-bonded dimers show a linear correlation with experiment. This correlation allows us to identify the R2PI spectra of the weakly populated Watson-Crick and wobble isomers of both 2PY.U and 2PY.T. (3) PW91 density functional calculation of the ground-state binding and dissociation energies De and D0 are in agreement with the assignment of the dominant hydrogen bond isomers of 2PY.U, 2PY.3MU and 2PY.T as the sugar-edge form. For 2PY.U, 2PY.T and 2PY.1MU the measured wobble:Watson-Crick:sugar-edge isomer ratios are in good agreement with the calculated ratios, based on the ab initio dissociation energies and gas-phase statistical mechanics. The Watson-Crick and wobble isomers are thereby determined to be several kcal/mol less strongly bound than the sugar-edge isomers. The 36 observed intermolecular frequencies of the nine different H-bonded isomers give detailed insight into the intermolecular force field.

  9. Probing the importance of hydrogen bonds in the active site of the subtilisin nattokinase by site-directed mutagenesis and molecular dynamics simulation.

    Science.gov (United States)

    Zheng, Zhong-liang; Ye, Mao-qing; Zuo, Zhen-yu; Liu, Zhi-gang; Tai, Keng-chang; Zou, Guo-lin

    2006-05-01

    Hydrogen bonds occurring in the catalytic triad (Asp32, His64 and Ser221) and the oxyanion hole (Asn155) are very important to the catalysis of peptide bond hydrolysis by serine proteases. For the subtilisin NK (nattokinase), a bacterial serine protease, construction and analysis of a three-dimensional structural model suggested that several hydrogen bonds formed by four residues function to stabilize the transition state of the hydrolysis reaction. These four residues are Ser33, Asp60, Ser62 and Thr220. In order to remove the effect of these hydrogen bonds, four mutants (Ser33-->Ala33, Asp60-->Ala60, Ser62-->Ala62, and Thr220-->Ala220) were constructed by site-directed mutagenesis. The results of enzyme kinetics indicated that removal of these hydrogen bonds increases the free-energy of the transition state (DeltaDeltaG(T)). We concluded that these hydrogen bonds are more important for catalysis than for binding the substrate, because removal of these bonds mainly affects the kcat but not the K(m) values. A substrate, SUB1 (succinyl-Ala-Ala-Pro-Phe-p-nitroanilide), was used during enzyme kinetics experiments. In the present study we have also shown the results of FEP (free-energy perturbation) calculations with regard to the binding and catalysis reactions for these mutant subtilisins. The calculated difference in FEP also suggested that these four residues are more important for catalysis than binding of the substrate, and the simulated values compared well with the experimental values from enzyme kinetics. The results of MD (molecular dynamics) simulations further demonstrated that removal of these hydrogen bonds partially releases Asp32, His64 and Asn155 so that the stability of the transition state decreases. Another substrate, SUB2 (H-D-Val-Leu-Lys-p-nitroanilide), was used for FEP calculations and MD simulations.

  10. Hydrogen production by ethanol steam reforming over co-hydrotalcites having basic sites

    Energy Technology Data Exchange (ETDEWEB)

    Contreras, J.L.; Salmones, J.; Garcia, L.A.; Ponce, A.; Zeifert, B.; Fuentes, G.A. [Univ. Autonoma Metropolitana-Azcapotzalco, Mexico City (Mexico); Contreras, J.L.; Salmones, J.; Garcia, L.A.; Ponce, A.; Zeifert, B.; Fuentes, G.A. [Inst. Politecnico Nacional, Mexico City (Mexico); Contreras, J.L.; Salmones, J.; Garcia, L.A.; Ponce, A.; Zeifert, B.; Fuentes, G.A. [Univ. Autonoma Metropolitana-Iztapalapa, Mexico City (Mexico)

    2008-04-15

    The catalytic steam reforming process can be used to produce hydrogen from ethanol for use in fuel cells. In comparison to methanol or gasoline, ethanol offers many advantages, notably, it is a renewable resource and neutral with respect to emissions of carbon dioxide (CO{sub 2}); it is less toxic; it can be readily stored without handling risk; and it can be obtained in large quantities from biomass. The reaction of ethanol with steam is strongly endothermic and can form undesirable products during the reaction. This article presented a study that combined, for the first time, the catalytic properties of cobalt (Co) with a new family of supports that are the hydrotalcites of high surface area and with basic sites. Co/Hydrotalcite catalysts were prepared, characterized and evaluated during the steam reforming of ethanol from 500 to 650 degrees Celsius. The article discussed the experiment, including the preparation of catalysts; characterization of solids; and catalytic evaluation. Scanning electron microscopy and x-ray diffraction studies were also described. Results were described in terms of area and pore volume distribution; thermogravimetric analysis and differential thermal analysis; temperature-programmed desorption (TPD) of CO{sub 2}; scanning electron microscopy; x-ray diffraction; the crystalline nature of cobalt; and ethanol steam-reforming reaction. It was concluded that the Co concentration was enriched on the hydrotalcite surface. In addition, a direct relationship between the Co concentration and the total basicity was found. A direct relationship between basicity and the conversion was also found. 27 refs., 3 tabs., 12 figs.

  11. RADIOLYTIC HYDROGEN GENERATION INSAVANNAH RIVER SITE (SRS) HIGH LEVEL WASTETANKS COMPARISON OF SRS AND HANFORDMODELING PREDICTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, C; Ned Bibler, N

    2009-04-15

    In the high level waste tanks at the Savannah River Site (SRS), hydrogen is produced continuously by interaction of the radiation in the tank with water in the waste. Consequently, the vapor spaces of the tanks are purged to prevent the accumulation of H{sub 2} and possible formation of a flammable mixture in a tank. Personnel at SRS have developed an empirical model to predict the rate of H{sub 2} formation in a tank. The basis of this model is the prediction of the G value for H{sub 2} production. This G value is the number of H{sub 2} molecules produced per 100 eV of radiolytic energy absorbed by the waste. Based on experimental studies it was found that the G value for H{sub 2} production from beta radiation and from gamma radiation were essentially equal. The G value for H{sub 2} production from alpha radiation was somewhat higher. Thus, the model has two equations, one for beta/gamma radiation and one for alpha radiation. Experimental studies have also indicated that both G values are decreased by the presence of nitrate and nitrite ions in the waste. These are the main scavengers for the precursors of H{sub 2} in the waste; thus the equations that were developed predict G values for hydrogen production as a function of the concentrations of these two ions in waste. Knowing the beta/gamma and alpha heat loads in the waste allows one to predict the total generation rate for hydrogen in a tank. With this prediction a ventilation rate can be established for each tank to ensure that a flammable mixture is not formed in the vapor space in a tank. Recently personnel at Hanford have developed a slightly different model for predicting hydrogen G values. Their model includes the same precursor for H{sub 2} as the SRS model but also includes an additional precursor not in the SRS model. Including the second precursor for H{sub 2} leads to different empirical equations for predicting the G values for H{sub 2} as a function of the nitrate and nitrite concentrations in

  12. Chemical Kinetics of Hydrogen Atom Abstraction from Allylic Sites by 3O2; Implications for Combustion Modeling and Simulation.

    Science.gov (United States)

    Zhou, Chong-Wen; Simmie, John M; Somers, Kieran P; Goldsmith, C Franklin; Curran, Henry J

    2017-03-09

    Hydrogen atom abstraction from allylic C-H bonds by molecular oxygen plays a very important role in determining the reactivity of fuel molecules having allylic hydrogen atoms. Rate constants for hydrogen atom abstraction by molecular oxygen from molecules with allylic sites have been calculated. A series of molecules with primary, secondary, tertiary, and super secondary allylic hydrogen atoms of alkene, furan, and alkylbenzene families are taken into consideration. Those molecules include propene, 2-butene, isobutene, 2-methylfuran, and toluene containing the primary allylic hydrogen atom; 1-butene, 1-pentene, 2-ethylfuran, ethylbenzene, and n-propylbenzene containing the secondary allylic hydrogen atom; 3-methyl-1-butene, 2-isopropylfuran, and isopropylbenzene containing tertiary allylic hydrogen atom; and 1-4-pentadiene containing super allylic secondary hydrogen atoms. The M06-2X/6-311++G(d,p) level of theory was used to optimize the geometries of all of the reactants, transition states, products and also the hinder rotation treatments for lower frequency modes. The G4 level of theory was used to calculate the electronic single point energies for those species to determine the 0 K barriers to reaction. Conventional transition state theory with Eckart tunnelling corrections was used to calculate the rate constants. The comparison between our calculated rate constants with the available experimental results from the literature shows good agreement for the reactions of propene and isobutene with molecular oxygen. The rate constant for toluene with O 2 is about an order magnitude slower than that experimentally derived from a comprehensive model proposed by Oehlschlaeger and coauthors. The results clearly indicate the need for a more detailed investigation of the combustion kinetics of toluene oxidation and its key pyrolysis and oxidation intermediates. Despite this, our computed barriers and rate constants retain an important internal consistency. Rate constants

  13. Chance-constrained multi-objective optimization of groundwater remediation design at DNAPLs-contaminated sites using a multi-algorithm genetically adaptive method.

    Science.gov (United States)

    Ouyang, Qi; Lu, Wenxi; Hou, Zeyu; Zhang, Yu; Li, Shuai; Luo, Jiannan

    2017-05-01

    In this paper, a multi-algorithm genetically adaptive multi-objective (AMALGAM) method is proposed as a multi-objective optimization solver. It was implemented in the multi-objective optimization of a groundwater remediation design at sites contaminated by dense non-aqueous phase liquids. In this study, there were two objectives: minimization of the total remediation cost, and minimization of the remediation time. A non-dominated sorting genetic algorithm II (NSGA-II) was adopted to compare with the proposed method. For efficiency, the time-consuming surfactant-enhanced aquifer remediation simulation model was replaced by a surrogate model constructed by a multi-gene genetic programming (MGGP) technique. Similarly, two other surrogate modeling methods-support vector regression (SVR) and Kriging (KRG)-were employed to make comparisons with MGGP. In addition, the surrogate-modeling uncertainty was incorporated in the optimization model by chance-constrained programming (CCP). The results showed that, for the problem considered in this study, (1) the solutions obtained by AMALGAM incurred less remediation cost and required less time than those of NSGA-II, indicating that AMALGAM outperformed NSGA-II. It was additionally shown that (2) the MGGP surrogate model was more accurate than SVR and KRG; and (3) the remediation cost and time increased with the confidence level, which can enable decision makers to make a suitable choice by considering the given budget, remediation time, and reliability. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Chance-constrained multi-objective optimization of groundwater remediation design at DNAPLs-contaminated sites using a multi-algorithm genetically adaptive method

    Science.gov (United States)

    Ouyang, Qi; Lu, Wenxi; Hou, Zeyu; Zhang, Yu; Li, Shuai; Luo, Jiannan

    2017-05-01

    In this paper, a multi-algorithm genetically adaptive multi-objective (AMALGAM) method is proposed as a multi-objective optimization solver. It was implemented in the multi-objective optimization of a groundwater remediation design at sites contaminated by dense non-aqueous phase liquids. In this study, there were two objectives: minimization of the total remediation cost, and minimization of the remediation time. A non-dominated sorting genetic algorithm II (NSGA-II) was adopted to compare with the proposed method. For efficiency, the time-consuming surfactant-enhanced aquifer remediation simulation model was replaced by a surrogate model constructed by a multi-gene genetic programming (MGGP) technique. Similarly, two other surrogate modeling methods-support vector regression (SVR) and Kriging (KRG)-were employed to make comparisons with MGGP. In addition, the surrogate-modeling uncertainty was incorporated in the optimization model by chance-constrained programming (CCP). The results showed that, for the problem considered in this study, (1) the solutions obtained by AMALGAM incurred less remediation cost and required less time than those of NSGA-II, indicating that AMALGAM outperformed NSGA-II. It was additionally shown that (2) the MGGP surrogate model was more accurate than SVR and KRG; and (3) the remediation cost and time increased with the confidence level, which can enable decision makers to make a suitable choice by considering the given budget, remediation time, and reliability.

  15. Constrained consequence

    CSIR Research Space (South Africa)

    Britz, K

    2011-09-01

    Full Text Available their basic properties and relationship. In Section 3 we present a modal instance of these constructions which also illustrates with an example how to reason abductively with constrained entailment in a causal or action oriented context. In Section 4 we... of models with the former approach, whereas in Section 3.3 we give an example illustrating ways in which C can be de ned with both. Here we employ the following versions of local consequence: De nition 3.4. Given a model M = hW;R;Vi and formulas...

  16. Hydrogen adsorption strength and sites in the metal organic framework MOF5: Comparing experiment and model calculations

    Science.gov (United States)

    Mulder, F. M.; Dingemans, T. J.; Schimmel, H. G.; Ramirez-Cuesta, A. J.; Kearley, G. J.

    2008-07-01

    Hydrogen adsorption in porous, high surface area, and stable metal organic frameworks (MOF's) appears a novel route towards hydrogen storage materials [N.L. Rosi, J. Eckert, M. Eddaoudi, D.T. Vodak, J. Kim, M. O'Keeffe, O.M. Yaghi, Science 300 (2003) 1127; J.L.C. Rowsell, A.R. Millward, K. Sung Park, O.M. Yaghi, J. Am. Chem. Soc. 126 (2004) 5666; G. Ferey, M. Latroche, C. Serre, F. Millange, T. Loiseau, A. Percheron-Guegan, Chem. Commun. (2003) 2976; T. Loiseau, C. Serre, C. Huguenard, G. Fink, F. Taulelle, M. Henry, T. Bataille, G. Férey, Chem. Eur. J. 10 (2004) 1373]. A prerequisite for such materials is sufficient adsorption interaction strength for hydrogen adsorbed on the adsorption sites of the material because this facilitates successful operation under moderate temperature and pressure conditions. Here we report detailed information on the geometry of the hydrogen adsorption sites, based on the analysis of inelastic neutron spectroscopy (INS). The adsorption energies for the metal organic framework MOF5 equal about 800 K for part of the different sites, which is significantly higher than for nanoporous carbon materials (˜550 K) [H.G. Schimmel, G.J. Kearley, M.G. Nijkamp, C.T. Visser, K.P. de Jong, F.M. Mulder, Chem. Eur. J. 9 (2003) 4764], and is in agreement with what is found in first principles calculations [T. Sagara, J. Klassen, E. Ganz, J. Chem. Phys. 121 (2004) 12543; F.M. Mulder, T.J. Dingemans, M. Wagemaker, G.J. Kearley, Chem. Phys. 317 (2005) 113]. Assignments of the INS spectra is realized using comparison with independently published model calculations [F.M. Mulder, T.J. Dingemans, M. Wagemaker, G.J. Kearley, Chem. Phys. 317 (2005) 113] and structural data [T. Yildirim, M.R. Hartman, Phys. Rev. Lett. 95 (2005) 215504].

  17. Interpretation of Flow Logs from Nevada Test Site Boreholes to Estimate Hydraulic conductivity Using Numerical Simulations Constrained by Single-Well Aquifer Tests

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, C. Amanda; Halford, Keith J.; Laczniak, Randell J.

    2010-02-12

    Hydraulic conductivities of volcanic and carbonate lithologic units at the Nevada Test Site were estimated from flow logs and aquifer-test data. Borehole flow and drawdown were integrated and interpreted using a radial, axisymmetric flow model, AnalyzeHOLE. This integrated approach is used because complex well completions and heterogeneous aquifers and confining units produce vertical flow in the annular space and aquifers adjacent to the wellbore. AnalyzeHOLE simulates vertical flow, in addition to horizontal flow, which accounts for converging flow toward screen ends and diverging flow toward transmissive intervals. Simulated aquifers and confining units uniformly are subdivided by depth into intervals in which the hydraulic conductivity is estimated with the Parameter ESTimation (PEST) software. Between 50 and 150 hydraulic-conductivity parameters were estimated by minimizing weighted differences between simulated and measured flow and drawdown. Transmissivity estimates from single-well or multiple-well aquifer tests were used to constrain estimates of hydraulic conductivity. The distribution of hydraulic conductivity within each lithology had a minimum variance because estimates were constrained with Tikhonov regularization. AnalyzeHOLE simulated hydraulic-conductivity estimates for lithologic units across screened and cased intervals are as much as 100 times less than those estimated using proportional flow-log analyses applied across screened intervals only. Smaller estimates of hydraulic conductivity for individual lithologic units are simulated because sections of the unit behind cased intervals of the wellbore are not assumed to be impermeable, and therefore, can contribute flow to the wellbore. Simulated hydraulic-conductivity estimates vary by more than three orders of magnitude across a lithologic unit, indicating a high degree of heterogeneity in volcanic and carbonate-rock units. The higher water transmitting potential of carbonate-rock units relative

  18. Interpretation of Flow Logs from Nevada Test Site Boreholes to Estimate Hydraulic Conductivity Using Numerical Simulations Constrained by Single-Well Aquifer Tests

    Science.gov (United States)

    Garcia, C. Amanda; Halford, Keith J.; Laczniak, Randell J.

    2010-01-01

    Hydraulic conductivities of volcanic and carbonate lithologic units at the Nevada Test Site were estimated from flow logs and aquifer-test data. Borehole flow and drawdown were integrated and interpreted using a radial, axisymmetric flow model, AnalyzeHOLE. This integrated approach is used because complex well completions and heterogeneous aquifers and confining units produce vertical flow in the annular space and aquifers adjacent to the wellbore. AnalyzeHOLE simulates vertical flow, in addition to horizontal flow, which accounts for converging flow toward screen ends and diverging flow toward transmissive intervals. Simulated aquifers and confining units uniformly are subdivided by depth into intervals in which the hydraulic conductivity is estimated with the Parameter ESTimation (PEST) software. Between 50 and 150 hydraulic-conductivity parameters were estimated by minimizing weighted differences between simulated and measured flow and drawdown. Transmissivity estimates from single-well or multiple-well aquifer tests were used to constrain estimates of hydraulic conductivity. The distribution of hydraulic conductivity within each lithology had a minimum variance because estimates were constrained with Tikhonov regularization. AnalyzeHOLE simulated hydraulic-conductivity estimates for lithologic units across screened and cased intervals are as much as 100 times less than those estimated using proportional flow-log analyses applied across screened intervals only. Smaller estimates of hydraulic conductivity for individual lithologic units are simulated because sections of the unit behind cased intervals of the wellbore are not assumed to be impermeable, and therefore, can contribute flow to the wellbore. Simulated hydraulic-conductivity estimates vary by more than three orders of magnitude across a lithologic unit, indicating a high degree of heterogeneity in volcanic and carbonate-rock units. The higher water transmitting potential of carbonate-rock units relative

  19. Ion Mobility Spectrometry-Hydrogen Deuterium Exchange Mass Spectrometry of Anions: Part 2. Assessing Charge Site Location and Isotope Scrambling

    Science.gov (United States)

    Khakinejad, Mahdiar; Ghassabi Kondalaji, Samaneh; Donohoe, Gregory C.; Valentine, Stephen J.

    2016-03-01

    Ion mobility spectrometry (IMS) coupled with gas-phase hydrogen deuterium exchange (HDX)-mass spectrometry (MS) and molecular dynamic simulations (MDS) has been used for structural investigation of anions produced by electrospraying a sample containing a synthetic peptide having the sequence KKDDDDDIIKIIK. In these experiments the potential of the analytical method for locating charge sites on ions as well as for utilizing collision-induced dissociation (CID) to reveal the degree of deuterium uptake within specific amino acid residues has been assessed. For diffuse (i.e., more elongated) [M - 2H]2- ions, decreased deuterium content along with MDS data suggest that the D4 and D6 residues are charge sites, whereas for the more diffuse [M - 3H]3- ions, the data suggest that the D4, D7, and the C-terminus are deprotonated. Fragmentation of mobility-selected, diffuse [M - 2H]2- ions to determine deuterium uptake at individual amino acid residues reveals a degree of deuterium retention at incorporation sites. Although the diffuse [M - 3H]3- ions may show more HD scrambling, it is not possible to clearly distinguish HD scrambling from the expected deuterium uptake based on a hydrogen accessibility model. The capability of the IMS-HDX-MS/MS approach to provide relevant details about ion structure is discussed. Additionally, the ability to extend the approach for locating protonation sites on positively-charged ions is presented.

  20. Understanding hydrogen sorption in a metal-organic framework with open-metal sites and amide functional groups

    KAUST Repository

    Pham, Tony T.

    2013-05-09

    Grand canonical Monte Carlo (GCMC) studies of the mechanism of hydrogen sorption in an rht-MOF known as Cu-TPBTM are presented. The MOF is a decorated/substituted isostructural analogue to the unembellished rht-MOF, PCN-61, that was studied previously [ Forrest, K. A.J. Phys. Chem. C 2012, 116, 15538-15549. ]. The simulations were performed using three different hydrogen potentials of increasing complexity. Simulated hydrogen sorption isotherms and calculated isosteric heat of adsorption, Qst, values were in excellent agreement with the reported experimental data for only a polarizable model in one of four experimentally observed crystal structure configurations. The study demonstrates the ability of modeling to distinguish the differential sorption of distinct strucures; one configuration is found to be dominant due to favorable interactions with substrates. In addition, it was discovered that the presence of polar amide groups had a significant effect on the electrostatics of the Cu2+ ions and directs the low-pressure physisorption of hydrogen in the MOF. This is in contrast to what was observed in PCN-61, where an exterior copper ion had a higher relative charge and was the favored loading site. This tunability of the electrostatics of the copper ions via chemical substitution on the MOF framework can be explained by the presence of the negatively charged oxygen atom of the amide group that causes the interior Cu2+ ion to exhibit a higher positive charge through an inductive effect. Further, control simulations, taking advantage of the flexibility afforded by theoretical modeling, include artificially modified charges for both Cu2+ ions chosen equal to or with a higher charge on the exterior Cu2+ ion. This choice resulted in distinctly different hydrogen sorption characteristics in Cu-TPBTM with no direct sorption on the open-metal sites. Thus, this study demonstrates both the tunable nature of MOF platforms and the possibility for rational design of sorption

  1. Investigation of hydrogen assisted cracking in acicular ferrite using site-specific micro-fracture tests

    Energy Technology Data Exchange (ETDEWEB)

    Costin, Walter L. [School of Mechanical Engineering, The University of Adelaide, SA 5005 (Australia); Lavigne, Olivier, E-mail: Olivier.lavigne@adelaide.edu.au [School of Mechanical Engineering, The University of Adelaide, SA 5005 (Australia); Kotousov, Andrei; Ghomashchi, Reza [School of Mechanical Engineering, The University of Adelaide, SA 5005 (Australia); Linton, Valerie [Energy Pipelines Cooperative Research Centre, Faculty of Engineering, University of Wollongong, NSW 2522 (Australia)

    2016-01-10

    Hydrogen assisted cracking (HAC) is a common type of failure mechanism that can affect a wide range of metals and alloys. Experimental studies of HAC are cumbersome due to various intrinsic and extrinsic parameters and factors (associated with stress, hydrogen and the materials microstructure) contributing to the hydrogen crack kinetics. The microstructure of many materials consists of diverse constituents with characteristic features and mechanical properties which only occur in very small material volumes. The only way to differentiate the effect of these individual constituents on the hydrogen crack kinetics is to miniaturise the testing procedures. In this paper we present a new experimental approach to investigate hydrogen assisted crack growth in a microstructural constituent, i.e. acicular ferrite. For this purpose, sharply notched micro-cantilevers were fabricated with a Focus Ion Beam within this selected microscopic region. Acicular ferrite can be found in many ferrous alloys including ferritic weld metal and has specific features that control its intrinsic susceptibility to HAC. These features were characterised via Electron Backscatter Diffraction and the specimens were subsequently loaded under uncharged and hydrogen charged conditions with a nano-indenter. The outcomes of the testing, demonstrated that the threshold stress intensity factor, K{sub th}, to initiate crack propagation in acicular ferrite ranges between 1.56 MPa m{sup 1/2} and 4.36 MPa m{sup 1/2}. This range is significantly below the values of K{sub th} reported for various ferrous alloys in standard macro-tests. This finding indicates that the mechanisms and resistance to HAC at micro-scale could be very different than at the macro-scale as not all fracture toughening mechanisms may be activated at this scale level.

  2. Estimation of the molecular hydrogen soil uptake and traffic emissions at a suburban site near Paris through hydrogen, carbon monoxide, and radon-222 semicontinuous measurements

    International Nuclear Information System (INIS)

    Yver, C.; Schmidt, M.; Bousquet, P.; Ramonet, M.; Bousquet, P.; Zahorowski, W.

    2009-01-01

    Since June 2006, simultaneous semicontinuous measurements of tropospheric molecular hydrogen (H 2 ), carbon monoxide (CO), and radon-222 ( 222 Rn) have been performed at Gif-sur-Yvette (Paris region), a suburban atmospheric measurement site in France. Molecular hydrogen mixing ratios range from 500 to 1000 ppb, CO mixing ratios vary from 100 to 1400 ppb, and 222 Rn concentrations fluctuate from 0 to 20 Bq m -3 . The H 2 seasonal cycle shows the expected pattern for the Northern Hemisphere with a maximum in spring and a minimum in autumn. We inferred a mean baseline value of 533 ppb with a peak-to-peak amplitude of 30 ppb. Carbon monoxide exhibits a seasonal cycle with a maximum in winter and a minimum in summer. The mean baseline value reaches 132 ppb with a peak-to-peak amplitude of 40 ppb. Radon-222 presents weak seasonal variations with a maximum in autumn/winter and a minimum in spring/summer. The diurnal cycles of H 2 and CO are dominated by emissions from nearby traffic with two peaks during morning and evening rush hours. The typical H 2 /CO emission ratio from traffic is found to be 0.47 ± 0.08 on a molar basis (ppb/ppb). The radon tracer method is applied to nighttime H 2 observations to estimate the H 2 soil uptake of the nocturnal catchment area of our sampling site. The influences from nocturnal local anthropogenic combustion sources are estimated by parallel measurements of CO at 0.14 * 10 -5 g(H 2 ) m -2 h -1 . The mean inferred dry deposition velocity is 0.024 ± 0.013 cm s -1 with a seasonal amplitude of 40% at Gif-sur-Yvette.

  3. Conformational Effects through Hydrogen Bonding in a Constrained γ-Peptide Template: From Intraresidue Seven-Membered Rings to a Gel-Forming Sheet Structure.

    Science.gov (United States)

    Awada, Hawraà; Grison, Claire M; Charnay-Pouget, Florence; Baltaze, Jean-Pierre; Brisset, François; Guillot, Régis; Robin, Sylvie; Hachem, Ali; Jaber, Nada; Naoufal, Daoud; Yazbeck, Ogaritte; Aitken, David J

    2017-05-05

    A series of three short oligomers (di-, tri-, and tetramers) of cis-2-(aminomethyl)cyclobutane carboxylic acid, a γ-amino acid featuring a cyclobutane ring constraint, were prepared, and their conformational behavior was examined spectroscopically and by molecular modeling. In dilute solutions, these peptides showed a number of low-energy conformers, including ribbonlike structures pleated around a rarely observed series of intramolecular seven-membered hydrogen bonds. In more concentrated solutions, these interactions defer to an organized supramolecular assembly, leading to thermoreversible organogel formation notably for the tripeptide, which produced fibrillar xerogels. In the solid state, the dipeptide adopted a fully extended conformation featuring a one-dimensional network of intermolecularly H-bonded molecules stacked in an antiparallel sheet alignment. This work provides unique insight into the interplay between inter- and intramolecular H-bonded conformer topologies for the same peptide template.

  4. Impacts of glycolate and formate radiolysis and thermolysis on hydrogen generation rate calculations for the Savannah River Site tank farm

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, C. L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); King, W. D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-08-14

    Savannah River Remediation (SRR) personnel requested that the Savannah River National Laboratory (SRNL) evaluate available data and determine its applicability to defining the impact of planned glycolate anion additions to Savannah River Site (SRS) High Level Waste (HLW) on Tank Farm flammability (primarily with regard to H2 production). Flammability evaluations of formate anion, which is already present in SRS waste, were also needed. This report describes the impacts of glycolate and formate radiolysis and thermolysis on Hydrogen Generation Rate (HGR) calculations for the SRS Tank Farm.

  5. Combining Ru, Ni and Ni(OH){sub 2} active sites for improving catalytic performance in benzene hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Lihua, E-mail: lihuazhu@stu.xmu.edu.cn [School of Metallurgy and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, Jiang Xi (China); Department of Chemical and Biochemical Engineering, National Engineering Laboratory for Green Productions of Alcohols-Ethers-Esters, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Sun, Hanlei; Zheng, Jinbao [Department of Chemical and Biochemical Engineering, National Engineering Laboratory for Green Productions of Alcohols-Ethers-Esters, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Yu, Changlin, E-mail: yuchanglinjx@163.com [School of Metallurgy and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, Jiang Xi (China); Zhang, Nuowei [Department of Chemical and Biochemical Engineering, National Engineering Laboratory for Green Productions of Alcohols-Ethers-Esters, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Shu, Qing [School of Metallurgy and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, Jiang Xi (China); Chen, Bing H., E-mail: chenbh@xmu.edu.cn [Department of Chemical and Biochemical Engineering, National Engineering Laboratory for Green Productions of Alcohols-Ethers-Esters, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China)

    2017-05-01

    In this study, the Ru{sub 0.04}Ni{sub 0.96}/C(T) catalysts were successfully prepared by the simple methods of hydrazine-reduction and galvanic replacement, where 0.04/0.96 and T represented the Ru/Ni atomic ratio and reducing temperature of the catalyst in N{sub 2}+10%H{sub 2}, respectively. The nanostructures of the Ru{sub 0.04}Ni{sub 0.96} nanoparticles in the Ru{sub 0.04}Ni{sub 0.96}/C(T) catalysts were controlled by modulating their annealing temperature in N{sub 2}+10%H{sub 2} and characterized by an array of techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy energy dispersive X-ray spectroscopy (STEM-EDS) mapping and high-sensitivity low-energy ion scattering (HS-LEIS). The Ru{sub 0.04}Ni{sub 0.96}/C(30) catalyst, which was composed of Ru clusters or single atoms supported on Ni/Ni(OH){sub 2} nanoparticles, exhibited much better catalytic performance for benzene hydrogenation than the Ru{sub 0.04}Ni{sub 0.96}/C(T) catalysts reduced at above 30 °C, such as Ru{sub 0.04}Ni{sub 0.96}/C(160) with the nanostructure of partial Ru{sub 0.04}Ni{sub 0.9} alloy and Ru{sub 0.04}Ni{sub 0.96}/C(280) with the nanostructure of complete Ru{sub 0.04}Ni{sub 0.9} alloy. The reason was that the synergistic effect of multiple active sites – Ru, Ni and Ni(OH){sub 2} sites was present in the Ru{sub 0.04}Ni{sub 0.96}/C(30) catalyst, where hydrogen was preferentially activated at Ru sites, benzene was probably activated at Ni(OH){sub 2} surface and Ni acted as a “bridge” for transferring activated H{sup ∗} species to activated benzene by hydrogen spillover effect, hydrogenating and forming product – cyclohexane. This study also provided a typical example to illustrate that the synergy effect of multiple active sites can largely improve the catalytic hydrogenation performance. - Highlights: • The Ru

  6. Hydrogen Oxidation-Selective Electrocatalysis by Fine Tuning of Pt Ensemble Sites to Enhance the Durability of Automotive Fuel Cells.

    Science.gov (United States)

    Yun, Su-Won; Park, Shin-Ae; Kim, Tae-June; Kim, Jun-Hyuk; Pak, Gi-Woong; Kim, Yong-Tae

    2017-02-08

    A simple, inexpensive approach is proposed for enhancing the durability of automotive proton exchange membrane fuel cells by selective promotion of the hydrogen oxidation reaction (HOR) and suppression of the oxygen reduction reaction (ORR) at the anode in startup/shutdown events. Dodecanethiol forms a self-assembled monolayer (SAM) on the surface of Pt particles, thus decreasing the number of Pt ensemble sites. Interestingly, by controlling the dodecanethiol concentration during SAM formation, the number of ensemble sites can be precisely optimized such that it is sufficient for the HOR but insufficient for the ORR. Thus, a Pt surface with an SAM of dodecanethiol clearly effects HOR-selective electrocatalysis. Clear HOR selectivity is demonstrated in unit cell tests with the actual membrane electrode assembly, as well as in an electrochemical three-electrode setup with a thin-film rotating disk electrode configuration. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Self-optimization of the active site of molybdenum disulfide by an irreversible phase transition during photocatalytic hydrogen evolution

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Longlu; Duan, Xidong; Liu, Chengbin; Zhang, Shuqu; Zeng, Yunxiong [State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha (China); Liu, Xia; Pei, Yong [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, Xiangtan University (China); Luo, Jinming; Crittenden, John [Brook Byers Institute for Sustainable Systems and School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA (United States); Duan, Xiangfeng [Department of Chemistry and Biochemistry, University of California, Los Angeles, CA (United States)

    2017-06-19

    The metallic 1T-MoS{sub 2} has attracted considerable attention as an effective catalyst for hydrogen evolution reactions (HERs). However, the fundamental mechanism about the catalytic activity of 1T-MoS{sub 2} and the associated phase evolution remain elusive and controversial. Herein, we prepared the most stable 1T-MoS{sub 2} by hydrothermal exfoliation of MoS{sub 2} nanosheets vertically rooted into rigid one-dimensional TiO{sub 2} nanofibers. The 1T-MoS{sub 2} can keep highly stable over one year, presenting an ideal model system for investigating the HER catalytic activities as a function of the phase evolution. Both experimental studies and theoretical calculations suggest that 1T phase can be irreversibly transformed into a more active 1T' phase as true active sites in photocatalytic HERs, resulting in a ''catalytic site self-optimization''. Hydrogen atom adsorption is the major driving force for this phase transition. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. A three-site Langmuir adsorption model to elucidate the temperature, pressure, and support dependence of the hydrogen coverage on supported Pt particles

    NARCIS (Netherlands)

    Ji, Y.; Koot, V.; van der Eerden, A.M.J.; Weckhuysen, B.M.; Koningsberger, D.C.; Ramaker, D.E.

    2007-01-01

    The three-site adsorption model, previously developed to describe H adsorption on small Pt particles, was used to gain insight into dependence of hydrogen coverage on temperature, pressure, and support ionicity. The three sites, in order of decreasing PtH bond strength, involve H in an atop, a

  9. Evidence of superstoichiometric H/D LENR active sites and high-temperature superconductivity in a hydrogen-cycled Pd/PdO

    International Nuclear Information System (INIS)

    Lipson, A.G.; Castano, C.H.; Miley, G.H.; Lyakhov, B.F.; Tsivadze, A.Yu.; Mitin, A.V.

    2006-01-01

    Electron transport and magnetic properties have been studied in a 12.5 μm thick Pd foil with a thermally grown oxide and a low-residual concentration of hydrogen. This foil was deformed by cycling across the Pd hydride miscibility gap and the residual hydrogen was trapped at dislocation cores. Anomalies of both resistance and magnetic susceptibility have been observed below 70 K, indicating the appearance of excess conductivity and a diamagnetic response that we interpret in terms of filamentary superconductivity. These anomalies are attributed to a condensed hydrogen-rich phase at dislocation cores. The role of deuterium rich dislocation cores as LENR active sites is discussed. (author)

  10. Evidence of Superstoichiometric H/d Lenr Active Sites and High-Temperature Superconductivity in a Hydrogen-Cycled Pd/PdO

    Science.gov (United States)

    Lipson, A. G.; Castano, C. H.; Miley, G. H.; Lyakhov, B. F.; Tsivadze, A. Yu.; Mitin, A. V.

    Electron transport and magnetic properties have been studied in a 12.5 μm thick Pd foil with a thermally grown oxide and a low-residual concentration of hydrogen. This foil was deformed by cycling across the Pd hydride miscibility gap and the residual hydrogen was trapped at dislocation cores. Anomalies of both resistance and magnetic susceptibility have been observed below 70 K, indicating the appearance of excess conductivity and a diamagnetic response that we interpret in terms of filamentary superconductivity. These anomalies are attributed to a condensed hydrogen-rich phase at dislocation cores. The role of deuterium rich dislocation cores as LENR active sites is discussed.

  11. Unraveling the Nature of Sites Active toward Hydrogen Peroxide Reduction in Fe?N?C Catalysts

    OpenAIRE

    Choi, Chang Hyuck; Choi, Won Seok; Kasian, Olga; Mechler, Anna K.; Sougrati, Moulay Tahar; Br?ller, Sebastian; Strickland, Kara; Jia, Qingying; Mukerjee, Sanjeev; Mayrhofer, Karl J. J.; Jaouen, Fr?d?ric

    2017-01-01

    Abstract Fe?N?C catalysts with high O2 reduction performance are crucial for displacing Pt in low?temperature fuel cells. However, insufficient understanding of which reaction steps are catalyzed by what sites limits their progress. The nature of sites were investigated that are active toward H2O2 reduction, a key intermediate during indirect O2 reduction and a source of deactivation in fuel cells. Catalysts comprising different relative contents of FeN x C y moieties and Fe particles encapsu...

  12. The origins of enhanced activity in factor VIIa analogs and the interplay between key allosteric sites revealed by hydrogen exchange mass spectrometry

    DEFF Research Database (Denmark)

    Rand, Kasper D; Andersen, Mette D; Olsen, Ole H

    2008-01-01

    Factor VIIa (FVIIa) circulates in the blood in a zymogen-like state. Only upon association with membrane-bound tissue factor (TF) at the site of vascular injury does FVIIa become active and able to initiate blood coagulation. Here we used hydrogen exchange monitored by mass spectrometry to invest......Factor VIIa (FVIIa) circulates in the blood in a zymogen-like state. Only upon association with membrane-bound tissue factor (TF) at the site of vascular injury does FVIIa become active and able to initiate blood coagulation. Here we used hydrogen exchange monitored by mass spectrometry...... to investigate the conformational effects of site-directed mutagenesis at key positions in FVIIa and the origins of enhanced intrinsic activity of FVIIa analogs. The differences in hydrogen exchange of two highly active variants, FVIIa(DVQ) and FVIIa(VEAY), imply that enhanced catalytic efficiency was attained...

  13. Physiological and genomic features of highly alkaliphilic hydrogen-utilizing Betaproteobacteria from a continental serpentinizing site

    NARCIS (Netherlands)

    Suzuki, S.; Kuenen, J.G.; Schipper, K.; van der Velde, S.; Ishii, S.; Wu, A.; Sorokin, D.Y.; Tenney, A.; Meng, X.Y.; Morrill, P.L.; Kamagata, Y.; Muyzer, G.; Nealson, K.H.

    2014-01-01

    Serpentinization, or the aqueous alteration of ultramafic rocks, results in challenging environments for life in continental sites due to the combination of extremely high pH, low salinity and lack of obvious electron acceptors and carbon sources. Nevertheless, certain Betaproteobacteria have been

  14. Simulation of the Mechanism of Gas Sorption in a Metal–Organic Framework with Open Metal Sites: Molecular Hydrogen in PCN-61

    KAUST Repository

    Forrest, Katherine A.; Pham, Tony; McLaughlin, Keith; Belof, Jonathan L.; Stern, Abraham C.; Zaworotko, Michael J.; Space, Brian

    2012-01-01

    polarizability; sorbed hydrogen is a dipolar dense fluid in the MOF. This study demonstrates that many-body polarization makes a critical contribution to gas sorption structure and must be accounted for in modeling MOFs with polar interaction sites. © 2012

  15. A small-scale flow alkaline fuel cell for on-site production of hydrogen peroxide

    International Nuclear Information System (INIS)

    Brillas, Enric; Alcaide, Francisco; Cabot, Pere-Lluis

    2002-01-01

    The behavior of a small-scale flow alkaline fuel cell (AFC) built-up for on-site production of HO 2 - using commercial gas-diffusion electrodes has been studied. It produces a spontaneous current due to the oxidation of H 2 to H 2 O at the H 2 -diffusion anode and the reduction of O 2 to HO 2 - at the O 2 -diffusion cathode, while a fresh 1.0-6.0 mol dm -3 KOH electrolyte at 15.0-45.0 deg. C is injected through it. Under circulation of HO 2 - +KOH solutions in open circuit, the flow AFC behaves as a two-electron reversible system. When it is shorted with an external load (R ext ), steady cell voltage-current density curves are found. The use of O 2 /N 2 mixtures to fed the cathode causes a loss of its performance, being required to supply pure O 2 to yield a maximum HO 2 - electrogeneration. The current density and HO 2 - productivity increase with raising OH - concentration, temperature and pressure of O 2 fed. At R ext =0.10 Ω, a current efficiency close to 100% is obtained, and current densities >100 mA cm -2 are achieved for 1.0 mol dm -3 KOH at 45.0 deg. C and for higher KOH concentrations at 25.0 deg. C. The flow AFC can work under optimum conditions up to 6.0 mol dm -3 KOH and 45.0 deg. C for possible industrial applications

  16. Simulation of the Mechanism of Gas Sorption in a Metal–Organic Framework with Open Metal Sites: Molecular Hydrogen in PCN-61

    KAUST Repository

    Forrest, Katherine A.

    2012-07-26

    Grand canonical Monte Carlo (GCMC) simulations were performed to investigate hydrogen sorption in an rht-type metal-organic framework (MOF), PCN-61. The MOF was shown to have a large hydrogen uptake, and this was studied using three different hydrogen potentials, effective for bulk hydrogen, but of varying sophistication: a model that includes only repulsion/dispersion parameters, one augmented with charge-quadrupole interactions, and one supplemented with many-body polarization interactions. Calculated hydrogen uptake isotherms and isosteric heats of adsorption, Q st, were in quantitative agreement with experiment only for the model with explicit polarization. This success in reproducing empirical measurements suggests that modeling MOFs that have open metal sites is feasible, though it is often not considered to be well described via a classical potential function; here it is shown that such systems may be accurately described by explicitly including polarization effects in an otherwise traditional empirical potential. Decomposition of energy terms for the models revealed deviations between the electrostatic and polarizable results that are unexpected due to just the augmentation of the potential surface by the addition of induction. Charge-quadrupole and induction energetics were shown to have a synergistic interaction, with inclusion of the latter resulting in a significant increase in the former. Induction interactions strongly influence the structure of the sorbed hydrogen compared to the models lacking polarizability; sorbed hydrogen is a dipolar dense fluid in the MOF. This study demonstrates that many-body polarization makes a critical contribution to gas sorption structure and must be accounted for in modeling MOFs with polar interaction sites. © 2012 American Chemical Society.

  17. On-site SiH4 generator using hydrogen plasma generated in slit-type narrow gap

    Science.gov (United States)

    Takei, Norihisa; Shinoda, Fumiya; Kakiuchi, Hiroaki; Yasutake, Kiyoshi; Ohmi, Hiromasa

    2018-06-01

    We have been developing an on-site silane (SiH4) generator based on use of the chemical etching reaction between solid silicon (Si) and the high-density H atoms that are generated in high-pressure H2 plasma. In this study, we have developed a slit-type plasma source for high-efficiency SiH4 generation. High-density H2 plasma was generated in a narrow slit-type discharge gap using a 2.45 GHz microwave power supply. The plasma’s optical emission intensity distribution along the slit was measured and the resulting distribution was reflected by both the electric power distribution and the hydrogen gas flow. Because the Si etching rate strongly affects the SiH4 generation rate, the Si etching behavior was investigated with respect to variations in the experimental parameters. The weight etch rate increased monotonically with increasing input microwave power. However, the weight etch rate decreased with increasing H2 pressure and an increasing plasma gap. This reduction in the etch rate appears to be related to shrinkage of the plasma generation area because increased input power is required to maintain a constant plasma area with increasing H2 pressure and the increasing plasma gap. Additionally, the weight etch rate also increases with increasing H2 flow rate. The SiH4 generation rate of the slit-type plasma source was also evaluated using gas-phase Fourier transform infrared absorption spectroscopy and the material utilization efficiencies of both Si and the H2 gas for SiH4 gas formation were discussed. The main etch product was determined to be SiH4 and the developed plasma source achieved a SiH4 generation rate of 10 sccm (standard cubic centimeters per minute) at an input power of 900 W. In addition, the Si utilization efficiency exceeded 60%.

  18. INTEGRAL FIELD SPECTROSCOPY OF SUPERNOVA EXPLOSION SITES: CONSTRAINING THE MASS AND METALLICITY OF THE PROGENITORS. I. TYPE Ib AND Ic SUPERNOVAE

    Energy Technology Data Exchange (ETDEWEB)

    Kuncarayakti, Hanindyo; Maeda, Keiichi [Kavli Institute for the Physics and Mathematics of the Universe (WPI), Todai Institutes for Advanced Study, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan); Doi, Mamoru; Morokuma, Tomoki; Hashiba, Yasuhito [Institute of Astronomy, Graduate School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Aldering, Greg [Physics Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Arimoto, Nobuo [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Pereira, Rui [CNRS/IN2P3, Institut de Physique Nucleaire de Lyon, 4 Rue Enrico Fermi, F-69622 Villeurbanne Cedex (France); Usuda, Tomonori, E-mail: hanindyo.kuncarayakti@ipmu.jp [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A' ohoku Place, Hilo, HI 96720 (United States)

    2013-08-01

    Integral field spectroscopy of 11 Type Ib/Ic supernova (SN Ib/Ic) explosion sites in nearby galaxies has been obtained using UH88/SNIFS and Gemini-N/GMOS. The use of integral field spectroscopy enables us to obtain both spatial and spectral information about the explosion site, enabling the identification of the parent stellar population of the SN progenitor star. The spectrum of the parent population provides metallicity determination via strong-line method and age estimation obtained via comparison with simple stellar population models. We adopt this information as the metallicity and age of the SN progenitor, under the assumption that it was coeval with the parent stellar population. The age of the star corresponds to its lifetime, which in turn gives the estimate of its initial mass. With this method we were able to determine both the metallicity and initial (zero-age main sequence) mass of the progenitor stars of SNe Ib and Ic. We found that on average SN Ic explosion sites are more metal-rich and younger than SN Ib sites. The initial mass of the progenitors derived from parent stellar population age suggests that SN Ic has more massive progenitors than SN Ib. In addition, we also found indication that some of our SN progenitors are less massive than {approx}25 M{sub Sun }, indicating that they may have been stars in a close binary system that have lost their outer envelope via binary interactions to produce SNe Ib/Ic, instead of single Wolf-Rayet stars. These findings support the current suggestions that both binary and single progenitor channels are in effect in producing SNe Ib/Ic. This work also demonstrates the power of integral field spectroscopy in investigating SN environments and active star-forming regions.

  19. A new multi-gas constrained model of trace gas non-homogeneous transport in firn: evaluation and behaviour at eleven polar sites

    Directory of Open Access Journals (Sweden)

    E. Witrant

    2012-12-01

    Full Text Available Insoluble trace gases are trapped in polar ice at the firn-ice transition, at approximately 50 to 100 m below the surface, depending primarily on the site temperature and snow accumulation. Models of trace gas transport in polar firn are used to relate firn air and ice core records of trace gases to their atmospheric history. We propose a new model based on the following contributions. First, the firn air transport model is revised in a poromechanics framework with emphasis on the non-homogeneous properties and the treatment of gravitational settling. We then derive a nonlinear least square multi-gas optimisation scheme to calculate the effective firn diffusivity (automatic diffusivity tuning. The improvements gained by the multi-gas approach are investigated (up to ten gases for a single site are included in the optimisation process. We apply the model to four Arctic (Devon Island, NEEM, North GRIP, Summit and seven Antarctic (DE08, Berkner Island, Siple Dome, Dronning Maud Land, South Pole, Dome C, Vostok sites and calculate their respective depth-dependent diffusivity profiles. Among these different sites, a relationship is inferred between the snow accumulation rate and an increasing thickness of the lock-in zone defined from the isotopic composition of molecular nitrogen in firn air (denoted δ15N. It is associated with a reduced diffusivity value and an increased ratio of advective to diffusive flux in deep firn, which is particularly important at high accumulation rate sites. This has implications for the understanding of δ15N of N2 records in ice cores, in relation with past variations of the snow accumulation rate. As the snow accumulation rate is clearly a primary control on the thickness of the lock-in zone, our new approach that allows for the estimation of the lock-in zone width as a function of accumulation may lead to a better constraint on the age difference between the ice and entrapped gases.

  20. Understanding Hydrogen Sorption in In- soc -MOF: A Charged Metal-Organic Framework with Open-Metal Sites, Narrow Channels, and Counterions

    KAUST Repository

    Pham, Tony

    2015-03-04

    © 2015 American Chemical Society. Grand canonical Monte Carlo (GCMC) simulations of hydrogen sorption were performed in In-soc-MOF, a charged metal-organic framework (MOF) that contains In3O trimers coordinated to 5,5′-azobis(1,3-benzenedicarboxylate) linkers. The MOF contains nitrate counterions that are located in carcerand-like capsules of the framework. This MOF was shown to have a high hydrogen uptake at 77 K and 1.0 atm. The simulations were performed with a potential that includes explicit many-body polarization interactions, which were important for modeling gas sorption in a charged/polar MOF such as In-soc-MOF. The simulated hydrogen sorption isotherms were in good agreement with experiment in this challenging platform for modeling. The simulations predict a high initial isosteric heat of adsorption, Qst, value of about 8.5 kJ mol-1, which is in contrast to the experimental value of 6.5 kJ mol-1 for all loadings. The difference in the Qst behavior between experiment and simulation is attributed to the fact that, in experimental measurements, the sorbate molecules cannot access the isolated cages containing the nitrate ions, the most energetically favorable site in the MOF, at low pressures due to an observed diffusion barrier. In contrast, the simulations were able to capture the sorption of hydrogen onto the nitrate ions at low loading due to the equilibrium nature of GCMC simulations. The experimental Qst values were reproduced in simulation by blocking access to all of the nitrate ions in the MOF. Furthermore, at 77 K, the sorbed hydrogen molecules were reminiscent of a dense fluid in In-soc-MOF starting at approximately 5.0 atm, and this was verified by monitoring the isothermal compressibility, βT, values. The favorable sites for hydrogen sorption were identified from the polarization distribution as the nitrate ions, the In3O trimers, and the azobenzene nitrogen atoms. Lastly, the two-dimensional quantum rotational levels

  1. Simulations of hydrogen sorption in rht-MOF-1: identifying the binding sites through explicit polarization and quantum rotation calculations

    KAUST Repository

    Pham, Tony; Forrest, Katherine A.; Hogan, Adam; McLaughlin, Keith; Belof, Jonathan L.; Eckert, Juergen; Space, Brian

    2014-01-01

    . This is a charged rht-MOF that contains extra-framework nitrate counterions within the material. For the simulations performed herein, excellent agreement with experiment was achieved for the simulated hydrogen sorption isotherms and calculated isosteric

  2. Stable isotopes of hydrogen and oxygen in surface water and ground water at selected sites on or near the Idaho National Engineering Laboratory, Idaho

    International Nuclear Information System (INIS)

    Ott, D.S.; Cecil, L.D.; Knobel, L.L.

    1994-01-01

    Relative stable isotopic ratios for hydrogen and oxygen compared to standard mean ocean water are presented for water from 4 surface-water sites and 38 ground-water sites on or near the Idaho National Engineering Laboratory (INEL). The surface-water samples were collected monthly from March 1991 through April 1992 and after a storm event on June 18, 1992. The ground-water samples either were collected during 1991 or 1992. These data were collected as part of the US Geological Survey's continuing hydrogeological investigations at the INEL. The relative isotopic ratios of hydrogen and oxygen are reported as delta 2 H (δ 2 H) and as delta 18 O (δ 18 O), respectively. The values of δ 2 H and δ 18 O in water from the four surface-water sites ranged from -143.0 to -122 and from -18.75 to -15.55, respectively. The values of δ 2 H and δ 18 O in water from the 38 ground-water sites ranged from -141.0 to -120.0 and from -18.55 to -14.95, respectively

  3. Hydrogen Evolution and Sludge Suspension During the Preparation of the First Batch of Sludge at the Savannah River Site

    International Nuclear Information System (INIS)

    Hay, M.S.; Lee, E.D.

    1995-01-01

    The first batch of High Level Radioactive Sludge for the Defense Waste Processing Facility is being prepared in two 4.9 million liter waste tanks. The preparation involves removing water soluble salts by washing (water addition, sludge suspension, settling and decantation). Sludge suspension is accomplished using long shafted slurry pumps that are mounted on rotating turntables. During the sludge suspension runs in 1993 and 1994, the slurry pumps' cleaning radius was determined to be less than that expected from previous determinations using synthetic sludge in a full size waste tank mockup. Hydrogen concentrations in the tanks' vapor space were monitored during the sludge suspension activities. As expected, the initial agitation of the sludge increased the hydrogen concentration, however, with the controls in place the hydrogen concentration was maintained below seven percent of the lower flammability limit

  4. Development of Next-Generation Borehole Magnetometer and Its Potential Application in Constraining the Magnetic Declination of Oman Samail Ophiolite at ICDP Drill Sites

    Science.gov (United States)

    Lee, S. M.; Parq, J. H.; Kim, H.; Moe, K.; Lee, C. S.; Kanamatsu, T.; Kim, K. J.; Bahk, K. S.

    2017-12-01

    Determining the azimuthal orientation of core samples obtained from deep drilling is extremely difficult because the core itself could have rotated during drilling operations. Several indirect methods have been devised to address this issue, but have certain limitations. Thus it is still a challenge to determine the azimuthal orientation consistently over the entire length of the hole. Provided that the recovery rate is high and thus all the other magnetic properties such as magnetization intensity and inclination are measured from the recovered cores, one possible method for ascertaining magnetic declination information is to measure the magnetic field inside the empty borehole and invert for the best fitting declination. However, there are two major problems: one is that present-day borehole magnetometers are not precise enough to resolve changes in direction of magnetization, and the other is that in most rock drilling experiments the rate of recovery is low. To overcome the first major problem which is technical, scientists from Korea and Japan jointly conducted the development for the next-generation borehole magnetometer, namely 3GBM (3rd Generation Borehole Magnetometer). The borehole magnetometer which uses fiber-optic laser gyro promises to provide accurate information on not only the magnetic field itself but also the orientation of the instrument inside the borehole. Our goal is to deploy this borehole magnetometer in the ICDP Oman Drilling Project Phase 2 drilling experiment early 2018. The site may be suitable for the investigation because, as recent Phase 1 of the Oman Samail Ophiolite drilling has demonstrated, the recovery rate was very high. Also the post-drilling measurements onboard DV Chikyu have shown that much of the recovered samples has moderate magnetization intensity on the order of 0.1 and 1 A/m. Here, we present the results of numerical simulation of magnetic field inside the borehole using finite element method to show that magnetic

  5. Optimizing the deposition of hydrogen evolution sites on suspended semiconductor particles using on-line photocatalytic reforming of aqueous methanol solutions.

    Science.gov (United States)

    Busser, G Wilma; Mei, Bastian; Muhler, Martin

    2012-11-01

    The deposition of hydrogen evolution sites on photocatalysts is a crucial step in the multistep process of synthesizing a catalyst that is active for overall photocatalytic water splitting. An alternative approach to conventional photodeposition was developed, applying the photocatalytic reforming of aqueous methanol solutions to deposit metal particles on semiconductor materials such as Ga₂O₃ and (Ga₀.₆ Zn₀.₄)(N₀.₆O₀.₄). The method allows optimizing the loading of the co-catalysts based on the stepwise addition of their precursors and the continuous online monitoring of the evolved hydrogen. Moreover, a synergetic effect between different co-catalysts can be directly established. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. [NiFe] hydrogenase structural and functional models: new bio-inspired catalysts for hydrogen evolution; Modeles structuraux et fonctionnels du site actif des hydrogenases [NiFe]: de nouveaux catalyseurs bio-inspires pour la production d'hydrogene

    Energy Technology Data Exchange (ETDEWEB)

    Oudart, Y

    2006-09-15

    Hydrogenase enzymes reversibly catalyze the oxidation and production of hydrogen in a range close to the thermodynamic potential. The [NiFe] hydrogenase active site contains an iron-cyano-carbonyl moiety linked to a nickel atom which is in an all sulphur environment. Both the active site originality and the potential development of an hydrogen economy make the synthesis of functional and structural models worthy. To take up this challenge, we have synthesised mononuclear ruthenium models and more importantly, nickel-ruthenium complexes, mimicking some structural features of the [NiFe] hydrogenase active site. Ruthenium is indeed isoelectronic to iron and some of its complexes are well-known to bear hydrides. The compounds described in this study have been well characterised and their activity in proton reduction has been successfully tested. Most of them are able to catalyze this reaction though their electrocatalytic potentials remain much more negative compared to which of platinum. The studied parameters point out the importance of the complexes electron richness, especially of the nickel environment. Furthermore, the proton reduction activity is stable for several hours at good rates. The ruthenium environment seems important for this stability. Altogether, these compounds represent the very first catalytically active [NiFe] hydrogenase models. Important additional results of this study are the synergetic behaviour of the two metals in protons reduction and the evidence of a protonation step as the limiting step of the catalytic cycle. We have also shown that a basic site close to ruthenium improves the electrocatalytic potential of the complexes. (author)

  7. Sites involved in intra- and interdomain allostery associated with the activation of factor VIIa pinpointed by hydrogen-deuterium exchange and electron transfer dissociation mass spectrometry.

    Science.gov (United States)

    Song, Hongjian; Olsen, Ole H; Persson, Egon; Rand, Kasper D

    2014-12-19

    Factor VIIa (FVIIa) is a trypsin-like protease that plays an important role in initiating blood coagulation. Very limited structural information is available for the free, inactive form of FVIIa that circulates in the blood prior to vascular injury and the molecular details of its activity enhancement remain elusive. Here we have applied hydrogen/deuterium exchange mass spectrometry coupled to electron transfer dissociation to pinpoint individual residues in the heavy chain of FVIIa whose conformation and/or local interaction pattern changes when the enzyme transitions to the active form, as induced either by its cofactor tissue factor or a covalent active site inhibitor. Identified regulatory residues are situated at key sites across one continuous surface of the protease domain spanning the TF-binding helix across the activation pocket to the calcium binding site and are embedded in elements of secondary structure and at the base of flexible loops. Thus these residues are optimally positioned to mediate crosstalk between functional sites in FVIIa, particularly the cofactor binding site and the active site. Our results unambiguously show that the conformational allosteric activation signal extends to the EGF1 domain in the light chain of FVIIa, underscoring a remarkable intra- and interdomain allosteric regulation of this trypsin-like protease. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  8. Hydrogen bonding between the QB site ubisemiquinone and Ser-L223 in the bacterial reaction centre – a combined spectroscopic and computational perspective^

    OpenAIRE

    Martin, Erik; Baldansuren, Amgalanbaatar; Lin, Tzu-Jen; Samoilova, Rimma I.; Wraight, Colin A.; Dikanov, Sergei A.; O’Malley, Patrick J.

    2012-01-01

    In the QB site of the Rba. sphaeroides photosynthetic reaction centre the donation of a hydrogen bond from the hydroxyl group of Ser-L223 to the ubisemiquinone formed after the first flash is debatable. In this study we use a combination of spectroscopy and quantum mechanics/molecular mechanics (QM/MM) calculations to comprehensively explore this topic. We show that ENDOR, ESEEM and HYSCORE spectroscopic differences between the mutant L223SA and the wild type sample (WT) are negligible, indic...

  9. Evolutionary constrained optimization

    CERN Document Server

    Deb, Kalyanmoy

    2015-01-01

    This book makes available a self-contained collection of modern research addressing the general constrained optimization problems using evolutionary algorithms. Broadly the topics covered include constraint handling for single and multi-objective optimizations; penalty function based methodology; multi-objective based methodology; new constraint handling mechanism; hybrid methodology; scaling issues in constrained optimization; design of scalable test problems; parameter adaptation in constrained optimization; handling of integer, discrete and mix variables in addition to continuous variables; application of constraint handling techniques to real-world problems; and constrained optimization in dynamic environment. There is also a separate chapter on hybrid optimization, which is gaining lots of popularity nowadays due to its capability of bridging the gap between evolutionary and classical optimization. The material in the book is useful to researchers, novice, and experts alike. The book will also be useful...

  10. Fabrication of efficient TiO2-RGO heterojunction composites for hydrogen generation via water-splitting: Comparison between RGO, Au and Pt reduction sites

    Science.gov (United States)

    El-Bery, Haitham M.; Matsushita, Yoshihisa; Abdel-moneim, Ahmed

    2017-11-01

    A facile one-step synthesis approach of M/TiO2/RGO (M = Au or Pt) ternary composite by hydrothermal treatment for hydrogen generation via water-splitting was investigated. Photocurrent response measurements revealed that TiO2 (P25) nanoparticles anchored on the reduced graphene oxide (RGO) surface exhibited a p-n heterojunction interface by changing the photocurrent direction with the applied bias from reverse to forward potential. H2 evolution rate of TiO2/RGO (5 wt.%) composite was substantially enhanced by 12-fold in comparison to bare TiO2 under simulated solar light irradiation. Cyclic volatmmetry measurements manifested, that the optimized 0.3 wt.% of platinum metal loaded on TiO2/RGO composite was the most active catalytic reduction sites for hydrogen generation reaction with an initial hydrogen rate of 670 μmol h-1. This study sheds the light on the tunable semiconductor type of TiO2/RGO composite fabricated by solution mixing pathway and its merits to improve the photocatalytic activity.

  11. Exploring Constrained Creative Communication

    DEFF Research Database (Denmark)

    Sørensen, Jannick Kirk

    2017-01-01

    Creative collaboration via online tools offers a less ‘media rich’ exchange of information between participants than face-to-face collaboration. The participants’ freedom to communicate is restricted in means of communication, and rectified in terms of possibilities offered in the interface. How do...... these constrains influence the creative process and the outcome? In order to isolate the communication problem from the interface- and technology problem, we examine via a design game the creative communication on an open-ended task in a highly constrained setting, a design game. Via an experiment the relation...... between communicative constrains and participants’ perception of dialogue and creativity is examined. Four batches of students preparing for forming semester project groups were conducted and documented. Students were asked to create an unspecified object without any exchange of communication except...

  12. Choosing health, constrained choices.

    Science.gov (United States)

    Chee Khoon Chan

    2009-12-01

    In parallel with the neo-liberal retrenchment of the welfarist state, an increasing emphasis on the responsibility of individuals in managing their own affairs and their well-being has been evident. In the health arena for instance, this was a major theme permeating the UK government's White Paper Choosing Health: Making Healthy Choices Easier (2004), which appealed to an ethos of autonomy and self-actualization through activity and consumption which merited esteem. As a counterpoint to this growing trend of informed responsibilization, constrained choices (constrained agency) provides a useful framework for a judicious balance and sense of proportion between an individual behavioural focus and a focus on societal, systemic, and structural determinants of health and well-being. Constrained choices is also a conceptual bridge between responsibilization and population health which could be further developed within an integrative biosocial perspective one might refer to as the social ecology of health and disease.

  13. Constrained superfields in supergravity

    Energy Technology Data Exchange (ETDEWEB)

    Dall’Agata, Gianguido; Farakos, Fotis [Dipartimento di Fisica ed Astronomia “Galileo Galilei”, Università di Padova,Via Marzolo 8, 35131 Padova (Italy); INFN, Sezione di Padova,Via Marzolo 8, 35131 Padova (Italy)

    2016-02-16

    We analyze constrained superfields in supergravity. We investigate the consistency and solve all known constraints, presenting a new class that may have interesting applications in the construction of inflationary models. We provide the superspace Lagrangians for minimal supergravity models based on them and write the corresponding theories in component form using a simplifying gauge for the goldstino couplings.

  14. Minimal constrained supergravity

    Energy Technology Data Exchange (ETDEWEB)

    Cribiori, N. [Dipartimento di Fisica e Astronomia “Galileo Galilei”, Università di Padova, Via Marzolo 8, 35131 Padova (Italy); INFN, Sezione di Padova, Via Marzolo 8, 35131 Padova (Italy); Dall' Agata, G., E-mail: dallagat@pd.infn.it [Dipartimento di Fisica e Astronomia “Galileo Galilei”, Università di Padova, Via Marzolo 8, 35131 Padova (Italy); INFN, Sezione di Padova, Via Marzolo 8, 35131 Padova (Italy); Farakos, F. [Dipartimento di Fisica e Astronomia “Galileo Galilei”, Università di Padova, Via Marzolo 8, 35131 Padova (Italy); INFN, Sezione di Padova, Via Marzolo 8, 35131 Padova (Italy); Porrati, M. [Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States)

    2017-01-10

    We describe minimal supergravity models where supersymmetry is non-linearly realized via constrained superfields. We show that the resulting actions differ from the so called “de Sitter” supergravities because we consider constraints eliminating directly the auxiliary fields of the gravity multiplet.

  15. Minimal constrained supergravity

    Directory of Open Access Journals (Sweden)

    N. Cribiori

    2017-01-01

    Full Text Available We describe minimal supergravity models where supersymmetry is non-linearly realized via constrained superfields. We show that the resulting actions differ from the so called “de Sitter” supergravities because we consider constraints eliminating directly the auxiliary fields of the gravity multiplet.

  16. Minimal constrained supergravity

    International Nuclear Information System (INIS)

    Cribiori, N.; Dall'Agata, G.; Farakos, F.; Porrati, M.

    2017-01-01

    We describe minimal supergravity models where supersymmetry is non-linearly realized via constrained superfields. We show that the resulting actions differ from the so called “de Sitter” supergravities because we consider constraints eliminating directly the auxiliary fields of the gravity multiplet.

  17. A-site order–disorder in the NdBaMn2O5+δ SOFC electrode material monitored in situ by neutron diffraction under hydrogen flow

    KAUST Repository

    Tonus, Florent

    2017-05-11

    The A-site disordered perovskite manganite, Nd0.5Ba0.5MnO3, has been obtained by heating the A-site-ordered and vacancy ordered layered double perovskite, NdBaMn2O5, in air at 1300 °C for 5 h. Combined transmission electron microscopy (TEM) images and neutron powder diffraction (NPD) analysis at 25 °C revealed that Nd0.5Ba0.5MnO3 has a pseudotetragonal unit cell with orthorhombic symmetry (space group Imma, √2ap × 2ap × √2ap) at 20 °C with the cell dimensions a = 5.503(1) Å, b = 7.7962(4) Å, c = 5.502(1) Å, in contrast to Pm[3 with combining macron]m or Cmcm that have been previously stated from X-ray diffraction studies. The in situ neutron diffraction study carried out on Nd0.5Ba0.5MnO3 in hydrogen flow up to T ∼ 900 °C, allows monitoring the A-site cation disorder–order structural phase transition of this representative member of potential SOFC anode materials between air sintering conditions and hydrogen working conditions. Oxygen loss from Nd0.5Ba0.5MnO3 proceeds with retention of A-site disorder until the oxygen content reaches the Nd0.5Ba0.5MnO2.5 composition at 600 °C. The phase transition to layered NdBaMn2O5 and localization of the oxygen vacancies in the Nd layer proceeds at 800 °C with retention of the oxygen content. Impedance spectroscopy measurements for the oxidized A-site ordered electrode material, NdBaMn2O6, screen printed on a Ce0.9Gd0.1O2−δ (CGO) electrolyte showed promising electrochemical performance in air at 700 °C with a polarization resistance of 1.09 Ω cm2 without any optimization.

  18. How HE (Hydrogen Energy) Knowledge and Innovativeness Affect Potential Innovators' Acceptance and Opinions Regarding HE An example from UNIDO-ICHET Web-site Users

    International Nuclear Information System (INIS)

    Mavis Tsai; Scott Warren; Reide Song; JingYi Gao

    2006-01-01

    According to innovation diffusion research, the innovators, opinion leaders, and diffusion agents play vital roles in promoting the acceptance of innovation. The purpose of this research is to investigate how HE innovators' knowledge affects their acceptance and opinions about HE and related products. The research method is an on-line survey and the sample is a voluntary sample. This survey successfully collected 1126 HE innovators' information. The researchers used SPSS statistics software to analyze the data and found the relationship between HE innovators' demographics, their knowledge about hydrogen energy, their innovativeness, and their familiarity with new energy technology with their acceptance and opinions about HE, and how they use the UNIDO-ICHET web-site. The researchers found HE knowledge could be used to predict new energy innovators' information resource usage, innovativeness, new energy product adoption and their opinions about HE. (authors)

  19. Hydrogen energy

    International Nuclear Information System (INIS)

    2005-03-01

    This book consists of seven chapters, which deals with hydrogen energy with discover and using of hydrogen, Korean plan for hydrogen economy and background, manufacturing technique on hydrogen like classification and hydrogen manufacture by water splitting, hydrogen storage technique with need and method, hydrogen using technique like fuel cell, hydrogen engine, international trend on involving hydrogen economy, technical current for infrastructure such as hydrogen station and price, regulation, standard, prospect and education for hydrogen safety and system. It has an appendix on related organization with hydrogen and fuel cell.

  20. Hydrogen molecules and hydrogen-related defects in crystalline silicon

    Science.gov (United States)

    Fukata, N.; Sasaki, S.; Murakami, K.; Ishioka, K.; Nakamura, K. G.; Kitajima, M.; Fujimura, S.; Kikuchi, J.; Haneda, H.

    1997-09-01

    We have found that hydrogen exists in molecular form in crystalline silicon treated with hydrogen atoms in the downstream of a hydrogen plasma. The vibrational Raman line of hydrogen molecules is observed at 4158 cm-1 for silicon samples hydrogenated between 180 and 500 °C. The assignment of the Raman line is confirmed by its isotope shift to 2990 cm-1 for silicon treated with deuterium atoms. The Raman intensity has a maximum for hydrogenation at 400 °C. The vibrational Raman line of the hydrogen molecules is broad and asymmetric. It consists of at least two components, possibly arising from hydrogen molecules in different occupation sites in crystalline silicon. The rotational Raman line of hydrogen molecules is observed at 590 cm-1. The Raman band of Si-H stretching is observed for hydrogenation temperatures between 100 and 500 °C and the intensity has a maximum for hydrogenation at 250 °C.

  1. Constrained Vapor Bubble Experiment

    Science.gov (United States)

    Gokhale, Shripad; Plawsky, Joel; Wayner, Peter C., Jr.; Zheng, Ling; Wang, Ying-Xi

    2002-11-01

    Microgravity experiments on the Constrained Vapor Bubble Heat Exchanger, CVB, are being developed for the International Space Station. In particular, we present results of a precursory experimental and theoretical study of the vertical Constrained Vapor Bubble in the Earth's environment. A novel non-isothermal experimental setup was designed and built to study the transport processes in an ethanol/quartz vertical CVB system. Temperature profiles were measured using an in situ PC (personal computer)-based LabView data acquisition system via thermocouples. Film thickness profiles were measured using interferometry. A theoretical model was developed to predict the curvature profile of the stable film in the evaporator. The concept of the total amount of evaporation, which can be obtained directly by integrating the experimental temperature profile, was introduced. Experimentally measured curvature profiles are in good agreement with modeling results. For microgravity conditions, an analytical expression, which reveals an inherent relation between temperature and curvature profiles, was derived.

  2. Constrained noninformative priors

    International Nuclear Information System (INIS)

    Atwood, C.L.

    1994-10-01

    The Jeffreys noninformative prior distribution for a single unknown parameter is the distribution corresponding to a uniform distribution in the transformed model where the unknown parameter is approximately a location parameter. To obtain a prior distribution with a specified mean but with diffusion reflecting great uncertainty, a natural generalization of the noninformative prior is the distribution corresponding to the constrained maximum entropy distribution in the transformed model. Examples are given

  3. Application of site-specific natural isotope fractionation (SNIF-NMR) of hydrogen to the characterization of European beers

    International Nuclear Information System (INIS)

    Martin, G.J.; Benbernou, M.; Lantier, F.

    1985-01-01

    More than one hundred samples of European beers have been investigated by the new SNIF-NMR method which is based on 2H NMR at the natural abundance level and enables site-specific natural isotope fractionation factors in ethanol to be determined. The relative (R) and absolute (D/H)sub(i) parameters are shown to be characteristic of the country where the beers are brewed and the observed variations are explained in terms of cereal composition, water resource, and manufacturing processing (fermentation, yeast, temperature cycle). These new parameters find analytical and mechanistic applications in the identification of a beer and in the investigation of a fermentation process. (author)

  4. The first direct observation of hydrogen trapping sites in TiC precipitation-hardening steel through atom probe tomography

    International Nuclear Information System (INIS)

    Takahashi, Jun; Kawakami, Kazuto; Kobayashi, Yukiko; Tarui, Toshimi

    2010-01-01

    For the first time ever, atomic-scale direct observation of deuterium atoms trapping at nano-sized titanium carbide (TiC) precipitates in steel was successfully achieved using atom probe tomography (APT). Deuterium gas charging into the needle specimen and subsequently quenching were conducted in our designed chamber attached to three-dimensional atom probe (3DAP). The deuterium atoms were definitely observed on the broad surface of TiC platelets, which indicated that the broad interface between the matrix and TiC was the main trapping site.

  5. Hydrogen peroxide (H2O2) irreversibly inactivates creatine kinase from Pelodiscus sinensis by targeting the active site cysteine.

    Science.gov (United States)

    Wang, Wei; Lee, Jinhyuk; Hao, Hao; Park, Yong-Doo; Qian, Guo-Ying

    2017-12-01

    Creatine kinase (EC 2.7.3.2, CK) plays an important role in cellular energy metabolism and homeostasis by catalysing the transfer of phosphate between ATP and creatine phosphate. In this study, we investigated the effects of H 2 O 2 on PSCKM (muscle type creatine kinase from Pelodiscus sinensis) by the integrating method between enzyme kinetics and docking simulations. We found that H 2 O 2 strongly inactivated PSCKM (IC 50 =0.25mM) in a first-order kinetic process, and targeted the active site cysteine directly. A conformational study showed that H 2 O 2 did not induce the tertiary structural changes in PSCKM with no extensive exposure of hydrophobic surfaces. Sequential docking simulations between PSCKM and H 2 O 2 indicated that H 2 O 2 interacts with the ADP binding region of the active site, consistent with experimental results that demonstrated H 2 O 2 -induced inactivation. Our study demonstrates the effect of H 2 O 2 on PSCKM enzymatic function and unfolding, and provides important insight into the changes undergone by this central metabolic enzyme in ectothermic animals in response to the environment. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Constrained reaction volume approach for studying chemical kinetics behind reflected shock waves

    KAUST Repository

    Hanson, Ronald K.; Pang, Genny A.; Chakraborty, Sreyashi; Ren, Wei; Wang, Shengkai; Davidson, David Frank

    2013-01-01

    We report a constrained-reaction-volume strategy for conducting kinetics experiments behind reflected shock waves, achieved in the present work by staged filling in a shock tube. Using hydrogen-oxygen ignition experiments as an example, we

  7. Ring-constrained Join

    DEFF Research Database (Denmark)

    Yiu, Man Lung; Karras, Panagiotis; Mamoulis, Nikos

    2008-01-01

    . This new operation has important applications in decision support, e.g., placing recycling stations at fair locations between restaurants and residential complexes. Clearly, RCJ is defined based on a geometric constraint but not on distances between points. Thus, our operation is fundamentally different......We introduce a novel spatial join operator, the ring-constrained join (RCJ). Given two sets P and Q of spatial points, the result of RCJ consists of pairs (p, q) (where p ε P, q ε Q) satisfying an intuitive geometric constraint: the smallest circle enclosing p and q contains no other points in P, Q...

  8. Hydrophobic fluorine mediated switching of the hydrogen bonding site as well as orientation of water molecules in the aqueous mixture of monofluoroethanol: IR, molecular dynamics and quantum chemical studies.

    Science.gov (United States)

    Mondal, Saptarsi; Biswas, Biswajit; Nandy, Tonima; Singh, Prashant Chandra

    2017-09-20

    The local structures between water-water, alcohol-water and alcohol-alcohol have been investigated for aqueous mixtures of ethanol (ETH) and monofluoroethanol (MFE) by the deconvolution of IR bands in the OH stretching region, molecular dynamics simulation and quantum chemical calculations. It has been found that the addition of a small amount of ETH into the aqueous medium increases the strength of the hydrogen bonds between water molecules. In an aqueous mixture of MFE, the substitution of a single fluorine induces a change in the orientation as well as the hydrogen bonding site of water molecules from the oxygen to the fluorine terminal of MFE. The switching of the hydrogen bonding site of water in the aqueous mixture of MFE results in comparatively strong hydrogen bonds between MFE and water molecules as well as less clustering of water molecules, unlike the case of the aqueous mixture of ETH. These findings about the modification of a hydrogen bond network by the hydrophobic fluorine group probably make fluorinated molecules useful for pharmaceutical as well as biological applications.

  9. Sharp spatially constrained inversion

    DEFF Research Database (Denmark)

    Vignoli, Giulio G.; Fiandaca, Gianluca G.; Christiansen, Anders Vest C A.V.C.

    2013-01-01

    We present sharp reconstruction of multi-layer models using a spatially constrained inversion with minimum gradient support regularization. In particular, its application to airborne electromagnetic data is discussed. Airborne surveys produce extremely large datasets, traditionally inverted...... by using smoothly varying 1D models. Smoothness is a result of the regularization constraints applied to address the inversion ill-posedness. The standard Occam-type regularized multi-layer inversion produces results where boundaries between layers are smeared. The sharp regularization overcomes...... inversions are compared against classical smooth results and available boreholes. With the focusing approach, the obtained blocky results agree with the underlying geology and allow for easier interpretation by the end-user....

  10. Enhancement of Ag-Based Plasmonic Photocatalysis in Hydrogen Production from Ammonia Borane by the Assistance of Single-Site Ti-Oxide Moieties within a Silica Framework.

    Science.gov (United States)

    Verma, Priyanka; Kuwahara, Yasutaka; Mori, Kohsuke; Yamashita, Hiromi

    2017-03-13

    Ag nanoparticles (NPs) have gained great attention owing to their interesting plasmonic properties and efficient catalysis under visible-light irradiation. In this study, an Ag-based plasmonic catalyst supported on mesoporous silica with isolated and tetrahedrally coordinated single-site Ti-oxide moieties, namely, Ag/Ti-SBA-15, was designed with the purpose of utilizing the broad spectral range of solar energy. The Ti-SBA-15 support allows the deposition of small Ag NPs with a narrow size distribution. The chemical structure, morphology, and optical properties of the prepared catalyst were characterized by techniques such as UV/Vis, FT extended X-ray absorption fine structure, and X-ray photoelectron spectroscopy, field-emission SEM, TEM, and N 2 physisorption studies. The catalytic activity of Ag/Ti-SBA-15 in hydrogen production from ammonia borane by hydrolysis was significantly enhanced in comparison with Ag/SBA-15 without Ti-oxide moieties and Ag/TiO 2 /SBA-15 involving agglomerated TiO 2 , both in the dark and under light irradiation. Improved electron transfer under light irradiation caused by the creation of heterojunctions between Ag NPs and Ti-oxide moieties explains the results obtained in the present study. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Hydrogen sensor

    Science.gov (United States)

    Duan, Yixiang; Jia, Quanxi; Cao, Wenqing

    2010-11-23

    A hydrogen sensor for detecting/quantitating hydrogen and hydrogen isotopes includes a sampling line and a microplasma generator that excites hydrogen from a gas sample and produces light emission from excited hydrogen. A power supply provides power to the microplasma generator, and a spectrometer generates an emission spectrum from the light emission. A programmable computer is adapted for determining whether or not the gas sample includes hydrogen, and for quantitating the amount of hydrogen and/or hydrogen isotopes are present in the gas sample.

  12. Hydrogenation properties of Mg1-xM1xCu2 (M1=La and Nd) with larger interstitial sites than MgCu2

    International Nuclear Information System (INIS)

    Tsushio, Y.

    1998-01-01

    The hydrogenation properties of C15 compounds are controlled by crystal structure, the size of the interstitial hole being an especially important factor. Its effect on the hydrogenation properties of MgCu 2 substituted with rare earth elements of various radii is discussed and the limit in controlling the crystal structure by conventional substitution is explained. (orig.)

  13. Early cosmology constrained

    Energy Technology Data Exchange (ETDEWEB)

    Verde, Licia; Jimenez, Raul [Institute of Cosmos Sciences, University of Barcelona, IEEC-UB, Martí Franquès, 1, E08028 Barcelona (Spain); Bellini, Emilio [University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH (United Kingdom); Pigozzo, Cassio [Instituto de Física, Universidade Federal da Bahia, Salvador, BA (Brazil); Heavens, Alan F., E-mail: liciaverde@icc.ub.edu, E-mail: emilio.bellini@physics.ox.ac.uk, E-mail: cpigozzo@ufba.br, E-mail: a.heavens@imperial.ac.uk, E-mail: raul.jimenez@icc.ub.edu [Imperial Centre for Inference and Cosmology (ICIC), Imperial College, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom)

    2017-04-01

    We investigate our knowledge of early universe cosmology by exploring how much additional energy density can be placed in different components beyond those in the ΛCDM model. To do this we use a method to separate early- and late-universe information enclosed in observational data, thus markedly reducing the model-dependency of the conclusions. We find that the 95% credibility regions for extra energy components of the early universe at recombination are: non-accelerating additional fluid density parameter Ω{sub MR} < 0.006 and extra radiation parameterised as extra effective neutrino species 2.3 < N {sub eff} < 3.2 when imposing flatness. Our constraints thus show that even when analyzing the data in this largely model-independent way, the possibility of hiding extra energy components beyond ΛCDM in the early universe is seriously constrained by current observations. We also find that the standard ruler, the sound horizon at radiation drag, can be well determined in a way that does not depend on late-time Universe assumptions, but depends strongly on early-time physics and in particular on additional components that behave like radiation. We find that the standard ruler length determined in this way is r {sub s} = 147.4 ± 0.7 Mpc if the radiation and neutrino components are standard, but the uncertainty increases by an order of magnitude when non-standard dark radiation components are allowed, to r {sub s} = 150 ± 5 Mpc.

  14. Hydrogen system (hydrogen fuels feasibility)

    International Nuclear Information System (INIS)

    Guarna, S.

    1991-07-01

    This feasibility study on the production and use of hydrogen fuels for industry and domestic purposes includes the following aspects: physical and chemical properties of hydrogen; production methods steam reforming of natural gas, hydrolysis of water; liquid and gaseous hydrogen transportation and storage (hydrogen-hydride technology); environmental impacts, safety and economics of hydrogen fuel cells for power generation and hydrogen automotive fuels; relevant international research programs

  15. Constraining neutrinoless double beta decay

    International Nuclear Information System (INIS)

    Dorame, L.; Meloni, D.; Morisi, S.; Peinado, E.; Valle, J.W.F.

    2012-01-01

    A class of discrete flavor-symmetry-based models predicts constrained neutrino mass matrix schemes that lead to specific neutrino mass sum-rules (MSR). We show how these theories may constrain the absolute scale of neutrino mass, leading in most of the cases to a lower bound on the neutrinoless double beta decay effective amplitude.

  16. New hydrogen technologies

    International Nuclear Information System (INIS)

    1992-01-01

    This report presents an overview of the overall hydrogen system. There are separate sections for production, distribution, transport, storage; and applications of hydrogen. The most important methods for hydrogen production are steam reformation of natural gas and electrolysis of water. Of the renewable energy options, production of hydrogen by electrolysis using electricity from wind turbines or by gasification of biomass were found to be the most economic for Finland. Direct use of this electricity or the production of liquid fuels from biomass will be competing alternatives. When hydrogen is produced in the solar belt or where there is cheap hydropower it must be transported over long distances. The overall energy consumed for the transport is from 25 to 40 % of the initial available energy. Hydrogen storage can be divided into stationary and mobile types. The most economic, stationary, large scale hydrogen storage for both long and short periods is underground storage. When suitable sites are not available, then pressure vessels are the best for short period and liquid H 2 for long period. Vehicle storage of hydrogen is by either metal hydrides or liquid H 2 . Hydrogen is a very versatile energy carrier. It can be used to produce heat directly in catalytic burners without flame, to produce electricity in fuel cells with high efficiency for use in vehicles or for peak power shaving, as a fuel component with conventional fuels to reduce emissions, as a way to store energy and as a chemical reagent in reactions

  17. Hail hydrogen

    International Nuclear Information System (INIS)

    Hairston, D.

    1996-01-01

    After years of being scorned and maligned, hydrogen is finding favor in environmental and process applications. There is enormous demand for the industrial gas from petroleum refiners, who need in creasing amounts of hydrogen to remove sulfur and other contaminants from crude oil. In pulp and paper mills, hydrogen is turning up as hydrogen peroxide, displacing bleaching agents based on chlorine. Now, new technologies for making hydrogen have the industry abuzz. With better capabilities of being generated onsite at higher purity levels, recycled and reused, hydrogen is being prepped for a range of applications, from waste reduction to purification of Nylon 6 and hydrogenation of specialty chemicals. The paper discusses the strong market demand for hydrogen, easier routes being developed for hydrogen production, and the use of hydrogen in the future

  18. Constraining Lyman continuum escape using Machine Learning

    Science.gov (United States)

    Giri, Sambit K.; Zackrisson, Erik; Binggeli, Christian; Pelckmans, Kristiaan; Cubo, Rubén; Mellema, Garrelt

    2018-05-01

    The James Webb Space Telescope (JWST) will observe the rest-frame ultraviolet/optical spectra of galaxies from the epoch of reionization (EoR) in unprecedented detail. While escaping into the intergalactic medium, hydrogen-ionizing (Lyman continuum; LyC) photons from the galaxies will contribute to the bluer end of the UV slope and make nebular emission lines less prominent. We present a method to constrain leakage of the LyC photons using the spectra of high redshift (z >~ 6) galaxies. We simulate JWST/NIRSpec observations of galaxies at z =6-9 by matching the fluxes of galaxies observed in the Frontier Fields observations of galaxy cluster MACS-J0416. Our method predicts the escape fraction fesc with a mean absolute error Δfesc ~ 0.14. The method also predicts the redshifts of the galaxies with an error .

  19. Emergence of a high-temperature superconductivity in hydrogen cycled Pd compounds as an evidence for super-stoichiometric H/D sites

    Energy Technology Data Exchange (ETDEWEB)

    Lipson, Andrei; Castano, Carlos; Miley, George [University of Illinois at Urbana - Champaign, lL (United States); Lipson, Andrei; Lyakhov, Boris [lnstitute of Physical Chemistry, RAS, Moscow (Russian Federation); Mitin, Alexander [P. Kapitza Institute for Physical Problems, RAS, Moscow (Russian Federation)

    2006-07-01

    Transport and magnetic properties of hydrogen cycled PdH{sub x} and Pd/PdO:H{sub x} (x {approx} = (4/6) x 10{sup -4}) nano-composite consisting of a Pd matrix with hydrogen trapped inside dislocation cores have been studied. The results suggest emergence of a high-temperature superconductivity stale of a condensed hydrogen phase confined inside deep dislocation cores in the Pd matrix. The possible role of hydrogen/deuterium filled dislocation nano-tubes is discussed. These dislocation cores could be considered as active centers of LENR triggering due to (i) short D-D separation distance ({approx}Bohr radius); (ii) high-local D-loading in the Pd and the corresponding effective lattice compression; (iii) a large optic phonon energy resulting in a most effective lattice-nuclei energy transfer.

  20. Emergence of a high-temperature superconductivity in hydrogen cycled Pd compounds as an evidence for super-stoichiometric H/D sites

    International Nuclear Information System (INIS)

    Lipson, Andrei; Castano, Carlos; Miley, George; Lipson, Andrei; Lyakhov, Boris; Mitin, Alexander

    2006-01-01

    Transport and magnetic properties of hydrogen cycled PdH x and Pd/PdO:H x (x ∼ = (4/6) x 10 -4 ) nano-composite consisting of a Pd matrix with hydrogen trapped inside dislocation cores have been studied. The results suggest emergence of a high-temperature superconductivity stale of a condensed hydrogen phase confined inside deep dislocation cores in the Pd matrix. The possible role of hydrogen/deuterium filled dislocation nano-tubes is discussed. These dislocation cores could be considered as active centers of LENR triggering due to (i) short D-D separation distance (∼Bohr radius); (ii) high-local D-loading in the Pd and the corresponding effective lattice compression; (iii) a large optic phonon energy resulting in a most effective lattice-nuclei energy transfer

  1. Emergence of a High-Temperature Superconductivity in Hydrogen Cycled pd Compounds as AN Evidence for Superstoihiometric H/d Sites

    Science.gov (United States)

    Lipson, Andrei; Castano, Carlos; Miley, George; Lipson, Andrei; Lyakhov, Boris; Mitin, Alexander

    2006-02-01

    Transport and magnetic properties of hydrogen cycled PdHx and Pd/PdO:Hx (x ~ (4/6) × 10-4) nano-composite consisting of a Pd matrix with hydrogen trapped inside dislocation cores have been studied. The results suggest emergence of a high-temperature superconductivity state of a condensed hydrogen phase confined inside deep dislocation cores in the Pd matrix. The possible role of hydrogen/deuterium filled dislocation nano-tubes is discussed. These dislocation cores could be considered as active centers of LENR triggering due to (i) short D-D separation distance (~Bohr radius); (ii) high-local D-loading in the Pd and the corresponding effective lattice compression; (iii) a large optic phonon energy resulting in a most effective lattice-nuclei energy transfer.

  2. Electrochemical Hydrogen Compressor

    Energy Technology Data Exchange (ETDEWEB)

    Lipp, Ludwig [FuelCell Energy, Inc., Torrington, CT (United States)

    2016-01-21

    Conventional compressors have not been able to meet DOE targets for hydrogen refueling stations. They suffer from high capital cost, poor reliability and pose a risk of fuel contamination from lubricant oils. This project has significantly advanced the development of solid state hydrogen compressor technology for multiple applications. The project has achieved all of its major objectives. It has demonstrated capability of Electrochemical Hydrogen Compression (EHC) technology to potentially meet the DOE targets for small compressors for refueling sites. It has quantified EHC cell performance and durability, including single stage hydrogen compression from near-atmospheric pressure to 12,800 psi and operation of EHC for more than 22,000 hours. Capital cost of EHC was reduced by 60%, enabling a path to meeting the DOE cost targets for hydrogen compression, storage and delivery ($2.00-2.15/gge by 2020).

  3. Constrained evolution in numerical relativity

    Science.gov (United States)

    Anderson, Matthew William

    The strongest potential source of gravitational radiation for current and future detectors is the merger of binary black holes. Full numerical simulation of such mergers can provide realistic signal predictions and enhance the probability of detection. Numerical simulation of the Einstein equations, however, is fraught with difficulty. Stability even in static test cases of single black holes has proven elusive. Common to unstable simulations is the growth of constraint violations. This work examines the effect of controlling the growth of constraint violations by solving the constraints periodically during a simulation, an approach called constrained evolution. The effects of constrained evolution are contrasted with the results of unconstrained evolution, evolution where the constraints are not solved during the course of a simulation. Two different formulations of the Einstein equations are examined: the standard ADM formulation and the generalized Frittelli-Reula formulation. In most cases constrained evolution vastly improves the stability of a simulation at minimal computational cost when compared with unconstrained evolution. However, in the more demanding test cases examined, constrained evolution fails to produce simulations with long-term stability in spite of producing improvements in simulation lifetime when compared with unconstrained evolution. Constrained evolution is also examined in conjunction with a wide variety of promising numerical techniques, including mesh refinement and overlapping Cartesian and spherical computational grids. Constrained evolution in boosted black hole spacetimes is investigated using overlapping grids. Constrained evolution proves to be central to the host of innovations required in carrying out such intensive simulations.

  4. Simple inorganic complexes but intricate hydrogen bonding ...

    Indian Academy of Sciences (India)

    Administrator

    We are interested in obtaining single crystals of metal-opda complexes because their crystal structures would show complex hydrogen bonding network due to the presence of. –NH2 groups in the opda ligand (hydrogen bonding donor sites) and inorganic anions having mostly oxo groups (hydrogen bonding acceptor sites) ...

  5. Preliminary analysis of an hydrogen generator system based on nuclear energy in the Laguna Verde site; Analisis preliminar de un sistema generador de hidrogeno basado en energia nuclear en el sitio de Laguna Verde

    Energy Technology Data Exchange (ETDEWEB)

    Flores y Flores, A [FI-UNAM, 04500 Mexico D.F. (Mexico); Francois L, J L [FI-UNAM, Jiutepec, Morelos (Mexico)

    2003-07-01

    The shortage of fossil fuels in the next future, as well as the growing one demand of energetics and the high cost of the production of alternating fuels, it forces us to take advantage of to the maximum the fossil fuel with the one which we count and to look for the form of producing alternating fuels at a low cost and better even if these supply sources are reliable and non pollutants. It is intended a solution to the shortage of fuel; to use the thermal energy liberated of some appropriate nuclear reactor to be able to obtain a fuel but clean and relatively cheap as it is the hydrogen. In the first place the methods were looked for to produce hydrogen using thermal energy, later it was analyzed the temperature liberated by the existent nuclear reactors as well as the advanced designs, according to this liberated temperature settled down that the methods but feasible to produce hydrogen its were the one of reformed with water stream of the natural gas (methane) and the other one of the S-I thermochemical cycle, and the nuclear reactors that give the thermal energy for this production they are those of gas of high temperature. Once established the processes and the appropriate reactors, it was analyzed the site of Laguna Verde, with relationship to the free space to be able to place the reactor and the plant producer of hydrogen, as well as the direction in which blow the dominant winds and the near towns to the place, it was carried out an analysis of some explosion of tanks that could store hydrogen and the damage that its could to cause depending from the distance to which its were of the fire. Finally it was carried out an evaluation of capital and of operation costs for those two methods of hydrogen production. (Author)

  6. Within-Site Variation in Feather Stable Hydrogen Isotope (δ2Hf) Values of Boreal Songbirds: Implications for Assignment to Molt Origin.

    Science.gov (United States)

    Nordell, Cameron J; Haché, Samuel; Bayne, Erin M; Sólymos, Péter; Foster, Kenneth R; Godwin, Christine M; Krikun, Richard; Pyle, Peter; Hobson, Keith A

    2016-01-01

    Understanding bird migration and dispersal is important to inform full life-cycle conservation planning. Stable hydrogen isotope ratios from feathers (δ2Hf) can be linked to amount-weighted long-term, growing season precipitation δ2H (δ2Hp) surfaces to create δ2Hf isoscapes for assignment to molt origin. However, transfer functions linking δ2Hp with δ2Hf are influenced by physiological and environmental processes. A better understanding of the causes and consequences of variation in δ2Hf values among individuals and species will improve the predictive ability of geographic assignment tests. We tested for effects of species, land cover, forage substrate, nest substrate, diet composition, body mass, sex, and phylogenetic relatedness on δ2Hf from individuals at least two years old of 21 songbird species captured during the same breeding season at a site in northeastern Alberta, Canada. For four species, we also tested for a year × species interaction effect on δ2Hf. A model including species as single predictor received the most support (AIC weight = 0.74) in explaining variation in δ2Hf. A species-specific variance parameter was part of all best-ranked models, suggesting variation in δ2Hf was not consistent among species. The second best-ranked model included a forage substrate × diet interaction term (AIC weight = 0.16). There was a significant year × species interaction effect on δ2Hf suggesting that interspecific differences in δ2Hf can differ among years. Our results suggest that within- and among-year interspecific variation in δ2Hf is the most important source of variance typically not being explicitly quantified in geographic assignment tests using non-specific transfer functions to convert δ2Hp into δ2Hf. However, this source of variation is consistent with the range of variation from the transfer functions most commonly being propagated in assignment tests of geographic origins for passerines breeding in North America.

  7. Hydrogen detector

    International Nuclear Information System (INIS)

    Kumagaya, Hiromichi; Yoshida, Kazuo; Sanada, Kazuo; Chigira, Sadao.

    1994-01-01

    The present invention concerns a hydrogen detector for detecting water-sodium reaction. The hydrogen detector comprises a sensor portion having coiled optical fibers and detects hydrogen on the basis of the increase of light transmission loss upon hydrogen absorption. In the hydrogen detector, optical fibers are wound around and welded to the outer circumference of a quartz rod, as well as the thickness of the clad layer of the optical fiber is reduced by etching. With such procedures, size of the hydrogen detecting sensor portion can be decreased easily. Further, since it can be used at high temperature, diffusion rate is improved to shorten the detection time. (N.H.)

  8. Hydrogen in amorphous silicon

    International Nuclear Information System (INIS)

    Peercy, P.S.

    1980-01-01

    The structural aspects of amorphous silicon and the role of hydrogen in this structure are reviewed with emphasis on ion implantation studies. In amorphous silicon produced by Si ion implantation of crystalline silicon, the material reconstructs into a metastable amorphous structure which has optical and electrical properties qualitatively similar to the corresponding properties in high-purity evaporated amorphous silicon. Hydrogen studies further indicate that these structures will accomodate less than or equal to 5 at.% hydrogen and this hydrogen is bonded predominantly in a monohydride (SiH 1 ) site. Larger hydrogen concentrations than this can be achieved under certain conditions, but the excess hydrogen may be attributed to defects and voids in the material. Similarly, glow discharge or sputter deposited amorphous silicon has more desirable electrical and optical properties when the material is prepared with low hydrogen concentration and monohydride bonding. Results of structural studies and hydrogen incorporation in amorphous silicon were discussed relative to the different models proposed for amorphous silicon

  9. Lightweight cryptography for constrained devices

    DEFF Research Database (Denmark)

    Alippi, Cesare; Bogdanov, Andrey; Regazzoni, Francesco

    2014-01-01

    Lightweight cryptography is a rapidly evolving research field that responds to the request for security in resource constrained devices. This need arises from crucial pervasive IT applications, such as those based on RFID tags where cost and energy constraints drastically limit the solution...... complexity, with the consequence that traditional cryptography solutions become too costly to be implemented. In this paper, we survey design strategies and techniques suitable for implementing security primitives in constrained devices....

  10. [Hydrogen systems analysis, education, and outreach

    Energy Technology Data Exchange (ETDEWEB)

    None

    1998-01-01

    This paper illustrates a search of web sites on the keyword, Hydrogen, and a second search combining keywords, Hydrogen and Renewable Energy. Names, addresses, and E-mail addresses or web site URLs are given for a number of companies and government or commercial organizations dealing with hydrogen fuel cells. Finally, brief summaries are given on hydrogen research projects at the National Renewable Energy Laboratory.

  11. Hydrogen: a new resource for the Venice industrial area

    International Nuclear Information System (INIS)

    Giorgio Mattiello

    2006-01-01

    Hydrogen Park is based in Marghera, inside the Venice Municipality, where it is produced the 40% of the Italian production of hydrogen, as by-product of industrial processes. This availability gives the possibility to develop and to test new technologies based on hydrogen without the gas generation constrain. The Company deal is to coordinate the partners activities to utilize the Hydrogen resources available in Marghera. (authors)

  12. Hydrogen sulfide adsorption on activated carbon fiber. Tests on Parisian subway; Elimination du sulfure d'hydrogene par adsorption sur tissu de charbon actif. Essais sur site RATP

    Energy Technology Data Exchange (ETDEWEB)

    Bouzaza, A.; Marsteau, St.; Laplanche, A. [Ecole Nationale Superieure de Chimie, Lab. Chimie des Nuissances et Genie de l' Environnement - CNGE, 35 - Rennes (France); Garrot, B. [RATP, Dept. Environnement et Securite-Domaines d' Expertises de l' Environnement-Entite Qualite de l' Air, 75 - Paris (France)

    2003-06-01

    Hydrogen sulfide has an unpleasant odor and may cause damage to the electrical materials of the Parisian subway. The activated carbon has some intrinsic catalytic activity, so the removal of hydrogen sulfide is due to an adsorption-oxidation process. In a laboratory scale, some kinetic parameters were acquired, which allowed us to build up two dynamic reactors. These continuous reactors, equipped with activated carbon fibers, were tested on the Madeleine station of the Parisian subway. The feasibility of the elimination of H{sub 2}S by continuous adsorption-oxidation was confirmed. The relative humidity of the gas phase was found to play an important role in the performance of the elimination. The durability of the pilot tested was compatible with an industrial exploitation of the process. (authors)

  13. Hydrogen highway

    International Nuclear Information System (INIS)

    Anon

    2008-01-01

    The USA Administration would like to consider the US power generating industry as a basis ensuring both the full-scale production of hydrogen and the widespread use of the hydrogen related technological processes into the economy [ru

  14. Understanding Hydrogen Sorption in In- soc -MOF: A Charged Metal-Organic Framework with Open-Metal Sites, Narrow Channels, and Counterions

    KAUST Repository

    Pham, Tony; Forrest, Katherine A.; Hogan, Adam; Tudor, Brant; McLaughlin, Keith; Belof, Jonathan L.; Eckert, Juergen; Space, Brian

    2015-01-01

    ,3-benzenedicarboxylate) linkers. The MOF contains nitrate counterions that are located in carcerand-like capsules of the framework. This MOF was shown to have a high hydrogen uptake at 77 K and 1.0 atm. The simulations were performed with a potential that includes

  15. Palladium-Catalyzed Atom-Transfer Radical Cyclization at Remote Unactivated C(sp3 )-H Sites: Hydrogen-Atom Transfer of Hybrid Vinyl Palladium Radical Intermediates.

    Science.gov (United States)

    Ratushnyy, Maxim; Parasram, Marvin; Wang, Yang; Gevorgyan, Vladimir

    2018-03-01

    A novel mild, visible-light-induced palladium-catalyzed hydrogen atom translocation/atom-transfer radical cyclization (HAT/ATRC) cascade has been developed. This protocol involves a 1,5-HAT process of previously unknown hybrid vinyl palladium radical intermediates, thus leading to iodomethyl carbo- and heterocyclic structures. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Thermal decay of rhodopsin: role of hydrogen bonds in thermal isomerization of 11-cis retinal in the binding site and hydrolysis of protonated Schiff base.

    Science.gov (United States)

    Liu, Jian; Liu, Monica Yun; Nguyen, Jennifer B; Bhagat, Aditi; Mooney, Victoria; Yan, Elsa C Y

    2009-07-01

    Although thermal stability of the G protein-coupled receptor rhodopsin is directly related to its extremely low dark noise level and has recently generated considerable interest, the chemistry behind the thermal decay process of rhodopsin has remained unclear. Using UV-vis spectroscopy and HPLC analysis, we have demonstrated that the thermal decay of rhodopsin involves both hydrolysis of the protonated Schiff base and thermal isomerization of 11-cis to all-trans retinal. Examining the unfolding of rhodopsin by circular dichroism spectroscopy and measuring the rate of thermal isomerization of 11-cis retinal in solution, we conclude that the observed thermal isomerization of 11-cis to all-trans retinal happens when 11-cis retinal is in the binding pocket of rhodopsin. Furthermore, we demonstrate that solvent deuterium isotope effects are involved in the thermal decay process by decreasing the rates of thermal isomerization and hydrolysis, suggesting that the rate-determining step of these processes involves breaking hydrogen bonds. These results provide insight into understanding the critical role of an extensive hydrogen-bonding network on stabilizing the inactive state of rhodopsin and contribute to our current understanding of the low dark noise level of rhodopsin, which enables this specialized protein to function as an extremely sensitive biological light detector. Because similar hydrogen-bonding networks have also been suggested by structural analysis of two other GPCRs, beta1 and beta2 adrenergic receptors, our results could reveal a general role of hydrogen bonds in facilitating GPCR function.

  17. Hydrogen economy

    Energy Technology Data Exchange (ETDEWEB)

    Pahwa, P.K.; Pahwa, Gulshan Kumar

    2013-10-01

    In the future, our energy systems will need to be renewable and sustainable, efficient and cost-effective, convenient and safe. Hydrogen has been proposed as the perfect fuel for this future energy system. The availability of a reliable and cost-effective supply, safe and efficient storage, and convenient end use of hydrogen will be essential for a transition to a hydrogen economy. Research is being conducted throughout the world for the development of safe, cost-effective hydrogen production, storage, and end-use technologies that support and foster this transition. This book discusses hydrogen economy vis-a-vis sustainable development. It examines the link between development and energy, prospects of sustainable development, significance of hydrogen energy economy, and provides an authoritative and up-to-date scientific account of hydrogen generation, storage, transportation, and safety.

  18. California Hydrogen Infrastructure Project

    Energy Technology Data Exchange (ETDEWEB)

    Heydorn, Edward C

    2013-03-12

    Air Products and Chemicals, Inc. has completed a comprehensive, multiyear project to demonstrate a hydrogen infrastructure in California. The specific primary objective of the project was to demonstrate a model of a real-world retail hydrogen infrastructure and acquire sufficient data within the project to assess the feasibility of achieving the nation's hydrogen infrastructure goals. The project helped to advance hydrogen station technology, including the vehicle-to-station fueling interface, through consumer experiences and feedback. By encompassing a variety of fuel cell vehicles, customer profiles and fueling experiences, this project was able to obtain a complete portrait of real market needs. The project also opened its stations to other qualified vehicle providers at the appropriate time to promote widespread use and gain even broader public understanding of a hydrogen infrastructure. The project engaged major energy companies to provide a fueling experience similar to traditional gasoline station sites to foster public acceptance of hydrogen. Work over the course of the project was focused in multiple areas. With respect to the equipment needed, technical design specifications (including both safety and operational considerations) were written, reviewed, and finalized. After finalizing individual equipment designs, complete station designs were started including process flow diagrams and systems safety reviews. Material quotes were obtained, and in some cases, depending on the project status and the lead time, equipment was placed on order and fabrication began. Consideration was given for expected vehicle usage and station capacity, standard features needed, and the ability to upgrade the station at a later date. In parallel with work on the equipment, discussions were started with various vehicle manufacturers to identify vehicle demand (short- and long-term needs). Discussions included identifying potential areas most suited for hydrogen fueling

  19. Hydrogen safety

    International Nuclear Information System (INIS)

    Frazier, W.R.

    1991-01-01

    The NASA experience with hydrogen began in the 1950s when the National Advisory Committee on Aeronautics (NACA) research on rocket fuels was inherited by the newly formed National Aeronautics and Space Administration (NASA). Initial emphasis on the use of hydrogen as a fuel for high-altitude probes, satellites, and aircraft limited the available data on hydrogen hazards to small quantities of hydrogen. NASA began to use hydrogen as the principal liquid propellant for launch vehicles and quickly determined the need for hydrogen safety documentation to support design and operational requirements. The resulting NASA approach to hydrogen safety requires a joint effort by design and safety engineering to address hydrogen hazards and develop procedures for safe operation of equipment and facilities. NASA also determined the need for rigorous training and certification programs for personnel involved with hydrogen use. NASA's current use of hydrogen is mainly for large heavy-lift vehicle propulsion, which necessitates storage of large quantities for fueling space shots and for testing. Future use will involve new applications such as thermal imaging

  20. Hydrogen Embrittlement

    Science.gov (United States)

    Woods, Stephen; Lee, Jonathan A.

    2016-01-01

    Hydrogen embrittlement (HE) is a process resulting in a decrease in the fracture toughness or ductility of a metal due to the presence of atomic hydrogen. In addition to pure hydrogen gas as a direct source for the absorption of atomic hydrogen, the damaging effect can manifest itself from other hydrogen-containing gas species such as hydrogen sulfide (H2S), hydrogen chloride (HCl), and hydrogen bromide (HBr) environments. It has been known that H2S environment may result in a much more severe condition of embrittlement than pure hydrogen gas (H2) for certain types of alloys at similar conditions of stress and gas pressure. The reduction of fracture loads can occur at levels well below the yield strength of the material. Hydrogen embrittlement is usually manifest in terms of singular sharp cracks, in contrast to the extensive branching observed for stress corrosion cracking. The initial crack openings and the local deformation associated with crack propagation may be so small that they are difficult to detect except in special nondestructive examinations. Cracks due to HE can grow rapidly with little macroscopic evidence of mechanical deformation in materials that are normally quite ductile. This Technical Memorandum presents a comprehensive review of experimental data for the effects of gaseous Hydrogen Environment Embrittlement (HEE) for several types of metallic materials. Common material screening methods are used to rate the hydrogen degradation of mechanical properties that occur while the material is under an applied stress and exposed to gaseous hydrogen as compared to air or helium, under slow strain rates (SSR) testing. Due to the simplicity and accelerated nature of these tests, the results expressed in terms of HEE index are not intended to necessarily represent true hydrogen service environment for long-term exposure, but rather to provide a practical approach for material screening, which is a useful concept to qualitatively evaluate the severity of

  1. Constraining walking and custodial technicolor

    DEFF Research Database (Denmark)

    Foadi, Roshan; Frandsen, Mads Toudal; Sannino, Francesco

    2008-01-01

    We show how to constrain the physical spectrum of walking technicolor models via precision measurements and modified Weinberg sum rules. We also study models possessing a custodial symmetry for the S parameter at the effective Lagrangian level-custodial technicolor-and argue that these models...

  2. Biomimetic hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Krassen, Henning

    2009-05-15

    Hydrogenases catalyze the reduction of protons to molecular hydrogen with outstanding efficiency. An electrode surface which is covered with active hydrogenase molecules becomes a promising alternative to platinum for electrochemical hydrogen production. To immobilize the hydrogenase on the electrode, the gold surface was modified by heterobifunctional molecules. A thiol headgroup on one side allowed the binding to the gold surface and the formation of a self-assembled monolayer. The other side of the molecules provided a surface with a high affinity for the hydrogenase CrHydA1 from Chlamydomonas reinhardtii. With methylviologen as a soluble energy carrier, electrons were transferred from carboxy-terminated electrodes to CrHydA1 and conducted to the active site (H-cluster), where they reduce protons to molecular hydrogen. A combined approach of surface-enhanced infrared absorption spectroscopy, gas chromatography, and surface plasmon resonance allowed quantifying the hydrogen production on a molecular level. Hydrogen was produced with a rate of 85 mol H{sub 2} min{sup -1} mol{sup -1}. On a 1'- benzyl-4,4'-bipyridinum (BBP)-terminated surface, the electrons were mediated by the monolayer and no soluble electron carrier was necessary to achieve a comparable hydrogen production rate (approximately 50% of the former system). The hydrogen evolution potential was determined to be -335 mV for the BBP-bound hydrogenase and -290 mV for the hydrogenase which was immobilized on a carboxy-terminated mercaptopropionic acid SAM. Therefore, both systems significantly reduce the hydrogen production overpotential and allow electrochemical hydrogen production at an energy level which is close to the commercially applied platinum electrodes (hydrogen evolution potential of -270 mV). In order to couple hydrogen production and photosynthesis, photosystem I (PS1) from Synechocystis PCC 6803 and membrane-bound hydrogenase (MBH) from Ralstonia eutropha were bound to each other

  3. Hydrogen millennium

    International Nuclear Information System (INIS)

    Bose, T.K.; Benard, P.

    2000-05-01

    The 10th Canadian Hydrogen Conference was held at the Hilton Hotel in Quebec City from May 28 to May 31, 2000. The topics discussed included current drivers for the hydrogen economy, the international response to these drivers, new initiatives, sustainable as well as biological and hydrocarbon-derived production of hydrogen, defense applications of fuel cells, hydrogen storage on metal hydrides and carbon nanostructures, stationary power and remote application, micro-fuel cells and portable applications, marketing aspects, fuel cell modeling, materials, safety, fuel cell vehicles and residential applications. (author)

  4. Color Changing Hydrogen Sensors

    Science.gov (United States)

    Roberson, Luke B.; Williams, Martha; Captain, Janine E.; Mohajeri, Nahid; Raissi, Ali

    2015-01-01

    benefits over the traditional hydrogen sensors: The technology has excellent temperature stability (4K to 373 K), it can be used in cryogenic fluid applications, it is easy to apply and remove; it requires no power to operate; it has a quick response time; the leak points can be detected visually or electronically; it is nonhazardous, thus environmentally friendly; it can be reversible or irreversible; it does not require on-site monitoring; has a long shelf life; the detector is very durable; and the technology is inexpensive to manufacture.

  5. A-site order–disorder in the NdBaMn2O5+δ SOFC electrode material monitored in situ by neutron diffraction under hydrogen flow

    KAUST Repository

    Tonus, Florent; Bahout, Mona; Dorcet, Vincent; Sharma, Rakesh K.; Djurado, Elisabeth; Paofai, Serge; Smith, Ronald I.; Skinner, Stephen J.

    2017-01-01

    The A-site disordered perovskite manganite, Nd0.5Ba0.5MnO3, has been obtained by heating the A-site-ordered and vacancy ordered layered double perovskite, NdBaMn2O5, in air at 1300 °C for 5 h. Combined transmission electron microscopy (TEM) images

  6. Hydrogen application dynamics and networks

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, E. [Air Liquide Large Industries, Champigny-sur-Marne (France)

    2010-12-30

    The Chemical Industry consumes large volumes of hydrogen as raw material for the manufacture of numerous products (e.g. polyamides and polyurethanes account for 60% of hydrogen demand). The hydrogen demand was in the recent past and will continue to be driven by the polyurethane family. China will host about 60% of new hydrogen needs over the period 2010-2015 becoming the first hydrogen market next year and reaching 25% of market share by 2015 (vs. only 4% in 2001). Air Liquide supplies large volumes of Hydrogen (and other Industrial Gases) to customers by on-site plants and through pipeline networks which offer significant benefits such as higher safety, reliability and flexibility of supply. Thanks to its long term strategy and heavy investment in large units and pipeline networks, Air Liquide is the Industrial Gas leader in most of the world class Petrochemical basins (Rotterdam, Antwerp, US Gulf Coast, Yosu, Caojing,..) (orig.)

  7. Trends in PDE constrained optimization

    CERN Document Server

    Benner, Peter; Engell, Sebastian; Griewank, Andreas; Harbrecht, Helmut; Hinze, Michael; Rannacher, Rolf; Ulbrich, Stefan

    2014-01-01

    Optimization problems subject to constraints governed by partial differential equations (PDEs) are among the most challenging problems in the context of industrial, economical and medical applications. Almost the entire range of problems in this field of research was studied and further explored as part of the Deutsche Forschungsgemeinschaft (DFG) priority program 1253 on “Optimization with Partial Differential Equations” from 2006 to 2013. The investigations were motivated by the fascinating potential applications and challenging mathematical problems that arise in the field of PDE constrained optimization. New analytic and algorithmic paradigms have been developed, implemented and validated in the context of real-world applications. In this special volume, contributions from more than fifteen German universities combine the results of this interdisciplinary program with a focus on applied mathematics.   The book is divided into five sections on “Constrained Optimization, Identification and Control”...

  8. HySTAR: the hydrogen safety training and risk workplace

    International Nuclear Information System (INIS)

    Hay, R.

    2006-01-01

    This paper shows the output of the software package HySTAR, the Hydrogen Safety, Training and Risk Workplace. This is the software output of the CTFA, Canadian Hydrogen Safety Program projects. It shows the Hydrogen Virtual Interactive Expert Workplace, a guide for permitting and code enforcement for officials and other parties involved in approving hydrogen energy facilities. It also shows the Hydrogen Codes and Standards Report (Site Level) as well as Hydrogen Distances and Clearances Report

  9. Hydrogen exchange

    DEFF Research Database (Denmark)

    Jensen, Pernille Foged; Rand, Kasper Dyrberg

    2016-01-01

    Hydrogen exchange (HX) monitored by mass spectrometry (MS) is a powerful analytical method for investigation of protein conformation and dynamics. HX-MS monitors isotopic exchange of hydrogen in protein backbone amides and thus serves as a sensitive method for probing protein conformation...... and dynamics along the entire protein backbone. This chapter describes the exchange of backbone amide hydrogen which is highly quenchable as it is strongly dependent on the pH and temperature. The HX rates of backbone amide hydrogen are sensitive and very useful probes of protein conformation......, as they are distributed along the polypeptide backbone and form the fundamental hydrogen-bonding networks of basic secondary structure. The effect of pressure on HX in unstructured polypeptides (poly-dl-lysine and oxidatively unfolded ribonuclease A) and native folded proteins (lysozyme and ribonuclease A) was evaluated...

  10. Trapping and detrapping of hydrogen in graphite materials exposed to hydrogen gas

    International Nuclear Information System (INIS)

    Atsumi, Hisao; Iseki, Michio; Shikama, Tatsuo.

    1994-01-01

    Measurements of hydrogen solubility have been performed for several unirradiated and neutron-irradiated graphite (and CFC) samples at temperatures between 973 and 1323 K under a ∼10 kPa hydrogen atmosphere. The hydrogen dissolution process has been studied and it is discussed here. The values of hydrogen solubility vary substantially among the samples up to about a factor of 16. A strong correlation has been observed between the values of hydrogen solubility and the degrees of graphitization determined by X-ray diffraction technique. The relation can be extended even for the neutron irradiated samples. Hydrogen dissolution into graphite can be explained with the trapping of hydrogen at defect sites (e.g. dangling carbon bonds) considering an equilibrium reaction between hydrogen molecules and the trapping sites. The migration of hydrogen in graphite is speculated to result from a sequence of detrapping and retrapping events with high energy activation processes. (author)

  11. Hydrogen bonds between the alpha and beta subunits of the F1-ATPase allow communication between the catalytic site and the interface of the beta catch loop and the gamma subunit.

    Science.gov (United States)

    Boltz, Kathryn W; Frasch, Wayne D

    2006-09-19

    F(1)-ATPase mutations in Escherichia coli that changed the strength of hydrogen bonds between the alpha and beta subunits in a location that links the catalytic site to the interface between the beta catch loop and the gamma subunit were examined. Loss of the ability to form the hydrogen bonds involving alphaS337, betaD301, and alphaD335 lowered the k(cat) of ATPase and decreased its susceptibility to Mg(2+)-ADP-AlF(n) inhibition, while mutations that maintain or strengthen these bonds increased the susceptibility to Mg(2+)-ADP-AlF(n) inhibition and lowered the k(cat) of ATPase. These data suggest that hydrogen bonds connecting alphaS337 to betaD301 and betaR323 and connecting alphaD335 to alphaS337 are important to transition state stabilization and catalytic function that may result from the proper alignment of catalytic site residues betaR182 and alphaR376 through the VISIT sequence (alpha344-348). Mutations betaD301E, betaR323K, and alphaR282Q changed the rate-limiting step of the reaction as determined by an isokinetic plot. Hydrophobic mutations of betaR323 decreased the susceptibility to Mg(2+)-ADP-AlF(n)() inhibition and lowered the number of interactions required in the rate-limiting step yet did not affect the k(cat) of ATPase, suggesting that betaR323 is important to transition state formation. The decreased rate of ATP synthase-dependent growth and decreased level of lactate-dependent quenching observed with alphaD335, betaD301, and alphaE283 mutations suggest that these residues may be important to the formation of an alternative set of hydrogen bonds at the interface of the alpha and beta subunits that permits the release of intersubunit bonds upon the binding of ATP, allowing gamma rotation in the escapement mechanism.

  12. [NiFe] hydrogenase structural and functional models: new bio-inspired catalysts for hydrogen evolution; Modeles structuraux et fonctionnels du site actif des hydrogenases [NiFe]: de nouveaux catalyseurs bio-inspires pour la production d'hydrogene

    Energy Technology Data Exchange (ETDEWEB)

    Oudart, Y

    2006-09-15

    Hydrogenase enzymes reversibly catalyze the oxidation and production of hydrogen in a range close to the thermodynamic potential. The [NiFe] hydrogenase active site contains an iron-cyano-carbonyl moiety linked to a nickel atom which is in an all sulphur environment. Both the active site originality and the potential development of an hydrogen economy make the synthesis of functional and structural models worthy. To take up this challenge, we have synthesised mononuclear ruthenium models and more importantly, nickel-ruthenium complexes, mimicking some structural features of the [NiFe] hydrogenase active site. Ruthenium is indeed isoelectronic to iron and some of its complexes are well-known to bear hydrides. The compounds described in this study have been well characterised and their activity in proton reduction has been successfully tested. Most of them are able to catalyze this reaction though their electrocatalytic potentials remain much more negative compared to which of platinum. The studied parameters point out the importance of the complexes electron richness, especially of the nickel environment. Furthermore, the proton reduction activity is stable for several hours at good rates. The ruthenium environment seems important for this stability. Altogether, these compounds represent the very first catalytically active [NiFe] hydrogenase models. Important additional results of this study are the synergetic behaviour of the two metals in protons reduction and the evidence of a protonation step as the limiting step of the catalytic cycle. We have also shown that a basic site close to ruthenium improves the electrocatalytic potential of the complexes. (author)

  13. Nested Sampling with Constrained Hamiltonian Monte Carlo

    OpenAIRE

    Betancourt, M. J.

    2010-01-01

    Nested sampling is a powerful approach to Bayesian inference ultimately limited by the computationally demanding task of sampling from a heavily constrained probability distribution. An effective algorithm in its own right, Hamiltonian Monte Carlo is readily adapted to efficiently sample from any smooth, constrained distribution. Utilizing this constrained Hamiltonian Monte Carlo, I introduce a general implementation of the nested sampling algorithm.

  14. Constrained minimization in C ++ environment

    International Nuclear Information System (INIS)

    Dymov, S.N.; Kurbatov, V.S.; Silin, I.N.; Yashchenko, S.V.

    1998-01-01

    Based on the ideas, proposed by one of the authors (I.N.Silin), the suitable software was developed for constrained data fitting. Constraints may be of the arbitrary type: equalities and inequalities. The simplest of possible ways was used. Widely known program FUMILI was realized to the C ++ language. Constraints in the form of inequalities φ (θ i ) ≥ a were taken into account by change into equalities φ (θ i ) = t and simple inequalities of type t ≥ a. The equalities were taken into account by means of quadratic penalty functions. The suitable software was tested on the model data of the ANKE setup (COSY accelerator, Forschungszentrum Juelich, Germany)

  15. Coherent states in constrained systems

    International Nuclear Information System (INIS)

    Nakamura, M.; Kojima, K.

    2001-01-01

    When quantizing the constrained systems, there often arise the quantum corrections due to the non-commutativity in the re-ordering of constraint operators in the products of operators. In the bosonic second-class constraints, furthermore, the quantum corrections caused by the uncertainty principle should be taken into account. In order to treat these corrections simultaneously, the alternative projection technique of operators is proposed by introducing the available minimal uncertainty states of the constraint operators. Using this projection technique together with the projection operator method (POM), these two kinds of quantum corrections were investigated

  16. Florida Hydrogen Initiative

    Energy Technology Data Exchange (ETDEWEB)

    Block, David L

    2013-06-30

    The Florida Hydrogen Initiative (FHI) was a research, development and demonstration hydrogen and fuel cell program. The FHI program objectives were to develop Florida?s hydrogen and fuel cell infrastructure and to assist DOE in its hydrogen and fuel cell activities The FHI program funded 12 RD&D projects as follows: Hydrogen Refueling Infrastructure and Rental Car Strategies -- L. Lines, Rollins College This project analyzes strategies for Florida's early stage adaptation of hydrogen-powered public transportation. In particular, the report investigates urban and statewide network of refueling stations and the feasibility of establishing a hydrogen rental-car fleet based in Orlando. Methanol Fuel Cell Vehicle Charging Station at Florida Atlantic University ? M. Fuchs, EnerFuel, Inc. The project objectives were to design, and demonstrate a 10 kWnet proton exchange membrane fuel cell stationary power plant operating on methanol, to achieve an electrical energy efficiency of 32% and to demonstrate transient response time of less than 3 milliseconds. Assessment of Public Understanding of the Hydrogen Economy Through Science Center Exhibits, J. Newman, Orlando Science Center The project objective was to design and build an interactive Science Center exhibit called: ?H2Now: the Great Hydrogen Xchange?. On-site Reformation of Diesel Fuel for Hydrogen Fueling Station Applications ? A. Raissi, Florida Solar Energy Center This project developed an on-demand forecourt hydrogen production technology by catalytically converting high-sulfur hydrocarbon fuels to an essentially sulfur-free gas. The removal of sulfur from reformate is critical since most catalysts used for the steam reformation have limited sulfur tolerance. Chemochromic Hydrogen Leak Detectors for Safety Monitoring ? N. Mohajeri and N. Muradov, Florida Solar Energy Center This project developed and demonstrated a cost-effective and highly selective chemochromic (visual) hydrogen leak detector for safety

  17. Questioning hydrogen

    International Nuclear Information System (INIS)

    Hammerschlag, Roel; Mazza, Patrick

    2005-01-01

    As an energy carrier, hydrogen is to be compared to electricity, the only widespread and viable alternative. When hydrogen is used to transmit renewable electricity, only 51% can reach the end user due to losses in electrolysis, hydrogen compression, and the fuel cell. In contrast, conventional electric storage technologies allow between 75% and 85% of the original electricity to be delivered. Even when hydrogen is extracted from gasified coal (with carbon sequestration) or from water cracked in high-temperature nuclear reactors, more of the primary energy reaches the end user if a conventional electric process is used instead. Hydrogen performs no better in mobile applications, where electric vehicles that are far closer to commercialization exceed fuel cell vehicles in efficiency, cost and performance. New, carbon-neutral energy can prevent twice the quantity of GHG's by displacing fossil electricity than it can by powering fuel cell vehicles. The same is true for new, natural gas energy. New energy resources should be used to displace high-GHG electric generation, not to manufacture hydrogen

  18. Hierarchical self-assembly of a bow-shaped molecule bearing self-complementary hydrogen bonding sites into extended supramolecular assemblies.

    Science.gov (United States)

    Ikeda, Masato; Nobori, Tadahito; Schmutz, Marc; Lehn, Jean-Marie

    2005-01-07

    The bow-shaped molecule 1 bearing a self-complementary DAAD-ADDA (D=donor A=acceptor) hydrogen-bonding array generates, in hydrocarbon solvents, highly ordered supramolecular sheet aggregates that subsequently give rise to gels by formation of an entangled network. The process of hierarchical self-assembly of compound 1 was investigated by the concentration and temperature dependence of UV-visible and (1)H NMR spectra, fluorescence spectra, and electron microscopy data. The temperature dependence of the UV-visible spectra indicates a highly cooperative process for the self-assembly of compound 1 in decaline. The electron micrograph of the decaline solution of compound 1 (1.0 mM) revealed supramolecular sheet aggregates forming an entangled network. The selected area electronic diffraction patterns of the supramolecular sheet aggregates were typical for single crystals, indicative of a highly ordered assembly. The results exemplify the generation, by hierarchical self-assembly, of highly organized supramolecular materials presenting novel collective properties at each level of organization.

  19. Hydrogen program overview

    Energy Technology Data Exchange (ETDEWEB)

    Gronich, S. [Dept. of Energy, Washington, DC (United States). Office of Utility Technologies

    1997-12-31

    This paper consists of viewgraphs which summarize the following: Hydrogen program structure; Goals for hydrogen production research; Goals for hydrogen storage and utilization research; Technology validation; DOE technology validation activities supporting hydrogen pathways; Near-term opportunities for hydrogen; Market for hydrogen; and List of solicitation awards. It is concluded that a full transition toward a hydrogen economy can begin in the next decade.

  20. Hydrogen storage in nanostructured materials

    Energy Technology Data Exchange (ETDEWEB)

    Assfour, Bassem

    2011-02-28

    total hydrogen uptake at 77 K and 100 bar amounts to 7.8 wt.% comparable to the total uptake reported of MOF-177 (10 wt.%), which is a benchmark material for high pressure and low temperature H{sub 2} adsorption. Covalent organic frameworks are new class of nanoporous materials constructed solely from light elements (C, H, B, and O). The number of adsorption sites as well as the strength of adsorption are essential prerequisites for hydrogen storage in porous materials because they determine the storage capacity and the operational conditions. Currently, to the best of our knowledge, no experimental data are available on the position of preferential H{sub 2} adsorption sites in COFs. Molecular dynamics simulations were applied to determine the position of preferential hydrogen sites in COFs. Our results demonstrate that H{sub 2} molecule adsorbed at low temperature in seven different adsorption sites in COFs. The calculated adsorption energies are about 3 kJ/mol, comparable to that found for MOF systems. The gravimetric uptake for COF-108 reached 4.17 wt.% at room temperature and 100 bar, which makes this class of materials promising for hydrogen storage applications. (orig.)

  1. Visualization of hydrogen in steels by secondary ion mass spectrometry

    International Nuclear Information System (INIS)

    Takai, Kenichi

    2000-01-01

    Secondary ion mass spectrometry (SIMS) enables us to visualize hydrogen trapping sites in steels. Information about the hydrogen trapping sites in high-strength steels by SIMS is very important to discuss environmental embrittlement mechanism for developing steels with a high resistance to the environmental embrittlement. Secondary ion image analysis by SIMS has made possible to visualize the hydrogen and deuterium trapping sites in the steels. Hydrogen in tempered martensite steels containing Ca tends to accumulate on inclusions, at grain boundaries, and in segregation bands. Visualization of hydrogen desorption process by secondary ion image analysis confirms that the bonding between the inclusions and the hydrogen is strong. Cold-drawn pearlite steels trap hydrogen along cold-drawing direction. Pearlite phase absorbs the hydrogen more than ferrite phase does. This article introduces the principle of SIMS, its feature, analysis method, and results of hydrogen visualization in steels. (author)

  2. Formal language constrained path problems

    Energy Technology Data Exchange (ETDEWEB)

    Barrett, C.; Jacob, R.; Marathe, M.

    1997-07-08

    In many path finding problems arising in practice, certain patterns of edge/vertex labels in the labeled graph being traversed are allowed/preferred, while others are disallowed. Motivated by such applications as intermodal transportation planning, the authors investigate the complexity of finding feasible paths in a labeled network, where the mode choice for each traveler is specified by a formal language. The main contributions of this paper include the following: (1) the authors show that the problem of finding a shortest path between a source and destination for a traveler whose mode choice is specified as a context free language is solvable efficiently in polynomial time, when the mode choice is specified as a regular language they provide algorithms with improved space and time bounds; (2) in contrast, they show that the problem of finding simple paths between a source and a given destination is NP-hard, even when restricted to very simple regular expressions and/or very simple graphs; (3) for the class of treewidth bounded graphs, they show that (i) the problem of finding a regular language constrained simple path between source and a destination is solvable in polynomial time and (ii) the extension to finding context free language constrained simple paths is NP-complete. Several extensions of these results are presented in the context of finding shortest paths with additional constraints. These results significantly extend the results in [MW95]. As a corollary of the results, they obtain a polynomial time algorithm for the BEST k-SIMILAR PATH problem studied in [SJB97]. The previous best algorithm was given by [SJB97] and takes exponential time in the worst case.

  3. The behavior of hydrogen in metals

    International Nuclear Information System (INIS)

    Hirabayashi, Makoto

    1975-01-01

    Explanation is made on the equilibrium diagrams of metal-hydrogen systems and the state of hydrogen in metals. Some metals perform exothermic reaction with hydrogen, and the others endothermic reaction. The former form stable hydrides and solid solutions over a wide range of composition. Hydrogen atoms in fcc and bcc metals are present at the interstitial positions of tetrahedron lattice and octahedron lattice. For example, hydrogen atoms in palladium are present at the intersititial positions of octahedron. When the ratio of the composition of hydrogen and palladium is 1:1, the structure becomes NaCl type. Hydrogen atoms in niobium and vanadium and present interstitially in tetrahedron lattice. Metal hydrides with high hydrogen concentration are becoming important recently as the containers of hydrogen. Hydrogen atoms diffuse in metals quite easily. The activation energy of the diffusion of hydrogen atoms in Nb and V is about 2-3 kcal/g.atom. The diffusion coefficient is about 10 -5 cm 2 /sec in alpha phase at room temperature. The number of jumps of a hydrogen atom between neighboring lattice sites is 10 11 --10 12 times per second. This datum is almost the same as that of liquid metals. Discussion is also made on the electronic state of hydrogen in metals. (Fukutomi, T.)

  4. Explaining evolution via constrained persistent perfect phylogeny

    Science.gov (United States)

    2014-01-01

    Background The perfect phylogeny is an often used model in phylogenetics since it provides an efficient basic procedure for representing the evolution of genomic binary characters in several frameworks, such as for example in haplotype inference. The model, which is conceptually the simplest, is based on the infinite sites assumption, that is no character can mutate more than once in the whole tree. A main open problem regarding the model is finding generalizations that retain the computational tractability of the original model but are more flexible in modeling biological data when the infinite site assumption is violated because of e.g. back mutations. A special case of back mutations that has been considered in the study of the evolution of protein domains (where a domain is acquired and then lost) is persistency, that is the fact that a character is allowed to return back to the ancestral state. In this model characters can be gained and lost at most once. In this paper we consider the computational problem of explaining binary data by the Persistent Perfect Phylogeny model (referred as PPP) and for this purpose we investigate the problem of reconstructing an evolution where some constraints are imposed on the paths of the tree. Results We define a natural generalization of the PPP problem obtained by requiring that for some pairs (character, species), neither the species nor any of its ancestors can have the character. In other words, some characters cannot be persistent for some species. This new problem is called Constrained PPP (CPPP). Based on a graph formulation of the CPPP problem, we are able to provide a polynomial time solution for the CPPP problem for matrices whose conflict graph has no edges. Using this result, we develop a parameterized algorithm for solving the CPPP problem where the parameter is the number of characters. Conclusions A preliminary experimental analysis shows that the constrained persistent perfect phylogeny model allows to

  5. Model study in chemisorption: atomic hydrogen on beryllium clusters

    International Nuclear Information System (INIS)

    Bauschlicher, C.W. Jr.

    1976-08-01

    The interaction between atomic hydrogen and the (0001) surface of Be metal has been studied by ab initio electronic structure theory. Self-consistent-field (SCF) calculations have been performed using minimum, optimized minimum, double zeta and mixed basis sets for clusters as large as 22 Be atoms. The binding energy and equilibrium geometry (the distance to the surface) were determined for 4 sites. Both spatially restricted (the wavefunction was constrained to transform as one of the irreducible representations of the molecular point group) and unrestricted SCF calculations were performed. Using only the optimized minimum basis set, clusters containing as many as 22 beryllium atoms have been investigated. From a variety of considerations, this cluster is seen to be nearly converged within the model used, providing the most reliable results for chemisorption. The site dependence of the frequency is shown to be a geometrical effect depending on the number and angle of the bonds. The diffusion of atomic hydrogen through a perfect beryllium crystal is predicted to be energetically unfavorable. The cohesive energy, the ionization energy and the singlet-triplet separation were computed for the clusters without hydrogen. These quantities can be seen as a measure of the total amount of edge effects. The chemisorptive properties are not related to the total amount of edge effects, but rather the edge effects felt by the adsorbate bonding berylliums. This lack of correlation with the total edge effects illustrates the local nature of the bonding, further strengthening the cluster model for chemisorption. A detailed discussion of the bonding and electronic structure is included. The remaining edge effects for the Be 22 cluster are discussed

  6. Metastable hydrogen

    International Nuclear Information System (INIS)

    Dose, V.

    1982-01-01

    This paper deals with the basic physical properties of the metastable 2 2 sub(1/2) state of atomic hydrogen. Applications relying on its special properties, including measurement of the Lamb shift, production of spin-polarized protons and the measurement of molecular electric moments, are discussed. (author)

  7. Industrial implications of hydrogen

    International Nuclear Information System (INIS)

    Pressouyre, G.M.

    1982-01-01

    Two major industrial implications of hydrogen are examined: problems related to the effect of hydrogen on materials properties (hydrogen embrittlement), and problems related to the use and production of hydrogen as a future energy vector [fr

  8. Wavelet library for constrained devices

    Science.gov (United States)

    Ehlers, Johan Hendrik; Jassim, Sabah A.

    2007-04-01

    The wavelet transform is a powerful tool for image and video processing, useful in a range of applications. This paper is concerned with the efficiency of a certain fast-wavelet-transform (FWT) implementation and several wavelet filters, more suitable for constrained devices. Such constraints are typically found on mobile (cell) phones or personal digital assistants (PDA). These constraints can be a combination of; limited memory, slow floating point operations (compared to integer operations, most often as a result of no hardware support) and limited local storage. Yet these devices are burdened with demanding tasks such as processing a live video or audio signal through on-board capturing sensors. In this paper we present a new wavelet software library, HeatWave, that can be used efficiently for image/video processing/analysis tasks on mobile phones and PDA's. We will demonstrate that HeatWave is suitable for realtime applications with fine control and range to suit transform demands. We shall present experimental results to substantiate these claims. Finally this library is intended to be of real use and applied, hence we considered several well known and common embedded operating system platform differences; such as a lack of common routines or functions, stack limitations, etc. This makes HeatWave suitable for a range of applications and research projects.

  9. How well do different tracers constrain the firn diffusivity profile?

    Directory of Open Access Journals (Sweden)

    C. M. Trudinger

    2013-02-01

    Full Text Available Firn air transport models are used to interpret measurements of the composition of air in firn and bubbles trapped in ice in order to reconstruct past atmospheric composition. The diffusivity profile in the firn is usually calibrated by comparing modelled and measured concentrations for tracers with known atmospheric history. However, in most cases this is an under-determined inverse problem, often with multiple solutions giving an adequate fit to the data (this is known as equifinality. Here we describe a method to estimate the firn diffusivity profile that allows multiple solutions to be identified, in order to quantify the uncertainty in diffusivity due to equifinality. We then look at how well different combinations of tracers constrain the firn diffusivity profile. Tracers with rapid atmospheric variations like CH3CCl3, HFCs and 14CO2 are most useful for constraining molecular diffusivity, while &delta:15N2 is useful for constraining parameters related to convective mixing near the surface. When errors in the observations are small and Gaussian, three carefully selected tracers are able to constrain the molecular diffusivity profile well with minimal equifinality. However, with realistic data errors or additional processes to constrain, there is benefit to including as many tracers as possible to reduce the uncertainties. We calculate CO2 age distributions and their spectral widths with uncertainties for five firn sites (NEEM, DE08-2, DSSW20K, South Pole 1995 and South Pole 2001 with quite different characteristics and tracers available for calibration. We recommend moving away from the use of a firn model with one calibrated parameter set to infer atmospheric histories, and instead suggest using multiple parameter sets, preferably with multiple representations of uncertain processes, to assist in quantification of the uncertainties.

  10. Order-constrained linear optimization.

    Science.gov (United States)

    Tidwell, Joe W; Dougherty, Michael R; Chrabaszcz, Jeffrey S; Thomas, Rick P

    2017-11-01

    Despite the fact that data and theories in the social, behavioural, and health sciences are often represented on an ordinal scale, there has been relatively little emphasis on modelling ordinal properties. The most common analytic framework used in psychological science is the general linear model, whose variants include ANOVA, MANOVA, and ordinary linear regression. While these methods are designed to provide the best fit to the metric properties of the data, they are not designed to maximally model ordinal properties. In this paper, we develop an order-constrained linear least-squares (OCLO) optimization algorithm that maximizes the linear least-squares fit to the data conditional on maximizing the ordinal fit based on Kendall's τ. The algorithm builds on the maximum rank correlation estimator (Han, 1987, Journal of Econometrics, 35, 303) and the general monotone model (Dougherty & Thomas, 2012, Psychological Review, 119, 321). Analyses of simulated data indicate that when modelling data that adhere to the assumptions of ordinary least squares, OCLO shows minimal bias, little increase in variance, and almost no loss in out-of-sample predictive accuracy. In contrast, under conditions in which data include a small number of extreme scores (fat-tailed distributions), OCLO shows less bias and variance, and substantially better out-of-sample predictive accuracy, even when the outliers are removed. We show that the advantages of OCLO over ordinary least squares in predicting new observations hold across a variety of scenarios in which researchers must decide to retain or eliminate extreme scores when fitting data. © 2017 The British Psychological Society.

  11. Solar hydrogen for urban trucks

    Energy Technology Data Exchange (ETDEWEB)

    Provenzano, J.: Scott, P.B.; Zweig, R. [Clean Air Now, Northridge, CA (United States)

    1997-12-31

    The Clean Air Now (CAN) Solar Hydrogen Project, located at Xerox Corp., El Segundo, California, includes solar photovoltaic powered hydrogen generation, compression, storage and end use. Three modified Ford Ranger trucks use the hydrogen fuel. The stand-alone electrolyzer and hydrogen dispensing system are solely powered by a photovoltaic array. A variable frequency DC-AC converter steps up the voltage to drive the 15 horsepower compressor motor. On site storage is available for up to 14,000 standard cubic feet (SCF) of solar hydrogen, and up to 80,000 SCF of commercial hydrogen. The project is 3 miles from Los Angeles International airport. The engine conversions are bored to 2.9 liter displacement and are supercharged. Performance is similar to that of the Ranger gasoline powered truck. Fuel is stored in carbon composite tanks (just behind the driver`s cab) at pressures up to 3600 psi. Truck range is 144 miles, given 3600 psi of hydrogen. The engine operates in lean burn mode, with nil CO and HC emissions. NO{sub x} emissions vary with load and rpm in the range from 10 to 100 ppm, yielding total emissions at a small fraction of the ULEV standard. Two trucks have been converted for the Xerox fleet, and one for the City of West Hollywood. A public outreach program, done in conjunction with the local public schools and the Department of Energy, introduces the local public to the advantages of hydrogen fuel technologies. The Clean Air Now program demonstrates that hydrogen powered fleet development is an appropriate, safe, and effective strategy for improvement of urban air quality, energy security and avoidance of global warming impact. Continued technology development and cost reduction promises to make such implementation market competitive.

  12. Information needs and instrumentation availability for hydrogen control and management

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jae Hong [Korea Institute of Nuclear Safety, Taejon (Korea, Republic of); Park, Gun Chul; Suh, Kune Y.; Lee, Seung Dong; Lee, Jin Yong [Seoul National Univ., Seoul (Korea, Republic of); Jae, Moo Sung [Hansung Univ., Seoul (Korea, Republic of)

    1999-03-15

    This study is concerned with development of comprehensive hydrogen management strategies based on identification of a severe accident condition and formulation of hydrogen models. Reducing containment hydrogen during a severe accident will mitigate a potential containment failure mechanism. One of the hydrogen control strategies is intentional burning by the hydrogen igniter. Though intentional hydrogen burn strategy will cause pressure and temperature spikes, it is the fastest way of reducing the containment hydrogen concentration. Based on the Westinghouse owners group Severe Accident Management Guidance (SAMG) hydrogen ignition decision tree was developed. From the information of decision tree, hydrogen ignition decision can be determined in Containment Event Tree (CET). We have examined previous hydrogen generation related models in fuel coolant interaction (FCI) and developed transient model for it. Using this model, we have simulated the Argonne National Laboratory (ANL) tests which are single droplet experiments, and Fully Instrumented Test Site (FITS) tests which contain dynamic fragmentation.

  13. The hydrogen; L'hydrogene

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    The hydrogen as an energy system represents nowadays a main challenge (in a scientific, economical and environmental point of view). The physical and chemical characteristics of hydrogen are at first given. Then, the challenges of an hydrogen economy are explained. The different possibilities of hydrogen production are described as well as the distribution systems and the different possibilities of hydrogen storage. Several fuel cells are at last presented: PEMFC, DMFC and SOFC. (O.M.)

  14. Hydrogen production in a PWR during LOCA

    International Nuclear Information System (INIS)

    Cassette, P.

    1984-01-01

    Hydrogen generation during a PWR LOCA has been estimated for design basis accident and for two more severe hypothetical accidents. Hydrogen production during design basis accident is a rather slow mechanism, allowing in the worst case, 15 days to connect a hydrogen recombining unit to the containment atmosphere monitoring system. Hydrogen generated by steam oxidation during more severe hypothetical accidents was found limited by steam availability and fuel melting phenomena. Uncertainty is, however, still remaining on corium-zirconium-steam interaction. In the worst case, calculations lead to the production of 500 kg of hydrogen, thus leading to a volume concentration of 15% in containment atmosphere, assuming homogeneous hydrogen distribution within the reactor building. This concentration is within flammability limits but not within detonation limits. However, hydrogen detonation due to local hydrogen accumulation cannot be discarded. A major uncertainty subsisting on hydrogen hazard is hydrogen distribution during the first hours of the accident. This point determines the effects and consequences of local detonation or deflagration which could possibly be harmful to safeguard systems, or induce missile generation in the reactor building. As electrical supply failures are identified as an important contributor to severe accident risk, corrective actions have been taken in France to improve their reliability, including the installation of a gas turbine on each site to supplement the existing sources. These actions are thus contributing to hydrogen hazard reduction

  15. Modeling the microstructural evolution during constrained sintering

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Frandsen, Henrik Lund; Tikare, V.

    A numerical model able to simulate solid state constrained sintering of a powder compact is presented. The model couples an existing kinetic Monte Carlo (kMC) model for free sintering with a finite element (FE) method for calculating stresses on a microstructural level. The microstructural response...... to the stress field as well as the FE calculation of the stress field from the microstructural evolution is discussed. The sintering behavior of two powder compacts constrained by a rigid substrate is simulated and compared to free sintering of the same samples. Constrained sintering result in a larger number...

  16. The hydrogen village: building hydrogen and fuel cell opportunities

    International Nuclear Information System (INIS)

    Smith, R.

    2006-01-01

    fuel cells; Fuel cell powered fork lifts and refueling facilities at industrial sites; Fuel cell-based back up power system for an internet service provider; Fuel cell-based back up power system at a telecommunications switching station;Fuel cell powered delivery vehicles and hydrogen production/refueling station; Hydrogen FC powered utility vehicles and hydrogen production/refueling station in downtown core; and, Some 15 additional projects are under development representing all program areas. (author)

  17. Hydrogen storage by physisorption on porous materials

    Energy Technology Data Exchange (ETDEWEB)

    Panella, B.

    2006-09-13

    A great challenge for commercializing hydrogen powered vehicles is on-board hydrogen storage using economic and secure systems. A possible solution is hydrogen storage in light-weight solid materials. Here three principle storage mechanisms can be distinguished: i) absorption of hydrogen in metals ii) formation of compounds with ionic character, like complex hydrides and iii) physisorption (or physical adsorption) of hydrogen molecules on porous materials. Physical adsorption exhibits several advantages over chemical hydrogen storage as for example the complete reversibility and the fast kinetics. Two classes of porous materials were investigated for physical hydrogen storage, i.e. different carbon nanostructures and crystalline metal-organic frameworks possessing extremely high specific surface area. Hydrogen adsorption isotherms were measured using a Sieverts' apparatus both at room temperature and at 77 K at pressures up to the saturation regime. Additionally, the adsorption sites of hydrogen in these porous materials were identified using thermal desorption spectroscopy extended to very low temperatures (down to 20 K). Furthermore, the adsorbed hydrogen phase was studied in various materials using Raman spectroscopy at different pressures and temperatures. The results show that the maximum hydrogen storage capacity of porous materials correlates linearly with the specific surface area and is independent of structure and composition. In addition the pore structure of the adsorbent plays an important role for hydrogen storage since the adsorption sites for H2 could be assigned to pores possessing different dimensions. Accordingly it was shown that small pores are necessary to reach high storage capacities already at low pressures. This new understanding may help to tailor and optimize new porous materials for hydrogen storage. (orig.)

  18. Hydrogen storage by physisorption on porous materials

    Energy Technology Data Exchange (ETDEWEB)

    Panella, B

    2006-09-13

    A great challenge for commercializing hydrogen powered vehicles is on-board hydrogen storage using economic and secure systems. A possible solution is hydrogen storage in light-weight solid materials. Here three principle storage mechanisms can be distinguished: i) absorption of hydrogen in metals ii) formation of compounds with ionic character, like complex hydrides and iii) physisorption (or physical adsorption) of hydrogen molecules on porous materials. Physical adsorption exhibits several advantages over chemical hydrogen storage as for example the complete reversibility and the fast kinetics. Two classes of porous materials were investigated for physical hydrogen storage, i.e. different carbon nanostructures and crystalline metal-organic frameworks possessing extremely high specific surface area. Hydrogen adsorption isotherms were measured using a Sieverts' apparatus both at room temperature and at 77 K at pressures up to the saturation regime. Additionally, the adsorption sites of hydrogen in these porous materials were identified using thermal desorption spectroscopy extended to very low temperatures (down to 20 K). Furthermore, the adsorbed hydrogen phase was studied in various materials using Raman spectroscopy at different pressures and temperatures. The results show that the maximum hydrogen storage capacity of porous materials correlates linearly with the specific surface area and is independent of structure and composition. In addition the pore structure of the adsorbent plays an important role for hydrogen storage since the adsorption sites for H2 could be assigned to pores possessing different dimensions. Accordingly it was shown that small pores are necessary to reach high storage capacities already at low pressures. This new understanding may help to tailor and optimize new porous materials for hydrogen storage. (orig.)

  19. Asymptotic Likelihood Distribution for Correlated & Constrained Systems

    CERN Document Server

    Agarwal, Ujjwal

    2016-01-01

    It describes my work as summer student at CERN. The report discusses the asymptotic distribution of the likelihood ratio for total no. of parameters being h and 2 out of these being are constrained and correlated.

  20. Constrained bidirectional propagation and stroke segmentation

    Energy Technology Data Exchange (ETDEWEB)

    Mori, S; Gillespie, W; Suen, C Y

    1983-03-01

    A new method for decomposing a complex figure into its constituent strokes is described. This method, based on constrained bidirectional propagation, is suitable for parallel processing. Examples of its application to the segmentation of Chinese characters are presented. 9 references.

  1. Mathematical Modeling of Constrained Hamiltonian Systems

    NARCIS (Netherlands)

    Schaft, A.J. van der; Maschke, B.M.

    1995-01-01

    Network modelling of unconstrained energy conserving physical systems leads to an intrinsic generalized Hamiltonian formulation of the dynamics. Constrained energy conserving physical systems are directly modelled as implicit Hamiltonian systems with regard to a generalized Dirac structure on the

  2. Client's Constraining Factors to Construction Project Management

    African Journals Online (AJOL)

    factors as a significant system that constrains project management success of public and ... finance for the project and prompt payment for work executed; clients .... consideration of the loading patterns of these variables, the major factor is ...

  3. Industrial view of Hydrogen Energy

    International Nuclear Information System (INIS)

    Francois Jackow

    2006-01-01

    Industrial Gases Companies have been mastering Hydrogen production, distribution, safe handling and applications for several decades for a wide range of gas applications. This unique industrial background positioned these companies to play a key role in the emerging Hydrogen Energy market, which can rely, at early stage of development, on already existing infrastructure, logistics and technical know-how. Nevertheless, it is important to acknowledge that Hydrogen Energy raised specific challenges which are not totally addressed by industrial gas activities. The main difference is obviously in the final customer profile, which differs significantly from the qualified professional our industry is used to serve. A non professional end-user, operating with Hydrogen at home or on board of his family car, has to be served with intrinsically safe and user-friendly solutions that exceed by far the industrial specifications already in place. Another significant challenge is that we will need breakthroughs both in terms of products and infrastructure, with development time frame that may require several decades. The aim of this presentation is to review how a company like Air Liquide, worldwide leader already operating more than 200 large hydrogen production sites, is approaching this new Hydrogen Energy market, all along the complete supply chain from production to end-users. Our contributions to the analysis, understanding and deployment of this new Energy market, will be illustrated by the presentation of Air Liquide internal development's as well as our participation in several national and European projects. (author)

  4. Energy infrastructure: hydrogen energy system

    Energy Technology Data Exchange (ETDEWEB)

    Veziroglu, T N

    1979-02-01

    In a hydrogen system, hydrogen is not a primary source of energy, but an intermediary, an energy carrier between the primary energy sources and the user. The new unconventional energy sources, such as nuclear breeder reactors, fusion reactors, direct solar radiation, wind energy, ocean thermal energy, and geothermal energy have their shortcomings. These shortcomings of the new sources point out to the need for an intermediary energy system to form the link between the primary energy sources and the user. In such a system, the intermediary energy form must be transportable and storable; economical to produce; and if possible renewable and pollution-free. The above prerequisites are best met by hydrogen. Hydrogen is plentiful in the form of water. It is the cheapest synthetic fuel to manufacture per unit of energy stored in it. It is the least polluting of all of the fuels, and is the lightest and recyclable. In the proposed system, hydrogen would be produced in large plants located away from the consumption centers at the sites where primary new energy sources and water are available. Hydrogen would then be transported to energy consumption centers where it would be used in every application where fossil fuels are being used today. Once such a system is established, it will never be necessary to change to any other energy system.

  5. On the origin of constrained superfields

    Energy Technology Data Exchange (ETDEWEB)

    Dall’Agata, G. [Dipartimento di Fisica “Galileo Galilei”, Università di Padova,Via Marzolo 8, 35131 Padova (Italy); INFN, Sezione di Padova,Via Marzolo 8, 35131 Padova (Italy); Dudas, E. [Centre de Physique Théorique, École Polytechnique, CNRS, Université Paris-Saclay,F-91128 Palaiseau (France); Farakos, F. [Dipartimento di Fisica “Galileo Galilei”, Università di Padova,Via Marzolo 8, 35131 Padova (Italy); INFN, Sezione di Padova,Via Marzolo 8, 35131 Padova (Italy)

    2016-05-06

    In this work we analyze constrained superfields in supersymmetry and supergravity. We propose a constraint that, in combination with the constrained goldstino multiplet, consistently removes any selected component from a generic superfield. We also describe its origin, providing the operators whose equations of motion lead to the decoupling of such components. We illustrate our proposal by means of various examples and show how known constraints can be reproduced by our method.

  6. Wind to Hydrogen in California: Case Study

    Energy Technology Data Exchange (ETDEWEB)

    Antonia, O.; Saur, G.

    2012-08-01

    This analysis presents a case study in California for a large scale, standalone wind electrolysis site. This is a techno-economic analysis of the 40,000 kg/day renewable production of hydrogen and subsequent delivery by truck to a fueling station in the Los Angeles area. This quantity of hydrogen represents about 1% vehicle market penetration for a city such as Los Angeles (assuming 0.62 kg/day/vehicle and 0.69 vehicles/person) [8]. A wind site near the Mojave Desert was selected for proximity to the LA area where hydrogen refueling stations are already built.

  7. Low-CO(2) electricity and hydrogen: a help or hindrance for electric and hydrogen vehicles?

    Science.gov (United States)

    Wallington, T J; Grahn, M; Anderson, J E; Mueller, S A; Williander, M I; Lindgren, K

    2010-04-01

    The title question was addressed using an energy model that accounts for projected global energy use in all sectors (transportation, heat, and power) of the global economy. Global CO(2) emissions were constrained to achieve stabilization at 400-550 ppm by 2100 at the lowest total system cost (equivalent to perfect CO(2) cap-and-trade regime). For future scenarios where vehicle technology costs were sufficiently competitive to advantage either hydrogen or electric vehicles, increased availability of low-cost, low-CO(2) electricity/hydrogen delayed (but did not prevent) the use of electric/hydrogen-powered vehicles in the model. This occurs when low-CO(2) electricity/hydrogen provides more cost-effective CO(2) mitigation opportunities in the heat and power energy sectors than in transportation. Connections between the sectors leading to this counterintuitive result need consideration in policy and technology planning.

  8. Constrained Unfolding of a Helical Peptide: Implicit versus Explicit Solvents.

    Directory of Open Access Journals (Sweden)

    Hailey R Bureau

    Full Text Available Steered Molecular Dynamics (SMD has been seen to provide the potential of mean force (PMF along a peptide unfolding pathway effectively but at significant computational cost, particularly in all-atom solvents. Adaptive steered molecular dynamics (ASMD has been seen to provide a significant computational advantage by limiting the spread of the trajectories in a staged approach. The contraction of the trajectories at the end of each stage can be performed by taking a structure whose nonequilibrium work is closest to the Jarzynski average (in naive ASMD or by relaxing the trajectories under a no-work condition (in full-relaxation ASMD--namely, FR-ASMD. Both approaches have been used to determine the energetics and hydrogen-bonding structure along the pathway for unfolding of a benchmark peptide initially constrained as an α-helix in a water environment. The energetics are quite different to those in vacuum, but are found to be similar between implicit and explicit solvents. Surprisingly, the hydrogen-bonding pathways are also similar in the implicit and explicit solvents despite the fact that the solvent contact plays an important role in opening the helix.

  9. Destructive hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Terrisse, H; Dufour, L

    1929-01-21

    Oils of high boiling point, e.g. gas oil, lamp oil, schist oil, brown coal tar etc., are converted into motor benzine by heating them at 200 to 500/sup 0/C under pressure of 5 to 40 kilograms/cm/sup 2/ in the presence of ferrous chloride and gases such as hydrogen, or water gas, the desulfurization of the oils proceeding simultaneously. One kilogram of lamp oil and 100 g. ferrous chloride are heated in an autoclave in the presence of water gas under a pressure of 18 kg/cm/sup 2/ to 380 to 400/sup 0/C. The gaseous products are allowed to escape intermittently and are replaced by fresh water gas. A product distilling between 35 and 270/sup 0/C is obtained.

  10. Regulatory and standard issues on hydrogen in 2009. Investigation report

    International Nuclear Information System (INIS)

    Tigreat, Delphine

    2009-01-01

    This report proposes an overview of the French and European regulations and standards regarding the use of hydrogen as an energy vector. The European and French regulations concern hydrogen production, storage and use on site and in transports of hazardous goods, the homologation of hydrogen powered vehicles, or the transport of hydrogen in ducts. Some standards are presented. A comparison is proposed between France and Germany, other European countries and the USA

  11. Hydrogen-based industry from remote excess hydroelectricity

    International Nuclear Information System (INIS)

    Ouellette, N.; Rogner, H.-H.; Scott, D.S.

    1997-01-01

    This paper examines synergies, opportunities and barriers associated with hydrogen and excess hydro-electricity in remote areas. The work is based on a case study that examined the techno-economic feasibility of a new hydrogen-based industry using surplus/off-peak generating capacity of the Taltson Dam and Generating Station in the Northwest Territories, Canada. After evaluating the amount and cost of hydrogen that could be produced from the excess capacity, the study investigates three hydrogen utilization scenarios: (1) merchant liquid or compressed hydrogen, (2) hydrogen as a chemical feedstock for the production of hydrogen peroxide, (3) methanol production from biomass, oxygen and hydrogen. Hydrogen peroxide production is the most promising and attractive strategy in the Fort Smith context. The study also illustrates patterns that recur in isolated sites throughout the world. (Author)

  12. Hydrogen Bonds and Life in the Universe

    Directory of Open Access Journals (Sweden)

    Giovanni Vladilo

    2018-01-01

    Full Text Available The scientific community is allocating more and more resources to space missions and astronomical observations dedicated to the search for life beyond Earth. This experimental endeavor needs to be backed by a theoretical framework aimed at defining universal criteria for the existence of life. With this aim in mind, we have explored which chemical and physical properties should be expected for life possibly different from the terrestrial one, but similarly sustained by genetic and catalytic molecules. We show that functional molecules performing genetic and catalytic tasks must feature a hierarchy of chemical interactions operating in distinct energy bands. Of all known chemical bonds and forces, only hydrogen bonds are able to mediate the directional interactions of lower energy that are needed for the operation of genetic and catalytic tasks. For this reason and because of the unique quantum properties of hydrogen bonding, the functional molecules involved in life processes are predicted to have extensive hydrogen-bonding capabilities. A molecular medium generating a hydrogen-bond network is probably essential to support the activity of the functional molecules. These hydrogen-bond requirements constrain the viability of hypothetical biochemistries alternative to the terrestrial one, provide thermal limits to life molecular processes, and offer a conceptual framework to define a transition from a “covalent-bond stage” to a “hydrogen-bond stage” in prebiotic chemistry.

  13. Hydrogen Bonds and Life in the Universe

    Science.gov (United States)

    2018-01-01

    The scientific community is allocating more and more resources to space missions and astronomical observations dedicated to the search for life beyond Earth. This experimental endeavor needs to be backed by a theoretical framework aimed at defining universal criteria for the existence of life. With this aim in mind, we have explored which chemical and physical properties should be expected for life possibly different from the terrestrial one, but similarly sustained by genetic and catalytic molecules. We show that functional molecules performing genetic and catalytic tasks must feature a hierarchy of chemical interactions operating in distinct energy bands. Of all known chemical bonds and forces, only hydrogen bonds are able to mediate the directional interactions of lower energy that are needed for the operation of genetic and catalytic tasks. For this reason and because of the unique quantum properties of hydrogen bonding, the functional molecules involved in life processes are predicted to have extensive hydrogen-bonding capabilities. A molecular medium generating a hydrogen-bond network is probably essential to support the activity of the functional molecules. These hydrogen-bond requirements constrain the viability of hypothetical biochemistries alternative to the terrestrial one, provide thermal limits to life molecular processes, and offer a conceptual framework to define a transition from a “covalent-bond stage” to a “hydrogen-bond stage” in prebiotic chemistry. PMID:29301382

  14. Hydrogen Bonds and Life in the Universe.

    Science.gov (United States)

    Vladilo, Giovanni; Hassanali, Ali

    2018-01-03

    The scientific community is allocating more and more resources to space missions and astronomical observations dedicated to the search for life beyond Earth. This experimental endeavor needs to be backed by a theoretical framework aimed at defining universal criteria for the existence of life. With this aim in mind, we have explored which chemical and physical properties should be expected for life possibly different from the terrestrial one, but similarly sustained by genetic and catalytic molecules. We show that functional molecules performing genetic and catalytic tasks must feature a hierarchy of chemical interactions operating in distinct energy bands. Of all known chemical bonds and forces, only hydrogen bonds are able to mediate the directional interactions of lower energy that are needed for the operation of genetic and catalytic tasks. For this reason and because of the unique quantum properties of hydrogen bonding, the functional molecules involved in life processes are predicted to have extensive hydrogen-bonding capabilities. A molecular medium generating a hydrogen-bond network is probably essential to support the activity of the functional molecules. These hydrogen-bond requirements constrain the viability of hypothetical biochemistries alternative to the terrestrial one, provide thermal limits to life molecular processes, and offer a conceptual framework to define a transition from a "covalent-bond stage" to a "hydrogen-bond stage" in prebiotic chemistry.

  15. On the hydrogen atom via Wigner-Heisenberg algebra

    International Nuclear Information System (INIS)

    Rodrigues, R. de Lima . Unidade Academica de Educacao.

    2008-01-01

    We extend the usual Kustaanheimo-Stiefel 4D → 3D mapping to study and discuss a constrained super-Wigner oscillator in four dimensions. We show that the physical hydrogen atom is the system that emerges in the bosonic sector of the mapped super 3D system. (author)

  16. Renewable solar hydrogen production and utilization

    International Nuclear Information System (INIS)

    Bakos, J.

    2006-01-01

    There is a tremendous opportunity to generate large quantities of hydrogen from low grade and economical sources of methane including landfill gas, biogas, flare gas, and coal bed methane. The environmental benefits of generating hydrogen using renewable energy include significant greenhouse gas and air contaminant reductions. Solar Hydrogen Energy Corporation (SHEC LABS) recently constructed and demonstrated a Dry Fuel Reforming (DFR) hydrogen generation system that is powered primarily by sunlight focusing-mirrors in Tempe, Arizona. The system comprises a solar mirror array, a temperature controlling shutter system, and two thermo-catalytic reactors to convert methane, carbon dioxide, and water into hydrogen. This process has shown that solar hydrogen generation is feasible and cost-competitive with traditional hydrogen production. The presentation will provide the following: An overview of the results of the testing conducted in Tempe, Arizona; A look at the design and installation of the scaled-up technology site at a landfill site in Canada; An examination of the economic and environmental benefits of renewable hydrogen production using solar energy

  17. Al and Si Influences on Hydrogen Embrittlement of Carbide-Free Bainitic Steel

    Directory of Open Access Journals (Sweden)

    Yanguo Li

    2013-01-01

    Full Text Available A first-principle method based on the density functional theory was applied to investigate the Al and Si influences on the hydrogen embrittlement of carbide-free bainitic steel. The hydrogen preference site, binding energy, diffusion behaviour, and electronic structure were calculated. The results showed that hydrogen preferred to be at the tetrahedral site. The binding energy of the cell with Si was the highest and it was decreased to be the worst by adding hydrogen. The diffusion barrier of hydrogen in the cell containing Al was the highest, so it was difficult for hydrogen to diffuse. Thus, hydrogen embrittlement can be reduced by Al rather than Si.

  18. Hydrogen converters

    International Nuclear Information System (INIS)

    Mondino, Angel V.

    2003-01-01

    The National Atomic Energy Commission of Argentina developed a process of 99 Mo production from fission, based on irradiation of uranium aluminide targets with thermal neutrons in the RA-3 reactor of the Ezeiza Atomic Centre. These targets are afterwards dissolved in an alkaline solution, with the consequent liberation of hydrogen as the main gaseous residue. This work deals with the use of a first model of metallic converter and a later prototype of glass converter at laboratory scale, adjusted to the requirements and conditions of the specific redox process. Oxidized copper wires were used, which were reduced to elementary copper at 400 C degrees and then regenerated by oxidation with hot air. Details of the bed structure and the operation conditions are also provided. The equipment required for the assembling in cells is minimal and, taking into account the operation final temperature and the purge with nitrogen, the procedure is totally safe. Finally, the results are extrapolated for the design of a converter to be used in a hot cell. (author)

  19. Towards weakly constrained double field theory

    Directory of Open Access Journals (Sweden)

    Kanghoon Lee

    2016-08-01

    Full Text Available We show that it is possible to construct a well-defined effective field theory incorporating string winding modes without using strong constraint in double field theory. We show that X-ray (Radon transform on a torus is well-suited for describing weakly constrained double fields, and any weakly constrained fields are represented as a sum of strongly constrained fields. Using inverse X-ray transform we define a novel binary operation which is compatible with the level matching constraint. Based on this formalism, we construct a consistent gauge transform and gauge invariant action without using strong constraint. We then discuss the relation of our result to the closed string field theory. Our construction suggests that there exists an effective field theory description for massless sector of closed string field theory on a torus in an associative truncation.

  20. Continuation of Sets of Constrained Orbit Segments

    DEFF Research Database (Denmark)

    Schilder, Frank; Brøns, Morten; Chamoun, George Chaouki

    Sets of constrained orbit segments of time continuous flows are collections of trajectories that represent a whole or parts of an invariant set. A non-trivial but simple example is a homoclinic orbit. A typical representation of this set consists of an equilibrium point of the flow and a trajectory...... that starts close and returns close to this fixed point within finite time. More complicated examples are hybrid periodic orbits of piecewise smooth systems or quasi-periodic invariant tori. Even though it is possible to define generalised two-point boundary value problems for computing sets of constrained...... orbit segments, this is very disadvantageous in practice. In this talk we will present an algorithm that allows the efficient continuation of sets of constrained orbit segments together with the solution of the full variational problem....

  1. Progress in hydrogen fueled busses

    International Nuclear Information System (INIS)

    Scott, P.B.; Mazaika, D.M.; Tyler, T.

    2004-01-01

    'Full text:' The Thor/ISE fuel cell bus has been in demonstration and revenue service during 2002-2003 at sites including SunLine Transit, Chula Vista Transit, Los Angeles County Metropolitan Transit Authority, and AC Transit in Oakland. By taking advantage of ISE's advanced hybrid-electric drive technology, this 30-foot bus operates with a much smaller fuel cell than those used in other buses of this class. Further, stress on the fuel cell is diminished. Based on the exceptional performance of this prototype bus, the transit agencies listed above have concluded that hybrid electric hydrogen fueled buses are attractive. Two types of hydrogen fueled hybrid electric buses will be described: - fuel cell powered, and - HICE (Hydrogen Internal Combustion Engine) This progress report will include: 1. Experience with the Thor/ISE fuel cell bus, including results from revenue service at two transit locations, 2. Design and fabrication status of the advanced fuel cell buses being built for AC Transit and SunLine Transit, 3. Design and fabrication status of the prototype HHICE (Hybrid electric Hydrogen fueled Internal Combustion Engine) bus that uses a Ford hydrogen burning engine, mated to a generator, rather than a fuel cell. Other than the engine, the drive train in the HHICE bus is nearly identical to that of a fuel cell hybrid-electric bus. Canadian participation in the HHICE bus is extensive, it is a New Flyer platform and will be winter tested in Winnipeg. (author)

  2. Constrained principal component analysis and related techniques

    CERN Document Server

    Takane, Yoshio

    2013-01-01

    In multivariate data analysis, regression techniques predict one set of variables from another while principal component analysis (PCA) finds a subspace of minimal dimensionality that captures the largest variability in the data. How can regression analysis and PCA be combined in a beneficial way? Why and when is it a good idea to combine them? What kind of benefits are we getting from them? Addressing these questions, Constrained Principal Component Analysis and Related Techniques shows how constrained PCA (CPCA) offers a unified framework for these approaches.The book begins with four concre

  3. Predictions of glass transition temperature for hydrogen bonding biomaterials.

    Science.gov (United States)

    van der Sman, R G M

    2013-12-19

    We show that the glass transition of a multitude of mixtures containing hydrogen bonding materials correlates strongly with the effective number of hydroxyl groups per molecule, which are available for intermolecular hydrogen bonding. This correlation is in compliance with the topological constraint theory, wherein the intermolecular hydrogen bonds constrain the mobility of the hydrogen bonded network. The finding that the glass transition relates to hydrogen bonding rather than free volume agrees with our recent finding that there is little difference in free volume among carbohydrates and polysaccharides. For binary and ternary mixtures of sugars, polyols, or biopolymers with water, our correlation states that the glass transition temperature is linear with the inverse of the number of effective hydroxyl groups per molecule. Only for dry biopolymer/sugar or sugar/polyol mixtures do we find deviations due to nonideal mixing, imposed by microheterogeneity.

  4. Study of hydrogen implanted in aluminium

    International Nuclear Information System (INIS)

    Bugeat, J.P.; Chami, A.C.; Danielou, R.; Ligeon, E.

    1976-01-01

    An aluminium sample was implanted with deuterium and hydrogen at 5keV and 10keV respectively. The 1 H( 11 B,α) 8 Be* and D( 3 He,p) 4 He reactions were used for the analysis of H and D respectively. The implanted deuterium was shown to be as a whole in a tetrahedral site as far as the implantation temperature is lower than 175K, beyond that temperature the deuterium is randomly located. When the implantation temperature increases from 33K up to 275K the tetrahedral siting remains during annealing. The migration temperatures of hydrogen (or temperature of transition from the tetrahedral siting to a random distribution) experimentally observed during annealing (300K) and for increased implantation temperatures, show that the tetrahedral site is associated with a monovacancy migrating at 300K, the diffusion temperature of hydrogen being lower than 180K [fr

  5. Fusion facility siting considerations

    International Nuclear Information System (INIS)

    Bussell, G.T.

    1985-01-01

    Inherent in the fusion program's transition from hydrogen devices to commercial power machines is a general increase in the size and scope of succeeding projects. This growth will lead to increased emphasis on safety, environmental impact, and the external effects of fusion in general, and of each new device in particular. A critically important consideration in this regard is site selection. The purpose of this paper is to examine major siting issues that may affect the economics, safety, and environmental impact of fusion

  6. Electric arc hydrogen heaters

    International Nuclear Information System (INIS)

    Zasypin, I.M.

    2000-01-01

    The experimental data on the electric arc burning in hydrogen are presented. Empirical and semiempirical dependences for calculating the arc characteristics are derived. An engineering method of calculating plasma torches for hydrogen heating is proposed. A model of interaction of a hydrogen arc with a gas flow is outlined. The characteristics of plasma torches for heating hydrogen and hydrogen-bearing gases are described. (author)

  7. Estimation of optimal capacity of the module through the demand analysis of refinery hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Young-Seek; Kim, Ho-Jin; Kim, Il-Su [SK energy Institution of Technology, Daejeon (Korea, Republic of)] (and others)

    2006-02-15

    Hydrogen is focused as energy carrier, not an energy source on the rising of problems such as exhaustion of fossil fuel and environment pollution. Thermochemical hydrogen production by nuclear energy has potential to efficiently produce large quantities of hydrogen without producing greenhouse gases. The oil refiners and petro-chemical plant are very large, centralized producers and users of industrial hydrogen, and they a high-potential early market for hydrogen produced by nuclear energy. Therefore, hydrogen market of petro-chemical industry as demand site for nuclear hydrogen was investigated and worked for demand forecast of hydrogen in 2020. Also we suggested possible supply plans of nuclear hydrogen considered regional characteristics. The hydrogen production cost was analyzed and estimated for nuclear hydrogen as well as conventional hydrogen production such as natural gas reforming and coal gasification in various range.

  8. Estimation of optimal capacity of the module through the demand analysis of refinery hydrogen

    International Nuclear Information System (INIS)

    Yoon, Young-Seek; Kim, Ho-Jin; Kim, Il-Su

    2006-02-01

    Hydrogen is focused as energy carrier, not an energy source on the rising of problems such as exhaustion of fossil fuel and environment pollution. Thermochemical hydrogen production by nuclear energy has potential to efficiently produce large quantities of hydrogen without producing greenhouse gases. The oil refiners and petro-chemical plant are very large, centralized producers and users of industrial hydrogen, and they a high-potential early market for hydrogen produced by nuclear energy. Therefore, hydrogen market of petro-chemical industry as demand site for nuclear hydrogen was investigated and worked for demand forecast of hydrogen in 2020. Also we suggested possible supply plans of nuclear hydrogen considered regional characteristics. The hydrogen production cost was analyzed and estimated for nuclear hydrogen as well as conventional hydrogen production such as natural gas reforming and coal gasification in various range

  9. On Tree-Constrained Matchings and Generalizations

    NARCIS (Netherlands)

    S. Canzar (Stefan); K. Elbassioni; G.W. Klau (Gunnar); J. Mestre

    2011-01-01

    htmlabstractWe consider the following \\textsc{Tree-Constrained Bipartite Matching} problem: Given two rooted trees $T_1=(V_1,E_1)$, $T_2=(V_2,E_2)$ and a weight function $w: V_1\\times V_2 \\mapsto \\mathbb{R}_+$, find a maximum weight matching $\\mathcal{M}$ between nodes of the two trees, such that

  10. Constrained systems described by Nambu mechanics

    International Nuclear Information System (INIS)

    Lassig, C.C.; Joshi, G.C.

    1996-01-01

    Using the framework of Nambu's generalised mechanics, we obtain a new description of constrained Hamiltonian dynamics, involving the introduction of another degree of freedom in phase space, and the necessity of defining the action integral on a world sheet. We also discuss the problem of quantizing Nambu mechanics. (authors). 5 refs

  11. Client's constraining factors to construction project management ...

    African Journals Online (AJOL)

    This study analyzed client's related factors that constrain project management success of public and private sector construction in Nigeria. Issues that concern clients in any project can not be undermined as they are the owners and the initiators of project proposals. It is assumed that success, failure or abandonment of ...

  12. Hyperbolicity and constrained evolution in linearized gravity

    International Nuclear Information System (INIS)

    Matzner, Richard A.

    2005-01-01

    Solving the 4-d Einstein equations as evolution in time requires solving equations of two types: the four elliptic initial data (constraint) equations, followed by the six second order evolution equations. Analytically the constraint equations remain solved under the action of the evolution, and one approach is to simply monitor them (unconstrained evolution). Since computational solution of differential equations introduces almost inevitable errors, it is clearly 'more correct' to introduce a scheme which actively maintains the constraints by solution (constrained evolution). This has shown promise in computational settings, but the analysis of the resulting mixed elliptic hyperbolic method has not been completely carried out. We present such an analysis for one method of constrained evolution, applied to a simple vacuum system, linearized gravitational waves. We begin with a study of the hyperbolicity of the unconstrained Einstein equations. (Because the study of hyperbolicity deals only with the highest derivative order in the equations, linearization loses no essential details.) We then give explicit analytical construction of the effect of initial data setting and constrained evolution for linearized gravitational waves. While this is clearly a toy model with regard to constrained evolution, certain interesting features are found which have relevance to the full nonlinear Einstein equations

  13. A Dynamic Programming Approach to Constrained Portfolios

    DEFF Research Database (Denmark)

    Kraft, Holger; Steffensen, Mogens

    2013-01-01

    This paper studies constrained portfolio problems that may involve constraints on the probability or the expected size of a shortfall of wealth or consumption. Our first contribution is that we solve the problems by dynamic programming, which is in contrast to the existing literature that applies...

  14. A model for optimal constrained adaptive testing

    NARCIS (Netherlands)

    van der Linden, Willem J.; Reese, Lynda M.

    2001-01-01

    A model for constrained computerized adaptive testing is proposed in which the information on the test at the ability estimate is maximized subject to a large variety of possible constraints on the contents of the test. At each item-selection step, a full test is first assembled to have maximum

  15. A model for optimal constrained adaptive testing

    NARCIS (Netherlands)

    van der Linden, Willem J.; Reese, Lynda M.

    1997-01-01

    A model for constrained computerized adaptive testing is proposed in which the information in the test at the ability estimate is maximized subject to a large variety of possible constraints on the contents of the test. At each item-selection step, a full test is first assembled to have maximum

  16. Neutron Powder Diffraction and Constrained Refinement

    DEFF Research Database (Denmark)

    Pawley, G. S.; Mackenzie, Gordon A.; Dietrich, O. W.

    1977-01-01

    The first use of a new program, EDINP, is reported. This program allows the constrained refinement of molecules in a crystal structure with neutron diffraction powder data. The structures of p-C6F4Br2 and p-C6F4I2 are determined by packing considerations and then refined with EDINP. Refinement is...

  17. Terrestrial Sagnac delay constraining modified gravity models

    Science.gov (United States)

    Karimov, R. Kh.; Izmailov, R. N.; Potapov, A. A.; Nandi, K. K.

    2018-04-01

    Modified gravity theories include f(R)-gravity models that are usually constrained by the cosmological evolutionary scenario. However, it has been recently shown that they can also be constrained by the signatures of accretion disk around constant Ricci curvature Kerr-f(R0) stellar sized black holes. Our aim here is to use another experimental fact, viz., the terrestrial Sagnac delay to constrain the parameters of specific f(R)-gravity prescriptions. We shall assume that a Kerr-f(R0) solution asymptotically describes Earth's weak gravity near its surface. In this spacetime, we shall study oppositely directed light beams from source/observer moving on non-geodesic and geodesic circular trajectories and calculate the time gap, when the beams re-unite. We obtain the exact time gap called Sagnac delay in both cases and expand it to show how the flat space value is corrected by the Ricci curvature, the mass and the spin of the gravitating source. Under the assumption that the magnitude of corrections are of the order of residual uncertainties in the delay measurement, we derive the allowed intervals for Ricci curvature. We conclude that the terrestrial Sagnac delay can be used to constrain the parameters of specific f(R) prescriptions. Despite using the weak field gravity near Earth's surface, it turns out that the model parameter ranges still remain the same as those obtained from the strong field accretion disk phenomenon.

  18. Chance constrained uncertain classification via robust optimization

    NARCIS (Netherlands)

    Ben-Tal, A.; Bhadra, S.; Bhattacharayya, C.; Saketha Nat, J.

    2011-01-01

    This paper studies the problem of constructing robust classifiers when the training is plagued with uncertainty. The problem is posed as a Chance-Constrained Program (CCP) which ensures that the uncertain data points are classified correctly with high probability. Unfortunately such a CCP turns out

  19. Integrating job scheduling and constrained network routing

    DEFF Research Database (Denmark)

    Gamst, Mette

    2010-01-01

    This paper examines the NP-hard problem of scheduling jobs on resources such that the overall profit of executed jobs is maximized. Job demand must be sent through a constrained network to the resource before execution can begin. The problem has application in grid computing, where a number...

  20. Neuroevolutionary Constrained Optimization for Content Creation

    DEFF Research Database (Denmark)

    Liapis, Antonios; Yannakakis, Georgios N.; Togelius, Julian

    2011-01-01

    and thruster types and topologies) independently of game physics and steering strategies. According to the proposed framework, the designer picks a set of requirements for the spaceship that a constrained optimizer attempts to satisfy. The constraint satisfaction approach followed is based on neuroevolution...... and survival tasks and are also visually appealing....

  1. Models of Flux Tubes from Constrained Relaxation

    Indian Academy of Sciences (India)

    tribpo

    J. Astrophys. Astr. (2000) 21, 299 302. Models of Flux Tubes from Constrained Relaxation. Α. Mangalam* & V. Krishan†, Indian Institute of Astrophysics, Koramangala,. Bangalore 560 034, India. *e mail: mangalam @ iiap. ernet. in. † e mail: vinod@iiap.ernet.in. Abstract. We study the relaxation of a compressible plasma to ...

  2. Zero emission distributed hydrogen production

    International Nuclear Information System (INIS)

    Maddaloni, J.; Rowe, A.; Bailey, R.; McDonald, J.D.

    2004-01-01

    The need for distributed production facilities has become a critical issue in developing a hydrogen infrastructure. Hydrogen generation using processes that make effective use of what would normally be considered waste streams or process inefficiencies can have more favorable economics than stand-alone technologies. Currently, natural gas is distributed to industrial and residential customers through a network of pipelines. High pressure main lines move gas to the vicinity of consumers where the pressure is reduced for local, low pressure distribution. Often, the practice is to use an isenthalpic expansion which results in a cooling of the gas stream. Some of the natural gas is burned to preheat the fuel so that the temperature after the expansion is near ambient. This results in the destruction of exergy in the high pressure gas stream and produces CO 2 in the process. If, instead, a turbo-expander is used to reduce the stream pressure, work can be recovered using a generator and hydrogen can be produced via electrolysis. This method of hydrogen production is free of green-house gas emissions, makes use of existing gas distribution facilities, and uses exergy that would otherwise be destroyed. Pressure reduction using the work producing process (turbo-expander) is accompanied by a large drop in temperature, on the average of 70 K. The local gas distributor requires the gas temperature to be raised again to near 8 o C to prevent damage to valve assemblies. The required heating power after expansion can be on the order of megawatts (site dependent.) Supplying the heat can be seen as a cost if energy is taken from the system to reheat the fuel; however, the low temperature stream may also be considered an asset if the cooling power can be used for a local process. This analysis is the second stage of a study to examine the technical and economic feasibility of using pressure let-down sites as hydrogen production facilities. This paper describes a proposed

  3. Hycom Pre - Feasibility study. Final report[Hydrogen communities

    Energy Technology Data Exchange (ETDEWEB)

    Lacobazzi, A; Mario, F di [ENEA, (Italy); Hasenauer, U [Fraunhofer IS, (Germany); Joergensen, B H; Bromand Noergaard, P [Risoe National Lab., (Denmark)

    2005-07-01

    The Quick-start Programme of the European Union Initiative for Growth identifies the hydrogen economy as one of the key areas for investment in the medium term (2004-2015). In this context the HyCOM (Hydrogen Communities) programme has been initiated. The main goal of this programme is the creation of a limited number of strategically sited stand-alone hydrogen communities producing hydrogen from various primary sources (mostly renewables) and using it for heat and electricity production and as fuel for vehicles. This report looks at the establishment of such hydrogen communities, analysing the main technical, economic, social, and environmental aspects as well as financial and regulatory barriers associated with the creation and operation of hydrogen communities. It also proposes a number of concepts for Hydrogen Communities and criteria with which a Hydrogen Community should be evaluated. The study is not in any way intended to be prescriptive. (ln)

  4. Anelastic mechanical loss spectrometry of hydrogen in austenitic stainless steels

    International Nuclear Information System (INIS)

    Yagodzinskyy, Y.; Andronova, E.; Ivanchenko, M.; Haenninen, H.

    2009-01-01

    Atomic distribution of hydrogen, its elemental diffusion jumps and its interaction with dislocations in a number of austenitic stainless steels are studied with anelastic mechanical loss (AML) spectrometry in combination with the hydrogen thermal desorption method. Austenitic stainless steels of different chemical composition, namely, AISI 310, AISI 201, and AISI 301LN, as well as LDX 2101 duplex stainless steel are studied to clarify the role of different alloying elements on the hydrogen behavior. Activation analyses of the hydrogen Snoek-like peaks are performed with their decomposition to sets of Gaussian components. Fine structure of the composite hydrogen peaks is analyzed under the assumption that each component corresponds to diffusion transfer of hydrogen between octahedral positions with certain atomic compositions of the nearest neighbouring lattice sites. An additional component originating from hydrogen-dislocation interaction is considered. Binding energies for hydrogen-dislocation interaction are also estimated for the studied austenitic stainless steels.

  5. Why hydrogen; Pourquoi l'hydrogene?

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-02-01

    The energy consumption increase and the associated environmental risks, led to develop new energy sources. The authors present the potentialities of the hydrogen in this context of energy supply safety. They detail the today market and the perspectives, the energy sources for the hydrogen production (fossils, nuclear and renewable), the hydrogen transport, storage, distribution and conversion, the application domains, the associated risks. (A.L.B.)

  6. Hydrogen fuel. Uses

    International Nuclear Information System (INIS)

    Darkrim-Lamari, F.; Malbrunot, P.

    2006-01-01

    Hydrogen is a very energetic fuel which can be used in combustion to generate heat and mechanical energy or which can be used to generate electricity and heat through an electrochemical reaction with oxygen. This article deals with the energy conversion, the availability and safety problems linked with the use of hydrogen, and with the socio-economical consequences of a generalized use of hydrogen: 1 - hydrogen energy conversion: hydrogen engines, aerospace applications, fuel cells (principle, different types, domains of application); 2 - hydrogen energy availability: transport and storage (gas pipelines, liquid hydrogen, adsorbed and absorbed hydrogen in solid materials), service stations; 3 - hazards and safety: flammability, explosibility, storage and transport safety, standards and regulations; 4 - hydrogen economy; 5 - conclusion. (J.S.)

  7. Hydrogen energy systems studies

    Energy Technology Data Exchange (ETDEWEB)

    Ogden, J.M.; Kreutz, T.G.; Steinbugler, M. [Princeton Univ., NJ (United States)] [and others

    1996-10-01

    In this report the authors describe results from technical and economic assessments carried out during the past year with support from the USDOE Hydrogen R&D Program. (1) Assessment of technologies for small scale production of hydrogen from natural gas. Because of the cost and logistics of transporting and storing hydrogen, it may be preferable to produce hydrogen at the point of use from more readily available energy carriers such as natural gas or electricity. In this task the authors assess near term technologies for producing hydrogen from natural gas at small scale including steam reforming, partial oxidation and autothermal reforming. (2) Case study of developing a hydrogen vehicle refueling infrastructure in Southern California. Many analysts suggest that the first widespread use of hydrogen energy is likely to be in zero emission vehicles in Southern California. Several hundred thousand zero emission automobiles are projected for the Los Angeles Basin alone by 2010, if mandated levels are implemented. Assuming that hydrogen vehicles capture a significant fraction of this market, a large demand for hydrogen fuel could evolve over the next few decades. Refueling a large number of hydrogen vehicles poses significant challenges. In this task the authors assess near term options for producing and delivering gaseous hydrogen transportation fuel to users in Southern California including: (1) hydrogen produced from natural gas in a large, centralized steam reforming plant, and delivered to refueling stations via liquid hydrogen truck or small scale hydrogen gas pipeline, (2) hydrogen produced at the refueling station via small scale steam reforming of natural gas, (3) hydrogen produced via small scale electrolysis at the refueling station, and (4) hydrogen from low cost chemical industry sources (e.g. excess capacity in refineries which have recently upgraded their hydrogen production capacity, etc.).

  8. WVU Hydrogen Fuel Dispensing Station

    Energy Technology Data Exchange (ETDEWEB)

    Davis, William [West Virginia University Research Corporation, Morgantown, WV (United States)

    2015-09-01

    The scope of this project was changed during the course of the project. Phase I of the project was to construct a site similar to the site at Central West Virginia Regional Airport in Charleston, WV to show that duplication of the site was a feasible method of conducting hydrogen stations. Phase II of the project was necessitated due to a lack of funding that was planned for the development of the station in Morgantown. The US Department of Energy determined that the station in Charleston would be dismantled and moved to Morgantown and reassembled at the Morgantown site. This necessitated storage of the components of the station for almost a year at the NAFTC Headquarters which caused a number of issues with the equipment that will be discussed in later portions of this report. This report will consist of PHASE I and PHASE II with discussions on each of the tasks scheduled for each phase of the project.

  9. Hydrogen in metals

    CSIR Research Space (South Africa)

    Carter, TJ

    2001-04-01

    Full Text Available .J. Cartera,*, L.A. Cornishb aAdvanced Engineering & Testing Services, MATTEK, CSIR, Private Bag X28, Auckland Park 2006, South Africa bSchool of Process and Materials Engineering, University of the Witwatersrand, Private Bag 3, P.O. WITS 2050, South Africa... are contrasted, and an unusual case study of hydrogen embrittlement of an alloy steel is presented. 7 2001 Published by Elsevier Science Ltd. Keywords: Hydrogen; Hydrogen-assisted cracking; Hydrogen damage; Hydrogen embrittlement 1. Introduction Hydrogen suC128...

  10. Hydrogen-related effects in crystalline semiconductors

    International Nuclear Information System (INIS)

    Haller, E.E.

    1988-08-01

    Recent experimental and theoretical information regarding the states of hydrogen in crystalline semiconductors is reviewed. The abundance of results illustrates that hydrogen does not preferentially occupy a few specific lattice sites but that it binds to native defects and impurities, forming a large variety of neutral and electrically active complexes. The study of hydrogen passivated shallow acceptors and donors and of partially passivated multivalent acceptors has yielded information on the electronic and real space structure and on the chemical composition of these complexes. Infrared spectroscopy, ion channeling, hydrogen isotope substitution and electric field drift experiments have shown that both static trigonal complexes as well as centers with tunneling hydrogen exist. Total energy calculations indicate that the charge state of the hydrogen ion which leads to passivation dominates, i.e., H + in p-type and H/sup /minus// in n-type crystals. Recent theoretical calculations indicate that is unlikely for a large fraction of the atomic hydrogen to exist in its neutral state, a result which is consistent with the total absence of any Electron Paramagnetic Resonance (EPR) signal. An alternative explanation for this result is the formation of H 2 . Despite the numerous experimental and theoretical results on hydrogen-related effects in Ge and Si there remains a wealth of interesting physics to be explored, especially in compound and alloy semiconductors. 6 refs., 6 figs

  11. A new type of hydrogen generator-HHEG (high-compressed hydrogen energy generator)

    International Nuclear Information System (INIS)

    Harada, H.; Tojima, K.; Takeda, M.; Nakazawa, T.

    2004-01-01

    'Full text:' We have developed a new type of hydrogen generator named HHEG (High-compressed Hydrogen Energy Generator). HHEG can produce 35 MPa high-compressed hydrogen for fuel cell vehicle without any mechanical compressor. HHEG is a kind of PEM(proton exchange membrane)electrolysis. It was well known that compressed hydrogen could be generated by water electrolysis. However, the conventional electrolysis could not generate 35 MPa or higher pressure that is required for fuel cell vehicle, because electrolysis cell stack is destroyed in such high pressure. In HHEG, the cell stack is put in high-pressure vessel and the pressure difference of oxygen and hydrogen that is generated by the cell stack is always kept at nearly zero by an automatic compensator invented by Mitsubishi Corporation. The cell stack of HHEG is not so special one, but it is not broken under such high pressure, because the automatic compensator always offsets the force acting on the cell stack. Hydrogen for fuel cell vehicle must be produce by no emission energy such as solar and atomic power. These energies are available as electricity. So, water electrolysis is the only way of producing hydrogen fuel. Hydrogen fuel is also 35 MPa high-compressed hydrogen and will become 70 MPa in near future. But conventional mechanical compressor is not useful for such high pressure hydrogen fuel, because of the short lifetime and high power consumption. Construction of hydrogen station network is indispensable in order to come into wide use of fuel cell vehicles. For such network contraction, an on-site type hydrogen generator is required. HHEG can satisfy above these requirements. So we can conclude that HHEG is the only way of realizing the hydrogen economy. (author)

  12. Constrained reaction volume approach for studying chemical kinetics behind reflected shock waves

    KAUST Repository

    Hanson, Ronald K.

    2013-09-01

    We report a constrained-reaction-volume strategy for conducting kinetics experiments behind reflected shock waves, achieved in the present work by staged filling in a shock tube. Using hydrogen-oxygen ignition experiments as an example, we demonstrate that this strategy eliminates the possibility of non-localized (remote) ignition in shock tubes. Furthermore, we show that this same strategy can also effectively eliminate or minimize pressure changes due to combustion heat release, thereby enabling quantitative modeling of the kinetics throughout the combustion event using a simple assumption of specified pressure and enthalpy. We measure temperature and OH radical time-histories during ethylene-oxygen combustion behind reflected shock waves in a constrained reaction volume and verify that the results can be accurately modeled using a detailed mechanism and a specified pressure and enthalpy constraint. © 2013 The Combustion Institute.

  13. Self-constrained inversion of potential fields

    Science.gov (United States)

    Paoletti, V.; Ialongo, S.; Florio, G.; Fedi, M.; Cella, F.

    2013-11-01

    We present a potential-field-constrained inversion procedure based on a priori information derived exclusively from the analysis of the gravity and magnetic data (self-constrained inversion). The procedure is designed to be applied to underdetermined problems and involves scenarios where the source distribution can be assumed to be of simple character. To set up effective constraints, we first estimate through the analysis of the gravity or magnetic field some or all of the following source parameters: the source depth-to-the-top, the structural index, the horizontal position of the source body edges and their dip. The second step is incorporating the information related to these constraints in the objective function as depth and spatial weighting functions. We show, through 2-D and 3-D synthetic and real data examples, that potential field-based constraints, for example, structural index, source boundaries and others, are usually enough to obtain substantial improvement in the density and magnetization models.

  14. Cosmogenic photons strongly constrain UHECR source models

    Directory of Open Access Journals (Sweden)

    van Vliet Arjen

    2017-01-01

    Full Text Available With the newest version of our Monte Carlo code for ultra-high-energy cosmic ray (UHECR propagation, CRPropa 3, the flux of neutrinos and photons due to interactions of UHECRs with extragalactic background light can be predicted. Together with the recently updated data for the isotropic diffuse gamma-ray background (IGRB by Fermi LAT, it is now possible to severely constrain UHECR source models. The evolution of the UHECR sources especially plays an important role in the determination of the expected secondary photon spectrum. Pure proton UHECR models are already strongly constrained, primarily by the highest energy bins of Fermi LAT’s IGRB, as long as their number density is not strongly peaked at recent times.

  15. A constrained supersymmetric left-right model

    Energy Technology Data Exchange (ETDEWEB)

    Hirsch, Martin [AHEP Group, Instituto de Física Corpuscular - C.S.I.C./Universitat de València, Edificio de Institutos de Paterna, Apartado 22085, E-46071 València (Spain); Krauss, Manuel E. [Bethe Center for Theoretical Physics & Physikalisches Institut der Universität Bonn, Nussallee 12, 53115 Bonn (Germany); Institut für Theoretische Physik und Astronomie, Universität Würzburg,Emil-Hilb-Weg 22, 97074 Wuerzburg (Germany); Opferkuch, Toby [Bethe Center for Theoretical Physics & Physikalisches Institut der Universität Bonn, Nussallee 12, 53115 Bonn (Germany); Porod, Werner [Institut für Theoretische Physik und Astronomie, Universität Würzburg,Emil-Hilb-Weg 22, 97074 Wuerzburg (Germany); Staub, Florian [Theory Division, CERN,1211 Geneva 23 (Switzerland)

    2016-03-02

    We present a supersymmetric left-right model which predicts gauge coupling unification close to the string scale and extra vector bosons at the TeV scale. The subtleties in constructing a model which is in agreement with the measured quark masses and mixing for such a low left-right breaking scale are discussed. It is shown that in the constrained version of this model radiative breaking of the gauge symmetries is possible and a SM-like Higgs is obtained. Additional CP-even scalars of a similar mass or even much lighter are possible. The expected mass hierarchies for the supersymmetric states differ clearly from those of the constrained MSSM. In particular, the lightest down-type squark, which is a mixture of the sbottom and extra vector-like states, is always lighter than the stop. We also comment on the model’s capability to explain current anomalies observed at the LHC.

  16. Coding for Two Dimensional Constrained Fields

    DEFF Research Database (Denmark)

    Laursen, Torben Vaarbye

    2006-01-01

    a first order model to model higher order constraints by the use of an alphabet extension. We present an iterative method that based on a set of conditional probabilities can help in choosing the large numbers of parameters of the model in order to obtain a stationary model. Explicit results are given...... for the No Isolated Bits constraint. Finally we present a variation of the encoding scheme of bit-stuffing that is applicable to the class of checkerboard constrained fields. It is possible to calculate the entropy of the coding scheme thus obtaining lower bounds on the entropy of the fields considered. These lower...... bounds are very tight for the Run-Length limited fields. Explicit bounds are given for the diamond constrained field as well....

  17. Communication Schemes with Constrained Reordering of Resources

    DEFF Research Database (Denmark)

    Popovski, Petar; Utkovski, Zoran; Trillingsgaard, Kasper Fløe

    2013-01-01

    This paper introduces a communication model inspired by two practical scenarios. The first scenario is related to the concept of protocol coding, where information is encoded in the actions taken by an existing communication protocol. We investigate strategies for protocol coding via combinatorial...... reordering of the labelled user resources (packets, channels) in an existing, primary system. However, the degrees of freedom of the reordering are constrained by the operation of the primary system. The second scenario is related to communication systems with energy harvesting, where the transmitted signals...... are constrained by the energy that is available through the harvesting process. We have introduced a communication model that covers both scenarios and elicits their key feature, namely the constraints of the primary system or the harvesting process. We have shown how to compute the capacity of the channels...

  18. Q-deformed systems and constrained dynamics

    International Nuclear Information System (INIS)

    Shabanov, S.V.

    1993-01-01

    It is shown that quantum theories of the q-deformed harmonic oscillator and one-dimensional free q-particle (a free particle on the 'quantum' line) can be obtained by the canonical quantization of classical Hamiltonian systems with commutative phase-space variables and a non-trivial symplectic structure. In the framework of this approach, classical dynamics of a particle on the q-line coincides with the one of a free particle with friction. It is argued that q-deformed systems can be treated as ordinary mechanical systems with the second-class constraints. In particular, second-class constrained systems corresponding to the q-oscillator and q-particle are given. A possibility of formulating q-deformed systems via gauge theories (first-class constrained systems) is briefly discussed. (orig.)

  19. Fuel Cell and Hydrogen Technologies Program | Hydrogen and Fuel Cells |

    Science.gov (United States)

    NREL Fuel Cell and Hydrogen Technologies Program Fuel Cell and Hydrogen Technologies Program Through its Fuel Cell and Hydrogen Technologies Program, NREL researches, develops, analyzes, and validates fuel cell and hydrogen production, delivery, and storage technologies for transportation

  20. Dynamics of hydrogen in hydrogenated amorphous silicon

    Indian Academy of Sciences (India)

    is mobile and can easily move through the material). Hydrogen diffuses ... The determination of the relationship of light-enhanced hydrogen motion to ... term is negligible, and using the thermodynamic relation given below f(c) = kBT .... device-applications problematic but the normal state can be recovered by a thermal an-.

  1. Hydrogen Production for Refuelling Applications

    Energy Technology Data Exchange (ETDEWEB)

    Hulteberg, Christian; Aagesen, Diane (Intelligent Energy, Long Beach, CA (United States))

    2009-08-15

    The aim of this work is to support the development of a high-profile demonstration of hydrogen generation technologies in a Swedish context. The overall objective of the demonstration is to deploy a reforming based hydrogen refilling station along the Swedish west coast; intermediate to the Malmoe refuelling station and planned stations in Goeteborg. In this way, the Norwegian hydrogen highway will be extended through the south of Sweden and down into Denmark. The aim of the project's first phase, where this constitutes the final report, was to demonstrate the ability to operate the IE reforming system on the E.On/SGC site-specific fuel. During the project, a preliminary system design has been developed, based on IE's proprietary reformer. The system has been operated at pressure, to ensure a stable operation of the downstream PSA; which has been operated without problems and with the expected hydrogen purity and recovery. The safe operation of the proposed and tested system was first evaluated in a preliminary risk assessment, as well as a full HazOp analysis. A thorough economic modelling has been performed on the viability of owning and operating this kind of hydrogen generation equipment. The evaluation has been performed from an on-site operation of such a unit in a refuelling context. The general conclusion from this modelling is that there are several parameters that influence the potential of an investment in a Hestia hydrogen generator. The sales price of the hydrogen is one of the major drivers of profitability. Another important factor is the throughput of the unit, more important than efficiency and utilization. Varying all of the parameters simultaneously introduce larger variations in the NPV, but 60% of the simulations are in the USD 90 000 to USD 180 000 interval. The chosen intervals for the parameters were: Hydrogen Sales Price (USD 5 - USD 7 per kg); Investment Cost (USD 70 000 - USD 130 000 per unit); Throughput (20 - 30 kg

  2. Epoch of reionization 21 cm forecasting from MCMC-constrained semi-numerical models

    Science.gov (United States)

    Hassan, Sultan; Davé, Romeel; Finlator, Kristian; Santos, Mario G.

    2017-06-01

    The recent low value of Planck Collaboration XLVII integrated optical depth to Thomson scattering suggests that the reionization occurred fairly suddenly, disfavouring extended reionization scenarios. This will have a significant impact on the 21 cm power spectrum. Using a semi-numerical framework, we improve our model from instantaneous to include time-integrated ionization and recombination effects, and find that this leads to more sudden reionization. It also yields larger H II bubbles that lead to an order of magnitude more 21 cm power on large scales, while suppressing the small-scale ionization power. Local fluctuations in the neutral hydrogen density play the dominant role in boosting the 21 cm power spectrum on large scales, while recombinations are subdominant. We use a Monte Carlo Markov chain approach to constrain our model to observations of the star formation rate functions at z = 6, 7, 8 from Bouwens et al., the Planck Collaboration XLVII optical depth measurements and the Becker & Bolton ionizing emissivity data at z ˜ 5. We then use this constrained model to perform 21 cm forecasting for Low Frequency Array, Hydrogen Epoch of Reionization Array and Square Kilometre Array in order to determine how well such data can characterize the sources driving reionization. We find that the Mock 21 cm power spectrum alone can somewhat constrain the halo mass dependence of ionizing sources, the photon escape fraction and ionizing amplitude, but combining the Mock 21 cm data with other current observations enables us to separately constrain all these parameters. Our framework illustrates how the future 21 cm data can play a key role in understanding the sources and topology of reionization as observations improve.

  3. Online constrained model-based reinforcement learning

    CSIR Research Space (South Africa)

    Van Niekerk, B

    2017-08-01

    Full Text Available Constrained Model-based Reinforcement Learning Benjamin van Niekerk School of Computer Science University of the Witwatersrand South Africa Andreas Damianou∗ Amazon.com Cambridge, UK Benjamin Rosman Council for Scientific and Industrial Research, and School... MULTIPLE SHOOTING Using direct multiple shooting (Bock and Plitt, 1984), problem (1) can be transformed into a structured non- linear program (NLP). First, the time horizon [t0, t0 + T ] is partitioned into N equal subintervals [tk, tk+1] for k = 0...

  4. Constraining supergravity models from gluino production

    International Nuclear Information System (INIS)

    Barbieri, R.; Gamberini, G.; Giudice, G.F.; Ridolfi, G.

    1988-01-01

    The branching ratios for gluino decays g tilde → qanti qΧ, g tilde → gΧ into a stable undetected neutralino are computed as functions of the relevant parameters of the underlying supergravity theory. A simple way of constraining supergravity models from gluino production emerges. The effectiveness of hadronic versus e + e - colliders in the search for supersymmetry can be directly compared. (orig.)

  5. Cosmicflows Constrained Local UniversE Simulations

    Science.gov (United States)

    Sorce, Jenny G.; Gottlöber, Stefan; Yepes, Gustavo; Hoffman, Yehuda; Courtois, Helene M.; Steinmetz, Matthias; Tully, R. Brent; Pomarède, Daniel; Carlesi, Edoardo

    2016-01-01

    This paper combines observational data sets and cosmological simulations to generate realistic numerical replicas of the nearby Universe. The latter are excellent laboratories for studies of the non-linear process of structure formation in our neighbourhood. With measurements of radial peculiar velocities in the local Universe (cosmicflows-2) and a newly developed technique, we produce Constrained Local UniversE Simulations (CLUES). To assess the quality of these constrained simulations, we compare them with random simulations as well as with local observations. The cosmic variance, defined as the mean one-sigma scatter of cell-to-cell comparison between two fields, is significantly smaller for the constrained simulations than for the random simulations. Within the inner part of the box where most of the constraints are, the scatter is smaller by a factor of 2 to 3 on a 5 h-1 Mpc scale with respect to that found for random simulations. This one-sigma scatter obtained when comparing the simulated and the observation-reconstructed velocity fields is only 104 ± 4 km s-1, I.e. the linear theory threshold. These two results demonstrate that these simulations are in agreement with each other and with the observations of our neighbourhood. For the first time, simulations constrained with observational radial peculiar velocities resemble the local Universe up to a distance of 150 h-1 Mpc on a scale of a few tens of megaparsecs. When focusing on the inner part of the box, the resemblance with our cosmic neighbourhood extends to a few megaparsecs (<5 h-1 Mpc). The simulations provide a proper large-scale environment for studies of the formation of nearby objects.

  6. Dynamic Convex Duality in Constrained Utility Maximization

    OpenAIRE

    Li, Yusong; Zheng, Harry

    2016-01-01

    In this paper, we study a constrained utility maximization problem following the convex duality approach. After formulating the primal and dual problems, we construct the necessary and sufficient conditions for both the primal and dual problems in terms of FBSDEs plus additional conditions. Such formulation then allows us to explicitly characterize the primal optimal control as a function of the adjoint process coming from the dual FBSDEs in a dynamic fashion and vice versa. Moreover, we also...

  7. Statistical mechanics of budget-constrained auctions

    OpenAIRE

    Altarelli, F.; Braunstein, A.; Realpe-Gomez, J.; Zecchina, R.

    2009-01-01

    Finding the optimal assignment in budget-constrained auctions is a combinatorial optimization problem with many important applications, a notable example being the sale of advertisement space by search engines (in this context the problem is often referred to as the off-line AdWords problem). Based on the cavity method of statistical mechanics, we introduce a message passing algorithm that is capable of solving efficiently random instances of the problem extracted from a natural distribution,...

  8. Constraining neutron star matter with Quantum Chromodynamics

    CERN Document Server

    Kurkela, Aleksi; Schaffner-Bielich, Jurgen; Vuorinen, Aleksi

    2014-01-01

    In recent years, there have been several successful attempts to constrain the equation of state of neutron star matter using input from low-energy nuclear physics and observational data. We demonstrate that significant further restrictions can be placed by additionally requiring the pressure to approach that of deconfined quark matter at high densities. Remarkably, the new constraints turn out to be highly insensitive to the amount --- or even presence --- of quark matter inside the stars.

  9. Hydrogen economy and nuclear energy

    International Nuclear Information System (INIS)

    Knapp, V.

    2004-01-01

    Global energy outlooks based on present trends, such as WETO study, give little optimism about fulfilling Kyoto commitments in controlling CO2 emissions and avoiding unwanted climate consequences. Whilst the problem of radioactive waste has a prominence in public, in spite of already adequate technical solutions of safe storage for future hundreds and thousands of years, there s generally much less concern with influence of fossil fuels on global climate. In addition to electricity production, process heat and transportation are approximately equal contributors to CO2 emission. Fossil fuels in transportation present also a local pollution problem in congested regions. Backed by extensive R and D, hydrogen economy is seen as the solution, however, often without much thought where from the hydrogen in required very large quantities may come. With welcome contributions from alternative sources, nuclear energy is the only source of energy capable of producing hydrogen in very large amounts, without parallel production of CO2. Future high temperature reactors could do this most efficiently. In view of the fact that nuclear weapon proliferation is not under control, extrapolation from the present level of nuclear power to the future level required by serious attempts to reduce global CO2 emission is a matter of justified concern. Finding the sites for many hundreds of new reactors would, alone, be a formidable problem in developed regions with high population density. What is generally less well understood and not validated is that the production of nuclear hydrogen allows the required large increases of nuclear power without the accompanied increase of proliferation risks. Unlike electricity, hydrogen can be economically shipped or transported by pipelines to places very far from the place of production. Thus, nuclear production of hydrogen can be located and concentrated at few remote, controllable sites, far from the population centers and consumption regions. At such

  10. Constraining the mass of the Local Group

    Science.gov (United States)

    Carlesi, Edoardo; Hoffman, Yehuda; Sorce, Jenny G.; Gottlöber, Stefan

    2017-03-01

    The mass of the Local Group (LG) is a crucial parameter for galaxy formation theories. However, its observational determination is challenging - its mass budget is dominated by dark matter that cannot be directly observed. To meet this end, the posterior distributions of the LG and its massive constituents have been constructed by means of constrained and random cosmological simulations. Two priors are assumed - the Λ cold dark matter model that is used to set up the simulations, and an LG model that encodes the observational knowledge of the LG and is used to select LG-like objects from the simulations. The constrained simulations are designed to reproduce the local cosmography as it is imprinted on to the Cosmicflows-2 data base of velocities. Several prescriptions are used to define the LG model, focusing in particular on different recent estimates of the tangential velocity of M31. It is found that (a) different vtan choices affect the peak mass values up to a factor of 2, and change mass ratios of MM31 to MMW by up to 20 per cent; (b) constrained simulations yield more sharply peaked posterior distributions compared with the random ones; (c) LG mass estimates are found to be smaller than those found using the timing argument; (d) preferred Milky Way masses lie in the range of (0.6-0.8) × 1012 M⊙; whereas (e) MM31 is found to vary between (1.0-2.0) × 1012 M⊙, with a strong dependence on the vtan values used.

  11. Handbook of hydrogen energy

    CERN Document Server

    Sherif, SA; Stefanakos, EK; Steinfeld, Aldo

    2014-01-01

    ""This book provides an excellent overview of the hydrogen economy and a thorough and comprehensive presentation of hydrogen production and storage methods.""-Scott E. Grasman, Rochester Institute of Technology, New York, USA

  12. Hydrogen production by Cyanobacteria

    Directory of Open Access Journals (Sweden)

    Chaudhuri Surabhi

    2005-12-01

    Full Text Available Abstract The limited fossil fuel prompts the prospecting of various unconventional energy sources to take over the traditional fossil fuel energy source. In this respect the use of hydrogen gas is an attractive alternate source. Attributed by its numerous advantages including those of environmentally clean, efficiency and renew ability, hydrogen gas is considered to be one of the most desired alternate. Cyanobacteria are highly promising microorganism for hydrogen production. In comparison to the traditional ways of hydrogen production (chemical, photoelectrical, Cyanobacterial hydrogen production is commercially viable. This review highlights the basic biology of cynobacterial hydrogen production, strains involved, large-scale hydrogen production and its future prospects. While integrating the existing knowledge and technology, much future improvement and progress is to be done before hydrogen is accepted as a commercial primary energy source.

  13. Center for Hydrogen Storage.

    Science.gov (United States)

    2013-06-01

    The main goals of this project were to (1) Establish a Center for Hydrogen Storage Research at Delaware State University for the preparation and characterization of selected complex metal hydrides and the determination their suitability for hydrogen ...

  14. Improved brain MRI indices in the acute brain stem infarct sites treated with hydroxyl radical scavengers, Edaravone and hydrogen, as compared to Edaravone alone. A non-controlled study

    Directory of Open Access Journals (Sweden)

    Ono Hirohisa

    2011-06-01

    Full Text Available Abstract Background In acute stage of cerebral infarction, MRI indices (rDWI & rADC deteriorate during the first 3-7 days after the ictus and then gradually normalize in approximately 10 days (pseudonormalization time, although the tissue is already infarcted. Since effective treatments improve these indices significantly and in less than the natural pseudonormalization time, a combined analysis of these changes provides an opportunity for objective evaluation on the effectiveness of various treatments for cerebral infarction. Hydroxyl radicals are highly destructive to the tissue and aggravate cerebral infarction. We treated brainstem infarction patients in acute stage with hydroxyl radical scavengers (Edaravone and hydrogen by intravenous administration and evaluated the effects of the treatment by a serial observation and analysis of these MRI indices. The effects of the treatment were evaluated and compared in two groups, an Edaravone alone group and a combined group with Edaravone and hydrogen, in order to assess beneficial effects of addition of hydrogen. Methods The patients were divided in Edaravone only group (E group. 26 patients and combined treatment group with Edaravone and hydrogen enriched saline (EH group. 8 patients. The extent of the initial hump of rDWI, the initial dip of rADC and pseudo-normalization time were determined in each patient serially and averages of these data were compared in these two groups and also with the natural course in the literatures. Results The initial hump of rDWI reached 2.0 in the E group which was better than 2.5 of the natural course but was not as good as 1.5 of the EH group. The initial dip of rADC was 0.6 in the E group which was close to the natural course but worse than 0.8 of the EH group. Pseudonormalization time of rDWI and rADC was 9 days only in EH group but longer in other groups. Addition of hydrogen caused no side effects. Conclusions Administration of hydroxyl radical scavengers in

  15. Nuclear electrolytic hydrogen

    International Nuclear Information System (INIS)

    Barnstaple, A.G.; Petrella, A.J.

    1982-05-01

    An extensive study of hydrogen supply has recently been carried out by Ontario Hydro which indicates that electrolytic hydrogen produced from nuclear electricity could offer the lowest cost option for any future large scale hydrogen supply in the Province of Ontario, Canada. This paper provides a synopsis of the Ontario Hydro study, a brief overview of the economic factors supporting the study conclusion and discussion of a number of issues concerning the supply of electrolytic hydrogen by electric power utilities

  16. Hydrogen Technologies Safety Guide

    Energy Technology Data Exchange (ETDEWEB)

    Rivkin, C. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Burgess, R. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Buttner, W. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2015-01-01

    The purpose of this guide is to provide basic background information on hydrogen technologies. It is intended to provide project developers, code officials, and other interested parties the background information to be able to put hydrogen safety in context. For example, code officials reviewing permit applications for hydrogen projects will get an understanding of the industrial history of hydrogen, basic safety concerns, and safety requirements.

  17. Hydrogen-metal systems

    International Nuclear Information System (INIS)

    Wenzl, H.; Springer, T.

    1976-01-01

    A survey is given on the alloys of metal crystals with hydrogen. The system niobium-hydrogen and its properties are especially dealt with: diffusion and heat of solution of hydrogen in the host crystal, phase diagram, coherent and incoherent phase separation, application of metal-hydrogen systems in technology. Furthermore, examples from research work in IFF (Institut fuer Festkoerperforschung) of the Nuclear Research Plant, Juelich, in the field of metal-H systems are given in summary form. (GSC) [de

  18. Hydrogenation of passivated contacts

    Energy Technology Data Exchange (ETDEWEB)

    Nemeth, William; Yuan, Hao-Chih; LaSalvia, Vincenzo; Stradins, Pauls; Page, Matthew R.

    2018-03-06

    Methods of hydrogenation of passivated contacts using materials having hydrogen impurities are provided. An example method includes applying, to a passivated contact, a layer of a material, the material containing hydrogen impurities. The method further includes subsequently annealing the material and subsequently removing the material from the passivated contact.

  19. Hydrogen separation process

    Science.gov (United States)

    Mundschau, Michael [Longmont, CO; Xie, Xiaobing [Foster City, CA; Evenson, IV, Carl; Grimmer, Paul [Longmont, CO; Wright, Harold [Longmont, CO

    2011-05-24

    A method for separating a hydrogen-rich product stream from a feed stream comprising hydrogen and at least one carbon-containing gas, comprising feeding the feed stream, at an inlet pressure greater than atmospheric pressure and a temperature greater than 200.degree. C., to a hydrogen separation membrane system comprising a membrane that is selectively permeable to hydrogen, and producing a hydrogen-rich permeate product stream on the permeate side of the membrane and a carbon dioxide-rich product raffinate stream on the raffinate side of the membrane. A method for separating a hydrogen-rich product stream from a feed stream comprising hydrogen and at least one carbon-containing gas, comprising feeding the feed stream, at an inlet pressure greater than atmospheric pressure and a temperature greater than 200.degree. C., to an integrated water gas shift/hydrogen separation membrane system wherein the hydrogen separation membrane system comprises a membrane that is selectively permeable to hydrogen, and producing a hydrogen-rich permeate product stream on the permeate side of the membrane and a carbon dioxide-rich product raffinate stream on the raffinate side of the membrane. A method for pretreating a membrane, comprising: heating the membrane to a desired operating temperature and desired feed pressure in a flow of inert gas for a sufficient time to cause the membrane to mechanically deform; decreasing the feed pressure to approximately ambient pressure; and optionally, flowing an oxidizing agent across the membrane before, during, or after deformation of the membrane. A method of supporting a hydrogen separation membrane system comprising selecting a hydrogen separation membrane system comprising one or more catalyst outer layers deposited on a hydrogen transport membrane layer and sealing the hydrogen separation membrane system to a porous support.

  20. Fabrication of (PPC/NCC)/PVA composites with inner-outer double constrained structure and improved glass transition temperature.

    Science.gov (United States)

    Cui, Shaoying; Li, Li; Wang, Qi

    2018-07-01

    Improving glass transition temperature (T g ) and mechanical property of the environment-friendly poly(propylene carbonate) via intermacromolecular complexation through hydrogen bonding is attractive and of great importance. A novel and effective strategy to prepare (polypropylene carbonate/nanocrystalline cellulose)/polyvinyl alcohol ((PPC/NCC)/PVA) composites with inner-outer double constrained structure was reported in this work. Outside the PPC phase, PVA, as a strong skeleton at microscale, could constrain the movement of PPC molecular chains by forming hydrogen bonding with PPC at the interface of PPC and PVA phases; inside the PPC phase, the rod-like NCC could restrain the flexible molecular chains of PPC at nanoscale by forming multi-hydrogen bonding with PPC. Under the synergistic effect of this novel inner-outer double constrained structure, T g , mechanical properties and thermal stability of (PPC/NCC)/PVA composite were significantly increased, e.g. T g of the composite researched the maximum value of 49.6 °C, respectively 15.6 °C, 5.7 °C and 4.2 °C higher than that of PPC, PPC/NCC and PPC/PVA composite. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. Agglomeration Versus Localization Of Hydrogen In BCC Fe Vacancies

    International Nuclear Information System (INIS)

    Simonetti, S.; Juan, A.; Brizuela, G.; Simonetti, S.

    2006-01-01

    Severe embrittlement can be produced in many metals by small amounts of hydrogen. The interactions of hydrogen with lattice imperfections are important and often dominant in determining the influence of this impurity on the properties of solids. The interaction between four-hydrogen atoms and a BCC Fe structure having a vacancy has been studied using a cluster model and a semiempirical method. For a study of sequential absorption, the hydrogen atoms were positioned in their energy minima configurations, near to the tetrahedral sites neighbouring the vacancy. VH 2 and VH 3 complexes are energetically the most stables in BCC Fe. The studies about the stability of the hydrogen agglomeration gave as a result that the accumulation is unfavourable in complex vacancy-hydrogen with more than three atoms of hydrogen. (authors)

  2. Comparative study of hydrogen storage on metal doped mesoporous materials

    Science.gov (United States)

    Carraro, P. M.; Sapag, K.; Oliva, M. I.; Eimer, G. A.

    2018-06-01

    The hydrogen adsorption capacity of mesoporous materials MCM-41 modified with Co, Fe, Ti, Mg and Ni at 77 K and 10 bar was investigated. Various techniques including XRD, N2 adsorption and DRUV-vis were employed for the materials characterization. The results showed that a low nickel loading on MCM-41 support promoted the presence of hydrogen-favorable sites, increasing the hydrogen storage capacity.

  3. Configuration and mobility of hydrogen implanted in aluminium

    International Nuclear Information System (INIS)

    Bugeat, J.P.; Chami, A.C.; Ligeon, E.

    1976-01-01

    Localization methods through channeling and nuclear reaction analysis using low energy ion beam were applied to the study of deuterium and hydrogen implanted in aluminium single crystals. It was shown that implanted hydrogen occupies a tetrahedral site in the lattice as far as the implantation temperature is lower than 175K. This fact is interpreted by considering an interaction between hydrogen and monovacancies created during the implantation [fr

  4. Hydrogen transport in 4130 steel

    International Nuclear Information System (INIS)

    Kass, W.J.

    1976-01-01

    The solubility data indicate that under glow discharge conditions hydrogen entering the lattice is already dissociated in the gas phase. Since subsequent diffusion is expected to be no longer limited by a surface process, the remaining anomalous low temperature diffusion behavior may be related to a bulk process such as trapping. The normal permeation behavior is consistent with a trapping mechanism since the steady state permeation rate is not affected by trapping. Consequently, in normal permeation measurements it appears that both perturbations to simple diffusion occur, the hydrogen dissociation is influenced by a slow surface step and the bulk diffusion is perturbed by trapping sites. Promising future work should be the analysis of the transient diffusion behavior under glow discharge conditions via the model of McNabb and Foster to determine if meaningful trapping parameters may be elicited

  5. Solar Hydrogen Reaching Maturity

    Directory of Open Access Journals (Sweden)

    Rongé Jan

    2015-09-01

    Full Text Available Increasingly vast research efforts are devoted to the development of materials and processes for solar hydrogen production by light-driven dissociation of water into oxygen and hydrogen. Storage of solar energy in chemical bonds resolves the issues associated with the intermittent nature of sunlight, by decoupling energy generation and consumption. This paper investigates recent advances and prospects in solar hydrogen processes that are reaching market readiness. Future energy scenarios involving solar hydrogen are proposed and a case is made for systems producing hydrogen from water vapor present in air, supported by advanced modeling.

  6. Canada's hydrogen energy sector

    International Nuclear Information System (INIS)

    Kimmel, T.B.

    2009-01-01

    Canada produces the most hydrogen per capita of any Organization of Economic Cooperation and Development (OECD) country. The majority of this hydrogen is produced by steam methane reforming for industrial use (predominantly oil upgrading and fertilizer production). Canada also has a world leading hydrogen and fuel cell sector. This sector is seeking new methods for making hydrogen for its future energy needs. The paper will discuss Canada's hydrogen and fuel cell sector in the context of its capabilities, its demonstration and commercialization activities and its stature on the world stage. (author)

  7. Applications of Nuclear Energy to Oil Sands and Hydrogen Production

    International Nuclear Information System (INIS)

    Duffey, R.B.; Miller, A.; Kuran, S.

    2011-01-01

    Many novel and needed applications of nuclear energy arise in today's energy-hungry, economically challenged world, and in solving tomorrow's search for a globally carbon-constrained and sustainable energy supply. Not only can nuclear power produce low cost electricity, it can provide co-generation of process heat, desalinated water, and hydrogen with negligible greenhouse gas emissions. In each of these new applications, nuclear energy is competing against, or displacing conventional and established use of natural gas or coal in thermal power plants and boilers. Therefore, there must be a compelling case, in terms of supply certainty, stability, safety, security, and acceptability. In addition, a synergistic relation must exist or be created with the existing power and energy markets, the use of windpower, and the needs for low-cost supply with negligible greenhouse gas emissions and carbon 'footprint'. The development of Canada's oil sands resource depends on a substantial energy input for extraction and upgrading. So far, this input has been supplied by natural gas, a resource that (a) is a premium fuel; (b) has constrained availability; and (c) produces significant CO 2 emissions. For the oil sands extraction process, natural gas is the current energy source used to generate the steam for in-situ heating, the power to drive the separation equipment, and the hydrogen for varying degrees of upgrading before piping. Nothwithstanding the current imbalance between supply and demand for gas within North America, the very demand of the oil sands for prodigious amounts of natural gas has itself the potential to force higher prices and create supply constraints for natural gas. Rooted in the energy equivalence of oil and gas, there is a long-established link between American gas prices whereby one bbl of oil is worth 7 GJ of natural gas. Temporary supply/demand imbalances apart, only cheap oil can maintain cheap gas. Only the improbability of cheap oil will maintain low

  8. Cascading Constrained 2-D Arrays using Periodic Merging Arrays

    DEFF Research Database (Denmark)

    Forchhammer, Søren; Laursen, Torben Vaarby

    2003-01-01

    We consider a method for designing 2-D constrained codes by cascading finite width arrays using predefined finite width periodic merging arrays. This provides a constructive lower bound on the capacity of the 2-D constrained code. Examples include symmetric RLL and density constrained codes...

  9. Operator approach to solutions of the constrained BKP hierarchy

    International Nuclear Information System (INIS)

    Shen, Hsin-Fu; Lee, Niann-Chern; Tu, Ming-Hsien

    2011-01-01

    The operator formalism to the vector k-constrained BKP hierarchy is presented. We solve the Hirota bilinear equations of the vector k-constrained BKP hierarchy via the method of neutral free fermion. In particular, by choosing suitable group element of O(∞), we construct rational and soliton solutions of the vector k-constrained BKP hierarchy.

  10. The Importance of Mars Samples in Constraining the Geological and Geophysical Processes on Mars and the Nature of its Crust, Mantle, and Core

    Science.gov (United States)

    iMOST Team; Herd, C. D. K.; Ammannito, E.; Anand, M.; Debaille, V.; Hallis, L. J.; McCubbin, F. M.; Schmitz, N.; Usui, T.; Weiss, B. P.; Altieri, F.; Amelin, Y.; Beaty, D. W.; Benning, L. G.; Bishop, J. L.; Borg, L. E.; Boucher, D.; Brucato, J. R.; Busemann, H.; Campbell, K. A.; Carrier, B. L.; Czaja, A. D.; Des Marais, D. J.; Dixon, M.; Ehlmann, B. L.; Farmer, J. D.; Fernandez-Remolar, D. C.; Fogarty, J.; Glavin, D. P.; Goreva, Y. S.; Grady, M. M.; Harrington, A. D.; Hausrath, E. M.; Horgan, B.; Humayun, M.; Kleine, T.; Kleinhenz, J.; Mangold, N.; Mackelprang, R.; Mayhew, L. E.; McCoy, J. T.; McLennan, S. M.; McSween, H. Y.; Moser, D. E.; Moynier, F.; Mustard, J. F.; Niles, P. B.; Ori, G. G.; Raulin, F.; Rettberg, P.; Rucker, M. A.; Sefton-Nash, E.; Sephton, M. A.; Shaheen, R.; Shuster, D. L.; Siljestrom, S.; Smith, C. L.; Spry, J. A.; Steele, A.; Swindle, T. D.; ten Kate, I. L.; Tosca, N. J.; Van Kranendonk, M. J.; Wadhwa, M.; Werner, S. C.; Westall, F.; Wheeler, R. M.; Zipfel, J.; Zorzano, M. P.

    2018-04-01

    We present the main sample types from any potential Mars Sample Return landing site that would be required to constrain the geological and geophysical processes on Mars, including the origin and nature of its crust, mantle, and core.

  11. Hydrogen energy assessment

    Energy Technology Data Exchange (ETDEWEB)

    Salzano, F J; Braun, C [eds.

    1977-09-01

    The purpose of this assessment is to define the near term and long term prospects for the use of hydrogen as an energy delivery medium. Possible applications of hydrogen are defined along with the associated technologies required for implementation. A major focus in the near term is on industrial uses of hydrogen for special applications. The major source of hydrogen in the near term is expected to be from coal, with hydrogen from electric sources supplying a smaller fraction. A number of potential applications for hydrogen in the long term are identified and the level of demand estimated. The results of a cost benefit study for R and D work on coal gasification to hydrogen and electrolytic production of hydrogen are presented in order to aid in defining approximate levels of R and D funding. A considerable amount of data is presented on the cost of producing hydrogen from various energy resources. A key conclusion of the study is that in time hydrogen is likely to play a role in the energy system; however, hydrogen is not yet competitive for most applications when compared to the cost of energy from petroleum and natural gas.

  12. Hydrogen energy for beginners

    CERN Document Server

    2013-01-01

    This book highlights the outstanding role of hydrogen in energy processes, where it is the most functional element due to its unique peculiarities that are highlighted and emphasized in the book. The first half of the book covers the great natural hydrogen processes in biology, chemistry, and physics, showing that hydrogen is a trend that can unite all natural sciences. The second half of the book is devoted to the technological hydrogen processes that are under research and development with the aim to create the infrastructure for hydrogen energetics. The book describes the main features of hydrogen that make it inalienable player in processes such as fusion, photosynthesis, and metabolism. It also covers the methods of hydrogen production and storage, highlighting at the same time the exclusive importance of nanotechnologies in those processes.

  13. Hydrogen peroxide safety issues

    International Nuclear Information System (INIS)

    Conner, W.V.

    1993-01-01

    A literature survey was conducted to review the safety issues involved in handling hydrogen peroxide solutions. Most of the information found in the literature is not directly applicable to conditions at the Rocky Flats Plant, but one report describes experimental work conducted previously at Rocky Flats to determine decomposition reaction-rate constants for hydrogen peroxide solutions. Data from this report were used to calculate decomposition half-life times for hydrogen peroxide in solutions containing several decomposition catalysts. The information developed from this survey indicates that hydrogen peroxide will undergo both homogeneous and heterogeneous decomposition. The rate of decomposition is affected by temperature and the presence of catalytic agents. Decomposition of hydrogen peroxide is catalyzed by alkalies, strong acids, platinum group and transition metals, and dissolved salts of transition metals. Depending upon conditions, the consequence of a hydrogen peroxide decomposition can range from slow evolution of oxygen gas to a vapor, phase detonation of hydrogen peroxide vapors

  14. Hydrogen and its challenges

    International Nuclear Information System (INIS)

    Schal, M.

    2008-01-01

    The future of hydrogen as a universal fuel is in jeopardy unless we are able to produce it through an environment-friendly way and at a competitive cost. Today almost all the hydrogen used in the world is produced by steam reforming of natural gas. This process releases 8 tonnes of CO 2 per tonne of hydrogen produced. Other means of producing hydrogen are the hydrolysis, the very high temperature hydrolysis, and the direct chemical dissociation of water, these processes are greener than steam reforming but less efficient. About one hundred buses in the world operate on fuel cells fed by hydrogen, but it appears that the first industrial use of hydrogen at great scale will be for the local generation of electricity. Globally the annual budget for research concerning hydrogen is 4.4 milliard (10 9 ) euros worldwide. (A.C.)

  15. Optimizing the hydrogen storage in boron nitride nanotubes by defect engineering

    Energy Technology Data Exchange (ETDEWEB)

    Oezdogan, Kemal; Berber, Savas [Physics Department, Gebze Institute of Technology, Cayirova Kampusu, Gebze, 41400 Kocaeli (Turkey)

    2009-06-15

    We use ab initio density functional theory calculations to study the interaction of hydrogen with vacancies in boron nitride nanotubes to optimize the hydrogen storage capacity through defect engineering. The vacancies reconstruct by forming B-B and N-N bonds across the defect site, which are not as favorable as heteronuclear B-N bonds. Our total energy and structure optimization results indicate that the hydrogen cleaves these reconstructing bonds to form more stable atomic structures. The hydrogenated defects offer smaller charge densities that allow hydrogen molecule to pass through the nanotube wall for storing hydrogen inside the nanotubes. Our optimum reaction pathway search revealed that hydrogen molecules could indeed go through a hydrogenated defect site with relatively small energy barriers compared to the pristine nanotube wall. The calculated activation energies for different diameters suggest a preferential diameter range for optimum hydrogen storage in defective boron nitride nanotubes. (author)

  16. Feature and Pose Constrained Visual Aided Inertial Navigation for Computationally Constrained Aerial Vehicles

    Science.gov (United States)

    Williams, Brian; Hudson, Nicolas; Tweddle, Brent; Brockers, Roland; Matthies, Larry

    2011-01-01

    A Feature and Pose Constrained Extended Kalman Filter (FPC-EKF) is developed for highly dynamic computationally constrained micro aerial vehicles. Vehicle localization is achieved using only a low performance inertial measurement unit and a single camera. The FPC-EKF framework augments the vehicle's state with both previous vehicle poses and critical environmental features, including vertical edges. This filter framework efficiently incorporates measurements from hundreds of opportunistic visual features to constrain the motion estimate, while allowing navigating and sustained tracking with respect to a few persistent features. In addition, vertical features in the environment are opportunistically used to provide global attitude references. Accurate pose estimation is demonstrated on a sequence including fast traversing, where visual features enter and exit the field-of-view quickly, as well as hover and ingress maneuvers where drift free navigation is achieved with respect to the environment.

  17. Incomplete Dirac reduction of constrained Hamiltonian systems

    Energy Technology Data Exchange (ETDEWEB)

    Chandre, C., E-mail: chandre@cpt.univ-mrs.fr

    2015-10-15

    First-class constraints constitute a potential obstacle to the computation of a Poisson bracket in Dirac’s theory of constrained Hamiltonian systems. Using the pseudoinverse instead of the inverse of the matrix defined by the Poisson brackets between the constraints, we show that a Dirac–Poisson bracket can be constructed, even if it corresponds to an incomplete reduction of the original Hamiltonian system. The uniqueness of Dirac brackets is discussed. The relevance of this procedure for infinite dimensional Hamiltonian systems is exemplified.

  18. Capturing Hotspots For Constrained Indoor Movement

    DEFF Research Database (Denmark)

    Ahmed, Tanvir; Pedersen, Torben Bach; Lu, Hua

    2013-01-01

    Finding the hotspots in large indoor spaces is very important for getting overloaded locations, security, crowd management, indoor navigation and guidance. The tracking data coming from indoor tracking are huge in volume and not readily available for finding hotspots. This paper presents a graph......-based model for constrained indoor movement that can map the tracking records into mapping records which represent the entry and exit times of an object in a particular location. Then it discusses the hotspots extraction technique from the mapping records....

  19. Quantization of soluble classical constrained systems

    International Nuclear Information System (INIS)

    Belhadi, Z.; Menas, F.; Bérard, A.; Mohrbach, H.

    2014-01-01

    The derivation of the brackets among coordinates and momenta for classical constrained systems is a necessary step toward their quantization. Here we present a new approach for the determination of the classical brackets which does neither require Dirac’s formalism nor the symplectic method of Faddeev and Jackiw. This approach is based on the computation of the brackets between the constants of integration of the exact solutions of the equations of motion. From them all brackets of the dynamical variables of the system can be deduced in a straightforward way

  20. Quantization of soluble classical constrained systems

    Energy Technology Data Exchange (ETDEWEB)

    Belhadi, Z. [Laboratoire de physique et chimie quantique, Faculté des sciences, Université Mouloud Mammeri, BP 17, 15000 Tizi Ouzou (Algeria); Laboratoire de physique théorique, Faculté des sciences exactes, Université de Bejaia, 06000 Bejaia (Algeria); Menas, F. [Laboratoire de physique et chimie quantique, Faculté des sciences, Université Mouloud Mammeri, BP 17, 15000 Tizi Ouzou (Algeria); Ecole Nationale Préparatoire aux Etudes d’ingéniorat, Laboratoire de physique, RN 5 Rouiba, Alger (Algeria); Bérard, A. [Equipe BioPhysStat, Laboratoire LCP-A2MC, ICPMB, IF CNRS No 2843, Université de Lorraine, 1 Bd Arago, 57078 Metz Cedex (France); Mohrbach, H., E-mail: herve.mohrbach@univ-lorraine.fr [Equipe BioPhysStat, Laboratoire LCP-A2MC, ICPMB, IF CNRS No 2843, Université de Lorraine, 1 Bd Arago, 57078 Metz Cedex (France)

    2014-12-15

    The derivation of the brackets among coordinates and momenta for classical constrained systems is a necessary step toward their quantization. Here we present a new approach for the determination of the classical brackets which does neither require Dirac’s formalism nor the symplectic method of Faddeev and Jackiw. This approach is based on the computation of the brackets between the constants of integration of the exact solutions of the equations of motion. From them all brackets of the dynamical variables of the system can be deduced in a straightforward way.

  1. Constraining Lipid Biomarker Paleoclimate Proxies in a Small Arctic Watershed

    Science.gov (United States)

    Dion-Kirschner, H.; McFarlin, J. M.; Axford, Y.; Osburn, M. R.

    2017-12-01

    Arctic amplification of climate change renders high-latitude environments unusually sensitive to changes in climatic conditions (Serreze and Barry, 2011). Lipid biomarkers, and their hydrogen and carbon isotopic compositions, can yield valuable paleoclimatic and paleoecological information. However, many variables affect the production and preservation of lipids and their constituent isotopes, including precipitation, plant growth conditions, biosynthesis mechanisms, and sediment depositional processes (Sachse et al., 2012). These variables are particularly poorly constrained for high-latitude environments, where trees are sparse or not present, and plants grow under continuous summer light and cool temperatures during a short growing season. Here we present a source-to-sink study of a single watershed from the Kangerlussuaq region of southwest Greenland. Our analytes from in and around `Little Sugarloaf Lake' (LSL) include terrestrial and aquatic plants, plankton, modern lake water, surface sediments, and a sediment core. This diverse sample set allows us to fulfill three goals: 1) We evaluate the production of lipids and isotopic signatures in the modern watershed in comparison to modern climate. Our data exhibit genus-level trends in leaf wax production and isotopic composition, and help clarify the difference between terrestrial and aquatic signals. 2) We evaluate the surface sediment of LSL to determine how lipid biomarkers from the watershed are incorporated into sediments. We constrain the relative contributions of terrestrial plants, aquatic plants, and other aquatic organisms to the sediment in this watershed. 3) We apply this modern source-to-sink calibration to the analysis of a 65 cm sediment core record. Our core is organic-rich, and relatively high deposition rates allow us to reconstruct paleoenvironmental changes with high resolution. Our work will help determine the veracity of these common paleoclimate proxies, specifically for research in

  2. Hydrogen as indicator for redox conditions and dechlorination

    NARCIS (Netherlands)

    Meer, J. ter; Gerritse, J.; Mauro, C. di; Harkes, M.P.; Rijnaarts, H.H.M.

    2000-01-01

    The use of intrinsic degradation processes (natural attenuation) is becoming the basis for the restoration of many contaminated sites. Within this context, measuring concentrations of hydrogen in groundwater is important in two ways. Firstly, the hydrogen concentration can be used to characterize

  3. Hydrogen - From hydrogen to energy production

    International Nuclear Information System (INIS)

    Klotz, Gregory

    2005-01-01

    More than a century ago, Jules Verne wrote in 'The Mysterious Island' that water would one day be employed as fuel: 'Hydrogen and oxygen, which constitute it, used singly or together, will furnish an inexhaustible source of heat and light'. Today, the 'water motor' is not entirely the dream of a writer. Fiction is about to become fact thanks to hydrogen, which can be produced from water and when burned in air itself produces water. Hydrogen is now at the heart of international research. So why do we have such great expectations of hydrogen? 'Hydrogen as an energy system is now a major challenge, both scientifically and from an environmental and economic point of view'. Dominated as it is by fossil fuels (oil, gas and coal), our current energy system has left a dual threat hovering over our environment, exposing the planet to the exhaustion of its natural reserves and contributing to the greenhouse effect. If we want sustainable development for future generations, it is becoming necessary to diversify our methods of producing energy. Hydrogen is not, of course, a source of energy, because first it has to be produced. But it has the twofold advantage of being both inexhaustible and non-polluting. So in the future, it should have a very important role to play. (author)

  4. Hydrogen Filling Station

    Energy Technology Data Exchange (ETDEWEB)

    Boehm, Robert F; Sabacky, Bruce; Anderson II, Everett B; Haberman, David; Al-Hassin, Mowafak; He, Xiaoming; Morriseau, Brian

    2010-02-24

    Hydrogen is an environmentally attractive transportation fuel that has the potential to displace fossil fuels. The Freedom CAR and Freedom FUEL initiatives emphasize the importance of hydrogen as a future transportation fuel. Presently, Las Vegas has one hydrogen fueling station powered by natural gas. However, the use of traditional sources of energy to produce hydrogen does not maximize the benefit. The hydrogen fueling station developed under this grant used electrolysis units and solar energy to produce hydrogen fuel. Water and electricity are furnished to the unit and the output is hydrogen and oxygen. Three vehicles were converted to utilize the hydrogen produced at the station. The vehicles were all equipped with different types of technologies. The vehicles were used in the day-to-day operation of the Las Vegas Valley Water District and monitoring was performed on efficiency, reliability and maintenance requirements. The research and demonstration utilized for the reconfiguration of these vehicles could lead to new technologies in vehicle development that could make hydrogen-fueled vehicles more cost effective, economical, efficient and more widely used. In order to advance the development of a hydrogen future in Southern Nevada, project partners recognized a need to bring various entities involved in hydrogen development and deployment together as a means of sharing knowledge and eliminating duplication of efforts. A road-mapping session was held in Las Vegas in June 2006. The Nevada State Energy Office, representatives from DOE, DOE contractors and LANL, NETL, NREL were present. Leadership from the National hydrogen Association Board of Directors also attended. As a result of this session, a roadmap for hydrogen development was created. This roadmap has the ability to become a tool for use by other road-mapping efforts in the hydrogen community. It could also become a standard template for other states or even countries to approach planning for a hydrogen

  5. Quantitative estimation of hydrogen concentration on the Ni3Al specimens surface in the process of hydrogen release

    International Nuclear Information System (INIS)

    Katano, Gen; Sano, Shogo; Saito, Hideo; Mori, Minoru

    2000-01-01

    The method to calculate the hydrogen concentration in metal specimens is given by tritium counts with the liquid scintillation counter. As segments to measure, Ni 3 Al intermetallic compound crystals were used. Tritium was charged to crystals with the method of cathode charging. The charged tritium was transported by diffusion and released from specimen surface. The tritium releasing rate was calculated from the increasing rate of tritium activity. Then the concentration of hydrogen at the surface was calculated from tritium counts. The outcome showed that the hydrogen concentration decreases at specimens surface by elapsed time. Then, the behavior of tritium diffusion was affected by doped boron (up to 0.235 atom% B and 0.470 atom% B) in Ni 3 Al crystals. As the amount of boron increased, the tritium diffusion coefficient decreased. And the hydrogen concentration varied with the amount of boron. After passing enough time, the hydrogen concentration in crystals with boron was much larger than the one without boron. Since it is very likely that the hydrogen concentration is affected by the number of hydrogen sites in the crystal, it is obvious judging by these phenomena, that by doping boron, numbers of hydrogen trapping sites were created. As the hydrogen distribution becomes homogenous after passing enough time, it is possible to measure the hydrogen concentration in all the crystals from β-ray counts at specimens surface. (author)

  6. Pole shifting with constrained output feedback

    International Nuclear Information System (INIS)

    Hamel, D.; Mensah, S.; Boisvert, J.

    1984-03-01

    The concept of pole placement plays an important role in linear, multi-variable, control theory. It has received much attention since its introduction, and several pole shifting algorithms are now available. This work presents a new method which allows practical and engineering constraints such as gain limitation and controller structure to be introduced right into the pole shifting design strategy. This is achieved by formulating the pole placement problem as a constrained optimization problem. Explicit constraints (controller structure and gain limits) are defined to identify an admissible region for the feedback gain matrix. The desired pole configuration is translated into an appropriate cost function which must be closed-loop minimized. The resulting constrained optimization problem can thus be solved with optimization algorithms. The method has been implemented as an algorithmic interactive module in a computer-aided control system design package, MVPACK. The application of the method is illustrated to design controllers for an aircraft and an evaporator. The results illustrate the importance of controller structure on overall performance of a control system

  7. Changes in epistemic frameworks: Random or constrained?

    Directory of Open Access Journals (Sweden)

    Ananka Loubser

    2012-11-01

    Full Text Available Since the emergence of a solid anti-positivist approach in the philosophy of science, an important question has been to understand how and why epistemic frameworks change in time, are modified or even substituted. In contemporary philosophy of science three main approaches to framework-change were detected in the humanist tradition:1. In both the pre-theoretical and theoretical domains changes occur according to a rather constrained, predictable or even pre-determined pattern (e.g. Holton.2. Changes occur in a way that is more random or unpredictable and free from constraints (e.g. Kuhn, Feyerabend, Rorty, Lyotard.3. Between these approaches, a middle position can be found, attempting some kind of synthesis (e.g. Popper, Lakatos.Because this situation calls for clarification and systematisation, this article in fact tried to achieve more clarity on how changes in pre-scientific frameworks occur, as well as provided transcendental criticism of the above positions. This article suggested that the above-mentioned positions are not fully satisfactory, as change and constancy are not sufficiently integrated. An alternative model was suggested in which changes in epistemic frameworks occur according to a pattern, neither completely random nor rigidly constrained, which results in change being dynamic but not arbitrary. This alternative model is integral, rather than dialectical and therefore does not correspond to position three. 

  8. Fringe instability in constrained soft elastic layers.

    Science.gov (United States)

    Lin, Shaoting; Cohen, Tal; Zhang, Teng; Yuk, Hyunwoo; Abeyaratne, Rohan; Zhao, Xuanhe

    2016-11-04

    Soft elastic layers with top and bottom surfaces adhered to rigid bodies are abundant in biological organisms and engineering applications. As the rigid bodies are pulled apart, the stressed layer can exhibit various modes of mechanical instabilities. In cases where the layer's thickness is much smaller than its length and width, the dominant modes that have been studied are the cavitation, interfacial and fingering instabilities. Here we report a new mode of instability which emerges if the thickness of the constrained elastic layer is comparable to or smaller than its width. In this case, the middle portion along the layer's thickness elongates nearly uniformly while the constrained fringe portions of the layer deform nonuniformly. When the applied stretch reaches a critical value, the exposed free surfaces of the fringe portions begin to undulate periodically without debonding from the rigid bodies, giving the fringe instability. We use experiments, theory and numerical simulations to quantitatively explain the fringe instability and derive scaling laws for its critical stress, critical strain and wavelength. We show that in a force controlled setting the elastic fingering instability is associated with a snap-through buckling that does not exist for the fringe instability. The discovery of the fringe instability will not only advance the understanding of mechanical instabilities in soft materials but also have implications for biological and engineered adhesives and joints.

  9. Ultrafine hydrogen storage powders

    Science.gov (United States)

    Anderson, Iver E.; Ellis, Timothy W.; Pecharsky, Vitalij K.; Ting, Jason; Terpstra, Robert; Bowman, Robert C.; Witham, Charles K.; Fultz, Brent T.; Bugga, Ratnakumar V.

    2000-06-13

    A method of making hydrogen storage powder resistant to fracture in service involves forming a melt having the appropriate composition for the hydrogen storage material, such, for example, LaNi.sub.5 and other AB.sub.5 type materials and AB.sub.5+x materials, where x is from about -2.5 to about +2.5, including x=0, and the melt is gas atomized under conditions of melt temperature and atomizing gas pressure to form generally spherical powder particles. The hydrogen storage powder exhibits improved chemcial homogeneity as a result of rapid solidfication from the melt and small particle size that is more resistant to microcracking during hydrogen absorption/desorption cycling. A hydrogen storage component, such as an electrode for a battery or electrochemical fuel cell, made from the gas atomized hydrogen storage material is resistant to hydrogen degradation upon hydrogen absorption/desorption that occurs for example, during charging/discharging of a battery. Such hydrogen storage components can be made by consolidating and optionally sintering the gas atomized hydrogen storage powder or alternately by shaping the gas atomized powder and a suitable binder to a desired configuration in a mold or die.

  10. Canadian hydrogen safety program

    International Nuclear Information System (INIS)

    MacIntyre, I.; Tchouvelev, A.V.; Hay, D.R.; Wong, J.; Grant, J.; Benard, P.

    2007-01-01

    The Canadian hydrogen safety program (CHSP) is a project initiative of the Codes and Standards Working Group of the Canadian transportation fuel cell alliance (CTFCA) that represents industry, academia, government, and regulators. The Program rationale, structure and contents contribute to acceptance of the products, services and systems of the Canadian Hydrogen Industry into the Canadian hydrogen stakeholder community. It facilitates trade through fair insurance policies and rates, effective and efficient regulatory approval procedures and accommodation of the interests of the general public. The Program integrates a consistent quantitative risk assessment methodology with experimental (destructive and non-destructive) failure rates and consequence-of-release data for key hydrogen components and systems into risk assessment of commercial application scenarios. Its current and past six projects include Intelligent Virtual Hydrogen Filling Station (IVHFS), Hydrogen clearance distances, comparative quantitative risk comparison of hydrogen and compressed natural gas (CNG) refuelling options; computational fluid dynamics (CFD) modeling validation, calibration and enhancement; enhancement of frequency and probability analysis, and Consequence analysis of key component failures of hydrogen systems; and fuel cell oxidant outlet hydrogen sensor project. The Program projects are tightly linked with the content of the International Energy Agency (IEA) Task 19 Hydrogen Safety. (author)

  11. High density hydrogen research

    International Nuclear Information System (INIS)

    Hawke, R.S.

    1977-01-01

    The interest in the properties of very dense hydrogen is prompted by its abundance in Saturn and Jupiter and its importance in laser fusion studies. Furthermore, it has been proposed that the metallic form of hydrogen may be a superconductor at relatively high temperatures and/or exist in a metastable phase at ambient pressure. For ten years or more, laboratories have been developing the techniques to study hydrogen in the megabar region (1 megabar = 100 GPa). Three major approaches to study dense hydrogen experimentally have been used, static presses, shockwave compression, and magnetic compression. Static tchniques have crossed the megabar threshold in stiff materials but have not yet been convincingly successful in very compressible hydrogen. Single and double shockwave techniques have improved the precision of the pressure, volume, temperature Equation of State (EOS) of molecular hydrogen (deuterium) up to near 1 Mbar. Multiple shockwave and magnetic techniques have compressed hydrogen to several megabars and densities in the range of the metallic phase. The net result is that hydrogen becomes conducting at a pressure between 2 and 4 megabars. Hence, the possibility of making a significant amount of hydrogen into a metal in a static press remains a formidable challenge. The success of such experiments will hopefully answer the questions about hydrogen's metallic vs. conducting molecular phase, superconductivity, and metastability. 4 figures, 15 references

  12. The energy carrier hydrogen

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    The potential of hydrogen to be used as a clean fuel for the production of heat and power, as well as for the propulsion of aeroplanes and vehicles, is described, in particular for Germany. First, attention is paid to the application of hydrogen as a basic material for the (petro)chemical industry, as an indirect energy source for (petro)chemical processes, and as a direct energy source for several purposes. Than the importance of hydrogen as an energy carrier in a large-scale application of renewable energy sources is discussed. Next an overview is given of new and old hydrogen production techniques from fossil fuels, biomass, or the electrolysis of water. Energetic applications of hydrogen in the transportation sector and the production of electric power and heat are mentioned. Brief descriptions are given of techniques to store hydrogen safely. Finally attention is paid to hydrogen research in Germany. Two hydrogen projects, in which Germany participates, are briefly dealt with: the Euro-Quebec project (production of hydrogen by means of hydropower), and the HYSOLAR project (hydrogen production by means of solar energy). 18 figs., 1 tab., 7 refs

  13. Hydrogen energy applications

    International Nuclear Information System (INIS)

    Okken, P.A.

    1992-10-01

    For the Energy and Material consumption Scenarios (EMS), by which emission reduction of CO 2 and other greenhouse gases can be calculated, calculations are executed by means of the MARKAL model (MARket ALlocation, a process-oriented dynamic linear programming model to minimize the costs of the energy system) for the Netherlands energy economy in the period 2000-2040, using a variable CO 2 emission limit. The results of these calculations are published in a separate report (ECN-C--92-066). The use of hydrogen can play an important part in the above-mentioned period. An overview of several options to produce or use hydrogen is given and added to the MARKAL model. In this report techno-economical data and estimates were compiled for several H 2 -application options, which subsequently also are added to the MARKAL model. After a brief chapter on hydrogen and the impact on the reduction of CO 2 emission attention is paid to stationary and mobile applications. The stationary options concern the mixing of natural gas with 10% hydrogen, a 100% substitution of natural gas by hydrogen, the use of a direct steam generator (combustion of hydrogen by means of pure oxygen, followed by steam injection to produce steam), and the use of fuel cells. The mobile options concern the use of hydrogen in the transportation sector. In brief, attention is paid to a hydrogen passenger car with an Otto engine, and a hydrogen passenger car with a fuel cell, a hybrid (metal)-hydride car, a hydrogen truck, a truck with a methanol fuel cell, a hydrogen bus, an inland canal boat with a hydrogen fuel cell, and finally a hydrogen airplane. 2 figs., 15 tabs., 1 app., 26 refs

  14. Short hydrogen bonds in the catalytic mechanism of serine proteases

    Directory of Open Access Journals (Sweden)

    VLADIMIR LESKOVAC

    2008-04-01

    Full Text Available The survey of crystallographic data from the Protein Data Bank for 37 structures of trypsin and other serine proteases at a resolution of 0.78–1.28 Å revealed the presence of hydrogen bonds in the active site of the enzymes, which are formed between the catalytic histidine and aspartate residues and are on average 2.7 Å long. This is the typical bond length for normal hydrogen bonds. The geometric properties of the hydrogen bonds in the active site indicate that the H atom is not centered between the heteroatoms of the catalytic histidine and aspartate residues in the active site. Taken together, these findings exclude the possibility that short “low-barrier” hydrogen bonds are formed in the ground state structure of the active sites examined in this work. Some time ago, it was suggested by Cleland that the “low-barrier hydrogen bond” hypothesis is operative in the catalytic mechanism of serine proteases, and requires the presence of short hydrogen bonds around 2.4 Å long in the active site, with the H atom centered between the catalytic heteroatoms. The conclusions drawn from this work do not exclude the validity of the “low-barrier hydrogen bond” hypothesis at all, but they merely do not support it in this particular case, with this particular class of enzymes.

  15. Controlled Hydrogen Fleet and Infrastructure Demonstration Project

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Scott Staley

    2010-03-31

    the fuel provider, while viability of the vehicle requires an expected level of cost, comfort, safety and operation, especially driving range, that consumers require. This presents a classic 'chicken and egg' problem, which Ford believes can be solved with thoughtful implementation plans. The eighteen Ford Focus FCV vehicles that were operated for this demonstration project provided the desired real world experience. Some things worked better than expected. Most notable was the robustness and life of the fuel cell. This is thought to be the result of the full hybrid configuration of the drive system where the battery helps to overcome the performance reduction associated with time related fuel cell degradation. In addition, customer satisfaction surveys indicated that people like the cars and the concept and operated them with little hesitation. Although the demonstrated range of the cars was near 200 miles, operators felt constrained because of the lack of a number of conveniently located fueling stations. Overcoming this major concern requires overcoming a key roadblock, fuel storage, in a manner that permits sufficient quantity of fuel without sacrificing passenger or cargo capability. Fueling infrastructure, on the other hand, has been problematic. Only three of a planned seven stations were opened. The difficulty in obtaining public approval and local government support for hydrogen fuel, based largely on the fear of hydrogen that grew from past disasters and atomic weaponry, has inhibited progress and presents a major roadblock to implementation. In addition the cost of hydrogen production, in any of the methodologies used in this program, does not show a rapid reduction to commercially viable rates. On the positive side of this issue was the demonstrated safety of the fueling station, equipment and process. In the Ford program, there were no reported safety incidents.

  16. Effects of dimethyl sulfoxide on the hydrogen bonding structure and ...

    Indian Academy of Sciences (India)

    School of Basic Sciences, Indian Institute of Technology, Bhubaneswar 751 013, India e-mail: .... molecules are modeled by the 4-site P2 model of Luzar and Chandler9 which ..... lifetime of hydrogen bond acceptance by carbonyl oxy-.

  17. Energy storage applications of activated carbons: supercapacitors and hydrogen storage

    OpenAIRE

    Sevilla Solís, Marta; Mokaya, Robert

    2014-01-01

    Porous carbons have several advantageous properties with respect to their use in energy applications that require constrained space such as in electrode materials for supercapacitors and as solid state hydrogen stores. The attractive properties of porous carbons include, ready abundance, chemical and thermal stability, ease of processability and low framework density. Activated carbons, which are perhaps the most explored class of porous carbons, have been traditionally employed as catalyst s...

  18. Hydrogen gains further momentum

    International Nuclear Information System (INIS)

    Anon.

    2017-01-01

    As first industrial production projects should become a reality in the next few years, hydrogen as a source of energy will find important applications with mobility, which momentum is rapid and irresistible. Next steps will be the (large capacity) storage of hydrogen associated to power-to-gas systems and the generalization of renewable energies. This document presents 5 articles, which themes are: Description and explanation of the process of hydrogen production; Presentation of the H2V project for the construction, in Normandy, of the first operational industrial hydrogen production plant using electric power 100 pc generated by renewable energies; The conversion of electric power from renewable energies through hydrogen storage and fuel cells for buildings applications (Sylfen project); The development of a reversible fuel cell at Mines-Paris Tech University, that will be adapted to the storage of renewable electric power; Hydrogen as a lever for the development of zero-emission vehicles, from trucks to cars and bicycles

  19. Hydrogen Fuelling Stations

    DEFF Research Database (Denmark)

    Rothuizen, Erasmus Damgaard

    . A system consisting of one high pressure storage tank is used to investigate the thermodynamics of fuelling a hydrogen vehicle. The results show that the decisive parameter for how the fuelling proceeds is the pressure loss in the vehicle. The single tank fuelling system is compared to a cascade fuelling......This thesis concerns hydrogen fuelling stations from an overall system perspective. The study investigates thermodynamics and energy consumption of hydrogen fuelling stations for fuelling vehicles for personal transportation. For the study a library concerning the components in a hydrogen fuelling...... station has been developed in Dymola. The models include the fuelling protocol (J2601) for hydrogen vehicles made by Society of Automotive Engineers (SAE) and the thermodynamic property library CoolProp is used for retrieving state point. The components in the hydrogen fuelling library are building up...

  20. Fuel Cell and Hydrogen Technology Validation | Hydrogen and Fuel Cells |

    Science.gov (United States)

    NREL Fuel Cell and Hydrogen Technology Validation Fuel Cell and Hydrogen Technology Validation The NREL technology validation team works on validating hydrogen fuel cell electric vehicles; hydrogen fueling infrastructure; hydrogen system components; and fuel cell use in early market applications such as

  1. Hydrogen energy systems studies

    Energy Technology Data Exchange (ETDEWEB)

    Ogden, J.M.; Steinbugler, M.; Dennis, E. [Princeton Univ., NJ (United States)] [and others

    1995-09-01

    For several years, researchers at Princeton University`s Center for Energy and Environmental Studies have carried out technical and economic assessments of hydrogen energy systems. Initially, we focussed on the long term potential of renewable hydrogen. More recently we have explored how a transition to renewable hydrogen might begin. The goal of our current work is to identify promising strategies leading from near term hydrogen markets and technologies toward eventual large scale use of renewable hydrogen as an energy carrier. Our approach has been to assess the entire hydrogen energy system from production through end-use considering technical performance, economics, infrastructure and environmental issues. This work is part of the systems analysis activity of the DOE Hydrogen Program. In this paper we first summarize the results of three tasks which were completed during the past year under NREL Contract No. XR-11265-2: in Task 1, we carried out assessments of near term options for supplying hydrogen transportation fuel from natural gas; in Task 2, we assessed the feasibility of using the existing natural gas system with hydrogen and hydrogen blends; and in Task 3, we carried out a study of PEM fuel cells for residential cogeneration applications, a market which might have less stringent cost requirements than transportation. We then give preliminary results for two other tasks which are ongoing under DOE Contract No. DE-FG04-94AL85803: In Task 1 we are assessing the technical options for low cost small scale production of hydrogen from natural gas, considering (a) steam reforming, (b) partial oxidation and (c) autothermal reforming, and in Task 2 we are assessing potential markets for hydrogen in Southern California.

  2. Hydrogen storage container

    Science.gov (United States)

    Wang, Jy-An John; Feng, Zhili; Zhang, Wei

    2017-02-07

    An apparatus and system is described for storing high-pressure fluids such as hydrogen. An inner tank and pre-stressed concrete pressure vessel share the structural and/or pressure load on the inner tank. The system and apparatus provide a high performance and low cost container while mitigating hydrogen embrittlement of the metal tank. System is useful for distributing hydrogen to a power grid or to a vehicle refueling station.

  3. Hydrogen meter prooftesting

    International Nuclear Information System (INIS)

    McCown, J.J.; Mettler, G.W.

    1976-04-01

    Two diffusion type hydrogen meters have been tested on the Prototype Applications Loop (PAL). The ANL designed unit was used to monitor hydrogen in sodium during FFTF startup and over a wide range of hydrogen concentrations resulting from chemical additions to the sodium and cover gas. A commercially available meter was added and its performance compared with the ANL unit. Details of the test work are described

  4. Photochemical hydrogen production system

    International Nuclear Information System (INIS)

    Copeland, R.J.

    1990-01-01

    Both technical and economic factors affect the cost of producing hydrogen by photochemical processes. Technical factors include the efficiency and the capital and operating costs of the renewable hydrogen conversion system; economic factors include discount rates, economic life, credit for co-product oxygen, and the value of the energy produced. This paper presents technical and economic data for a system that generates on-peak electric power form photochemically produced hydrogen

  5. Hydrogen Fuel Cell Vehicles

    OpenAIRE

    Anton Francesch, Judit

    1992-01-01

    Hydrogen is an especially attractive transportation fuel. It is the least polluting fuel available, and can be produced anywhere there is water and a clean source of electricity. A fuel cycle in which hydrogen is produced by solar-electrolysis of water, or by gasification of renewably grown biomass, and then used in a fuel-cell powered electric-motor vehicle (FCEV), would produce little or no local, regional, or global pollution. Hydrogen FCEVs would combine the best features of bat...

  6. Hydrogen storage materials and method of making by dry homogenation

    Science.gov (United States)

    Jensen, Craig M.; Zidan, Ragaiy A.

    2002-01-01

    Dry homogenized metal hydrides, in particular aluminum hydride compounds, as a material for reversible hydrogen storage is provided. The reversible hydrogen storage material comprises a dry homogenized material having transition metal catalytic sites on a metal aluminum hydride compound, or mixtures of metal aluminum hydride compounds. A method of making such reversible hydrogen storage materials by dry doping is also provided and comprises the steps of dry homogenizing metal hydrides by mechanical mixing, such as be crushing or ball milling a powder, of a metal aluminum hydride with a transition metal catalyst. In another aspect of the invention, a method of powering a vehicle apparatus with the reversible hydrogen storage material is provided.

  7. Biological Hydrogen Carriers: Harnessing Fossil Fuels in a Carbon-Constrained World

    Directory of Open Access Journals (Sweden)

    Mark T. Holtzapple

    2009-05-01

    Full Text Available Due to their widespread availability, the use of lignocellulosic resources as feedstocks for fuels and chemicals is very promising. To make this a practical reality, 18 years of research at Texas A&M University have resulted in the development of a novel process known as MixAlco.TM This article compares this process with other technologies and provides some process details. At the end, a brief economic analysis is presented. / Debido a una amplia disponibilidad, el uso de recursos lignocelulósicos como materia prima para producir combustibles y otros productos químicos es muy prometedor. Para hacer de esto una realidad, 18 años de investigación en la Universidad de Texas A&M han resultado en el desarrollo de un proceso novedoso denominado MixAlco.TM Este artículo compara este proceso con otras tecnologías y provee algunos detalles del proceso. Por último, se presenta un breve análisis económico.

  8. Liquid hydrogen in Japan

    Energy Technology Data Exchange (ETDEWEB)

    Yasumi, S. [Iwatani Corp., Osaka (Japan). Dept. of Overseas Business Development

    2009-07-01

    Japan's Iwatani Corporation has focused its attention on hydrogen as the ultimate energy source in future. Unlike the United States, hydrogen use and delivery in liquid form is extremely limited in the European Union and in Japan. Iwatani Corporation broke through industry stereotypes by creating and building Hydro Edge Co. Ltd., Japan's largest liquid hydrogen plant. It was established in 2006 as a joint venture between Iwatani and Kansai Electric Power Group in Osaka. Hydro Edge is Japan's first combined liquid hydrogen and ASU plant, and is fully operational. Liquid oxygen, liquid nitrogen and liquid argon are separated from air using the cryogenic energy of liquefied natural gas fuel that is used for power generation. Liquid hydrogen is produced efficiently and simultaneously using liquid nitrogen. Approximately 12 times as much hydrogen in liquid form can be transported and supplied as pressurized hydrogen gas. This technology is a significant step forward in the dissemination and expansion of hydrogen in a hydrogen-based economy.

  9. Hydrogen gas detector

    International Nuclear Information System (INIS)

    Bohl, T.L.

    1982-01-01

    A differential thermocouple hydrogen gas detector has one thermocouple junction coated with an activated palladium or palladium-silver alloy catalytic material to allow heated hydrogen gas to react with the catalyst and raise the temperature of that junction. The other juction is covered with inert glass or epoxy resin, and does not experience a rise in temperature in the presence of hydrogen gas. A coil heater may be mounted around the thermocouple junctions to heat the hydrogen, or the gas may be passed through a heated block prior to exposing it to the thermocouples

  10. Sustainable hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Block, D.L.; Linkous, C.; Muradov, N.

    1996-01-01

    This report describes the Sustainable Hydrogen Production research conducted at the Florida Solar Energy Center (FSEC) for the past year. The report presents the work done on the following four tasks: Task 1--production of hydrogen by photovoltaic-powered electrolysis; Task 2--solar photocatalytic hydrogen production from water using a dual-bed photosystem; Task 3--development of solid electrolytes for water electrolysis at intermediate temperatures; and Task 4--production of hydrogen by thermocatalytic cracking of natural gas. For each task, this report presents a summary, introduction/description of project, and results.

  11. Purification of hydrogen sulfide

    International Nuclear Information System (INIS)

    Tsao, U.

    1978-01-01

    A process is described for purifying a hydrogen sulfide gas stream containing carbon dioxide, comprising (a) passing the gas stream through a bed of solid hydrated lime to form calcium hydrosulfide and calcium carbonate and (b) regenerating hydrogen sulfide from said calcium hydrosulfide by reacting the calcium hydrosulfide with additional carbon dioxide. The process is especially applicable for use in a heavy water recovery process wherein deuterium is concentrated from a feed water containing carbon dioxide by absorption and stripping using hydrogen sulfide as a circulating medium, and the hydrogen sulfide absorbs a small quantity of carbon dioxide along with deuterium in each circulation

  12. Hydrogen as automotive fuel

    International Nuclear Information System (INIS)

    Ambrosini, G.; Ciancia, A.; Pede, G.; Brighigna, M.

    1993-01-01

    Hydrogen fueled vehicles may just be the answer to the air pollution problem in highly polluted urban environments where the innovative vehicle's air pollution abatement characteristics would justify its high operating costs as compared with those of conventional automotive alternatives. This paper examines the feasibility of hydrogen as an automotive fuel by analyzing the following aspects: the chemical-physical properties of hydrogen in relation to its use in internal combustion engines; the modifications necessary to adapt internal combustion engines to hydrogen use; hydrogen fuel injection systems; current production technologies and commercialization status of hydrogen automotive fuels; energy efficiency ratings; environmental impacts; in-vehicle storage systems - involving the use of hydrides, high pressure systems and liquid hydrogen storage systems; performance in terms of pay-load ratio; autonomous operation; and operating costs. With reference to recent trial results being obtained in the USA, an assessment is also made of the feasibility of the use of methane-hydrogen mixtures as automotive fuels. The paper concludes with a review of progress being made by ENEA (the Italian Agency for New Technology, Energy and the Environment) in the development of fuel storage and electronic fuel injection systems for hydrogen powered vehicles

  13. Hydrogen as automotive fuel

    International Nuclear Information System (INIS)

    Dini, D.; Ciancia, A.; Pede, G.; Sglavo, V.; ENEA, Rome

    1992-01-01

    An assessment of the technical/economic feasibility of the use of hydrogen as an automotive fuel is made based on analyses of the following: the chemical- physical properties of hydrogen in relation to its use in internal combustion engines; the modifications necessary to adapt internal combustion engines to hydrogen use; hydrogen fuel injection systems - with water vapour injection, cryogenic injection, and the low or high pressure injection of hydrogen directly into the combustion chamber; the current commercialization status of hydrogen automotive fuels; energy efficiency ratings; environmental impacts; in-vehicle storage systems - involving the use of hydrides, high pressure systems and liquid hydrogen storage systems; performance in terms of pay-load ratio; autonomous operation; and operating costs. The paper concludes that, considering current costs for hydrogen fuel production, distribution and use, at present, the employment of hydrogen fuelled vehicles is feasible only in highly polluted urban environments where the innovative vehicle's air pollution abatement characteristics would justify its high operating costs as compared with those of conventional automotive alternatives

  14. Palladium Nanoparticle Hydrogen Sensor

    Directory of Open Access Journals (Sweden)

    I. Pavlovsky

    2006-12-01

    Full Text Available An innovative hydrogen sensor based on palladium (Pd nanoparticle networks is described in the article. Made by Applied Nanotech Inc. sensor has a fast response time, in the range of seconds, which is increased at 80 °C due to higher hydrogen diffusion rates into the palladium lattice. The low detection limit of the sensor is 10 ppm of H2, and the high limit is 40,000 ppm. This is 100% of a lowest flammability level of hydrogen. This range of sensitivities complies with the requirements that one would expect for a reliable hydrogen sensor.

  15. Atomic hydrogen reactor

    International Nuclear Information System (INIS)

    Massip de Turville, C.M.D.

    1982-01-01

    Methods are discussed of generating heat in an atomic hydrogen reactor which involve; the production of atomic hydrogen by an electrical discharge, the capture of nascent neutrons from atomic hydrogen in a number of surrounding steel alloy tubes having a high manganese content to produce 56 Mn, the irradiation of atomic hydrogen by the high energy antineutrinos from the beta decay of 56 Mn to yield nascent neutrons, and the removal of the heat generated by the capture of nascent neutrons by 55 Mn and the beta decay of 56 Mn. (U.K.)

  16. Constraining local 3-D models of the saturated-zone, Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Barr, G.E.; Shannon, S.A.

    1994-01-01

    A qualitative three-dimensional analysis of the saturated zone flow system was performed for a 8 km x 8 km region including the potential Yucca Mountain repository site. Certain recognized geologic features of unknown hydraulic properties were introduced to assess the general response of the flow field to these features. Two of these features, the Solitario Canyon fault and the proposed fault in Drill Hole Wash, appear to constrain flow and allow calibration

  17. Scheduling of resource-constrained projects

    CERN Document Server

    Klein, Robert

    2000-01-01

    Project management has become a widespread instrument enabling organizations to efficiently master the challenges of steadily shortening product life cycles, global markets and decreasing profit margins. With projects increasing in size and complexity, their planning and control represents one of the most crucial management tasks. This is especially true for scheduling, which is concerned with establishing execution dates for the sub-activities to be performed in order to complete the project. The ability to manage projects where resources must be allocated between concurrent projects or even sub-activities of a single project requires the use of commercial project management software packages. However, the results yielded by the solution procedures included are often rather unsatisfactory. Scheduling of Resource-Constrained Projects develops more efficient procedures, which can easily be integrated into software packages by incorporated programming languages, and thus should be of great interest for practiti...

  18. Constrained mathematics evaluation in probabilistic logic analysis

    Energy Technology Data Exchange (ETDEWEB)

    Arlin Cooper, J

    1998-06-01

    A challenging problem in mathematically processing uncertain operands is that constraints inherent in the problem definition can require computations that are difficult to implement. Examples of possible constraints are that the sum of the probabilities of partitioned possible outcomes must be one, and repeated appearances of the same variable must all have the identical value. The latter, called the 'repeated variable problem', will be addressed in this paper in order to show how interval-based probabilistic evaluation of Boolean logic expressions, such as those describing the outcomes of fault trees and event trees, can be facilitated in a way that can be readily implemented in software. We will illustrate techniques that can be used to transform complex constrained problems into trivial problems in most tree logic expressions, and into tractable problems in most other cases.

  19. Constraining dark sectors with monojets and dijets

    International Nuclear Information System (INIS)

    Chala, Mikael; Kahlhoefer, Felix; Nardini, Germano; Schmidt-Hoberg, Kai; McCullough, Matthew

    2015-03-01

    We consider dark sector particles (DSPs) that obtain sizeable interactions with Standard Model fermions from a new mediator. While these particles can avoid observation in direct detection experiments, they are strongly constrained by LHC measurements. We demonstrate that there is an important complementarity between searches for DSP production and searches for the mediator itself, in particular bounds on (broad) dijet resonances. This observation is crucial not only in the case where the DSP is all of the dark matter but whenever - precisely due to its sizeable interactions with the visible sector - the DSP annihilates away so efficiently that it only forms a dark matter subcomponent. To highlight the different roles of DSP direct detection and LHC monojet and dijet searches, as well as perturbativity constraints, we first analyse the exemplary case of an axial-vector mediator and then generalise our results. We find important implications for the interpretation of LHC dark matter searches in terms of simplified models.

  20. Constrained KP models as integrable matrix hierarchies

    International Nuclear Information System (INIS)

    Aratyn, H.; Ferreira, L.A.; Gomes, J.F.; Zimerman, A.H.

    1997-01-01

    We formulate the constrained KP hierarchy (denoted by cKP K+1,M ) as an affine [cflx sl](M+K+1) matrix integrable hierarchy generalizing the Drinfeld endash Sokolov hierarchy. Using an algebraic approach, including the graded structure of the generalized Drinfeld endash Sokolov hierarchy, we are able to find several new universal results valid for the cKP hierarchy. In particular, our method yields a closed expression for the second bracket obtained through Dirac reduction of any untwisted affine Kac endash Moody current algebra. An explicit example is given for the case [cflx sl](M+K+1), for which a closed expression for the general recursion operator is also obtained. We show how isospectral flows are characterized and grouped according to the semisimple non-regular element E of sl(M+K+1) and the content of the center of the kernel of E. copyright 1997 American Institute of Physics

  1. Quantum cosmology of classically constrained gravity

    International Nuclear Information System (INIS)

    Gabadadze, Gregory; Shang Yanwen

    2006-01-01

    In [G. Gabadadze, Y. Shang, hep-th/0506040] we discussed a classically constrained model of gravity. This theory contains known solutions of General Relativity (GR), and admits solutions that are absent in GR. Here we study cosmological implications of some of these new solutions. We show that a spatially-flat de Sitter universe can be created from 'nothing'. This universe has boundaries, and its total energy equals to zero. Although the probability to create such a universe is exponentially suppressed, it favors initial conditions suitable for inflation. Then we discuss a finite-energy solution with a nonzero cosmological constant and zero space-time curvature. There is no tunneling suppression to fluctuate into this state. We show that for a positive cosmological constant this state is unstable-it can rapidly transition to a de Sitter universe providing a new unsuppressed channel for inflation. For a negative cosmological constant the space-time flat solutions is stable.

  2. Multiple Clustering Views via Constrained Projections

    DEFF Research Database (Denmark)

    Dang, Xuan-Hong; Assent, Ira; Bailey, James

    2012-01-01

    Clustering, the grouping of data based on mutual similarity, is often used as one of principal tools to analyze and understand data. Unfortunately, most conventional techniques aim at finding only a single clustering over the data. For many practical applications, especially those being described...... in high dimensional data, it is common to see that the data can be grouped into different yet meaningful ways. This gives rise to the recently emerging research area of discovering alternative clusterings. In this preliminary work, we propose a novel framework to generate multiple clustering views....... The framework relies on a constrained data projection approach by which we ensure that a novel alternative clustering being found is not only qualitatively strong but also distinctively different from a reference clustering solution. We demonstrate the potential of the proposed framework using both synthetic...

  3. Shape space exploration of constrained meshes

    KAUST Repository

    Yang, Yongliang

    2011-12-12

    We present a general computational framework to locally characterize any shape space of meshes implicitly prescribed by a collection of non-linear constraints. We computationally access such manifolds, typically of high dimension and co-dimension, through first and second order approximants, namely tangent spaces and quadratically parameterized osculant surfaces. Exploration and navigation of desirable subspaces of the shape space with regard to application specific quality measures are enabled using approximants that are intrinsic to the underlying manifold and directly computable in the parameter space of the osculant surface. We demonstrate our framework on shape spaces of planar quad (PQ) meshes, where each mesh face is constrained to be (nearly) planar, and circular meshes, where each face has a circumcircle. We evaluate our framework for navigation and design exploration on a variety of inputs, while keeping context specific properties such as fairness, proximity to a reference surface, etc. © 2011 ACM.

  4. Shape space exploration of constrained meshes

    KAUST Repository

    Yang, Yongliang; Yang, Yijun; Pottmann, Helmut; Mitra, Niloy J.

    2011-01-01

    We present a general computational framework to locally characterize any shape space of meshes implicitly prescribed by a collection of non-linear constraints. We computationally access such manifolds, typically of high dimension and co-dimension, through first and second order approximants, namely tangent spaces and quadratically parameterized osculant surfaces. Exploration and navigation of desirable subspaces of the shape space with regard to application specific quality measures are enabled using approximants that are intrinsic to the underlying manifold and directly computable in the parameter space of the osculant surface. We demonstrate our framework on shape spaces of planar quad (PQ) meshes, where each mesh face is constrained to be (nearly) planar, and circular meshes, where each face has a circumcircle. We evaluate our framework for navigation and design exploration on a variety of inputs, while keeping context specific properties such as fairness, proximity to a reference surface, etc. © 2011 ACM.

  5. Constrained vertebrate evolution by pleiotropic genes.

    Science.gov (United States)

    Hu, Haiyang; Uesaka, Masahiro; Guo, Song; Shimai, Kotaro; Lu, Tsai-Ming; Li, Fang; Fujimoto, Satoko; Ishikawa, Masato; Liu, Shiping; Sasagawa, Yohei; Zhang, Guojie; Kuratani, Shigeru; Yu, Jr-Kai; Kusakabe, Takehiro G; Khaitovich, Philipp; Irie, Naoki

    2017-11-01

    Despite morphological diversification of chordates over 550 million years of evolution, their shared basic anatomical pattern (or 'bodyplan') remains conserved by unknown mechanisms. The developmental hourglass model attributes this to phylum-wide conserved, constrained organogenesis stages that pattern the bodyplan (the phylotype hypothesis); however, there has been no quantitative testing of this idea with a phylum-wide comparison of species. Here, based on data from early-to-late embryonic transcriptomes collected from eight chordates, we suggest that the phylotype hypothesis would be better applied to vertebrates than chordates. Furthermore, we found that vertebrates' conserved mid-embryonic developmental programmes are intensively recruited to other developmental processes, and the degree of the recruitment positively correlates with their evolutionary conservation and essentiality for normal development. Thus, we propose that the intensively recruited genetic system during vertebrates' organogenesis period imposed constraints on its diversification through pleiotropic constraints, which ultimately led to the common anatomical pattern observed in vertebrates.

  6. Statistical mechanics of budget-constrained auctions

    International Nuclear Information System (INIS)

    Altarelli, F; Braunstein, A; Realpe-Gomez, J; Zecchina, R

    2009-01-01

    Finding the optimal assignment in budget-constrained auctions is a combinatorial optimization problem with many important applications, a notable example being in the sale of advertisement space by search engines (in this context the problem is often referred to as the off-line AdWords problem). On the basis of the cavity method of statistical mechanics, we introduce a message-passing algorithm that is capable of solving efficiently random instances of the problem extracted from a natural distribution, and we derive from its properties the phase diagram of the problem. As the control parameter (average value of the budgets) is varied, we find two phase transitions delimiting a region in which long-range correlations arise

  7. Constraining Dark Sectors with Monojets and Dijets

    CERN Document Server

    Chala, Mikael; McCullough, Matthew; Nardini, Germano; Schmidt-Hoberg, Kai

    2015-01-01

    We consider dark sector particles (DSPs) that obtain sizeable interactions with Standard Model fermions from a new mediator. While these particles can avoid observation in direct detection experiments, they are strongly constrained by LHC measurements. We demonstrate that there is an important complementarity between searches for DSP production and searches for the mediator itself, in particular bounds on (broad) dijet resonances. This observation is crucial not only in the case where the DSP is all of the dark matter but whenever - precisely due to its sizeable interactions with the visible sector - the DSP annihilates away so efficiently that it only forms a dark matter subcomponent. To highlight the different roles of DSP direct detection and LHC monojet and dijet searches, as well as perturbativity constraints, we first analyse the exemplary case of an axial-vector mediator and then generalise our results. We find important implications for the interpretation of LHC dark matter searches in terms of simpli...

  8. Statistical mechanics of budget-constrained auctions

    Science.gov (United States)

    Altarelli, F.; Braunstein, A.; Realpe-Gomez, J.; Zecchina, R.

    2009-07-01

    Finding the optimal assignment in budget-constrained auctions is a combinatorial optimization problem with many important applications, a notable example being in the sale of advertisement space by search engines (in this context the problem is often referred to as the off-line AdWords problem). On the basis of the cavity method of statistical mechanics, we introduce a message-passing algorithm that is capable of solving efficiently random instances of the problem extracted from a natural distribution, and we derive from its properties the phase diagram of the problem. As the control parameter (average value of the budgets) is varied, we find two phase transitions delimiting a region in which long-range correlations arise.

  9. Constrained least squares regularization in PET

    International Nuclear Information System (INIS)

    Choudhury, K.R.; O'Sullivan, F.O.

    1996-01-01

    Standard reconstruction methods used in tomography produce images with undesirable negative artifacts in background and in areas of high local contrast. While sophisticated statistical reconstruction methods can be devised to correct for these artifacts, their computational implementation is excessive for routine operational use. This work describes a technique for rapid computation of approximate constrained least squares regularization estimates. The unique feature of the approach is that it involves no iterative projection or backprojection steps. This contrasts with the familiar computationally intensive algorithms based on algebraic reconstruction (ART) or expectation-maximization (EM) methods. Experimentation with the new approach for deconvolution and mixture analysis shows that the root mean square error quality of estimators based on the proposed algorithm matches and usually dominates that of more elaborate maximum likelihood, at a fraction of the computational effort

  10. Constraining dark sectors with monojets and dijets

    Energy Technology Data Exchange (ETDEWEB)

    Chala, Mikael; Kahlhoefer, Felix; Nardini, Germano; Schmidt-Hoberg, Kai [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); McCullough, Matthew [European Organization for Nuclear Research (CERN), Geneva (Switzerland). Theory Div.

    2015-03-15

    We consider dark sector particles (DSPs) that obtain sizeable interactions with Standard Model fermions from a new mediator. While these particles can avoid observation in direct detection experiments, they are strongly constrained by LHC measurements. We demonstrate that there is an important complementarity between searches for DSP production and searches for the mediator itself, in particular bounds on (broad) dijet resonances. This observation is crucial not only in the case where the DSP is all of the dark matter but whenever - precisely due to its sizeable interactions with the visible sector - the DSP annihilates away so efficiently that it only forms a dark matter subcomponent. To highlight the different roles of DSP direct detection and LHC monojet and dijet searches, as well as perturbativity constraints, we first analyse the exemplary case of an axial-vector mediator and then generalise our results. We find important implications for the interpretation of LHC dark matter searches in terms of simplified models.

  11. Constraining the dark side with observations

    International Nuclear Information System (INIS)

    Diez-Tejedor, Alberto

    2007-01-01

    The main purpose of this talk is to use the observational evidences pointing out to the existence of a dark side in the universe in order to infer some of the properties of the unseen material. We will work within the Unified Dark Matter models, in which both, Dark Matter and Dark Energy appear as the result of one unknown component. By modeling effectively this component with a classical scalar field minimally coupled to gravity, we will use the observations to constrain the form of the dark action. Using the flat rotation curves of spiral galaxies we will see that we are restringed to the use of purely kinetic actions, previously studied in cosmology by Scherrer. Finally we arrive to a simple action which fits both cosmological and astrophysical observations

  12. Constraining the dark side with observations

    Energy Technology Data Exchange (ETDEWEB)

    Diez-Tejedor, Alberto [Dpto. de Fisica Teorica, Universidad del PaIs Vasco, Apdo. 644, 48080, Bilbao (Spain)

    2007-05-15

    The main purpose of this talk is to use the observational evidences pointing out to the existence of a dark side in the universe in order to infer some of the properties of the unseen material. We will work within the Unified Dark Matter models, in which both, Dark Matter and Dark Energy appear as the result of one unknown component. By modeling effectively this component with a classical scalar field minimally coupled to gravity, we will use the observations to constrain the form of the dark action. Using the flat rotation curves of spiral galaxies we will see that we are restringed to the use of purely kinetic actions, previously studied in cosmology by Scherrer. Finally we arrive to a simple action which fits both cosmological and astrophysical observations.

  13. Hard exclusive meson production to constrain GPDs

    Energy Technology Data Exchange (ETDEWEB)

    Wolbeek, Johannes ter; Fischer, Horst; Gorzellik, Matthias; Gross, Arne; Joerg, Philipp; Koenigsmann, Kay; Malm, Pasquale; Regali, Christopher; Schmidt, Katharina; Sirtl, Stefan; Szameitat, Tobias [Physikalisches Institut, Albert-Ludwigs-Universitaet Freiburg, Freiburg im Breisgau (Germany); Collaboration: COMPASS Collaboration

    2014-07-01

    The concept of Generalized Parton Distributions (GPDs) combines the two-dimensional spatial information, given by form factors, with the longitudinal momentum information from the PDFs. Thus, GPDs provide a three-dimensional 'tomography' of the nucleon. Furthermore, according to Ji's sum rule, the GPDs H and E enable access to the total angular momenta of quarks, antiquarks and gluons. While H can be approached using electroproduction cross section, hard exclusive meson production off a transversely polarized target can help to constrain the GPD E. At the COMPASS experiment at CERN, two periods of data taking were performed in 2007 and 2010, using a longitudinally polarized 160 GeV/c muon beam and a transversely polarized NH{sub 3} target. This talk introduces the data analysis of the process μ + p → μ' + p' + V, and recent results are presented.

  14. Enhancing hydrogen spillover and storage

    Science.gov (United States)

    Yang, Ralph T [Ann Arbor, MI; Li, Yingwel [Ann Arbor, MI; Lachawiec, Jr., Anthony J.

    2011-05-31

    Methods for enhancing hydrogen spillover and storage are disclosed. One embodiment of the method includes doping a hydrogen receptor with metal particles, and exposing the hydrogen receptor to ultrasonification as doping occurs. Another embodiment of the method includes doping a hydrogen receptor with metal particles, and exposing the doped hydrogen receptor to a plasma treatment.

  15. Methanation of hydrogen and carbon dioxide

    International Nuclear Information System (INIS)

    Burkhardt, Marko; Busch, Günter

    2013-01-01

    Highlights: • The biologic methanation of exclusively gases like hydrogen and carbon dioxide is feasible. • Electrical energy can be stored in the established gas grid by conversion to methane. • The quality of produced biogas is very high (c CH4 = 98 vol%). • The conversion rate is depending on H 2 -flow rate. - Abstract: A new method for the methanation of hydrogen and carbon dioxide is presented. In a novel anaerobic trickle-bed reactor, biochemical catalyzed methanation at mesophilic temperatures and ambient pressure can be realized. The conversion of gaseous substrates by immobilized hydrogenotrophic methanogens is a unique feature of this reactor type. The already patented reactor produces biogas which has a very high quality (c CH4 = 97.9 vol%). Therefore, the storage of biogas in the existing natural gas grid is possible without extensive purification. The specific methane production was measured with P = 1.17 Nm CH4 3 /(m R 3 d). It is conceivable to realize the process at sites that generate solar or wind energy and sites subject to the conditions for hydrogen electrolysis (or other methods of hydrogen production). The combination with conventional biogas plants under hydrogen addition to methane enrichment is possible as well. The process enables the coupling of various renewable energy sources

  16. Hydrogen gas getters: Susceptibility to poisoning

    International Nuclear Information System (INIS)

    Mroz, E.J.; Dye, R.C.; Duke, J.R.; Weinrach, J.

    1998-01-01

    About 40% (∼9,000) of the ∼23,000 transuranic (TRU) waste drums at Los Alamos National Laboratory (LANL) are presently unshippable because conservative calculations suggest that the hydrogen concentration may exceed the lower explosive limit for hydrogen. This situation extends across nearly all DOE sites holding and generating TRU waste. The incorporation of a hydrogen getter such as DEB into the waste drums (or the TRUPACT II shipping containers) could substantially mitigate the explosion risk. The result would be to increase the number of drums that qualify for transportation to the Waste Isolation Pilot Plant (WIPP) without having to resort to expensive re-packaging or waste treatment technologies. However, before this approach can be implemented, key technical questions must be answered. Foremost among these is the question of whether the presence of other chemical vapors and gases in the drum might poison the catalytic reaction between hydrogen and DEB. This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this project was to obtain fundamental information on the chemical mechanism of the catalytic reaction of hydrogen with one commonly used hydrogen getter, DEB. Experiments with these materials showed that the method of exposure affects the nature of the reaction products. The results of this work contributed to the development of a mechanistic model of the reaction

  17. Process for exchanging hydrogen isotopes between gaseous hydrogen and water

    International Nuclear Information System (INIS)

    Hindin, S. G.; Roberts, G. W.

    1980-01-01

    A process for exchanging isotopes of hydrogen, particularly tritium, between gaseous hydrogen and water is provided whereby gaseous hydrogen depeleted in tritium and liquid or gaseous water containing tritium are reacted in the presence of a metallic catalyst

  18. Hydrogen assisted diesel combustion

    Energy Technology Data Exchange (ETDEWEB)

    Lilik, Gregory K.; Boehman, Andre L. [The EMS Energy Institute, The Pennsylvania State University, University Park, PA 16802 (United States); Zhang, Hedan; Haworth, Daniel C. [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Herreros, Jose Martin [Escuela Tecnica Superior de Ingenieros Industriales, Universidad de Castilla La-Mancha, Avda. Camilo Jose Cela s/n, 13071 Ciudad Real (Spain)

    2010-05-15

    Hydrogen assisted diesel combustion was investigated on a DDC/VM Motori 2.5L, 4-cylinder, turbocharged, common rail, direct injection light-duty diesel engine, with a focus on exhaust emissions. Hydrogen was substituted for diesel fuel on an energy basis of 0%, 2.5%, 5%, 7.5%, 10% and 15% by aspiration of hydrogen into the engine's intake air. Four speed and load conditions were investigated (1800 rpm at 25% and 75% of maximum output and 3600 rpm at 25% and 75% of maximum output). A significant retarding of injection timing by the engine's electronic control unit (ECU) was observed during the increased aspiration of hydrogen. The retarding of injection timing resulted in significant NO{sub X} emission reductions, however, the same emission reductions were achieved without aspirated hydrogen by manually retarding the injection timing. Subsequently, hydrogen assisted diesel combustion was examined, with the pilot and main injection timings locked, to study the effects caused directly by hydrogen addition. Hydrogen assisted diesel combustion resulted in a modest increase of NO{sub X} emissions and a shift in NO/NO{sub 2} ratio in which NO emissions decreased and NO{sub 2} emissions increased, with NO{sub 2} becoming the dominant NO{sub X} component in some combustion modes. Computational fluid dynamics analysis (CFD) of the hydrogen assisted diesel combustion process captured this trend and reproduced the experimentally observed trends of hydrogen's effect on the composition of NO{sub X} for some operating conditions. A model that explicitly accounts for turbulence-chemistry interactions using a transported probability density function (PDF) method was better able to reproduce the experimental trends, compared to a model that ignores the influence of turbulent fluctuations on mean chemical production rates, although the importance of the fluctuations is not as strong as has been reported in some other recent modeling studies. The CFD results confirm

  19. Hydrogen Bond Basicity Prediction for Medicinal Chemistry Design.

    Science.gov (United States)

    Kenny, Peter W; Montanari, Carlos A; Prokopczyk, Igor M; Ribeiro, Jean F R; Sartori, Geraldo Rodrigues

    2016-05-12

    Hydrogen bonding is discussed in the context of medicinal chemistry design. Minimized molecular electrostatic potential (Vmin) is shown to be an effective predictor of hydrogen bond basicity (pKBHX), and predictive models are presented for a number of hydrogen bond acceptor types relevant to medicinal chemistry. The problems posed by the presence of nonequivalent hydrogen bond acceptor sites in molecular structures are addressed by using nonlinear regression to fit measured pKBHX to calculated Vmin. Predictions are made for hydrogen bond basicity of fluorine in situations where relevant experimental measurements are not available. It is shown how predicted pKBHX can be used to provide insight into the nature of bioisosterism and to profile heterocycles. Examples of pKBHX prediction for molecular structures with multiple, nonequivalent hydrogen bond acceptors are presented.

  20. Ion beam investigation of hydrogen implanted in magnesium

    International Nuclear Information System (INIS)

    Chami, A.-C.

    1977-01-01

    The diffusion mechanism for hydrogen implanted in magnesium was investigated by nuclear reaction analysis or channeling. The hydrogen introduced is then in the presence of radiation defects created by implantation. The H( 11 B,α) reaction used allowed the profiles of implanted hydrogen to be drawn. The Winterbon calculations derived from LSS theory (Lindhard, Scharff, Schiott) were used. LSS profiles folding and the excitation curve unfolding give very same results. An analysis of the profile of the defects and the evaluation of the total number of Frenkel pairs produced show that the defects are isolated when low energy light elements are implanted, and hydrogen interactions are effected through point defects. A channeling analysis shows that hydrogen occupies tetrahedral sites as far as the temperature remains lower that the migration temperature (about 100K). Beyonds this temperature, the hydrogen migrates and is trapped on motionless defects [fr

  1. Constrained optimization via simulation models for new product innovation

    Science.gov (United States)

    Pujowidianto, Nugroho A.

    2017-11-01

    We consider the problem of constrained optimization where the decision makers aim to optimize the primary performance measure while constraining the secondary performance measures. This paper provides a brief overview of stochastically constrained optimization via discrete event simulation. Most review papers tend to be methodology-based. This review attempts to be problem-based as decision makers may have already decided on the problem formulation. We consider constrained optimization models as there are usually constraints on secondary performance measures as trade-off in new product development. It starts by laying out different possible methods and the reasons using constrained optimization via simulation models. It is then followed by the review of different simulation optimization approach to address constrained optimization depending on the number of decision variables, the type of constraints, and the risk preferences of the decision makers in handling uncertainties.

  2. Hydrogen and fuel cells

    International Nuclear Information System (INIS)

    2006-06-01

    This road-map proposes by the Group Total aims to inform the public on the hydrogen and fuel cells. It presents the hydrogen technology from the production to the distribution and storage, the issues as motor fuel and fuel cells, the challenge for vehicles applications and the Total commitments in the domain. (A.L.B.)

  3. Hydrogen evolution reaction catalyst

    Science.gov (United States)

    Subbaraman, Ram; Stamenkovic, Vojislav; Markovic, Nenad; Tripkovic, Dusan

    2016-02-09

    Systems and methods for a hydrogen evolution reaction catalyst are provided. Electrode material includes a plurality of clusters. The electrode exhibits bifunctionality with respect to the hydrogen evolution reaction. The electrode with clusters exhibits improved performance with respect to the intrinsic material of the electrode absent the clusters.

  4. Dark hydrogen fermentations

    NARCIS (Netherlands)

    Vrije, de G.J.; Claassen, P.A.M.

    2003-01-01

    The production of hydrogen is a ubiquitous, natural phenomenon under anoxic or anaerobic conditions. A wide variety of bacteria, in swamps, sewage, hot springs, the rumen of cattle etc. is able to convert organic matter to hydrogen, CO2 and metabolites like acetic acid, lactate, ethanol and alanine.

  5. Hydrogen Storage Tank

    CERN Multimedia

    1983-01-01

    This huge stainless steel reservoir,placed near an end of the East Hall, was part of the safety equipment connected to the 2 Metre liquid hydrogen Bubble Chamber. It could store all the hydrogen in case of an emergency. The picture shows the start of its demolition.

  6. Thick film hydrogen sensor

    Science.gov (United States)

    Hoffheins, Barbara S.; Lauf, Robert J.

    1995-01-01

    A thick film hydrogen sensor element includes an essentially inert, electrically-insulating substrate having deposited thereon a thick film metallization forming at least two resistors. The metallization is a sintered composition of Pd and a sinterable binder such as glass frit. An essentially inert, electrically insulating, hydrogen impermeable passivation layer covers at least one of the resistors.

  7. Hydrogen pellet injection device

    International Nuclear Information System (INIS)

    Kanno, Masahiro.

    1992-01-01

    In a hydrogen pellet injection device, a nozzle block having a hydrogen gas supply channel is disposed at the inner side of a main cryogenic housing, and an electric resistor is attached to the block. Further, a nozzle block and a hydrogen gas introduction pipe are attached by way of a thermal insulating spacer. Electric current is supplied to the resistor to positively heat the nozzle block and melt remaining solid hydrogen in the hydrogen gas supply channel. Further, the effect of temperature elevation due to the resistor is prevented from reaching the side of the hydrogen gas introduction pipe by the thermal insulation spacer. That is, the temperature of the nozzle block is directly and positively elevated, to melt the solid hydrogen rapidly. Preparation operation from the injection of the hydrogen pellet to the next injection can be completed in a shorter period of time compared with a conventional case thereby enabling to make the test more efficient. Further, only the temperature of the nozzle block is elevated with no effect of temperature elevation due to the resistor to other components by the thermal insulation flange. (N.H.)

  8. Hydrogen from biomass

    NARCIS (Netherlands)

    Claassen, P.A.M.; Vrije, de G.J.

    2006-01-01

    Hydrogen is generally regarded as the energy carrier of the future. The development of a process for hydrogen production from biomass complies with the policy of the Dutch government to obtain more renewable energy from biomass. This report describes the progress of the BWP II project, phase 2 of

  9. DEVELOPMENT OF DOPED NANOPOROUS CARBONS FOR HYDROGEN STORAGE

    Energy Technology Data Exchange (ETDEWEB)

    Lueking, Angela D.; Li, Qixiu; Badding, John V.; Fonseca, Dania; Gutierrez, Humerto; Sakti, Apurba; Adu, Kofi; Schimmel, Michael

    2010-03-31

    Hydrogen storage materials based on the hydrogen spillover mechanism onto metal-doped nanoporous carbons are studied, in an effort to develop materials that store appreciable hydrogen at ambient temperatures and moderate pressures. We demonstrate that oxidation of the carbon surface can significantly increase the hydrogen uptake of these materials, primarily at low pressure. Trace water present in the system plays a role in the development of active sites, and may further be used as a strategy to increase uptake. Increased surface density of oxygen groups led to a significant enhancement of hydrogen spillover at pressures less than 100 milibar. At 300K, the hydrogen uptake was up to 1.1 wt. % at 100 mbar and increased to 1.4 wt. % at 20 bar. However, only 0.4 wt% of this was desorbable via a pressure reduction at room temperature, and the high lowpressure hydrogen uptake was found only when trace water was present during pretreatment. Although far from DOE hydrogen storage targets, storage at ambient temperature has significant practical advantages oner cryogenic physical adsorbents. The role of trace water in surface modification has significant implications for reproducibility in the field. High-pressure in situ characterization of ideal carbon surfaces in hydrogen suggests re-hybridization is not likely under conditions of practical interest. Advanced characterization is used to probe carbon-hydrogen-metal interactions in a number of systems and new carbon materials have been developed.

  10. Photosynthesis in Hydrogen-Dominated Atmospheres

    Science.gov (United States)

    Bains, William; Seager, Sara; Zsom, Andras

    2014-01-01

    The diversity of extrasolar planets discovered in the last decade shows that we should not be constrained to look for life in environments similar to early or present-day Earth. Super-Earth exoplanets are being discovered with increasing frequency, and some will be able to retain a stable, hydrogen-dominated atmosphere. We explore the possibilities for photosynthesis on a rocky planet with a thin H2-dominated atmosphere. If a rocky, H2-dominated planet harbors life, then that life is likely to convert atmospheric carbon into methane. Outgassing may also build an atmosphere in which methane is the principal carbon species. We describe the possible chemical routes for photosynthesis starting from methane and show that less energy and lower energy photons could drive CH4-based photosynthesis as compared with CO2-based photosynthesis. We find that a by-product biosignature gas is likely to be H2, which is not distinct from the hydrogen already present in the environment. Ammonia is a potential biosignature gas of hydrogenic photosynthesis that is unlikely to be generated abiologically. We suggest that the evolution of methane-based photosynthesis is at least as likely as the evolution of anoxygenic photosynthesis on Earth and may support the evolution of complex life. PMID:25411926

  11. Photosynthesis in Hydrogen-Dominated Atmospheres

    Directory of Open Access Journals (Sweden)

    William Bains

    2014-11-01

    Full Text Available The diversity of extrasolar planets discovered in the last decade shows that we should not be constrained to look for life in environments similar to early or present-day Earth. Super-Earth exoplanets are being discovered with increasing frequency, and some will be able to retain a stable, hydrogen-dominated atmosphere. We explore the possibilities for photosynthesis on a rocky planet with a thin H2-dominated atmosphere. If a rocky, H2-dominated planet harbors life, then that life is likely to convert atmospheric carbon into methane. Outgassing may also build an atmosphere in which methane is the principal carbon species. We describe the possible chemical routes for photosynthesis starting from methane and show that less energy and lower energy photons could drive CH4-based photosynthesis as compared with CO2-based photosynthesis. We find that a by-product biosignature gas is likely to be H2, which is not distinct from the hydrogen already present in the environment. Ammonia is a potential biosignature gas of hydrogenic photosynthesis that is unlikely to be generated abiologically. We suggest that the evolution of methane-based photosynthesis is at least as likely as the evolution of anoxygenic photosynthesis on Earth and may support the evolution of complex life.

  12. Measures for removing hydrogen

    International Nuclear Information System (INIS)

    Baukal, W.; Koehling, A.; Langer, G.; Poeschel, E.

    1984-01-01

    Basis for the investigation is a 1300-MW-PWR. The evolution of hydrogen was studied in design-basis and three hypothetical accident scenarios, the loss-of-coolant accident, the failure of emergency cooling system and core meltdown. It was shown that in the case of release rates of 4m 3 H 2 /h, the known post-accident hydrogen removal systems can be used and at medium rates up to 80 m 3 H 2 /h recombines of nuclear and non-nuclear industries are suitable under certain conditions. In the case of larger release rates it appears useful to apply a small recombiner of the type of the post-accident hydrogen removal system combined with an other hydrogen countermeasures. Recommendations are being made for the installation of an accident-proof hydrogen measuring system. (DG) [de

  13. Liquid hydrogen properties

    International Nuclear Information System (INIS)

    Choi, Jung Woon; Kim, Y. J.; Lee, K. H.; Kim, H. I.; Han, K. Y.; Park, J.H.

    2004-03-01

    The purpose of this report is to provide the input data, whose characteristic is thermodynamic and transport, in the form of equation for the thermo-hydraulic calculations using hydrogen as a working substance. The considered data in this report are particularly focused on the properties of para-hydrogen and of equilibrium-hydrogen around the working temperature range of the HANARO-CNS. The discussed properties of hydrogen are, in turn, the pressure of saturated vapors, the density, the heat of vaporization, thermal conductivity, viscosity, and heat capacity. Several equations to fit the above-mentioned experimental data allow calculating the various properties of liquid hydrogen with high accuracy at all considered temperatures

  14. Hydrogen production methods

    International Nuclear Information System (INIS)

    Hammerli, M.

    1982-07-01

    Old, present and new proceses for producing hydrogen are assessed critically. The emphasis throughout is placed on those processes which could be commercially viable before the turn of the century for large-scale hydrogen manufacture. Electrolysis of water is the only industrial process not dependent on fossil resources for large-scale hydrogen production and is likely to remain so for the next two or three decades. While many new processes, including those utilizing sunlight directly or indirectly, are presently not considered to be commercially viable for large-scale hydrogen production, research and development effort is needed to enhance our understanding of the nature of these processes. Water vapour electrolysis is compared with thermochemical processes: the former has the potential for displacing all other processes for producing hydrogen and oxygen from water

  15. Hydrogen storage using borohydrides

    International Nuclear Information System (INIS)

    Bernard BONNETOT; Laetitia LAVERSENNE

    2006-01-01

    The possibilities of hydrogen storage using borohydrides are presented and discussed specially in regard of the recoverable hydrogen amount and related to the recovering conditions. A rapid analysis of storage possibilities is proposed taking in account the two main ways for hydrogen evolution: the dehydrogenation obtained through thermal decomposition or the hydrolysis of solids or solutions. The recoverable hydrogen is related to the dehydrogenation conditions and the real hydrogen useful percentage is determined for each case of use. The high temperature required for dehydrogenation even when using catalyzed compounds lead to poor outlooks for this storage way. The hydrolysis conditions direct the chemical yield of the water consuming, and this must be related to the experimental conditions which rule the storage capacity of the 'fuel' derived from the borohydride. (authors)

  16. Reflected stochastic differential equation models for constrained animal movement

    Science.gov (United States)

    Hanks, Ephraim M.; Johnson, Devin S.; Hooten, Mevin B.

    2017-01-01

    Movement for many animal species is constrained in space by barriers such as rivers, shorelines, or impassable cliffs. We develop an approach for modeling animal movement constrained in space by considering a class of constrained stochastic processes, reflected stochastic differential equations. Our approach generalizes existing methods for modeling unconstrained animal movement. We present methods for simulation and inference based on augmenting the constrained movement path with a latent unconstrained path and illustrate this augmentation with a simulation example and an analysis of telemetry data from a Steller sea lion (Eumatopias jubatus) in southeast Alaska.

  17. An unusual mode of failure of a tripolar constrained acetabular liner: a case report.

    LENUS (Irish Health Repository)

    Banks, Louisa N

    2012-02-01

    Dislocation after primary total hip arthroplasty (THA) is the most commonly encountered complication and is unpleasant for both the patient and the surgeon. Constrained acetabular components can be used to treat or prevent instability after primary total hip arthroplasty. We present the case of a 42-year-old female with a BMI of 41. At 18 months post-primary THA the patient underwent further revision hip surgery after numerous (more than 20) dislocations. She had a tripolar Trident acetabular cup (Stryker-Howmedica-Osteonics, Rutherford, New Jersey) inserted. Shortly afterwards the unusual mode of failure of the constrained acetabular liner was noted from radiographs in that the inner liner had dissociated from the outer. The reinforcing ring remained intact and in place. We believe that the patient\\'s weight, combined with poor abductor musculature caused excessive demand on the device leading to failure at this interface when the patient flexed forward. Constrained acetabular components are useful implants to treat instability but have been shown to have up to 42% long-term failure rates with problems such as dissociated inserts, dissociated constraining rings and dissociated femoral rings being sited. Sometimes they may be the only option left in difficult cases such as illustrated here, but still unfortunately have the capacity to fail in unusual ways.

  18. An unusual mode of failure of a tripolar constrained acetabular liner: a case report.

    Science.gov (United States)

    Banks, Louisa N; McElwain, John P

    2010-04-01

    Dislocation after primary total hip arthroplasty (THA) is the most commonly encountered complication and is unpleasant for both the patient and the surgeon. Constrained acetabular components can be used to treat or prevent instability after primary total hip arthroplasty. We present the case of a 42-year-old female with a BMI of 41. At 18 months post-primary THA the patient underwent further revision hip surgery after numerous (more than 20) dislocations. She had a tripolar Trident acetabular cup (Stryker-Howmedica-Osteonics, Rutherford, New Jersey) inserted. Shortly afterwards the unusual mode of failure of the constrained acetabular liner was noted from radiographs in that the inner liner had dissociated from the outer. The reinforcing ring remained intact and in place. We believe that the patient's weight, combined with poor abductor musculature caused excessive demand on the device leading to failure at this interface when the patient flexed forward. Constrained acetabular components are useful implants to treat instability but have been shown to have up to 42% long-term failure rates with problems such as dissociated inserts, dissociated constraining rings and dissociated femoral rings being sited. Sometimes they may be the only option left in difficult cases such as illustrated here, but still unfortunately have the capacity to fail in unusual ways.

  19. Resource Management in Constrained Dynamic Situations

    Science.gov (United States)

    Seok, Jinwoo

    Resource management is considered in this dissertation for systems with limited resources, possibly combined with other system constraints, in unpredictably dynamic environments. Resources may represent fuel, power, capabilities, energy, and so on. Resource management is important for many practical systems; usually, resources are limited, and their use must be optimized. Furthermore, systems are often constrained, and constraints must be satisfied for safe operation. Simplistic resource management can result in poor use of resources and failure of the system. Furthermore, many real-world situations involve dynamic environments. Many traditional problems are formulated based on the assumptions of given probabilities or perfect knowledge of future events. However, in many cases, the future is completely unknown, and information on or probabilities about future events are not available. In other words, we operate in unpredictably dynamic situations. Thus, a method is needed to handle dynamic situations without knowledge of the future, but few formal methods have been developed to address them. Thus, the goal is to design resource management methods for constrained systems, with limited resources, in unpredictably dynamic environments. To this end, resource management is organized hierarchically into two levels: 1) planning, and 2) control. In the planning level, the set of tasks to be performed is scheduled based on limited resources to maximize resource usage in unpredictably dynamic environments. In the control level, the system controller is designed to follow the schedule by considering all the system constraints for safe and efficient operation. Consequently, this dissertation is mainly divided into two parts: 1) planning level design, based on finite state machines, and 2) control level methods, based on model predictive control. We define a recomposable restricted finite state machine to handle limited resource situations and unpredictably dynamic environments

  20. NMR studies of hydrogen diffusion in hydrogen uranyl phosphate tetrahydrate (HUP)

    International Nuclear Information System (INIS)

    Metcalfe, K.

    1988-01-01

    1 H NMR spin-lattice relaxation times, T 1 (Zeeman) and T 1p (rotating frame) and spin-spin relaxation times, T 2 , and 31 P NMR solid-echoes are reported for phase I and II of hydrogen uranyl phosphate tetrahydrate (HUP) at temperatures in the range 200-323 K. The spectral density functions extracted from the measured relaxation times for phases I and II are consistent with a 2D diffusion mechanism for hydrogen motion. 31 P second moments determined from the solid-echoes show that all the hydrogens diffuse rapidly in phase I, and that the hydrogen-bond site nearest to the phosphate oxygen is not occupied in phase II. The mechanism for diffusion in phase II is discussed. 30 refs.; 6 figs.; 2 tabs

  1. Sequential unconstrained minimization algorithms for constrained optimization

    International Nuclear Information System (INIS)

    Byrne, Charles

    2008-01-01

    The problem of minimizing a function f(x):R J → R, subject to constraints on the vector variable x, occurs frequently in inverse problems. Even without constraints, finding a minimizer of f(x) may require iterative methods. We consider here a general class of iterative algorithms that find a solution to the constrained minimization problem as the limit of a sequence of vectors, each solving an unconstrained minimization problem. Our sequential unconstrained minimization algorithm (SUMMA) is an iterative procedure for constrained minimization. At the kth step we minimize the function G k (x)=f(x)+g k (x), to obtain x k . The auxiliary functions g k (x):D subset of R J → R + are nonnegative on the set D, each x k is assumed to lie within D, and the objective is to minimize the continuous function f:R J → R over x in the set C = D-bar, the closure of D. We assume that such minimizers exist, and denote one such by x-circumflex. We assume that the functions g k (x) satisfy the inequalities 0≤g k (x)≤G k-1 (x)-G k-1 (x k-1 ), for k = 2, 3, .... Using this assumption, we show that the sequence {(x k )} is decreasing and converges to f(x-circumflex). If the restriction of f(x) to D has bounded level sets, which happens if x-circumflex is unique and f(x) is closed, proper and convex, then the sequence {x k } is bounded, and f(x*)=f(x-circumflex), for any cluster point x*. Therefore, if x-circumflex is unique, x* = x-circumflex and {x k } → x-circumflex. When x-circumflex is not unique, convergence can still be obtained, in particular cases. The SUMMA includes, as particular cases, the well-known barrier- and penalty-function methods, the simultaneous multiplicative algebraic reconstruction technique (SMART), the proximal minimization algorithm of Censor and Zenios, the entropic proximal methods of Teboulle, as well as certain cases of gradient descent and the Newton–Raphson method. The proof techniques used for SUMMA can be extended to obtain related results

  2. Detecting coevolving amino acid sites using Bayesian mutational mapping

    DEFF Research Database (Denmark)

    Dimmic, Matthew W.; Hubisz, Melissa J.; Bustamente, Carlos D.

    2005-01-01

    Motivation: The evolution of protein sequences is constrained by complex interactions between amino acid residues. Because harmful substitutions may be compensated for by other substitutions at neighboring sites, residues can coevolve. We describe a Bayesian phylogenetic approach to the detection...

  3. Salinity dependent hydrogen isotope fractionation in alkenones produced by coastal and open ocean haptophyte algae

    NARCIS (Netherlands)

    M'boule, D.; Chivall, D.; Sinke-Schoen, D.; Sinninghe Damsté, J.S.; Schouten, S.; van der Meer, M.T.J.

    2014-01-01

    The hydrogen isotope fractionation in alkenones produced by haptophyte algae is a promising new proxy for paleosalinity reconstructions. To constrain and further develop this proxy the coastal haptophyte Isochrysis galbana and the open ocean haptophyte alga Emiliania huxleyi were cultured at

  4. Systems analysis on the condition of market penetration for hydrogen technologies using linear programming model

    International Nuclear Information System (INIS)

    Kato, K.; Ihara, S.

    1993-01-01

    Hydrogen is expected to be an important energy carrier, especially in the frame of global warming problem solution. The purpose of this study is to examine the condition of market penetration of hydrogen technologies in reducing CO 2 emissions. A multi-time-period linear programming model (MARKAL, Market Allocation)) is used to explore technology options and cost for meeting the energy demands while reducing CO 2 emissions from energy systems. The results show that hydrogen technologies become economical when CO 2 emissions are stringently constrained. 9 figs., 2 refs

  5. Constrained Sypersymmetric Flipped SU (5) GUT Phenomenology

    Energy Technology Data Exchange (ETDEWEB)

    Ellis, John; /CERN /King' s Coll. London; Mustafayev, Azar; /Minnesota U., Theor. Phys. Inst.; Olive, Keith A.; /Minnesota U., Theor. Phys. Inst. /Minnesota U. /Stanford U., Phys. Dept. /SLAC

    2011-08-12

    We explore the phenomenology of the minimal supersymmetric flipped SU(5) GUT model (CFSU(5)), whose soft supersymmetry-breaking (SSB) mass parameters are constrained to be universal at some input scale, Min, above the GUT scale, M{sub GUT}. We analyze the parameter space of CFSU(5) assuming that the lightest supersymmetric particle (LSP) provides the cosmological cold dark matter, paying careful attention to the matching of parameters at the GUT scale. We first display some specific examples of the evolutions of the SSB parameters that exhibit some generic features. Specifically, we note that the relationship between the masses of the lightest neutralino {chi} and the lighter stau {tilde {tau}}{sub 1} is sensitive to M{sub in}, as is the relationship between m{sub {chi}} and the masses of the heavier Higgs bosons A,H. For these reasons, prominent features in generic (m{sub 1/2}, m{sub 0}) planes such as coannihilation strips and rapid-annihilation funnels are also sensitive to Min, as we illustrate for several cases with tan {beta} = 10 and 55. However, these features do not necessarily disappear at large Min, unlike the case in the minimal conventional SU(5) GUT. Our results are relatively insensitive to neutrino masses.

  6. Constrained supersymmetric flipped SU(5) GUT phenomenology

    Energy Technology Data Exchange (ETDEWEB)

    Ellis, John [CERN, TH Division, PH Department, Geneva 23 (Switzerland); King' s College London, Theoretical Physics and Cosmology Group, Department of Physics, London (United Kingdom); Mustafayev, Azar [University of Minnesota, William I. Fine Theoretical Physics Institute, Minneapolis, MN (United States); Olive, Keith A. [University of Minnesota, William I. Fine Theoretical Physics Institute, Minneapolis, MN (United States); Stanford University, Department of Physics and SLAC, Palo Alto, CA (United States)

    2011-07-15

    We explore the phenomenology of the minimal supersymmetric flipped SU(5) GUT model (CFSU(5)), whose soft supersymmetry-breaking (SSB) mass parameters are constrained to be universal at some input scale, M{sub in}, above the GUT scale, M{sub GUT}. We analyze the parameter space of CFSU(5) assuming that the lightest supersymmetric particle (LSP) provides the cosmological cold dark matter, paying careful attention to the matching of parameters at the GUT scale. We first display some specific examples of the evolutions of the SSB parameters that exhibit some generic features. Specifically, we note that the relationship between the masses of the lightest neutralino {chi} and the lighter stau {tau}{sub 1} is sensitive to M{sub in}, as is the relationship between m{sub {chi}} and the masses of the heavier Higgs bosons A,H. For these reasons, prominent features in generic (m{sub 1/2},m{sub 0}) planes such as coannihilation strips and rapid-annihilation funnels are also sensitive to M{sub in}, as we illustrate for several cases with tan {beta}=10 and 55. However, these features do not necessarily disappear at large M{sub in}, unlike the case in the minimal conventional SU(5) GUT. Our results are relatively insensitive to neutrino masses. (orig.)

  7. Joint Chance-Constrained Dynamic Programming

    Science.gov (United States)

    Ono, Masahiro; Kuwata, Yoshiaki; Balaram, J. Bob

    2012-01-01

    This paper presents a novel dynamic programming algorithm with a joint chance constraint, which explicitly bounds the risk of failure in order to maintain the state within a specified feasible region. A joint chance constraint cannot be handled by existing constrained dynamic programming approaches since their application is limited to constraints in the same form as the cost function, that is, an expectation over a sum of one-stage costs. We overcome this challenge by reformulating the joint chance constraint into a constraint on an expectation over a sum of indicator functions, which can be incorporated into the cost function by dualizing the optimization problem. As a result, the primal variables can be optimized by a standard dynamic programming, while the dual variable is optimized by a root-finding algorithm that converges exponentially. Error bounds on the primal and dual objective values are rigorously derived. We demonstrate the algorithm on a path planning problem, as well as an optimal control problem for Mars entry, descent and landing. The simulations are conducted using a real terrain data of Mars, with four million discrete states at each time step.

  8. Constraining the roughness degree of slip heterogeneity

    KAUST Repository

    Causse, Mathieu

    2010-05-07

    This article investigates different approaches for assessing the degree of roughness of the slip distribution of future earthquakes. First, we analyze a database of slip images extracted from a suite of 152 finite-source rupture models from 80 events (Mw = 4.1–8.9). This results in an empirical model defining the distribution of the slip spectrum corner wave numbers (kc) as a function of moment magnitude. To reduce the “epistemic” uncertainty, we select a single slip model per event and screen out poorly resolved models. The number of remaining models (30) is thus rather small. In addition, the robustness of the empirical model rests on a reliable estimation of kc by kinematic inversion methods. We address this issue by performing tests on synthetic data with a frequency domain inversion method. These tests reveal that due to smoothing constraints used to stabilize the inversion process, kc tends to be underestimated. We then develop an alternative approach: (1) we establish a proportionality relationship between kc and the peak ground acceleration (PGA), using a k−2 kinematic source model, and (2) we analyze the PGA distribution, which is believed to be better constrained than slip images. These two methods reveal that kc follows a lognormal distribution, with similar standard deviations for both methods.

  9. Technologies for a greenhouse-constrained society

    International Nuclear Information System (INIS)

    Kuliasha, M.A.; Zucker, A.; Ballew, K.J.

    1992-01-01

    This conference explored how three technologies might help society adjust to life in a greenhouse-constrained environment. Technology experts and policy makers from around the world met June 11--13, 1991, in Oak Ridge, Tennessee, to address questions about how energy efficiency, biomass, and nuclear technologies can mitigate the greenhouse effect and to explore energy production and use in countries in various stages of development. The conference was organized by Oak Ridge National Laboratory and sponsored by the US Department of Energy. Energy efficiency biomass, and nuclear energy are potential substitutes for fossil fuels that might help slow or even reverse the global warming changes that may result from mankind's thirst for energy. Many other conferences have questioned whether the greenhouse effect is real and what reductions in greenhouse gas emissions might be necessary to avoid serious ecological consequences; this conference studied how these reductions might actually be achieved. For these conference proceedings, individuals papers are processed separately for the Energy Data Base

  10. Constrained Supersymmetric Flipped SU(5) GUT Phenomenology

    CERN Document Server

    Ellis, John; Olive, Keith A

    2011-01-01

    We explore the phenomenology of the minimal supersymmetric flipped SU(5) GUT model (CFSU(5)), whose soft supersymmetry-breaking (SSB) mass parameters are constrained to be universal at some input scale, $M_{in}$, above the GUT scale, $M_{GUT}$. We analyze the parameter space of CFSU(5) assuming that the lightest supersymmetric particle (LSP) provides the cosmological cold dark matter, paying careful attention to the matching of parameters at the GUT scale. We first display some specific examples of the evolutions of the SSB parameters that exhibit some generic features. Specifically, we note that the relationship between the masses of the lightest neutralino and the lighter stau is sensitive to $M_{in}$, as is the relationship between the neutralino mass and the masses of the heavier Higgs bosons. For these reasons, prominent features in generic $(m_{1/2}, m_0)$ planes such as coannihilation strips and rapid-annihilation funnels are also sensitive to $M_{in}$, as we illustrate for several cases with tan(beta)...

  11. Constrained supersymmetric flipped SU(5) GUT phenomenology

    International Nuclear Information System (INIS)

    Ellis, John; Mustafayev, Azar; Olive, Keith A.

    2011-01-01

    We explore the phenomenology of the minimal supersymmetric flipped SU(5) GUT model (CFSU(5)), whose soft supersymmetry-breaking (SSB) mass parameters are constrained to be universal at some input scale, M in , above the GUT scale, M GUT . We analyze the parameter space of CFSU(5) assuming that the lightest supersymmetric particle (LSP) provides the cosmological cold dark matter, paying careful attention to the matching of parameters at the GUT scale. We first display some specific examples of the evolutions of the SSB parameters that exhibit some generic features. Specifically, we note that the relationship between the masses of the lightest neutralino χ and the lighter stau τ 1 is sensitive to M in , as is the relationship between m χ and the masses of the heavier Higgs bosons A,H. For these reasons, prominent features in generic (m 1/2 ,m 0 ) planes such as coannihilation strips and rapid-annihilation funnels are also sensitive to M in , as we illustrate for several cases with tan β=10 and 55. However, these features do not necessarily disappear at large M in , unlike the case in the minimal conventional SU(5) GUT. Our results are relatively insensitive to neutrino masses. (orig.)

  12. Scheduling Aircraft Landings under Constrained Position Shifting

    Science.gov (United States)

    Balakrishnan, Hamsa; Chandran, Bala

    2006-01-01

    Optimal scheduling of airport runway operations can play an important role in improving the safety and efficiency of the National Airspace System (NAS). Methods that compute the optimal landing sequence and landing times of aircraft must accommodate practical issues that affect the implementation of the schedule. One such practical consideration, known as Constrained Position Shifting (CPS), is the restriction that each aircraft must land within a pre-specified number of positions of its place in the First-Come-First-Served (FCFS) sequence. We consider the problem of scheduling landings of aircraft in a CPS environment in order to maximize runway throughput (minimize the completion time of the landing sequence), subject to operational constraints such as FAA-specified minimum inter-arrival spacing restrictions, precedence relationships among aircraft that arise either from airline preferences or air traffic control procedures that prevent overtaking, and time windows (representing possible control actions) during which each aircraft landing can occur. We present a Dynamic Programming-based approach that scales linearly in the number of aircraft, and describe our computational experience with a prototype implementation on realistic data for Denver International Airport.

  13. Should we still believe in constrained supersymmetry?

    International Nuclear Information System (INIS)

    Balazs, Csaba; Buckley, Andy; Carter, Daniel; Farmer, Benjamin; White, Martin

    2013-01-01

    We calculate partial Bayes factors to quantify how the feasibility of the constrained minimal supersymmetric standard model (CMSSM) has changed in the light of a series of observations. This is done in the Bayesian spirit where probability reflects a degree of belief in a proposition and Bayes' theorem tells us how to update it after acquiring new information. Our experimental baseline is the approximate knowledge that was available before LEP, and our comparison model is the Standard Model with a simple dark matter candidate. To quantify the amount by which experiments have altered our relative belief in the CMSSM since the baseline data we compute the partial Bayes factors that arise from learning in sequence the LEP Higgs constraints, the XENON100 dark matter constraints, the 2011 LHC supersymmetry search results, and the early 2012 LHC Higgs search results. We find that LEP and the LHC strongly shatter our trust in the CMSSM (with M 0 and M 1/2 below 2 TeV), reducing its posterior odds by approximately two orders of magnitude. This reduction is largely due to substantial Occam factors induced by the LEP and LHC Higgs searches. (orig.)

  14. Electricity in a Climate-Constrained World

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2012-07-01

    After experiencing a historic drop in 2009, electricity generation reached a record high in 2010, confirming the close linkage between economic growth and electricity usage. Unfortunately, CO2 emissions from electricity have also resumed their growth: Electricity remains the single-largest source of CO2 emissions from energy, with 11.7 billion tonnes of CO2 released in 2010. The imperative to 'decarbonise' electricity and improve end-use efficiency remains essential to the global fight against climate change. The IEA’s Electricity in a Climate-Constrained World provides an authoritative resource on progress to date in this area, including statistics related to CO2 and the electricity sector across ten regions of the world (supply, end-use and capacity additions). It also presents topical analyses on the challenge of rapidly curbing CO2 emissions from electricity. Looking at policy instruments, it focuses on emissions trading in China, using energy efficiency to manage electricity supply crises and combining policy instruments for effective CO2 reductions. On regulatory issues, it asks whether deregulation can deliver decarbonisation and assesses the role of state-owned enterprises in emerging economies. And from technology perspectives, it explores the rise of new end-uses, the role of electricity storage, biomass use in Brazil, and the potential of carbon capture and storage for ‘negative emissions’ electricity supply.

  15. Nucleosome breathing and remodeling constrain CRISPR-Cas9 function

    Science.gov (United States)

    Isaac, R Stefan; Jiang, Fuguo; Doudna, Jennifer A; Lim, Wendell A; Narlikar, Geeta J; Almeida, Ricardo

    2016-01-01

    The CRISPR-Cas9 bacterial surveillance system has become a versatile tool for genome editing and gene regulation in eukaryotic cells, yet how CRISPR-Cas9 contends with the barriers presented by eukaryotic chromatin is poorly understood. Here we investigate how the smallest unit of chromatin, a nucleosome, constrains the activity of the CRISPR-Cas9 system. We find that nucleosomes assembled on native DNA sequences are permissive to Cas9 action. However, the accessibility of nucleosomal DNA to Cas9 is variable over several orders of magnitude depending on dynamic properties of the DNA sequence and the distance of the PAM site from the nucleosome dyad. We further find that chromatin remodeling enzymes stimulate Cas9 activity on nucleosomal templates. Our findings imply that the spontaneous breathing of nucleosomal DNA together with the action of chromatin remodelers allow Cas9 to effectively act on chromatin in vivo. DOI: http://dx.doi.org/10.7554/eLife.13450.001 PMID:27130520

  16. Constrained variability of modeled T:ET ratio across biomes

    Science.gov (United States)

    Fatichi, Simone; Pappas, Christoforos

    2017-07-01

    A large variability (35-90%) in the ratio of transpiration to total evapotranspiration (referred here as T:ET) across biomes or even at the global scale has been documented by a number of studies carried out with different methodologies. Previous empirical results also suggest that T:ET does not covary with mean precipitation and has a positive dependence on leaf area index (LAI). Here we use a mechanistic ecohydrological model, with a refined process-based description of evaporation from the soil surface, to investigate the variability of T:ET across biomes. Numerical results reveal a more constrained range and higher mean of T:ET (70 ± 9%, mean ± standard deviation) when compared to observation-based estimates. T:ET is confirmed to be independent from mean precipitation, while it is found to be correlated with LAI seasonally but uncorrelated across multiple sites. Larger LAI increases evaporation from interception but diminishes ground evaporation with the two effects largely compensating each other. These results offer mechanistic model-based evidence to the ongoing research about the patterns of T:ET and the factors influencing its magnitude across biomes.

  17. The hydrogen highway

    International Nuclear Information System (INIS)

    Grigg, A.

    2004-01-01

    'Full text:' The Hydrogen Highway in British Columbia, Canada, is a coordinated, large-scale demonstration and deployment program aimed at accelerating the commercialization of hydrogen and fuel cell technologies and products. It will be a showcase for fuel cell vehicles, refuelling stations and stationary power systems leading up to the 2010 Olympic and Paralympic Winter Games in Whistler, BC. The Hydrogen Highway is designed to help address many of the challenges to commercialization identified in the Canadian Fuel Cell Commercialization Roadmap. The project will create an early adopter network of hydrogen and fuel cell microenvironments where technology developers and users can learn about the technical, economic, environmental and social impacts of products. The Hydrogen Highway will give the public and potential purchasers an opportunity to feel, touch and see the new technology, as well as provide the industry with a venue in which to develop industry standards and supply chains of materials and components. While demonstration and deployment programs are a recognized and necessary component in the process to commercialize hydrogen and fuel cell technologies, there is no handbook describing how it should be done. This paper will describe the history, objectives, project details and some of the challenges associated with establishing Canada's Hydrogen Highway. (author)

  18. The hydrogen highway

    Energy Technology Data Exchange (ETDEWEB)

    Grigg, A. [Fuel Cells Canada, Vancouver, British Columbia (Canada)

    2004-07-01

    'Full text:' The Hydrogen Highway in British Columbia, Canada, is a coordinated, large-scale demonstration and deployment program aimed at accelerating the commercialization of hydrogen and fuel cell technologies and products. It will be a showcase for fuel cell vehicles, refuelling stations and stationary power systems leading up to the 2010 Olympic and Paralympic Winter Games in Whistler, BC. The Hydrogen Highway is designed to help address many of the challenges to commercialization identified in the Canadian Fuel Cell Commercialization Roadmap. The project will create an early adopter network of hydrogen and fuel cell microenvironments where technology developers and users can learn about the technical, economic, environmental and social impacts of products. The Hydrogen Highway will give the public and potential purchasers an opportunity to feel, touch and see the new technology, as well as provide the industry with a venue in which to develop industry standards and supply chains of materials and components. While demonstration and deployment programs are a recognized and necessary component in the process to commercialize hydrogen and fuel cell technologies, there is no handbook describing how it should be done. This paper will describe the history, objectives, project details and some of the challenges associated with establishing Canada's Hydrogen Highway. (author)

  19. A green hydrogen economy

    Energy Technology Data Exchange (ETDEWEB)

    Clark, W.W. II [Clark Communications, Beverly Hills, CA (United States). Green Hydrogen Scientific Advisory Committee; Rifkin, J. [The Foundation on Economic Trends (United States)

    2006-11-15

    This paper is the result of over a dozen scholars and practitioners who strongly felt that a hydrogen economy and hence the future is closer than some American politicians and bureaucrats state. Moreover, when seen internationally, there is strong evidence, the most recent and obvious ones are the proliferation of hybrid vehicles, that for any nation-state to be energy independent it must seek a renewable or green hydrogen future in the near term. The State of California has once again taken the lead in this effort for both an energy-independent future and one linked strongly to the hydrogen economy. Then why a hydrogen economy in the first instance? The fact is that hydrogen most likely will not be used for refueling of vehicles in the near term. The number of vehicles to make hydrogen commercially viable will not be in the mass market by almost all estimates until 2010. However, it is less than a decade away. The time frame is NOT 30-40 years as some argue. The hydrogen economy needs trained people, new ventures and public-private partnerships now. The paper points out how the concerns of today, including higher costs and technologies under development, can be turned into opportunities for both the public and private sectors. It was not too long ago that the size of a mobile phone was that of a briefcase, and then almost 10 years ago, the size of a shoe box. Today, they are not only the size of a man's wallet but also often given away free to consumers who subscribe or contract for wireless services. While hydrogen may not follow this technological commercialization exactly, it certainly will be on a parallel path. International events and local or regional security dictate that the time for a hydrogen must be close at hand. (author)

  20. A green hydrogen economy

    International Nuclear Information System (INIS)

    Clark, Woodrow W.; Rifkin, Jeremy

    2006-01-01

    This paper is the result of over a dozen scholars and practitioners who strongly felt that a hydrogen economy and hence the future is closer than some American politicians and bureaucrats state. Moreover, when seen internationally, there is strong evidence, the most recent and obvious ones are the proliferation of hybrid vehicles, that for any nation-state to be energy independent it must seek a renewable or green hydrogen future in the near term. The State of California has once again taken the lead in this effort for both an energy-independent future and one linked strongly to the hydrogen economy. Then why a hydrogen economy in the first instance? The fact is that hydrogen most likely will not be used for refueling of vehicles in the near term. The number of vehicles to make hydrogen commercially viable will not be in the mass market by almost all estimates until 2010. However, it is less than a decade away. The time frame is NOT 30-40 years as some argue. The hydrogen economy needs trained people, new ventures and public-private partnerships now. The paper points out how the concerns of today, including higher costs and technologies under development, can be turned into opportunities for both the public and private sectors. It was not too long ago that the size of a mobile phone was that of a briefcase, and then almost 10 years ago, the size of a shoe box. Today, they are not only the size of a man's wallet but also often given away free to consumers who subscribe or contract for wireless services. While hydrogen may not follow this technological commercialization exactly, it certainly will be on a parallel path. International events and local or regional security dictate that the time for a hydrogen must be close at hand

  1. The Italian hydrogen programme

    International Nuclear Information System (INIS)

    Raffaele Vellone

    2001-01-01

    Hydrogen could become an important option in the new millennium. It provides the potential for a sustainable energy system as it can be used to meet most energy needs without harming the environment. In fact, hydrogen has the potential for contributing to the reduction of climate-changing emissions and other air pollutants as it exhibits clean combustion with no carbon or sulphur oxide emissions and very low nitrogen oxide emissions. Furthermore, it is capable of direct conversion to electricity in systems such as fuel cells without generating pollution. However, widespread use of hydrogen is not feasible today because of economic and technological barriers. In Italy, there is an ongoing national programme to facilitate the introduction of hydrogen as an energy carrier. This programme aims to promote, in an organic frame, a series of actions regarding the whole hydrogen cycle. It foresees the development of technologies in the areas of production, storage, transport and utilisation. Research addresses the development of technologies for separation and sequestration of CO 2 , The programme is shared by public organisations (research institutions and universities) and national industry (oil companies, electric and gas utilities and research institutions). Hydrogen can be used as a fuel, with significant advantages, both for electric energy generation/ co-generation (thermo-dynamic cycles and fuel cells) and transportation (internal combustion engine and fuel cells). One focus of research will be the development of fuel cell technologies. Fuel cells possess all necessary characteristics to be a key technology in a future economy based on hydrogen. During the initial phase of the project, hydrogen will be derived from fossil sources (natural gas), and in the second phase it will be generated from renewable electricity or nuclear energy. The presentation will provide a review of the hydrogen programme and highlight future goals. (author)

  2. Measuring hydrogen-isotope distribution profiles

    International Nuclear Information System (INIS)

    Poppe, C.H.

    1977-01-01

    A new nondestructive technique was developed for measuring the depth distribution of hydrogen isotopes absorbed or implanted near the surface of any material. The method allows real-time study of the inventory and diffusion of hydrogen, deuterium, and tritium. Briefly, the technique involves bombarding the surface with a monoenergetic beam of ions chosen for their ability to react with the hydrogen isotope in question and produce fast neutrons. The energy distribution of the neutrons is a sensitive indicator of the energy of the bombarding particles at the instant of reaction, and hence of the depth of the reaction sites below he surface of the material. A sensitivity of one part per million was obtained for tritium in copper. The technique is applicable to several energy-related materials problems. 5 figures

  3. Transient shielded liquid hydrogen containers

    International Nuclear Information System (INIS)

    Varghese, A.P.; Herring, R.H.

    1990-01-01

    The storage of hydrogen in the liquid phase has been limited in duration due to the thermal performance constraints of conventional Liquid Hydrogen containers available. Conventional Liquid Hydrogen containers lose hydrogen because of their relatively high heat leak and variations in usage pattern of hydrogen due to shutdowns. Local regulations also discourage venting of hydrogen. Long term storage of Liquid Hydrogen without product loss was usually accomplished using Liquid Nitrogen sacrificial shields. This paper reports on a new low heat leak container developed and patented that will extend the storage time of liquid hydrogen by five hundred percent. The principle of operation of the Transient Shields which makes the extraordinary performance of this container feasible is described in this paper. Also covered are the impact of this new container on present applications of hydrogen and the new opportunities afforded to Liquid hydrogen in the world hydrogen market

  4. Technical project of complex fast cycle heat treatment of hydrogenous coal preparation

    OpenAIRE

    Moiseev, V. A.; Andrienko, V. G.; Pileckij, V. G.; Urvancev, A. I.; Gvozdyakov, Dmitry Vasilievich; Gubin, Vladimir Evgenievich; Matveev, Aleksandr Sergeevich; Savostiyanova, Ludmila Viktorovna

    2015-01-01

    Problems of heat-treated milled hydrogenous coal preparation site creation in leading fast cycle heat treatment complex were considered. Conditions for effective use of electrostatic methods of heat-treated milled hydrogenous coal preparation were set. Technical project of heat treatment of milled hydrogenous coal preparation site was developed including coupling of working equipment complex on fast heat treatment and experimental samples of equipment being designed for manufacturing. It was ...

  5. Magnesium for Hydrogen Storage

    DEFF Research Database (Denmark)

    Vigeholm, B.; Kjøller, John; Larsen, Bent

    1980-01-01

    The reaction of hydrogen with commercially pure magnesium powder (above 99.7%) was investigated in the temperature range 250–400 °C. Hydrogen is readily sorbed above the dissociation pressure. During the initial exposure the magnesium powder sorbs hydrogen slowly below 400 °C but during the second...... that the particles do not disintegrate is explained by a sintering process at the working temperatures. Exposure to air does not impair the sorption ability; on the contrary, it appears that surface oxidation plays an important role in the reaction. Some handling problems, e.g. the reaction of the hydride with water...

  6. Photobiological hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Seibert, M; Lien, S; Weaver, P F

    1979-01-01

    Hydrogen production by phototrophic organisms, which has been known since the 1930's, occurs at the expense of light energy and electron-donating substrates. Three classes of organisms, namely, photosynthetic bacteria, cyanobacteria, and algae carry out this function. The primary hydrogen-producing enzyme systems, hydrogenase and nitrogenase, will be discussed along with the manner in which they couple to light-driven electron transport. In addition, the feasibility of using in vivo and in vitro photobiological hydrogen producing systems in future solar energy conversion applications will be examined.

  7. Photobiological hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Seibert, M.; Lien, S.; Weaver, P.F.

    1979-01-01

    Hydrogen production by phototrophic organisms, which has been known since the 1930's, occurs at the expense of light energy and electron-donating substrates. Three classes of organisms, namely, photosynthetic bacteria, cyanobacteria, and algae carry out this function. The primary hydrogen-producing enzyme systems, hydrogenase and nitrogenase, will be discussed along with the manner in which they couple to light-driven electron transport. In addition, the feasibility of using in vivo and in vitro photobiological hydrogen producing systems in future solar energy conversion applications will be examined.

  8. Chromatographic hydrogen isotope separation

    International Nuclear Information System (INIS)

    Aldridge, F.T.

    1983-01-01

    Intermetallic compounds with the CaCu5 type of crystal structure, particularly LaNiCo and CaNi5, exhibit high separation factors and fast equilibrium times and therefore are useful for packing a chromatographic hydrogen isotope separation column. The addition of an inert metal to dilute the hydride improves performance of the column. A large scale multi-stage chromatographic separation process run as a secondary process off a hydrogen feedstream from an industrial plant which uses large volumes of hydrogen can produce large quantities of heavy water at an effective cost for use in heavy water reactors

  9. National hydrogen energy roadmap

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2002-11-01

    This report was unveiled by Energy Secretary Spencer Abraham in November 2002 and provides a blueprint for the coordinated, long-term, public and private efforts required for hydrogen energy development. Based on the results of the government-industry National Hydrogen Energy Roadmap Workshop, held in Washington, DC on April 2-3, 2002, it displays the development of a roadmap for America's clean energy future and outlines the key barriers and needs to achieve the hydrogen vision goals defined in

  10. Chromatographic hydrogen isotope separation

    International Nuclear Information System (INIS)

    Aldridge, F.T.

    1981-01-01

    Intermetallic compounds with the CaCu5 type of crystal structure , particularly LaNiCo and CaNi5, exhibit high separation factors and fast equilibrium times and therefore are useful for packing a chromatographic hydrogen isotope separation colum. The addition of an inert metal to dilute the hydride improves performance of the column. A large scale mutli-stage chromatographic separation process run as a secondary process off a hydrogen feedstream from an industrial plant which uses large volumes of hydrogen can produce large quantities of heavy water at an effective cost for use in heavy water reactors

  11. Uncertainties in hydrogen combustion

    International Nuclear Information System (INIS)

    Stamps, D.W.; Wong, C.C.; Nelson, L.S.

    1988-01-01

    Three important areas of hydrogen combustion with uncertainties are identified: high-temperature combustion, flame acceleration and deflagration-to-detonation transition, and aerosol resuspension during hydrogen combustion. The uncertainties associated with high-temperature combustion may affect at least three different accident scenarios: the in-cavity oxidation of combustible gases produced by core-concrete interactions, the direct containment heating hydrogen problem, and the possibility of local detonations. How these uncertainties may affect the sequence of various accident scenarios is discussed and recommendations are made to reduce these uncertainties. 40 references

  12. Chemochromic Hydrogen Leak Detectors

    Science.gov (United States)

    Roberson, Luke; Captain, Janine; Williams, Martha; Smith, Trent; Tate, LaNetra; Raissi, Ali; Mohajeri, Nahid; Muradov, Nazim; Bokerman, Gary

    2009-01-01

    At NASA, hydrogen safety is a key concern for space shuttle processing. Leaks of any level must be quickly recognized and addressed due to hydrogen s lower explosion limit. Chemo - chromic devices have been developed to detect hydrogen gas in several embodiments. Because hydrogen is odorless and colorless and poses an explosion hazard, there is an emerging need for sensors to quickly and accurately detect low levels of leaking hydrogen in fuel cells and other advanced energy- generating systems in which hydrogen is used as fuel. The device incorporates a chemo - chromic pigment into a base polymer. The article can reversibly or irreversibly change color upon exposure to hydrogen. The irreversible pigment changes color from a light beige to a dark gray. The sensitivity of the pigment can be tailored to its application by altering its exposure to gas through the incorporation of one or more additives or polymer matrix. Furthermore, through the incorporation of insulating additives, the chemochromic sensor can operate at cryogenic temperatures as low as 78 K. A chemochromic detector of this type can be manufactured into any feasible polymer part including injection molded plastic parts, fiber-spun textiles, or extruded tapes. The detectors are simple, inexpensive, portable, and do not require an external power source. The chemochromic detectors were installed and removed easily at the KSC launch pad without need for special expertise. These detectors may require an external monitor such as the human eye, camera, or electronic detector; however, they could be left in place, unmonitored, and examined later for color change to determine whether there had been exposure to hydrogen. In one type of envisioned application, chemochromic detectors would be fabricated as outer layers (e.g., casings or coatings) on high-pressure hydrogen storage tanks and other components of hydrogen-handling systems to provide visible indications of hydrogen leaks caused by fatigue failures or

  13. Biological hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Benemann, J.R. [Univ. of California, Berkeley, CA (United States)

    1995-11-01

    Biological hydrogen production can be accomplished by either thermochemical (gasification) conversion of woody biomass and agricultural residues or by microbiological processes that yield hydrogen gas from organic wastes or water. Biomass gasification is a well established technology; however, the synthesis gas produced, a mixture of CO and H{sub 2}, requires a shift reaction to convert the CO to H{sub 2}. Microbiological processes can carry out this reaction more efficiently than conventional catalysts, and may be more appropriate for the relatively small-scale of biomass gasification processes. Development of a microbial shift reaction may be a near-term practical application of microbial hydrogen production.

  14. Fire Protection Engineering Design Brief Template. Hydrogen Refueling Station.

    Energy Technology Data Exchange (ETDEWEB)

    LaFleur, Angela Christine [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Muna, Alice Baca [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Groth, Katrina M. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-08-01

    Building a hydrogen infrastructure system is critical to supporting the development of alternate- fuel vehicles. This report provides a methodology for implementing a performance-based design of an outdoor hydrogen refueling station that does not meet specific prescriptive requirements in NFPA 2, The Hydrogen Technologies Code . Performance-based designs are a code-compliant alternative to meeting prescriptive requirements. Compliance is demonstrated by comparing a prescriptive-based fueling station design with a performance-based design approach using Quantitative Risk Assessment (QRA) methods and hydrogen risk assessment tools. This template utilizes the Sandia-developed QRA tool, Hydrogen Risk Analysis Models (HyRAM), which combines reduced-order deterministic models that characterize hydrogen release and flame behavior with probabilistic risk models to quantify risk values. Each project is unique and this template is not intended to account for site-specific characteristics. Instead, example content and a methodology are provided for a representative hydrogen refueling site which can be built upon for new hydrogen applications.

  15. Production of hydrogen from organic waste via hydrogen sulfide

    International Nuclear Information System (INIS)

    McMahon, M.; Davis, B.R.; Roy, A.; Daugulis, A.

    2007-01-01

    In this paper an integrated process is proposed that converts organic waste to hydrogen via hydrogen sulphide. The designed bioreactor has achieved high volumetric productivities comparable to methanogenic bioreactors. Proposed process has advantages of bio-methane production and is more resilient to process upset. Thermochemical conversion of hydrogen sulphide to hydrogen is exothermic and also requires smaller plant infrastructure

  16. A discretized algorithm for the solution of a constrained, continuous ...

    African Journals Online (AJOL)

    A discretized algorithm for the solution of a constrained, continuous quadratic control problem. ... The results obtained show that the Discretized constrained algorithm (DCA) is much more accurate and more efficient than some of these techniques, particularly the FSA. Journal of the Nigerian Association of Mathematical ...

  17. I/O-Efficient Construction of Constrained Delaunay Triangulations

    DEFF Research Database (Denmark)

    Agarwal, Pankaj Kumar; Arge, Lars; Yi, Ke

    2005-01-01

    In this paper, we designed and implemented an I/O-efficient algorithm for constructing constrained Delaunay triangulations. If the number of constraining segments is smaller than the memory size, our algorithm runs in expected O( N B logM/B NB ) I/Os for triangulating N points in the plane, where...

  18. Theoretical study of hydrogen storage in metal hydrides.

    Science.gov (United States)

    Oliveira, Alyson C M; Pavão, A C

    2018-05-04

    Adsorption, absorption and desorption energies and other properties of hydrogen storage in palladium and in the metal hydrides AlH 3 , MgH 2 , Mg(BH 4 ) 2 , Mg(BH 4 )(NH 2 ) and LiNH 2 were analyzed. The DFT calculations on cluster models show that, at a low concentration, the hydrogen atom remains adsorbed in a stable state near the palladium surface. By increasing the hydrogen concentration, the tetrahedral and the octahedral sites are sequentially occupied. In the α phase the tetrahedral site releases hydrogen more easily than at the octahedral sites, but the opposite occurs in the β phase. Among the hydrides, Mg(BH 4 ) 2 shows the highest values for both absorption and desorption energies. The absorption energy of LiNH 2 is higher than that of the palladium, but its desorption energy is too high, a recurrent problem of the materials that have been considered for hydrogen storage. The release of hydrogen, however, can be favored by using transition metals in the material structure, as demonstrated here by doping MgH 2 with 3d and 4d-transition metals to reduce the hydrogen atomic charge and the desorption energy.

  19. Regional Responses to Constrained Water Availability

    Science.gov (United States)

    Cui, Y.; Calvin, K. V.; Hejazi, M. I.; Clarke, L.; Kim, S. H.; Patel, P.

    2017-12-01

    There have been many concerns about water as a constraint to agricultural production, electricity generation, and many other human activities in the coming decades. Nevertheless, how different countries/economies would respond to such constraints has not been explored. Here, we examine the responding mechanism of binding water availability constraints at the water basin level and across a wide range of socioeconomic, climate and energy technology scenarios. Specifically, we look at the change in water withdrawals between energy, land-use and other sectors within an integrated framework, by using the Global Change Assessment Model (GCAM) that also endogenizes water use and allocation decisions based on costs. We find that, when water is taken into account as part of the production decision-making, countries/basins in general fall into three different categories, depending on the change of water withdrawals and water re-allocation between sectors. First, water is not a constraining factor for most of the basins. Second, advancements in water-saving technologies of the electricity generation cooling systems are sufficient of reducing water withdrawals to meet binding water availability constraints, such as in China and the EU-15. Third, water-saving in the electricity sector alone is not sufficient and thus cannot make up the lowered water availability from the binding case; for example, many basins in Pakistan, Middle East and India have to largely reduce irrigated water withdrawals by either switching to rain-fed agriculture or reducing production. The dominant responding strategy for individual countries/basins is quite robust across the range of alternate scenarios that we test. The relative size of water withdrawals between energy and agriculture sectors is one of the most important factors that affect the dominant mechanism.

  20. Constraining Cosmic Evolution of Type Ia Supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Foley, Ryan J.; Filippenko, Alexei V.; Aguilera, C.; Becker, A.C.; Blondin, S.; Challis, P.; Clocchiatti, A.; Covarrubias, R.; Davis, T.M.; Garnavich, P.M.; Jha, S.; Kirshner, R.P.; Krisciunas, K.; Leibundgut, B.; Li, W.; Matheson, T.; Miceli, A.; Miknaitis, G.; Pignata, G.; Rest, A.; Riess, A.G.; /UC, Berkeley, Astron. Dept. /Cerro-Tololo InterAmerican Obs. /Washington U., Seattle, Astron. Dept. /Harvard-Smithsonian Ctr. Astrophys. /Chile U., Catolica /Bohr Inst. /Notre Dame U. /KIPAC, Menlo Park /Texas A-M /European Southern Observ. /NOAO, Tucson /Fermilab /Chile U., Santiago /Harvard U., Phys. Dept. /Baltimore, Space Telescope Sci. /Johns Hopkins U. /Res. Sch. Astron. Astrophys., Weston Creek /Stockholm U. /Hawaii U. /Illinois U., Urbana, Astron. Dept.

    2008-02-13

    We present the first large-scale effort of creating composite spectra of high-redshift type Ia supernovae (SNe Ia) and comparing them to low-redshift counterparts. Through the ESSENCE project, we have obtained 107 spectra of 88 high-redshift SNe Ia with excellent light-curve information. In addition, we have obtained 397 spectra of low-redshift SNe through a multiple-decade effort at Lick and Keck Observatories, and we have used 45 ultraviolet spectra obtained by HST/IUE. The low-redshift spectra act as a control sample when comparing to the ESSENCE spectra. In all instances, the ESSENCE and Lick composite spectra appear very similar. The addition of galaxy light to the Lick composite spectra allows a nearly perfect match of the overall spectral-energy distribution with the ESSENCE composite spectra, indicating that the high-redshift SNe are more contaminated with host-galaxy light than their low-redshift counterparts. This is caused by observing objects at all redshifts with similar slit widths, which corresponds to different projected distances. After correcting for the galaxy-light contamination, subtle differences in the spectra remain. We have estimated the systematic errors when using current spectral templates for K-corrections to be {approx}0.02 mag. The variance in the composite spectra give an estimate of the intrinsic variance in low-redshift maximum-light SN spectra of {approx}3% in the optical and growing toward the ultraviolet. The difference between the maximum-light low and high-redshift spectra constrain SN evolution between our samples to be < 10% in the rest-frame optical.

  1. Laterally constrained inversion for CSAMT data interpretation

    Science.gov (United States)

    Wang, Ruo; Yin, Changchun; Wang, Miaoyue; Di, Qingyun

    2015-10-01

    Laterally constrained inversion (LCI) has been successfully applied to the inversion of dc resistivity, TEM and airborne EM data. However, it hasn't been yet applied to the interpretation of controlled-source audio-frequency magnetotelluric (CSAMT) data. In this paper, we apply the LCI method for CSAMT data inversion by preconditioning the Jacobian matrix. We apply a weighting matrix to Jacobian to balance the sensitivity of model parameters, so that the resolution with respect to different model parameters becomes more uniform. Numerical experiments confirm that this can improve the convergence of the inversion. We first invert a synthetic dataset with and without noise to investigate the effect of LCI applications to CSAMT data, for the noise free data, the results show that the LCI method can recover the true model better compared to the traditional single-station inversion; and for the noisy data, the true model is recovered even with a noise level of 8%, indicating that LCI inversions are to some extent noise insensitive. Then, we re-invert two CSAMT datasets collected respectively in a watershed and a coal mine area in Northern China and compare our results with those from previous inversions. The comparison with the previous inversion in a coal mine shows that LCI method delivers smoother layer interfaces that well correlate to seismic data, while comparison with a global searching algorithm of simulated annealing (SA) in a watershed shows that though both methods deliver very similar good results, however, LCI algorithm presented in this paper runs much faster. The inversion results for the coal mine CSAMT survey show that a conductive water-bearing zone that was not revealed by the previous inversions has been identified by the LCI. This further demonstrates that the method presented in this paper works for CSAMT data inversion.

  2. The cost-constrained traveling salesman problem

    Energy Technology Data Exchange (ETDEWEB)

    Sokkappa, P.R.

    1990-10-01

    The Cost-Constrained Traveling Salesman Problem (CCTSP) is a variant of the well-known Traveling Salesman Problem (TSP). In the TSP, the goal is to find a tour of a given set of cities such that the total cost of the tour is minimized. In the CCTSP, each city is given a value, and a fixed cost-constraint is specified. The objective is to find a subtour of the cities that achieves maximum value without exceeding the cost-constraint. Thus, unlike the TSP, the CCTSP requires both selection and sequencing. As a consequence, most results for the TSP cannot be extended to the CCTSP. We show that the CCTSP is NP-hard and that no K-approximation algorithm or fully polynomial approximation scheme exists, unless P = NP. We also show that several special cases are polynomially solvable. Algorithms for the CCTSP, which outperform previous methods, are developed in three areas: upper bounding methods, exact algorithms, and heuristics. We found that a bounding strategy based on the knapsack problem performs better, both in speed and in the quality of the bounds, than methods based on the assignment problem. Likewise, we found that a branch-and-bound approach using the knapsack bound was superior to a method based on a common branch-and-bound method for the TSP. In our study of heuristic algorithms, we found that, when selecting modes for inclusion in the subtour, it is important to consider the neighborhood'' of the nodes. A node with low value that brings the subtour near many other nodes may be more desirable than an isolated node of high value. We found two types of repetition to be desirable: repetitions based on randomization in the subtour buildings process, and repetitions encouraging the inclusion of different subsets of the nodes. By varying the number and type of repetitions, we can adjust the computation time required by our method to obtain algorithms that outperform previous methods.

  3. Hydrogen by water electrolysis

    International Nuclear Information System (INIS)

    Anon.

    1995-01-01

    Hydrogen production by water electrolysis (aqueous solution of potassium hydroxide) is shortly presented with theoretical aspects (thermodynamics and kinetics), and components of the electrolytic cell (structural materials, cathodes, anodes, diaphragms), and examples of industrial processes. (A.B.). 4 figs

  4. Nanomaterials for Hydrogen Storage

    Indian Academy of Sciences (India)

    concepts transferred from the gaseous state. Separation of a ... molecular mass to that calculated by colligative methods. It is important in ... namics is vital in the design and optimization of the materials for hydrogen ... vehicular applications.

  5. Hydrogen storage compositions

    Science.gov (United States)

    Li, Wen; Vajo, John J.; Cumberland, Robert W.; Liu, Ping

    2011-04-19

    Compositions for hydrogen storage and methods of making such compositions employ an alloy that exhibits reversible formation/deformation of BH.sub.4.sup.- anions. The composition includes a ternary alloy including magnesium, boron and a metal and a metal hydride. The ternary alloy and the metal hydride are present in an amount sufficient to render the composition capable of hydrogen storage. The molar ratio of the metal to magnesium and boron in the alloy is such that the alloy exhibits reversible formation/deformation of BH.sub.4.sup.- anions. The hydrogen storage composition is prepared by combining magnesium, boron and a metal to prepare a ternary alloy and combining the ternary alloy with a metal hydride to form the hydrogen storage composition.

  6. Hydrogen Fire Spectroscopy Issues

    Data.gov (United States)

    National Aeronautics and Space Administration — The detection of hydrogen fires is important to the aerospace community. The National Aeronautics and Space Administration (NASA) has devoted significant effort to...

  7. Canadian hydrogen strategies

    International Nuclear Information System (INIS)

    Fairlie, M.; Scepanovic, V.; Dube, J.; Hammerli, M.; Taylor, J.

    2004-01-01

    'Full text:' In May of 2004, industry and government embarked on a process to create a strategic plan for development of the 'hydrogen economy' in Canada. The process was undertaken to determine how the development and commercialization of hydrogen technologies could be accelerated to yield a 'visible' reduction in greenhouse gases within the timeframe of Kyoto, while establishing a direction that addresses the necessity of far greater reductions in the future. Starting with a meeting of twenty seven experts drawn from the hydrogen technology, energy and transportation industries and government, a vision and mission for the planning process was developed. Two months later a second meeting was held with a broader group of stakeholders to develop hydrogen transition strategies that could achieve the mission, and from identifying the barriers and enablers for these strategies, an action plan was created. This paper reviews the results from this consultation process and discusses next steps. (author)

  8. Hydrogen in titanium alloys

    International Nuclear Information System (INIS)

    Wille, G.W.; Davis, J.W.

    1981-04-01

    The titanium alloys that offer properties worthy of consideration for fusion reactors are Ti-6Al-4V, Ti-6Al-2Sn-4Zr-2Mo-Si (Ti-6242S) and Ti-5Al-6Sn-2Zr-1Mo-Si (Ti-5621S). The Ti-6242S and Ti-5621S are being considered because of their high creep resistance at elevated temperatures of 500 0 C. Also, irradiation tests on these alloys have shown irradiation creep properties comparable to 20% cold worked 316 stainless steel. These alloys would be susceptible to slow strain rate embrittlement if sufficient hydrogen concentrations are obtained. Concentrations greater than 250 to 500 wppm hydrogen and temperatures lower than 100 to 150 0 C are approximate threshold conditions for detrimental effects on tensile properties. Indications are that at the elevated temperature - low hydrogen pressure conditions of the reactors, there would be negligible hydrogen embrittlement

  9. Hydrogen environment embrittlement

    International Nuclear Information System (INIS)

    Donovan, J.A.

    1975-01-01

    Exposure of many metals to gaseous hydrogen causes losses in elongation, reduction of area, and fracture toughness, and causes increases in slow crack growth rate or fatigue life compared with values obtained in air or vacuum. Hydrogen pressure, temperature, and purity significantly influence deleterious effects. The strength and structural characteristics of the metal influence the degradation of its properties by hydrogen. Several theories have been proposed to explain the loss of properties in hydrogen, but none has gained wide acceptance. The embrittlement mechanism and the role of diffusion are, therefore, open questions and need more quantitative experimental data both to test the proposed theories and to allow the development of realistic preventive measures. (U.S.)

  10. Hydrogen perspectives in Japan

    International Nuclear Information System (INIS)

    Furutani, H.

    2000-01-01

    Hydrogen energy is considered to present a potential effective options for achieving the greenhouse gas minimization. The MITI (Ministry of International Trade and Industry) of Japanese Government is promoting the WE-NET (World Energy Network System) Project which envisions (1) construction of a global energy network for effective supply, transportation, storage and utilization of renewable energy using hydrogen as an energy carrier as a long-term options of sustainable energy economy, and (2) promotion of market entry of hydrogen energy in near and/or mid future even before construction of a WE-NET system. In this paper, I would like to report how far the hydrogen energy technology development addressed under Phase I has progressed, and describe the outline of the Phase II Plan. (author)

  11. Hydrogen permeability through metals

    International Nuclear Information System (INIS)

    Pisarev, A.A.; Tsvetkov, I.V.; Marenkov, E.D.; Yarko, S.S.

    2011-01-01

    The mechanisms of hydrogen permeability through one-layer and multi-layer membranes are considered. The effect of surface roughness, crystal defects, cracks and pores is described. Mathematical description of the processes is given [ru

  12. Photoelectrochemical hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Rocheleau, R.E.; Miller, E.; Misra, A. [Univ. of Hawaii, Honolulu, HI (United States)

    1996-10-01

    The large-scale production of hydrogen utilizing energy provided by a renewable source to split water is one of the most ambitious long-term goals of the U.S. Department of Energy`s Hydrogen Program. One promising option to meet this goal is direct photoelectrolysis in which light absorbed by semiconductor-based photoelectrodes produces electrical power internally to split water into hydrogen and oxygen. Under this program, direct solar-to-chemical conversion efficiencies as high as 7.8 % have been demonstrated using low-cost, amorphous-silicon-based photoelectrodes. Detailed loss analysis models indicate that solar-to-chemical conversion greater than 10% can be achieved with amorphous-silicon-based structures optimized for hydrogen production. In this report, the authors describe the continuing progress in the development of thin-film catalytic/protective coatings, results of outdoor testing, and efforts to develop high efficiency, stable prototype systems.

  13. Hydrogenizing oils, asphalts, etc

    Energy Technology Data Exchange (ETDEWEB)

    1925-03-14

    The hydrogenation of carbonaceous solids in presence of combined sulfur, e.g., sulfides as described in the parent specification is applied to the treatment of rock oils, shale oils, resins, ozokerite, asphalt, and the like, or fractions, residues, or acid sludge or other conversion products thereof, alone or mixed. Preferably the hydrogen or other reducing gas is in excess and under pressure, and is either circuited or led through a series of treatment vessels, hydrogen being added for that used. In an example, residues from American crude oil are passed continuously with hydrogen at 200 atmospheres and 450 to 500/sup 0/C over pressed precipitated cobalt sulfide, the issuing gases being cooled to condense the light oil produced.

  14. Constrained dansyl derivatives reveal bacterial specificity of highly conserved thymidylate synthases.

    Science.gov (United States)

    Calò, Sanuele; Tondi, Donatella; Ferrari, Stefania; Venturelli, Alberto; Ghelli, Stefano; Costi, Maria Paola

    2008-03-25

    The elucidation of the structural/functional specificities of highly conserved enzymes remains a challenging area of investigation, and enzymes involved in cellular replication are important targets for functional studies and drug discovery. Thymidylate synthase (TS, ThyA) governs the synthesis of thymidylate for use in DNA synthesis. The present study focused on Lactobacillus casei TS (LcTS) and Escherichia coli TS (EcTS), which exhibit 50 % sequence identity and strong folding similarity. We have successfully designed and validated a chemical model in which linear, but not constrained, dansyl derivatives specifically complement the LcTS active site. Conversely, chemically constrained dansyl derivatives showed up to 1000-fold improved affinity for EcTS relative to the inhibitory activity of linear derivatives. This study demonstrates that the accurate design of small ligands can uncover functional features of highly conserved enzymes.

  15. Novel, Ceramic Membrane System For Hydrogen Separation

    Energy Technology Data Exchange (ETDEWEB)

    Elangovan, S.

    2012-12-31

    Separation of hydrogen from coal gas represents one of the most promising ways to produce alternative sources of fuel. Ceramatec, teamed with CoorsTek and Sandia National Laboratories has developed materials technology for a pressure driven, high temperature proton-electron mixed conducting membrane system to remove hydrogen from the syngas. This system separates high purity hydrogen and isolates high pressure CO{sub 2} as the retentate, which is amenable to low cost capture and transport to storage sites. The team demonstrated a highly efficient, pressure-driven hydrogen separation membrane to generate high purity hydrogen from syngas using a novel ceramic-ceramic composite membrane. Recognizing the benefits and limitations of present membrane systems, the all-ceramic system has been developed to address the key technical challenges related to materials performance under actual operating conditions, while retaining the advantages of thermal and process compatibility offered by the ceramic membranes. The feasibility of the concept has already been demonstrated at Ceramatec. This project developed advanced materials composition for potential integration with water gas shift rectors to maximize the hydrogenproduction.

  16. Concentration dependent hydrogen diffusion in tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Ahlgren, T., E-mail: tommy.ahlgren@helsinki.fi; Bukonte, L.

    2016-10-15

    The diffusion of hydrogen in tungsten is studied as a function of temperature, hydrogen concentration and pressure using Molecular Dynamics technique. A new analysis method to determine diffusion coefficients that accounts for the random oscillation of atoms around the equilibrium position is presented. The results indicate that the hydrogen migration barrier of 0.25 eV should be used instead of the presently recommended value of 0.39 eV. This conclusion is supported by both experiments and density functional theory calculations. Moreover, the migration volume at the saddle point for H in W is found to be positive: ΔV{sub m} ≈ 0.488 Å{sup 3}, leading to a decrease in the diffusivity at high pressures. At high H concentrations, a dramatic reduction in the diffusion coefficient is observed, due to site blocking and the repulsive H-H interaction. The results of this study indicates that high flux hydrogen irradiation leads to much higher H concentrations in tungsten than expected. - Highlights: • The recommended value of 0.39 eV for the H in W migration barrier should be changed to 0.25 eV. • The random oscillation of atoms around the equilibrium position can be dealt with in diffusion simulations. • Hydrogen diffusion in tungsten is highly concentration dependent.

  17. The hydrogen issue.

    Science.gov (United States)

    Armaroli, Nicola; Balzani, Vincenzo

    2011-01-17

    Hydrogen is often proposed as the fuel of the future, but the transformation from the present fossil fuel economy to a hydrogen economy will need the solution of numerous complex scientific and technological issues, which will require several decades to be accomplished. Hydrogen is not an alternative fuel, but an energy carrier that has to be produced by using energy, starting from hydrogen-rich compounds. Production from gasoline or natural gas does not offer any advantage over the direct use of such fuels. Production from coal by gasification techniques with capture and sequestration of CO₂ could be an interim solution. Water splitting by artificial photosynthesis, photobiological methods based on algae, and high temperatures obtained by nuclear or concentrated solar power plants are promising approaches, but still far from practical applications. In the next decades, the development of the hydrogen economy will most likely rely on water electrolysis by using enormous amounts of electric power, which in its turn has to be generated. Producing electricity by burning fossil fuels, of course, cannot be a rational solution. Hydroelectric power can give but a very modest contribution. Therefore, it will be necessary to generate large amounts of electric power by nuclear energy of by renewable energies. A hydrogen economy based on nuclear electricity would imply the construction of thousands of fission reactors, thereby magnifying all the problems related to the use of nuclear energy (e.g., safe disposal of radioactive waste, nuclear proliferation, plant decommissioning, uranium shortage). In principle, wind, photovoltaic, and concentrated solar power have the potential to produce enormous amounts of electric power, but, except for wind, such technologies are too underdeveloped and expensive to tackle such a big task in a short period of time. A full development of a hydrogen economy needs also improvement in hydrogen storage, transportation and distribution

  18. Characterizations of Hydrogen Energy Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Energetics Inc

    2003-04-01

    In 1996, Dr. Ed Skolnik of Energetics, Incorporated, began a series of visits to the locations of various projects that were part of the DOE Hydrogen Program. The site visits/evaluations were initiated to help the DOE Program Management, which had limited time and limited travel budgets, to get a detailed snapshot of each project. The evaluations were soon found to have other uses as well: they provided reviewers on the annual Hydrogen Program Peer Review Team with an in-depth look at a project--something that is lacking in a short presentation--and also provided a means for hydrogen stakeholders to learn about the R&D that the Hydrogen Program is sponsoring. The visits were conducted under several different contract mechanisms, at project locations specified by DOE Headquarters Program Management, Golden Field Office Contract Managers, or Energetics, Inc., or through discussion by some or all of the above. The methodology for these site-visit-evaluations changed slightly over the years, but was fundamentally as follows: Contact the Principal Investigator (PI) and arrange a time for the visit; Conduct a literature review. This would include a review of the last two or three years of Annual Operating Plan submittals, monthly reports, the paper submitted with the last two or three Annual Peer Review, published reviewers' consensus comments from the past few years, publications in journals, and journal publications on the same or similar topics by other researchers; Send the PI a list of questions/topics about a week ahead of time, which we would discuss during the visit. The types of questions vary depending on the project, but include some detailed technical questions that delve into some fundamental scientific and engineering issues, and also include some economic and goal-oriented topics; Conduct the site-visit itself including--Presentations by the PI and/or his staff. This would be formal in some cases, informal in others, and merely a &apos

  19. Nuclear power and hydrogen

    International Nuclear Information System (INIS)

    Welch, Robert.

    1982-06-01

    Ontario has been using CANDU reactors to produce electricity since 1962. The province does not have an electricity shortage, but it does have a shortage of liquid fuels. The government of Ontario is encouraging research into the production of hydrogen using electricity generated by a dedicated nuclear plant, and the safe and economical use of hydrogen both in the production of synthetic petroleum fuels and as a fuel in its own right

  20. Purdue Hydrogen Systems Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Jay P Gore; Robert Kramer; Timothee L Pourpoint; P. V. Ramachandran; Arvind Varma; Yuan Zheng

    2011-12-28

    The Hydrogen Systems Laboratory in a unique partnership between Purdue University's main campus in West Lafayette and the Calumet campus was established and its capabilities were enhanced towards technology demonstrators. The laboratory engaged in basic research in hydrogen production and storage and initiated engineering systems research with performance goals established as per the USDOE Hydrogen, Fuel Cells, and Infrastructure Technologies Program. In the chemical storage and recycling part of the project, we worked towards maximum recycling yield via novel chemical selection and novel recycling pathways. With the basic potential of a large hydrogen yield from AB, we used it as an example chemical but have also discovered its limitations. Further, we discovered alternate storage chemicals that appear to have advantages over AB. We improved the slurry hydrolysis approach by using advanced slurry/solution mixing techniques. We demonstrated vehicle scale aqueous and non-aqueous slurry reactors to address various engineering issues in on-board chemical hydrogen storage systems. We measured the thermal properties of raw and spent AB. Further, we conducted experiments to determine reaction mechanisms and kinetics of hydrothermolysis in hydride-rich solutions and slurries. We also developed a continuous flow reactor and a laboratory scale fuel cell power generation system. The biological hydrogen production work summarized as Task 4.0 below, included investigating optimal hydrogen production cultures for different substrates, reducing the water content in the substrate, and integrating results from vacuum tube solar collector based pre and post processing tests into an enhanced energy system model. An automated testing device was used to finalize optimal hydrogen production conditions using statistical procedures. A 3 L commercial fermentor (New Brunswick, BioFlo 115) was used to finalize testing of larger samples and to consider issues related to scale up

  1. A Rechargeable Hydrogen Battery.

    Science.gov (United States)

    Christudas Dargily, Neethu; Thimmappa, Ravikumar; Manzoor Bhat, Zahid; Devendrachari, Mruthunjayachari Chattanahalli; Kottaichamy, Alagar Raja; Gautam, Manu; Shafi, Shahid Pottachola; Thotiyl, Musthafa Ottakam

    2018-04-27

    We utilize proton-coupled electron transfer in hydrogen storage molecules to unlock a rechargeable battery chemistry based on the cleanest chemical energy carrier molecule, hydrogen. Electrochemical, spectroscopic, and spectroelectrochemical analyses evidence the participation of protons during charge-discharge chemistry and extended cycling. In an era of anthropogenic global climate change and paramount pollution, a battery concept based on a virtually nonpolluting energy carrier molecule demonstrates distinct progress in the sustainable energy landscape.

  2. Hydrogen recovery process

    Science.gov (United States)

    Baker, Richard W.; Lokhandwala, Kaaeid A.; He, Zhenjie; Pinnau, Ingo

    2000-01-01

    A treatment process for a hydrogen-containing off-gas stream from a refinery, petrochemical plant or the like. The process includes three separation steps: condensation, membrane separation and hydrocarbon fraction separation. The membrane separation step is characterized in that it is carried out under conditions at which the membrane exhibits a selectivity in favor of methane over hydrogen of at least about 2.5.

  3. Purdue Hydrogen Systems Laboratory

    International Nuclear Information System (INIS)

    Gore, Jay P.; Kramer, Robert; Pourpoint, Timothee L.; Ramachandran, P.V.; Varma, Arvind; Zheng, Yuan

    2011-01-01

    The Hydrogen Systems Laboratory in a unique partnership between Purdue University's main campus in West Lafayette and the Calumet campus was established and its capabilities were enhanced towards technology demonstrators. The laboratory engaged in basic research in hydrogen production and storage and initiated engineering systems research with performance goals established as per the USDOE Hydrogen, Fuel Cells, and Infrastructure Technologies Program. In the chemical storage and recycling part of the project, we worked towards maximum recycling yield via novel chemical selection and novel recycling pathways. With the basic potential of a large hydrogen yield from AB, we used it as an example chemical but have also discovered its limitations. Further, we discovered alternate storage chemicals that appear to have advantages over AB. We improved the slurry hydrolysis approach by using advanced slurry/solution mixing techniques. We demonstrated vehicle scale aqueous and non-aqueous slurry reactors to address various engineering issues in on-board chemical hydrogen storage systems. We measured the thermal properties of raw and spent AB. Further, we conducted experiments to determine reaction mechanisms and kinetics of hydrothermolysis in hydride-rich solutions and slurries. We also developed a continuous flow reactor and a laboratory scale fuel cell power generation system. The biological hydrogen production work summarized as Task 4.0 below, included investigating optimal hydrogen production cultures for different substrates, reducing the water content in the substrate, and integrating results from vacuum tube solar collector based pre and post processing tests into an enhanced energy system model. An automated testing device was used to finalize optimal hydrogen production conditions using statistical procedures. A 3 L commercial fermentor (New Brunswick, BioFlo 115) was used to finalize testing of larger samples and to consider issues related to scale up. Efforts

  4. Hydrogen diffusion and microstructure in undoped and boron-dope hydrogenated amorphous silicon: An IR and SIMS study

    International Nuclear Information System (INIS)

    Mitra, S.

    1991-01-01

    Hydrogenated amorphous silicon (a-Si:H) prepared by rf sputtering of a polycrystalline Si target at various rf powers 50 ≤ P ≤ 550 W (0.27--2.97 W/cm 2 ), target to substrate distance 1 ≤ d ≤ 2 double-prime, and varying hydrogen partial pressures. Doping was accomplished by introducing diborane (B 2 H 6 ) in the plasma. Hydrogen diffusion was studied from the depth profiles obtained from the SIMS on multilayered a-Si:H/a-Si:(H,D)/a-Si:H samples. The properties of the samples were characterized by IR absorption, optical gap measurements and ESR. IR yielded quantitative and qualitative information total hydrogen content and the nature of the hydrogen bonding, respectively. Hence the hydrogen microstructure of the samples could be varied in a systematic manner and monitored from the hydrogen vibrational modes. The ESR gave information on the number of paramagnetic defects per unit volume in the samples. The IR absorption of both as-deposited and annealed samples were closely monitored and the results clearly demonstrate a strong correlation between hydrogen diffusion and its microstructure. It is shown that microvoids in a-Si:H play a critical role in the process of diffusion by inducing deep hydrogen trapping sites that render them immobile. Consequently, as the microvoid density increases beyond a critical density hydrogen diffusion is totally quenched. The diffusion results are discussed both in the context of multiple trapping transport of hydrogen in an exponential distribution of trapping sites and the floating bond model

  5. Nanostructured materials for hydrogen storage

    Science.gov (United States)

    Williamson, Andrew J.; Reboredo, Fernando A.

    2007-12-04

    A system for hydrogen storage comprising a porous nano-structured material with hydrogen absorbed on the surfaces of the porous nano-structured material. The system of hydrogen storage comprises absorbing hydrogen on the surfaces of a porous nano-structured semiconductor material.

  6. Hydrogen Delivery Technical Team Roadmap

    Energy Technology Data Exchange (ETDEWEB)

    None

    2013-06-01

    The mission of the Hydrogen Delivery Technical Team (HDTT) is to enable the development of hydrogen delivery technologies, which will allow for fuel cell competitiveness with gasoline and hybrid technologies by achieving an as-produced, delivered, and dispensed hydrogen cost of $2-$4 per gallon of gasoline equivalent of hydrogen.

  7. Diffusion of hydrogen in yttrium

    International Nuclear Information System (INIS)

    Vorobyov, V.V.; Ryabchikov, L.N.

    1966-01-01

    In this work the diffusion coefficients of hydrogen in yttrium were determined from the rate at which the hydrogen was released from yttrium samples under a vacuum at temperatures of 450 to 850 0 C and from the quantity of hydrogen retained by yttrium at hydrogen pressures below 5 x 10 - 4 mm Hg in the same temperature range

  8. MODELING STYRENE HYDROGENATION KINETICS USING PALLADIUM CATALYSTS

    Directory of Open Access Journals (Sweden)

    G. T. Justino

    Full Text Available Abstract The high octane number of pyrolysis gasoline (PYGAS explains its insertion in the gasoline pool. However, its use is troublesome due to the presence of gum-forming chemicals which, in turn, can be removed via hydrogenation. The use of Langmuir-Hinshelwood kinetic models was evaluated for hydrogenation of styrene, a typical gum monomer, using Pd/9%Nb2O5-Al2O3 as catalyst. Kinetic models accounting for hydrogen dissociative and non-dissociative adsorption were considered. The availability of one or two kinds of catalytic sites was analyzed. Experiments were carried out in a semi-batch reactor at constant temperature and pressure in the absence of transport limitations. The conditions used in each experiment varied between 16 - 56 bar and 60 - 100 ºC for pressure and temperature, respectively. The kinetic models were evaluated using MATLAB and EMSO software. Models using adsorption of hydrogen and organic molecules on the same type of site fitted the data best.

  9. Development of Hydrogen Education Programs for Government Officials

    Energy Technology Data Exchange (ETDEWEB)

    Baxter, Shannon [South Carolina Hydrogen and Fuel Cell Alliance, Columbia, SC (United States); Keller, Russ [Advanced Technology International, Cedarburg, WI (United States)

    2016-03-08

    1. Subcontractor/Technical Subject Matter Expert (Tasks 1-3) 2. Technical lead for LFG cleanup and hydrogen production systems Support for Feasibility Study 3. Technical Lead for Feasibility Study Coordination of site preparation activities for all project equipment 4. Host site

  10. Constraining the Evolution of ZZ Ceti

    Directory of Open Access Journals (Sweden)

    Mukadam A. S.

    2003-03-01

    Full Text Available We report our analysis of the stability of pulsation periods in the DAV star (pulsating hydrogen atmosphere white dwarf ZZ Ceti, also called R548. Based on observations that span 31 years, we conclude that the period 213.132605 s observed in ZZ Ceti drifts at a rate dP/dt≤(5.5±1.9×10−15 s/s, after correcting for proper motion. Our results are consistent with previous Ṗ values for this mode and an improvement over them due to the larger time-base. The characteristic stability timescale implied for the pulsation period is |P/ Ṗ|≥1.2 Gyr, comparable to the theoretical cooling timescale for the star. Our current stability limit for the period 213.132605 s is only slightly less than the present measurement for G117-B15A for the period 215.2 s, another DAV, establishing this mode in ZZ Ceti as the second most stable optical clock known, more stable than atomic clocks and most pulsars.

  11. Multiple Observation Types Jointly Constrain Terrestrial Carbon and Water Cycles

    Science.gov (United States)

    Raupach, M. R.; Haverd, V.; Briggs, P. R.; Canadell, J.; Davis, S. J.; Isaac, P. R.; Law, R.; Meyer, M.; Peters, G. P.; Pickett Heaps, C.; Roxburgh, S. H.; Sherman, B.; van Gorsel, E.; Viscarra Rossel, R.; Wang, Z.

    2012-12-01

    Information about the carbon cycle potentially constrains the water cycle, and vice versa. This paper explores the utility of multiple observation sets to constrain carbon and water fluxes and stores in a land surface model, and a resulting determination of the Australian terrestrial carbon budget. Observations include streamflow from 416 gauged catchments, measurements of evapotranspiration (ET) and net ecosystem production (NEP) from 12 eddy-flux sites, litterfall data, and data on carbon pools. The model is a version of CABLE (the Community Atmosphere-Biosphere-Land Exchange model), coupled with CASAcnp (a biogeochemical model) and SLI (Soil-Litter-Iso, a soil hydrology model including liquid and vapour water fluxes and the effects of litter). By projecting observation-prediction residuals onto model uncertainty, we find that eddy flux measurements provide a significantly tighter constraint on Australian continental net primary production (NPP) than the other data types. However, simultaneous constraint by multiple data types is important for mitigating bias from any single type. Results emerging from the multiply-constrained model are as follows (with all values applying over 1990-2011 and all ranges denoting ±1 standard error): (1) on the Australian continent, a predominantly semi-arid region, over half (0.64±0.05) of the water loss through ET occurs through soil evaporation and bypasses plants entirely; (2) mean Australian NPP is 2200±400 TgC/y, making the NPP/precipitation ratio about the same for Australia as the global land average; (3) annually cyclic ("grassy") vegetation and persistent ("woody") vegetation respectively account for 0.56±0.14 and 0.43±0.14 of NPP across Australia; (4) the average interannual variability of Australia's NEP (±180 TgC/y) is larger than Australia's total anthropogenic greenhouse gas emissions in 2011 (149 TgCeq/y), and is dominated by variability in desert and savannah regions. The mean carbon budget over 1990

  12. Examining hydrogen transitions.

    Energy Technology Data Exchange (ETDEWEB)

    Plotkin, S. E.; Energy Systems

    2007-03-01

    This report describes the results of an effort to identify key analytic issues associated with modeling a transition to hydrogen as a fuel for light duty vehicles, and using insights gained from this effort to suggest ways to improve ongoing modeling efforts. The study reported on here examined multiple hydrogen scenarios reported in the literature, identified modeling issues associated with those scenario analyses, and examined three DOE-sponsored hydrogen transition models in the context of those modeling issues. The three hydrogen transition models are HyTrans (contractor: Oak Ridge National Laboratory), MARKAL/DOE* (Brookhaven National Laboratory), and NEMS-H2 (OnLocation, Inc). The goals of these models are (1) to help DOE improve its R&D effort by identifying key technology and other roadblocks to a transition and testing its technical program goals to determine whether they are likely to lead to the market success of hydrogen technologies, (2) to evaluate alternative policies to promote a transition, and (3) to estimate the costs and benefits of alternative pathways to hydrogen development.

  13. Hydrogen and nuclear power

    International Nuclear Information System (INIS)

    Holt, D.J.

    1976-12-01

    This study examines the influence that the market demand for hydrogen might have on the development of world nuclear capacity over the next few decades. In a nuclear economy, hydrogen appears to be the preferred energy carrier over electricity for most purposes, due to its ready substitution and usage for all energy needs, as well as its low transmission costs. The economic factors upon which any transition to hydrogen fuelling will be largely based are seen to be strongly dependent on the form of future energy demand, the energy resource base, and on the status of technology. Accordingly, the world energy economy is examined to identify the factors which might affect the future demand price structure for energy, and a survey of current estimates of world energy resources, particularly oil, gas, nuclear, and solar, is presented. Current and projected technologies for production and utilization of hydrogen are reviewed, together with rudimentary cost estimates. The relative economics are seen to favour production of hydrogen from fossil fuels far into the foreseeable future, and a clear case emerges for high temperature nuclear reactors in such process heat applications. An expanding industrial market for hydrogen, and near term uses in steelmaking and aircraft fuelling are foreseen, which would justify an important development effort towards nuclear penetration of that market. (author)

  14. Electrochemical hydrogen Storage Systems

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Digby Macdonald

    2010-08-09

    As the global need for energy increases, scientists and engineers have found a possible solution by using hydrogen to power our world. Although hydrogen can be combusted as a fuel, it is considered an energy carrier for use in fuel cells wherein it is consumed (oxidized) without the production of greenhouse gases and produces electrical energy with high efficiency. Chemical storage of hydrogen involves release of hydrogen in a controlled manner from materials in which the hydrogen is covalently bound. Sodium borohydride and aminoborane are two materials given consideration as chemical hydrogen storage materials by the US Department of Energy. A very significant barrier to adoption of these materials as hydrogen carriers is their regeneration from 'spent fuel,' i.e., the material remaining after discharge of hydrogen. The U.S. Department of Energy (DOE) formed a Center of Excellence for Chemical Hydrogen Storage, and this work stems from that project. The DOE has identified boron hydrides as being the main compounds of interest as hydrogen storage materials. The various boron hydrides are then oxidized to release their hydrogen, thereby forming a 'spent fuel' in the form of a lower boron hydride or even a boron oxide. The ultimate goal of this project is to take the oxidized boron hydrides as the spent fuel and hydrogenate them back to their original form so they can be used again as a fuel. Thus this research is essentially a boron hydride recycling project. In this report, research directed at regeneration of sodium borohydride and aminoborane is described. For sodium borohydride, electrochemical reduction of boric acid and sodium metaborate (representing spent fuel) in alkaline, aqueous solution has been investigated. Similarly to literature reports (primarily patents), a variety of cathode materials were tried in these experiments. Additionally, approaches directed at overcoming electrostatic repulsion of borate anion from the cathode, not

  15. Metallic hydrogen research

    International Nuclear Information System (INIS)

    Burgess, T.J.; Hawke, R.S.

    1978-01-01

    Theoretical studies predict that molecular hydrogen can be converted to the metallic phase at very high density and pressure. These conditions were achieved by subjecting liquid hydrogen to isentropic compression in a magnetic-flux compression device. Hydrogen became electrically conducting at a density of about 1.06 g/cm 3 and a calculated pressure of about 2 Mbar. In the experimental device, a cylindrical liner, on implosion by high explosive, compresses a magnetic flux which in turn isentropically compresses a hydrogen sample; coaxial conical anvils prevent escape of the sample during compression. One anvil contains a coaxial cable that uses alumina ceramic as an insulator; this probe allows continuous measurement of the electrical conductivity of the hydrogen. A flash x-ray radiograph exposed during the experiment records the location of the sample-tube boundaries and permits calculation of the sample density. The theoretical underpinnings of the metallic transition of hydrogen are briefly summarized, and the experimental apparatus and technique, analytical methods, and results are described. 9 figures

  16. Hydrogen isotope technology

    International Nuclear Information System (INIS)

    Anon.

    1980-01-01

    Hydrogen pumping speeds on panels of molecular sieve types 5A and Na-Y were compared for a variety of sieve (and chevron) temperatures between 10 and 30 K. Although pumping speeds declined with time, probably because of the slow diffusion of hydrogen from the surface of the sieve crystals into the internal regions, the different sieve materials and operating conditions could be compared using time-averaged pump speeds. The (average) pumping speeds declined with increasing temperature. Under some conditions, the Na-Y sieve performed much better than the 5A sieve. Studies of the effect of small concentrations (approx. 4%) of hydrogen on helium pumping indicate that compound cryopumps in fusion reactors will not have to provide complete screening of hydrogen from helium panels. The concentrations of hydrogen did not lower effective helium pumping speeds or shorten the helium operating period between instabilities. Studies of tritium recovery from blankets of liquid lithium focused on design and construction of a flowing-lithium test system and on ultimate removal of tritium from yttrium sorbents. At 505 0 C, tritium release from yttrium behaves as a diffusion-controlled process, but the release rates are very low. Apparently, higher temperatures will be required for effective sorbent regeneration. An innovative technique for separating hydrogen isotopes by using bipolar electrolysis with permeable electrodes was analyzed to determine its potential usefulness in multistage separation

  17. Electrochemical hydrogen Storage Systems

    International Nuclear Information System (INIS)

    Macdonald, Digby

    2010-01-01

    As the global need for energy increases, scientists and engineers have found a possible solution by using hydrogen to power our world. Although hydrogen can be combusted as a fuel, it is considered an energy carrier for use in fuel cells wherein it is consumed (oxidized) without the production of greenhouse gases and produces electrical energy with high efficiency. Chemical storage of hydrogen involves release of hydrogen in a controlled manner from materials in which the hydrogen is covalently bound. Sodium borohydride and aminoborane are two materials given consideration as chemical hydrogen storage materials by the US Department of Energy. A very significant barrier to adoption of these materials as hydrogen carriers is their regeneration from 'spent fuel,' i.e., the material remaining after discharge of hydrogen. The U.S. Department of Energy (DOE) formed a Center of Excellence for Chemical Hydrogen Storage, and this work stems from that project. The DOE has identified boron hydrides as being the main compounds of interest as hydrogen storage materials. The various boron hydrides are then oxidized to release their hydrogen, thereby forming a 'spent fuel' in the form of a lower boron hydride or even a boron oxide. The ultimate goal of this project is to take the oxidized boron hydrides as the spent fuel and hydrogenate them back to their original form so they can be used again as a fuel. Thus this research is essentially a boron hydride recycling project. In this report, research directed at regeneration of sodium borohydride and aminoborane is described. For sodium borohydride, electrochemical reduction of boric acid and sodium metaborate (representing spent fuel) in alkaline, aqueous solution has been investigated. Similarly to literature reports (primarily patents), a variety of cathode materials were tried in these experiments. Additionally, approaches directed at overcoming electrostatic repulsion of borate anion from the cathode, not described in the

  18. Neutron Spectroscopy Can Constrain the Composition and Provenance of Phobos and Deimos

    Science.gov (United States)

    Elphic, R. C.; Lee, P.; Zolensky, M. E.; Mittlefehldt, D. W.; Lim, L. F.; Colaprete, A.

    2016-01-01

    The origin of the martian moons Phobos and Deimos is obscure and enigmatic. Hypotheses include the capture of small bodies originally from the outer main belt or beyond, residual material left over from Mars' formation, and accreted ejecta from a large impact on Mars, among others. Measurements of reflectance spectra indicate a similarity to low-albedo, red D-type asteroids, but could indicate a highly space-weathered veneer. Here we suggest a way of constraining the near-surface composition of the two moons, for comparison with known meteoritic compositions. Neutron spectroscopy, particularly the thermal and epithermal neutron flux, distinguishes clearly between various classes of meteorites and varying hydrogen (water) abundances. Perhaps most surprising of all, a rendezvous with Phobos or Deimos is not necessary to achieve this. Multiple flybys suffice.

  19. Wind-To-Hydrogen Energy Pilot Project

    Energy Technology Data Exchange (ETDEWEB)

    Ron Rebenitsch; Randall Bush; Allen Boushee; Brad G. Stevens; Kirk D. Williams; Jeremy Woeste; Ronda Peters; Keith Bennett

    2009-04-24

    WIND-TO-HYDROGEN ENERGY PILOT PROJECT: BASIN ELECTRIC POWER COOPERATIVE In an effort to address the hurdles of wind-generated electricity (specifically wind's intermittency and transmission capacity limitations) and support development of electrolysis technology, Basin Electric Power Cooperative (BEPC) conducted a research project involving a wind-to-hydrogen system. Through this effort, BEPC, with the support of the Energy & Environmental Research Center at the University of North Dakota, evaluated the feasibility of dynamically scheduling wind energy to power an electrolysis-based hydrogen production system. The goal of this project was to research the application of hydrogen production from wind energy, allowing for continued wind energy development in remote wind-rich areas and mitigating the necessity for electrical transmission expansion. Prior to expending significant funding on equipment and site development, a feasibility study was performed. The primary objective of the feasibility study was to provide BEPC and The U.S. Department of Energy (DOE) with sufficient information to make a determination whether or not to proceed with Phase II of the project, which was equipment procurement, installation, and operation. Four modes of operation were considered in the feasibility report to evaluate technical and economic merits. Mode 1 - scaled wind, Mode 2 - scaled wind with off-peak, Mode 3 - full wind, and Mode 4 - full wind with off-peak In summary, the feasibility report, completed on August 11, 2005, found that the proposed hydrogen production system would produce between 8000 and 20,000 kg of hydrogen annually depending on the mode of operation. This estimate was based on actual wind energy production from one of the North Dakota (ND) wind farms of which BEPC is the electrical off-taker. The cost of the hydrogen produced ranged from $20 to $10 per kg (depending on the mode of operation). The economic sensitivity analysis performed as part of the

  20. Hydrogen Storage In Nanostructured Materials

    OpenAIRE

    Assfour, Bassem

    2011-01-01

    Hydrogen is an appealing energy carrier for clean energy use. However, storage of hydrogen is still the main bottleneck for the realization of an energy economy based on hydrogen. Many materials with outstanding properties have been synthesized with the aim to store enough amount of hydrogen under ambient conditions. Such efforts need guidance from material science, which includes predictive theoretical tools. Carbon nanotubes were considered as promising candidates for hydrogen storag...

  1. Hydrogen storage and generation system

    Science.gov (United States)

    Dentinger, Paul M.; Crowell, Jeffrey A. W.

    2010-08-24

    A system for storing and generating hydrogen generally and, in particular, a system for storing and generating hydrogen for use in an H.sub.2/O.sub.2 fuel cell. The hydrogen storage system uses the beta particles from a beta particle emitting material to degrade an organic polymer material to release substantially pure hydrogen. In a preferred embodiment of the invention, beta particles from .sup.63Ni are used to release hydrogen from linear polyethylene.

  2. KINETIC CONSEQUENCES OF CONSTRAINING RUNNING BEHAVIOR

    Directory of Open Access Journals (Sweden)

    John A. Mercer

    2005-06-01

    Full Text Available It is known that impact forces increase with running velocity as well as when stride length increases. Since stride length naturally changes with changes in submaximal running velocity, it was not clear which factor, running velocity or stride length, played a critical role in determining impact characteristics. The aim of the study was to investigate whether or not stride length influences the relationship between running velocity and impact characteristics. Eight volunteers (mass=72.4 ± 8.9 kg; height = 1.7 ± 0.1 m; age = 25 ± 3.4 years completed two running conditions: preferred stride length (PSL and stride length constrained at 2.5 m (SL2.5. During each condition, participants ran at a variety of speeds with the intent that the range of speeds would be similar between conditions. During PSL, participants were given no instructions regarding stride length. During SL2.5, participants were required to strike targets placed on the floor that resulted in a stride length of 2.5 m. Ground reaction forces were recorded (1080 Hz as well as leg and head accelerations (uni-axial accelerometers. Impact force and impact attenuation (calculated as the ratio of head and leg impact accelerations were recorded for each running trial. Scatter plots were generated plotting each parameter against running velocity. Lines of best fit were calculated with the slopes recorded for analysis. The slopes were compared between conditions using paired t-tests. Data from two subjects were dropped from analysis since the velocity ranges were not similar between conditions resulting in the analysis of six subjects. The slope of impact force vs. velocity relationship was different between conditions (PSL: 0.178 ± 0.16 BW/m·s-1; SL2.5: -0.003 ± 0.14 BW/m·s-1; p < 0.05. The slope of the impact attenuation vs. velocity relationship was different between conditions (PSL: 5.12 ± 2.88 %/m·s-1; SL2.5: 1.39 ± 1.51 %/m·s-1; p < 0.05. Stride length was an important factor

  3. Safe production and application of hydrogen at Munich airport

    Energy Technology Data Exchange (ETDEWEB)

    Szamer, R.

    2005-07-01

    At Munich International Airport the world's first public filling station for liquid and gaseous hydrogen with on-site hydrogen gas production has been installed. In order to prove the safety, liability and economic feasibility of hydrogen this pilot project examined the complete sequence of hydrogen production and application: on-site production with pressurized electrolyser and steam reformer, storage and filling of gaseous and liquid hydrogen, application of hydrogen for propelling several vehicles, e.g. airport busses in day to day operation, cars, fork lifter. TUV SUD Group, one of the largest service provider for technical safety and quality, was involved in the safety evaluation of the hydrogen project from the very beginning with the following services: safety consultancy throughout all project phases, e.g. for licensing procedures, plant design and operation safety analysis of the overall plant and of subsystems (electrolyser, filling stations, storage tanks, control systems etc.) safety assessment and acceptance testing of CH2 busses, CH2 fork lifter and LH2 passenger cars inspections and tests The challenges of this complex project relating to safety will be presented in the lecture, e.g. identification of potential hazards, safety requirements for the design and operation of the hydrogen plant as wells as for the various applications. Project description The hydrogen plant (cf. Figure 1) comprises two supply paths, one for compressed gaseous hydrogen (CH2) and one for cryogenic liquid hydrogen. Gaseous hydrogen is produced via high-pressure electrolysis at an operating pressure of 3 MPa (30 bar) and/or steam reforming process. The hydrogen will be led into a compressor, compressed to 35 MPa (350 bar) and stored in high pressure cylinders with a total geometrical storage volume of 10 m. The cylinders supply the high-pressure filling stations which refuels the 3 hydrogen buses and the fork lifter. Liquid hydrogen (LH2) is delivered in tank trucks and

  4. Hydrogen, energy of the future?

    International Nuclear Information System (INIS)

    Alleau, Th.

    2007-01-01

    A cheap, non-polluting energy with no greenhouse gas emissions and unlimited resources? This is towards this fantastic future that this book brings us, analyzing the complex but promising question of hydrogen. The scientific and technical aspects of production, transport, storage and distribution raised by hydrogen are thoroughly reviewed. Content: I) Energy, which solutions?: 1 - hydrogen, a future; 2 - hydrogen, a foreseeable solution?; II) Hydrogen, an energy vector: 3 - characteristics of hydrogen (physical data, quality and drawbacks); 4 - hydrogen production (from fossil fuels, from water, from biomass, bio-hydrogen generation); 5 - transport, storage and distribution of hydrogen; 6 - hydrogen cost (production, storage, transport and distribution costs); III) Fuel cells and ITER, utopias?: 7 - molecular hydrogen uses (thermal engines and fuel cells); 8 - hydrogen and fusion (hydrogen isotopes, thermonuclear reaction, ITER project, fusion and wastes); IV) Hydrogen acceptability: 9 - risk acceptability; 10 - standards and regulations; 11 - national, European and international policies about hydrogen; 12 - big demonstration projects in France and in the rest of the world; conclusion. (J.S.)

  5. Future hydrogen markets for large-scale hydrogen production systems

    International Nuclear Information System (INIS)

    Forsberg, Charles W.

    2007-01-01

    The cost of delivered hydrogen includes production, storage, and distribution. For equal production costs, large users (>10 6 m 3 /day) will favor high-volume centralized hydrogen production technologies to avoid collection costs for hydrogen from widely distributed sources. Potential hydrogen markets were examined to identify and characterize those markets that will favor large-scale hydrogen production technologies. The two high-volume centralized hydrogen production technologies are nuclear energy and fossil energy with carbon dioxide sequestration. The potential markets for these technologies are: (1) production of liquid fuels (gasoline, diesel and jet) including liquid fuels with no net greenhouse gas emissions and (2) peak electricity production. The development of high-volume centralized hydrogen production technologies requires an understanding of the markets to (1) define hydrogen production requirements (purity, pressure, volumes, need for co-product oxygen, etc.); (2) define and develop technologies to use the hydrogen, and (3) create the industrial partnerships to commercialize such technologies. (author)

  6. Potential of AlN nanostructures as hydrogen storage materials.

    Science.gov (United States)

    Wang, Qian; Sun, Qiang; Jena, Puru; Kawazoe, Yoshiyuki

    2009-03-24

    The capability of AlN nanostructures (nanocages, nanocones, nanotubes, and nanowires) to store hydrogen has been studied using gradient-corrected density functional theory. In contrast to bulk AlN, which has the wurtzite structure and four-fold coordination, the Al sites in AlN nanostructures are unsaturated and have two- and three-fold coordination. Each Al atom is capable of binding one H(2) molecule in quasi-molecular form, leading to 4.7 wt % hydrogen, irrespective of the topology of the nanostructures. With the exception of AlN nanotubes, energetics does not support the adsorption of additional hydrogen. The binding energies of hydrogen to these unsaturated metal sites lie in the range of 0.1-0.2 eV/H(2) and are ideal for applications under ambient thermodynamic conditions. Furthermore, these materials do not suffer from the clustering problem that often plagues metal-coated carbon nanostructures.

  7. Ionization of Interstellar Hydrogen

    Science.gov (United States)

    Whang, Y. C.

    1996-09-01

    Interstellar hydrogen can penetrate through the heliopause, enter the heliosphere, and may become ionized by photoionization and by charge exchange with solar wind protons. A fluid model is introduced to study the flow of interstellar hydrogen in the heliosphere. The flow is governed by moment equations obtained from integration of the Boltzmann equation over the velocity space. Under the assumption that the flow is steady axisymmetric and the pressure is isotropic, we develop a method of solution for this fluid model. This model and the method of solution can be used to study the flow of neutral hydrogen with various forms of ionization rate β and boundary conditions for the flow on the upwind side. We study the solution of a special case in which the ionization rate β is inversely proportional to R2 and the interstellar hydrogen flow is uniform at infinity on the upwind side. We solve the moment equations directly for the normalized density NH/NN∞, bulk velocity VH/VN∞, and temperature TH/TN∞ of interstellar hydrogen as functions of r/λ and z/λ, where λ is the ionization scale length. The solution is compared with the kinetic theory solution of Lallement et al. The fluid solution is much less time-consuming than the kinetic theory solutions. Since the ionization rate for production of pickup protons is directly proportional to the local density of neutral hydrogen, the high-resolution solution of interstellar neutral hydrogen obtained here will be used to study the global distribution of pickup protons.

  8. Onomatopoeia characters extraction from comic images using constrained Delaunay triangulation

    Science.gov (United States)

    Liu, Xiangping; Shoji, Kenji; Mori, Hiroshi; Toyama, Fubito

    2014-02-01

    A method for extracting onomatopoeia characters from comic images was developed based on stroke width feature of characters, since they nearly have a constant stroke width in a number of cases. An image was segmented with a constrained Delaunay triangulation. Connected component grouping was performed based on the triangles generated by the constrained Delaunay triangulation. Stroke width calculation of the connected components was conducted based on the altitude of the triangles generated with the constrained Delaunay triangulation. The experimental results proved the effectiveness of the proposed method.

  9. In Situ Measurement of Local Hydrogen Production Rate by Bubble-Evolved Recording

    Directory of Open Access Journals (Sweden)

    Xiaowei Hu

    2013-01-01

    Full Text Available Hydrogen visibly bubbles during photocatalytic water splitting under illumination with above-bandgap radiation, which provides a direct measurement of local gas-evolving reaction rate. In this paper, optical microscopy of superfield depth was used for recording the hydrogen bubble growth on Cd0.5Zn0.5S photocatalyst in reaction liquid and illuminated with purple light. By analyzing change of hydrogen bubble size as a function of time, we understood that hydrogen bubble growth experienced two periods, which were inertia effect dominated period and diffusion effect dominated period, respectively. The tendency of hydrogen bubble growth was similar to that of the gas bubble in boiling, while the difference in bubble diameter and growth time magnitude was great. Meanwhile, we obtained the local hydrogen production rate on photocatalyst active site by measuring hydrogen bubble growth variation characteristics. This method makes it possible to confirm local actual hydrogen evolution rate quantitatively during photocatalytic water splitting.

  10. Hydrogen for buses in London: A scenario analysis of changes over time in refuelling infrastructure costs

    International Nuclear Information System (INIS)

    Shayegan, S.; Pearson, P.J.G.; Hart, D.

    2009-01-01

    The lack of a hydrogen refuelling infrastructure is one of the major obstacles to the introduction of the hydrogen vehicles to the road transport market. To help overcome this hurdle a likely transitional solution is to introduce hydrogen for niche applications such as buses or other types of fleet vehicles for which fuel demand is predictable and localised. This paper analyses the costs of different hydrogen production-delivery pathways, via a case study of buses in London. Scenario analysis over time (2007-2025) is used to investigate potential changes to the cost of hydrogen as a result of technology development, growing demand for hydrogen and changes in energy prices (gas and electricity). It is found that factors related to hydrogen demand have the greatest effect on the unit cost of hydrogen, while for the whole of the analysis period, on-site SMR (steam methane reforming) remains the least-cost production-delivery pathway. (author)

  11. Influence of adsorbed carbon dioxide on hydrogen electrosorption in palladium-platinum-rhodium alloys

    International Nuclear Information System (INIS)

    Lukaszewski, M.; Grden, M.; Czerwinski, A.

    2004-01-01

    Carbon dioxide electroreduction was applied to examine the processes of hydrogen electrosorption (adsorption, absorption and desorption) by thin electrodeposits of Pd-Pt-Rh alloys under conditions of cyclic voltammetric (CV) experiments. Due to different adsorption characteristics towards the adsorption product of the electroreduction of CO 2 (reduced CO 2 ) exhibited by the alloy components hydrogen adsorption and hydrogen absorption signals can be distinguished on CV curves. Reduced CO 2 causes partial blocking of hydrogen adsorbed on surface Pt and Rh atoms, without any significant effect on hydrogen absorption into alloy. It reflects the fact that adsorbed hydrogen bonded to Pd atoms does not participate in CO 2 reduction, while hydrogen adsorbed on Pt and Rh surface sites is inactive in the absorption reaction. In contrast, CO is adsorbed on all alloy components and causes a marked inhibition of hydrogen sorption (both adsorption and absorption)/desorption reactions

  12. Hydrogen adsorption on and solubility in graphites

    International Nuclear Information System (INIS)

    Kanashenko, S.L.; Wampler, W.R.

    1996-01-01

    The experimental data on adsorption and solubility of hydrogen isotopes in graphite over a wide range of temperatures and pressures are reviewed. Langmuir adsorption isotherms are proposed for the hydrogen-graphite interaction. The entropy and enthalpy of adsorption are estimated, allowing for effects of relaxation of dangling sp 2 bonds. Three kinds of traps are proposed: edge carbon atoms of interstitial loops with an adsorption enthalpy relative to H 2 gas of -4.4 eV/H 2 (unrelaxed, Trap 1), edge carbon atoms at grain surfaces with an adsorption enthalpy of -2.3 eV/H 2 (relaxed, Trap 2), and basal plane adsorption sites with an enthalpy of +2.43 eV/H 2 (Trap 3). The adsorption capacity of different types of graphite depends on the concentration of traps which depends on the crystalline microstructure of the material. The number of potential sites for the 'true solubility' (Trap 3) is assumed to be about one site per carbon atom in all types of graphite, but the endothermic character of this solubility leads to a negligible H inventory compared to the concentration of hydrogen in type 1 and type 2 traps for temperatures and gas pressures used in the experiments. Irradiation with neutrons or carbon atoms increases the concentration of type 1 and type 2 traps from about 20 and 200 appm respectively for unirradiated (POCO AXF-5Q) graphite to about 1500 and 5000 appm, respectively, at damage levels above 1 dpa. (orig.)

  13. Hydrogen concentration control utilizing a hydrogen permeable membrane

    International Nuclear Information System (INIS)

    Keating, S.J. Jr.

    1976-01-01

    The concentration of hydrogen in a fluid mixture is controlled to a desired concentration by flowing the fluid through one chamber of a diffusion cell separated into two chambers by a hydrogen permeable membrane. A gradient of hydrogen partial pressure is maintained across the membrane to cause diffusion of hydrogen through the membrane to maintain the concentration of hydrogen in the fluid mixture at the predetermined level. The invention has particular utility for the purpose of injecting into and/or separating hydrogen from the reactor coolant of a nuclear reactor system

  14. Hydrogen molecules and hydrogen-related defects in crystalline silicon

    OpenAIRE

    Fukata, N.; Sasak, S.; Murakami, K.; Ishioka, K.; Nakamura, K. G.; Kitajima, M.; Fujimura, S.; Kikuchi, J.; Haneda, H.

    1997-01-01

    We have found that hydrogen exists in molecular form in crystalline silicon treated with hydrogen atoms in the downstream of a hydrogen plasma. The vibrational Raman line of hydrogen molecules is observed at 4158cm-1 for silicon samples hydrogenated between 180 and 500 °C. The assignment of the Raman line is confirmed by its isotope shift to 2990cm-1 for silicon treated with deuterium atoms. The Raman intensity has a maximum for hydrogenation at 400 °C. The vibrational Raman line of the hydro...

  15. Magnetic liquefier for hydrogen

    International Nuclear Information System (INIS)

    1992-01-01

    This document summarizes work done at the Astronautics Technology Center of the Astronautics Corporation of America (ACA) in Phase 1 of a four phase program leading to the development of a magnetic liquefier for hydrogen. The project involves the design, fabrication, installation, and operation of a hydrogen liquefier providing significantly reduced capital and operating costs, compared to present liquefiers. To achieve this goal, magnetic refrigeration, a recently developed, highly efficient refrigeration technology, will be used for the liquefaction process. Phase 1 project tasks included liquefier conceptual design and analysis, preliminary design of promising configurations, design selection, and detailed design of the selected design. Fabrication drawings and vendor specifications for the selected design were completed during detailed design. The design of a subscale, demonstration magnetic hydrogen liquefier represents a significant advance in liquefaction technology. The cost reductions that can be realized in hydrogen liquefaction in both the subscale and, more importantly, in the full-scale device are expected to have considerable impact on the use of liquid hydrogen in transportation, chemical, and electronic industries. The benefits to the nation from this technological advance will continue to have importance well into the 21st century

  16. The hydrogen laminar jet

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Sanz, M. [Departamento de Motopropulsion y Termofluidomecanica, ETSI Aeronauticos, Universidad Politecnica de Madrid, 28040 Madrid (Spain); Rosales, M. [Department Ingenieria Termica y de Fluidos, Universidad Carlos III de Madrid, 28911, Leganes (Spain); Instituto de Innovacion en Mineria y Metalurgia, Avenida del Valle 738, Santiago (Chile); Sanchez, A.L. [Department Ingenieria Termica y de Fluidos, Universidad Carlos III de Madrid, 28911, Leganes (Spain)

    2010-04-15

    Numerical and asymptotic methods are used to investigate the structure of the hydrogen jet discharging into a quiescent air atmosphere. The analysis accounts in particular for the variation of the density and transport properties with composition. The Reynolds number of the flow R{sub j}, based on the initial jet radius a, the density {rho}{sub j} and viscosity {mu}{sub j} of the jet and the characteristic jet velocity u{sub j}, is assumed to take moderately large values, so that the jet remains slender and stable, and can be correspondingly described by numerical integration of the continuity, momentum and species conservation equations written in the boundary-layer approximation. The solution for the velocity and composition in the jet development region of planar and round jets, corresponding to streamwise distances of order R{sub j}a, is computed numerically, along with the solutions that emerge both in the near field and in the far field. The small value of the hydrogen-to-air molecular weight ratio is used to simplify the solution by considering the asymptotic limit of vanishing jet density. The development provides at leading-order explicit analytical expressions for the far-field velocity and hydrogen mass fraction that describe accurately the hydrogen jet near the axis. The information provided can be useful in particular to characterize hydrogen discharge processes from holes and cracks. (author)

  17. Hydrogen Contractors Meeting

    Energy Technology Data Exchange (ETDEWEB)

    Fitzsimmons, Tim [Dept. of Energy (DOE), Washington DC (United States). Office of Basic Energy Sciences. Division of Materials Sciences and Engineering

    2006-05-16

    This volume highlights the scientific content of the 2006 Hydrogen Contractors Meeting sponsored by the Division of Materials Sciences and Engineering (DMS&E) on behalf of the Office of Basic Energy Sciences (BES) of the U. S. Department of Energy (DOE). Hydrogen Contractors Meeting held from May 16-19, 2006 at the Crystal Gateway Marriott Hotel Arlington, Virginia. This meeting is the second in a series of research theme-based Contractors Meetings sponsored by DMS&E held in conjunction with our counterparts in the Office of Energy Efficiency and Renewable Energy (EERE) and the first with the Hydrogen, Fuel Cells and Infrastructure Technologies Program. The focus of this year’s meeting is BES funded fundamental research underpinning advancement of hydrogen storage. The major goals of these research efforts are the development of a fundamental scientific base in terms of new concepts, theories and computational tools; new characterization capabilities; and new materials that could be used or mimicked in advancing capabilities for hydrogen storage.

  18. Hot Hydrogen Test Facility

    International Nuclear Information System (INIS)

    W. David Swank

    2007-01-01

    The core in a nuclear thermal rocket will operate at high temperatures and in hydrogen. One of the important parameters in evaluating the performance of a nuclear thermal rocket is specific impulse, ISp. This quantity is proportional to the square root of the propellant's absolute temperature and inversely proportional to square root of its molecular weight. Therefore, high temperature hydrogen is a favored propellant of nuclear thermal rocket designers. Previous work has shown that one of the life-limiting phenomena for thermal rocket nuclear cores is mass loss of fuel to flowing hydrogen at high temperatures. The hot hydrogen test facility located at the Idaho National Lab (INL) is designed to test suitability of different core materials in 2500 C hydrogen flowing at 1500 liters per minute. The facility is intended to test non-uranium containing materials and therefore is particularly suited for testing potential cladding and coating materials. In this first installment the facility is described. Automated Data acquisition, flow and temperature control, vessel compatibility with various core geometries and overall capabilities are discussed

  19. Microfabricated hydrogen sensitive membranes

    Energy Technology Data Exchange (ETDEWEB)

    Naddaf, A.; Kraetz, L. [Lehrstuhl fuer Thermische Verfahrenstechnik, Technische Universitaet Kaiserslautern (Germany); Detemple, P.; Schmitt, S.; Hessel, V. [Institut fuer Mikrotechnik Mainz GmbH, Mainz (Germany); Faqir, N. [University of Jordan, Amman (Jordan); Bart, H.J.

    2009-01-15

    Thin, defect-free palladium, palladium/copper and palladium/silver hydrogen absorbing membranes were microfabricated. A dual sputtering technique was used to deposit the palladium alloy membranes of only 1 {mu}m thickness on a nonporous silicon substrate. Advanced silicon etching (ASE) was applied on the backside to create a mechanically stable support structure for the thin films. Performance evaluation was carried out for different gases in a temperature range of 20 C to 298 C at a constant differential pressure of 110 kPa at the two sides of the membrane. The composite membranes show an excellent permeation rate of hydrogen, which appears to be 0.05 Pa m{sup 3} s{sup -1} and 0.01.10{sup -3} Pa m{sup 3} s{sup -1} at 20 C for the microfabricated 23 % silver and the 53 % copper composite membranes, respectively. The selectivity to hydrogen over a gas mixture containing, in addition to hydrogen, carbon monoxide, carbon dioxide and nitrogen was measured. The mass spectrometer did not detect any CO{sub 2} or CO, showing that the membrane is completely hydrogen selective. The microfabricated membranes exhibit both high mechanical strength (they easily withstand pressures up to 4 bar) and high thermal stability (up to 650 C). (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  20. Possibilities of hydrogen removal

    International Nuclear Information System (INIS)

    Langer, G.; Koehling, A.; Nikodem, H.

    1982-12-01

    In the event of hypothetical severe accidents in light-water reactors, considerable amounts of hydrogen may be produced and released into the containment. Combustion of the hydrogen may jeopardize the integrity of the containment. The study reported here aimed to identify methods to mitigate the hydrogen problem. These methods should either prevent hydrogen combustion, or limit its effects. The following methods have been investigated: pre-inerting; chemical oxygen absorption; removal of oxygen by combustion; post-inerting with N 2 , CO 2 , or halon; aqueous foam; water fog; deliberate ignition; containment purging; and containment venting. The present state of the art in both nuclear and non-nuclear facilities, has been identified. The assessment of the methods was based on accident scenarios assuming significant release of hydrogen and the spectrum of requirements derived from these scenarios was used to determine the advantages and drawbacks of the various methods, assuming their application in a pressurized-water reactor of German design. (orig.) [de

  1. Saga of hydrogen civilization

    Energy Technology Data Exchange (ETDEWEB)

    Veziroglu, T.N. [Univ. of Miami, Coral Gables, FL (United States). Clean Energy Research Institute

    2008-09-30

    In the 1960s, air pollution in cities became an important issue hurting the health of people. The author became interested in environmental issues in general and air pollution in particular. He started studying possible vehicle fuels, with a view of determining the fuel which would cause little or no pollution. He particularly studied methanol, ethanol, ammonia and hydrogen as well as the gasohols (i.e., the mixtures of gasoline and methanol and/or ethanol). His investigation of fuels for transportation lasted five years (1967-1972). The result was that hydrogen is the cleanest fuel, and it is also the most efficient one. It would not produce CO (carbon monoxide), CO{sub 2} (carbon dioxide), SO{sub x}, hydrocarbons, soot and particulates. If hydrogen was burned in oxygen, it would not produce NO{sub x} either. If it burned in air, there would then be some NO{sub x} produced. Since the author has always believed that engineers and scientists should strive to find solutions to the problems facing humankind and the world, he established the Clean Energy Research Institute (CERI) at the University of Miami in 1973. The mission of the Institute was to find a solution or solutions to the energy problem, so the world economy can function properly and provide humankind with high living standards. To find clean forms of energy was also the mission of the Institute, so that they would not produce pollution and damage the health of flora, fauna and humans, as well as the environment of the planet Earth as a whole. CERI looked at all of the possible primary energy sources, including solar, wind, currents, waves, tides, geothermal, nuclear breeders and thermonuclear. Although they are much cleaner and would last much longer than fossil fuels, these sources were not practical for use. They were not storable or transportable by themselves, except nuclear. They could not be used as a fuel for transportation by themselves, except nuclear for marine transportation. In order to solve

  2. Grain Yield Observations Constrain Cropland CO2 Fluxes Over Europe

    Science.gov (United States)

    Combe, M.; de Wit, A. J. W.; Vilà-Guerau de Arellano, J.; van der Molen, M. K.; Magliulo, V.; Peters, W.

    2017-12-01

    Carbon exchange over croplands plays an important role in the European carbon cycle over daily to seasonal time scales. A better description of this exchange in terrestrial biosphere models—most of which currently treat crops as unmanaged grasslands—is needed to improve atmospheric CO2 simulations. In the framework we present here, we model gross European cropland CO2 fluxes with a crop growth model constrained by grain yield observations. Our approach follows a two-step procedure. In the first step, we calculate day-to-day crop carbon fluxes and pools with the WOrld FOod STudies (WOFOST) model. A scaling factor of crop growth is optimized regionally by minimizing the final grain carbon pool difference to crop yield observations from the Statistical Office of the European Union. In a second step, we re-run our WOFOST model for the full European 25 × 25 km gridded domain using the optimized scaling factors. We combine our optimized crop CO2 fluxes with a simple soil respiration model to obtain the net cropland CO2 exchange. We assess our model's ability to represent cropland CO2 exchange using 40 years of observations at seven European FluxNet sites and compare it with carbon fluxes produced by a typical terrestrial biosphere model. We conclude that our new model framework provides a more realistic and strongly observation-driven estimate of carbon exchange over European croplands. Its products will be made available to the scientific community through the ICOS Carbon Portal and serve as a new cropland component in the CarbonTracker Europe inverse model.

  3. Hydrogen Fueling Station in Honolulu, Hawaii Feasibility Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Porter Hill; Michael Penev

    2014-08-01

    The Department of Energy Hydrogen & Fuel Cells Program Plan (September 2011) identifies the use of hydrogen for government and fleet electric vehicles as a key step for achieving “reduced greenhouse gas emissions; reduced oil consumption; expanded use of renewable power …; highly efficient energy conversion; fuel flexibility …; reduced air pollution; and highly reliable grid-support.” This report synthesizes several pieces of existing information that can inform a decision regarding the viability of deploying a hydrogen (H2) fueling station at the Fort Armstrong site in Honolulu, Hawaii.

  4. Carbon-constrained scenarios. Final report

    International Nuclear Information System (INIS)

    2009-05-01

    This report provides the results of the study entitled 'Carbon-Constrained Scenarios' that was funded by FONDDRI from 2004 to 2008. The study was achieved in four steps: (i) Investigating the stakes of a strong carbon constraint for the industries participating in the study, not only looking at the internal decarbonization potential of each industry but also exploring the potential shifts of the demand for industrial products. (ii) Developing an hybrid modelling platform based on a tight dialog between the sectoral energy model POLES and the macro-economic model IMACLIM-R, in order to achieve a consistent assessment of the consequences of an economy-wide carbon constraint on energy-intensive industrial sectors, while taking into account technical constraints, barriers to the deployment of new technologies and general economic equilibrium effects. (iii) Producing several scenarios up to 2050 with different sets of hypotheses concerning the driving factors for emissions - in particular the development styles. (iv) Establishing an iterative dialog between researchers and industry representatives on the results of the scenarios so as to improve them, but also to facilitate the understanding and the appropriate use of these results by the industrial partners. This report provides the results of the different scenarios computed in the course of the project. It is a partial synthesis of the work that has been accomplished and of the numerous exchanges that this study has induced between modellers and stakeholders. The first part was written in April 2007 and describes the first reference scenario and the first mitigation scenario designed to achieve stabilization at 450 ppm CO 2 at the end of the 21. century. This scenario has been called 'mimetic' because it has been build on the assumption that the ambitious climate policy would coexist with a progressive convergence of development paths toward the current paradigm of industrialized countries: urban sprawl, general

  5. Rupture mechanics of metallic alloys for hydrogen transport

    International Nuclear Information System (INIS)

    Moro, I.; Briottet, L.; Lemoine, P.; Andrieu, E.; Blanc, C.

    2007-01-01

    With the aim to establish a cheap hydrogen distribution system, the transport by pipelines is a solution particularly interesting. Among the high limit of elasticity steels, the X80 has been chosen for hydrogen transport. Its chemical composition and microstructure are given. Important microstructural changes have been revealed in the sheet thickness: the microstructure is thinner and richer in perlite in surface than in bulk. In parallel to this microstructural evolution, a microhardness gradient has been observed: the material microhardness is stronger in surface than in bulk of the sheet. The use of this material for hydrogen transport requires to study its resistance to hydrogen embrittlement. The main aim of this work is to develop an easy rupture mechanics test allowing to qualify the studied material in a gaseous hydrogen environment, to determine the sensitivity of the studied material to the hydrogen embrittlement and to better understand the mechanisms of the hydrogen embrittlement for ferritic materials. Two experimental tests have been used for: the first one is a traction machine coupled to an autoclave; the second one allows to carry out disk rupture tests. The toughness of the material in a gaseous hydrogen environment has thus been determined. The resistance of the material to hydrogen embrittlement has been characterized and by simulation, it has been possible to identify the areas with a strong concentration in hydrogen. The second aim of this work is to study the influence of the steel microstructure on the hydrogen position in the material and on the resistance of the material to the hydrogen embrittlement. The preferential trapping sites on the material not mechanically loaded have at first been identified, as well as the hydrogen position on the different phases and at the ferrite/cementite interface. The interaction between the mechanical loads, the position and the trapping of the hydrogen have been studied then. At last, has been

  6. Depth profiling of hydrogen in ferritic/martensitic steels by means of a tritium imaging plate technique

    International Nuclear Information System (INIS)

    Otsuka, Teppei; Tanabe, Tetsuo

    2013-01-01

    Highlights: ► We applied a tritium imaging plate technique to depth profiling of hydrogen in bulk. ► Changes of hydrogen depth profiles in the steel by thermal annealing were examined. ► We proposed a release model of plasma-loaded hydrogen in the steel. ► Hydrogen is trapped at trapping sites newly developed by plasma loading. ► Hydrogen is also trapped at surface oxides and hardly desorbed by thermal annealing. -- Abstract: In order to understand how hydrogen loaded by plasma in F82H is removed by annealing at elevated temperatures in vacuum, depth profiles of plasma-loaded hydrogen were examined by means of a tritium imaging plate technique. Owing to large hydrogen diffusion coefficients in F82H, the plasma-loaded hydrogen easily penetrates into a deeper region becoming solute hydrogen and desorbs by thermal annealing in vacuum. However the plasma-loading creates new hydrogen trapping sites having larger trapping energy than that for the intrinsic sites beyond the projected range of the loaded hydrogen. Some surface oxides also trap an appreciable amount of hydrogen which is more difficult to remove by the thermal annealing

  7. Changes in mechanical properties following cyclic prestressing of martensitic steel containing vanadium carbide in presence of nondiffusible hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Kaneko, Mao; Doshida, Tomoki [Graduate School of Science and Technology, Sophia University, Tokyo 102-8554 (Japan); Takai, Kenichi, E-mail: takai@me.sophia.ac.jp [Department of Engineering and Applied Science, Sophia University, Tokyo 102-8554 (Japan)

    2016-09-30

    Changes in the states of nondiffusible hydrogen and mechanical properties after cyclic prestressing in the presence of only nondiffusible hydrogen were examined for martensitic steel containing vanadium carbide. The relationship between the change in the state of nondiffusible hydrogen and mechanical properties was also investigated. The hydrogen desorption profile in the high-temperature range decreased and that in the low-temperature range increased with increasing stress amplitude during cyclic prestressing in the presence of only nondiffusible hydrogen. Thus, the application of cyclic prestressing changed the state of hydrogen from a stable to an unstable one because of vacancies and their clusters. Hydrogen embrittlement susceptibility after cyclic prestressing increased with increasing stress amplitude and number of prestressing cycles in the presence of only nondiffusible hydrogen. This relationship indicates that hydrogen embrittlement susceptibility increased with the increasing amount of hydrogen detrapped from trap sites of nondiffusible hydrogen during cyclic prestressing. These results revealed that nondiffusible hydrogen easily detrapped from vanadium carbide due to the application of cyclic prestress and probably interacted with vacancies and their clusters, thus increasing hydrogen embrittlement susceptibility. The change of nondiffusible hydrogen to diffusible hydrogen and accumulation of vacancies and their clusters during cyclic prestressing are concluded to be the dominant factors in hydrogen embrittlement after the application of cyclic prestress.

  8. FXR agonist activity of conformationally constrained analogs of GW 4064.

    Science.gov (United States)

    Akwabi-Ameyaw, Adwoa; Bass, Jonathan Y; Caldwell, Richard D; Caravella, Justin A; Chen, Lihong; Creech, Katrina L; Deaton, David N; Madauss, Kevin P; Marr, Harry B; McFadyen, Robert B; Miller, Aaron B; Navas, Frank; Parks, Derek J; Spearing, Paul K; Todd, Dan; Williams, Shawn P; Bruce Wisely, G

    2009-08-15

    Two series of conformationally constrained analogs of the FXR agonist GW 4064 1 were prepared. Replacement of the metabolically labile stilbene with either benzothiophene or naphthalene rings led to the identification of potent full agonists 2a and 2g.

  9. Automated Precision Maneuvering and Landing in Extreme and Constrained Environments

    Data.gov (United States)

    National Aeronautics and Space Administration — Autonomous, precise maneuvering and landing in extreme and constrained environments is a key enabler for future NASA missions. Missions to map the interior of a...

  10. Security constrained optimal power flow by modern optimization tools

    African Journals Online (AJOL)

    Security constrained optimal power flow by modern optimization tools. ... International Journal of Engineering, Science and Technology ... If you would like more information about how to print, save, and work with PDFs, Highwire Press ...

  11. Affine Lie algebraic origin of constrained KP hierarchies

    International Nuclear Information System (INIS)

    Aratyn, H.; Gomes, J.F.; Zimerman, A.H.

    1994-07-01

    It is presented an affine sl(n+1) algebraic construction of the basic constrained KP hierarchy. This hierarchy is analyzed using two approaches, namely linear matrix eigenvalue problem on hermitian symmetric space and constrained KP Lax formulation and we show that these approaches are equivalent. The model is recognized to be generalized non-linear Schroedinger (GNLS) hierarchy and it is used as a building block for a new class of constrained KP hierarchies. These constrained KP hierarchies are connected via similarity-Backlund transformations and interpolate between GNLS and multi-boson KP-Toda hierarchies. The construction uncovers origin of the Toda lattice structure behind the latter hierarchy. (author). 23 refs

  12. Slow logarithmic relaxation in models with hierarchically constrained dynamics

    OpenAIRE

    Brey, J. J.; Prados, A.

    2000-01-01

    A general kind of models with hierarchically constrained dynamics is shown to exhibit logarithmic anomalous relaxation, similarly to a variety of complex strongly interacting materials. The logarithmic behavior describes most of the decay of the response function.

  13. Synthesis of conformationally constrained peptidomimetics using multicomponent reactions

    NARCIS (Netherlands)

    Scheffelaar, R.; Klein Nijenhuis, R.A.; Paravidino, M.; Lutz, M.; Spek, A.L.; Ehlers, A.W.; de Kanter, F.J.J.; Groen, M.B.; Orru, R.V.A.; Ruijter, E.

    2009-01-01

    A novel modular synthetic approach toward constrained peptidomimetics is reported. The approach involves a highly efficient three-step sequence including two multicomponent reactions, thus allowing unprecedented diversification of both the peptide moieties and the turn-inducing scaffold. The

  14. Filter Pattern Search Algorithms for Mixed Variable Constrained Optimization Problems

    National Research Council Canada - National Science Library

    Abramson, Mark A; Audet, Charles; Dennis, Jr, J. E

    2004-01-01

    .... This class combines and extends the Audet-Dennis Generalized Pattern Search (GPS) algorithms for bound constrained mixed variable optimization, and their GPS-filter algorithms for general nonlinear constraints...

  15. Capacity Constrained Routing Algorithms for Evacuation Route Planning

    National Research Council Canada - National Science Library

    Lu, Qingsong; George, Betsy; Shekhar, Shashi

    2006-01-01

    .... In this paper, we propose a new approach, namely a capacity constrained routing planner which models capacity as a time series and generalizes shortest path algorithms to incorporate capacity constraints...

  16. Site Features

    Data.gov (United States)

    U.S. Environmental Protection Agency — This dataset consists of various site features from multiple Superfund sites in U.S. EPA Region 8. These data were acquired from multiple sources at different times...

  17. Analysis of combined hydrogen, heat, and power as a bridge to a hydrogen transition.

    Energy Technology Data Exchange (ETDEWEB)

    Mahalik, M.; Stephan, C. (Decision and Information Sciences)

    2011-01-18

    Combined hydrogen, heat, and power (CHHP) technology is envisioned as a means to providing heat and electricity, generated on-site, to large end users, such as hospitals, hotels, and distribution centers, while simultaneously producing hydrogen as a by-product. The hydrogen can be stored for later conversion to electricity, used on-site (e.g., in forklifts), or dispensed to hydrogen-powered vehicles. Argonne has developed a complex-adaptive-system model, H2CAS, to simulate how vehicles and infrastructure can evolve in a transition to hydrogen. This study applies the H2CAS model to examine how CHHP technology can be used to aid the transition to hydrogen. It does not attempt to predict the future or provide one forecast of system development. Rather, the purpose of the model is to understand how the system works. The model uses a 50- by 100-mile rectangular grid of 1-square-mile cells centered on the Los Angeles metropolitan area. The major expressways are incorporated into the model, and local streets are considered to be ubiquitous, except where there are natural barriers. The model has two types of agents. Driver agents are characterized by a number of parameters: home and job locations, income, various types of 'personalities' reflective of marketing distinctions (e.g., innovators, early adopters), willingness to spend extra money on 'green' vehicles, etc. At the beginning of the simulations, almost all driver agents own conventional vehicles. They drive around the metropolitan area, commuting to and from work and traveling to various other destinations. As they do so, they observe the presence or absence of facilities selling hydrogen. If they find such facilities conveniently located along their routes, they are motivated to purchase a hydrogen-powered vehicle when it becomes time to replace their present vehicle. Conversely, if they find that they would be inconvenienced by having to purchase hydrogen earlier than necessary or if they

  18. Hydrogen in energy transition

    International Nuclear Information System (INIS)

    2016-02-01

    This publication proposes a rather brief overview of challenges related to the use of hydrogen as an energy vector in the fields of transports and of energy storage to valorise renewable energies. Processes (steam reforming of natural gas or bio-gas, alkaline or membrane electrolysis, biological production), installation types (centralised or decentralised), raw materials and/or energy (natural gas, water, bio-gas, electricity, light), and their respective industrial maturity are indicated. The role of hydrogen to de-carbonate different types of transports is described (complementary energy for internal combustion as well as electrical vehicles) as well as its role in the valorisation and integration of renewable energies. The main challenges faced by the hydrogen sector are identified and discussed, and actions undertaken by the ADEME are indicated

  19. Constrained multi-degree reduction with respect to Jacobi norms

    KAUST Repository

    Ait-Haddou, Rachid; Barton, Michael

    2015-01-01

    We show that a weighted least squares approximation of Bézier coefficients with factored Hahn weights provides the best constrained polynomial degree reduction with respect to the Jacobi L2L2-norm. This result affords generalizations to many previous findings in the field of polynomial degree reduction. A solution method to the constrained multi-degree reduction with respect to the Jacobi L2L2-norm is presented.

  20. Clustering Using Boosted Constrained k-Means Algorithm

    Directory of Open Access Journals (Sweden)

    Masayuki Okabe

    2018-03-01

    Full Text Available This article proposes a constrained clustering algorithm with competitive performance and less computation time to the state-of-the-art methods, which consists of a constrained k-means algorithm enhanced by the boosting principle. Constrained k-means clustering using constraints as background knowledge, although easy to implement and quick, has insufficient performance compared with metric learning-based methods. Since it simply adds a function into the data assignment process of the k-means algorithm to check for constraint violations, it often exploits only a small number of constraints. Metric learning-based methods, which exploit constraints to create a new metric for data similarity, have shown promising results although the methods proposed so far are often slow depending on the amount of data or number of feature dimensions. We present a method that exploits the advantages of the constrained k-means and metric learning approaches. It incorporates a mechanism for accepting constraint priorities and a metric learning framework based on the boosting principle into a constrained k-means algorithm. In the framework, a metric is learned in the form of a kernel matrix that integrates weak cluster hypotheses produced by the constrained k-means algorithm, which works as a weak learner under the boosting principle. Experimental results for 12 data sets from 3 data sources demonstrated that our method has performance competitive to those of state-of-the-art constrained clustering methods for most data sets and that it takes much less computation time. Experimental evaluation demonstrated the effectiveness of controlling the constraint priorities by using the boosting principle and that our constrained k-means algorithm functions correctly as a weak learner of boosting.

  1. New Exact Penalty Functions for Nonlinear Constrained Optimization Problems

    Directory of Open Access Journals (Sweden)

    Bingzhuang Liu

    2014-01-01

    Full Text Available For two kinds of nonlinear constrained optimization problems, we propose two simple penalty functions, respectively, by augmenting the dimension of the primal problem with a variable that controls the weight of the penalty terms. Both of the penalty functions enjoy improved smoothness. Under mild conditions, it can be proved that our penalty functions are both exact in the sense that local minimizers of the associated penalty problem are precisely the local minimizers of the original constrained problem.

  2. Constrained multi-degree reduction with respect to Jacobi norms

    KAUST Repository

    Ait-Haddou, Rachid

    2015-12-31

    We show that a weighted least squares approximation of Bézier coefficients with factored Hahn weights provides the best constrained polynomial degree reduction with respect to the Jacobi L2L2-norm. This result affords generalizations to many previous findings in the field of polynomial degree reduction. A solution method to the constrained multi-degree reduction with respect to the Jacobi L2L2-norm is presented.

  3. Hydrogen vehicle fueling station

    Energy Technology Data Exchange (ETDEWEB)

    Daney, D.E.; Edeskuty, F.J.; Daugherty, M.A. [Los Alamos National Lab., NM (United States)] [and others

    1995-09-01

    Hydrogen fueling stations are an essential element in the practical application of hydrogen as a vehicle fuel, and a number of issues such as safety, efficiency, design, and operating procedures can only be accurately addressed by a practical demonstration. Regardless of whether the vehicle is powered by an internal combustion engine or fuel cell, or whether the vehicle has a liquid or gaseous fuel tank, the fueling station is a critical technology which is the link between the local storage facility and the vehicle. Because most merchant hydrogen delivered in the US today (and in the near future) is in liquid form due to the overall economics of production and delivery, we believe a practical refueling station should be designed to receive liquid. Systems studies confirm this assumption for stations fueling up to about 300 vehicles. Our fueling station, aimed at refueling fleet vehicles, will receive hydrogen as a liquid and dispense it as either liquid, high pressure gas, or low pressure gas. Thus, it can refuel any of the three types of tanks proposed for hydrogen-powered vehicles -- liquid, gaseous, or hydride. The paper discusses the fueling station design. Results of a numerical model of liquid hydrogen vehicle tank filling, with emphasis on no vent filling, are presented to illustrate the usefulness of the model as a design tool. Results of our vehicle performance model illustrate our thesis that it is too early to judge what the preferred method of on-board vehicle fuel storage will be in practice -- thus our decision to accommodate all three methods.

  4. Hydrogen: Fueling the Future

    International Nuclear Information System (INIS)

    Leisch, Jennifer

    2007-01-01

    As our dependence on foreign oil increases and concerns about global climate change rise, the need to develop sustainable energy technologies is becoming increasingly significant. Worldwide energy consumption is expected to double by the year 2050, as will carbon emissions along with it. This increase in emissions is a product of an ever-increasing demand for energy, and a corresponding rise in the combustion of carbon containing fossil fuels such as coal, petroleum, and natural gas. Undisputable scientific evidence indicates significant changes in the global climate have occurred in recent years. Impacts of climate change and the resulting atmospheric warming are extensive, and know no political or geographic boundaries. These far-reaching effects will be manifested as environmental, economic, socioeconomic, and geopolitical issues. Offsetting the projected increase in fossil energy use with renewable energy production will require large increases in renewable energy systems, as well as the ability to store and transport clean domestic fuels. Storage and transport of electricity generated from intermittent resources such as wind and solar is central to the widespread use of renewable energy technologies. Hydrogen created from water electrolysis is an option for energy storage and transport, and represents a pollution-free source of fuel when generated using renewable electricity. The conversion of chemical to electrical energy using fuel cells provides a high efficiency, carbon-free power source. Hydrogen serves to blur the line between stationary and mobile power applications, as it can be used as both a transportation fuel and for stationary electricity generation, with the possibility of a distributed generation energy infrastructure. Hydrogen and fuel cell technologies will be presented as possible pollution-free solutions to present and future energy concerns. Recent hydrogen-related research at SLAC in hydrogen production, fuel cell catalysis, and hydrogen

  5. Hydrogen production from microbial strains

    Science.gov (United States)

    Harwood, Caroline S; Rey, Federico E

    2012-09-18

    The present invention is directed to a method of screening microbe strains capable of generating hydrogen. This method involves inoculating one or more microbes in a sample containing cell culture medium to form an inoculated culture medium. The inoculated culture medium is then incubated under hydrogen producing conditions. Once incubating causes the inoculated culture medium to produce hydrogen, microbes in the culture medium are identified as candidate microbe strains capable of generating hydrogen. Methods of producing hydrogen using one or more of the microbial strains identified as well as the hydrogen producing strains themselves are also disclosed.

  6. Investigation of nanocrystalline Gd films loaded with hydrogen

    KAUST Repository

    Hruška, Petr; Čí žek, Jakub; Dobroň, Patrik; Anwand, Wolfgang; Mü cklich, Arndt; Gemma, Ryota; Wagner, Stefan; Uchida, Helmut; Pundt, Astrid

    2015-01-01

    The present work reports on microstructure studies of hydrogen-loaded nanocrystalline Gd films prepared by cold cathode beam sputtering on sapphire (112¯0) substrates. The Gd films were electrochemically step-by-step charged with hydrogen and the structural development with increasing concentration of absorbed hydrogen was studied by transmission electron microscopy and in-situ   X-ray diffraction using synchrotron radiation. The relaxation of hydrogen-induced stresses was examined by acoustic emission measurements. In the low concentration range absorbed hydrogen occupies preferentially vacancy-like defects at GBs typical for nanocrystalline films. With increasing hydrogen concentration hydrogen starts to occupy interstitial sites. At the solid solution limit the grains gradually transform into the ββ-phase (GdH2). Finally at high hydrogen concentrations xH>2.0xH>2.0 H/Gd, the film structure becomes almost completely amorphous. Contrary to bulk Gd specimens, the formation of the γγ-phase (GdH3) was not observed in this work.

  7. Container for hydrogen isotopes

    Energy Technology Data Exchange (ETDEWEB)

    1976-01-12

    A container is described for storage, shipping and and dispensing of hydrogen isotopes such as hydrogen, deuterium, tritium, or mixtures of the same. The container is compact, safe against fracture or accident, and is reusable. It consists of an outer housing with suitable inlet and outlet openings and electrical feed elements, the housing containing an activated sorber material in the form, for example of titanium sponge or an activated zirconium aluminate cartridge. The gas to be stored is introduced into the chamber under conditions of heat and vacuum and is retained in the sorber material. Subsequently, it may be released by heating the unit to drive off the stored gas at desired rates.

  8. Hydrogen bonded supramolecular materials

    CERN Document Server

    Li, Zhan-Ting

    2015-01-01

    This book is an up-to-date text covering topics in utilizing hydrogen bonding for constructing functional architectures and supramolecular materials. The first chapter addresses the control of photo-induced electron and energy transfer. The second chapter summarizes the formation of nano-porous materials. The following two chapters introduce self-assembled gels, many of which exhibit unique functions. Other chapters cover the advances in supramolecular liquid crystals and the versatility of hydrogen bonding in tuning/improving the properties and performance of materials. This book is designed

  9. Electrocatalysts for hydrogen energy

    CERN Document Server

    Losiewicz, Bozena

    2015-01-01

    This special topic volume deals with the development of novel solid state electrocatalysts of a high performance to enhance the rates of the hydrogen or oxygen evolution. It contains a description of various types of metals, alloys and composites which have been obtained using electrodeposition in aqueous solutions that has been identified to be a technologically feasible and economically superior technique for the production of the porous electrodes. The goal was to produce papers that would be useful to both the novice and the expert in hydrogen technologies. This volume is intended to be us

  10. Magnesium for Hydrogen Storage

    DEFF Research Database (Denmark)

    Pedersen, Allan Schrøder; Kjøller, John; Larsen, B.

    1983-01-01

    A study of the hydrogenation characteristics of fine magnesium powder during repeated cycling has been performed using a high-pressure microbalance facility. No effect was found from the cycling regarding kinetics and storage capacity. The reaction rate of the absorption process was fast...... at temperatures around 600 K and above, but the reversed reaction showed somewhat slower kinetics around 600 K. At higher temperatures the opposite was found. The enthalpy and entropy change by the hydrogenation, derived from pressure-concentration isotherms, agree fairly well with those reported earlier....

  11. Hydrogen production from hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Docekal, J

    1986-01-01

    Hydrogen is an important feed stock for chemical and petroleum industries, in addition to being considered as the energy carrier of the future. At the present time the feed stock hydrogen is mainly manufactured from hydrocarbons using steam reforming. In steam reforming two processes are employed, the conventional process and PSA (pressure swing adsorption) process. These two processes are described and compared. The results show that the total costs and the maintenance costs are lower for the PSA process, the capital outlay is lower for the conventional process, and the operating costs are similar for the two processes.

  12. Container for hydrogen isotopes

    International Nuclear Information System (INIS)

    1976-01-01

    A container is described for storage, shipping and and dispensing of hydrogen isotopes such as hydrogen, deuterium, tritium, or mixtures of the same. The container is compact, safe against fracture or accident, and is reusable. It consists of an outer housing with suitable inlet and outlet openings and electrical feed elements, the housing containing an activated sorber material in the form, for example of titanium sponge or an activated zirconium aluminate cartridge. The gas to be stored is introduced into the chamber under conditions of heat and vacuum and is retained in the sorber material. Subsequently, it may be released by heating the unit to drive off the stored gas at desired rates

  13. Free and constrained symplectic integrators for numerical general relativity

    International Nuclear Information System (INIS)

    Richter, Ronny; Lubich, Christian

    2008-01-01

    We consider symplectic time integrators in numerical general relativity and discuss both free and constrained evolution schemes. For free evolution of ADM-like equations we propose the use of the Stoermer-Verlet method, a standard symplectic integrator which here is explicit in the computationally expensive curvature terms. For the constrained evolution we give a formulation of the evolution equations that enforces the momentum constraints in a holonomically constrained Hamiltonian system and turns the Hamilton constraint function from a weak to a strong invariant of the system. This formulation permits the use of the constraint-preserving symplectic RATTLE integrator, a constrained version of the Stoermer-Verlet method. The behavior of the methods is illustrated on two effectively (1+1)-dimensional versions of Einstein's equations, which allow us to investigate a perturbed Minkowski problem and the Schwarzschild spacetime. We compare symplectic and non-symplectic integrators for free evolution, showing very different numerical behavior for nearly-conserved quantities in the perturbed Minkowski problem. Further we compare free and constrained evolution, demonstrating in our examples that enforcing the momentum constraints can turn an unstable free evolution into a stable constrained evolution. This is demonstrated in the stabilization of a perturbed Minkowski problem with Dirac gauge, and in the suppression of the propagation of boundary instabilities into the interior of the domain in Schwarzschild spacetime

  14. A Lean Framework for Production Control in Complex and Constrained Construction Projects (PC4P)

    DEFF Research Database (Denmark)

    Lindhard, Søren Munch; Wandahl, Søren

    2014-01-01

    Production conditions in construction are different than in themanufacturing industry. First of all, construction is rooted in place and conducted as on-site manufacturing. Secondly, every construction project is unique and a one-of-a-kind production, managed by a temporary organization consisting...... and constrained construction project. Even though several tools have attempted to add structure and to create order, to the complex, dynamic, and uncertain context in which constructions is conducted, none has yet fully succeeded in providing a robust production control system. With outset in the lean tool Last...

  15. SITE-94. Radionuclide solubilities for SITE-94

    Energy Technology Data Exchange (ETDEWEB)

    Arthur, R.; Apted, M. [QuantiSci, Denver, CO (United States)

    1996-12-01

    In this report, solubility constraints are evaluated on radioelement source-term concentrations supporting the SITE-94 performance assessment. Solubility models are based on heterogeneous-equilibrium, mass- and charge-balance constraints incorporated into the EQ3/6 geochemical software package, which is used to calculate the aqueous speciation behavior and solubilities of U, Th, Pu, Np, Am, Ni, Ra, Se, Sn, Sr, Tc and Zr in site groundwaters and near-field solutions. The chemical evolution of the near field is approximated using EQ3/6 in terms of limiting conditions at equilibrium, or steady state, in three closed systems representing fully saturated bentonite, Fe{sup o} corrosion products of the canister, and spent fuel. The calculations consider both low-temperature (15 deg C) and high-temperature (80 deg C) conditions in the near field, and the existence of either reducing or strongly oxidizing conditions in each of the bentonite, canister, and spent-fuel barriers. Heterogeneities in site characteristics are evaluated through consideration of a range of initial groundwaters and their interactions with engineered barriers. Aqueous speciation models for many radioelements are constrained by thermodynamic data that are estimated with varying degrees of accuracy. An important question, however, is how accurate do these models need to be for purposes of estimating source-term concentrations? For example, it is unrealistic to expect a high degree of accuracy in speciation models if such models predict solubilities that are below the analytical detection limit for a given radioelement. From a practical standpoint, such models are irrelevant if calculated solubilities cannot be tested by direct comparison to experimental data. In the absence of models that are both accurate and relevant for conditions of interest, the detection limit could define a pragmatic upper limit on radioelement solubility 56 refs, 25 tabs, 10 figs

  16. SITE-94. Radionuclide solubilities for SITE-94

    International Nuclear Information System (INIS)

    Arthur, R.; Apted, M.

    1996-12-01

    In this report, solubility constraints are evaluated on radioelement source-term concentrations supporting the SITE-94 performance assessment. Solubility models are based on heterogeneous-equilibrium, mass- and charge-balance constraints incorporated into the EQ3/6 geochemical software package, which is used to calculate the aqueous speciation behavior and solubilities of U, Th, Pu, Np, Am, Ni, Ra, Se, Sn, Sr, Tc and Zr in site groundwaters and near-field solutions. The chemical evolution of the near field is approximated using EQ3/6 in terms of limiting conditions at equilibrium, or steady state, in three closed systems representing fully saturated bentonite, Fe o corrosion products of the canister, and spent fuel. The calculations consider both low-temperature (15 deg C) and high-temperature (80 deg C) conditions in the near field, and the existence of either reducing or strongly oxidizing conditions in each of the bentonite, canister, and spent-fuel barriers. Heterogeneities in site characteristics are evaluated through consideration of a range of initial groundwaters and their interactions with engineered barriers. Aqueous speciation models for many radioelements are constrained by thermodynamic data that are estimated with varying degrees of accuracy. An important question, however, is how accurate do these models need to be for purposes of estimating source-term concentrations? For example, it is unrealistic to expect a high degree of accuracy in speciation models if such models predict solubilities that are below the analytical detection limit for a given radioelement. From a practical standpoint, such models are irrelevant if calculated solubilities cannot be tested by direct comparison to experimental data. In the absence of models that are both accurate and relevant for conditions of interest, the detection limit could define a pragmatic upper limit on radioelement solubility

  17. Site decontamination

    International Nuclear Information System (INIS)

    Bicker, A.E.

    1981-01-01

    Among the several DOE sites that have been radiologically decontaminated under the auspices of the Nevada Operations Office are three whose physical characteristics are unique. These are the Tatum Dome Test Site (TDTS) near Hattiesburg, Mississippi; a location of mountainous terrain (Pahute Mesa) on the Nevada Test Site; and the GNOME site near Carlsbad, New Mexico. In each case the contamination, the terrain, and the climate conditions were different. This presentation includes a brief description of each site, the methods used to perform radiological surveys, the logistics required to support the decontamination (including health physics and sample analysis), and the specific techniques used to reduce or remove the contamination

  18. Theoretical study of molecular hydrogen and spiltover hydrogen storage on two-dimensional covalent-organic frameworks

    International Nuclear Information System (INIS)

    Liu Xiu-Ying; He Jie; Yu Jing-Xin; Fan Zhi-Qin; Li Zheng-Xin

    2014-01-01

    Molecular hydrogen and spiltover hydrogen storages on five two-dimensional (2D) covalent-organic frameworks (COFs) (PPy-COF, TP-COF, BTP-COF, COF-18 Å, and HHTP-DPB COF) are investigated using the grand canonical Monte Carlo (GCMC) simulations and the density functional theory (DFT), respectively. The GCMC simulated results show that HHTP-DPB COF has the best performance for hydrogen storage, followed by BTP-COF, TP-COF, COF-18 Å, and PPy-COF. However, their adsorption amounts at room temperature are all too low to meet the uptake target set by US Department of Energy (US-DOE) and enable practical applications. The effects of pore size, surface area, and isosteric heat of hydrogen on adsorption amount are considered, which indicate that these three factors are all the important factors for determining the H 2 adsorption amount. The chemisorptions of spiltover hydrogen atoms on these five COFs represented by the cluster models are investigated using the DFT method. The saturation cluster models are constructed by considering all possible adsorption sites for these cluster models. The average binding energy of a hydrogen atom and the saturation hydrogen storage density are calculated. The large average binding energy indicates that the spillover process may proceed smoothly and reversibly. The saturation hydrogen storage density is much larger than the physisorption uptake of H 2 molecules at 298 K and 100 bar (1 bar = 10 5 Pa), and is close to or exceeds the 2010 US-DOE target of 6 wt% for hydrogen storage. This suggests that the hydrogen storage capacities of these COFs by spillover may be significantly enhanced. Thus 2D COFs studied in this paper are suitable hydrogen storage media by spillover

  19. Hydrogen isotope effect through Pd in hydrogen transport pipe

    International Nuclear Information System (INIS)

    Tamaki, Masayoshi

    1992-01-01

    This investigation concerns hydrogen system with hydrogen transport pipes for transportation, purification, isotope separation and storage of hydrogen and its isotopes. A principle of the hydrogen transport pipe (heat pipe having hydrogen transport function) was proposed. It is comprised of the heat pipe and palladium alloy tubes as inlet, outlet, and the separation membrane of hydrogen. The operation was as follows: (1) gas was introduced into the heat pipe through the membrane in the evaporator; (2) the introduced gas was transported toward the condenser by the vapor flow; (3) the transported gas was swept and compressed to the end of the condenser by the vapor pressure; and (4) the compressed gas was exhausted from the heat pipe through the membrane in the condenser. The characteristics of the hydrogen transport pipe were examined for various working conditions. Basic performance concerning transportation, evacuation and compression was experimentally verified. Isotopic dihydrogen gases (H 2 and D 2 ) were used as feed gas for examining the intrinsic performance of the isotope separation by the hydrogen transport pipe. A simulated experiment for hydrogen isotope separation was carried out using a hydrogen-helium gas mixture. The hydrogen transport pipe has a potential for isotope separation and purification of hydrogen, deuterium and tritium in fusion reactor technology. (author)

  20. Hydrogen Storage in Metal-Organic Frameworks

    Energy Technology Data Exchange (ETDEWEB)

    Long, Jeffrey R. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2016-04-28

    rigorous understanding of experimental findings was further achieved via first-principles electronic structure calculations, which also supported synthetic efforts through predictions of additional novel frameworks with promising properties for vehicular H2 storage. The results of the computational efforts also helped to elucidate the fundamental principles governing the interaction of H2 with the frameworks, and in particular with exposed metal sites in the pores of these materials. Significant accomplishments from this project include the discovery of a metal-organic framework with a high H2 binding enthalpy and volumetric capacity at 25 °C and 100 bar, which surpasses the metrics of any other known metal-organic framework. Additionally this material was designed to be extremely cost effective compared to most comparable adsorbents, which is imperative for eventual real-world applications. Progress toward synthesizing new frameworks containing multiple open coordination sites is also discussed, and appears to be the most promising future direction for hydrogen storage in these porous materials.